Antarctic Marine Biology

Transcription

Antarctic Marine Biology
The role of NSF in facilitation of antarctic marine biology,
ecology and oceanography.
MARINELLI, R.L.* and P.A. PENHALE. Antarctic Biology and
Medicine Program, National Science Foundation, Washington,
DC.
of UV-induced damage relative to trophic transfer and
biogeochemical cycling is the ultimate goal of current research
efforts.
The chemical ecology of antarctic marine organisms.
BAKER, B.J.*, J.B. MCCLINTOCK, and C D . AMSLER. Florida
Institute of Technology, Melbourne, and Univ. of Alabama at
Birmingham.
Few studies have examined the ecological function of
secondary metabolites produced by polar marine organisms. We
report that bioactive secondary metabolites occur in a wide
variety of antarctic marine organisms and play complex roles in
mediating patterns of predation and in preventing fouling on
surfaces. Chemical relationships of particular note among
antarctic organisms include sequestration of defensive
compounds in the most vulnerable body components, sponge
associated bacteria that produce bioactive metabolites,
chemically defended macroalgae that are carried by sea urchins
to serve as defense against urchin-consuming sea anemones,
sponge metabolites that cause tube-foot retractions in
spongivorous sea stars, and the abduction and carrying of a
chemically defended sea butterfly by an amphipod to provide
defense against fish predators. Patterns of high species
abundance and diversity are likely to have selected for
chemically mediated interactions in marine organisms. Our
studies reflect the potential for diverse chemistry and highlights
the need to preserve biodiversity among antarctic marine
organisms. Supported by the Office of Polar Programs (NSF).
Microbial dynamics and carbon flus in south ocean habitats.
BIRD, D. F.*, D. M. KARL, and E. F. DELONG. Univ. of Quebec at
Montreal, Canada, Univ. Hawaii, Honolulu and MBARI, Moss
Landing, CA.
Climate change and benthic community structure in
Antarctica.
ARONSON, R.B.* and D.B. BLAKE. Dauphin Island Sea Lab, AL
and Univ. of Illinois, Champaign-Urbana.
Microorganisms including eukaryotes Bacteria Archaea and
viruses are vital components of Southern Ocean habitats. They
are responsible for the production and decomposition of organic
matter for the primary uptake and regeneration of inorganic
nutrients and for export of carbon and energy to intermediate
ocean depths. Consequently field data both on individual groups
of microorganisms and on the complex interactions among them
are necessary for a complete assessment of the role of marine
microorganisms on both local and global environments. Recent
evidence suggests that Archaea represent a major portion of the
near surface microbial communities in Southern Ocean habitats
yet representative pure culture isolates do not exist. A dramatic
temporal decoupling between eukaryote photoautotrophy and
prokaryote heterotrophy has also been observed in Antarctic
coastal waters. Results from recent field measurements and
experiments provide new insights into the structure and function
of microbial food webs and the controls on population dynamics.
A new conceptual model that accommodates these observations
will be presented along with a research prospectus for the future.
Neontologists have long appreciated the archaic character of
shallow-water benthic faunas in Antarctica. Because skeletoncrushing (durophagous) fish and decapod crustaceans are
scarce, seastars and other slow-moving invertebrates are the
primary predators. Dense populations of epifaunal suspensionfeeders are common today in shallow, soft-bottom, antarctic
habitats, but at lower latitudes such populations were restricted
by predation to deep water in the Mesozoic and Cenozoic.
Climate change from the late Eocene onward was apparently
responsible for a permanent change in trophic structure in
Antarctica, when declining temperatures altered the geographic
and bathymetric ranges of predatory taxa. Brachyuran crabs, for
example, disappeared from shallow antarctic communities in the
late Eocene. The disruption of trophic linkages in Antarctica has
allowed retrograde ecologies to persist for the past 40 m.y.
Since cooling trends in temperate upwelling regions will likely
accompany ongoing global warming, understanding the
evolution of predator-prey relationships in Antarctica will help us
predict future patterns of species distribution and trophic
interaction.
Influence of ultraviolet light on antarctic marine organisms.
BOSCH, I.* AND D. KARENTZ. Univ. of San Francisco, CA and
State Univ. of New York, Geneseo.
Every spring for the past two decades, ozone depletion over
the Antarctic has resulted in increases in the amount of
ultraviolet B radiation (UVB, 280-320 nm) reaching terrestrial and
aquatic environments. Research on the UV-photobiology of
Antarctic organisms has focused on phytoplankton under the
assumption that ecosystem effects will most likely originate
through reductions in primary productivity. However, this may
not be the only significant aspect of ecosystem response to
elevated UVB. Invertebrates and fish, particularly early
developmental stages in the plankton, receive relatively high
doses of UVB. DNA damage, morphological aberrations and
lethality can be caused by ambient UVB exposure in shallow
water (<10 m) during ozone depletion events. The impact of such
direct effects on consumer populations is not yet known.
Understanding the balance between direct biological damage
and species-specific potentials for protection against and repair
2A
The Palmer LTER: Long-term ecological research on the
antarctic marine ecosystem.
SMITH, R.C. Univ. of California, Santa Barbara.
The ecosystem diversity of LTER sites includes tundra,
forests, grasslands, deserts, lakes & coastal & marine systems.
The Palmer LTER focuses on the assemblage of plants, animals,
ocean & sea ice within the shelf-slope waters of the western
Antarctic Peninsula (WAP)area. Our interdiscuplinary program
provides a stream of systematically collected ecological data
that is invaluable for detecting & understanding envrionmental
change over a range of scales from local to regional. Across
these scales, we are testing hypotheses linking physical forcing
to space/time integrated biological response. Within this
Southern Ocean ecosystem, the abundance & distribution of
phytoplankton production, as well as its contribution to global
biogeochemical processes, is poorly known relative to more
temperate marine ecosystems. Due to the vast remoteness of
this region, satellite data are essential to provide space/time
SOCIETY FOR INTEGRATIVE AND COMPARATIVE BIOLOGY
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The role of NSF in the US Antarctic Program was delineated
by a Presidential Memorandum in 1982. This document provided
a context in which to maintain and enhance access to some of
earth's most unusual environments and the organisms they
support. While many species with unique adaptations have been
discovered, there are vast areas of the Southern continent and
ocean that remain to be explored. Thus, it is likely that new taxa
with novel adaptations remain to be discovered. Increasingly,
research has revealed that Antarctica plays a significant role in
global change processes. These discoveries have led to the
development and support of sophisticated platforms to allow
interdisciplinary, process-oriented investigations of organisms
and biological processes in an environmental context, with the
goal of predicting how organisms will influence and respond to
global change. Much of the research on organisms and their
environment has been conducted in the austral summer, but little
is known of how organisms survive during winter. NSF is
studying the feasibility of providing access for the conduct of
biological research during winter.
coverage that would otherwise be unavailable. SeaWiFS ocean
color data, along with surface bio-optical observations, are being
used to provide estimates of both pigment biomass &
phytoplankton productivity for the WAP area.
Biogeochemical contributions of sea ice algae to antarctic
marine ecosystems.
LIZOTTE, M.P. Univ. of Wisconsin, Oshkosh.
10
Food web structure on the antarctic peninsula: del13C
analysis.
DUNTON, K.D. The Univ. of Texas at Austin, Port Aransas, TX.
Stable carbon isotope measurements (del 13C) were used to
assess the importance of macroalgal carbon (-14 to -18 ppt)
versus phytoplankton carbon (-26 to -29 ppt) to resident marine
fauna of the Antarctic Peninsula near Anvers Island (65° S).
Macroalgae were dominated by browns in the Desmarestiales,
including the kelp-like species Himantothallus grandifolius. There
was a clear dependence on macroalgal carbon by consumers;
animals that showed the greatest assimilation of brown algal
carbon included macroalgal herbivores (limpets, -15 to 18 ppt)
and omnivorous benthic feeders (polychaetes, nemerteans, sea
urchins and fishes, -18 to -22 ppt). Animals that incorporated the
least macroalgal carbon included selective suspension feeders
(bryozoans and hydroids, -25 to -27 ppt). Although various
crustaceans (eg. amphipods) had del 13 C values indicating an
intermediate dependence on kelp carbon, the del 13C values of
resident penguins (-23 to -25 ppt) reflected a strong
phytoplankton signature. In contrast, isotopic values of
epibenthic and benthic fauna clearly demonstrated the
assimilation of macroalgal carbon and the importance of these
benthic plants in Antarctic Peninsula food webs.
1J
8
Environmental variability and its impact on the reproductive
cycle of antarctic krill, Euphausia superba.
ROSS, R.M.* and L.B. QUETIN. University of California, Santa
Barbara.
For the past seven years the Palmer LTER has documented
the distribution and abundance of Antarctic krill (Euphausia
superba) and the salp Salpa thompsoni. Spawning frequency and
physiological maturity of Antarctic krill have also been
determined. Interannual variability in the spatial distribution
timing and intensity of spawning has been high. Two
mechanisms have been proposed to explain both interannual
variability in relative amounts of krill and salps and variation in
the krill reproductive cycle: early sea ice retreat leading to
abundant salp populations that outcompete krill populations for
limited food resources versus variability in the influence of the
oceanic water masses and their characteristic phytoplankton
communities. The existence of two long-term studies in the
region west of the Antarctic Peninsula allows us to examine the
effects of environmental variability on reproductive success in
Antarctic krill in two locations that differ in latitude shelf width
and oceanic influence. The Palmer LTER lies between Anvers
and Adelaide Islands (~ 66°°S) whereas the AMLR study region
lies at the tip of the Antarctic Peninsula (62~S).
Weddell seal versus Emperor penguin: Boss of the Ross Sea.
KOOYMAN, G.L. and J. BURNS*. Univ. of California, San Diego
and University of California, Santa Cruz.
Only two top predators live year round at high latitudes of
the Ross sea. They are the Weddell seal and emperor penguin.
The seasonal distribution, foraging depths, and diet of these two
species overlap. What makes it possible for these two species to
live and co-exist at these high latitudes through the winter while
other marine tetrapods apparently cannot? Some of the
adaptations for hypoxia that enable deep and prolonged diving
are similar in kind. So too perhaps are some of the adaptations
to pressure, light and temperature. Nevertheless, there is
probably little competition between the two species because of
differing physical abilities that result in the exploitation of
different local and regional habitats. In winter, for example, while
the female emperor penguin is ranging widely in the pack ice of
lower latitudes and the male is fasting while incubating the egg,
Weddell seals, including pregnant females, are foraging and
ABSTRACTS
Adaptive evolution of gene expression in antarctic fishes.
DETRICH, III, H.W. Northeastern Univ., Boston, MA.
The fishes of the Antarctic express their genomes in an
extremely cold thermal environment (-1.86 to +1 °C). To
determine the compensatory adjustments, if any, that adapt
transcription to low temperatures, we are studying the structure,
genomic organization, and expression of globin genes from an
Antarctic rockcod, Notothenia coriiceps (Nc), and from a
temperate relative, the New Zealand black cod N. angustata (Na).
The adult alpha- and beta-globin genes of these fishes are tightly
linked in head-to-head (5' to 5') orientation. When assayed in
MEL cells, the DNA sequences that separate the globin genes
(4.3 kb in Nc and 3.2 kb in Na) function as bidirectional,
erythroid-responsive promoters. However, the globin promoters
of Nc are 2-6 fold more active than are the Na promoters. The
greater activity of the Nc intergenic region appears to be due to
an expanded enhancer that contains multiple copies of an Sp-1
binding motif. We propose that efficient gene expression by
Antarctic fishes results in part from evolutionary restructuring of
c/s-acting gene regulatory elements.
12
Antarctic fishes are frozen, but are alive and well!
DEVRIES, A.L. Univ. of Illinois, Urbana.
Freezing avoidance in Antarctic fishes is associated with the
presence of antifreeze glycoproteins (AFGPs) and a recently
discovered AFGP potentiating protein. Together these antifreeze
proteins(APs)along with normal salt concentrations lower the
fishes' freezing points to -2.5 to-3oC, a temperature well below
the coldest ice-laden waters (-2oC) of the Southern Ocean.
Ocassionaly small ice crystals enter the fish and accumulate in
the spleen. Even though the water never warms above the
melting point of ice in their blood (-1oC), these splenic crystals
slowly disappear when the summer water warms slightly above
freezing. It is proposed that macrophages endocytose the AP
coated crystals and dissolve them in lysosomes. A correlation
between AP levels and the severity of their winter environment
exists with the Antarctic Peninsula fish species having about half
the AP level that the McMurdo Sound fishes do. The AFGP gene
appears to have evolved de novo about 12 million year ago from
their trypsinogen gene by amplifying a short repeat intronic
sequence. The estimate of time of origin agrees with time of
radiation of the Antarctic notothenioid fishes as well as with the
glacial-geological estimates of freezing of the Southern Ocean.
3A
The seasonally ice-covered regions of the Southern Ocean
have distinct biogeochemical features due to the growth of
microalgae in sea ice. Although sea ice microalgal production is
probably exceeded by phytoplankton production on an annual
basis, the blooms of sea ice algae differ considerably in terms of
timing and distribution. Thus sea ice algae provide food
resources for higher trophic level organisms in seasons and
regions where water column biological production is negligible.
The downward flux of biogenic material from sea ice algal
blooms may be rapid following ice melt, and some of the species
present are responsible for ensuing phytoplankton blooms. The
biogenic materials produced by sea ice algal blooms also carry
specific biogeochemical signatures due to the extreme
environmental conditions found in sea ice microenvironments.
These signatures may make it possible to trace food web
dynamics and benthic deposition to either sea ice or planktonic
primary production. The biogeochemical contribution of sea ice
algae in Antarctic marine ecosystems will be reviewed in terms
of production, chemical composition, isotopic fractionation,
sedimentation, and trophic interactions.
fattening for the summer fast, literally beneath the feet of the
male penguins.
Intermittent Locomotion: Integrating the
Physiology, Biomechanics of Repreated
Activity
13
The behavioral ecology of intermittent locomotion.
MCLAUGHLIN, R.L* and D.L KRAMER. McGill Univ., Montreal,
Canada, and Univ. of Guelph, Canada.
16
Transient and intermittent phenomena in aquatic locomotion.
DANIEL, T.L*, E.B. GOLDMAN, and S.A. COMBES. Univ. of
Washington, Seattle.
14
Intermittent movements in fluids generate stresses that
always exceed their steady-state equivalent. These increased
stresses arise from both inertial and viscous characteristics of
the fluid. Thus, there is an increased energetic cost associated
with intermittent propuslor motions, as well as whole body
accelerations. While such unsteady phenomena can lead to
greater energy requirements for movement, a trade-off emerges
from the coupling between mass flux and fluid flow: high
stresses coincide with high fluxes of dissolved or suspended
materials. Thus the coupling between fluid flow and mass flux
can also lead to an increased gas or nutrient transport. We
explore the energetic consequences of transient motions for a
variety of aquatic animals to understand this trade-off. We use
mathematical models and kinematic data to show how the
Reynolds number (ratio of inerital to viscous stresses), Strouhal
number (ratio of unsteady to steady movement), and Peclet
number (ratio of diffusive to convective fluxes) determine the
total energetic cost of transient motions. We show that there are
benefits to intermittent movement in fluids that arise from
coupled mass and momentum transport. (NSF grant IBN9511681).
Effects of dive depth, buoyancy, and propulsive mode on the
inertial work of swimming in birds.
LOWORN, J. R. Univ. of Wyoming, Laramie.
17
During vertical dives, wing-propelled auks maintained" almost
constant mean speed that minimized their drag coefficient.
Buoyant resistance changed with depth due to varying
compression of air spaces, so maintaining constant speed
required altering either stroke rate or work per stroke. Changes
in contraction speed decrease muscle efficiency, so altering
strokes without changing contraction speed is desirable. One
method is to vary glide duration. In wing (lift-based) propulsion,
another method is to vary thrust from the upstroke vs.
downstroke. In this way, similar mean speeds may be achieved
at lower drag by more evenly distributing thrust throughout
strokes, lowering instantaneous speed, and thus reducing drag
which increases rapidly with speed. In foot (drag-based)
propulsion, the 'upstroke' (retraction) generates only backward
thrust, making strokes more pulsatile. During descent, inertial
work from more pulsatile drag-based thrust is greater nearer the
surface where buoyancy is higher. Nevertheless, use of wing vs.
foot propulsion appears to correlate less with dive depth than
with water-column vs. benthic foraging, perhaps due to the need
for greater speed for effective lift-based thrust which is not
possible while probing for benthic prey.
15
Sink or swim strategies for low cost diving in marine
mammals.
WILLIAMS, T.M. Univ. of California, Santa Cruz.
During diving, marine mammals must balance the
conservation of limited oxygen stores with the cost of
locomotion. To determine how energetic costs are balanced
against locomotor demands, this study measured swimming
behavior and post-dive oxygen consumption of Weddell seals
foraging beneath the Antarctic ice shelf. Comparative kinematic
studies were conducted on diving elephant seals and bottlenose
dolphins. All animals were fitted with instrument packs (8 mm
camera, video recorder and time-depth microprocessor). For
Weddell seals, oxygen consumption was measured by open-flow
respirometry as the seal surfaced at an icehole. Each species
used constant swimming followed by prolonged gliding during
the descent. Glide duration depended on depth and represented
4A
Morphology, velocity, and intermittent flight in birds.
TOBALSKE, B.W. Univ. of Portland, OR.
Body size, wing shape, pectoralis composition, and forward
speed affect the use of intermittent flight in birds. During
intermittent non-flapping phases, birds extend their wings and
glide or flex their wings and bound. The primary flight muscles
are active and the wings support body weight during glides but
not during bounds. Body lift may be generated during bounds.
Species of intermediate body mass (35 -158 g), tend to flapglide at slower speeds and flap-bound at faster speeds,
regardless of their morphology. Such behavior may reduce
mechanical power output relative to continuous flapping. Smaller
species (< 35 g) with wings of low aspect ratio flap-bound at all
speeds, yet existing models do not predict an aerodynamic
advantage for the flight style at slow speeds. The behavior of
these species appears to be due to wing design rather than
pectoralis physiology. As body size increases among species,
percent time spent bounding decreases, and larger birds (> 300
g) do not flap-bound. This pattern may be explained by adverse
scaling of mass-specific power or lift per unit power output
available from flight muscles. The size limit for the ability to
bound intermittently may be offset somewhat by the scaling of
pectoralis composition.
18
Aerodynamics and energetics of intermittent flight in birds.
RAYNER, J.M.V.* and P.W. VISCARDI. Univ. of Leeds, United
Kingdom.
Many birds use an intermittent flap-bounding or flap-gliding
(undulating) flight strategy in preference to flying continuously.
Because of the aerodynamic demands and constraints of flight
these mechanisms are significant for birds, although suprisingly
are relatively rare in bats. Bounding flight is confined to small
birds, while undulating flight is more common in larger species.
For some birds intermittent strategies (particularly bounding) are
obligate, while for others they are facultative responses to flight
path geometry or environmental conditions. Intermittent flapping
may be a means of balancing or 'gearing' the energy required for
flight against the energy available from the flight muscles, or may
In many animals, locomotor movements are interspersed
with pauses lasting from msec to min. Potential costs of pauses
include increased energy costs for deceleration and acceleration,
increased time to travel a given distance, and a decreased rate
of beneficial encounters (e.g., with food, mates). Potential
benefits include increased biomechanical efficiency, increased
endurance through physiological recovery, decreased rate of
energy expenditure, decreased rate of detrimental encounters
(e.g.,with predators), decreased detection by predators, and
increased detection of prey, predators, mates, competitors, or
pathways through complex environments. The full range of costs
and benefits has rarely been considered in an single research
project because the costs and benefits arise from such diverse
biomechanical, energetic, perceptual, behavioral, and ecological
processes. Direct evidence for the importance of these costs
and benefits is surprisingly limited, but indirect evidence
supports their relevance in specific cases. When only a few
factors are important, relatively simple cost-benefit and game
theory models may be able to predict the evolution and flexible
use of pausing.
nearly 80% of the descent for dives exceeding 300 m. Ascents
were characterized by burst-and-glide swimming modes.
Transitions in swimming mode were attributed to buoyancy
changes with compression at depth and resulted in a 10-22%
reduction in energetic cost of the dive. By modifying locomotor
patterns to account for buoyancy changes, marine mammals are
able to extend the duration of dives despite limitations in oxygen
stores. Supported by NSF and ONR.
be to reduce the mechanical or aerodynamic power required to
fly. Novel theoretical models of power consumption are
combined with observations of varying flight patterns with speed
and with new measurements of body aerodynamics in European
Starling Stumus vulgaris to explore alternative hypotheses.
19
Energetics and mechanics of human walking at oscillating
speeds.
MINETTI, A.E.*. L. P. ARDIGO, E. M. CAPODAGLIO, and F.
SAIBENE. Manchester Metropolitan Univ., United Kingdom,
I.T.B.A., C.N.R., Italy.
20
Biochemical and ecological energetics of hummingbird
foraging flight.
SUAREZ, R. K.* and C. L GASS. Univ. of California, Santa
Barbara, and Univ. of British Columbia, Vancouver, Canada.
Small hummingbirds in hovering flight achieve the highest
known mass-specific metabolic rates among vertebrates. Their
foraging activity provides the opportunity for studies that
address a wide range of issues. What factors determine resting
and active metabolic rates and what are their physiological and
biochemical bases? How is behaviour integrated with physiology
and biochemistry to facilitate net energy gain? We shall explore
these issues in the context of their migratory flight from British
Columbia to Mexico. In their southward migration, rufous
hummingbirds stop to refuel by feeding on floral nectar in
subalpine meadows. In such habitats, they face the task of
achieving net energy gain despite the high energetic costs of
flight and thermoregulation. On a cold morning in a subalpine
meadow, rufous hummingbirds achieve the highest timeaveraged metabolic rates (250 W/kg) known among vertebrates.
Funded by NSF 9507407 and NSERC Operating Grant.
22
Modeling power output during terrestrial intermittent
locomotion.
WEINSTEIN, R.B. Univ. of Arizona, Tucson.
The earliest studies of intermittent exercise physiology noted
that moving intermittently (alternating brief movements with brief
pauses) could transform a heavy workload into a submaximal
one that can be sustained. This research provided the foundation
for the development of interval training and, more recently, for
the re-evaluation of steady-state paradigms for comparative
animal locomotion. I review key concepts underlying interval
training and discuss their values and limitations for modeling
power output during intermittent locomotion. In interval training,
recovery periods should be long enough for sufficient recovery of
power output but short enough to stress physiological systems
and induce a training effect. When intervals are short (<30 s),
optimal recovery periods are 3 times the interval duration. When
intervals are long (>180 s), recovery periods are less than or
equal to exercise duration. Using interval training as a model, I
examine the effect of intermittent movement on distance
capacity (i.e., total distance traveled before fatigue) for
ectotherms (lizards, crustaceans and insects). While the model
predicts some performance enhancing intervals, it does not
account for inter-specific differences or the effect of body
temperature.
23
Metabolic responses to intermittent exercise in humans.
PUTMAN, C.T.*, M.L PAROLIN, and G.J.F. HEIGENHAUSER.
Univ. of Alberta, Canada and McMaster Univ.H24, Hamilton,
Canada.
Many daily human activities require brief periods of
maximum muscular effort separated by periods of submaximal
activity or inactivity. Our laboratory has used a model of
repeated 30-second bouts of maximum isokinetic cycling
interspersed with 4-minutes of rest recovery to study the
metabolic response to short duration high intensity intermittent
exercise in humans. Throughout the initial bout ATP is primarily
derived from substrate phosphorylation {i.e. PCr and glycolysis)
and is associated with a large reduction in PCr and increased
lactate concentration. During subsequent bouts an increasing
proportion of ATP is derived from oxidative phosphorylation and
coincides with a reduction in force production. Initial force
production in each subsequent bout is highly dependent on the
replenishment of PCr during the preceding recovery period. Both
active and inactive muscles are involved in the redistribution of
energy substrates thereby contributing to the restoration of
osmotic acid-base and energetic homeostasis during the
recovery periods. Supported by MRC and NSERC Canada.
21
24
Modeling the metabolic energetics of brief and intermittent
locomotion in lizards and rodents.
GLEESON, T.T.* and T.V. HANCOCK. Univ. of Colorado,
Boulder.
A conflicting role for the pyruvate dehydrogenase complex in
resting versus contracting skeletal muscle?
TIMMONS, J.A. Pfizer Central Research, Sandwich, United
Kingdom.
When locomotor activity is brief, steady state conditions are
not attained. Thus it is difficult to model the energetic costs of
intermittent activity using standard methods. This difficulty is
addressed by considering as reflective of the metabolic costs of
activity not only the oxygen consumed during the activity itself,
but also the excess post-exercise oxygen consumption (EPOC).
This talk briefly reviews the metabolic events associated with
EPOC, and then examines how this approach can be applied to
address questions of how behavioral variables associated with
locomotion (activity duration, intensity, frequency) can influence
the energetic costs to the animal per unit distance. Using data
for lizards, mice, and others, EPOC can be shown to be the
major component of energetic costs when durations are short,
regardless of exercise intensity. Brief activity is much more
expensive by this measure than is steady state locomotion,
regardless of phylogeny or mass. Intermittent brief activity may
sometimes afford energetic savings relative to a single bout of
Flux dramatically increases through the pyruvate
dehydrogenase complex (PDC) at the onset of muscle
contraction. Under these conditions, oxidative phosphorylation
was thought to be rate limited by the availability of oxygen.
Randle and co-workers described a new integrated mechanism
for glucose homeostasis and a key role for PDC. The Randle
cycle stipulated that in order to prevent unnecessary glucose
oxidation, PDC had to be tightly regulated by the balanced
activities of a kinase and a phosphatase. Further, flux is also
regulated by alterations in substrate availability (e.g. pyruvate)
and product accumulation (e.g. acetyl-CoA). During the transition
from rest, the availability of acetyl groups dramatically alters the
metabolic responses to exercise, and it now seems that PDC
contributes significantly to the slow rate of increase in oxidative
phosphorylation (OxP). During ischemic contraction the rate of
increase in OxP has functional implications such that inactivate
PDC appears to reflect a developmental compromise in favour of
ABSTRACTS
5A
Six subjects walked on a programmable treadmill (Woodway
mod. ERGO-LG2, Germany) both at constant (3.5±0.0 km/h) and
oscillating speed (±0.5, ±1.0, ±1.5, ±2.0 km/h), set to change
between the two limits in 3 seconds. In each condition oxygen
consumption and 3D motion analysis were performed on 18
body joints at a frequency of 100 Hz. The same experimental
protocols were reproduced on the walkway by allowing subject
to adapt their stride frequency to an audio signal corresponding
to the sinusoidal stride frequency changes, individually measured
on the treadmill. Differently from what expected, only E±2.0
resulted to be different from E±0.0, both for the treadmill and the
walkway conditions. The analysis of the time course of the
mechanical external work, the one needed to accelerate and lift
the body centre of mass, reveals that a strategy devoted to
benefit from the normal mechanical energy fluctuations, as
occurring at 'constant speed', is likely to be used to cope with
different time-sequences of acceleration/deceleration, within a
given speed oscillation range.
activity. The approach is applied to examples of brief and
intermittent field behaviors. Supported by NSF 97240140.
glucose sparing. However, under conditions whereby PDC is full
activated, glucose homeostasis is not compromised. Thus, PDC
activation status does not appear to play a critical role in glucose
homeostasis, yet it can limit skeletal muscle performance by
reducing mitochondrial responsiveness during the rest to work
transition period.
25
MRS and NIRS vs. gas exchange in the assessment of
metabolic transients in skeletal muscle.
CERRETELLI, P.* and B. GRASSI. ITBA, National Research
Council, Milano, Italy.
Osmoregulation: An Integrated Approach
26
Water stress and proteins.
YANCEY, P.H. Whitman College, Walla Walla, WA.
Organic osmolytes are small solutes used to balance high
external salinity by cells of numerous water-stressed organisms
and tissues. Most such osmolytes are neutral amino acids,
polyols and sugars, and methylamines, but compositions vary
among species with different metabolisms and habitats, and
among mammalian tissues in normal and pathological states.
Unlike salt ions, most organic osmolytes are 'compatible,' i.e.,
do not perturb macromolecules. In addition, methylamines are
'counteracting,' i.e., can stabilize proteins and ligand binding
against perturbations by, e.g., urea in elasmobranchs and
mammalian kidney, and (our latest findings) high hydrostatic
pressure in deep-sea animals. These properties have led to
increasing use in agriculture and medicine, from plants
engineered for drought and salt tolerance, to in vitro rescue ot
misfolded proteins in cystic fibrosis and prion diseases (work of
Welch et al.). Methylamines appear to coordinate water
molecules tightly, resulting in osmolyte exclusion from hydration
layers of peptide backbones. This makes unfolded protein
conformations entropically unfavorable (work of Timasheff, Noto,
Bolen et al.).
28
A comparison of taurine efflux control during cell volume
recovery by invertebrate and vertebrate cells.
PIERCE, S. K.* and J. W. WARREN. Univ. of South Florida,
Tampa.
Symposia held to review cell volume regulation (CVR) after
osmotic stress often distinguish between 'invertebrate' and
'vertebrate' topics. This implies differences in the way
'invertebrate' cells go about their business. However, it is now
obvious that CVR mechanisms are very similar from species to
species, even from Kingdom to Kingdom. Implying differences in
CVR mechanisms based on phytogeny is misleading. Generally,
CVR in all cell types is accomplished by the regulation of two
general categories of osmolytes: inorganic ions, usually K+and
CI', and low molecular weight organic compounds, usually
certain amino acids and quaternary ammonium compounds. The
difference in who regulates what does not depend upon the
presence or absence of a backbone, but instead upon the type
of osmotic environment that a cell expects (in an evolutionary
sense) to encounter. To illustrate this, we will compare the
hypoosmotically induced mechanism of taurine efflux from
RBC's of the bivalve, Noetia ponderosa, probably the best
understood 'invertebrate' cell type in this regard, and taurine
efflux from a variety of 'vertebrate' cells.
29
Cell surface area regulation in neurons: A mechanosensitive
process.
MORRIS, C. Loeb Institute, Ottawa, Canada.
Cell surface area regulation is a fundamental engineering
issue that all cells must face. The task: to ensure that at all times
and at all parts of the cell, there is sufficient but not excess
plasma membrane. Because lipid bilayers are essentially inelastic
(area increase >3% ruptures the membrane), membrane must be
added or subtracted to accommodate changes in cytoplasmic
shape and volume. For example, during development, some
neurites of a given neuron retract (necessitating membrane
retrieval) while simultaneously others elongate (necessitating
membrane insertion). I hypothesize that local membrane tension
provides a critical signal for area adjustments: high tension
promotes membrane acquisition, low tension promotes
membrane retrieval. We use multiple approaches to study
surface area regulation in swelling and shrinking molluscan
neurons: membrane capacitance, determination of in-plane
membrane tension using laser tweezers to pull membrane
tethers, live cell confocal microscopy with membrane and fluid
phase dyes, fluorescence-labelling of membrane skeleton viewed
at high resolution, and calcium imaging. Compared to the wellrecognized issue of cell volume regulation, cell surface area
regulation has received scant experimental attention.
27
Microbial stress responses to high-osmolality environments:
Uptake and synthesis of compatible solutes.
BREMER, E. Philipps-Univ., Marburg, Germany.
Exposure of bacteria to high osmolality environments triggers
rapid fluxes of water along the osmotic gradient, causing a
reduction in turgor, dehydration of the cytoplasm and cessation
of growth. Microorganisms actively respond to variations in the
external osmolality to maintain turgor within physiologically
acceptable boundaries. They do not possess active transport
mechanisms for water, and hence turgor is adjusted by
controlling the pool of osmotically active solutes in the
cytoplasm. To counteract the out flow of water under
6A
30
Organic osmolyte release pathways and cell volume
regulation in the mammalian kidney.
KINNE, R.K.H.* and E. KINNE-SAFFRAN. Max-Planck-lnstitute
for Molecular Physiology, Dortmund, Norway.
In the medulla of the mammalian kidney cells are exposed to
rapid and extensive changes in the osmolarity of extracellular
fluid. To regulate their volume these cells rely on organic
osmolytes such as polyols, methylamines, and amino acids.
During hypertonicity osmolytes are accumulated by secondary
active transport systems or by intracellular synthesis. Lowering
the osmolarity leads to a rapid release of organic osmolytes. At
Kinetics of 0 2 consumption (V02) at onset and offset of
constant-load exercise can give insights into regulation of
skeletal muscle oxidative metabolism. Measurements have been
carried out at the tissue and at the whole body level. At the
tissue level VO2 on- and off-kinetics were determined: a) Directly
by dynamic solution of the Fick equation; attempts were made to
get similar informations from [HHb] and [02Hb] measurements
by NIRS. b) Indirectly from kinetics of PCr hydrolysis and
resynthesis (31P-MRS). At the whole body V02 on- and offkinetics are determined by breath-by-breath pulmonary gas
exchange. The phase 2 of the VO2 on-response and the V02
off-response yield relevant metabolic informations. At the tissue
level the VO2 on- and off-responses are monoexponential (halftimes t1/2 of 15-20 s). At the whole-body level the VO2 onkinetics is more complex. The VO2 off-phase is more constant
and its kinetics parameters are close to those obtained at the
tissue level. Informations derived from VO2 kinetics are valuable
for a functional evaluation of skeletal muscle oxidative
metabolism. In ordinary conditions the rate of adjustment of
muscle VO2 appears to be mainly imposed by intrinsic factors.
hyperosmotic conditions, microorganisms dynamically increase
their intracellular solute pool by amassing large amounts of
special organic osmolytes, the so-called compatible solutes,
either through synthesis or uptake from the environment. These
osmolytes (e.g. glycine betaine) are highly congruous with
macromolecular and cellular functions. The molecular and
physiological mechanisms of compatible solute accumulation
operating in the soil bacterium Bacillus subtilis will be
summarized. Through this overview, I intend to provide the
audience with a survey of the common strategies used in the
microbial world to cope with high osmolality stress.
least three different release pathways exist: one for sorbitol, one
shared by taurine and myoinositol, and one for betaine. All of
them appear to have channel-like properties. They differ,
however, in their signal transduction pathways with regard to the
involvement of calcium, G-proteins, and arachidonic acid. Also
calcium/calmodulin protein kinases seem to regulate cell plasma
membrane permeability. Furthermore, cycling of reserve
membrane vesicles and transporters has been shown to elicit
rapid modification of transmembrane fluxes. Thus, multiple
organic osmolytes and various signal transduction pathways
regulate in a concerted manner cell volume in the renal medulla
and support the capability of these cells for whole body
osmoregulation.
31
Osmotically responsive genes: The mammalian osmotic
response element (ORE).
FERRARIS, J.D. National Institutes of Health, Bethesda, MD.
32
Evolution of osmosensory cell signaling pathways.
KULTZ, D. Univ. of Florida, St. Augustine.
Osmolality is an important environmental factor that imposes
a major selection pressure on the evolution of life. As a result of
this pressure, all extant cells have osmoregulatory mechanisms
that control the intracellular ionic milieu, for which cell
metabolism has been optimized. A change in the osmolality of
the environment imposes an osmotic stress upon cells that
affects the concentration and stability of macromolecules, the
rate of biochemical reactions, and cell function as a whole. Cells
respond to osmotic stress with a variety of osmoregulatory
responses, whose concerted action promotes (1) survival, and (2)
adaptation of cell function to an altered osmolality, or, if cell
type-specific tolerance thresholds are exceeded, (3)
programmed cell death. These different outcomes depend on
complex intracellular signaling networks. The evolution of such
networks is discussed with emphasis on mitogen-activated
protein kinase cascades.
33
MAPK activation cascades mediating stress responses to
hyperosmolarity in yeast.
ERREDE, B.' and B.M. BUEHRER. Univ. of North Carolina,
Chapel Hill.
A prevalent signal transmission mechanism involves a protein
kinases cascade that is conserved from yeast to humans.
Enzymes of the cascade are members of families known as
MEK-kinases (MEKKs), MAPK/ERK kinases (MEKs), and mitogen
activated protein kinases (MAPKs). Five MAPK activation
cascades are already defined in yeast. For example, two different
membrane proteins, Sln1 and Sho1, sense increases in external
osmolarity and stimulate activation of the MAPK, Hog1. The two
sensors use different MEKKs and integrate information at the
level of the MEK, Pbs2. Ssk2 and Ssk22 are redundant MEKKs
ABSTRACTS
34
Osmoregulation in plants.
CUSHMAN, J. C. Oklahoma State Univ., Stillwater.
Unlike animals, osmotic adjustment and ion homeostasis in
plants and fungi is maintained by a complex system of ion
transporters at the plasma and vacuolar membranes energized
by chemiosmotic proton circuits energized by H + -ATPases.
Insights about plant cation uptake and efflux systems and their
regulation by osmotic and ionic stress have come mainly from
comparative studies with yeast and genetic analysis of
Arabidopsis mutants. Calcium and calcium activated protein
phosphatases (calcineurin) and kinases (Ca2* /calmodulindependent protein kinases) clearly participate in osmotic and
ionic stress signaling and tolerance. However, little is known
about the primary sensors of osmoregulatory pathways. To gain
a global understanding of the complex ways in which plants
integrate osmoregulatory responses, functional genomics
approaches are being used to isolate and characterize all salinity
or drought stress-related genes in halophytic and glycophytic
higher plant {Arabidopsis, Mesembryanthemum , and Oryza ),
and non-plant models (Aspergillus , Dunaliella , Synechocystis ,
and Saccharomyces ). Comparisons among these diverse
organisms should reveal both evolutionary conserved and
unique osmotic stress defense mechanisms. This work is
support by the NSF Plant Genome Program.
35
Osmoregulation by gills of aquatic animals.
TOWLE, D.W. Lake Forest College, IL and Mount Desert Island
Biological Laboratory, Salsbury Cove, ME.
Poised at the interface between the milieu interieur and
environment, gills contribute to osmoregulation by controlling
fluxes of osmolytes, regulating particularly the concentration of
Na and Cl ions in blood. A review of the mechanisms by which
gills of teleosts, crustaceans, and molluscs regulate the transport
of these ions reveals that the sodium pump provides the major
driving force by linking basolateral Na* transport to ATP
hydrolysis. The resulting electrochemical gradient energizes a
variety of other transporters, including the sodium-hydrogen
exchanger, sodium-potassium-2-chloride cotransporter, and
sodium channel. A vacuolar-type hydrogen ion pump may also
drive ion uptake or ammonia excretion across gills, and evidence
suggests roles for the chloride-bicarbonate exchanger and
chloride channels. In crustacean gills, osmoregulatory challenge
is accompanied by induction of carbonic anhydrase activity,
likely increasing counterions for sodium-hydrogen and chloridebicarbonate exchange. Recently, several of these transporter
cDNAs have been cloned and sequenced. Changes in gene
expression appear to be important components of the
osmoregulatory response in gills. Supported by NSF (IBN9807539).
36
The hormonal control of osmoregulation in fish.
MCCORMICK, S.D. Conte Anadromous Fish Research Center,
Turners Falls, MA.
As the primary link between environmental change and
physiological response, the neuroendocrine system is a critical
part of osmoregulatory adaptations. Cortisol has been viewed as
'the' seawater-adapting hormone in fish and prolactin as 'the'
fresh water adapting hormone. Recent evidence indicates that
the growth hormone/insulin-like growth factor I axis is also
important in seawater adaptation in several teleosts of widely
differing lineages. In salmonids growth hormone acts in synergy
7A
Hyperosmotic accumulation of organic osmolytes is
transcriptionally regulated in bacteria, yeast, plants and
mammals. Renal medullary cells, among mammalian cells, are
uniquely exposed to hyperosmotic stress; in these cells,
hyperosmotic stress results in accumulation of sorbitol as a
predominant osmolyte. Sorbitol accumulates due to a rise in the
synthesis rate of aldose reductase (AR), which catalyzes the
conversion of glucose to sorbitol. Hyperosmotic stress increases
transcription of the AR gene which leads to a rise in AR mRNA
levels. In cloning and characterizing the rabbit AR gene, the first
evidence of a eukaryotic osmotic response element (ORE) was
found. Since then, several mammalian OREs have been
discovered. Sequence containing an ORE was identified for the
canine Na- and Cl- coupled betaine transporter gene as well as
the Na/myo-inositol cotransporter gene. Because it is possible to
find homology between the OREs of the AR genes and those of
the betaine and inositol genes, a consensus for the mammalian
ORE was derived by functional assessment. Most recent studies
have yielded discovery of other c/s-elements that potentiate the
ORE response and a trans-activating factor that binds to the
ORE.
for the Sln1-dependent branch while Ste11 is the MEKK for the
Sho1-dependent branch. Ste11 is also the MEKK for another
cascade with Ste7 (MEK) and the redundant Fus3 and Kss1
enzymes (MAPKs) that mediate responses to peptide mating
pheromone. Even though Ste11 functions in both the mating and
stress pathways, activation of Ste11 by pheromone or
hyperosmolarity leads only to the response appropriate to one
stimllus or the other. My talk will describe two mechanisms that
contribute to the specificity of signaling through the different
MAPK activation modules.
with cortisol to increase seawaler tolerance, at least partly
through the upregulation of gill cortisol receptors. Cortisol under
some conditions may promote ion uptake and interacts with
prolactin during acclimation to fresh water. The osmoregulatory
actions of growth hormone and prolactin are antagonistic.
Although a broad generalization that holds for all teleosts is
unlikely, our current understanding indicates that growth
hormone promotes acclimation to seawater, prolactin promotes
acclimation to fresh water, and cortisol interacts with both of
these hormones thus having a dual osmoregulatory function.
considerable evolutionary change occurred in egg size as phyla
diverged into classes, but that little has occurred since. Higher
nodes analysis and phylogenetic subtraction analysis at the class
level revealed that egg size was largest for species with
nonplanktonic development, next largest for species with
planktonic, nonfeeding development, and smallest for species
with planktonic, feeding development. When all development
modes were considered at the class level, egg size was
significantly negatively correlated with planktonic duration, but
egg size was not correlated with adult size.
37
40
The role of plant and animal 'behavior' in confronting
osmotic challenges.
WOLCOTT, T. G.* and D. L WOLCOTT. North Carolina State
Univ., Raleigh.
Calculation and interpretation of the level of egg provisioning
in marine invertebrate life cycles.
MCEDWARD, LR. Univ. of Florida, Gainesville.
Topic in Integrative Evolutionary Studies
38
The fertilization ecology of three congeneric sea urchins
from the northeastern Pacific.
LEVITAN, D.R. Florida State Univ., Tallahasee.
Three species of sea urchins, Strongylocentrotus
droebachiensis, S. franciscanus, and S. purpuratus, vary in
gamete traits and demography. Female fertilization success was
measured in two ways: (1) By releasing gametes from a single
male and female into the sea and recapturing them to measure
fertilization performance when all else is equal and (2) By
inducing natural assemblages of sea urchins to spawn in their
natural habitat to estimate levels of fertilization. In the first test,
fertilization was correlated with species specific gamete traits. In
the second test, fertilization was con-elated with the distribution
and abundance of males. The species rank performance in these
two tests was inversely correlated; species that did the best
when all else was equal had the lowest fertilization rates under
natural demographic conditions. These data suggest that gamete
attributes greatly influence fertilization in the sea and that
selection has acted on these gametes to enhance the probability
of fertilization in species that are more likely to be sperm limited.
3?
A comparative analysis of egg size in marine invertebrates:
Relationships with development mode, planktonic period and
adult size.
ECKERT, G.L. Univ. of California, Santa Barbara.
I examined variation in egg size for over 600 species of
marine invertebrates from 10 phyla to investigate the
relationships between egg size and developmental mode, egg
size and planktonic period, and egg size and adult size, i used
comparative methods to identify the level at which taxa can be
considered independent and then conducted analyses at this
level. For the species examined in this study, the majority of
variance in egg size occurred at the class level, suggesting that
8A
The resources packaged into the eggs of free-spawning
marine invertebrates represent the entire parental contribution
towards the energy and material requirements for development.
Although the proportion of the required energy that is provided in
the egg (s) is an important quantity in life history theory, there are
extremely few published values in the literature. I used four
different methods to calculate s. Calculations based on egg
volume and average values for energy per unit volume can be
applied to a very large database of egg sizes in several taxa. The
best estimates of s require information on the energy content of
eggs and juveniles and the rate of energy metabolism during
development, which is rare. Calculated values of s, among
species of echinoids spanned 5 orders of magnitude (s < 0.01 s > 1000). The interpretation of s is straightforward for
planktotrophic development, but becomes problematic for
lecithotrophic development (s > 1). Better data and a precise
definition of this measure of egg provisioning are crucial to
understanding the evolutionary transitions among patterns of
larval development.
41
Extended parental care in Sphaerium striatinum: Evidence
for retention of competent young.
BEEKEY, M.A.', R.H. KARLSON, and A. GREENBURG. Univ. of
Delaware, Newark.
The release of offspring marks a critical turning point in an
organism's life history. The timing of offspring release signals the
end of parental investment and the beginning of independence
for offspring. The amount of time and energy invested in the
parental care of young is a shaped by a myriad of both
physiological and microevolutionary trade-offs. Feeding young
has heavy energetic requirements that may exceed those of egg
production or gestation. In many species, a variety of
mechanisms exist that reduce the costs of feeding young. In
Sphaerium striatinum,a freshwater clam, fertilized eggs are
brooded within the inner demibranch, undergo direct
development, and are retained until the young mature into
miniature adults. Juveniles as small as 2.0 mm, independent of
the adult, are competent in terms of feeding and survival. Young
are retained within the brood pouch until they reach a size of 4.0
mm. Here we present a mechanism for decreasing costs
associated with parental care in this species. The retention of
competent young in S. striatinum will also be discussed in
relation to increasing offspring survivorship in response to
factors such as predation and environmental instability.
42
Colony allometry and life history evolution in the soft coral
genus Alcyonium.
MCFADDEN, C.S. Harvey Mudd College, Claremont, CA.
The association between small body size and embryonic
brooding has been well documented in a wide variety of solitary
marine invertebrate taxa. To date, however, associations
between either polyp size or colony size and brooding have not
been documented in colonial taxa. The soft coral genus
Alcyonium encompasses a diversity of colony morphologies and
life histories. A partial phytogeny based on ribosomal internal
transcribed spacer (ITS) sequences suggests that there is no
phylogenetic pattern to the distribution of life histories in this
aenus: sister taxa often reproduce very differently. There is.
Biologists must remember that physiology is the product of
natural selection on organisms interacting with heterogeneous
environments. 'Behaving' organisms may alter the osmotic
conditions they experience and achieve results unexpected from
laboratory studies. Their ability to exploit environmental
heterogeneity depends on its temporal/spatial scale relative to
that of the organism, and the correspondence beween the
osmotic differences and the organism's sensory and
osmoregulatory physiology. 'Behaviors' include evasion of
stressful habitats, selection among differing microenvironments,
changing body characteristics that affect salt/water uptake/loss,
manipulating fluids differing in osmolytes, and modification of
osmotic microenvironments (especially for vulnerable offspring).
To draw 'comparative and integrative' inferences, investigators
must strive to understand organisms' actual challenges by
'seeing' the world from their perspective, and then making
observations and performing experiments in the context of the
'real world' experienced by that organism.
however, a significant correlation between colony size and mode
of development: species with large colony size broadcast spawn,
while small colonies brood their embryos. These results suggest
that Alcyonium colonies may experience allometric constraints
on brooding similar to those that have been proposed to explain
the association between size and life history in solitary taxa.
43
Regulation of binary fission in the sea anemone Anthopleura
elegantissima: The role of clonal genotype and feeding
regime.
SECORD, D.*, J.S. PEARSE, V.B. PEARSE, and C.E. MILLS.
Univ. of Washington, Tacoma, Univ. of California, Santa Cruz,
and Friday Harbor Laboratories, WA.
44
Consequences of offspring body size on offspring
survivorship in reptiles.
STEYERMARK, A.C.* and J.R. SPOTILA. Drexel Univ.,
Philadelphia, PA.
Offspring body size is important because it may affect both
offspring and parental fitness. Although data support a higher
probability of survival in larger offspring as compared to smaller
offspring in some taxa, this 'bigger is better' hypothesis is purely
conjectural when it comes to reptiles. Here, we present the
theoretical framework surrounding the tradeoff between offspring
size and offspring number and review the literature that
examines the effect of offspring size on hatchling and juvenile
survivorship in reptiles. Little is known of body size effects on
survival of snake and crocodile hatchlings and juveniles. In
lizards, hatchling body size appears to affect survivorship when
competition for resources is high; however survivorship is
independent of body size in some years and in some
populations. In turtles, it is unclear from available studies
whether variation in observed hatchling body size affects
survivorship in species of larger freshwater turtles and most sea
turtles. Strength of competition, importance of body size in
determining competitive outcomes, predator size, and rates of
egg predation in part determine the strength of the relationship
between offspring size and survivorship.
45
Elevated CO 2 depresses growth in Japanese quail and bank
swallows.
BAVIS, R.W.* and D.L. KILGORE, JR. Univ. of Montana,
Missoula.
While studying the effects of CO2 exposure during
development on adult ventilation in Japanese quail, we observed
that COj-exposed individuals appeared smaller. In subsequent
experiments, we incubated quail eggs in moderate (-2%) CO2
and then raised the young in room air. Growth curves were
constructed by weighing the quail weekly. We found that CO 2 exposed quail weighed less than control quail at each weighing.
To determine whether a similar effect exists in a species
chronically exposed to elevated CO 2 in nature, we monitored
burrow CO2 levels and nestling mass (at 13,14, and 17 days) of
bank swallows; CO 2 was supplemented in a few burrows. There
was a significant negative relationship between nestling mass
ABSTRACTS
46
Morphological and ecological correlates of sprint capacity in
lizards - a phylogenetic analysis.
VAN DAMME.R.*, B. VANHOOYDONCK, and P. AERTS. Univ. of
Antwerp, Belgium.
Because it seems ecologically relevant and is relatively easy
to measure, maximal sprint speed has become a popular 'whole
animal function1 in herpetology. The literature now holds data on
the sprinting capacity of over 200 species of lizards from 9
families or subfamilies. We have compiled these data and added
our own measurements on lacertid lizards. Preliminary inspection
of the data suggested important disparity among methodologies
(e.g., race track versus treadmill measurements), and urged us to
restrict our analyses to a subset of the available data (still about
100 species). We used this restricted set to test a number of
ecomorphological hypotheses on the determinants of
interspecific variation in sprint capacity. More specifically, we
investigated the effects of body size, limb length, and body
temperature. We also tested whether maximal sprinting capacity
differed among lizards from different climates, between diurnal
and nocturnal species, between animals with different foraging
strategies (sit-and-wait versus actively foraging), and between
species with different microhabitat uses. All analyses were done
using comparative method statistical programs.
47
Do speedy sprinters make clumsy climbers in lacertid
lizards?
VANHOOYDONCK, B.*, R. VAN DAMME, P. AERTS, and F. DE
VREE. Univ. of Antwerp, Belgium.
The theory of natural selection predicts a tight fit between an
organism's morphology and its ecology. However, phenotypic
evolution can be constrained in several ways. The existence of
trade-offs is one cause of imperfection. A trade-off occurs when
performance at one task can not be optimized without
detrimentally affecting performance at another. Here, we study
whether evolution of locomotor performance in lacertid lizards is
constrained by a trade-off between sprinting and climbing ability.
Since biomechanical reflections suggest that lizards specialized
in level-running should differ in parts of their morphological
design from lizards specialized in climbing, a trade-off can be
expected. Moreover, lacertid lizards are known to occupy a wide
range of microhabitats in which different locomotor modes are
favoured (e.g. sandy plains, rocks, vegetation).
We compared maximal sprint and climbing speed in twelve
lacertid lizard species and measured several morphological
features thought to influence locomotor capacity (e.g. length of
limb segments). To determine the ecological relevance of the
variation in performance, we quantified microhabitat preference.
All analyses were done in a phylogenetic context.
48
The strength of phenotypic selection in natural populations:
A review.
KINGSOLVER, J.G.', H. HOEKSTRA, J. HOEKSTRA, D.
BERRIGAN, S. VIGNIERI, C. HILL, A. HOANG, P. GIBERT, and P.
BEERLI. Univ. of Washington, Seattle.
How strong is natural and sexual selection in the wild? We
reviewed the literature from 1984 through 1997 for studies that
estimated the strength of directional selection in terms of linear
selection gradients (S) on natural variation in quantitative traits
for field populations. We tabulated 63 published selection
studies that reported over 900 estimates of (S. The absolute
values of I(SI were exponentially distributed with a mean of 0.22,
suggesting that strong directional selection was uncommon. The
distributions of I(SI for selection via aspects of survival (viability
selection) and via aspects of mating success (sexual selection)
9A
The intertidal sea anemone Anthopleura elegantissima of
northeast Pacific rocky coasts facultatively undergoes binary
fission. Published studies suggest that both genetic and
environmental factors may underlie regulation of polyp fission,
and hence the formation of large clonal aggregations, in this
species. In a factorial laboratory experiment designed to
minimize aggressive interactions between individuals, we
independently varied clonal genotype (six clones from two
locations in Washington State) and feeding regime (fed versus
starved) to determine their effects on fission rate. We found that
genotypes vary in their division frequency, that well-fed polyps
are significantly more likely to divide than starved polyps, and
that starved polyps move significantly more than fed polyps.
Together with published data on agonistic interactions, patterns
of genetic diversity, and the frequency of sexual recruitment, this
study contributes to a mechanistic understanding of the origins
and maintenance of clonal aggregations in these sea anemones.
and burrow CO2 levels at 13 and 14 days, but a similar trend
was nonsignificant at 17 days. The response to intradermal PHA
injection, used as an indicator of stress, was not correlated to
burrow CO 2 levels in nestling bank swallows. Our data suggest
that there may be a tradeoff between the protection afforded by
burrows and the consequences of CO 2 accumulation within
burrows.
were significantly different: on average, sexual selection was
stronger than viability selection. Most published selection studies
were unreplicated and had small sample sizes, resulting in low
power to detect selection of the magnitude typically reported for
natural populations.
49
A new phylogenetic hypothesis for the order
Tetraodontiformes (Teleostei, Pisces), with placement of the
most fossil basal lineages.
SANTINI.F.*, and J.C.TYLER. Univ. of Toronto, Canada, and
National Museum of Natural History, Washington, DC.
50
Phylogenetic relationships of the amphisbaenia based on
morphological evidence from fossil and living forms.
KEARNEY, M. George Washington Univ., Washington, DC.
Amphisbaenians are fossorial, highly modified, squamate
reptiles. Fossil amphisbaenians differ dramatically from living
forms in morphology and geographic distribution, which has
prompted quite different evolutionary scenarios from
neontological vs. paleontological viewpoints. The phylogenetic
relationships of the group have been enigmatic for decades but
have never been explored cladistically. A data matrix of 160
characters based on the comparative anatomy of osteology,
integument, and soft tissues for the 23 extant genera and 18
fossil forms was compiled and phylogenetic analyses of these
data were conducted. Results provide an explicit hypothesis of
amphisbaenian relationships and character evolution, and imply
that known fossil amphisbaenians are derived relative to extant
forms. Disparate views of amphisbaenian phylogeny emerge
depending on whether fossil or extant forms are emphasized. A
combined analysis provides the most highly corroborated
hypothesis. Such combined analyses are often considered
intractable, however, due to non-preservation of many
characters in fossil taxa and concommitant missing data in data
matrices. Problems related to missing data in cladistic analyses
are discussed.
51
Non-avian feathers in a Triassic basal archosaur.
RUBEN, J.*, T.JONES, W.HILLENIUS, L.MARTIN, and
E.KOROCHKIN. Oregon State Univ., Corvallis, College of
Charleston, SC, Univ. of Kansas, Lawrence, and Russian
Academy of Science, Moscow.
Longisquama was a Triassic arboreal archosaur with many
bird-like skeletal features, including a well-developed furcula,
strap-like scapula, elongate penultimate digits, bird-like teeth, a
posteroventrally oriented foramen magnum, and expanded
braincase. In addition, the brachium and antebrachium contained
a series of elongate postaxial scales. Based on close
examination of the specimens, we interpret the elongate scales""
as having been a unique axial gliding wing which is comprised of
a set of asymmetrical feather-like structures. Each of these
contains a hollow pulp cavity central rachis and distally
10A
52
Amniote relationships as inferred from morphology and
molecules.
SHEIL, C.A.*, R.J. RAXWORTHY, A.L. CLARKE, S. HAUSWALDT,
J.B. PRAMUK, and LA. PUGENER. Univ. of Kansas, Lawrence.
Relationships among amniotes have been argued for
centuries and little consensus has been reached; recent
publications have brought much renewed attention to the topic.
Here, morphological and molecular data are analyzed to
determine relationships among extant and fossil amniotes.
Extant taxa included represent members of six amniote lineages
(turtles, mammals, squamates, rhynchocephalia, crocodilians,
and birds), with a single anamniote (amphibians) selected as the
outgroup for phylogenetic analyses. Extinct taxa included in this
investigation represent several fossil lineages: Captorhinidae,
Procolophonidae and Parieasauridae (non-turtle anapsids);
Petrolacosaurus and Araeooscelis (early diapsids);
Trytilodontidae (a non-mammal synapsid); and Mesosauridae.
Combined and separate parsimony analyses of 401
morphological (soft anatomy, physiology, behavior, and
osteology) and 8000 molecular (base pairs from the nuclear and
mitochondrial genome) characters were conducted with extant
taxa only, as well as both extant and fossil taxa. Relative
congruence among analyses, taxon sampling, importance of
fossils, and the controversy of amniote phylogeny are discussed.
53
Brain evolution in cetaceans as revealed by endocranial
morphology.
MARINO, L. Emory Univ., Atlanta, GA.
About 55 million years ago cetacean (dolphin, whale, and
porpoise) ancestors began a transition from a terrestrial to
aquatic lifestyle which was accompanied by dramatic
endocranial and transformations. These changes reveal
reorganization of overall brain morphology and size, i.e., a major
increase in brain/body weight ratio and cortical elaboration.
Some modern cetacean species are second only to humans in
level of encephalization and possess a number of unique derived
brain features. Yet, there has been relatively little work on how,
when, and at what rate these changes in cetacean brains
occurred. I will discuss the results of studies aimed at
uncovering patterns of cetacean brain evolution by using
Computed Tomography-based imaging and measurement
methods to examine endocranial morphology in several fossil
cetacean species. Data to be presented include quantitative and
qualitative analyses and images of endocranial volume and
morphology in several Eocene, Oligocene, and Miocene
cetaceans, and a comparison with modern cetacean data. These
results will be discussed within the context of their implications
for the evolution of brain function and behavior in cetaceans.
54
Paleoclimates, plant and animal impacts on hominid
evolution of bipedalism, fur loss and lifestyle changes 8
MYBP.
PORTER, W.P.*, Y. WISE, J. KUTZBACH, and K. STEUDEL
Univ. of Wisconsin, Madison.
We reconstruct paleoclimates of 8 million years before
present (MYBP) in Africa. We use these to drive microclimate
models for forest and savannah. We use a state-of-the-art
endotherm model with chimpanzee fur insulation to calculate
hourly metabolic and water costs, and potential activity (foraging)
time for the year. We explore how these change due to fur
presence/absence, bipedal/quadrupedal posture, paleo-Anodem
climate, and low/high vegetation, which affects ground shading.
Bipedal posture has a significant heat balance advantage and
extends activity time significantly. Fur loss does not confer an
evaporative water loss advantage in the warmer, more humid
paleoclimates of Africa, except on savannahs with short grass.
Otherwise, fur always conferred an energetic and activity time
advantage. Finally, we suggest how grazing animals on the
savannah as it emerged in ancient Africa may have been cruciai
The order Tetrodontiformes comprises over 300 species of
mostly coral reef fishes. The first fossil record spans back to the
upper Cretaceous, with the now extinct superfamily
Plectocretacicoidea. This superfamily represents the sister group
to all the other tetrodontiform groups. Most modern lineages of
Tetraodontiformes appear in the fossil record in the Eocene, and
many fossil taxa already show very close resemblance to present
representatives of their lineage. The goals of our work will be to:
1) Present a phylogenetic hypothesis, based on osteological
characters, for the order Tetrodontiformes, including fossil and
extant representatives for each lineage. This will allow us to test
the present classification, based on myological characters, and
to place for the first time in a cladistic framework many fossil
taxa; 2) Discuss, on the basis of phylogenetic and
ecological/paleoecological evidences, possible scenarios for a
deep-sea origin of the Tetraodontiformes; 3) Discuss if
theTetraodontiformes have undergone an evolutionary radiation,
and try to elucidate what factors might have triggered such an
event.
separated barbs. Longisquama is member of a group of arboreal
forms from which birds may well have been derived.
in the hominid transition from a sedentary quadrupedal herbivore
to a smart nomadic bipedal carnivore.
55
Paleonemerteans as urbilaterians and hoplonemerteans as
rudimentary vertebrates.
JENSEN, D.D.. Univ. of Nebraska-Lincoln.
Nemerteans (phylum Nemertini or Rhynchocoela) are
identified by the key character of an eversible proboscis. The
three nemertean orders differ substantially in embryology and
neuromuscular arrangements. It is suggested that
paleonemerteans are the urbilateria (the proximal ancestor of
both protostomes and deuterostomes), that the
heteronemerteans gave rise to other protostomes (determinant
spiral cleavage embryology, blastopore associated with the
mouth, increased muscularity, intramuscular nervous system)
and that hoplonemerteans gave rise to deuterostomes (regulative
development, a blastopore not associated with the mouth,
submuscular nervous system). Hoplonemerteans possess many
potential homologues for vertebrate organs and a bauplan similar
to that of agnathans, hence their description as rudimentary
vertebrates."" Currently available biochemical evidence will be
discussed..""
Direct-developing intertidal Lasaea lineages occur in the
North Atlantic as both continental margin and oceanic island
populations. We conducted molecular phylogenetic analyses of
representative populations in order to test colonization
hypotheses for North Atlantic oceanic islands. Individuals were
collected from continental putative source populations (Florida,
Iberia) and three oceanic island groups (Bermuda, Azores,
Madeira). Mitochondrial gene sequence data were generated and
analyzed phylogenetically. No amphi-Atlantic genotypes were
detected. Azorean and Madeira samples clustered exclusively
with downstream Iberian congeners and tree topologies are
consistent with multiple countercurrent colonizations of the
Azores. Bermudan lineages clustered exclusively with Floridian
congeners to form a shallow western North Atlantic clade in
which the mainland lineages formed a terminal branch. This is a
mirror image of a priori expectations based on western Atlantic
current polarity and may result from divergent demographic
processes operating on the Floridian and Bermudan populations.
57
Is evolution progressive? Insights from herbivorous lizards.
ESPINOZA, R.E. Univ. of Nevada, Reno.
Correlated progression is an evolutionary hypothesis that
predicts organismal traits will evolve in a progressive fashion as
a result of the accumulation of adaptive specializations.
Specializations associated with diet, for example, might be
expected to select for correlated and progressive adaptations to
enhance feeding and digestion. I tested this hypothesis for
herbivorous lizards. I examined morphological, physiological, and
reproductive traits considered to be associated with herbivory in
lizards. Species examined spanned all major lineages and
exhibited a diversity of dietary strategies. Comparative analyses
indicate that strictly herbivorous lizards can be characterized by
large body and gut sizes, specialized teeth, hindgut nematodes,
high activity temperatures, and the production of small clutches
of large eggs. Traits associated with herbivory have been
acquired independently in several clades of lizards and appear to
be irreversible. Omnivorous outgroup taxa exhibited some of
these traits, but closely related carnivores had relatively few such
features. Collectively, these data suggest that traits associated
with herbivory evolve in a manner of increasing specialization
thereby supporting the hypothesis of correlated progression.
ABSTRACTS
Molecular phytogeny of the live-bearing fishes of the
subfamily Poeciliinae (Cyprinodontiformes: Poeciliidae).
THOMPSON, L E . The Univ. of Alabama, Tuscaloosa.
Members of the subfamily Poeciliinae exhibit extensive
behavioral and morphological variation which when coupled with
relative ease of maintenance and short generation times make
them popular with both researchers and aquarists alike. Although
much work regarding these fishes has been conducted in the
past, most has been based on morphological and/or behavioral
data resulting in implied inter- and intra-generic relationships. In
those cases where molecular data were used, either relatively
few taxa were incorporated, or the analyses were restricted to
intra-generic relationships. In this study a portion of the
cytochrome b gene (313 bp) and control region (163 bp) of the
mtDNA genome were sequenced and analyzed both
independently and combined using maximum parsimony and
maximum likelihood analyses. Some aspects of the phylogenetic
relationships obtained are consistent with work performed
previously while others imply that a taxonomic re-evaluation of
portions of the subfamily Poeciliinae is in order.
59
Towards a genomics resource for developmental and
evolutionary studies of salamanders.
VOSS, S.R.', J.J. SMITH, and D.M. PARICHY. Colorado State
Univ., Fort Collins and Univ. of Texas, Austin.
The identification of homologous chromosomal segments
among all the major vertebrate groups will facilitate candidate
gene analyses of interesting developmental traits and
comparative studies of genome evolution. Here, we present
preliminary results from a recently initiated genome project of
two classical salamanders {Ambystoma): Eastern tiger
salamander and Mexican axolotl. We mapped 20 protein-coding
loci, 2 single gene color variants, and a major QTL for
metamorphic failure using an existing interspecific mapping
cross and partial genetic linkage map. Our data indicate that
both tightly and relatively, distantly-linked genes in mammalian
and fish models are identified as syntenic in Ambystoma. We
also report a close correspondence between the white color
variant locus and a protein-coding locus that maps to a
conserved synteny group between mouse and human. Thus, our
preliminary results suggest that an Ambystoma genomics
resource will provide a database from which to cross-reference
genetic information from salamanders to genetically wellcharacterized vertebrate models for the purpose of candidate
gene analysis and comparative genomics.
60
Making a hydrozoan planula: Cellular rearrangements during
gastrulation.
BYRUM, C.A. Univ. of Texas at Austin.
Although much is known about the formation of germ layers
in triploblasts, comparatively little is known about it in
diploblasts. This study looks at gastrulation in the hydrozoan
Phialidium gregarium. Like many cnidarians, Phialidium
gastrulates by unipolar ingression. Prior to gastrulation, the
blastula elongates and cells in the posterior (oral) portion of the
embryo become more columnar. At the onset of gastrulation,
cells move into the blastocoel, first filling the posterior areas and
then the anterior (aboral) areas. Cell marking studies showed
that most of the cells forming the endoderm are derived from
posterior portions of the blastula. Also, the overall length of the
embryo changes little during gastrulation, and cells in the
anterior and mid regions of the embryo do not change their
relative positions along the A-P axis. The ectodermal cells
probably maintain their positions because A) embryo width
decreases as gastrulation proceeds (caused by convergence of
cells), and B) cells in the anterior ectoderm become more
columnar. These observations are used to develop a model of
unipolar ingression and for comparison to modes of gastrulation
in other animals. 'NSF grant IBN-9513068 to G. Freeman.
11A
56
Amphi-Atlantic phylogeography of direct-developing Lasaea
(Mollusca: Bivalvia) lineages.
O'FOIGHIL, D. *, R. JENNINGS, and J.-K. PARK. Univ. of
Michigan, Ann Arbor.
58
61
64
Development of the reproductive system in Bulla striata
Bruguiere, 1792, and Acteocina atrata Mikkelsen &
Mikkelsen, 1984 (Gastropoda, Opisthobranchia).
DEMAINTENON, M.J." and P.M. MIKKELSEN. Univ. of Hawaii,
Hilo, and American Museum of Natural History, New York, NY.
The evolutionary and developmental genetic basis of wing
polymorphism in ants.
ABOUHEIF, E.* and G. A. WRAY. Duke Univ., Durham, NC.
62
Evolution of development in Crepidula (Gastropoda:
Calyptraeidae): Is the loss of feeding larvae irreversible?
COLLIN, R. Univ. of Chicago and The Field Museum, Chicago,
IL
The similarity of feeding larvae within families or classes of
marine invertebrates suggests that feeding larvae are ancestral
and that the transition to direct development, the derived state,
is irreversible. However, the frequencies of transitions between
modes of development are difficult to estimate. To examine the
frequency and relative probabilities of such transitions I
reconstructed the evolution of mode of development on a
phylogeny of Crepidula. The null hypothesis that the loss of
feeding larvae is irreversible cannot be rejected, however, neither
can the hypothesis that evolution of mode of development is
random with respect to phylogeny.
63
All compound eyes are not created equal: Opsin gene history
is consistent with a recent origin of myodocopid (Crustacea)
compound eyes.
OAKLEY, T.H. Duke Univ., Durham, NC.
Mapping characters on phylogenies is important and
increasingly popular for evolutionary inference. Though
undeniably important, these methods are sensitive to violations
of certain assumptions. It is therefore important to consider other
ways to test such hypotheses. I illustrate these ideas by
examining the history of arthropod compound eyes. Although
many researchers consider all arthropod compound eyes
homologous, two recent authors have postulated that those of
myodocopid ostracods have an independent origin. However,
this claim is highly sensitive to assumptions about character
evolution. I am therefore taking a step beyond character
mapping and using the history of eye structural genes,
photosensitive opsins, to test alternative hypotheses. I have
discovered three opsins from the ostracod Vargula hilgendorfii
that are more closely related to each other than to any known
non-ostraocod opsin. Furthermore, one of these genes is
exclusively expressed in the compound eye. The recent origin of
a compound eye-specific opsin is consistent with the recent
origin of compound eyes in myodocopid ostracods.
12A
65
Expression of homeobox genes during regeneration and
asexual reproduction in an annelid.
BELY, A. E.* and G. A. WRAY. Univ. of California at Berkeley,
and Duke Univ, Durham, NC.
Many animals are capable of non-embryonic forms of
development, such as regeneration and vegetative reproduction.
We are interested in how these non-embryonic forms of
development evolve. One approach we are taking is to determine
whether homeobox genes involved in embryogenesis are also
expressed during regeneration and vegetative reproduction. We
have isolated a homolog of the gene engrailed (PRIIe-en) and
two homologs of the gene orthodenticle (PRIIe-otx1 and -otx2)
from the annelid Pristina leidyi, an oligochaete that reproduces
by fission and has extensive regenerative abilities. In situ
hybridization studies show that during fission and regeneration,
these genes exhibit dynamic expression patterns in the newly
developing tissues. The expression patterns during regeneration
and fission are highly similar, supporting the hypothesis that
fission evolved by recruitment of regenerative developmental
processes. Some similarities are also apparent between these
non-embryonic expression patterns and the embryonic
expression of these genes in other annelids, suggesting that
non-embryonic forms of development may redeploy embryonic
pathways.
66
The evolution of polyphenic development and its
consequences: Rapid allometric divergence between exotic
populations of the scarab beetle Onthophagus taurus.
MOCZEK, A.P.* and H.F. NIJHOUT. Duke Univ., Durham, NC.
We examined the genetic and developmental underpinnings
of polyphenism evolution using populations of the polyphenic
beetle Onthophagus taurus. Adult male O. taurus vary in body
size in response to environmental conditions, and males that
exceed a critical body size develop a pair of spectacular horns
on their heads, while those smaller than this threshold remain
hornless. Several exotic O. taurus populations have diverged
dramatically in this critical threshold body size, which resulted in
substantial differentiation in body size-horn length allometries
between populations. Here we show that phenotypic
divergences between these populations are largely due to
genetic divergence in the developmental machinery responsible
for morph determination. Our data further suggest that these
divergences have evolved extraordinarily rapidly since the recent
establishment of these populations. Finally, we contrast the
endocrine control of morph expression in divergent populations,
and discuss the roles of (i) hormone sensitivity per se and pi) the
timing of hormone sensitivity during growth as the potential
developmental basis for allometry evolution.
Late development of the reproductive system was
investigated in two cephalaspid opisthobranchs, Bulla striata
BruguiEre, 1792 [Bulloidea] and Acteocina atrata Mikkelsen &
Mikkelsen, 1984 [Philinoidea]. Both species are monaulic
simultaneous hermaphrodites, with the 'female' gland mass and
'male' copulatory organ separate. Their adult reproductive
anatomies are similar, though the gross copulatory organ
anatomy of B. striata is much more complex. The female and
male portions of the anterior gonoduct develop separately as
ectodermal invaginations, apparently during the juvenile stage of
development. The invagination forming the female glandular
mass connects to the posterior gonoduct. The common genital
opening changes location during development in both species,
from an original position close to the pericardium to a more
lateral position closer to the right side of the body. The two
species also differ somewhat with regards to timing of
maturation of different reproductive organs. In both species, the
copulatory organ matures before the female glands.
Organogenetic timing in A. atrata is protandric however, with
male ducts and gonadal tissue fully developed (assuming full
functionality) before the female components; B. striata appears
to be a true simultaneous hermaphrodite, with male and female
systems maturing concurrently.
The eusocial behavior and wing polymorphism observed
between the different social castes in ants provide an excellent
system to study the developmental genetic basis of polymorphic
traits, such as the wing. We have cloned and sequenced three
members of the wingless gene family from the ant Pheidole
morrisi. One of these family members, Pheidole morrisi wingless
(Pmwg), is clearly the ortholog of Drosophila wingless. We
characterized the expression of this gene by in situ hybridization.
The results indicate that expression in the imaginal discs within
reproductive castes is similar to that in Drosophila. In the nonreproductive worker castes, however, the timing and presence of
Pmwg expression varies, being absent from minor workers and
being present in a later stage of the major workers. These data
are consistent with the hypothesis that natural selection may
play an important role in constraining and changing the
expression of the regulatory pathway that will give rise to the
wing. Also, these data are consistent with a model where wing
polymorphisms may be ultimately manifested by delayed
activation and repression in the wing developmental pathway.
67
The evolution and adaptive significance of sexual size
dimorphism in the polyembryonic parasitoid, Copidosoma
floridanum.
CORLEY.LS.", M.R.STRAND,and P.J.ODE. Univ. of Wisconsin,
Madison, and Texas A&M Univ.
Sexual size dimorphism (SSD) is assumed to be adaptive
and is expected to evolve in response to differences in natural
and sexual selection pressures. The polyembryonic wasp
Copidosoma floridanum exhibits SSD — females are significantly
larger than males (p=0.00003). We are examining how the
evolution of polyembryony in this wasp affects body size
evolution and what factors are important to SSD. We have
evidence that proliferation of the egg into the clonal individuals
comprising a brood is different for males and females and we will
investigate how these differences may affect SSD. Other factors
we examined are wasp brood type (single sex versus mixed
broods), genetic variation of the wasps, and host size.
68
Body size and the pace of embryonic development in
thamnophiine snakes.
VELHAGEN, JR., W. A. Longwood College. Farmville, VA.
69
Early cranial development in marsupial mammals: The
origins of heterochrony.
SMITH, K.K. Duke Univ., Durham, NC.
Marsupial young are bom at an extremely altricial state and
undergo most development while attached to the teat. Relative
to placentals, marsupial embryos accelerate the development of
certain bones of the facial region, most cranial musculature and
a few additional structures; they delay the development of
central nervous system structures, in particular the forebrain. In
this study I detail the early development of cranial and nervous
system features in the marsupial, Monodelphis domestica in
order to document the developmental origins of these
heterochronies. I show: 1) neural crest begins migration early
relative to neural tube development in marsupials; 2) the relative
amounts of neural crest to the facial region at an early stage of
development are large in marsupials relative to eutherians; 3)
hindbrain structures, including the appearance of rhombomeres
and the development of cranial motor nerves are accelerated in
marsupials, and 4) the development of the fronto-nasal
processes are advanced relative to forebrain development.
These results suggest that the heterochronies that distinguish
marsupials and placentals represent fundamental shifts in the
development of the mammalian body plan, and are not simply
terminal changes in rate.
70
On the constancy of morphological patterns: 7 cervical
vertebrae and the phylotypic stage.
GALIS F. Leiden Univ., The Netherlands.
Mammals have a very constant number of 7 cervical
vertebrae. The constraint on variation is hypothesized to be
caused by developmental constraints: changes in Hoxgene
expression which lead to changes in the number of cervical
ABSTRACTS
71
Evolutionary genetics of Danio pigment pattern
development.
PARICHY, D.M.* and S.L. JOHNSON. Washington Univ. Medical
School, MO, and Univ. of Texas at Austin.
Neural crest-derived pigment cells exhibit a diverse array of
pigment patterns in fishes of the genus Danio and we are using
these patterns as a model system for understanding the
evolution of morphology. Previous work identified two
melanophore populations in the zebrafish D. rerio; an early
appearing population that is ablated in the sparse mutant, and a
late appearing population that is ablated in the rose mutant. As a
first step in dissecting the development and evolution of these
populations we sought to identify the sparse and rose genes.
Here, we show that sparse corresponds to c-Mf, whereas rose
corresponds to endothelin receptor B, two genes long studied
for roles in amniote pigment pattern development. Finally, we
show that the D. rerio mutant panther lacks stripes, and that
panther or the pathway in which it acts may have contributed to
the evolutionary loss of stripes in D. albolineatus. Unexpectedly,
we find that panther corresponds to c-rms, which is the closest
known homologue of c-Wf, and has not previously been
suspected to have a role in pigment pattern development.
72
Cranial neural crest migration in the Australian lungfish,
Neoceratodus forsteri.
OLSSON, L*, P. FALCK, and J. JOSS. Uppsala Univ., Sweden
and Macquarie Univ., Sydney, Australia.
A crucial role for the cranial neural crest in head
development has been established in actinopterygian fishes as
well as in tetrapods. It has however been claimed that the neural
crest is unimportant for head development in the Australian
lungfish (Neoceratodus forsteri). Here we report scanning
electron microscopy results showing that although cranial neural
crest cells start migrating very late (after neural fold closure) in
the lungfish the pattern of emergence and migration closely
resembles that seen in amphibians particularly in the Mexican
axolotl. These descriptive studies will be extended to include
experimental studies (ablation of selected streams of neural crest
cells) and fate mapping (using fluoresent tracer dyes such as Dil)
to document the normal fate as well as the role in head
patterning of the cranial neural crest in the Australian lungfish.
Supported by the ARC (to JJ and LO)."n
73
Comparative patterns of neural crest development in
cartilaginous and bony fishes.
MIYAKE, T.*, J. L. VAGLIA*. and B. K. HALL. Dalhousie Univ.,
Halifax, Canada.
The neural crest (NC), the fourth germ layer of craniates,
gives rise to many structures. We summarize comparative data
from our studies and from the literature on modes of neurulation
and migration and patterning of NC in cartilaginous and bony
fishes. Neurulation differs among fishes: open neural tube
formation in cartilaginous and some bony fishes; neural keel
formation in other bony fishes. In contrast to amphibians, cranial
13A
To determine whether embryos of closely related species of
different body size develop at unequal rates, data on size and
developmental stage were obtained from embryos and neonates
of eight thamnophiine snakes and two other colubrid snakes.
Because previous work had shown that snake embryos grow
linearly, embryo size relative to species neonate size was used
as a measure of developmental time. Species were compared to
determine whether embryos at the same developmental stage
were at the same relative age. Analyses showed that within most
stages, embryos of smaller species were relatively larger, and
hence further along in their gestation period, than embryos of
larger species. This implies that, compared to large species,
small species take relatively longer in their ontogeny to reach a
given stage. Thus, the pace of development appears to vary with
size, and stages are not entirely equivalent across species
because they represent different ages.
vertebrae are associated with an increased susceptibility to
neonatal cancer. In vertebrates Hoxgenes are involved in the
development of vertebrae and also in the proliferation of cell
lines. Several types of cancer are associated with abnormal
Hoxgene expression. In embryonal tumours the incidence of a
cervical rib (a homeotic change of C7 towards T1) is increased
more than 100-fold. The high probability for neonatal cancer in
cervical rib phenotypes (12%) is the minimal estimate of the
selection coefficient against these mutations. In birds and
reptiles the number of cervical vertebrae is not constrained. In
birds and reptiles the susceptibility to cancer appears much
lower than in mammals and this probably prevents the
pleiotropic effect of neonatal cancer. The hypothesized coupling
in mammals between the development of a cervical rib and
diseases was investigated using phenocopies of Hoxgene
mutations. Implications for the constancy of the phylotypic stage
are discussed.
neural crest (CNC) cells do not migrate as discrete streams in all
fishes. Trunk neural crest (TNC) cells migrate over the midsomitic region rather than over the rostral half of each somite. In
cartilaginous fishes as in rodents, CNC cells migrate from the
most rostral region of the forebrain. HNK-1 antibody recognizes
migrating NC cells and identifies NC derivatives such as
trigeminal ganglion in cartilaginous and most bony fishes. Some
populations, e.g., pigment cells, exhibit tremendous plasticity
during development and/or regulation. Such morphogenetic
diversity reflects the central role of NC in the evolution of fish
morphology. Supported by NSERC, SICB, AMNH, Sigma Xi.
74
HOX gene evolution among telosts.
STELLWAG, E.J.*, J.-L. SCEMAMA, Y. A. MOHAMUD, and
S.PARKER. East Carolina Univ., Greenville.
75
Comparative anuran development: Going beyond Xenopus.
CHIPMAN, A.D. The Hebrew Univ. of Jerusalem, Israel.
Comparative embryology is recognized as an important tool
in studies of the evolution of development. Comparing the
developmental sequences of different species can shed light on
how the developmental program of these species has evolved.
However, such comparison are often done using arbitrary
stages, rather than concentrating on specific, identifiable events.
A comparative study was carried out using 10 anuran species.
Embryos of these species were compared regarding the relative
timing of a number of important events in their embryogenesis,
using histological markers on serial sections of embryos, and
external morphology on time lapse video sequences. These
comparisons differentiate between a number of developmental
modules with varying degrees of coupling between them. The
dimensions of a number of embryological structures were
measured using computerized image analysis and compared
among the different species to find differences in size and
shape. Although the Anura is a relatively conservative group,
subtle differences found in the development of different species,
provide data for learning about the evolution of anuran
development, and shed light on the developmental processes
themselves.
76
Monophasic development of the spinal cord in direct
developing frogs.
SCHLOSSER, G.* and C. KINTNER. Univ. of Bremen, Germany,
and Salk Institute, San Diego, CA.
Spinal cord development in most amphibians is biphasic:
there is an early peak of neurogenesis during gastrulation and a
later peak during larval stages, with an intervening quiescent
period of little proliferation and neuronal differentiation. We show
that in Xenopus, several markers of neurogenesis (X-NGNR-1,
XNeuroD, XMyT1, and X-Delta-1) are expressed during both
peaks suggesting that regulation of neurogenesis relies at least
partially on similar mechanisms. This spatiotemporal pattern of
neurogenesis has been altered in the spinal cord of the direct
developing frog Eleutherodactylus coqui, which has lost a freeiiving iarval stage. In £ coqui spinal cord, neurogenesis
proceeds without an intermittent quiescent period: while
14A
77
Morphospace and disparity approaches to development and
evolution.
EBLE, G.J. Smithsonian Institution.Washington, DC.
Morphospace and disparity profiles in a number of groups
have consistently suggested large-scale inhomogeneities,
expressed as apparently nonrandom distributions of
morphologies within clades and through time. This in turn has
usually been interpreted in terms of constraint. Contrasts
between morphological disparity and taxonomic diversity can
suggest the existence of constraint, and when tied with
environmental and functional information can lead to the
identification of selective constraints. In contrast, developmental
constraints have received less attention in this context.
Developmental data can suggest to what extent developmental
constraints are involved, but this demands a change in
conceptual framework. The notions of developmental disparity
and developmental morphospaces (defined by incorporation of
developmental data) are here illustrated as a means of .
approaching issues such as clade shape in ontogenetic time,
general changes in rate and timing, testing of developmental
laws and links between phylogenetic and ontogenetic trends.
Morphometric data from echinoids and hominoids are used to
illustrate these approaches.
78
Population genetics and microevolution of developmental
mechanisms.
NIJHOUT, H. F. Duke Univ., Durham, NC.
Evolutionary developmental biology has focused largely on
(macroevolution and the) analyses of the phylogenetic patterns
of developmental events. Studies in this field have been
concerned with the identification of primitive (conserved) and
derived genetic mechanisms, and with the analysis of patterns of
divergence of gene expression, genetic regulation, and
morphogenesis (in different taxa). In order to understand the
evolution of development it is also necessary to understand (it at
the microevolutionary level. This can be done by examining) how
the fundamental mechanisms of evolutionary change: mutation,
selection, and drift, affect the genetic mechanisms of
development. Such an understanding depends, in part, on
developing methods for studying the association between
natural genetic variation and variation in developmental
processes. We have begun to develop theoretical methods for
studying the population genetics of developmental mechanisms,
and have been using these methods to study how
developmental systems respond to selection. Our results show
that selection on the phenotype can result in non-intuitive
changes at the level of the genotype. Our results help to explain
the variable and inconsistent con-elation between specific genes
and the heritable properties of complex traits, and suggest
methods by which such correlations can be predicted.
79
Assessing the causes of evolution of development: The role
of functional morphology.
BUDD, G.E. Univ. of Uppsala, Sweden.
Recent interest in mechanisms of metazoan evolution have
focussed on the role of relatively high-level genetic changes
causing a cascade of changes to occur in down-stream genes
and gene networks. These sorts of approaches suffer from
several flaws, including failing to give a functionally continuous
account for the origin of novelty, ignoring the only loose
correlation between genomic and morphological complexity, and
by ignoring the external events that provide a backdrop to all
adaptive radiations. An outline model for the opposite direction
The study of Hox gene evolution among vertebrates
continues to serve as a paradigm for those interested in
vertebrate genome evolution and development. Recent exciting
discoveries about Hox gene composition in fishes, together with
re-examination of known Hox gene relationships, challenges
conventional views about vertebrate Hox gene evolution, and has
initiated lively debates concerning the evolutionary events
marking the divergence of the major vertebrate lineages. Based
on comparative genomic analyses of Hox genes from several
actinopterygian species, including zebrafish, pufferfish, medaka,
killifish, and striped bass, we propose alternative models for the
evolution of teleost Hox gene clusters. These models, which
postulate that basal actinopterygians possessed either four or
eight Hox gene clusters, provide alternative hypotheses for the
evolutionary history of a key developmental regulatory gene
cluster.
neurogenesis in the spinal cord of likewise starts during
gastrulation, massive proliferation (assessed by an antibody
against proliferating cell nuclear antigen) and neuronal
differentiation (revealed by in situ hybridization against
EcNeuroD) continue throughout early embryogenesis, correlated
with the early development of the limbs. We currently investigate
if thyroid hormones may play a role in this modulation of the
timing of neurogenesis in frogs.
of causality is proposed here, wherein (for example) genome
duplications and other high-level events are only favoured (and
thus retained) in lineages that had already diversified
morphologically. This analysis suggests that the new field of
'evolution of development' may need to import theory from
functional morphology and population genetics before a
satisfactory account of developmental change through time can
be developed.
80
Teleost HOX clusters and vertebrate genome evolution.
AMORES, A.* and POSTLETHWAIT, J.H. Univ. of Oregon,
Eugene.
81
T-box genes and the evolution of paired vertebrate
appendages.
RUVINSKY, I*, J.J. GIBSON-BROWN, A.C. OATES, R. K. HO,
and L. M. SILVER. Princeton Univ., NJ.
Modern jawed vertebrates possess two sets of paired
appendages. The specific molecular genetic events associated
with their origin remain enigmatic. Recently we suggested that
certain T-box genes, transcription factors playing essential roles
in vertebrate embryogenesis, were involved in the transition from
a limbless ancestral chordate into a modern vertebrate with two
sets of paired appendages. In tetrapods, Tbx5 and Tbx4 are
expressed in the fore- and hindlimb fields, respectively, prior to
the initiation of limb bud formation, and are likely to be
responsible for determining limb identity. We will demonstrate
that, prior to the advent of jawed vertebrates, these two genes
diverged from a common ancestral locus within the vertebrate
lineage. Comparative developmental data indicate that limbrelated gene functions were first established, and subsequently
maintained, shortly following gene divergence. We will propose a
model, which incorporates palaeontological, developmental, and
genetic data, to argue that gene duplication followed by
differential regulation of these genes was a major driving force in
the evolution of paired vertebrate appendages.
82
The mitochondrial genome of the rotifer Brachionus
plicatilis.
GAREY, J.R.* and M.S.ROBESON II. Univ. of South
Florida.Tampa.
There are no published sequences of the complete
mitochondrial genome from a rotifer. The mitochondrial genome
of different isolates of the rotifer Brachionus plicatilis vary in size
from 16-26 kilobases (kb). We have sequenced 12 kb from an
isolate with a genome totaling 20 kb. A contiguous 6 kb stretch
contains the genes for 11 tRNAs as well as two rRNA genes and
4 protein coding genes (NADH dehydrogenase 1, NADH
dehydrogenase 2, ATPase 6, and cytochrome b). The remaining
6 kb that we have sequenced appears to be non-coding. The
expansion or contraction of this non-coding region may account
for the variation in mitochondrial genome size from different
ABSTRACTS
83
Gene conversion and natural selection drive hsp70 molecular
evolution.in Drosophila.
BETTENCOURT, B.R.* and M.E. FEDER. Univ. of Chicago, IL.
Both the expression level and organismal phenotype of
Hsp70, the principal inducible heat-shock protein of Drosophila
melanogaster, respond to natural selection. To determine now
the five hsp70 genes (two at chromosomal locus 87A7, three at
87C1) coevolve with this response, we sequenced multiple
alleles of each gene. Two forces shape nucleotide variation at
the hsp70 loci. First, gene conversion both homogenizes
sequence and transfers motifs among the genes. A "snapshot"
of this process is at the 87C1 locus, where conversion transfers
a 7 base insertion among the 5'-UTRs of specific alleles of each
gene. Second, selection maintains much of this diversity in
natural populations as balanced polymorphisms. These include
two segregating types of the 87A7 locus. The types differ by a
large intergenic insertion and differential conversion tracts in
coding and 3'-UTR sequence. Frequencies of these and other
alleles respond to natural and laboratory selection. The
combined forces of conversion and selection thus fuel rapid
concerted evolution by propagating nonneutral mutations among
loci in an allele-specific fashion. Supported by NSF and HHMI.
84
A combined cladistic analysis of the Naticidae (Mollusca:
Gastropoda): Assessing their phylogenetic position within
the Gastropoda.
ARONOWSKY, A. Univ. of California at Berkeley.
The Naticidae are a family of marine prosobranch
gastropods. They have been important drilling predators since
the early Triassic. Their classification has been hampered by
morphologic homogeneity and a lack of molecular studies.
Naticids never been included in published molluscan
phylogenies and their position within the Gastropoda is
uncertain. To determine their placement, 18 extant naticid taxa
were analyzed. Two archaeogastropod, four neogastropod, and
12 mesogastropod taxa were used as outgroups. Forty-one
conchological, anatomical, and radular characters were used in
the analysis run with PAUP 4.0b2. This first cladistic analysis of
the Naticidae tentatively establishes the relationships among the
four naticid subfamilies and the position of the family relative to
the outgroups. Future work involves the addition of molecular
data, primarily in the form of 16S, 18S, and 28S rRNA
sequences.
85
A developmental model for the evolution of trophotaeniae in
viviparous fishes.
WOURMS.J.P.* and G.ULUKOY. Clemson Univ., SC.
Trophotaeniae are external gut derivatives that function in
maternal-embryonic transport. In early development.surface
ectoderm fails to invaginate and fuse with the gut to form a
proctodeum. Instead, the hindgut fuses with the body surface to
form a vent whose vestibule is lined with endoderm. Absence of
a proctodeum eliminates the interface between hindgut and
proctodeal compartments. The hindgut terminus loses positional
identity and is no longer constrained from posterior extension.
Hindgut cells grow out of the vent to form an external perianal
peduncle.Prototypic trophotaeniae develop from primordia in the
peduncle. Trophotaenial development is accelerated relative to
the gut and embryo. Patterns of mitosis control trophotaenial
morphogenesis. Cells of ribbon trophotaeniae and hindgut
differentiate as endocytotic cells and rosette types produce
transport cells (hyperdifferentiation or expression of different
identity?). At birth.osmotic shock triggers ecdysis of
trophotaeniae. Surface epidermal cells extend into the vent and
15A
Hox genes encode a family of closely related transcription
factors that are involved in the establishment of regional identity
along the body axis. Invertebrate chordates have one Hox
cluster, but tetrapods have four clusters (A-D) that are thought to
have originated by genome duplication. To investigate the role of
genome duplication in the evolution vertebrates, we screened
PAC genomic libraries from zebrafish {Danio rerio) and pufferfish
(Spheroides nephelus ) by PCR using degenerate primers for the
homeobox. Chromosome walks revealed seven Hox clusters in
zebrafish and at least five Hox clusters in pufferfish. Phylogenetic
analysis showed that zebrafish has duplicates of each of three of
the mammalian Hox clusters and pufferfish has duplicates of at
least one of the mammalian Hox clusters. The mapping of the
seven zebrafish Hox clusters along with paralogous copies of
other gene families is consistent with the model that a third
chromosome duplication event not shared with tetrapods gave
rise to the present Hox cluster organization in zebrafish.
Comparison of sequence and Hox cluster organization between
zebrafish and pufferfish suggest that this duplication event
occurred before the teleost radiation.
isolates. We are currently PCR amplifying and sequencing the
remaining 8 kb of the genome. The order of the genes and the
sequences of the genes will provide phylogenetic information to
help elucidate the relationship of rotifers to other metazoans. The
sequence of this genome will make it easier to PCR amplify
mitochondrial genes from other rotifers, facilitating studies of the
evolutionary relationships among rotifers.
convert it into a proctodeum.Evolution involves paedomorphic
(postdisplacement of proctodeum formation)and peramorphic
(accelerated growth of trophotaeniae) processes(Supported by
NSF)-
specifics of which agree with the relationships found in
saurischian dinosaurs. Neognaths possess similar patterns but
have interesting deviations possibly related to the reduction of
the maxilla and rearrangement of the palate.
86
89
CT (Computerized X-Ray Tomography) provides new views
of the swim bladder of butterflyfishes (Perciformes:
Chaetodon) with a novel specialization of the lateral line
system.
WEBB, J.F.*, W.L SMITH, and D.R. KETTEN. Villanova Univ.,
PA, and Woods Hole Oceanographic Institution-Harvard Medical
School, Boston, MA.
Comparative histology, growth, and evolution of
archosaurian osteoderms: How Stegosaurs got its plates.
MAIN, R.P' and K. PADIAN. Univ. of California, Berkeley.
87
The evolution of batoid locomotion.
ROSENBERGER, L J . Univ. of Chicago and Field Museum of
Natural History, Chicago, IL.
The recent integration of functional morphology with
phylogenetic data is creating a renaissance in our view of
functional evolution. Comparative methods using current higher
level phylogenies for batoids (skates, stingrays, and relatives)
reveal the evolutionary patterns of locomotion within this unique
and diverse group of fishes by tracing morphology and kinematic
behavior. Batoids exhibit three broadly categorized locomotor
modes related to their lifestyles including axial-based locomotion
(shark-like), undulation of the pectoral fins (waves propagated
down the fins), and oscillation of the pectoral fins (bird-like
flapping). Character states related to locomotion that tend to
correlate with each other are high fin beat frequency, high wave
number, low fin amplitude, low aspect ratio and a benthic
lifestyle versus low frequency, low wave number, high amplitude,
high aspect ratio and a pelagic lifestyle. In general, the evolution
of locomotion within batoids moves from axial-based to
combination of axial and pectoral undulation to strictly pectoral
undulation to pectoral oscillation. Pectoral undulation has
independently evolved at least three times, and pectoral
oscillation may have evolved at least twice in this group of
fishes.
88
Cephalic vasculature in Archosauria, with special emphasis
on the nasal region.
SEDLMAYR, J.C.* and L.M. WITMER. Ohio Univ., Athens, and
College of Osteopathic Medicine, Athens, OH.
Cephalic blood vasculature is a critical anatomical system,
involved in nutrient supply, physiological processes such water
economy and heat and gas exchange, and development and
patterning of the head. It is thus surprising that head vasculature
remains poorly understood in extant archosaur clades, not to
mention extinct groups such as dinosaurs. Using the extant
phylogenetic bracket approach, head vasculature in birds and
crocodiles has been studied to elucidate homologous structures.
Vascular structures commonly form osteologica! correlates which
allow for soft-tissue reconstruction in fossils. Our research
suggests a vascular interpretation for the functionally enigmatic
subnarial canal of saurischian dinosaurs. Within the narial cavity,
crocodiles and ratites have a similar system of anastomoses
between palatai, maxillary, and dorsal nasal vessels which are
related to the blood supply of the nariai cavernous tissue.
16A
90
Acoustically Innovative lineages: The distribution of sound
producing mechanisms among teleost fishes.
KAATZ, I.M.* and D.S. STEWART. Boston Univ. Marine Program,
Woods Hole, MA, and State Univ. of New York, Syracuse.
The distribution of acoustic vs. silent fishes has not been
considered from a phylogenetic perspective. We reviewed the
sound producing capabilities of teleost fishes based on the
presence of sound producing mechanisms (SPMs) and
behavioral evidence. We present a classification for SPMs of
fishes. We identified 520 species as acoustic. These species
represent 96 families (23% of described families). We identified
15 orders as silent and 21 as acoustic. Several orders included
species with multiple, non-homologous SPMs. We describe
these groups as acoustically innovative lineages:
scorpaeniformes, siluriformes, in the order perciformes the
suborder percoidea and tetraodontiformes. Hypotheses have
been proposed in the literature regarding the association of
acoustic fishes with different habitats. We compare acoustic with
silent lineages with respect to their habitat association (marine
vs. freshwater) and ecotype (benthic, benthopelagic or pelagic).
We found a significant number of acoustic families to be
represented by benthopelagic famlies.
91
Caudal morphology in plethodontid salamanders.
DICKIE, R. Univ. of California, Berkeley.
Although the tails of plethodontid salamanders have been
modified in a diversity of ways and perform a variety of different
roles across taxa, relatively little is known of caudal structure or
function in this group. I focus on one aspect of locomotory
function, prehensility, and its interrelationship with tail
morphology and ontogeny. Prehensility has evolved convergently
within the plethodontids, and prehensile ability cannot be
predicted by arboreal habit. Comparative morphology within this
clade was investigated using a combination of gross dissection,
histology, and immunohistochemistry. Specializations for
prehensility, though subtle, are found in the vertebrae and
musculature, and both development and growth impact
prehensile ability.
The laterophysic connection (LC) is a unique swim bladderlateral line linkage in Chaetodon, which we have examined
histologically in 21 spp.; 2 LC types including 7 variants have
been defined. Radiographic and gross morphological
examination of the swim bladder in fixed material reveals that
swim bladder morphology is correlated with LC type. CT was
used to clarify aspects of swim bladder morphology subject to
fixation and histological artifacts. Anaesthetized fishes from
representative Chaetodon species were scanned using an ultrahigh resolution sub-millimeter spiral protocol. Imaging of slices
and 3-D reconstruction clearly documents horn and swim
bladder shape, and the relationship of the swim bladder to the
axial skeleton in living fishes, confirming interpretations derived
from histological and whole fixed material. Supported by NSF
IBN-9603896 to J.F.W. and a Seaver Institute grant to D.R.K.
The mostly flat dorsal scutes of Pseudosuchia (crocodiles,
phytosaurs, aetosaurs) grow by periosteal deposition and by
external and internal remodeling. The dorsal and lateral scutes of
Scutellosaurus, a basal thyreophoran (ankylosaurian and
stegosaurian dinosaurs), grew in much the same way. The flat,
parasagittal vertical plates and elongated spikes of stegosaurs
grew mostly by basal osteogenesis with some lateral periosteal
deposition and extensive internal remodeling. Hence, the plate
"evolved" by hypertrophic growth of the parasagittal dorsal keel
of basal thyreophoran scutes. Medullary "pipes" and surface
grooves reflect the course of vascular canals that have
implicated the plates in thermoregulatory functions. However,
their ontogeny and phylogenetic variability imply a more
consistent role in display or species recognition. Stegosaur
plates are histologically similar to some dinosaurian cranial frills
and platelike girdle bones, suggesting growth regimes related to
constructing large flat bones rather than to thermoregulatory
function.
92
individuals over their lifetimes and populations over evolutionary
time, leads to changes in rates of evaporative water loss.
Osteology and evolution of the avian reversed hallux.
MIDDLETON, K.M. Brown Univ., Providence, Rl.
The perching foot of birds is characterized by an opposable
first digit (reversed hallux). Analysis of hallucal morphology in
extant birds with different degrees of reversion revealed two
primary con-elates of orientation. 1. Metatarsal I shows a torsion
of its shaft, reorienting the distal tubercula; torsion increases in
conjunction with hallucal orientation angle. 2. The metatarsal I
fossa varies in position, reorienting the digit as a whole. These
characteristics can be identified in skeletons of extant birds and
thus should allow determination of hallucal orientation in fossil
birds. Since the discovery of Archaeopteryx, the orientation of
the hallux in Mesozoic birds has remained of significant interest.
The preserved position of the hallux has been used as the only
determinant of hallucal orientation in fossil birds. The presumed
presence of a reversed hallux in Archaeopteryx has been used to
infer a 'trees-down' origin of flight. However, preserved
appearance is subject to potentially unknown biases in the
taphonomy of three-dimensional structures. For example, a digit
which is partially reversed or unreversed could be preserved in a
reversed orientation. The methodology presented here avoids
misinterpretations due to preservation.
93
Independent invasions of fresh water Comparison of sodium
pumping ability among lineages of the copepod Eurytemora
affinis.
LEE, C. E. Univ. of San Diego, CA.
The invasion of fresh water has occurred at least eight times
independently in the sibling species complex Eurytemora affinis.
These independent invasions offer replicated tests for
investigating physiological and biochemical changes that occur
during habitat transitions. Because the lineages are closelyrelated and form a polytomy, this system is ideal for applying the
comparative method. Lineages vary in their tolerance to low
salinity, and in the occurrence of freshwater descendents. I
examined Na, K-ATPase activity in nine populations from four
genetically divergent lineages (or subspecies) at four salinities,
ranging from 1 to 25 PSU. Activity of this sodium pump changed
in response to changes in salinity. Response varied among
populations, with some populations varying activity of the pump,
while others keeping it fairly constant. I am in the process of
examining the relationship between physiological and
biochemical traits and variation among lineages in their
propensity to invade fresh water, to gain insight into the
evolution of body fluid regulation during habitat transitions.
94
Comparison of acclimatory and evolutionary changes in
water balance physiology of larval Manduca sexta.
WOODS, H.A.* and J.F. HARRISON. Arizona State Univ., Tempe.
An important goal of physiological ecology is to understand
the relation between time scales of physiological and
environmental change. We examined responses of larval
Manduca sexta to water stress over three time scales: during the
day following a switch from high- to low-water food, after
chronic exposure to high- and low-water diets, and over
evolutionary time. Larvae switched acutely from high- to lowwater diet rapidly doubled the rate of water recovery by the
rectum but did not show changes in evaporative water loss. In
contrast, larvae exposed from hatching to low-water diet had
33% lower rates of evaporative water loss but did not show
additional increases in rectal water absorption. We also
examined M. sexta from two geographic regions, North Carolina
(mesic) and Arizona (xeric), that had been reared in a common
garden. Larvae from AZ had 25% lower rates of evaporative
water loss than those from NC. These data suggest that
caterpillars counter short-term water stress by altering rectal
water absorption, but that longer-term water stress, for
ABSTRACTS
Influence of varying egg water exchange during different
trimesters of incubation on eggs and hatchlings of snapping
turtles (Chelydra serpentina).
RIMKUS, T.A.* and R.A. Ackerman. Marymount Univ., Arlington,
VA.
The influence of alternating intervals of egg water uptake and
egg water loss on the eggs and hatchlings of snapping turtles
was examined by exposing incubating eggs to sand media at
two different water potentials (wet, -7 kPa; dry, -1007 kPa) for
intervals equal to one third of incubation. Treatments ranged
from WWW (-7 kPa throughout) to DDD (-1007 kPa throughout)
with all possible combinations of wet and dry trimesters (8
treatments total). Egg water exchange ranged from a net loss of
3% in the treatment where eggs were exposed to the dry
condition throughout incubation to a net gain of 35% when eggs
were held under the wet condition throughout incubation. Egg
water exchange was significantly (p=0.0002) influenced by the
number of dry trimesters, with each dry trimester producing
about a 10% loss in mass. Eggs that were held under dry
conditions during the final trimester had the greatest water loss.
Hatchling size was significantly (p=0.0153) effected by the
treatments, with the smallest hatchling associated with driest
condition (DDD) but the number of dry trimesters encountered
was also significant (p=0.0135), such that an increase in dry
trimesters lead to smaller hatchlings. The timing of the dry
trimester significantly (p=0.0007) influenced hatchling size, such
that a dry exposure in the first trimester had the greatest effect
on overall size.
96
Organ mass and aerobic performance in house sparrows.
CHAPPELL, M.A.*, C. BECH, and W.A. BUTTEMER. Univ. of
California, Riverside, Univ. of Trodheim, Norway, and Univ. of
Wollongong, Australia.
Maximum aerobic performance during exercise (V02max)
may be limited by peripheral effectors, central supporting
organs, or both in concert ('symmorphosis'). We used individual
variation in performance and organ mass to evaluate these
models in house sparrows (Passer domesticus). We also tested
whether birds with high V02max also had elevated basal
metabolism (BMR), as might be expected if both are linked to
organ mass. Freshly-captured birds were exercised to V02max,
after which BMR was measured. Adults had higher V02max and
lower BMR than juveniles. In both age classes, VO2max was
correlated to the mass of the major peripheral effector (breast
muscle) and to the central organ most closely associated with
oxygen transport (heart). These findings are consistent with the
symmorphosis concept for V02max. BMR was strongly
correlated to several central organs (gut, liver, kidney) and to
breast muscle. There was a positive correlation between BMR
and V02max in juveniles, but not in adults or in the pooled data.
Taken together, our data indicate that house sparrows can
achieve elevated V02max without paying a 'penalty' in the form
of increased BMR.
97
Intraspecific scaling and physiological plasticity in relation to
variable demands during migration in the western sandpiper.
GUGLIELMO, C.G.* and T.D. WILUAMS. Simon Fraser Univ.,
Burnaby, Canada.
Migratory birds offer an excellent natural model system to
study the design of physiological systems relative to the peak
loads placed upon them. During migration seasons Western
Sandpipers (Calidris maun) face elevated demands for
hyperphagia to allow for rapid mass deposition at stop-overs,
and for endurance exercise capacity to ensure successful
migratory flights. In this study we explore how the functional
capacity of 'digestive' and 'exercise' components are adjusted
seasonally in relation to migration, and determine if modulation is
made in anticipation of future need or simply as a response to
increased use (training effects). We exploit the wide variation in
17A
Topic in Integrative and Comparative
Morphology
95
body masses and organ sizes in this species to study
intraspecific scaling rules, and discuss how they differ from
those obtained in interspecific studies. We use multivariate
analysis and scaling to explore the sub-structuring of organs
within the broad categories of 'digestive' and 'exercise'
components.
releasing hormone were observed in the torus. Neuropeptides
and neurotransmitters located in the torus likely influence
processing of incoming auditory information in the frog midbrain.
Supported by NSF #IBN95-14305.
98
The role of radiation receptors in the predatory behavior of
anacondas.
SMITH, T. L* and K. V. KARDONG. Washington State Univ.,
Pullman.
Digestive and osmoregulatory traits in phyllostomid bats: A
phytogenetic exploration.
SCHONDUBE, J. E.* and L. G. HERRERA. Univ. of Arizona,
Tucson, and Universidad Nacional Autonoma de Mexico, Distrito
Federal.
Anacondas lack distinct facial pits similar to pythons and pit
vipers. Consequently, it is assumed that anacondas adopt a
predatory lifestyle dependent on other routes of proximate
stimuli, visual and tactile. However, anacondas may possess
diffuse infrared receptors within labial scales. To test these
possibilities, mice were presented to anacondas under four
treatments: baseline (nothing covered), eyes covered, labial
scales covered, both labial scales and eyes covered. We found
that anacondas with baseline treatments struck prey sooner, and
from a greater range then when blindfolded (visual). However,
overall the predatory performance under the blindfolded
treatment was equivalent to the baseline treatment and tactile
contact with the prey was not necessary for a successful strike.
In the absence of input from eyes (visual) and labial scales
(infrared), predatory performance dropped significantly. If a strike
occurred, it was after tactile contact. We conclude that
anacondas are using infrared and/or tactile cues, but secondary
to visual cues in their predatory behavior. Furthermore
anacondas evaluate sensory stimuli in a hierarchical system
switching between proximate stimuli based on the availability of
sensory input.
99
102
Nitric oxide in the central nervous system of the opisthobranch Melibe leonina.
NEWCOMB, J.M.* and W.H. WATSON, III. Univ. of New
Hampshire, and Center for Marine Biology, Durham, NH.
Are seasonal variations in salamander chemoreceptor
epithelia related to their behavior?
DAWLEY. E.D.', D.S. HWANG, AND S.S. JOHN. Ursinus College,
Collegeville, PA.
Our goal was to determine if nitric oxide synthase (NOS) is
present in the central nervous system (CNS) of Melibe leonina
and to investigate its role. NADPH-diaphorase histochemistry
was used to detect NOS activity in 2 nerve cells in each
cerebropleural ganglion. Their axons pass into the pedal ganglia,
where swim interneurons (SINs) and motorneurons (SMNs) are
located. The NOS-positive cells did not stain in control
preparations with NAD+ and L-NAME. Immunohistochemical
staining with NOS-antibodies confirmed these findings. To
determine if nitric oxide (NO) plays a role in swimming,
intracellular recordings were obtained in isolated brains and
semi-intact preparations before and during application of the NO
donor sodium nitroprusside (SNP). Normally, SINs and SMNs
burst rhythmically with a cycle of about 2-4 seconds. In isolated
brains, SNP caused the rhythm to slow considerably and in
semi-intact preparations, this manifested itself behaviorally as a
decrease in the rate of swimming. These data indicate that NO is
present in the CNS of Melibe leonina and that it may play a role
in modulation of swimming. Supported by an NIH grant to WHW.
A wealth of behavioral and ecological studies have revealed
that red-backed salamanders (Plethodon cinereus) can be
reproductively active from fall through spring but maintain
territories during the stressful summer period. Chemoreception
mediates these seasonal activities. We have investigated
changes in the chemoreceptor epithelia of adults throughout the
year, hypothesizing that this epithelia may be flexible and its
morphology may correlate with seasonal changes in functions of
the chemoreceptor system. Vertebrates generate new receptor
neurons in response to death of functioning receptors. We
measured the rate of receptor cell division throughout the year.
During the entire mating season, new chemoreceptor cells are
generated at a very low rate. In May, receptor cell division rate
increases significantly. While the low rate of receptor renewal
throughout most of the year probably is in response to the death
of old receptors, we speculate that the up-regulation of
receptors in May is an adaptation that provides new receptors
for specific activities. This research was supported by grants
from NSF, HHMI, the Whitehall Foundation, and Ursinus College.
100
103
Immunocytochemical distribution of neurochemicals in the
auditory torus semicircularis of the bullfrog, Rana
catesbeiana.
HOLLIS, D.M.* and S.K. BOYD. Univ. of Notre Dame, IN.
Functional units of a compound nose: Aesthetasc sensilla
house similar populations of olofactory receptor neurons on
the antennule of spiny lobsters.
CATE, H.S.-, P. STEULLET, C D . DERBY, and W.C. MICHEL.
Georgia State Univ., Atlanta and Univ. of Utah, Salt Lake City.
Although electrophysiology of the auditory torus
semicircularis of anurans has been well-described, the
neurochemical modulators of the torus are not well known. We
used immunocytochemistry to locate several neurochemicals in
the torus of male bullfrogs, Rana catesbeiana. Extensive staining
of cell bodies for gamma-aminobutyric acid (GABA) was
observed in the laminar nucleus of the torus, while scattered
staining was found in the principal nucleus (especially caudal
regions). Small populations of neuropeptide Y-immunoreactive
cells and fibers were observed in the medial torus and scattered
fibers were seen in the principal nucleus. Arginine vasotocin
fibers were observed in the laminar nucleus. Neither cells nor
fibers for chicken-ll or mammalian forms of gonadotropin-
18A
The lateral flagellum of the antennule of the spiny lobster
Panulirus argus houses more than 1000 morphologically similar
olfactory sensilla, called aesthetascs. Using activity labeling, we
examined the distribution of different functional types of olfactory
receptor neurons (ORNs) in mature aesthetascs. A significant
number of ORNs in mature aesthetascs are labeled by single
odorants. The % of ORNs labeled averaged 0.5-1.6% for single
compounds and 4.6% for a 33-component mimic of oyster. The
% of ORNs labeled by a given odorant was statistically
homogeneous across most aesthetascs. The extent of
heterogeneity among mature aesthetascs was correlated with
their age: extensive heterogeneity was observed only in the
Contrasting diets pose constrasting physiological challenges.
Nectar and fruit diets contain large amounts of carbohydrates
and water and low amounts of protein whereas carnivorous diets
are rich in protein. We correlated diet with the digestive and
renal characteristics of 18 species of phyllostomid bats. We used
the nitrogen isotopic composition of blood (Delta15N) as an
estimate of trophic level. Delta15N differed significantly among
diets and increased with trophic level, and hence was a good
indicator of protein intake. Nectar- and fruit-eating clades
exhibited high levels of sucrase and maltase activity and reduced
ability to hydrolyze protein. The renal characteristics of bats also
correlated with diet. Relative medullary thickness was higher in
bat species with high protein intakes and lower in nectar- and
fruit-eating bats. The ability to concentrate urine appeared to be
negatively correlated with the ability to feed on carbohydrateand water-rich nectar and fruit. In phyllostomid bats, an
evolutionary commitment to a plant diet seems to result in the
inability to produce concentrated urine.
101
oldest aesthetascs. Thus, it appears that different functional
types of aesthetascs generally do not exist. Rather, aesthetascs
appear to be repetitive functional units in olfactory coding.
However, because odor sensitivity of ORNs can change with the
age of an aesthetasc, some developmentally related functional
heterogeneity exists among aesthetascs. Supported by NIH
grantDC00312.
Topic in Integrative Developmental Studies
104
Ascidian larval CNS: A 4-D analysis of cell lineage in Ciona
Intestlnalis.
COLE, A.G.* and I.A MEINERTZHAGEN. Dalhousie Univ., Halifax,
Canada.
105
A spatio-temporal wave of turnover of olfactory receptor
neurons in spiny lobsters.
HARRISON, P.J.H.*, P. STEULLET, H.S. CATE, and C D . DERBY.
Georgia State Univ., Atlanta.
Olfactory receptor neurons (ORNs) of crustaceans reside in
aesthetasc sensilla located on the lateral flagellum of the
antennule. Using pre-adult (60-80 mm carapace length) spiny
lobsters Panulirus argus, we examined turnover of aesthetascs
and their ORNs, including birth, maturation, and death. New
aesthetascs are added in the proximal-lateral part of the
flagellum. Older aesthetascs are lost in the more distal regions of
the flagellum. A complete turnover of aesthetascs occurs within
3 molt cycles. Taurine-like IR is typically high in ORNs of
differentiating aesthetascs that have not yet emerged, decreases
in a spatio-temporal wave correlated with age of the newly
emerged aesthetascs, and is absent in ORNs of all new
aesthetascs before the next molt. Taurine-like IR is inversely
correlated with odor sensitivity as shown by odor-dependent
activity labeling. These results suggests that taurine-like IR
reveals developing and functionally immature ORNs, and that
turnover of aesthetascs involves a spatio-temporal wave of birth,
functional maturation, and death. We are currently using BrdU
and TUNEL methods to investigate turnover of ORNs in the
antennule. Supported by NIH grant DC00312.
106
Development of the nasal chemosensory systems in a frog
without a tadpole.
DORSEY, D. A.*, W. J. JERMAKOWICZ, A.L. BROWN, C.L
GISCOMBE, and G.R. TEN EYCK. Univ. of Southern Indiana,
Evansville.
Anuran amphibians typically lead a dual life, with an aquatic
larva that undergoes metamorphosis, and a terrestrial adult. The
transition from water to land place many demands on sensory
systems, and studies show that the nasal chemosensory
ABSTRACTS
107
Central nervous system ontogeny in directly developing
frogs: Serotonergic systems.
TEN EYCK, G. R. Univ. of Southern Indiana, Evansville.
Serotonergic (5-HT) neurotransmitter systems are vital for
normal, integrated neural function and play crucial roles in
locomotion, feeding, digestion, and other essential processes.
This study examines 5-HT ontogeny in a directly developing
anuran, Eleutherodactylus coqui. Directly developing frogs have
eliminated the larval stage, and thereby also, the biphasic life
history exhibited by the majority of anurans. Presumably, this
variation in life history could lead to evolutionary alterations in
central nervous system development. Immunocytochemical
studies reveal initial 5-HTir cells during the middle of
embryogenesis. 5-HTir axons of the paraventricular organ
contacted cerebral spinal fluid of the third ventricle, similar to
other non-mammalian vertebrates. Late embryogenesis was
characterized by increased 5-HT fiber and varicosity
development, especially in hypothalamic and telencephalic
regions. Significant increases of 5-HT were detected by HPLC
following hatching, similar to that observed in birds. Compared
with metamorphic anurans, E. coqui displays a much more
precocious embryonic pattern of 5-HT ontogeny and is similar to
mammals and birds in many respects.
108
Transcriptional regulatory networks induced by thyroid
hormone in the developing brain.
DENVER, R.J.' and E.D. HOOPFER. Univ. of Michigan, Ann
Arbor.
Thyroid hormone (T3) is critical for normal brain
development. Previously we identified a small GC box binding
protein, basic transcription element binding protein (BTEB) as a
T3-regulated gene in developing frog and rodent brain. We
analyzed the developmental expression and function of Xenopus
BTEB. BTEB mRNA level rises in tadpole brain during
metamorphosis and this rise depends on T3. T3 receptor beta
(TRb) is autoinduced by T3, and TRb and BTEB are coordinately
upregulated during metamorphosis. Because the TRb promoter
contains multiple GC box sequences we hypothesized that
autoinduction of TRb depends on the coordinate upregulation of
BTEB. Overexpression of a dominant negative form of xBTEB in
XTC-2 cells reduced basal CAT expression from cotransfected
xTRb promoter-CAT plasmid and blocked T3-induced
upregulation of TRb promoter activity. Our data support the
hypothesis that GC box binding proteins like BTEB are
necessary for the autoinduction of TRb during metamorphosis.
The coordinate upregulation of TRb and BTEB suggests that
BTEB could participate in the gene regulation cascade induced
by T3 in the developing tadpole brain, (supported by NSF grant
IBN-9724080 to R.J.D.)
109
Spinal nerves in anurans: A key for understanding
homologies among vertebrae.
PUGENER, L.A. The Univ. of Kansas, Lawrence.
The number of presacral vertebrae has been used by several
authors as a phylogenetic character. Spinal nerves, on the other
hand, have never been considered as a potential source of
19A
Ascidian larvae constitute the simplest invertebrate group
exhibiting chordate characteristics. Pre-localized cytoplasmic
factors specify differentiation early in embryonic development of
the larva, thus the pattern of mitotic descent becomes important
in the specification of embryonic cell fate. To investigate the
extent of variation in late cleavage patterns within the developing
the central nervous system [CNS], we have created a
consecutive series of detailed embryonic cell maps of the larval
CNS from the ascidian, Ciona intestinalis. Using confocal
microscopy, 3-D images of cell nuclei in wholemount
preparations have been generated and used to reconstruct the
relative positions of each cell in the CNS throughout
development. The entire lineage of cell lines forming the visceral
ganglion and the caudal nerve cord has been worked out,
showing little variation in cleavage patterns. The anterior rows of
the neural plate appear to form the neurohypophysis [NH],
however the boundary between the NH and the sensory vesicle
remains unclear. The development of these 3-D cell maps should
facilitate further analysis of ascidian embryogenesis. Supported
by NSERC [I.A.M.] and Dal. Graduate Scholarship [A.G.C.]
systems are remodeled at metamorphosis. We examined the
ontogeny of the olfactory and vomeronasal organs in the direct
developing frog Eleutherodactylus coqui. Olfactory placodes
appear early in embryogenesis, vomeronasal placodes appear
later, ventromedially from the olfactory epithelium. Olfactory and
vomeronasal epithelia rapidly develop, possessing receptor and
supporting cells. The principle chamber forms first, on the
dorsolateral region of the head, the inferior chamber develops
ventrally from the principle and the middle chamber appears at
the end of embryogenesis. Comparisons with another terrestrial
anuran, Bufo americanus, which undergoes metamorphosis,
reveal that the developmental pattern of the chemosensory
organs in E. coqui is altered, skipping some larval developmental
patterns and metamorphic remodeling, and develops directly
into the adult phenotype during embryogenesis.
information. Nevertheless, informative data are usually difficult to
obtain from structures that are repetitions of a basic unit.
Therefore, the number of structures that are repeated is used as
the source of information in proposing hypothesis of evolutionary
relationships. This study shows the importance of analyzing the
nervous system in order to understand vertebral reduction and to
recognize homologous structures among vertebral elements.
Some of the results suggest that the vertebrae that seem more
likely to be lost are those related to the abdominal nerves. Other
reductions in the number of vertebrae may be accounted for by
fusion of elements. In addition, this analysis reveals several
characters that may be phylogenetically informative.
110
Postinhibitory rebound in interneurons of Clione limacina.
PIRTLE, T.J.* and R. A. SATTERLIE. Arizona State Univ., Tempe.
111
Changes in the nervous system and behavior of crayfish
following changes in social status.
DRUMMOND, J., K. SONG, and D.H. EDWARDS*. Georgia State
Univ., Atlanta.
The modulatory effect of 5-HT on the crayfish Lateral Giant
command neuron depends on the animal's social status through
regulation of the 5-HT receptors that affect LG. Here we show
that changes in social status affect the balance of excitatory and
inhibitory input to 5-HT neurons, the patterns of release of 5-HT,
and behavior. The first abdominal (A1) and last thoracic ganglia
of crayfish and lobster contain a pair of 5-HT neurons that
project to the thoracic nervous system and to neurosecretory
endings on nerve roots. In a semi-intact preparation from a
social isolate or dominant animal, touch to the lateral margins of
the A1 segment evoked an asymmetric neuronal response: the
ipsilateral 5-HT neurons were excited and the contralateral cells
were either inhibited or did not respond. In social subordinates,
the same touch evoked a symmetric response: the neurons were
either bilaterally excited or inhibited. The behavior of freely
moving isolate or dominant crayfish to the same touch also
evoked an asymmetric response: the animal turned towards the
stimulus source. The same stimulus in a subordinate evoked a
symmetric locomotor response, either directly forward or
backward.
112
The distribution of serotonin and its precursor, 5-HTP, in two
molluscan species.
FICKBOHM, D.J.*, C.P. LYNN, H.K. CALDWELL, and P.S. KATZ.
Georgia State Univ., Atlanta.
The rate limiting step in serotonin (5-HT) synthesis is thought
to be formation of 5-hydroxy-tryptophan (5-HTP) from
tryptophan, yet little is known about normal 5-HTP distribution.
We compared 5-HTP and 5-HT immune—reactive (ir) cell
distribution in two gastropod molluscs, Aplysia califomica and
Tritonia diomedea, and determined if 5-HTP application altered
these distributions. Although levels of 5-HTP generally are low,
we found that identified 5-HT-ir neurons reliably stained for 5HTP. However, in Aplysia, some 5-HTP-ir neurons were seen in
regions devoid of 5-HT-ir neurons. In addition, 5-HTP staining
was generally more diffuse and variable. 5-HTP treatment
affected the distribution of 5-HTP-ir and 5-HT-ir neurons. After
treatment, almost all neurons were 5-HTP-ir, yet this did not
cause a widespread increase in the number of 5-HT-ir cells.
20A
113
Local calcium changes regulate growth cone filopodia.
CHENG, S.* and V.REHDER. Georgia State Univ., Atlanta.
Previous studies have demonstrated that the intracellular
calcium concentration ([Ca]) can act as a regulator of growth
cone behavior. An increase in [Ca] in identified B5 neurons of the
snail Helisoma by depolarization with elevated KCI medium
caused a transient elongation of filopodia as well as a reduction
in filopodial number. We report here the use of the calcium cage
NP-EGTA to elevate [Ca] within single growth cones or defined
regions of growth cones. Calcium released from NP-EGTA by
short light pulses emitted from an UV laser led to filopodial
elongation in stimulated growth cones only, indicating that the
stimulation remained local. Elevating [Ca] locally in an individual
filopodium resulted in either the elongation of the stimulated
filopodium alone, or in the elongation of a larger number of
filopodia on the same growth cone. Fluphenazine, a specific
inhibitor of calmodulin, blocked the effect on filopodial
elongation caused by uncaging of calcium. Taken together,
these findings suggest that local elevations of [Ca] elicited by
intra- or extracellular signals can regulate filopodial length and
could thus affect neuronal pathfinding.
114
Metamorphosis in a marine gastropod: The role of
transcription and translation.
DEL CARMEN, K.A.* and M.G. HADFIELD. Univ. of Hawaii,
Honolulu.
Metamorphosis in the marine gastropod Phestilla sibogae is
a rapid and drastic transition from a planktonic larval stage to a
benthic juvenile stage. Past work in our lab indicates that
metamorphosis in P. sibogae is not blocked by transcription or
translation inhibitors. The objective of this study was to answer
two questions: To what extent do known inhibitors of
transcription and translation inhibit these processes in larvae of
P. sibogae? Do changes in protein expression occur in larvae of
P. sibogae during metamorphosis? By measuring the
incorporation of 3H-uridine into RNA and 3 5 Smethionine/cysteine into protein, we confirmed that the
pharmacological agents DRB and puromycin drastically reduce
transcription and translation in P. sibogae, without inhibiting
metamorphosis. Changes in the pattern of protein expression
durinng metamorphosis were seen when 3 5 Smethionine/cysteine labeled proteins were separated by 2-D
PAGE. Given that metamorphosis proceeds in the presence of
transcription and translation inhibitors, we propose that posttranslational controls such as phosphorylation play a role in the
control of metamorphosis in P. sibogae.
Topic in Integrative Regulatory Biology
115
Ovarian development inihibition by methyl famesoate (MF) in
the tadpole shrimp, Triops longicaudatus.
UNDER, C.J.* and B. TSUKIMURA. California State Univ.,
Fresno.
The tadpole shrimp, T. longicaudatus, inhabits temporary
bodies of water and thus rapidly become sexually mature. MF,
the unexpoxidated form of insect juvenile hormone III, was
administered daily using Artemia nauplii as a vector (Abdu et a!.,
1999), with minor modifications tflrtemia were incubated in
0.05% albumin and MF for 2 hours). Feedings occurred 24 hours
after Triops hatching until day 10. Controls were fed Artemia
soaked in ethanol and albumin. Oocyte development did not
occur in tadpole shrimp shorter than 8.5 mm, thus animals below
this size were not included. Total lengths of Triops between
The central pattern generator for slow swimming in the
pteropod mollusk Clione limacina is comprised of two groups of
antagonistic interneurons that interact via reciprocal inhibitory
connections. One intrinsic property of interneurons of both
groups, that contributes to pattern generator cycling, is
postinhibitory rebound (PIR). Preliminary experiments suggest
that PIR is enhanced in the presence of serotonin. Serotonin,
and activity of identified serotonergic neurons have been shown
to increase swimming speed in whole animals and reduced
preparations. Exogenous serotonin produces a slight decrease in
intemeuron input resistance. Ion substitution experiments
indicate that postinhibitory rebound is sodium dependent and
TTX resistant.
Rather a small number of additional 5-HT-ir cells appeared.
These results may have implications for the control of 5-HT
levels; neurons that stain for 5-HTP but not 5-HT may lack a
decarboxylase enzyme or alternatively may rapidly metabolize 5HT. Supported by NIH grant NS-35371.
control and treatment groups were not significantly different at
day 5 or day 10. However, MF significantly decreased the
number of oocytes present in the body cavity of day 5 Triops
from a mean of 36.0 oocytes (controls) to 14.4 oocytes (MF
treated) (p<0.002, 2-way ANOVA). On day 10, ovarian weight
was significantly reduced from a mean of 1.02 mg (controls) to
0.3 mg (MF treated) (p<0.001, 2-way ANOVA). Mean weights for
day 10 adults were 68.4 mg. This work was supported in part by
a California State University Research Award.
116
Changes in biosynthesis and degradation of juvenile
hormone during breeding by burying beetles: A reproductive
or social role?
SCOTT, M.P.*, S.T. TRUMBO, P.A. NEESE, W.D. BAILEY, and
R.M. ROE. Univ. of New Hampshire, Durham, Univ. of
Connecticut, Waterbury, and North Carolina State Univ., Raleigh.
117
Stimulation of steroidogenesis through an insulin-like
signaling pathway in Aedes aegypti.
RIEHLE, M.A.* and M.R. Brown. Univ. of Georgia, Athens.
This study characterizes the signaling pathway of the
mosquito insulin receptor in the ovary, and its role in
steroidogenesis. A dose-response experiment with bovine insulin
found that maximal ecdysteroid secretion occurred in the
presence of 17 uM insulin. Peroxyvanadate, a tyrosine
phosphatase inhibitor, stimulated ecdysteroid release at
concentrations of 250 uM to 1 mM. Okidaic acid, a
serine/threonine phosphatase inhibitor, stimulated
steroidogenesis with an ED50 of 77.39 nM. Inhibitors of the
vertebrate insulin signaling cascade were tested in the presence
of 17 uM insulin. Concentrations of the tyrosine kinase inhibitor
HNMPA as low as 170 uM prevented ecdysteroid secretion. Two
selective inhibitors of PI 3-kinase, wortmannin and LY294002,
inhibited ecdysteroid production at low concentrations (IC- 50 =
1.6 nM and 30 nM, respectively). Finally, PD098059, an inhibitor
of the MAP kinase cascade, did not inhibit steroidogenesis.
Western blot studies identified two beta subunits with an
approximate molecular weight of 95 and 125 kDa, and two alpha
subunits, approximately 100 kDa and 120 kDa. Supported by
NIH grant AI33108.
118
Capsule structure and embryonic development in neuralextract-induced egg-capsules in the snail Chorus giganteus.
RAM, J.L - , M.L RAM, and C.S. GALLARDO. Wayne State Univ.,
Detroit, Ml, and Universidad Austral de Chile, Valdivia, Chile.
In order to develop efficient aquaculture of the Chilean
muricid snail Chorus giganteus, hormonal induction of egg laying
and subsequent development were investigated. Extracts of
circumesophageal ganglia caused laying of both hard and soft
capsules, no more than one capsule/injection. Control injections
did not cause laying. The inducing substance was resistant to
boiling (as are neuropeptide egg-laying hormones in Lymnaea,
Aplysia, and Busycon). Median injection/laying latency was 4 - 5
ABSTRACTS
119
Serum and slime vitellogenin in the Atlantic cod.Gadus
morhua, and its relation to ovarian development
KUNKEL, J.G.', J. BOHANNON, R. SHARMA, and
J.ZYDLEWSKI. Univ. of Massachusetts, Amherst.
A rabbit antiserum was prepared against cod lipovitellin (Lv).
The antiserum was used to demonstrate that Vitellogenin (Vg)
could be detected in mucous scraped from the gill and body of
cod captured by 30 min otter trawl. Vg however was not able to
be detected in mucous from captive resting females who were
injected with estradiol and accumulated large amounts of Vg in
their serum. We conclude that Vg in mucous from wild caught
cod is a result of trawl trauma. The antiserum applied to cod
serum correctly identified reproductive females and
demonstrated that resting females eventually lost reactive
products in their serum by late spring. This is encouraging in that
it may permit the use of the antiserum in examining the
phenomenon of early maturation in cod populations as well as
identifying reproductive status in the fall season, when visual
identification of maturation state is difficult, particularly during
the first year of fecundity. Additional observation of control male
sera using the anti-Lv serum found that occasional large males
give a substantial positive test for Vg in their serum. (Supported
by NOAA/CMER grant 528687)
120
A non-destructive technique to measure the rate of
vitellogenin production in vivo in a small bird.
CHRISTIANS, J.K.* and T.D. WILLIAMS. Simon Fraser Univ.,
Burnaby, Canada.
Intraspecific variation in performance provides a valuable
resource for studying the evolution of phenotypic traits.
Reproductive performance (e.g., egg mass) shows great variation
within avian species and is often repeatable within individuals.
However, the physiological basis of this variation is not known.
We hypothesize that the rate at which the liver produces
vitellogenin, the primary source of yolk protein in oviparous
vertebrates, will explain variation in yolk quality. Here we
describe the development and validation of a non-destructive
technique to measure the rate of vitellogenin production in vivo
in a small (ca. 17 g) passerine, the zebra finch (Taeniopygia
guttata). Radiolabeled amino acids were injected intraperitoneally
and, shortly thereafter, a small blood sample was obtained.
Vitellogenin was selectively precipitated from plasma, and the
amount of activity that had been incorporated into vitellogenin
was used as an index of its rate of production. In addition to
contributing to the study of natural variation in reproductive
performance, this technique may also be useful for monitoring
the effects of xenoestrogens.
121
Diurnal and daily variation in vitellogenin levels during the
laying cycle.
SALVANTE, K.G.*. W.O. CHALLENGER, and T.D. WILLIAMS.
Simon Fraser Univ., Burnaby, Canada.
Vitellogenin (VTG) is the main egg-yolk precursor in
oviparous vertebrates, and has been proposed as a biomarker
for estrogenic effects of endocrine disruptors. Plasma VTG has
been found to vary markedly (10-fold) between females in a
population sampled at the 1-egg stage. However, little is known
about the dynamics of VTG during the laying cycle and the
sources of variation in VTG within individuals. We will describe
the daily variation in plasma VTG during the laying cycle and its
relationship with reproductive effort (egg and clutch size, lay
21A
Burying beetles, Nicrophorus orbicollis, depend on the
location of an unpredictable resource, a small vertebrate
carcass, for reproduction. They must out compete many
competitors and as a consequence have evolved several
behavioral and physiological adaptations to exploit carrion
quickly. Upon the discovery of a carcass, there is a correlated
rapid rise in juvenile hormone (JH) hemolymph titers, JH
biosynthesis and ovarian weight and a fall in JH esterase activity.
Oviposition usually begins within 24 hours. Males and females
provide extensive parental care and have similar hormone
profiles during the first 48 hours. In spite of the substantial
changes in titers, synthesis and degradation, JH does not
appear to regulate ovarian development. Application of
methoprene or JH III in the absence of a carcass did not result in
vitellogenin uptake and females treated with precocene II
behaved and oviposited normally, although later than acetonetreated control females. We suggest that the role of JH has been
preempted to organize social behavior and coordinate parental
behavior between mates.
hr, and 24 of 25 induced capsules contained eggs—up to 3000
eggs/capsule. Eggs in soft capsules were subject to infection;
however, eggs in some hard capsules developed into veliger
larvae by 49 days (time of fixation). Differences in capsule wall
structure being studied by e.m. may underlie the protective
effect of capsule hardening. This study demonstrates that laying
of viable eggs can be induced in C. giganteus by a putative egglaying hormone, possibly similar to hormones in Lymnaea,
Aplysia, and Busycon. Supported by NSF#9724918and
FONDAP/DID-UACH S199951.
date) and laying rate (daily vs. skipped days) using data from
captive zebra finches (Taeniopygia guttata) and free-living
European starlings (Sturnus vulgaris) that were blood sampled at
different stages of the laying cycle, ranging from pre-laying to
clutch completion. We will also examine diurnal variation in
plasma VTG, and intra-individual repeatability of VTG levels
assessed by blood sampling females at the same stage of laying
during two laying bouts. Finally, we will consider the idea of
'economic' design of physiological systems by comparing
variation in plasma VTG (i.e. 'supply') with patterns of follicle
development (i.e. 'demand').
122
Bioactive substances regulating mammalian parturition
influence contractions of ovarian smooth muscele in the
oviparous fish, Fundulus heteroclitus.
TATE, A.E. Roger Williams Univ., Bristol, Rl.
123
Cloning and characterization of chicken II gonadotropinreleasing hormone in a caecilian amphibian, Typhlonectes
natans.
EBERSOLE, T.J. 1 , F.W. GOETZ, and S.K. BOYD. Univ. of Notre
Dame, IN.
Caecilians belong to the under-studied third order
(Gymnophiona) of amphibians. Very little is known about their
endocrine control of reproduction. Our goal was to clone and to
characterize chicken II gonadotropin-releasing hormone
(cllGnRH) from this amphibian and to compare its structure with
other cllGnRH genes. We used a PCR-based strategy to
generate a partial fragment from a caecilian brain cDNA library
which we then used as a probe to screen the library. We
obtained a full length cDNA of 785bp. The open reading frame of
258 nucleotides encoded for a preprohormone of 86 amino
acids. It consisted of a signal peptide (24aa), cllGnRH (10aa), a
processing site (3aa) and a GnRH-associated peptide (49aa).
Using GenBank, the prohormone for amphibian cllGnRH is 65%,
63%, 6 1 % , 59%, 59% and 58% identical to cichlid, seabream,
bass, goldfish, catfish and trout, respectively. Therefore, the
brain of this caecilian amphibian contains a likely cDNA for
cllGnRH and we have previously shown the presence of this
peptide using ICC and RIA. This is the first time the gene for
cllGnRH has been cloned in any amphibian. Supported by
NSF#IBN95-14305, SICB and CSHL
124
Sex determination and sex differentiation in reptiles.
MARQUEZ, E.*, D. DENARDO, and T.B. HAYES. Univ. of
California, Berkeley.
125
Effects of temperature and testosterone on mating in male
big brown bats.
MENDONCA, M.T.' and M.C. SMITH. Auburn Univ., AL.
Anecdotal observations of vespertilionid bats indicate that
mating occurs during fall and winter months, when testosterone
(T) is basal in males. A previous study on big brown bats,
Eptesicus fuscus , found that males were more likely to mate if
exposed to a period of low temperature (4"C) with subsequent
arousal than if maintained at higher temperature (25°C). It also
found that males would mate regardless of testosterone level.
We further tested this observation by exposing intact,
gonadectomized (GX), GX+T, GX+flutamide male Eptesicus to
different temperature regimens (20, 10, and 5"C) for different time
periods (1, 4, and 7 days) from Nov 1998-Mar 1999. Bats were
observed for 4 days after arousal. Bats did not mate after
exposure to 7 days of 10°C in late November. However, 7 days
of 5°C in December, stimulated mating in 40% of males from all
treatment groups except flutamide (an anti-androgen). Percent of
males mating varied from 40-80% but did not differ significantly
among temperature regimens (Dec-Mar). However, a significantly
lower percentage of flutamide-treated males exhibited mating
behavior when compared to intact, GX and GX+T groups. This
research funded by NIH MH55335.
Division of Animal Behavior
126
Photorefractoriness and the evolution of reproductive
flexibility in cardueline finches.
MACDOUGALL-SHACKLETON, S. A.* and T.P. HAHN. Princeton
Univ., NJ.
Cardueline finches exhibit diverse breeding schedules, from
strictly seasonal to opportunistic. We tested the relationship
between breeding flexibility and absolute photorefractoriness in 4
species: Loxia curvirostra, Carpodacus cassinii, Carduelis pinus
and Leucosticte tephrocotis. In autumn, when birds were
molting, we left half the birds of each species on natural
declining photoperiod, and transferred the other half to 24 h
light. Before and after photostimulation we measured plasma
luteinizing hormone (LH) and testes length. C. cassinii did not
respond to photostimulation, demonstrating absolute
photorefractoriness. However, all 3 other species grew their
testes and exhibited a surge in LH in response to
photostimulation. Most notable is the response of L tephrocotis.
This species is the most distantly related among the 4 tested
here and breeds for only a brief time in the summer, yet retains
the ability to respond to stimulatory cues even in autumn. Thus,
cardueline finches may have been pre-adapted to respond to
stimulatory cues year-round and thus to evolve long, flexible
breeding seasons such as those exhibited by siskins and
crossbills.
Steroids can alter sex ratios in environmentally sex
determined (ESD) reptiles, but such studies are lacking in
genetically sex determined (GSD) species. We hypothesized that
GSD are protected from the effects of exogenous steroids. We
studied one ESD species: the slider (Pseudemys scripta); and
two GSD: the softshel! turtle (fipalone spiniferus), and the Florida
king snake (Lampropeltis getulus). Eggs of each species were
22A
Spontaneous contractions of the myometrium contribute to
fetal deliver in eutherians. Lesser derived animals, such as fish,
also possess muscular reproductive tracts. We previously
showed that the mummichog has prominent ovarian smooth
muscle. We found the proportion of females with spontaneously
contracting ovaries proportional to the stage of sexual
maturation. And we showed that the amplitude and frequency of
contractions were correlated with the reproductive cycle.
Recently, we found that prostaglandin F2alpha, and arginine
vasotocin, produced dose-related responses in the amplitude of
ovarian contractions. We also found that fish treated with
estradiol 17-beta produced significantly stronger contractions
than those treated with a vehicle control. And we found evidence
for cholinergic and adrenergic control of ovarian contractions.
The responses to these chemical messengers are similar to
those found in more highly derived, and reproductively complex
animals, suggesting a strong conservation of hormone function,
and implying that mummichog ovarian contractions may be
analogous to eutherian uterine contractions.
treated post-oviposition with dihydrotestosterone (DHT), estradiol
(E2), or vehicle. In P. scripta E2-treatment resulted in 88%
females; DHT produced 68% males; controls yielded 80% with
undifferentiated gonads. Neither steroid affected sex ratios in A.
spiniferus, so steroids may not affect gonadal differentiation in
this GSD. Distinguishing males and females by histology has
proven difficult in L. getula, and the effects of steroids on
gonadal differentiation are unclear. However, hemipenes
development was inhibited by E2: only 2% E2-treated hatchlings
developed hemipenes, compared with 50% controls and 55%
DHT-treatments. Studies on other GSD reptiles are required to
determine if protection from exogenous steroids is correlated
with the mode of sex determination.
127
130
Ringneck snakes, Diadophis, discriminate among chemical
deposits of salamanders.
CUPP, P. V., JR. Eastern Kentucky Univ., Richmond.
Chemical orientation of bullheads and stonecats under
different flow regimes.
SHERMAN, M.L.- and P.A. MOORE. Bowling Green State Univ.,
OH.
Ringneck snakes were tested for the ability to detect
substrate odors of the salamanders, Plethodon richmondi, and
Notophthalmus viridescens(red eft stage). D. punctatus are
known to prey on P. richmondi, and apparently not on red efts.
Individual D. punctatus were placed in plastic containers with
two substrate choices. In the 1st experiment, one substrate
consisted of a paper towel previously exposed to P. richmondi or
red efts for 24 hrs. The other substrate consisted of a towel
without salamander odor. In the 2nd experiment, substrate
choices of P. richmondi and red eft odors were provided. The
snakes were released at the center of the containers and their
positions were monitored for two hrs. D. punctatus exhibited a
highly significant preference for P. richmondi substrates over
substrates with no odor and substrates with odors of red efts.
These results suggest that D. punctatus may discriminate among
the chemical deposits of salamanders that are prey and nonprey,
and thus may reduce energy costs and searching time by
selecting sites with odors of their prey.
128
Previous research has demonstrated that chemical stimuli
play a fundamental role in the survival, growth, and reproduction
of organisms. While fluid hydraulics has been shown to alter
orientation behavior, it is unclear from these studies whether
chemical signal structure or flow dynamics was responsible for
differences in animal behavior. Our study examined how
changes in chemical signal structure (through changes in source
arrangement, addition of other chemicals, and changes in
substrate) affect crayfish search behavior. This study is unique in
that we are altered signal structure while keeping hydrodynamics
constant. Results demonstrate that crayfish found the source
faster when sources when we increased the complexity of
information presented in the odor signal. Measurements of tracer
molecules indicated that these manipulations influenced the
downstream fine-scale structure of odor plumes. We conclude
that the complexity of odor signals actually increase search
efficiency for crayfish and that future studies on the mechanisms
of orientation need to consider the role of signal structure,
independent of hydrodynamics effects, on chemosensory
mediated orientation.
131
Behavioral asymmetries in zebrafish Danio rerio, with
reference to the degree of asymmetry in the brain.
CAMPIONI-NOACK.M.', M.K.RYLANDER, J.A. CARR, and
R.E.STRAUSS. Texas Tech Univ., Lubbock.
Miklosi etal. (1998) have shown that zebrafish display a
cognitive lateralization and this is suggested by their asymmetric
perceptual processing of various stimuli. Previous unpublished
work with guppies {Poecilia reticulata)in our laboratory has
suggested that inspection behavior is asymmetric with respect to
sense organs (eyes and acousticolateralis system). We studied
behavioral asymmetries in adult and juvenile zebrafish (Danio
rerio) by comparing directional responses in searching,
inspection, and escape behaviors. Responses under specific
stimuli (those that include inspection or escape) and non-specific
stimuli (searching behavior) were video-taped and analyzed using
the Video-max system. Fifty adults and 50 juveniles were
randomly tested using 15 replications for each stimulus.
Preliminary results indicate significant lateralization in
approximately 70% of the specimens. The directional responses
for each individual were compared to the degree of asymmetry in
the whole brain as determined by photographing the brains and
measuring the relative sizes of their parts using a digitizing
system (TPSDig).
129
132
The effect of reduced salinity on locomotion in the American
lobster.
O'GRADY, D.F.' and W.H. WATSON, III. Univ. of New
Hampshire, Durham.
Reproductive behavior of two female morphs of the
damselfly, Ischnura ramburi.
SIROT, L.K. Univ. of Florida, Gainesville.
The American lobster inhabits estuaries along the New
England coast. Estuarine lobster populations tend to have a
skewed sex ratio in which males outnumber females. In Great
Bay estuary, New Hampshire, lobsters move into the upper
estuary during the late spring and early summer, and tend to
move back toward the coast during the late summer and early
fall. Large storms such as hurricanes have caused mass
movements of lobsters out of the upper estuary. Lobsters can
detect small changes in salinity, and have been shown to avoid
low salinity in previous behavioral experiments. The purpose of
our experiment was to investigate the effect that reduced salinity
has on the locomotion of lobsters. Lobster activity was
measured before, during, and after a. 50% drop in salinity. Males
tended to reduce their locomotion after the salinity drop, while
females tended to increase their locomotion. These results are
consistent with previous data that determined females are more
active when choosing between high and low salinity water, and
could help to explain the skewed sex ratio in estuaries.
Supported by grants from the USDA and Sea Grant to WHW and
a Levine Summer Fellowship to DFO.
Mating duration in ischnuran damselflies exhibits high intraand interspecific variability. In some insect species, mating
duration has been demonstrated to vary with social conditions,
specifically male density and operational sex ratio. This variation
has been attributed to male control in the context of varying
levels of male-male competition. In this study, I tested for social
correlates of mating duration in the damselfly, Ischnura ramburi,
by timing the duration of matings under conditions varying in
male and female density and operational sex ratio. I then used
the results of this study to examine whether males and/or
females influence mating duration by varying the pre-mating
social context of one sex while keeping the pre-mating social
context of the other sex constant. The results of this study give
us insight into both the mechanisms and the function of
prolonged copulations in ischnuran damselflies.
133
Lekking behavior in the prairie mole cricket
HILL, P.S.M. Univ. of Tulsa, OK.
The prairie mole cricket is a rare, burrowing insect of the
tallgrass prairie of the south-central U.S. Males aggregate to
ABSTRACTS
23A
Chemical orientation in complex odor landscapes by
crayfish.
MOORE, P A " , T.A. KELLER, and A.M. TOMBA. Bowling Green
State Univ., OH.
Catfish use chemical signals to make important ecological
decisions. During chemical orientation an animal must be able to
extract distance and direction information from the signal.
Evolutionary theory predicts that organisms should be adapted
to the dominant sensory information in their environment. Two
catfish species that live in different sensory environments were
chosen the above prediction. Environmental differences provide
an opportunity to study chemical orientation of closely related
species under certain types of evolutionary constraints. We used
a comparative study with the brown bullhead and the stonecat
under different flow regimes to investigate differences in
chemical orientation behaviors. Bullheads were more successful
than stonecats in finding the odor source in the no flow
condition. However in the high flow condition both species were
less successful in finding the odor source. These results seem to
support the above prediction for the bullhead but not for the
stonecat. This may indicate that chemical signals are not as
important for stonecats as they are for bullheads.
display to flying females in spectacular choruses just at sunset in
the spring in Oklahoma. Aggregations are clumped on at least
three scalar levels, unlike other chorusing Orthoptera that are
regularly spaced at nearest neighbor distances. The species
meets all the criteria for classification as forming a classical
lek"": in addition to the aggregation of calling males females
have freedom of choice of mates males contribute no parental
care nor do males sequester resources valuable to females.
Verifying that the mating system qualifies as a lek is less
interesting than exploring costs and benefits to males in this
system. Here we report on preliminary work on testing the
'hotshot male' hypothesis.
of signals reaching the spider's legs were measured for prey in
various locations in the web. The amplitude of the motion each
rear leg experienced varied with prey location, and there was a
measurable time delay in the arrival of the signal at each leg; the
spider might use amplitude, time delay, or both for prey
localization. Finally, a numerical model of the web was
constructed; resonant frequencies predicted by the model
closely matched the observed resonances. Supported by NSF
DBI 99-96072.
134
carolinus.
137
Synchronic flashing and mating behavior in Photinus
Polyandrous parasitoid?: Mating behavior of the parasitic
wasp Cotes/a congregata (Say) [Hymenoptera: Braconidae].
FREEMAN, E.W.* and K.M. KESTER. Virginia Commonwealth
Univ., Richmond.
135
Effects of sequential learning experiences on the foraging
behavior of the gregarious parasitoid Cotesia congregata
(Say) (Hymenoptera: Braconidae).
LENTZ, A.J.* and K.M. KESTER, Virginia Commonwealth Univ.,
Richmond.
Foraging behavior of parasitoids is modified both by postemergence and ovipositional experiences with plants. Postemergence experience induces positive responses to the plant
experienced at emergence and generalized responses, either
positive or inhibitory, to other plants. Ovipositional experience
induces a positive response to the plant on which oviposition
occurs. We tested the effects of post-emergence experience
followed by ovipositional experience on searching responses to
plants, offspring allocation and sex ratios of resulting offspring.
Experience did not reduce searching responses to inherently
attractive plants or affect brood size. However, parasitoids
produced proportionately more females per host on plants
experienced at emergence, regardless of the inherent
attractiveness of the plant or prior ovipositional experience.
136
Prey location in funnel and sheet spider webs.
NAFTILAN, S.A. Claremont Colleges, CA.
Sheet and funnel web spiders rely on vibrations transmitted
through their web for prey identification and orientation. We have
investigated the nature of this transmission in the webs of
Hololena curta and Angelenopsis aperta. Using a high-speed
video camera, amplitudes and velocities of both transverse and
longitudinal vibrations were measured. Transverse vibrations
produced by prey had larger amplitude; therefore we speculate
that the spider keys on these vibrations. Wave velocity was
measured to be as high as 800 cm/sec for both modes.
Resonances and damping in the web were also measured. Webs
typically had a strong resonance near 28 Hz, and spiders would
consistently attack when a probe vibrating near that frequency
was gently pressed into the web. The amplitude and time delay
24A
Photinus carolinus is a synchronic firefly. Flying flashing
males produce 5-8 pulses (2 Hz) followed by 8-10 sec of no
flashing. The mechanisms underlying synchrony are partially
understood and a predictive model has been developed. To
understand the behavioral function of synchrony, we observed
mating behavior. The OSR was male dominant throughout the
season. Clusters of males were found to surround a single
female. Males flashed synchronically or sequentially when near
to a responding female. A female responded during the male
interburst interval. During Stage I mating, multiple males could
form a vertical stack on top of a female. Once Stage II mating
occurred, the dyad no longer responded to flashes. Once
uncoupling occurred, the female walked and flashed at 1 Hz, a
new female flash rhythm. We suspect that synchrony preserves
the species specific male flash rhythm for the female and
provides an interburst period during which the low intensity flash
of the female can be seen by a male. Sponsored by the Great
Smoky Mountains Conservation Association and Georgia
Southern University.
Division of Comparative Endocrinology
138
Development of an immunoassay for detection of
vitellogenin in mosquitofish (Gambusia affinis).
TOLAR.J.F.*, R.D. WATSON, and R.A. ANGUS. Univ. of
Alabama, Birmingham.
Vitellogenin (VTG) is a phospholipoglycoprotein precursor of
egg yolk. In mature female fish, VTG is synthesized and secreted
by the liver in response to circulating estrogens. VTG is normally
undetectable in the plasma of male fish, but can be induced by
exposure to compounds possessing estrogenic activity. An
objective of our research was to develop an immunoassay for
VTG of the western mosquitofish [Gambusia affinis). VTG was
identified according to accepted criteria, purified from blood by
gel filtration chromatography and nondissociating PAGE, then
electroblotted to nitrocellulose. Immune sera were raised in
rabbits using the purified VTG as immunogen and specificity of
the antiserum was determined by Western blot. The antiserum
was used in Western blots to quantify the effects of estrogenic
compounds on vitellogenesis in 6. affinis. Supported by USEPA
grant R826130-01-0.
139
A behavioral assay for endocrine disrupters: Effects of 4-tert
octylphenol on zebrafish (Dan/o rerio).
CAMPBELL, A.J., N.L. COLLIE*, and M.K. RYLANDER. Texas
Tech Univ., Lubbock.
Detection of endocrine-disrupting chemicals (EDCs) in the
environment has relied primarily on chemical or physiological
techniques. We developed a computer-assisted behavioral assay
to quantify effects of octylphenol (OP), a common industrial
pollutant that binds to estrogen receptors, on reproductive
behavior in zebrafish. Videotapes of male-female pairs were
made of fish exposed to OP (10"7-10 "5-5 M) dissolved in an
acetone vehicle for acute (minutes) and chronic (up to 72 h)
Cotesia congregata is a gregarious larval endoparasitoid of
sphingid larvae including Manduca sexta L, the tobacco
hornworm. Like most hymenopterans, C. congregata reproduces
parthenogenetically and is arrhenotokous, whereby unfertilized
eggs develop into haploid males and fertilized eggs develop into
diploid females. Males emerge and remain on the plant with the
host. Upon detection of pheromones from the cocoons of their
sisters, males form small groups and produce a complex low
frequency sound by fanning their wings. Immediately after the
sisters emerge from the cocoons, mating occurs; therefore, sibmating is the norm. Females mate only once. The likelihood a
female would mate, her resulting brood-size and the sex ratio of
the offspring were examined when the number of males per
group was varied. Females offered multiple males were more
likely to mate and produce female offspring than those offered a
single male. Unrelated to the number of males offered the
female, there was a marked change in fecundity over the lifetime
of the female as shown through a decrease in brood size and a
decrease in the ratio of female offspring.
FAUST, L, M.F. KUBKE, J. MAUPIN*, A. MOISEFF, and J.
COPELAND. Georgia Southern Univ., Statesboro, and Univ. of
Connecticut, Storrs.
treatments. A tracking system (Videomex V was used to count
the number and duration of social contacts. OP was found to
inhibit dose- dependently both the number and duration of
contacts of zebrafish pairs . The acetone vehicle alone had no
effect. Zebrafish pairs also showed a dose-dependent reduction
in spawning behavior when exposed acutely to 17-beta estradiol.
The results suggest that such automated behavioral assays may
prove useful to governmental regulatory agencies and chemical
companies in screening for potential EDCs before their release
into the environment. Supported by Advanced Technology
Program grant # 003644-0115-1997.
140
Do the soy isoflavones genestein and genestin mimic
estrogens in fish?
ROWELL, C.B.*, S. A. WATTS, and S. BARNES. The Univ. of
Alabama at Birmingham.
141
Limb deformities and abnormal sex hormone concentrations
in frogs.
REED, K.L.*, K.J. BABBITT, and S.A. SOWER. Univ. of New
Hampshire, Durham.
Recent declines and deformities in frog populations have
prompted concern regarding their biological status. Surveys of
bullfrogs and green frogs were conducted during the summers of
1997 and 1998 in NH and MA. Deformed frogs were found at
31/35 sites (86%). Deformity rates ranged from 0%-9.3% and
the mean deformity rate was 4.9% for 1997 and 3.7% for 1998.
To assess their reproductive status, in vitro gonadal steroid
production and brain gonadotropin-releasing hormone (GnRH)
concentrations were analyzed. After incubation with
pregnenalone, normal male frogs produced significantly higher
(P<0.05) levels of androgens (140.5+40.5 pg/mg testes)
compared to deformed male frogs (45.9+24.5 pg/mg testes).
Estradiol was undetectable. Mammalian GnRH concentrations in
normal frogs (60.0+15.7 pg/brain) were significantly higher
(P<0.05) than those compared to deformed frogs (19.3+3.4
pg/brain). These are the first data to demonstrate decreased
androgen and GnRH production associated with developmental
deformities. We suggest that environmental influences may
produce both limb and reproductive abnormalities in developing
amphibians. (Supported by UNH Sustainability Program, COLSA
and VP for Research)
142
Water from a fish hatchery disrupts stress response in an
amphibian.
OVERSTREET, S.L*, LP. MAYER, M.D. MINOR, and C.R.
PROPPER. Northern Arizona Univ., Flagstaff.
Previously, we found that a population of Rana catesbieana
tadpoles from a local fish hatchery demonstrated a female
biased sex ratio. Another population in the state from a wildlife
refuge showed no such bias. One hypothesis explaining the
ABSTRACTS
143
Effect of weight change on serum leptin and corticosterone
concentrations in lemmings.
NAGY, T.R.*, D.P. ONORATO, and B.A. GOWER. Univ. Alabama
at Birmingham.
Collared lemmings (Dicrostonyx groenlandicus) change body
mass seasonally. Short photoperiod (SD) induces rapid increases
in mass resulting in an animal that is nearly twice the size of
those remaining in long photoperiod (LD). Large SD-lemmings
show decreases in body mass when exposed to LD. We
examined the effect of photoperiod-induced changes in body
mass on circulating concentrations of leptin and corticosterone
(B). The effects of weight gain were assessed in adult animals
that had been raised in LD (22L2D). One half of the group was
transferred to SD (8L:16D), and the controls remained in LD. The
effect of weight loss was assessed in adult animals raised in SD
and switched to LD (SD-SD controls). In the weight gain
experiment, neither leptin (p=0.92; adjusted for body fat by
ANCOVA) nor B (p=0.28) differed between groups (LD-SD vs.
LD-LD). In contrast, in the weight loss experiment, leptin was
significantly reduced (22%, p<0.01; ANCOVA), and B was
significantly increased (162%, p<0.01) in SD-LD animals vs SDSD controls. In conclusion, photoperiod-mediated weight loss,
but not weight gain, may be mediated by the catabolic hormone
B. Leptin appears to reflect negative, but not positive, energy
balance. NIH R01 DK54918
144
Prenatal exposure to diethylstilbesterol and methoxychlor
alters uterine response to estrogen in adult mice.
HOWDESHELL, K.L.*, L.C. ALWORTH, R. RUHLEN, and F.S.
VOM SAAL. Univ. of Missouri, Columbia.
Traditional risk assessment for endocrine disrupting
chemicals determines safe exposure levels based on linear
extrapolation of high dose effects. We report that such
chemicals can produce opposite results at high and low doses.
Pregnant CD-1 mice were injected with 0.1 or 100 ug/kg
diethylstilbesterol (DES) or fed 0.01 or 10 mg/kg methoxychlor
(MXC) on days 11-17 gestation. At 8-months of age, female
offspring were ovariectomized and capsule-implanted with a
range of estradiol (E2) doses. Animals were sacrificed 7 days
later and organ weights were recorded. Prenatal exposure to 100
ug/kg DES significantly increased body weight at weaning and in
adulthood relative to controls. Prenatal DES and MXC both
altered the adult uterine response to increasing doses of E2. At
maximal E2 stimulation, the 0.01 ug/kg DES uteri were 37%
heavier (P<0.05) than controls, while the 100 ug/kg DES uteri
were 69% lighter (P<0.001) than controls. MXC-treated females
tended to be different from controls, and the 0.01 mg/kg uteri
were significantly heavier (P<0.005) than the 10 mg/kg uteri.
145
Estrogen mimics cause minimal behavioral alterations in
rats.
FLYNN, K.M.', S.A. FERGUSON, and R.R. NEWBOLD.
FDA/National Center for Toxicological Research, Jefferson, AR,
and National Institute for Environmental Health Sciences,
Research Triangle Park, NC.
Ethinyl estradiol or the estrogen agonists genistein,
nonylphenol, or methoxychlor were fed to pregnant rats and their
offspring. Doses ranged from 10 to 2000 ppm. Offspring were
25A
The isoflavones genestein and genestin are polyphenolic
compounds that have been isolated from soy. These compounds
have been associated with reduced incidences of prostrate
cancer as well as reduction in osteoporosis and decreased
severity of menopause related conditions; effects that can also
be acheived through the administration of estrogen. The
chemical structure of these compounds is similar to estrogens.
Several in vitro studies though show that the binding affinity of
the estrogen receptors for these phytoestrogens is orders of
magnitude less as compared to estradiol. However, in vivo it has
been demonstrated that these compounds can affect estrogendependent activities, such as inducement of vitellogenin
production in male rainbow trout. Given these two results, it is
hypothesized that isoflavones may have mechanisms of action
that are associated with estrogen mediated and estrogen
independent effects. In the tilapia dietary administration of
estrogen or estrogen agonists have been shown to cause
functional feminization of genotypic males. Our goal is to
determine if dietary administration of these isoflavone will have
estrogenic effects on sex differentiaion and gamete development
in the tilapia.
hatchery bias is that something in the water is affecting sexual
differentiation by disrupting the endocrine system. We tested the
hypothesis that the hatchery water would affect other aspects of
the endocrine system, specifically the corticosterone stress
response. Juvenile frogs from the wildlife refuge were exposed
for 5 days to either hatchery water or refuge water. Following
exposure animals were exposed to handling stress for 0, 3, 16,
and 24 hours. Plasma corticosterone (CS) levels were measured
following the stress. In both groups, plasma CS levels rose
(P<0.001). However, animals exposed to the hatchery water did
not exhibit as strong of a stress response (P<0.001). These
results suggest that these animals may not be able to mount an
appropriate stress response in the hatchery environment.
tested for sexually dimorphic behaviors: open field and running
wheel activity, play, and intake of sweet and salty solutions.
Gestational duration, pups per litter, sex ratio, birthweight, body
weight, and food intake were recorded. There was a significant
treatment effect on intake of the sodium chloride solution in all
high dose groups. Each sex drank more per kg body weight than
same sex controls, however, there was a sex by treatment
interaction only for genistein. There were sporadic treatment
effects on open field activity, play, and sweet solution intake,
and no significant effects on running wheel activity. There was a
decreased birthweight in high dose genistein animals and no
other significant effects on litter measures. Body weight and food
intake were decreased at all high doses. This suggests that
exposure to estrogen mimics can decrease body weight, alter
taste preferences, and cause subtle changes in other sexually
dimorphic behaviors.(Supported by Interagency Agreement 22493-001 between the FDA and the NIEHS.)
146
Shrimp were reared separately through both complete
embryonic and larval development during exposure to 0.1 to
1000 ug fenoxycarb/L. Exposure to 1000 ug fenoxycarb/L
significantly (p<0.05) inhibited embryonic development to larval
hatching, while concentrations £800 ug/L had no significant
(p>0.05) effect on complete embryonic development.
Significantly fewer shrimp successfully metamorphosed to
postlarvae while exposed through complete larval development
to fenoxycarb concentrations £10 ug/L- Larval development of
grass shrimp was, therefore, two orders of magnitude more
sensitive to this juvenile hormone agonist than was embryonic
development. Viability of larvae developing in fenoxycarb was
dose dependent. Development beyond third zoeal stage was
significantly inhibited at concentrations >200 ug/L, while
development beyond fourth zoeal stage was inhibited by >50
ug/L. Fenoxycarb exposure of developing larvae did not alter
either the duration of total larval development or the total number
of larval stages prior to metamorphosis. Rearing of fenoxycarbexposed embryos through larval development without further
exposure had no significant effect on number of larval stages,
larval developmental rate or metamorphic success of larvae.
Growth and ecdysone activity were determined and correlated
with larval developmental stages and fenoxycarb exposure.
147
Cloning of a shrimp eyestalk neuropeptide gene encoding for
the putative gonad-inhibiting hormore.
GU, P.-L.' and S.-M. CHAN. The Univ. of Hong Kong, China.
Female gonad maturation in shrimp is inhibited by eyestalk
Gonad Inhibiting-Hormone (GIH) synthesized in the X-organ
sinus gland complex (XOSG). We reported here the cloning and
characterization of a new cDNA characteristic of the MIH/GIH
eyestalk neuropeptide subfamily. It consists of an open reading
frame of 879 bp and is encoded for a pre-prohormone of 105
amino acids. The signal peptide and matured peptide consist of
29 and 78 amino acid respectively. It shows the highest amino
acid sequence homology to the GIH of the lobster. Initial study
of the genomic organization of GIH suggested that there is a
high degree of similarity between GIH and MIH-like and CHH
gene of the same shrimp. Unlike other neuropeptide, the shrimp
GIH is expressed abundantly in the CNS in addition to the
eyestalk. GIH transcript is most abundant in juveniles and newly
spawned females. Recombinant protein for GIH was produced
for antibody production. As expected, both the neuronal tissues
of the eyestalk and the nerve cord react immunopositively with
the antibody. Injection of recombinant GIH has little molt
inhibiting effect. Current study involves the study of biological
effect of the rGlH on gonad protein synthesis. Supported by a
HKU Institutional grant (CRCG).
26A
Methyl farnesoate (MF) is a sesquiterpenoid compound that
is similar in structure to insect juvenile hormone (JH). This
similarity suggests that MF has functions in crustaceans similar
to those of JH in insects. To investigate the role of MF in larval
development, we studied MeT, an enzyme in the mandibular
organ that catalyzes the final step in MF production. In previous
studies, we have shown that MeT activity is correlated with
hemolymph levels of MF and increases in response to eyestalk
ablation and stress, two conditions known to elevate hemolymph
levels of MF. In this study, we examined lobster eggs and larvae
(stages 1-3) for the presence of this enzyme using both cellular
and molecular approaches. MeT mRNA was identified in eggs
and all larval stages by RT-PCR. Northern blot analysis of mRNA
indicated that MeT transcript levels were similar in all stages
except for stage 1, in which levels were elevated. However, we
were unable to detect the MeT activity after incubating egg and
larval homogenates with appropriate precursors. Thus, it appears
that MeT activity, if it is present in larvae, is below the level that
we can detect with this assay. (Supported by a NIH-AREA grant
to DWB).
149
Juvenile hormone degradation in the lubber grasshopper.
KNEPP, M.D.*, J.D. HATLE, and D.W. BORST. Illinois State
Univ., Normal.
Juvenile hormone (JH) has important regulatory roles during
the ovipositional cycle of many female insects. In Romalea
microptera, JH levels rise and fall during the last half of the
oviposition cycle, suggesting that JH is regulating reproduction
in this species. These fluctuations suggest that the rates of JH
production and/or degradation vary developmentally. To
determine these rates in vivo, we treated adult females with 3H(10RJ-JH III in insect Ringer's supplemented with 0 . 1 % BSA.
Each animal was bled every hour for 24 h after treatment. Half
was extracted with hexane (to separate JH from its breakdown
products). Part of each extract was counted to determine the
rate of JH degradation from the decline in radioactive JH III. In
the animals tested, over half of the 3H-JH III was degraded
within 6 h. The rate of JH degradation was initially greater than
zero, but the rate slowed to zero within 3 h. A second aliquot of
the extract was analyzed by RIA, and the total amount of JH in
the hemolymph calculated. The rate of In vivo JH production was
determined from the difference in the amount of JH present plus
the amount of JH degraded. (Supported by NSF BIR9510979A000toDWB).
150
Vitellogenesis in the lubber grasshopper.
WAGNER, S.J.*, K.M. SHORES, L.A. LUKER, J.D. HATLE, L B .
HECHT, and D.W. BORST. Illinois State Univ., Normal.
The general model of insect vitellogenesis suggests that
juvenile hormone (JH) stimulates the synthesis of vitellogenin
(Vg)-mRNA in the fat body leading to increased production of Vg.
We conducted a correlative study to test whether this model
holds for Romalea microptera (=guttata). Female grasshoppers
were isolated at eclosion, raised communally, and sacrificed at
pre-determined ages. Hemolymph levels of JH and Vg were
measured by RIA and ELISA, respectively. Fat body levels of VgmRNA were quantified by RT-PCR using fluorescent-labeled
primers based on the partial Vg-cDNA. JH levels rose slightly
from day 3 to 13, rose dramatically from day 18 to 28, and then
fell to low levels at oviposition. Vg-mRNA levels were low on day
8, but then rose quickly at day 13. Vg-mRNA reached maximum
levels on day 18, remained high through day 28, and then fell to
an intermediate level (40% of max) at oviposition. Vg levels were
initially low but rose to maximum levels by day 18. We
hypothesize that the slight rise in JH from days 3 to 13
stimulates Vg-mRNA. We are currently testing this hypothesis
with the JH analog methoprene. (Supported by NSF grant BIR9510979A000toDWB).
Comparative embryonic and larval developmental responses
of the estuarine grass shrimp [Palaemonetes pugio) to the
juvenile hormone agonist fenoxycarb.
MCKENNEY, JR., C.L.*, S.R. TUBERTY, G.M. CRIPE, M.D.
HOGLUND, and S. FOSS. U.S. EPA, NHEERL, Gulf Ecology
Division, Gulf Breeze, FL and Univ. of West Florida, Pensacola.
148
Famesoic acid O-methyl transferase in lobster larva
(Homarus americanus).
HOLFORD, K.C.*, J.T. OGAN, and D.W. BORST. Illinois State
Univ., Normal.
151
154
Structure and expression of EcR and RXR A/B domain
clones in the fiddler crab, Uca pugilator.
WU, X.*, D.S. DURICA, and P.M. HOPKINS. Univ. of Oklahoma,
Norman.
Development of competitive PCRs for turtle SF-1 and
aromatase.
MURDOCK, C A \ and T. WIBBELS. Univ. of Alabama at
Birmingham.
We are examining the roles of steroids, retinoids and their
nuclear receptors (NRs) in the proliferation, differentiation and
growth events accompanying the crustacean molt cycle and limb
regeneration. We have isolated fiddler crab cDNA clones
encoding homologs of the ecdysteroid (UpEcR) and retinoid-X
{UpRXR) classes of NR. These genes represent the functional
ecdysone receptor in insects. The poorly conserved A/B
domains of NRs are involved in ligand-independent
transactivation. In many insects, isoforms for both the EcR and
RXR/USP proteins have been identified; these isoforms arise
from the splicing of alternative A/B domains onto common DNAbinding and ligand-binding domains. Studies in insects strongly
suggest that these isoforms have different physiological roles.
Analyses of the recovered crab UpEcR and UpRXR clones,
however, reveal a unique (i.e. invariant) A/B domain open-reading
frame for each gene, showing greatest similarities to the
Tenebrio EcR B1 and the Manduca USP-1 isoforms,
respectively. We are examining A/B: common domain transcript
ratios by PCR and RPA, to assess for the presence of other A/B
isoforms.
Steroids have been implicated as possible factors in the sex
determination cascade of reptiles with temperature-dependent
sex determination (TSD). In the current study, competitive PCRs
are being developed for examining the expression of two
putative factors in the sex determination cascade: Steroidogenic
factor-1 (SF-1) and aromatase. Templates for the competitors
were developed using a PCR-based deletion strategy. These
cDNA competitors were shown to amplify at similar efficiencies
to endogenous templates. In order to produce an RNA
competitor for SF-1, a 729 bp fragment of turtle SF-1 which
includes a 90 bp deletion was cloned into a pGEM-T vector. To
produce an RNA competitor for aromatase, a 1047 bp fragment
of turtle aromatase with a 96 bp deletion was cloned into a
pGEM-T vector. The development of competitive PCRs for turtle
SF-1 and aromatase provides a highly sensitive method for
examining the expression of these factors during TSD.
The synthesis of ecdysteroids by crustacean Y-organs is
negatively regulated by a neuropeptide molt-inhibiting hormone
(MIH). As part of our studies of the control of crustacean growth
and molting, we have used immunocytochemistry to investigate
the structure of the MIH neuroendocrine axis in eyestalk neural
ganglia of the blue crab, Callinectes sapidus. Using antiserum
generated against MIH purified from the shore crab {Carcinus
maenas) as primary antibody, MIH-immunoreactivity was
detected in 15-20 neurosecretory cell bodies, their axons, and
axon terminals in the X-organ /sinus gland complex of C.
sapidus. This cellular architecture is generally similar to that
reported previously for C. maenas. We anticipate the results will
provide baseline data for future experimental manipulations of
MIH synthesis and secretion in blue crabs, and for screening test
antisera (e.g., those raised against recombinant MIH) for their
ability to specifically bind native MIH. Supported by NSF IBN9419916 and NOAA/MS-AL Sea Grant NA86RG0039.
153
Changes in estradiol and testosterone levels in yolks of the
snapping turtle, Chelydra serpentina, during embryonic
development.
ELF,P.K.\ J.W. LANG, and A.J. FIVIZZANI. Univ. of North
Dakota, Grand Forks.
We have hypothesized that yolk hormones play a role in
sexual differentiation in temperature-dependent sex determined
(TSD) species. The purpose of these investigations was to
determine changes in the levels of estradiol(E) and
testosteronefO in the yolks of snapping turtle eggs during
embryonic development. Snapping turtle eggs were collected,
labeled for clutch and incubated at three temperatures,26° (male
producing), 28° (pivotal temperature)and 29.5° (female
producing). Eggs were sacrificed at different times during
development, embryos staged and yolk material collected. Yolks
were homogenized and hormones extracted. E and T were
separated via column chromatography and hormone levels
determined using RIAs. Results show a decrease in the levels of
both hormones during embryonic development, and significant
differences in the pattern of decline of E at the three incubation
temperatures. These results indicate that yolk E levels could be
influenced by incubation temperature which may impact sexual
differentiation.
ABSTRACTS
Sea turtles possess temperature-dependent sex
determination in which the incubation temperature of the egg
determines the sex of the hatchling. During the current study
hatchling sex ratios of hawksbill sea turtles were estimated
during the 1997 and 1998 nesting seasons on Buck Island Reef
National Monument, U.S. Virgin Islands. This island represents a
natural and undeveloped nesting beach for the hawksbill sea
turtles in the Caribbean. Data loggers were place directly into the
middle of nests in order to monitor incubation temperatures.
Additionally, several nests received multiple data loggers to
evaluate temperature variation within nests. Average incubation
temperature during the temperature-sensitive period was used to
predict sex ratio. The results suggest that Buck Island produced
female-biased sex ratios during the heaviest nesting periods of
1997 and 1998. However, the results also suggest that major
tropical weather systems (e.g. hurricanes, tropical storms, etc.)
moving through the Carribean can cool nests and significantly
influence hawksbill sex ratios produced on Buck Island.
156
Seasonal changes in sex and adrenal steroid hormones of
gopher tortoises (Gopnerus polyphemus).
OTT, J.A.*, M.T. MENDONCA, C. GUYER, and W.K. MICHENER.
Jones Ecological Research Center, Newton, GA.
We sampled a population of gopher tortoises from May to
October 1997 to determine seasonal cycles of steroid hormones
(T, E, P) and related them to observations of mating behavior. In
males, plasma T levels peaked in July and August and remained
elevated through October. This coincides with the reported time
of peak mating and spermatogenesis, indicating that males
display an associated pattern of reproduction. In females, E
levels were high in September and October. Plasma T levels in
females were elevated in May, decreased to basal levels in June
and July, and rose again in August and September. Elevated E
and T levels correspond to the reported time of peak vitellogenic
activity, indicating that females also display an associated cycle.
Plasma P in females remained basal throughout the active
season, suggesting that ovulation occurs during winter. We also
determined levels of B to assess the influence of capture stress
on tortoises. We found no seasonal variation in levels of B in
males or females. Seasonal hormone levels are discussed in
relation to tortoise activity patterns and reproductive behavior.
27A
152
Immunocytochemical investigation of the molt-inhibiting
hormone neuroendocrine axis of the blue crab, Callinectes
sapidus.
BORDERS, K.J., K.Y. LILLY, H. DIRCKSEN, K.J. LEE*, and R.D.
WATSON. Univ. of Alabama at Birmingham, and Univ. of Bonn,
Germany.
155
Hurricances and hatchling hawksbill sea turtle sex ratios.
WIBBELS, T.*, W.R. MACKEY, Z.-M. HILLIS -STARR, and B.
PHILLIPS. Univ. of Alabama at Birmingham, National Park
Service, U.S.Virgin .Islands, U.S. Geological Survey, U.S.Virgin
Islands.
157
160
Effects of testosterone on hibernation parameters in male
big brown bats, Eptesicus fuscus.
SMITH, S*, M.T. MENDONCA, and M.C. SMITH. Auburn Univ.,
AL.
Steroid sulfatase activity in the rat ovary.
SELCER, K.W.* and J.W. CLEMENS Duquesne Univ., Pittsburgh,
PA.
Anecdotal observations of vespertilionid bats indicate that
mating occurs during fall and winter months, when testosterone
(T) is basal in males. A previous study on big brown bats,
Eptesicus fuscus, found that males were more likely to mate if
exposed to a period of low temperature (4*C) with subsequent
arousal than if maintained at higher temperature (25°C). It also
found that males would mate regardless of testosterone level.
We further tested this observation by exposing intact,
gonadectomized (GX), GX+T, GX+flutamide male Eptesicus to
different temperature regimens (20,10, and 5'C) for different time
periods (1, 4, and 7 days) from Nov 1998-Mar 1999. Bats were
observed for 4 days after arousal. Bats did not mate after
exposure to 7 days of 10*C in late November. However, 7 days
of 5"C in December, stimulated mating in 40% of males from all
treatment groups except flutamide (an anti-androgen). Percent of
males mating varied from 40-80% but did not differ significantly
among temperature regimens (Dec-Mar). However, a significantly
lower percentage of flutamide-treated males exhibited mating
behavior when compared to intact, GX and GX+T groups. This
research funded by NIH MH55335.
Sulfated steroids are major circulating forms of adrenal and
gonadal steroids. Sulfonation occurs by esterification at C-3 of
the steroid by the enzyme sulfotransferase. The sulfate can be
removed by steroid sulfatase (STS), thereby generating
biologically active steroids or their precursors. The physiological
significance of this sulfonation/sulfatase 'cycling' of steroids is
largely uncharacterized. Female reproductive tissues have been
reported to express significant STS activity, especially the
mammalian placenta. We have characterized STS activity in rat
ovaries and cultured granulosa cells. Ovarian homogenates
prepared from animals following hormonal treatments were
tested for STS activity. Ovarian homogenates converted 3Hestrone sulfate to 3H-estrone, indicating the presence of STS
activity. The specific STS inhibitor estrone sulfamate (EMATE)
significantly inhibited this activity. In similar conversion assays,
primary cultures of rat granulosa cells and granulosa cell lines
were determined to have high levels of STS activity that were
inhibited by EMATE. The presence of high-level STS activity in
ovarian tissues and steroidogenic granulosa cells suggests that
sulfated steroids may serve as a substrate for ovarian
steroidogenesis.
161
Distribution of androgen receptor-immunoreactivity In the
brain of the eastern fence lizard, Sceloporus undulatus.
HEWS, D.K.*, M.M. MOGA, and G.S. PRINS. Indiana State Univ.,
Terre Haute, Indiana Univ. School of Medicine, Bloomington, and
Univ. of Illinois College of Medicine, Chicago.
Physiological stress response in male and female lizards
Sceloporus virgatus.
ABELL, A. J.* and D.K. HEWS. Univ. of Texas, Brownsville, and
Indiana State Univ., Terre Haute.
Circulating androgens have been implicated in the
expression of many male-typical traits, including reproductive
and aggressive behaviors. In Sceloporus lizards, territorial
aggression is dramatically higher in males compared to females.
As part of a study of the neuroendocrine basis of these sex
differences, we determined the distribution of androgen
receptors (AR) in the brains of breeding-season adults, using the
polyclonal AR antibody PG21. In the male (N=6), ARimmunoreactive (-ir) nuclei were observed in the external nucleus
of the amygdala; the arcuate, ventromedial and periventricular
nuclei of the hypothalamus; and the basal forebrain. Dense
concentrations of AR-ir fibers were found in the medial cortex,
periventricular hypothalamus, and lateral forebrain bundle. Fiber
staining was also present in the preoptic hypothalamus,
habenula, and deep layers of the optic tectum. In the female
(n=3), AR-ir fibers were relatively sparse, but showed a similar
distribution to that in males. No AR-ir nuclei were seen in the
amygdala or hypothalamus of females.
Short-term elevations of glucocorticoids can help during an
acute stressful event, but long-term elevations may decrease sex
steroid levels and suppress reproduction. We measured the
corticosterone response to handling, as well as changes in
plasma androgen following stress-induced CORT changes, in
male and female lizards Sceloporus virgatus. Both sexes
responded to a standard handling stressor with increased CORT.
Neither DHT nor testosterone changed with handling stress in
males, and there was no significant correlation between
androgens and CORT in males held for 0, 10, 60 or 180 minutes
prior to sampling. A rapid CORT response without a concomitant
decrease in androgens may let males cope with a short-term
stressor without suppressing reproduction. Female androgen
levels were highly variable, tended to be higher at intermediate
handling times, and were positively correlated with CORT levels.
Females at advanced reproductive stages (late vitellogenesis;
with oviductal eggs) had higher androgen levels. Androgens may
play a role in mediating reproduction or aggression in female S.
virgatus, either directly or as a precursor to estradiol.
159
162
Elevated testosterone suppresses cell-mediated and
humoral immunity in male dark-eyed juncos.
KETTERSON, E.D.*, J.M. CASTO, and V. NOLAN, JR. Indiana
Univ., Bloomington.
Characterization of fluorescein conjugated alpha-MSH as a
tool for labeling melanocortin receptors.
BROWN, C.L* and J.A. CARR. Texas Tech Univ., Lubbock.
In adult male dark-eyed juncos (Junco hyemalis),
experimental season-long maintenance of testosterone (T) titers
near the early-season peak alters behavior and physiology.
Although seasonal reproductive success of these T-males and of
controls (C-males) does not differ significantly, it is still unclear
whether treatment groups differ in life span or lifetime
reproductive success and study continues. Since T is
immunosuppressive in some birds, we assessed whether high T
titers suppress acquired immunity in captive and free-living Tand C-male juncos. In captive T-males, both T and
corticosterone titers were elevated as compared to C-males, and
humoral and cell-mediated immune responses were suppressed.
Cell-mediated immunity returned to normal shortly after
exogenous T was removed. Free-living T-males also exhibited
suppressed cell-mediated immunity as compared to free-living
controls, which suggests that immunosuppression is not due to
interactions between captivity and T-treatment. We are currently
testing whether the observed immunosuppression results from
direct effects of T or indirect effects via a corticosteroid-related
Tiechanism.
28A
Biological activity equivalent to that of the native peptide is a
prerequisite for use of radio- or fluorophore-labeled peptide
conjugates in receptor binding studies. Radioiodination of alphaMSH destroys the biological activity of the peptide, rendering it
useless for receptor binding experiments. Here we describe a
fluorescein labeled form of alpha-MSH (fluo-MSH) that retains its
biological activity in amphibian and mammalian bioassay
systems. Administration of a single dose (80 pmol) of fluo-MSH
via the dorsal lymph sac in Rana pipiens stimulated skin
darkening for up to 5 hrs with a potency identical to that of the
native peptide. Alpha-MSH, fluo-MSH and fluo-NDP-MSH
exhibited similar dose-response relationships in the R pipiens invivo skin-darkening assay. Fluo-MSH stimulated melanin
production in B16 mouse melanoma cells in a dose-dependent
fashion. We conclude that fluo-MSH retains the biological
potency of the native peptide and should be a useful tool for
labeling melanocortin receptors. Supported in part by a HHMI
grant through the Undergraduate Biological Sciences Education
Program to TTU.
158
163
Development of corticotropes, gonadotropes and prolactin
cells in the anterior pituitary of the lungfish Neoceratodus
forsteri.
JOSS, J.M.*, A. RAJ-PRASAD, and D. BIRCH, D. Macquarie
Univ., Sydney, Australia.
The development of the pituitary of N. forsteri is being
studied both historically and ultrastructurally to define the
ontogeny of differentiation of cell types by immunocytochemical
and immunogold identification of cell types. At hatching, the
pituitary comprises a hollow ball of undifferentiated cells.
Corticotropes are the first cell type to be distinguished at
approximately 4 weeks of age. Prolactin cells differentiate a few
weeks later, but gonadotropes do not differentiate until at least
12 months of age. The ontogeny of both corticotropes and
prolactin cells is similar to that observed in amphibians but the
very late differentiation of gonadotropes is more likely associated
with late gonadogenesis in this species. The ultrastructure of all
three cell types is also similar to the same cell types in
amphibians. It is concluded that the pituitary of lungfish
resemble most closely that of amphibians, not only in
morphology as has been described previously, but also in
differentiation of cell types in the anterior lobe.
The family of gonadotropin-releasing hormones (GnRHs) has
been considered a vertebrate preserve until recently when new
members were discovered in protochordates and GnRHIike
immunoreactivity (GnRH-IR) was detected in neurons and
extracts from molluscs. We provide evidence that such peptides
exist and are biologically active in representatives of the lowest
invertebrates in which neurons are identifiable. Two GnRH-like
peptides were extracted by HPLC-RIA from the sea pansy R.
koellikeri and found to mimic mammalian and chicken II GnRHs
in causing an inhibition of peristaltic contractions, an activity
which involves the circular musculature in the sea pansy. As
GnRH-IR neurons were found to innervate the circular
musculature of the body wall in the sea pansy and in the starlet
anemone Nematostella vectensis, we suggest that GnRH-like
peptides are involved in the modulation of peristalsis in these
anthozoans. Supported by NSERC of Canada.
165
Immunoassays for insulin-like peptides in two flies.
BROWN, M. R.", C. CAO, and M. R. RIEHLE. Univ. of Georgia,
Athens.
A cDNA sequence for an insulin-like peptide was identified in
the database of the Drosophila Genome Project. Antisera to the
A-chain were produced and used in immunoassays.
Immunocytochemistry on whole tissues showed that only medial
neurosecretory cells were stained in the brain of Drosophila;
whereas, in Aedes aegypti, it was only in lateral neurosecretory
cells. In both flies, axons from the immunoreactive cells
extended to neurohemal sites outside the brain. Western blot
analyses confirmed the existence of immunoreactive peptides,
which were extracted from heads of both flies and resolved by
electrophoresis. Progress will be reported on the development of
quantitative immunoassays to monitor purification of the
immunoreactive peptides from both flies.
166
Proposed growth-inhibitory role of low-MW insulin-like
growth factor-binding proteins (IGFBPs) in the goby
Gillichthys mirabilis.
PEREZ, M.*, J.T. ROTH, and K.M. KELLEY. California State Univ.
at Long Beach.
IGFBP levels in the fasting goby were assessed in relation to
metabolic status and changes in somatic growth. Ten- and 20-d
fasted fish, which showed moderate hypoglycemia, exhibited
50%-reduced hepatosomatic indeces (HSI) compared with those
ABSTRACTS
167
Validation of radioimmunoassay for salmon insulin-like
growth factor-l using commercially available assay
components.
SHIMIZU, M.*, P. SWANSON, and W.W. DICKHOFF. National
Marine Fisheries Service, Seattle, WA, and Univ. of Washington,
Seattle.
Insulin-like growth factor binding proteins (IGFBPs) interfere
with IGF radioimmunoassay (RIA). Although several methods to
extract IGF from IGFBP have been developed, these methods
are not always validated for different physiological conditions
and animal species. For assay of teleost IGF, neither the
necessity of plasma extraction nor validity of extraction methods
for IGF RIA are widely established. This study was designed to
validate acid-ethanol (AE) extraction in RIA for salmon IGF-I
using commercially available assay components (GroPep Pty)1.
Displacement curves of coho salmon plasma extracted by AE
were parallel to the standard. IGF-I levels in plasma from fed and
fasted coho salmon increased after extraction and these values
were comparable to those from acid gel filtration. AE-extraction
considerably reduced the intensity of IGFBP bands on Western
ligand blotting. We thus conclude that extraction is necessary for
this salmon IGF-I RIA and AE-extraction is applicable to
measurement of IGF-I in plasma of salmon. 1 Use of trade names
dose not imply endorsement of NOAA, Dept. Commerce.
168
Alanine uptake in catfish (fctalurus punc-tatus) intestine.
TIPTON, H.A.*, R.L. LOMBARDINI, and N.L COLLIE. Texas Tech
Univ., Lubbock.
Intestinal brushborder uptake of alanine in 2-yr old catfish is
stimulated by 17-beta estradiol (E2) in 1-h incubations. This
stimulation is nutrient and tissue-region specific. Here we
followed seasonal changes in alanine transport as yearling
catfish approached 2 yr of age and tested tissue responses to
E2 (1 -500 ng/ml) in vitro. Younger catfish (<1 yr) were primed
with E2 injections in vivo and the response to E2 was measured
in vitro. Alanine uptake was highest in July and fell by 50% by
April. There were no effects of E2 in yearlings. However, in young
catfish E2 injections stimulated alanine uptake. Priming injections
also enhanced the in-vitro response of the distal intestine to E2
incubations. Age, endogenous E2 levels, and E2 receptor
expression may interact to determine E2 regulation of the gut.
169
Effect of day length on feed intake in channel catfish,
Ictalurvs punctatus.
SILVERSTEIN, J.T. U.S. Dept. Agriculture, Stoneville, MS.
This study was conducted to examine the effect of daylength
on feed consumption and growth in channel catfish. Feed
consumption in temperate fish decreases during fall-winter. This
decrease is at least partially driven by lower temperatures. The
effect of daylength has not been clear. Fish were held under 2
photoperiod regimes, 16h:8h or 8h:16h (L:D), at 21.7C. All fish
were fed to satiation at 9:00AM (during the light period). Daily
consumption was recorded and individual intake was measured
on one occasion using labeled feed. Weight gain was measured
bi-weekly. Fish on long photoperiod consumed more feed (2%
vs. 1 % body weight/day) and grew faster for about 5 weeks.
Then the effect of photoperiod abated, though the light regime
29A
164
Biological activity of two gonadotropin-releasing hormonelike peptides extracted from the cnidarian Renilla koellikeri.
ANCTIL, M.*, and K.E. DOBLE. Universite de Montreal, Canada,
and Univ. of Florida, St. Augustine.
in fed controls, suggesting utilization of hepatic energy stores
and a catabolic condition. In refed fish (13-d fast, then 7-d fed),
serum glucose rebounded to control levels, while HSI showed
partial normalization. Fasted fish also exhibited body weight loss,
a 50% reduction in cartilage ^S-proteoglycan synthetic rate, and
increased levels of 24 and 29 kDa IGFBPs in serum and in
conditioned medium from liver explant cultures (hepatic IGFBP
release) as measured by Western ligand blot analysis. All growth
parameters were restored in the refed group. These results
demonstrate that lower-MW IGFBPs in the goby are increased
with catabolic growth inhibition, suggesting possible growthinhibitory roles of these fish IGFBPs, similar to that of growthinhibitory mammalian IGFBP-1. (Supported by NSF grant IBN9600783).
was unchanged. The fish were held under these same lighting
conditions for a further four weeks and then photoperiod
treatments were reversed, i.e. the group initially on 16:8 was
changed to 8:16 and vice versa. When photoperiod was reversed
in this manner, the fish changed to long days ate more and grew
faster than short day fish. These results show a clear and
independent effect of daylength on feed consumption in this
temperate region teleost. Partial support by NSF, IBN-9722830.
170
Isolation and characterization of cDNAs encoding for
somatostatin receptor from rainbow trout.
SLAGTER, B.J.* and M.A. SHERIDAN. North Dakota State Univ.,
Fargo.
171
Sex differences in lipid metabolism during reproduction in
free-living tree lizards.
LACY, E.L.*, M.A. SHERIDAN, and M.C. MOORE. Arizona State
Univ., Tempe, and North Dakota State Univ., Fargo.
Patterns of lipid metabolism often differ between males and
females during reproduction. Sex steroid hormones (SSH) vary
within sexes across reproductive stages and between sexes
during active reproductive periods. We quantified lipid
metabolism in free-living animals across several reproductive
stages as a step toward understanding the role of SSH in lipid
metabolism. We measured lipid stores, circulating lipid
substrates, and activities of lipid regulating enzymes in liver and
adipose tissue. Lipid metabolism varied significantly across
reproductive stages in both sexes. Sex differences in lipid
metabolism appeared between animals in similar reproductive
stages, most commonly during periods of active reproduction.
The fat storage enzyme, DGAT, varied within and between
sexes. The activity of this enzyme may be regulated 1) across
reproductive cycles and 2) to differing degrees in males and
females. The observed changes in lipid metabolism may be
explained by differences in SSH levels as well as differences in
behavioral and physiological energy demands experienced
during the reproductive season.
173
Egg size and larval shell characters of geminate species in
the bivalve family Arcidae.
M0RAN,A.L Univ. of Washington, Friday Harbor.
Many Caribbean marine species have Pacific 'geminates'
that were presumably separated from their counterparts by the
rise of the Central American Isthmus. Greater egg sizes in
Caribbean echinoderms (compared to Pacific geminates) are
thought to be due to lower productivity and hence poorer larval
feeding environment in the Caribbean. If indeed related to ocean
productivity, this pattern should (1) occur in other planktotrophic
taxa and (2) first appear at the closure of the Isthmus. The arcid
bivalves, with 7 geminate pairs, are an excellent group in which
to test these hypotheses. Ripe females of 12 species, including 5
geminate pairs, were collected in Panama and egg sizes were
measured. Egg sizes are greater in Caribbean than in Pacific
geminates, in agreement with patterns seen in echinoderms.
Further, the size of Prodissoconch I (Pd I) is tightly con-elated
with egg size. Because Pd I can be measured on well-preserved
fossil shells and Central American arcids have a good fossil
record, this method provides a potentially powerful tool for
dating egg size divergence and exploring the role of the rise of
the Isthmus in driving changes in egg size.
174
Predator-induced morphological variation in predatory
snails, Nucella spp.: Tests using field experiments.
REIMER, C.T. Oregon State Univ., Corvallis.
Shell morphology is an important component of a
gastropod's defense against predators. Laboratory and field
studies have shown that one Northeastern-Pacific species, N.
lamellosa, responds to the presence of a crab (Cancer
productus) by producing thick shells with apertural teeth that are
an effective defense against these predators. Similar predatorinduced morphological change has also been described in the
Atlantic species, N. lapillus. In this study, I address the question:
How widespread is predator-induced phenotypic plasticity in the
genus Nucella? Individuals from three co-occurring species in
the San Juan Islands, WA (N. lamellosa, N. canaliculata, and N.
ostrina) were transplanted from a crab-free site to a quiet water
bay with an abundant population of C. productus. Their
morphological responses will be compared, and implications for
the evolution of phenotypic plasticity in this genus will be
discussed.
175
Division of Ecology & Evolution
172
The effects of egg size on predation rates of sand dollar,
Dendraster excentricus, larvae.
ALLEN, J.D.Univ. of North Carolina at Chapel Hill.
Current life history theory suggests that a reduction in egg
size may be costly to marine invertebrates with planktotrophic
larvae. One possible cost is an increase in larval mortality due to
predation. The effects of changes in egg size on rates of
predation upon Dendraster excentricus (Eschscholtz) larvae were
investigated through laboratory experiments with common
30A
The juvenile hormone agonist methoprene disrupts mate
recognition in Tigriopus califomicus (Copepoda,
Harpacticoidea).
TING, J.H.*, L. LETTIERI, R. GAY, and T.W. SNELL. Georgia
Institute of Technology, Atlanta.
Low levels of anthropogenic compounds may disrupt
hormonally controlled systems in animals, interfering with
growth, reproduction and development. Methoprene is an
insecticide that mimics juvenile hormone and is designed to
inhibit molting in mosquitoes. In non-target species, it has been
shown to arrest juvenile development, decrease clutch size,
delay maturity, and decrease total fecundity. We tested the
effect of sub-lethal exposure to methoprene on the marine
harpacticoid copepod Tigriopus califomicus. Animals were
exposed from egg to the first copepodite stage, and the
Somatostatins (SS) are multi-functional peptides that are
distributed throughout numerous tissues. They have been shown
to regulate a number of biological processes in vertebrates.
These effects are initiated in target cells through specific
interactions with receptors. Previously, five different somatostatin
receptors (sst) have been identified in mammals. The SS
signaling system of teleost fish, however, is more diverse; our
laboratory has reported three distinct cDNAs encoding for SSs in
rainbow trout. In order to better understand the structurefunction relationship of SS and sst and to provide greater insight
into the basis of the multi-functional nature of the SS family, we
initiated a characterization of sst sequences in rainbow trout.
Two partial sst cDNAs were isolated, cloned, and sequenced
from trout using a PCR-based approach. Sequence analysis
revealed cDNAs of 500-bp which share 92% similarity to each
other and were 73% similar to human sst1. Future studies will be
done to deduce the full nucleotide and amino acid sequence of
these two ssts. These findings indicate that trout possess
multiple ssts that may be important in modulating the biological
actions of SS.
planktonic predators. Full and half-sized embryos(obtained via
blastomere separation) of D. excentricus were exposed to zoeal
and megalopal stages of two crustacean predators: the red crab,
Cancer productus (Randall) and the Dungeness crab, Cancer
magister (Dana). There were no significant differences in
predation rates between the full and half-sized larvae. This result
was consistent across all larval stages measured. Clearance
rates of C. magister increased as the larvae developed, with
gastrulae/prism larvae having the lowest rates and 4-armed and
6-armed plutei having the highest rates. These results suggest
that halving the egg size of D. excentricus has little effect on
rates of predation relative to other factors such as predator type
or developmental stage.
following endpoints were observed: clutch size, naupliar
mortality, sex ratio, and mate guarding. Females exposed to
methoprene were significantly less attractive to males than
unexposed females in a male choice assay. All other endpoints
showed no significant effects at the concentrations tested. Mate
recognition is mediated by pheromones in Tigriopus, and
pheromonal expression is most likely hormonally controlled.
Disruption of mate recognition, therefore, suggests that
methoprene acts as an endocrine disrupter in these copepods.
176
Differential behavior of arctic woollybear caterpillars
[Gynaephora groenlandica) with respect to thermal
characteristics of several tundra microhabitats on Ellesmere
Island, NT (82'N).
BENNETT, V.A.*, O. KUKAL, T.F. ALLEN, and R.E. LEE. Miami
Univ., Oxford, OH, Univ. of Victoria, Canada.
177
Response of juvenile western toads, Bufo boreas, to
chemical cues of snakes fed juvenile and larval conspecifics.
BELDEN, L.K.*, E.L. WILDY, A.C. HATCH, and A.R. BLAUSTEIN.
Oregon State Univ., Corvallis.
Previous investigations have demonstrated the importance of
predator diet in chemically mediated antipredator behavior.
However, there are few data on responses to life-stage specific
predator diets. This could be important for animals like
amphibians that undergo metamorphosis and must respond to
different suites of predators at different life history stages. In
laboratory choice tests, we investigated the chemically mediated
avoidance response of juvenile western toads, Bufo boreas, to
four different chemical stimuli: 1)live conspecific juveniles, 2)live
earthworms, 3) snakes fed juvenile conspecifics, and 4) snakes
fed larval conspecifics. Juvenile toads avoided chemical cues
from snakes that had eaten juvenile conspecifics, but did not
avoid the other three stimuli, including chemical cues from
snakes fed larval conspecifics. This study demonstrates the
importance of diet in predator avoidance by juvenile anurans and
the ability of juvenile toads to distinguish between chemical cues
from predators that have consumed larval versus juvenile
conspecifics.
178
Oligosaccharide structure of a mate recognition pheromone:
Comparison of three closely related rotifer species.
DINGMANN, B.J.'and T.W. SNELL Georgia Institute of
Technology, Atlanta, GA.
Mate recognition in rotifers is mediated by a glycoprotein on
the surface of females that serves as a pheromone that triggers
mating behavior in males. Males identify potential mates by
contact chemoreception of this pheromone, and localize to the
corona of females where penile attachment occurs. A
glycoprotein (gp29) has been isolated and sequenced that acts
as a mating pheromone. The carbohydrate moiety has been
analyzed using MALDI-mass spectrometry to more accurately
describe its structure. A comparison of the carbohydrate moiety
among three closely related rotifer species will be presented.
This research contributes to the understanding of how chemical
ABSTRACTS
179
Size-biased, female mate choice in a population of the
American toad infected by a trematode.
HRANITZ, J.M. Univ. of Central Oklahoma, Edmond.
A fundamental assumption of parasite models of sexual
selection is that females choose mates with lowest parasite
loads and that comparisons of mated and unmated males should
reveal that females mate with uninfected males more frequently
than infected males. I compared the mating success of male
toads using 1997 census data from a population of Bufo
americanus. I monitored reproductive activities of 69 toads,
measured toad mass and SVL, and examined toads for an
encysted trematode, Clinostomum marginatum. I collected all
amplectant pairs (N=14) at this locality in 1997. Frequency of
infection (24.6%) did not differ between males and females, or
recaptured toads and new recruits. In both sexes, uninfected
and infected toads did not differ in size. Although mated and
unmated males did not differ in their frequencies of infection,
mated males were larger than their unmated counterparts. These
results suggest that encysted trematodes may not affect
expression of male reproductive traits, female toads may have
selected larger males, independent of parasitism, or low
correspondence between male reproductive traits and parasitism
may have precluded females from distinguishing uninfected from
infected males.
180
Are halogenated hydrocarbons effective predator deterrents
for infaunal organisms? Effects of compound type and prey
size.
EDWARDS, D.R.* and S.A. WOODIN. Univ. of South Carolina,
Columbia.
Halogenated hydrocarbons are widespread among
hemichordates and polychaetes in temperate sedimentary
environments. The bromophenols produced by some larger
(>3cm) macroinfauna act as predator deterrents. However, many
of the infaunal organohaline producers are small (<1cm), and
produce a variety of halogenated compounds, including
branched aliphatic halides, bromopyrroles, and
bromovinylphenols. In this study, we examine whether small
individuals with such compounds are less palatable to infaunal
predators than similarly sized individuals without, and whether
payability varies according to compound produced.
Mummichogs {Fundulus heteroclitus), striped killifish [Fundulus
majalis), and spot (Leiostomus xanthurus) were offered equal
numbers of both individuals without (Nereis) and with
halogenated compounds {Streblospio benedictii, Tharyx marioni,
or Mediomastus califomiensis). These results are compared to
those obtained by feeding the above fish small artificial prey with
and without bromophenols. The effect of prey size is examined
by testing the fishes' response to larger artificial prey infused
with biologically realistic concentrations of the test compounds.
181
Detoxification differences of specialist and generalist
herbivores.
DEARING, M. D., J. SORENSEN", A. M. MANGIONE, and W. H.
KARASOV. Univ. of Utah, Salt Lake City, and Univ. of Wisconsin,
Madison.
Limitations of the mammalian detoxification system have
been proposed to explain the preponderance of dietary
generalism among mammalian herbivores. To test this
hypothesis, we investigated detoxification processes of closely
related generalist (Neotoma albigula) and specialist (N. stephensi)
herbivores. The generalist and specialist were fed a diet
containing alpha-pinene, the predominant secondary compound
found in Juniperus monosperma, the host plant of the specialist.
When consuming the same dose of alpha-pinene, the specialist
excreted a less acidic urine than the generalist. Six detoxification
metabolites were produced by both the generalist and specialist
consuming a diet with alpha-pinene. Although the specialist and
generalist excreted the same detoxification metabolites of alpha-
31A
During their short active season (June), G. groenlandica
caterpillars can elevate body temperatures as much as 20°C
above ambient temperature by basking, which increases their
metabolism and efficiency of food assimilation. G. groenlandica
body temperatures change rapidly in response to changing
substrate temperatures (due to snow cover, cloud cover, or
incident sunlight). Caterpillars are most frequently associated
with one of three plant microhabitats: Salix arctica, Dryas
integrifolla, or Cassiope tetragona. All microhabitats showed
marked diurnal thermal cycles, even though the sun remained
continuously above the horizon in June. Most caterpillars on D.
integrifolia, the warmest microhabitat, were found basking. In
contrast, caterpillars found on S. arctica, which was only slightly
cooler, were mostly feeding. Very few caterpillars were found on
C. tetragona, which was significantly cooler. Of the caterpillars
found on bare tundra, most were either travelling or parasitized.
structure of the mate recognition pheromone determines mate
recognition in the phylum Rotifera.
pinene, the amounts of differed. On the same dose of alphapinene, the generalist excreted nearly 2x as much glucuronic
acid, a detoxification conjugate. The results suggest that the
energetic and physiological costs of detoxification are lower for
the specialist than the generalist.
182
Isolation and characterization of microsatellite loci from the
red snapper, Lutjanus campechanus.
WRIGHT, K.L.* and S.Y. WANG. Univ. of Southern Mississippi,
Hattiesburg.
183
RAPD analysis of the Japanese eel, Anguilla japonica.
KATOH, M.* and M. KOBAYASHI. Seikai National Fisheries
Research Institute, Okinawa, Japan.
The recent decline of glass eel, Anguilla japonica, catches in
East Asia has caused serious problems in eel aquaculture in
Japan and Taiwan. Adult eels migrate several thousands of
kilometers to spawn as the spawning site of the Japanese eel is
west of the Mariana Islands. Leptocephali migrate back to the
freshwater habitats in Taiwan, mainland China, Korea and Japan.
The limited spawning area suggests that the Japanese eel is one
large panmictic population throughout East Asia. However,
synchronized spawning of eels occurs during several
consecutive new moon periods, which suggests more than one
eel population is present. Moreover, a previous allozyme study of
recruiting glass eels collected along the East Asian coasts found
clinal changes of allele frequencies at two loci. We compared the
frequency difference of each RAPD band to investigate genetic
structure of the Japanese eel between Taiwan and Japan. Tenbase random primers were used for DNA amplification through
PCR. Nineteen primers produced bands and intra-specific
genetic variation was revealed. Genetic information on the
populations of glass eels in East Asia is necessary to provide
effective management for this important fishery resource.
184
Identification of microsatellite DNA markers for the parasitic
wasp Cotesia congregata (Say)[Hymenoptera: Braconidae].
JENSEN, M.K.*, B.L BROWN, and K.M. KESTER. Virginia
Commonwealth Univ., Richmond.
Microsatellites were identified in Cotesia congregata, an
endoparasitoid of many sphingids including Manduca sexta L .
Microsatellites are composed of short DNA sequence units
repeated in tandem and dispersed throughout the genome. D>JA
was extracted from wasps to create a DNA library which was
screened for the presence of various oligonucleotide repeats.
Differences in microsatellite allele frequencies were used to
discern genetic separation among C. congregata populations.
Approximately 3000 colonies, of which 78% were transformed,
were screened for presence of tri- and tetrameric repeats in the
inserts. Eighteen potential microsatellite markers were detected
and sequenced. Mendelian inheritance was verified, and wild
populations were tested to determine population levels of
polymorphism. Results detail the levels of spatial and temporal
32A
185
Population genetic structure of the cricket frog, Acris
crepitans.
ESTEP, A.D.* and J.M. HRANITZ. Univ. of Central Oklahoma,
Edmond.
Although genetic variation in A. crepitans has been described
throughout most of its range, a hierarchical sampling design that
may detect genetic structure among localities at different spatial
scales has not been used. Our goal was to describe the genetic
structure of six populations, containing two or three
subpopulations, along a 350 Km east-west transect in central
Oklahoma,. Nine allozyme loci were resolved in a total of 320
frogs using starch gel electrophoresis. Populations did not differ
in the mean number of alleles per locus, polymorphism, or mean
heterozygosity. No deviation from HWE occurred at the
polymorphic loci studied. F-statistics revealed no appreciable
inbreeding (f=-0.060; 95% CI=-0.225, 0.102) or subdivision
within subpopulations (F=0.013; -0.203, 0.140) but, detected
subdivision within populations (TP=0.044; 0.006, 0.075) and
genetic divergence (TS=0.068; 0.010, 0.121) among populations.
Contingency chi-square analyses showed that the population
subdivision occurred in only two populations and that the
remaining four populations were not subdivided. These results
indicate that gene flow may be a cohesive force among frogs at
localities separated by less than about 10 Km in our transect.
186
Ecological comparison of three populations of
mediterranean gecko.
HIBBS, T.S.*, H.A. MEYER, and M.A. PAULISSEN. McNeese
State Univ., Lake Charles, LA.
Hemidactylus turcicus is an introduced gecko that has
established colonies along the Gulf Coast. A demographic
survey was conducted of populations on three buildings on the
campus of McNeese State University to provide baseline
information for studies involving population dynamics and
genetic variability. The survey showed a significant difference in
population density among buildings as well as a significant
difference in the size of males. A sampling of food availability
showed insect density to be fifty times greater on the building
with the greatest population density and the larger geckos.
187
The reproductive behavior of the wetland perennial Iris
hexagona in response to floral predation and salinity stress.
TOBLER, M.', P.A. VAN ZANDT, and S. MOPPER. Univ. of
Southwestern Louisiana, Lafayette.
Individual plants have a finite amount of resources that are
available for maintenance, vegetative growth, and reproduction.
Because of this, resources allocated and spent on one activity
are generally unavailable for allocation to another activity. In
clonal plants the production of flowers and fruit may limit current
asexual reproduction, and/or constrain parental sexual
reproduction in the future. Therefore, if a plant can enhance its
overall lifetime fitness by producing asexual propagules, then the
ability to allocate resources differentially in response to biotic
(e.g. floral predation) and abiotic (e.g. salinity) factors would be
advantageous. We conducted a common garden experiment to
examine the effect of salinity and sexual reproductive loss on the
asexual propagation of a native wetland perennial. We grew 46
plants in low and high salinity (0.4 and 6.0ppt) treatments and
artificially removed all flowers from half of the plants in each
treatment. The results are linked with field data from Marsh
Island Wildlife Refuge that show deer floral predation greater
than 99 % for 10 sub-populations surveyed.
Red snapper is an important fish species that supports both
commercial and recreational fisheries in the Gulf of Mexico. The
species is targeted for both stock management and
enhancement. The goal of this project is to identify microsatellite
markers useful for population genetic analysis. A genomic library
containing DNA inserts in the 300-600 bp range was constructed
using the bacteriophage cloning vector ZapExpress. Screening
of the library using di-, tri-, and tetranucleotide repeats revealed
uneven distribution of the microsatellites in the genome as
expected. Among the nine microsatellite probes used, (AC)n,
(GA)n, (AAC)n, (AAG)n, (AAT)n, (ACG)n, (ACT)n, (ATQn, and
(AAAT)n, the most and least frequently encountered repeats were
(AC)n and (AAATJn at 1.6 and 0.06%, respectively. The validity of
the frequency observations, which is influenced greatly by the
hybridization efficiency of the probes, awaits confirmation by
sequencing data. PCR primers based on the sequence data will
be used to characterize microsatellite loci of red snapper from
the northern Gulf of Mexico.
variation in laboratory and wild populations with respect to food
plants of their hosts.
188
191
Unique ecosystem in Roatan, Honduras.
ROSEBROCK, T.R.* New College at the Univ. of South Florida,
Sarasota.
An occurance and classification of Acropora cervicomis
abundance in nearshore waters adjacent to Ft. Lauderdale,
Florida.
HERBER, S.A.' and J.D. THOMAS Nova Southeastern Univ.
Oceanographic Center, Wilton Manors, FL
The degradation of a small reef off of Bailey's Cay, Roatan,
Honduras, has led to a unique ecosystem where the grassflat
community has migrated into the reef. Bailey's reef now provides
an ideal habitat for two common species of octopus, 0. briareus
and 0. vulgaris, where shelter is located in proximity to a rich
food source. Continuing an observational study begun in 1998,
an evaluation of the Bailey's Cay octopus population was
completed in 1999. Den sites for both species were tagged and
mapped providing a rough estimation of hunting 'territories'. Prey
selection was determined through daily evacuations and
identification of debris found in den middens. Both species
consume the pitho aculeata crab, which provides up to 95
percent of their diet. Direct competition may be limited between
these two species given their alternate hunting times. 0. vulgaris
can be found actively hunting during the afternoons whereas O.
briareus remains dormant throughout the daylight hours.
189
Since 1886 effluents from Marseille, French Mediterranean
coast with 1 million people are discharged into the Cortiou cove
on the shore line, only the larger debris was removed from the
effluents. A primary treatment plant which services a population
of 1,500,000, has been in operation since October 1987, the
input at sea decreasing from 20,000 T/year of dry solids in 1986
to presently, 1,300 T/year. Since 1965 macrobenthic
assemblages have been studied in the area surrounding the
sewer outfall of Marseille, on both hard and soft substrates. The
evolution of these assemblages was studied while the multiple
qualitative and quantitative evolutions of the effluents were
occuring (Bellan-Santini et al., 1993, Bellan et al., 1999). After
eight years of operation, limited but dramatic data on the benthic
communities surrounding the outfall showed strong signs of
recovery and indicated a significant improvement in the quality of
the marine environment as previously demonstrated by
conventional statistics (Bellan et al., 1999). The major goal of this
paper is to substantiate the importance of the analysis of
parcimony (cladistics) widely used in taxonomy (Dariu et Tassy,
1993) and bio-geography (Cracraft, 1994) as an ecomonitoring
tool as suggested by Lambshead (1986), Bellan-Santini et al.
(1994), Bellan-Santini et Bellan, 1997, Deets and Roney (1998),
among few others.
190
Changing coral reef concepts, definitions, and realities.
BUDDEMEIER, R. W.', B. O. OPDYKE, J. A. KLEYPAS, and J.-P.
GATTUSO. Univ. of Kansas, Lawrence; Austral. Nat. Univ.,
Canberra, NCAR, Boulder, CO and CNRS-UPMC, France.
By 2100, critical environmental conditions for carbonateproducing ecosystems may be more similar to the early Eocene
than to human experience. Key factors will be reduced calcium
carbonate saturation state of surface ocean water and global
temperature elevation due to the anthropogenic greenhouse
effect. To predict future responses and understand observed
changes, we must understand and resolve differences between
geological and biological views of reefs. We apply two tools: use
of biogeochemical function to link biology and geology; and,
explicit consideration of temporal and spatial scales in the
definition and application of terms and concepts. Carbonate
production and accumulation — rates, loci, controls, and
especially agents and their habitats — are quantifiable defining
characteristics of reef systems that relate real-time observations
to geologic records. Both upscaling and downscaling are needed
to interpret local manifestations of global change using longterm, low-resolution earth history records. Careful attention to
scales is essential to avoid fallacious extrapolations between
short-term, local observations and the geologic record.
ABSTRACTS
192
Is evolution in the color vision system of Hawaiian
damselflies adaptive or neutral?
BUTLER.M.A. Institue of Statistical Mathematics, Tokyo Japan.
How molecular mechanisms produce the diversity of spectral
sensitivities in visual systems remains unanswered in visual
evolution. Although animals have a limited number of visual
pigments, they are able to interpret the tremendous array of
environmental light stimuli in finding mates, food, and
appropriate habitat. Therefore, the light environment should be a
potent selective force in the spectral tuning of visual pigments. I
investigated visual pigment evolution in Hawaiian Megalagrion
damselflies. This relatively small genus is an adaptive radiation
with a large range of variation in breeding ecology (light
environments) and body coloration, comparable to that of the
remainder of the suborder. I used a combination of physiological
and molecular techniques to study variation in the visual system
among species. I characterized the number and spectral location
of functionally different visual pigments using electroretinography
and intracellular recordings, and PCR based cloning and
sequencing techniques to deduce the molecular sequence of
opsins. I tested hypotheses of adaptive evolution of visual
pigments, relative rates of evolution among opsins, and the
relationship between amino acid sequence and function.
193
The contribution of maximal growth rate, growth efficiency
and starvation resistance to fitness in thermally-selected
bacteria.
CULLUM, A.J.', A.F. BENNETT, and R.E. LENSKI. Univ. of
California, Irvine and Michigan State Univ., East Lansing.
Replicate lines of Escherichia coli were previously cultured
for 2000 generations at 20"C, 32'C, 37*C and 42°C in a 'feast or
famine' environment, resulting in significant adaptation to these
temperatures. Because the standard culture conditions feature
alternating periods of resource abundance and resource
absence, we hypothesized that the increased fitness in these
lines could be the result of increased maximal growth rate,
increased growth efficiency, increased resistance to starvation,
or a combination of these. In this study, we examine the relative
contributions of these three variables to the fitness
improvements seen in these evolved lines. Data collected to date
suggest that improvements in growth rate are important for
adaptation to temperatures near the ancestral 37X), but not to
critical temperature environments (20*C and 42"C), where
stressful conditions may make growth efficiency or starvation
resistance more vital. Funded by an NSF postdoctoral fellowship
to AJC and NSF-IBN 9507416 and NSF-IBN 9905980 to AFB
and REL
33A
Cladistics as a tool for the ecomonitoring of the benthic
communities in a stressed environment.
BELLAN, G.L.* and D. R. BELLAN-SANTINI Centre National de la
Rechercher Scientifique, Marseille, France.
Numerous colonies of the scleractinian coraWcropora
cervicomisbave been discovered in the coastal waters adjacent
to Ft.Lauderdale.Florida,between Hillsboro Inlet and Port
Everglades Inlet. The extent of coverage between the inlets
appears restricted to bottom topography. Initial data indicates
the colonies are primarily found in shallow waters(<5 m),hard
bottom zones and the colonies are not always congruent with
each other. Mapping and classification of this unexpected
occurrence are in process and will include classification of the
colonies ofA cerv/com/sinto distinct categories for descriptive
purposes. A map of this specific area was divided into
quadrates. Each quadrate was individually assessed for the
occurrence ofAce/v/com/s.Percentage of coverage and
distribution ofAce/v/com/swithin each quadrate was ascertained.
The colonies were then classified .The classification scheme was
based on, but not limited to bathymetry, location.distribution
pattern,and size of the outcrops. This data will assist in future
assessment of Ace/v/com/scolonies,including succession,
regression,and migration.
194
197
Laboratory evolution modifies heat shock transcription
factor (HSF) activation in Drosophila melanogaster.
LERMAN, D.N.* and M.E. Feder. Univ. of Chicago, IL.
Cold hardiness of hatchling painted turtles is influenced by
nest soil characteristics, but not geographic origin.
COSTANZO, J.P., J.D. LITZGUS, J.L. LARSON*, J.B. IVERSON,
and R.E. LEE, JR. Miami Univ., Oxford, OH and Earlham College,
Richmond, IN.
Hsp70, the major heat-inducible stress protein in Drosophila
melanogaster, decreases in expression in populations evolving at
a high temperature, 28°C (Evolution 53: 484-492). To determine if
this evolutionary modification results from differences at the level
of transcriptional regulation, we investigated whether thermal
sensitivity of activation of the heat shock transcription factor
(HSF) differs between this line and others evolving at lower
temperatures (18'C and 25°C). We performed electrophoretic
mobility shift assays (EMSAs) on larvae heat-shocked at diverse
temperatures. At lower heat-shock temperatures (30*-33°C), flies
from the18°C line showed greater HSF activation than those from
both the 25°C and 28"C lines. At higher temperatures, however,
the lines did not differ. These results indicate that modification of
HSF activity accounts for some, but not all, of the differences in
Hsp70 expression found in these lines, and suggest that
variation in HSF activation temperature may play a role in
shaping the evolution of the heat shock response. Supported by
NSF IBN97-23298 and HHMI.
This investigation explored how nest soil characteristics and
place of turtle origin influence cold hardiness of hatchling
painted turtles (Chrysemys picta) native to Indiana and Nebraska.
Nests explanted from the Indiana site were cooled in the
laboratory to minimum temperatures of -2.5 to -6 degrees C
(duration 7 to 28d). Survival of turtles in the nests ranged from
30-100%. Additional experiments demonstrated that water
content of the soil in which hatchlings were cooled greatly
affected their ability to resist freezing. Hatchlings from Indiana
resisted freezing better than those from Nebraska when cooled
in their respective native soils hydrated to 15%; however, this
difference was attributable to variation in native soil
characteristics, and not physical differences in the turtle
populations. We conclude that variation in physical
characteristics of soils at different geographic locales, and
among nesting sites at the same locale, is an important
determinant of overwintering success of hatchling C. picta.
Food habits of two populations of largemouth bass,
Micropterus salmoides, were investigated to explore intraspecific
variation in prey resource utilization by a species encompassing
a broad geographic and climatic home range. Florida bass were
sampled from three lakes in east-central Florida. Bass from
Michigan were collected from four isolated lakes in southwest
Michigan. Standard length was recorded and stomach contents
were removed via tube- purging. Formalin fixed gut contents
were classified into the following functional categories: plankton,
insect, shrimp, crawdad, fish, and other. Volumetric analyses of
gut contents demonstrated a significant difference in the onset
of piscivory between the two populations. Michigan bass utilize
plankton for a greater period of time (beyond 60mm SL) than do
their Florida conspecifics (up to 40mm SL). Following a shift to
piscivory, Florida bass begin including alternative prey resources
(e.g. shrimp) to a greater extent than fish until 200mm SL.
Michigan bass, however, once shifted to piscivory, maintain a
diet composed of significantly more fish with fewer alternative
prey resources.
Integrative and Comparative Issues
198
Integrating an international experience into research
education.
GILCHRIST, S.L New College at the Univ. of South Florida,
Sarasota.
Research education for undergraduate students should allow
students to integrate local and global experiences. At New
College, students interested in ecology, population biology,
neurobiology and behavior are given practical research
experience through classes and independent studies from their
first year. During the summer, selected students from different
year classes design and implement experiments at the Institute
of Marine Science at Roatan, Honduras. Students work with
faculty to create projects that can be completed at the home
institution in Sarasota, Florida. Students then present work at a
national meeting, allowing faculty to bring the research
experience full circle for students. This has been a valuable
approach for immersing students in the excitement and
practicality of science.
196
199
Functional morphology of raptor hindlimbs: A comparative
study of owls and hawks.
WARD, A.B.*, P.D. WEIGL", and R.M. CONROY. Wake Forest
Univ., Winston-Salem, NC.
Use of museum specimens in undergraduate and K-12
instruction by means of images on the Internet.
JOHNSON, J.I.', M.LEGARE, W.I. WELKER, A.J.FOBBS, A.NOE,
N.HUMBLOT, K.L.GRAEME, C.L.DIZACK, J.A.MORRIS,
P.M.GORAYSKI, R.A.CARLONI, S.E.SHEPPARD, B.M.WINN, and
C.E.OSBORN. Michigan State Univ., E. Lansing, California State
Univ., Sacramento, Univ. of Wisconsin, Madison, Nat. Mus.
Health & Medicine, AFIP., Washington, D.C.
Prey capture in owls and hawks is largely dependent on the
biomechanics of hindlimbs, and both limb size and talon forces
potentially determine the prey size range and the extent of
possible resource partitioning among sympatric species.
Anatomical study and muscle measurements of six species of
sympatric raptors: the owls — Otus asio, Strix varia, and Bubo
virginianus — and the hawks commonly considered their diurnal
'ecological equivalents' — Falco sparverius, Buteo lineatus, and
Buteo jamaicensis — revealed that, in both groups, talon closure
is effected by a recently described dual and additive system of
muscle action. Grip force measurements obtained from live owls
and hawks using a type of 'hydraulic' perch showed that grip
force increases exponentially with body size and that owls
appear to produce greater forces than hawks. This finding is
consistent with their distinctive foot anatomy, muscle structure,
and hunting behavior. These data provide some understanding
of the different demands of diumal and nocturnal hunting as well
as the mechanism of coexistence for these six species in eastern
woodlands.
34A
As an example of 'virtual specimens on demand', we
presented images of brains on the Internet, at websites
http://www.msu.edu/user/brains and
http://www.neurophys.wisc.edu/brain, for use by students in the
undergraduate course: Introduction to Neuroscience. Students in
Sacramento downloaded images of stained sections and of
whole brains of ten different mammalian species. They then used
these virtual specimens in the construction of posters for
instructing other undergraduate, high school, and grade school
students. In this way stained sections and whole-brain photos of
specimens physically located in Washington, DC, East Lansing,
Ml, and Madison, Wl were readily used for instruction in
Sacramento, CA. Our presentation at this conference will include
demonstrations of the websites as well as of posters produced
by the students who downloaded images and text from the
websites. Supported by NSF grants IBN 9812712, 9814911,
9814912.
195
Dietary switch through ontogeny in largemouth bass,
Micropterus salmoides: A comparison between subtropical
and temperate lakes.
HUSKEY, S.H.* and R.G. TURINGAN. Florida Institute of
Technology, Melbourne.
200
Estrogen as a theme for an undergraduate physiology lab.
CLEMENS, J.W.* and K.W. SELCER. Duquesne Univ.,
Pittsburgh, PA.
The synthesis, systemic effects, and trophic effects of
estrogens were examined in an Experimental Biology:Cell and
Systems Physiology course. Labs reinforced reproductive
physiology lectures with an inquiry-based approach. For
example, mechanisms of ovarian steroidogenesis and hormonal
immunoassay principles were presented to students. They then
used a 17beta-estradiol ELISA kit to determine the estradiol (E2)
content of media from rat granulosa cells treated with steroids
and gonadotropin. The estrogenic effects of E2 on rodent uterine
tissues were examined by determination of E2-induced increases
in uterine wet weight and protein content. In addition, uterine
proteins were subjected to SDS-PAGE and Western blotting for
estrogen receptor. Finally, estradiol's trophic effect on growth of
MCF-7 breast cancer cells was examined by MTT assay.
Students then presented PowerPoint talks modeled after
scientific meeting presentations. Using contemporary analytical
methods, multiple model systems, and the theme"" of estrogen
students gained an in-depth understanding of female
reproductive physiology at multiple organizational levels.
Students taking this lab showed enhanced interest and abilities
in reproductive physiology.
Teaching how protein information can be used to distinguish
biological species: An Azorean model.
COSTA, M.J. and C.P.BRITO. Univ. of Azores, Ponta Delgada,
Portugal.
In the Azores, two dominating periwinkle species can be
recognised by evident morphologic characteristics such as size,
colour or shell pattern: Litorina striata and Melarhaphe neritoides
. These abundant molluscs of the rocky intertidal exhibit a red
radular muscle, which can be isolated. In a biomolecular
laboratory, myoglobin-like proteins can be extracted in one step,
with a considerable degree of purity. Such proteins, identified
after polyacrylamide gel electrophoresis and specific peroxidase
staining, can be used to distinguish the species after isoelectric
focusing. In this work, field and laboratory observations are
confronted in a teaching context as their role as specific markers
is discussed. Altogether, the easiness of sample handling,
experimental design and straightforward conclusions are
experienced by students, allowing a clearer insight on how
proteins can be used as molecular markers. The abundance of
information on myoglobin structure and function (a classical
textbook example) as well as myoglobin diversity can be
explored to illustrate theoretical aspects on protein concepts.
202
Isolated earthworm gut as a model of smooth muscle
properties.
KRAJNIAK, K.G.* AND R.W. KLOHR. Southern Illinois Univ.,
Edwardsville.
The classical laboratory demonstrating smooth muscle
properties uses isolated organs like rabbit ileum. However, there
are drawbacks. The organs must be handled carefully since
contamination inhibits contractions and maintained at the body
temperature of the animal. Also, mammals are costly, require
special care, and may need institutional approval. We have
developed a comparable laboratory with the earthworm cropgizzard. Worms can be purchased for a few dollars, kept in a
refrigerator, and used at room temperature. Since they are
invertebrates, no special permit is required. In this lab students
remove the crop-gizzard from the worm and place it in a tissue
bath at room temperature. Once the tissue is connected to a
recorder, students can monitor spontaneous contractions and
effects of neurotransmitters like acetylcholine and serotonin.
Acetylcholine causes an increase in contraction rate and a
biphasic change in amplitude, while serotonin causes a decrease
in both contraction rate and amplitude. These responses are
similar to those caused by neurotransmitters in the isolated
mammalian digestive tract. Thus the worm experiment can show
the same properties without the drawbacks.
ABSTRACTS
203
Shell cycling from reef to shore: Influence of hurricane Mitch
on hermit crab populations at Bailey's Cay, Roatan,
Honduras.
GILCHRIST, S.L. New College at the Univ. of South Florida,
Sarasota.
Over the past five years, the distribution of shells used by
hermit crabs has been characterized in the shallow reef area of
Bailey's Cay. In 1998, Hurricane Mitch pounded the Cay
resulting in scouring and in removal of algae and some corals
(damage to about 20 feet). Prior to the disturbance, distribution
of hermit crab species and predator species showed distinct
zonation. After Mitch, the crabs and their predators still
maintained some zonal identities, but the shells used by crabs
were redistributed across zones. Crabs on average were smaller
than in previous years and shells in each zone were heavily
damaged.
204
Stability and flux in the rocky intertidal.
PEARSE, J.S.', E. DANNER, L WATSON, AND C. ZABIN. Univ.
of California, Santa Cruz.
Invertebrate and algal species richness and abundance of
common species were compared at 10 rocky intertidal sites on
northern Monterey Bay, California in 1971-73 and 1995-97 by
teams of trained undergraduate students. Species richness
(number of species found) was as high or higher at almost all the
sites in the mid 90s as in the early 70s. The abundance of
common species also remained stable, as did the pattern of
similarity among the sites - despite droughts, El Ni&ntildeo
associated storms, earthquakes, and increased human
disturbance during the intervening years. On the other hand,
species composition varied considerably between the time
periods: only about 50% of the species at each site were found
during both periods. The flux in species composition did not
follow any obvious trend (e.g., reflecting suspected global
warming), but instead appeared to be chaotic, reflecting the
rarity of most species and the contingency of their being found
during the surveys. Supported by California Sea Grant, Monterey
Bay National Marine Sanctuary, and Association of Monterey
Bay Area Governments.
205
Bathymetric distribution of amphipods in the Mediterranean
Sea.
BELLAN-SANTINI, D. Centre d'Oceanologie de Marseille Station
marine d'Endoume, France.
The Mediterranean benthic amphipods fauna consists of 451
species, 167 genera and 48 families (Bellan-Santini et al. 1999).
The bathymetric distribution of families is richer in the 0-35m
zone (35 families), then decreases, 28 species at 35-150m, 29 at
150-500m, 17 at 500-2000m and 8 beyond 2000m. The
maximum number of genera is between 0 and 35m (110 genera),
107 at 35-150m, 88 at 150-500m, 51 at 500-2000m and 22
beyond 2000m. The maximum number of species is in the 035m zone (310 species), 214 in the 35-150m, 128 between 150500m, 62 between 500-2000m and 28 beyond 2000m. The high
number of endemic species, 166, is a very significant feature of
the Mediterranean amphipod fauna. The percentages vary
considerably from surface to the bathyai. The high percentage of
endemics in the supra-mediolittoral zones is due to the greater
possibilities of isolation. The high percentage in the bathyai
reveals the originality of the Mediterranean component and its
indo-pacific affinities. In conclusion: -the highest diversity at all
taxonomic levels and the strongest speciation are in the Infra
and Circalittoral with the highest number of different
environments.-the representation at the specific level in the
deepest zones is very weak with a high endemicity. This seems
directly linked to the Tethysian history of the Mediterranean and
to our present knowledge of this sea.
35A
201
Division of Integrative Zoology
206
209
Bioremediation of petroleum contaminated soil as monitored
by mini-biocells under laboratory conditions.
CUNNINGHAM, S.L* and R.C. MARIS. Mansfield Univ. of
Pennsylvania.
Tube dwelling cumaceans?
GERKEN, S. Univ. of Maine, Walpole.
The potential of petroleum spills possesses a significant
threat to the natural environment. Such eminences have
prompted the necessity for alternative methods of contaminated
soil treatment. Studies at Mansfield University, over the last five
years, have centered around the breakdown of toxins by
naturally-occurring microbes, or bioremediation. Investigations
have utilized bacterial growth studies with drying and organic
ashing in soil excavated from petroleum spills and in artificiallymaintained external biocells. The present study employed the
use of mini-biocells. Daily samples were taken over a one-week
period to examine immediate effects of contamination on the soil
ecosystem. Biodegradation was likewise monitored over an
eight-week period. All methods indicated that gasoline toxicity
was consistently lowered to safe levels after several weeks. Even
though levels of contamination were reduced in the diesel
biocell, total remediation will take longer than eight weeks.
Overall, bioremediation has proven to be an economical and
ecologically effective alternative in the restoration of petroleumcontaminated soil.
Identification of symbiotic chloroplast proteins that may be
encoded in the host molluscan genome {Elysia chlorotica).
HANTEN.J. J . ' and S. K. PIERCE. Univ. of Maryland, College
Park.
Digestive cells in the ascoglossan mollusc, Elysia chlorotica,
sequester chloroplasts from their algal food source, Vaucheria
litorea. The plastids remain photosynthetically active within the
slug for as long as nine months. During this period, plastid
proteins necessary for photosynthesis are synthesized, including
some which are produced in the presence of chloramphenicol, a
chloroplastic ribosomal inhibitor. These same proteins are
inhibited by cycloheximide, a cytosolic ribosomal inhibitor, which
suggests that the genes encoding their expression are located in
the molluscan DNA. Western blot analysis has identified some of
these plastid proteins as members of the light harvesting
complex I family. (Supported by the NSF)
208
Life history of a hydroid/nudibranch association: A discreteevent simulation.
CHESTER, CM.*, R. TURNER, M. CARLE, and LG.HARRIS.
Spring Hill College, Mobile, AL, Univ. of Maine, Orono, and Univ.
of New Hampshire, Durham.
The general paradigm for early community succession is that
early colonists do not replace themselves. Hydroids are typical
early colonists that play an important role in the recruitment of
later species. Aeolid nudibranchs are important predators on
hydroids, and may thus have an indirect impact on succession.
In an attempt to understand the mechanics of community
change, we modeled nudibranch-hydroid community dynamics
using a discrete-event simulation. Data for the model was
obtained from life history studies of the aeolid nudibranch
Tenellia adspersa (Nordmann, 1845) and its hydroid prey
Cordylophora lacusths (Allman, 1853). Seven simulations were
performed, varying adult immigration, emigration, and larval
settlement. The results of these simulations have important
implications for early community succession and the role of
nudibranchs in the persistence of hydroid colonies. In all
simulations, the hydroid colony was completely removed by T.
adspersa. Cordylophora lacustris persisted for the longest time in
simulations with no adult migration or larval settlement. In
addition, nudibranchs persisted for up to 46 days after their food
supply was exhausted. These predictions suggest that Tenellia
adspersa can play an important indirect role in succession by
removing hydroids and preventing their re-establishment.
36A
210
Tentacle branching pattern in the sea anemone family
Actinodendridae Haddon 1898.
ARDELEAN, A. Univ. of Kansas, Lawrence.
The family Actinodendridae is a monophyletic group of three
genera of exclusively tropical sea anemones. They have the oral
disc drawn out into a variable number of ramified lobes that
make them resemble a tree. My research focuses on the
structure of the tentacles and their growth pattern, characters
that are species-specific and therefore valuable for taxonomy.
The genera of Actinodendridae have been defined on the basis
of the disposition of secondary branches on the oral lobes. I
suggest that the growth pattern of the terminal branches is of
more importance in defining genera. My findings may require one
or more additional genera of Actinodendridae. Supported by
NSF grant DEB95-21819 in the PEET program to D. G. Fautin.
211
Relationships among the Zoantharia.
DALY, M. The George Washington Univ., Washington, D.C.
The Zoantharia (Cnidaria:Anthozoa) exhibit a diversity of
morphotypes, including solitary and colonial organisms, softbodied and skeletoned forms, polyps attached to hard
substrates and more mobile, burrowing animals. Traditionally,
these broad distinctions have been used to recognize ordinal
and subordinal groupings. However, most currently recognized
Zoantharian orders include animals which fall into multiple
categories, or which defy easy classification. The utility of these
characters for recovering monophyletic groups will be assessed
with reference to a phylogenetic hypothesis based on 18srDNA,
anatomical and histological data. The importance of ecological
and morphological innovation in Zoantharian evolution will be
explored within the context of a phylogenetic hypothesis.
Supported by NSF DEB 980-1370.
212
Applications of a bioinformatics database for sea anemones.
MCCLOSKEY, B.M.*, M.D. FULLERTON, and D.G. FAUTIN. Univ.
of Kansas, Lawrence.
Bioinformatics databases facilitate addressing a variety of
questions by organizing large quantities of information. We
provide two examples of questions that can be addressed with
our database containing geographical and bibliographical
information on all known species of sea anemones. Using the
geographical component, we compare Arctic and Antarctic
anemone faunas and assess the number of species known from
greater than 66.5~ latitude. As for other marine invertebrates, the
number in south polar waters exceeds that in the north. We also
assess the number of polar species when Arctic and Antarctic
are defined by biologically relevant parameters, which may reveal
a natural break between polar and non-polar anemones. Using
the bibliographic component, we graph the cumulative number
of anemone species described through time. This allows us to
infer how completely anemone diversity is known. If the
cumulative number of species is growing more slowly than in the
past, we infer most species have been discovered. If, however,
the number is increasing steadily, many undescribed species
207
Cumaceans are small crustaceans frequently encountered in
benthic marine and littoral environments. Many species inhabit
the surface layer of sediment, partially burying themselves and
pursuing a deposit feeding lifestyle, while other species can be
found clinging to algal turf on rocks. Some species are known to
coat themselves in mucus, but no tube dwelling species have
been reported in the literature. Investigation of some large
collections of Australian cumacea have yielded species that
seem to be adapted for tube dwelling, with setal types similar to
well known tube dwellers in other related groups, such as
amphipods. Several preserved specimens have what appear to
be mucus tubes surrounding them, lending credence to the idea
that cumaceans can build tubes.
may remain. Supported by an REU supplement in bioinformatics
to DGF's NSF grant DEB 95-21819 (PEET-supported research).
216
213
Evolutionary antecedents: Muscles, brains, and skeletons:
Developmental genetics, paleontology and the metazoan
radiation.
JACOBS, D.K.', S. E. LEE, R. D. GATES, V. A. PALCHEVSKIY,
and C. DELLACORTE. Univ. of California, Los Angeles.
Apoptosis during longitudinal fission in a sea anemone.
MIRE, P.* and S. VENABLE. Univ. of Southwestern Louisiana,
Lafayette.
In sea anemones, longitudinal fission begins with stretching
of the body column and culminates in ripping apart of the
animal. We previously found that mechanical stretching of the
anemone plays a regulatory role in early fission events. Here we
use histology, TUNEL cytochemistry, and TEM to analyze the
potential spatio-temporal relationship between stretching of
tissues during fission and apoptosis within stretched tissues. We
find that enhanced apoptosis occurs in specific tissue regions
apparently most affected by stretching during fission. In
stretched animals, a significant induction of apoptosis occurs at
the junctions of the body wall and particular mesenteries that
begins in the axis parallel to stretch and then progresses to the
axis perpendicular to stretch as fission progresses. We propose
a model whereby stretching induces apoptosis in populations of
cells, allowing tissues to thin and thus facilitating successful
fission.
Wormsnails are currently recognized as a grade of uncoiled,
sessile, filter-feeding marine gastropods, comprising members of
the Vermetidae, Siliquariidae, and the genus, Vermicularia within
the family Turritellidae. In this study we examine the evolution of
the wormsnail form within the Caenogastropoda using both
morphological and nucleotide sequence data (18S rRNA).
Results from our combined dataset indicate that wormsnails
have evolved independently at least twice within the
Caenogastropoda. Further exploration of the evolutionary
radiation of wormsnails within the family Vermetidae, using
sequence data from nuclear (28S rRNA) and mitochondrial (12S
and 16S rRNA) DNA, has revealed that the systematics of
vermetid gastropods is currently in a state of disarray. Our
results challenge the current generic arrangement of species
within this family and suggest that at least three of the five
vermetid genera, Dendropoma, Tripsycha, and Petaloconchus,
are not monophyletic groups. Based on our molecular data, we
present a revised phylogeny of the Vermetidae and discuss
patterns of character evolution within this family.
215
Resolution of gastropod subclass taxa using new
characteristics: Utilization of novel morphological techniques
and genetic data.
UYENO, T.A.* and G.B.BOURNE Univ. of Calgary, Canada and
Duke Univ. Medical Center, Durham, NC.
The arrangement of higher taxa in the class Gastropoda has
historically been unstable. Characteristics traditionally relied
upon to decipher the systematics of this class were either shell
form or gross dissections and in rare cases histological sections.
In instances these approaches have led to the placement of
unrelated organisms into the same taxon. More recently, some of
these problems have been addressed using embryological data
and DNA analysis, but resultant taxonomic schemes have met
with varied acceptance. We used a multi-disciplinary approach
to help resolve some of these difficulties. Thus we used digital
magnetic resonance microscope techniques to create high
resolution, 3-D in vivo anatomical models with particular
emphasis of hydro-biomechanical structures. We compared
those data to data obtained by partially sequencing and
analysing the 18S ribosomal subunits of previously undescribed
species to aid in the creation of a phylogenetic tree.
ABSTRACTS
217
Rate of gametogenesis in the vent polychaete Paratvinella
palmiformis.
BACON, S. N.' and C. L. VAN DOVER. The College of William
and Mary, Williamsburg, VA.
Rates of gametogenesis vary greatly in polychaetes with
some shallow-water species producing oocytes in 48h.
Polychaetes at deep-sea hydrothermal vents may also have
rapid gametogenesis. We examined the rate of oogenesis in
Paralvinella palmiformis by sampling at intervals consistent with
the hypothesized rapid gametogenesis (h to d) rather than typical
'seasonal' (monthly) intervals. Female P. palmiformis from vents
on the Juan de Fuca Ridge (2200m) were maintained at 8"C and
sacrificed at intervals. A high frequency of mature females (75%)
had no detectable oocytes suggestive of a recent spawning
event. Oocyte size-frequency distributions did not vary
significantly among individuals a sign of reproductive synchrony.
There was no significant change over 120h in mean diameter for
all oocytes (20-210um) or for mature oocytes (80-210um). Mean
oocyte diameter thus increases at a rate slower than can be
detected over 120h. We cannot eliminate the possibility that
oogenesis was inhibited by stressful conditions associated with
decompression and maintenance on surface. Two peaks in the
oocyte size-frequency distributions (40-60um 145-185um)
indicate rapid vitellogenesis.
218
infrastructure of spermatogenesis and the formation of
spermatophore in the male reproductive system of Porcellia
scaber.
TAKETOMI.Y.", Y. NAKAHARA, and M. YANAGIDA. Kumamoto
Univ., Japan.
We have observed spermatogenesis and formation of
spermatophores in the male reproductive system of the isopod,
Porcellio scaber by means of light and electron microscopy. The
stages of spermatogenesis, primary/secondary spermatocytes,
spermatids and spermatozoa, differ from one testis to another.
The differences depend on the size of the testis. The testes
contain many follicle cells. A spermatozoon consists of an
acrosome, nucleus, and motionless tails. A bundle of 8-12
spermatozoa is present in a follicle cell, delimited by a
membrane. The follicle cells are characterized by a large
nucleus, endoplasmic reticulum, Golgi complexes, and many
kinds of inclusions. A bundle of spermatozoa turns into a
spermatophore in the seminal vesicles and vasa deferentia. The
epithelial cells of the seminal vesicles contain rough endoplasmic
reticulum, Golgi complexes, mitochondria and many inclusions
37A
214
Vermetid gastropods and the evolution of 'wormsnails'.
RAWLINGS, T.A.*, R. BIELER, and T.M. COLLINS. Florida
International Univ., Miami, and Field Museum of Natural History,
Chicago, IL.
Tracing the evolution of the homeodomains leads to several
hypotheses: 1) homeodomains are exclusive to a clade
containing all the major multicellular lineages - Animals, Fungi,
Slime Molds and Plants, 2) Homeodomains in sponges suggest
complex differentiation of tissues, 3) Cnidarians have a relatively
comprehensive set of homeodomains and the most basal
integrated sensory system of statocyst and eye linked to motor
response, aka the first brain. 4) Differences between bilaterian
phyla may often be mediated by loss of discrete aspects of gene
function. In response to these observations we documented that:
1) sponges contain, Mef2, a molecule required for muscle
differentiation. 2) Cnidarians contain, Brain 3, agene expressed in
nerves that control both eye and ear in bilaterian metazoa (3)
expression of the engrailed gene delimits skeletal elements
across a range of Bilateria (arthropods, molluscs, echinoderms)
suggesting that invertebrate skeletons are homologous, and that
the appearance of shelly fossils in the record may result from
evolution in a single lineage. 4) Onychophora do not express
engrailed in their ectoderm, and do not have ectodermal skeletal
elements. This may be a consequence of evolutionary loss of
exoskeletons, as Cambrian lobopods, such as Microdictyon have
segmental sclerites
and participate in the spermatophore formation. The electron
micrographs of the wall of the vasa deferentia show release of
secretory material, presumably used to form spermatophores.
219
Reproductive timing in a coelomic-brooding sea cucumber.
WILSON, M.M.*, E.A. SPRINGER, C.L. VAN CLEAVE, E.P.
WHEELER, J.A. WOOD, and R.L. TURNER. Florida Institute of
220
Glutathione depletion and reproductive success.
RINGWOOD, A.H. *, D.E. CONNERS, and N. COBB. Marine
Resources Research Institute, Charleston, SC, Univ. of Georgia,
Athens, and Univ. of Charleston, SC.
Glutathione(GSH)is a ubiquitous tripeptide that functions as a
very important modulator of cellular homeostasis, including
detoxification of metals and oxyradicals. Oysters {Crassostrea
virginica) were exposed to buthionine sulfoximine in the
laboratory to deplete gonadal GSH. Then fertilization and
developmental assays were conducted with gametes from
control and GSH depleted adults. No significant differences with
fertilization were observed. The effects on embryonic
development were more severe with gametes exposed to Cd
when they were derived from GSH depleted adults. Gonadal
GSH and reproductive assays were also conducted with oysters
deployed at metal-contaminated sites and reference sites.
Although gonadal GSH depletion was observed in oysters from
some of the reference sites as well as from the contaminated
sites, adverse effects on development were observed only with
oysters from the metal contaminated sites. Therefore, the model
established by the laboratory study (i.e. parental depletion of
GSH may increase the susceptibility of embryos to metal toxicity)
was substantiated by the field data.
221
Which way up? Phototaxis and polarity in a sponge.
LEYS, S.P.*, V.F. HINMAN, and B.M. DEGNAN. Univ. of
Queensland, Brisbane, Australia.
The parenchymella larva of Reniera a demosponge is
negatively phototactic a behaviour that presumably allows it to
select the underside of coral rubble for settlement the habitat of
the adult sponge at Heron Island Reef on the Great Barrier Reef.
Polarity of the larva is first apparent in the accumulation of
pigment cells that coalesce to form a dark ring at one end of late
stage embryos. The larva is ciliated except for a patch within the
pigment ring and swims in a corkscrew fashion with the pigment
ring at the rear. After settlement on its anterior swimming end the
pigment ring becomes submerged or is overgrown by the
neighboring epithelia and all indications of polarity of the animal
are lost. A search for expressed homeobox genes in the sponge
larva revealed Prox - common to sponges and no other
metazoan - and Bar-type genes but no Hox genes that are
typical of the so-called zootype in other metazoans. An RT-PCR
survey of larval RNA with degenerate Pax primers revealed that a
Pax 2/5/8 gene is expressed in the larva; no other Pax genes
were detected. The expression of Pax 2/5/8 and Bar-type genes
38A
222
Indirect development in the order Hoplonemertea (Phylum
Nemertea).
MASLAKOVA, S.A.', V.V. MALAKHOV, and J.L NORENBURG.
Moscow State Univ., Russia, and National Museum of Natural
History, Washington, D.C.
Nemertean worms have several basic types of development.
A planktonic larva, the pilidium, characterizes the order
Heteronemertea. The juvenile worm develops via unique
'imaginal discs' and sheds the larval body in a radical
metamorphosis. In one species, a 'hidden larva' (Desor's larva),
homologous to the pilidium, metamorphoses inside the egg
envelope. Species of the orders Paleo- and Hoplonemertea are
regarded as so-called direct developers. Which type of
development is ancestral is a key question in nemertean
evolution. We studied the hoplonemertean Tetrastemma
candidum Mueller, 1774. The embryo develops inside the egg
envelope; cells of a specialized larval ectoderm and apical plate
are distinguished from others by larger size, large bubble-like
nuclei and weakly stained cytoplasm. These cells are resorbed
during development and replaced by a secondary ectoderm,
whereas three other hoplonemertean species have been
reported to shed the larval ectoderm. Are these 'hidden larvae'?
If they can be shown to be homologous with Desor's larva, they
present a challenge to the current, implicit view that direct
development is primitive for Nemertea.
223
Transient formation of a right-sided vestibule is a normal
part of morphogenesis in three species of echinoplutei.
EAVES, A.A. Univ. of Victoria, Canada.
A left-sided invagination of the larval ectoderm to form the
vestibule is recognized as one of the earliest events of juvenile
rudiment formation in indirectly developing echinoids. Here I
report on the regular appearance of a transient ectodermal
invagination forming a vestibule on the right, contralateral to the
definitive vestibule on the left. The transient vestibule, which
extends toward the right anterior coelom, appears only after the
definitive vestibule has contacted the hydrocoel on the left side.
The transient vestibule normally recedes, but it can give rise to a
second rudiment. The definitive and transient vestibules were
examined in three species of echinoids {Strongylocentrotus
purpuratus, S. droebachiensis, and Dendraster excentricus) using
Nomarski DIC microscopy, histological sections, and localization
by immunofluorescence of the S2 (SALMFamide) neuropeptide.
Anti-S2 antibodies are immunoreactive to the vestibular
ectoderm for unknown reasons.
224
Rearing sea urchin larvae in artificial seawater.
WATTS, S.A.*, M.S. VICKERY, J.B. MCCLINTOCK, and J.M.
LAWRENCE. Univ. of Alabama at Birmingham and Univ. of South
Florida, Tampa.
Studies of echinoid larvae are usually confined to coastal
laboratories which have access to natural seawater. We have
recently cultured larvae of the echinoid Lytechinus variegatus
using 100% artificial seawater. Tap water was filtered through
sediment and carbon prefilters, a reverse osmosis unit, and
finally passed through a deionization canister, producing ultrapure water which was adjusted to 32 ppt with Instant Ocean sea
salts. Eggs and sperm were spawned by 0.5 M KCI injection and
fertilized in glass dishes at 26 C. Larvae were fed either
Chaetocerous gracilis, Dunaliella sp., Isocrysis spp. (Tahitian
strain), or a combination of all three. The greatest rate of growth
was observed in larvae fed mixed cultures, with lengths of ca.
1200 urn observed by 10 d. Larval competence (appearance of
the rudiment) was observed by 9-10 d, and metamorphosis to
juveniles was observed by as little as 17 d. Artificial seawater
could be used effectively in iarval studies (eg. toxicology) where
a defined medium is desirable, and may be extremely useful in
the aquaculture industry. Funded by Mississippi-Alabama Sea
Grant.
The viviparous sea cucumber Synaptula hydriformis is a
simultaneous hermaphrodite that retains multiple broods within
the perivisceral coelom. The modes of spawning and fertilization
in this species have long been in question. Recent studies
support the long-debated possibility that it self-fertilizes and add
new evidence that spawning is synchronized with the new moon;
but the occurrence of selfing and synchronous spawning
together seems incongruous to us. Our study tested the idea of
lunar synchrony by examining the composition of the brood over
time. Animals were collected weekly for 5 wk from Lake Surprise,
Key Largo, Florida; two of the six sampling dates shortly
followed new moons. The broods were removed by dissection
and categorized into five developmental stages. Chi-square
analysis showed that frequency distributions of stages in the
coelom differed over the 5 wk, but the frequency distributions
did not indicate a relationship with lunar cycle. Ongoing studies
will address synchronous spawning in subpopulations within
their clumped algal habitat.
suggests their possible conserved function in photoreception in
these animals.
225
Post-settlement success of larvae from Bugula pacifica:
Large vs. small.
HENDERSON, S.Y.* Univ. of Washington, Seattle.
Do differences in maternal nutrition acquired during brooding
affect post-settlement success? Bugula pacifica broods and
releases thousands of larvae during the spring and summer.
Adult zooids supply nutrients to developing embryos, greatly
increasing their size. In previous experiments I starved adult
colonies and over time these colonies released smaller larvae
than controls. Smaller larvae metamorphosed into ancestrulae
with smaller rhizoid attachments, and the spines that are
normally present were either reduced or absent. I examined the
effects of these changes in morphology on survivorship of newly
settled juveniles. I also looked at the time to first reproduction
and differences in larval size between juvenile and more mature
colonies..
226
Opposed ciliary bands and larval feeding in a capitellid
annelid.
PERNET, B.* and P. SCHROEDER. Friday Harbor Laboratories,
WA, and Washington State Univ., Pullman.
227
Sensory structures of deposit-feeding polychaetes:
Candidate chemoreceptors?
LINDSAY, S.M. Univ. of Maine, Orono.
Recent behavioral studies implicate chemoreception in
coordinating deposit-feeding by polychaetes. Yet,
chemoreception mechanisms remain poorly understood in many
deposit-feeding species. Part of an integrated investigation of
chemoreception and deposit-feeding in spionid polychaetes, this
study describes candidate chemoreceptors from Polydora
quadrilobata. In addition to frontal cilia of the food groove and
latero-frontal cirri adjacent to the food groove, scanning electron
microscopy revealed sensory tufts of cilia on feeding palps.
These structures were located lateral to the food groove and
were more sparsely distributed on the abfrontal surface of the
palps. There was no apparent pattern to the distal/proximal
distribution of the structures. Ciliated sensory structures, with
adjacent pores, were also distributed on all sides of the
prostomium and peristomium. To further define the nature of
these sensory structures (i.e., mechano- vs. chemoreceptor),
ultrastructural studies are in progress. Research on the
molecular biological basis of chemoreception in spionid
polychaetes is also ongoing.
229
Regulation of 5-HT uptake in crayfish hindgut neurons
through sensory stimulation.
MUSOLF, B.E.* and D.H. EDWARDS. Georgia State Univ.,
Atlanta.
The hindgut neurons (HGNs) of crayfish are distinctive in that
they acquire serotonin (5-HT) through uptake and therefore rely
on extrinsic sources of 5-HT. Sources of 5-HT for the HGNs exist
in the terminal ganglion (A6), hindgut, and hemolymph, however
it is not known what regulates extrinsic supplies of 5-HT for the
HGNs. We present evidence that sensory input can increase 5HT levels in the HGNs. Stimulation of nerves that transmit
sensory information from exteroceptive mechanosensors on the
tailfan leads to an increase in HGN 5-HT-ir. Unstimulated control
preparations show no increase in HGN 5-HT-ir. Application of
either 5-HT or paroxetine, a serotonin transporter (SERT)
antagonist, to the hindgut increases both gut peristaltic activity
and HGN 5-HT-ir over control preparations. This increased
labeling can be blocked by the application of paroxetine to the
nerve cord. Fills from the intestinal nerve to the hindgut reveal
putative proprioceptors that project to A6. This evidence
suggests that the increased peristalsis excites a centripetal
proprioceptive signal from the hindgut that leads to an increase
in central 5-HT uptake by the HGNs. Supported by the NSF.
230
Tpep antibodies label components of a veliger larval nervous
system.
KEMPF, S.C. Auburn Univ., Alabama.
The veliger larvae of marine molluscs exhibit behaviors very
different from those of adult and juvenile stages. Some
components of these behaviors are exhibited long before most
of the definitive ganglia of the juvenile/adult nervous system are
fully developed or, in some cases, even present. Recent
research on the serotonergic neural components of veliger larvae
has revealed a group of neurons and associated axonal circuitry
in and arising from a centrally located apical sensory organ
(ASO) that 1) appears to be 'separate' from the serotonergic
system that develops in association with the classical adult
ganglia and 2) is lost during the metamorphic process (Kempf et
al. 1997. J. Comp. Neural. 386, pp. 507-528). It has been
suggested that veliger larvae have a specifically larval nervous
system that deals with the needs of larval life history and that is
'separate' from the juvenile/adult system. In support of this
hypothesis, immunolabeling of veligers of Melibe leonina with
antibodies that bind to the adult molluscan peptide Tpep reveals
putative neurons and axonal circuitry that appear to have a
specifically larval function. Additionally, the axons labeled with
this peptide antibody appear to extend into the ASO neuropil.
231
228
A comparative study of the apical sensory organ in
planktotrophic Caenogastropod larvae: infrastructure and
serotonergic immunoreactivity.
PARRIES, S.C.* and LR. PAGE. Univ. of Victoria, Canada.
An apical sensory organ (ASO) is present in many marine
invertebrate larvae. Previous research indicates that the ASO in
gastropod larvae detects and integrates sensory stimuli and
relays motor signals to effectors in the velum. It has also been
ABSTRACTS
Links between dermal morphology, locomotor mode, and
lifestyle in holothurians.
SPAIN, D. Univ. of North Carolina at Chapel Hill.
Peristaltic locomotion is used by many soft bodied,
vermiform invertebrates. Although previous research has been
conducted on either the locomotion or the morphology of a few
holothurian (sea cucumbers) species, there are no studies that
examine the links between dermal morphology and mode of
locomotion. In particular, there are no data on potential
39A
The feeding mechanisms of annelid larvae are diverse, but
have been well described in only a few taxa. As part of
comparative studies on the functional morphology and evolution
of annelid larvae, we describe the form and feeding of early
stages of Notomastus sp. (Family Capitellidae) from San Juan
Island, Washington. These larvae capture particles between two
equatorial ciliary bands, a pre-oral prototroch (effective stroke
anterior to posterior) and a post-oral metatroch (effective stroke
posterior to anterior). Captured particles are carried around the
body to the mouth by an intermediate band of short cilia. Larvae
of Notomastus sp. have relatively high clearance rates on
particles of a wide range of sizes, including some whose
diameters are greater than the length of the prototrochal cilia or
width of the food groove. They may capture these large particles
by another mechanism. This is the first report of a capitellid larva
with opposed ciliary bands, and the first description of larval
feeding mechanism in a member of this family.
suggested that specific characteristics of the ASO relate either to
ancestry or to velum size and life history; this debate is
unresolved. We used SEM, TEM and localized serotonin
immunoreactive (5HTir) neurons to characterize the ASO in
larvae of four planktotrophic caenogastropod species.
Ultrastructure of the ASO is similar amongst these species and
the overall layout corresponds to the tripartite arrangement
described for opisthobranch larvae. The 5HTir neurons of the
ASO show interspecific variation in these caenogastropods with
the number of somata ranging from 3 to 6; quite unlike the
characteristic 5 neurons found in opisthobranchs. A lateral pair
of 5HTir, non-sensory neurons is common to all species. These
and other comparative data suggest that common ancestry is a
major determinant of overall ASO design within the Gatropoda.
differences between epifaunal and infaunal species. Time-lapse
video was used to study the locomotion of epifaunal (Oncus
pygmaeus) and infaunal (Thyonella gemmata) holothurian species
within the same order. The amounts of connective tissue,
musculature and ossification in the body wall were quantified
from histological sections. The data from the videotape analysis
suggests that both species use the same type of peristaltic
locomotion. However, data from the histological analysis
suggests that specializations in the dermal morphology exist for
epifaunal and infaunal lifestyles. Current research is being
conducted on additional epifaunal and infaunal species in the
same order.
232
The effect of flow on feeding success in encrusting versus
erect bryozoans.
PRATT, M.C. Duke Univ., Durham, NC.
233
Growing ploughshares into swords: The morphological and
functional transition of feeding to display claws in maturing
male fiddler crabs.
MERZ, R.A.*, S.B. ALTSCULER, and K.C. HAUSER. Swarthmore
College, PA.
Fiddler crabs are known for their sexual dimorphism and the
limits it imposes to feeding in males. We examined the change in
morphology and function in Uca pugnax from the newly settled
stage where males feed with both claws to the point where it is
no longer possible for them to use their display claw to feed. We
recorded the fraction of time males spontaneously used feeding
or display claws to feed. Up to a carapace width of 6 mm, males
use both claws with equal frequency. From 6 mm to 10 mm
there is a diminution of the use of the display claw for feeding;
above 10 mm it does not happen spontaneously. Is this a
morphological limit or a behavioral choice? We excised the
feeding claws of male crabs with carapace sizes between 7 - 1 5
mm and found that up to about 12 mm, crabs could still feed
with the display claw. These experiments show that during a
time when rapid growth might be particularly favored, young
male crabs are not yet handicapped in their feeding by the
presence of a developing display claw. As the display claw
matures, it increases in size, changes shape and loses small
hairs that make it less successful at scooping up sediment.
234
Ontogenetic changes in thrust production during escape jet
behavior in tethered Pacific Oval Squid, Sepioteuthis
lessoniana.
THOMPSON, J.T. Univ. of North Carolina at Chapel Hill.
A crude model based on previous morphometric and
kinematics studies predicts an ontogenetic decline in sizenormalized thrust production during escape jet behavior in the
Pacific Oval squid (Sepioteuthis lessoniana). The prediction of
this model is counterintuitive because the mantle musculature of
young squid contains a much lower proportion of powerful
anaerobic fibers than the adult mantle. However, the model's
prediction is based, not on muscle physiology, but on geometric
40A
235
Molluscan hemocytes exhibit S-100 protein
immunoreactivity.
RIDGWAY, R.L.*, M. WALLACE, and J. COOK. Seattle Pacific
Univ., WA.
Hemocytes serve as the main immune system in molluscs.
They proliferate within connective tissues and are released into
the blood, circulating as spherical cells until activated to adopt a
phagocytic function and morphology. In Lymnaea stagnalis,
hemocyte activation is correlated with a rapid shift in cytoskeletal
organization resulting in directed amoeboid movement. We are
examining signal transduction mechanisms relevant to hemocyte
activation, starting with the regulation of intracellular calcium. S100 proteins are a family of small calcium-binding modulator
proteins with cell-type-specific expression. Previous reports of
S-100 immunoreactivity in molluscs limited expression to neural
tissues. We now report that a polyclonal antiserum generated
against a mammalian S-100 protein recognizes a cytoplasmic
molecule within both non-activated and activated Lymnaea
hemocytes. In activated hemocytes the immunoreactivity is
localized initially to the perinuclear cytoplasm. As the cell begins
to spread, however, the immunoreactivity moves outward with
roughly the same time course as microtubule polymerization,
suggesting a possible role in mediating the cytoskeletal
dynamics of molluscan hemocytes.
236
Quantification of Taura Syndrome Virus in shrimp by
competitive reverse transcription-PCR.
BARAGONA, M.A.* and S.Y. WANG. Univ. of Southern
Mississippi, Hattiesburg.
Taura Syndrome Virus (TSV) is a ssRNA virus in the family
Picornaviridae that infects penaeid shrimp. The virus was first
observed near the Taura River in Ecuador in 1992 and is of
interest because it causes high mortality rates at shrimp
aquaculture facilities. The goal of the present project is to
develop a competitive reverse transcription (RT)-PCR procedure
to determine the relative abundance of TSV among infected
shrimp. A competitive template identical in sequence to a 420 bp
fragment of the TSV genome except for the addition of a 30 bp
insert was synthesized by PCR and cloned. The 30 bp insert
allowed us to distinguish the two PCR products on the basis of
size. Because the competitive template and the 420 bp TSV
sequence contain the same primer annealing sites, it is assumed
that the two templates are amplified with equal efficiency.
Knowing the amount of competitive template added to the
amplification reaction, TSV was quantified by comparing the
yield of the 420 bp TSV sequence relative to that of the
competitive template. The assumption that the two templates are
amplified colineariy was tested to determine the efficacy of the
quantification procedure.
237
Isolation and characterization of differentially expressed
genes in Taura Syndrome Virus-infected shrimp.
LU, Y.* and S.Y. WANG. Univ. of Southern Mississippi,
Hattiesburg.
Taura Syndrome Virus (TSV) is a picornavirus that infects
penaeid shrimp. The PCR-based differential display (DD)
technique was used to isolate differentially expressed genes
between control shrimp {Penaeus vannamei) and those
experimentally infected with TSV. The technique enabled us to
achieve two objectives: 1) to develop a reverse transcription
(RT)-PCR based technique for the molecular detection of TSV in
shrimp; and 2) to isolate shrimp genes whose expression are
enhanced during viral infection. Portions of five differentially
SOCIETY FOR INTE&RATIVE AND COMPARATIVE BIOLOGY
Bryozoans are active filter feeding animals that can exhibit a
variety of different colonial morphologies. Certain colonial forms
may have a selective advantage over others in particular
hydrodynamic habitats. Membranipora membranacea has an
encrusting sheetlike morphology and is found almost exclusively
on large flat macroalgae (such as kelps). Bugula pacifica has a
bushy erect morphology and is generally found covering hard
substrata (such as docks or rocks). These two species do
occasionally overlap in habitat: both can be found on large
macroalgae in protected areas. I investigated the ability of these
two species to capture particles in relatively slow and fast
unidirectional flow to determine if either species is better at
capturing food in different flow habitats. Data to date suggest
that M. membranacea colonies capture more food than B.
pacifica colonies at both slow and fast flow velocities. Further
work is needed to elucidate more definitively whether or not
hydrodynamics play a central role in determining which habitats
different bryozoan colony forms can survive in.
and kinematics differences that occur during ontogeny. To test
this model, an apparatus analogous to a force plate was built to
allow simultaneous recording of mantle kinematics and force
production in tethered squid. An ontogenetic series of squid,
ranging in size from 5mm dorsal mantle length (DML) to 65mm
DML was tested. The consequences of ontogenetic changes in
thrust production will be discussed in terms of life history
strategy and the evolution of escape behavior.
expressed genes were isolated. Two were shown by PCR to be
TSV specific and a RT-PCR procedure was developed to amplify
a 420 and a 435 segment of the TSV genome. One microliter of
shrimp hemolymph, used directly in RT-PCR, was found to be
sufficient for the detection of TSV. Three of the differentially
expressed genes were shown by PCR to be shrimp genes
whose expression appear to be enhanced during viral infection.
Efforts are currently underway to isolate full length cDNAs and to
determine whether these genes are truly differentially expressed.
If true, their potential use as molecular markers of disease
resistance will be examined.
238
Diagnostic tests and population dynamics concerning
interactions among lyme disease vectors and agents in
northern Pennsylvania.
WANNER, A.J.* and R.C. MARIS. Mansfield Univ. of
Pennsylvania.
239
Immunolocalization of recombitant cathepsin L1 in
Schistosoma mansoni.
BOGITSH, B.J.*, J.P. DALTON, and P.J. BRINDLEY. Vanderbilt
Univ., Nashville, TN, Dublin City Univ., Rep. of Ireland, and
Tulane Univ., New Orleans, LA.
Cysteine proteases (e.g., cathepsins B & L) expressed by
schistosomes play key roles in the digestion of host hemoglobin.
It has been reported that, based on substrate specificity,
cathespin L is the predominant member of these two proteases
in Schistosoma mansoni. For localization by
immunocytochemical procedures, a PCR-based cDNA encoding
a discrete 33 KDa cathepsin L-like cysteine protease (SmCL1) in
S. mansoni was used to generate a monospecific rabbit
antiserum. Adult worms were freeze-dried, formalin-vapor fixed
and embedded in paraffin in vacuo. Sections were incubated in
the primary antibody and visualized with a secondary antibody
conjugated with FITC. For electron microscopy, L.R. Whiteembedded tissue was visualized with a secondary antibody
conjugated with 15 nm gold. Under light microscopy, fluorescent
reaction product was visible in the gastrodermis of both sexes.
Electron microscopy revealed gold particles in the superficial
digestive vacuoles of the gastrodermis of both sexes. Together
with previous biochemical findings, these results support a role
for SmCL1 in the digestive processes of S. mansoni.
Division of Neurobiology
240
NO producing cells in the CNS and peripheral tissues of
bivalvia: A histochemical study.
UNTCH B.*, M. J. GREENBERG, and L L . MOROZ. Univ. of
Florida, St. Augustine.
NADPH-diaphorase histochemistry has been used to analyze
the distribution of putative NOS-containing cells in the bivalve
mollusc, Mercenaria mercenaria. Serial sections and whole
mount preparations were made from the pedal, visceral, cerebral
ganglia, gills, mantle, palps, siphon, stomach/intestine, foot, and
gonads. The majority of the selective labeling occurred in
ABSTRACTS
241
The distribution of NOS-containing cells in the primitive
chordate Branchiostoma floridae and the hemichordate
Balanoglossus.
DZHASHIASHVILI, Y.Y*. and L.L. MOROZ. Univ. of Florida, St.
Augustine.
The distribution of putative NOS-containing cells in
Branchiostoma floridae and Balanoglossus sp. was studied using
NADPH-diaphorase histochemistry. In B. floridae selective
staining in the CNS was very restricted: it was found only in 1-2
pairs of neurons around the cerebral vesicle and in up to 70-75
neurons in the posterior two-thirds of the neuronal tube. No
NADPH-d positive neurons were identified in the periphery.
Distinct staining was observed in the myosepta, specifically in
distal parts of individual myofibers close to the lateral surface of
the body wall. A similar pattern was observed in the muscle
system of Balanoglossus, but there was no staining detected in
the nervous system. The distribution of NADPH-d positive cells
in the muscular system suggests that NO may be directly
involved in the modulation of locomotion. In Balanoglossus,
positive staining was also found in the epidermis throughout the
animal's body and in the collarette. In contrast to vertebrates, no
NADPH-d reactivity was found in the circulatory system of either
species.
242
Assessment of the effects of neurohormones on cardiac
performance in the grass shrimp (Palaemonetes pugio).
NEWELL, C.R.' and C. REIBER. Univ. of Nevada, U s Vegas.
Limited work has focused on cardiac performances in the
grass shrimp {Palaemonetes pugio). The neurogenic heart of the
decapod is regulated by the cardiac ganglion, cardioexcitatory
and cardioinhibitory axons, as well as the pericardial organ.
Neurohormones released into the pericardial sinus include: 1) the
excitatory hormones serotonin, proctolin, and octopamine, and
2) the inhibitory hormone Gamma-aminobutyric acid (GABA).
Utilizing microinjection techniques and video microscopy
cardiovascular parameters were monitered. Observations were
made in response to injection of serotonin and GABA at various
concentrations (10"5, 10"7, 10 -9 , and 10"11 M). Strong excitatory
responses, including an increased heart rate, decreased stroke
volume, and increased cardiac output were observed in
response to injection of serotonin. Inhibitory effects were seen in
response to injection of GABA. Cardiac regulation is discussed in
light of the results.
243
Serotonin (5-HT) increases the rate of evoked
neurotransmission at the crayfish NMJ.
WHITEHEART, S.W.*, R.C. SOUTHARD, J. HAGGARD, and R.L
COOPER. Univ. of Kentucky, Lexington.
Synaptic vesicles and the mechanisms by which they fuse to
the presynaptic membrane are important to signal transduction
at the neuromuscular junction (NMJ). Although exact
mechanisms at the crayfish NMJ are not fully understood, the
vesicular release of neurotransmitter is quantal. Using the
crayfish tonic NMJ, quantal events can be recorded directly at
the release sites allowing assessments to be made regarding the
parameters of vesicle action. These parameters include latency
and frequency in the first evoked response and subsequent
multiple responses. The kinetics of this action and the
41A
The Lyme Disease spirochete {Borrelia burgdorferi) has been
well-studied. However, little is known about population dynamics
and interactions between an intermediate host (the white-footed
mouse, Peromyscus leucopus) and the deer tick vector {Ixodes
scapularis). One objective was to exploit a conventional test for
Lyme Disease antibodies using dog blood serum which was
modified for similar use with mice. Immunofluorescence methods
were employed for antibody detection. A second objective
concerned an investigation into the magnitude of tick
populations. Ticks were collected using carbon dioxide traps.
Potential outcomes are a predictive model for the tick
populations in northern Pennsylvania and a reliable diagnostic
tool for determining the presence of the Lyme Disease
spirochete.
subepithelial non-neuronal cells located in gills, and in ciliated
epithelium of the gut. The gonad areas, body wall muscles, pedal
muscle and secretory cells were almost completely negative for
NADPH-d. The most prominent neuronal staining was located in
the pedal ganglion, followed by the visceral and cerebral ganglia.
Although only a few isolated neurons were found stained in the
cerebral ganglion, distinct NADPH-d labeling was found in the
neuropil and in peripheral nerves. Several groups of subepithelial
sensory-like neurons were found in the palps, esophagus and
stomach/intestine. We suggest that NO is used as a signal
molecule within the CNS and peripheral tissue of bivalves, but
the distribution patterns of NOS-containing non-neuronal cells
are different from those in the gastropods.
progressions in which the neuromodulators affect the
parameters of the vesicular action can be obtained. The
application of biogenic amines to various synapses has been
known to produce varying results. We assessed the
neuromodulatory effects of 5-HT through the analysis of the
latency jitter at the NMJ. The presence of 5-HT at the terminal
results in a smaller latent period or a faster rate of release as
indexed by evoked currents and is enhanced by HHMI
undergraduate fellowship (RCS); NSF grants IBN-9808631 (RLC);
NIH-HL56652 (SWW).
244
The differential effects of 5-HT on tonic and phasic motor
nerve terminals.
SHEARER.J.F.* and R.L. COOPER. Univ. of Kentucky, Lexington.
245
The effects of 5-HT on sensory neurons, CNS command, and
neuromuscular junctions of the crayfish abdominal
superficial flexor.
NECKAMEYER, W.S.*, J.R. STRAWN, and R. L COOPER. Univ.
of Kentucky, Lexington.
Serotonin (5-HT) induces a variety of physiological &
behavioral effects in crustaceans, and is found in the hemolymph
and ventral nerve cord (HPLC data to be presented). Previous
studies show that 5-HT increases heart rate and neurotransmitter
release at neuromuscular junctions, and changes firing
frequencies of motor neurons associated with the somatogastric
system and other motor command systems. Our studies address
the role of 5-HT in altering: (1) the activity of superficial flexor
motor neurons; (2) release properties of the nerve terminal; (3)
input resistance of the muscle; and (4) sensory neuron activity.
Using en passant recordings from the motor nerve, with and
without extrinsic sensory stimulation, and intracellular recordings
from the muscle, we have shown that the application of 100 nM
5-HT enhances sensory input to the CNS, increases firing
frequency of the motor neurons associated with the superficial
flexor, increases neurotransmitter release at the NMJ, and alters
the input resistance of sup. flexor fibers. NSF-IBN-9808631
(RLC), NSF-IBN 9423616 (WSN), & HHMI (JRS).
246
Load does not influence muscle phenotype in crayfish.
MOFFETT, S.*, B. GRIFFIS, and R. L. COOPER. Univ. of
Kentucky, Lexington.
Loss of chelipeds in crustaceans results in severe atrophy of
the major muscle responsible for lifting the limb, the anterior
levator (Moffett, JEZ 1987). We decided to test if this loss of
mechanical load altered muscle phenotype as measured by
SDS-PAGE analysis of levator total protein and actomyosin
fractions. Levator muscles of adult crayfish, Procambarus clarkii,
with either functional regenerate limbs or lack of limb buds
(papilla stage) were compared with those from normal
contralateral limbs and those from pristine animals. We find that
there is no difference in protein profiles among the three
42A
247
Mechanisms of synaptic depression in high output phasic
motor neurons.
KELLIE, S. P.* and R.L. COOPER. Univ. of Kentucky, Lexington.
Heterosynaptic and homosynaptic depression have been
studied in the cerebellar slice. In both of these cases, the
actually mechanisms are not well understood. Some evidence
points to a presynaptic component; other evidence points to a
postsynaptic site. By studying synaptic depression at the
neuromuscular junction of the crayfish leg extensor muscle,
additional information on the mechanisms of synaptic depression
is revealed. Through the use of intracellular and extracelluar
recordings, release parameters, such as the quantal size, the
number of release sites, and the probability of release, are being
quantified during depression. These parameters have also been
examined under the influence of serotonin, a neuromodulator.
The rate of depression and recovery of depression also is being
investigated with and without the presence of this
neuromodulator. The results obtained aid in understanding the
workings of chemical synaptic transmission within a
physiological range of activities and conditions.
248
The anatomical, physiological and biochemical
characterization of muscles associated with the articulating
membrane in the dorsal surface of the crayfish abdomen.
MYKLES, D.L*, J. SOHN, and R.L. COOPER. Univ. of Kentucky,
Lexington.
The anatomy, physiology, and biochemistry of the dorsal
membrane muscle and the superficial extensor muscle
accessory in the abdomen of the crayfish, is reported. These
muscles have not been previously characterized physiologically
or biochemically. The arrangement of these muscles vary
depending on the abdominal segment. The function of the dorsal
membrane muscle is to retract the thin articulating membrane
joining the cuticular segments so that the dorsal membrane does
not evert during extension of the abdomen. Consequently, the
articulating membrane does not protrude, and thus potential
damage to the membrane is minimized. Nerve terminal
morphology indicates a tonic like structure. The
electrophysiological data indicate that there are at least four
tonic-like motor neurons innervating these muscles: fatigueresistant and facilitating. The electrophoretic analysis of
myofibrillar proteins indicates that they are tonic-like fibers.
Supported by NSF grants IBN-9808631 & ILI DUE-9850907
(RLC) and a UC Davis Distinguished Research Fellowship (DLM).
249
Development of drosophila larva neuromuscular junction:
Maintaing synaptic strength.
LI, H.*, D.A. HARRISON, and R.L. COOPER. Univ. of Kentucky,
Lexington.
The regulation of synaptic efficacy is essential for the
development of functional neural circuits and adult plasticity. As
a model system, Drosophila melanogaster, provides many
experimental advantages for analysis of the mechanisms that
regulate synaptic efficacy during development. The amplitudes
of the evoked excitatory junction potentials (EJPs)of Ib and Is
neurons, recorded in muscle 6 within abdominal segment 3 (A3),
decrease sightly from the 1st to the 3rd larval instar. However,
the input resistance of the muscle decreases dramatically as the
muscle increases in its size. The EJPs were also recorded from
muscles 6 and 7 from A2 to A6, and the relationship between the
EJP amplitude and the muscle size will be reported on.
Determination of the relationship of the length and bouton
The distribution of biogenic amines are not directed at
discrete postsynaptic targets, but rather they are diffuse over a
wide area, interacting with receptors on several target cells. In
the crayfish leg extensor muscle, phasic and tonic motor
neurons innervate the same muscle fibers. With this preparation,
intrinsic differences between high- and low-output terminals can
be examined in the absence and presence of neuromodulators.
The hypothesis is that acute application of serotonin (5-HT)
affects different types of neurons differently. We are examining if
such differences in response to modulators will likely depend on
the neurons' intrinsic differences in synaptic efficacy and on
induced long-term physiological and structural changes.
Second-messenger signaling is also being examined to aid in the
study of mechanisms responsible for differential effects of
modulators on terminals of phasic and tonic motor neurons
innervating the same target cell. Anatomical and physiological
correlation are in the process of being investigated to provide a
better understanding of the mechanisms behind the kinetics of
modulating synaptic transmission. NSF IBN-9808631 (RLC) and
Univ. of KY-INP & Ribble scholarships (JS).
conditions. However, the total protein profile for the levator
muscle is unique compared to those of purely phasic or purely
tonic muscle of the abdomen (L and SEL, respectively). The
levator myosin heavy chain profile is similar to that of mixed
phenotype muscles such as the claw closer and walking leg
extensor. We conclude that load does not influence levator
phenotype. This is likely due to the intact innervation and
continued activation of the levator during atrophy. Funded by
NIH-NIMH BEACON (B.G.), NSF IBN-9808631 (R.L.C.).
number of the motor neuron terminals (Ib and Is) and the surface
area and volume of their targets at each larval instar is currently
be analyzed. In addition, the synaptic strength and ultrastructure
of primary varicosities of both Type Ib and Is terminals is also be
examined throughout the larval development. Supported by NSF
grants IBN-9808631 & ILI DUE-9850907 (RLC) and IBN-9723994
(DH).
250
Involvement of PLAj in growth cone formation after neurite
transection..
GEDDIS, M.S.* and V. REHDER. Georgia State Univ., Atlanta.
251
The control of orientation behavior by large peptidergic
neurons in Tritonia diomedea.
CAIN, S.D.*, J.H. WANG, and K.J. LOHMANN. Univ. of North
Carolina at Chapel Hill.
Previous work has identified two pairs of bilaterally
symmetric peptidergic neurons (Pd5 and Pd6) within the pedal
ganglia of the sea slug Tritonia diomedea that respond to
changes in earth-strength magnetic fields. The observed
responses are characterized by an increase in spike firing rate
apparent many minutes (6-10) after the beginning of the
stimulus. Therefore, the role of these cells in magnetoreception
and magnetic orientation behavior is not obvious. To better
understand the function of these cells in the neural circuitry
underlying magnetic orientation behavior, the cellular properties
of the neurons were characterized using electrophysiological,
anatomical and ultrastructural techniques. Both the anatomical
and electrophysiological data suggest that these neurons
innervated the cilia of the foot epithelium, which is used for
locomotion. It appears that both Pd5 and Pd6 are involved in the
motor output controlling orientation behavior. Furthermore, the
data suggest that these cells might function in a modulatory or a
general arousal role in directed locomotory activity.
252
The identification and characterization of magnetically
sensitive neurons in the marine mollusc Tritonia diomedea.
WANG, J.H.*, S.D. CAIN,and K.J. LOHMANN. Univ. of North
Carolina at Chapel Hill.
Many animals can detect the Earth's magnetic field and use
it as a cue for orientation. However, little is known about the
neural mechanisms and circuitry that underlie this ability.
Previous work on Tritonia diomedea, a marine mollusc capable
of magnetic orientation, identified a pair of bilaterally symmetric
neurons (LPd5 and RPd5) in the CNS that increased their
electrical activity in response to changes in Earth-strength
magnetic fields. We have isolated another pair of bilaterally
symmetric neurons (LPd6 and RPd6) that also increase their
electrical activity in response to changes of the magnetic field.
These four neurons (Pd 5 and 6) respond similarly to changes in
the magnetic field. In addition, they receive common synaptic
inputs, have axons located in nerves that innervate the foot, and
contain peptides that have been shown to stimulate ciliary
ABSTRACTS
253
Boundary layer effect on chemical signal movement near the
antennae of the sphinx moth.
SCHNEIDER, R.W.S.* and P.A. MOORE. Bowling Green State
Univ., OH.
For olfaction to occur, signal molecules must move through
the environment from the source to the receptor cells. Within
boundary layers, the interaction between the forces causing
chemical dispersion changes. To investigate how the boundary
layer changes the dynamics of the chemical signals, we
measured chemical dynamics within the boundary layer around
the moth antennae using microelectrodes at biologically relevant
angles of attack. Spectral analysis shows the way signals are
filtered depends on the angle of attack. In addition, very low
frequency signals are amplified as the angle of the antennae
decreases. At lower angles and faster odor frequencies, the
pulsatile signal is unresolvable as separate peaks and appears
as a smooth peak. Peaks can not be resolved at lower angles
and higher frequencies. Conversely, at higher angles and slower
frequencies the peaks have a very high rise time and short decay
time. Analysis of the frequency resolution shows a very
consistent pattern across angles and signal frequencies. This
suggests that moths may have the ability to control temporal
filtering of the boundary layer around the antennae.
254
Sea anemones count cycles of vibration to sensitize
nematocyst discharge into vibrating targets.
WATSON, G.M. Univ. of Southwestern Lousiana, Lafayette.
Discharge of nematocysts is regulated in part by hair bundle
mechanoreceptors located on tentacles. Data from a simple
bioassay indicate a doubling of nematocysts discharged at key
frequencies as compared to other frequencies. We here report
that subsecond bursts of vibrations sensitize discharge or not
according to the stimulus duration. As the number of completed
cycles is increased, discharge is sensitized in rhythmic pattterns
that vary according to the key frequency.
Division of Systematic & Evolutionary
Biology
255
Reassessment of the anthozoan order Ptychodactiaria.
CAPPOLA, V.A.* and D.G. FAUTIN. Univ. of Kansas, Lawrence.
The current classification scheme of cnidarian class
Anthozoa recognizes Ptychodactiaria as an order equivalent to
the Actiniaria and Scleractinia. We will assess whether
Ptychodactiaria merits ordinal status. It contains three
monospecific genera (Dactylanthus, Preactis, and Ptychodactis)
in two families (Preactiidae and Ptychodactiidae). Order
Ptychodactiaria was originally characterized by the lack of basiiar
muscles, the absence of ciliated tracts on the filaments, and the
placement of the gonads in a layer on either side of the
mesenterial mesoglea. It was redefined to accommodate the
presence of basiiar muscles and ciliated tracts in the genus
Preactis. Preactis has characteristics that are intermediate
between those of the other ptychodactiarians and the
actiniarians. Except for the presence of basiiar muscles and
ciliated tracts, Preactis is more similar to Dactylanthus than
either genus is to Ptychodactis. The condition of basiiar muscles
in all three species and the phylogenetic importance of this
character will be reassessed to determine whether these three
genera form a clade. This research was supported by NSF grant
DEB95-21819(PEET) to D.G. Fautin.
43A
Membrane sealing and growth cone formation are necessary
preliminary steps in successful neuronal regeneration. In order to
further understand the mechanisms underlying these processes
we have investigated the formation of growth cones in an in vitro
injury model. Neurites from identified snail neurons {Helisoma
trivolvis) were transected with a glass microknife and the
formation of new growth cones from the distal portions of the
transected neurites was recorded at defined times after
transection. Growth cone formation under control conditions
occurred within 15 minutes, in contrast growth cone formation
was completely inhibited in the presence of the phospholipase
A2 (PLA^ inhibitor 4-bromophenacyl bromide (BPB).
Furthermore, BPB caused the deterioration of both the proximal
and distal portions of the severed neurite, but not of
untransected neurites, suggesting that P U ^ is an important
component in membrane sealing. Since P U ^ catalyzes the
hydrolysis of phospholipids to arachidonic acid and
lysophospholipids, we are presently investigating if the
mechanism of inhibition is second messenger or lipid derived.
beating on the foot epithelium. Because T.diomedea locomote
by ciliary beating, we hypothesize that these four neurons (Pd5
and 6) play a role in the motor output of 7. diomedea's magnetic
orientation behavior.
259
Conspectficity of the clonal and solitary forms of two
clownfish sea anemones (Cnidaria: Actiniaria) using ITS1
sequence data.
WHITE, T.R. Univ. of Kansas, Lawrence.
Fluorescent microscopy: A new tool in taxonomic and
evolutionary studies of Gastrotricha.
HOCHBERG, R.* and M.K. LITVAITIS, Univ. of New Hampshire,
Durham.
Of the 10 species of clownfish sea anemones, only
Entacmaea quadricolor and Heteractis magnifies are capable of
asexual reproduction; therefore, the two species occur in clonal
clusters as well as solitary individuals. The clonal and solitary
forms of each species are morphologically identical but may
differ in size (solitary individuals being larger), in ecology, and in
the type of clownfish they host. It was thought that Methdium
senile in the Pacific and Anthopleura elegantissima occurred as
both clonal and solitary morphs despite ecological and some
morphological differences between the two. However, molecular
data (allozymes) supported the clonal and solitary forms being
separate species. I will use another form of molecular data, DNA
sequence from the internal transcribed spacer (ITS1) located in
the nuclear ribosomal genome, to test whether the clonal and
solitary forms of E. quadricolor and H. magnifica are conspecific.
Supported by NSF grant DEB 9521819 (PEET) to D.G. Fautin,
and the KU Natural History Museum and Biodiversity Research
Center Panorama Small Grant Society.
Fluorescent procedures provide an effective means of
studying neuronal and muscular organization in marine and
freshwater gastrotrichs. Several species of Gastrotricha from the
orders Macrodasyida and Chaetonotida were examined.
Chemically-induced fluorescent procedures (GAIF, FaGlu)
revealed similar patterns of catecholaminergic neurons in a wide
variety of species. Further demonstration of neuronal
organization was performed with the fluorescent carbocyanine
dye, DiO, which effectively displayed the morphology and
position of cephalic sensory receptors. In addition, the F-actin
stain, Alexa 488-phalloidin was useful in demonstrating patterns
of circular and longitudinal musculature and successfully
revealed the shape of the buccal cavity, development of the
myoepithelial pharynx, position of the pharyngeal pores and the
location of muscular reproductive organs. These fluorescent
procedures all have utility in studies of gastrotrich taxonomy
because they reveal species-specific patterns. Used in
conjunction with EM studies, fluorescent methods will provide
sound morphological characters for revealing intraphyletic
relationships and for reconstructing the ground pattern of the
Gastrotricha.
257
Repeated evolution of clonality in sea anemones in the
genus Anthopleura inferred from a molecular phylogeny
based on mitochondrial 16S rRNA and cytochrome oxidase
subunit III.
GELLER, J.B.* and E.D. WALTON. Moss Landing Marine
Laboratories, CA, and Univ. of North Carolina at Wilmington.
Life history traits may reflect adaptation to particular
environments, or may be inherited from ancestors. These
opposing hypotheses predict different distributions of traits on
phylogenetic trees. In this study, we asked whether clonal and
solitary life histories among sea anemones in the genus
Anthopleura have many origins (supporting adaptation) or few
origins (supporting phylogenetic constraint). We sequenced 1459
base pairs of DNA from three loci (mitochondrial 16S rRNA,
mitochondrial cytochrome oxidase subunit III, and nuclear 28S
rRNA) from 12 species of Anthopleura and four outgroup
species. Most parsimonious trees indicate a minimum of five
independent origins of clonality, or five origins of solitariness
(depending on assignment of the ancestral character state).
Alternative trees in which the monophyly of life history traits was
enforced were significantly longer than most parsimonious trees.
These data suggest that the ability to reproduce asexually is an
evolutionary labile trait in Anthopleura and support adaptive
interpretations. These data suggest that one western Pacific
species {A- midori) is closely related to eastern Pacific species.
258
Evolution of musculature in lower platyhelminths.
HOOGE, M.D.' and S. TYLER. Univ. of Maine, Orono.
The systematics of the Acoela has remained problematic
despite a long history of study. The paucity of characters
discernible in them as well as the seeming plasticity of those few
characters has left little on which to base phylogenetic
reconstruction. In a search for new morphological characters
that could be phylogenetically informative, we are using
fluorescence microscopy to survey the musculature in the ventral
body wall, which shows surprisingly distinctive patterns in
several groups of acoels. Among representatives of the majority
of the acoel families, we can discern what appear to be six
distinct clades. The consistency of these patterns among the
many species we have examined and their lack of con-elation
with habitat, feeding mode, or body shape suggest that they did
not arise through convergent evolution and, therefore, provide
phylogenetically useful characters. Because these characters do
not in all cases correlate with characters currently used to
distinguish families, we suggest that revisions to the system of
the Acoela will be necessary.
44A
260
Problems inferring coelomate protostome phylogeny from
elongation factor 1 alpha sequence data.
SCHWARTZ, M.L.' and J.L. NORENBURG. George Washington
Univ., Washington, DC and National Museum of Natural History,
Washington, D.C.
Despite numerous studies, coelomate protostomes
relationships are not well understood. A nuclear protein-coding
gene, elongation factor 1 alpha, was used to investigate these
relationships based on previous studies indicating its utility for
resolving deep phylogenetic relationships. Nucleotide and amino
acid sequences of 52 coelomate protostomes deposited in
Genbank were analyzed in a parsimony analysis. Amino acid
data yielded results congruent with other studies despite the
presence of a paraphyletic Mollusca, Annelida and Crustacea.
Nonsensical topologies, however, resulted for the nucleotide
data. This can be attributed in part to homoplasy. The possibility
of paralogue sequences present in the data introduces an
uncontrolled variable and may account for the lack of wellcorroborated trees. A proportion of the homoplasy present in the
nucleotide data results in synonymous substitution of amino
acids, accounting for some of the differences between the
topologies of the nucleotide and amino acid data sets.
Elongation factor 1 alpha, with the available sequence data, is
not effective at recovering deep divergences of coelomate
protostomes.
261
Evolution of vestimentiferan and perviate pogonophorans
(Siboglinidae: Annnelida).
HALANYCH, K. M. Woods Hole Oceanographic Institution, MA.
Pogonophorans are gutless tube-dwelling worms that derive
their nutritional needs from endosymbiotic bacteria. Although
some recent studies have focused on the genetics of
hydrothermal vent dwelling vestimentiferans, little is known about
the genetic diversity or phylogenetic relationships of the perviate
pogonophorans. Using a multi-gene approach (COI, 18S rDNA,
28S rDNA), the evolutionary history of pogonophorans was
reconstructed using standard phylogenetic techniques.
Interestingly, much more genetic diversity was found in the
perviates than in the vestimentiferans. These reconstructions
suggest that the vestimentiferans are nested within a
paraphyletic clade of perviates. This finding adds further support
to idea that Siboglinid evolution was driven by an increasing
ability to adapt to reducing environments.
SOCIETY FOR INTEGRAUVE AND COMPARATIVE BIOLOGY
256
Nitric Oxide in the Invertebrates:
Comparative Physiology and Diverse
Functions
locate NOS-immunoreactive neurons and have found somata in
the apical ganglion and putative sensory neurons in the
epidermis of the foot and mantle. We have hypothesized that
nitrergic maintenance of the larval state occurs through the
activation of guanylyl cyclase and the production of cGMP, but
to date, results from pharmacological experiments are equivocal.
Supported by NSF grant IBN-9604516.
262
Synthesis of nitric oxide via nitrate reduction.
BENJAMIN, N. St. Bartholowmew's Hospital, London, United
Kingdom.
Nitric oxide and cyclic GMP regulate Drosophila visual
system development.
GIBBS, S.M.*, and J.W. TRUMAN. Univ. of California, Berkeley,
and Univ. of Washington, Seattle.
As Drosophila photoreceptors undergo target selection in the
optic lobe they express a soluble guanylate cyclase (sGC) that
can be stimulated by nitric oxide (NO) to produce cGMP. At the
same time, optic lobe cells label with a nitric oxide synthase
(NOS) antibody. In vitro inhibition of NOS, NO or sGC leads to
the overgrowth of retinal axons beyond their normal targets. A
mutation in the sGC gene dgd significantly attenuates retinal
cGMP production in response to NO. Although the retinal
projection pattern appears normal, dgd mutants lack positive
phototaxis as adults. This behavioral defect is rescued with heatshock expression of dgd during the normal window of NOsensitivity. Electoretinograms from these mutants reveal a
diminished postsynaptic response in the lamina following light
stimulus. Normal postsynaptic activity is restored with heatshock expression of dgd during metamorphosis. These in vivo
results support in vitro findings that NO and cGMP regulate
synapse formation between photoreceptors and optic lobe
interneurons.
263
Characterization of nitric oxide synthase activity,
localization, and effects in the sea anemone Aiptasia pallida.
TRAPIDO-ROSENTHAL, H.G.*, K.H. SHARP, AND C.E.
MORRALL Bermuda Biological Station for Research, St.
George's, Bermuda.
The presence of nitric oxide synthase (NOS) activity is shown
in the tropical marine cnidarian Aiptasia pallida. Enzyme activity
was assayed by measuring the conversion of arginine to
citrulline. Optimal activity was found to require the cofactor
NADPH. Activity was inhibited by N-methyl-L-arginine, but not
by the arginase inhibitors L-valine and L-ornithine. Activity was
cytosolic, and was characterised by a Km for arginine of 19.05
mM and a Vmax of 2.96 pmol/min/mg protein. Localization using
NADPH diaphorase staining showed NOS to be mainly present
in the epidermal cells and at the extremities of the mesoglea. In
response to temperature shock, mechanical agitation, or intense
light, anemones retract their tentacles. Animals subjected to
these stresses had lower NOS activities than did controls.
Treatment with NOS inhibitors caused tentacular retraction, while
treatment with the NOS substrate arginine inhibited this
response to stress. These results provide a preliminary
biochemical characterization and histochemical localization of,
and suggest a functional significance for, NOS activity in A.
pallida.
266
Nitric oxide and Xenopus brain development.
PEUNOVA, N. Cold Spring Harbor Laboratory, NY.
Mechanisms controlling the transition of a neural precursor
cell from proliferation to differentiation during brain development
determine the distinct anatomical features of the brain. Nitric
oxide (NO) may mediate such a transition, since it can suppress
DNA synthesis and cell proliferation. We cloned the neuronal
isoform of Xenopus nitric oxide synthase (XNOS1) and found that
in the developing brain of Xenopus tadpoles, a zone of NOSexpressing neurons lies adjacent to the zone of dividing neuronal
precursors. To test whether NO is essential for cell cycle arrest in
Xenopus brain development, we introduced a polymer matrix
impregnated with NOS inhibitors into the ventricle of the tadpole
brain. This resulted in a dramatic increase in the number of
proliferating cells in the optic area and a net increase in the
overall size of the tadpole brain. The excess cell proliferation
grossly perturbed the organization of the brain; however, the
pattern of neurons which differentiated before application of
NOS inhibitors appeared unaffected. Our results indicate that NO
is an essential negative regulator of neuronal precursor
proliferation during vertebrate brain development.
267
264
Serotonin and nitric oxide regulate metamorphosis in the
marine snail llyanassa obsoleta.
LEISE,E.M.\ K. THAVARADHARA, N. DURHAM, and B.
TURNER. Univ. of North Carolina, Greensboro.
As demonstrated by NADPH diaphorase histochemistry,
nitric oxide synthase (NOS) activity occurs in the neuropils of all
larval ganglia. This activity increases throughout larval
development and is pronounced in the apical ganglion. This
ganglion houses the apical sensory organ and innervates the
velum, the larval swimming and feeding organ. Pharmacological
studies with nitric oxide (NO) donors and NOS inhibitors have
shown that NO can inhibit serotonergically induced
metamorphosis in competent llyanassa larvae. Upon initiation of
metamorphosis by a natural inducer, release of endogenous
serotonin presumably leads to the inactivation of NOS. The
pathway by which this happens is unknown. We have recently
used commercial antibodies to mammalian neuronal NOS to
ABSTRACTS
Nitric oxide is a cotransmitter at synapses in CNS olAplysia.
JACKLET, J.W.' and H-Y. KOH. Univ. at Albany, NY and State
Univ. of New York at Stony Brook.
Nitric oxide (NO) is now well known as an orthograde
neurotransmitter in the CNS of Aplysia. Nitric oxide synthase, the
enzyme that produces NO, is found in a few neurons in all
ganglia, including C2 in the cerebral ganglion; and guanylyl
cyclase (GC) the target enzyme of NO, is found in a few other
neurons in the ganglia, including MCC a synaptic follower of
C2(Koh and Jacklet, 1999). Stimulation of C2 causes a vsEPSP
in MCC that is blocked in part by NOS inhibitors and ODQ, a GC
inhibitor. The remaining vsEPSP is mediated by histamine (HA),
thus NO and HA act as cotransmitters in producing the vsEPSP,
which is mediated by the closure of a potassium channel.
Exogenous NO and HA mimic the vsEPSP's depolarization and
decreased conductance. Isolation of MCC and or another
follower CN in cell culture shows that the isolated neurons
respond to NO and HA just as they do in the ganglion and the
45A
We have recently shown that nitric oxide can be synthesised
in the gut of mammals from sequential reduction of inorganic
dietary nitrate. Nitrate is present in large concentrations in
green, leafy vegetables, and is absorbed rapidly from the
stomach and small intestine. It is concentrated at least 10 fold in
saliva and then rapidly reduced to nitrite on the tongue surface
by facultative anaerobic bacteria. Nitrite is futher reduced under
acid conditions to nitric oxide. Using nasogastric intubation in
healthy volunteers we have shown that gastric headspace gas
nitric oxide concentrations rise from a baseline of 15ppm to over
80ppm following ingestion of 1 mMole nitrate (the amount in an
average helping of lettuce). Furthermore, if inorganic nitrate
(1 mMole) is given as lettuce, headspace nitric oxide rises to over
400ppm. We hypothesise that this concentration of nitric oxide is
sufficient to destroy many swallowed pathogens and have
shown that salivary concentrations of nitrite are effective in killing
a wide range of enteric pathogen under acid conditions. It
appears that the enterosalivary circulation of nitrate is important
to protect the lower gut from harmful infections.
265
of cGMP without an associated SGCb subunit. Supported by
BBSRC.
268
271
NO/cGMP signaling and the specification of motor networks
in the crab stomatogastric ganglion.
SCHOLZ, N.L. Northwest Fisheries Science Center, Seattle, WA.
Regulation of nNOS expression by a natural antisense RNA.
O'SHEA, M'and KORNEEV, S.A.. Sussex Center for
Neuroscience, Brighton, United Kingdom.
The stomatogastric ganglion (STG) of crabs is a model for
studying how modulatory transmitters specify different
operational networks from a common pool of neurons. The STG
contains - 30 neurons arrayed into two interacting but discrete
motor circuits: a gastric mill network that drives the teeth of the
foregut, and a pyloric network that directs the rhythmic
movements of the pylorus. In crabs, NO/cGMP signaling is
required for the functional division of the STG into these two
motor networks. NO is synthesized in the terminals of input
neurons, from which it diffuses to activate a soluble guanylate
cyclase (sGC) in a subset of the cells in the ganglion. Inhibitors
of either extracellular NO diffusion (250 uM PTIO) or sGC
activation (50 uM ODQ) trigger a rapid and reversible
disassembly of the gastric mill network. Some gastric neurons
cease firing while others pattern-switch and begin firing in pyloric
time. These results demonstrate that NO-releasing input neurons
can specify the temporal assembly of a functional gastric mill
circuit.
A nitric oxide synthase (NOS) pseudogene is expressed in
the CNS of Lymnaea stagnalis. The pseudo-NOS transcript
includes a region of antisense homology to a neuronal
NOS(nNOS)-encoding mRNA. This suggested that the pseudoNOS transcriptacts as a natural antisense regulator of nNOS
protein synthesis. We show that both the nNOS encoding and
the pseudo-NOS transcripts are co-expressed in giant identified
neurons in the cerebral ganglion. Moreover, reverse
transcription-PCR experiments on RNA isolated from the CNS
establish that stable RNA-RNA duplex molecules form between
the two transcripts in vivo. Using an in vitro translation assay, we
show that the antisense region of the pseudogene transcripts
prevents the translation of nNOS protein. We also find that when
both the nNOS-encoding and the pseudo-NOS transcripts are
present in the same neuron, nNOS enyme activity is substantially
suppressed. These results show that a natural antisense
mechanism mediates the translational control of nNOS
expression in the Lymnaea CNS. Our findings also suggest that
transcribed pseudogenes are a source of a new class of
regulatory gene in the nervous system.
269
The origin and evolution of neuronal nitric oxide (NO)
signaling: A comparative overview.
MOROZ, L.L.* Univ. of Florida, St. Augustine.
272
Nitric oxide and carbon monoxide modulate olfactory
oscillations and odor learning in Umax.
GELPERIN, A. Bell Laboratories, Lucent Technologies, Murray
Hill, NJ.
Ancestral" functions of NO and mechanisms of its synthesis
in primitive organisms are likely well-preserved across 4 Gya of
evolution. In prokaryotes NO is involved in cellular bioenergetics,
non-specific defense mechanisms, intra/intercellular signaling,
the regulation of gene expression. These functions can be crucial
in symbiotic interactions, in the origin of both the eukaryotic cell
and multicellular organization. A role for NO in regulation of
developmental processes, neuronal signaling and synapse
formation could be also derived from these ancestral functions of
NO. Specific neuronal NO signaling seems to be a relatively new
evolutionary innovation. It might be likely that neuronal NOS and
nitrergic neurons were 'introduced' independently. Thus,
somewhat contradictory data related to the presence of NOS in
lower invertebrates could reflect the different stages of the
involvement of NO in neuronal signaling. However, the role of NO
in chemosensory processing and feeding can be one of
evolutionary first neuronal functions for NO in primitive animals.
Variations in feeding ecology are correlated with patterns of NOS
distribution and its functions in feeding networks in some
invertebrate groups.
The procerebral (PC) lobe of the Umax cerebral ganglion is
the major locus of olfactory processing and odor learning. The
PC lobe displays a 0.7 Hz oscillation of local field potential (LFP)
and activity waves which propagate from apex to base at 0.7 Hz.
The LFP oscillation is dependent on intrinsic synthesis of NO and
is modulated by exogenous NO applied via caged NO. Bursting
local interneurons responsible for the LFP oscillation are excited
by NO. CO is also synthesized in the PC lobe and CO also
augments the LFP oscillation. NO synthesis is necessary for odor
learning, presumably mediated by PC lobe memory storage. A
coupled oscillator model of PC lobe circuitry which stores odor
memories has been constructed, stimulated by recent results
showing Lucifer yellow labeled odor memory bands in the PC
lobe (J. Exp. Biol. 202:1855, 1999).
270
Nitric oxide, invertebrates and hemoglobin.
BONAVENTURA, J.* and V. P. LANCE. Duke University Marine
Biomedical Center and Duke University Marine Laboratory, NC.
Functional analysis of the expression and activity of soluble
guanylyl cyclase in insect photoreceptor cells.
ELPHICK, M.R. Queen Mary & Westfield College, Univ. of
London, United Kingdom.
Nitric oxide (NO) exerts effects by causing an increase in
cGMP in cells expressing soluble guanylyl cyclase (SGC), a
dimeric enzyme comprising alpha and beta subunits. Genes
encoding SGCa and SGCb have been sequenced in insects but
little is known about the expression and activity of SGC in insect
nervous systems. A 65 kDa SGCa subunit is expressed in the
nervous system of the locust Schistocerca gregaria and is
localised in identified sensory neurons including photoreceptor
cells of the compound eyes. Here SGCa is concentrated in
phototransducing rhadomeric compartments indicating that SGC
and cGMP may modulate phototransduction. The concentration
of cGMP in eyes is high and similar to cAMP whereas in most
tissues the concentration of cGMP is about 10-fold lower than
cAMP. However, exposure of eyes to NO causes only a 2-fold
and dark-dependent increase in cGMP with light causing Ca 2+ dependent inhibition of NO-stimulated SGC activity. This relative
insensitivity to NO suggests that in locust rhabdoms the SGCa
subunit may maintain high NO-independent basal concentrations
46A
273
Nitric oxide is not just the free radical gas that scientists
once regarded it as. Rich redox chemistry of the diatomic NO
gives this molecule the functional flexibility to interact with both
metal and non-metal components of biological molecules and
thereby allow for allosteric control. Many of the basic discoveries
linking NO to biological systems have arisen from structurefunction relationships in hemoglobin (Hb). For example by
analogy with Hb Lou Ignarro in a now-classic papers on NO
proposed that the activation of soluble guanylate cyclase occurs
via a NO-driven planar shift of the iron in the enzyme's heme.
Other proteins involved in NO biology are heme proteins where
NO coordination plays an essential function so Hb can be
regarded as a microcosm of NO biology. Invertebrates provide
an opportunity to explore alternate functions or perhaps the
original functions of Hbs. Modem oxygen earners might have
arisen as metalloproteins having the primary focus of NO
metabolism rather than reversible oxygen binding. Newly
discovered aspects of Hb function relate to the signaling and
control processes that nitric oxide shows in biological systems.
The comparative approach to these processes has played an
important role in their elucidation.
NO effect, but not the HA effect, is blocked by ODQ. Supported
by NIMH grant MH57746.
Beyond Reconstruction: Using
Phylogenies to Test Hypothese About
Evolution
274
Introduction to 'Using Phytogenies.'
SWIDERSKI, D.L. Univ. of Michigan, Ann Arbor.
275
Morphological and molecular data and the sequence of
character transformation in the origin of cetaceans from
terrestrial mammals.
O'LEARY, M. A. State Univ. of New York at Stony Brook.
Phylogenetic trees of the position of cetaceans among
mammals differ depending on whether they are derived from
molecular or morphological data. Molecular data corroborate the
hypothesis that cetaceans are nested within Artiodactyla as the
sister taxon of hippopotamids. Morphological trees suggest,
however, that artiodactyls are monophyletic and cetaceans are
the sister taxon of an extinct clade, the mesonychians. Partitionhomogeneity tests show that the two data sets are significantly
incongruent, whether fossils are included or not. The number of
informative characters in the molecular data set, however, are
almost ten times greater than in the morphological data set. It is
also estimated that 89% of the clade of interest is extinct. The
number of taxa that can be sampled for morphological (primarily
skeletal) data, therefore, is far greater than the number of taxa
that can be sampled for molecular data. A total evidence
analysis results in an unresolved polytomy of artiodactyls,
cetaceans, mesonychians, and certain condylarths. Examinations
of the molecular and morphological trees suggest very different
scenarios of character transformation.
277
Hypotheses about the evolution of semi-lunar spawning in
three clades of teleosts.
MARTIN, K. L. M. Pepperdine Univ., Malibu, CA.
Many marine algae, invertebrates, and fish time spawning to
occur with extreme tides. The moon and tides may act as
environmental synchronizers on endogenous rhythms for
spawning in fishes of coral reefs, estuaries, gulfs, and the
nearshore environment. Evolution of this behavior may be
influenced by a number of different selective regimes. Among
hypotheses for factors leading to semilunar spawning are
placement of benthic eggs to reduce predation risk, timing of
development for a propitious hatch date, improvement of larval
recruitment or settlement, and migrations of adults to feed with
tides. Semilunar spawning at the water's edge may position the
eggs so they are emerged into air during embryonic
development. This may result in increased oxygen availability
and temperature but also greater risk of desiccation and avian
predation. Semilunar spawning occurs in several species of
some fish families, particularly among the cyprinodonts, the
atherinids, and the osmerids. These clades are used as
examples with relevant behaviors, ecology, and developmental
information mapped onto their phylogenies, to examine the
evidence for some hypotheses about the evolution of semilunar
reproduction in each group.
278
Skeletal developmental patterns among anurans: A historical
perspective.
MAGLIA, A.M.*, A. PUGENER, and L. TRUEB. Univ. of Kansas,
Lawrence.
Despite the fact that anuran skeletal morphology is fairly well
known and is diverse among taxa, our current understanding of
anuran skeletal developmental patterns is poor. This is
unfortunate because anurans, as basal tetrapods, may possess
plesiomorphic developmental patterns that are necessary for
understanding the evolution of other tetrapods. A recent
resurgence of interest in collecting basic ontogenetic information
provides the opportunity to compare developmental trajectories
among anurans. We examined larval morphology, developmental
modifications to the larval skeleton, and timing of ossification
events for several representative anurans (and outgroups) in the
context of a phylogeny, as well as conducted a phylogenetic
analysis using developmental characters. We found that several
developmental features are highly conserved among anurans,
whereas other features differ at various taxonomic levels. We
summarize overall patterns of anuran skeletal development and
discuss the implications of examining developmental trajectories
in a phylogenetic framework.
276
Using phylogenies to study convergence: The case of the
ant-eating mammals.
REISS, K.Z. Humboldt State Univ., Arcata, CA.
Identifying when homoplasy is due to convergence requires
confidence in trees and precise analysis of potentially
convergent characters.Some features of mammals that eat
mostly ants and termites are used as examples of
convergence;the most speciose assemblages of these mammals
are in the orders Xenarthra and Pholidota.My studies on cranial
muscles in xenarthrans, pholidotans and some insedivores aim
to 1)describe the anatomy in ant-eating and non-ant-eating
lineages,2)assess variation among ant-eating lineages.and
3)compare the most derived conditions found (xenarthran
anteaters and pholidotan pangolins).These data clarify the nature
of morphological adaptation in ant-eating mammals,and when
combined with accumulating phylogenetic studies.allow us to
ABSTRACTS
279
A phylogenetic approach to the evolution of functional
integration: Feeding and sensory systems in squamate
reptiles.
SCHWENK, K. Univ. of Connecticut, Storrs.
Evolutionists traditionally approach phenotypic evolution by
atomizing organisms into characters that by definition are
individuated, autonomous bits of the phenotype. Characters are
assumed to evolve independent of other such bits. In reality,
organisms are integrated wholes and characters must be
associated on some level by genetic architecture, development
or function. Can the emergent property of character integration
influence the process of evolution and if so, what is its
phylogenetic signature? Phylogenetic and functional approaches
reveal that the lingual feeding system of iguanian lizards is a
tightly integrated character complex within which internal
47A
Comparative biologists have become increasing aware of the
importance of casting their studies in a phylogenetic framework.
Several papers have shown that traditional methods of
multispecies comparison can be misleading because the failure
to incorporate information about phylogenetic relationships
distorts the statistical parameters being estimated. Several
methods of incorporating measures of relatedness in traditional
analyses have been developed, but these measures of
relatedness are rather dubious. In addition, these methods
preserve the deeper flaw of analyzing differences between
terminal taxa rather that the historical transformations that
produced those differences. Consequently, results obtained by
these methods may also be misleading. A more direct approach
which lacks this fundamental flaw is to use the phylogeny to infer
the history of transformations, then use those histories to test
hypotheses about patterns of evolutionary change. In this
symposium, the speakers will demonstrate how they have used
this approach to address various evolutionary questions. Some
of the topics that will be addressed include: convergence in the
evolution of developmental patterns, trends in the evolution of
locomotion, and congruence in the evolution of form and
function.
distinguish features that have evolved convergently from those
that are variable but not correlated with diet.Interpreting the
extreme similarity in anteaters and pangolins remains
problematic due to lingering disagreement among phylogenetic
hypotheses.Prevailing opinion favors interpretation of these
similarities as convergent, a view that suggests a great deal of
malleability in mammalian muscle evolution, which has
implications for muscles as characters in phylogenetic studies.
selection constrains the evolution of constituent characters. Loss
of the constraint in a sister clade allowed disintegration of the
character complex and initiated a cascade of phenotypic
diversification in the feeding system and in disparate characters
not known a priori to be related, including neuroanatomy and
cranial kinesis. Functional integration has a top-down effect on
the process of phenotypic evolution that is manifest in the
distribution of character states across a phylogeny. Phenotypes
may be self-limiting.
280
The importance of phylogeny in interpreting the crocodylian
fossil record.
BROCHU, C.A.* and P.M.A. WILLIS. Field Museum, Chicago, IL
and Quinkana Pty Ltd., Berowra Hts., Australia.
281
Exaptation and the origin of flight: What do phylogenies test?
PADIAN, K. Univ. of California, Berkeley.
The hierarchical structure of the distribution of
synapomorphies is an inherent advantage of cladograms.
Successive nodes of a cladogram dissect the evolution and
assembly of individual features that comprise complex
adaptations that we recognize in living and extinct organisms.
Given a sufficient sample of transitional nodes in the phylogeny,
it is possible not only to see how the complex adaptation was
assembled, but also to infer the structures and functions from
which it evolved. In this way the role of exaptation in evolution is
explicitly demonstrated. Alternative phylogenies can "test"
alternative hypotheses of functional evolution, but such
reciprocal analyses also test conventional ideas about the
original evolutionary role and importance of structures. New
paleontological evidence, analyzed cladistically, suggests a
wholesale re-evaluation of conventional ideas about the origins
of structures traditionally associated with the evolution of birds
and flight.
An Integrative Approach to the Studies of
Terrestrial Plant-Animal Interactions
282
Eating and being eaten: The role of host plant chemistry in
multitrophic interactions.
BOWERS, M. D. Univ. of Colorado, Boulder.
Plant chemistry may have both direct and indirect effects on
plants, their insect herbivores, and the natural enemies of those
herbivores, as well as other trophic levels such as soil biota and
hyperparasitoids. Understanding the relative importance of plant
chemistry in such complex interactions requires a thorough
knowledge of the chemistry of a particular set of interactants, as
well as their biology. Here I will highlight what we do and do not
know about the roles of host plant chemistry in multitrophic
interactions and suggest avenues that may be useful for future
48A
283
Plant-microbe symbiosis and the regulation of terrestrial
communities.
CLAY, K. Indiana Univ., Bloomington.
There is a growing realization that microbial interactions are
important determinants of plant community structure. The
structure of plant communities, in turn, affects higher trophic
levels. Studies with mycorrhizae, rhizobia and endophytes of
grasses have demonstrated large effects of symbiosis on plant
community structure by affecting colonization, competition,
coexistence and soil nutrient dynamics. All of these factors may
have indirect effects on plant-herbivore interactions. Research on
grass-endophyte interactions has further documented direct
effects of the symbiosis on herbivores through the production of
toxic alkaloids. Long-term field experiments suggest that
grassland community structure is altered by endophyte
symbiosis via changes in herbivore physiology. These results
bely bottom-up and top-down hypotheses and suggest that
inside-out mechanisms of community control occur.
284
Towards a unified view of mutualism.
BRONSTEIN, J.L. University of Arizona, Tucson.
A thorough understanding of the biology of mutualism has
been slow to develop. Two widely held beliefs are partially to
blame: first, that mutualisms are a grab-bag of beneficial
interactions that share little in common either ecologically and
evolutionary, and second, that mutualism is fundamentally
different from better-studied antagonistic interactions such as
competition, parasitism, and predation. I analyze and reject both
propositions. With regard to the first point, I discuss three
general phenomena that seem to characterize all mutualisms
regardless of their natural history, habitat, specificity, or intimacy:
the existence of costs as well as benefits, spatiotemporal
variation in those costs and benefits, and the problem posed by
cheaters (individuals that enjoy the benefits of mutualism while
escaping its costs). With regard to the second point, I review
evidence for the existence of continua between mutualism and
antagonism at a variety of ecological and evolutionary scales.
Finally, I re-introduce the interaction compass, a method of
picturing interactions developed over fifty years ago, which
allows different forms of variation in interaction outcome to be
illustrated and rigorously quantified.
285
From behavioral decisions to forest structure: Caching
behaviors of animals and their effects on the dispersal of
oaks.
SMALLWOOD, P.D.*, M.A. STEELE, and J. BROWN. Univ. of
Richmond, VA, Wilkes Univ., Wilkes-Barre, PA, and Wabash
College, Crawfordsville, IN.
Grey squirrels(Sc/urus caro/inens/s)cache acorns from the red
oak group (RO) more often and at further distances than acorns
from the white oak group (WO). Steele, Smallwood, and Stiles
(this symposium) show how the physical and chemical properties
of acorns influence the caching decisions of squirrels, resulting
in differential dispersal. Here, we test hypotheses of the adaptive
significance of this behavior. We show that several different
animals have similar preferences for caching (and therefore
dispersing) RO acorns. These experiments were done with an
array of different animals, across a wide geographic area,
suggesting that differential dispersal of RO acorns is a general
phenomena. Finally, we present evidence that this differential
dispersal affects the structure of forests, with RO species being
more widely scattered within the forest than WO species. This
suggests that white oaks may employ an ecological strategy
significantly different from red oaks, where white oaks are
adapted to shorter dispersal distances. We discuss this
hypothesis, and ways of testing it.
Although taxonomy is often regarded as secondary to
phylogeny reconstruction, precise communication of phylogeny
with unambiguous nomenclature can bear critically on studies
that apply fossils, their geographic and temporal distributions,
and their perceived ecological adaptations to evolutionary
questions. Recent phylogenetic analyses of Crocodylia show that
a few morphotypes arise multiple times in unrelated lineages.
But distant relatives sharing similar body plans have often been
classified together. This is especially true for long-snouted
crocodylians, which have long been classified on the basis of
'key characters' that appear independently in distant clades, and
which are central to current conflicts between morphological and
molecular phylogenetic data sets. This led to confusion over the
fossil estimate of divergence timing between extant Gavialis and
other living crocodylians. Some of these names include living
species, and failure to distinguish 'form taxa' from natural
assemblages united by ancestry led to 'debates' in the literature
that should never have occurred, such as the issue over the age
of the genus Crocodylus.
investigations. In particular, I will emphasize the importance of a
multifaceted approach, one that integrates chemistry with
behavior, ecology, evolution and physiology, in studying
multitrophic interactions.
286
Historical correlations of defenses and counterdefenses in
an ancient plant-insect interaction.
BECERRA, J. X. Univ. of Arizona, Tucson.
The genus Bursera (Burseraceae) produces resins containing
terpenes stored in networks of canals that run throughout the
leaf veins. In some species the abundant resins create pressure
inside the canals, so that if a piece of a leaf is cut, there is an
immediate release of resins in the form of a squirt. Larvae of the
beetle genus Blepharida (Alticinae: Chrysomelidae) feeding on
these species have to cut the veins before eating the leaves.
Larvae may take up to two hours cutting a vein. This operation
increases their risk of predation. Some Blepharida species have
evolved the ability to use their host compounds for their own
defense against predators. I did a characterization of the
chemical and structural (squirt) defenses in Bursera and a
characterization of the counterdefenses in Blepharida to
determine their evolutionary trends.
287
Micro- and macro-evolution in response to micro- and
macro-herbivores.
BERENBAUM, M. Univ. of Illinois, Urbana.
290
Novel approaches to the study of algal secondary
metabolites.
TARGET!", N.M.* and T.M. ARNOLD. Univ. of Delaware, Lewes.
Marine algal secondary metabolites function in a variety of
ecological roles. In studies of these metabolites, their
concentrations within the algae are generally measured as point
estimates, which represent the metabolite concentration at the
time of collection. Inferences regarding ecological roles and their
underlying mechanisms are then based upon these point
estimates. We suggest that our understanding of how biotic and
abiotic factors influence the production of secondary metabolites
is limited by information that provides only a correlation between
a particular plant stress (e.g. nutrient limitation, irradiance levels,
herbivory) and static metabolite concentrations. Here we discuss
the results of In situ experiments that utilize NaH13CO3 to label
algal secondary metabolites (phlorotannins and terpenes) to
directly measure the rates of metabolite synthesis, turnover and
exudation. This approach is then used to compare the responses
of algal secondary metabolite production to ambient conditions
and to conditions of elevated nutrient levels, decreased
irradiance, and enhanced herbivory.
288
From seed chemistry to behavioral decisions: Effects of
physical and chemical characteristics of acorns on oak
dispersal.
STEELE, M.A.', P.D. SMALLWOOD, and E. STILES. Wilkes Univ.,
Wilkes-Barre, PA, Univ. of Richmond, Richmond, VA, Rutgers
Univ., Piscataway, NJ.
While many food-hoarding animals disperse plants, few
studies have considered how seed traits affect these
interactions. Previously, we showed that mammals selectively
cache acorns of red oaks (RO) over those of white oak (WO) due
to delayed germination of RO acoms. We also reported that
mammals and birds often consume only the basal portion of RO
acorns and that these partially eaten seeds still germinate. Here
we review three sets of field experiments designed to test how
the physical and chemical characteristics of acoms influence oak
dispersal. We manipulate the chemical composition of acorns
and determine that caching decisions are not influenced by
composition of the cotyledon, but rather by a chemical in the
pericarp that may serve as cue of dormancy. We also show that
chemical gradients within acoms promote partial acorn
consumption and seed survival, and that acorn size affects the
probability of oak dispersal. We argue that food-hoarding
decisions are controlled by a suite of physical and chemical
traits that are likely to represent adaptations for oak dispersal.
New Approaches to Studies of Marine
Plant-Animal Interactions
289
Effects of acute and chronic exposure to microalgal toxins to
marine animals.
BURKHOLDER, J. North Carolina State Univ., Raleigh.
Outbreaks of increasing numbers of harmful algal species in
many coastal regions indicate that these organisms are
becoming a more important influence on shellfish populations
ABSTRACTS
291
Form, function and structure in marine plant animal
interactions.
PADILLA, D. K. State Univ. of New York at Stony Brook.
The size, form, material properties, and function of plants
and the feeding apparatus of animals are critical determinants of
plant-animal interactions. Precise consideration of scaling,
structural and material properties, and the functioning of
morphologies are essential to property interpret mechanisms
underlying plant animal ecology as well as the evolution of plant
animal associations. The use of an engineering approach to
these questions has proven to be a very fruitful avenue of
research. In addition, studies that consider the plasticity of
morphologies and behaviors can give us additional insights into
the ecology and evolution of form and function and the roles that
they play in plant-animal interactions. Previous considerations of
form and function have appeared in a 'functional group' context.
However, in the majority of these approaches organisms are on
grouped the basis of gross morphology rather than function,
assuming that for a given species morphology and function,
including behavior, are constant across habitats and
ontogenetically. I will suggest alternative approaches to study
these questions, using examples of marine molluscs and their
algal prey, and consider plasticity in both morphology behavior.
292
Promising directions for greater understanding of digestive
processes in marine herbivores.
HORN, M.H. California State Univ., Fullerton.
Marine herbivores survive and grow on low quality, often
chemically or structurally defended food in which the nutrients
are locked inside relatively indigestible cell walls. Questions
arise: What does it take to be a herbivore? What are their
morphological, physiological and biochemical specializations for
processing plant and algal material? Deeper understanding at all
steps of the digestive process and at different levels of
organization is required to answer these questions. For fishes,
49A
The idea that plant enemies act as selective agents
generating and maintaining phytochemical diversity has been
long established but considerable debate continues as to the
relative evolutionary impacts of different forms of herbivory. This
review examines evidence both direct and indirect in support of
the efficacy of different plant consumers as selective agents on
plant chemistry. Direct evidence consists of quantitative genetic
studies measuring selective impacts; indirect evidence consists
of documentation of specialized modes of action of plant
chemicals as well as distribution patterns consistent with
particular forms of herbivory.
through both direct and indirect mechanisms. Impacts on
shellfish populations from harmful algae have been considered
primarily from the limited view of acute or lethal influences; or
shellfish have been regarded as unaffected 'vectors' of harmful
algal toxins. Accumulating evidence suggests that insidious
sublethal and chronic impacts on shellfish health such as
metabolic dysfunction, long-term behavior alteration, increased
susceptibility to disease, and impaired reproduction and
recruitment may be substantial and pervasive. The available data
point to a critical need to determine the full range of
chronic/sublethal impacts on shellfish by harmful algae, a goal
which can be achieved in part through use of recent innovations
in instrumentation for tracking the metabolic responses of
shellfish species.
structural and kinematic studies of the pharyngeal jaws will help
show how cell walls are disrupted, and how mucus-mediated
absorption may occur in some herbivores. Use of tracer
molecules to examine algal cell porosity in a low pH environment
ought to reveal the role of acid lysis in digestion. Enzyme- and
immuno-histochemistry will allow precise localization of enzyme
activity, and in situ hybridization holds promise for localizing
gene expression sites of digestive enzymes. Identification of
biochemical pathways involving microbial fermentation of various
polysaccharides should reveal vital information about digestive
processes, energy sources and neutralization of secondary
metabolites in many marine herbivores.
and microsatellite genotyping has allowed us to examine the
ontogeny of the symbiosis and the dynamics of the symbiont
populations in the gorgonian Plexaura kuna. These data will be
used to demonstrate the new areas of research opened by
molecular approaches and to highlight some potential technical
difficulties in applying molecular techniques to these systems.
Topic in Integrative Developmental Studies
296
293
Integrating the effects of animals on plant physiology and
community function.
WILLIAMS, S. L. San Diego State Univ., CA.
294
Positive interactions among plants and animals: Mutualism
and commensalism in marine communities.
STACHOWICZ, J.J. University of Connecticut, Storrs.
Positive interactions like mutualisms and commensalisms are
ubiquitous and may lie at the root of such diverse phenomena as
the origin of eukaryotic cells and the flourishing of coral reef yet
these interactions are often ignored by ecologists. Many positive
interactions important to marine community structure can be
placed into the category of 'habitat modification' in which one
species alters biotic or abiotic conditions making the local
environment more favorable for others. Because the outcome of
such interactions is context-dependent making the local
environment more favorable for others. Because the outcome of
such interactions is context-dependent the same pair of species
may be mutualists commensals and enemies under different
circumstances. Interactions have both costs and benefits and
understanding how each of these components changes with
environmental conditions will help predict where and when
positive interactions will be important for community structure.
Because many habitat-forming species like corals or kelps are
dependent on positive interactions the mechanisms and
conditionalities underlying these interactions must be better
understood if we are to develop effective strategies for the
management of marine ecosystems.
Information about how different phyla reorganize organ
systems at metamorphosis is lacking. Actinotroch larvae of the
phylum Phoronida undergo rapid cell death and tissue
reorientation at metamorphosis. How this transition from the
larval to the juvenile state is achieved within the muscle and
nervous systems remains unexplored. Musculature and neural
components necessary for competence and their metamorphic
fates have been studied using TEM and Confocal microscopy
within the larva of Phoronis pallida. This larva can be cultured to
competence within six weeks at 16±1°C. Competent larvae can
be induced to metamorphose by exposure to 20mM CsCI. The
metasomal sac possesses a functional muscle and nervous
system prior to metamorphosis. Eversion of the metasomal sac
during metamorphosis occurs along with the histolysis of the
hood, telotrochal cilia, and epidermal tips of the tentacles.
Muscles and nerves associated with these latter structures also
undergo autolysis. The gut and the tentacles of the larva are
incorporated into the juvenile but undergo remodeling. The
juvenile tentacles and circulatory system are functional two days
post-metamorphosis.
297
Correlation of protein synthesis with morphological changes
during metamorphosis of the glochidia of Utterbackia
imbecillis (Unionoida: Unionidae).
FISHER, G.R.* and R.V. DIMOCK, Jr. Wake Forest Univ.,
Winston-Salem, NC.
The period of metamorphosis from glochidia to juvenile is a
critical time for unionid mussels; however little is known about
the molecular and morphological changes that accompany this
transition. The rate of RNA, DNA and protein synthesis was
measured daily over the development period. There was a
decrease in the rates of synthesis during metamorphosis as
compared to pre-cultured glochidia and juveniles. Once the
animals entered the metamorphic period, the level of cell division
increased steadily for three days and then decreased between
days three and four. The fourth day was characterized by low
rates of cell activity. From day four until the end of
metamorphosis, synthesis levels increased. The animals were
examined histologically to determine what morphological
changes correlated to these molecular changes. During
metamorphosis the glochidial tissues are degraded and the
animals develop the juvenile morphology including a foot, two
adductor muscles, a stomach, gastric shield, and gill bars. This
study provides a detailed description of the development of
these features and their correlation with changes in protein
synthesis.
298
295
Ontogeny and dynamics of a coral-algal symbiosis: A
molecular ecological approach.
COFFROTH, M.A. Univ. of Buffalo, NY.
The symbiosis between dinoflagellates and cnidarians is
among the most important plant-animal interactions that occur
on coral reefs. Although they have been intensely studied for
over 30 y, the application of molecular genetic approaches to
these symbioses has allowed us to examine hitherto intractable
problems. Use of techniques such as RFLP, DNA fingerprinting
50A
Regeneration in echinoid larvae.
VICKERY.M.S.', M.C.LVICKERY, AND J.B.MCCLINTOCK. Univ.
of Alabama at Birmingham.
Adult echinoderms are well known to regenerate missing
body parts. More recently in asteroids and ophiuroids. While
adult echinoids have been shown to have a limited regenerative
capacity have examined regeneration in echinoid larvae. To
examine regenerative capacity in echinoids larvae of the sand
dollar Dendraster excentricus and the sea urchin Lytechinus
variegatus were surgically bisected into anterior and posterior
Few studies of marine plant-animal interactions have
emphasized resultant effects on community/ecosystem function,
in contrast to community structure. As in terrestrial
environments, marine animals profoundly influence primary
production and nitrogen fixation by modulating plant physiology
through modifying the physico-chemical environment of the
plants. Local nutrient supply is enhanced by animal excretions.
By removing vegetation canopies, grazers also reduce shading
and boundary layers. Reduced boundary layers and increased
mass transfer of limiting elements to marine plants is a
consequence of herbivory critically important in marine
environments, but not notable in terrestrial ones. Grazer
modification of the physico-chemical environment is a positive
feedback not yet incorporated into models of trophic structure
that describe the world as a top-down/bottom-up linear
hierarchy. Marine plants also might shift resource allocation, e.g.,
growth vs. reproduction, when grazed. Understanding whether
shifts occur, and if they can influence plant demography, is a
new research avenue that should be fruitful because a change in
plant community structure fundamentally results from differences
in plant population growth rates.
Remodeling of the muscle and nervous systems of the
actinotroch larva of Phoronis pallida at metamorphosis.
SANTAGATA, S. Univ. of Southern California, Los Angeles.
portions. The anterior larval portions of both species were able
to fully regenerate and eventually metamorphosed into normal
juveniles. The posterior larval portions did not regenerate over a
10-day period bisection. To examine the effects of retinoic acid
treatment on the regenerative capacity of sea urchin larvae
exposed the bisected larvae of L variegatus to retinoic acid.
Retinoic acid is known to affect pattern formation during
development and regeneration in a number of organisms
factors(FGFs). Bisected larvae developed numerous deformities
and failed to regenerate role for FGFs in larval sea urchin
regeneration.
299
Characterization of novel genes expressed during
regeneration in larval sea stars.
VICKERY, M.C.L*, M.S. VICKERY, C D . AMSLER, and J.B.
MCCLINTOCK. Univ. of Alabama at Birmingham.
300
Molecular embryology of a stem chordate, Oikopleura dioica.
BASSHAM S.', M. MARTINEZ, and, J.H. POSTLETHWAIT. Univ.
of Oregon, Eugene.
Since Garstang proposed his model for the origin of the
vertebrates in 1928 (i.e. by paedomorphosis leading to
precocious sexual maturation in the larva of a sessile, ascidianlike ancestor), research attention has focused mainly on the
ascidians, a sister class of the larvaceans, as a model for
Urochordata and for the chordate ancestral condition. Recent
molecular phylogenies, however, place larvaceans rather than
ascidians at the stem of the urochordate clade (H. Wada 1998.
Mol. Biol. Evol. 15:1189). It is therefore important that Larvacea
be included in comparative developmental and molecular
phylogeny studies that probe the origins of the vertebrates and
the evolution of chordate development. We have cloned
larvacean members of key developmental gene families: T-box,
Pax, and Hox. Expression analysis of these genes in the embryos
of larvacean Oikopleura dioica provide a basis for comparison of
develomental anatomy among chordates.
301
Fifty ways to leave your larvae: Metamorphosis.
SWALLA, B.J. Univ. of Washington, Seattle, WA.
Within the metazoan phyla, there are a diversity of lifestyles
and life histories that have evolved. The ancestral Deuterostomes
had the ability to live either as solitary or as colonial organisms,
and had considerable regenerative capacities. Studies of
evolutionary modification of the body plan must take into
account the evolutionary changes that have occurred when
organisms move from a colonial to a solitary adult phenotype,
and when the larval life stage is modified or abandoned for a
directly developing adult. We have studied the Urochordata
subphyla and the Hemichordata phyla in an effort to understand
the functional constraints that may exist in the evolution to direct
development from indirect development. This talk will not be like
ABSTRACTS
302
The role of carotenoids on egg quality and development in
the sea urchin Lytechinus variegatus.
GEORGE, S.B.*, J.M. LAWRENCE, A.L. LAWRENCE, J. SMILEY,
and L. PLANK. Georgia Southern Univ., Statesboro, Univ. of
South Florida, Tampa, Texas A&M Univ., Port Aransas.
The present study investigated the effect of adding vitamins
alone, vitamins and beta-carotene, and vitamins and 60% trans
zeaxanthine, 25% trans lutein and 15% other xanthophylls to the
diet of the adult sea urchins. Diet had a greater effect on the
number of eggs spawned than on egg size. The largest numbers
of eggs were produced by females fed oxycarotenoids followed
by those fed beta-carotene. Larvae from parents fed
oxycarotenoids were bigger, developed faster, had higher
survival rates and attained metamorphic competence faster than
those from the other two diets. The numbers of juveniles
originating from parents that had received oxycarotenoids was
significantly higher than those from parents fed beta-carotene.
No juveniles were produced by parents fed vitamins alone. The
data indicate a semi-purified diet that will support normal seaurchin reproduction and development is available. This allows
the sea-urchin to be used as a model to evaluate nutritional
requirements for reproduction and development. Supported in
part by Florida Sea Grant R/LR-l-21.
303
A possible mechanism for phenotypic plasticity in echinoid
larvae.
MINER, B.G. Univ. of Florida, Gainesville.
The ability of a single genotype to produce different
phenotypes as a result of the environment (phenotypic plasticity)
has been well documented. As a result, biologists have a good
ecological understanding of adaptive plasticity. Despite this
ecological understanding, there is almost no work on the
developmental mechanisms of plasticity. That is,
developmental^/ how do organisms produce different
morphologies in response to the environment. This question can
be addressed by studying larva of sand dollars and sea urchins
(plutei). Plutei produce longer arms (feeding structures) when
food is scarce and short arms when food is abundant. In
addition, cells that produce the larval skeleton (primary
mesenchyme cells) and control arm length can be identified
throughout larval development. These cells were quantified in
larvae reared in high and low food concentrations to determine if
longer arms result from an increase in the number of primary
mesenchyme cells specified in early development, or an increase
in calcium carbonate deposition rates.
304
Ecology of planktonic horseshoe crab larvae in Delaware
Bay: Patterns of abundance and the potential for dispersal.
BOTTON, M.L. Fordham Univ., New York, NY.
Horseshoe crab (LJmulus polyphemus) trilobite larvae develop
within intertidal beach sediments before emerging into the
plankton where they reside before assuming a benthic existence.
Over 500 plankton tows were taken from June through August
1998 and 1999 to establish the distributional patterns of trilobite
larvae along a transect from the high tide line to 200 m offshore
of a Delaware Bay NJ beach. Three major patterns were found:
(1) the abundance of larvae in the plankton was consistently
higher on evening than daytime high tides; (2) the largest
numbers of trilobites were encountered during periods of strong
onshore winds and rough surf; and (3) the number of trilobites
decreased abruptly with distance from shore. Larval densities at
the inshore station were 2 to 3 orders of magnitude higher than
at stations 100 to 200 m offshore. The limited dispersal
capabilities of trilobite larvae shown in this study contradict
51A
We recently reported that sea star larvae are capable of
regeneration of missing body parts, providing a new
deuterostome model for the study of regeneration. Using cDNA
subtractive hybridization, we identified 9 cDNA fragments
representing early regeneration-specific gene expression in
bisected bipinnariae of Luidia foliolata. One cDNA, for which the
complete coding sequence was obtained, showed strong
homology to trypsinogen and plasminogen. Another showed
partial homology to a protein kinase receptor. The remaining
fragments showed no significant homology to any GenBank
sequences. Plasminogen plays an important role in early
regeneration and wound repair in vertebrates, and there are
similarities between echinoderm coelomocytes and the immune
systems of vertebrates. We propose that the sea star
regeneration-associated protease gene, S-rap, identified in this
study, may have a function analogous to vertebrate
plasminogen, aiding in early reepithelialization at the site of
injury. It may also play a role in apoptosis during re-development
of the larval body, as proteases play a key role in apoptosis
during embryonic development. Funded by SICB, SIGMA XI, and
AAS.
any other you will ever see or hear at any other meeting. It is all
about metamorphosis and direct development leading to
chordate evolution. There are many ways to evolve direct
development. I will discuss a few of these ideas and then
present our current ideas of how direct development came
about. There must be 50+ ways to leave your larvae and
metamorphose.
earlier population genetic studies which assumed that regional
genetic patterns in Umulus are a consequence of the high levels
of gene flow resulting from the dispersal of planktonic larvae.
305
Deposition of embryo masses in the intertidal: do adults
predict the probability of heat stress for vulnerable
embryonic stages?
PODOLSKY, R.D. Univ. of North Carolina, Chapel Hill.
306
Endoscopic observations of interactions between exploring
larvae and resident sessile marine invertebrates.
WALTERS, L.J.* and J. WELCH. Univ. of Central Florida,
Orlando, and Harbor Branch Oceanographic Institution, Fort
Pierce, FL.
On subtidal surfaces, larvae of sessile invertebrates search
for settlement sites. If occupied by filter-feeding adults, then a
larva must avoid mortality associated with residents. The
response of larvae of the bryozoan Bugula neritina to 4 filterfeeders was recorded. At 2 flow rates, the response of resident
species to 100 larvae and mimics was observed using videoendoscopy. When larvae of Bugula entered the pharyngeal
chamber of the ascidian Styela plicata, larvae were observed to:
1) swim until trapped, 2) attempt to settle, 3) actively swim out of
the buccal siphon, or 4) be forcibly ejected. Particles were
immediately entrained. No larvae or particles were consumed by
the polychaete Hydroides elegans. Particles were entrained along
the tentacles and then rejected. Larval contact rarely elicited any
response. Both larvae and particles were either flicked away by
cirri of the barnacles Balanus amphitrite and 8. eburneus or
captured and brought into the mantle cavity. The former
response rarely damaged Bugula; the latter response often
resulted in larval mortality.
Issues
307
Integration of biology into an interdisciplinary environmental
stewardship curriculum.
CREASER, E. S.', M. MALMBERG, and D. FOX. Unity College,
ME.
Critical thinking and scientific reasoning are central
outcomes for many general education programs, as they are for
the new environmental stewardship curriculum at Unity College.
A team of Interdisciplinary faculty are designing active learning
materials to engage freshmen in activities that integrate the
classroom and field work. Focusing on the first course where
biological and other origin stories are compared, we will share
examples of the learning materials being developed and student
portfolio products, such as student field books with journal
52A
308
Sustainable seas expeditions in national marine sanctuaries:
Toward a new millennium of ocean education and
stewardship.
FRANCIS, L.A.', S.A. EARLE, and F.M. CAVA. Marine
Sanctuaries Division, Santa Barbara, CA, National Geographic
Society, Washington, D.C., Sustainable Seas Expeditions, Santa
Barbara, CA.
The Sustainable Seas Expeditions (SSE), a five-year project
of ocean exploration and public education, provides
opportunities for trained submerisible pilots to explore the
deeper areas of NOAA's nationalmMarine sanctuaries. During its
first year, SSE has captured the interest and attention of the
public and has created tremendous educational opportunities for
communicating the value and importance of protection and
conservation of the marine environment. This year we piloted a
variety of formal and informal educational initiatives including a
SSE Teacher Resource Book, SSE Poster, Teacher-in-the-Sea
Program, Sanctuary Student Summits, Teacher Workshops, Web
Chats, Web Broadcasts and traveling exhibits. These initiatives
reach beyond the walls of classrooms and engage students,
teachers and the public as explorers and field scientists, and
transform national marine sanctuaries into living laboratories for
investigation and discovery. The Sustainable Seas Expeditions
is a project of the National Geographic Society (NGS) in
partnership with NOAA's marine sanctuaries and made possible
by an initial grant from the Richard & Rhoda Goldman Fund.SSE
is led by Project Director Dr.Sylvia Earle and Project Manager
Francesca Cava.
309
Teaching evolution on the web using interactive and
collaborative learning initiatives.
EDWARDS, D.D.* and B.A. COHEN. Univ. of Evansville, IN.
Darwin and Evolution is an integral unit of the World Cultures
sequence, the cornerstone of the general education program, at
the University of Evansville. Because most of the faculty that
teach World Cultures are not well versed in evolutionary issues,
they do not adequately discuss this unit, leaving students with
vague or misguided perceptions as to how evolution has
revolutionized the way in which humanity understands and
interprets the natural world. To address these concerns, we have
developed an evolution web site intended to facilitate student
learning through interactive and inquiry based pedagogical
initiatives and provide students and faculty with historical and
contemporary information on a variety of evolutionary issues.
The web site also provides students and faculty with the
opportunity to engage in an ongoing campus dialogue regarding
critical issues of evolutionary theory. The spirit of the web site is
a collaborative learning initiative in which students interact with
each other and with their professors as fellow participants in the
learning process.
310
The replication rhumba and the translation tango: A whole
body approach to molecular biology.
Voltzow, Janice
VOLTZOW, J. Univ. of Scranton, PA.
Students in introductory biology classes often fail to
appreciate the three-dimensional nature of macromolecules and
the reactions they undergo. Two-dimensional representations of
space-filling molecules are sometimes difficult for them to
visualize. Using the students themselves as molecules, I have
them model some of the most basic aspects of DNA structure,
replication, and translation. This participatory approach places
Few organisms develop in intertidal habitats, perhaps
because development is especially sensitive to environmental
stress. Several invertebrates, including the mollusc
Melanochlamys diomedia, tether embryo masses on the surface
of intertidal sand flats, where temperatures vary from 10 to 34°C.
Late-stage embryos express heat-shock proteins (hsps) above
25"C, and are protected from heat stress. Early-stage embryos,
however, cannot express hsps, and are highly vulnerable to heat
stress during their first 1 -2 low tides. I examined patterns of
reproduction to assess whether adults are influenced by
environmental cues in their propensity to deposit a mass. Mass
deposition changed significantly and regularly over a tidal cycle.
The probability of deposition was negatively correlated with
temperatures experienced by adults during the preceding tide.
Maximum temperatures on consecutive tides were positively
correlated, indicating that some predictive information was
available to adults. These results are consistent with the
hypothesis that adults use information from the environment
when exposing vulnerable, pre-inducing stages to potential heat
stress.
notation. A brief synopsis of the methodology for measuring the
extent to which the outcomes are being achieved will be
presented and preliminary results shared. The work, supported
by grants from the Davis Foundation and the National
Endowment for the Humanities, is particularly focused upon
examining outcomes-based curriculum design as we create a
campus culture for learning and design learning materials that
will actively engage the learner.
them physically into the third dimension and transforms the
flatland of a figure into a whole body experience.
311
dimension to this course gives students a more purposeful
direction in learning anatomy. For students entering a very hectic
medical curriculum, this course may serve as an effective
introduction to human anatomy and medicine.
What do biological educators get from attending C.L.A.S.S.?
WHEATLY, M. G.', T. WOOD, P. RENICK, J. VERNOOY, L.
TASCHENBERGER, J. WEIL, and C. VANCE. Wright State Univ.,
Dayton, OH.
314
Creating Laboratory Access for Science Students is an NSFfunded initiative to train educators to develop lab exercises and
field trips that are universally accessible through attendance at a
2 week workshop. To assess the effectiveness of the CLASS
workshop, educators completed a pre/post test assessing: (1)
prior exposure to disability issues (classroom, teacher education)
(2) perceived preparedness to teach science to student with
disabilities and (3) attitudes about teaching science to disabled
students. The survey instrument was developed by Stefanich
and Norman (1996) and baseline data had been gathered by
randomly distributing the survey via NSTA and AETS. The pre
test data revealed that educators felt poorly prepared to teach
science to students with disabilities. After 2 weeks of acquiring
skills and working one-on-one with high school students with
disabilities, the post test data revealed that the workshop had
achieved the desired objectives of providing strategies to
educators and changing their overall attitude about teaching
laboratory science to students with disabilities. NSF grant
DUE/CCD 9653121.
Practitioners of evolutionary developmental biology (Evo
Devo) differ from mainstream "Modern Synthesis" evolutionary
theorists in many ways. One of them is that Evo Devo treats as
real items of the biological world certain entities that range
across taxa, such as Bauplans, the Vertebrate Limb, and
perhaps developmental fields. The nature and causal influence of
these entities is an important topic of study. These same entities
are seen as ephemera or epiphenomena by mainstream
evolutionists, mere byproducts of the history of natural selection
and diversification. This ontological contrast and its possible
resolution will be explored in this paper.
Case-based learning in physiology: A view from the
trenches.
MUELLER, P.1 and J. TORMEY. Univ. of California, Los Angeles,
Medical School.
Problem-based learning (PBL) is an educational methodology
that actively engages students in the learning experience,
thereby enhancing interest and knowledge retention. In medical
school curricula, students acquire both scientific content and
problem-solving skills by examining carefully designed patient
case-histories. The Department of Physiology at UCLA Medical
School has been involved in an interdisciplinary PBL course,
termed CABS (Clinical Applications of Basic Science) since
1995. It requires students to use insights from all of their first
year courses in order to address clinical issues. Goals include
developing critical thinking skills and working as a team, as well
as deepening understanding of basic science concepts. An
instructor sets the framework, but students must identify relevant
data, develop plausible hypotheses, then locate, evaluate and
synthsize information from outside sources. Student initiative is
important, and demands on faculty time can be high. Recently,
weekly web-based forums have helped increase interactive
learning. Case-based courses require that the students take
responsibility for learning, generate enthusiasm, and can be
successfully applied in a variety of settings.
313
Human gross anatomy for undergraduates.
CULLINANE, D.M. Johns Hopkins Univ. School of Medicine,
Baltimore, MD.
Human gross anatomy in the United States is typically a
graduate/professional level course conducted in medical,
nursing, osteopathic, dental, and other health related programs.
A specifically undergraduate course in human dissection is
extremely rare, yet the percentage of pre-medical students within
life and other science programs is significant. Arguments against
undergraduates conducting human dissection include a lack of
maturity on the part of the students and a lack of facilities and
qualified instruction on the part of the institution. A senior
undergraduate human gross anatomy course was conducted in a
medical school facility using an anatomical/clinical focus.
Students were assigned clinical specialties (orthopaedics,
oncology, neurology, etc.) and were active in presenting predissection reviews of the anatomy and relevant clinical
dysfunctions and procedures (as in medical grand rounds). Also,
clinicians were invited to give reviews and/or clinically oriented
dissection guidance which enhances student focus. The clinical
ABSTRACTS
315
Diversity of natural kinds in biology.
MCCALL, L* and G.J. EBLE. Smithsonian Institute, Washington,
D.C.
Interest in natural kinds revolves mainly about taxonomic
issues. While taxonomic inconsistencies may be ultimately
mended by recourse to cladistic logic, is this the source of the
definition we want to give "natural kind"? On the one hand,
some have proposed different criteria for the definition of kind:
morphological and genetic patterns of overall similarity; shared
developmental pathways; diversification rates; functional
integration; ecological role. If natural kinds are to be defined so
locally, one should debate the propriety of each of these criteria
in contrast to that of historical homology. On the other hand, a
more fundamental issue must be faced before natural kinds
unique to biology can be advanced: do any of these criteria point
to truly universal natural kinds, or are they contingent
manifestations of biological evolution? If kinds are more
contingent than universal and can be characterized only locally,
in terms of surrogate terms like similarity, commonality,
regularity, and pattern, we may be able to validate natural kinds
in biology only by appealing to ahistorical principles to be found
outside biology, as often expressed in many different complex
systems in terms of more abstract notions such as fractals and
bifurcations, or more generally as physical constraints.
316
Wilsonian consilience: Blueprint or pipedream?
RUSSERT-KRAEMER, L* and KRAEMER, E. R. Univ. of
Arkansas, Fayetteville, and Univ. of Wisconsin, La Crosse.
Ever a dauntingly courageous thinker, yet a man of disarming
personal modesty, E.O.Wilson, in his recent work on Consilience,
proposes ideas of enormous importance for biologists. Wilson
seizes our attention with the assertion that human beings can
use the precedent of thinkers of the 18th century Enlightenment,
who argued that fundamental order, implicit in human
disciplines, provides the key to the ultimate unity of all
knowledge. Wilson argues that Biology, and the most
interdisciplinary of academic disciplines, is hence the ideal
candidate for bringing about consilience among the sciences,
the social sciences and the humanities. We find Wilson's
arguments worthy of serious attention. Can biologists,
undertaking the rigorous and necessary Wilsonian Dialogue,
persuade themselves and others to push for the requisite revival,
perhaps at a sputnik level, of overarching concern for the first
rate, solidly interdisciplinary public-educational commitment that
Wilson's vision requires?
53A
312
Ontology of the archetype: What is real in evo devo.
AMUNDSON, R. Univ. of Hawaii at Hilo.
317
The historical impact of the development of standard
laboratory animals on assessing species differences in
physiology and neurology: The case of white rats.
LOGAN, C. A. Univ. of North Carolina, Greensboro.
Morphology
318
High-velocity swimming performance of adult migratory
teleosts.
CASTRO-SANTOS,,T.* and A. HARO. Univ. of Massachusetts,
Amherst, and USGS-BRD-Conte Anadromous Fish Research
Center, Turners Falls, MA.
Migratory fishes are often confronted with zones of high
velocity flow that must be traversed in order to reach spawning
habitat. These challenges can be exacerbated by dams and
other anthropogenic obstacles with profound implications for
spawning success. The extent to which a given velocity
challenge will impede migration is difficult to predict, however,
because existing data on swimming performance (largely derived
from respirometry studies) fail to quantify maximum anaerobic
locomotor capacity of free-swimming species. We addressed
this issue using a 23 m long open-channel flume that fish enter
volitionally and swim against controlled water velocities of 1.54.5 m's" 1 . Performance indicators included distance and duration
of ascent and maximum swimming speed. Distance of ascent
and duration of time spent in the flume varied among species,
determined largely by water velocity and body length. Maximum
swimming speeds ranged from 6-25 body lengths per second
(BL*s~1), and was affected by species, length, and sex.
Performance indicators may be affected by ecology as well as
morphology, with life-history characteristics influencing
motivation of fish confronted with velocity challenges.
319
Alternative neuromotor mechanisms of the fast-start:
Kinematics and EMGs of S- and C-start escape responses.
HALE, M.E. State Univ. of New York at Stony Brook.
Fast-start escape responses include the C-start and the less
well understood S-start. C- and S-start kinematics suggest that
the neural control of the S-start is different from that of the Cstart. To test this hypothesis, motor patterns and behavior of Cand S-starts were compared in muskellunge (Esox
masquinongy). Bilateral EMGs (6 positions) were recorded from
epaxial muscle with simultaneous high-speed video (500 Hz). Cstarts involved synchronous muscle activity on one side of the
body causing the fish to bend into a " C shape. In contrast, Sstarts showed ipsilateral anterior and midbody muscle activity
and contralateral activity in posterior muscle resulting in a "S"
54A
320
Rapid reconfigurations: Modeling the body flexures of faststarting fish.
CZUWALA, P.J.*, C. BLANCHETTE, S.VARGA, R.G. ROOT, and
J.H. LONG.JR. Vassar College, Poughkeepsie, NY and Lafayette
College, Easton, PA.
To understand the mechanics of the rapid, high-amplitude
changes in body shape that generate fast starts, we modeled the
pumpkinseed sunfish, Lepomis gibbosus, as an elastic column
eccentrically loaded by lateral musculature. Since bending
moments are a function of body shape, we used real sunfish to
determine (1) from cross-sections the effective moment arm of
the lateral musculature, and (2) from high speed video the points
about which the body bends. In addition, electromyography of
the myomeric musculature of sunfish revealed simultaneous
contralateral activation in stage 1; we used the relative emg
timing and intensity to model the internal forces from which the
reactive loads were determined. The model predicts that faststarting sunfish produce a standing wave of bending moment
posteriorly that then becomes a traveling wave of bending
moment moving caudally from the anterior region. At the time of
the standing moment wave, the body reaches its maximal
effective flexural stiffness and, as a result, would be able to
rapidly transmit bending moments along the body axis. This
work was funded by ONR grant #N-00014-97-1-0292 to RGR &
JHL
321
Unsteady fluid dynamics of steady undulatory swimming: 3D
simulations of sunfish.
WATTS, P.*, R.G. ROOT, S.S. SHARIFF, P.J. CZUWALA, and
J.H. LONG, JR. Applied Fluids Engineering, Long Beach, CA,
Lafayette College, Easton, PA, and Vassar College,
Poughkeepsie, NY.
In order to understand the fluid forces involved in undulatory
swimming, we use the vortex panel method to model threedimensional, unsteady flow about an untethered, swimming
pumpkinseed sunfish, Lepomis gibbosus. Biological inputs to our
model include (1) accurate, three-dimensional shape
measurements of a 12 cm long sunfish and (2) digitized
swimming motions of the same fish during steady swimming in a
flow tank. Using the numerical renditions of shape and
undulatory motions from these sources, the numerical model
reconstructs the appropriate swimming speed and vortex
shedding pattern. This method allows us to examine the fluid
dynamic and anatomical origins of swimming forces and to relate
observed shape and motions to body flexibility, known
swimming maneuvers, and foraging behavior. The model shows
that swimming motions form low pressure regions, on alternating
sides of the fish's head, that are responsible for thrust
generation. This work was funded by an ONR grant to RGR &
JHL (#N-00014-97-1-0292).
322
Do swimming fish actively tune the motion of their
undulatory waves?
LONG, J.H. JR.', H.-W. COURTLAND, CA. PELL, B. HOBSON,
E.J. TWOHIG, W. Shepherd, and R.G. ROOT. Vassar College,
Poughkeepsie, NY, Nekton Technologies Inc., Durham, NC, and
Lafayette College, Easton, PA.
To test the hypothesis that fish actively tune the motions of
their undulatory waves, we compared, using a Fourier-based
method, the body motions of forward and backward swimming
lamprey with those of theoretical and mechanical models of fish.
Fourier series of up to five frequencies were fit to the axial and
Historians argue that the tools of science are not theoretically
neutral. Rather they carry implicit commitments to constructs
and assumptions that guide explanation and the assessment of
alternative hypotheses. Among the tools that directly shape
inquiry in the life sciences are the living organisms chosen to
carry out empirical tests. Using the history of the development of
white rats as an example, I argue that the development of readily
available standard animals that were selectively bred for
laboratory research was accompanied by a shift from the careful
attention to species differences to the increasingly widespread
assumption that standard animals represented a priori common
processes shared by a wide array of animal taxa. White rats
were first bred for research in neuroanatomy and physiology
beginning around 1900, and this shift was apparent even with
such commonly used 'standard' animals as rats. Prior to
approximately 1915, scientists using rats paid close attention to
species differences. But by the 1930s and 40s this emphasis
disappeared, and many scientists using rats began to assume
rather than empirically conclude the generality of their accounts.
By de-emphasizing organic diversity this trend contributed to the
increasing industrialization of the life sciences and to a devaluing
of comparative analyses in laboratory research.
shaped body bend. EMG amplitude of posterior muscle was
significantly greater during C-starts. However, anterior and
midbody EMG amplitudes and relative onset times between
EMG burst and first movement were not significantly different
between fast-start types. Models of neural control of the C-start
cannot explain the contralateral caudal muscle activity of the Sstart. This suggests that alternative reticulospinal and/or spinal
interneurons are involved in S-start escape behavior. Supported
by NIH NRSA Fellowship MH11861-02.
lateral motions of 31 midline points. Only frequencies that
significantly described the axial and lateral displacements were
included. All of the models and the backward-swimming lamprey
undulate with harmonics of higher-order than the fundamental
frequency and first harmonic in lateral and axial motion,
respectively. In contrast, the forward-swimming lamprey has far
fewer higher-order harmonics and thus operates in a manner
consistent with the active tuning hypothesis. Since higher-order
harmonics produce trajectories that are energetically costly,
forward-swimming lamprey may use their muscles, in part, to
suppress or remove higher harmonics from their undulatory wave
motion. This work was funded by ONR grants to RGR & JHL
(#N-00014-97-1-0292) and CAP (# N-00014-97-C-0462).
323
Vortex wake dynamics of turning in sunfish.
DRUCKER, E.G.* and G.V. LAUDER. Univ. of California, Irvine.
324
Wake dynamics of the heterocercal tail in freely-swimming
sturgeon (Ac/penser transmontanus).
LIAO, J.* and G.V. LAUDER. Harvard Univ., Cambridge, MA.
326
Pectoral fin diversity and evolution in labrid fishes.
WAINWRIGHT, P.*, M. WESTNEAT, and D. BELLWOOD. Univ. of
California, Davis, Field Museum of Natural History, Chicago, IL,
and James Cook Univ., Townsville, Australia.
Swimming labrid fishes (wrasses and parrotfish) use at least
two mechanisms to generate thrust with their pectoral fins: drag
based 'paddling' and lift based 'flying'. The fin shapes expected
to perform best with these mechanisms differ: rounded
symmetrical fins for paddling and higher aspect ratio fins for
flying. We generated a morphospace of pectoral fin shape based
on anatomical measurements of 719 specimens from 120
species of Great Barrier Reef labrid fishes as a basis for
interpreting locomotor diversity in this group. Fin aspect ratio
varies among species, from a low of 0.5 to a high of over 2.2.
Swimming speed estimates of 41 species were made as fish
moved naturally about the reef. After removing body size effects
faster swimming species have higher aspect ratio fins. Evaluation
of fin shape evolution in the light of a phylogeny of labrid genera
indicates relatively low aspect ratio fins are plesiomorphic and
high aspect ratio fins have evolved at least seven times, most
frequently in association with the origin of midwater
zooplanktivory. Supported by ARC A19802057 to DB & PW, NSF
DEB9815614 and ONR N000149910184 to MW.
327
Function of the pectoral fins during locomotion in the
bamboo shark Chiloscyllium plagiosum.
WILGA, CD.* and G.V. LAUDER. Harvard Univ., Cambridge, MA.
During steady horizontal locomotion, the heterocercal caudal
fin of sturgeon has been shown to move in a complex sinusoidal
manner. This movement pattern has been hypothesized to
generate locomotor forces parallel to the body axis, which is
maintained at a positive angle of attack. During maneuvering,
changes in body axis angle should alter the direction of thrust
from the caudal fin. We used Digital Particle Image Velocimetry
with both horizontal and vertical light sheet orientations to
quantify patterns of wake velocity and vorticity behind the
heterocercal tail of sturgeon swimming freely at 1.2 and 2.0 L/s.
At 1.2 L/s sturgeon produce unlinked vortex rings, with each half
tail beat producing one distinct ring. At 2.0 L/s sturgeon
generate linked rings. The orientation of the vortex rings changes
predictably with alterations in the angle of the body axis, despite
a largely consistent horizontal orientation of the fluid jet through
the ring core. Our results show that vortex ring angle and jet
angle need not be perpendicular, and suggest that tail flexibility
may account for the maintenance of a horizontal momentum jet
despite alteration of the vortex ring axis.
The bamboo shark is a benthic shark that uses its relatively
flexible pectoral and pelvic fins to move about on the substrate.
In a previous study, we found that the pectoral fins of the more
pelagic leopard shark are less flexible, are not used to move
about on the substrate, do not provide lift during steady
swimming, and are held at a negative dihedral angle promoting
maneuverability. Here, we examine swimming behavior in the
bamboo shark to determine if a benthic lifestyle affects the
function of the pectoral fins while swimming in the water column.
We use three-dimensional kinematics and digital particle imaging
velocimetry to examine pectoral fin function in 4 individuals
swimming at 1.0 l/s while holding, rising and sinking in the water
column. When bamboo sharks hold position in the water column,
the pectoral fin is held at a slightly positive angle of attack,
indicating that some positive lift may be generated. The pectoral
fins are also held more horizontally than in leopard sharks,
providing increased stability during steady swimming. In
addition, the pectoral fins of bamboo sharks move through a
broader angular range while maneuvering in the water column
than in leopard sharks.
325
328
Locomotion in scombrid fishes: Function of the finlets in the
Chub mackerel Scomber japonicus.
NAUEN, J.C.* and G. V. LAUDER. Harvard Univ., Cambridge,
MA.
Pelvic fin locomotion in the skate, Leucoraja erinacea.
KOESTER, D.M.* and C.P. SPIRITO. Univ. of New England,
Biddeford, ME.
Finlets are small nonretractable fins that extend dorsally and
ventrally along the midline between the second dorsal and anal
fins and the caudal peduncle of scombrid fishes. The five finlets
of S. japonicus are stiffened by bony rays, rotate on a
cartilaginous pad, and are under at least some muscular control
by two muscle groups that originate from the carinal muscles
and insert onto the base of each finlet. During steady swimming
ABSTFIACTS
Descriptions of pectoral fin swimming in skates are often
accompanied by suggestions that the pelvic fins also assist in
locomotion especially along the bottom. The pelvic fins of skates
are characterized by a notch in the lateral margin which partially
separates each fin into anterior and posterior lobes. The skeletal
elements and musculature of the anterior lobe form a functionally
distinct appendage, termed the cms. Video recordings of the
little skate, Leucoraja erinacea, in the field show that locomotion
55A
To explore the hydrodynamic mechanism by which fish turn,
we examined the vortex wake produced by bluegill sunfish
{Lepomis macrochirus) during escape maneuvers. Fish 22 cm in
length (L) swimming at 0.5 L/s were induced by a visual stimulus
to execute turns using only the pectoral fins. Patterns of water
flow in the pectoral fin wake were quantified using digital particle
image velocimetry. Thin horizontal sections of near-fin flow were
illuminated by a 5 W argon laser and video taped at 250 fps.
Each pectoral fin produces a discrete vortex ring during turning
that differs significantly in strength and orientation from that
used in steady swimming. During turning, the ring's central fluid
jet increases twofold in mean velocity (to 12 cm/s) and changes
in orientation up to 60 *. Turning is accomplished by an
imbalance of forces exerted by the left and right fins, involving
both a temporal delay between movements of the strong- and
weak-side appendages and a significant difference in the
orientation of wake momentum flow on opposite sides of the
animal. Bluegill are capable of increasing locomotor force output
during turning fivefold from steady swimming, a result reflecting
the mechanical and functional versatility of the teleost pectoral
fin.
the finlets oscillate symmetrically in the horizontal and vertical
planes. The amplitude of oscillation increases posteriorly and is
phased anterio-posteriorly; both the amplitude and phase of
oscillation were independent of swimming speed over the range
of 1.2 - 3.0 lengths/s (l/s). During gliding (0.85 l/s) the finlets
occasionally oscillated independently of each other and the
body. The angle of attack of the finlets averaged 0 degrees over
the tailbeat, indicating no net contribution to thrust production.
The most posterior finlets reached maximum excursion as the
tail decelerated at the end of each stroke. At these times the
finlets could deflect water into the developing tail vortex, which
would increase swimming efficiency.
along the bottom is almost always due to the exclusive activity
of the caira of the pelvic fins. Both crura function synchronously
to generate thrust by pushing off the bottom allowing the skate
to glide through the water as the crura are repositioned for the
next thrust phase. This type of locomotion, which consists of
alternating phases of thrust generation and gliding, is called
punting (Long, J.H., personal communication; Martinez, et.al.,
1998). Video recordings of captive skates were also obtained to
examine kinematics of individual punting cycles. We conclude
that punting is a significant mode of locomotion suited to the
benthic lifestyle of skates.
329
Swimming mechanics of negatively buoyant brief squid.
BARTOL, I.K. The College of William and Mary, Gloucester
Point,VA.
330
Optimal kinematics of flapping wing/fin propulsion.
WRIGHT, B. Univ. of Chicago and Field Museum of Natural
History, Chicago, IL.
An optimality analysis provides a theoretical framework for
examining the stroke kinematics of balistiform locomotion in a
taxonomically broad sample of Balistidae (triggerfishes) and its
sister group Monacanthidae (filefishes). Based on two fluid
dynamic models (one for rigid-chord high-AR wings, one for lowAR undulatory fins), the optimality simulations suggest a
quantitative explanation for the observation that the ratio of
forward speed to wave speed is typically around 0.7 during
steady forward swimming. When thrust is prescribed, high
efficiencies are possible over a wide range of stroke angles
through the appropriate tuning of stroke frequency and timedependent spanwise variation in angle of attack (described by
wave speed or spanwise dynamic twist). At biologically relevant
values of thrust, both low and high-AR fins are capable of
achieving nearly optimal efficiencies, while high-AR fins are
clearly better for high-speed propulsion. Morphological and
physiological constraints set boundaries on the kinematic
parameter space available to paired-fin swimmers.
331
Spatio-temporal variables and modulation of speed in
swimming frogs.
NAUWELAERTS, S.* and P. AERTS. Univ. of Antwerp, Belgium.
To study the spatio-temporal behaviour of swimming cycles
in frogs, swimming bouts of Rana esculenta were video-taped.
Durations and displacements of the propulsive, glide and
recovery phase (i.e. the six spatio-temporal variables) were
determined and instantaneous velocity fluctuations and average
locomotor speed were calculated. None of these six correlate
with average speed. This points either at the absence of
coordination or at the presence of a complex control system
attuning the spatio-temporal variables to eachother to realize any
intentional speed, instantaneous velocities at the transitions
between successive phases, however, are highly correlated with
56A
332
Forces on model animals as they emerge from the water.
GOLDMAN, J.A. Duke Univ., Durham, NC.
When an animal such as a penguin, whale, or fish jumps out
of the water, its interaction with the air-water interface involves
an uncertain interplay among forces arising from gravity, static
and dynamic pressure, viscosity, and surface tension. To
understand this interaction better, I have measured the timevarying force on model animals as they emerge from the water.
The net downward force acting on disks, spheres, and
streamlined bodies travelling vertically through the interface at
constant speeds, increases sharply during their emergence
(Reynolds numbers in water between 3 700 and 90 000; Froude
numbers between 0.01 and 2). I have also constructed a simple
mathematical model that computes the time-varying force on the
same model animals when only their weight and buoyancy are
considered. Comparisons of data with model indicate that the
drag on disks oriented perpendicularly to flow roughly doubles
as they cross the interface and then decreases nearly to zero
shortly after their emergence. The drag on all other models
simply decreases from a steady value to near zero immediately
upon their emergence. For these latter models and thus most
likely for animals jumping vertically out of the water, drag
augmentation near the interface appears insignificant.
333
Mechanical performance of underwater flying in aquatic
vertebrates.
WALKER, J.A.* and M.W. WESTNEAT. Field Museum of Natural
History. Chicago, IL.
Aquatic flight is a major locomotor mechanism in many
vertebrates and occurs in fishes, turtles, birds and mammals.
Aquatic flight is performed by rowing or flapping the pectoral
appendages to generate thrust. We used a computer simulation
to compare the performance of rowing and flapping appendages
across a range of speeds. Hydrodynamic models revealed the
propulsive advantages of aquatic flight over other forms of
propulsion and demonstrated the relative mechanical benefits of
flapping versus rowing. Flapping appendages were more
mechanically efficient than rowing appendages at all speeds,
suggesting that animals that frequently engage in locomotor
behavior that requires energy conservation should employ a
flapping stroke. The low efficiency of rowing at all speeds begs
the question, why does rowing occur at all? The answer lies in
the ability of rowing to generate much more thrust than flapping
during the power stroke. Large forces are required for
accelerating, turning, and braking, suggesting that rowing should
occur in slowly swimming animals that maneuver frequently.
Model predictions are supported by observed patterns of
locomotion in a wide range of aquatic vertebrates. Supported by
ONR N000149910184.
334
Control of aquatic flight in Clione limacina.
FLICK, K. Univ. of Washington, Seattle.
Directional control of aquatic flight requires the animal to
steer by changing its wing kinematics and/or by using its
appendages as rudders. To determine the relative contributions
of wing steering and body ruddering, I used 3D-image analysis
of body turning and wing tip kinematics of the opisthobranch, C.
limacina. I tracked 3D coordinates of the head, mid-body, and
trunk tip in free flying animals, and the wing tip position in
tethered animals. Data from free flying animals show that the
motion of the head and mid-section precedes motion of the
Squids are highly maneuverable organisms capable of
swimming in various orientations as a result of a unique body
architecture and two propulsion systems: the jet and fins.
Negatively buoyant, slow squids, such as Lolliguncula brews, rely
heavily on both forms of propulsion and manipulate arm and
mantle angles, contraction rates, and swimming orientation in
ways that are not fully understood. To learn more about
swimming mechanics and behavior of these squids, Lolliguncula
brevis of various sizes (1-8 cm mantle length) were videotaped in
flumes swimming in both tail-first and arms-first orientations, and
the footage was analyzed using motion analysis equipment.
Additional force and flow visualization data also were collected
using models and live squid placed in flow tunnels. Results
suggest that lift generation is a critical issue for squid of all sizes
at low speeds, tail-first and arms-first swimming preferences as
well as fin utilization are functions of both swimming speed and
size, the acceleration reaction is an important instantaneous
force during the jet cycle, and complex interactions of arm
movement, mantle contraction, and fin motion may account in
part for the inherent inefficiency of jet propulsion.
the average locomotor speed. Mathematical simulations prove
that such strong correlations emerge automatically from
randomly chosen propulsive, glide and recovery characteristics.
Apparently, the overall swimming performance is mainly
determined by the magnitude of the propulsive impulse, whereas
glide and recovery characteristics have only minor effects. In this
respect, swimming can be regarded as 'jumping in water' and it
is postulated that the strategy to control swimming performance
(speed) is retained from the evolutionary primary saltatorial
mode.
trunk by about 1.5s during turns. This suggests that the trunk
does not activate a turn. Analysis of the 3D coordinates of the
wingtip in tethered animals shows that the amplitude of the
stroke plane is about 30% larger and more variable in animals
pitching about the tether, compared to those hovering steadily
above the tether. I use a two-dimensional, fluid dynamic model
of the wing during tethered flight to compare the forces arising
from the observed changes in the wing kinematics to the
theoretical forces necessary to turn the animal. As in flying
insects, steering control in C. limacina appears to arise from
stroke-to-stroke changes in wing kinematics. (NSF grant IBN9511681)
335
Toad hindlimb muscle function during hopping and
swimming.
GILLIS, G.B.' and A.A. BIEWENER. Harvard Univ., Cambridge,
MA.
336
Motor control of swimming and walking in red-eared slider
turtles.
BLOB, R.W.', C. PACE, and M.W, WESTNEAT. Field Museum,
Chicago, IL.
Many turtles use their limbs for both walking and swimming.
We examined modulation of hindlimb motor patterns between
these behaviors in red-eared sliders (Trachemys scripts) using
EMGs and video of locomotion. Kinematic differences between
walking and swimming include: (1) femoral retraction is a greater
fraction of the stride in walking (70%) than in swimming (48%);
(2) the knee flexes during protraction and extends during
retraction in swimming strokes, but flexes then extends during
both protraction and retraction in walking steps. Hindlimb motor
patterns correlate with these kinematics. Femorotibialis (FT, a
knee extensor) shows a low amplitude burst during most of each
knee extension phase in walking, but one high amplitude burst
during knee extension in swimming. The knee remains extended
throughout retraction in swimming despite cessation of FT
activity and onset of activity by its antagonist, flexor tibialis
intemus (FTI). Knee extension may be maintained during
retraction by the force of water on the limb during propulsion.
FTI is not active during initial knee flexion in swimming or
walking and may act primarily as a retractor rather than a knee
flexor. NIH 1F32NS1081301 to RB and ONR N000149910184 to
MW.
338
Effects of temperature on performance and the axial motor
pattern of a sandswimming lizard.
JAYNE, B.C.* and M.W. DAGGY. Univ. of Cincinnati., OH.
We recorded the activity of the epaxial muscles in the trunk
and tail of sandswimming Mojave fringe-toed lizards (Uma
scoparia) to determine whether the motor pattern of this
specialized behavior differs from the common features of axial
motor patterns of other ectothermic vertebrates. Initially, muscle
activity during sandswimming was a standing wave pattern in the
trunk and tail. Next, the hind limbs moved alternately and the
caudofemoralis muscles and nearby axial muscle in the trunk
and tail had long duration emg bursts, whereas the anterior trunk
had shorter more frequent emg bursts. Finally, tail burial involved
a posteriorly propagated traveling wave of axial muscle activity
within localized regions of the tail. With increased temperature
(from 22 to 40"C) the mean frequencies of axial oscillations
increased from 7 to 21 Hz, and the greatest value (33 Hz) was
nearly twice that reported for the maximal limb cycling frequency
during running. Mean burial time at the lowest temperature (3.8
s) was nearly twice that for higher temperature. The total
numbers of emg bursts and their duty factors did not change
significantly with temperature.
339
'Stick and slip': A novel mechanism of sound production in
spiny lobsters (Palinuridae).
PATEK, S. N. Duke Univ., Durham, NC.
Unlike the familiar ratcheting of a hard pick over a ridged file
in crickets, crabs and other arthropods, palinurid lobsters
produce a pulsed sound by rubbing a soft tissue plectrum over a
hard file covered with microscopic shingles. The friction between
the soft tissue plectrum and microscopic shingles results in a
pulsed 'stick and slip' movement which produces a distinctive
rasping sound. In order to correlate sounds and associated
movements of the plectrum, I attached a Hall-Effect sensor to
the file and a magnet to the plectrum. The sensor tracked
changes in magnetic field as the plectrum moved over the file.
Results from the sensor data reveal that sound is produced each
time the plectrum 'slips' over the file in a rapid succession of
stick and slip movements. In addition, I used electromyography
to determine which muscles control the sound-producing
movement of the plectrum over the file. This sound-producing
mechanism illustrates a novel way in which soft tissue materials
can be used to produce a pulsed sound. The use of soft tissue
to produce friction-based sound pulses may be beneficial for
molting lobsters that otherwise would be unable to produce
ratcheting sounds with a softened exoskeleton.
337
Turning performance by leg and wing propulsion of
swimming whirligig beetles.
FISH, F.E. West Chester Univ., PA.
Turning performance is constrained by morphology, whereby
flexibility of the body, and mobility and position of the control
surfaces determine the level of performance. Whirligig beetles
(Coleoptera: Gyrinidae) are rigid bodied, but these aquatic
ABSTRACTS
57A
One of the obvious roles of a tetrapod's limbs is that of
generating the forces required for locomotion. Most studies of
tetrapod locomotion have focused on movement in a single
environment. To investigate how limb muscle function might be
modified to accommodate changes in the locomotor
environment, patterns of muscle strain and activation were
examined during hopping and swimming in the toad .Bufo
marinus. Toads were implanted with sonomicrometry crystals
and EMG electrodes in major limb extensors and allowed to
locomote in water and on land. Muscles were activated 5-40 ms
before limb extension begins in both environments. The degree
and rate of strain in some muscles (e.g. semimembranosus)
encompass similar ranges during hopping and swimming (strain
= 0.1-0.4L, rate = 1-3 L/s, depending on locomotor effort). Other
muscles (e.g. gluteus and cruralis) often undergo distinct strain
regimes during swimming in which they begin to shorten before
activation as opposed to during hopping in which they shorten
only after activation. Thus while the function of some muscles
may not be altered by an environmental shift, other muscles
undergo notable changes in their patterns of activation and/or
strain.
insects can swim rapidly in circular patterns. Turning
performance of swimming whirligig beetles, Dineutes horni, was
assess by videotaping beetles in a small (115 mm diameter)
arena at 500 and 1000 frames/s. Circular trajectories were
executed as continuous powered turns. Asymmetrical paddling
of the out-board legs was used to power the turn. Turns were
produced also by abduction of the in-board elytra and vectored
thrust generated from sculling of the wing at 46.5 Hz. The
abducted elytra increased drag and acted as a pivot. Turning
radius was not associated with swimming velocity; whereas
turning rate was related to centripetal acceleration. Relative
minimum radius was 24% of body length. Maximum rate of turn
was 4428 deg/s with maximum centripetal acceleration of 2.86
g. Compared to flexible bodied vertebrates, relative turning
radius of whirligig beetles is constrained by a rigid body and use
of drag-based propulsive mechanisms, however, these
mechanisms permit continuous turning.
Topic in Physiological and Biochemical
Mechanisms
340
Genetic analysis of adaptation to temperature stress.
RIEHLE, M.M.*, A.F. BENNETT, and A.D. LONG. Univ. of
California Irvine.
341
Thermal physiology of fish: Does behavior acclimate, and is
hotter better?
O'STEEN, S . \ M.M. RIEHLE, and A.F. BENNETT. Univ. of
California, Irvine.
This study examines the consequences of temperature
acclimation for the locomotor physiology and behavior of two
species of ectothermic fish, the cyprinids Barbus barbus and
Barbodes schwanenfeldii. We acclimated fish in the laboratory
for at least 6 weeks at 4°°C below and above critical thermal
maxima and minima, respectively. We then assayed voluntary,
burst and endurance swimming performance, myosin heavy
chain expression and myosin ATPase activity, at several assay
temperatures. Our results demonstrate acute effects of
temperature on some but not all traits, and acclimation effects
on only some traits. Notably, response patterns differed both
among species and within organismal and suborganismal
categories of traits. Our study indicates that fish behavior can
acclimate, that hotter can be better (i.e., performance increases
with either acute or acclimation temperature), and that
acclimation can be beneficial (relative performance increases
following acclimation), but critically, that none of these
possibilities can be generally assumed. Supported by NSF Grant
IBN-9420155.
343
Physiological control of heat exchange during basking and
shuttling in lizards.
DZIALOWSKI, E.M.* and M.P. O'CONNOR. Univ. of North Texas,
Denton.
Differences in warming and cooling in lizards have been
measured in animals exposed to long step changes in
environmental temperature, such as during basking. These
differences have been thought to translate into the ability to
control warming and cooling over short time periods, such as
during shuttling. Techniques have not been available to measure
time constants of shuttling animals. Using a new technique, we
measured time constants of Iguana iguana experiencing short
periods of warming and cooling. Animals were subjected to both
simulated basking and simulated shuttling. When exposed to
simulated basking, warming time constants were shorter than
cooling time constants. In response to simulated shuttling,
warming and cooling time constants did not differ. We measured
subcutaneous blood flow and heart rate during shuttling and
basking. During long warming, subcutaneous blood flow and
heart rate increased and returned to pre-warming values upon
cooling. In response to simulated shuttling, blood flow changed
with surface temperature while heart rate did not vary over the
same range.
344
Unappreciated thermal tolerance in a widely distributed
desert rodent.
TRACY, R. L.* and G.E. WALSBER. Arizona State Univ., Tempe.
A long-held assertion has been that many nocturnal desert
rodents possess low heat tolerances and are nocturnal because
of this limitation. To test this claim, we used a treadmill to
examine the thermal tolerances of one subspecies of desert
rodent, Merriam's kangaroo rat, Dipodomys merriami merriami,
from contrasting environments. We measured body temperature,
evaporative water loss, and metabolic rates at different ambient
temperatures. Mesic- and xeric- site animals possessed similar
tolerances and remained active up to Tb=42"C. At Ta=42.5°C,
however, T b increased more quickly in mesic- than xeric-site
animals. Most animals from both sites could run at Ta=40"C for
at least 30 min; however, at 42.5°C, most could not run more
than 18 min. Nonetheless, activity in excess of 0.5 hr occurred at
40°C. This and previous studies imply that geographic variability
in water loss and not tolerable T b accounts for the occupancy of
this subspecies in contrasting environments. Thus, the benefits
of nocturnality for this species appear to reside more in
purposes of water conservation and less on the direct regulation
342
Effect of shape and orientation of Te models on estimated
operative temperatures.
O'CONNOR, M.P.' and C.R. TRACY. Drexel Univ., Philadelphia,
PA, and Univ. of Nevada, Reno.
Operative temperature (Te) models are used to assess the
body temperatures available to ectotherms. Often, few models
are used in each microhabitat. When solar radiation is an
important heat exchange pathway, this can skew Te estimates if
absorbed radiation depends on the orientation of the animals to
the sun and the models used do not adequately sample the
orientations available to the animal. We modeled absorbed solar
radiation for 3 reptilian shapes, a tortoise, a limbless cylindrical
snake or lizard, and a lizard with cylindrical limbs. Absorbed
radiation varied 2-3 times more strongly with the solar elevation
than with the azimuth of the sun for the tortoise shape.
Maximum radiant loads (per unit area) were smaller in the lizard
shapes with minimum absorption when the rostrum was pointed
at the sun. For lizard shapes, radiant load depended more
strongly on azimuth and less strongly on elevation of the sun
58A
345
Does Merriam's kangaroo rat {Dipodomys merriami) select
ambient temperatures that allow it to conserve water or
energy?
BANTA, M.R. Univ. of Nevada, Reno.
Merriam's kangaroo rat (Dipodomys merriami) is a small,
desert-dwelling, granivorous rodent in the family Heteromyidae.
Kangaroo rats need to conserve both water and energy. They
can conserve energy by selecting temperatures within their
thermoneutral zone (TNZ). They can conserve water by selecting
temperatures well below their TNZ where metabolic water
production exceeds evaporative water loss, putting them into a
state of positive water balance. But, kangaroo rats cannot
conserve energy and water simultaneously. I am investigating
what temperatures kangaroo rats choose under conditions of
water stress, energy stress and both stresses simultaneously.
Animals are placed in an apparatus consisting of 8 shuttle
Although many studies have examined organismal or
physiological responses to environmental stress, the genetic
basis of such adaptation is only beginning to be explored. Six
lines of Escherichia coli were grown at 42°C for 2000 generations
and all six lines exhibited increases in relative fitness
(mean=33.5%) when grown in their propagation environment.
Utilizing DNA array technology, these six thermally adapted lines
of E. coli were screened for gene duplications and deletions to
determine the genetic changes correlated with enhanced relative
fitness at 42'C. Three of the six selected lines have a 25 Kb gene
duplication in the 59th minute of the chromosome. This
duplicated region contains genes that have previously been
shown to enhance stationary phase survival under benign or
stressful conditions and to help in the repair of damaged
proteins. With frozen isolates from different time points of the
laboratory natural selection we will determine at what generation
gene duplication occurred and whether this coincided with the
increase in relative fitness. Supported by NSF-IBN 9507416,
NSF-IBN 9905980 to AFB and a NSF Predoctoral Fellowship to
MMR.
than for tortoises. To assess the importance of shape and
orientation to the sun for the use of models to estimate Te, we
assessed the range of predicted Te's for models of all three
shapes with midlines oriented at 10' intervals on a sunny
summer day. Radiant loads on tortoise-shaped models varied
little (< 1-3'C in Te), whereas for lizard shapes with low wind
speeds, the range of temperatures could reach 8-10'C during
mid-morning and mid-afternoon.
boxes, with each box held at a constant temperature between
10-38 C. Motion detectors record the amount of time animals
spend in each box. I predict that energy-stressed kangaroo rats
will spend more time in boxes with temperatures in their TNZ
and water-stressed kangaroo rats will spend more time in boxes
with temperatures below their TNZ. I am most interested in
learning where animals that are both energy and water-stressed
will spend their time.
346
Differential synthesis and distribution of a symbiosis protein,
SYM32, in the sea anemone Anthopleura elegantissima.
SCHWARZ, J.A.* and V.M. Weis. Oregon State Univ., Corvallis.
347
Evidence of horizontal gene transfer in a cnidarian-algal
mutualism.
WEIS, V.M.* and W.S. REYNOLDS. Oregon State Univ., Corvallis.
349
The role of glutamine synthetase in inorganic nitrogen
assimilation by chemoautotrophic bacterial-invertebrate
symbioses.
LEE, R.W. Washington State Univ., Pullman.
Symbioses between chemoautotrophic bacteria and marine
invertebrates use environmental sulfide as an energy source and
assimilate inorganic carbon and nitrogen. It is hypothesized that
inorganic nitrogen is assimilated via glutamine synthetase (GS) of
the symbionts. Symbiont GS is distinct from host GS and similar
to GSI of free-living gram negative bacteria based on DNA
hybridization, immunoblots, and characteristics of the partially
purified protein. Further experiments were conducted on the
coastal clam symbiosis Solemya velum to determine the
importance of GS in ammonia assimilation. A flow-through
respirometry system was constructed for exposure of clams to
controlled conditions with automated determination of metabolic
fluxes. In order to grow autotrophically, net uptake of ammonia
(rather than excretion) must occur. In respirometry experiments
S. velum consistently took up ammonia. Exposure to the GS
inhibitor, methionine sulfoximine (MSX), resulted in a rapid switch
from net uptake to net excretion of ammonia. Further
experiments are underway to investigate the effect of MSX on
15
N-ammonia assimilation and symbiont GS expression.
350
Sulfide-mediated thiosulfate production in mussel gills.
DOELLER, J.E.', D.W. KRAUS, and M.K. GRIESHABER. Univ. of
Alabama at Birmingham and Heinrich Heine Univ. of Duesseldorf,
Germany.
Mutualistic symbioses between two partners are complex
associations that are regulated by the genetic interactions of the
partners. One such mutualism is that between the sea anemone
Anthopleura elegantissima and its dinoflagellate symbiont. We
have been interested in characterizing genes that are expressed
as a function of the symbiotic state. We constructed a
subtracted 'symbiosis' cDNA library from anemone RNA and
have identified a cDNA sequence that is highly expressed in
symbiotic anemone RNA but is virtually absent from
aposymbiotic anemone transcript. The deduced amino acid
sequence has a high sequence identity to the enzyme
glyceraldehyde-3-phosphate dehydrogenase (GAPD). The
sequence most closely aligns with GAPDs from dinoflagellate
chloroplasts. Southern blots of symbiotic and aposymbiotic host
DNA, using a highly specific probe designed from the sequence,
labeled a strong band in symbiotic DNA but none in
aposymbiotic DNA. This suggests that the GAPD DNA has been
horizontally transferred from the dinoflagellate symbiont to host
cells. This is the first report of gene transfer in a cnidarian-algal
mutualism and gives us a glimpse at the complexity of the
genetic regulation of these associations.
Gills of the sulfide-tolerant ribbed mussel Geukensia demissa
exhibit sulfide-stimulated oxygen consumption rate (nO2) and
ciliary beat frequency (CBF), with a drop in the CBF/nO2 ratio
that is quantitatively consistent with the use of sulfide as
respiratory substrate as seen in isolated gill mitochondria.
Thiosulfate is the major thiol compound produced by the gills
after exposure to sulfide, with sulfite exhibiting a minor increase.
Tissue levels of the other thiol compounds glutathione and
cysteine as well as sulfide remain constant throughout a 50
minute exposure to sulfide. Mitochondrial complex III inhibitors
do not decrease sulfide-stimulated nO2 or thiosulfate production
but both cyanide and SHAM, terminal oxidase inhibitors, limit
both processes, indicating that electrons from sulfide oxidation
are conducted to one or more terminal oxidases downstream
from complex III. Supported by NSF IBN9728408.
348
Egg production substantially increases resting metabolic
rate.
VEZINA, F.* and T.D. WILLIAMS. Simon Fraser Univ., Bumaby,
Canada.
Confirmation of the production of the symbiosome
membrane by both symbiont and host cell.
WAKEFIELD, T.S.* and S.C. KEMPF. Auburn Univ., AL.
Endosymbionts and their surrounding membranes have been
dubbed 'symbiosomes'. The boundary layer between the host
cell and the symbiont is the symbiosome membrane. All cell to
cell communication between the host and the symbiont must
occur through this layer. Thus information on the origin and
molecular structure of this layer is critical. In many
dinoflagellate/cnidarian symbioses the symbiosome membrane
consists of many layers of apparent membranes. This condition
is evident in the association between Aiptasia pallida and its
symbiont Symbiodinium bermudense. The origin of these
membranes has been attributed to the host symbiont and to
ABSTRACTS
351
Energetic costs of egg production are poorly understood in
birds. Most studies have been based simply on the energy
content of eggs or clutches and little is known about additional
physiological costs, e.g. energy expenditure for nutrient transport
and/or uptake, yolk precursor synthesis, or maintenance cost(s)
of reproductive organs. We measured resting metabolic rate
(RMR) of free living European starlings (Sturnus vulgaris) in nonlaying (March) and egg producing (1 -egg stage, May-June)
females. We compared these data with RMR of chick-rearing
birds (when energy expenditure is presumed to be highest). RMR
was substantially higher (two-fold) in laying birds compared with
non-laying females, and was also significantly higher than in
chick-rearing birds. In laying females, RMR was independent of
59A
Anthopleura elegantissima is facultatively symbiotic with
photosynthetic algae and occurs in nature either with or without
symbionts. This species forms symbiotic associations with two
genera of algae, Symbiodinium (=zooxanthellae) and Chlorella
(=zoochlorellae). The presence of symbionts affects host gene
expression and protein synthesis; upregulated genes and
proteins are likely involved in regulating the symbiotic interaction.
One of the most abundant symbiosis proteins, sym32, belongs
to the Fas-I family of cell adhesion proteins. We examined
differential synthesis of sym32 using Western analysis and
localized the sym32 protein within host tissue using
immunocytochemistry. Sym32 synthesis is affected by the
presence and type of symbiont: zooxanthellate anemones
contain much more sym32 than do zoochlorellate anemones,
and nonsymbiotic anemones contain very little sym32. There is
also a differential distribution of sym32: nonsymbiotic anemones
contain roughly equal amounts of sym32 in endoderm and
ectoderm, while symbiotic anemones contain more sym32 in the
endoderm, where symbionts are housed, than in the ectoderm,
which is free of symbionts.
both by various authors. As to date no evidence has been
presented to confirm any of these proposed origins. Using
extracted symbiosomes as a source of antigen two monoclonal
antibodies were produced an IgG and an IgM both of which
show positive binding to the symbiosome membrane in
immunofluorescent studies. Utilizing nanogold conjugated
antibodies and the TEM we have demonstrated that the multiple
layers of membranes closest to the symbiont are of symbiont
origin while only the outer most membrane is supplied by the
host.
body composition (residual organ masses) but was positively
correlated with plasma levels of the yolk precursor vitellogenin (r
= 0.69). This suggest that physiological adjustments associated
with egg production may be substantial and cause the elevation
in RMR.
352
Interaction of oxygen tension and temperature on insect
development.
FRAZIER, M.R. Arizona State Univ., Tempe.
353
Body size effects on gas exchange capacities of primary
trachea of the American locust.
HARRISON, J.F.*, J.J. LAFRENIERE, and K.J. QREENLEE.
Arizona State Univ., Tempe.
Recent reviews have suggested that atmospheric oxygen
levels may be causally linked to historical variation in insect body
size; however, there have been no empirical studies of how
tracheal morphology varies with size in insects. We examined the
effect of ontogenetic changes in body size on the morphology of
the primary transverse trachea of the American locust,
Schistocerca americana. Tracheal diffusive conductances
calculated from morphology increased with a lower slope than
resting oxygen consumption with size. The calculated partial
pressure drop for oxygen across these trachea assuming
completely diffusive gas exchange was minimal (< 1 kPa) in 10
mg 1 st instars, but increased linearly with size to 10 kPa in
adults. These data are consistent with the hypothesis that
diffusion can supply the oxygen needs of small but not large
grasshoppers. Calculated pressure gradients necessary to
achieve gas exchange completely by convection were in the
range (< 1 kPa) measured empirically for adults, and did not vary
with size. This research was supported by NSF grant IBN
972844 to JFH.
354
Effects of hypoxia/hypercapnia on blue crab.Callinectes
sapidus in the York River, VA.
DEFUR, P. L* and S. R. Hypes. Virginia Commonwealth Univ.,
Richmond.
This research examined effects of hypoxic environments on
blue crabs, Callinectes sapidus in an estuarine environment.
Hypoxic conditions were treated as a multiple stressor involving
low dissolved oxygen (D.O.), increased carbon dioxide
(hypercapnia), and low pH concurrently. The objectives were to:
1) identify hypoxia/hypercapnia by monitoring D.O. and pH as an
indicator of hypercapnia in shallow regions of the York River 2)
measure blue crab abundance 3) describe blue crab responses
to hypoxia/hypercapnia via field work at Taskinas Creek and lab
measurements of respiration. Ambient D.O. and pH were
positively correlated in the Taskinas Creek and York River sites
during 07/98-09/98 (r= .74). Results confirm concurrent
hypoxia/hypercapnia in this estuary. It was concluded that
60A
355
Effect of Cu/Zn-Superoxide dismutase overexpression on
metabolic rate in Drosophila melanogaster.
FOLK, D.G.*, J. SUN, J. TOWER, and T.J. BRADLEY. Univ. of
California, Irvine, and Univ. of Southern Calif., Los Angeles.
We employed yeast FLP recombinase, the expression of
which was driven by a heat-inducible hsp 70 promotor, in a
binary transgenic system ('FLP-OUT') to test the effect of Cu/Znsuperoxide dismutase overexpression on metabolic rate in
Drosophila melanogaster. Young adults treated with 2 heat
pulses (90 min each), overexpressed Cu/ZnSOD for the
remainder of life. Overexpression of Cu/ZnSOD has been shown
to increase lifespan in our transgenic lines. To determine if
reduction in metabolic rate leads to the increased longevity
associated with SOD overexpression, we measured oxygen
consumption in heat-pulsed and non-heat pulsed (control) flies
from two distinct Cu/ZnSOD transgenic lines. Identical
measurements were made on Oregon R flies, which lack
constructs, to examine the effects of heat pulses alone. Our
results show that all heat pulsed populations have reduced
metabolic rates, but these are not statistically significant. Our
results suggest that increased longevity associated with
overexpression of Cu/ZnSOD cannot be explained by a lowering
of metabolic rate, but must be due to other effects of
Cu/ZnSOD. Supported by NIH grant AG11644 to J.T. and NSF
grant IBN9723404 to T.J.B.
356
Analysis of quantitative trait loci affecting metabolic traits in
Drosophila melanogaster.
MONTOOTH, K.L.*, J.H. MARDEN, and A.G. CLARK.
Pennsylvania State Univ., Univ. Park.
The maintenance of efficient metabolism requires the
coordinated regulation of the many enzymes involved in the
metabolic pathways. Analysis of suites of functionally related
characters by QTL mapping provides a powerful means of
identifying factors responsible for this coordinated regulation. In
this study we find an abundance of variation in metabolic rate,
11 metabolic enzyme activities, and two metabolite storage pool
concentrations among genetic lines of Drosophila melanogaster.
Variation in activity for the 11 metabolic enzymes primarily maps
to regions of the genome that exclude the structural gene,
providing strong evidence for trans-regulation. We also find that
variation in multiple correlated traits, including metabolic rate,
maps to similar regions of the genome. Thus QTL mapping
suggests that pleiotropic effects of trans-regulators cause
correlations between metabolic traits. These putative transregulatory regions place important constraints on the evolution of
metabolic regulation. The association between these metabolic
traits and flight performance will also be discussed.
357
Cloning, sequencing and differential expression of alpha B
crystallin in the zebrafish Danio rerio.
POSNER, M.*, M. KANTOROW, and J. HORWITZ. Ashland Univ.,
OH, and Jules Stein Eye Institute, Los Angeles, CA.
Crystallins are a diverse group of proteins that make up over
90% of the soluble protein of the vertebrate eye lens. One of
these proteins, alpha crystallin, is a member of the small heat
shock protein family and functions as a molecular chaperone.
Whereas alpha crystallin has been extensively studied in
endothermic mammals, little is known about this protein in the
ectothermic bony fishes. Here we report the cloning and
expression of alpha B crystallin from the zebrafish. 5' and 3'
RACE was used to isolate a 900 bp transcript that contained
insertions and deletions that differentiated it from both alpha A
crystallin and HSP 27. The deduced amino acid sequence of
zebrafish alpha B crystallin revealed that it lacked 4 residues in
As temperature rises, the metabolic rate of animals usually
increases more rapidly than the diffusion rate of oxygen.
Consequently, we hypothesized that at higher temperatures
insects would be more sensitive to rearing atmospheric oxygen
levels than at lower temperatures. To test our hypothesis,
Drosophila melanogaster were reared from eggs to adult in
either 10%, 2 1 % , or 40% oxygen and at 15°C, 25°C, or 30"C.
Final adult size was measured as thorax length and wet mass. In
support of our hypothesis, there was a strong interaction
between the effects of rearing temperature and oxygen on body
size. At high temperatures, body size increased strongly with
increasing atmospheric oxygen levels, while at cool
temperatures, atmospheric oxygen effects on size were small or
nonexistant. In addition, females reared at 30°C in 40% oxygen
were larger than those reared at 21 % oxygen. This suggests that
normal atmospheric oxygen levels of 21 % may limit growth in
some conditions. The tendency for oxygen diffusion to increase
more slowly than metabolism with rising temperature may
partially explain why many insects have smaller body sizes at
higher temperatures. This research was supported by NSF grant
IBN 972844 to JF Harrison.
hemolymph blood lactate concentration was not considered a
good in situ biomarker for exposure to hypoxic/hypercapnic
conditions. Oxygen uptake was not significantly different
between normoxic and hypoxic conditions but was significantly
affected by pH. Research supported by VCU Center for
Environmental Studies and CBNERRVA.
the C-terminus implicated in protein-protein interactions in other
vertebrate species. In addition, the sequence contained two
substitutions at sites implicated in phosphorylation in other
vertebrate species. Northern analysis and semi-quantitative RTPCR indicated that zebrafish alpha B crystallin is expressed at
extremely low levels outside of the lens, unlike its mammalian
orthologue.
interspecific differences, our results cast doubt on the notion
that hummingbirds can vary degree of ammonotely with water
flux rate. Our study also allowed calculation of nitrogen
requirements, which were similar for all three species and
comparable to previously reported values for hummingbirds.
358
A new method for quantifying oxygen diffusion distance
within spongy myocardium of hearts.
O'BRIEN, K.M.' and B.D. SIDELL Univ. of Maine, Orono.
Myofibrillar protein composition in regenerating claw closer
muscle of the yabby, an Australian freshwater crayfish.
PATAK, A*, L CUTLER, and J.M. WEST. Edith Cowan Univ.,
Perth, Australia, and Monash Univ., Clayton, Australia.
We developed a stereologically-based method for quantifying
oxygen diffusion distance within spongy myocardium of three
species of Antarctic fishes that vary in expression of oxygenbinding proteins. Using this method, we compared hearts from a
red-blooded species, Gobionotothen gibberifrons whose
ventricle has myoglobin (Mb), and hearts from two species of
icefish that lack hemoglobin (Hb) and vary in expression of
cardiac myoglobin; Chionodraco rastrospinosus expresses Mb,
Chaenocephalus aceratus does not. Average oxygen diffusion
distance within heart ventricular tissue is greater in red-blooded
teleosts (9.82um ± 1.37) compared to icefish (C. rastrospinosus,
6.20um ± 0.86; C. aceratus, 6.23um ± 0.41). Mean diffusion
distance between lumenal boundary of tissue and mitochondria
parallels this trend because mitochondria are uniformly
distributed within cardiac muscle of these fishes. These results
indicate that loss of Hb, but not Mb, is correlated with an
increase in the degree of trabeculation of heart ventricle in
icefish. Support provided by NSF grant OPP-94-21657.
Topic in Integrative and Regulatory
Biology
359
The effects of alpha-tocopherol on mammalian torpor.
FRANK, C.L.* and A.G. GIBBS. Fordham Univ., Armonk, NY, and
Univ. of Arizona, Tucson.
Tocopherols (Vitamin E) are antioxidants that intercept the
reactive oxygen species responsible for lipid peroxidation. Plants
produce four tocopherol isomers, with alpha-tocopherol being
the most biologically active. All mammals require tocopherols in
their diets. Field and laboratory studies were conducted to
determine the influence of diet alpha-tocopherol content on
torpor by ground squirrels Spermophilus lateralis . The diets of
free-ranging ground squirrels contained both alpha and gammatocopherols, and alpha-tocopherol was most abundant. Natural
diet alpha-tocopherol levels ranged from 1.5 to 35.1 ug/g.
Laboratory experiments, however, revealed that squirrels fed
diets with alpha-tocopherol contents above or below 12 ug/g: 1)
were less likely to enter torpor, 2) were less likely to survive
torpor, and, 3) maintained higher body temperatures during
torpor than those fed a diet containing 12 ug alpha-tocopherol/g.
A low alpha-tocopherol diet is thus actually required for proper
torpor.
360
Ammonotely and nitrogen excretion in three sympatric
hummingbird species.
MCWHORTER, T.J.*, D.R. POWERS, and N. MILLER. Univ. of
Arizona, Tucson, George Fox Univ., Newberg, OR, and Linfield
College, McMinnville, OR.
When hummingbirds encounter low ambient temperatures or
energy-dilute floral nectars, they must consume food at
exceedingly high rates to meet energetic demands. Under these
conditions, they often experience water flux rates more similar to
freshwater fish or amphibians than to terrestrial vertebrates. It
has been suggested that under some conditions, hummingbirds
may be facultatively ammonotelic. We examined nitrogen
excretion in three sympatric hummingbird species in
southeastern Arizona (firchilochus alexandri, Eugenes fulgens,
Lampomis clemenciae). Archilochus excreted roughly equal
amounts of nitrogen as ammonia and uric acid, whereas the
other two species excreted nitrogen primarily as uric acid.
Proportion of nitrogen excreted as ammonia did not vary with
water flux or nitrogen intake rates. Although we found intriguing
ABSTRACTS
362
Insulin's counter-regulatory hormones: Catabolic and
growth-inhibitory actions in an alternative, teleost fish model
of insulin-dependent diabetes mellitus (IDDM).
HAIGWOOD, J.T.*, R.M. FLORES, and K.M. KELLEY. California
State Univ. at Long Beach.
The isletectomized (Ix) goby, Gillichthys mirabilis, provides for
the only experimental model of IDDM in which pancreatic
glucagon is removed simultaneously with insulin, allowing for
studies on the diabetogenic effects of exogenously administered
counter-regulatory factors (e.g., glucagon, cortisol) without the
interfering effects of endogenously produced glucagon. In
contrast to other models of IDDM, the onset of hyperglycemia
and other diabetic symptoms in the Ix goby is delayed for up to
15 d after the removal of insulin. This difference may be
accounted for by the simultaneous absence of glucagon, since
exogenous glucagon treatment induces a full-blown diabetic
symptomatology in these animals. Cortisol also exhibits
significant diabetogenic actions. Glucagon and cortisol appear to
have important growth-inhibitory influences as well, as they
reduce tissue growth activity (cartilage 35S-proteoglycan
synthesis) and cause hypothesized growth-inhibitory changes in
circulating levels of IGFBPs. (Support by NSF grant
IBN9600783).
363
Insulin-regulated glucose transporters in an ectothermic
vertebrate: Studies in the diabetic goby Gillichthys mirabilis.
NICHOLSON, G.S.*, V.P. DESAI, and K.M. KELLEY. California
State Univ. at Long Beach.
In mammals, insulin stimulates the translocation of
intracellular vesicles containing Glut4 glucose transporters from
the frans-Golgi area to the plasma membrane where they are
active. In ectotherms, the degree to which this metabolic
regulatory apparatus is similar, if it exists at all, is not known. As
in mammals, in vitro insulin treatment of goby muscle results in
stimulated transport of 14C-2-deoxyglucose; however, the
increase is <20% that of rat tissues under similar conditions. In
untreated diabetic gobies, muscle glucose transport becomes
resistant to insulin action in vitro, while insulin replacement
61A
Regeneration of the chelae has been studied in the yabby,
Cherax destructor by characterising the ultrastructure, sarcomere
length, myofibrillar protein composition and activation properties
of the fibres at different stages of limb formation. Pristine chelae
of the yabby are symmetrical and are composed of two major
fibre types (Fast and Slow S2) that have greatly different
sarcomere lengths and unique myofibrillar protein assemblages.
Fast fibres differed from slow fibres by a paramyosin isoform
(105K), a 75K unidentified protein and in the isoforms of troponin
I and T. Papillae contained large amounts of an 88K protein,
possibly a haemolymph protein while most of the major
myofibrillar proteins from pristine muscle fibres were absent.
Muscle fibres isolated from fully segmented but non-functional
regenerating chelae (dactyl fused to propus) expressed all
protein isoforms observed in fast and slow pristine fibres. These
fibres resembled fast muscle in their ultrastructure but had
atypically long sarcomere lengths. The activation profiles showed
that the muscle fibres are functional before the chelae become
operational.
361
therapy of the diabetic goby restores this response to normal,
comparable to the situation in mammals in which the Glut4
transporter gene is down-regulated with insulin deficiency.
Purified goby muscle plasma membranes specifically bind the
competitive inhibitor of glucose transporters, 3H-cytochalaisin-B,
which may be due to a 45-50 kDa protein. These data indicate
that an insulin-regulated cellular glucose transport system exists
in an ectotherm that is comparable to the mammalian Glut4
system. (Supported by NSF grant #IBN9600783).
membrane-bound IGFBP in high concentrations relative to that in
the medium. Interestingly, addition of IGF-I or -II during cell
culture removes the IGFBP from its cell membrane site(s) and
releases it into the medium. This effect, unknown in mammalian
cell systems, occurs in less than 5 min of the addition of IGF. It
is hypothesized that this IGFBP may have an inhibitory role, as it
appears to bind IGF peptide followed immediately by removal of
the IGF/IGFBP complex from proximity to the cellular IGF
receptor. (Supported by NSF grant #IBN-9600783).
364
367
Glucose regulates somatostatin gene expression in rainbow
trout.
EHRMAN, M.M.*, G. MELROE, J.D. KITTILSON, and M.A.
SHERIDAN. North Dakota State Univ., Fargo.
Effects of endothelin-1 and homologous trout endothelin on
cardiovascular function in raindbow trout.
HOAGLAND, T.M.' and K. R. OLSON. Univ. of Notre Dame, IN.
365
Cell membrane association of IGF-binding proteins (IGFBPs)
in vertebrates: Mechanisms and regulatory roles.
KELLEY, K.M.*, P. DESAI, K.E. SCHMIDT, and G.S.
NICHOLSON. California State Univ. at Long Beach.
IGFBPs are multifunctional proteins that are not simply
carriers for IGF peptides, but that also act as important
regulatory factors at the cell membrane level. To varying
degrees, each of the six primary mammalian IGFBPs exhibits
direct cell membrane interaction, including a specific property of
binding with membrane proteins and/or extracellular matrix
(ECM). This interaction, which has not been studied in other
vertebrates, has the potential either to promote or inhibit IGF
receptor activation, depending on the properties of the
IGF/IGFBP complex when it is bound to the membrane. In the
mouse, binding of IGFBP-2 to ECM components on kidney cells
reduces its affinity and potentiates IGF action. In a reptile, a
membrane-associated 30 kDa IGFBP appears to inhibit IGF
action by acutely removing IGF from the surface of heart cells. In
two teleost fish species, IGFBP membrane association has also
been demonstrated, suggesting that membrane association is a
fundamental property of IGFBPs through the vertebrates.
(Supported by NSF grant IBN-9600783).
366
Cell membrane localization of a non-mammalian insulin-like
growth factor-binding protein (IGFBP) and its regulation by
IGF.
SCHMIDT, K.E.*, P. DESAI, and K.M. KELLEY. California State
Univ. at Long Beach.
Development of the functional roles of IGFBPs, particularly at
the cellular level, during vertebrate evolution is not understood. A
cell line derived from the heart of the lizard, Iguana iguana,
expresses a single IGFBP of 30 kDa and provides for an
experimental system to study the cell physiology of a reptilian
iGFBP. The Iguana IGFBP binds ' J5 I-IGF-I and -II in a specific
manner, in that IGF-I and -II effectively compete for ligand
binding while insulin and growth hormone do not. Affinity crosslinking of ceil monolayers demonstrates the presence of cell
62A
The cardiovascular effects of endothelin-1 (ET-1) and the
recently sequenced homologous trout endothelin (tET) were
examined in unanesthetized trout and vascular capacitance
curves were constructed to evaluate the responsiveness of the
venous system to ET-1. Bolus doses of ET-1 increased ventral
aortic pressure produced a triphasic pressor-depressor-pressor
response in dorsal aortic pressure increased central venous
pressure gill resistance and systemic resistance and decreased
cardiac output heart rate and stroke volume. These responses
were dose-dependent. Bolus injection of tET produced
essentially identical dose-dependent cardiovascular responses
as ET-1. Infusion of 1 picomol·kg"1·min"1 ET-1
decreased vascular compliance but had no effect on unstressed
blood volume. These results show that endothelins affect a
variety of cardiovascular functions in trout and that branchial
vascular resistance and venous compliance are especially
sensitive. The multiplicity of effectors stimulated by endothelin
suggests that this peptide was extensively integrated into
cardiovascular function early on in vertebrate phylogeny.
Acknowledgments: NSF IBN-9723306.
368
Seasonal variation in yolk hormone levels and pivotaltemperature sex ratios in a turtle with TSD.
BOWDEN, R.M.*, M.A. EWERT, and C.E. NELSON. Indiana Univ.,
Bloomington.
We incubated eggs of Chrysemys picta, a turtle with
temperature-dependent sex determination, at 28 °C, the constant
temperature that yields a 1:1 sex ratio (pivotal temperature). In
each of five years, sex ratios at 28 °C shifted toward more
females as the nesting season advanced. In 1998, we used a
competitive-binding RIA to assess levels of endogenous
estradiol and testosterone in yolks from eggs frozen shortly after
oviposition. Levels of yolk estradiol increased significantly and
levels of testosterone decreased significantly with progression of
nesting season. The ratio of estradiol to testosterone (and
estradiol alone) was significantly associated with sex ratios from
hatchlings from the same clutches. These results provide a
mechanism for matching sex to time of hatching and phenotype
to sex.
369
Female kestrels hormonally regulate the survival of their
offspring.
SOCKMAN, K.W.*, and H. SCHWABL. Washington State Univ.,
Pullman.
Parental favoritism or discrimination enables some offspring
to out-compete their siblings and thus the parents to cull a
brood too large for available resources. Female birds bestow
yolks of eggs with variable quantities of androgen hormones,
and, in canaries (Serinus canan'a), these yolk androgens enhance
begging vigor and growth rate of nestlings. Comparative studies
were necessary to test if this function of yolk androgens applies
to wild birds potentially contending with limited food availability.
We measured the concentrations of androgens in yolks of freeliving American kestrels (Fa/co sparverius) and then manipulated
these concentrations to determine how they affect nestling
growth and mortality. We found that concentrations of yolk
androgens were higher in later- than in first-laid eggs of a clutch
and that high concentrations of yolk androgens delayed hatching
and reduced growth and survival rates of nestlings. This function
We previously characterized two cDNAs that encode for
distinct preprosomatostatins containing (Tyr7, Gly 10 ]somatostatin-14 (PPSS II' and PPSS II) and found that these
cDNAs were differentially expressed in the pancreas of rainbow
trout. In this study we examined the control of PPSS II
expression. Fish injected with glucose had 3-fold higher levels of
PPSS II mRNAs compared to control animals. Glucose
stimulated the expression of both PPSS II mRNAs in vitro in a
dose-dependent manner; however glucose was a more potent
stimulator of PPSS II"" than of PPSS II.' Mannose galactose and
fructose also induced the expression of PPSS II mRNAs whereas
sucrose 3-O-methylglucose and 2-deoxyglucose were without
effect. PPSS II mRNA levels were stimulated by dihydoxyacetone
and pyruvate but were inhibited by iodoacetate an inhibitor of
glycolysis. Finally glucose-stimulated PPSS II expression was
inhibited by actinomycin. These results indicate that the
expression of PPSS II mRNAs in the pancreas of trout is
regulated by glucose and suggest that glucose-stimulated
expression of PPSS II mRNAs requires the uptake and
subsequent metabolism of the sugar.""
is opposite of that in canaries and may facilitate brood reduction
when parents are faced with limited resources. Such 'transgenerational' hormone effects may have helped shaped the
hormonal regulation of reproduction.
370
The relationship between yolk testosterone concentration
and Complexus mass in nestling red-winged blackbirds.
LIPAR, J.L/ and E.D. KETTERSON. Indiana Univ., Bloomington.
371
Extended phenotypic effects of elevated testosterone in
male dark-eyed juncos: Female mates produce smaller eggs,
but do not alter yolk steroid concentrations or primary sex
ratio.
CASTO, J.M.', J.L. LIPAR, C.A. BUERKLE, J. GRINDSTAFF, V.
NOLAN, JR., and E.D. KETTERSON. Indiana Univ., Bloomington.
Male juncos (Junco hyemalis) with artificially elevated levels
of testosterone (T) are more attractive to females, but provide
less parental care than control males. We tested whether female
juncos would alter investment in eggs in response to the
hormonal condition of their social mates. In particular we
assessed whether mates of T-treated males would alter the size
of their eggs or the concentration of steroid hormones (T,
estradiol, and progesterone) in the yolks. We also tested whether
females would alter the primary sex ratio in response to Ttreatment. Our findings suggest that length, breadth, and mass
of junco eggs increase with laying order as do concentrations of
T and progesterone, but not of estradiol. Females mated to Ttreated males produce eggs that are not as broad and heavy as
eggs of females mated to controls; however, yolk steroid
concentrations and the primary sex ratio are not influenced by
the treatment of the social mate.
372
Role of the adrenal gland in early post-hatching
differentiation of alternative male phenotypes in the tree
lizard (Urosaurus omatus).
JENNINGS, D.J.*, D.L PAINTER, and M.C. MOORE. Arizona
State Univ., Tempe.
During development sex steroids mediate development of
differences between males and females. Sex steroids may also
regulate the production of individual differences in morphology
and behavior within a sex. Males of the tree lizard, Urosaurus
ornatus, exhibit alternative reproductive tactics correlated with
dewlap coloration. Recent work suggests that progesterone (P)
and testosterone (T) secreted during early development mediate
male morph development. The current work uses tissue
incubation to determine the source of these hormones during
early post-hatching development. Gonadal incubations had
quantifiable levels of T while adrenal incubations primarily
contained P. A second source of steroid hormones during
development is from maternal provisioning of steroids in yolk.
Both T and P are present in yolk of newly oviposited eggs and in
yolk collected from embyros just prior to hatching, but at very
low levels. Our results suggest that hatchling gonads and
ABSTRACTS
373
Development of the endocrine stress axis in Xenopus laevis.
GLENNEMEIER, K.S.* and R.A. DENVER. Univ. of Michigan, Ann
Arbor.
Characterization of the endocrine stress response in
developing amphibians has been problematic due to the
difficulty of collecting blood from small tadpoles. Here, we have
characterized the development of the endocrine stress axis in
Xenopus laevis, using several techniques. We extracted whole
tadpoles of different developmental stages and determined
corticosterone content using radioimmunoassay. We also
determined the responsiveness of the axis over development by
measuring changes in corticosterone content after ACTH
injection and confinement stress. Whole body corticosterone
content decreased as tadpoles progressed from pre- to
prometamorphosis. ACTH injection and confinement stress
caused a 2-to-3-fold increase in corticosterone content at all
stages examined. To characterize further the development of the
stress axis, we currently are determining the ability of interrenal
tissue to synthesize various corticosteroids from radiolabeled
precursor. Kidneys are incubated with 3H-progesterone and the
extracted medium analyzed using thin layer chromatography
(TLC) and high performance liquid chromatography (HPLC) to
identify the corticosteroids produced. Funded by a grant from
the Ml Great Lakes Protection Fund
374
Analysis of neuroendocrine gene expression during
environmentally-induced metamorphosis in the Western
Spadefoot Toad [Scaphiopus hammondii).
BOORSE, G.C.* and R.J. DENVER. Univ. of Michigan, Ann Arbor.
Plasticity in the timing of metamorphosis allows amphibians
to respond adaptively to changes in their larval habitat. S.
hammondii tadpoles respond to water volume reduction in the
lab by accelerating metamorphosis. Corticotropin-releasing
hormone (CRH) may mediate environmental effects on
metamorphosis. To study the early neuroendocrine events
involved in metamorphic acceleration S. hammondii tadpoles
were raised in a constant high water environment to late
prometamorphosis and then transferred to either low or high
water. By 24 hours, tadpoles transferred to low water exhibited
decreased body weight, decreased tail height and longer hind
limbs. Electrophoretic mobility shift assays were used to detect
changes in DNA binding activity for transcription factors thought
to regulate the CRH gene. No changes in binding were detected
for the cAMP-response element (CRE) or activator protein-1 (AP1) at the earliest post-transfer timepoint (2 hr). Further analysis of
the hypothalamic early response genes by gene expression
screening is currently underway. Supported by NSF grant IBN
9974672 to RJD and NSF Predoctoral fellowship to GCB.
375
Biochemical characterization and expression analysis of the
Xenopus laevis corticotropin-releasing hormone binding
protein.
VALVERDE, R.A.* and R. J. DENVER. Univ. of Michigan, Ann
Arbor.
Corticotropin-releasing hormone (CRH) is thought to play a
key role in regulating amphibian metamorphosis. A secreted
binding protein with high affinity for CRH (CRHBP) has been
reported in mammals. Here we describe the biochemical
characterization and expression analysis of a CRHBP from an
amphibian, Xenopus laevis. Competitive binding assays
established that the affinity of xCRHBP for CRH-like peptides is
highest for urotensin I and lowest for oCRH, and that the protein
binds xCRH with high affinity. Northern blot analysis showed that
xCRHBP mRNA is expressed in brain, intestine and tail of
prometamorphic tadpoles. xCRHBP expression in brain shows
little change during metamorphosis; whereas expression in tail is
dramatically increased at metamorphic climax. The high affinity
of the xCRHBP for CRH-like peptides and its expression pattern
63A
Yolk testosterone concentration increases with laying order
in clutches of the red-winged blackbird, Agelaius phoeniceus.
The musculus complexus, located dorsally in the neck, provides
the force necessary for the breaking of the shell during hatching
and for the dorsal flexion and extension of the neck during
begging. We investigated the relationship between yolk
testosterone concentration and the mass of the complexus by
taking yolk samples from viable eggs and allowing them to
hatch. Complexus mass increased with laying order in both
newly-hatched and three-day-old nestlings. Testosterone
concentration was positively correlated with complexus mass at
both ages. The elevation of yolk testosterone via direct injection
resulted in an increased complexus mass. Similarly, the injection
of flutamide, an anti-androgen, into eggs resulted in a decreased
complexus mass. Because a larger complexus may translate into
either a shorter hatching span or an increased ability to beg,
these results suggest that a mechanism to mitigate the
detrimental effects of hatching asynchrony on last-hatched
young may be in effect.
adrenals are the primary sources of T and P and that both
glands play an important role in the development of alternative
male phenotypes in tree lizards.
during metamorphosis suggests that the protein can modulate
CRH bioavailability and thus serve as a regulatory factor of
metamorphosis. (Supported by NSF grant IBN9724080 to RJD
and a minority postdoctoral fellowship from the University of
Michigan to RAV).
376
Corticosterone inhibits larval development in vivo, but
enhances T3-induced tail reabsorption in vitro in Xenopus
laevis.
YEHYA, N.* and T.B. HAYES. Univ. of California, Berkeley.
37?
Developmental changes in plasma T 4 and plasma and ocular
melatonin in larval and juvenile bullfrogs.
WRIGHT, M.L-, J.L. DUFFY, C.J. GUERTIN, M. SZATKOWSKI,
and C D . ALVES. College of Our Lady of the Elms, Chicopee,
MA.
Melatonin (ML), which influences metamorphic rate and can
directly inhibit the thyroid, may interact with T 4 in the control of
anuran metamorphosis. On an 18L:6D cycle, ML decreased in
the plasma at climax when T4 levels increased, unlike other T 4
modulators, which peak at climax. The relationship between T 4
and ML in Rana catesbeiana has been studied on other LD
cycles in larvae and metamorphosed froglets sacrificed at 7
intervals during the 24-hr day for plasma and eyes. The diurnal
rhythm of all hormones studied was different on 12L:12D and
6L:18D. Nevertheless, on both LD cycles T4 increased from
prometamorphosis to climax, and then decreased again in the
froglet. In contrast, plasma ML decreased at climax, then rose
again in the froglet to about twice the prometamorphic level. The
findings suggest that the decline in plasma ML is a constant
feature of climax and further indicate that ML may not give a
clear 'night' signal until after metamorphosis. (Supported by NSF
IBN9723858.)
378
Preliminary evaluations of the Hyperolius argus estrogen
screen.
NORIEGA, N.C.* and T.B. HAYES. Univ. of California, Berkeley.
Juvenile Hyperolius argus develop premature adult female
coloration (PFC) when exposed as larvae to estrogens . Induced
PFC has been proposed for use as an indicator in estrogen
screening assays. We assessed the effects of DDT and
phytoestrogens on H. argus coloration, and found o,p' isomers
of DDT congeners effective at inducing PFC at 2.8 uM whereas
phytoestrogen effects were small or non existent at 2.8 uM
(coumestrol, equol and genestein), 14 uM (quercetin), or 28 uM
(naringenin). We used a survey to test if the color morphologies
induced by chemical treatment could be consistently interpreted
by people given only photographic examples of the phenotypes
in question. Volunteers age six to 57 were able to distinguish,
64A
Division of Comparative Physiology &
Biochemistry
379
The effects of speed, load-carrying and incline on function of
the vastus lateralis during trotting in the horse.
MAGANA, S.A.*, D.F. HOYT, S.J. WICKLER, E.A. COGGER, and
A.A. BIEWENER. California State Polytechnic Univ., Pomona,
and Harvard Univ., Cambridge, MA.
The gastrocnemius functions relatively isometrically during
steady-state running on the level. We hypothesized that the
vastus lateralis, with its parallel fiber architecture, would shorten
more than the highly pennate gastrocnemius, that trotting up a
10% incline would require increased shortening, and carrying a
load (=19% of body mass) would not. Muscle length was
measured using sonomicrometry in five horses trotting on a
treadmill at speeds from 2.0 to 4.0 m/s. Total positive strain was
calculated from time intervals when the muscle shortened (from
10% to 70% of stance when extensor moments were developed
at the knee). Repeated measures ANOVA indicates that on the
level and when loaded the amount of strain is independent of
speed but on an incline there is a 44% increase in the amount of
strain as speed increases from 2.0 to 4.0 m/s. When loaded the
amount of strain is the same as on the level. On the level the
vastus shortens more than the gastrocnemius (10% vs 6%) but
most vastus shortening occurs when the knee is flexing and the
muscle-tendon unit is lengthening. Supported by NIH 1 S06
GM53933.
380
The effects of speed and incline on function of the gluteus
medius during trotting in the horse.
DE LA PAZ, K.L.*, D.F. HOYT, E.A. COGGER, and S.J.
WICKLER. California State Polytechnic Univ., Pomona.
Knee and ankle extensors function relatively isometrically
during running but these muscles are pennate and/or have long
tendons. We studied muscle function in the gluteus medius, a
paralleled-fibered, mono-articular hip extensor with short
tendons. Our hypothesis was that the gluteus medius would
track the movement of the hip more closely and strain would
increase with speed and with incline. Muscle length was
measured using sonomicrometry in a horse trotting on a
treadmill on the level and up a 10% incline at speeds from 2.5 to
4.5 m/s. Total average positive strain and the mean positive
strain rate were calculated from time intervals when the muscle
shortened during the initial 70% of stance (when EMGs indicated
the muscle was active). Mean positive strain rate increased with
speed on the incline (P=0.013) but not on the level. Total positive
strain on the incline was twice that on the level (ca. 5%). Even
though the gluteus is a parallel-fibered muscle with short
tendons, it functions relatively isometrically during trotting on the
level. Supported by NIH 1 S06 GM53933.
381
The effect of limb mass distribution on the energetic cost of
locomotion in the horse.
MCGUIRE, R.F.*, S.J. WICKLER, D.F. HOYT, and E.A. COGGER.
California State Polytechnic Univ., Pomona.
A previous study of three cursorial species of quadrupeds of
similar body mass and limb iength, but varying considerably in
limb structure, found no detectable differences in the cost of
locomotion. The authors concluded that most of the energy
expended in traveling at a constant speed is not used to
Corticosterone (CORT)-treatment accelerates larval
development in several anuran species. CORT inhibits
development in the African clawed frog Q(enopus laevis),
however. We examined whether X. laevis has a different
endocrine physiology compared to other species, or whether this
apparent difference in response to CORT is an artifact of
experimental conditions. We treated X. laevis larvae with 72 or
720 nM CORT over a range of stages (from N-F stages 50, 52,
54, 56, or 58 to stage 66). The higher dose inhibited in all
treatments. At 72 nM, CORT inhibited only at treatments initiated
at stage 50, and had no effect when administered at the later
stages. In a second study, stage 58 or 62 larvae were treated
individually with five doses of CORT (7.2, 34, 72, 340, or 720
nM). 720 nM CORT slowed development, but lower doses had
no effect. Further studies examined tail reabsorption in vitro:
CORT (7.2, 34, 72, 340, or 720 nM) alone had no effect.
However, when given with 10nM thyroid hormone (T3), all five
doses of CORT enhanced tail reabsorption. Thus, CORT can
enhance Tj-induced tail reabsorption in vitro, but may only
inhibit in vivo. This observation is in marked contrast with the
effect of CORT on other anuran species. Supported by NSF
grant # IBN-9513362 to Hayes and an HHMI Undergraduate
Research Grant to Yehya.
with < 5% error, animals that showed from animals that did not
show PFC. In summary, we showed that H. argus' color
response to chemical treatment can be used to evaluate the
potential for chemicals to mimic estrogen and that this color
response can be interpreted consistently. This work was
supported by a Howard Hughes Predoctoral Fellowship in
Biological Sciences and NSF grants IBN-9513362 and IBN9508996.
accelerate and decelerate the limbs. Similar studies of bipedal
and quadrupedal subjects in which the limb mass was altered
demonstrated a relationship between limb mass distribution and
energy costs. The present study measured the rate of oxygen
consumption and cost of transport in horses (n=6) running on the
treadmill at 3.5 and 6.0 m/s with mass equal to 0.62% of body
mass added either to the second phalanx or near the center of
mass. The use of externally applied loads has the advantage of
allowing limb mass to be altered in a system in which other
aspects of physiology that might influence cost of locomotion
are held constant. When 0.71 kg was added to each limb,
oxygen consumption increased by 7.48% at 3.5 m/s and 11.1%
at 6.0 m/s. Adding 2.84 kg to the center of mass had no
detectable affect. Supported by NIH 1 S06 GM53933.
382
The cantilever abilities of snakes.
ULLYWHITE, H.B.*, J.R. LAFRENTZ, Y.C. LIN, and M.C. TU.
Univ. of Florida, Gainesville, and National Taiwan Normal Univ.,
Taipei, Republic of China.
383
Hind limb forces during acceleration in wild turkeys.
ROBERTS, T.J.* and H.A. HUMPHREYS. Oregon State Univ.,
Corvallis.
385
Unusual osmolytes in deep-sea vestimentrferans,
gastropods, and echinoderms.
YIN, M.', H.R. PALMER, J.J. BEDFORD, A. FYFE-JOHNSON, F.
SANTOSO, J. SUKO, and P.H. YANCEY. Sarah Lawrence
College, Bronxville, NY, Univ. of Otago, New Zealand, and
Whitman College, Walla Walla, WA.
In shallow-water marine invertebrates, osmotic balance
depends on organic osmolytes, usually free amino acids such as
glycine, alanine, taurine. Recently we showed that muscles of
some deep-sea crustaceans, anemones, squid and bivalves are
dominated by trimethylamine oxide (Kelly and Yancey, Biol. Bull.
196:18, 1999). We have now examined other deep-sea
invertebrates. In vestimentiferan vestiment tissue, hydrothermalvent Riftia were dominated by hypotaurine (an antioxidant) and
cold-seep Lamellibrachia were dominated by N-methyltaurine (up
to 190 mmol/kg wet wt.), identified by HPLC and NMR. Muscles
of four sea cucumber, one sea urchin and two gastropod
species had high contents of scyllo-inositol (up to 90 mmol/kg
wet wt.), identified by HPLC and GC-MS. To our knowledge
none of these solutes have previously been reported at high
levels in any organism, and the inositol is the first major
carbohydrate osmolyte reported for a marine invertebrate. We
thank C. Fisher and G. Somero for samples. Supported by the
M.J. Murdock Charitable Trust and The University of Otago.
386
Carbonic anhydrase gene expression in the gills of the shore
crab during acclimation to low salinity.
GEHNRICH, S.*, C. BROOKS, D. WEIHRAUCH, D. TOWLE, and
R. HENRY. Salisbury State Univ., MD; Bates Coll., Lewiston, ME;
Lake Forest Coll., IL; Auburn Univ., AL; Mt. Desert Island Biol.
Lab, Salisbury Cove, ME.
Acceleration in running animals requires that the impulse of
accelerative horizontal ground reaction force is greater than the
decelerative (braking) impulse in a step. During maximal
accelerations humans are able to completely eliminate the
decelerative component of the horizontal ground reaction force
by leaning forward to keep the center of mass in line with the
accelerative ground reaction force. We hypothesized that turkeys
(Meleagris gallopavo) have a relatively limited ability to alter
posture during running, and that their accelerative performance
would be limited by an inability to eliminate braking forces. We
used high-speed video and force plate measurements to
determine ground reaction forces produced during accelerations
across a 10 meter track. Contrary to expectations, turkeys were
capable of producing purely accelerative horizontal ground
reaction forces during several steps of an acceleration. A
decrease in pelvic pitch angle, decrease in leg protraction angle,
and an increase in limb retraction angle appear to be important
for maintaining alignment between the center of mass and the
ground reaction force during acceleration.
The gills of the euryhaline shore crab, Carcinus maenus, are
a major site of ion uptake in low salinity. Carbonic anhydrase
(CA) generates intracellular bicarbonate and protons which are
exchanged for extracellular chloride and sodium. CA activity
increased ten-fold in posterior gills during acclimation to low
salinity, but anterior gill activity did not change. Using RT-PCR
we identified and sequenced cDNA for CA from the crab gill. The
crab enzyme contains the conserved amino acid residues found
in vertebrate CA (-50% homology). Semi-quantitative PCR
detected increased CA mRNA (compared to actin) in posterior
gills of crabs acclimated to low salinity, whereas anterior gills
showed no increase in CA mRNA. These results support the role
of CA in ion uptake by the gills of the shore crab, and the
predominant role of the posterior gills in ion regulation. Future
experiments will identify regulatory mechanisms involved in CA
gene expression. Supported by NSF (IBN-9807539) and Mt.
Desert Island Biological Lab.
384
387
Kinematics of turning in the lizard Basiliscus basiliscus.
KHAN, M. A.* and D. R. CARRIER. Univ. of Utah, Salt Lake City.
Effect of eyestalk ablation on salinity-mediated carbonic
anhydrase induction in three species of decapod
crustaceans.
HENRY, R.P.*, M. CAMPOVERDE, and D.W. BORST. Auburn
Univ., AL, Marymount College, N.Y., and Illinois State. Univ.,
Normal.
Relative location of the center of mass of a body can be
expected to influence the turning performance of terrestrial
vertebrates. To address this, we measured turning performance
and kinematics of the iguanid lizard, Basiliscus basiliscus, on a
narrow track with a 90o turn at mid-length. When running at high
speeds, successful turns were characterized by a stereotypic
pattern of limb support during both deceleration and
acceleration. Deceleration during these turns was associated
with support of both forelimbs in a bounding posture and by the
hindlimb on the inside of the turn. Usually the inside hind foot
ABSTRACTS
Carbonic anhydrase (CA) is induced 10-fold in gills of
euryhaline crustaceans in low salinity, but regulation of this
process is unknown. Recently, increases in methyl farnesoate
(MF) in low salinity were correlated to increased Na/K ATPase
activity. Eyestalk ablation (ESA) was used to increase MF in
crabs to study its effect on CA induction. In Carcinus maenas,
65A
We quantified the abilities of snakes to extend the anterior
body horizontally without support, and we evaluated data for 31
species representing five families. Generally, terrestrial snakes
exhibit rather uniform cantilever ability and can extend the body
30-50% of total body length. Arboreal species exhibit statistically
superior performance both within and among families, with some
species extending the body to more than 50% of total body
length. Extreme divergence of cantilever abilities occurs between
arboreal and aquatic species. Intraspecific comparisons also
show that juvenile snakes cantilever better than adults,
presumably due to a lower mass relative to body length.
Musculoskeletal features of the vertebral column are generally
conserved in evolutionary terms, thus possibly explaining the
generally uniform cantilever abilities in large numbers of snake
species. However, several modifications of vertebrae and
associated epaxial muscles appear to be related to cantilever
performance.
turned backwards, gripping the substrate, and appeared to aid in
deceleration by pulling on the substrate. Initial acceleration in the
new direction was produced primarily by the outside hindlimb.
Trials in which the animal did not follow this sequence of limb
support often produced unsuccessful turns. No trials were
observed in which a bounding-type deceleration was combined
with a bounding (both hindlimbs) acceleration. In animals such
as lizards, in which the center of mass is positioned close to the
pelvic girdle, rapid deceleration in a sharp turn may require
simultaneous support from both fore and hindlimbs.
ESA resulted in a 25% increase in CA activity in crabs
transferred from 33 to 10 ppt but not in crabs transferred from
33 to 28 ppt. Injection of lovastatin, an inhibitor of MF synthesis,
did not abolish normal CA induction. Preliminary results in
Callinectes sapidus indicate ESA caused a doubling and a 4-fold
increase in CA activity in crabs transferred from 35 to 15 or 28
ppt, respectively, vs controls. Slight increases in hemolymph MF
levels occurred in ESA treated blue crabs but not in controls.
ESA had no effect on CA activity in the stenohaline Cancer
irroratus. It appears ESA has a stimulatory effect on CA induction
that interacts additively with low salinity. However, this does not
appear to be a result of increases in MF. Supported by NSF IN
97-27835.
388
Immunolocalization of NaK-ATPase in the branchial cavity of
Homarus gammarus during the post-embryonnic
development.
LIGNOT, J.H.* and G. CHARMANTIER. Univ. of Montpellier II,
Paris, France.
389
An immunological analysis of the Na+,K+-ATPase protein in
the blue crab, Callinectes sapidus, during osmoregulation.
VERZI, M.P.* and D.L LOVETT. The College of New Jersey,
Ewing.
The specific activity of Na+,K+-ATPase (ATPase) in blue crab
gills increases when salinity decreases. This increase may occur
through synthesis of more enzyme and/or modification
(activation or deinhibition) of existing enzyme. Western blots of
crude homogenates and microsomal fractions of gills were
stained immunologically with murine antibody against chicken
ATPase a-5 subunit. Samples from crabs acclimated to high
salinity had a single 110 kda band. In samples from low-salinity
crabs, this band was considerably wider than in high-salinity
crabs; in samples from some low-salinity crabs, there appeared
to be two distinct bands (110 kda and 113 kda). Perhaps these
two bands represent two forms of ATPase. Thus, activity may be
modulated through modification of the enzyme. When gels were
stained for total protein, ATPase appeared to be the primary
protein present. Because of this, adjusting sample volume on the
basis of total protein in the homogenate was not effective in
standardizing differences in homogenate concentration.
Therefore, we have not been able to determine whether the
amount of ATPase present in the gill actually changes during the
acclimation response.
66A
Molecular characterization of the B-subunit of a V-type H + ATPase in gills of the euryhaline shore crab Carcinus
maenas.
WEIHFiAUCH, D.*, J.-H. LIGNOT, and D.W. TOWLE. Lake Forest
College, IL, and Univ. of Montpellier II, Paris, France.
Previous studies of gills in fishes and in Chinese crabs
Eriocheir sinensis have related active NaCI uptake at low
salinities with V-ATPase, which is localized in the apical
membrane of the epithelium. To explore the relation of V-ATPase
and NaCI uptake in C. maenas, we designed degenerate
oligonucleotide primers based on V-ATPase B-subunit
homologies. Using these primers, we amplified related
sequences in cDNA reverse transcribed from mRNA of C.
maenas and E.sinensis gills and employed the resulting PCR
products for sequencing reactions. Using the known partial
sequence and specific primers, we completed the entire cDNA
sequence, including a 489 amino acid ORF, from C. maenas.
Employing monoclonal antibodies against the yeast B-subunit,
the branchial V-ATPase of C. maenas was found throughout the
cytoplasmatic compartment. In contrast to our findings with E.
sinensis, semiquantitative PCR analysis of the V-ATPase in C.
maenas revealed a low expression in back gills and high
expression in front gills. Supported by NSF (IBN-9807539).
391
Antibodies to crayfish Ca pump and exchanger.
WHEATLY, M. G.\ Z. ZHANG, and L. M. STINER. Wright State
Univ., Dayton, OH.
The crayfish molting cycle is used to study gene expression
for membrane Ca translocating proteins specifically
Sarco/Endoplasmic Reticular or Plasma Membrane Ca ATPase
(SERCA, PMCA) and Na/Ca exchanger (NCX). Using PCR and
RACE we have cloned the complete cDNA sequences for
crayfish SERCA from cardiac (4495 bp) and axial skeletal muscle
(3856 bp), and partial sequences for crayfish kidney PMCA (2700
bp) and egg NCX (880 bp). Homologous antibodies are required
for immunohistochemistry. Oligo-peptide antigens (15 mers, two
each for SERCA, PMCA and NCX) were designed based on the
deduced amino acid sequence of hydrophilic loop regions. Each
peptide was conjugated to cationized BSA and injected into 2
rabbits. ELISA revealed high titer antisera (1:40,000 to 1: 100,000
dilutions) for all antigens except one NCX. Western analysis of
homogenized epithelia, isolated vesicles or protein has been
performed to confirm antibody specificity. Immunoblotting has
initially revealed multiple bands (typical of polyclonals), one of
which is of the expected size (120K). Further characterization
involves immunoprecipitation through conjugation of the
transporter+antibody with protein A sepharose. (NSF grant IBN
9603723).
392
Expression of sodium/proton exchanger (NHE) proteins in
the gills and kidneys of the little skate, Raja erinacea.
CHOE, K.P.*, B.P. WALL, and J.B. CLAIBORNE. Univ. of Florida,
Gainesville, Georgia Southern Univ., Statesboro, and Mount
Desert Island Biological Laboratory, Salisbury Cove, ME.
Fishes elevate bicarbonate in the blood to compensate for an
acidosis. This is accomplished by a net acid excretion at the
gills; the kidneys may be important in preventing the loss of
bicarbonate. Branchial acid excretion and renal bicarbonate
reabsorption are expected to take place via Na+/H+ exchangers.
To detect proteins similar to cloned NHE isoforms, gill and
kidney proteins were separated by SDS-PAGE and Western
blotted. Density centrifugation was used to prepare apical and
basolateral membrane vesicles in order to determine the location
of NHE isoform targeting. An antibody for NHE-1 bound to a
protein of 70 and 80 kDa in both gills and kidneys; the signal for
basolateral vesicles was dramatically greater than for the apical
vesicles indicating a polarized expression in the gill. A polyclonal
antibody for NHE-3 detected an 80 kDa protein in gills and a
92.4 kDa protein in kidneys. Thus, proteins with epitopes similar
to mammalian NHE-1 and 3 are expressed in the gills and
kidneys of the little skate. Further work will evaluate the
regulation of protein expression during hypercapnia.
The expression of NaK-ATPase was examined using
immunofluorescence and immunogold techniques, throughout
the postembryonnic development of Homarus gammarus and
after exposure to seawater (SW) and dilute seawater (DSW). This
study was aimed to ascertain the involvement of various tissues
from the branchial cavity (gills, epipodites and branchiostegites)
in the ontogeny of osmoregulation. A specific monoclonal
antibody IgGaS raised against the avian a-subunit of the NaKATPase was used. In thin sections, controls showed no specific
binding within gill, branchiostegite and epipodite epithelia.
Copious immunostaining was observed in the epipodites of
larvae (stages l-lll), postlarvae (stage IV) and juveniles held in SW
and DSW. In DSW, immunoreactivity was also observed along
the inner-side epithelium of the branchiostegites in postlarvae
and juveniles. Within the epipodite and branchiostegite
ionocytes, NaK-ATPase was localised along the basolateral
infolding systems. These results suggest that larvae already
possess osmoregulatory structures, but only in the epipodites.
After metamorphosis, the additional involvement of
branchiostegites in ion transport results in the slight hyperregulation displayed by postmetamorphic stages at low salinity.
390
393
396
Effect of external salinity on the regulation of NHE-like
proteins in the gills of mummichog (Fundulus heterclitus).
WALL, B.P.\ A.I. MORRISON-SHETLAR, and J.B. CLAIBORNE.
Georgia Southern Univ., Statesboro.
Ion regulation in developing tilapia {Oreochromis
mossambicus) larvae during seawater acclimation.
HWANG, R.D.', T.H. LEE, and P.P. HWANG. National Taiwan
Univ., National Chung-Hsing Univ., Taichung and Academia
Sinica, Taipei, Taiwan.
Current models for branchial acid excretion in freshwater
fishes include an electrogenic H+ pump with passive uptake of
Na+, while marine species are postulated to use an
electroneutral Na+/H+ exchanger (NHE). Using immunological
techniques, we have previously demonstrated the presence of a
NHE-like protein (NHE-1) in the gills of the freshwater adapted
mummichog. Our current investigations involve: 1) Detection of
other NHE-like protein isoforms and 2) If expression of NHE-like
proteins are modified during resporitory acidosis in both fresh
and seawater-adapted fish. Membrane proteins from control and
hypercapnic mummichogs were immunoblotted with antibodies
made to mammalian NHE-1 (aa 574-818) or NHE-3 (aa 528-648).
Preliminary results show an upregulation of NHE-1-like proteins
during acidosis in seawater adapted mummichogs, while no
increase in expression could be quantified in fish adapted to
freshwater. It remains to be determined if NHE-3-like proteins
are expressed in fresh or seawater adapted killiflsh. Funded by
N.S.F. Grant IBN-9808141 to J.B.C.
Screening of a cDNA library for Na+/H+ exchanger (NHE) in
the long-homed sculpin, Myoxocephalus octodecimspinosus.
GUNNING, D.L*, J.B. CLAIBORNE, and A.I. MORRISONSHETLAR. Georgia Southern Univ., Statesboro, and Mount
Desert Island Biological Laboratory, Salisbury Cove, ME.
Gills of fish are comparable to the lungs and kidneys of
mammals because they are used for respiration and the
elimination of toxic waste, which are important functions of acidbase regulation. The Na+/H+ exchanger (NHE) is a transport
protein that has been shown to be involved in ion regulation and
acid excretion. Recently, two NHE isoforms, an bNHE and an
NHE2 isoform have been cloned and sequenced from a single
RT-PCR product obtained from the gill tissue of the long-horned
sculpin using NHE degenerate primers. The goal of this study is
the use the partial product of an NHE2 sequence to screen a
sculpin gill cDNA library and isolate positive colonies containing
full-length or partial cDNA transcripts of NHE. Once the 3'
sequence data is obtained from the long-horned sculpin, we can
more conclusively identify which isoform is being expressed in
the gills. This will allow further determination as to the function of
the transport protein in the gill tissue. This will lead to a better
understanding of the cellular mechanisms behind acid-base
regulation, and may provide insight to the physiology of the
mammalian kidney and other organs.
395
Morphologies and functions of mitochondria-rich cells in
yolk-sac tilapia {Oreochromis mossambicus) larvae.
LIN, L. Y.*, and P. P. HWANG. National Defense Medical Center
and Academia Sinica, Taipei, Republic of China.
In the present study, distribution and morphological changes
of integumental MR cells of tilapia larvae were studied with
confocal laser scanning microscopy. Larval MR cells double
labeled with antibody against Na-K ATPase a subunit and Con-A
were identified to be located all over larval skin of head, buccal
cavity, yolk-sac membrane, trunk and tail. These numerous
extrabranchial MR cells may play a critical role in ion-regulation
before branchial MR cells fully develop. Based on the
morphologies of the apical openings labeled with con-A, different
types (wavy-convex and non-wavy-convex) of MR cells were
identified in the larval skin as in the gills of adult tilapia. Wavyconvex, appeared predominantly in the larvae acclimated to low
NaCI artificial fresh water, and this change occurred within 24
hours following transfer. Furthermore, non-wavy-convex became
the dominant type when ambient NaCI content increased. These
morphological alterations of MR cells correlated with ionic
composition of different milieus, indicating that these types of
cells may be responsible for specific ion transport function.
ABSTRACTS
397
Effects of environmental calcium levels on calcium balance
in tilapia {Oreochromis mossambicus) larvae.
LIN, H.C.*, M.Y. CHOU, F.I. LU, C.H. YANG, and P.P. HWANG.
Tunghai Univ., National Taiwan Univ., and Academia Sinica,
Taiwan, ROC.
Using different calcium concentrations as environmental
factor, we investigated calcium balance in tilapia larvae. In
addition, the methodology for calcium efflux in tilapia larvae was
established. Upon 48 hours after fertilization, eggs were
incubated respectively in 1 and 0.02 mM Ca 2+ artificial water for
8 days. Different stages of larvae showed a different sensitivity to
low Ca 2+ , and the body Ca 2+ content in low Ca 2+ group was
lower than that in the control group. Larvae in 0.02 mM group
had a lower Ca 2+ efflux, but they had a similar influx as the 1 mM
group. When fertilized eggs were incubated in 0.2 mM Ca 2 *
medium and transferred respectively to 1 and 0.02 mM artificial
water 0 or 3 days after hatching, both newly hatched and 3-dayold larvae from low-calcium medium had an increase in influx
and a decrease in efflux. Three-day-old larvae was faster to
modulate Ca 2+ balance.
398
Ammonotely in hummingbirds: A test of the water turnover
hypothesis.
BEUCHAT, C.A. Univ. of Arizona, Tucson.
Patterns of nitrogen excretion in vertebrates are thought to
reflect both phytogeny and environment. Ammonotely and
ureotely are thus typical of freshwater fishes and amphibians,
which have high rates of water excretion, whereas uricotely in
reptiles and birds permits excretion of nitrogen with minimal
water loss. Hummingbirds, which have rates of water turnover
rivaling those of freshwater vertebrates, have recently been
shown to be facultatively ammonotelic. I tested the hypothesis
that the switch from uricotely to ammonotely in hummingbirds is
related to rates of water excretion. In hummingbirds fed dilute
nectar (0.2 M sugar), rates of water turnover were extreme,
amounting to about 25% of body mass per hour. Nonetheless,
the birds remained uricotelic, excreting more than twice as much
nitrogen in the form of urates than as ammonia. Birds fed
concentrated nectar (2.0 M), on the other hand, consumed less
food and had low rates of water turnover, but they excreted
more nitrogen as ammonia and urea than as urates. These data
fail to support the notion that the switch in hummingbirds from
uricotely to ammonotely is linked to high rates of water
excretion. The physiological significance of facultative
ammonotely in hummingbirds remains unknown.
67A
394
In the present study, we determined the dynamic changes in
Cl fluxes and content of euryhaline tilapia larvae during
development and upon seawater (SW) challenge. Fertilized eggs
were incubated in fresh water (FW) and 20 ppt SW, respectively,
for 8 days. Whole-body Cl content and Cl fluxes of larvae were
measured from day1 to 5 after hatching. No significantly change
was found in whole-body Cl content during development in ether
FW or SW larvae, while Cl fluxes increased with development
and was higher in SW larvae then in FW larvae. In another
experiment, 3-day-old larvae were transferred acutely from FW
to 20 ppt SW, and their Cl fluxes and content were measured. Cl
content of larvae increased dramatically and reached a peak at
5-8 h after the transfer, then restored to the level of control FW
larvae after 16 h. Cl influx increased rapidly after the transfer,
while Cl efflux did not increase until 8 h after the transfer. These
results suggested that developing tilapia larvae were capable of
modulating both Cl influx and efflux to maintain body Cl
constancy upon SW challenge.
399
Ontogeny of osmoregulation in the embryos of the crayfish
Astacus leptodactylus.
CHARMANTIER-DAURES, M*, G. N. SUSANTO, and G.
CHARMANTIER. Univ. of Montpellier II, Paris, France.
400
Involvement of CHH in the control of osmoregulation in a
grapsid crab.
CHARMANTIER, G.*, C. SPANINGS-PIERROT, D. SOYEX, and F.
VAN HERP. Univ. Montpellier II, Paris, France, and Univ. of
Nijmegen, The Netherlands.
Total extracts of sinus glands (SG) of the euryhaline crab
Pachygrapsus marmoratus have been shown to contain peptidic
factor(s) that stimulate osmoregulating processes in isolated
perfused posterior gills from crabs acclimated to low salinity.
Separation of P. marmoratus SG peptides by RP-HPLC, followed
by a direct ELISA performed with an anti-Carc/nus maenas CHH
(crustacean hyperglycemic hormone) antiserum, revealed a major
immunoreactive peak in the chromatogram. A glucose
quantification bioassay demonstrated a strong hyperglycemic
activity only in this immunoreactive so called CHH fraction.
Isolated posterior gills were then perfused with HPLC fractions at
a dose of 4 SGeq/assay. Only the CHH fraction significantly
increased the transepithelial potential difference and the sodium
influx by about 50%, in a rapid and reversible way. Another
substance of unknown nature, eluted earlier than CHH in the
HPLC gradient, caused a small increase in sodium influx (14%)
but had no effect on the transepithelial potential difference. No
other peptidic product from the SG had significant effect on the
measured parameters. These results indicate that CHH, in
addition to its hyperglycemic activity, is also directly implicated
in branchial ion transport. Therefore, CHH is most probably
involved in the control of osmoregulation in decapod
crustaceans.
401
Chick allantoic membrane is an aldosterone target tissue.
MACHART, J.M.* and D.U. SILVERTHORN. Univ. of Texas,
Austin.
Aldosterone (aldo) enhances Na + reabsorption by the kidney
and intestine. The effect of aldo on chick allantoic membrane, a
Na + -absorbing epithelium encasing the embryonic waste fluid,
has not been examined to date. We conducted dose-response
experiments by adding aldo (0.55, 1.1, 11 or 28 nM) to 9-19 day
old chick allantoic preparations suspended in a Ussing chamber.
Responses were categorized as amiloride-inhibitable increases in
short-circuit current (LJ initiating at 0-15 min, 16-45 min, 46-90
min or 91-120 min after aldo application. From 0-45 min, all aido
concentrations stimulated a comparable increase of less than 2
uA/cm 2 over 30 min. From 46-120 min, 28 nM aldo stimulated a
roughly two-fold l^. increase over that of 0.55-11 nM aldo. We
conclude that: 1) chick allantoic membrane is an aldo target
68A
402
Survival of water stress by embryos of an annual killifish:
Dehydration avoidance and protein structure of the egg
envelope.
PODRABSKY, J.E.*, J.F. CARPENTER, and S.C. HAND. Univ. of
Colorado, Boulder, and Univ. of Colorado Health Sciences
Center, Denver.
Survival of water stress during diapause in embryos of
Austrofundulus limnaeus is achieved by reducing evaporative
water loss. Diapause II embryos survive >100 d in air at relative
humidities (RH) above 75.5%. Pre-diapause II and diapause III
stages are less tolerant of desiccating conditions. Rate of
evaporative water loss is high during the initial 1 -2 d and then
falls to very low values after day 4. Early water loss is explained
by dehydration of the perivitelline space without invoking loss
from tissues. This conclusion is supported by microscopic
observations, as well as retention of bulk, freezable water in
embryos exposed to 75.5% RH. Secondary structure of proteins
comprising the egg envelope shows strong intermolecular
contacts via beta-sheet. An increase in intermolecular beta-sheet
occurs during drying of isolated egg envelopes. Increased
resistance of diapause II embryos to water stress is not
correlated with any ontogenetic change in protein secondary
structure. Thus additional mechanisms are likely involved in
resistance to dehydration. [NSF grant IBN-9723746]
403
Oxygen uptake via hindgut irrigation in tadpole shrimp
Triops longicaudatus.
CHAPMAN, S.L.' and C.L REIBER. Univ. of Nevada - Las Vegas.
Tadpole shrimp Triops longicaudatus live in temporary waters
that are often hypoxic for prolonged periods of time. Tadpole
shrimp have unspecialized respiratory appendages that are
thought to be inadequate for adjusting oxygen uptake under
hypoxia. Accessory respiratory surfaces, such as the hindgut, aid
in the diffusion of oxygen into the animal. Reverse peristaltic
movements of the hindgut, resulting in water and oxygen uptake,
increase with changes in environmental oxygen tension. Two
populations of tadpole shrimp were reared under hypoxic
conditions (27-32 and 65-70 mmHg). In both populations,
regulation of hindgut irrigation occurs at the anterior end of the
animal. The difference between the populations of tadpole
shrimp in their ability to uptake oxygen using hindgut irrigation
was not significant. After accounting for cutaneous gas
exchange, smaller tadpole shrimp are able to take up more
oxygen using hindgut irrigation than are larger animals
regardless of their rearing environment.
404
Effects of hypoxic exposure on cardiac function in the larval
grass shrimp [Palaemonetes pugio).
LAUNDRIE, N. C* and C. L REIBER. Univ. of Nevada, U s
Vegas.
Grass shrimp exhibit an anamorphic developmental pattern
where successive larval stages show only minor anatomical
change. Cardiac physiological development has not been
investigated to determine if physiological changes occur in
parallel with gross anatomical development. Physiologically,
adults are able to regulate cardiac functions and compensate for
reductions in oxygen availability by increasing heart rate to
maintain oxygen delivery to the tissues. Larval grass shrimp were
exposed to step wise reductions in water oxygen (150,100, 75,
50, and 25 mmHg O2). Cardiac functions were monitored using
videomicroscopic techniques followed by dimensional analysis.
Both heart rate and stroke volume of larval shrimp (stages 6 -10)
remained unchanged when exposed to moderate hypoxia (75
mmHg O,); below this a bradycardia was observed. Stroke
volume remained at normoxic levels, resulting in a decrease in
Osmoregulation was studied throughout the embryonic
development of Astacus leptodactylus. Egg-carrying females
were held in freshwater (FW) and in three saline media (200, 400,
600 mosm/kg). In FW, changes in peri-embryonic fluid (PEF) and
embryonic hemolymph (when available) osmolality were followed
from freshly-laid eggs to hatching (for an embryonic eye index,
El, of 430-450 urn) and in first-stage juveniles. The PEF and/or
hemolymph osmolality remained stable at about 350-370
mosm/kg from early to late (El 390 urn) embryos; it decreased (El
420 urn) prior to hatching and in freshly hatched juveniles, down
to 290 mosm/kg. Artificial opening and removal of the egg
membranes, followed by direct exposure to FW, demonstrated
that the ability to hyper-osmoregulate, and consequently to
survive, in FW appears in embryos with El > 410 urn, i.e. only a
few days before hatching. Following a transfer to the saline
media, the PEF/hemolymph osmolality increased slowly over 14
days and became isosmotic with the external media at 400 and
600 mosm/kg. The embryos died at El 380-390 urn in these
media, and only at 200 mosm/kg was the development
completed until successful hatch. These results demonstrate that
- the crayfish egg membranes are highly impermeable to water
and ions, - the embryos become able to osmoregulate in FW
shortly before hatching.
tissue, 2) a rapid response occurs as well as the classic early
response and 3) the effects of 0.55-11 nM aldo are comparable,
whereas 28 nM aldo stimulates a greater increase in !„.. Aldo
may play a crucial role in rehydration of the embryo by regulating
Na+ transport and subsequent water reabsorption across the
allantoic membrane.
cardiac output. This is in direct contrast to the adult response.
This may indicate physiological maturation of cardiac regulatory
mechanisms as the larvae develop.
system did not contribute to hypoxic pressure responses. These
reactions differed from those known to occur in adult chickens
suggesting the operation of a unique regulatory system
405
408
Chronic training influences on the cardiovascular system of
larval zebrafish, Danio rerio.
BAGATTO, B.*, T. SCHWERTE, B. PELSTER, and W.
BURGGREN. Univ. of North Texas, Denton, and Univ. of
Innsbruck, Austria.
Postprandial acid base status in the Savannah monitor
lizard.
HARTZLER, L.K.', J.W. HICKS, and A.F. BENNETT. Univ. of
California, Irvine.
406
Effects of ventricular hypertrophy on the coronary
microvasculature in male rainbow trout.
CLARK, J.J.*, J.T. MCMINN, and K.J. RODNICK. Idaho State
Univ., Pocatello.
The purpose of this study was to characterize myocardial
capillaries during maturation-induced cardiac hypertrophy in
male rainbow trout (Oncorhynchus mykiss). Hearts from trout at
various stages of sexual maturation were excised, cannulated via
the coronary artery, perfusion fixed with Histochoice, casted with
Microfil, and examined histologically. We estimated capillary
density and functional capillary reserve. Consistent with the type
II ventricular myocardium, the capillary bed was confined to the
compact layer. In mature fish (relative ventricular
mass,(RVM)>0.12%), capillary density increased significantly with
ventricular growth (-1200-2200 mm"*). Over 80% of capillaries
were perfused with Microfil and we found a positive correlation
between RVM and the percentage of perfused capillaries. These
data suggest that the capillary bed of the trout heart is adaptable
and compensates by promoting angiogenesis and increasing the
number of perfused capillaries. We hypothesize that a shorter
diffusion distance may help support higher metabolic needs of
enlarged hearts of mature male rainbow trout. Supported by
NSF-ldaho EPSCoR grant EPS-9720634 (KJR) and ISU GSRSC
S99-05 (JJC).
407
Cardiovascular responses to hypoxic stress in embryos of
the domestic chicken (Gallus gallus).
CROSSLEY, D.A.*, J. ALTIMIRAS, and W.W. BURGGREN. Univ.
of California, Irvine, Univ. of Goteberg, Sweden, and Univ. of
North Texas, Denton.
The primary focus of this work was to characterize hypoxic
cardiovascular responses in embryonic chickens and determine
regulatory systems responsible for these responses. Bouts of
15, 10 and 5% oxygen depressed heart rate and blood pressure
consistently from day 9 to 21 of chicken incubation. Increases in
the hypoxic severity augmented the cardiovascular responses to
hypoxia. Exposure to 10% oxygen caused a characteristic fall in
heart rate on all days of study, however arterial pressure was
unaffected by this level of hypoxia on day 20 and 21. Heart rate
reactions to 10% oxygen exposure were accomplished without
cholinergic or adrenergic action on all days of study, possibly
suggesting a direct inhibitory action on the heart. Early in
development arterial pressure response also exhibited this trait,
however starting on days 18 and 19 both beta and alphaadrenergic systems contributed to hypoxic reactions. Cholinergic
ABSTRACTS
A large alkaline tide (>20mM increase in bicarbonate) has
been measured in alligators 24 hr after ingesting a large meal
(Coulson and Hernandez, CBP, 1983). Recent studies on
Burmese pythons (Overgaard et al, unpublished data) show little
change in plasma bicarbonate (<5mM) or pH (<0.05 pH units) 24
hr following feeding (20-40% of body mass). The variation
between these two species poses the question: is the alkaline
tide unique to crocodilians? We measured the postprandial
changes in arterial pH, oxygen consumption rate (Vo2), and
hematocrit (Hct) in Varanus exanthematicus at 35°C following
consumption of a meal approximately 10% of body mass. Within
4 hr following feeding, pH, Hct, and Vo 2 increased. At 12 hr
postfeeding pH was as much as 0.07 pH units higher than
control, Vo2 had doubled and Hct had increased -10%. During
the following 24 hr Hct returned towards control values while Vo 2
continued to increase (3-4 fold over rest) and pH remained
slightly elevated (-0.06 pH units). These studies suggest that
large postprandial increases in arterial pH may not be a general
phenomenon in carnivorous reptiles. Supported by NSF grant
IBN-9727762.
409
Body component analysis of hypogean crayfish.
POWELL, M.L.* AND S.A. WATTS. Univ. of Alabama at
Birmingham.
Prolonged periods of nutrient deprivation occur during the
normal life cycles of the crayfish Procambarus clarkii and P.
zonangulus. During summer months crayfish retreat into burrows
for up to four months, consuming little or no food. We examined
the composition of tissues during starvation. Crayfish of both
species were isolated in individual containers for 5 months and
either fed to excess or starved. Total dry weights for starved
crayfish were significantly lower than fed controls after 2 months
of starvation. The dry weight of the hepatopancreas was
significantly lower than controls after 2 months of starvation;
percent lipid was unchanged. Tail muscle dry weights were
significantly lower than controls after 4 months, percent lipid was
unchanged. The organic content of the carapacefminus
hepatopancreas and tail) decreased the first month of starvation.
Neither lipid or carbohydrate decreased in the carapace, but
protein decreased significantly in the carapace after 5 months.
The carapace comprises 90% of the total dry matter in a well fed
crayfish and contributed 73% of the total dry matter used during
starvation, indicating the carapace is a significant source of
energy during starvation. Funded by TVA.
410
The effects of drinking, feeding and starvation on mass
changes in the tropical fruit-eating satyrine butterfly
Manataria maculata.
STEVENSON, R.D.*, P. SZCZYS, and C.A.L. WOOD. Univ. of
Massachusetts, Boston, and Vassar College, Poughkeepsie, NY.
Mass allocation among body parts and tissues is a dynamic
process in animals that allows them to improve survival and
performance. Measuring allocation will lead to better
understanding of the physiological condition of the organism.
The Lepidoptera abdomen is the location where water, food, fat
and reproductive materials are stored. A cargo model predicts
that mass changes occur only in the abdomen. This model was
tested using individuals (0.12 to 0.35 g) of Manataria freshly
captured during July in Monteverde, Costa Rica and kept
indoors in flight cages. Animals were fed water or sugar water
(20%) daily or starved. Those fed water drank for 2-3 minutes
and took small meals averaging 10% of body mass. Mass was
maintained over 5 days. Those fed sugar water drank for 3 to 7
minutes, imbibing meals averaging 50 to 60% of body mass.
69A
Zebrafish (Danio rerio) larvae of an albino color mutant
(alb/alb) were divided into two different age groups (4 and 9 days
old) and subjected to a training water velocity of 5 body lengths
per second. Day 4 larvae were trained continuously for 2 days
whereas Day 9 larvae were trained for 15 hours during the night
and allowed to feed during the day in the absence of water flow
(25'C). Although training did not significantly affect resting heart
rate and stroke volume in day 4 larvae, it did significantly
increase resting cardiac output. The same result was also true of
day 9 larvae after 4 days of training. Increased cardiac output
was observed in day 9 larvae after 2 and 6 days of training,
however, large variation in measurements prevented these
results from being statistically significant. Digital imaging analysis
of the vascular system suggested that erythropoiesis was not
initiated during and after training periods. This research was
supported by NSF IBN 96-16138 and the Austrian Science
Foundation (P12571-BIO).
but an increase in the amount of lipid carried by HDL and a
decrease in LDL late in the spawning cycle. These findings imply
that lipid from mesenteric fat is being transported by HDL just
prior to spawning in F. heteroclitus.
411
414
The effects of age and feeding on body mass, CO 2
production, and water toss in the butterfly Vanessa cardui.
WOODS JR, W.A.*, C.A L. WOOD, and R.D. STEVENSON. Univ.
of Massachusetts Boston, MA and Vassar College,
Poughkeepsie, NY.
Long-term effects of hydric conditions during incubation on
body size and triglyceride content of neonatal snapping
turtles: Is wetter better in the long run?
FINKLER, M. S.*, J. T. BOWEN, T. M. CHRISTMAN, and A. D.
RENSHAW. Indiana Univ., Kokomo.
Little is known about the effects of age and feeding in
invertebrates, though such effects are important and well
documented for vertebrates. We maintained 8 male and 8 female
adult V. cardui in individual 500 cc chambers (30"C, 14% RH,
16L:8D) from the day after eclosion until death. Half of each sex
were unfed, and half were fed 10% sucrose daily ad libitum.
Body mass, CO 2 production and water loss rate were measured
daily for the lifetime of each individual. Unfed individuals lived
3.2 days on average and fed individuals 15.1 days, though mean
body mass at death for both treatments and both sexes was
approximately 63% of the initial value of 0.248 g. Among fed
individuals, females lived longer than males, a mean of 17 days
versus 13.5 days. CO 2 production for unfed animals increased
from 1.1 to 1.25 cc/g h, while for fed animals it decreased from
1.1 to 0.9 cc/g h between the first and second days, then
remained relatively unchanged. Water loss rates varied from 9.9
to 25.7 cc/g h and exhibited complex patterns with age and
feeding state.
Though many studies have suggested that wet incubation
conditions may lead to enhanced fitness during the period
immediately following nest emergence, few have addressed the
consequences of associated elevated embryonic yolk utilization
on the energetic reserves of the hatchlings during the first winter.
We measured the size, dry mass, and triglyceride contents of the
carcasses and yolk sacs of hatchlings from eggs incubated
under wet and dry conditions at three time intervals: one week
posthatching (late August), at the onset of an overwintering
period following ten weeks of ad libitum feeding (early
November), and at the end of overwintering (late March). Dry
hatchlings demonstrated greater increases in both wet and dry
carcass mass during the fall, and showed smaller decreases in
dry mass during the winter, than did wet hatchlings. Dry yolk sac
mass and triglyceride contents were higher in dry hatchlings than
in wet hatchlings at all intervals. These findings suggest that
possible survival advantages of hatchlings emerging from wet
nests may be tempered by decreased energy reserves during the
first winter.
412
Effects of methemoglobin on hypoxia tolerance and oxygen
consumption in rainbow trout.
LACEY, J.A.*, K.M. KESSLER, and K.J. RODNICK. Idaho State
Univ., Pocatello.
It is generally thought that elevated levels of methemoglobin
(metHb) in fishes impair respiratory function due to lower oxygen
carrying capacity. We evaluated whether metHb influences
hypoxia tolerance and oxygen consumption in rainbow trout
{Oncorhynchus mykiss). MetHb was induced by injections of
NaNO2 (76 mg/kg body wt.) and animals were studied 1 or 2 h
post injection in closed respirometry vessels at 15°C. Water was
taken every 15 min, dissolved oxygen (DO) were recorded and
oxygen consumption rates (MO2) determined. As fish lost
equilibrium, DO was recorded, blood taken, and assayed for
metHb. At similar DO, the control group (-2% metHb) had higher
MO 2 than the 2h group (26±4% metHb) and 1h group (47±3%
metHb). Test groups had similar MO 2 at high DO (>5ppm),
however the 2h group maintained higher MO, than the 1 h group
at lower DO (<5ppm). Control fish tolerated the lowest DO
(2.0ppm), followed by the 2h group (2.4ppm), then the 1h group
(2.6ppm). These results suggest that moderately elevated metHb
reduces hypoxia tolerance and lowers MO 2 . Supported by NSF
grant EPS-9720634 (KJR) and ISU GSRSC F98-16 (JAL).
413
Lipid allocation and transportation in Fundulus heteroclitus
over three consecutive spawning cycles.
JENSEN, B.H.', K.E. WONG, and M.H. TAYLOR. Univ. of
Delaware, Newark.
During reproduction in Fundulus heteroclitus much energy is
used to produce viable oocytes which are spawned on spring
tides. How fish allocate energy throughout spawning is important
since it is essential for survival. The purpose of this study was to
establish which body components, if any, are being used as a
lipid source during ovarian growth. We measured GSI; HSI; gut
content; lipid per cell in the ovary, liver, mesentery, and soma;
using agarose gel electrophoresis, the percentage of total
plasma lipid carried by each lipoprotein. Lipid per cell in the
ovary dropped during spawning, while in the mesentery, there
was an increase in lipid/cell after spawning and early in the next
spawning cycle. Lipid per cell in the liver changed little
throughout the cycle, suggesting that the liver may not be an
important storage depot in F. heteroclitus. Preliminary results
indicated constant plasma VLDL during the reproductive cycle,
70A
415
Carbon isotope ratios in exhaled carbon dioxide, as an
indicator of past diets, present diets, and metabolic
substrate in birds.
HATCH, K.A*, B. PINSHOW, and J.R. SPEAKMAN. Univerisity of
Nevada, Reno, Ben-Gurion Univ., Sede Boqer, Israel, and Univ.
of Aberdeen, United Kingdom.
The ratio of Carbon 13 to Carbon 12 in exhaled CO2 reflects
the carbon isotope ratio of the substrate that the bird is currently
using for energy. This fact can be used to determine dietary
source and composition when foods have unique carbon isotope
signatures, We took breath samples from six pigeons (Columba
livia) fed and raised on a corn based diet. The carbon isotope
ratios of the samples reflected that diet. We then switched them
to a wheat based diet. Again breath carbon isotope ratios
reflected that of diet. Finally, we fasted three of these pigeons for
three days. In birds raised on corn and then fed wheat, the
carbon isotope signature of the exhaled breath showed that the
endogenous energy stores of the fasting birds were laid down
while the pigeons were eating the corn based diet. Thus exhaled
carbon dioxide can be an indicator of past diet in fasting birds as
well as present diet in fed birds. Finally, we demonstrate a new,
non-invasive breath sampling technique that can be easily used
in the laboratory or in the field. This technique can be applied to
virtually any species of bird and promises to provide us in the
future with valuable dietary information.
416
Digestive and metabolic responses to foraging risk in a
dabbling duck.
BARBOZA, P.S/ and D.G. JORDE. Univ. of Alaska, Fairbanks
and USGS, Patuxent Wildlife Research Center MD.
Feeding was restricted without limiting the quality and
quantity of food for black duck (Anas rubripes). Nine adult males
were fed an extruded diet of 2% fat, 17% protein and 9% fiber.
Ducks were caged indoors from September (12h light; 17-24°C)
to measure balances over 14d when fed ad libitum each day
(unfasted) and then fasted for 2d/wk (low-risk) or 4d/wk (highrisk). Birds held mass at 1089g, body water at 800g and dry
matter intake at 604g/14d. Intakes increased by 40% (low-risk)
and by 133% (high-risk) on feeding days but energy
metabolizability (82% to 79%; P<0.01), and fiber digestibility
(44% to 9%; P<0.05) were reduced. Fasting regimes were
continued in individual outdoor pens for 9wk. Birds gained mass
They gained 15% of their initial body mass over 5 days. Those
starved for 3 days averaged 12% loss in mass. Dissection of
freshly-caught and starved groups revealed that only the
abdomen changed mass, supporting the cargo model.
and body water as temperatures declined from 14-21'C to -916°C. At week 5, low-risk ducks were heavier (1372 vs. 1241g;
P<0.05) and fatter (276 vs. 140g; P<0.001) than high-risk birds
while body water (894g) and protein were similar between
groups (222g). Ducks are unable to increase digestible intakes to
compensate for lost foraging time in the fall when nutrient
demands for tissue synthesis, thermoregulation and activity are
elevated.
417
Intestinal function is only modestly compromised in 20-yearold naked mole-rats.
O'CONNOR, T.P.* and R. BUFFENSTEIN. City College of New
York, NY.
418
Characterization of a vertebrate gastric chitinase.
MOE, CM.* and A.R. PLACE. Univ. of Maryland Biotechnology
Institute, Baltimore, MD.
We have purified a chitinase (E.C. 3.2.1.14) from the gastric
tissues of rainbow trout [Onchorynchus mykiss) that has Nterminal amino acid sequence homology with known invertebrate
(Brugia malayia, Penaeus japonicus) and vertebrate (human
chitotriosidase) chitinases. The pH optimum of the chitinase
activity is 4.0-4.5. Using fluorophore assisted carbohydrate
electorphoresis (FACE), we have shown that this enzyme
releases dimers from the non-reducing end of soluble and
insoluble chitin substrates. Crude gastric extracts of several
vertebrate species (fish, bird, reptile, amphibian, mamml) were
investigated with respect to chitinolytic activity, substrate
specificity (using FACE), pH profile, and immunocrossreactivity
(using rabbit polyclonal antiserum raised against the purified
rainbow trout protein). A homologous enzyme was found in the
stomach tissues of all the major vertebrate classes investigated.
Based on our findings, it is proposed that chitinase is an ancient
gastric enzyme whose major function may be anti-pathogenic
rather than digestive.
419
Influence of anoxia on transcription and mRNA stability in
mitochondria isolated from Artemia franciscana embryos.
EADS, B.D.* and S.C. HAND. Univ. of Colorado, Boulder.
During periods of anoxia embryos of the brine shrimp
Artemia franciscana enter a reversible state of metabolic arrest,
which is characterized by a rapid drop in intracellular pH (pH)
and ATP. Using in organello transcriptional run-on assays,
incorporation of 32P-UTP drops 66% from the optimal pH of 7.9
to 6.7, the pH seen after 1 h of anoxia. Additionally, mitochondria
incubated anoxically reduce UTP incorporation by 46% over a 1
h period compared to aerobic controls. Previous work has
shown that levels of the mitochondrially encoded subunit 1 of
cytochrome c oxidase are stable during 6 h of anoxia. Taken
together, these data suggest that production and degradation of
RNA may be coordinately downregulated during anoxia. To
directly test whether mRNA pools are stable during anoxia due
to extended message half-life, we have used oligonucleotide
ABSTRACTS
420
Evolution of quaternary structure in phosphagen kinases.
ELLINGTON, W.R.*, A. PINEDA, and T. SUZUKI. Florida State
Univ., Tallahassee, and Kochi Univ., Japan.
Phosphagen kinases (PKs) catalyze the reversible transfer of
phosphoryl group from phosphagen to ADP yielding ATP. There
are six major PKs, each differing in specificity for guanidine
substrates. Most PKs exist as functional dimers with an Mr of
approx. 80 kD. Creatine kinases (CKs), in contrast, exist as
dimers as well as octamers and as a large, monomeric CKs
which consist of three contiguous CK domains. Similar diversity
in structure exits for arginine kinases (AKs) as this enzyme can
be found as monomers and dimers as well as a monomer
consisting of two contiguous AK domains. Recent elucidation of
the cDNA sequences of a variety of invertebrate CKs and AKs
has shed considerable light on the evolution of quaternary
structure. Virtually all subunit association states as well as
contiguous dimers and trimers were present prior to the radiation
of the major metazoan groups. Since quaternary structure may
strongly influence the localization of these enzymes to particular
parts of cells, intracellular targeting may have been a major
factor driving the evolution of this enzyme family. (Supported by
NSF grant IBN-96-31907 to WRE and a grant from the Japanese
Ministry of Education to TS).
421
Nitric oxide potentiates muscle contraction in clam gills.
GAINEY.JR., L.F.*, R.T. PIRONE, and M.J. GREENBERG. Univ.
of Southern Maine, Portland, and Univ. of Florida, St. Augustine.
When isolated gills of Mercenaria mercenaria axe treated with
5-hydroxytryptamine (5HT), the branchial musculature contracts.
Moreover, a second application of the same concentration of
5HT produces a larger contraction. This potentiation persists for
up to 2 hours. At 2x10-5M 5HT, the mean ratio of the second to
the first contractions (CR) is 2.14 (se = 0.24; n=54); the ratio is
significantly greater than 1. When the gills are exposed to the
nitric oxide synthase inhibitor L-NAME for 15 minutes between
doses of 5HT, the potentiation is inhibited in a dose dependent
manner. From 10-4M to 10-6M L-NAME, the potentiation is
abolished. The mean CR for these doses is 1.05 (se = 0.08,
n=12). At 10-8M L-NAME, the mean CR is 3.6 (se = 0.59, n = 3);
but this ratio is not significantly different from untreated controls,
nor of gills treated with D-NAME. The nitric oxide generator
SNAP mimics the effects of 5HT potentiation: That is, gills
pretreated with 10-4M SNAP and then exposed to 2x10-5M 5HT
contract as though they had been exposed to a previous dose of
5HT; the mean CR of gills exposed to NO and untreated controls
is 3.04 (se = 0.64, n = 9).
422
The effects of serotonin agonists and antagonists on the
isolated earthworm gut.
KLOHR, R.W.' and K.G. KRAJNIAK. Southern Illinois Univ.,
Edwardsville.
Previously we studied the effects of serotonin on the isolated
crop-gizzard of the earthworm, Lumbricus terrestris, and found
that it had an inhibitory effect on both rate and amplitude with a
threshold between 10' 8 M, and 10"7M. To further classify the
serotonin receptor, we are using several agonists and
antagonists which are known to bind to specific mammalian
receptor subtypes. We have found that 8-OH-DPAT, a selective
agonist for the 1A subtype, has an inhibitory effect on rate
similar to serotonin. The threshold for this decrease in rate was
between 10"10M, and 10~9M. The amplitude increased however,
with a threshold between 10' 7 M, and lO^M. This amplitude
increase is opposite to that of serotonin. We are currently testing
several other compounds, including: methysergide maleate (a
type 2 antagonist), m-chlorophenylbiguanide (a type 3 agonist),
and alpha-methyl-5-HT (a type 2 agonist). Only after testing
71A
Aging is associated with a progressive decline in nearly all
physiological capacities, including substantial declines in
gastrointestinal function. For example, intestinal transport
activities in lab mice decline by 50-60% from peak values as
animals reach their median lifespan of ca. 2y. Naked mole-rats
(Heterocephalus glabei) are also 40g rodents, and hence
allometric relationships predict a maximal lifespan of 6y for both
species. Remarkably, naked mole-rats often live over 20y in
captivity. We investigated rates of glucose transport throughout
the gastrointestinal tract of 1, 5, 10, and 20 y-old naked molerats. Glucose transport activity (per mg tissue) in the proximal
and distal small intestine decreased significantly with increasing
age between ages 1 and 10, but did not decline further between
ages 10 and 20. Overall, rates were only 15-30% lower in 20 yolds than in 1 y-olds. There was no significant effect of age on
the mass of the heart, liver, stomach, spleen, kidneys, or brain,
but small intestine mass decreased significantly. The attenuated
decline of intestinal transport rates may contribute to the long
lifespan found in naked mole-rats.
probes for four genes. Specificity of the probes was shown by
Northern blotting against mitochondrial RNA. Dot blots were
used to estimate messenger half-life. The results indicate that
mRNA stability may be an important regulatory aspect of gene
expression during bouts of anoxia-induced quiescence.
these and several other compounds will we begin to be able to
determine which mammalian serotonin receptor subtype the
crop-gizzard of L terrestris resembles.
423
Serotonin increases cyclic AMP content of Aplysia foot
muscle.
MCPHERSON, D.R. State Univ. of New York at Geneseo.
424
The physiological consequences of claw autotmy in the
stone crab Menippe mercenaria.
SCHOLNICK, D.S.", L.M. WATERS, and A.L. WOLF. Eckerd
College, St. Petersburg, FL.
Claw autotomy is an important survival mechanism in the
stone crab Menippe mercenaria that can result in the acute loss
of almost half of the animal's body mass. We examined the
impact of skeletal muscle loss due to claw autotomy on lactate
recycling, blood glucose, and acid-base balance during recovery
from 30 min of exercise or 12 h of hypoxia. Claw autotomy
decreased hemolymph glucose levels by as much as 48% 2 h
postexercise. Hemolymph lactate and pH levels were similar 4 h
postexercise between autotomized and unautotomized crabs.
Hemolymph clearance rates of infused sodium lactate were also
similar between autotomized and unautotomized crabs. Although
major and minor chelae make up as much as 41 % of stone crab
body mass (about 62% of which is skeletal muscle and blood)
claw skeletal muscle does not appear to contribute to lactate
metabolism but may be an important glucose source during
recovery from hypoxia or exercise. Support provided by Howard
Hughes Medical Institute.
425
426
Thermal dependence of muscle CA2+ in bluefin tuna.
BLANK, J.M.*, J.M. MORRISSETTE, and B.A. BLOCK. Stanford
Univ., Pacific Grove, CA.
Bluefin tuna are endothermic teleosts capable of maintaining
slow-twitch muscle temperatures of 23-30°C in ambient
temperatures ranging from 5-30°C. Bluefin fast-twitch muscle is
warm near the center of the fish, adjacent to the slow-twitch
muscle mass, but the fast muscle beneath the skin is often 6-8°C
cooler. Studies of muscle fiber mechanics in yellowfin tuna show
that warming the slow-twitch muscle increases power output at
higher frequencies, due in part to reductions in relaxation time.
The sarcoplasmic reticulum Ca2+ ATPases (SERCA1 and 2) play
a major role in setting muscle relaxation rate. Here, we compare
the temperature-dependence of Ca2+ uptake in slow-twitch and
both superficial and deep fast-twitch muscle, using fura-2.
SERCA function in bluefin slow muscle is more temperature
sensitive than in fast muscle. The bluefin tuna slow-twitch
SERCA functions optimally at a higher temperature than slowtwitch SERCA from yellowfin tuna. Bluefin tuna deep fast muscle
fails to pump Ca2+ below 15'C, but superficial fast muscle
SERCA operates down to 5°C. We are currently investigating
what factors underly these variations in function.
427
Lactate transport in lizard muscle.
DONOVAN, E.R.* and T.T. GLEESON. Univ. of Colorado,
Boulder.
Lactate (LA) uptake in Dipsosaurus dorsalis was studied
under conditions simulating those seen following exercise. The
uptake rates of the red and white portions of the iliofibularis (rIF,
wIF), equilibrated in a 5mM LA solution, were measured over 1 to
15 min in a 15mM LA incubation. RIF had a greater uptake rate
than wIF. The 1, 2 and 3 min rates (nmoles/mg muscle/min) were
3.3, 1.7 and .8 for wIF and 6.4, 4.7 and 2.9 for rIF. By 10 minutes
the rates leveled off at .4 for wIF and 1.3 for rIF. Uptake rates in
mouse soleus under the same conditions were 2.79, 1.65 and
1.63. Rates were also measured in the presence of 10mM
ethymaleimide (ETH), a sulphydryl-group modifier. Preliminary
data suggest that ETH has no effect on wIF but causes a 64%
drop in the uptake rate of rIF, suggesting that the dominant
mode for LA uptake by red fibers is protein mediated transport.
In vitro rates of LA utilization over 2 hours are equivalent to 0.1
nmoles/mg/min. Thus, the in vitro rate of LA uptake far exceeds
the ability of the muscle to utilize LA over the long term
suggesting the possibility that the high rates of uptake in red
fibers are more of an adaptation to a fast response to changes in
LA concentrations than to long term LA removal. Supported by
NSF 9724140.
Adjusting muscle power and optimal frequency: Strong
effects of calcium sensitivity and troponin T expression on
flight muscle of the dragonfly L. pulchella.
FITZHUGH, G.H.*, M.R. WOLF, and J.H. MARDEN. Penn State,
State Collega, PA.
Power and control muscles of cicada song.
STOKES, D.R.* and R.K. JOSEPHSON. Emory Univ., Atlanta, GA,
and Univ. of California, Irvine.
Dragonflies are aerial acrobats, engaging in high
performance maneuvers that enable them to mate and defend
territories. We investigated the mechanisms by which L
pulchella regulates flight muscle performance. Maximum specific
power output (Pmax) of flight muscles was measured with workloops (20-45 Hz). Pmax of individual dragonflies varied between
44-148 W/kg and was strongly correlated with the calcium
sensitivity (pCa50) of skinned fibers (r2=0.64, p<0.0001) and
expression levels (r2=0.56, p<0.0008) of alternatively spliced
transcripts of troponin T, a calcium regulatory protein. Calcium
sensitivity (p<0.016) and troponin T isoform composition
(p<0.015) also significantly affected the frequency at which the
muscle produced maximal power (Fopt). The relative amount of
one transcript, constituting only 7% of the total troponin T
transcript pool, explained 56% of the 3-fo!d variation in Pmax
and 40% of the variaiton in Fopt. These data suggest that broad
The song of male cicadas is produced by repetitive buckling
of paired tymbals on the first abdominal segment. Buckling of
the tymbals is caused by contraction of tymbal muscles.
Additional muscles modulate the sound pulses; tensor muscles
which insert on the rim of each tymbal control its stiffness, and
ventral longitudinal muscles (vim) which depress the abdomen
thereby altering the size of the abdominal resonance chamber.
We have examined the power and control muscles in the cicada
<Magicicada septimdecim\>. The large, pink, tymbal muscle is a
single motor unit which, when stimulated, produces a fast twitch.
Its fibers are rich in mitochondria and sarcoplasmic reticulum
(SR). The tensor muscle, which is much smaller, has two motor
units, each of which produces slow twitches. Its fibers are white
with a much reduced volume density of mitochondria and SR as
compared with the tymbal muscle. The vim, whose size is similar
to the tensor muscle, is more complex yet, with at least 6 motor
72A
428
SOCIETY FOR INTEURATIVE AND COMPARATIVE BIOLOGY
Serotonin (5HT) plays an important neuromodulatory role in
animal locomotion, including the crawling and swimming
locomotion of marine opisthobranch molluscs in the genus
Aplysia. Serotonergic axons innervate muscles in Aplysia foot,
body wall, and parapodia. Activation of serotonergic neurons in
the pedal ganglia increases both the peak force and the
relaxation rate of motoneuron-evoked muscle contractions. The
modulatory effects of 5HT far outlast the duration of the activity
in serotonergic neurons, suggesting that a second messenger
system is involved. Cyclic AMP (cAMP) is involved in
serotonergic modulation at other sites in Aplysia, including the
abdominal ganglion gill-withdrawal reflex circuit, modulation of
buccal muscles by the metacerebral giant neurons, and
modulation of pleural sensory neurons. I have examined the
effect of bath-applied 5HT (10 micromolar) on cAMP levels in
Aplysia foot muscle. Preliminary results indicate a large increase
in cAMP after 10 minutes incubation, and a smaller increase
when the incubation was extended to 30 minutes. Experiments
are underway to determine the time course and dose-response
relationship of the 5HT effect, and to test the effects of 5HT
agonists and antagonists.
variation in whole muscle contractile performance can be
brought about by small changes in troponin T isoform
composition. Work supported by NSF grants IBN-9600840,9722196 and AHA.
mechanism that modulates mitochondrial translation. If the
hypothesis is correct, then administering native heme to the
mitochondrion should reverse the influence of Co 2 * and Ni 2+ .
(NSF grant IBN-9723746)
429
432
cDNA and deduced amino acid sequences for an octameric
creatine kinase from a protostome.
PINEDA, A.* and W.R. ELLINGTON. Florida State Univ.,
Tallahassee.
Effect of lonomycin (IM) and Thapsigargin (TG) on Ca**dependent Cl~ Currents (l a -) in Xenopus oocytes.
BURNS, J.S/, R.G. O'NEIL, and C.L.THURMAN . Univ. of Texas,
Houston, and Univ. of Northern Iowa, Cedar Falls.
Creatine kinase (CK) is a member of a highly conserved
enzyme family that is widely distributed in the metazoa. It is
found localized in cells as distinct cytoplasmic, mitochondrial
and flagellar isoenzymes. We elucidated the evolutionary
relationships of these forms by isolating the cDNA for
mitochondrial CK (MiCK) from Chaetopterus variopedatus. It
consisted of 1703 nucleotides with an open reading frame (orf) of
1227 nucleotides. The first 102 nucleotides of the orf code for a
34-amino acid leader peptide. The mature protein has an
estimated pi of 9.7 and molecular mass of 42.17 kD which
compares well to the SDS-PAGE determined subunit Mr of 43.42
kD (Ellington et al., FEBS Lett. 425:75-78, 1998). Its percent
identity to vertebrate CKs ranges from 64 to 71 %. Conserved
residues in this MiCK are consistent with residues thought to be
important in membrane interaction and dimer/octamer
stabilization based on the available crystal structure for chicken
sarcomeric MiCK. Phylogenetic analyses showed that the
octamer evolved very early in the CK lineage, before the
divergence of deuterostomes and protostomes, roughly 700
million years ago. (Supported by NSF grant IBN-96-31907 to
WRE).
Oocytes from Xenopus laevis were used to study the effects
of the ionophore IM and the Ca**pump inhibitor TG on the
membrane Ca**-dependentl cl -. Unfertilized ova were surgically
extirpated from Xenopus, defolliculated, and bathed with a Ca**free-Ringer's solution. The Ca** dependent ICI. was -36+11.9 nA
in oocytes (-38.8+ 3.4 mV; n=10) voltage-clamped to -60mV.
Adding IM (0.1 to 10 uM)increased ICI- in a dose-dependent
fashion to 143.2 + 47.8 nA. Likewise, TG (0.1 to 10 uM; n=6)
increased l c l - from 58.3 + 6.2 to 111.7+ 6.8 nA. Giving IM after
10 uM TG increased ICI- to 2250+239.5 nA (n=5). On the other
hand, TG responses after 10 uM IM were only 200+65 nA. Thus,
it is concluded that, in a Ca**-free medium, IM and TG both
express an effect on cytoplasmic calcium stores. Supported by
NSF DUE-9750754 and NIDDK-2RO1DK40545.
430
Onset of symbiosis in Fungia scutaria: Changes in patterns
of protein synthesis and gene expression.
DEBOER, M.D.* and V.M. WEIS. Oregon State Univ., Corvallis.
Partners in a symbiosis, such as that between cnidarians and
dinoflagellates, engage in genetic regulation of their association.
Onset of symbiosis occurs during larval development in many
cnidarians, making early genetic interplay between partners
likely. The coral Fungia scutaria can acquire its symbionts as a
planula larva, after formation of a mouth. Little is known,
however, about changes occurring in the larvae on a biochemical
and molecular level, with the onset of symbiosis. Using 2-D
PAGE, we have shown variation in the protein profiles among
non-feeding, symbiotic, and aposymbiotic larvae. In addition, we
report on the expression of specific genes which have been
shown in other cnidarians to be upreguiated within the context of
symbiosis. One such gene, carbonic anhydrase, was shown by
PCR to be expressed in all three larval states. Anti-CA
immunoblots, however, showed no bands, indicating that the
mRNA is not yet transcribed. These results only hint at the
complex biochemical changes that are occurring in developing
larvae with the establishment of the symbiosis.
431
Arrest of mitochondrial protein synthesis during anoxia in
Artemia embryos: Evidence for a heme-based oxygen
sensor.
HAND, S.C.* and K.E. KWAST. Univ. of Colorado, Boulder, and
Univ. of Illinois, Chanpaign-Urbana.
Arrest of translation occurs in mitochondria of brine shrimp
embryos {flrtemia franciscana) under anoxia. The strong oxygen
dependency of mitochondrial protein synthesis is not explained
simply by blockage of the electron transport chain or by the
increased redox state. Preincubation with cobalt or nickel under
normoxia should promote insertion of these ions into heme by
ferrochelatase resident in mitochondria, thereby preventing
oxygen binding and mimicking anoxia. Preincubation with Co 2 *
and Ni 2 * causes an 80% depression of translation under
normoxia. This depression matches that obtained with anoxia.
Co 2 * and Ni 2 * do not compromise rates of state 3 or state 4
respiration, which suggests a minimal influence on integral
cytochromes of the respiratory chain. Results are consistent with
the participation of hemoprotein(s) in an oxygen sensing
ABSTRACTS
433
Immunosuppresion of contact hypersensitivity by sidestream
smoke in ICR mice.
MAYS, C.E.* and S.C. MAYS. DePauw Univ., Greencastle, IN.
Reports of the impact of various stressors on the immune
system have been increasing in recent years. It is well
established that epicutaneous application of haptens can induce
contact hypersensitivity (CHS). Certain irritants such as
ultraviolet B have been shown to induce CHS tolerance. In this
study, using the ear swelling assay and the hapten
dinitrofluorobenzene (DNFB), we produce evidence that
sidestream cigarette smoke may alter the immune system of the
skin of ICR mice in a way that results in CHS suppression. Mice
were divided into three dosage groups consisting of daily
exposure to sidestream smoke from one filter-tip cigarette. Ear
swelling of mice exposed to sidestream smoke for 3 weeks prior
to sensitization through 72 h post-challenge was significantly
less than for the positive controls (P<0.0001). CHS of this group
was suppressed by 80.8%. CHS was not significantly
suppressed in mice dosed from the day of sensitization through
72 h post-challenge (14.3%), nor those dosed from the day of
right ear challenge through 72 h post-challenge (7.6%),
indicating that CHS suppression by sidestream smoke is dose
related.
434
Interspecific and geographic variation of freeze tolerance in
the gray treefrogs Hyla chrysoscelis and H. verslcolor.
IRWIN, J.T.* and R.E. LEE, JR. Miami Univ., Oxford, OH.
The diploid Hyla chrysoscelis and its tetraploid descendent
Hyla versicolor are among 6 northern anuran species that survive
extensive tissue freezing during winter. We hypothesized that H.
versicolor, with its northern range and use of glycerol as a
cryoprotectant, may have a greater capacity for freeze tolerance
than H. chrysoscelis. Our study was the first to directly compare
freeze tolerance in these species where they occur in sympatry
and, by collecting from three locales (Minnesota, Missouri,
Indiana), we have described geographic variation in physiological
responses to freezing and the degree of freeze tolerance. Initial
results indicate that H. versicolor has a higher tissue water
content (e.g., 73% water in liver vs. 70% in H. chrysoscelis).
Higher initial water contents may not be an advantage during
freezing as tissues of both species dehydrate to the same level
(e.g., 6 1 % water in liver when frozen to -2.5°C). This study will
also consider cryoprotectant production (glucose and glycerol),
tissue glycogen stores, and lower lethal temperature limits for
these species and populations.
73A
units, two of which are fast and four slow. There are three
muscle bands in the vim—a central band whose ultrastructure is
like that of the tymbal muscle and lateral and medial bands
which are similar to the tensor muscle.
435
438
Heterosis in two closely related species of earthworms
(Eisenia fetida and E. andrei).
MCELROY, T.C.H613 and W.J. DIEHL*. Mississippi State Univ.
Natural selection at loci controlling dorsoventral patterning
in protostomes vs. deuterostomes.
DIEHL, W.J. Mississippi State Univ., MS.
A relationship between multilocus heterozygosity (MLH) and
fitness has been detected in many populations. Efforts at
describing the mechanism and importance of this correlation
have been frustrated by overlapping predictions of hypotheses.
This study compared growth in two species of earthworm. We
tested the hypothesis that heterosis for growth would be
greatest in inter-populational crosses. Parents were drawn from
two large populations of each species and mated within and
between populations. Allozyme data were collected from 8
polymorphic loci and used to calculate MLH for each individual
and genetic distance (GD) between parents. Heterosis was
detected in both species but the probable mechanisms differ.
When growth rate was heritable MLH and GD between parents
were related to heterosis, and heterosis was likely the result of
associative overdominance. Heterosis detected in other F1
populations was likely the result of epistatic interactions. The role
of allozyme genotypes in heterosis was inconsistent among
species, crosses and families. There may not be a unifying
mechanism among species or individuals for heterosis. Funded
by Sigma Xi and NSF.
Zygotic genes, dpp & sog, have dorsalizing and ventralizing
effects respectively in Drosophila, but their homologues, bmp-4
& chordin, have ventralizing and dorsalizing effects respectively
in Xenopus (Holley et al., 1995). Thus as protostomes and
deuterostomes diverged, natural selection for reversed
dorsoventral patterning likely occurred in maternal genes
upstream from dpp/bmp-4 & sog/chordin. I used the McDonaldKreitman (1991) analysis to test this hypothesis on maternal
genes (toll, cact/NFKBI & dl/rel) and zygotic genes (dpp/bmp-4,
sog/chordin & snail) that establish dorsoventral axes. Coding
sequences from GenBank were identified with Entrez (NCBI);
additional sequences were identified with Blast (NCBI) or Fasta
(EBI). Sequences were aligned using ClustalX with gap penalties
that produced phylogenies with maximum distances between
protostomes & deuterostomes and the fewest frameshifts.
Maternal genes, cact/NFKBI & dl/rel, and the zygotic gene
sog/chordin showed significant selection (P<.05) between
protostomes and deuterostomes. Divergence of protostomes
and deuterostomes was likely caused in part by selection on
some maternal genes that establish the dorsoventral axis.
439
Can locomotor performance evolve in response to natural
selection?
WATKINS, T.B. Dartmouth College, Hanover, NH.
An unusual mucus gland on the tubefeet of Acrocnida
brachiata , a burrowing brittlestar.
CREASER, E. Unity College, ME.
Variation in locomotor performance is often assumed to be
adaptive. Adaptation may be prevented or constrained if
variation in performance is not heritable, if it is subject to strong
maternal effects, or if there exist genetic correlations between
performance and other traits under selection. I conducted a
quantitative genetic analysis of tadpole burst swimming speed,
frog jump distance, body size and larval period in the treefrog
Hyla regilla. Heritabilities for locomotor performance and larval
period were low (0.0 - 0.23) and not significant; body size
measurements showed higher and significant heritabilities (0.240.34). All traits were subject to strong maternal effects, which
were more important than additive genetic sources of phenotypic
variation. All traits were significantly correlated with body size,
even across metamorphosis; locomotor performance
independent of body size was not correlated across
metamorphosis. Low heritabilities and strong maternal effects
constrain and complicate the evolutionary response of these
traits to natural selection imposed by predators. Adaptation in
one stage of the life cycle may not be independent of adaptation
in the other stage, owing to correlations with size across
metamorphosis.
Acrocnida brachiata is a burrowing brittlestar with a
discontinuous distribution throughout North West Europe. It is
found sub-littorally to 40m in clean fine sand in burrows
approximately 10 cm deep. Acrocnida brachiata has arms up to
fifteen times the disc diameter with tubefeet that vary in structure
along the length of the arm. A large mucus gland is prominent on
the oral surface of proximal tubefeet of Acrocnida brachiata. This
gland, found at the base of the tubefeet, has a complex
structure. This glands stains positively for both acid and neutral
mucopolysaccharides. Transmission electron microscopy
indicates that this gland has a complex structure with both
secretory vesicles and granulated cells present. The function of
this mucus gland has yet to be confirmed but initial observations
suggest that this gland functions primarily in burrow
maintenance.
437
Respiratory quotients and nitrogen excretion in clones of the
sea anemone Haliplanella lineata.
2AMER, W.E.' and L.E. BURNETT. Lake Forest College, IL, and
Univ. of Charleston, SC.
Understanding the evolution of differences in mean
physiological values between populations requires study of
genetically based physiological variation within populations. We
measured oxygen uptake, carbon dioxide output, and ammonia
excretion at 15C in anemones (n=41) from 5 clones in one
population of Haliplanella lineata. Mean variation of CO2
replicates was <2%. RQs were variable within and among
clones, and most (n=24) were > 1.0, indicating lipid synthesis
from carbohydrate, not a surprising result for routine anemone
metabolism (fasted 11.5-25 h). Other values (n=10) were <0.7,
indicating gluconeogenesis from fat. Ammonia excretion was
correlated with oxygen uptake (P<0.0001; r2=0.698), indicating
that intensity of energy demand is strongly related to protein
metabolism in this carnivore. The results highlight the importance
of protein metabolism as a source of variation in energy balance,
and point to an approach using controlled feeding in this passive
suspension feeder. NSF grant DCB-9057315 to WEZ.
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440
Geotaxis in the squid hatchling Loligo pealei.
SIDIE.J.* and B.HOLLOWAY Marine Biological Laboratory,
Woods Hole, MA and Ursinus College, Collegeville, PA.
Long-Finned Squid Loligo pealei deposit eggs in shallow (130 meter) benthic environments. We examined the behavior of
newly hatched (6-12 hour) individuals with regard to phototaxis
and geotaxis. Hatchlings respond strongly to white light at 100
lux (100 lux is preferred over 200 or 400 lux). Hatchlings are
unresponsive to red(650 nm); there is a preference for green(525
nm) over blue(430 nm). Light intensity is important; 100 lux
produces stronger phototactic responses than 200 or 400 lux.
Squid hatchlings (6-12 hours post hatch) are strongly negatively
geotactic. Hatchlings are injected into the bottom of a 1.0 meter
cylinder and their vertical ascent is timed. Typical vertical
swimming velocity is 35-40 seconds/meter. It is not possible to
distract them from this vertical movement using light cues.
Timing is critical; hatchlings older than 12 hours act lethargic and
do not swim vertically. Squid hatchlings respond strongly to light
and gravitational cues which may serve to guide them from eggdeposition depth to surface waters where zooplankton (food)
densities may be greater, especially at the neuston.
436
441
444
Feeding selectivity of native freshwater mussels (Unionidae)
and competiton with zebra mussels.
BAKER, S.M.* and J.S. LEVINTON. State Univ. of New York,
Stony Brook.
Growth and changes in biochemical composition during
larval development of the Stone Crab, Menippe adina
Williams and Felder, 1986.
NATES, S. F.* and C. L. MCKENNEY, JR. U.S. EPA, Gulf Breeze,
FL.
The invasion of the Hudson River by zebra mussels
{Dreissena polymorpha) has resulted in lowered phytoplankton
biomass, a shift in the phytoplankton community, and increases
in native mussel (Family Unionidae) mortality. Our objective was
to examine feeding selectivity in unionid mussels and determine
the potential competition for food between native mussels and
zebra mussels. We examined feeding rate and feeding selectivity
of several species of native mussels, using flow cytometry. We
found that i) Like zebra mussels, most species of unionids we
examined vary their clearance rates according to the
composition of the suspension. Amblema plicata, however,
which as been less severely affected by zebra mussels, does not
vary clearance rate, ii) The degree and direction of selectivity
exhibited by some species of unionids are similar to that of zebra
mussels. A. plicata, on the other hand, has a lower degree of
selection and prefers different particle types. Our results suggest
that varying degrees of competition with zebra mussels for
particular food types may be an underlying factor in the decline
of native mussel abundance and diversity.
Sunlight damage of DNA and subsequent repair in grass
shrimp from an estuary
LEE, R. F.* and G.B. KIM. Skidaway Institute of Oceanography,
Savannah, GA.
445
Sublethal effects of coal fly ash on southeastern
herpetofauna.
HOPKINS, W.A.*, C.L. ROWE, J.H. ROE, D.S. SCOTT, and J.D.
CONGDON. Univ. of South Carolina, Columbia.
DNA strand damage, using the single cell
electrophoresis(comet)method, was determined in grass shrimp
embryos collected at different times from surface waters of a
local estuary. Extensive DNA damage was found in embryos
collected at mid-day in July while embryos collected late at night
on the same day showed significantly less DNA strand damage.
It appeared that the DNA damaged during the day was repaired
in the evening hours. This was verified by transfer of embryos
collected at mid-day to the dark where repair of the DNA took
place within a few hours. Placement of embryos into a solar
simulator, which produced total irradiance of mid-day in the
summer at 34 N, caused DNA damage similar to the damage
produced in the estuary. Large increases in cyclobutane
pyrimidine dimers (18 cyclobutane pyrimidine dimers per 1000
kilobases) were detected in the DNA of embryos exposed to the
solar simulator for 1 hour. There was little or no DNA strand
damage in embryos collected at mid-day in the fall, presumably
due to lower solar irradiance at this time.
Historically, a coal ash disposal area on the Savannah River
Site has been used as a model system for examining the impact
of trace elements on wildlife. Nearly 25 species of amphibians
and reptiles inhabit the polluted site, and many accumulate high
concentrations of toxic trace elements including As, Cd, Cu, Cr,
Se, and Sr. More importantly, amphibians exposed to coal ash
exhibit deformities which affect feeding and swimming,
behavioral modifications that may increase susceptibility to
predation, disruption of endocrine systems, and severe
modifications to energy budgets. In addition, our studies indicate
that reptiles, the most understudied class of vertebrates in
ecotoxicology, are also adversely affected by the wastes.
Snakes, which rely on highly contaminated prey items at the
polluted site, appear to be particularly at risk. Egg laying reptiles,
such as turtles and alligators, transfer significant quantities of
teratogenic trace elements to their offspring. Here we summarize
our comparative studies on amphibians and reptiles, present our
most current research findings, and discuss potential populationlevel ramifications.
443
446
Cold acclimation increases cold hardiness in the hatching
painted turtle.
COSTANZO, J.P.", J.D. LITZGUS, J.B. IVERSON, and R.E. LEE,
Jr. Miami Univ., Oxford, OH and Eariham College, Richmond, IN.
Freezing fails to alter enzyme activities associated with
glycogen metabolism in freeze-tolerant chorus frogs.
SWANSON, D.L* and J.R. EDWARDS. Univ. of South Dakota,
Vermillion.
In northern regions, hatchling painted turtles (Chrysemys
picta) may be exposed to temperatures as low as -12 C during
hibernation in their shallow, natal nests. We investigated how
supercooling capacity, susceptibility to ice inoculation, and the
physiology of turtles change between hatching and midwinter.
Turtles were acclimated to winter conditions by exposing them
to temperatures that decreased from 22 to 4°C over a 5-month
period. Supercooling capacity of newly hatched turtles was low
(mean temperature of crystallization = -6.3'C), but increased by
10'C with cold acclimation. Recently hatched turtles were highly
susceptible to inoculative freezing (mean temperature of
crystallization = -1.TC), whereas cold-acclimated turtles resisted
ice inoculation at low temperatures. Cold acclimation did not
trigger an accumulation of the amino acids or low molecular
mass carbohydrates commonly found in cryoprotectant systems
of other ectotherms. Also, the cold-hardiness strategy used by
hatchling painted turtles does not involve thermal hysteresis
(antifreeze) proteins or ice-nucleating proteins. Supported by the
NSF(IBN 98017087).
Liver increases in glycogen phosphorylase activity, along
with inhibition of glycogen synthetase, are associated with
elevated glucose levels during freezing in some freeze-tolerant
anurans. In contrast, previous studies showed no increase in
phosphorylase activity with freezing in the freeze-tolerant chorus
frog, although phosphorylase was assayed only at 24 h postfreeze in these studies. Chorus frogs were frozen for 5 min, 30
min, 2 h, and 24 h durations. After freezing, glucose, glycogen,
and glycogen phosphorylase and synthetase activities were
measured in leg muscle and liver. Liver and muscle glucose
levels rose significantly (5 to 12-fold) during freezing, but
glycogen showed no significant temporal variation. Moreover,
neither liver nor muscle phosphorylase a or total phosphorylase
activities showed significant temporal variation following
freezing. Neither independent (I) nor dependent (D) forms of
glycogen synthetase were inhibited in liver or muscle during
freezing. Thus, chorus frogs displayed typical cryoprotectant
accumulation compared with other freeze-tolerant anurans, but
freezing did not significantly alter activities of enzymes
associated with glycogen metabolism.
ABSTFIACTS
75A
442
Larval development in decapod crustaceans is associated
with changes in weight and biochemical composition. Larvae of
the stone crab, Menippe adina, were mass-reared under
laboratory conditions (28°C; 20°/ooS) from hatching to the
megalopal stage. Growth in M. adina is exponential throughout
the zoeal stages (y=6.471e 06509x , R2=0.99). Dry weight increased
by 16-fold from Zl to ZV, and by day 28, the average weight for
megalops is 272.5&plusm;48.6 mg. latroscan lipid class analysis
revealed that polar lipids (>64%) and sterol esters (>20%) were
the major lipid classes in larvae at every stage. Free fatty acids
and diacylglycerols were present in small amounts. Overall the
triacylglycerols represented on average 8% of all neutral lipids.
The total lipids of the zoeae and megalops contained palmitic
(16:0), stearic (18:0), oleic (18:1w9) and eicosapentaenoic
(20:5w3) acids as the major fatty acids. Proximate biochemical
composition reveals conspicuous variations during
metamorphosis that appear cyclic in nature.
447
450
Adenosine is a mediator of hypoxia-induced behavioral
hypothermia in toads.
TATTERSALL, G.J.*, A.A. STEINER, L.G.S. BRANCO, and S.C.
WOOD. Northeastern Ohio Universities College of Medicine,
Rootstown, and Universidade de San Paulo, Brazil.
Effect of body-temperature perturbations on locomotory
performance in a diurnal desert rodent, Spermophilus
tereticaudus.
WOODEN, K. M.w and G.E. WALSBERG. Arizona State Univ.,
Tempe.
Hypoxia is well known to elicit a fall in body temperature in a
wide variety of animals. In ectotherms this is accomplished by a
downward shift in behavioral temperature preference (behavioral
hypothermia). The biochemical mediators (e.g. neuromodulators)
that evoke this response are presently unknown. We tested the
hypothesis that adenosine mediates the behavioral hypothermia
of hypoxic toads by using the general adenosine receptor
blocker, aminophylline. Systemic (lymph sac) and central
(intracerebroventricular) injections of aminophylline (25 and 0.25
mg/kg, respectively) caused no change in preferred temperature
during normoxia (21 % 02), however during hypoxia (7% 02),
aminophylline prevented the behavioral hypothermia observed in
the saline controls (normoxic body temperature 24.8 ± 0.3'C,
hypoxic body temperature 19.5 ± 1.1'C, P<0.05). This blockade
was observed with systemic and central aminophylline injections.
Therefore, the present data indicate that centrally, and possibly
peripherally, adenosine is a mediator of hypoxia-induced
hypothermia.
Homeothermic mammals, when exposed to ambient
temperatures outside of their thermoneutral zone, must employ
energetically-expensive mechanisms to maintain a relatively
constant body-temperature. When these animals can no longer
compensate for the difference between ambient and normal
body temperatures, changes in body temperature occur.
Typically, when body temperature deviates from normal by
greater than 1-2~C, locomotory performance and coordination
become severely impaired. We investigated this effect on
locomotory performance by altering body temperature in a
diurnal, desert rodent Spermophilus tereticaudus which is
unable to maintain a stable body temperature under varying
ambient conditions. We measured sprint speed, force
production, and limb cycling frequency in response to
perturbations in body temperature. Results for this species show
only slight, if any, variation in these locomotory parameters when
body temperatures range from 30-42~C. This investigation calls
into question many of the purported selective advantages
attributed to homeothermy at the organismal level.
The effect of cold exposure on bacterial content of the gut
and spleen of adult northern leopard frogs (Rana pipiens).
LEONARD, M.*, I. VATNICK.M. BRODKIN, and M.SIMON.
Widener Univ., Chester, PA and Benedictine College, Atchison,
KS.
Cold exposure during hibernation suppresses the immune
system of frogs. Therefore, frogs emerging from hibernation are
vulnerable until their immune capacity is restored. Our previous
data suggests that cold and acid act synergistically to increase
frog mortality. We have developed a theoretical model that
provides a possible explanation for the effects of environmental
acidification on the natural defense mechanisms of ranid frogs.
This model also suggests a mechanism by which exposure to
acidic environments, upon emergence from hibernation, may
lead to increased mortality of acid-sensitive Rana pipiens. In this
poster we report evidence that endogenous gut- bacteria persist
throughout a six-week cold exposure and may be the source of
systemic infection upon emergence from hibernation into an
acidic environment. This systemic infection combined with
decreased natural defenses may cause increased mortality in
Rana pipiens emerging from hibernation.
449
Diapause development in frozen larvae of the goldenrod gall
fly Eurosta solidaginis (Diptera: Tephritidae).
LEE, JR., R.E.*, J.T. IRWIN, and V.A. BENNETT. Miami Univ.,
Oxford, OH.
Although the goldenrod gall fly, Eurosta solidaginis, has been
extensively studied as a model freeze-tolerant organism,
diapause has not been characterized in this species. We
described metabolic and developmental changes associated
with winter diapause, and examined interactions between tissue
freezing and diapause development. Seasonal measures of
metabolic rate indicated a deep and stable diapause between
Oct. 15 and Feb. 15. This is likely important for energy
conservation as galls often experience diel temperatures
changes up to 20°C. By Jan. 15 (but not Dec. 15) larvae could
develop when warmed to 23°C. Those collected on Jan. 15
required 2 weeks to increase their metabolic rates and pupate
when wanned whereas Feb. 15 larvae increased their metabolic
rates immediately upon warming. Larvae collected on Dec. 15
could not continue development upon warming. However, during
4 weeks of freezing at -22°C the proportion able to continue
development steadily increased, indicating that diapause
development occurred while the larvae were frozen.
76A
451
Characterization of a factor in secondary limb regenerates
that suspends molting in the land crab.
CHANG, E.S.*, X.L. YU, and D.L. MYKLES. Colorado State Univ.,
Ft. Collins, and Bodega Marine Lab, Bodega Bay, CA.
Molting is regulated by molt-inhibiting hormone (MIH), a
neuropeptide synthesized by the X-organs located in the
eyestalks. MIH prevents molting by inhibiting secretion of
ecdysteroids by the Y-organs. In Gecarcinus lateralis, removal
(autotomy) of a limb regenerate (limb bud) during premolt inhibits
growth of any remaining primary (1~) limb buds (LBs) and delays
molting until a secondary (2~=) LB is regenerated. Our purpose is
to identify and characterize factor(s) that mediate the moltinhibiting response of limb bud autotomy (LBA). Extracts of 2~
LBs contain a factor, termed limb autotomy factor-proecdysis
(LAFpro), that blocked molting when injected into premolt
animals. LBA resulted in a decrease in the ecdysteroid
concentration in the hemolymph. MIH is stable to boiling for 15
min, even at acidic pH (0.1 M acetic acid). Molt-inhibiting activity
in 2°° LB extracts was resistant to boiling. However, boiling
extracts at acidic pH destroyed the inhibitory activity. Also,
extracts digested with proteinase K also lost the ability to inhibit
molting. These data suggest that LAFpro is an MIH-like
polypeptide that suppresses the Y-organs. Supported by NSF.
Division of Developmental & Cell Biology
452
Optimization of invertebrate RNA extraction by RNeasy(r).
BHARDWAJ, S.*, D.D. DIMACULANGAN, W.A. McFADDEN, and
J.P. SMITH, III. Winthrop Univ., Rock Hill, NC.
Several methods are now available for rapid and efficient
extraction of whole-cell RNA from tissues, including the
RNeasy(r) kit from Qiagen. While optimizing the use of the kit for
flatworms (Dugesia dorotocephala) and other invertebrates, we
adopted a technique originally recommended for vertebrate
tissue-a phenol/chloroform purification step before loading
samples on the RNeasy(r) column. Like others, we found that this
step improves the yield of RNA from vertebrate tissues from 2 to
3 fold. In invertebrates, however, we obtained dramatic increases
in yield from 5 to 15 fold, bringing the relative yield (ug RNA /mg
tissue) into the same range as vertebrate samples. We conclude
that the extraction removes some material, perhaps the large
quantities of mucus present in the epidermis present in these
invertebrates, that interferes with the binding of RNA to the
column. We also found that maintaining an optimum ratio of RLT
buffer to wet weight of tissue allows for the loading of larger
448
quantities of sample and results in a greater amount of total RNA
bound to the column. Supported by a grant from the Winthrop
University Research Council to D. Dimaculangan, and S.
Bhardwaj.
453
Mechanisms of segment formation in the polychaete
Capitella.
SEAVER, E . C and S.D. HILL. Univ. of Hawaii, Honolulu.
454
Calcium-sequestering cell of the hydroid Hydractinia
symbiolongicarpus.
DANDAR, A / , C. ROGERS, D. STANLEY, and M.B. THOMAS.
Univ. of North Carolina, Charlotte.
Gastrodermal cells of the hydroid Hydractinia
symbiolongicarpus accumulate calcium in the nucleus and
cytosol. The calcium is then transferred to large vacuoles where
crystals visible with the light microscope appear. Gastrodermal
cells capable of producing calcium crystals in their vacuoles
have been identified in uninduced larvae, larvae stimulated to
undergo metamorphosis, the primary polyp, and polyps of a
mature colony. In the mature colony, cells capable of
sequestering calcium are restricted to a region near the base of
the tentacles, yet crystals occur throughout the polyps and their
interconnecting stolonal mat. We propose that calcium
deposited in vacuoles at the base of the tentacles remains in
those cells and is distributed to other locations by migration of
the endodermal epithelium along the mesoglea. The ultimate
destination for the calcium appears to be the substrate to which
the colony is attached. This cell type was not found in larvae or
polyps of three other hydroid genera. Possible roles for this cell
type in H. symbiolongicarpus are discussed. Calcium analysis by
LEO, Inc. is gratefully acknowledged.
455
Sub-lethal effects of exposure to UV-radiation on the
development of blastulas and gastrulas of the antarctic sea
urchin Sterechlnus neumayeri.
HENDERSON, M.J.*, D.KRAKOWSKI, D.KARENTZ, and
I.BOSCH. State Univ. of New York at Geneseo and Univ. of San
Francisco, CA.
Early cleavage embryos were incubated for 4 days at depths
of 1-7 m adjacent to Palmer Station, Antarctica during the spring
1996 and 1997. After quantitation of lethality, morphological
abnormalities were studied in survivors using light and scanning
electron microscopy. Analysis of 3 experiments indicated that an
increase of about 20 microns or less in the thickness of the
columnar blastoderm (ANOVA p=0.03) was the most prevalent
UV-induced abnormality. Blastula and gastrula size were not
affected tp=0.20), however, the volume of the blastocoel was
reduced significantly (19-33%; p=0.01). In the blastocoel of UV
exposed embryos, dense masses consisting of abnormally large
cell bodies and of mesenchyme cells were evident. Such a
density of material in a reduced blastocoel may impair the
normal functioning of mesenchyme cells, possibly accounting for
ABSTRACTS
456
Evolution of left-right asymmetry: Expression of ascidian
nodal.
SCHUMPERT, B.*, A. KEEFER, C.V.E. WRIGHT, and B.J.
SWALLA. Univ. of Washington, Seattle, and Vanderbilt Univ.,
Nashville, TN.
The Nodal gene is a member of the TGF-Beta superfamily of
signalling molecules and has been implicated by experimental
analysis to be involved in the asymmetric looping of internal
organs such as the heart and the gut in vertebrate embryos. We
cloned an ascidian homologue of the vertebrate Nodal gene,
Anr-1, from the ascidian Molgula oculata. Anr-1 is more closely
related to the vertebrate nodals (mouse, xenopus, zebrafish) than
it is to other TGF Beta-like molecules and falls as an outgroup to
the vertebrate nodals. We have analysed the expression pattern
of Anr-1 in M. oculata, a tailed ascidian and M. occulta, a tailless
ascidian using in situ hybridization. Anr-1 is expressed during
gastrulation in three mesenchymal precursor cells on either side
of the blastopore in both species, despite their very different
larval phenotypes. In the neurula and tailbud stages of the tailed
species it is expressed asymmetrically, while expression is
down-regulated in the tailess species. These results suggest that
Nodal may be involved in lateral signalling during gastrulation in
ascidian embryos, and that an ancient left-right asymmetry
signalling evolved during chordate evolution.
457
Developmental basis for the evolution of the cephalofoil in
the bonnethead shark, Sphyma tiburo.
HAENNI.E.G.*, J.P. WOURMS, CA. MANIRE, and R.E. HUETER.
Clemson Univ., SC, and Mote Marine Laboratory, Sarasota, FL.
The cephalofoil, the unique cranial modification characteristic
of bonnethead and hammerhead sharks, involves lateral
expansion and dorsal-ventral flattening of the head. To ascertain
the developmental basis of this evolutionary novelty,
representative stages of the bonnethead shark, Sphyrna tiburo,
from early embryos to neonates were examined using
macrophotography, light microscopy, and electron microscopy.
Width of the cephalofoil, total length of the embryo, and specific
components of the chondrocranium were measured. Changes in
chondrcranial morphology, elongation of the optic nerve, and
expansion of the olfactory sacs were analyzed. Based on our
observations, the morphogenetic events that modify cranial
morphology and produce the cephalofoil are initiated early in
embryonic development. Growth of the cephalofoil exhibits
positive allometry, with respect to the body, especially during the
middle and late phases of development.
458
Cell death during the morphogenetic period of chick
development.
HIRATA, M.* and B. K. HALL. Dalhousie Univ., Halifax, Canada.
Cell death has long been known to play an important role in
morphogenesis. We have examied the spatio-temporal patterns
of cell death in unincubated eggs and in chick embryo of 0-5
days of development using the TUNEL technique. Cell death was
not seen in unincubated eggs containing gastrulae. Prominent
cell death was observed a few hours after the onset of
incubation in the area pellucida. Until stage 6, apoptotic cells
were restricted to the headfold region. Neural tube became
TUNEL- positive at stage 9. Otic, optic and somitic regions
became positive at stage 11. Scattered positive cells were
observed in the branchial arches at stages 16-20. At stages 2425, only limb and tail buds showed intense TUNEL staining.
Supported by Suzuki Scholarship Foundation (MH) and NSERC
(Canada) (BKH).
77A
Both the annelids and arthropods are known for their
segmented body plans, yet the exact mechanisms of segment
addition are understood in very few species in either group.
Segment formation is best understood within the arthropods in
Drosophila melanogaster, and in the annelids in the leech. The
mechanisms by which segments are generated in these two
animals are very different. Furthermore, both have many derived
characters that make it hard to predict if the mechanisms by
which they make segments can be generalized. Therefore, it is
important to include other species, and we have chosen to study
segment formation in the polychaetes, generally considered to
be a more basal group of annelids. We have analyzed patterns of
cell division and cell movements during segment addition in
Capitella sp.l. The incorporation of BrdU was utilized as a marker
of cell division, and we examined cell division patterns for both
embryonic and larval stages. Our results suggest that in
Capitella, segments are generated in a manner quite different
from how they form in the leech, suggesting there may be a
range of mechanisms within the annelids.
the high incidence of abnormal gastrulation and pluteus
formation observed in these treatments. Overall, developmental
abnormalities were statistically more prevalent in treatments
subject to the full solar spectrum (i.e., with UVB) than in
treatments subject to UVA and visible light (i.e., minus UVB).
Abnormalities often occurred to depths of at least 2 m below the
depths at which lethal damage was detected and to the
maximum experimental depth of 7 m.
459
Silk production in the black widow spider Correlation of
various silk types with their glands of origin.
CASEM, M.L.*, A.K. IYER, and A.P. TRAN. Scripps College,
Pitzer College, and The Claremont Colleges, CA.
A characteristics of spiders is their ability to produce a
variety of silk proteins that each serve a distinct function. These
proteins are synthesized and stored by glands within the
abdomen of the spider. Each gland-type produces a unique silk.
The relationship between gland and silk has not been
investigated in the non orb-weaving spiders. We have examined
the silks and silk glands from the cob-weaving spider,
Lactrodectus hesperus (black widow). Comparisions were made
of the spun silks and glandular silks using SDS-PAGE.Consistent
with results from the orb-weavers, dragline silk of the black
widow is synthesized by the major ampullate gland. The minor
ampullate gland also contributes a distinct silk to this fiber. The
scaffolding silk of the cob web is produced by white cylindrical
(tubuliform) glands, while the silks of the egg case are produced
by orange cylindrical glands. Other gland types have been
identified and work is currently underway to determine their
protein products. This work was supported by the Parson's
Research Fund (to A.K. Iyer), the Keck Foundation (to A.P. Tran),
and the National Science Foundation (DBI 99-96072).
460
Preservation of duplicate genes by subfunctionalization.
FORCE, A.', M. LYNCH, and J. POSTLETHWAIT. Univ. of
Oregon, Eugene.
Under the classical model for the evolution of duplicate
genes one of two fates is expected, one member of a duplicated
pair degenerates within a few million years or alternatively one
member of the duplicate pair may acquire a new adaptive
function, resulting in the preservation of both. Empirical evidence
suggests that gene duplicates are preserved in genomes far
more frequently than expected under this model. An alternative
hypothesis is that gene duplicates are frequently preserved by
subfunctionalization, whereby both members of a duplicated
gene pair experience complementary degenerative mutations
that reduce their combined levels and patterns of activity to that
of the single ancestral gene. We have performed computer
simulations to explore the ways in which the probability of
duplicate-gene preservation by complementary degenerative
mutations is modified by gene structure, gene dosage, mutation
rates, and population size. The results of these ongoing
simulations and the probability of duplicate gene preservation by
subfunctionalization will be discussed.
461
Comparative codehopping: Testing a web-based tool for
degenerate primer design.
LECLAIR, E.E.* and G.P. NAYLOR. DePaul Univ., Chicago, IL,
and Univ. of Iowa, Ames.
Degenerate PCR primers can accelerate cloning sequence
fragments from new species. We recently tested CODEHOP, a
Web tool that produces primers degenerate at the 3' end, but
non-degenerate at the 5' end. Because only four consecutive
conserved amino acids are needed to anchor these partiallydegenerate primers, this approach seems particularly useful for
finding highly diverged coding sequences among distantly
related groups. We successfully combined CODEHOP with a
touchdown PCR strategy to clone Dlx, Msx, and Shh gene
fragments from turtles and sharks. After aligning known protein
sequences, we fed selected blocks to CODEHOP to generate
candidate primers,. Primer pairs were selected based on
structural and Tm characteristics. In each case, a single PCR
experiment yielded strong, unique bands for the target genes.
Analysis of the Msx fragments revealed successful cloning of
turtle and shark sequences closely related to vertebrate Msx-1
(GenBank AAD44907, AF172815). Thus the CODEHOP method
78A
462
Molecular cloning and phylogenetic analysis of a novel RNAbinding protein.
KIM, C.B.*, D. BAYARSAIHAN, and F.H. RUDDLE. Yale Univ.,
New Haven, CT.
In the search for transcription factors involved in the
regulation of HoxC8, we have used yeast one-hybrid screening
and isolated several clones. Here we report a cDNA encoding a
novel ribonucleoprotein. The cDNA encodes a polypeptide of
357 amino acid residues. The predicted protein contains two
repeats of a putative RNA-binding domain, each composed of
canonical RNP-1 and RNP-2 motifs. To know relationship of the
novel RNA-binding protein within RNP families, we did
phylogenetic analyses with amino acid sequences. The data
suggest that the novel RNA-binding protein is highly homologous
to a Xenopus hRNPA3 and human FBRNP.
463
HOX gene organization of horn shark, Heterodontus
francisci.
KIM, C.B.*, W. BAILEY, C. AMEMIYA, W. MILLER, N. SHIMIZU,
and F.H. RUDDLE. Yale Univ., New Haven, CT, Boston Univ.,
MA, Penn State Univ., Univ. Park, and Keio Univ., Tokyo, Japan.
To understand the history of vertebrate Hox cluster
duplication, we have isolated two Hox clusters from horn shark,
Heterodontus francisci which is a representative of the
cartilaginous fishes. Two clusters isolated have been sequenced
completely and compared with other vertebrate Hox sequences.
Hox genes of this species have been assigned precisely within
the clusters together with extensive sequence data. The data
suggest that the two clusters are similar to human A and mouse
D clusters, respectively. The present data support the semiconservative duplication of Hox clusters, and the results are
consistent with the relationship topology of
(HoxA/HoxD):(HoxB/HoxC) based on collagen genes. The
present data also suggest more primitive origins of the Hox A
and Hox D clusters. The results are consistent with a duplication
event giving rise to A and D like clusters prior to the evolution of
the cartilaginous fishes. In addtion, many conserved sequences
located in the non-coding regions have been defined. They may
be candidates for control motifs in the Hox clusters.
464
The evolution of CIS-regulatory elements in the DLX3-DLX-7
cluster.
SUMIYAMA, K.* and F.H. RUDDLE. Yale Univ., New Haven, CT.
The Dlx3 and Dlx7 genes cluster together and have
important roles in the development of vertebrates. In mice, Dlx3
is expressed in the teeth, hair follicles, and limb buds which are
derived from epithelial mesenchymal interaction. In some tissues,
Dlx7 expression overlaps with Dlx3.
We obtained human, mouse and zebrafish P1/PAC clones
covering the whole Dlx3-Dlx7 cluster. Comparative analysis
among those genomic sequences showed several highly
conserved motifs other than coding sequence between human
and mouse, and even in zebrafish, not only in the 5' upstream
region, but also in the 3' intergenic region. We sought to identify
cis-elements that are responsible for temporal and spatial
specific expression by using the transgenic mouse system. We
transferred a 80kb insert of the mouse P1 clone which covers
the whole Dlx3-Dlx7 cluster into the pClasper vector by
homologous recombination in yeast cells and inserted LacZ into
the first exon of Dlx3 and injected them into mice embryos.
Reporter gene expression in embryos at different stages was
consistent with endogenous Dlx3 expression. This suggests that
our construct contains the required cis- regulatory elements to
replicate the Dlx3 endogenous expression pattern.
Division of Evolutionary Developmental
Biology
appears robust for PCR cloning of multiple gene products across
distantly related species, yielding cloned fragments useful for in
situ studies or library screening.
465
events in development are conserved, while the upstream
regulators are open to change.
Comparative genomic analysis of the HOXb-2 regulatory
region from selected vertebrates.
SCEMAMA, J.L. - , E.J. STELLWAG, M. SMITH, and K. LABUTTI.
East Carolina Univ., Greenville, NC.
468
Comparative genomic analysis of the Hoxb-2 regulatory
region from Human, Morone saxatilis, Fugu rubripes and
Tetraodont fluviatilis revealed extensive divergence of regulatory
elements between humans and teleosts but remarkable
conservation within the teleosts. We identified a number of
transcription elements common to the Hoxb-2 promoter regions
of vertebrates including a TATA box, AP-2 site, a CAAT box, a
Krox-20 binding site and a Box I motif. However the Hoxb-2
regulatory region from teleosts possessed a NF-1 site not found
in the human Hoxb-2 promoter region, whereas the human
promoter region possessed both GATA-1 and NF-kappaB sites
not found in the teleost promoters. Sequence analysis of the 540
bp located upstream of the start codon of Hoxb-2 using the
GCG program GAP revealed a 88% identity between Morone
and Fugu, a 86 % identity between Morone and Tetraodont and
a 83% identity between Tetraodont and Fugu. The significant
similarities observed in the teleosts Hoxb-2 promoter region
suggest a conserved evolutionary role for Hoxb-2 in the
actinopterygian fishes.
HOX genes in barnacles.
MOUCHEL-VIELH, E', C.RIGOLOT, J-M.GIBERT, and
J.S.DEUTSCH. UniversitE Paris VI, France.
466
Conserved syntenies between zebrafish and human:
Implications for the evolution of the vertebrate genome.
POSTLETHWAIT, J.H.*, Y. YAN, P. NGO, and A. FORCE. Univ. of
Oregon, Eugene.
Living organisms bear the imprint of evolutionary history not
only in their morphologies and gene sequences, but also in the
order of genes on chromosomes. Comparative genomics has
uncovered substantial chromosome conservation among
mammals. Understanding the genome of the last common
ancestor of extant mammals, however, requires comparison to
outgroups with well studied gene maps. We have mapped genes
in the zebrafish Danio rerio to explore the evolution of vertebrate
genomes. Zebrafish has many large chromosome segments
apparently orthologous to large regions of the human genome,
and frequently two such orthologous segments, suggesting a
fish-specific genome duplication, probably at the base of the
teleost radiation. More than half a human chromosome often
appears to have been conserved intact (but with inversions)
since the last common ancestor of zebrafish and mammals. In
other cases, apparent orthologous genes appear on the 'wrong'
paralogous chromosome in zebrafish. These exceptions may
provide insight into the length of time after genome duplications
that individual duplicated chromosomes continued to undergo
recombination during meiosis. These studies will help to
reconstruct the genome of 420 million year old jawed fishes, and
thus understand stasis and variation in the evolution of
vertebrate genomes.
467
Early differences in decapentaplegic expression correlate
with changes in appendage development.
JOCKUSCH, E.I.-, C. NULSEN, and L. NAGY. Univ. of
Connecticut, Storrs and Univ. of Arizona, Tucson.
Metamorphosis is a derived mode of development within
insects. Drosophila melanogaster has taken metamorphosis to
an extreme: virtually the entire adult ectoderm forms from
imaginal discs that are set aside during embryogenesis.
Developmental^, the origin of imaginal discs was a key event in
the evolution of metamorphosis. In order to gain insight into the
genetic modifications that underlie both the evolution of imaginal
discs and differences in appendage form we have undertaken a
molecular comparative analysis of appendage development in
three species with different developmental modes, a
grasshopper, a beetle, and a thysanuran. We find variation in
critical early limb patterning events involving the signaling
molecule decapentaplegic {dpp) that are correlated with
differences among taxa and appendage types. Despite these
early differences, expression of two genes regulated by dpp in
Drosophila, Distal-less and extradenticle, are conserved. This
suggests a model for the evolution of limbs wherein downstream
ABSTRACTS
469
Development and evolution of the echinoderm nervous
system.
SLY, B.J.* and R.A. RAFF. Indiana Univ., Bloomington.
The echinoderm central nervous system is composed of five
radial nerves cords connected to a circular nerve ring, which
perfectly illustrates the pentameral symmetry of this phyla. The
central nervous system can further be divided into the ectoneural
nervous system, which is composed of motor, sensory, and
inter-neurons, and the hyponeural, which is believed to be
strictly motor. Although much is known about the molecular
mechanisms underlying neurogenesis in many invertebrate and
vertebrate species, virtually nothing is known about these
processes in echinoderms. Along with degenerate PCR and low
stringency hybridizations, we have begun a radial nerve cDNA
sequencing project to identify neural specific genes in the sea
urchin Heliocidaris erythrogramma. Putative neural genes are
characterized by their sequence similarity to known genes,
Northern blot analysis, and In situ hybridizations. Expression
patterns of these neural markers allows us to readily observe the
spatial and temporal dynamics of the development of this unique
nervous system, as well as to make comparisons to the better
characterized bilateral nervous systems of other phlya.
470
Comparison of superficial mesoderm morphogenesis and its
role in amphibian gastrutation.
SHOOK, D. R.', C. MAJER and R. E. KELLER. Univ. of Virginia,
Chariottesville.
We have characterized and compared the morphogenesis of
prospective mesoderm that lies in the superficial layer prior to
gastrulation in a number of amphibians, including Ambystoma,
Bombina, and Xenopus. Surface labeling embryos prior to
gastrulation shows the overall contribution of superficial cells to
mesodermal tissues. Timelapse video microscopy of embryo
explants shows the pattern and timing of mesodermal invasion
from the gastrocoel roof and the inner rim of the blastopore
during gastrula and neurula stages. SEM and confocal histology
show the morphological arrangement of invading cells, providing
clues as to the mechanism of invasion. We find large variation
among the amphibians in the invasion of cells into the somites,
in time, place, and amount. Some of these variations in somitic
invasion may be related to variation in gastrulation mechanism.
For example, we directly observed a large number of cells
invading the somites just inside the blastopore in Ambystoma,
which may contribute to the closure of the blastopore; this is in
contrast to Xenopus, in which mediolateral intercalation is
primarily responsible for blastopore closure.
79A
Barnacles constitute a crustacean subclass with sessile and
parasitic species,which is well defined by several
characteristics.In particular all cirripedes are devoid of any
complete abdominal segment. Furthermore the parasitic
rhizocephalan barnacles completely lose segmentation at the
adult stage.By PCR amplification and cDNA library cloning we
have determined the repertoire of Hox genes in the
rhizocephalan Sacculina carcini.VJe have thus isolated the
homologues of all the homeotic genes known in insects except
abdominalA. Furthermore,we have isolated a homologue of the
Drosophila gene fushi-tarazu that we named Diva. In Drosophila,
fushi-tarazu (ftz although located in the homeotic complex is not
a homeotic gene but a pair-rule gene.Studies of the expression
of the Hox genes Antennapedia and AbdominalB and of the Diva
gene during larval development of Sacculina carcini reveal that
Diva has an expression pattern similar to that of the Hox
genes.This result suggests that the ancestral function of Diva/ftz
would have been an homeotic function.
471
Segmentation gene homologues in annelids.
SAVAGE, R.*, A. WERBROCK, S. AIROLDI and K. PINKEY.
Williams College, Williamstown, MA.
We are interested in determining the function of
segmentation gene homologues in annelids. Currently we are
characterizing LZF2 (Leech Zinc Finger) and Caphb {Capitella
hunchback), orthologues to the Drosophila gap gene hunchback
in leeches and polychaetes. LZF2 protein is expressed in
micromere derived tissues such as the prostomium and the
provisional integument, a temporary squamous epithelium that
surrounds the embryo until the formation of the adult cuticle. We
have disrupted the activity of the LZF2 gene following the
introduction of double-stranded RNA (dsRNA) into the leech.
LZF2 dsRNA injection into the D macromere of 4-cell embryos
leads to normal teloblast and bandlet formation but germinal
band formation is severly disrupted. These data suggest that the
epithelial cells may provide signaling cues to the underlying
segmental tissue, and are intimately involved in directing
gastrulation movements. We are also characterizing the
expression of Caphb, a hunchback homologue in the polychaete
Capitella capitata, as part of our effort to determine the role of
this gene in different annelid classes. This research is supported
by NIH grant (HD-57778) to RMS.
Expression of bobcat/P68 during gametogenesis and neural
development in frogs and ascidians.
SEUFERT, D.W.* and B.J. SWALLA. Pennsylvania State Univ.,
Univ. Park, and Univ. of Washington, Seattle.
The p68 group of DEAD-box RNA helicases have recently
been implicated in early animal development, bobcaf, an
ascidian member of this gene family, has been shown to be
differentially expressed in Molgula oculata. bobcat transcripts are
found in small oocytes, it is also expressed in dorsal mesoderm
and in developing neural ectoderm during gastrula and neurula
stages, implicating it in establishing basic chordate features,
including the notochord and neural tube (Swalla et al., 1999.
Development 126:1643). To examine a possible role for p68 in
vertebrate development, we isolated a homolog from the frog
Xenopus laevis. Like M. oculata, p68 is expressed in early
oocytes. Embryonic expression in frog embryos includes neural
plate and migrating neural crest streams. However, mesodermal
expression has not been detected in early Xenopus embryos.
Thus, p68 may function in early neural development in Xenopus
and Molgula. Its role in ascidian mesoderm development,
however, may not be conserved in vertebrates.
473
The non-pigmented cave-dwelling form of the Mexican tetra,
Astyanax fasciatus, contains presumptive melanogenic
neural crest cells.
MCCAULEY.D.W.* and W.R.JEFFERY. California Institute of
Technology, Pasadena, and The Univ. of Maryland, College Park.
Cave- and surface-dwelling populations of Astyanax fasciatus
show developmental differences. We are studying how these
have lead to evolutionary changes within this species. Currently,
we are investigating the developmental basis for pigmentation
differences. We show here that cave-dwelling fish, though
lacking pigment, retain a migratory population of cells that begin
to differentiate as melanocytes; these cells show tyrosinase
activity soon after hatching that remains in seven-week old
juvenile fish. We have also investigated the origin of the
tyrosinase positive cells. Dil injected dorsal to the neural tube in
25-somite stage cave fish embryos labeled cells that migrated
away from the site of injection to take up positions along the
flank. These cells have a location and morphology similar to the
tyrosinase positive cells, suggesting they belong to the same cell
population. These results suggest that presumptive melanogenic
neural crest cells begin to differentiate as melanocytes and that
the developmental switch leading to observed pigmentation
differences occurs late during development.
80A
474
Cranial kinesis in lizards.
KARDONG, K. V.*, T.L. SMITH, and T. H. FRAZZETTA.
Washington State Univ., Pullman, and Univ. of Illinois, Urbana.
Cranial kinesis occurs throughout vertebrates, although not
in mammals, which may account for the irregular attention paid
to its role in the biology of tetrapods. In squamates, it is a major
feature of the feeding apparatus where it can be examined
closely. Previous work has identified a four-bar crank mechanism
as the basis of lizard kinesis. It has been hypothesized to be a
mechanism by which jaw closure on elusive prey is more
precisely accomplished. It also produces a more favorable
orientation of tooth engagement with prey. Therefore, cranial
kinesis has been implicated in food selection and prey sizes,
suggesting that it is a major feeding adaptation addressing
various ecological demands. To more precisely characterize its
role, we examined cranial kinesis by means of strain gauges and
correlated filmed sequences. We discovered that the
mesokinetic joint, the major component of the four-bar crank
system, is active not only during prey capture but also during
intraoral transport. The degree of activity of the mesokinetic joint
was also correlated with a variety of prey variables.
475
Mechanical properties of manatee bone in compression.
CLIFTON, K.B.*, T.J. KOOB.and R.L.REEP. Univ. of Florida,
Gainesville and Shriners Hospital for Children.Tampa, FL.
Florida manatee (Thchechus manatus /af/rosfris)mortality has
been documented since 1974. Watercraft-related mortality,
caused by propeller wounds or impact, accounts for 23% of all
deaths from 1976-1998, and 78% of human-related deaths.
Sixty-six percent of animals killed by impact suffered broken or
luxated ribs. The number of boat-related deaths increased at a
rate of 10% from 1992-1998. Reducing boat-related mortality is
a high priority in recovery efforts. Unlike most marine mammals,
manatee bones are pachyostotic. Stress, strain, and Young's
modulus were calculated for rib bone in compression. Samples
were tested for 10 adult manatees in 3 planes. Compressive
strength was greatest parallel to the long axis of the rib (119
MPa), and weaker in the cranio-caudal (109 MPa) and mediolateral planes (104MPa). Females (99 MPa) were weaker than
males (109 MPa) in the medio-lateral plane. Manatee bone is
weaker in compression than other mammalian bone. This is
consistent with its high density, degree of compactness, and
high mineral content. Results indicate that boat impacts may
inflict fatal injuries even at low speeds.
476
Young's modulus increased in the appendicular skeleton of
mudskippers during their transition to land as determined by
nanoindentation.
ERICKSON, G.M.* and E.T. LILLEODDEN. Florida State Univ.,
Tallahassee, and Stanford Univ., CA.
How the appendicular musculoskeletal system of oxudercine
gobies (aka 'mudskippers') was biomechanically modified during
evolution to allow terrestrial locomotion is a mystery. We are
addressing this question by studying the biomechanics of
primitive aquatic, and derived semi-amphibious and lobed fin
terrestrial gobies. These are serving as phylogenetic snapshots""
of the steps leading to terrestrialization in the clade. One
difficulty encountered has been a means to assess the elastic
material properties of the 'long bones' in the goby appendages
since their small size and shape precludes the use of engineering
beam theory. We have successfully determined Young's
modulus for these elements using nanoindentation (i.e.
miniaturized hardness testing with continuous high-resolution
load and displacement measurement). Aquatic gobies showed
a modulus of 3-5 GPa and terrestrial species 20-22 GPa. These
findings suggest increases in skeletal material stiffness was one
of the means by which terrestriality was facilitated during
mudskipper evolution.
472
Division of Vertebrate Morphology
477
480
Buccal oscillation behavior and body size in the Sonoran
Desert toad (Bufo ah/anus).
CHOQUETTE, D. M.*, J. C. O'REILLY, and E. L. BRAINERD.
Univ. of Massachusetts, Amherst.
Sphincter valves in the pulmonary arteries of turtles.
WYNEKEN, J* and RHODIN, A. G. J. Florida Atlantic Univ., Boca
Raton, and Chelonian Research Foundation, Lunenburg, MA.
478
Ecomorphology of Taiwanese tree frogs.
CHI, K. Duke Univ., Durham, NC.
Ecomorphological studies generally assume a causal
relationship between morphology and ecological habits or
adaptation that is mediated by performance. This study tests
relationships between (1) morphology and performance, and (2)
performance and ecology in Taiwanese tree frogs. It was
predicted that tree frogs with larger toepads would have a better
sticking ability (performance) both intra- and interspecifically,
with sticking ability reflecting the types of microhabitats. The
results showed sticking ability of different species well predicted
their various microhabitat types. However, the form-function
relationship between toepad area and sticking ability differed
intra- and interspecifically. Preliminary behavioral investigation
shows different species have measurably different 'motivation' to
stick onto the inclined substrates, which masks the contribution
of toepad area to testable performance. Structural differences
among toepads may also affect sticking performance. These
findings indicate that more critical empirical work needs to be
done in order to establish the causal relationship between
morphology and function, especially its implications for
ecological adaptation.
479
A small penguin with a big heart: An adaptation for deeper
diving?
DRABEK.C.M.' andY.TREMBLAY. Whitman College, Walla Walla,
WA, and Centre d'Estudes Biologiques de Chize, Centre National
de la Recherche Scientifique, Villier-en-Bois, France.
We compared the heart morphology of the small sized (2.3
kg), deep diving Rockhopper Penguin to the hearts of the small
sized (1.2 kg), shallow diving Little Penguin and to several large
sized (4-25 kg), deep diving Antarctic penguin species. The
Rockhopper Penguin has a heart larger than expected for its
body mass, and its heart weight/body weight is significantly
greater than in the larger sized Adelie Penguin. We found the
Rockhopper's right ventricle weight/heart weight to be
significantly greater than this relationship in both the larger sized
Chinstrap and Adelie penguins. The relationship of the right to
left ventricular weights in the Rockhopper heart is not different
than that of the large sized, deepest diving Emperor Penguin.
The heart morphology of the Rockhopper Penguin might be
related to diving capabilities if its proportionately larger right
ventricle contributes to diving efficiency during foraging by
increasing lung perfusion during surface recovery.
Constrictor or sphincter valves in the pulmonary arteries have
been described in several cheloniid sea turtles species (Caretta
caretta, Chetonia mydas , and Eretmochelys imbricata) as well as
in the leatherback (Dermochelys coriacea). We have found valves
in all marine taxa examined to date (Chelonia, Caretta,
Lepidochelys, and Dermochelys). These valves are closer to the
heart in cheloniids and immediately adjacent to the lungs in
Dermochelys. Several species of freshwater turtles (Trachemys
spp.) also have sphincter valves however, they are
proportionately less thick and longer. Comparisons of marine
turtles with the freshwater aquatic species show this valve is
more robust in the marine taxa. Within the marine taxa all
species are capable divers, yet it best developed in Dermochelys
a diving specialist noted for swimming to extreme depths. The
presence of the valve has been linked to intracardiac shunting by
some authors however the range in degree of development
suggests a functional link to diving as well.
481
The avian paratympanic organ matrix.
SCOTT, M. G. Univ. of Tennessee, Knoxville.
The paratympanic organ, a probable atmospheric pressure
detector, is located on the medial wall of the middle ear of most
birds. The central portion of the elongated, vesicular organ
contains a sensory epithelium from which hair cell bundles
project. The columellar-squamosal ligament attaches adjacent to
the caudal end of the paratympanic organ. The rostral end of the
paratympanic organ is connected to the superior part of the
tympanic membrane by the superior drum-tubal ligament. Air
pressure changes in the external ear can change the tension of
the superior drum-tubal liagment and influence conformation of
the paratympanic organ. In this paper, I describe the
Paratympanic Organ Matrix; an apparent accessory structure
that is aassociated with hair cells in the paratympanic organ. The
lumen of the paratympanic organ is filled with an extracellular,
fiber-form collagenous matrix in which the ciliary bundles of hair
cells are embedded. I propose that the function of the
Paratympanic Organ Matrix is to directly couple conformational
changes in the paratympanic organ with the ciliary bundles of
hair cells; a function analagous to the function of other
accessory structures in the octavolateralis system.
482
The possible role of medicinal herbs in regulating activity of
the pineal gland: Revelations on an integrated system of
biological rhythms.
HYDE, M. L Eastern New Mexico Univ., Portales.
There has been an explosion of research done on biological
rhythms and the activity of melatonin and the pineal gland in the
brain. I propose here a mechanism for the activity of several
medicinal herbs, especially yarrow (Achillea maculatum) and St.
Johnswort {Hypericum perforatum) on the pineal gland, based
upon my own observations and on observations made by others
from a study of the literature on their biochemical activity. The
action of melatonin is ubiquitous, helping to integrate many
systems of the body, including the nervous, reproductive,
gastrointestinal, cardiovascular, skeletal, and immune systems.
There are many physiological disorders and normal activities of
animals which may be explained by the link between melatonin
activity day/night cycles, with seasonal effects as well. I suggest
other areas for future research.
483
Historical biogeography of short-tailed shrews based on
analysis of skull and mandibular shape.
STEVENS, W.P.*, M.N. JEFFRIES, and T.J. GAUDIN.
Georgetown College, KY, and Univ. of Tennessee at
Chattanooga.
Blarina brevicauda occurs in the Appalachian highlands and
the karyotypically distinct B. carolinensis in lowlands of the
ABSTRACTS
81A
Because Bufo alvarius (Sonoran Desert toad) grows over
1000 fold in body mass while maintaining very similar linear
proportions, it is an ideal model organism for understanding the
influence of body size on movement. This growth pattern allows
the influence of body size to be measured while most other
aspects of biomechanical design remain constant. Buccal
oscillation in anurans is a behavior in which the floor of the
buccal cavity is rhythmically raised and lowered, and air flows in
and out of the nares without being pumped into the lungs.
Previous studies on feeding in B. alvarius found that the duration
of feeding movements scaled as Length 1 0 (L 1 0 ) , which led to
the prediction that buccal oscillatory frequencies would scale as
L 1 0 . Using pneumotachography, we quantified buccal
oscillations of resting individuals. Specimens ranged from 60mm
to 160mm in body length. Data were regressed against body
length. Frequency scales as approximately Length ~°- 5 , flow as L
10
, and volume per oscillation as L 1-7 . Our results to this point
do not meet predictions based on feeding behavior, predictions
based on modeling the hyoid apparatus as a geometrically
growing spring, or predictions based on the known scaling of
metabolic rate. This project was supported by NSF IBN
9875245.
Mississippi valley and the Atlantic coastal plain. The species
boundary in intermediate physiographic provinces such as the
Cumberland plateau of Tennessee has been controversial.
Although these species are generally distinguished by size,
specimens of intermediate size occur along the border between
the species ranges and fossil material tends to be larger than
either extant species. We constructed 'size-out' morphometric
variables based on within-species PCA of 18 cranial, mandibular,
and dental measurements. We were then able to identify a
number of significant differences between brevicauda and
carolinensis in the transformed variables and to use 'size-out'
Mahalanobis distances to predict species membership.
Preliminary results indicate that the species boundary in eastern
Tennessee is determined by a combination of elevation and the
position of the Tennessee River.
484
Phylogenetic and functional influences in odontocete enamel
prism structure.
WERTH, A.J.* and C.B. WOOD. Hampden-Sydney College, VA,
and Providence College, Rl.
485
Morphological comparison of the buccal apparatus in two
bivalve commensal carapfdae.
PARMENTIER, E*, J.L. CASTRO-AGUIRRE, and P.
VANDEWALLE. Univ. of Uege, Belgium, and CICIMAR, La Paz,
Mexico.
487
A morphological staging system for the comparison of early
ontogenetic development among species of teleost fishes.
SHARDO, J.D. Univ. of South Alabama, Mobile.
Teleost embryos and larvae undergo a progression of rapid
changes during early ontogeny. To compare early ontogenies,
one must be able to identify comparable levels of development
among individuals of different species. A sequence of
morphological stages, each defined by 1-2 fundamental features
of teleostean development, is the basis for a comparative
system. A comparison of development of two species of teleosts
illustrates the system. Between American shad and Atlantic
salmon there are large differences in egg size, incubation
temperature, hatching time, larval size and habitat; however,
both species follow the sequence of stages. For example,
cleavage cell number is a fundamental feature defining Stages 16. But cell divisions become asynchronous in salmon at an
earlier stage than in shad, thus concurrent developmental
characteristics are not necessarily coupled to a stage's defining
criteria and may occur at different stages in different species.
The two species are compared from Stages 1-15, through
development of optic vesicles. This methodology can provide a
source of developmental characters for phylogenetic analysis.
Supported by NSF grant DEB 9707530.
488
Morphometric analysis of chondrocranial shape in Rana
tadpoles.
LARSON, P.M. Ohio Univ., Athens.
Onuxodon fowleri and Encheliophis dubius are two
Carapidae (pisces) that both shelter in bivalves and have a
similar diet. Their cephalic diet and muscles are constituted with
trhe same pieces that differ froom one another in size, shape
and fitting. The buccal system of O. fowleri seems more
appropriate to bite and carve a prey whereas this one of E.
dubius could allow to seize and suck in the food. A simulated
displacement of the quadrate-mandible articulation of £ dubius
in order to induce it to coincide with the structures of O. fowleri
is realised. This displacement induces the suspensorium and
jaws of E. dubius to superpose with their analog pieces in O.
fowleri. Such modifications of places and shapes and their
influences on their annex pieces could so explain in part the
species biodiversity.
Nearly all studies of the larval anuran chondrocranium to
date have been qualitative in nature and few have examined
variation in structure among closely related species. Examination
of chondrocranial morphology in Rana larvae indicates that
qualitative variation is limited. Of nine North American species
examined, only Rana sylvatica has distinct characteristics that
differentiate it from other species. Recently developed geometric
morphometric techniques have the potential to elucidate
structural variation that may not be qualitatively obvious by
testing for statistical differences in shape. Thus, relative warp
analysis is used here to analyze chondrocranial shape variation
among species of Rana. A plot of the first two relative warps
identifies three distinct clusters of species. These clusters
correspond to members of the Rana catesbeiana group, Rana
pipiens complex, and Rana sylvatica respectively. Quantitative
discrimination of chondrocranial shape between these species
groups indicates that geometric morphometric techniques may
be useful in discerning morphological variation among species
when qualitative structural variation is limited.
486
489
Brain size depends on life history depends on metabolism.
FROST, G. T. Univ. of Georgia, Athens.
Skull development in the West African caecilian Geotrypetes
seraphini (Gymnophiona: Caeciliidae).
REISS, J.O.* and J.C. O'REILLY. Humboldt State Univ., Arcata,
CA, and Univ. of Massachusetts, Amherst.
Analysis reveals that among precocial mammals large body
size in neonates is associated with large relative brain size in
adulthood. A parallel pattern holds among precocial birds:
relative adult brain weight is positively correlated with relative
egg weight. Large neonates result from a prolongation of
prenatal somatic growth, permitting delayed maturation and an
extension of high-allometry fetal brain growth, resulting in a
larger adult brain size. Altricial birds rely on intensive posthatching parental care rather than large eggs, and they mature at
a large fraction of adult body size, resulting in the highest levels
82A
Development of caecilians has been studied primarily in
genera with primitively aquatic larvae and those with highly
derived viviparity. Here we describe posthatching development
of the skull in a species with an intermediate reproductive mode,
involving birth of altricial young that feed exogenously on the
mother's skin. At birth (approx. 32 mm TL), the dermal skull is
already quite well ossified. However, in the neurocranium,
cartilage remains in the entire nasal capsule (including the lamina
SEM analysis of Amazon river dolphin or bouto (Inia
geoffrensis) teeth reveals distinct Hunter-Schreger bands
(alternating layers of 'decussating' enamel prisms). H-S bands
have been reported in the Ganges susu {Platanista gangetica)
and are found in various living and fossil condylarths, ungulates,
and carnivores. Their presence in basal pakicetid and
basilosaurid archaeocetes suggests they may be retained as
symplesiomorphic features in Inia and Platanista, especially since
'river dolphins' are putatively plesiomorphic (their relations
remain unclear). Systematic inferences based on H-S bands may
be misleading, however, as it is thought they evolved in
response to greater bite forces in taxa with strong occlusion.
Since odontocetes with less complex enamel tend to have
simple, conical teeth that do not occlude during feeding, their
non-decussating, poorly prismatic (or even aprismatic) enamel
may reflect reversion or loss. Inia bears distinct cusps on its rear
teeth which are presumed to crush prey, yet Platanista has
conical teeth used less for grasping or crushing, implying that
phylogenetic factors override functional ones here.
of encephalization among the birds. The pattern holds even
across vertebrate classes: the neonates of birds and mammals
are larger in relation to adult body size than are those of most
fishes, amphibians and reptiles, and as adults they tend to be
more highly encephalized. Birds and mammals are also
endothermic, which suggests that brain enlargement may be
favored by higher metabolic rates. I argue that elevated
metabolism allows greater parental investment in individual
offspring, thus permitting neonatal enlargement, hence larger
adult brain size. Consistent with this hypothesis, analysis reveals
that among precocial mammals higher metabolic rates are
associated with larger neonates, thus favoring brain enlargement.
orbitonasalis), the anterior neurocranium, the otic capsule, and
the occiput. In the visceral skeleton, the palatoquadrate,
Meckel's cartilage, and columella are still partly cartilaginous, as
is the hyobranchial apparatus. As the young grow, cartilage is
gradually replaced, largely by perichondral bone. By 53 mm TL
cartilage remains only in isolated parts of the nasal capsule, the
side wall of the skull in mid-orbit, and the occiput, as well as the
visceral skeleton. In sum, Geotrypetes retains more cranial
cartilage at birth than do free-living larvae or viviparous young of
other taxa, reflecting its small size and altriciality.
490
Ontogenetic scaling of poison glands in Dendrobates
pumilio.
CONDON, K.', R. SAPORITO, and M.A. DONNELLY. Florida
International Univ., Miami.
491
Developmental tempo and pattern in Tree Swallow flight
muscle.
HERMANSON, J.W.* and D.W. WINKLER. Cornell Univ., Ithaca,
NY.
The growth and development of the pectoralis muscle
(sternobrachialis and thoracobrachialis) in nestling (aged 3 d to
19 d) Tree Swallows was examined using standard histological,
histochemical and immunocytochemical techniques. Pectoralis
development paralleled body mass in that muscle mass
increased linearly to d 12, and showed a 20% decrease between
d 12 and d 16. Day 19 nestlings were volant and achieved body
and pectoralis masses that were not significantly different from
adults. The cross sectional areas of pectoralis muscle fibers
exhibited linear growth during the period from d 3 to d19 and did
not show any decrease in fiber area associated with the
reduction in body and muscle mass that occurred between d 12
and d 16. Thus, the loss of muscle mass appeared to be
confined to non-contractile components of the muscle.
Histochemical and immunocytochemical profiles of the muscle
suggested that all fibers were aerobic (high NADH activity) and
fast twitch (all fibers homogeneous with respect to ATPase
activity). Further, glycolytic (anaerobic) fibers were present in the
pectoralis muscle by d 12 and a mosaic of fiber types (high and
low glycolytic fibers) exists from this age onwards.
492
Morphological effects of injected progesterone on western
fence lizards, Sceloporus occidentalis.
CAMPBELL, M. California State Univ., Chico.
This study investigated hormonal action in lizards of the
family Iguanidae, in particular progesterone, and its
morphological effects on S. occidentalis Baird and Qirard.
Progesterone in oil was injected subcutaneously in an attempt to
induce morphological changes in chromatophores and femoral
pores in S. occidentalis. Differences in effects upon male and
female S. occidentalis injected with progesterone were
assessed, as were age differences.
ABSTRACTS
493
Cell death in epidermal cells of Xenopus laevis following
retinol treatment in vitro.
MENON, V.-, A. VANDIVER, S. BARANOWITZ, and J. MENON.
William Paterson Univ., Wayne, NJ.
Programmed cell death has been extensively studied during
early development in amphibian metamorphosis. Role of retinol
in inducing cell death is also very well documented. Here we
characterize by a whole-mount TUNEL staining as well as
scanning and transmission electron microscopy (SEM and TEM)
cell death in tail of Xenopus laevis tadpoles following retinol
treatment. High incidence of cell death was detected in TUNEL
stained tail epidermis following retinol treatment. SEM studies
revealed a loss of microvilli and intercellular connections as well
as pitting of epidermal surface. TEM studies confirmed a near
total loss of the bilayered epidermis exposing collagen bundles.
Epidermal cells that remained displaced clear total apoptotic
features. Degenerative changes were apparent in the muscle
bundles where mitochondrial morphology was also altered. This
is the first documented apoptotic inducing effects of retinol in
tadpole tail, a larva specific organ.
494
Effects of retinol on metamorphosing tadpoles and
melanocyte distribution in two species of anuran tadpoles,
Rana catesbelana and Xenopus laveis.
REN.K.*, V. MENON, C. BRANDONI, and J. MENON. William
Paterson Univ., Wayne, NJ.
Vitamin A and its derivaties (retinoids) have multiple effects
on the control of epithelial cell differentiation and
morphogenesis. The thyroid hormone-induced tissue remodeling
that occurs during metamorphosis is accomplished by
heterodimerization of thyroid hormone receptors and retinoic
acid receptors. We found complete inhibition of metamorphosis
when tadpoles of Rana catesbeiana and Xenopus laevis were
treated with retinol palmitate (1IU/ml and 0.5 lU/ml respectively)
during premetamorphoic stage. However, this effect was found
to be stage specific. When R. catesbeiana were treated with
retinol during late prometamorphic stage, there was no effect on
the progress of metamorphosis. Additionally, light microscopic
observations were made on thyroid gland following retinol
treatment. Retinol also affected melanocyte morphology, in
terms of reduction in their numbers as well as dendritic
processes in both the species of tadpoles.
495
Temperature-independent effects of water viscosity on larval
swimming speed in the small-mouthed salamander
Ifimbystoma texanum).
SUGALSKI, M.T. New England College, Henniker, NH.
The effects of temperature-independent changes in water
viscosity on the swimming performance of small-mouthed
salamander larvae were investigated. Burst swimming speed
trials were conducted on both hatchling and developed larvae in
water at 10 and 20 C, and in a methyl cellulose solution at 20 C
whose kinematic viscosity had been adjusted to that of 10 C
water (i.e., 20(10) C). Burst swimming speed trials were
conducted in a 25 cm diameter arena and were measured by
video analysis. Although the swimming speed of hatchlings was
significantly affected by temperature-independent changes in
water viscosity (27% decrease from 20 C to 20(10) C), larger,
83A
Dendrobatid frogs are endemic to the Neotropics.
Approximately 100 species of brightly colored, toxic frogs are
placed in one of four genera {Epipedobates, Dendrobates,
Minyobates, and Phyllobates) and all produce alkaloids in
granular skin glands. Dendrobatid tadpoles are not toxic and it is
not known if granular gland density varies as a function of body
size. To determine if size confers an advantage, we surveyed
granular gland size and density in a population of Dendrobates
pumilio, collected from the La Selva Biological Station in
northeastern Costa Rica. Patches of skin from the dorsum were
fixed and embedded in paraffin for histological sectioning. Total
gland counts from a single specimen (15 mm SVL) show that
18.7% of the dermal surface is occupied by poison glands.
Poison glands are uniformly distributed across the skin and
average 51.3 +/- 8.34 urn in diameter. Preliminary analysis of a
second individual (SVL 23 mm) shows poison glands average
120.0 +/- 11.83 urn in diameter. Assuming the number of glands
remains constant, this suggests that glands increase in size at a
rate greater than that of body size, thus toxicity increases with
Although there were a few statistically significant changes in
scale color and femoral pore size, the overall evidence
suggesting progesterone is involved in morphological color
change is weak, especially, when compared to changes elicited
by androgens in other studies of S. occidentalis. However, there
were significant (p< .01) changes in dorsal green coloration in
adult males. These findings reinforce past studies where
epinephrine and norepinephrine influenced dorsal green
coloration in S. occidentalis by contraction of melanophores
exposing underlying iridophores. The induction of morphological
color changes in S. occidentalis is the subject of continuing
exploration in determining a possible correlation between
progesterone and pigmentation as observed in other lizards.
more developed larvae were not. These results suggest that the
combined physical and physiological effects of temperature
fluctuations are especially limiting to the performance of
hatchling larvae and may contribute to high larval mortality rates
in the field.
496
Elastic storage and dynamic gearing in jumping dogs.
CARRIER, D.R.* and C. S. GREGERSEN. Univ. of Utah, Salt Lake
City.
497
Locomotion of kinematics of African elephants.
FAMINI, D.J.\ J.R. HUTCHINSON, and R. KRAM. Univ. of
The largest extant animals provide information about how
large extinct animals may have moved. However, there are few
published data for the locomotion of elephants. We measured
the locomotion kinematics of 4 trained, adult (1600-4600 kg)
African elephants moving from 0.8-4.1 m/s. Elephants used a
lateral sequence walk with lateral couplets at all speeds. Unlike
smaller quadrupeds, the elephants' footfall patterns did not
qualitatively change even though they reached Froude numbers
of nearly 1.0. The lowest single leg duty factor was 0.52 (same
fore and hind). Relative phase averaged 0.17 at all speeds. Many
speed estimates for large extinct animals (e.g. sauropods)
involve footprint analysis. We tested Alexander's equation (1976)
for estimating speed from trackways. Inputting our stride length
(SL) and hip height (L) data into that equation overestimated the
actual speeds of the slowly moving elephants by 2-fold. This
suggests that sauropods may have moved even slower than
previously thought. The best fit equation for our elephants was:
velocity (m/s) = 0.1 g 0 - 50 SL2-94 L"2-44. Thanks to Six Flags
Marine World, Vallejo CA. Supported by UCB URAP stipend to
DJF and NIH grant AR44688 to RK.
498
Testing the sagittal rebound hypothesis for the epaxial
muscles.
RITTER, D.A.*, P.N. NASSAR, M.M. FIFE, and D.R. CARRIER.
Heidelberg College, Tiffin, OH, Bryn Mawr College, PA, and Univ.
of Utah, Salt Lake City.
The epaxial muscles of mammals are generally thought to
'stabilize the trunk' during locomotion. We are attempting to
provide a more precise understanding of their function.
Electromyography of the epaxial muscles, dorso-ventral
kinematics of the trunk, and ground reaction forces were
collected from trotting dogs. The timing of muscle activity
relative to locomotor forces is consistent with the hypothesis that
the epaxial muscles counteract sagittal rebound of the trunk,
which tends to sagittaly flex the trunk during the latter half of the
support phase. The epaxial muscles are uniquely situated to
counteract sagittal flexion of the back, as they are the only
muscles dorsal to the vertebra] column, and thus the only
84A
499
Epaxial muscle morphology of robust vs. emaciated harbor
porpoises.
STEGALL, V.S.*, W.A. MCLELLAN, R.M. DILLAMAN, A.J. READ,
and D.A. PABST. Univ. of North Carolina -Wilmington, and Duke
Marine Lab, Beaufort, NC.
Harbor porpoises, Phocoena phocoena, in the northwest
Atlantic provide an opportunity to study apparent starvation in a
wild cetacean. Emaciated porpoises stranded along the midAtlantic coast were compared to robust porpoises killed in
fishing operations. Based on comparative studies of starvation,
we hypothesized that emaciated porpoises would have smaller
epaxial locomotor muscle masses, smaller muscle fiber
diameters, and higher percentages of slow twitch fibers.
Preliminary comparative results demonstrate that emaciated
porpoises have 30% less epaxial mass, though the ratio of body
mass to epaxial mass remains similar. Fast twitch fiber diameters
of emaciated porpoises are 40% smaller and slow twitch
diameters 19% smaller. Also, emaciated porpoises have 1 1 %
more slow twitch fibers. The magnitude of these changes in
muscle composition is similar to that observed in laboratory
animals in phase III of starvation, where extensive muscle
catabolism is exhibited, which often leads to death. These
results support the hypothesis that starvation contributes to
harbor porpoise mortality in the mid-Atlantic.
500
Ontogeny of contractile properties of gastrocemius muscle
in Japanese quail.
BURDICK, J. B.* and J. M. OLSON. Villanova Univ., PA.
Galliform birds hatch with some locomotor and thermogenic
capabilities, despite restricted conditions in ovo. The hindlimb
muscles are particularly important for both locomotion and
shivering thermogenesis, however, little is known about the
ontogeny of contractile properties. We measured standard
isometric and isotonic contractile properties of the
gastrocnemius muscle (GM) isolated from Japanese quail
between the ages of 1d and adult. Body mass increased -25fold during posthatch development, and GM cross-sectional area
increased -19-fold. Both peak isometric twitch (P^) and tetanic
(PJ forces (N/cm2 muscle) did not change with age (ANOVA,
p>0.25), nor did the time to reach P ^ and 90%P o (p>0.15). In
contrast, the time to reach 50% relaxation after a twitch
decreased significantly with increasing age (p<0.005). Maximal
isotonic shortening velocity decreased markedly between d4 and
d8 (8.95±0.75 SE l/s to 5.13±0.44 l/s; p<0.0001), and decreased
further to 3.05±0.11 l/s in adults. The high shortening velocities
and contractile forces contribute to the remarkable locomotor
and thermoregulatory capabilities of young chicks.
501
Comparison of aerodynamics of gliding frogs vs. non-gliding
frogs using flow visualization.
BISHOP, K.L. Univ. of California, Berkeley.
Gliding has evolved in two families of tree frog. Aerodynamic
stability is important to a glider because it helps to maintain its
direction of gliding without active postural adjustments. A
previous study measured aerodynamic stability of three species
of frog and found no significant difference between gliding and
non-gliding morphologies. However, this study was unable to
ascertain the contribution of individual morphological features of
the frog to its aerodynamic stability. Another previous study
indicated a complex interaction of local flow fields around the
parts of the frog's body. In our study we sought to discover
whether the flow field around a gliding frog differs from that of a
non-gliding frog and how the flow fields around individual body
parts interact. We compared the flow fields around models of
Two mechanisms have been suggested to improve jumping
performance: storage and recovery of elastic strain energy and
dynamic gearing. We used recordings of ground forces from
dogs jumping vertically to 1) calculate the external work
produced at individual limb joints and 2) calculate the changes in
gear ratio of the limb extensor muscles. Our analysis of external
work suggests that when dogs are allowed to take one
locomotor cycle prior to the execution of a jump, 25% of the
positive work may be due to the recovery of elastic strain
energy. This suggests that dogs do employ elastic storage
during maximal accelerations. Observed changes in gear ratio at
the wrist, elbow, ankle, and hip joints are not compatible with
maximization of muscle power during active shortening.
Nevertheless, the gear ratios at the shoulder and knee joints did
increase during jumping in a manner that could facilitate power
production. The extensor muscles of the knee joint were found
to produce a large proportion (25%) of the positive work of the
limbs, and the vastus lateralis muscle was found to undergo
extensive active shortening. These observations suggest that
dynamic gearing at the knee joint may contribute to the jumping
performance of dogs.
muscles capable of extending the back. Data from trunk loading
experiments supports this hypothesis. When weights (4 - 10% of
body weight) are positioned in the middle of the animals back,
such that they would increase sagittal rebound, rectified
integrated area (RIA) of the longissimus dorsi muscle increases
significantly. When the same amount of weight is positioned over
the limb girdles, RIA does not increase significantly.
three species of frog in the family Hylidae chosen to represent
three levels of specialization for gliding, from a highly specialized
glider to a non-glider. Flow visualization provided insight into the
physical mechanisms which dictate aerodynamic stability.
< 0.05) while opening lever ratios were not (ANCOVA, P > 0.05).
Asymmetry of the feeding apparatus is expected to have
consequences for feeding performance, resource utilization, and
ultimately direct fitness.
502
505
A comparison of launch characteristics in gliding and
nonglinding mammals.
ESSNER, JR., R. L. Ohio Univ., Athens.
Two-stage development of the lower-jaw depressing
mechanism and its consequences for feeding in larval red
drum.
TURINGAN, R.G. Florida Institute of Technology, Melbourne.
503
Body rotation critical to modification of takeoff trajectory in
birds.
EARLS, K.D. Brown Univ., Providence, Rl.
Analysis of starling takeoff at a range of trajectories has
shown that not only are the hindlimbs the primary source of
propulsion for ground takeoff in birds, they may also be the
primary agent of trajectory modification. The hindlimbs of
starlings (Sturnis vulgaris) produce greater vertical forces with
increasing trajectory, but this force increase does not propel the
center of mass along a more vertical trajectory. Instead it creates
a larger moment about the center of mass, and causes the body
to rotate more rapidly at higher trajectories. This increased body
rotation positions the body more vertically at liftoff, and trajectory
of takeoff is higher as a result. Analysis of whole body
mechanics, to separate the contributions of the wings and
hindlimbs to takeoff, indicates it is unlikely that the wings are
producing greater propulsive force during the first wingbeat of
vertical takeoffs in starlings. Instead, the increased body rotation,
powered by the hindlimb, re-orients the lift vector produced by
the wing relative to vertical and horizontal axes. Thus we
measure that the wings are producing greater vertical impulse,
when in fact they may be acting in a mechanically similar way at
all trajectories.
504
Lateral asymmetry in pleuronectiform feeding biomechanics.
FRANCIS, JR., A.W.* and R.G. TURINGAN. Florida Institute of
Feeding biomechanics has been well characterized for
bilaterally symmetrical percomorph fishes, but has not been well
described for asymmetrical pieuronectiforms. As a representative
pleuronectiform, post-metamorphic Paralichthys dentatus were
examined for asymmetry between blind and ocular sides.
Juvenile flounder were preserved and measured for standard
length, wet weight, developmental stage, maximum jaw gape,
and biomechanical features of the lower jaw. Biomechanical
features included closing in-lever, opening in-lever, and out-lever
arms. Lever ratios were calculated from lever anns by dividing
each in-lever by the out-lever. Data for all individuals (n = 94)
was transformed prior to testing with ANCOVA or ANOVA.
Closing in-lever (ANOVA), opening in-lever (ANCOVA), and outlever (ANCOVA) arms were all significantly different between
sides IP < 0.05). Closing lever ratios were also found to be
significantly different between blind and ocular sides (ANOVA, P
ABSTRACTS
The relationship between feeding performance and
development of the mechanism of lower-jaw depression in larval
red drum (Sciaenops ocellatus) was investigated. Examination of
double-stained specimens and observation of live fish from
hatching through metamorphosis revealed that: (1) 3- to 6-day
old (age at first feeding) larvae depressed their lower jaw by
using a simple system that involved only the hyoid-mandible
coupling (hyoid stage); and (2) a more complex functional linkage
involving the hyoid- and opercular series-mandible linkages
(hyoid-opercular stage) were utilized to depress the lower jaw in
larvae around metamorphosis. Laboratory experiments revealed
that first exogenous feeding occurred in larvae at the hyoid
stage. However, less than 50% of these larvae consumed prey.
In contrast, almost 100% of the larvae at the hyoid-opercular
stage did consume prey. Furthermore, first-feeding larvae
preferred small, non-elusive prey whereas their conspecifics at
the hyoid-opercular stage consumed larger, more elusive prey. It
appeared that the two-stage development of the lower-jaw
depressing mechanism influenced the ability of larval red drum
to capture prey.
506
Diet and cannibal morphology in tiger salamanders.
WURST, G.Z.* and J.F. MULL. Weber State Univ., Ogden, UT.
Cannibalism in tiger salamanders {Ambystoma) is triggered
by drying in ephemeral breeding ponds and accompanied by
morphological changes, e.g., larger heads and increased
size/numbers of vomerine teeth. Casual field observations led us
to a systematic dietary study of local Ambystoma tigrinum
nebulosum, correlating prey size/identity with morphometric
variables. We analyzed stomach contents from preserved larval
salamanders, anesthetized and formalin-fixed in the field.
Phantom midges (Chaboridae) were present in 90% of the
stomachs, representing 80% of invertebrate prey. Only one
stomach was suspected to contain a conspecific larva. Prey
measurements regressed against salamander size (SVL) and
number of vomerine teeth (VOMT) yielded significant positive
correlations (r2 = 0.23, p<0.0001 - SVL; r2 = 0.22, p = 0.001 VOMT.) We propose ecological explanations for the relative rarity
of natural cannabalistic events in salamanders with relevant
morphology and behavior.
507
Fiber types in tongue muscles of three frogs that feed
differently.
PETERS, S.E. Univ. of North Carolina at Charlotte.
Standard histochemical techniques characterized the muscle
fiber types present in tongue protractor (genioglossus = GG) and
retractor (hyoglossus = HG) muscles of anurans. Tongues from
three frogs, LJtoria caervlea (mechanical pulling tongue), Bufo
marinus (inertial elongation), and Dyscophus guinetti (hydrostatic
and inertial elongation) were compared and results interpreted in
light of previous data on contractile properties. HG was least
variable; in all species, it is composed of uniformly large (6080um) FG fibers surrounded by small (20-30um) FOGs. The total
HG cross-section was relatively smallest in Bufo, agreeing with
its smaller isometric force production. GG is more complex. In all
three species, it consists of three regions: a ventral mass that is
mostly FGs with scattered FOGs; an intermediate layer of mixed
fibers, mostly FOGs, with some FGs and SOs. The most
superficial layer is also FGs and FOGs. GG in the most endurant
species [LJtoria and Bufo) had the largest number of SOs and
FOGs in the outer two layers. Dyscophus had fewer SOs in the
intermediate layer and fewer FOGs in the outermost layer. No
tonic fibers were found.
85A
Precise descriptions of behavior are key to understanding
the role of morphology in the evolution of novel locomotor
modes. While a number of studies have compared morphological
variation among gliding and nongliding forms, there is currently a
lack of insight into the extent of variation among locomotor
behaviors. This has led to questions concerning the degree of
specialization necessary for gliding versus nongliding (leaping)
locomotion. In order to address this concern I have examined
the kinematics and kinetics associated with the launch phase of
a gliding mammal, the flying squirrel, Glaucomys volans. Five
individual G. volans were filmed launching from a 1.5 meter
horizontal platform with high-speed video at 250 frames/second
in simultaneous lateral and dorsal views. Landmarks were
digitized on the limbs, tail, and body and converted into 3D
coordinates. Locomotor behavior was examined by generating
kinematic profiles of angular motion at the limb joints and tail.
These data were subsequently compared with launch data from
nongliding forms (other squirrels and primates), in order to
evaluate behavioral variation and further delineate the roles of
morphological elements during the initial stage of the glide.
508
Structural flexibility of the intestine of python (Python
molurus).
STARCK, J.M.' and K. BEESE. K. Friedrich-Schiller-Univ., Jena,
Germany.
The intestine of pythons shows a considerable degree of
structural flexibility. When fasting, the gut's size is only one third
of that in the functional state, i.e., when digesting. We used
transcutaneous ultrasound imaging for morphometric data
acquisition to study the patterns of structural flexibility in
response to feeding in Burmese pythons. We applied
immunohistology, electron microscopy, and flow cytometry to
study the cellular mechanisms that drive such flexibility.
Ultrasonography reveals a rapid, repeated, and reversible upand down-regulation of gut size in response to feeding. Within
two days after feeding, average gut size increases to three times
the fasting size. Immunohistochemistry and ultrastructural
studies show that size increase of the gut is based on a
hydraulic mechanism supported by the properties of a
pseudostratified epithelium of the mucosa epithelium. Cell
proliferation does not contribute to the up-regulation of intestine
size. Gut size increases without biosynthesis of new tissue.
509
Since the Paleognathae were recognised as a single taxon,
the group has caused controversy in both systematics and
functional morphology. The clearest difference between the
Paleognathae and the Neognathae is the morphology of the
Rerygoid-Palate Complex(PPC), which operates the movement
of the upper bill. We used functional morphology to analyse the
PPC and to come to an explanation for the bifurcation between
the Paleognathae and the Neognathae. A movement analysis
showed that the Paleognathae have a standard feeding method,
which appears to be primitive within birds. Cranial kinesis and
tongue movement are very limited. An X-ray based displacement
analysis showed that the PPC is moveable and acts as a fourbar system, but seems to be more constrained in its movement
than in neognathous birds. When compared with other
rhynchokinetic birds, the Paleognathae do not posses the
specialised bending zones in the upper bill, and muscle forces
are relatively small. Based on these findings an evolutionary
pathway is proposed in which the paleognathous PPC is
reinforced for stability and cranial kinesis is a relic from ancestral
morphologies.
Recent Progress in Crustacean
Endocrinology: A Symposium in Honor of
Milton Fingerman
510
Crustacean pigmentary-effector hormones: Chemistry and
functions.
RAO, K.R.* and J.P. RIEHM. Univ. of West Florida, Pensacola.
Crustacean pigmentary-effector hormones are known to be
members of two distinct neuropeptide families found in
arthropods: RPCH/AKH and PDH/PDF families. Whereas the
crustacean RPCH has a conserved octapeptide sequence, the
related AKHs in insects show certain residue substitutions and
variations in chain length. The crustacean PDHs and the related
insect PDFs are all octadecapeptides, with considerable
sequence similarity. Despite similarities in the sequences of
RPCH and AKHs, their prepropeptides show almost no
homology except that they share the basic organization
consisting of a signal peptide (SP), a region encoding RPCH or
AKH, and a precursor-related peptide (PRP). Similarly, except for
precursor organization (SP, PRP, PDH or PDF), the SP and PRP
components of the PDH precursors in crustaceans do not show
any resemblance to the corresponding components of PDF
86A
511
Crustacean hyperglycemic hormone in the lobster
Physiology, localization, and release.
CHANG, E.S.*, R. KELLER, E.A. KRAVITZ, B.S. BELTZ, and S.A.
CHANG. Univ. of California, Bodega Marine Lab., Univ. of Bonn,
Germany, Harvard Medical School, Boston, MA, and Wellesley
College, MA.
Crustacean hyperglycemic hormone (CHH) belongs to an
arthropod-specific family of neuropeptides. We have measured
alterations in the levels of circulating CHH under various
conditions of environmental stress, including thermal, salinity,
and hypoxia in the lobster, Homarus americanus. We have
identified CHH immunoreactivity in neural tissue distinct from the
eyestalk x-organ/sinus gland complex. In particular we
demonstrate CHH activity in pairs of cells in the subesophageal
ganglion and in neurosecretory cells along thoracic second
roots. The latter cells are spontaneously active, temperature
sensitive, and inhibited by serotonin and octopamine, both of
which are found in nerve terminals in their immediate vicinity.
CHH is released from these cells upon depolarization in the
presence of calcium. A dramatic peak in hemolymph CHHimmunoactivity is observed at the initiation of ecdysis, even in
eyestalk-ablated lobsters. Supported by the California Sea Grant
College Program.
512
Further studies on signaling pathways for steroidogenesis in
crustacean Y-organs.
SPAZIANI, E.* and T.C. JEGLA. Univ. of Iowa, Iowa City and
Kenyon College, Gambier, OH.
Y-organs secrete ecdysteroid hormones, responsible for
molting and regeneration. Ecdysteroidogenesis is controlled
(negatively) by the eyestalk peptide, molt-inhibiting hormone
(MIH), mediated by rises in cAMP/cGMP. Research in crabs and
crayfishes explored the signaling paths in activated Y-organ cells
(MIH absent) that connect the MIH receptor and genes which
express ecdysteroidogenic enzymes. Low external Ca ([Ca]e)(1 10 mM) stimulates ecdysteroid production, whereas high [Ca]e
(100 mM) depresses production to 0-[Ca]e level. Our direct and
indirect evidence does not support a role for the phospholipase
C-IP3 messenger system in ecdysteroidogenesis. Thapsigargin
(releases intracellular Ca) and intracellular Ca chelators were
moderately inhibitory. Ca channel agonists at lower doses were
stimulatory. Ca channel (L-type) antagonists were inhibitory, the
higher doses inhibiting steroidogenesis to below basal levels.
Protein kinase C (PKC) activators stimulated steroid production
in crabs but were inhibitory in crayfishes. These data support a
regulatory role for external Ca, not internally-releasable Ca, that
operates by affecting PKC via Ca cycling at the plasma
membrane.
513
Molecular cloning, expression, and tissue distribution of
crustacean molt-inhibiting hormone.
WATSON, R.D. Univ. of Alabama at Birmingham.
Synthesis of ecdysteroids by crustacean Y-organs is
negatively regulated by a neuropeptide molt-inhibiting hormone
(MIH). Our laboratory has cloned cDNAs encoding MIH of two
brachyurans: the blue crab {Callinectes sapidus) and the
Dungeness crab (Cancer magister). Each cDNA encodes a 113
residue prohormone (proMIH). Each proMIH includes a 35
residue signal peptide and a 78 residue MIH. Northern blot
analysis revealed eyestalk MIH mRNA levels were elevated
during postmolt and intermolt, and low during premolt in C.
sapidus. Recombinant MIH (rMIH) was produced in insect Sf9
cells using a baculovirus expression system, and in E. coli using
a pET vector. The recombinant peptide generated using
bacuiovirus was of the predicted size, was MIH-immunoreactive,
Functional morphology and evolution of the pterygoid-palate
complex of paleognathous birds.
GUSSEKLOO, S.W.S.* and G.A.ZWEERS. Leiden Univ., The
Netherlands.
precursors in insects. PDHs occur in multiple forms in certain
crustaceans, and their pigmentary effects are known. PDFs are
implicated in the regulation of circadian rhythms in the nervous
system of insects. These peptides open new opportunities to
elucidate the molecular biology, structural relationships, and
functional attributes of neuropeptide families.
and had MIH bioactivity. The peptide expressed in £ coli was of
the predicted size and was MIH-immunoreactive, but did not
possess MIH bioactivity. The prokaryotically-expressed peptide
was purified and used for production of antisera.
Immunocytochemical studies revealed anti-rMIH
immunoreactivity in the X-organ/sinus gland complex of C.
sapidus. Supported by NSF IBN-9419916 and NOAA/MS-AL Sea
Grant NA86RG0039.
514
Regulation of claw muscle atrophy and limb regeneration in
decapod crustaceans.
MYKLES, D.L*, X. YU, and E.S. CHANG. Colorada State Univ.,
Ft. Collins.
515
The roles of ecdysteroid hormones, retinoids, and other
growth factors in the control of limb regeneration in the
fiddler crab Uca pugilator.
HOPKINS, P.M. Univ. of Oklahoma, Norman.
In the fiddler crab, Uca pugilator, regeneration of walking
legs can be divided into two stages. The first stage, basal
growth, begins with the formation of a limb primordium at the
site of the wound. Over a time course related to the physiology
and growth cycle of the animal, blastemal cells proliferate and
differentiate into an intact miniature limb. The second stage,
proecdysial growth, primarily represents a hypertrophy of the
regenerate. The size of the limb bud increases due to muscle
deposition and water uptake, with the emergence of a functional
appendage occurring at the next molting of the body
exoskeleton. The roles of ecdysteroids (and their receptors UpEcRs) as well as growth factors such as retinoids (and their
receptors - UpRXRs), and fibroblast growth factors in the
regulation of limb regeneration will be discussed. Nucleic acid
and immunological probes for receptor gene expression have
been used to study these problems. For limb buds and other
potential hormone-responsive tissues, steady-state receptor
transcript levels relative to changes in hormone titer over the
molt cycle have been established. Limb buds from both the
basal and proecdysial stages of limb regeneration express
UpEcR and UpRXR transcripts and immunoreactive fibroblast
growth factors have been identified in early blastemas.
516
Regulation of the crustacean mandibular organ.
BORST, D.W. Illinois State Univ., Normal.
The crustacean mandibular organ (MO) is controlled at least
partially by neuropeptides from the sinus gland (SG), a
neurohemal organ located in the eyestalk. Several groups have
isolated and sequenced CHH-related peptides from the SG that
inhibit the MO in vitro. More recently, we have detected a SG
compound that only affects the MO in vivo. This indirect
regulator of the MO is currently being characterized and its
physiological importance assessed. Both classes of
neuropeptides affect MF synthesis by lowering the activity of
ABSTRACTS
517
Hormonal regulation of crustacean morphogenesis and
reproduction.
LAUFER, H. Univ. of Connecticut, Storrs.
Methyl farnesoate (MF) is the unepoxidated form of the most
abundant insect juvenile hormone, JH III. MF has been found in
more than thirty-five species of Crustacea and is synthesized by
the crustacean mandibular organs (MOs). The administration of
MF to adult females of several crustacean species results in a
stimulation of vitellogenesis. In addition, MF increases in both
reproductive males and females. Thus, MF is likely to be a
reproductive hormone for both sexes. In addition, the presence
of MF in larvae at critical premolt stages interferes with their
progression through metamorphosis. Likewise, juvenile males
and females retain their juvenile status in the presence of MF at
critical times during the premolt rather than progressing to a
more differentiated state. MF may function as a morphogen in
Crustacea. Our understanding of reproductive maturation and
morphogenesis of Crustacea has been enhanced by a more
thorough appreciation of the role of methyl farnesoate.
518
Crustacean vitellogenesis: The role in oocyte development.
TSUKIMURA, B. California State Univ., Fresno.
During the complex life history of oocytes, the accumulation
of yolk protein, or vitellin (Vn), is one of the many intercellular
changes that occur during maturation. To understand the
regulation of vitellogenesis, we have characterized the Vn of the
ridgeback shrimp, Sicyonia ingentis, as a 322 kDa protein and
composed of 3 subunits. Against the purified Vn, we developed
an anti-Vn antibody with which we were able to develop Western
blot assay and an ELISA. Using the ELISA, injections of
progesterone, hydroxyprogesterone and estradiol did not
increase hemolymph levels of yolk proteins in sexually quiescent
shrimp. We found that these hormones were also ineffective in
elevating hemolymph levels of vitellogenin in Homarus
americanus. A likely reason is that gonad inhibiting hormone may
prevent any oocyte development. We have determined that S.
ingentis hepatopancreas and ovary both produce mRNA to yolk
proteins by screening a cDNA library. We have found a 2.9 kB
cDNA in both tissues that express (using lambda gt-11) proteins
that bound to the anti-Vn antibody. We are in the process of
sequencing the cDNA to construct a probe, with which we will
screen common hormones for their effectiveness in stimulating
vitellogenesis.
519
Yolk synthesis in the marine shrimp Penaeus Vannamei.
QUACKENBUSH.L.S. Univ. N.C.at Wilmington.
The marine shrimp Penaeus vannamei produces about
200000 yolk laden eggs during each ovarian maturation cycle.
Each egg contains about 50 ng of yolk protein about 10% of the
total protein of the egg. Based on in vitro assays both ovarian
tissue and the hepatopancreas are capable of yolk protein
biosynthesis. Eyestalk ablation removes the endocrine centers
which normally regulate reproduction and is used to induce
ovarian maturation. After eyestalk ablation yolk biosynthesis
proceeds rapidly in both the ovaries and the hepatopancreas.
Yolk proteins are transported in the hemolymph (1mg/mf) during
this process. Eyestalk endocrines are capable of both inhibiting
and stimulating yolk biosynthesis in vivo and in vitro. Steroid
hormones may also be involved in shrimp yolk
87A
Molting in decapod crustaceans is controlled by the Xorgan/sinus gland complex, which secretes a molt-inhibiting
hormone (MIH) that suppresses production of molting hormone
(alpha-ecdysone) by the Y-organs. Timing of molting events (e.g.
limb regeneration, exoskeleton synthesis, claw muscle atrophy)
is regulated by circulating titers of ecdysteroid, which increases
during proecdysis. Molting is induced by autotomy of at least 5
walking legs, which are then regenerated during proecdysis. If
one of these primary limb buds (LBs) is autotomized, growth of
remaining primary LBs stops and molting is delayed 2-3 weeks
to allow for regeneration of a secondary LB. Secondary LBs
contain a factor (LAFpro), which appears to be a MIH-like
polypeptide that supresses secretion of ecdysteroids by Y
organs. LBA reduced circulating ecdysteroid in the blood of land
crabs. In order to study the effects of limb bud autotomy on claw
muscle atrophy, cDNAs encoding calcium-dependent
proteinases (calpains) were isolated. One of the clones is
expressed at high levels in muscles but not other tissues,
indicating its value as a marker for activation of protein
degradation in atrophic muscle.
farnesoic acid O-methyl transferase (MeT). MeT catalyzes the
final step in MF synthesis. Its activity is correlated with
hemolymph levels of MF, and is elevated by procedures
(eyestalk ablation and stress) that elevate MF levels. In a
collaborative study with other investigators, our lab has
characterized this enzyme in the lobster and isolated its putative
cDNA clone. The activity of this enzyme and its expression are
being investigated in lobsters at different developmental stages
and under different physiological conditions. Both of these
studies should provide further clues regarding about the role(s)
of the MO in crustaceans. (Supported by IBN 93-19206 from the
NSF and a NIH-AREA grant).
biosynthesis.Supported by Florida Sea Grant Florida Dept. Ag.
and US Mexico Foundation.
genes appear to be similar to those of annelids and mollusks,
the ectoproct's Hox genes appear to be considerably different.
524
HOX genes in the Ecdysozoa.
GRENIER, J.K. Univ. of Wisconsin-Madison.
The androgenic gland was found to have a central role in the
maintenance of the endocrine balance between male and female
components of the reproductive system in intersex individuals of
the crayfish Cherax quadricarinatus. In the presence of the gland
the ovary of the intersex was arrested at a primary-vitellogenic
stage while the testis was active, its absence permitted the onset
of secondary- vitellogenesis while spermatogenesis ceased. In
the crayfish this gland exerts its effect on the expression of
certain polypeptides, sex characters and aggressive behavior.
These recent findings illustrate the importance of the androgenic
hormone in the regulation of sexual differentiation in sexually
plastic as well as gonochoristic crustacean species. Recent
research of the androgenic gland, its function and the nature of
its secretion will be discussed.
Understanding the early evolution of animal body plans
requires knowledge both of metazoan phylogeny and of
comparative developmental genetics. One set of ancient,
conserved genes which contribute to the diversity of animal
body plans are the Hox genes. Changes in the number,
expression, and function of these genes is thought to have
facilitated the radiation and diversification of animal body plans.
In order to better characterize the distribution of Hox genes in
protostome animals, I have cloned the Hox genes of a
centipede, an onychophoran, and a priapulid worm. Each of
these animals has a characteristic set of Hox genes which
distinguishes them as members of the Ecdysozoa, one of the
two major clades of protostome animals. This analysis shows
that the common ancestor of the Ecdysozoa had at least eight
Hox genes. Comparative analysis of Hox expression patterns
indicates that Hox genes are deployed in different body regions
among the panarthropods and often demarcate a transition in
limb identity, consistent with a role in patterning distinct body
regions. While no new Ecdysozoan Hox genes have arisen in the
last 540 million years, evolutionary changes in Hox expression
patterns and regulatory networks have likely contributed to body
plan diversity.
HOX Clusters and the Evolution of
Morphology
521
Early HOX evolution as revealed by cnidarians.
FINNERTY, J.R.* and M.Q. MARTINDALE. Boston University, MA
and University of Hawaii, Honolulu,
The last common ancestor of the Bilateria (the bilaterally
symmetrical triploblastic animals) was a pre-Cambrian marine
invertebrate. Its morphology and ecology are unknown to us but
its genetic architecture is becoming better understood. This
urBilaterian possessed a Hox cluster consisting of perhaps 8
distinct Hox genes (Finnerty and Martindale 1998) and a
ParaHox cluster consisting of 3 or 4 distinct genes (Brooke et al.
1998). These genes play critical roles in patterning the A-P axis
of bilaterian animals and therefore represent part of the genetic
foundation for the bilaterian radiation. How did this foundation
arise? The origins of Hox and ParaHox genes remain obscure.
However data from outgroup taxa such as the phylum Cnidaria
(corals hydras jellyfishes and sea anemones) are beginning to
yield powerful insights. Phylogenetic analyses of recent data
from sea anemones identify specific classes of Hox genes and
ParaHox genes in the Cnidaria (Finnerty and Martindale 1999).
Furthermore cnidarians possess a compact Hox cluster linked to
an even-skipped ortholog. These findings establish the origin of
Hox and ParaHox genes prior to the split between Cnidaria and
Bilateria.
522
HOX gene expression in hydra.
BODE, H. University of California at Irvine.
No abstract submitted.
523
A survey of HOX genes in lophophorates: Implications for
metazoan phylogeny.
HALANYCH, K. M.* and Y. PASSAMANECK. Woods Hole
Oceanographic Institution, MA.
We surveyed the articulate brachiopod Terebratalia
transversa and the ectoproct Bugula turrita for Hox like genes
using PCR based approaches. Genetic similarity and
reconstructed gene-geneologies were used to identify Hox gene
homologs and make inferences concerning metazoan evolution.
Information based on Hox genes confirms the earlier report by
Halanach et al. (1995) that ectoprocts and brachiopods fall in a
clade called the Lophotrochoza. These findings are in agreement
with a recent report from de Rosa et al. (1999) that brachiopods
have pratostome-like Hox genes. Although the brachiopod Hox
88A
525
Polychaete HOX genes and comparative analysis of
expression patterns: Implications for body plan
regionalization.
IRVINE, S.Q.* and M.Q. MARTINDALE. Yale Univ., New Haven,
CT, and Univ. of Hawaii, Honolulu.
The Hox genes are widely regarded as candidates for
involvement in major evolutionary change in body plan
organization. We examine Hox gene expression data for several
taxa, in relation to recent work on the polychaete annelid
Chaetopterus. The analysis reveals certain divergent patterns,
such as differences in the extent of gene expression domains
along the body axis, and differences in timing of the onset of
expression. These differences in pattern represent evolutionary
changes in Hox gene regulation between lineages. Here we
compare these regulatory differences and their correlation with
morphological differences. We also discuss the molecular and
genetic evidence supporting the importance of these differences
for evolutionary changes in body plan morphogenesis.
526
HOX and para-HOX genes in flatworms.
BAGUNA, J.*, E. SALO, J. TAULER, E. JIMENEZ, J.R.
BAYASCAS, and J. G A R C I A - F E R N A N D E Z . Universitat de
Barcelona, Spain.
Flatworms (phylum Platyhelminthes) are favourite organisms
in Developmental Biology and Zoology because of their
extraordinary powers of regeneration and they may hold a pivotal
place in the origin and evolution of the Bilateria. Hox genes play
a key role in setting up the new anteroposterior pattern in the
former and as qualitative markers of phylogenetic affinities
among bilaterian phyla in the latter. We have searched for Hox
and ParaHox genes in several flatworm groups spanning from
freshwater triclads to marine polyclads and more recently the
acoels the likely earliest extant bilaterian. We have isolated and
sequenced seven Hox genes from the freshwater triclad Girardia
tigrina and four Hox and one ParaHox genes from the polyclad
Discocelis tigrina. Recent data from the acoel Paratomella rubra
will also be reported. Expression of Hox genes has been studied
in adult organisms and during regeneration and shown to bear a
nested pattern with graded anterior expression boundaries.
Comparison of flatworm Hox sequences to other metazoans
support its clear affinities to spiralian lophotrochozoans a result
also supported from recent 18S rDNA sequence data.
520
The androgenic gland and sexual plasticity in crustaceans.
SAGI, A. Ben Gurion Univ. of the Negev, Israel.
527
530
Body-patterning gene evolution and the diversification of
echinoderms.
LOWE, C.J.* and G.A. WRAY Univ. of California, Berkeley and
State Univ. of New York at Stony Brook.
HOX-clusters, genome duplications, and the evolution of
diversity in vertebrate body plans.
MEYER, A.' and E. MALAGA-TRILLO. Univ. of Konstanz,
Germany.
The echinoderms are a particularly interesting phylum to
investigate body patterning gene evolution as they are
characterized by two very distinct body plans during their
development: Their larvae are bilaterally symmetrical and exhibit
unusually diverse early life history strategies within the group,
whereas the adult body plan is characterized by five fold radial
symmetry, acephalization and derived organ systems. The single
echinoderm hox gene complex has been cloned in the labs of
Rudy Raff and Eric Davidson. Expression analysis suggests that
only a few of the hox genes are expressed during larval
development, and most of them are expressed with the onset of
the developing adult rudiment. We have been investigating the
role of different genes in the elaboration of the echinoderm body
plan. Some of these homeobox-containing genes, such as distalless and orthodenticle, exhibit variable expression patterns even
within a single family of echinoderms. More recently genes
involved in the dorso-ventral patterning of the chordate neural
tube and arthropod nerve cord have been cloned from an
asteroid. Hopefully their expression patterns will reveal some
clues to early deuterostome evolution and the origin of
chordates.
Sequences from the entire complement of HOX genes and
their genomic organization from three fish species, the zebrafish,
fugu and medaka have already been published. We now
determined the Hox gene architecture in a cichlid fish. The
surprising finding is that in fish the HOX genes are arranged in at
least seven rather than the expected four HOX gene clusters that
seem to be the norm for sarcopterygian vertebrates. This
suggests that an earty ancestor of the modern fish lineage
experienced an additional genome duplication and explains why
descendents of the lineage leading to land vertebrates typically
have only half the number of genes that are found within a
particular gene family in fishes. Variation in HOX gene numbers
and genomic architecture of HOX-clusters among the fish is
discussed in light of diversity of aspects of their body plans.
Homeobox genes in ascidian development: Evolution
through heterochrony.
HINMAN, V.' and B. DEGNAN. Univ. of Queensland, Brisbane,
Australia.
Comparison of molecular developmental processes utilised
by representatives from the chordate subphyla have contributed
to a recent increase in the understanding of the evolution of
morphological diversity. Unlike other chordate taxa ascidians
and thaliaceans have a biphasic life-history. Embryogenesis
results in a tadpole larva with notochord dorsal hollow nerve
cord and axial musculature. During metamorphosis the embryo
undergoes a dramatic alteration in body plan and these tissues
degenerate and morphogenesis of the endoderm rudiment
begins forming an anterior pharyngeal basket endostyle and
posterior gut tube in the juvenile. It is widely accepted that
present day ascidians evolved from a free-living ancestor in
which these structures developed concomitantly. We present
data on the expression of a number of developmental regulatory
genes (e.g. Otx Pax2/5/8 Cdx) during the embryonic and
metamorphic development of the ascidian Herdmania curvata.
These expression patterns suggest that the evolution of the
novel ascidian adult body plan was not accompanied by a
deployment of such genes into novel pathways but by a
heterochronic shift in tissue-specific expression."
529
Zebrafish HOX genes and hindbrain patterning.
PRINCE, V.E.* and J.M MCCLINTOCK. Univ. of Chicago, IL
We are using the zebrafish as a convenient model system to
investigate the evolution of hox gene patterning functions. The
zebrafish has 7 hox clusters rather than the 4 clusters reported
for tetrapod vertebrates, probably due to a genome duplication
event in the teleost lineage. We are concentrating on the
zebrafish homologues of Drosophila labial, the members of hox
paralogue group 1. Zebrafish have 4 genes in this group where
mouse has only 3. Interestingly, the zebrafish hoxbib gene has
an expression pattern in the developing hindbrain very similar to
that of mouse Hoxa-1, while the zebrafish hoxaia gene has
taken on a later, novel expression pattern that extends into the
midbrain. Mis-expression of hoxbib leads to a partial homeotic
transformation of the hindbrain, where rhombomere 2 acquires
multiple molecular and neuroanatomical characteristics of
rhombomere 4. Ectopic zebrafish hoxaia produces a similar
transformation, but unlike hoxbib this gene is not normally
expressed in a time or place consistent with a role in setting up
rhombomere 4 identity. We are now extending our analysis to
incorporate the other members of paralogue group 1.
ABSTRACTS
Axial specification by HOX genes in vertebrates.
BURKE, A.C. Wesleyan Univ., Middletown, CT.
The colinear anterior to posterior expression domains of the
Hox genes in vertebrate embryos is strongly correlated with
regional changes in vertebral morphology. The limbs of tetrapods
are consistently aligned with specific areas of the vertebral
column. However control of limb development is apparently
situated in the lateral plate mesoderm and has been
experimentally shown to be independent of an axial Hox code
(Cohn et al. 1997 Nature 387:97-101). We have used
experimental manipulation of chick embryos to test the causal
role of Hox genes in patterning derivatives of the paraxial
mesoderm. Hox expression in heterotopically transplanted
segmental plate responds in a manner consistent with a
patterning role for these genes in the morphological behavior of
the transplants. Expression is maintained in dorsal paraxial
regions where patterning is also intrinsic to the donor site of the
graft. However expression is apparently lost in cells that migrate
into the host lateral plate environment and form appropriate
host-level muscles. This arrangement could enable increased
plasticity in the evolution of transpositional variation in the
vertebrate body plan.
532
New experimental observations concerning bilaterian
origins.
CAMERON, R. A.*, K. PETERSON, and E. DAVIDSON. California
Institute of Technology, Pasadena, CA.
We have proposed that the invention of set-aside cells and
pattern formation processes rendered micrometazoan animals
capable of developing the widely divergent body plans seen
suddenly at the start of the Cambrian. Our proposals predict that
the latest common ancestor of bilaterian groups must have been
an indirect developing form and that the genetic regulatory
mechanisms that pattern the adult body are specifically utilized
in the larval phase. Using new systematic, molecular and
paleontological evidence, we argue that the latest common
ancestor of echinderms and hemichordates was a maximallydeveloping form, as was the latest common ancestor of molluscs
and annelids. We discuss new evidence on Hox gene expression
patterns which supports the notion that both sea urchins and
polychaete annelids use Hox genes ina similar fashion during
larval development. Thus, the latest common ancestor of
annelids and echinoderms (which for phylogenetic reasons must
also be the latest common ancestor of bilaterians) was a
maximally-indirect developing organism that used set-aside cells
and regional specification mechanisms (e.g. the Hox gene
complex) for construction of the adult body plan.
89A
528
531
533
535A
Molecular evolution of floral homeotic genes.
PURUGGANAN, M.D. North Carolina State Univ., Raleigh.
Feeding at the fringe: Scaling up marine plant-herbivore
interactions.
DETHIER, M.N. Univ. of Washington, Seattle.
Flower development in plants is controlled by several
homeotic loci, many of which are members of the MADS-box
regulatory gene family of transcriptional activators. Evolutionary
analyses indicates that MADS-box genes that control flower
development form well-supported gene groups, while other more
basal members of the gene family appear to be involved in
vegetative or embryonic development. The major expansion of
this gene family in plants appears to coincide with the rise of
land plants ca. 480 mya. More recent work also suggests that
variation at these loci may contribute to ecologically-significant
quantitative variation within plant populations.
534
Probing the arthropod bauplan with HOX genes.
KAUFMAN,!".*, A. ABZHANOV, and C. HUGHES Indiana Univ.,
Bloomington.
New Approaches to Studies of Marine
Plant-Animal Interactions
535
Novel algal-micrograzer interactions within the marine
plankton.
STROM, S.L.* and G. V. WOLFE. Shannon Point Marine Center,
Western Washington Univ., Anacortes.
Relative to terrestrial ecology, the study of plant-animal
interactions in the ocean's planktonic realm is in its infancy. Most
research has focused on identifying 'structural constraints'.
However, planktonic protists, the dominant consumers of plant
biomass in the sea, have sophisticated sensory and behavioral
capabilities. Here I present several novel findings regarding
interactions between protist grazers and their microalgal prey,
some of which closely parallel important interactions in terrestrial
communities. For example, marine microalgae may use
chemicals as defenses against micrograzers. Several abundant
and widespread microalgal taxa produce sulfur compounds that
appear to depress feeding rates in protist consumers. We have
also found that light interacts strongly with the digestion of
pigmented algae inside of protist grazers. In combining the
above observations, it is tantalizing to speculate that marine
microalgae may produce light-activated chemical defense
compounds in a manner analogous to some terrestrial plants.
Overall, the potential for chemically mediated behavioral
interactions between planktonic plants and animals appears to
be much greater than generally realized.
90A
536
Recruitment on Hawaiian macrophytes: Do pre- or postsettlement processes keep plants free from fouling?
SMITH, CM.*, M.G. HADFIELD, and L J . WALTERS. Univ. of
Hawaii, Honolulu, and Univ. of Central Florida, Orlando.
Some sessile invertebrates are rarely found on Hawaiian
algae or seagrasses. We considered 3 potential explanations for
the lack of fouling by H. elegans and 8. neritina on 40
macrophytes: 1) larvae avoid settling on plant surfaces due to
chemical or physical (morphology, surface energy) traits of the
plant, 2) physical characteristics of the plant surfaces deter firm
attachment of epiphytes, and 3) plant flexibility is greater than
animal flexibility, and promotes shedding of attached
invertebrates. Overall, both pre- and post-settlement processes
effectively prevented recruitment of H. elegans on these tropical
macrophytes. Pre-settlement defenses kept H. elegans from
attaching to 23 plant species; post-settlement processes could
explain the absence of this invertebrate from the remaining 17
species. One of the tested alternatives could explain the lack of
fouling by 8. neritina on only 18 species of macrophytes. Thus,
other processes, such as predation or larval supply, must also
influence the distribution of B. neritina on Hawaiian macrophytes.
536A
Plant-animal interactions in seagrass-dominated
ecosystems.
HECK, JR., K.L.* and J. F. VALENTINE. Dauphin Island Sea
Lab/University of South Alabama.
Two well known generalizations about seagrass-dominated
ecosystems are that seagrasses provide shelter from predators
and enhanced food supplies for associated animals and that
grazing of seagrasses is of little importance in coastal food
webs. A review of existing data and our own work shows strong
evidence for the role of shelter although with significant
modifications from existing generalizations. We also find
increasing evidence that sheltered animals produce positive
effects on seagrasses. There is however inconsistent evidence
for enhanced food supply in seagrass habitats. With regard to
seagrass herbivory its demographic and food web importance
has been largely underestimated owing to methodological
problems and idiosyncrasies of previous study sites. Herbivores
can and at times do consume the bulk of aboveground
production but herbivory can stimulate new shoot growth at
intermediate grazing levels. It also appears that destructive
overgrazing of seagrasses is prevented by the grazing-induced
loss of seagrass shelter for juvenile herbivores. Overall we
conclude that existing generalizations about plant-animal
interactions in seagrass-dominated ecosystems require
substantial revision.
The discovery of the homeobox and the Homeotic Gene
Clusters (HOM-C) has had two major impacts on evolutionary
thought and research. Firstly, the presence of the clusters in all
of the bilateria indicated that the molecular mechanisms for the
regulation of development evolved early. Thus the evolutionary
biologist must be concerned with explaining how an essentially
common set of molecular paradigms have been used to produce
the array of morphologies found in extant and fossil animals.
Fortunately the second virtue of the Hox genes can be used in
this endeavor. The conservation of the homeobox has allowed
the cloning of this motif from a large number of organisms. In
Drosophila the Hox genes have stereotypical patterns of
expression and an analysis of these patterns within the
Arthropoda has been a focus of this laboratory. Using RT-PCR
we have cloned homeobox fragments from several insects,
spiders and higher crustaceans. Interestingly, the expression
patterns found in these latter two groups are different from that
seen in insects as well as from each other. While the expression
domains of the Hox genes are divergent in the three groups
there are two unifying principles: 1) The rule of colinearity is
maintained. And 2) The deployment of the Hox genes correlates
with the functional roles of the tagma rather than with a strict
anterior-posterior enumeration of the metameres.
Marine plant-herbivore interactions, like other ecological
processes, generally have been studied at the population level
and only on small sections of shoreline at few sites. Thus we
know little about how these interactions affect parameters other
than densities of the interactors, or about how well we can
generalize results to larger geographical regions. For example,
even within a site, few studies have examined effects of
herbivory on marine plant fitness or community-level
productivity. Equally important is learning how interactions vary
among sites. To scale up our understanding of plant-herbivore
interactions to a regional level, we must learn how they integrate
with the physical environment: how does variation in
environmental stress (e.g. changes in temperature, wave
exposure, or sea level) affect how algae and their consumers
interact? We are currently attempting such studies with Fucus
and its consumers on rocky shores in the Pacific Northwest.
Research done at a wide variety of sites and at several tidal
levels will determine how plant physiology and herbivory
integrate across abiotic gradients, providing a more realistic view
of region-level processes.
537
Scale me up, scale me down: Variation in bottom-up and
top-down effects across scales in herbivore-plant
interactions on the rocky shore.
HALPIN, P.M.*, G.W. ALUSON, T. FREIDENBURG, J.
LUBCHENCO, and B.A. MENGE. Oregon State Univ., Corvallis.
Marine intertidal communities embody a useful model system
for examining plant-animal interactions. Physical and biological
gradients occur over a variety of scales. Work in our lab has
investigated how marine plant-animal interactions operate over
the scale of meters (e.g. low to high intertidal), the meso-scale
(10-100s of kms), and between oceanographic regions with
distinct patterns of upwelling. Our studies indicate that no single
scale is adequate for understanding community dynamics.
Future and current directions for research include examining the
sublethal stresses on both grazers (e.g. through heat shock
protein production) and algae (e.g. through assessment of
nutrient limitation via C:N ratios), quantifying recruitment
dynamics of algae, and connecting onshore patterns to both
oceanographic and atmospheric variation. The newly formed
Partnership for the Interdisciplinary Study of Coastal Oceans
(PISCO) will extend the study of these processes underlying
community dynamics to the latitudinal scale.
Changing patterns of host use: Introduced marcophytes as
food and substrata of resident animals.
TROWBRIDGE, C D . Oregon State University, Hatfield Marine
Science Center, Newport, OR.
How marine animals use introduced macrophytes as food or
substratum is a pressing but largely unexplored issue. This
review will describe work on herbivores and epibionts of major
marine introduced pests (Caulerpa taxifolia and Codium fragile
ssp. tomentosoides). Use of exotic macrophytes may be
contingent on past experience, indicating genetic, physiological,
behavioral, or ecological barriers control changed resource use.
Priority areas for future research include determining (1) the role
of exotic algae and their exudates on larval and adult stages of
animals, (2) the fitness consequences of ingesting or inhabiting
exotic macrophytes, and (3) the spatio-temporal dynamics of
host-use.
541
Intake responses in nectarivores: Digestive and metabolic
causes and osmoregulatory consquences.
MARTINEZ DEL RIO, C.*, L G. HERRERA, T. J. MCWHORTER,
and J. E. SCHONDUBE. Univ. of Arizona, Tucson and
Universidad Nacional Autonoma de MExico.
The sugar content of floral nectars spans a tenfold range.
Nectar-feeding vertebrates respond to variation in sugar content
by modulating volumetric intake. In some nectar feeding animals,
the intake response to sugar concentration can be accurately
predicted from simple mathematical models that rely on
knowledge of gut morphology and in vitro rates of sugar
digestion. Sugar processing rates in the gut appear to shape the
intake response. Because most of the floral nectars consumed
by vertebrates are dilute, these animals ingest large amounts of
water while feeding. The water turnover rates of hummingbirds
feeding on dilute nectar are more similar to those of fresh water
teleost fish than to those of terrestrial vertebrates. Dilute nectars
impose osmoregulatory challenges to nectarivores.
Nectarivorous vertebrates exhibit renal traits that are well suited
to dispose of large water loads and inadequate to produce
concentrated urine. A phylogenetic survey of digestive and renal
characteristics of phyllostomid bats indicates that the ability to
assimilate sugar is negatively correlated with the capacity to
concentrate urine. Feeding on dilute floral nectars has both
digestive and renal consequences. The intake response of
nectarivores to sugar content in nectar is a behavior that
highlights the physiological consequences and challenges of
feeding on nectar.
539
Incorporating plant-animal interactions in the design of
marine protected area networks.
KLINGER, T. Univ. of Washington, Seattle.
Marine protected area (mpa) networks increasingly are being
established for the protection and recovery of marine biological
resources, and considerable attention is being devoted to their
design. However, design criteria typically focus on the
preservation and recovery of target species without
consideration of species interactions. Plants and their animal
associates often exhibit very different dispersal characteristics.
Therefore, mpa networks must be designed to facilitate dispersal
and recruitment among plant-animal pairs. As a general rule, I
suggest that the longer-dispersing member of a plant-animal pair
be used to determine the minimum extent of an mpa network,
and the shorter-dispersing member be used to determine the
maximum distance between mpas within a network.
An Integrative Approach to the Studies of
Terrestrial Plant-Animal Interactions
540
Plant-animal interactions in a model micro-community.
FOGLEMAN, J.C. Univ. of Denver, CO.
The Cactus-Microorganism-DrosopAw/a Model System of the
Sonoran Desert represents an excellent paradigm of a microcommunity. In this system, four species of endemic Drosophila
feed and reproduce in necrotic tissue of five species of columnar
cacti. Studies over the past 35 years have characterized a
ABSTRACTS
542
Evolution of plant resistance: Integrating pattern and
process.
MAURICIO, R. Univ. of Georgia, Athens.
The broad goals of my research are to understand the
process of natural selection in plant populations and to
determine the underlying genetic basis of adaptation. A detailed
knowledge of both the genetic basis of adaptively important
traits and the historical and contemporary selective forces acting
on those traits is fundamental to our understanding of evolution.
In this talk, I will summarize work that I have done to understand
the mechanisms of natural selection acting on resistance traits in
the plant, Arabidopsis thaliana. I will present current research on
the molecular population genetics of disease resistance genes —
work that is a first step in integrating studies of evolutionary
mechanisms and patterns.Michael
543
Gall flies, inquilines, and goldenrods: a model for host-race
formation and sympatric speciation.
ABRAHAMSON, W.G.*, M.D. EUBANKS, A.V. WHIPPLE, and
C.P. BLAIR. Bucknell Univ., Lewisburg, PA and Auburn Univ., A L
The interactions of Solidago host-plants with the gall fly
Eurosta solidaginis (Tephritidae) and gall inquiline beetle
Mordellistena convicta (Mordellidae) provide a model system to
examine host shifts and sympatric speciation. E. solidaginis has
developed genetically differentiated and reproductively isolated
host races associated with the ancestral host S. altissima and
the derived host S. gigantea. Eurosta attacking the derived host
suffer high larval mortality but largely escape mortality from one
91A
538
myriad of trophic level interactions between the three major
components of the model system. The distribution and chemistry
of the cacti; the distribution, metabolism, and successionary
patterns of the cactus-specific microorganisms (bacteria and
yeasts); and the metabolic capabilities, feeding strategies, and
behavior of the cactophilic Drosophila all play significant
interactive roles in the function of the micro-community. The
study of this interesting model system provides examples of
microscale processes in physiological ecology. Current research
is focused on evolution and regulation of genes whose products
(cyctochrome P450 enzymes) are involved in the specific insecthost plant relationships which exist between the Drosophila
species and the cactus species. Supported by NSF grant
IBN9806888
parasitoid. However, a potential shift to S. canadensis is not
limited by gall induction or choice: initial results suggest that
phenology may limit host shifts. The gall fly's host-race formation
has facilitated host-race formation of the inquiline beetle. Beetles
from gigantea and altissima galls show assortative mating
according to natal gall even in the absence of host plants,
allochronic emergence, and differences in adult mass. When
females are caged with both S. altissima and S. gigantea, beetles
emerge only from galls of the natal host the following spring
symposium -
544
Diversification at the insect-plant interface.
FARRELL, B. Harvard Univ., Cambridge, MA.
545
Where is the biology in conservation biology?
KAREIVA, P. NMFS, NOAA, Seattle, WA.
There are 25 endangered and threatened Evolutionary
Significant Salmonid Units (ESU's) in western North America.
Using science to plan for the recovery of these fish is one of the
biggest challenges being faced by conservation biology in the
United States. Yet the actual science of recovery is surprisingly
lacking in biology of a form familiar to most ecologists or
evolutionary biologists. Species interactions, adaptations,
ecosystem dynamics, and natural history all take a back seat to
maps, censuses, and demography. This is not to say maps,
censuses, and demography are unimportant. But it is ironic that
so little of what we learn as students in ecology or evolution
actually comes into play when making critical decisions about
salmon. I will argue that this is typical of conservation biology,
and that an unfortunately recurring theme in applied
conservation science is the absence of basic biological
information that is critical to protecting endangered species and
biodiversity. Expert opinion, complicated models, and
numerology all too often replace what cannot be replaced - the
understanding of a species' basic natural history and its
evolutionary and ecological dynamics.
Topic in Physiological and Biochemical
Mechanisms
546
Early seawater entry of juvenile American shad may be
advantageous.
ZYDLEWSKI, J.*, S.D. MCCORMICK, and J.G. KUNKEL Univ. of
Massachusetts, Amherst, and CAFRC, USGS-BRD, Turners
Falls, MA.
Migration of juvenile American shad is strongly influenced by
declining fall temperatures. Physiologically, shad tolerate
seawater (SW) after metamorphosis. While there is variability in
the timing of migration, tolerance to SW develops months prior
to entry for most fish. During their migration shad lose the ability
to regulate ions in fresh water, have increased gill Na,K-ATPase
activity and gill chloride cells proliferate. SW entry results in the
loss of chloride cells on the secondary lamellae and high gill
Na,K-ATPase activity. Physiological changes associated with
early (Sep) and late (Nov) migration were tested by isothermal
92A
547
Effects of environmental dilution on body fluid regulation in
the marine yellow stingray, Urolophus jamaicensis .
SULIKOWSKI, J.A.' and L. A. MAGINNISS. DePaul Univ.,
Chicago, IL
Adult stingrays collected off southeast Florida and airshipped to Chicago, were maintained in filtered and re-circulated
synthetic seawater (33a) for 5-13 days at 30 ° C. Animals
exposed to 82%, 74% and 66% SW in gradual steps exhibited
rapid and significant weight gains followed by recovery to predilution levels in 2-6 days. Acclimated animals at each salinity
(100% [N=12]), 82% [7], 74% [4] and 66% SW [3]) were
anesthetized and bled from the caudal vein into heparinized
syringes. In 100% SW, stingray plasma was slightly hypoosmotic to the external medium. Plasma [Osm] decreased with
stepwise dilution, but became increasingly hyperosmotic to the
bathing media. Mean corpuscular [Hb] measurements suggest
that stingray red cells swelled less with dilution than predicted
for a passive erythrocyte osmometer. We suggest that for mild
and moderate dilutions (82% and 74% SW), as an adaptive
process, yellow stingrays release both electrolytes and urea from
intracellular and extracellular compartments; with further dilution
(66% SW), animals retain electrolytes at the expense of urea.
548
Localization and changes in the abundance of the Na+-K+2CI- cotransporter in the gill of Atlantic salmon (Salmo salar
(during smolting and salinity acclimation.
PELIS, R.M.', J. ZYDLEWSKI, and S.D. MCCORMICK. Univ. of
Massachusetts, Amherst, and Conte Anadromous Fish Research
Center, Turners Falls, MA.
Changes in abundance of the Na+-K+-2CI- cotransporter
were monitored in the gill of Atlantic salmon during smolting and
salinity acclimation. The monoclonal antibody (T4), which
recognizes both secretory (NKCC1) and absorptive (NKCC2)
isoforms (Lytle et al. 1995) was utilized in immunocytochemical
and immunoblotting procedures. The Na+-K+-2CI- cotransporter
was localized to chloride cells and not other cells in the gill of
Atlantic salmon and was colocalized with Na+,K+,ATPase. In
parr, only a few chloride cells stained positive for the
cotransporter and low levels were observed on immunoblots.
Acclimation of parr to seawater resulted in increased
immunoreactivity in chloride cells on primary filaments
exclusively and in increased levels of the cotransporter. Smolts
exhibited chloride cells that were strongly stained on both
primary filaments and secondary lamellae and showed increased
expression of the cotransporter. After smolting the number of
stained cells decreased along with amounts of the cotransporter.
The Na+-K+-2CI- cotransporter is located in gill chloride cells of
Atlantic salmon and is upregulated during smolting and salinity
acclimation.
549
Na,K-ATPase in the gills and rectal gland of fresh water and
marine Atlantic stingrays [Dasyatis sabina).
PIERMARINI, P.M.* and D.H. EVANS. Univ. of Florida,
Department of Zoology, Gainesville.
While Na,K-ATPase has been extensively studied in the
rectal gland of marine elasmobranchs, little is known about the
enzyme's role in the gills and rectal gland of euryhaline
elasmobranch fishes. The goal of this study was to compare
branchial and rectal gland Na,K-ATPase expression, using
immunohistochemistry and Western blotting, between freshwater
and marine Atlantic stingrays (Dasyatis sabina). In fresh water,
Na,K-ATPase was localized to both filamental and lamellar cells
of the branchial epithelium, but was only localized to cells of the
filament in marine (D. sabina). The overall branchial amount of
Phylogenetic studies of beetles and other phytophagous
insects, as well as of plant and animal pathogens, have begun to
reveal consistent variation in the evolutionary rates of traits
affecting host use, including diet breadth, host tissue specificity
and host taxon affiliations. Some traits are conservative
throughout large taxonomic groups— across vast geographic
areas and through deep geological time-while others are highly
labile, changing more rapidly than speciation. These inform
theories on the roles of stabilizing selection and availability of
genetic variation in contributing to rates of evolutionary change.
Phylogenetic studies also pinpoint where changes in host use
occur and permit study of their population genetic con-elates,
potentially illuminating the role of microevolutionary change in
molding macroevolutionary patterns.
SW transfers. Early SW transfers (24C) resulted in a 3-fold
increase in gill Na,K-ATPase, and a rapid recovery of body
moisture. Late transfers (10C) had no change in gill Na,KATPase, and recovery of body moisture was protracted. Patterns
of FAs were influenced by both temperature and salinity, and
could reflect chloride cell number and ultrastructure. Analysis of
chloride cell number, size and morphology is underway.
Na,K-ATPase was lowest in marine (D. sabina). Localization of
Na,K-ATPase in the rectal gland was similar in freshwater and
marine individuals, however, rectal glands from marine (D.
sabina) contained more Na,K-ATPase than those from freshwater
animals. The euryhaline life style of the Atlantic stingray may be
linked to its 'ability' to differentially express Na,K-ATPase in the
gills and rectal gland. Supported by EPA STAR Grant U-91541901-0 (PMP) and NSF Grant IBN-9604824 (DHE).
550
Cutaneous water absorption in a urodele amphibian, the
rough-skinned newt (Taricha granulosa).
POWERS, D. R.*, P. M. ANDREWJESKI, and K. L. THORNBURG.
George Fox Univ., Newberg, OR, and Oregon Health Sciences
Univ., Portland, OR.
551
Water exchange by snapping turtle (Chelydra serpentina)
eggs in field nests.
ACKERMAN, R.A.* and D.B. LOTT. Iowa State Univ., Ames.
553
Protein requirements of the orange-tufted sunbird
{Nectarinia osea).
ROXBURGH, L* and B. PINSHOW. Jacob Blaustein Inst. for
Desert Res., and Ben-Gurion Univ., Sede Boger, Israel.
Floral nectar contains small amounts of amino acids and
proteins, but not enough to provide nutritional benefit to
nectarivorous birds. Thus, nectarivores require additional
sources of dietary protein, namely pollen or insects, and often
have low protein requirements. Nectarivorous birds are
represented by three major radiations: honeyeaters
(Meliphagidae), sunbirds (Nectarinidae) and hummingbirds
(Trochilidae). Reliance on nectar has resulted in a variety of
convergent features in these families. To test the hypothesis that
orange-tufted sunbirds have low maintenance protein
requirements, as found in other nectarivorous birds, we
measured nitrogen balance, endogenous nitrogen loss and body
mass changes in captive birds, using insects as a protein
source. Nitrogen requirements of sunbirds are a third of those
predicted for birds (Robbins, 1983). This pattern of low nitrogen
requirements among nectarivorous birds may be partly
attributable to lower fecal nitrogen losses when consuming a
liquid diet. Furthermore, these birds may be unable to obtain
larger quantities of protein, due to digestive constraints.
Supported by Israel Science Foundation grant 3/98.
554
Effects of fasting on in-flight fuel catabolism of pigeons.
GANNES, LZ.*, K. HATCH, and B. PINSHOW. Princeton Univ., .
NJ, and Ben-Gurion Univ., Sede Boger Israel.
Change in mass of snapping turtle eggs in 15 field nests and
thermal and hydric microclimates around the nests were
assessed over 2 years in Iowa. Freshly laid egg clutches were
placed either in turtle or human excavated nests and were
weighed at varying intervals thereafter. Prior to hatching the eggs
were removed to the lab and hatchling variables assessed. In the
field, nest and soil temperatures, soil water content and other
microclimate variables were measured and recorded throughout
incubation. Viable eggs increased nearly linearly in mass during
incubation. Water uptake averaged 46.7 % of initial mass (12.7
g) or 67.0 mg/day (± sd 9.9) in year 1 and 42.9 % (11.8g) or 76.0
mg/day (± sd 13.8) in year 2. Hatchling and yolk mass and water
content as well as incubation time (mean 81, ± 5 days) were
independent of egg mass change over the range observed. Soil
water potential averaged -28.4 (± sd 6.9) kPa in year 1 and -31.8
(± sd 5.0) kPa in year 2. Summer rainfall was above normal in
year 1 and below normal in year 2. Egg water exchange was
independent of rainfall. The pattern and quantity of water
exchange closely resembled those observed in lab studies using
natural media.
Some birds regularly undergo extended fasts and many
maintain high-metabolic activity while fasting. We investigated
the effects of fasting on energy substrate metabolism in flight by
depriving trained tippler pigeons (Columba livia) of food for 2-48
h preceding flights of 4-h. Immediately after flight, blood
concentrations of uric acid and beta-hydroxybutyrate were
increased, indicating elevated protein and lipid catabolism during
flight. Lighter birds and birds fasted for longer periods before a
flight lost less mass during the flight. Birds that lost more body
mass during flight had lower blood beta-hydroxybutyrate
concentrations, suggesting lower lipid oxidation. Flying pigeons
apparently did not compensate for lower lipid catabolism with
increased proteolysis. Changes in protein catabolism during
flight were not correlated with either fast duration or pre-flight
body mass. We reasoned that pigeons lost more mass during
flight after feeding than after fasting because they catabolized
more glycogen. Thus, pre-flight fast duration is an important
determinant of the fuels used in flight.
552
555
Comparative protein requirements and digestive strategies
of three species of parrots with distinct dietary
specializations.
PRYOR, G.S. Univ. of Florida, Gainesville.
Relative organ mass explains photoperiod-induced
differences in energy expenditure in collared lemmings.
POWELL, C.S.*, H.L. HUNTER, M.L. BLAYLOCK, and T.R.
NAGY. Univ. of Alabama at Birmingham.
Protein deficiency has been an obstacle in the evolution of
specialized nectarivores and frugivores. Proposed physiological
mechanisms that enable such specialists to subsist on lowprotein diets include low endogenous protein losses and
requirements, and high intake rates and digestibilities. I
compared these traits among nectarivorous Red Lories (Eos
bornea), frugivorous Pesquet's Parrots tpsittrichas fulgidus), and
granivorous Budgerigars (Melopsittacus undulatus). Protein
losses and requirements were directly proportional to the level of
protein in each species' diet. However, mass-specific intake
rates were inconsistent with predictions based on dietary protein
We have previously demonstrated that collared lemmings
(Dicrostonyx groenlandicus) exhibit significant reductions in REE
following exposure to short photoperiod (SD) relative to long
photoperiod (LD: 48±2 vs. 52±2 kJ/day, p<0.05). We
hypothesized that the reduction in REE was due to changes in
relative organ mass. Our results showed that SD animals had
smaller organs (liver, kidney, heart) than LD animals, after
correcting for remaining body mass (ANCOVA). Multiple linear
regression analysis indicated that photoperiod remained
significantly associated with REE after correction for body mass
and composition. However, photoperiod was not significantly
ABSTRACTS
93A
We examined water uptake rate across ventral skin of roughskinned newts (Taricha granulosa), urodele amphibians. This
would be important during the newt's terrestrial phase when
desiccation is a concern. Water absorption varied seasonally,
being highest during summer. Peak absorption rate was 6 x
lower than in the sympatric Pacific tree frogs (Hyla regilla).
Slower uptake rate is likely due to characteristics of the skin that
1) differ from anurans (e.g. thickness), and 2) are linked with the
aquatic nature of the newts. To explore this latter possibility we
are studying the role of cellular water channels, specifically
aquaporins (AQP), in water flow across ventral skin. AQP is
important in tissues exhibiting bulk water flow. We hypothesize
that AQP density in skin will be related to water uptake rate.
Using PCR we have shown that AQP genes are expressed in the
ventral skin of newts throughout the year. We are currently
attempting to quantify AQP expression in both newts and tree
frogs using Northern analysis, and isolate its tissue location
using immunohistochemistry.
levels. Intake rates for Pesquet's Parrots were unexpectedly low,
apparently due to their large size. Indeed, in a separate analysis,
I found that intake rates of wild birds are correlated with body
mass, not dietary protein levels. Digestibilities of protein were
highest for Red Lories, and lowest for Pesquet's Parrots. While
protein requirements and endogenous losses are low in
nectarivorous and frugivorous birds, differences in intake rates
and digestibilities suggest alternative strategies to coping with
low protein diets.
(p>0.5) related to REE when the weight of the dry organs (liver,
kidney, and heart) and remaining dry body mass were included
in the model. Likewise, photoperiod was not significantly
associated with REE when either liver or kidney dry mass, but
not heart dry mass, replaced combined organ dry mass in the
model. Our results suggest that differences in REE between SD
and LD lemmings are primarily due to differences in relative liver
and kidney mass. Supported by NIH R01 DK-54918
556
Basal and maximal metabolic rate, and cytochrome c
oxidase activity in Siberian hamsters at different
photoperiods.
BOILY, P.* and B. B. REES. Univ. of New Orleans, LA.
557
Body composition, nutrient transport, and resting metabolic
rate of energy restricted, parasitized mice.
KRISTAN, D.M.* and K.A. HAMMOND. Univ. of California,
Riverside.
Effects of energy restriction depend on whether energy is
restricted on a long-term (months to years) or short-term (days to
weeks) basis. Laboratory mice ( Mus musculus) were infected
with Heligmosomoides polygyrus larvae, an intestinal
nematode. Mice were then exposed to energy restriction to
examine combined effects of both parasites and short-term
energy restriction on body composition, nutrient transport and
resting metabolic rate (RMR). Parasitized mice lost body fat and
increased their lean body mass; thus, they had a higher RMRs
than unparasitized mice for both ad lib fed and energy restricted
treatments. Glucose transport declined for parasitized mice,
compared to unparasitized mice. Energy restricted mice had less
mucosal mass in the small intestine than ad lib fed mice, but
increased their glucose transport. However, energy restricted
mice that were also parasitized were not able to upregulate their
glucose transport. Energy restricted mice had less body fat (no
change in lean tissue mass), lower small intestine mass and
lower RMR than mice in other treatments. The combination of
energy restriction and parasitism heightens the challenges to
these mice.
558
Lacustrine salmonids and the energetic physiology of
migration: Reproductive steroids, thyroid hormones and
metabolic enzymes.
LEONARD, J. B.K.* and H. UEDA. Hokkaido Univ., Abuta, Japan.
We characterized the changes in reproductive steroids,
thyroid hormones, and white muscle metabolic enzymes that
occurred over the course of the pre-migratory and reproductive
season using non-lethal sampling techniques in two lake
salmonids: masu (Oncorhynchus masou) and sockeye
(Oncorhynchus nerka) salmon. Profiles of steroid hormones
followed patterns typical of reproductively maturing, adult
salmonids, including increasing T (both sexes) and male 11-KT,
elevated female E2 and a peak in DHP late in the season.
94A
559
Intraspecific variation in the energy budgets of lizard
embryos.
ANGILLETTA, M.J.* and M.W. SEARS. Univ. of Pennsylvania,
Philadelphia.
In Sceloporvs undulatus, females in northern populations
produce larger offspring than those in southern populations. Are
hatchlings in northern populations larger simply because females
allocate more energy to eggs, or do embryos in these
populations utilize available energy differently than embryos from
other populations? To answer this question, we compared the
energy budgets of embryos from NJ and SC populations of S.
undulatus. Non-polar lipid content and total caloric content were
determined for a subset of eggs oviposited in the laboratory.
Remaining eggs were incubated at 30 °C and metabolic rates of
embryos were measured throughout incubation. Eggs laid by NJ
females contained more energy than those laid by SC females.
The total energy expended on metabolism during incubation was
greater for NJ embryos (2.2 kJ) than SC embryos (1.7 kJ), but
embryos from both populations metabolized the same
percentage of energy available in eggs (55%). Intraspecific
variation in hatchling body size is caused by a difference in
energy provided for embryos by maternal investment, rather than
a difference in allocation of energy by embryos.
560
Metabolic expenditure as a proximate source of variation in
growth rates of the sagebrush lizard [Sceloporvs graciosus).
SEARS, M. W. Univ. of Pennsylvania, Philadelphia.
Growth rates vary among three elevationally distinct
populations of Sceloporvs graciosus in Zion National Park, UT.
Lizards from a high elevation population grow faster than lizards
from two lower elevation populations. Given that food availability
does not appear to differ between the sites, I tested the
hypothesis that high elevation lizards have lower metabolic
expenditures than lower elevation lizards, which would allow
more energy to be diverted to growth. For lizards from each of
the three study populations, oxygen consumption was measured
using flow-through respirometry over a range of temperatures
(17 °C to 37 °C) and times of day. Resting metabolic rates of
lizards were significantly different between sites, temperatures,
and times of day. High elevation lizards exhibited lower resting
metabolic rates than those from lower elevations did. Oxygen
consumption increased with temperature and decreased with
time of day over the measurement period. Daily metabolic
budgets were constructed from resting metabolic rates using
field active body temperatures and daily activity patterns. Total
metabolic expenditures were lowest for high elevation lizards
supporting the hypothesis of decreased metabolic rates
compensating for higher growth rates.
561
Effects of intensity and duration of activity on metabolic
recovery and cost of activity (Cact) in the desert iguana
(Dipsosaurus dorsalis).
HANCOCK, T.V.* and T.T. GLEESON. Univ. of Colorado,
Boulder.
The speed or intensity at which an animal locomotes
determines the suite of overlapping physiological mechanisms
which will be used to support such activity. Intensities above the
lactate threshold or maximum aerobic speed (MAS) utilize
anaerobic support, thus excess exercise oxygen consumption
(EEOC) cannot account for all costs associated with the activity.
Inclusion of excess post-exercise oxygen consumption (EPOC)
Previous work indicated that basal metabolic rates (BMR) of
Siberian hamsters {Phodopus sungorvs) decrease when
photoperiod changes from a long, summer-like to a short,
winter-like photoperiod. It is not known if this change in BMR is
coupled with a decrease in maximal metabolic rate (MMR), or if
variation in these measures of aerobic metabolism is correlated
with cytochrome c oxidase (COX) activity, the terminal oxidase of
the electron transport chain. We measured BMR, cold-induced
MMR and COX activity in several key tissues in Siberian
hamsters acclimated to a long (14L:10D) or to a short
photoperiod (10L:14D). Our results confirm a small but significant
decrease in BMR after acclimation to short photoperiod, while
MMR did not change. This may reflect a decrease in energetic
demands while maintaining a high thermogenic capacity for
winter-like conditions. Acclimation to short-day photoperiod led
to an increase in total heart and liver COX activity of 20 and
30%, respectively. However, tissue activities (as U/g, U/mg
protein, or whole organ activities) were not correlated to BMR or
MMR, which may result from low inter-individual variability or
small sample sizes.
Thyroid hormones changed significantly; both T3 and T4 in masu
and T3 in sockeye salmon decreased. There was a trend for
T3/T4 to decline. There were few changes in CS, HOAD, PFK
and GOT. MDH and LDH generally decreased in activity and PK
demonstrated substantial decreases (-3x in sockeye). Our data
indicate there are changes in energy-regulating processes that
occur prior to river entry and spawning. We suggest that
landlocked populations of anadromous fishes can serve as
useful models for examining the physiology of migration during
stages prior to upstream migration.
throughout recovery is useful to reflect total costs, especially
when activity is vigorous and brief. This study examined EEOC
and EPOC during 15-300 sec sprints in Dipsosaurus at
intensities of 1/2 to 4 times MAS. We have previously shown that
EPOC increases with duration at maximum intensities and this
study also showed increases with duration at submaximal
intensities. At common durations EPOC increased with intensity,
with the largest increases seen above MAS. Cact was calculated
as (EEOC+EPOC)/distance to reflect locomotor costs. Cact was
above traditional costs of locomotion for all activities examined.
Cact decreased with activity duration at all intensities, but is
independent of intensity at a common duration. NSF Grant
97240140.
562
Relationship of metabolic rate and organ mass to
environmental productivity in Peromyscus mice.
MUELLER, P.' and J. DIAMOND. UCLA Medical School, Los
Angeles, CA.
563
Dietary protein affects consumption, gonad production, and
survivorship in the echinoid Lytechinus variegatus.
HAMMER, H.S.\ S.A. WATTS, J.B. MCCLINTOCK, J.M.
LAWRENCE, and A.L. LAWRENCE. Univ. of Alabama at
Birmingham, Univ. of South Florida, Tampa, and Texas A&M,
Port Aransas.
An understanding of nutrition and how it relates to gonad
production is essential to maximize the commercial potential of
sea urchin roe. Previously-starved urchins (ca. 36 mm diameter,
n=12) were held in replicated (3x) 80 L aquaria with ASW at 21*C
and 32 ppt for each diet treatment. Urchins were fed a
formulated isocaloric diet at either 10 (L), 30 (M) or 50% (H)
protein ad libitum for 10 weeks. Consumption averaged 1.99,
1.35 and 1.30 g/individual/day for the L, M and H protein diets,
respectively, and was significantly greater in individuals fed the L
protein diet. The gonad index increased from 0.3 to 3.0, 8.5 and
7.9 at 5 weeks and to 10.7, 11.3 and 12.7 at 10 weeks when fed
the L, M and H protein diets, respectively. The gonad production
efficiency at 10 weeks was 0.28, 0.51, and 0.54 g wet gonad/dry
weight of food consumed for the L, M, and H protein diets,
respectively. After 7 weeks individuals fed the L protein diet
began to die, with final survivorships recorded at 72, 94, and
100% for the L, M and H protein diets, respectively. Funded by
Sea Grant.
564
The effect of frequency of feeding on consumption,
absorption efficiency, and assimilation efficiency in the sea
urchin Lytechinus variegatus.
LAWRENCE, J.M.*, L PLANK, J.B. MCCUNTOCK, S.A. WATTS,
and A.L. LAWRENCE. Univ. of South Florida, Tampa.
The frequency of feeding of sea urchins in the field ranges
from nearly continuous to very infrequent. Sea urchins were
starved for ten days after collection and then put in groups fed
every day, every 2 days, or every 4 days for 28 days. The
consumption rate of all individuals was high the first week of
feeding. It then decreased to a lower, constant rate in those fed
every day but increased to a higher, constant, and equal rate in
ABSTFtACTS
565
Physiological constraints on reproductive nutrient allocation
in Lepidoptera: The dietary origins of individual egg amino
acids.
O'BRIEN, D.M.*, C.L. BOGGS, and M.L FOGEL. Stanford Univ.,
CA, and Carnegie Institute of Washington, D.C.
Reproductive resource allocation, the link beween nutritional
physiology and life history, is particularly complex in
Lepidoptera. We previously used diets naturally distinct in 13C to
show that eggs come to reflect a highly consistent mix of larval
and adult-derived resources. The fixed contribution of larval
nutrients should reflect constraints upon the availablility or
synthesis of specific nutrients from the adult nectar diet. Here we
use compound-specific stable isotope analysis (GC - IRMS) to
determine the dietary origins of specific egg amino acids. The
carbon composition of the essential amino acids tested indicated
that they derived entirely from the larval diet. In contrast, the
non-essential amino acids showed a substantial carbon signal
from nectar sucrose. The proportion of amino acid carbon
deriving from the nectar diet varied among the non-essential
amino acids, from as little as 30% up to 100%. The pattern of
carbon use among the amino acids was consistent across two
unrelated species, and suggests general biochemical constraints
upon the dietary sources of nutrient for egg production in
Lepidoptera.
566
Hydrogen (H2) production by digesting pythons:
Fermentation, malabsorption, or putrefication?
SECOR, S.M.* and J. DIAMOND. Univ. of California, Los
Angeles.
Hydrogen production, a by-product of carbohydrate
fermentation by colonic/cecal bacteria, is used clinically to
demonstrate intestinal carbohydrate malabsorption. In a pilot
study, we found digesting pythons to expel large amounts of
hydrogen, even though they consume little carbohydrate (but
possess a cecum). Hence we measured hydrogen production in
digesting pythons, evaluated its link to malabsorption, and
identified its source. While digesting a rat meal, pythons' oxygen
consumption increased 12-fold and hydrogen production peaked
at 0.1 mmol/kg.hr within 24 hr (no hydrogen produced before
feeding). To induce malabsorption, we fed corn starch-filled rats
to pythons, who responded with peak hydrogen production of
0.5 mmol/kg.hr within 36 hr, days before digesta enter the colon.
Exercising fasted pythons increased metabolism by 7-fold, but
produced no hydrogen. Live rats produced no hydrogen, but
dead rats left to putrefy produced hydrogen at rates up to 2
mmol/kg.hr. We conclude that hydrogen released from digesting
pythons results from putrefication of their intact meal within their
stomachs, rather than from colonic/cecal fermentation after
intestinal malabsorption.
567
Digestive metabolism in banded water snakes, Nerodia
fasciata.
HOPKINS, W.A.*, J. H. ROE, T. PHILUPI, and J.D. CONGDON.
Univ. of South Carolina, Columbia, and Savannah River Ecology
Laboratory, Aiken, SC.
Traditional techniques for measuring digestive metabolism in
ectotherms rely on linear interpolation of periodic oxygen
consumption measurements over long periods of time. While
such techniques provide good estimates of specific dynamic
action (SDA) in sit-and-wait predators, they are potentially less
effective at estimating SDA in more active organisms. Here,we
utilize a computer-controlled respirometer to monitor digestive
metabolism in banded water snakes, an active forager which
95A
Related species of mammals of similar body mass show
differences in metabolic rate, possibly reflecting adaptive
responses to differing environmental pressures. Since relative
resource availability may set the limits for metabolic activity, we
hypothesized that metabolic rate and masses of organs that
support it (kidneys, liver, heart, digestive tract) would correlate
possitively with environmental productivity. We tested this
hypothesis using six species of Peromyscus mice (body size
12-60 g) originating from habitats that vary from very low to high
productivity. Macmillan and Garland (1989) proposed that low
BMR in arid zone Peromyscus was most likely a response to
high summer temperatures, not low precipitation levels. Our
data, in contrast, show increses in resting metabolic rate with
inceasing rainfall as well as with increasing July temperature. We
suggest therefore that habitats of high plant productivity support
evolution of greater metabolic intensity.
those fed every 2 or 4 days. The amount eaten was directly
related and the absorption efficiency indirectly related to the
frequency of feeding. The assimilation efficiency was greatest for
individuals fed every day. It was lower and similar for those fed
every 2 or 4 days. The increased absorption efficiency of the
latter two groups did not compensate for the decrease in the
amount of food eaten. Supported by Florida Sea Grant R/LR-A21.
exhibits daily activity cycles during respiratory measurements.We
collected 264 O2 consumption measurements over 2
consecutive 6 day periods following ingestion of prey items(each
equaling 20% of snake body mass). By collecting many
measurements with minimal temporal separation, we remove
activity-derived peaks from our estimates of metabolic changes
related to digestion. Using these techniques we estimate
standard metabolic rate(SMR)of water snakes to be 0.043
mlO2/g*h. Snakes exhibited a 5-fold increase in metabolic rate
during digestion with peak 02 consumption reaching 0.215
mlO2/g*h at 22.47 h post-feeding. Metabolic rate remained
elevated above SMR for 83.23 h.
Morphology
568
Effect of stresses in the surrounding bone on the size of the
infraorbital foramen.
LANDRY JR. S.O. State Univ. of New York, Binghamton.
569
Axial orthogonal fiber arrays in the penis of the loggerhead
turtle (Caretta caretta).
KELLY, D. A. Cornell Univ., Ithaca, NY.
The turtle penis contains two erectile structures, a dorsal
corpus spongiosum and a ventral corpus fibrosum. The corpus
spongiosum is a heavily vascularized erectile tissue which forms
the borders of the open urethral groove on its dorsal surface; the
corpus fibrosum contains stiff tissue that supports the penis
during copulation. The gross anatomy and microanatomy of
these structures have never been examined from a
biomechanical perspective, and it is not known how the design
of these tissues permits the penis to resist bending during
copulation. Gross dissection and histological examination of a
loggerhead turtle penis (Caretta caretta) shows that the corpus
spongiosum and corpus fibrosum are not separate erectile
systems as in mammals, but appear to be connected by
extensive anastamoses along their interface. The corpus
fibrosum appears to consist of a central cavity densely filled with
collagenous cords bordered by an approximately 1 mm thick
wall. The wall contains bundles of collagen fibers organized in a
series of layers with fibers oriented alternately at 90~° and 0=°' to
the long axis of the penis, forming a plywood of axial orthogonal
fiber arrays.
570
Keeping an eye on the nose: The Harderian gland is part of
the VN system.
REHOREK, S.J.*, W.J.HILLENIUS, W.QUAN, and M.HALPERN.
NYCOM, Old Westbury, College of Charleston.SC, and State
Univ. of New York, Brooklyn.
The Harderian giand (HG) is a poorly understood anterior
orbital structure, found in most tetrapods. Numerous functions
have been ascribed to this gland, including contributions to
orbital lubrication or the VN system, in Thamnophis sirtalis
(Serpentes: Colubridae) it is connected to the VNO via the
96A
571
Regulating bone at the cellular level: A little evidence for
Wolff's Law.
CULLINANE, D.', N. INOUE, R MEFFERT, J. TIS, B. RAFIEE, and
E. CHAO. Johns Hopkins School of Medicine, Baltimore, MD.
Wolff's Law describes the structural adaptation of the
vertebrate skeleton to stress. This law is believed to govern the
architecture and orientation of trabecular bone and the
deposition or resorption of cortical bone in direct response to
increased or decreased loads, respectively. Specific evidence for
this phenomenon ranges from hypertrophic bone in the
skeletons of elite athletes to osteopenia in the skeletons of
astronauts and hibernating mammals. We have investigated a
cellular level response in living bone to a pulsed electromagnetic
field (PEMF) and ultrasound, which we theorize simulates
increased mechanical loading of the skeleton by perturbation at
the cellular level. We surgically induced fractures in canine and
rabbit tibia models and stimulated the fracture sites with PEMF
and Ultrasound, respectively. We found significant increases in
cartilagenous and bony callus formation, and a significant
increase in bone torsional stiffness and strength after clinical
healing, in comparison to controls. Our results suggest a cellular
basis for the action of Wolff's Law via signals to
mechanoreceptors in the membranes of osteoblasts,
chondrocytes, and other target cells.
572
Scaling in the skull of the Colorado River toad, Bufo alvarius.
MCGOWN, C.P.*, J.C.O'REILLY, J.M.BIRCH, and
K.C.NISHIKAWA. Northern Arizona Univ., Flagstaff.
The physiology and kinematics of movements such as
locomotion or feeding are closely linked to body size and shape.
Isometric changes in movement kinematics were predicted to be
a function of isometric changes in body size. Yet this relationship
has been difficult to test due to the fact that few animals have
been shown to grow isometrically. An exception may be toads in
the genus Bufo. To model this problem, we chose Bufo alvarius,
which grows over a 1000 fold size range and demonstrates
isometric feeding kinematics. In order to test for isometric
growth, we used linear measurements and geometric
morphometrics in 30 specimens ranging from 15 to 130 mm
SVL. Linear measurements of the jaw and related musculature
were also taken in order to model the jaw as a lever-arm system
to calculate closing forces. Preliminary results from linear skull
measurements suggest that growth isometry exists; yet a more
detailed look at shape via relative warp analysis strongly points
to areas of allometry. The most notable of these changes is in
the area of the squamosal and points of adductor and depressor
attachment. This result implies that jaw forces may not scale
isometrically with body mass in B.alvarius. However, further
analysis of the jaw lever-arm is necessary to fully test this
hypothesis. Supported by NSF 9809942 and a Hooper
Undergraduate Research Award from NAU.
573
Running and bleeding: Design conflict in galloping mammals.
BRAMBLE, D.M. Univ. of Utah, Salt Lake City.
Exercise induced pulmonary hemorrhage (EIPH) is a frequent
pathology of both racehorses and racedogs. It results from
mechanical failure of the lung capillaries during sustained, highspeed running. While pulmonary hypertension is widely assumed
The infraorbital foramen in mammals is located in the
maxillary bone just beneath the orbit and provides a passageway
for nerves and vessels serving the face.Since foramina in the
skull form in the bone around the structures passing through
them, one would expect that the diameter of any foramen should
conform to that of the transmitted structures. The infraorbital
foramen is often larger than they. In the dog {Canis familiaris) the
outer wall of the infraorbital foramen appears to be a pillar
resisting the force of the bite at the carnassial. Tamias
sfriafusfthe chipmunk) alone among sciurids has a large
infraorbital foramen,which however, does not transmit a slip of
the masseter muscle. The foramen divides the anterior face of
the maxillary into two struts which resist the stress generated by
the masseter rotating the zygomatic arch inward.The upper strut
presumably resists tensile stress and the lower, compressive.
nasolacrimal duct (NLD). HG's of 6 individuals were injected
(right side unilaterally or bilaterally) with a radioactively labeled
protein precursor. The right HG's were then injected with a
potassium-rich solution. Labeling was exhibited in the right-sided
HG, NLD, apex of VN sensory epithelium (implying uptake of the
HG secretions), VNO lumen and VN duct. No such labeling was
found in the other treatments. Thus, the HG secretions of snakes
flow to the VNO, and may be considered part of the VN system.
No labeling was observed in the orbit, and it may be unlikely that
the HG of T. sirtalis functions in orbital lubrication. Based on the
close association of the HG, NLD and VNO in several other
tetrapods, it is possible that similar conclusions may be
extended out to other taxa.
to be the primary or sole cause of EIPH, the localized distribution
of tissue damage is inconsistent with such an interpretation.
Experimental data from galloping dogs, including
cineradiographic observations of dynamic trunk-lung
interactions, suggest an alternative model. It proposes that EIPH
is a direct consequence of the use of the lungs as mechanical
stabilizers of the thorax in galloping mammals. Specifically, a
combination of locomotor induced pressure pulses in the
pulmonary arteries and synchronous inertial loading of the
dorso-caudal lung field appear to account for regional stress
fracture of the lung tissue. This model also explains the apparent
absence of EIPH in trotting mammals. EIPH reflects a basic
design conflict in mammals and stems from the evolutionary
recruitment of a primary respiratory organ for locomotor function.
Phylogenetic and developmental constraints, related to details of
gross lung morphology (e.g., lobar fusion), may predispose
horses to lung hemorrhage in the gallop. (NSF IBN-9318610).
574
Connective tissue and its role during tongue protraction in
Rana pipiens and Bufo woodhousii.
ZEPNEWSKI, E.D.* and K.C. NISHIKAWA. Northern Arizona
Univ., Flagstaff.
Elapid snakes are divided into two major clades based on
palatine morphology and relationships. One clade (palatine
erectors) has a simple palatopterygoid joint, a link between
maxilla and palatine, and a choanal process on the palatine
serving as the fulcrum for rotation. These features are inferred to
define palatine movement. In Dendroaspis polylepis and Naja
pallida, both palatine erectors, video records show similar
palatomaxillary kinematics. However, whereas Naja has a joint
between palatine and maxilla and a choanal process on the
palatine, neither of these features is present in Dendroaspis.
Similarly, palatomaxillary kinematics during protraction of the
braincase appear identical in Naja and Dendroaspis despite
differences in critical muscle insertions. Functional similarity in
structurally divergent systems suggests a structural core
necessary to perform the function and a structural periphery that
does not decrease fitness or performs other functions.
577
Ontogeny of feeding structures in larval fish with different
life histories: Atlantic cod and winter flounder.
HUNT VON HERBING, I. Univ. of Maine, Orono.
Atlantic cod and winter flounder have symmetrical planktonic
larvae. In cod,larvae and juveniles remain symmetrical.ln winter
flounder, transition to the juvenile stage involves metamorphosis
from a symmetrical larva to an asymmetrical juvenile. This study
compared the development of feeding structures in both
species.using histological techniques and skeletal measurements
from hatch to juvenile. For both species.viscerocranial structures
were simple and non-integrated in early development and
increased in complexity with growth.Species-specific differences
in feeding morphology became apparent during the late
larval/early juvenile stage.ln cod.changes in head dimensions
occurred in larvae and resulted in a shift from simple to more
complex feeding structures.In winter flounder.the most dramatic
changes in cranial morphology occurred in the late larval/juvenile
stage.Despite the differences in life history between cod and
flounder.similarities in feeding morphology exist in the larval
stage,while radical differences occurred in the transition to and
during the juvenile stage.Species-specific differences in
development may reflect adaptations to changes in habitat.
575
Sweeping, striking, and sniping: Modes of aquatic prey
capture in thamnophiine snakes.
ALFARO, M. Field Museum and Univ. of Chicago, IL.
Fish are a common prey of many snakes, yet little is known
about the functional morphology of piscivory by snakes. To
examine the functional demands associated with aquatic prey
capture by snakes, the predatory strike was studied in three
species of thamnophiine in which a highly aquatic, piscivorous
lifestyle has evolved independently: the diamond-backed water
snake, Nerodia rhombifer, the narrowheaded garter snake
Thamnophis rufipunctatus; and the western aquatic garter snake,
Thamnophis couchii. Snakes were filmed at 250 fps using a 2
camera high speed system and skull and trunk kinematics were
quantified. Nerodia captured fish using a lateral and posterior
strike, often followed by head sweeping. Pre-strike coiling of the
anterior trunk was not observed and less than 30% of the trunk
was typically recruited for a strike. T. rufipunctatus struck
anteriorly over a distance of 2 to 4 headlengths. Pre-strike coiling
in the anterior 20-40% of the body was observed. T. couchii
strikes also were anteriorly directed and covered the longest
distances of all taxa, sometimes exceeding 5 headlengths (9
cm). Pre-strike coiling in > 40% of the body was observed.
Neither Thamnophis species displayed post-strike sweeping
behavior. In contrast to fishes, aquatic prey capture kinematics
in snakes may be highly variable among closely related species.
ABSTRACTS
578
Prey processing kinematics in Tupinambis teguixin and
Varanus exanthematicus: Conservation of feeding behavior
in chemosensory tongued ""lizards."
ELIAS, J. A.*, L.D. MCBRAYER, and S.M. REILLY. Ohio Univ.,
Athens.
Although lizards have been predicted to have extensive
intraoral prey processing behaviors quantitative analyses of
variation in prey processing behaviors and their kinematics have
been limited. To date, although basal lizard species have seen
some study, the prey processing repertoires of crown taxa have
not been examined and quantitative comparisons of behaviors
within or among species have not been possible. In this study
the prey processing behaviors in the Savannah Monitor (Varanus
exanthamaticus) and Gold Tegu (Tupinambis teguixin) axe
described and compared to basal lizards and other vertebrates.
Although these two species have independently evolved derived
tongues which are highly specialized for chemoreception we
found that they shared the same three distinct types of transport
behavior and that tongue is used extensively in both inertial and
normal transport behaviors. In addition, these species exhibit a
striking conservation of feeding kinematics compared to patterns
known for basal lizards. A scenario for the evolution of inertial
feeding is proposed.
97A
Frogs within the families Bufonidae and Ranidae use the
same inertial elongation mechanism when protracting the tongue
from the mouth. Angular momentum produced by rapid mouth
opening allows these frogs to protract the tongue up to 180% of
resting length at high velocities. Unilateral denervation of the
main protractor muscle (M. genioglossus) showed feeding
behavioral differences between Rana pipiens and Bufo
woodhousii. B. woodhousii shows a reduction in tongue
protraction length without directional deviation. The tongue of R.
pipiens, while also showing a reduction in extension, deviates
toward the intact side. We hypothesize that the differences in
behavioral responses are due to the orientation of epimysial
connective tissue surrounding the genioglossus muscles.
Polarized light microscopy will be used to analyze histological
sections of these species. Orientation of collagen fibers present
in the connective tissue surrounding the M. genioglossus will be
measured. We predict that the orientation angle of the collagen
fibers in B. woodhousii may be higher than 54°44', which would
account for the lack of directional deviation. In ft pipiens, the
fiber angle should be less than 54°44', which would account for
the deviation toward the active side.
576
What form defines function? A cautionary case from elapid
snakes.
DEUFEL, A.* and D. CUNDALL. Lehigh Univ., Bethlehem, PA.
579
mechanics of dolphins. We ask if the diaphragm plays a major
role in inspiration in dolphins.
Organization of elastic fibers in the vocal sac of frogs.
SAVITZKY, A.H.*, K.A. ROBERTS, and A.S. RAND. Old Dominion
Univ., Norfolk, VA, and Smithsonian Tropical Research Institute,
Washington, D.C.
582
Recent studies have suggested that the vocal sac of male
frogs serves a mechanical, rather than acoustic, function during
calling. Histological analysis has demonstrated the presence of
elastic fibers in the vocal sac musculature, suggesting that the
vocal sac serves primarily to return air to the lungs by elastic
recoil. We employed a modification of the Verhoeff elastin stain,
a histological procedure, to examine the organization of the
elastin fibers in whole mounts of stretched vocal sac muscles in
several anuran species. This method revealed a highly ordered
array of elastic fibers. In small hylids, for example, the elastic
fibers are arranged in two layers, oriented approximately
perpendicular to each other and oblique to the body axis. The
high density of elastic fibers presumably maximizes elastic recoil,
and the orthogonal arrangement ensures orderly contraction of
the vocal sac. Further study is required to determine whether
variation in the elastin network reflects phylogenetic patterns,
differences in call characteristics, or both. The procedure for
examining elastin in whole mount has broader applicability,
especially for use with thin tissues.
Unique structure and function of the diaphragm in the
Florida manatee.
ROMMEL, S.A.* and J.E. REYNOLDS, III. Florida Marine
Research Institute, St. Petersburg, FL, and Eckerd College, St.
Petersburg, FL.
Manatee diaphragms differ from diaphragms of other
mammals. Gross examinations of fresh carcasses showed that
manatee diaphragms lie in a dorsal plane; are located dorsal to
the heart and do not attach to the sternum (not prehepatic!); and
attach medially to the vertebral bodies, forming two distinct
hemidiaphragms. The manatee transverse septum, a separate
structure, lies orthogonal to the diaphragm and separates the
heart from the liver. The lungs lie dorsal to the diaphragm,
placing them in perhaps a uniquely susceptible position where
boat strikes along the back can cause pulmonary damage.
Locations of manatee hiatuses - associated with aorta, caudal
vena cava, and esophagus - are also unusual because of
diaphragm position and configuration. Unusual relationships of
internal organs in the manatee require the redefinition of
anatomical terms such as mediastinum. Extreme muscularity of
and structural separation of the diaphragm into hemidiaphragms,
along with the ability of manatees to adjust their position in the
water column with minimal external movement, suggest that
diaphragmatic contractions may change the volume of each
pleural cavity sufficiently to affect the buoyancy, roll, and pitch.
581
Ventilation in bottlenose dolphins (Tursiops truncatus): The
role of the diaphragm.
DEAROLF, J.L.*, W.A. MCLELLAN, D.A. PABST, and J.W.
HERMANSON. Cornell Univ., Ithaca, NY, and Univ. of North
Carolina at Wilmington.
Actively swimming dolphins exhale and inhale in 0.3
seconds, exchanging 80% or more of their tidal volume.
Although dolphins possess typical mammalian respiratory
muscles (intercostals, diaphragm, rectus abdominus, etc.), the
muscles responsible for their unique respiratory behavior are
poorly understood. This study assessed the significance of
contractions of the diaphragm, the main inspiratory muscle of
terrestrial mammals, in the respiratory mechanics of bottlenose
dolphins. Histochemical analyses revealed the adult fiber-type
profile to be 67% slow-twitch fibers, similar to the profiles of
diaphragms in other mammals, like horses (66%) and cattle
(76%). The diameters of the dolphin's muscle fibers are much
smaller than those of large mammals and of their own axial
locomotor muscles. The small size of the fibers, their high
oxidative capacity (NADH), and the slow-twitch fiber-type profile
suggest a fatigue-resistant, slow-contracting diaphragm, a
muscle profile that does not fit with the model of respiratory
98A
Aquatic salamanders activate the transverse abdominis (TA)
of the lateral hypaxial muscles to power both undulation and
exhalation. In S. lacertina and A. tridactylum, EMG recorded from
the TA differs in amplitude and frequency depending on the task.
During exhalation, EMG signals have peak to peak amplitudes
between 20-40 mvolts and median frequencies of -200 Hz.
During undulation, however, signal amplitude ranges between
100-600 mvolts with median frequencies of -400 Hz. These
differences suggest a change in the type of fibers that are
recruited in the muscle. Signals with low-frequency components,
as during exhalation, indicate the activation of tonic and slow
fibers whereas higher frequency signals, as during undulation,
represent the activity of phasic muscle fibers. Using
histochemical methods, the TA was found to contain a
concentration of slow-twitch and tonic fibers along the medial
edge and fast-twitch fibers throughout the remainder of the
muscle. The percentage of tonic fibers in the TA decreases with
the speed of exhalation in the species studied; A. tridactylum
has the largest percentage of tonic fibers and exhales most
slowly and A. tigrinum has the smallest percentage of tonic
fibers and exhales most rapidly. This correspondence, along with
EMG analysis, suggests that tonic fibers are responsible for
powering exhalation in salamanders that exhale slowly.
583
Respiratory mechanics of the little snake: An application of
sonomicrometry.
SUMMERS, A.P.* and L.A.FERRY-GRAHAM. Univ. of California,
Berkeley, and Univ. of California, Davis.
A simple two-pump model, developed from the pioneering
work of Hughes, has served to describe how fish move water
into the mouth and subsequently out the external gill openings
during respiration. A key feature of this model is that water is
pumped over the gills continuously and unidirectionally despite
the episodic nature of water entering the mouth and exiting the
gills. Recent work on the benthic swellshark, Cephaloscyllium
ventriosum, however, suggested that buccal pumping may not
generate the continuous, unidirectional flow of water.We used
sonomicrometry and pressure transducers to characterize the
kinematics and flow of normal respiration in the little skate
{Leucoraja erinacea). Regular oscillatory patterns of movement
were successfully recorded with corresponding pressures in the
buccal and parabranchial cavities. It is apparent is that the gill
bars do open and close during respiration, and that they are
closed when the pressure in the parabranchial chambers
exceeds the pressure in the buccal cavity. This is a time of
potential flow reversal. There is a trade-off between the extent of
mouth opening and spiracular opening. The mouth starts to open
less fully (approximately 2 sec. into the sequence), the spiracles
begin to close less forcefully. This supports the general findings
for teleosts, and may hold true for all cartilaginous and bony
fishes.
584
The narial anatomy of extant amniotes and its significance
for the interpretation of narial novelty in dinosaurs.
WITMER, L. M. Ohio Univ. College of Osteopathic Medicine,
Athens.
In several clades of dinosaurs the vestibulum nasi is
apomorphically enormous. The enigmatic function of these
enlarged narial apparatuses is addressed using the extant
phylogenetic bracket (EPB) approach. Birds and crocodilians
form the EPB of dinosaurs and hence are the most relevant for
assessing homology; other amniotes also are important,
particularly when assessing analogy. This approach has allowed
580
Task-specific recruitment of motor units in the transverse
abdominis muscle of aquatic salamanders (Siren lacertina,
Amphiuma tridactylum, Ambystoma tigrinum).
MONROY, J. A.*, C. A. KOSTEK, E. A. CONNOR, and E. L
BRAINERD. Northern Arizona Univ., Flagstaff, and Univ. of
Massachusetts, Amherst.
aspects of narial anatomy to be reconstructed in dinosaurs. The
example presented here tests hypotheses on the position of the
fleshy nostril relative to the much larger bony narial aperture.
Traditional reconstructions of dinosaurs have placed the nostril
far caudally in the bony nan's. A radiographic and anatomical
study involving 42 species of birds, crocodilians, and squamates
spanning 31 families and 21 orders reveals an almost invariant
pattern in which the fleshy nostril is located far rostrally within
the bony naris; other amniote groups show the same pattern.
The structure of dinosaur narial regions is consistent with a
rostroventral location of the fleshy nostril, rejecting the traditional
hypothesis and having major implications for nasal function.
elaborations including siphons, tremata, slits, or other openings
of the shell and underlying mantle. The shapes of the incurrent
and excurrent chambers are defined by the overlying mantle and
shell, the gill or gills, and the underlying surface of the animal's
head and anterior visceral mass (often called the "floor" of the
mantle cavity). Cilia beating on the surface of the gill and the
interior mantle surface, as well as muscular contractions of the
mantle, work singly or in concert to provide the pump. The
vascularized gill is usually the primary exchange surface. The
diversity of designs of modern molluscan mantle cavities reflect
compromises between restraints and possibilities of design and
function.
585
588
Gill-cleaning mechanisms of a penaeid shrimp: Description
and experimental testing of function.
BAUER, R.T. Univ. of Southwestern Louisiana, Lafayette.
Organization of the striated muscle layers in a crayfish
intestine.
BRENNER, T.M., M.J. CAVEY*, and J.L. WILKENS. Univ. of
Calgary, Canada.
586
Functional morphology of gills and pallia) organs of
freshwater mussels: In vivo imaging using video endoscopy.
DIMOCK, JR., R.V.*, R.A. TANKERSLEY, and M. BYRNE. Wake
Forest Univ., Winston-Salem, NC, Florida Institute of Technology,
Melbourne, and Univ. of Sydney, Australia.
Hyriidae, Margaritiferidae and Unionidae exhibit the 3 larval
brooding conditions of unionoid bivalves. Glochidia larvae are
held within inner (endobranchous hyriids), all 4 (tetragenous
margaritiferids) or the outer demibranchs (ectobranchous
unionids). Differential use of gills as marsupia includes variation
in the interiamellar tissue connections characteristic of
eulamellibranch ctenidia. Hyriids and margaritiferids have
perforated interiamellar septa, whereas unionids have numerous
complete septa, capped dorsally creating sealed brood
chambers. Video endoscopy within demibranchs reveals 3-D
morphological detail that cannot adequately be interpreted from
histology or dissection. This presentation will include video of
structural differences in the architecture of gills, comparative
morphology of renal and genital openings, the release of ova and
glochidia, and the anatomical arrangements that separate suprafrom infra-branchial cavities in these families. The imaging
techniques provide new insight for functional and phylogenetic
considerations.
587
Continuity and design in the molluscan mantle cavity.
VOLTZOW, J. Univ. of Scranton, PA.
The molluscan mantle cavity houses the principle sites of
metabolic exchange between the animal and its environment.
The multiple functions of the mantle cavity result from the
coordination of a suite of design elements: an incurrent window,
an incurrent chamber, the pump, the exchange surface, an
excurrent chamber, and an excurrent window. The incurrent and
excurrent windows are usually specific regions of the shell and
mantle that control the shape and size of the incurrent and
excurrent streams. These may include quite subtle or obvious
ABSTRACTS
The intestine of Procambarus clarkii has inner longitudinal
and outer circular layers of striated muscle cells. The circular
layer resides near the external boundary of the viscus, and a
narrow strip of dense irregular connective tissue separates it
from the longitudinal layer. The longitudinal muscle layer consists
of six strips, one associated with the base of each longitudinal
ridge in the intestinal wall. The muscle cells in both layers have
been examined in ultrastructural sections. Sarcomeres of the
myofilament bundles in the circular muscle cells are considerably
longer and more variable in length than those in the longitudinal
muscle cells. Sarcoplasmic features are indicative of the slow
type of crustacean muscle. Cells emerge from the longitudinal
muscle strips and extend obliquely to insert near the tops of the
intesitnal ridges. This disposition of the longitudinal muscle cells
accounts for the wringing (torsional) peristalsis observed in vivo
along this sector of the gut.
589
Histology and F-actin staining of the intestine of a crayfish.
TO, T.H., T.L. BRENNER, M.J. CAVEY*, and J.L. WILKENS. Univ.
of Calgary, Canada.
The intestine of Procambarus clarkii has been examined in
semithin glycol-methacrylate sections. The intestinal wall exhibits
six longitudinal ridges. Epithelial folds are common in both
elevated and depressed sectors of the wall. A robust cuticle
appears on the apical surface of the adluminal epithelium, and
the secretory units and ducts of acinar (alveolar) glands reside in
the subepithelial connective tissue, as well as cells with large
cytoplasmic vacuoles, called 'bladder cells'. Inner longitudinal
and outer circular layers of striated muscle reside external to the
glandular tissue. Longitudinal muscle cells frequently emerge
from the inner layer and span obliquely to insert near the
undersurface of the adluminal epithelium. Sarcomeres of the
circular muscle cells are considerably longer and less distinct
than those of the longitudinal muscle cells. Immunohistochemical
staining for F-actin in whole mounts of the intestinal wall
accentuates the sarcomeres in cells of both muscle layers.
590
Mechanics of jaw protrusion in Forcipiger. A mechanism
convergent with Epibulus insidiator?
FERRY-GRAHAM, LA.* and P.C. WAINWRIGHT. Univ. of
California, Davis.
Extreme jaw protrusion in the sling-jaw wrasse Epibulus
insidiator is attributed to a novel mechanism where cranial
elevation causes the quadrate and interopercle to rotate,
protruding the jaws. We document a similar mechanism in the
long-nosed butterflyfish Forcipiger longirostris. Individuals were
filmed capturing planktonic prey using high-speed video. Digital
analysis revealed that in F. longirostris the upper and lower jaws
protrude as a unit and simultaneously with cranial elevation. The
jaws open only slightly beyond their starting position, without
any evidence of hyoid depression. Anatomical manipulation
suggests that cranial elevation as an input motion can cause jaw
protrusion. The hyomandibula is highly reduced and not involved
in lower jaw movement or suspension. Dissections suggest that
novelties found in E. insidiator also exist in F. longirostris,
99A
The branched gills of decapod crustaceans, enclosed in a
branchial chamber, are subject to paniculate and epibiotic
fouling. Setiferous epipods have been proposed as the gillcleaning mechanism of penaeid shrimps. The hypothesis of
epipodal gill cleaning was tested in the common Gulf of Mexico
penaeid Rimapenaeus similis. Epipods inserted among gills are
equipped with multidenticulate setae similar to those described
on gill-cleaning claws and setobranchs in other decapods. In
addition, the pereopodal exopods, modified from a primitive
natatory state, are equipped with such "cleaning" setae.
Epipodal setae are passively moved among gills during limb
movements but exopods are actively brushed over the lateralmost gill filaments. Experiments in which epipods or exopods
were removed from the gill chamber of one side but not the
other confirm that both epipods and exopods keep gills free of
sediment. Epibiotic fouling, however, might only be removed by
molting. Passive gill cleaning, like that of penaeids and many
other decapods, is proposed as primitive while the cheliped
brushing of many carideans and anomurans is derived in the
Decapoda.
including a unique ligament connecting the anterior
neurocranium to ventral head structures and rotating quadrate
and interopercle bones that protrude the jaw. These same
behaviors and modifications exist to a lesser degree in F.
flavissimus, the only other member of the genus.
591
Diversity of mechanical design for feeding in labrid fishes.
WESTNEAT, M.W.*, P.C. WAINWRIGHT, and D.R. BELLWOOD.
Field Museum of Natural History, Chicago, IL, Univ. of California
Davis, James Cook Univ.,Townsville, Australia.
about the higher-level evolution of avian feeding systems. Many
strong hypotheses remain untested, and sample sizes are small.
I suggest that many exciting opportunities still exist in the study
of avian feeding systems, and that these opportunities lie in the
application of a phylogenetic strategy to the problem of
choosing study taxa, larger sample sizes and more formalized
hypothesis testing.
594
Morphological and functional properties of the chameleon
hyolingual system.
HERREL, A.I', J. MEYERS, J. MONROY, and K. NISHIKAWA.
Univ. of Antwerp, Belgium and Northern Arizona Univ., Flagstaff.
The chameleon hyolingual system has fascinated researchers
for over a century and a half, resulting in excellent descriptions
of the hyolingual system. More recently, experimental techniques
have been used to unravel the mechanistic basis of the ballistic
tongue projection in chameleons. However, new experimental
data on the actual tongue-prehension mechanism raise
questions on how the ballistic tongue is controlled during prey
capture. In a first step to elucidate control-related questions, the
functional properties of the chameleon hyolingual system were
investigated. Dissections and standard histological techniques
revealed several previously unnoticed peculiarities of the
chameleon tongue. The histochemical analyses and motor
endplate staining of the hyolingual muscles allow us to postulate
new functional hypotheses on how tongue projection is
controlled in chameleons. Scanning electron microscopical
imaging showed a clear functional subdivision of the tongue pad,
and transmission electron microscopy of the tongue retractor
raises new questions on the functioning of this muscle.
592
595
The evolution of molluscivory in teleosts: A convergence of
motor patterns?
GRUBICH, J.R. Florida State Univ., Tallahassee.
A novel mechanism of tongue prehension in lizards.
HERREL, A.H.*, J.J. MEYERS, and K.C. NISHIKAWA. Northern
Arizona Univ., Flagstaff and Univ. of Antwerp, Belgium.
The snail-crushing behavior of some sunfishes has been
linked to the evolution of robust pharyngeal jaws and the use of
a novel motor pattern during prey processing. This study
characterizes the evolution of molluscivory in the Family
Sciaenidae by comparing the motor activity patterns of
pharyngeal muscles between two closely related taxa, the
molluscivorous black drum and the generalist red drum. Muscle
activity patterns were recorded simultaneously from up to eight
muscles in five individuals of each species. EMG's were
recorded during feeding on four prey types: shrimp pieces,
fiddler crabs, blue crab pieces, and hardshelled bivalve prey.
Results show red drum employed similar manipulation and
transport behaviors for all prey types; however, the black drum
also utilized a unique pharyngeal crushing motor pattern. This
crushing motor pattern is similar to the one described in
sunfishes, in that both involve high intensity bursts in most jaw
muscles but low activity in the abducting jaw muscle, the
pharyngocleithralis extemus. However, a primary feature of this
crushing pattern that differs from sunfishes is the decrease in
upper jaw retraction by the retractor dorsalis. Supported by NSF
IBN-9766042 to JRG.
The ability to project the tongue ballistically is a unique
character, which in lizards, is found only among the
Chamaeleonidae. Chameleons can project the tongue off the
hyoid and out of the mouth up to twice snout vent length when
attempting to capture prey. Observations of chameleons eating
small vertebrates such as lizards and birds suggest a novel
mechanism of tongue prehension. In other lizards tongue
prehension of a prey item is accomplished through adhesive
bonding and interlocking. However, adhesive properties of the
tongue are insufficient to explain the capture and transport of
large prey items in chameleons. We used high-speed
videography and cineradiography to identify an unusual pouchlike structure that engulfs the prey item. Dissection and
histological sections were used to identify a muscle that allows
the formation of the pouch. Electromyography and nerve
transection experiments confirmed the role of this muscle in
forming the tongue pouch. The relative contribution of adhesive
bonding, pouch adduction and suction forces were determined.
The results of these experiments suggest that chameleons
possess a novel suction cup like tongue that allows them to
capture large prey items.
593
596
Patterns, problems and opportunities in the study of avian
feeding systems.
RUBEGA, M.A. Univ. of Connecticut, Storrs.
Crab chela morphology underlying force generation:
Comparing vices.
SCHENK, S.C. Florida State Univ., Tallahassee.
The mouthparts of birds are extremely diverse. This great
diversity has historically attracted attention and study.
Nonetheless, avian feeding mechanics and functional
morphology remain surprisingly poorly understood, and we still
lack a widely accepted theory explaining the evolution of the
great diversity of feeding structures in birds. An analysis of the
literature revealed that 21 of 25 orders of birds have been the
subject of some form of feeding analysis. However, published
work is restricted to about 49 of 158 families of birds; thus, the
details of feeding process and apparatus are completely
unknown for about 70% of all families of birds. Most of these
studies are based on single species, and taxa have been
sampled in a manner that makes it difficult to draw inferences
Relative mechanical simplicity, coupled with morphological
and functional diversity, make brachyuran crab chelae an
excellent system for studying morphological evolution. A basic,
comparative understanding of chela functional morphology is
necessary if chelae are to be used as a model system. As yet
little comparative data on crab chela morphology exists, and no
substantive effort has been made in the literature to place
comparative data in a phylogenetic context. In this study I have
examined the muscular and skeletal morphology that underlies
force generation in crab chelae for crabs from five families:
Cancridae, Majidae, Ocypodidae, Portunidae, and Xanthidae.
Two families (Ocypodidae and Xanthidae) are represented by at
least three species, and all data will be presented in a
100A
Feeding in fishes involves transmission of force and motion
to the jaws and hyoid for jaw opening, closing and pharyngeal
expansion. Biomechanical models of fish feeding depend on a
simple set of morphometrics to predict jaw mechanics. These
models include 3rd order levers for lower jaw mechanics as well
as musculoskeletal linkages that mediate upper jaw protrusion
and hyoid depression. We describe the structural and functional
diversity of feeding mechanisms in the Labridae, a family that
occupies numerous feeding guilds including molluscivores,
piscivores, herbivores, planktivores, and corallivores. Lever
systems of the jaws show a 3-fold trade-off in force and velocity
transmission across taxa (mechanical advantage of jaw opening=
0.08 to 0.3; jaw closing= 0.2 to 0.5). Linkage systems of the jaws
show strong patterns of evolutionary change in fundamental
linkage design as well as morphometrics of transmission
systems. Phylogenetic analysis reveals that force transmission
and molluscivory are basal traits and that high-speed jaw
motions associated with evasive prey have evolved multiple
times. Supported by NSF DEB9815614 to MW and ARCA19802057 to DB and PW.
phylogenetic context. In addition to examining variation in
muscle and skeletal characters within and between crab species,
an effort will be made to determine if capacity for force
generation (by way of internal anatomy) can be predicted from
external morphological characters, and whether or not the same
external characters predict capacity for force generation in all
claws examined.
597
Spatiotemporal reorganization of growth rates in the
evolution of piranhas.
ZELDITCH, M.L* and W.L FINK. Univ. of Michigan, Ann Arbor.
weight at conception. It remains to be seen if protein malnutrition
delays the onset of reproductive aging, thus allowing the low
protein females to produce larger litters than the controls later in
life.
600
Starvation effects of diabetes Type I on ontogeny in
hamsters: Understanding female protection mechanisms
during a time of starvation-like conditions.
STEWART, S. A. Univ. of Cincinnati, OH.
598
601
Cell birth in the mammalian jaw joint.
HERRING, S.W.* and J.D. DECKER. Univ. of Washington,
Seattle.
Ontogenetic changes in duty factor and mechanical
advantage.
LAMMERS, A.R. Univ. of Cincinnati, OH.
Joints mediate movements and modulate reaction forces. In
many cases, articular surfaces are also important sites of growth.
In young animals, the demands for load resistance and growth
may conflict. The jaw joint of the pig Sus scrota is composed of
the mandibular condyle, which is compressed, and the
squamosal bone, which is bent. Both elements translate
posteriorly with growth, the condyle directly and the eminence
indirectly by sutural growth. To study the interaction of loading
and growth, we injected 16 10-month-old pigs with the
thymidine analog bromodeoxyuridine. Animals were sacrificed 10
hours later and S-phase cells were identified
immunohistochemically. Cycling cells were more numerous in
the condyle than in the squamosal (p<0.01). Further, condylar
counts were higher in the growing posterior region than in the
more loaded anterior region (p<0.01); the squamosal showed no
anteroposterior variation. In frontal sections the squamosal was
less labeled at the capsular attachments than towards the
bearing surface (p=0.01), whereas the condyle had no regional
differences. Thus condylar cell cycling is regulated primarily by
growth whereas squamosal cycling is best explained by loading.
Supported by PHS award DE11962.
While the locomotor behaviors of adults vertebrates are well
known, the ontogenetic changes in locomotion are largely
unexplored. I examined duty factor and effective mechanical
advantage (EMA) throughout the ontogeny of Chinchilla laniger,
which exclusively uses the half-bound gait even as an infant. C.
laniger were radiographed throughout ontogeny to obtain
skeletal measurements and filmed once a month using a high
speed video system to measure duty factor and limb angles. The
limb angle data and skeletal morphology were used to estimate
EMA. Duty factor is negatively correlated with body mass,
possibly as a result of the increase in speed throughout
ontogeny. EMA is not correlated with speed, which is also true in
interspecific comparisons. EMA does not change with age or
body mass. The greater duty factor of juveniles may allow them
more stability when moving. The mechanical advantage results
suggest that locomotor mechanics may not change greatly
during the ontogeny of animals which are specialized for a single
gait.
599
The impact of protein malnutrition on reproductive success.
REICHLING, T.D. Univ. of Cincinnati, OH.
Insufficient dietary protein slows growth and therefore delays
sexual maturity in Rattus norvegicus. To investigate the impact
of nutritional insult on reproductive success throughout
reproductive aging, females fed either a control or an isocaloric
low protein diet will be mated at several key ages. Results after
mating at 3 and 5 months of age show that despite having a
significantly lower body weight, low protein mothers reproduced
successfully. However, the control mothers produced
significantly more pups per litter and had a significantly higher
total birth weight. The control pups had a significantly higher rate
of postnatal growth and significanlty larger organs and muscles
at weaning. These differences in reproductive competence
between control and low protein females are correlated with
ABSTRACTS
602
Structural design of finger bones of bats.
SWARTZ, S.M.* and P. WATTS Brown Univ., Providence, Rl.
The bones of the bat dactylopatagium, or handwing, are
highly in both structure and function. They are extremely
elongated and often possess little or no medullary cavity. They
are held in appropriate anatomical position by wing membrane
tension in addition to ligaments and muscles. They are relatively
poorly mineralized, and hence both less dense and less stiff than
most mammalian bones. They experience large forces due to
large aerodynamic forces exerted on the flexible but strong wing
skin but no impact loading. Here, we employ an accurate and
well-validated computer model of flight in large flying foxes to
explore design constraints on these unusual skeletal elements.
Our model suggests that the finger bones of bats operate
unusually near performance limits: their peculiar combination of
low modulus, low second moment of area, and great length
bring them near to buckling failure during normal flight. This
analysis suggests that mechanics of the distal wing bones may
101A
Few studies explore alternatives to heterochrony, even
though such alternatives may better explain morphological
diversity. For that reason, it is difficult to say whether
heterochrony is especially common, one of several equally
common phenomena, or rare. From considerations of
development biology alone, there is no good reason to believe
that the spatial patterning of development is invariant while
timing evolves. Spatial patterning and developmental timing
might both be labile. Using geometric methods, we compare
developmental rates and ontogenetic transformations of shape.
In one case, we find that developmental rate and the ontogeny
of form are both conserved; in other cases, the ontogenies
diverge in both spatial patterning and developmental rate; and in
at least one case, spatial patterning alone is modified. In no
case, to date, do we find ontogenies that differ solely in
developmental rate or timing. Thus heterochrony, by itself,
cannot explain any of the evolutionary transformations in
ontogeny of piranha body form. Instead, each case involves
either a combination of heterotopy and heterochrony, or
heterotopy alone.
Diabetes is a condition analogous to starvation at the cellular
level. Previous studies show that males are more affected by
malnutrition than are females, suggesting a female protection
mechanism. This study tested the hypothesis of female
protection in hamsters, a species where females are larger than
males. There were a total of 44 hamsters used in this longitudinal
growth study, divided into four groups defined by the two
factors, diabetic condition and sex. Diabetes was induced in test
individuals at weaning. All individuals were radiographed and
weighed from weaning through final size. Length and width
measurements of six limb bones were collected from the
radiographs. Growth data was analyzed using the Gompertz
growth model. Analysis of variance of the Gompertz parameters
revealed that consistent non-significant differences in growth
had significant effects on final size. After euthanasia various
muscles and organs were dissected and weighed. Analysis of
covariance of final limb bone lengths and widths along with
organ and muscle weights revealed a disproportionately greater
effect on the final size of bone and muscles in the females,
however not in the organs. These results suggest that the effect
of the starvation-like condition of diabetes on growth is not a
matter of the sex, but of size.
be one factor limiting maximum body size in bats. This work is
supported by the National Science Foundation.
603
correspond to beta-sheet secondary structure while the glycine
appears to be in a random coil configuration. The results are
similar to that of dragline silk of orbweb building spiders but
different from other Latrodectus hesperus silks such as egg case
silk. Work supported by NSF grant DBI-97-11031.
How wing shape influences lift capabilities in insects.
BIRCH, J.M.* and M.H. DICKINSON. Univ. of California,
Berkeley.
606
Electrostatic forces in wind pollination.
BOWKER, G.E. Duke Univ., Durham, NC.
The presence of an atmospheric electrostatic potential
gradient of 100 Volts per meter has been known for three
hundred years. This electrostatic field may have biological
consequences by influencing pollen deposition. In the earth's
electric field, pollen transported through the air acquires positive
charge until it reaches equipotential with the surrounding air.
Using simple computer models, the electrostatic force
experienced by these charged pollen grains was explored. The
electrostatic force acting on the charged pollen grain is the
product of the charge of the pollen grain and the ambient
electric field. The gravitational and electrostatic forces have the
same magnitude for a 10 micrometer radius pollen grain at a 100
Volt potential in an electric field of 400 Volts/m. The electric field
around sharp points (like spiky stigmas or bee hairs) can locally
exceed 10,000 Volts/m. Thus, the local electrical field
surrounding a plant stigma may influence the capture of charged
pollen grains.
604
Mechanisms for helical swimming: Asymmetries in the
morphology, mechanics, and movement of ascidian tadpole
larvae(D/sfap//a occidentalis).
MCHENRY, M.J. Univ. of California, Berkeley.
Material properties of the gumfoot threads from the black
widow spider Latrodectus hesperus.
MOORE, A.M.F.' and C M . BOTHAM. Univ. of the Pacific,
Stockton, CA.
In a typical theridiid cobweb, gumfoot threads capture
ground-moving insects when the prey walks into the thread. The
thread detaches from the ground and quickly shortens while the
prey remains attached to the sticky droplets at the lower end of
the gumfoot line. Such a novel capture mechanism makes the
material properties of gumfoot silk of great interest. We
determined these properties in the black widow spider
Latrodectus hesperus by stretching 41 gumfoot threads from 8
spiders until they broke. The silks were stretched at 0.211mm/s
while force was recorded every 0.02 s. Original cross-sectional
area was measured by vibrascope and used to calculate the
stress. The stress-strain curve for this silk has an intially stiff (5.2
GPa) region. After 1-2% strain, the stiffness abruptly decreased
to 2.7 GPa. The silk breaks at an average stress of 0.47 GPa and
strain of 17.5%. These results suggest that gumfoot lines are
made of dragline silk that has been plasticized. The plasticizing
agent might be found in the sticky droplets since the whole
thread is lightly coated. Preliminary protein analysis is consistent
with this hypothesis. Supported by NSF (DBI 99-96072).
605
Secondary structure of dragline silk from Latrodectus
hesperus.
LAWRENCE, B.A.* and B. BOMER. Eastern Illinois Univ.,
Charleston.
The secondary structure of dragline silk from the cobwebbuilding spider Latrodectus hesperus was investigated using
carbon-13 solid state NMR spectroscopy. Dragline silk was
collected by forcible silking after the spiders were anesthetized,
with carbon dioxide gas, and immobilized. Approximately 45mg
of dragline silk was collected. We also obtained samples of
dragline silk enriched with carbon-13. Spiders were fed solutions
of carbon-13 enriched amino acids and the silk collected from
those spiders. Spectra were obtained with a solid state NMR
spectrometer using cross polarization and magic angle spinning
(CP-MAS) to maximize signal and narrow the peaks in the
spectrum. The position of the amino acid peaks in the spectra
have been correlated with the secondary structure of those
amino acids in the silk protein. The two major amino acids
observed are alanine and glycine. The alanine peak positions
102A
607
Although it has long been observed that many microscopic
swimmers follow a helical trajectory, the biomechanics of such
swimming are not well understood. In ascidian larvae, the
asymmetry in forces necessary for helical motion has been
speculated to be a result of the curved shape of its tail. Do
asymmetries exist in the passive mechanical properties of the tail
and in the undulatory kinematics of swimming in Distaplia
occidentalis'! All individuals were found to have tails curved to
the right. In a 3-point bending test, it was found that tails had
higher stiffness when pushed on the convex side of this curve
(towards the right) than when pushed on the concave side
(towards the left). By analyzing the axial motion of the tail in 3D
with high-speed video (500 Hz), it was found that undulatory
waves were generally of lower curvature when the tail was
moving towards the right. These results suggest that the
asymmetry in tail shape is correlated with an asymmetry in
bending stiffness that helps to facilitate asymmetrical swimming.
Such asymmetry should contribute to the turning moment
necessary for helical swimming.
608
Mechanisms of fragmentation of a gorgonian coral: Why
we're not pigs when we say 'The Weaker Sex.'
BOLLER, M.L*, T.D. SWAIN, and H.R. LASKER. Univ. at Buffalo,
NY.
Asexual reproduction of colonies via fragmentation is
important for many colonial invertebrates such as the gorgonian
Plexaura kuna. Clone size (colonies per clone) varies among
clones and sexes in P. kuna. Skeletal constrictions and material
properties contribute to natural fragmentation among colonies
and thus influence clone size. We compared morphological and
material property data of sexes and clones within sexes. Branch
and constriction diameters of tissue stripped axis were
measured in the lab. Resisting force was monitored with a load
cell as each axis was deflected until failure. The bending energy,
bending moment at failure, and modulus of rupture were
calculated. Bending energy and bending moment were
predictable by architecture but indicated a material property
difference between the sexes. The modulus of rupture was lower
in female clones, indicating weaker skeletal material. The
difference in materials properties of the sexes is concurrent with
field observations. Female clones have utilized weaker skeletons
and greater frequency of constrictions to create larger numbers
Previous research has shown that three components
contribute to lift-generating capabilities in insects: delayed stall,
rotational circulation, and wake capture. Delayed stall generates
forces at high angles of attack that are in excess of steady-state
translational forces. Rotational circulation generates forces while
the wing twists during stroke reversals. Wake capture generates
forces during stroke reversal when the wing travels through the
wake of the previous stroke. These stroke-reversal forces can
account for roughly 35% of total lift production. We wanted to
test how changes in wing shape might influence the relative
contributions of each of these three lift mechanisms. We
measured the forces a wing experiences using a robotic fly
programmed to emulate kinematic patterns seen in insects. All
wing shapes had identical lengths and areas, but different
leading and trailing edges, as well as different areas in front of
and behind the axis of rotation. Enlarging the area behind the
axis of rotation augments lift by increasing rotational circulation,
while enlarging the area in front of the axis of rotation augments
lift through wake capture. Thus, different wing shapes extract lift
forces from various combinations of translational and rotational
forces, depending on the relationship between wing area and
axis of rotation.
of colonies when disturbances provide them the opportunity to
asexually reproduce.
data suggest that in order to maneuver, insects could bilaterally
alter the forces on their wings in multiple ways.
609
612
Cyberkelp: Creating a virtual reality for the kelp Nereocystis
leutkeana to investigate the optimality of its material
properties.
HALE, B.B. Hopkins Marine Station, Pacific Grove, CA.
Venation patterns and flexural stiffness in insect wings.
COMBES, S.A.* and T.L DANIEL. Univ. of Washington, Seattle.
610
Laminaria sacchahna in mussel beds, holding on for dear
life.
GRACE, S.P. Univ. of Rhode Island, Kingston.
At one site in the Narragansett Bay, the tenacity (attachment
strength) of the kelp Laminaria saccharina was determined in and
out of mussel bed areas. With a recording spring scale, the force
required to remove just the blade (pruning) and remove the
holdfast (clearing) was examined in areas where mussels were
not present and algal holdfasts directly attached to bare
substrate and in areas where mussels were present under the
algal holdfasts. T-tests were used to compare the force required
to prune and clear algae within and area and between mussel
beds and bare substrate. Results indicate the L saccharina in
mussel beds are significantly weaker than kelps attached to bare
substrate, and show on bare substrate a significant difference
between the force required to prune and clear algae. The blue
mussel Mytilus edulis may recruit to the holdfasts of the kelps for
refuge from predation or dislodgement, and ultimately weaken
the attachment strength of Laminaria saccharina increasing the
probability of dislodgement.
613
Maneuverability and unsteady aerodynamics in insect flight.
LEHMAN, F.O. Univ. of Wuerzburg, Germany.
Insects were the first animals to evolve active flight and
remain unsurpassed in many aspects of aerodynamic
performance and maneuverability. Force measurements in a
dynamically scaled robotic insect reveal that the enhanced
performance of a flapping insect wing results from three distinct
unsteady aerodynamic mechanisms: delayed stall, rotational
circulation and wake capture. In addition to force production by
flapping one wing, insects enhance total lift production through
the interaction of both wings at the dorsal stroke reversal. The
'clap and fling' is a close apposition of the two wings preceding
pronation and is thought to enhance aerodynamic circulation at
the beginning of the down stroke. Lift production during the
stroke of the robotic insect suggest that in the fruit fly, clap and
fling contributes between 5 and 10% to total flight force
production. Reconstruction of wing movement during yaw torque
maneuvers indicates that tethered flying fruit flies actively
modulates the timing of wing rotation during clap and fling within
a 0.2 ms range, whereas angular velocity of wing rotation does
not change. Because the contribution of clap and fling to total lift
is small compared to delayed stall, rotational circulation and
wake capture, fruit flies may primarily use clap and fling to
modulate flight forces in order to enhance both flight stability
and maneuverability.
611
614
Influence of wing kinematics on force generation during
insect flight maneuvers.
SANE, S.P.* and M.H. DICKINSON Univ. of California, Berkeley.
A tale of two tree frogs: Comparing the habitat and gliding
behavior of two species of tree frogs.
MCCAY, MICHAEL G. Univ. of California, Berkeley.
Insects perform complex flight maneuvers by subtly altering
their wing kinematics. These alterations allow insects to generate
differential aerodynamic forces on their two wings necessary for
generating turning moments. To study how specific wing
kinematics influence aerodynamic force generation, we
programmed a dynamically scaled robotic fly to flap its wings
simulating insect-like kinematic patterns. We systematically
varied stroke amplitude, angle of attack, flip timing, flip duration
and the angular deviation from the mean stroke plane, and
measured the forces generated on a wing using a 2-D force
sensor. Our data show that for constant flip timing, flip duration
and deviation, the average forces increase with increase in
stroke amplitude. Expectedly, as we vary the angles of attack
from 0 to 90 degrees, the forces increase up to 45 degrees but
decrease above 45 degrees. Further, the duration and phase of
wing flip also influence forces on the wing. Short duration, high
angular velocity flips generate higher forces provided that they
are timed to end at the onset of stroke reversal. In summary, our
Among the eight species of the Hylid tree frog genus
Agalychnis, at least 3 species are reported to use gliding in the
field. Gliding without turning requires a combination of active
stabilization (postural changes that control the frog's direction of
gliding), and passive stabilization (passive interaction of the
frog's morphological features with the air flow around the frog). A
previous study compared the passive aerodynamic stability of
three species of tree frog with varying morphological
characteristics (size of hands/feet relative to body, webbiness of
hands/feet) and found very low levels of passive stability for all
species of tree frog studied. This result indicates that either
gliding tree frogs glide in an environment that is free of wind
gusts, or that gliding tree frogs make use of active stabilization. I
studied Agalychnis tree frogs at the OTS La Selva field station in
Costa Rica. I measured wind speeds and habitat structure near
the frog's mating sites where the tree frogs are reported to glide,
as well as videotaping the frogs gliding in free air. In addition, I
ABSTRACTS
103A
The interaction between the material properties of the Bull
Kelp, Nereocystis leutkeana, and the dynamic loading of the kelp
under ocean waves is investigated through a novel integration of
computer modeling and dynamic material testing. The stipe of
Nereocystis is viscoelastic, and thus its material properties (e.g.
stiffness, resilience, strength...) depend on both the strain and
the strain rate of the loading process. The loading of the stipe in
the field depends likewise on the material properties of the stipe
itself, much like the loading on a bungee jumper depends on the
stiffness and resilience of the bungee. To investigate this
interaction, a computer model describing the dynamic behavior
of Nereocystis under unbroken waves is incorporated into the
program driving the tensometer in which a Nereocystis stipe is
clamped. In this integrated, closed-loop system, the values for
stress used in the computer model are those measured directly
in the tensometer, and the strain and strain rate produced in the
tensometer are taken in real time from the computer model. The
kelp stipe is thus loaded as it would be were it in situ under
ocean waves. The optimality of the material properties of
Nereocystis stipe may thus be tested by comparing the results of
the closed-loop material tests with those of pure computer
models.
Wing bending and twisting during flapping flight can
profoundly affect air flow and aerodynamic force production. In
insects, the interaction between patterns of supporting veins and
flight forces determine dynamic shape changes of wings.
Derived groups of insects show marked reduction in wing
venation, which could have functional implications for flight. We
approach this hypothesis by quantifying the flexural stiffness (El)
of a range of insect wings subject to simple point-force bending
in both the spanwise and chordwise directions. We find an
exponential increase in flexural stiffness with wing size.
Spanwise flexural stiffness ranges from 2 x 10"8 Nm2 in the
smallest insects tested to 9 x 10~5 Nm 2 in the largest. All wings
show significant anisotropy, with flexural stiffness in the
chordwise direction approximately two orders of magnitude less
than in the spanwise direction. In addition, insects with reduced
wing venation have slightly lower wing flexural stiffness than
expected for their size, while basal groups with extensive wing
venation have slightly higher flexural stiffness. (NSF grant IBN9511681)
analyzed the gliding behavior of the tree frogs gliding in a tilted
wind tunnel.
615
A 3-D computer-animated analysis of pigeon wing
movement.
GATESY, S.M.* and T. ALENGHAT. Brown Univ., Providence, Rl.
616
Mechanical power output of anseriform birds in flight.
WILLIAMSON, M.R.1, K.P. DIAL, and A.A. BIEWENER. Harvard
Univ., Cambridge, MA, and Univ. of Montana, Missoula.
The apparent degradation of avian flight performance with
increasing body size has traditionally been ascribed to sizedependant limitations in power output. To investigate the
relationship among power output, flight performance and body
size, a direct assessment of mechanical power output of the
flight muscles of anseriform birds was made, using burst takeoff
and slow level flight as indices of maximum and moderate
performance, respectively. Mechanical power output was
determined using in vivo measurements of pectoralis fascicle
length and delto-pectoral crest strain. Mean power output in
mallards {Anas platyrhynchos) ranged from 20.7 W/kg body mass
(156 W/kg pectoralis mass) in takeoff to 15.8 W/kg body mass
(120 W/kg pect. mass) in slow level flight, confirming predicted
relative power requirements of each behavior. Mean values for
work, peak force, and wingbeat frequency were similarly greater
in takeoff than in level flight, although high variability was
exhibited in both flight modes. Preliminary data for blue-winged
teal {Anas discors), an anseriform one-third the size of the
mallard, suggest that mass-specific power output may be
independent of body size.
617
Three-dimensional kinematics of the hindlimb during
locomotion vary ontogenetically in lizards.
IRSCHICK, D.J.* and B.C. JAYNE. Univ. of Cincinnati, OH.
The effects of ontogeny on locomotor performance are welldocumented, but the extent to which limb movements differ
ontogenetically is poorly understood. To determine if limb
movements change with size, we quantified the hindlimb
kinematics of three size classes (5,12, and 60 g) of the lizard
Dipsosaurus dorsalis running steadily at 100 cm/s (walk-run
transition) and 250 cm/s. In addition to the expected increase in
stride frequency with decreased size, several angular variables
differed significantly with size. Smaller lizards had more pelvic
rotation, but larger lizards had more femur retraction. Smaller
lizards had more extended knee and ankle joints at footfall, but
extended the knee joint less at the end of stance compared to
larger lizards. The locomotion of small lizards at slow speeds
had many of the characteristics of high-speed locomotion in
large lizards, such as relatively high hip heights, and large knee
and ankle angles.
104A
Effects of speed on the activity and length change in a
locomotory muscle of a lizard.
NELSON, F.E.* and B.C. JAYNE. Univ. of Cincinnati, OH.
For many ectothermic tetrapods, the caudofemoralis muscle
(CF) is the largest appendicular muscle; however predicting CF
function is complicated because the muscle spans both the hip
and knee joints. We used electromyography, sonomicrometry
and three-dimensional frame-by-frame kinematics to determine
CF function in the desert iguana, Dipsosaurus dorsalis moving at
steady speeds of locomotion ranging from 50 to 250 cm/sec.
Changes in the length of the CF con-elated with femur retraction,
femur rotation, and knee flexion. The effect of knee angle on CF
length was substantial when the femur was maximally protracted
but minimal when the femur was perpendicular to the body or
retracted. For each cycle of lengthening and shortening, the
minimum and maximum lengths and the change of length in the
CF all increased significantly as the speed of locomotion
increased. With increased locomotor speed the proportion of the
cycle for which the CF shortened decreased. The shortening
velocities of the CF ranged from 1 to 3 lengths/sec at the
slowest speed of locomotion and were four times greater at the
fastest speed of locomotion.
619
Temporal variation of locomotor performance in a
demographically known population of the banded rock
lizard, Petrosaurvs mearnsi.
ROBSON, M. A. Univ. of Pennsylvania, Philadelphia.
Performance has been argued to be a critical intermediate
link between lower level traits, e.g., morphology, and upper level
traits, e.g., fitness. Prior studies have demonstrated considerable
amounts of intraspecific variation in performance. Evidence
suggests an association between locomotor performance and
morphology. However, whether such variation has a selective
component is poorly known. Several factors may alter the
strength of the association, i.e., climatic variation. Attempts to
elucidate the relationship between these whole-body
physiological measures and other components of the organism's
life history; be it behavior, growth, survivorship or fecundity, have
typically employed short intervals (1 or 2 seasons) but represent
an important step in linking performance and fitness. As part of a
long-term study initiated in 1995 on a population of P. mearnsi
locomotor performance was recorded from 1996-99. This
involved measuring maximum sprint speed and endurance
utilizing an electronic racetrack and portable treadmill. The
current study addresses: (1) whether performance is a
physiologically consistent trait, (2) how performance changes
annually, (3) if a shift in performance is due to changes in
individual performance or in the age structure of the population,
and (4) the effect of analyzing performance longitudinally (agespecific) vs. cross-sectional (annual)?
620
The take-off and landing kinematics of a flying snake,
Chrysopelea ornata.
SOCHA, J.J. Univ. of Chicago, IL.
In contrast to limbed vertebrate fliers, snakes that 'fly' must
rely on movements of the axial column both to generate forward
momentum during take-off and to prevent injury during landing.
Digital video recording was used to observe these kinematic
mechanisms in six specimens of Chrysopelea ornata during takeoff from a horizontal branch and landing on the ground and other
substrates. The positions, velocities, and accelerations of the
head, body, and tail were quantified for each behavior. Typical
take-offs involve the following kinematic sequence: with the head
parallel with the ground, the anterior half of the body is lowered
from the branch into a U-shaped loop. At this point the head is
approximately one quarter the distance from the bottom of this
loop. To begin the jump, the head is successively accelerated
upwards and then horizontally away from the branch. The
posterior half of the body remains approximately stationary on
the branch until the body straightens out in the air, at which
point the snake is parallel with the ground. The snake then
dorsoventrally flattens and begins its airborne lateral undulation.
Similar kinematics have been observed in individual specimens
The forelimb skeleton represents a crucial link between the
neuromuscular and aerodynamic mechanisms of avian flight.
However, accurate joint angle measurement has remained
elusive due to the wingbeat's 3-D complexity. We reconstructed
and quantified skeletal motion from X-ray films of pigeons flying
in a wind tunnel using AliaslWavefront Studio 8.5 animation
software. Wing bones were scanned to create polygonal models,
from which NURBS models were constructed. Bone models
were linked to an articulated framework, which was manipulated
with control sliders (one slider per degree of freedom). Digitized
frames of a pigeon flying 12 m/s were imported as background
images. The wing model was then superimposed on sequential
images in front of a parallax-corrected virtual camera. After
alignment, the position of control sliders was saved (keyframed)
to quantify joint angles and create animated wingbeats. Our
results facilitate calculation of inertial power and musculotendon
length, assessment of subtle variations responsible for changes
in speed, as well as visualization and communication of the
wingbeat's true 3-D motion. Supported by Brown University and
AliaslWavefront.
618
of C. paradisi and C. pelias, suggesting that this take-off
behavior may characterize the genus. Video highlights will be
shown.
621
How gecko feet work.
AUTUMN, K.*, T. HSIEH, W. ZESCH, W.-P. CHAN, R. FEARING,
and R. J. FULL. Lewis & Clark College, Portland, OR and Univ. of
624
Mechanical properties of limb bones in runners versus
fighters.
KEMP, T. J.*, K. N. BACHUS, B. M. PASI, and D. R. CARRIER.
Univ. of Utah, Salt Lake City.
In some lineages, adaptations that facilitate fighting may
conflict with those that enhance locomotor speed and stamina.
To address this we compared the mechanical properties of the
humerus, radius, third metacarpal, femur, tibia, and third
metatarsal in two breeds of domestic dog that have experienced
strong selection, Greyhounds and Pit Bulls. From three point
static bending measurements, we found that bone of
Greyhounds failed at lower stains, but at higher stresses. In all
six bones the modulus of elasticity was 1.5 to 3 times higher in
the Greyhounds than in the Pit Bulls. Analysis of the bone tissue
showed no difference in porosity, but a 1 to 2 % higher mineral
content in the Greyhounds. The higher modulus of elasticity in
the Greyhounds is likely due, at least in part, to the higher
mineral content of their bones. We suspect that the lower
modulus of elasticity and higher strain to failure found in the limb
bones of Pit Bulls may indicate a greater capacity to absorb
energy and may reflect selection for physical combat.
622
625
Mechanical interactions between locomotion and ventilation
in humans.
DALEY, M. A.* and D. M. BRAMBLE. Univ. of Utah, Salt Lake
City.
Age-dependent differences in locomotor biodynamics in
canids.
BIKNEVICIUS, A.R.* and B. SUCHOWIECKI. Ohio Univ., Athens.
Locomotor-respiratory coupling (LRC) has been widely
observed in humans, but its significance is poorly understood.
To investigate whether LRC has mechanical significance in
running humans, we analyzed the mechanical interactions
between locomotion and breathing during treadmill exercise. We
recorded respiratory flow and vertical trunk acceleration from
subjects running at constant speeds. Synchronized video was
used to check the correlation between body motion and vertical
acceleration. LRC patterns, phase angles of respiratory events to
step cycle, and the correlation between acceleration of
ventilatory gas and vertical trunk acceleration were determined.
All subjects had a strong bias toward the initiation of inspiration
and expiration near heelstrike, although only half were coupled.
Further, the higher frequency accelerations of ventilatory gas had
consistent phase relationships to the step cycle. Lastly, breaths
initiated in the 'preferred' region of the step cycle had initial
accelerations 3 times greater than breaths initiated in the least
preferred region. These results suggest that significant
mechanical interactions exist between locomotion and ventilation
in human runners. We propose a mechanical model to account
for these interactions.
623
Muscle architecture and distribution in runners versus
fighters.
PASI, M.* and D. R. CARRIER. Univ. of Utah, Salt Lake City.
In some lineages, adaptations that facilitate fighting may
conflict with those that enhance locomotor speed and stamina.
To address this, we compared muscle architecture and
distribution in two breeds of domestic dog that have
experienced strong selection, Greyhounds and Pit Bulls.
Measures of muscle and tendon cross-sectional area and tendon
length allowed us to estimate each breed's potential for elastic
storage. Our calculations suggest that the ankle extensor
muscle-tendon systems of Greyhounds can store approximately
2.5 times more energy than those of Pit Bulls. This is consistent
with the expectation that animals specialized for fighting will
ABSTRACTS
While early postnatal (< 10 weeks) locomotor kinetics have
previously been found to differ from adult patterns in trotting
dogs (e.g., lower relative magnitudes of vertical forces applied by
hind versus forelimbs in juveniles), most aspects of locomotor
dynamics in domestic dogs ranging in age from 24 weeks to 3
years did not reveal significant age-related differences when the
effects of mass and body size were controlled. Parameters
evaluated included ground reaction forces, estimated tibiotarsal
(hock joint) extensor muscle forces, and estimated tibial stress
levels. The contrasts in these results point to differences in the
juvenile and adult conditions that are resolved within the first six
months of locomotor behavior. Supported by NSF.
626
The role of the head and neck during equine locomotion.
BERTRAM, J.E.A, K.S. GELLMAN*, and J.W. HERMANSON,
Florida State Univ., Tallahassee, and Cornell Univ., Ithaca, NY.
Horses use different patterns of head movement in their
three principle gaits. Using an inverse dynamic analysis of the
head motion in vivo, and an ex vivo analysis of the elastic strain
energy stored in the nuchal ligament at a range of head
positions, we show that the nuchal ligament provides from 30 to
60% of the mechanical work done on the cervical-thoracic
junction as the head and neck oscillate. The kinematic and
dynamic analyses indicate that head movement is an intrinsic
part of locomotion and that the pattern of head movement is
linked to the fundamental gait mechanisms. The principle
cervical muscles, the splenius and semispinalis capitus, have
been characterized morphologically, with quantitative
histochemical analysis (NADH, GPD, myosin ATPase and
immunohistochemistry) and morphometry (nitric acid digestion).
It was found that both these muscles are primarily SO and FG (<
0.5% intermediate) fiber types. The semispinalis shows
significant compartmentalization, with a gradient of SO fibers
decreasing from rostral to caudal (92%-62%). Differences in fiber
type composition, fiber length and muscle architecture imply that
these two muscles are utilized for different functions by the
animal
105A
Geckos are exceptional in their ability to climb rapidly up
smooth vertical surfaces at over 15 body length/sec. This is an
extraordinary feat that requires extraordinary feet. Prior work has
shown that the adhesive toe pads of the front feet of a Tokay
gecko can resist up to 20 N of force when pulled down a smooth
surface. Since stickier adhesives generally require larger
detachment forces, one predicts that large forces should be
involved in detachment of the toe pads. By using a force plate
(Hsieh et al. 1998), we showed that geckos running vertically are
able to rapidly detach their pads without measurable detachment
forces. The ventral surfaces of the toe pads are packed with
dense rows of keratinous setae. It is well known that the toes of
geckos peel away from the surface during detachment, thereby
concentrating the detachment force to a small subset of setae.
To examine whether detachment is facilitated at the micro-scale,
we isolated a single seta from a Tokay (Gekko gecko) and
allowed it to adhere to a wire force gauge. By using video
microscopy, we discovered that single setae detach at a
constant angle relative to the substrate (30.6° ±1.8 SD),
independent of the force required for detachment. This critical
angle suggests that rotation of the seta may permit detachment
of the toe pad without the need for large forces. DARPA
N00014-98-C-0183.
have a limited capacity for elastic storage. The ratio of triceps
cross-sectional area to quadriceps cross-section area is smaller
in Greyhounds than in Pit Bulls. This may indicate that animals
specialized for fighting rely more on forelimbs for acceleration
than do animals specialized for running. Finally, distal limb
muscle mass is a smaller percentage of total limb muscle mass
in Greyhounds than in Pit Bulls. This is consistent with the tenet
that animals specialized for fast running have reduced mass in
the distal limbs so as to lower the internal work of locomotion.
627
Age differences in the kinematics of the fetlock joint of the
leading forelimb during galloping in thoroughbred
racehorses.
BUTCHER, M.T.* and M.A. ASHLEY-ROSS. Wake Forest Univ.,
Winston-Salem, NC.
628
The biomechanics of penguin walking.
GRIFFIN, T.M.*, Y.-H. CHANG, and R. KRAM. Univ. of California,
Berkeley.
Penguins consume twice as much oxygen to walk a given
distance compared to other similarly sized animals. Many
animals reduce the mechanical work of walking with an inverted
pendulum-like exchange of the gravitational potential energy and
kinetic energy of the center of mass. Because walking penguins
undergo large lateral displacements, we hypothesized that the
. inverted pendulum mechanism would be less effective and
penguins would perform more mechanical work than other
similarly sized animals. We collected ground reaction force data
as emperor and king penguins walked across a force platform at
various speeds. Contrary to our hypothesis, the emperor and
king penguins recover 60-80% of the total mechanical energy of
the center of mass, among the highest values reported for any
animal. Consequently, the average mechanical work performed
by penguins (0.4 J/kg/m) is less than half that of other similarly
sized animals. Thus, mechanical work does not account for their
high metabolic cost of transport. A more viable explanation for
the high cost of penguin walking may be the relatively rapid
generation of force to support body weight. Ground contact time
data corroborate this idea.
Authors thank SeaWorid San Diego, supported by NIH
AR44688.
629
Differential leg function in sprawled-posture quadrupedal
trotters.
CHEN, J.J.*, A.M. PEATTIE, K. AUTUMN, and R.J. FULL. Univ.
of California, Berkeley, and Lewis & Clark College, Portland, OR.
Each leg of upright-posture quadrupeds exhibits spring-mass
behavior during trotting. A leg generates a deceleration followed
by an acceleration in the direction of motion. Sprawled-posture
arthropods show spring-mass behavior of the body, but each leg
pair functions differently. We measured single leg forces of a
sprawled posture quadruped (the gecko, Hemidactylus garnoti;
2.6±0.1 g) running on a level track embedded with a 3D force
platform. Three high-speed cameras operating at 1000 frames/s
showed geckos ran with constant average velocity at up to 75
cm/s (mean = 47.0±3.3 cm/s) with a mean stride frequency of
12.6±0.5 Hz. The mass-specific mechanical work output (2
W/kg) was similar to other animals. Whole-body ground reaction
forces showed that geckos use a spring-mass mechanism in
which kinetic energy and gravitational potential energy of the
body fluctuate in phase. Single-leg forces revealed that unlike
mammalian quadrupeds, geckos exhibit differential leg function.
Geckos running on a ievei primarily decelerated with their front
legs while hind legs generated both decelerating and
106A
630
Hindlimb-trunk proportions in theropod dinosaurs, cursorial
birds, and the feathered dinosaur ""Caudipteryx zhoui."
JONES, T. D.* and W. J. HILLENIUS. Oregon State Univ.,
Corvallis, and College of Charleston, SC.
Cursorial locomotor strategies are reflected in hindlimb-trunk
proportions. Theropods whose center of gravity is located near
the acetabulum were ""thigh-runners wherein the hindlimb
swung in a pendulum-like fashion with each stride. In contrast,
the center of gravity of cursorial birds is well forward of the distal
end of the hip joint, as it was in their flighted ancestors. To
compensate, the distal end of the femur remains anteriorly
situated during a stride, and the tibiotarsus swings in a
pendulum-like manner. Consequently, theropods have a
relatively shorter hindlimb than cursorial birds and their hindlimb
length/trunk length ratios are significantly different. These data
are used to determine the likely avian cursorial locomotor
strategy of Caudipteryx zhoui, which calls into question the
dinosaurian nature of this animal.
631
Time of contact and step length are a function of running
speed and leg length.
HOYT, D. F.*, S. J. WICKLER, and E. A. COGGER. California
State Polytechnic Univ., Pomona.
The metabolic cost of locomotion varies with body mass and
running speed (v: m/s). The time of contact (tc = duration of the
stance phase of the stride - in seconds) explains most of this
variation but it is not known what determines t c . It has been
assumed that step length (product of speed and t j is
independent of speed but the spring-mass model predicts an
increase with speed. Using published values of t c for 11 species
of birds and mammals plus our data on the horse, we
investigated the dependence of t c on running speed and leg
length (L in meters - predicted allometrically) by performing a
multiple regression on log-transformed values. Our analysis
yielded the following relationship: log t c = -0.097 + 0.84 log L 0.87 log vR2 = 0.97. The coefficient for v in this relationship is
significantly different from -1.0, indicating that step length
increases with speed. The coefficient for L is different from 1.0,
indicating that small species run with an average relative step
length (step length /leg length) that is longer than larger species
at the same running speed. Supported by NIH 1 S06 GM53933.
632
Locomotion in the Japanese Quail: The kinematics of
walking and increasing speed.
REILLY, S.M. Ohio Univ., Athens.
Hindlimb segmental kinematics and stride characteristics are
quantified in several quail locomoting on a treadmill over a sixfold increase in speed. In Japanese quail the femur did not move
during locomotion and the tarsometatarsus-phalangeal joint is a
major moving joint; thus, quail have lost the most proximal
moving joint and added one distally. The tibiotarsus and
tarsometatarsus act together as a fixed strut swinging from the
knee during stance phase and the tarsometatarsus-phalangeal
joint appears to have a major role in increasing limb length
during the propulsive phase of the stride. Speed is increased
with greater knee extension and increased ankle extension.
Because the femur is not moved and three distal elements are,
quail move the limb segments through a stride and increase
speed in a way fundamentally different than other non-avian
vertebrates. However, the three moving joints in quail (the knee,
ankle, and tarsometatarsophangeal joint) have strikingly similar
kinematics to the analogous moving joints (the hip, knee and
ankle) in other vertebrates. Comparisons to other vertebrates
indicates that birds appear to have two modes of limb function
(three- and four-segment modes) that vary with speed and
locomotory habits.
The purpose of this study was to determine if there are
differences in the kinematics of the fetlock joint of the leading
forelimb in both younger and older Thoroughbred racehorses
during race training. Six two- and three-year-old Thoroughbred
racehorses and six four- and five-year-old Thoroughbred
racehorses were videotaped using a Redlake 1000S high-speed
video system at 250 frames/second at a daily workout gallop on
a 7/8 mile sand-surface training track. Four galloping strides
were recorded for each horse and subsequently digitized. From
the digitized stride images, fetlock joint angles of the leading
forelimb were determined from the impact phase of limb support
through the breakover phase. Three variables were measured
from each stride: the average maximum degree of fetlock joint
dorsi-fiexion, maximum angular velocity from impact to midstance, and maximum angular velocity from mid-stance to
breakover. Average maximum dorsi-flexion and angular velocity
from mid-stance to breakover were greater in the older
population, while maximum angular velocity from impact to midstance was greater in the younger horses.
accelerating forces. Lateral forces equaled or exceeded fore-aft
forces. As in arthropods, sprawled-posture quadrupeds could
benefit from the stability provided by lateral and opposing leg
forces. Supported by DARPA N00014-98-C-0183.
Evolutionary Developmental Biology:
Paradigms, Problems and Prospects
by Schmaihausen dismissed by Waddington) saw developmental
plasticity as a selectable trait.""
636
633
General introduction to the symposium on evolutionary
developmental biology: Paradigms, problems, and prospects.
BUR1AN, R.M. Virgina Polytechnic Institute and State Univ.,
Blacksburg, VA.
Richard Goldschmidt's controversial theory of saltational
evolution was in his view a phyiogenetic consequence of his
theory of the gene. In this paper, I consider how Goldschmidt's
views on evolution were integrated with his theories of
development and genetics. From 1940 until his death in 1958,
Goldschmidt presented two parallel schemes of integration,
using one to argue by analogy for the other. The first scheme
included genes and argued that new species arose as hopeful
monsters from mutations in developmental^ significant loci. The
second replaced genes with a hierarchy of chromosomal
repatternings and argued that systemic repatternings produced
new species. While the first scheme was relatively well received,
the second was not, despite Goldschmidt's attempts to refine it
with his analysis of homeotic mutants. Nevertheless, both
schemes hold lessons for contemporary efforts to integrate
development, evolution, and genetics.
637
634
History of the concept of allometry.
GAYON, J. UniversitE Paris, France.
Batfour, Garstang and De Been The first century of
evolutionary embryology.
HALL, B.K. Dalhousie Univ., Halifax, Canada.
Julian Huxley and Georges Teissier coined the term
"allometry" in 1936. In a joint paper, these authors agreed to use
this term in order to avoid confusion in the field of relative
growth. Julian Huxley is often said to have discovered the law of
constant differential growth (y = bx*) in 1924, but a similar law
had been already discovered earlier by several authors, in
various disciplinary contexts, and under various names. Three
decades before Huxley, Dubois and Lapicque used a power law
and logarithmic coordinates for the description of the relation
between brain size and body size in mammals, both from an
intraspecific, and an interspecific, point of view. Later on, in the
1910s and early 1920s, Pézard's and Champy's work on
sexual characters provided decisive experimental evidence in
favor of a law of relative growth at the level of individual
development. This paper examines (1) These early works on
relative growth; (2) the line of research that led to Huxley's
"discovery"; (3) Huxley's role in generalizing the concept of
differential growth and emphasizing its role in evolution; (4)
Teissier's and Huxley's joint paper of 1936, and Teissier's
specific contribution, especially his rigorous and important
distinction between "allometry of growth" (in individuals) and
"allometry of size" (intraspecific and interspecific comparisons);
and (5) the role of allometry in evolutionary theory after Huxley,
especially in the context of paleobiology: allometry as a measure
of heterochrony (White, Gould), and as a controversial case of
nonadaptive evolution.
My aim is to discuss the foundations of evolutionary
evolutionary embryology in the UK. from 1870, when 'every
aspiring zoologist was an embryologist, and the one topic of
professional conversation was evolution' (Bateson, 1922, p. 56)
to the 1970s. The foundation rested on shared and conserved
developmental stages, the universality of germ layers, linkage of
embryology to classification (diplo- and triploblastic grades), and
an embryological criterion of homology. Balfour discovered the
homology of the avian primitive streak with the amphibian
blastopore. His textbook was infused with evolutionary thinking,
but his death coincided with a major decline in evolutionary
embryology in the 1880s. Garstang saw that ancestry should be
sought in larval stages; that many larval features are secondary
adaptations to larval life and so lack phyiogenetic information (he
coined paedomorphosis), and that ontogeny creates phylogeny.
De Beer, whose comparative vertebrate anatomy was grounded
in embryology, sought to unite evolution and embryology
through heterochrony, and to separate homology from the strait
jacket imposed by strict embryological criteria. Supported by
NSERC (Canada) and the Killam Trust of Dalhousie University.
635
Baldwin, Waddington, and Schmaihausen and the
foundations of evolutionary developmental biology.
GILBERT, S.F.* and G.E. ALLEN. Swarthmore College, PA, and
Washington Univ., St. Louis, MO.
The synthesis of embryology, genetics, and evolutionary
biology has had many forms. The diachronic biology"" of C.H.
Waddington. emphasized the transfer of developmental
competence such that a response initiated by an environmental
inducer could be transferred to an embryological inducer. Such
changes could be selected and would lead to the apparent
genetic assimilation of the physiologically induced trait. I.I.
Schmaihausen developed a similar integration of embryology
genetics and evolution. Their emphases however were different.
For Schmaihausen stabilizing selection completed the Modem
Synthesis but it could not produce novel organisms. To
Waddington stabilizing selection complemented the synthesis
and provided a mechanism for the generation of new
morphological structures. Moreover Waddington attempted to
experimentally demonstrate genetic assimilation. Both
Waddington and Schmaihausen were preceded by the
developmental psychologist J. M. Baldwin whose work (quoted
ABSTRACTS
638
Phytogeny and development from Willi Hennig onward.
DONOGHUE, M.J. Harvard Univ., Cambridge, MA.
My aim is to review the relationship between phyiogenetic
and developmental biology from Willi Hennig to the present.
Much has been said about estimating phyiogenetic relationships
using developmental evidence, especially ontogenetic criteria for
inferring the direction of character evolution. However, with
increasing attention to molecular evidence and the availability of
more and better phyiogenetic hypotheses, the emphasis has
shifted to how phyiogenetic knowledge might illuminate studies
of development. Also of increasing interest is how knowledge of
development can help explain patterns of character change
evident in phylogenies. Several examples from plants will
highlight developmental causes and consequences of the
evolutionary recurrence of form.
107A
The symposium has three principal tasks: (1) to examine
some of the historical background to the current renaissance in
biological studies linking evolution and development, (2) to
review the current status of research in this rapidly changing
area, especially the linkage of molecular to morphological
studies and the benefits and difficulties of molecular studies of
the relationship between evolution and development, and (3) to
help set the agenda for what might be accomplished in evo-devo
during the next few years. In the introduction to the symposium,
I will remind us of some of the older ways of formulating
questions about the relevance of development to evolution due
to such figures as Bateson, Johannsen, and Goldschmidt. I will
suggest that current research needs to address some of these
questions, abandoned long ago as intractable, because the
questions were legitimate and we have recently acquired
techniques that may enable us to answer some of them.
From hopeful monsters to homeotic effects: Richard
Goldschmidt's integration of development, evolution, and
genetics.
DIETRICH, M.R. Dartmouth Univ., Hanover, NH.
639
642
Modularity in development and why it matters to devo-evo.
BOLKER, J.A. Univ. of New Hampshire, Durham.
Developmental characters and phylogenetic systematics.
MABEE, P.M. Univ. of South Dakota, Vermillion.
Both evolutionary and developmental biologists have found
modularity a useful concept for describing and explaining
patterns of metazoan organization, from body segmentation to
the structure of signal transduction pathways. If the concept is
also to serve as a meeting point between devo and evo, we need
to agree, at least approximately, on what we mean by the term.
The search for a consensus definition raises both obvious
questions ('What exactly is modularity?') and subtler issues
('How do our working assumptions incorporate unstated
definitions of modularity?'). I will examine explicit and implicit
definitions of modularity in developmental biology, and argue
that recognizing developmental modules is essential to rigorous
comparative analyses, which are in turn central to evolutionary
studies of development. Most current developmental biology
focuses on a small number of model species rather than
engaging in comparisons, and much current thinking about the
evolution of metazoan development overlooks the extent of
developmental diversity. In the long run, detailed studies that
compare developmental modules rather than entire organisms or
ontogenies are the most likely to yield deep insights into how
development works and evolves.
Phylogenetic systematics has transformed many fields such
as behavior, physiology, ecology, and epidemiology, which have
sought to incorporate an evolutionary viewpoint. In contrast,
developmental biologists have almost completely ignored the
analytical methods of phylogenetic systematics, in spite of great
interest in incorporating an evolutionary perspective. My goal is
to argue not only the utility, but the necessity and productivity of
such an approach. When developmental features are compared
with a known evolutionary history for a group of organisms, new
and often fundamental problems in development and evolution
emerge. The phylogenetic history of numerous taxa is well
understood, and their "key" evolutionary features, typically
morphological characters from adults, have been hypothesized
by systematists. Using such reconstructions as a resource and
starting point, I present several such problems. Phylogenetic
methods for character "mapping" are important for explicit
interpretation of the evolution of development, and examples of
this approach from vertebrate evolution are given.
Homology in development and the development of the
homology concept.
LAUBICHLER, M.D. Princeton Univ., NJ.
Assessments of homology are the mainstay of comparative
biology. Yet the homology concept is still among the more
controversial notions in biological theory. Especially the
distinction between homology as a statement of phylogenetic
relationship as opposed to the mechanistic causes for homology
(the biological homology concept sensu Wagner) is not yet
resolved. Another question is how similarities between
sequences and expression patterns of genes in development
relate to ideas of homology on the level of phenotyopic
characters. Here I will analyze the development of these different
interpretations of homology over the period of the last 80 years
and propose an analytic framework that allows us to see the
implications of each of these different definitions of homology. I
will begin my analysis with Spemann's important essay from
1915, 'Zur Geschichte und Kritik des Begriffs der Homologie (A
History and Critique of the Homology Concept)' and will further
develop his distinction between a historical and a causal
interpretation of homology.
641
Co-option and developmental pathways.
CARROLL, S.B.', R. GALANT, D. KEYS, D. LEWIS, C.
BRUNETTI, J. SELEGUE, V. KASSNER, and S. PADDOCK. Univ.
of Wisconsin, Madison.
One of the most challenging problems at the interface of
developmental and evolutionary biology is to explain the origin of
new structures and the evolution of new patterns. Butterfly wing
color patterns present a special opportunity to address these
processes at several levels. First, the individual units of wing
color patterns, the scales, are a Lepidopteran invention. Second,
wing pattern elements, such as eyespots, are organized by novel
mechanisms. And third, there is tremendous diversity in the
number, size, and color of pattern elements between and even
within butterfly species. Scale evolution and eyespot formation
both appear to be the products of co-option. Scales appear to
have arisen via the co-option of insect sensory structures and an
achaete-scute gene homolog to give rise to a novel cell lineage
and cytoarchitecture. Eyespots appear to have evolved through
a novel system involving the redeployment of components of the
global insect wing anteroposterior patterning pathway in each
subdivision of the developing butterfly wing.
Morphometrics in development and evolution.
ROTH, V.L. Duke Univ., Durham, NC.
Morphometric approaches facilitate the analysis of
quantitative variation in form, typically becoming most useful for
the study of organisms that have completed morphogenesis and
are at differing stages of growth. Recent conceptual and
technical refinements in the characterization and comparison of
forms have joined methodological innovations in molecular
biology, embryology, and phylogeny reconstruction to advance
the study of the evolution of development. Among the
phenomena that have recently been examined morphometrically
are developmental integration and heterochrony, discoveries that
in turn raise deeper questions about the connections among
disciplines and among levels of description: the relationship
between morphometric variables and characters, between
phenomenology and process, and the interplay (and evolutionary
relevance) of genes and phenotypes. Morphometrics can
continue to play a vital role in evolutionary studies of
development as its results generate questions both for its
practitioners and for other sorts of biologists to explore.
644
Intraspecific variation in developmental characters: The
origin of evolutionary novelties.
ARTHUR, W. Univ. of Sunderiand, United Kingdom.
Evolutionary developmental biology is inevitably a
comparative subject. However, the taxonomic level at which
comparisons can be made varies widely, and this greatly affects
the kind of information that can be gained from the comparison.
Broadly speaking, high-level comparisons (e.g. between phyla)
are more informative about phylogenetic pattern and homology,
while low-level comparisons (e.g. between congeneric species)
are more informative about evolutionary mechanisms, including
speciation. However, so far evolutionary developmental biology
has had a relatively minor input into the traditional territory of
population genetics, namely comparisons within species - both
within and between geographic populations. Yet this area is
crucial, as all evolutionary novelties ultimately arise from
intraspecific variation. Here, I address this issue by outlining the
main approaches, concepts and problems; and by discussing
two examples of developmental polymorphism within species
involving two of the main body axes: anteroposterior
segmentation in centipedes and left-right asymmetry (chirality) in
gastropods.
645
Evo/Devo: New experimental directions and a return to old
intellectual roots.
RAFF, R.A. Indiana Univ., Bloomington.
The sudden growth of evolutionary developmental bioiogy
has been driven largely by the findings of widespread regulatory
108A
640
643
genes operating in development in disparate taxa. Although this
realization grew from comparisons of a few model systems, new
molecular technologies, such as RNAi, now allow us to explore
evo/devo problems in a widely diverse set of organisms. The
sustaining interest in evo/devo continues to be driven by more
profound problems of developmental constraint, the meaning of
homology, etc. The field has at least three major problems to
address. The first is the mechanistic one of how development
evolves. The answers there will lie in understandings of gene
regulatory systems and their evolution. It will also require an
understanding of the very dimly perceived problem of the robust
ability of developing systems to coherently organize when
perturbed. The second major problem is how ontogeny itself
constrains the evolution. Finally, we are faced with the apparent
paradox of the origins of body plans and their enormous stability
through time. These are the old problems faced by our 19th
century predecessors, but we are able to cast them in new terms
and powerful genie approaches.
646
Where are we and where do we go from there? How do we
find out whether we actually know what we think we know?
WAGNER, G.P.*, C. CHIU, T. HANSEN, and M. LAUBICHLER.
Yale Univ., New Haven, CT and Princeton Univ., NJ.
Swimming in Opisthobranch Mollusks:
Contributions to Control of Motor
Behavior
Control of serotonergic actions within the Tritonia swim
circuit.
KATZ, P.S.*, D.J. FICKBOHM, and S. CLEMENS. Georgia State
University, Altanta.
Although the structure and composition of neuronal circuits
underlying swimming in different opisthobranchs varies with the
mode of swimming the importance of the neurotransmitter
serotonin (5-HT) is ubiquitous. We have investigated the role of
serotonergic neurons intrinsic to the central pattern generator
(CPG) for the escape swim response of the nudibranch Tritonia
diomedea. Members of the CPG the dorsal swim interneurons
(DSIs) use 5-HT for both classic neurotransmission and
neuromodulation. We found that the potency of single DSIs is
correlated with their level of 5-HT immunoreactivity and can be
altered though treatment with the 5-HT precursor 5hydroxytryptophan (5-HTP). Paradoxically 5-HTP treatment
results in a decrease in DSI spiking activity during swim motor
programs indicating that negative feedback may regulate 5-HT
output. We also found that the DSI neuromodulatory actions are
mediated via serotonergic G protein-coupled receptors. Blocking
these receptors in one neuron of the swim CPG is sufficient to
prevent the generation of the rhythmic motor program
suggesting that serotonergic modulation within the swim circuit
may be essential for its operation. Supported by NIH grant
NS35371.
649
Locomotory speed changes induced by serotonergic
neurons extrinsic to the pattern generator in the pteropod
mollusk Clione limacina.
SATTERLIE, R.A. Arizona State Univ., Tempe.
Three bilaterally symmetrical clusters of serotonergic neurons
influence locomotory speed changes in Clione. One cluster,
found in the pedal ganglia, enhance contractility of the wing
musculature, but do not alter activity of the central pattern
generator. Two clusters from the cerebral ganglia increase swim
cycle frequency by inducing four changes in pattern generator
interneurons. First, cerebral serotonergic inputs reconfigure the
pattern generator through recruitment of type 12 intemeurons,
which synaptically shorten the cycle period through early
inhibitory and excitatory inputs to the pattern generator. Second,
serotonergic inputs produce a tonic depolarization of pattern
generator interneurons. Third, postinhibitory rebound in pattern
generator interneurons is enhanced. Fourth, intemeuron action
potentials are narrowed to nearly half of their original duration.
The first three changes are directly related to the increase in
cycle frequency, while spike narrowing is merely permissive without narrowing, the observed frequency changes would not
be possible.
647
650
Serotonin increases calcium current in swim motoneurons of
Aplysia.
BLANKENSHIP, J.E.*, B. YU, G.N. GAMKRELIDZE, and P.J.
LAURIENTI. Univ. of Texas Medical Branch, Galveston.
Central pattern generator for swimming in Melibe.
THOMPSON, S.H. Stanford University, Stanford, CA.
Neuromuscular transmission in swim muscle of A. brasiliana
is facilitated by serotonin (5-HT), which causes a large increase
in ejp amplitude and muscle contractions. Part of 5-HT's action
could be to increase transmitter release from motoneurons (MNs)
by enhancing one or more calcium currents. To test this
hypothesis, we have examined the effects of 5-HT on MNs using
intracellular recording and voltage-clamp protocols in the
presence of various channel blockers. MNs express any or all of
three different calcium-current types (L, N, and P). 5-HT causes
a large increase in total calcium current in MNs. Present data
indicate that 5-HT is acting on a P-type calcium channel, since
100 nM omega-agatoxin, but not other calcium-channel
blockers, selectively blocks the 5-HT-induced increase in
calcium current. The 5-HT effect on calcium current is blocked
pharmacologically by 20 u cinanserin.
ABSTRACTS
The nudibranch mollusc Melibe leonina swims by bending
rhythmically from side-to-side. A model is proposed for the
neuronal central pattern generator that organizes this behavior
based on synaptic interactions between two pairs of
interneurons. The network is bilaterally symmetrical. Interneurons
on the same side of the brain act as synergists while
homologous intemeurons on opposite sides act as antagonists.
Synergists are coupled by rectifying electrical junctions while
antagonists are linked by mutual inhibition. Because of its
simplicity the Melibe network offers an opportunity to investigate
factors responsible for establishing the dynamic range and
stability of this multineuron mutually inhibitory network in a living
animal. Reciprocal inhibition is essential for oscillation. In
addition action potential bursts in antagonistic interneurons
alternate with constant latency and the circuit always operates at
maximal frequency. This suggests that a single rate-limiting step
in the inhibitory pathways such as synaptic latency or relaxation
time of summed inhibitory potentials is responsible for
determining both output frequency and stability. Supported by
the National Science Foundation.
109A
Developmental Evolution is a confluence of at least three
areas: progress in developmental genetics, maturation of the
comparative method and conceptualization of developmental
principles in evolutionary biology. These provide the agenda and
tools for investigating the role of development in evolution. We
argue that to give the field of Developmental Evolution a
workable paradigm, an important piece is missing. This is a
consensus on what criteria should be used in testing
hypotheses. How do we establish a causal link between
observed genetic differences and morphological change? How
can we determine if a proposed mechanism, e.g. the ShubinAlberch mode of limb development, has constrained patterns of
diversification? The most important agenda for the near future of
Developmental Evolution is to provide answers to such
questions. Here, we propose criteria that connect developmental
and phylogenetic data to study claims of causation in
developmental evolution. Further defining and utilizing these
criteria is critical for exploiting the technical opportunities
provided by developmental genetics and the comparative
method.
648
651
654
The neural basis of swimming in the nudibranch Melibe
leonina.
WATSON III, W.H.*, K.A. LAWRENCE, and J.M. NEWCOMB.
Univ. of New Hampshire and Center for Marine Biology, Durham.
Serotonergic neural system not only activates swimming but
also inhibits competing neural systems in a pteropod
mollusk.
NOREKIAN, T.P. Arizona State Univ., Tempe.
Melibe leonina swims by rhythmically flexing its body from
side to side at a frequency of 1 cycle every 2-4 seconds. This
fixed action pattern is expressed spontaneously and triggered by
contact with the predatory seastar Pycnopodia. Intracellular
recordings obtained from semi-intact swimming animals reveal a
population of approx. 20 swim motorneurons (SMNs) in each
pedal ganglion that drive the muscles that control swimming. In
general, SMNs from opposite pedal ganglia fire in anti-phase,
resulting in rhythmic lateral bending. Recordings from the same
SMNs in isolated brains yields similar results, indicating the
existence of a swim central pattern generator (CPG). Light or
cutting of the pedal-pedal connectives inhibits fictive swimming
in the isolated brain. There is no evidence for synaptic
interactions between SMNs, and either inhibiting or exciting
SMNs has no impact on the swim pattern. The SMNs are driven
by a CPG which appears to consist of 4 interneurons; 2 in the
cerebropleural ganglion and 1 in each pedal ganglion.
Appropriate activity in the swim interneurons is necessary for
swimming. This study was supported by an NIH grant to whw.
Initiation of a particular behavior requires not only activation
of the neural center directly involved in its control, but also
inhibition of the neural networks controlling competing
behaviors. In the pteropod mollusc C//one limacina, many
identified serotonergic neurons modulate or induce activities of
different elements of the swimming system resulting in the fast
swimming behavior. A pair of cerebral serotonergic neurons has
been also identified, which produced in addition to excitatory
inputs to the swimming system a prominent inhibition of pleural
neurons that control the whole-body withdrawal behavior. The
main characteristic of whole-body withdrawal behavior is
complete inhibition of swimming. By inhibiting pleural withdrawal
cells serotonergic neurons eliminated its inhibitory influence on
the swimming system and thus favored increased swimming
speed. Serotonergic neurons also produced a prominent
inhibition of the Pleural White Cell, which is involved in the
control of egg laying behavior. Thus serotonergic system in
addition to directly activating swimming system alters a variety
of other neural systems preventing simultaneous initiation of
incompatable behaviors.
Optical recording of the Tritonia swimming neural network.
BROWN, G. D.*, S. YAMADA, M. NAKASHIMA, T. J.
SEJNOWSKI, and S. SHIONO. The Salk Institute, La Jolla, CA,
and Mitsubishi Electric Corporation, Amagasaki, Japan.
A membrane-bound, voltage-sensitive dye was used to
image action potential activity in the isolated brain preparation of
Tritonia. Fictive swimming was activated with a brief electrical
stimulus applied to the cut end of a nerve. Many neurons
important for swimming fired bursts of action potentials on each
cycle of the fictive pattern. Recently, the process of sorting
optical signals into action potential trains from individual neurons
was automated using a new technique from statistical signal
processing called independent component analysis. We are
studying the number and distribution of known types of neurons
in the Tritonia swimming neural network and have identified
additional bursting neurons that have no known function.
653
Multifunctionality in neurons of the swim motor network of
Pleurobranchaea.
GILLETTE, R.* AND J. JING. Univ. of Illinois at Urbana and Mt.
Sinai School of Medicine.
The escape swim of Pleurobranchaea emerges from
interactions of neurons otherwise involved in different defensive
and appetitive behaviors, locomotion and the potential
coordination of general arousal. The known swim network
comprises the pattern-generating neurons A1, A3, A10 and IVS,
and the four serotonergic intrinsic neuromodulator As1 -4 cells.
The neurons A 1 , A3 and A10 also cause inhibition of the feeding
motor network during the swim. The four serotonergic As1-4
neurons drive the serotonergic neurons of the pedal ganglion to
initiate and sustain presumed locomotor activity. Asymmetric
activation of the bilateral As1-4 clusters may cause orienting
turns towards an appetitive stimulus. Avoidance turns are
themselves stereotypically rigid episodes driven by either of the
bilateral A4 neurons, whose sustained activity may be dependent
on a noxious stimulus to the oral veil plus As 1-4 spiking, like
As1-4's support of the swim episode. A4 neurons firing together
may also mediate head withdrawal from pain stimuli. Last, As1-4
monosynaptically drive the serotonergic neuromodulatory
neurons of the feeding motor network and depolarize other major
intemeurons, suggesting a contribution to feeding arousal.
110A
655
Circuit mechanisms mediating swim initiation in Tritonia.
FROST, W.N. The Chicago Medical School, North Chicago, IL.
The nudibranch mollusc Tritonia responds to aversive stimuli
with an escape swim response consisting of a series of
alternating ventral and dorsal whole-body flexions. One
interesting feature of this response is its high threshold — as
stimulus strength is incrementally increased, the animal at some
point abruptly switches from no swim to a swim response lasting
several cycles. What neural mechanisms underlie this striking
behavioral 'switch'? This presentation will first review our current
understanding of the Tritonia swim network. The hierarchical
organization of the intemeurons that activate the swim central
pattern generator will be described, as well as two recently
discovered inhibitory subcircuits that influence network
activation. Several network mechanisms will then be described
that are hypothesized to collaboratively underlie the swim's high
initiation threshold. Because swim initiation in Tritonia is strongly
influenced by learning, the mechanisms described here may also
identify network sites at which experience acts to influence
Tritonia's decision-making process. These findings will be
contrasted, when possible, with results from other species.
Supported by NS 36500
656
Costs and benefits of opisthobranch swimming:
Neurobehavioral mechanisms underlying risk reduction.
WILLOWS, A.O. D. Univ. of Washington, Friday Harbor, WA.
When opisthobranch molluscs are dislodged from the
substrate by the onset of swimming, the ensuing flexion or
undulatory motions are apparently not well oriented with respect
to predators, prey or suitable substrate. Swimming motions are
primarily effective in launching animals off the substrate and
elevating them into the water column where they may be
transported passively by ambient waves and tidal currents.
However, loss of contact with the substrate and launching into
the water column may also bring a high cost in terms of
exposure to diverse risks. I will illustrate examples of
opisthobranch swimming and indicate the triggering stimuli and
also evaluate costs and benefits. In addition, I will describe
adaptations of some opisthobranchs that may reduce the risks
of exposure to predators, strong water currents or to loss of
contact with food and mates. These include transparency or
inconspicuous color to reduce predation while swimming, and
neurobehavioral development of rheotactic and geomagnetic
sensitivity that may be useful to re-orient the animal after a bout
of swimming.
652
Topic in Ecological and Behavioral Studies
657
greatest fitness benefits to predators, possibly because
Increased nutritional benefits of feeding on prey with similar
nutritional requirements as the predator offset increased costs of
disease transmission between predators and genetically similar
victims.
660
The social experience of an animal is an important influence
on its social behavior and endocrine correlates. We investigated
the effects of different lengths of social experience on
aggression in Anolis carolinensis. Male anoles were randomly
assigned to one of the following four conditions: a single
exposure to the aggression or neutral video, daily exposure to
the aggression or neutral video for 5 days. After the experience,
anoles were presented with a conspecific male. Aggressive
displays(Dewlap extension, Push-up, and Lateral
compression(LC)), stress, and plasma androgen levels were
measured. We also tested anoles for individual recognition by
assigning them to either encounters with the same or different
conspecifics. Both a single and 5 aggressive encounters caused
enhanced aggression and its different components were
influenced differently with LC being consistent among groups.
Five encounters had little impact on stress or basal androgen
level. Anoles encountering the same conspecific showed more
aggression than controls until day 2, while anoles encountering
different stimulus males showed more aggression up to day 9.
Our results suggest social experience and its length modulate
aggression and that anoles show individual recognition.
Female spadefoot toads compromise on mate quality to
ensure conspecific matings.
PFENNIG, K.S. Univ. of North Carolina, Chapel Hill.
658
Male-male repelling function of male pheromone in the redspotted newt.
PARK.D. S.' and C. R. PROPPER. Northern Arizona Univ.,
Flagstaff.
Many species use chemical signals to find and court
potential mates. A male that is courting a female is faced with
the possibility that other males may be attracted by the activity.
If males produce pheromones that repel other males, some
fitness benefits of the original male may be conserved. In
vertebrates, such a phenomenon has not been reported. Using a
Y-maze selection paradigm, we tested the hypothesis that male
red-spotted newts, Notophthalmus viridescens, produce
repelling pheromones. We found 1) pheromones from three
males alone attract conspecific males, 2) pheromones from one
female are selected more frequently by males than those from
three males that are interacting with a female, and 3) males do
not show any preference for pheromones from a female alone
compared to a female exposed to males, but 4) they are more
attracted to pheromones from three males alone than to those
from three males exposed to a female. These results
demonstrate that pheromones released from males who are
interacting with females function to repel approaching males.
This is the first report of a male-male repelling function for a
pheromone in vertebrates. Supported by Council for Tobacco
Research Grant # 4661R1 to CRP.
When high-quality conspecifics resemble heterospecifics,
females may be unable to engage effectively in both species
recognition and mate-quality recognition. Consequently, females
engaging primarily in mate-quality recognition risk heterospecific
matings and females engaging primarily in species recognition
risk matings with low quality mates. I examined the evolutionary
consequences of this conflict between species and mate-quality
recognition in spadefoot toads. I compared mate preferences
and the fitness consequences of these preferences in spadefoot
toad populations that did and did not overlap with congeners. In
non-overlapping populations, females preferred an extreme call
character resembling that possessed by heterospecifics, and
they had more eggs fertilized. In overlapping populations,
females preferred those call characteristics that were closest to
the norm for their population, and they did not benefit from mate
choice. Thus, female spadefoots appear to trade-off species and
mate-quality recognition, such that those co-occurring with
heterospecifics forego benefits of high-quality matings to ensure
conspecific matings.
661
Genetic analysis of sequential clutches in the painted turtle,
Chrysemys picta: Sperm storage and remating behavior of
individual females.
PEARSE, D.E.*, F.J. JANZEN, AND J.C. AVISE. Univ. of Georgia,
Athens, and Univ. of Iowa, Ames.
Studies of genetic parentage in natural populations generally
are limited to single breeding season or reproductive episode
and, thus, represent only a snapshot of the mating behaviors of
individuals. Female turtles can store viable sperm in their
reproductive tracts for as long as several years, but the extent to
which this capacity is utilized in nature remained unknown. Here
we employ microsatellite markers to assess genetic paternity in
successive clutches of individually tagged female painted turtles
(Chrysemys picta) over a four year period. Hatchlings from
clutches, produced by more than 30 females, were scored at
microsatellite loci which provided a combined paternity exclusion
power of 0.927-0.981. The genetic data demonstrate that each
female generally used a single male's sperm to fertilize multiple
clutches within a year, that she usually remated each spring, and
that sperm that she has stored overwinter occasionally was used
to fertilize eggs the following year. The production by some
females of single-paternity clutches across more than one
season suggests that annual remating is not necessary for clutch
formation.
659
662
Effect of predator-prey genetic similarity on the fitness
consequences of predation.
PFENNIG, D. W. Univ. of North Carolina, Chapel Hill.
Frequency-dependent reproductive success and the
persistence of the gynogenetic Amazon molly.
DRIES, L.A. Univ. of Texas at Austin.
A largely neglected aspect of foraging theory is whether the
costs and benefits of predation vary with genetic similarity
between predator and prey. I hypothesized that prey of varying
genetic similarities might differ in value to predators, because
both the risk of pathogen transmission as well as the nutritional
quality of prey generally decline with decreasing genetic
similarity between predator and prey. I evaluated the above
hypothesis by feeding omnivorous spadefoot toad tadpoles
(Spea bombifrons, S. multiplicata, and Scaphiopus couchii) either
conspecific tadpoles or an equal mass of three different species
of heterospecific prey, all of which contained naturally-occurring
bacteria. I also examined which prey species Spea tadpoles
preferred to eat. I found that tadpoles performed best on, and
preferred to eat, prey of intermediate genetic similarity. In
general, prey of intermediate genetic similarity may provide the
One of the more puzzling evolutionary questions is how
clonal species persist through evolutionary time. Gynogenetic
species are clonal lineages that face an additional obstacle to
persistence because reproduction is dependent on sperm from
males of a sexual species. A gynogenetic species cannot persist
in isolation; it must coexist with a host species whose males it
can parasitize sexually. Simple population models that
incorporate behaviors such as mate discrimination predict that
gynogenetic species should rapidly become extinct. The
presence of gynogenetic species indicates these models are
insufficient descriptions of reality. One factor that would allow
the persistence of gynogenetic species is frequency-dependent
reproductive success. This empirical study documents the
presence of frequency-dependent reproductive success in a
gynogenetic, livebearing fish, the Amazon molly (Poecilia
ABSTRACTS
111A
Social experience and aggression in anolis lizards.
YANG, E.J.* AND W. WILCZYNSKI. The Univ. of Texas, Austin.
formosa). The ramifications of this type of reproductive success
on the long-term coexistence of gynogens and their sexual hosts
is discussed.
663
Morphometric differences in calling muscles of the gray
treefrogs, Hyla chrysoscelis and Hyla versicolor.
TITO, M.B.* and S.K. BOYD. Univ. of Notre Dame, IN.
664
666
The effect of testosterone manipulation on parasite
resistance in the house finch.
DUCKWORTH, R.A.*, M.T. MENDONCA and G. E. HILL. Auburn
Univ., AL.
The immunocompetence handicap hypothesis is based on
the assumption that physiological levels of testosterone
suppress the immune response of males. Although this
hypothesis has gained much attention among animal
behaviorists, the immunosuppressive effects of testosterone
have yet to be conclusively demonstrated in any passerine
species. Although recent studies have tested the effects of
testosterone on specific immune parameters, there are very few
studies that experimentally test the effects of hormone
manipulation on parasite resistance. Using testosterone
implants, I was able to test the immunosuppressive effects of
testosterone on males' ability to resist infection by coccidia
(Isospora sp.), a protozoan gut parasite. Infection rates were
monitored on weeks 2, 3, and 4 following inoculation. On the
third week of infection, the higher level of infection in males
implanted with testosterone (N=6) versus control groups (N=15)
approached significance (P=.O59). These results may indicate a
critical point in the infection by coccidia which is particularly
sensitive to hormone treatment.
667
Effects of juvenile and adult experience on song preferences
of female mountain white-crowned sparrows.
MACDOUGALL-SHACKLETON, E. A.', S. A. MACDOUGALLSHACKLETON, and T. P. HAHN. Princeton Univ., NJ.
Testosterone and prolactin concentrations in the
cooperatively breeding red-cockaded woodpecker {Picoides
borealis).
KHAN.M.Z.'.J.R. WALTERS, F.M.A. MCNABB, and P J . SHARP.
Virginia Tech, Blacksburg and Roslin Institute, Edinburgh, UK.
We tested whether early experience affects song preferences
in female white-crowned sparrows (Zonotrichia leucophrys
oriantha), and whether adult experience with song modifies these
preferences. We tested song preferences of 26 female sparrows
that had all heard a common song (natal dialect) during their first
year of life. During their yearling spring, birds were split into 4
groups and exposed either to natal dialect song, foreign dialect
song, heterospecific song (Cassin's finch, Carpodacus cassinii)
or silence. The next spring, we tested song preferences by
measuring copulation solicitation displays of birds in response to
song playback. Females performed more displays in response to
natal dialect song than to either foreign dialect song or
heterospecific song. This natal song preference was attenuated
in birds that had heard foreign dialect or heterospecific song
during their yearling spring; when analyzed separately, these
birds showed no natal song preference. These results indicate
that both juvenile and adult experience influence song
preferences in females of this species.
We measured testosterone CO and prolactin (PRL) plasma
concentrations in female breeders, male breeders and male
helpers in the cooperatively breeding Red-cockaded
Woodpecker during different stages of the reproductive cycle.
Male breeders and helper have low T during the non-breeding
stage, T peaks during copulation and declines during incubation
and nestling-feeding stages. Helpers appear physiologically
capable of reproducing; their T concentrations equal that of male
breeders. Helpers unrelated to the breeding female have higher T
than helpers related to her. Sexual inactivity by male helpers is
best explained by behavioral suppression. Female breeder, male
breeder and helper PRL was equal and increased from the
nonbreeding stage through the copulation and incubation
stages. During the nestling-feeding stage, male breeder and
helper PRL declined, while female PRL continued to increase.
Based on these results, we conclude that the physiological
bases of alloparental behavior have not diverged from those
affecting parental behavior in this species.
665
668
Sexual selection limits evolutionary innovation in birdsong.
NOWICKI, S.*, W.A. SEARCY, M. HUGHES, and J. PODOS.
Duke Univ., Durham, NC, Univ. of Miami, Coral Gables, FL,
Princeton Univ., NJ, and Univ. of Arizona, Tuscon.
The role of prey choice in the diets of juvenile cottid fishes.
COOK, A. East Carolina Univ., Greenville, NC.
Young swamp sparrows (Melospiza georgiana), when tutored
with songs having artificially increased trill rates, are unable to
produce the songs in their original form. Males copying such
songs introduce silent intervals into their songs, producing a
novel "broken" syntax. Broken syntax songs are accepted as
models in tutoring experiments, with the novel syntax sometimes
being learned and thus passed from one generation to the next.
We asked whether these novel broken syntax songs also are
accepted as functional signals by adults of the species. We
tested male response using territorial playback experiments and
female response using the copulation solicitation display assay.
Results show that territorial males respond equally strongly to
broken syntax songs as they do to normal songs. Adult females
aiso respond to broken songs, significantly more than to
heterospecific control songs; females show a preference for
normal songs over broken syntax songs : however. These results
112A
The diet of a predator is influenced by several factors
including prey availability, predator search behavior, mouth
gape, and prey vulnerability. Among the juveniles of three
species of cottid fish common in the rocky intertidal habitat, prey
choice appears to play a significant role in determining the
composition of the diet. In lab experiments, the juveniles of
Artedius harringtoni, Artedius lateralis, and Oligocottus
maculosus, were presented with equal numbers of two prey
types that dominate the diet in these fishes - gammarid
amphipods and harpacticoid copepods. Artedius lateralis
exhibited a preference for amphipods over copepods, O.
maculosus exhibited a preference for copepods, and A.
harringtoni showed no preference for one prey type over the
other. These results of the prey choice experiments match the
interspecific patterns of diet composition in these three species
in the rocky intertidal habitat of Washington state. The
correlation between changes in diet composition over ontogeny
in O. maculosus and changes in prey choice provide further
SOCiETY FOR INTEGRATIVE AND COMPARATIVE BIOLOGY
In the gray treefrog species pair, Hyla chrysoscelis is diploid
and H. versicolor is tetraploid. Because changes in ploidy can
directly alter the size of cells, we examined muscle cells to
determine whether changes in fiber size in calling muscles could
account for behavioral differences between the 2 species. In the
laryngeal dilator muscle, whole muscle cross-sectional area in H.
chrysoscelis was more than 5 times greater than in H. versicolor.
Area of individual FOG fibers was greater in H. versicolor
however. FG fiber area and ratio of fiber types were otherwise
identical in this muscle. In the laryngeal posterior constrictor
muscle, cross-sectional area was significantly greater in H.
versicolor and this species had a greater ratio of FOG fibers to
FG fibers. In the oblique muscle, there were no significant
differences. In a control muscle not involved in calling behavior,
H. versicolor had a significantly higher ratio of FG to FOG fibers
but fiber and muscle size was not different. Muscle cell size is
thus not universally altered by tetraploidy in this species pair.
Differences in muscle fiber morphometrics are likely a
consequence of differences in call rate. Supported by NSF
#IBN95-14305.
suggest that female preferences act as a conservative force,
limiting innovation in the evolution of song.
evidence that choice plays a significant role in structuring the
diet of these fishes.
669
Green sea urchins cover themselves in response to UV
radiation.
ADAMS, N.L. Univ. of Maine, Orono.
670
Variable reproductive behavior in Uca sp. - an argument for
lek behavior.
CROLL, G.A.* and J.B. MCCLINTOCK, Univ. of Alabama at
Birmingham.
The reproductive behavior of Uca has been extensively
studied, especially the connection between the dimorphically
enlarged male claw and reproductive success. Sometimes Uca
males appear to congregate in defined areas for the purpose of
attracting a mate. In avian and mammalian species these
congregations would be termed leks. The purpose of this study
was to examine the lek-like breeding assemblages that occur in
marsh habitats that lack vegetative cover. Three factors were
considered: reproductive behavior, substratum organic content
and population dynamics. Four North American marshes were
sampled: two on the Atlantic Coast, one on the Chesapeake Bay
and one on the Gulf Coast. Significant differences in time spent
in reproductive behavior were noted within habitats and across
biogeographic regions. Substratum organic content in open
areas was equal to or less than the organic content in covered
areas of the marshes (p>0.05). Male/female ratios and age/class
structure varied significantly between covered and open areas of
the sampled marshes. When compared to currently accepted
parameters, it appears that lek behavior is a part of the
reproductive repertoire in selected Uca sp..
671
The role of odor in status recognition and fight dynamics in
the crayfish Orconectes rvsticus.
ZULANDT SCHNEIDER, R.A.* and P.A. MOORE. Bowling Green
State Univ., OH.
Agonistic interactions are determinants of dominance
relationships for many animals. Communication of dominance
occurs in several species. The sensory mechanisms involved
may be a combination of chemical, visual, or mechanosensory
cues. This study is designed to examine the role of chemical
signals in fight dynamics and recognition of status in dyadic
interactions between crayfish. Behavioral characteristics of
fighting were compared between odor blocked and non-blocked
pairs of animals with no prior fight experience. To address the
role of odor in status recognition, fight dynamics were also
examined in odor blocked and non-blocked pairs that fought
each other previously and pairs derived from organisms with
past status history but no previous experience with one another.
Average duration and maximum intensity of fights, time to first
encounter, and number of interactions were quantified. Our
ABSTRACTS
672
The aesthetasc pathway is not necessary for many odoractivated behaviors of spiny lobsters.
STEULLET, P.', T. FLAVUS, G. HAMIDANI, V. NGO, D.
RADMAN, M. ZHOU, and C D . DERBY. Georgia State Univ.,
Atlanta.
Chemoreceptor neurons (CNs) in the antennules in
crustaceans innervate different sensillar types that vary in their
central projections. CNs in aesthetasc sensilla project to the
olfactory lobes, whereas CNs in non-aesthetasc sensilla project
to the lateral antennular neuropiles. The present study
investigates, through ablation of specific sensillar types, the
functional role of these 2 pathways in several odor-driven
behaviors of the spiny lobster Panulirus argus. Both aesthetasc
and non-aesthetasc CNs are involved in evoking behavioral
responses to odors in low-flow conditions, and the response
magnitude decreases as more CNs are removed. However,
under many experimental conditions, aesthetasc CNs are not
necessary for odor detection, initiation of search behavior, odorassociative learning, or discrimination among complex odor
mixtures, although aesthetasc-less lobsters have slightly more
difficulty in discriminating similar complex odors. We are
currently investigating the role of aesthetascs using more difficult
discrimination tasks and by examining orientation in defined flow
conditions in a flume. Supported by NIH grant DC00312.
673
Honeybees estimate feeder distances by the duration of
outward flights.
ESCH.H.E.' and X.GEE. Univ. of Notre Dame, IN.
Previous studies suggest that honeybees use the optical flow
they experience on the way to a feeder to estimate feeder
distance. We manipulated the optical input of foragers on the
way to a feeder and studied subsequent dancing behavior:
Individuals on the way to a feeder saw the environment on three
computer screens while they performed stationary flights in front
of a servo-mechanically-controlled wind tunnel. After these
flights they were transferred to a feeder at a distance of three
meters from the hive. They fed, returned to their hives and
performed waggle dances. Waggle duration increased with
increasing flight duration. Augmenting optical flow by increasing
the velocity of the environment going by during flight made the
foragers more willing to fly, but it did not affect the duration of
subsequent wagging runs. Optical flow affects distance
estimation in free flight probably only indirectly by increasing or
decreasing flight duration. The work was supported by the
Whitehall Foundation.
674
Climate change, whitebark pine, and grizzly bears in the
greater Yellowstone ecosystem.
KOTEEN, L.E. Environmental Defense Fund, New York, NY.
The subalpine species whitebark pine is dwindling. The
exotic fungus, White pine blister rust, is largely responsible for
the tree's decline. Transmission to the GYE has been slow, and
infection remains relatively low. To understand future blister rust
spread in the GYE, a study of the area's climate was conducted
through an examination of weather records. It was found that the
conditions for blister rust spread do occur with sufficient
regularity to produce whitebark pine decline. The seeds of the
whitebark pine tree are of primary importance as mast for
wildlife, particularly the grizzly bear. Climate change is predicted
to alter interactions between pathogens and host organisms. A
changing climate may allow pathogens to expand their domain
into new regions or to increase their impact in regions where
pathogens are only marginally present. To assess the impact of
climate change on blister rust spread to whitebark pine in the
GYE, a sensitivity analysis was performed in which climate
change scenarios were generated. Under the scenarios
examined, climate change is found to further endanger whitebark
113A
Many sea urchins, including Strongylocentmtus
droebachiensis, cover themselves in response to light, but the
spectral sensitivity of urchins to ultraviolet radiation (UVR) has
not been characterized adequately. In laboratory studies using
artificial irradiance, urchins sought shade and covered
themselves significantly more frequently when exposed to UVR
(290-400nm) and photosynthetically active radiation (PAR, 400700 nm) than urchins exposed only to PAR. In outdoor aquaria,
urchins were exposed to ambient solar UVR that was filtered to
create four treatments (dark, PAR only, PAR+UVA, or
PAR+UVA+UVB) and observed for six hours as total irradiance
changed with time of day. Sea urchins covered themselves with
significantly more material when exposed to PAR+UVA+UVB
than all other treatments, and in direct response to the time of
day or total irradiance. Urchins exposed to PAR+UVA responded
more significantly than urchins exposed to PAR only and urchins
held in the dark which did not show any significant covering,
regardless of time of day. These results indicate that urchins
seek shelter or cover themselves in response to UVR, primarily
UVB but also UVA wavelengths, possibly to avoid UV-induced
damage. [Supported by an EPA STAR fellowship]
results suggest that odor plays a role in agonistic interactions by
influencing the temporal aspects of fight dynamics.
Communication of behavioral state through odors appears to
play an important role in the agonistic interactions of crayfish.
pine in the GYE through increasing the frequency of the climatic
events which produce pine infection.
675
The effect of Hurricane George (1998) on a Melongena
corona population, Perdido Key, Gulf Islands National
Seashore, Florida.
WALKER, J. M.* and T.S. HOPKINS. Univ. of Alabama,
Tuscaloosa.
676
Biodiversity at deep-sea vent and intertidal mussel beds.
VAN DOVER, C.L.' College of William & Mary, Williamsburg, VA.
Common ecological descriptors of hydrothermal vent
communities, apart from species lists, have eluded vent
biologists for decades. Using replicate sampling, we examine
species richness, diversity, evenness, and composition within
mussel beds at the Lucky Strike vent field on the Mid-Atlantic
Ridge, and we compare these measures to those found at
intertidal mussel beds along the south-central Alaska coast. The
number of species found at the vent mussel beds is less than
half that of the intertidal mussel beds. Lower diversity of the vent
mussel beds reflects a reduced number of rare species found
there compared to intertidal mussel beds. Both vent and
intertidal mussel beds have uneven distributions, with a large
number of individuals found in a small number of species. Based
on comparisons of the Shannon diversity index, diversity at vent
mussel beds is low, but no lower than the diversity measured in
certain shallow-water environments. We hypothesize that
diversity within the Lucky Strike mussel beds, located on a slowspreading ridge where the spacing between vents is large,
represents the low extreme of diversity at hydrothermal vents.
We expect higher diversity at mussel beds on fast-spreading
ridges.
677
Positive interactions in the low rocky intertidal zone: The
importance of shade to community structure.
BURNAFORD, J.L Oregon State Univ., Corvallis.
In the low rocky intertidal zone of the Pacific Northwest, the
chiton Katharina tunicata is closely associated with the canopy
forming alga Hedophyllum sessile. Previous investigators
discovered that removal of the algal canopy caused a
precipitous drop in chiton abundances and significant changes in
the understory algal assemblage. I used field manipulations to
test if the canopy maintained high chiton abundances by
reducing predation by birds or by reducing heat stress. In the
spring and summer, K.tunicata abundances were significantly
higher under artificial shades than in bird exclosure plots. In the
fall and winter, chiton abundances did not differ between
treatments. All examined aspects of community structure were
equally affected by shade. Mobile invertebrate abundances were
significantly higher under artificial shades than in bird exclosure
114A
678
Measuring scales of physical stress in the rocky intertidal.
HELMUTH, B.S.* and M.W. DENNY Univ. of South Carolina,
Columbia, and Stanford Univ., Pacific Grove, CA.
Wave-generated forces and temperature-related stresses
potentially play crucial roles in driving the ecology of rocky
intertidal communities. However, relatively seldom have these
'physical factors' been measured at the scale of the organisms
that must contend with them. We quantified wave velocities and
maximum temperatures at a spatial resolution of 0.5 m over a
50m transect, and at a resolution of 2m over a 200m transect.
Results indicated that both maximum temperature and wave
forces varied consistently over very small spatial scales, and that
this variation was coherent with aspects of the substrate
topography. For example, organisms inhabiting vertical slopes
tended to experience higher wave forces than those on
horizontal surfaces, but were less susceptible to temperature
stresses. Maximum zonational heights of Mytilus californianus
were positively correlated with maximum wave forces, and
negatively correlated with maximum temperature stresses. This
study shows that wave exposure and thermal stress can change
over small scales, and must be explicitly quantified over these
scales before their effects on intertidal communities can be
convincingly demonstrated.
Morphology
679
Does the thick skin of the Florida manatee provide ballast?
NILL E.K.*, D.A. PABST, S.A. ROMMEL, and W.A.MCLELLAN.
Univ. of North Carolina-Wilmington, and FFWCC, FL.
Skin of the Florida manatee (Trichechus manatus latirostrus)
is nearly devoid of lipid and is 2.5 times thicker than would be
predicted for a mammal of its body mass. The thickness is due
to their dermis, which is reinforced by a dense, threedimensional weave of collagen fibers. The lipid-rich integument
of cetaceans provides a mechanism for positive buoyancy
because lipid is less dense than fresh and salt water. Contrarily,
manatee dermis is constructed primarily of relatively dense
collagen. Unlike the function proposed for the skins of other
aquatic mammals, we hypothesized that the dermis of the
manatee contributes to negative buoyancy, adding ballast. The
skin densities of manatees, bottlenose dolphins [Tursiops
truncatus) and harbor porpoises (Phocoena phocoena) were
determined volumetrically. Preliminary results show that the
mean density of manatee skin (1151 kg/m3) is greater than that
of bottlenose dolphins (979 kg/m3), harbor porpoises (978
kg/m3), fresh and salt water. Thus, it appears that the skin of the
manatee, along with its dense skeleton adds ballast to
counteract its buoyant lungs and voluminous intestinal tract.
680
Locomotor functions of dolphin blubber.
PABST, D.A.', W.A. MCLELLAN, and T.M. WILUAMS. Univ. of
North Carolina at Wilmington, and Univ. of California, Santa
Cruz.
Bottlenose dolphin (Tursiops truncatus) blubber is a resilient
biocomposite. Specialized blubber structures, caudal keels,
streamline the dolphin tailstock. We investigated keels using (1)
tensile tests of excised keels and (2) analyses of keel
deformation from videos of exercising dolphins. Keel mechanical
behavior and strain vary along the tailstock's length. Near the
dorsal fin, blubber undergoes large sinusoidal strains during
swimming. Maximum strain occurs in-phase with maximum
deflection of the tailstock, suggesting blubber is acting as a
In early September, 1998, we completed a 16 month mark
and recapture census study of a population (N = 266) of
Melongena corona on Perdido Key, FL. Data collection generally
described each individual that was numbered, and its use
established a size frequency distribution for the marked
population. In late September, 1998, Hurricane George caused
evident physical damage to the collection site, and extirpated the
population. Moribund remains of 250 individuals were recovered;
only 25 carried our unique markers. In the previous year's effort,
we did not record the variability of character states in shell
morphology (other than note the presence or absence of the
corollary whorl of spines that supposedly characterized
Melongena corona johnstonei. Post hurricane data from the
moribund remains left by the hurricane indicate a wide range of
variation in the appearance and nature of the corollary row and
other character states of the shell morphology. These
inconsistencies rule against previous hypotheses alluding to
"ecophenotypic variation." As of August, 1999, Melongena
corona has not been encountered in the vicinity of the study site.
We suggest that "allelic variation" introduced by previous
recovery from "natural disasters" may be an underlying cause of
the morphological variations in the shell structure at this location.
plots, and the understory algal assemblage was significantly
different in plots with and without shade. The provision of shade
and amelioration of heat stress by the algal canopy is a major
factor in determining community structure in this system. This is
a rare example of a positive interaction in a 'low stress' habitat.
spring, in-parallel with swimming muscles. At a position cranial
to the insertion of the flukes, the keel undergoes little strain, and
is three orders of magnitude stiffer than blubber near the fin. This
blubber appears to function as an anchor for the spring blubber.
At the fluke base, the blubber undergoes two
extensions/locomotor sequence, once near the maximum
ventral, and again at the maximum dorsal, deflection of the
tailstock. This blubber appears to absorb energy imparted onto
the tailstock by the flukes as they change their position
throughout the tailbeat. These results suggest that keel blubber
has regionally specialized functions during swimming. Supported
by ONR.
681
Shape differences in the trophic apparatus of two Lake
Malawi cichlid species and their hybrid progeny - a
landmark-based morphometric approach.
ALBERTSON, R . C and T.D. KOCHER. Univ. of New Hampshire,
Durham.
682
Function morphology of rodent incisors.
RYBCZYNSKI, N. Duke Univerisity, Durham, NC.
Although a salient feature of the rodent masticatory system is
the presence of ever-growing incisors, the diversity in incisor
form and function has largely been overlooked. The lower
incisors of adult rodents can be divided into 2 morphological
groups, those with flat and those with rounded anterior faces. I
present a model that outlines the difference in blade mechanics
(loaded axially) between the 2 morphologies and predict that
they will be correlated with specific behaviors. In particular,
rodents that dig with their teeth are expected to have relatively
wide, flat-faced incisors. In addition, whereas flat-faced incisors
should more often be wider, round-faced incisors should be
more readily optimized for point loading. In this preliminary
study, the incisors and cranial dimensions of 45 rodent species
were measured. Sixteen tooth-digging taxa, from 6 independent
clades, were chosen. Additional taxa were included to allow for
adequate outgroup representation and to encompass a diversity
of incisor-use behaviors . The predictions were supported by
phylogenetically informed, paired comparisons, and comparative
morphometric analyses. The results further suggest that incisor
width is constrained by procumbency and possibly body size.
These results will be useful for interpreting the evolution and
behavior of fossil taxa.
683
Seasonal variability in kidney morphology using different
histological processing methods.
CASOTTI, G. West Chester Univ., PA.
Seasonal variability in the kidney morphology of the house
sparrow Passer domesticus was examined using light
microscopy. Sparrows from the wild were captured in winter,
spring, summer and autumn. A total of 6 birds were captured
during each season. The kidneys were perfused with
glutaraldehyde fixative and processed for light microscopy.
Kidneys from each bird (left or right) were embedded in either
ABSTRACTS
684
Comparative morphology and histochemistry of lipidcontaining glands in the skin of treefrogs.
BARBEAU, T.R.* and H.B. LILLYWHITE. Univ. of Florida,
Gainesville.
Anuran skin is generally described as being highly permeable
to water and vulnerable to cutaneous evaporative water loss
(CWL). Several species of treefrogs, however, deviate from the
typical anuran pattern of unrestricted CWL. A few of these
species live arid environments, have a high skin resistance to
CWL, and secrete lipids from cutaneous glands to form an extraepidermal layer (Phyllomedusa spp). In this study, Florida
treefrogs (Hyla spp) that are moderately resistant to CWL were
shown to secrete lipids from cutaneous glands onto their skin.
Phospholipids were detected, histochemically, in secretions on
the skin of seven species examined, while phospholipids were
detected in granular glands of four species. Comparative
morphology and histochemistry of granular glands among Florida
treefrogs, a phyllomedusine treefrog, and an aquatic anuran
revealed no significant difference in the mean diameter (urn) of
granular glands among the species while only Florida treefrogs
exhibited lipids within the granular glands. The pattern of lipid
secretion from cutaneous glands onto the skin in Florida
treefrogs, having a moderate resistance to CWL compared to
phyllomedusine treefrogs, indicates that an extra-epidermal lipid
layer provides a range of protection from CWL, and that the
presence of this pattern may be more widespread among
treefrogs than previously known.
685
The physical basis of transparency in biological tissue.
JOHNSEN, S. Woods Hole Oceanographic Institution, MA.
Many animals are transparent, but little is known about how
transparency is attained. The effects of ultrastructure on tissue
transparency were modeled. Given a constant volume or surface
area of a high refractive index material within a low refractive
index matrix, the model calculates the amount of light scattered
as a function of how the material is subdivided and shaped.
Light scattering peaks strongly when a volume is divided into
particles with a critical radius that depends on refractive index.
Similarly, given a constant surface area, the scattering increases
rapidly with particle size until the critical radius is reached, after
which scattering is relatively constant. Under both constraints,
refractive index is critical when the particles are small, but
becomes less important as particle size increases. When only
side and back scattering are considered, the critical radius is
independent of refractive index, and scattering depends on
refractive index at all particle sizes. Under constant volume,
small particles of any shape scatter light equally, but large
spheres scatter less light than other large shapes. Under
constant surface area, small spheres scatter more light than any
small shape, but large particles of any shape scatter equally.
686
Structure of cubozoan Jellyfish eyes.
MARTIN.VJ.* and J.GIVENS. Appalachian State Univ., Boone,
NC.and Univ. of Notre Dame, IN.
The cubozoan jellyfish, Carybdea marsupialis, has four
rhopalia, one on each quadrant of the bell. Each rhopalium
contains one large eye, one small eye, and four ocelli. Both the
115A
Cichlid fishes have undergone an extraordinary adaptive
radiation in the lakes of East Africa. Key to this success has
been the diversification of their oral jaws, which allow them to
adopt specialized modes of feeding. Here we use landmarkbased morphometrics to quantify functional differences in the
trophic apparatus of two closely related cichlid species from
Lake Malawi, Labeotropheus fuelleborni and Methaclima zebra.
We conclude that L. fuellebomi and M. zebra lie at distinct ends
of the 'biting/suction' continuum. We use the same technique to
characterize the morphology of both F1 and F2 hybrids from a
cross between L fuelleborni and M. zebra. By examining the oral
morphology of hybrid animals we gain insight towards 1) the
genetic control of cichlid trophic morphology (i.e.
additive/dominant), 2) the number of genes responsible for the
morphological disparity between the two parental species, and 3)
the epigenetic processes at work during development. This
knowledge will contribute to our understanding of morphological
diversification and its role in this remarkable radiation.
paraffin wax or JB4 epoxy resin. To date, data are available only
for the winter and spring months. Kidneys from birds collected in
the winter contained on average 83% cortex, 7% medulla and
10% blood vessels and in the spring 81 % cortex, 8% medulla
and 11 % blood vessels. These data were not significantly
different. The percentage of nephron tubule components (i.e.,
glomeruli, proximal tubules, loops of Henle etc) were similar to
those of previous studies on other avian species and did not
vary significantly between seasons. Mean tissue shrinkage for
kidneys embedded in paraffin wax was 2 1 % and for JB4 resin
10.7%. The results of this study indicate that season may not
significantly effect kidney morphology and that processing tissue
with JB4 resin may be preferable due to a reduction in tissue
shrinkage. Supported by FDC 2112-001.
large and small eyes have a cornea, lens, and retina of cilitated
photoreceptors. Each photoreceptor contains a basally-located
nucleus, medially-located pigment granules, and a ciliated apex
filled with stacks of membrane. The base of each photoreceptor
projects into a neural plexus while the apical end extends into a
small space beneath the lens. Antisera that detect rhodopsin,
and the green, red, blue, or ultraviolet opsin proteins in zebrafish
were applied to the jellyfish eyes. Both the large and small eyes
exhibited positive staining for rhodopsin, blue opsin, green opsin,
and ultraviolet opsin. Rhodopsin, blue opsin, and green opsin
staining were observed in the apical stacks of photoreceptor
membranes, whereas UV opsin staining was observed in the mid
to basal regions of some of the photoreceptors. Jellyfish eyes
exposed to antibodies that recognize all photoreceptors, larval
and adult, of Drosophila showed no staining.
morphological differences are adaptations to water flow around
the blades (i.e., bumpy blades increase turbulence and therefore
enhance nutrient transport). To test if a particular morph offers
some advantage/disadvantage to individuals, reciprocal
transplants of each morphotype were made between high (or
rough) and low flow (or calm) environments in the field and their
growth rate and survivorship were followed over time. I found
that calm plants grew significantly faster than rough plants under
calm conditions. Growth rates were not significantly different in
the rough environment. Survivorship of both morphs was low
(<50%) in both calm and rough conditions, but was even lower
for rough plants in the calm environment (<20%). These data
suggest that bumpy blades confer a fitness advantage to kelps
in low flow environments and that water flow may be driving the
development of a new species. Supported by HHMI.
687
690
Visual motion detection and control of flight forces in
Manduca sexta.
FRYE, M. A.*, D.C. O'CARROLL, and T.L DANIEL. Univ. of
Washington, Seattle.
Ontogenetic scaling of limb bone strength in the green
treefrog (Hyla cinerea).
ESPINOZA, N.R. Univ. of Chicago, IL.
688
Peritrich ciliates with a fully formed spasmoneme in a poorly
contractile stalk: Functional paradox or developmental
adaptation?
CLAMP, J.C. North Carolina Central Univ., Durham.
Myoschiston duplicatum is a peritrich ciliate occurring as
branched colonies attached to gills of the crab Carcinus maenas.
The stalk of M. duplicatum has a spasmoneme running through
its interior but is poorly contractile in mature colonies. Colonies
of up to several zooids are fully contractile. Older, larger colonies
achieve nothing more than feeble, uncoordinated bending of
secondary stalk segments. Transmission electron microscopy
explains nothing about this lack of contractile function. It
probably derives, therefore, from molecular characteristics of the
stalk materials, either stalk matrix or spasmoneme fibrils. Why
has partial loss of contractile function in M. duplicatum
(presuming that it was more fully present in an ancestor) not led
to an equal loss of spasmoneme mass, as has apparently
happened in /nfransfy/um? Contractility still may be important to
survival of young colonies, hence retention of a normal
spasmoneme. Progressive loss of contractility as colonies
mature may conserve energy after they develop beyond the
point at which contractility is advantageous.
689
Does shape really matter? Comparing growth and
survivorship of flat and bumpy morphs in the kelp Eisenia
arborea.
ROBERSON, L. Stanford Univ., Pacific Grove, CA .
In California, Eisenia displays two widely different
morphologies that are correlated with local flow regimes: in high
flow areas, blades are narrow and flat; in low flow areas, blades
are wide and bumpy. Boundary layer theory suggests that these
116A
Previous measurements of jumping performance and limb
bone cross-sectional geometry in H. cinerea suggests that the
peak bending stress induced during jump take-off increases
nearly 2.5-fold over a 10-fold increase in body mass. The crosssectional geometries of the femur and tibio-fibula scale
isometrically relative to their lengths, suggesting that
morphological compensation does not contribute to the
maintenance of a constant limb bone safety factor through
ontogeny in these frogs. To test whether size-related increases in
limb bone stress might be mitigated through an ontogenetic
increase in bone strength, I measured the bending strength of
whole bones from the hind limbs of an ontogenetic series of H.
cinerea. Bending strength increases significantly (p = 0.02) by a
factor of 2.5 over a 10-fold range in body mass. Greater limb
bone strength in adult frogs suggests that limb bone safety
factor does not decrease as body size increases. Supported by
Howard Hughes Predoctoral Fellowship and NSF (IBN-9701121).
691
Developmental constraint of marsupial forelimb morphology.
COOPER, J. Florida State Univ., Tallahassee.
It has often been suggested that the evolution of forelimb
diversity among Marsupials has been developmental^
constrained. Marsupials are born at an early developmental
stage, but at that time must already have well-developed
forelimbs in order to climb to their mother's nipple. This
obligatory need for climbing forelimbs early in life may limit the
diversity of forelimb shapes that adult marsupials can develop.
Whether marsupials present a clear example of developmental
constraint has not yet been demonstrated. Is possible that the
apparent differences in forelimb morphologies between
Placentals and Marsupials may be due to factors other than a
developmental constraint, e.g. different rates of speciation,
different rates of extinction, differences in taxonomic diversity, or
chance alone. It is also possible, if unlikely, that the forelimb
differences between these groups are not as great as previously
supposed. It is the purpose of this project to determine if an
analysis of the forelimb morphologies of Placental and Marsupial
mammals supports the existence a developmental constraint of
marsupial forelimb evolution.
692
In vivo mechanics of the pigeon supracoracoideus and
pectorals during flight.
BIEWENER, A.A.*, B.W. TOBALSKE, R. HICKS, and D. STARKS.
Harvard Univ., Cambridge, MA.
Strain patterns at the supracoracoideus' (SC) tendinous
insertion on the dorsal humerus were used to quantify timevarying muscle force during flight. These were combined with
sonomicrometry recordings of fiber length to quantify the relative
timing of force, muscle work and power for the SC and
pectoralis (P) during the upstroke and downstroke. For all flight
conditions, SC and P forces overlapped at the end of each
stroke cycle when forces were low minimizing antagonist work.
Peak stresses developed by SC (80 to140 kPa) were twice those
SOCIETY FOR INTEGRATIVE AND COMPARATIVE BlOLOGY
Extracting motion cues from spatial and temporal
characteristics of the visual world is crucial for flight control in
insects. Bees, for example, can determine image velocity
independently of its spatio-temporal composition; flies, however
cannot. For the hawkmoth we asked if the spatio-temporal
composition of the image interferes with the animal's ability to
discriminate its velocity. Animals were tethered in an oncoming
windstream in front of a screen subtending 180°° at the eye.
During flight, a black and white horizontally striped pattern was
moved up and down on the screen. We measured lift and thrust
forces in response to manipulation of stripe-speed (temporal
frequency) and stripe-density (spatial frequency). We show that
flight forces are modulated in proportion to the time integral of
temporal frequency, but do not depend on absolute image
position. Peak responses occur at temporal frequencies near
10Hz and responses fall with decreasing spatial frequency.
These results match results from intracellular recordings made in
the brain and indicate that Manduca uses the spatio-temporal
composition of an image to calculate apparent image velocity.
(NSFIBN-9511681)
developed by P (40 to 60 kPa). SC peak force occurred 45%
through upstroke, whereas pectoralis peaked at 40% of
downstroke. Thus, elastic recovery of inertial work by the SC
tendon is small compared with muscle work to elevate the wing.
Both muscles contracted over a large range of length (SC: 35 to
54% and P: 26 to 47%). Whereas the SC mainly shortened
relative to rest length, the pectoralis mainly lengthened. SC
produced 1.6 W during level flight, 31 % of the power generated
by the pectoralis (5.1 W). Both muscles generated greater (2230%) power during ascending and less during descent (-61 % to
-65%). (NSF IBN-9723699)
693
Mechanics of rattlesnake tailshaker muscle.
MOON, B.R.* and K.E. CONLEY. Univ. of Washington Medical
Center, Seattle.
694
Twisting and bending: The role of hypaxial musculature
during locomotion in a salamander Ambystoma tigrinum.
BENNETT, W.O. Univ. of Massachusetts, Amherst.
696
Mechanics of fast contracting squid muscle: Mechanisms of
specialization.
KIER, W.M.* and N.A. CURTIN. Univ. of North Carolina at Chapel
Hill, and Imperial College of Medicine, London, United Kingdom.
Comparison of striated muscle from diverse animals reveals
a remarkable range of performance and specialization. In
contrast to work on vertebrate muscle, recent research shows
that specialization of the fast-contracting tentacle muscle of
squid occurred by dramatic changes in the arrangement and
dimensions of fiber components, rather than by changes in
chemical composition. To explore the physiological implications
of these changes, the mechanical performance of the crossstriated cells of the prey capture tentacles of Loligo pealei was
analyzed and compared with that of the obliquely striated cells
of the arms, which are the evolutionary and developmental
precursors. Length-tension, frequency response, and forcevelocity data have been obtained from fiber bundle preparations.
The unloaded shortening velocity of greater than 13 l/s (19 " C) of
the tentacle cells is an order of magnitude higher than that of the
arm cells. The tentacle cells also show dramatic changes in
excitation. The ratio of twitch force to tetanic force of the
tentacle fibers was measured to be approximately 0.65,
compared with 0.05 in the arm. Supported by NSF IBN972707 &
NATO CRG 971179.
697
Stabilizing properties of invertebrate skeletal muscle.
MEIJER, K.* and R.J. FULL. Univ. of California, Berkeley.
When salamanders locomote through aquatic and terrestrial
habitats, their pattern of axial muscle activity changes. Carrier
(1993) found that all four layers of lateral hypaxial musculature in
Dicamptodon ensatus fire synchronously during swimming, but
asynchronously during walking. This study concluded that
hypaxial muscles contribute primarily to lateral bending during
swimming, whereas they function primarily to counteract
torsional forces caused by diagonal limb support during walking.
This 'torsional hypothesis' has been controversial, and data from
walking lizards indicate that these muscles function primarily to
produce lateral bending. The goal of this work was to test
whether Carrier's findings from 0. ensafus hold for another
salamander, Ambystoma tigrinum . In agreement with Carrier's
results, all hypaxial muscles were found to fire synchronously
during swimming in A. tigrinum. Data from A. tigrinum also
support the torsional hypothesis: during walking, the external
obliques were active on the side towards which the trunk was
bending, while the internal oblique and transverse abdominus
were active on the opposite side. However, during some walking
trials, a biphasic muscle activity pattern that is correlated with
both lateral bending and torsion control was evident. This work
was supported by a Sigma Xi Grant in Aid to WOB.
Muscle can serve a role in stabilization to rapid
perturbations. Intrinsic muscle properties may result in a
stabilizing response acting before reflexes, hence termed a
preflex (Loeb and Brown, 1996). To investigate the stabilizing
properties of muscle, we measured mechanical impedance of
two leg muscles used by the cockroach, Blaberus discoidalis.
Experiments consisted of ramp stretches (0.5-4%; 0.1-5 lo/sec)
and sinusoidal length oscillations (5-150 Hz; 0.5% strain; muscle
length 90-130% lo) that were imposed on active as well as
relaxed muscles. The force response to perturbations in relaxed
muscle was a significant fraction (10-50%) of that observed in
active muscle. Impedance (delta force/ delta length) of relaxed
muscle doubled over the range of frequencies, whereas it
increased 5-fold with a 40% increase in muscle length. The
tangent of phase angle ranged from 0.2-0.6, indicating significant
damping. The contribution of leg muscles toward rejecting
perturbations could be substantial and in part due to passive
mechanisms. The relative importance of active and passive
preflexes to stability will require a multiple muscle model which
includes moment arms to yield apparent joint stiffness and
damping. ONR N00014-98-1 -0669.
695
698
Function of the oblique hypaxial muscles in trotting dogs.
FIFE, M. M.* and D. R. CARRIER. Univ. of Utah, Salt Lake City.
Muscles stimulated by the same motor neuron function
differently in running roaches.
AHN, A . N . ' and R.J. FULL Univ. of California, Berkeley.
When dogs trot the timing of activity in the obliquely oriented
hypaxial muscles is consistent with the functions of stabilization
against vertical accelerations that cause the trunk to bounce in
the sagittal plane and stabilization against horizontal
accelerations that tend to shear the trunk in the sagittal plane. To
test these hypotheses we compared the intensity of muscle
activity 1) when dogs carried weights (4 -10 % of body weight)
supported over the limb girdles versus supported mid-trunk
ABSTRACTS
Studies of neural control often infer muscle function from
electromyography (EMG) and kinematics. Muscles within the
same anatomical group innervated by the same motor neuron
are assumed to function similarly. We examined the in vivo
function of two leg muscles in the cockroach, Blaberus
discoidalis. Both muscles are innervated by the same, single
excitatory motor neuron and extend a single degree-of-freedom
117A
Rattlesnake tailshaker muscle is specialized for high speed,
low force contractions. Each muscle is a single motor unit,
whose temperature-dependent contractions range from 20-90
Hz over 10-35° C. As body temperature and rattling frequency
increase in western diamondback rattlesnakes {Crotalus atrox),
the mechanical work and twitch force of rattling increase,
whereas twitch duration decreases. Two factors may account for
the discrepancy between these results and the constant
metabolic cost per twitch reported previously: (1) Twitch force
and duration tradeoff to produce a constant force-time integral,
and hence constant cost per twitch. This appears to be the case
for mid-frequency twitches. (2) An energy saving mechanism
may allow increased mechanical work at some frequencies
without increased metabolic cost. The mechanism of energy
savings is currently under study. Therefore, in contrast to the
constant metabolic cost per twitch, shaker muscle mechanics
and energy savings are frequency-dependent. These unique
physiological and mechanical properties of rattlesnake shaker
muscle allow sustained high speed, low force contractions at
very low metabolic cost.
(sagittal bounce), and 2) when dogs trotted up versus down a
12o slope (sagittal shear). The loading experiment had a variable
effect on the intensity of muscle activity. In contrast, the hill
experiment produced dramatic results. Relative to level running,
muscles with a craniodorsal orientation (external layers) showed
an increase in activity when the dogs ran uphill and a decrease
when they ran down. Muscles with a cranioventral orientation
(internal layers) exhibited the opposite pattern; increased activity
when the dogs ran down and decreased activity when they ran
up. Thus, the obliquely oriented hypaxial muscles of dogs
appear to help stabilize the trunk in the sagittal plane against
cranial and caudal directed accelerations.
joint. After measuring EMGs and kinematics during running, we
used the in situ workloop technique to measure power output.
One muscle (179) absorbed energy (-19 WAg; 16% strain), while
the other muscle (178) first generated then absorbed energy to
result in no net power output (2 W/kg; 18% strain). Function can
depend on strain. Muscle 179 absorbed energy over a range of
strains (14-19%), whereas muscle 178 generated power at lower
strains (< 17%), but absorbed energy at higher strains (> 19%).
There was a range of strains (14-18%) within which these
muscles innervated by the same motor neuron always functioned
differently. Common stimulation pattern, strain amplitude,
anatomical position and even innervation can be insufficient to
predict muscle function in a locomoting animal. N00014-98-10669.
699
Patterns of activation and length change in the
dorsolongitudinal muscles of the hawkmoth Manduca sexta.
DANIEL, T.L.* and M.S.TU. Univ. of Washington, Seattle.
700
Work and power output of the dorsolongitudinal muscles of
the hawkmoth Manduca sexta.
TU, M.S.* and T.L. DANIEL. Univ. of Washington, Seattle.
To examine the consequences of coupling between
musculoskeletal mechanics, aerodynamics, and neural feedback,
we performed work loop measurements on mechanically isolated
dorsolongitudinal muscles (DL1s) from Manduca sexta. We
measured work and power output at physiological flight
temperature (36 C) and cycle frequency (25 Hz), while varying
mean muscle length, strain amplitude and stimulus phase. The
net positive work performed per cycle increased with increasing
strain amplitude up to the amplitudes measured in vivo. At in
vivo strain amplitudes, with the mean muscle length set at the
length that maximized isometric twitch force (Lmax), the
maximum power output of the DL1s ranged from 50-80 W/Kg.
The mean operating length (Lo) measured in vivo, however, was
approximately 10% shorter than Lmax, and at Lo, the maximum
power output was only 75% of the maximum power performed
at Lmax. Sub-maximal power output in vivo would suggest that
additional constraints, such as the wing motions required for
aerodynamic force production, may conflict with optimization at
the level of individual muscles for power output. (NSF grant IBN9511681)
Topic in Ecological and Behavioral Studies
701
Influence of pregnancy and lactation on locomotor
performance.
ROGOWITZ, G.L. Univ. of Puerto Rico, San Juan.
Pregnancy and lactation require substantial increases in food
intake and energy allocation and thus are considered potentially
118A
702
Effects of acorn size on caching and cache pilfery by gray
squirrels.
HADJ-CHIKH, L.Z. Princeton Univ., NJ.
Food hoarders such as gray squirrels (Sciurvs carolinensis)
play a primary role in the dispersal of many nut-bearing trees,
including oaks (Quercus spp.). I designed two experiments to
examine how interspecific differences in the size of acorns may
affect their dispersal by squirrels and their likelihood of escaping
predation once cached. In the first, individual free-ranging gray
squirrels were presented with a large Quercus rubra acorn and a
smaller Q. coccinea acorn. Squirrels took significantly more time
to cache Q. mbra acorns than Q. coccinea acorns, and cached
Q. rubra acorns significantly farther from their presentation sites.
To determine whether large acorn species also differ from
smaller species in their susceptibility to pilfery, thirty 5m x 5m
plots were established at various points on the Princeton
University campus. Each plot contained two Q. rubra acorns and
two smaller Q. palustris acorns, each buried at a plot comer. Q.
rubra caches were pilfered significantly more often than Q.
palustris caches. These results suggest that acorn size may have
important effects on acorn dispersal and survival.
703
Use of saguaro fruit by white-winged doves: Isotopic
evidence of a tight ecological association.
WOLF, B.O.* and C. MARTINEZ DEL RIO. Univ. of Arizona,
Tucson.
The saguaro, Carnegiea gigantea, is a defining feature of the
Sonoran Desert; during the summer it produces large quantities
of floral nectar and fruit pulp. Anecdotal observations indicate
that these resources are used by a wide variety of animals. We
quantified the use of saguaro resources by White-winged Doves,
<l Zenaidia asiatica /!>, using crop contents and stable isotope
analyses of dove tissues. Stable carbon isotope analyses of liver
tissue and crop contents data convincingly demonstrate that
doves forage intensely on saguaro fruit from the onset of its
availability until well beyond its period of peak abundance.
Saguaro fruit accounted for 73, 76, 54, and 10% of crop
contents during June, July, August and September, respectively.
Stable carbon isotope measurements indicated that saguaro
comprised 65, 92, 64, and 42% of the White-winged Dove's
incorporated carbon during the same months. Pollen loads
showed that doves collected during May and June visited
saguaro flowers. Interestingly, carbon isotope data did not
detect the use of nectar. Nectar use was suggested by changes
in the delta D of the dove's body water during this period and
also tracked saguaro fruit use.
704
Morphological and locomotor ontogeny in response to
predator cues by larval Hyla chrysoscelis.
ALLEN, C.E. Indiana Univ., Bloomington.
Antipredator strategies of larval anurans are often
characterized by an ability to respond to the chemical signals of
aquatic predators. Responses can include induced changes in
development that affect morphology and expression of
antipredator traits. Individual gray treefrog (Hyla chrysoscelis)
larvae were raised from hatching in the laboratory in either the
presence or absence of water conditioned by larvae of the gapelimited predator Ambystoma jeffersonianum to examine effects
on the ontogeny of morphological and locomotor traits. Filmed
responses to simulated predator attacks and digital images of
The dorsolongitudinal muscles (DL1s) are one of two
antagonistic muscle pairs that power the wingstroke in Manduca
sexta. Towards understanding the determinants of work output
by the DL1s, we measured muscle length changes during flight
in 6 tethered moths, specifically examining the operating length
of the DL1 s relative to the peak of their isometric length-tension
curve. We simultaneously recorded extracellular muscle
potentials to determine the timing of muscle excitation. The DL1s
fired once in each wingstroke just prior to the onset of muscle
shortening. The operational length of the DL1s, (Lo), defined as
the median muscle length during flight, was 89 ± 4% of the
length that maximized isometric twitch force (Lmax). The
trajectory of muscle strain was approximately sinusoidal with a
somewhat reduced shortening duration (45 ± 05 % cycle period).
The peak-to-peak amplitude of muscle strain was 9 ± 5 % of Lo.
Under isometric conditions, the peak isometric twitch force at Lo
was only 60% of the peak force at Lmax, suggesting that the
power output of the DL1 in vivo may be less than the maximum
possible power output of the muscle. (NSF grant IBN-9511681)
stressful periods for small mammals. I tested whether the
locomotor performance or aerobic capacity of the white-footed
mouse (Peromyscus leucopus) change owing to pregnancy or
lactation. This could have important ecological consequences
because any change in locomotor performance during
reproductive periods could affect predation risk. A longitudinal
study was conducted in which measures of locomotor ability,
exercise metabolism, and voluntary behavior were measured four
times for each individual from pre-pregnancy to post-lactation.
This talk highlights the individual variation seen in sprint speed,
wheel running, aerobic capacity, and open field behavior.
individuals recorded weekly through ontogeny were used to
analyze the effect of predator cue on body length, tail length, tail
muscle width, fin height, burst speed and maneuvering behavior.
Tail muscle width and fin height were significantly affected by
exposure to predator cue (fin height, p < 0.01; tail muscle width,
p < 0.01). These data were used to examine correlations
between age-specific effects of response to chemical cues and
ontogenetic changes in escape performance in light of varying
susceptibility to gape-limited predation through ontogeny.
indicates strong evolutionary pressure for chemical defenses
among antarctic opisthobranchs.
705
Three species of gammarid amphipods {Chromopleustes
lineatus, Ch. oculatus, and Cryptodius kelleri) form dense
aggregations in the nearshore subtidal (5-20m) off Bell Is,
Washington. Field and laboratory observations/collections
indicate that fishes that feed on other amphipods ignore these
aposematic species. Laboratory experiments have confirmed
that the amphipods possess chemical defenses and are typically
rejected by predators if ingested. We used several techniques to
assess their distribution and abundance, including collection of
whole laminarian blades, and photo and video quadrats.
Amphipod densities can exceed 12,000 ind/m 2 in an
aggregation. All three species show reciprocal inverse
abundance relationships; where one species is abundant, the
others are rare. These dense aggregations are similar to those
observed for those terrestrial insects that are also chemically
defended and aposematic. Mixed with these aggregations are
other palatable amphipods that may benefit from reduced
predation pressure either by simple association or by Batesian
mimicry of the defended species.
Performance and development in predator-induced and
activity-induced tadpoles.
BAILEY, C. L. Univ. of Utah, Salt Lake City.
706
Predator-prey interactions of first year toadfish Opsanus tau.
PRICE, N.N.* and A.F. MENSINGER. Connecticut College, New
London, and Univ. of Minnesota, Duluth.
The oyster toadfish, Opsanus tau, is an ambush predator that
inhabits estuaries of the Eastern Atlantic coast. The purpose of
this study was to compare the feeding behaviors of two different
size classes (3.5±0.3 vs. 5.9±0.7 cm, standard length) of first
year fish. The feeding trials using five prey (feeder guppies or
herring) were conducted in opaque tanks at 20±2 "C. All trials
were recorded with a Sony Camcorder and reviewed frame by
frame using a VCR (30 frames/second). Strike success, distance,
and location angle were determined. The mean successful strike
distance was significantly different for the two size classes
(0.67&0.plusmn;3 cm vs. 1.26±0.8 cm, P < 0.002, T test). The
smaller toadfish had a less expansive location angle than the
larger (52.5" to 142.5* vs. 7.5° to 172.5°). Larger toadfish were
much less successful (13.6% vs. 36.4%) at capturing similar
sized, but faster moving herring than the slower guppies.
Research was supported by the Lawrence Scholarship of
Connecticut College and NSF DBI-9605155 grant.
709
Gender, family, and diet effects on the aposematism of an
arctiid moth: Honest advertisement to predators and
conspecifics?
KELLEY, K . C and M. SWEENEY. Ohio Univ., Athens.
While predation and sexual selection can influence the
evolution of animal coloration, the genotype and nutritional
environment of individuals may affect the development of color
pattern. We experimentally examined gender, genetic, and diet
effects on adult coloration of Utetheisa ornatrix, whose larvae
sequester alkaloids from their host plants. We quantified wing
brightness, hue, and saturation of individuals raised on diets of
varying concentrations of seed powder and pure alkaloid. We
found females were brighter and more orange, while males had a
mix of fewer hues. Reaction norms showed genetic differences
in the development of coloration across diets. Adults raised as
larvae on intermediate amounts seed powder and alkaloid were
more orange, whereas those fed higher concentrations of
alkaloid had a greater mixture of hues. These diet effects
suggest coloration may reflect the amount of alkaloid
sequestered by larvae and honestly signal moth unpalatability.
Sexual dimorphism in color may signal gender to conspecifics
and play a role in mate choice. The genetic effects indicate
significant opportunity for selection on the signaling of
sequestered alkaloids.
707
710
Chemical ecology of antarctic opisthobranchs.
IKEN, K.', C. AVILA, A. FONTANA, and G. CIMINO. Univ. of
Alabama at Birmingham, Centre d'Estudis Avancats de Blanes,
Spain, and Istituto per la Chimica di Molecole di Interesse
Biologico, Naples, Italy.
Susceptibility of shrimp to Vibrio parahaemolyticus under
hypoxic conditions.
BURNETT, L', C. MIKULSKI, and K. BURNETT. Univ. of
Charleston, SC.
Chemical defenses in tropical and temperate opisthobranch
molluscs are well known. However, few studies have been
conducted on polar species. In the Weddell Sea, Antarctica,
Austrodoris kerguelenensis was found to possess defensive
metabolites (diterpenoid diacylglycerols) in the mantle with
feeding deterrence activity against the sympatric seastar
Odontaster validus. Bathydoris hodgsoni produces a sea star
feeding deterrent sesquiterpene called hodgsonal, while the
morphologically similar species, B. clavigera, lacks this
compound. The mantle tissue of the notaspid Bathyberthella
antarctica secretes a strong acid, which prevents predation,
whereas in the mantle of the cephalaspid Philine alata only weak
acid is produced. In summary, chemical defense strategies in
antarctic opistobranchs appear highly developed, which
ABSTRACTS
Hypoxia suppresses the production of reactive oxygen
intermediates (ROI) by phagocytes of invertebrates and
vertebrates; it is unclear that suppression of ROI production
under hypoxic conditions enhances susceptibility to infectious
disease. We have developed a challenge model to test the
importance of water pH, CO2, and 0 2 on disease susceptibility
in shrimp. Specific pathogen-free juvenile shrimp, Penaeus
vannamei (Waddell Mariculture Center, Bluffton, SC) and grass
shrimp, Palaemonetes pugio (collected from local tidal creeks in
Charleston) were acclimated to test conditions in the laboratory
and injected intramuscularly with an LD50 dose of a known
pathogenic strain of Vibrio parahaemolyticus. The shrimp were
challenged under two levels of hypoxia (6% 0 2 and 4% O2) and
elevated CO2 in filtered artificial 30 ppt seawater. Both species
held under 4% 02 (2% CO2 and pH of 6.8-6.9) displayed lower
119A
Predator-prey interactions induce an increase in tailfin size
and body mass in some larval frogs. This plasticity has been
suggested to be an adaptive response to the presence of
predators. Nevertheless, measurements of sprint performance
indicate that predator-induced tadpoles are not better
swimmers. Another possible cause of the plasticity could be an
indirect effect of tadpole inactivity (tadpoles reduce activity in the
presence of predators to prevent detection). To address the
effect of activity on tadpole performance and morphology,
pacific treefrog {Hyla regilla) tadpoles were raised in the lab with
and without dragonfly predators; half of these tadpoles were
placed on shakers which intermittently generated 3 hours of
swimming activity a day throughout ontogeny. Video analysis
(250 HZ) was used to examine tadpole sprint performance in
each treatment. Tadpoles raised in the presence of predators
were 15% more massive but did not have faster sprint velocities.
The shaker tadpoles metamorphosed later and at a smaller size,
but did not appear to have reduced sprint performance.
708
The distribution and abundance of three aposematic,
chemically defended gammarid amphipods off Bell Island,
WA.
NORTON, S.F.* and C D . STALLINGS. East Carolina Univ.,
Greenville, NC.
48hr survival (15.7% and 3.1%, respectively) than animals held in
well-aerated water (pH of 7.7) (28.7% and 29.4%, respectively).
Experiments are now underway to determine if the bactericidal
activity of shrimp hemocytes is equally susceptible to hypoxia.
(SC Sea Grant R/ER-14; EPA Agreement R-826399)
711
Folivorous specialization: Adaptations in the detoxification of
the dietary terpene, p-cymene, in Australian marsupial
folivores.
BOYLE, R*, S. MCLEAN, N. DAVIES, W. FOLEY, and B. MOORE.
Univ. of Tasmania, Tasmania and Australian National Univ.,
Australia.
712
Harvesting of symbiotic bacteria during colonization of the
light organ of Euprymna scolopes.
NYHOLM, S. V. Univ. of Hawaii, Manoa.
Among horizontally transmitted symbioses, mechanisms
must be present to facilitate initial contact of the partners. This
process of colonization was studied in the initiation of the
Euprymna scolopes/Vibrio fischeri association where conditions
can be experimentally manipulated. Within hours after exposure
to V. fischeri, which were expressing green fluorescent protein,
aggregations of bacteria were visualized by confocal microscopy
near the pores of the light organ. Fluorescently labeled lectins
revealed that the bacteria are embedded in a host-derived
mucus-like substance. After several more hours, bacteria within
the aggregates migrated into the crypts where full colonization
was established by 12 h. The aggregations also formed after
exposure to motility mutants of V. fischeri, nonsymbiotic vibrios
and heat-killed E coli. However, these non-specific bacteria did
not colonize the squid light organ. Fluorescently labeled latex
beads did not form aggregations and no mucus-like substance
was detected unless bacteria were also added. These data
suggest that symbiont aggregations are host derived, but
symbiont induced, and serve as a mechanism to ensure
colonization of the squid host.
713
Laboratory survivorship and reproduction of aposymbiotic
and symbiotic molgulids.
SAFFO, M.B.*, J. GLYNN, and K. MENARD. Arizona State Univ.,
Phoenix.
Nephromyces is an obligately symbiotic protist in molgulid
tunicates. In nature, all individuals of all molgulids contain
Nephromyces, suggesting that the symbiosis might also be
obligate or beneficial for the molgulid hosts. To test this
hypothesis, we raised Molgula manhattensis in the laboratory,
with and without symbionts, in 2 regimes: (a) 2-gallon tanks, with
seawater changed weekly and (b) 100-galIon tubs of recirculating
seawater. After 3 months, there was no difference in 1 st-
120A
714
Neotyphodium in Arizona fescue: A necessary symbiont?
SULLIVAN, T. J.* and S. H. FAETH. Arizona State Univ., Tempe.
Asexual fungi in the genus Neotyphodium form symbiotic
relationships with grasses in the Poaceae family. For agricultural
grasses, these interactions have been shown to be highly
mutualistic. However, our studies with a native species, Arizona
fescue, and its Neotyphodium sp. symbiont have not
demonstrated the same highly mutualistic relationship.
Additionally, it is not well known how the symbiosis is affected
by environmental and geographic variation. A reciprocal
transplant experiment using Arizona fescue was done to examine
differences in growth and reproduction between infected and
uninfected (both naturally and artificially via fungicide treatment),
from two geographically distinct populations. Environmental
differences played a large role in the growth of Arizona fescue,
affecting height, diameter, and seed head production. Infection
status also affected growth. Infected plants produced more seed
heads and a greater seed mass per seed head than artificially
uninfected plants. Infected plants did not perform better than
naturally uninfected plants, however, suggesting that naturally
uninfected plants may not be suffering a fitness disadvantage
due to their lack of an endophytic partner.
715
Endophytic fungi and host grass symbioses: Who's in
control?
HAMILTON, C.E.* and S. H. FAETH. Arizona State Univ., Tempe.
Endophytic fungi, especially asexual, vertically-transmitted
ones inhabiting Pooideae grasses, are thought to interact
mutualistically with their hosts mostly by increasing resistance to
herbivores. Asexual Neotyphodium in Arizona fescue, however,
does not increase resistance to vertebrate or invertebrate
herbivores. We tested the hypothesis that Neotyphodium in
Arizona fescue instead increases germination success. Contrary
to our prediction, the endophyte did not consistently increase
germination rate, success or growth rate. However, infected
genotypes always had greatly reduced variation in germination,
growth parameters and growth of pathogenic seed fungi. Our
results suggest that despite loss of sexual reproduction,
Neotyphodium may still control key germination and growth
parameters of its host plant. Alternatively, the endophyte-grass
symbiosis may be most evolutionary stable in plant genotypes
with low variability in growth parameters.
716
Endophytic fungi in native populations of grasses: Against
conventional wisdom of the anti-herbivore mutualism and
the plant diversity hypothesis.
FAETH, S.H.*. K. SAIKKONEN, M. HELANDER, T.J. SULLIVAN,
and J.L. RAMBO. Arizona State Univ., Tempe.
Endophytic fungi have been proposed as mutualists of their
host grasses, mainly by increasing resistance to herbivores. As
such, endophytes may also alter plant community diversity.
However, these anti-herbivore and biodiversity effects have been
documented mostly for non-native agricultural grasses,
herbivores, and plant communities. We examined the pattern of
asexual Neotyphodium infections in natural populations of
Arizona fescue under different intensities of vertebrate grazing.
We found no pattern of increased infection frequency with
increased grazing as predicted by the anti-herbivore hypothesis.
In experiments, the endophyte did not alter preference or
mortality of native and non-native invertebrate herbivores.
SOCIETY FOR INT&JRATIVE AND COMPARATIVE BIOLOGY
A fundamental issue in animal-plant interactions is the
detoxification of ingested plant secondary metabolites (PSMs).
We present data on the detoxification of a common Eucalyptus
spp. terpene, p-cymene, in four folivorous marsupials: a
generalist herbivore, (Trichosurus vulpecula, Brushtail Possum)
and specialist folivores, (Pseudocheirus peregrinus, RT), greater
glider (Petauroides volans, GG) and koala (Phascolarctos
cinereus, K). Animals (n=6) were dosed with single oral doses of
p-cymene (0.37 and/or 1.49 mmol/kg). Quantitative analysis of
urinary metabolites was carried out by extraction, gas
chromatography and mass spectrometry. A species-specific
pattern of metabolite excretion was evident and reflected the
natural occurence of eucalypt in the diet. The specialists only
excreted radically oxidized metabolites whereas BP
predominantly excreted moderately oxidized metabolites. The
advantage of highly oxidized, polar metabolites is to allow their
rapid renal elimination. Conjugation with glucuronic acid (GA),
which also increases renal elimination, was only significant in
BPs, with approximately 50 % of metabolites being conjugated.
The data suggest that dietary limitations of specialist folivores
favors the excretion of radically oxidised metabolites of pcymene, conserving glucuronic acid for the elimination of PSMs
which can not be so extensively oxidized.
generation survivorship in aposymbiotic and symbiotic M.
manhattenis. But after 5 months, symbiotic animals in large tubs
greatly outnumbered aposymbiotic animals. This difference was
due mostly to a 10-fold greater production of 2nd-generation
zooids by symbiotic animals. Small tanks showed similar general
patterns, but with smaller aposymbiotic/symbiotic differences.
Animals in large tubs resembled field animals more closely than
did animals in small tanks, suggesting that culture in large tubs
mimicked field conditions more closely than did small-tank
culture. Thus, comparative symbiotic/aposymbiotic outcomes
may be affected by environmental conditions.
Generally, plant genotype swamped the effects of the endophyte
on both herbivore and host performance. Finally, we found no
relationship between endophyte frequency and diversity of native
plant species. Our results suggest that the purported antiherbivore mutualism between endophytes and host grasses, and
the effects of endophytes on plant diverity, are not universal.
papillated marginally and fused posteriorly, but does not reflect
over the shell as in many Galeommatoidea. The gill demibranchs
are single, and retain brooded larvae for part of their
development. Other morphological details will be presented, and
status within the definitions of 'parasite' and 'commensal'
discussed.
717
720
Genotypic diversity among algal symbionts isolated from
Cassiopea xamachana.
WILCOX, T. P.*, J. HICKOK, and A. SLOAN. Univ. of Texas at
Austin and Univ. of Houston, TX.
Effects of a trematode parasite on feeding and reproduction
of the snail Elimia flava (Lea).
LENERTZ, K.*, J. FEMINELLA, and R. HENRY. Auburn Univ., A L
Snails in the genus Elimia (Gastropoda: Prosobranchia),
intermediary hosts for trematode parasites, have shown a
variable capacity to control stream periphyton. E. flava were
collected from Choctafaula Ck, AL, a population naturally
infected with a cotylomicrocercous trematode. Snails (n=34)
grazed for 10 d on tiles colonized by periphyton in laboratory
streams. Grazing and ammonia excretion were measured for
each snail, and snails were dissected to quantify parasites.
Infections ranged from 0 to >500 sporocysts/snail, with 40% of
the population infected. Non-parasitized snails consumed more
periphyton and excreted more ammonia than parasitized snails.
Effects of infection on fertility were determined by examining
gonadal development. Gonadal development and parasite load
were each ranked on a scale of 0 to high. Infected females
showed no developed ovaries, while males with light infections
showed slight development of testes. Castrated snails may
require less energetic input than reproductively active snails.
Because of this, infection by parasites may account for some of
the often-high variation in grazing observed by other researchers
within and among populations of this snail.
718
721
So many hosts, so little t i m e . . . Worm choice benefits for
Trichotropis cancellata (Gastropoda).
IYENGAR, E.V. Cornell Univ., Ithaca, NY.
Documentation of shell-burrowing polychaete and barnacle
predation on hermit crab eggs.
WILLIAMS, J.D. Univ. of Rhode Island, Kingston.
Although many parasites are host-specific, others can use
multi pie host species. Different host species can present varied
benefits (amount or type of food provided, predator protection,
habitat amelioration) that may influence a parasite,A(tm)s choice
of host. The snail Trichotropis cancellata is a facultative kl e
ptoparasite, able to suspension feed independently or steal food
from at least five species of tube-dwelling polychaete worms. T.
cancellata grows faster when parasitizing serpulid worms than
when suspension feeding. Laboratory observations sug g es t T.
cancellata prefers sabellids to serpulids. Growth rates in field
tethering experiments showed no significant difference in snail
growth rates on three species of worm hosts (sabellids and
serpulids), while field release experiments showed n o significant
difference on a fourth host (sabellarids). This is surprising
because these worm species vary greatly in size, feeding mode
(passive versus active suspension feeders) and feeding
efficiency. Perhaps all host species provide T. cancellata with
enough food for maximal growth rate and factors besides worm
feeding ability determine the snail,A(tm)s host preference.c
Certain polydorid worms (Polychaeta: Spionidae) and
trypetesid barnacles (Acrothoracica: Trypetesidae) are
commensal associates of hermit crabs. Two Polydora spp. and
one Trypetesa sp. from the Philippines were found to ingest the
eggs of hermit crabs in nature. Polydora sp. A and Trypetesa sp.
burrow along the columella and create openings in the middle
body whorls of gastropod shells, allowing access to the eggs of
gravid hermit crabs. The percentage of shells infested by
barnacles and worms was 9% and 20%, respectively. For
observation of feeding behavior and experiments, specimens of
Polydora sp. A were removed from shells and isolated in
capillary tubes. The worms engulfed hermit crab eggs and
removed them from pleopod hairs via breakage of attachment
stalks. During a 6 hr feeding period, a maximum of 70 eggs was
ingested by the worms. The findings indicate these commensals
may have a significant deleterious effect on the reproductive
potential of hermit crabs and the nature of such symbioses
should be further examined. Known and suspected egg
predators of hermit crabs will be discussed. Supported by
AMNH (Lerner-Gray Fund) and SICB (Libbie Hyman Memorial
Scholarship).
719
Anatomy and occurrence of Mysella pedroana (Bivalvia:
Galeommatoidea: Lasaeidae), branchial chamber 'parasite'
of the spiny sand crab Blepharipoda occidentalis (Anomura:
Albuneidae).
BOYKO, C.B.' and P.M. MIKKELSEN. American Museum of
Natural History, New York, NY.
Chemical settlement cues used by a rhizocephalan barnacle
infecting the blue crab.
BOONE, E., A. A. BOETTCHER, T.D. SHERMAN, and J.J.
O'BRIEN Univ. of South Alabama, Mobile.
Mysella pedroana inhabits branchial chambers of sand crabs,
B. occidentalis, found intertidally from San Francisco to Baja
California. Clams are primarily found in the anterior chamber,
byssally attached to the gills. Examination of 100+ crabs
revealed that 2/3 harbored 1-2 clams per chamber. Some crabs
were more affected, with up to 22 clams per chamber. Statistical
analysis indicated that clams show no preference for host size,
sex, or side (left or right). Fresh clams provided anatomical
information through gross dissection and histological sectioning.
Although the clam physically attaches to its host's gills, it is not
anatomically modified as a 'parasite.' The shell is chalky, with
concentric ridges and yellow-brown periostracum. The mantle is
The rhizocephalan barnacle, Loxothylacus texanus, is a
parasitic castrator of the blue crab in the Gulf of Mexico. Cypris
larvae settle upon post-molt (soft-shell) exoskeleton and
metamorphose into the dart-like kentrogon larval stage. After 6070 hours, the invasive vermigon larval stage leaves the
kentrogon to infect the host. Experimental manipulations of postmolt exoskeleton included treatments with proteinase K,
chloroform (to remove lipids), and sodium borohydride (to
remove carbohydrates). Removal of proteins did not affect
settlement relative to untreated controls. Enhanced settlement
was observed following lipid removal. Decreased settlement
occurred following removal of carbohydrates. These data are
ABSTRACTS
722
121A
Analyses of ribosomal RNA genes indicate that
dinoflagellates isolated from marine invertebrates belong to a
diverse and ancient group of algae. This phyletic diversity is also
manifest in both ultrastructural and functional variation, and a
number of studies are now finding evidence for ecological niche
partitioning among algal symbionts. However, there has been
little examination of symbiont genetic diversity within a single
taxon of algae harbored in any host species. In this study, we
have identified 12 polymorphic Randomly Amplified Polymorphic
DNA (RAPD) markers that can distinguish among both freshly
isolated and cultured dinoflagellates from the jellyfish Cassiopea
xamachana. Dinoflagellate symbionts were isolated from
Cassiopea specimens collected at 7 different localities along the
Florida Keys. DNA was extracted from both whole population
algae and cultured clones, and RAPD analyses were performed.
Preliminary results indicate that RAPD analysis can reliably
distinguish among algal genotypes, and that at least some C.
xamachana hosts contain more than a single genotype of
symbiont.
consistent with the hypothesis that the parasite larvae are using
carbohydrates to detect vulnerable hosts and that these moieties
are masked by lipids in the exoskeleton of the host.
Topic in Environmental Biology
its corresponding target mRNA. Verification of probe specificity
was performed by blot analysis. Probe specificity was also
analyzed by its hybridization to total RNA from tissue exposed to
another toxicant. Several true toxicant-induced cDNAs were
sequenced. These sequences were compared to genes of
known function by performing a blast search in databases.
Differential display PCR can be used to identify toxicant-induced
genes that can serve as molecular biomarkers for rapid toxicity
assessment in corals.
723
Larvae come home: A field test of a chemical morphogen on
two species of scleractinian corals.
PETRIE, CD.* AND S.A. HERBER Nova Southeastern Univ.
Oceanographic Center, Dania, FL.
726
Analysis of genetic variation in Guam populations of the
mass spawning coral Acropora surculosa using RAPDs.
ROMANO, S.L.', J.M. AGUON, and R.H. RICHMOND. Univ. of
Guam, Mangilao.
Studies of molecular genetic variation in scleractinian corals
have been hindered by technical difficulties in using molecular
techniques. In recent years RAPD markers have been used as a
means of relatively easily, rapidly, efficiently and inexpensively
assaying genetic variation, from the level of the individual to the
species, in a wide variety of plants and animals. We have
successfully used RAPDs for assessing genetic variation in
populations of one of the common mass spawning corals around
Guam, Acropora surculosa. DNA extracted from azooxanthellate
coral sperm was amplified with 6 different RAPD primers. These
primers generated more than 50 bands that are each considered
an independent genetic locus. Preliminary analyses demonstrate
that populations from different sides of the island separated by
50 km are genetically distinct. These RAPD markers are being
developed to test hypotheses about speciation within the
Scleractinia and as biomarkers for assessing environmental
stress in corals.
724
727
•
Quantifying sub-lethal effects of stress in corals: Can growth
and fecundity of corals be used to detect stress before
mortality?
MCKENNA, S. A.', R.H. RICHMOND, and G. ROOS. Univ. of
Guam, Mangilao.
Techniques to detect stress before mortality in corals are
needed to conserve coral reefs. In Guam, we are testing
techniques that use growth and fecundity to quantify sub-lethal
effects of stress in corals. The common Pan-Pacific coral,
Pocillopora damicornis has been chosen as our experimental
species for its ease of use and applicability. Two age classes
(one month and adult) of P.damicornis were transplanted to three
sites. One site is subject to direct effluent from a sewage outfall.
Environmental parameters are being monitored at each site. After
eight months, all corals were collected from the field and their
growth rates are being determined. Adult colonies of
P.damicornis were transplanted to these sites from a population
of corals from a reference site. After five months, all colonies
were collected and the number of planuale produced per adult
are being determined. ANOVA will be used to test for an effect of
site on survivorship, growth rate and planuale production.
Measureable difference among any of these quantifiable
characters may be used to detect stress prior to mortality.
725
Assessing coral stress responses at the level of gene
expression.
MORGAN, M.B.* and T.W. SNELL Georgia Institute of
Techology, Atlanta.
Researchers now have the ability to evaluate coral stress
gene response at the mRNA level providing an opportunity for
earlier diagnosis of a stressed condition. Differential display PCR
was used to identify genes that could serve as inducible
biomarkers of stress from exposure to copper, permethrin or
dibrom. Staghorn coral were exposed for 4 hrs to Cu2+ 25ug/L,
1ug permethrin/L, or .5ug dibrom/L Several differentially
expressed mRNAs produced in response to each toxicant have
been isolated. The differentially expressed genes were reversed
transcribed to produce cDNAs fragments that were subsequently
isolated, amplified, and developed into probes.
Chemiluminescent detection identified when a probe annealed to
122A
Use of intersimple sequence repeats in analyzing intra- and
interspecific variability in scleractinian corals.
SNELL.T.L' and M.A. COFFROTH. Univ. at Buffalo, New York.
Quantifying variation is essential in addressing ecological and
evolutionary issues ranging from population dynamics to
distinguishing cryptic species. Currently, within scleractinian
coral species, markers that readily detect variation are not
abundant and studies in the past have relied on allozyme
polymorphisms. Hypervariable DNA-based markers, such as
intersimple sequence repeats (ISSR), which are used primarily on
plant systems, may provide sufficient variability for populationlevel analyses in corals. Multiple ISSR loci are generated via the
polymerase chain reaction using a single primer consisting of a
di- or trinucleotide repeat and a two or three nucleotide
anchoring sequence. Variability in the nucleotide sequence
between priming sites results in polymorphic banding patterns,
which can be scored on agarose or acrylamide gels. Porites
astreoides and Fawa fragum have been screened using five ISSR
primers revealing intraspecific variation in banding profiles. In
addition, many loci appear to be species-specific in nature.
These variable markers will enable us to assess genetic variation
within coral species and potentially identify cryptic species.
728
A model for siting marine protected areas in coral reefs: A
synthesis of geology and biodiversity.
THOMAS, J.D. National Coral Reef Institute, Dania, FL.
While there continues to be mounting evidence for largescale change in coral reefs and associated reef communities on
local, regional, and global scales, scientists and managers
continue to view reefs through a narrow lens of coral and fish
only infrequently looking to other less charismatic groups of
marine invertebrates. Recently, Marine Protected Areas (MPA's)
have been championed as potential mechanisms to ensure
protection of coral reef biodiversity. While global networks of
such marine reserves are predicted to help ensure long-term
survival of coral reefs and associated habitats, current protection
efforts lack testable hypotheses to affirm the value of such
actions. In the absence of compelling biodiveristy data, the siting
of MPA's are strongly influenced by sociological and political
realities. Using a predictive geological frame of reference
Previous research has shown chemical inducers extracted
from certain species of red crustose coralline algae initiates the
settling and metamorphosis of many species of scleractinian
corals. This inducer is liberated from the algal cell through
mechanical hydrolysis and chromatographic purification. This
inducer molecule is attached to a stable inert substrate and
tested for inducing capabilities. We have attached an inducer
molecule from Hydrolithon boergesenii and field-tested its ability
on thre species of scleratinian corals, Porites astreoides,
P.porites, and Montastrea annularis during the 1998 and 1999spawning events in Ft. Lauderdale. The experimental results
suggests that the application of inducer technology under in situ
conditions is successful. We also discuss the application of
chemical morphogens to the future of artifical reefs, coral
mariculture ventures, and reef building efforts. Additionally,
observations during field trials coupled with settling data indicate
predation as a significant factor in larval substrate selection and
settling.
incorporating detailed biodiversity data the author proposes a
new approach for targeting MPA's. This approach, based on
identifying centers of evolutionary diversification, can be tested
in selected groups of marine invertebrates. This model would
emphasize a focus on reef areas where geological history and
selected biodiversity data indicate location(s)of reef systems and
events that may explain high levels of endemism or areas of
composite biodiversity not obvious from other methods.
exposure to anthracene did not alter mating success, but
reduced the proportion of E2-induced sex reversal in coexposed fish. Anthracene did not prevent the E2 effect in fish coexposed for 8 weeks. We conclude that anthracene disrupts
estrogen action, since anthracene-induced effects are prevented
by E2, while E2-induced effects are prevented by anthracene.
729
Comparison of reproductive steroids in yellow-blotched map
turtles, Graptemys flavimaculata, from a polluted versus a
reference site.
SHELBY, J.A.* and M.T. MENDONCA. Auburn Univ., A L
Sublethal effects of diazinon of the ovary of bluegill,Lepom/s
macrochirus: A histological study.
MAXWELL, L. B.* and H. M. DUTTA. Kent State Univ., OH.
Low reproductive rates and declining numbers in yellowblotched map turtles in the contaminated Pascagoula River
drainage in Mississippi led us to investigate the possibility of
endocrine disruption due to exposure to pollutants. Plasma
samples were collected from adult males and females over a
five-month period from a reference and a polluted site and
analyzed for testosterone (T) and 1713-estradiol (E2). T levels for
males differed significantly between the two sites. Mean T was
significantly higher in reference site males for three of the five
months. E2 did not differ significantly between sites (or males,
although there are several males from the polluted site with
exceptionally high E2 levels. However, females did not exhibit
significant differences in monthly mean levels of T or E2 between
the two sites. Females were also examined by ultrasound
imaging to determine ovarian development. Ultrasound data from
reference site indicated that 50% of females documented with
shelled eggs also had large pre-ovulatory follicles, in contrast to
only 18% documented for females from the polluted site.
730
733
The role of thyroid hormones in the transmission of
environmental cues used for downstream migration of
Atlantic salmon smolts.
ZYDLEWSKI, G. B,- and S.D. MCCORMICK. Conte Anadromous
Fish Research Center, Biological Resources Division, USGS,
Turners Falls, MA.
In utero and lactational exposure of spraque dawley rats to
2, 3, 7, 8 - tetrachlorodibenzo-P-dioxin and polychlorinated
dibenzo-P-furans: A histological analysis of the kidney.
RAPP, K.C.* and H. M. DUTTA Kent State Univ., OH.
The endocrine system is responsible for the transmission of
environmental cues to physiological response. The thyroid
system has been implicated in behavioral changes that occur
during the parr-smolt transformation of salmonids. The direct
relationship between circulating thyroid hormone levels and
downstream movements of individuals has not been explored.
We demonstrated that when Atlantic salmon smolts are not
provided an increase in daylength there is no expression of
downstream migration and when provided with a prolonged cold
spring the expression of downstream migration is extended.
There is a close relationship between extended migration and
physiological condition. Gill Na+,K+-ATPase activity and plasma
T4 levels remained elevated in cold late springs compared to
control groups. However, a dirct relationship between these
physiological parameters and the photoperiod control of
migration is not evident. Increases in thyroid hormone levels
early in spring are likely to be necessary for the transmission of
environmental cues for migration, but alone are not sufficient.
731
Developmental exposure to anthracene and estradiol alters
reproductive success in medaka (Oryzias latipes).
CHEEK, A.O.*, T. HOEXUM-BROUWER, S. CARROLL, M.
BROUWER, and J.A. MCLACHLAN. Southeastern Louisiana
Univ., Hammond, Univ. of Southern Mississippi, Ocean Springs,
and Tulane Univ., New Orleans, LA.
Polyaromatic hydrocarbons (PAHs) impair fish reproduction
and can antagonize estradiol action in vitro. To test whether PAH
exposure alters mating success by disrupting estrogen action,
we exposed medaka for 2 or 8 weeks post-hatch to 0, 12, and
20 ug/L anthracene ± 0.27 ug/L estradiol-176 (E2). At the end of
the exposure, fish were transferred to clean water, grown to
maturity, mated, and eggs were scored for % fertilization (mating
success). Eight week exposure to E2 produced 100% females,
while 2 week exposure resulted in more than 50% females.
Exposure to 20 ug/L anthracene for 8 weeks halved mating
success, but co-exposure to E2 prevented this effect. Two week
ABSTRACTS
Recently published studies on dioxins have determined a
correlation between exposure and carcinogenic effects
endocrine distrupters immune inhibition and alterations in
hormone levels. This study is a histological analysis of the effect
of dioxins on the kidney through in utero and lactational
exposure. There were two treatment groups one receiving 2378tetrachlorodibenzo-p-dioxin (TCDD) the other polychlorinated
dibenzo-p-furans (PCDF)- Within each treatment group there was
a high and low dose. For TCDD the low dose was a
concentration of 1 ug/kg body weight and the high dose was a
concentration of 2.5 ug/kg. For PCDF the low dose was a
concentration of 1 ug/kg body weight and the high dose was a
concentration of 10 ug/kg. The pregnant rats were given a single
dose of TCDD or PCDF by gavage on gestational day 15. After
birth tissue samples were collected on days 0510 and 20.
Histological changes were examined within the glomerulus
Bowman's capsule macula densa proximal and distal tubules
and peritubular capillaries.""
734
Assay development for measuring pollutant effects on T4
excretion in birds.
MCCLEARY, R.J.R.* and F.M.A. MCNABB. Virginia Tech,
Blacksburg.
We have validated and assessed assays for phase II
biotransformation enzymes that may be responsible for the
indirect effects of polychlorinated biphenyls (PCBs) on thyroid
function in birds. Uridine diphosphate glucuronosyltransferases
(UDP-GTs) catalyze thyroxine (TJ glucuronidation which leads to
T4 excretion. Some exogenous chemicals, including dioxins and
dioxin-like PCBs, increase liver UDP-GT activity and cause
hypothyroid conditions in mammals. Birds also exhibit altered
thyroid function in response to these chemicals, but UDP-GT
activity has not been evaluated. We have validated enzyme
assays for measuring overall UDP-GT activity (para-nitrophenol
substrate; pNP) and activity specific to T 4 (labelled T4 substrate).
Assay conditions have been defined to measure zero order
kinetics in quail liver. The pNP assay effectively measured a large
difference in liver enzyme UDP-GT activity between dioxin-
123A
The effects of Diazinon on the ovaries of bluegill [Lepomis
macrochirus) was studied. Histological preparations of bluegill
ovarian tissue was examined at 24 48 72 and 96 hours as well as
1 2 and 3 weeks following exposure to sublethal doses of
diazinon (60 Eg/I). After 24 hours of exposure to diazinon primary
follicles began to show adhesion. Cytoplasmic degeneration as
well as additional adhesion and some retraction were visible at
48 hours. 72 hours brought forth cytoplasmic expulsion adhesion
additional retraction and atretic oocytes. Cytoplasmic retraction
and clumping was more visible at 96 hours. Partial destruction of
the ovigerous lamellae and vitellogenic membrane presented
after one week. 2 weeks continued to reveal destruction of
follicles. Severe damage of the ovigerous lamellae extrusion of
karyoplasm and necrosis in the cytoplasm were most evident
following 3 weeks of exposure. Based on observations it
becomes conclusive that consistent sublethal doses of diazinon
can and will alter microscopic anatomy of the fish ovary.
732
treated and control mice. These assays will be used to evaluate
the role of UDP-GT in alterations in circulating thyroid hormones
in chicken embryos treated with PCBs and in wild-caught
Herring gulls from the Great Lakes.
735
The effects of organic and inorganic phosphates on
fertilization and early embryonic development of the
nearshore echinoid Lytechinus variegatus.
BOETTGER, S.A.* and J.B MCCLINTOCK. The Univ. of Alabama
at Birmingham.
Sea urchins were collected in April, 1999 from St. Joseph's
Bay in the northern Gulf of Mexico. Mature individuals were
induced to spawn using KCI, and gametes combined and
exposed to artificial seawater (control), or one of three increasing
concentrations of either organic or inorganic phosphate in
artificial seawater. Sub-samples of all treatments were taken at
times corresponding to discrete embryonic stages (up to the
prism stage) of embryos in the control treatment. Fertilization
success (%) was measured (presence of fertilization membrane)
and embryos were counted and divided into normal, arrested,
and abnormal development categories. Fertilization success was
significantly reduced in all phosphate treatments. After attaining
the 4-cell stage, embryos exposed to the highest inorganic and
organic phosphate concentrations displayed arrested
development. A concentration dose response of abnormal
development was observed with increasing phosphate
concentrations. These results indicate that even low level
exposure to phosphate pollution may impact the reproductive
potential of this echinoid.
736
Incidence of cyst forming amoebae in Bermuda inshore
waters relative to distance from point source sewage
effluent.
MUNSON, D. A. Washington College, Chestertown, MD.
In July 1999 sediment samples were collected at varying
distances (50, 100, 500 meters) from a sewage effluent dispersal
pipe located off of Hungry Bay on the south shore of Bermuda.
Samples were collected by bottom grab and were stored in
sterile whirl-pak bags. Upon return to the laboratory samples
were stored under refrigeration until they were cultured.
Triplicate cultures from each sample were incubated on nonnutrient agar with a bacterial overlay of E. coli. as a food source.
Cultures were incubated at room temperature and 40C. Several
species of Acanthamoeba were identified, among them being A.
polyphaga, A. hatchetti, and A. astronyxis. Small Umax amoebae,
probably representing both vahlkampfiids and hartmannellids
were also present in the samples.
124A
ADDENDUM-CONTRIBUTED POSTER PRESENTATIONS
137B
137A
Predatory, planktonic hydroids on Georges Bank:
Behavioral response to naipliarcope|xid prey
J. Austin*. A. Sefl, E Horgan, and L Mulin
•[email protected]
TheGlcibul Ocean Euisysun Dynamb; (GLC BBC) pnij.u
atutipls ti model iliepnpukiiim dyivunts iil'ti)>ut.srixix i n
Georges Bank, awakjbixly kixiwn kibeinipiiituitfiirlaivalaid
njeruilmenl Our study addiusses auTnrxiuit issue: OxiDiioliV;
amtribulionofarutiiSy-distiihukxl plmkkmiepiedakH; llx;
hytisni Qyii<i;iirili\: Qtntilyiigpiulakir-piuyijuei-jLUinsiuiy
aikiw for Ililua; piudiJk «id' Ix iw ft iputilk mdisuibutk m aixl
ariundancederuxliir«iiic)llx3bkiu.fxiiiiN. Spjeiluilly, we
gp
kL
137D
137C
ORIENTATION BEHAVIOR OF SEA TURTLE
HATCHLINGS: DISRUPTION BY MAGNETS
W. P. Irwin* and K. J. Lohmann
University of North Carolina at Chapel Hill
[email protected]
Laboratory experiments have revealed that
hatchling loggerhead sea turtles (Caretta caretta)
are able to establish and maintain courses using
the earth's magnetic field. The magnetic compass
may play an important role in guiding the offshore
migration. To determine if magnetic orientation
can be disrupted by distorting the magnetic field
around swimming turtles, we studied the
orientation behavior of hatchlings carrying
magnets or non-magnetic brass bars of equivalent
size and weight. Control turtles (with brass bars)
oriented significantly toward the east, whereas
turtles bearing magnets were not significantly
oriented as a group. The two distributions were
statistically different. These results confirm
previous findings indicating that loggerhead
turtles are able to detect and orient to the earth's
magnetic field. In addition, they indicate that,
under laboratory conditions, the magnetic
compass of sea turtles can be disrupted by
applying a strong magnet to the anterior carapace.
ABSTRACTS
Location and acquisition or food is an important
ecological decision that all organisms must face. Many
organisms localize food in their environment through the
use of sensory cues emitted from the food source. Studies
examining orientation to food in crustaceans have shown
that chemical cues play an important role. Specifically
adult lobsters and crayfish are able to locate food sources
using the spatial information in odor plumes. The purpose
of this study is to compare the orientation behavior of
adult and juvenile crayfish under controlled conditions.
We hypothesize that adult and juvenile crayfish orient to
an odor source in similar fashions because of similar
ecological pressures. Adult and juvenile Procambanis
clarkii were used in the study. Trials were run in flumes
using a liquid fish odor source and control trials were run
with distilled water. Trials were video taped from above
and digitized using a PEAK Motus Motion Analysis
System. X, Y spatial coordinates were used to calculate
crayfish walking speed, heading angle, turning angle, and
net to gross distance traveled. Both adults and juveniles
can successfully locate odor sources under these
conditions. These results showed that orientation behavior
for both adults and juveniles are controlled by odor
signals.
125A
niuouismuxruinuus ;ixl uixk.iimk Wiaviir.il dbscivjlkus
using sVHS VKAXI mv\ isuipy. Tlx: fading hydnmilis til" WULTsuspendxi u i k n b ; capliiiul naupltir pivyrangingIn mi IX) in
4S) mm in bigtli Piulukm n i t vuxxl as uik mi* wiili ;m a
mimhcror 12 lixxlbig liytlr.uillis ILxl uprni .sevvralsrixxN
p
p
p
p
l P dp
failing hydranlh per day was ex;iniixxl in lutilinn m leinroumu,
ki dilluuxus between rnvy xp-xxs, e. g. iL-wk mn vntil stijv. uiul
ki tlill'uuxus hjtwcui pnxtikir-spLvirL-dtD-.LVis siidi as iLuliny
hydiiuidinxuplnilogy. Pnxl;ili(Mii".lccl.\.n."is.xllx't\vi.vnLv.i1yUi
h C > i x ^ t x (I'/JKKV ;uxl PxcittliKtiiiiis nwmtiis iiiwplii.
iixiinsing piuy tinsity (25, %), atxl H > I [wy L"1),
piLxlilkin r.lc b u u r u l wiji ilnvu.s|X\.vs (ifuipjiUKl n;aiplii anil
A/kow/naiiptn. As wdL nnxkuim r.*.' bxn-.NAl ;il liiglxr
tiiipuunuui. Bduixkir.JdilKuixvsdiningpn.7C.^Unu;iHl
unsiunptitn by lwmlLsiim.1 lluling liydr.mlli ir»Hyilniliigj>; wou
observed As dxi.suinlod n¥H-|TIII>kiyy :LVA«ii|>;uiixtMmicbwHiil'
txiVmy stiv.ixm, ilx- iiiimir.s stif c il'siuit m nuiy bii|\u picy
COROLLA GEOMETRY AS A FLOWER
CHOICE CRITERION FOR HAWKMOTHS
V.Barc5, Dept. of Biological Sciences, Univ. of
South Carolina. crocofSbiol.sc.edu
Hawkmoths are known to use visual stimuli
during close-range orientation to flowers. I
investigated the importance of corolla geometry in
flower choice by 7 wild hawkmoth species in
eastern Romania. Arrays of nectarless, plastic
flower dummies were placed within a large field
of Nicoliana alata, in order to recruit wild moths
standardize olfactory and visual display from a
distance. Visits to each object were recorded
personally during 400 observer hours at three
field sites. Hawkmoth responses to twodimensional flower dummies were assayed in the
first part of the experiment. All species
discriminated against strongly zygomorphic
flowers, but were attracted to all actinomorphic
models, with a slight preference for flowers with
larger perimeters. However, there was no
significant difference in attraction to star-shaped
dummies (like Nicoliana flowers) over other
actinomorphic models. When three-dimensional
dummies were used, all hawkmoths discriminated
against convex or shallowly concave floral
geometries, but were equally attracted to pyramidal
or funnel shaped flower dummies. Unexpectedly,
Macroglossum stellatarum showed similar
visitation preferences to those of the 6 nocturnal
hawkmoth species observed in this study.
Many thanks to W. Drane, M. Niculae, R.Raguso,
and C. Strungaru for advice and support.
137E
126A
ARGININE VASOTOON AFFECTS
COURTSHIP AND AGGRESSION
K. Semsar* and J. Godwin
North-Carolina State University
[email protected]
Arginine vasotocin (AVT) enhances male
sexual behavior in many species. We tested
AVT's effects on alternative male tactics in
bluehead wrasses, Thalassoma bifaciatum, a
tropical reef fish. We gave AVT injections
to territorial and non-territorial terminal
phase males in the field. AVT increased
courtship independent of status, while its
effects on territoriality and aggression were
dependent upon male status. In territorial
males, AVT increased courtship and time
spent chasing other territorial males while
decreasing the number of chases towards
initial phase individuals. In non-territorial
males, AVT increased courtship, chases
towards initial phase individuals, and
territorial behavior, all behaviors rarely seen
in non-territorial males. This is the first
demonstration of AVT affecting teleost
behavior under natural conditions.
Division of Comparative Endocrinology
171B
171A
In euryhaline fishes, such asreddrum (Sciamops
occllatus), PRL isrequiredforadaptation to
changes i s salinity, but the effects of salmityinduced changes in PRL secretion on their
reproductive cycles are unknown, due to a Imck of
rsdioimmunoassays (RIAs) for PRL measurement
in these species. A homologous RIA for
measurement of red drum PRL (rdPRL) was
developed using antibodies raised against purified
rdPRL Antisera to the purified rdPRL were raised
by multiple injections in rabbits, and the specificity
and titer of the rdPRL antisera was verified by
immunocytocbemical staining of sagittal sections
ofreddrum pituitaries. The rdPRL RIA was
developed using the antisera at a dilution of
1:10,000 and PRL tracer, which was iodinatcd
using the Chloramine-T method. The RIA
demonstrated no cross-reactivity to other red drum
hormones, including somatolactin and growth
hormone. Parallelism was demonstrated with serial
dilutions of bom red drum plasma and pituitary
extracts. Plasma serial dilutions of a related
species, Atlantic croaker (Micropogoniai
undulatus), also diluted parallel in the rdPRL RIA.
Preliminary data indicate that the RIA is able to
detect PRL in plasmafromred drum kept at a
variety of salinities. PRL values rangedfrom0.5gng/ml plasma. In vitro validation using red drum
pituitaries in dopamine-treated media also showed
significantly less PRLreleaseas compared to
controls. The RIA will be used to assess the effects
of differing osmotic environments on PRL
secretion and the reproductive cycles of red drum
and Atlantic croaker.
SOCIAL SIGNALS INFLUENCE ANDROGENS
INDEPENDENTLY OF CALLING BEHAVIOR
IN THE TREEFROG.
S. Burmeister*. and W. Wilczynski. University of
Texas at Austin, [email protected]
Social signals play an important role in regulating
hormone-behavior relationships. In anurans, acoustic signals are an essential aspect of reproductive
behavior, however, the physiological consequences
of receiving social signals have remained undescribed. Acoustically isolated male Hyla cinerea
(n=72) were exposed to a mating chorus, an array
of tones, or no sound for 5,10, or 20 days. Individual behavior was recorded, and blood was collected
before and after treatment. Testosterone (F, ,,=12.0,
p<0.01) and dihydrotestosterone (F, ,,=9.9, j><0.01)
increased significantly as early as S days only in the
group receiving the chorus. Males receiving the
chorus also increased their stimulus-evoked calling
rate by day 2, and androgens correlated with calling. We compared androgen levels among males
that demonstrated similarly low levels of calling
behavior. Low-callers exposed to the chorus had
higher levels of androgens than low-callers in the
other groups (F 4 ^=2.9, p<0.05). Further, chorus
males with low, intermediate, and high rate of
calling had similar levels of androgens. These data
indicate that social signals increase circulating androgens independently of calling behavior. Supported by NIMH grant T32 MH18837 to SB and
R01 MH57066 to WW.
171C
ARGININE VASOTOC1N AND MALE
COURTSHIP BEHAVIOR IN WHITE
PERCH (MORONE AMERICANA)
S.J. Salek*, C.V. Sullivan and J.R. Godwin.
North Carolina State Univ., Raleigh.
[email protected]
Arginine vasotocin (AVT) and its
mammalian homologue, arginine vasopressin
(AVP), have widespread behavioral effects in
vertebrates. AVT was evaluated for its
effectiveness in stimulating a courtship
behavior termed 'attending' in male white
perch, Morone americana. We administered
AVT to males intraperitoneally (IP) or
intracerebroventricularly (ICV) with or
without Manning compound, an AVP V,,receptor antagonist, and then exposed them to
an ovulated female. AVT produced
significant increases in attending relative to
saline injected control animals. Manning
compound blocked this effect of AVT when
given ICV but not IP. AVT and Manning
compound were effective at lower doses
when administered ICV, suggesting that AVT
acts centrally to produce this behavioral
efiert
ABSTRACTS
127A
197A
197C
SEED DISPERSAL BY TWO AMAZONIAN
PRIMATES, WITH NOTES ON DUNG BEETLES
J.L. Dew, Dept of Anthropology, UC Davis
[email protected]
I compared the feeding ecologies of two
sympatric and closely related frugivores, the whitebellied spider monkey Ateles belzebuth and the
woolly monkey, Lagothrix lagotricha, both highquality dispersers of multiple plant taxa. Sixty one
percent of primate gut-passed seeds on the forest
floor were removed by secondary dispersers or
mammalian seed predators, usually (41%) within
three days of deposition. Removal rates varied with
seed size and plant species. Seed burial by dung
beetles was rare, but the cleaning and scattering of
seeds longer than 5mm by dung beetles may
significantly affect plant survivorship. Individual
seeds survived longer than clustered seeds, and
dung beetles in this Ecuadorean terra firme forest
effectively separated larger seeds from fecal
clumps. At study's end significantly more seeds
(34%) passed by L lagotricha remained alive
compared with A. belzebuth (22%), possibly due to
their smaller mean volume (756 mm3 versus 2303
mm3) and to differential attractiveness to predators.
At least two plant species appear to depend on A.
belzebuth exclusively among primates for
endozoochorous dispersal.
128A
GENETIC STRUCTURING OF RELICT
POPULATIONS OF THE RED-BACKED
VOLE, CLETHRJONOMYS GAPPER1.
C.R. COUCH*, J.M. WATERS2, J.F.
PAGELS1, AND B.L. BROWN1. *•' Va.
Commonwealth Univ. and 2Univ. of Otago,
Dunedin, N.Z. [email protected]
We evaluated genetic variation in
Clethrionomys gapperii at two microsatellite
DNA loci and related our results to the
biogeographic history of the southern
Appalachians. A total of 222 individuals were
sampled from nine sites, including two
populations suspected to have been isolated
since the Wisconsin glacial retreat. Genetic
structuring was evident among the majority of
the sampled populations. Overall gene flow
was indirectly estimated with three methods
and ranged from 1.13 to 4.44 migrants per
generation. The hypothesized isolation of two
island-like populations at Massanutten (MA)
and Peaks of Otter (PO) was supported by our
data and was most apparent in the MA
population where genetic diversity was low
compared to all other populations.
197B
197D
GENETIC VARIATION AND GENE FLOW
WITHIN AND BETWEEN THREE TIMBER
RATTLESNAKE (Crotalus horridus)
POPULATIONS FROM EASTERN NEW
YORK AND WESTERN MASSACHUSETTS.
S.E. Gerum*, M.Thomas, K. Sadighi, H.K.
Reinert, and L.M. Bushar. The College of New
Jersey, Ewing, Beaver College, Glenside, PA
The Nature Conservancy, Sheffield, MA,
[email protected]
The timber rattlesnake (Crotalus horridus) in
the northeastern United Stated has been
subjected to habitat degradation, population
fragmentation, and decreased population size
over the last 300 years. In an effort to gather
information necessary for future conservation
and management, a preliminary study was
undertaken on three populations of C. horridus
from eastern New York and western
Massachusetts where C. horridus is considered a
threatened or endangered species. Genetic
variation and gene flow were characterized using
five microsatellite loci for 22 timber rattlesnakes.
These estimates were compared to similar
estimates of genetic variation and gene flow
taken from a study of C. horridus found in
Pennsylvania. The results do not suggest levels
of reduced variation and may imply that the
populations have not been isolated for a long
enough time for inbreeding to have impacted
genetic variation.
SOCIETY FOR lNTEGRATIVE AND COMPARATIVE BlOLOGY
Antarctic fur seals are a sub-polar migratory
Otariid that are an increasingly dominant APEX
predator in the South Shetland Islands region. To
gain a greater understanding of the foraging
ecology and energetics of this important APEX
marine predator we measured the foraging
energetics, dive pattern, foraging location, and
diet of foraging females from the Cape Shirreff
rookery, in concert with ship based measurements
of the distribution and abundance of Antarctic
krill Euphasia superba. In January 1999 large
aggregations of krill were found immediately
offshore of Cape Shirreff. By February 1999 krill
moved well beyond the foraging range of lactating
fur seals. In January 1999 fur seals traveled farther
and fed mostly on krill. Foraging locations
correlated with krill distribution. In February 1999
fur seals foraged inshore. In February 1998 fur
seals had high field metabolic rates (FMR), but
spent relatively less time diving, but more time
surface swimming. In January 1999 fur seals fed
primarily on krill and spent more time diving and
had higher FMRs that were probably related to the
greater distance covered. In February 1999 fur
seals fed on fish, krill and squid, foraged closer to
Cape Shirreff and spent less of their time diving
and exhibited lower FMRs.
197F
197E
DIET, SOCIAL INTERACTION, AND GROWTH
IN HATCHLING TURTLES
K.W. Pecor, University of Memphis,
[email protected]
197H
197G
BEHAVIORAL EFFECTS OF THE TOXIC
DINOFLAGELLATE, ALEXANDRIUM ON
LARVAL MUMMICHOGS, FUNDUIUS
HETEROCUTUS.
J.C Samson, T.L Robertson*, and J.S.Weis, Rutgers
University, Newark, NJ
[email protected]
The toxic dinoflagellate, Alexandrium, which
produces saxitoxin, has been reported to cause fish
kills during bloom conditions. We are interested in
examining sublethal effects of Alexandrium, as might
occur during pre- and post-bloom conditions. Due to
the large size of larval mummichogs, Fundulus
heleroclitus, exposure to Alexandrium was achieved
using copepods as a vector. Newly-caught copepods
consumed Alexandrium overnight, and were then fed
to experimental fish larvae. After consuming -100
exposed copepods (controls were fed unexposed
copepods), larvae were tested for prey capture ability
and swimming performance. To examine possible
effects on the copepods as well as on the fish, we
observed prey capture rates of both unexposed and
exposed fish on both unexposed and exposed
copepods. Exposed larvae consistently showed
reduced swimming performance and prey capture
compared to controls, and in some trials exposed
copepods were captured more easily than unexposed
ones. Our observations suggest Alexandrium impacts
both fish and their prey, therefore facilitating transfer
of the toxin through the food web.
ABSTRACTS
The hatchlings of many North American
freshwater turtles exhibit delayed
emergence from the nest. Seasonal
temperature is likely an important cue
regulating this behavior which may vary
along a latitudinal gradient. Eggs of the
slider turtle Trachemys scripta from a
Southern Louisiana and West Tennessee
population were incubated in artificial
nests in the laboratory at a temperature
of 25'C. Hatchlings from these eggs were
either maintained at 25'C (control) or
subjected to a period of cold (4'C) for 20,
40, or 60 days after which the
temperature was gradually returned to
25'C. Emergence of Louisiana and
Tennessee hatchlings was not
significantly different. Control
hatchlings delayed emergence 23.3 +/10.9 days following hatching. The 20, 40
and 60 day cold period treatments had a
significant effect on hatchling
emergence. The longer the duration of
the cold treatment, the sooner the
hatchlings emerged after the treatment
was suspended . This study indicates that
the duration of cold temperature may be
an important cue in synchronizing the
emergence of hatchling T. scripta in
natural nests.
129A
Many emydid species, such as Trachemys scripta,
undergo an ontogenetic shift from camivory in
juveniles to herbivory in adults. Chelydrid species,
such as Chelydra serpentina, ait carnivorous
throughout life. The sensitivity of growth rate to
increased levels of dietary protein may be
influenced by the difference in lifetime protein
intake between these two foraging ecologies.
Hatchling T. scripta and C. serpentina were raised
for twelve weeks on diets of various protein
concentrations to determine the optimal level for
growth in each species. Housing in T. scripta was
also manipulated to determine the effect of social
interaction on growth rate. At week ten, the diets
tested had a significant effect on growth in C.
serpentina. Neither diet nor social interaction had a
significant effect on growth rate in T. scripta. C.
serpentina growth was sensitive to increases in
dietary protein above the optimal level for T.
scripta. The preliminary results suggest that the
life-long carnivore has the physiological capacity to
assimilate higher levels of dietary protein than the
animal with an ontogenetic shift from camivory to
herbivory.
Bleaching, the loss of symbiotic dinoflagellates
(zooxanlhellae) from reef corals and other cnidarians, may
be a stress response of the host, algae or both. To
determine the role of zooxanthellae in the bleaching
process, aposymbiotic sea anemones from Bermuda
(Aiptasia pallida) were infected with symbioms from other
sea anemones (Aiptasia pallida from Florida, Bartholomea
annulata. Condvlactis gigantea). The expulsion of algae
from these heterologous infections and from symbiotic
Bermuda A, pallida was measured during 24-hour
incubations at 25,32 and 34°C. Photosynthetic rates of
freshly isolated zooxanthellae were also measured at these
temperatures. The Q. gigantea (Cg) symbionts were
expelled in higher numbers than the otlier strains at 32°
and photosynthesis by the Cg algae was completely
inhibited at this temperature. In contrast, the other strains
continued to photosynthesize at this temperature, although
at lower rates than at 23°. These results suggest that
zooxanthellae, rather than the host, are directly affected by
elevated temperatures during bleaching events. The
differential tolerance of zooxanthellae to stress could
partly explain variable patterns of coral bleaching, as
others have proposed.
1971
PHYLOGEOGRAPHY OF AMBYSTOMA
MACRODACTYLUM: NORTHERN, ISOLATED & RANGE
MARGINAL POPULATIONS.
M.D. Ihompsoti* and A.P. Russell. University of Calgary •
2500 University Dr. NW. Alberta. T2N 1N4. mduiompsrifucalgaiy.ca.
130A
The topographical diversity of the Canadian Rockies has
likely influenced multiple concordant avenues of
colonization. Historical biogeographic investigation of the
long-toed salamander, Ambystoma macrodactylum, in this
region has revealed interesting prospects for phylogeographic
analysis. The geographic setting heuristically elicits
hypotheses regarding the spread and distribution of
haplotypes from core ancestral regions. In British Columbia,
this taxon is distributed continuously along its latitudinal
range, but in Alberta A. macmdactylwn breeding pond
localities cluster into nine disjunct regions contiguous with
valleys and low elevation regions of the Rockies. These
clusters suggest that low elevation passes facilitated
colonization of Alberta from BC subsequent to the retreat of
Pleistocene glaciers. To trace the genealogical pathways of
these clustered populations we have employed the sequencing
of a rapidly evolving mitochondrial intergenic spacer unique
to the Ambystomatidae.
Thus far, strong haplotype
associations are observed in longitudinally adjacent northern
populations, but such close relationships have not been
demonstrated for latitudinal proximity. A geographic
information system (GIS) approach, using 30m2 DEM
resolution, is proving valuable as a spatial and genetic
analytical tool, permitting explicit tests of geographic-togenetic associative hypotheses. Employment of GIS can
provide pictorial representations of phylogeographic data and
will be used to make inference assessments of the visual data
using explicit programming criteria.
Division of Integrative & Comparative Issues
202A
ABSTRACTS
Recent studies report a migration from sciences
to the nonscience majors, including very talented
students. Moreover, students entering college in
the sciences are increasingly ill-prepared to
handle conceptual information and to critically
assess biological questions. An analysis of
traditional exam questions used in Biology
revealed that, 74% were fact-based, 14% semiconceptual, and only 12%, conceptual. We, as
instructors, were not providing students with the
proper training to handle conceptual information.
The traditional laboratory setting was used to
implement a conceptual focus by providing the
students the opportunity to collaborate and think
critically. We set up students in small groups,
called "seminar teams", and provided them with a
"thought question". They would discuss, debate,
write a reasoned response and then submit it to
their instructor via an online classroom setting.
Following feedback, students had the opportunity
to revise. Performance improved significantly
following the implementation of this approach.
We chose to implement this new pedagogy using
new interactive and multimedia technologies.
Supported in part by a grant from the U.S. Dept.
of Education.
131A
Division of Invertebrate Zoology
239B
239A
NUDIBRANCH LARVAL SHELLS:
DIFFERENT DEVELOPMENTAL PATHWAYS
HAVE THE SAME STRUCTURAL RESULT
L.R. Page, Dept. of Biology, University of
Victoria, B.C., Canada [email protected]
Most nudibranch larvae have a coiled larval
shell, similar to that of other opisthobranch larvae.
However, some nudibranchs have a non-coiled and
greatly expanded larval shell ('inflated'). Coiled
larval shells enlarge considerably during the larval
stage to provide space for growth of visceral
organs. Inflated larval shells have a huge interior
space from the time of hatching; growth of larval
viscera is accommodated without the need for shell
growth. Why is the inflated larval shell found only
among nudibranchs? I found that nudibranchs with
coiled larval shells remove overgrown shell walls
by dissolution after the shell has achieved full size.
Therefore, regardless of whether shells of young
nudibranch larvae are coiled or inflated, both types
are hollow cups at metamorphic competence.
Internal dissolution of the larval shell does not
occur in non-nudibranch opisthobranchs and the
pedal retractor muscle migrates along overgrown
shell to reach the columella of the juvenile shell.
This constraint is absent in nudibranchs, because
the post-metamorphic stage has neither shell nor
shell-attached pedal muscles. Lack of internal shell
partitions in larval nudibranchs permits uncoiling
of the digestive diverticulum prior to settlement
and metamorphic shell loss, thereby anticipating a
derived, post-metamorphic trait.
239C
MULfcCULAK AWKOACHllS 1O THH STUDY Oh
MICROBES FOUND IN ASSOCIATION WITH
BERMUDA'S MARINE INVERTEBRATES.
J. Ritter.* and H. Trapido-Rosenthal
Bermuda Biological Station for Research, Inc.
[email protected]
Microbes are an important part of the marine ecosystem. Although many of these microbes are
associated in some way with a variety of marine
invertebrates, little is known about the microbial
diversity in these relationships. Underlying this lack
of knowledge has been the difficulty of culturing
marine microbes. With the recent advent of
molecular techniques that permit the taxonomic
classification of microbes without culturing them,
we can anticipate a dramatic increase in our understanding of microbial diversity. We have applied
techniques of molecular taxonomy to both uncultured and cultured examples of marine microbes
that are found in association with sponges, a pelagic
tunicate, an intertidal oligochaete and raw seawater.
Our results suggest that the application of appropriate techniques to both types of microbial samples
has the potential to provide us with a more accurate
representation of the diversity of marine microbial
communities. Such a representation should advance
our understanding of the ecology and evolution of
microbial-invertebrate associations.
132A
239D
EXTRACELLULAR STRUCTURES SURROUNDING
ECIirNOID EGGS MITIGATE THE TRANSMISSION OF
COMPRESSIVE FORCES TO EGGS
•T, Bolton and F.I.M. Thomas
University of South Florida, Tampa.
Eggs of echinoids are surrounded by complex
extracellular layers composed of a network of fucose sulfate
fibers imbedded in a glycoprotein matrix. The composite
structure of these structures is reminiscent of engineered
structures designed to withstand physical stresses. The eggs of
echinoids are freely spawned into the water column. During
spawning, eggs arc exposed to physical stresses (shear
stresses) during passage thought the oviduct and in the water
column. These physical stresses have the potential to damage
eggs. Extracellular layers surrounding eggs appear to mitigate
the transmission of these forces to the eggs. In experiments
where eggs of Arbacia punctulata were exposed to shear
stresses apparent in the oviduct during spawning, more eggs
with extracellular layers survive than do eggs without
extracellular layers. To determine whether extracellular layers
surrounding echinoid eggs mitigate the transmission of
physical forces to eggs, experiments were conducted in which
eggs of Slrongylocentrotus franciscanus with and without
extracellular layers were compressed between two parallel
plates. Deformation of eggs with extracellular layers was
lower than that of eggs without these layers. Approximately
50% of eggs without extracellular layers were destroyed under
compression whereas no eggs with extracellular layers were
destroyed under the same force. These results provide the first
direct evidence of egg extracellular layers mitigating the
transmission of physical force to ej:gs.
LOCALIZATION AND QUANTIFICATION
OF CARBONIC ANHYDRASE IN C.
XAMACHANA.
A.M.ESTES*,S.C. KEMPF, R.P.HENRY
Auburn University, Al.
Carbonic anhydrase (CA), which catalyzes
the reversible dehydration of HCOj, is
believed to supply CO? to endosymbiotic
dinoflagellates of cnidarians. If CA is critical
to algal CO2 supply, location and
concentration of CA should be affected by
presence and abundance of algae. Oral
epithelial bell tissue of symbiotic Cassiopeia
xamachana has four times the algae associated
with it than the aboral side and has three-fold
higher CA activity as measured by the delta
pH CA assay. CA localization, using the
fluorescent inhibitor dansylamide (DNSA),
revealed a positive correlation between CA
concentration and algal presence. A distinct
band of DNSA-CA fluorescence was present
in oral epithelial tissue. Control tissues,
treated with ethoxzolamide, showed minimal
fluorescence. Symbiotic tissue and oral
epithelial layers fluoresced 1.5 times as
brightly as aposymbiotic tissue and aboral
epithelial layers.
Division of Invertebrate Zoology
239E
ABSTRACTS
THE ASCENT TO DOMINANCE OF PORITESRUS
(CN1DARIA: SCLERACTIN1A) ON A DISTURBED
CORAL REEF IN THE WESTERN PACIFIC OCEAN.
N.J. Quinn* and B.L. Kojis. Univ. South Pacific. Suva.
Fiji and US Virgin Islands Govt.. St. Thomas. U.S.
Virgin Islands. bkojisgSmola.uvi.edu
Scleractinian coral cover on coral reefs around islands
in the Northern Mariana Islands was substantially
reduced by an out-break of the Crown of Thorns (CoT)
starfish (/Icanthasler planci) in the 1960's. Following the
CoT outbreak, coral cover on the outer slope of the
western side of Saipan was estimated to be less than 5%.
Ponies rus was rare and was observed to be resistant to
predation by CoT. Twenty seven years after the outbreak,
P. rus had become the dominant species on many reefs of
the Northern Marianas Islands. Scleractinian larval
recruitment rates were low suggesting that reef development was being inhibited by lack of recruitment by
sexually produced larvae. The ascent to dominance of /'.
rus appears to be a function of its resistance to CoT
predation combined with indeterminate growth which
enables it to spread by forming large, extensive colonies
or clones. Its growth form from, a massive base with
short branches, may enable it to successfully fragment
and colonize new areas during storm events which are
seasonally common in the Northern Marianas Islands.
1 3 3 A
Division of Neurobiology
254B
254A
A Briscoe and L Wagy, University of Arizona,
[email protected]
Buoerfly ommatidia are composed of nine photonxeptor
cells, Rl-9, arranged in a semi-tiered fashion around a
centra], fused rhabdom. In order to elucidate the visual role
of six opsins (PglRhl-6) cloned from Papilio glaucus, we
performed single and double-labelled in situ hybridizations
on serially sectioned frozen head tissue. Phylogenedc
analysis had suggested that one of the six P. glaucus opsins
(PglRhS) is UV-sensitive, one (PglRh6) is blue-sensitive,
and theremainingfour (PglRhl-4) are long wavelengthsensitive (three more than found in most insects). We find
that both PglRh5 and PglRh6 probes hybridize to
photoreceptor cell types (R1-R2) known to be either UV- or
blue-sensitive. Probes to PglRhl and PglRh2 hybridize to
green-sensitive photoreceptor cells (R3-R4), and to green- or
red-sensitive photoreceptor cells (R9). PglRh2 and PgRh3
probes hybridize to photoreceptor cells that are either greenor red-sensitive (R5-R8). By contrast with the expression
patterns of the other Papilio opsins, which are found
primarily in the cytoplasm of pholoreceptor cells, PgKh4
transcript was delected in or around the nuclei of the retina
and optic lobe, and the PglRM protein was detected in the
neuronal axons in the optic lobe. No PglR4 protein was
detected in the retina. These findings suggest an altered
function for PglRM, analogous to the non-visual opsin-like
molecules found in mammals, e.g. encephalopsin.
254D
254C
SENSORY RESPONSES AND DENDRITIC
PROJECTIONS DEFINE DISTINCT
FUNCTIONAL GROUPS OF DENDRITIC
ARBORIZATION NEURONS IN MANDUCA
SEXTA
W.B. Grueber* and J.W. Truman, University of
Washington. Seattle. [email protected]
The insect body wall is covered with a plexus of
rrjultid.endrilic-d.cndrilic arborization (md-da) neurons.
Physiological and anatomical studies indicate that
these neurons fall into three discrete classes. The P
class, represented by the ddaC neuron, is tonically
active and responds to light touch of approximately
0.5 mN. The y class, represented by ddaD, is
normally silent but responds to tactile stimuli above
2.5 mN. The a class, represented by ddaB, may be
output cells rather than sensory neurons. Although
the peripheral receptive fields of neurons belonging to
different classes overlap extensively, there is little if
any overlap among cells within the same class.
Together, these data indicate that distinct classes of
md-da neurons allow insects to discriminate, and
presumably show appropriate behavioral responses to,
touch of varying intensities. Funding: NIH
134A
A 3-D ATLAS OF THE BRAIN OF A BELUGA
WHALE IN MAGNETIC RESONANCE IMAGES
T. L. Murphy, L. Marino, J. A Morris,
A. L. Deweerd, S. H Ridgway, A. J. Fobbs,
N. Humblot, J. L Johnson* MI State U., E.
Lansing; Emory U., Atlanta, GA; Nav. Marine
Mamm. Progr., San Diego.CA; NMHHAFIP,
Washington, DC.
[email protected]
Using magnetic resonance imaging (MPJ), the
internal structure of the brain can be observed when
sectioning and staining are not practicable. Internal
structures can be analyzed in their precise
quantitative spatial relationships, difficult with the
distortions due to histological processing. Images ofc
the brain of a beluga whale Delphinapterus leucas
were scanned in the coronal plane at 119 anteroposterior levels. From these MRI scans, a 3dimensional digital model was constructed using
VoxelView and VoxelMath programs (Vital
Images, Inc.) This model was then resectioned to
produce series of virtual sections, 165 in the
horizontal and 263 in the sagittal plane. Sections in
all 3 planes show the sizes and positions of such
structures as the corpus callosum, internal capsule,
cerebral peduncles, cerebral ventricles, certain
thalamic nuclear groups, caudate nucleus, ventral
striatum, subtantia nigra, pontine nuclei,
cerebellum, and all cerebral conical sulci and gyri.
Support: NSF B N 9814911,9814912,9812712.
THE TEGUMENT OF SCHISTOSOMA
MANSONl (TREMATODA) LARVAE IS A SITE
OF SEROTONIN STORAGE AND CARRIERMEDIATED SEROTONIN UPTAKE.
JP Boyle*, TP Yoshino, Dept. of Pathobiological
Sciences, University of Wisconsin-Madison
(*boylej@ svm.vetmed.wisc.edu), & JM Melville,
Dept. of Zoology, Oregon St. University.
The human blood fluke, Schistosoma mansoni,
has a two-host life cycle, with larval development
occurring in a snail intermediate host. We are
interested in the role of serotonin (5-hydroxytryptamine; 5-HT) in larval physiology. In vitro
transformed mother sporocysts were acid extracted
and subjected to HPLC-ED to analyze endogenous
levels of 5-HT. We detected 0.8 ± 0.03 picomoles
5-HT per 1000 parasites, roughly 20 uM if evenly
distributed throughout each worm. Using an anti-5HT antibody and confocal microscopy, we have
shown that this 5-HT is found exclusively in the
syncytial tegument. Because the tegument is
essential for the uptake of host-derived molecules,
we hypothesized that it was a capable of taking up
exogenous 5-HT. Indeed, worm 5-HT content
increased 8-fold after a 2 h incubation in 10 uM 5HT. This increase was inhibited by two serotonin
uptake inhibitors (both at 10 uM), and in the
presence of either low Na* or Cl' saline, suggesting
that 5. mansoni larvae express 5-HT transporters on
their tegumental surface. These results raise
interesting questions as to the role of 5-HT in the
biology of this parasite-host system. (Supported in
part by NIH grants AI38263 and AI07414)
SPATIAL EXPRESSION OF OPSINS IN THE RETINA
AND BRAIN OF THE TIGER SWALLOWTAIL PAP1UO
CLAUCUS
Division of Systematic & Evolutionary Biology
261A
261B
261D
261C
THE EVOLUTION OF LOCOMOTOR
SPECIALIZATIONS IN MOLES.
H. P. Whidden. Augustana College, Rock
Island, IL. [email protected]
The family Talpidae contains shrew moles,
desmans, burrowing moles, and the star-nosed
mole. Talpids exhibit remarkable locomotor
diversity; taxa are ambulatory, semi-aquatic,
aquatic/fossorial, semifossonal, and fully
fossorial. I used a phytogeny of the Talpidae
to test hypotheses of adaptation for 3 talpid
apomorpnies. The unique talpid
humeroclavicular joint nas been interpreted as
an adaptation for burrowing. However, this
hypothesis is contradicted by the phylogenetic
placement of the trait; it is more plausibly an
adaptation for aquatic locomotion. Stiffening
of the manus with loss of Mm. flexor breves
increases the effectiveness of the manus as a
digging tool. This change is inferred to be an
adaptation for burrowing that originated in
semifossorial taxa. Development of an
interscapular ligament from part of M.
rhomboideus counters the pull from a
hypertrophied M. teres major. It is inferred to
be an adaptation that allows a more powerful
digging stroke in fully fossorial taxa. I then
evaluated competing nypotheses for the
evolution of specialized locomotor habits in
talpids. Several lines of evidence suggest that
semi-aquatic rather than semifossoriafnabits
are primitive for talpids other than Uropsilus.
ABSTRACTS
PHYLOGENY OF THE DEUTEROSTOMES: A
MOLECULAR ANALYSIS OF LARGE AND SMALL
SUBUNIT RIBOSOMAL RNA GENE SEQUENCES.
C.J. Winchell,* J. Mallatt, J. Sullivan, C.B. Cameron and
B.J. Swalla Washington State Univ., Univ. ofldaho,
Univ. of Alberta, and Univ. of Washington.
winchelKSimail. wsu.edu
We explored the interrelationships among
deuterostome animals by generating and comparing
nearly complete large-subunit (LSU) ribosomal gene
sequences (consisting of both the 26S/28S and S.8S
rRNA genes) from two annelids, one chelicerale, four
echinoderms, four hemichordates (including a
pterobranch), one urochordate, and two vertebrates. We
also sequenced 18S (small-subunit or SSU) rRNA genes
from one of the annelids, one of the vertebrates, and two
of the hemichordates. Using these data, as well as other
SSU and LSU sequences from GenBank, we constructed
and evaluated hypotheses of deuterostome phylogeny.
We performed bootstrap analyses with maximum
parsimony, maximum likelihood, and minimumevolution using LogDet/Paralinear distances. Although
our results show strong support for a deuterostome cladc,
we show no evidence for or against a monophyletic
chordata (relationships at this level are essentially
unresolved). The echinoderms and hemichordates each
form natural groups which together form a discrete cladc.
Monophyly of Ihe urochordates is highly supported, with
the larvaceans forming the sister laxon to the other
tunicates. The cephalochordates form the sister group to
Ihe vertebrates and cyclostome fishes branch as a
monophyletic sister group to gnathostomes.
135A
QUANTIFICATION OF ONTOGENETIC
DISCONTINUITIES IN CEPHALOPODS
E.K. Shea* and M.Vecchione. Bryn Mawr
College and NMFS, Washington, DC.
The possibility that growth trajectories
of morphological characters change during
ontogeny is often overlooked or is
estimated visually. We present an objective
method for determining such discontinuities
in three species of oceanic squids. Standard
measurements of external morphology were
plotted against increasing dorsal mantle
length (DML) to produce growth
trajectories. Discontinuities were quantified
via an iterative, Model n, piecewise linear
regression (PLR) analysis. The regression
model incorporated a fixed breakpoint that
was increased in each iteration across the
range of DMLs. The iteration that resulted
in the lowest Loss value was selected as the
best estimate of the breakpoint. We used
this method to determine if changes in
growth trajectories coincided with changes
in ecology, as is required by the concept of
a "paralarva". In all species, we found that
breakpoints in multiple characters clustered
around certain DMLs; however, these
breakpoints were not always concomitant
with ecological change.
The snake genus Lampropeltis is a diverse
group of colorfully banded snakes that range
from northeastern North America to northern
South America. Currently eight species and
forty-eight subspecies are recognized based
on morphological data. We examined this
group using mitochondrial cytochrome-b
ONA sequences to estimate phylogenetic
relationships. Our analysis suggests the
presence of two divergent groups within the
genus Lampropeltis: 1) a northern group
consisting of L. getula, L altema and the
northern L tdangulum and 2) a southern
group comprised of L mexicana, L.
pyromelana, L. zonata and the southern L.
triangulum. Lampropeltis calligaster is basa
to the group. Our data suggest a revision of
the genus may be necessary.
Division of Comparative Physiology & Biochemistry
451B
451A
METABOLIC RESPONSES TO STRESS IN
THE ANTARCTIC SCALLOP
D.W. Gaitca and PA. Berianan, Ga. fast. Tech &
Ohio State Univ. ;da [email protected]
Respiration rates (VOj) of scallops collected
from three different sites near the Italian research
station, Terra Nova Bay, Ross Sea, were measured
under ambient (-0.7 °C; 34.S °/ooS) and stress
(+2.5 °C; 28 7ooS) conditions during the austral
summer of 1998-1999. Scallops collected from the
two impacted sites (freshwater input) had
significantly higher VO2 under ambient conditions
than scallops from a non-impacted she. Similarly,
scallops collected from impacted sites displayed
longer periods of increased V0 2 following transfer
to stress conditions. Metabolic responses were
seasonal, with late season VO2 strongly influenced
by gonadal condition. During late summer
scallops that had spawned had lower VO2 than
non-spawned scallops under both ambient and
stress conditions. Seasonal changes in metabolic
patterns occurred within a tour-week period when
sea temperature did not exceed 0 °C, remarkable
evidence of adaptation to low temperature
Antarctic habitats.
Supported by NSF OPP-9813318
451D
451C
REPEATABILITY OF ION SECRETION BY
SALT GLANDS OF DESERT IGUANAS
{D1PSOSA URUS DORSAUS).
L. C. Hazard. University of California, Riverside.
[email protected]
The salt glands of most lizards secrete primarily
potassium in the field, but some lizards can secrete
sodium at high rates. Intra-populational variability
and intra-individual repeatability of sodium and
potassium secretion were measured in desert
iguanas (Dipsosaurus dorsalis). Secretion of Na
and K was measured before and after NaCI or KC1
loading (S umol/g lizard daily for four days).
Experiments were repeated over short periods (two
to four weeks) for NaCI and KCI, and over long
periods (over two years) for NaCI. In KCl-treated
lizards, secretion was not repeatable once pretreatment effects were removed. In NaCl-treated
lizards, sodium secretion, potassium secretion, and
cation ratio (K/[Na + K]) were repeatable over
short periods. Cation ratio remained significantly
repeatable over a two-year period. If the variation
and repeatability found here have an underlying
genetic basis, natural selection could act on
secretory ability, providing a mechanism for the
evolution of sodium-secreting marine lizards
species such as the marine iguana.
136A
SPECIAL CELLS IN GILLS OF FISH AND
AMPHIBIAN TADPOLES
J.C. Kaltenbach, S. Kennedy, G. Dalagiorgou,
and S. K. Nystrom, Ml. Holyoke College,
S. Hadley, MA jtownsen®mtholyoke.edu
Chloride cells, or mitochondria-rich cells, in
fish gills play an important role in ion
transport; they can be identified in sections by
their strong Na7K*-ATPase activity. Are
similar cells present in gills of amphibian
tadpoles? To answer this question, we applied
the following techniques to paraffin sections
of gills from fresh-water goldfish (Carassius
auratus) and bullfrog tadpoles (Rana
catesbeiana): 1) immunohistochemical
staining for Na7K*-ATPase and 2) lectin
staining for specific terminal sugar residues on
glycoconjugates. As expected, chloride cells in
the goldfish gills stained intensely for ATPase.
In contrast, no immunoreactive ATPase was
detected in any cells of tadpole gills (even with
high concentrations of antibody and long
incubation times). Moreover, certain cells in
gills of tadpoles (and fish) stained strongly
with horseradish peroxidase conjugated lectinJ,
such as SBA for N-acetylgalactosamine, PNA
for galactose, and WGA for Nacetylglucosamine. The results suggest that
tadpole gills do contain special cells (positive
lectin staining); yet, such cells lack ATPase
immunoreactivity and thus differ from
chloride cells in fish gills.
Little is known of normal or pathological kidney
function in shrews, yet they are often used as
bioindicators of soil contamination by toxicants,
particularly for heavy metals like cadmium which
target the kidneys. We therefore initiated studies to
define renal function and osmoregulation in C.
parva, mass 4.S g. Shrews were fed cat food and
water ad libitum, supplemented with meal worms.
Water flux (HTO turnover) was 4.7 rnl/d. Plasma
and urine osmolalities were 355 and 2244
mmol/kg, respectively. Kidney function was
assessed by infusing inulin via subcutaneous
osmotic minipumps, and by collecting blood (via
tail clip) and spontaneously voided urine. GFR
was 2.4 ml/h, somewhat less than predicted (3.9
ml/h). U/P inulin was 32, indicating fractional
water reabsorption of 97% and urine flow rate of
75ul/h (1.8 ml/d). Urinary protein and glucose
concentrations were 5.5 and 15.4 mg/dl,
respectively. We administered Cd via the diet, by
injecting it into mealworms, at a rate of 10 mg/kg
d, for 4 weeks. In response, urinary glucose rose
to a peak of 63.2 mg/dl by week 3, and urinary
protein rose slightly; concentrations of these
constituents in the plasma were unchanged, and
body mass remained stable. The altered urine
composition was accompanied by apoptosis in
renal cortical tissues. Supported by WSU
Research Initiation Grant and NSF IBN-9630630.
Division of Comparative Physiology & Biochemistry
451E
ABSTRACTS
N-ACETYL-B-GLUCOSAMINIDASE
ACTIVITY IS INDUQBLE BY THE
MOLTING HORMONE, 20HYDROXYECDYSONE, IN THE FIDDLER
CRAB, UCA PUGILATOR
E. Zou and M. Fingerman. Univ. of California,
Davis, and Tulane Univ., New Orleans.
N-Acetyl-B-glucosaminidase is one of two
chitinolytic enzymes responsible for breakdown
of chitinous cxoskeleton of crustaceans during
the premolt stage. Activity of N-acetyl-Bglucosaminidase in the epidermis and
hepatopancreas of the fiddler crab, Uca pugilator,
was found to vary during the molting cycle with
peak activity in both tissues occurring in premolt
substage D^,. This pattern of N-acetyl-Bglucosaminidase activity parallels the hemolymph
liter of ecdysteroids during the molting cycle
reported for the same species. Injections of the
molting hormone, 20-hydroxyecdysone, at 25
ug/g live weight, into crabs in premolt substage
D,, significantly increased N-acetyl-Bglucosaminidase activity in the epidermis by
86%. These results are the first direct evidence
that N-acetyl-B-glucosaminidase activity is
inducible by the molting hormone in a
crustacean.
137A
Division of Development & Cell Biology
459A
459B
459D
459C
EARLY DEVELOPMENT OF THE SUMMER
FLOUNDER PARALICHTHYS DENTATUS.
G.M. Martinez* and J.A. Bolker. University of New
Hampshire, Durham, [email protected]
The summer flounder (Paralichthys dentatus) is a
commercially important species for which there is a
growing aquaculture industry, but surprisingly little
is known about its early development. Basic
embryological research can contribute to
aquaculture efforts by shedding light on the
developmental basis of common defects. At the
same time, taking advantage of the availability of
;ommercially reared species such as summer
flounder can add to our knowledge of marine teieost
development. We present a preliminary embryonic
staging series for summer flounder, focusing on
major events and morphological landmarks that
appear between fertilization and hatching. Samples
of embryos and larvae were collected daily from a
commercial aquaculture facility (Great Bay
Aquafarms, Newington, NH). Living specimens
were photographed at 1-2 hour intervals to capture
images of all major embryonic stages. Camera
lucida drawings were subsequently prepared from
fixed material to supplement the photographs.
Supported by a grant from the Hubbard Marine
Research Initiation and Infrastructure Program to
J.A.B.
138A
INHIBITORS OF PROTEIN KINASE C
PREVENT INDUCTION OF METAMORPHOSIS BY MMA IN A HYDROID
M.B. Thomas, C. Elmore, and A. Shariatpanahi.
University of North Carolina, Charlotte.
[email protected]
Hydroid larvae require an exogenous
stimulus for metamorphosis. Schneider & Leitz
(1994) and Leitz & Lay (1995) provided a
model for signal transduction during metamorphosis in the hydroid Hydractinia echinata. The
model proposes that a bacterial product binds a
receptor on anterior sensory cells resulting in
production of diacylglycerol which then activates protein kinase C (PKC); activation of PKC
results in release of an LW-amide, MMA, which
causes other cells to transform to polypoid cells.
We used H. symbiolongicarpus to explore the
model by determining where MMA acts relative
to PKC. Since the model places MMA downstream of PKC-activation, inhibitors of PKC
should not interfere with induction by MMA.
Results indicate, however, that PKC inhibitors
do block induction of metamorphosis by MMA.
We suggest that the model be modified by
adding a second form of PKC in the target cells.
NOVEL ROLE FOR THE GENE SLUG IN
MEDIATING APOPTOSIS REVEALED IN THE
FROG, XENOPUS LAEV1S
T. F., Carl u , M. K. Klymkowsky1, & J. Hanken2,
'University of Colorado and 2Harvard University.
[email protected]
The neural crest is a distinct population of
embryonic cells found only in vertebrates. Its
development is mediated by several genes,
including the zinc-finger transcription factor Slug
in both chickens and mice. We examined the
function of Slug in the frog Xenopus laevis by
injecting anti-sense RNA (ASR) targeted to the 3'
UTR of Xenopus Slug (XSlug). Injection of XSlug
ASR inhibited neural crest-cell migration and led
to reduction or loss of many neural crest
derivatives, including pigment cells and cranial
cartilages. Regions of XSlug ASR also showed
significantly elevated levels of cell death. Thus, in
addition to its important role in neural crest
migration, XSlug may also mediate the cell-death
signaling pathway. This latter embryonic function
has not been suggested previously. Supported by
NSFtoT.F.CandJ.H.
REGULATION OF METAMORPHOSIS IN
ASCIDIANS.
C. D. Bishop*1, W.R. Bates2 and B.P.
Brandhorst1
'Simon Fraser University, B.C. 2Okanagan
University College, B.C. [email protected]
The regulation of metamorphosis in marine
invertebrates is poorly understood. Incubation
of ascidian larvae in HSP90 inhibitors
increases the frequency of tail resorption, the
first morphogenetic event of metamorphosis.
Nitric oxide synthase (NOS) has been shown
to regulate metamorphosis in a marine snail
(Froggett and Leise, 1999) and it interacts
with HSP90 in mammalian cells (GarciaCardena et. al. 1999). Therefore, larvae were
incubated in inhibitors of NOS and its most
common effector, soluble guanylyl cyclase.
Both inhibitors increased the frequency of
metamorphosis. NOS was detected in larval
tail muscle cells. When tails are removed from
competent larvae, heads metamorphose at
higher frequencies than intact larvae. These,
and other results indicate that a NO-mediated
signal represses metamorphosis in ascidians,
and that it may require HSP90 for this
function.
Division of Development & Cell Biology
459E
ABSTRACTS
THE CURVATURE AND CHOLESTEROL
CONTENT OF PHOSPHOLIPID BILAYERS
ALTERS THEIR TRANSBILAYER
DISTRIBUTION OF SPECIFIC SPECIES OF
PHOSPHATIDYLETHANOLAMINE (PE).
E. E. Williams*, J. A. Cooper, L. J. Jenski, and
W. Stillwell. IUPUI. [email protected]
The curvature, cholesterol content, and
transbilayer distribution of phospholipids significantly influence the functional properties of
cellular membranes, yet little is known of how
these parameters interact. Phospholipid vesicles
were prepared with large (99 run) and small (20
ran) radii of curvature and with different
proportions of cholesterol (up to 30 mol%) before
their transbilayer distributions of PE and PE fatty
acids were assessed. Membrane curvature
significantly influenced the transbilayer distribution of both PE and PE fatty acids. Membrane
cholesterol content significantly altered the distribution of some PE fatty acids, and others were
influenced by changes in both curvature and
cholesterol content. Differences in membrane
shape and composition thus likely alter the
specific array of PE molecules present on the
surfaces of cells and organelles. This may furnish
a means of modulating such functional properties
as fusion potential and microdomain architecture.
139A
Division of Evolutionary Developmental Cell Biology
473A
idenritv rn th» flu Darn »•«. • • ~-A •« . k . i - ..-~^i
._ i_"_l__i
Pax3 and Pax?. We have also raised polyclonal antisera against
conserved portions of the individual proteins that appear to
crossreact to all three proteins. The antisera also appear to
crossreact with presumptive Pglll orthologs in Schistocerca.
Trtbolium and at least two crustaceans. Data on theroleof
"pair-berry" in the segmentation of other species, as inferred
from expression data, should shed light on both the evolution of
segmentation in arthropods, and possibly the origins of
segmentation more generally.
473C
DOMINANCE AND EPISTASIS AS EMERGENT
PROPERTIES USING A SIMPLE DEVELOPMENTAL MODEL.
Gilchrist, M.A., Duke University, [email protected]
I explore how initially additive gene interactions
within a locus can lead to dominant and epistatic
effects when combined with simple model of trait
development. This work is based on a model in
which the size of a trait is determined by the
location of a concentration threshold of a
morphogen diffusing from a point source. Each
parameter in the model is controlled by a single
locus. The genotype value of an individual is
simply the sum of the two alleles at a given locus.
Analyzing this model I find that both dominance
and epistatic interactions between two loci are
ubiquitous through out the genotype space. In
addition, the behavior and strength of these effects
are greatly influenced by the genotype value at
other loci. Thus even a simple model of
development can lead to a complex relationship
between the transmission of genetic information and
the expression of a trait.
140A
USING YOUR NOGGIN TO UNDERSTAND
THE EVOLUTION OF THE LARGE EGG OF
THE DIRECT DEVELOPING FROG
ELEUTHERODACTYLUS COQU1.
H. Fang, Y. Marikawa, R.P. Elinson,
University of Toronto, Canada
[email protected]
The direct developing frog Eleutherodaaylus
coqui lacks a tadpole stage and has large 3.5mm
eggs. An increase in egg size was likely a key
step in the evolution of direct developing frogs.
To address whether this increase in egg size in
E. coqui affected the arrangement of the egg
cytoplasm, we compared responses of early
embryos of E. coqui and the metamorphosing
frog Xenopus laevis to overexpression of noggin
RNA, a neural and axis inducer. We show that
noggin RNA induces complete extra axes with
heads in E. coqui embryos, but only trunks in X.
laevis embryos. This different response of the
E. coqui embryo to noggin RNA suggests that
the distribution of dorsal determinants in the E.
coqui embryo is significantly different from that
in the X. laevis embryo.
473D
CRANIOFACIAL DEVELOPMENT IN THE
LAMPREY EMBRYO AND EVOLUTION OF
THE VERTEBRATE
JAW 1
S. Kuratani*1, Y. Nobusada
, N. Horigome1, M.
Myojin' and S. Hirano2 2'Dept. Biol., Okayama
Univ. Fac. Sci., Japan; Dept. Anat., Niigata Univ.
Sch. Med., Japan (S.K.: [email protected])
Embryonic development and gene expressions
of the Japanese marine lamprey, Lampetrajaponica,
were examined. Cephalic neural crest cells were
distributed as three cell populations associated with
pharyngeal arches and rhombomeres. Focal
injection of Dilrevealedthat the crest cells were
anteroposteriorly organized along the neuraxis
before emigration, and the cells derived from the
Ofcc-expressing midbrain migrated into the
mandibular and premandibular regions. Overall
morphological pattern was similar to gnathostomes,
showing the conserved phylotype of vertebrates. In
later stages, the craniofacial ectomesenchyme
showed strikingly different distribution patterns in
each animal group, so that homologies are lost in
oral structures; the upper lip of the lamprey seemed
to belong to the premandibular component, unlike
the gnathostome upper jaw. The Dbc gene, whose
expression is restricted to the mandibular arch
derivatives in gnathostomes, was expressed also in
the upper lip in the lamprey, implying the
evolutionary shift of gene expression domains was
involved, possibly through heterotopic processes,
in the evolution of the gnathostome jaw.
G.K. Davis. C.A. Jararaillo. and N.H. Patet. University of
'
Chicago, IL.
The Drosophila Pax group in (Pgin) genes paired,
gooseberry, and gooseberry-neuro encode transcription factors,
each containing both a DNA-binding paired domain and a
paired-type homeodomain. paired acts as one of several pairrule genes to define the boundaries of future segments via the
activation of segment-polarity genes, including gooseberry,
gooseberry-neuro is a gene of is yet undefined function
expressed later in the developing nervous system. The three
genes are similar in sequence and are thought to have resulted
from two duplication events in the lineage leading to Drosophila.
The protein products are also functionally equivalent, as the
coding regions have been shown to be functionally
interchangeable between the different cis-regulatory regions
(Xue and Noll. EMBO. 45. 3722-3731, 1996). The evolutionary
changes affecting development have thus been restricted to
these cis-regulatory regions. Because of their importance in
segmentation we are screening cDNA pools from early embryos
of the short-germ insect Schistocerca. We have identified at
least two distinct Schistocerca genes that have high sequence
473B
Division of Evolutionary Developmental Cell Biology
473E
ABSTRACTS
DIFFERENT ECHINODERM CLASSES
HAVE DIFFERENT HOX GENE CLUSTERS
SC Lone* & M Byrne
Anatomy Fl 3. University of Sydney NSW
2006. Australia
[email protected]
Of current interest in evo-devo research is the
problem of how such a diversity of animal body
plans is generated through the "remarkably
conserved" sequences of Hox genes. Despite
their highly derived pentameral body plan,
echinoderms have a Hox cluster essentially
similar to those of bilateral organisms (Martinez
et al. 1999). Recently Martinez et al. (1999)
showed that the Hox cluster of the echinoid
Strongxlacentrotus purpuratus contains ten
genes. Comparison with genes from eight other
echinoids, three asteroids and a holothuroid
shows that the Hox clusters of different
echinoderm classes contain different genes. Of
particular interest are the apparently classspecific expansions which have occurred
amongst the more posterior Hox gene groups.
Perhaps this is the echinoderm solution to the
problem of generating body plan diversity, via
class-specific duplication and evolution of Hox
genes within the cluster.
141A
Division of Vertebrate Morphology
509B
509A
142A
THE DEVELOPMENT OF CRANIAL ORNAMENTATION
IN THE ANKYLOSAURIA: TOWARDS RESOLVING AN
ARCHITECTURAL ENIGMA USING THE
COMPARATIVE METHOD
M.K. Vickaryous and A.P. Russell, University of
Calgary, AB. [email protected]
The dinosaur clade Ankylosauria (Omilhschia:
Thyreophora) is characterized by a novel skull
morphology and the pervasive development of
postcranial osteoderms. A review of fossil material
attributed to this taxon provides a unique
opportunity to examine the development of
ornamentation in a fossi) group, and reappraise the
hypothesized developmental pathways. Osseous
cranial ornamentation occurs within representative
members of most major tetrapod clades, and
appears to be structurally similar to that noted in
ankylosaurs. A review of modem taxa (with a
special emphasis on squamates) identifies two
alternative developmental pathways giving rise to
osseous cranial ornamentation: the coossification of
osteoderms superficial to, and sometimes with, the
dermatocranium (as typified by members of the
Scleroglossa); and the elaboration of individual
dermatocraniat elements proper (as in members of
the Iguania). The identification of osteological
correlates for each ontogenetic process permits the
diagnosis of the condition in ankylosaurs. The
revised hypothesis postulates that cranial ontogeny
of ankylosaurs involved both developmental
pathways: dermatocranial element elaboration in
concert with osteoderm coossification.
HINDLIMB EVOLUTION IN ARCHOSAURS:
MUSCULOSKELETAL FORM AND FUNCTION
IN A PHYLOGENETIC PERSPECTIVE.
Hutchinson, J.R.* & Galesy, S.M. Dept Integr
Biol, Univ of Calif & Dept Ecol Evol Biol, Brown
Univ. Providence [email protected]
We integrate dala from myology, locomotion, and
fossils to reconstruct the pattern of locomotor
evolution in archosaurs. Crocodylians retain most
ancestral aspects of morphology and locomotion.
Many traits commonly thought of as "avian," such
as the expansive ilium and dorsal thigh musculature,
widened postacetabular pelvis and reduced ventral
symphyses. and proximally shifted thigh muscle
insertions first evolved in non-avian theropods.
Some features of locomotor morphology, such as
the antitrochanter. ilio-ischiadic fenestra, retroverted
pubes and ischia, pygostyle, trochanteric crest, and
cnemial crests, acquired their most derived character
states within Aves (especially Omithurae), but more
ancestral states first appeared in non-avian taxa.
Even basal birds probably moved slightly differently
from extant birds; their locomotor morphology is
more similar to non-avian maniraptorans than to
extant birds. Changes of body size, center of mass
position, limb proportions, joint articulations,
motor control, muscle sizes, muscle moment arms,
etc.. all contributed to this stepwise evolutionary
pattern. No single parameter tells the whole story.
Supported by NSF grant #IBN 9407367 to SMG.
SICB 2000 ANNUAL MEETING PROGRAM AUTHOR INDEX
ABSTRACTS
Paper #
161
64
543
534
95, 551
669
46, 47, 331
726
698
471
681
615
575
704
635
172
176
537
407
233
377
144
463
80
4, 299
314
164
550
559
138
210
19
290
84
5
644
627
137A
621, 629
707
661
141
624
217
405
526
705
463
116
4
441
345
236
493
684
Author
BARBOZA, P.S
BARCA, V
BARNES, S
BARTOL, I.K
BASSHAM, S
BATES, W.R
BAUER, R.T
BAVIS, R.W
BAYARSAIHAN, D
BAYASCAS, J.R
BECERRA, J. X
BECH, C
BEDFORD, J.J
BEEKEY, M.A
BEERLI, P
BEESE, K
BELDEN, L K
BELLAN.G.L
BELLAN-SANTINI, D. R
BELLWOOD, D.R
BELTZ, B.S
BELY, A. E
BENJAMIN, N
BENNETT, A.F
BENNETT, V.A
BENNETT, W.0
BERENBAUM, M
BERKMAN, P.A
BERRIGAN, D
BERTRAM, J.E.A
BETTENCOURT, B.R
BEUCHAT, C A
BHARDWAJ, S
BIELER, R
BIEWENER, A.A
BIKNEVICIUS, A.R
BIRCH, D
BIRCH, J.M
BIRD, D. F
BISHOP, C D
BISHOP, K.L
BLAIR, C.P
BLAKE, D.B
BLANCHETTE, C
BLANK, J.M
BLANKENSHIP, J.E
BLAUSTEIN, A.R
BLAYLOCK, M.L
BLOB, R.W
BLOCK, B.A
BODE, H
BOETTCHER, A. A
BOETTGER, S.A
BOGGS, C.L
BOGITSH, B.J
Paper #
416
137B
140
329
300
459A
585
45
462
526
286
96
385
41
48
508
177
189
189, 205
326, 591
511
65
262
193, 340, 341, 408
176, 449
694
287
451A
48
626
83
398
452
214
335, 379, 616, 692
625
163
572, 603
2
459A, 459C
501
543
5
320
426
647
177
555
336
426
522
722
735
565
239
143A
Author
ABELL, A. J
ABOUHEIF, E
ABRAHAMSON, W.G
ABZHANOV, A
ACKERMAN, R.A
ADAMS, N.L
AERTS, P
AGUON, J.M
AHN, A.N
AIROLDI, S
ALBERTSON, R.C
ALENGHAT, T
ALFARO, M
ALLEN, C.E
ALLEN, G.E
ALLEN, J.D
ALLEN, T.F
ALLISON, G.W
ALTIMIRAS, J
ALTSCULER, S.B
ALVES, C D
ALWORTH, L C
AMEMIYA, C
AMORES, A
AMSLER, C D
AMUNDSON, R
ANCTIL, M
ANDREWJESKI, P. M
ANGILLETTA, M.J
ANGUS, R.A
ARDELEAN, A
ARDIGO, L P
ARNOLD, T.M
ARONOWSKY, A
ARONSON, R.B
ARTHUR, W
ASHLEY-ROSS, M.A
AUSTIN, J
AUTUMN, K
AVILA, C
AVISE, J.C
BABBITT, K.J
BACHUS, K. N
BACON, S. N
BAGATTO, B
BAGUNA, J
BAILEY, C.L
BAILEY, W
BAILEY, W.D
BAKER, B.J
BAKER, S.M
BANTA, M.R
BARAGONA, M.A
BARANOWITZ, S
BARBEAU, T.R
SICB 2000 ANNUAL MEETING PROGRAM AUTHOR INDEX continued
144A
Paper #
119
556
459C, 639
608
239D
605
273
722
374
152
148, 149, 150, 387, 516
3, 455
604
304
368
414
282
606
100, 123, 663
719
254A
711
355
477, 582
573, 622
447
459A
494
27
588, 589
239
254B
201
280
448
284
386
197F
731
106
184, 197B
162
652
202A
285
117, 165
641
79
190
33
371
417
500
405, 407
633
Author
Paper #
BURKE, A.C
531
BURKHOLDER, J
289
BURMEISTER, S
171A
BURNAFORD, J.L
677
BURNETT, K
710
BURNETT, L.E
437, 710
BURNS, J
9
BURNS, J.S
432
BUSHAR, L M
197D, 473E
BUTCHER, M.T
627
BUTLER, M.A
192
BUTTEMER, W.A
96
BYRNE, M
473E, 586
BYRUM, C.A
60
CAIN, S.D
251, 252
CALDWELL, H.K
112
CALLOWAY, P
451B
CAMERON, C.B
261D
CAMERON, R. A
532
CAMPBELL, A.J
139
CAMPBELL, M
492
CAMPIONI-NOACK, M
131
CAMPOVERDE, M
387
CAO, C
165
CAPODAGLIO, E. M
19
CAPPOLA, V.A
255
CARL, T.F
459B
CARLE, M
208
CARLONI, R.A
199
CARPENTER, J.F
402
CARR, J.A
131, 162
CARRIER, D. R
384, 496, 498, 623, 624, 695
CARROLL, S
731
CARROLL, S.B
641
CASEM, M.L
459
CASOTTI, G
683
CASTO, J.M
159, 371
CASTRO-AGUIRRE, J.L
485
CASTRO-SANTOS, T
318
CATE, H.S
103, 105
CAVA, F.M
308
CAVEY, M.J
588, 589
CERRETELLI, P
25
CHALLENGER, W.0
121
CHAN, S.-M
147
CHAN, W.-P
621
CHANG, E.S
451, 511, 514
CHANG, S.A
511
CHANG, Y.-H
628
CHAO, E
571
CHAPMAN, S.L
403
CHAPPELL, M.A
96
CHARMANTIER, G
388, 399, 400
CHARMANTIER-DAURES, M
399
CHEEK, A.0
731
Author
BOHANNON, J
BOILY, P
BOLKER, J.A
BOLLER, M.L
BOLTON, T.F
BOMER, B
BONAVENTURA, J
BOONE, E
BOORSE, G.C
BORDERS, K.J
BORST, D.W
BOSCH, 1
BOTHAM, C M
BOTTON, M.L
BOWDEN, R.M
BOWEN, J. T
BOWERS, M. D
BOWKER, G.E
BOYD, S.K
BOYKO, C.B
BOYLE, J. P
BOYLE, R
BRADLEY, T.J
BRAINERD, E. L
BRAMBLE, D. M
BRANCO, L.G.S
BRANDHURST, B.P
BRANDONI, C
BREMER, E
BRENNER, T.L
BRINDLEY, P.J
BRISCOE, A
BRITO, C.P
BROCHU, C.A
BRODKIN, M
BRONSTEIN, J.L
BROOKS, C
BROOKS, W.R
BROUWER, M
BROWN, A.L
BROWN, B.L
BROWN, C.L
BROWN, G. D
BROWN, G
BROWN, J
BROWN, M. R
BRUNETTI, C
BUDD, G.E
BUDDEMEIER, R. W
BUEHRER, B.M
BUERKLE, C.A
BUFFENSTEIN, R
BURDICK, J. B
BURGGREN, W.W
BURIAN, R.M
SICB 2000 ANNUAL MEETING PROGRAM AUTHOR INDEX Continued
ABSTRACTS
Author
CULLINANE, D.M
CULLUM, A.J
CUNDALL, D
CUNNINGHAM, S.L
CUPP, JR., P. V
CURTIN, N.A
CUSHMAN, J. C
CUTLER, L
CZUWALA, P.J
DAGGY, M.W
DALAGIORGOU, G
DALEY, M.A
DALTON, J.P
DALY, M
DAMME, R. VAN
DANDAR, A
DANIEL, T.L
DANNER, E
DAVIDSON, E
DAVIES, N
DAVIS, G.K
DAWLEY, E.D
DE LA PAZ, K.L
DEARING, M. D
DEAROLF, J.L
DEBOER, M.D
DECKER, J.D
DEFUR, P. L
DEGNAN, B.M
DEL CARMEN, K.A
DELLACORTE, C
DELONG, E. F
DEMAINTENON, M.J
DEMER, D.A
DENARDO, D
DENNY, M.W
DENVER, R.J
DERBY, C D
DESAI, P
DETHIER, M.N
DETRICH, III, H.W
DEUFEL, A
DEVRIES, A.L
DEW, J.D
DEWEERD, A.L
DIAL, K.P
DIAMOND, J
DICKHOFF, W.W
DICKIE, R
DICKINSON, M.H
DIEHL, W.J
DIETRICH, M.R
DILLAMAN, R.M
DIMACULANGAN, D.D
DIMOCK, JR., R.V
Paper #
313, 571
193
576
206
127
696
34
358
320, 321
338
451D
622
239
211
47
454
16, 612, 687, 699, 700
204
532
711
473
102
380
181
581
430
598
354
221, 528
114
216
2
61
197A
124
678
108, 373, 374, 375
103, 105, 672
363, 365, 366
535A
11
576
12
197C
254D
616
562, 566
167
91
603, 611
435, 438
636
499
452
297, 586
145A
Author
Paper #
CHEN, J.J
629
CHENG, S
113
CHESTER, C M
208
CHI, K
478
CHIPMAN, A.D
75
CHIU, C
646
CHOE, K.P
392
CHOQUETTE, D. M
477
CHOU, M.Y
397
CHRISTIANS, J.K
120
CHRISTMAN, T. M
414
CIMINO, G
707
CLAIBORNE, J.B
392, 393, 394
CLAMP, J.C
688
CLARK, A.G
356
CLARK, J.J
406
CLARKE, A.L
52
CLAY, K
283
CLEAVE, C.L VAN
219
CLEMENS, J.W
160, 200
CLEMENS, S
648
CLIFTON, K.B
475
COBB, N
220
COFFROTH, M.A
295, 727
COGGER, E. A
379, 380, 381, 631
COHEN, B.A
309
COLE, A.G
104
COLLIE, N.L
139, 168
COLLIN, R
62
COLLINS, T.M
214
COMBES, S.A
16, 612
CONDON, K
490
CONGDON, J.D
445, 567
CONLEY, K.E
693
CONNERS, D.E
220
CONNOR, E. A
582
CONROY, R.M
196
COOK, A
668
COOK, C.B
197F
COOK, J
235
COOPER, J
691
COOPER, J.A
459E
COOPER, R.L. .243, 244, 245, 246, 247, 248, 249
COPELAND, J
137
CORLEY, L.S
67
COSTA, D.P
197A
COSTA, M.J
201
COSTANZO, J.P
197, 443
COUCH, C.R
197B
COURTLAND, H.-W
322
CREASER, E. S
307, 439
CRIPE, G.M
146
CROKER, D.E
197A
CROLL, G.A
670
CROSSLEY, D.A
407
146A
Paper #
178
152
199
164
350
490
638
427
106
479
662
323
111
666
377
10
264
151
729, 733
241
343
419
308
503
223
123
77, 315
39
309
111, 229
180
446
364
153
578
473B
420, 429
459D
270
476
33
673
690
57
502
185
239A
543
468
549
368
106
714, 715, 716
72
497
Author
FANG, H
FARRELL, B
FAUST, L
FAUTIN, D.G
FEARING, R
FEDER, M.E
FEMINELLA, J
FERGUSON, S.A
FERRARIS, J.D
FERRY-GRAHAM, L A
FETZNER, JR., J.W
FICKBOHM, D.J
FIFE, M. M
FINGERMAN, M
FINK, W.L
FINKLER, M. S
FINNERTY, J.R
FISH, F.E
FISHER, G.R
FITZHUGH, G.H
FIVIZZANI, A.J
FLAVUS, T
FLICK, K
FLORES, R.M
FLYNN, K.M
FOBBS, A.J
FOGEL, M.L
FOGLEMAN, J.C
FOLEY, W
FOLK, D.G
FONTANA, A
FORCE, A
FOSS, S
FOX, D
FRANCIS, JR., A.W
FRANCIS, L A
FRANK, C.L
FRAZIER, M.R
FRAZZETTA, T. H
FREEMAN, E.W
FREIDENBURG, T
FROST, G. T
FROST, W.N
FRYE, M. A
FULL, R.J
FULLERTON, M.D
FYFE-JOHNSON, A
GAINEY, JR., L F
GALANT, R
GALIS, F
GALLARDO, C.S
GAMKRELIDZE, G.N
GANNES, L Z
GARCIA-FERNANDEZ, J
GAREY, J.R
Paper #
473B
544
137
212, 255
621
83, 194
720
145
31
583, 590
254D, 261A
112, 648
498, 695
451E
597
414
521
337
297
425
153
672
334
362
145
199, 254D
565
540
711
355
707
460, 466
146
307
504
308
359
352
474
134
537
486
655
687
621, 629, 697, 698
212
385
421
641
70
118
647
554
526
82
Author
DINGMANN, B.J
DIRCKSEN, H
DIZACK, C.L
DOBLE, K.E
DOELLER, J.E
DONNELLY, M.A
DONOGHUE, M.J
DONOVAN, E.R
DORSEY, D. A
DRABEK, C M
DRIES, L A
DRUCKER, E.G
DRUMMOND, J
DUCKWORTH, R.A
DUFFY, J.L
DUNTON, K.D
DURHAM, N
DURICA, D.S
DUTTA, H. M
DZHASHIASHVILI, Y.Y
DZIALOWSKI, E.M
EADS, B.D
EARLE, S.A
EARLS, K.D
EAVES, A.A
EBERSOLE, T.J
EBLE, G.J
ECKERT, G.L
EDWARDS, D.D
EDWARDS, D.H
EDWARDS, D.R
EDWARDS, J.R
EHRMAN, M.M
ELF, P.K
ELIAS, J. A
ELINSON, R.P
ELLINGTON, W.R
ELMORE, C
ELPHICK, M.R
ERICKSON, G.M
ERREDE, B
ESCH, H.E
ESPINOZA, N.R
ESPINOZA, R.E
ESSNER, JR., R. L
ESTEP, A.D
ESTES, A.M
EUBANKS, M.D
EUTSCH, J.S
EVANS, D.H
EWERT, M.A
EYCK, G.R. TEN
FAETH, S. H
FALCK, P
FAMINI, D.J
ABSTRACTS
Paper #
451A
20
216
509A, 615
190
483
175
637
250
673
386
257
626
272
302
209
197D
359
265
468
48
81
635
473C
198, 203
653
335
106
686
21, 427, 561
373
713
137E
171C
197A
123
16
332
451B
199
143
610
199
25
240, 421
41
353
496
524
350
628
246
371
592
254C
Author
GU.P.-L
GUERTIN, C.J
GUGLIELMO, C.G
GUNNING, D.L
GUSSEKLOO, S.W.S
GUYER, C
HADFIELD, M.G
HADJ-CHIKH, L.Z
HAENNI, E.G
HAGGARD, J
HAHN, T.P
HAIGWOOD, J.T
HALANYCH, K. M
HALE, B.B
HALE, M.E
HALL, B.K
HALPERN, M
HALPIN, P.M
HAMIDANI, G
HAMILTON, C.E
HAMMER, H.S
HAMMOND, K.A
HANCOCK, T.V
HAND, S.C
HANKEN, J
HANSEN, T
HANTEN, J. J
HARO, A
HARRIS, L.G
HARRISON, D.A
HARRISON, J.F
HARRISON, P.J.H
HARTZLER, L K
HATCH, A.C
HATCH, K.A
HATLE, J.D
HAUSER, K.C
HAUSWALDT, S
HAYES, T.B
HAZARD, L C
HECHT, L B
HECK, JR., K.L
HEIGENHAUSER, G.J.F
HELANDER, M
HELMUTH, B.S
HENDERSON, M.J
HENDERSON, S.Y
HENRY, R.P
HERBER, S.A
HERMANSON, J.W
HERP, F. VAN
HERREL, A.H
HERREL, A.I
HERRERA, L.G
HERRING, S.W
Paper #
147
377
97
394
509
156
114, 536
702
457
243
126, 664
362
261, 523
609
319
73, 458, 634
570
537
672
715
563
557
21, 561
402, 419, 431
459B
646
207
318
208
249
94, 353
105
408
177
415, 554
149, 150
233
52
124, 376, 378
451C, 239A
150
536A
23
716
678
455
225
239A, 386, 387, 720
191, 723
491, 581, 626
400
595
594
98, 541
598
147A
Author
GARTON, D.W
GASS, C. L
GATES, R. D
GATESY, S.M
GATTUSO, J.-P
GAUDIN, T.J
GAY, R
GAYON, J
GEDDIS, M.S
GEE, X
GEHNRICH, S
GELLER, J.B
GELLMAN, K.S
GELPERIN, A
GEORGE, S.B
GERKEN, S
GERUM, S.G
GIBBS, A.G
GIBBS, S.M
GIBERT, J-M
GIBERT, P
GIBSON-BROWN, J.J
GILBERT, S.F
GILCHRIST, M.A
GILCHRIST, S.L
GILLETTE, R
GILLIS, G.B
GISCOMBE, C.L
GIVENS, J
GLEESON, T.T
GLENNEMEIER, K.S
GLYNN, J
GODWIN, J
GODWIN, J.R
GOEBEL, M.E
GOETZ, F.W
GOLDMAN, E.B
GOLDMAN, J.A
GOLDSTEIN, D
GORAYSKI, P.M
GOWER, B.A
GRACE, S.P
GRAEME, K.L
GRASSI, B
GREENBERG, M.J
GREENBURG, A
GREENLEE, K.J
GREGERSEN, C. S
GRENIER, J.K
GRIESHABER, M.K
GRIFFIN, T.M
GRIFFIS, B
GRINDSTAFF, J
GRUBICH, J.R
GRUEBER, W.B
148A
Paper #
158, 161
186
717
408
692
48
666
133
453
51, 570, 630
155
221, 528
473D
458
81
367
48
322
259
48
48
731
146
148
100
258
108
151, 515
675
445, 567
137A
137A
254D, 473D, 509A
292
357
144
379, 380, 381, 631
179, 185
621
457
534
665
199, 254D
383
577
555
195
497
102
395, 396, 397
396
482
354
707
571
Author
IRSCHICK, D.J
IRVINE, S.Q
IRWIN, J.T
IRWIN, W.P
IVERSON, J.B
IYENGAR, E.V
IYER, A.K
JACKLET, J.W
JACOBS, D.K
JANZEN, F.J
JARAMILLO, C
JAYNE, B.C
JEFFERY, W.R
JEFFRIES, M.N
JEGLA, T.C
JENNINGS, D.J
JENNINGS, R
JENSEN, B.H
JENSEN, D.D
JENSEN, M.K
JENSKI, L.J
JERMAKOWICZ, W. J
JIMENEZ, E
JING, J
JOCKUSCH, E.L
JOHN, S.S
JOHNSEN, S
JOHNSON, J.I
JOHNSON, S.L
JONES, T. D
JONES, T
JORDE, D.G
JOSEPHSON, R.K
JOSS, J.M
KAATZ, I.M
KALTENBACH, J.C
KANTOROW, M
KARASOV, W. H
KARDONG, K. V
KAREIVA, P
KARENTZ, D
KARL, D. M
KARLSON, R.H
KASSNER, V
KATOH, M
KATZ, P.S
KAUFMAN, T
KEARNEY, M
KEEFER, A
KELLER, R. E
KELLER, R
KELLER, T.A
KELLEY, K.C
KELLEY, K.M
KELLIE, S. P
Paper #
617
525
434, 449
137C
197, 443
718
459
267
216
661
473A
338, 617, 618
473
483
512
372
56
413
55
184
459E, 254D
106
526
653
467
102
685
199, 254D
71
630
51
416
428
72, 163
90
202A, 239A, 451D
357
181
101, 202A, 474
545
3, 455
2
41
641
183
112,648
534
50
456
470
511
128
709
166, 362, 363, 365, 366
247
Author
HEWS, D.K
HIBBS, T.S
HICKOK, J
HICKS, J.W
HICKS, R
HILL, C
HILL, G. E
HILL, P.S.M
HILL, S.D
HILLENIUS, W.J
HILLIS-STARR, Z.-M
HINMAN, V.F
HIRANO, S
HIRATA, M
HO, R. K
HOAGLAND, T.M
HOANG, A
HOBSON, B
HOCHBERG, R
HOEKSTRA, H
HOEKSTRA, J
HOEXUM-BROUWER, T
HOGLUND, M.D
HOLFORD, K.C
HOLLIS, D.M
HOOGE, M.D
HOOPFER, E.D
HOPKINS, P.M
HOPKINS, T.S
HOPKINS, W.A
HORGAN, E
HORGAN, E
HORIGOME, N
HORN, M.H
HORWITZ, J
HOWDESHELL, K.L
HOYT, D.F
HRANITZ, J.M
HSIEH, T
HUETER, R.E
HUGHES, C
HUGHES, M
HUMBLOT, N
HUMPHREYS, H.A
HUNT VON HERBING, 1
HUNTER, H.L
HUSKEY, S.H
HUTCHINSON, J.R
HWANG, D.S
HWANG, P.P
HWANG, R.D
HYDE, M. L
HYPES, S. R
IKEN, K
INOUE, N
ABSTRACTS
Paper #
569
624
230, 239A, 348
451D
412
134, 135, 184
86
159, 370, 371
641
384
667
696
45
462, 463
442
48
30
30
76
364
190
539
202, 422
459B
149
183
681
328
267
239E
475
9
271
51
582
674
316
202, 422
455
497, 628
13
350
511
557
137
176
32
119, 546
2, 137C, 473D
54
431
465
412
171
353
Author
LAFRENTZ, J.R
LAMMERS, A.R
LANCE, V. P
LANDRY JR., S.0
LANG, J.W
LARSON, J.L
LARSON, P.M
LASKER, H.R
LAUBICHLER, M.D
LAUDER, G.V
LAUFER, H
LAUNDRIE, N. C
LAURIENTI, P.J
LAWRENCE, A.L
LAWRENCE, B.A
LAWRENCE, J.M
LAWRENCE, K.A
LECLAIR, E.E
LEE, JR., R.E
LEE, C. E
LEE, K.J
LEE, R. F
LEE, R.E
LEE, R.W
LEE, S. E
LEE, T.H
LEGARE, M
LEHMAN, F.0
LEISE, E.M
LENERTZ, K
LENSKI, R.E
LENTZ.A.J
LEONARD, J. B.K
LEONARD, M
LERMAN, D.N
LETTIERI, L
LEVINTON, J.S
LEVITAN, D.R
LEWIS, D
LEYS, S.P
LI, H
LIAO, J
LIGNOT, J.H
LILLEODDEN, E.T
LILLY, K.Y
LILLYWHITE, H.B
LIN, H.C
LIN, L. Y
LIN, Y.C
UNDER, C.J
LINDSAY, S.M
LIPAR, J.L
LITVAITIS, M.K
LITZGUS, J.D
LIZOTTE, M.P
Paper #
382
601
273
568
153
197
488
608
640, 646
323, 324, 325, 327
517
404
647
302, 563, 564
605
224, 302, 563, 564
651
461
197, 434, 443, 449
93
152
442
176
349
216
396
199
613
264
720
193
135
i
558
448
194
175
441
38
641
221
249
324
388, 390
476
152
382, 684
397
395
382
115
227
370, 371
259
197, 443
7
149A
Author
KELLY, D. A
KEMP, T. J
KEMPF, S.C
KENNEDY, S
KESSLER, K.M
KESTER, K.M
KETTEN, D.R
KETTERSON, E.D
KEYS, D
KHAN, M. A
KHAN, M.Z
KIER, W.M
KILGORE, JR, D.L
KIM, C.B
KIM, G.B
KINGSOLVER, J.G
KINNE, R.K.H
KINNE-SAFFRAN, E
KINTNER, C
KITTILSON, J.D
KLEYPAS, J. A
KLINGER, T
KLOHR, R.W
KLYMKOWSKY, M.K
KNEPP, M.D
KOBAYASHI, M
KOCHER, T.D
KOESTER, D.M
KOH, H-Y
KOJIS, B.L
KOOB, T J
KOOYMAN, G.L
KORNEEV, S.A
KOROCHKIN, E
KOSTEK, C. A
KOTEEN, L.E
KRAEMER, E. R
KRAJNIAK, K.G
KRAKOWSKI, D
KRAM, R
KRAMER, D.L
KRAUS, D.W
KRAVITZ, E.A
KRISTAN, D.M
KUBKE, M.F
KUKAL, 0
KULTZ, D
KUNKEL, J.G
KURATANI, S
KUTZBACH, J
KWAST, K.E
LABUTTI, K
LACEY, J.A
LACY, E.L
LAFRENIERE, J.J
150A
Author
MCCALL, L
MCCAULEY, D.W
MCCAY, M.G
MCCLEARY, R.J.R
MCCLINTOCK, J.B
MCCLOSKEY, B.M
MCCORMICK, S.D
MCEDWARD, L.R
MCELROY, T.C
MCFADDEN, C.S
MCFADDEN, W.A
MCGOWN, C.P
MCGUIRE, R.F
MCHENRY, M.J
MCINTYRE, J.C
MCKENNA, S. A
MCKENNEY, JR, C. L
MCLACHLAN, J.A
MCLAUGHLIN, R.L
MCLEAN, S
MCLELLAN, W.A
MCMINN, J.T
MCNABB, F.M.A
MCPHERSON, D.R
MCWHORTER, T.J
MEFFERT, R
MEIJER, K
MELROE, G
MELVILLE, J.M
MENARD, K
MENDONCA, M.T
MENGE, B.A
MENON, J
MENON, V
MENSINGER, A.F
MERZ, R.A
MEYER, A
MEYER, H.A
MEYERS, J.J
MICHEL, W.C
MICHENER, W.K
MIDDLETON, K.M
MIKKELSEN, P.M
MIKULSKI, C
MILLER, L.R
MILLER, N
MILLER, W
MILLS, C.E
MINER, B.G
MINETTI, A.E
MINOR, M.D
MIRE, P
MIYAKE, T
MOCZEK, A.P
Paper #
315
473
614
734
4, 224, 298, 299, 563,
564, 670, 735
212
36, 546, 548, 730
39
435
42
452
572
381
607
137D
724
146, 444
731
13
711
499, 581, 679, 680
406
667, 734
423
360, 541
571
697
364
254A
713
125, 156, 157, 666, 732
537
493, 494
493, 494
706
233
530
186
594, 595
103
156
92
61, 719
710
137D, 254D, 261A
360
463
43
303
19
142
213
73
66
Author
Paper #
LOGAN, C. A
317
LOHMANN, K.J
137C, 251, 252
LOMBARDINI, R.L
168
LONG, A.D
340
LONG, JR., J.H
320, 321, 322
LONG, S.C
473E
LONG, S.C
473E
LOTT, D.B
551
LOVETT, D.L
389
LOWORN, J. R
14
LOWE, C.J
527
LU, F.I
397
LU, Y
237
LUBCHENCO, J
537
LUKER, L A
150
LYNCH, M
460
LYNN, C.P
112
MABEE, P.M
642
MACDOUGALL-SHACKLETON, E. A
664
MACDOUGALL-SHACKLETON, S. A. . . .126, 664
MACHART, J.M
401
MACKEY, W.R
155
MADIN, L
137A
MAGANA, S.A
379
MAGINNISS, L A
547
MAGLIA, A.M
278
MAIN, R.P
89
MAJER, C
470
MALAGA-TRILLO, E
530
MALAKHOV, V.V
222
MALLATT, J
261D
MALMBERG, M
307
MANGIONE, A. M
181
MANIRE, C.A
457
MARDEN, J.H
356, 425
MARIKAWA, Y
254D, 473B
MARINELLI, R.L
1
MARINO, L
53, 254D
MARIS, R.C
206, 238
MARQUEZ, E
124
MARTIN, K. L M
277
MARTIN, L
51
MARTIN, V.J
686
MARTINDALE, M.Q
521, 525
MARTINEZ DEL RIO, C
541, 703
MARTINEZ, G.M
459C
MARTINEZ, M
300
MASLAKOVA, S.A
222
MAUPIN, J
137
MAURICIO, R
542
MAXWELL, L B
729
MAYER, L P
142
MAYS, C.E
433
MAYS, S.C
433
MCBRAYER, L.D
578
ABSTRACTS
Author
NISHIKAWA, K.C
NOBUSADA, Y
NOBUSADA, Y
NOE, A
NOLAN, JR., V
NOREKIAN, T.P
NORENBURG, J.L
NORIEGA, N.C
NORTON, S.F
NOWICKI, S
NULSEN, C
NYHOLM, S. V
NYSTROM, S.K
OAKLEY, T.H
OATES, A.C
ODE, P.J
OGAN, J.T
OLSON, J. M
OLSON, K. R
OLSSON, L
ONORATO, D.P
O'BRIEN, D.M
O'

Antarctic Marine Biology

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