- PersatuanGenetik Malaysia

POSTER PRESENTATIONS: ANIMAL GENETICS
PAO5
.
1
Sambar deer and their
G-banded karyotype of Rusa
ffilif".t"ean
lsmail ldrisl, Norbazlin Md. Marhaml, Saidi Moin2
2Department of Biomedicat Sciences
Department of Animat Science and
Universiti Putra Malaysia,43400 UPM Serdang, Selangor, Malaysia
ABSTRACT
The chromosomes of the Rusa (Cervus timorensis timorensis), Bornean sambar
(Cervus unicolor brookei) and their hybrids were studied using a lymphocytes culture
method and G-banding technique. All the hybrids had a diploid chromosome number of
2n=61, made up of 9 submetacentric autosomes, which were arranged in pairs in
descending order of size except for chromosome 1 (the largest submetacentric
autosomes in the complement). The sex chromosomes (X) in females were a pair of
acrocentric chromosomes being the largest among the acrocentric chromosomes. The Y
chromosome is a small submetacentric chromosome. The G-banding patterns were useful
in identifying the individual chromosomes between parental breeds and their hybrids. The
two species have identical G-band patterns and the hybrids may not suffer from the
pairing incompatibility during meiosis.
lntroduction
The hybridization process either intergenera or interspecies have potential benefit
to the farmed deer industries in terms of increased growth rate and proportion of muscle,
extended breeding season and an improved alignment to feed supply and annual energy
requirements. A number of hybridizations have been achieved, purposely or not, between
different genus such as red deer crossed with Pere david's deer or between different
species of deer of the same genus, such as red deer and sambar deer. The latter being
more frequent and may occur even in the wild. However, crosses between different genus
may produce sterile offspring, especially in males. Within the family Cervidae, several
hybridizations have proven to be successful, The crosses between sambar deer and red
deer, between red deer and axis deer and between red deer and sika deer, have been
reported (Delap, 1968; Whitehead, 1993; Muir et. al., 1997). Most of the successful
interspecific hybrids reported were the result of the presence of genetic compatibility
between parental lines. Parental species differing cytogenetically in chromosome
constitution could produce fertile hybrids. However, this is not always the case. Some
adult hybrids failed to reproduce. ln this case, the sterility could be due to the absence of
homology of the parental species. G-banding techniques may facilitate the identification of
homologous chromosomes and determine the possible relationship between the parental
lines. With that in mind, this paper presents the results for chromosome analysis of
Bornean Sambar crossed with Rusa hybrids.
Materials and methods
Lymphocytes were isolated from peripheral blood from two species of deer:
Sambar deer (Ceruus unicolor brookei) and Rusa deer (Ceruus timorensis timorensrd as
well as from their hybrids. The samples were collected at Pusat Pembiakan Ternakan
Sabrang, Sabah. Cells were cultivated in RPMI 1640 medium (Gibco@) supplemented with
20% tetal calf serum (FCS) (Gibco@) and penicillin-streptomycine (Sigma@;. Cells were
stimulated with pokeweed mitogen (PWM) (Sigma@) at a final concentration of 10 pl/ml
and cultivated at 37oC. Cells were harvested 72 hours after the onset of the cultivation.
Cells were treated with lprg/ml colcemid tor 1Yz hours prior to cell fixation. The cell
suspensions were swelled in hypotonic solution tor 20 minutes. Subsequently, the
suspension were fixed three times in 3:1 methanol:acetic acid before spread on wet slides
and air-dried at room temperature. G-banding for identification of individual chromosomes
was produced by using a standard procedure with slight modification. Following incubation
Proceedings of the dn Nationat Congress on Genetics, 12-14 May 2OO5, Kuala Lumput
PO STE H
PR
ESENTATI ON S : AN I M AL
G EN
ETICS
at 37oC for 3-5 days, slides were treated with 0.125o/" lrypsin in Dulbecco's Phosphate
buffered saline at 37oC for 2 minutes, rinsed in normal saline for 1 minute, air- dried and
stained in Giemsa solution in Sorenson's buffered, pH 6.8 for 5 minutes.
Results and Discussion
. The diploid chromosome number in the Bornean Sambar deer is 2n=62 and the
number of arm is 70. The autosomal set is composed of 4 pairs of metacentric to
submetacentric chromosomes and the remaining autosomes are all acrocentrics,
gradually decreasing in size. The X chromosome is the largest acrocentric in the
complement while the Y chromosome is the smallest submetacentric. G-banded
karyotypes of Sambar is shown in Figure 1. The karyotype was prepared from single
metaphase spreads with no overlapping chromosomes. The classification and
chromosome numbers were arranged according to Muir et al. (1997) where homologous
pairs of chromosomes were numbered in order of descending sizes as an aid to identify
the chromosomes in the hybrids. The G-band patterns enabled all of the homolog to be
distinguished despite their gradual decrease in size. The Rusa deer is characterized by
2n=60 and the fundamental number is similar to that of Bornean Sambar, FN=70. The
autosomal set is composed of one pair of large submetacentric and 4 pairs of medium
sized metacentric to submetacentric autosomes. The remaining 24 pairs are acrocentrics
with decreasing size (Figure 2). The X chromosome is an acrocentric, as was also
described in Bornean Sambar. The Y chromosome is a small submetacentric, differing
from that reported previously by Wang and Du, 1983)
The analysis of G-banded karyotype from the parental species has allowed a more
accurate assessment of the level of homology between their chromosomes and the
determination of type of karyotypic differences. As shown in Figures '1 and 2, Bornean
Sambar and Rusa deer have homologous G-banding patterns. Twenty-eight pairs of the
Bornean Sambar autosomes and sex chromosomes shared homology with 28 pairs of
autosomes and sex chromosomes of the Rusa deer with respect to the patterns of the Gbanded chromosomes. Their chromosome complement differ because the Rusa deer
carries one pair of submetacentrics autosome (pair 1) where the G-banding pattern is
homologous to two of the Bornean Sambar acrocentric chromosomes. Pair 1 of the Rusa
karyotype is significantly different in size and banding patterns from that of Bornean
Sambar. However in the hybrid karyotype this chromosome is a single pair in the
complement.
ln matching the banding patterns of the acrocentric chromosomes of the Bornean
Sambar with those of the submetacentric chromosomes of the Rusa deer, the equivalent
pairs of acrocentric chromosomes of the Sambar have been arranged to mirror those of
Rusa deer. The karyotype of the hybrids is shown in figure 3. lt has been arranged with
that of Rusa deer karyotype as a reference. Banded chromosomes from the Bornean
Sambar are aligned beside the chromosomes from Rusa. All, except three of the
autosomes were unpaired. The apparent pairing of the chromosomes in the hybrids
confirms their close similarity in the two parental species of deer, which was suggested by
their highly similar banding patterns,
Proceedings of the dh National Congress on Genetics, 12-14 May 2005, Kuala Lumpur
138
POSTER PRESENTATIONS: ANIMAL GENETICS
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References
Delap, P. (1968). Hybridization of Red deer and sika deer in the Lake District. J. Zool.
Lond. 156:532-533
Muir, P. D; Semiadi, G; Asher, G.W; Broad, T. E; Tate, M. L. and Barry, T. N. (1997).
Sambar deer (C.unicolor) x Red deer (C. elaphus) interspecies hybrids. J. Hered. 88: 366372
Whitehead, G. K. (1993). The Whitehead encyclopedia of deer. Swanhill Press. U. K. pp.
409-410
Wand, Z. and Du, D. R. (1983). Karyotype of four species of deer. Acta Zool. Sing.29:
214-222
Proceedings of the dh National Congress on Genetics, 12-14 May 2005, Kuala
Lumpur
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