sintesis abiotica

Segunda Escuela de Posgrado Iberoamericana de Astrobiología
Darwin, Oparin y la sopa primitiva: síntesis
prebiótica y el origen de la vida
Antonio Lazcano Araujo
Facultad de Ciencias, UNAM
MEXICO
E-mail: [email protected]
Montevideo 2009
Intellectual & scientific genealogies
Charles Darwin
Kliment A. Tymiriazev
Alexandr I. Oparin
Closing in on a time frame for the origin
of life on Earth
cooling of the Earth
impact frustrations
4.5
4.0
?
fossil records
3.5
3.0
The age of the Earth (billions of years ago)
pre-RNA
worlds
RNA
world
RNA/protein
world
DNA/RNA/protein
world
sulfate reducers, anoxygenic phototrophs,
methanogens (?)
formation of
stable
Earth
hydrosphere
4.5
4.2
prebiotic
chemistry
origin of
life
4.2 - 4.0
~ 4.0
LCA
Apex Formation
microstructures
~3.5
oxygen-rich
atmosphere
3.4
~2.8 - 2.5
Becerra, Delaye, Islas & Lazcano (2007) Annu. Rev. Ecol. Evol. Syst. 38: 361
Bada & Lazcano, 2003
A. I. Oparin y sus hermanos
J. B. S. Haldane
Heterotrophic origin of life
reducing atmosphere
synthesis of organic compounds
& formation of the primitive soup
coacervates
primordial heterotrophs
Síntesis abiótica de compuestos orgánicos en el siglo XIX
1) Proust 1807
HCN OH- polímero + adenina (?)
2) Wöhler 1828
NH4NCO
urea
3) Strecker 1850
CH3CHO + NH3 + HCN
4) Butlerow 1861
OHHCHO
azúcares
alanina
Reduction of carbon dioxide in aqueous solutions
by ionizing radiations
Garrison et al (1951) Science 114: 416
Reduction of carbon dioxide in aqueous solutions
by ionizing radiations
Garrison, W.M., Morrison, D. C., Hamilton, J. G., Benson,
A. A. and Calvin, M. (1951) Science 114: 416
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Sat, 4 Jun 2005 16:44:15 -0700
"Andrew A. Benson" <[email protected]>
[email protected]
Nopales, again
Message Source
So many thanks for your delightful and informative message, Antonio.
I am so fortunate to learn of your familiarity with Nopales and their
effects.
Be assured, though, that obtaining Nopal and Nopalitos in the stores
is not a problem. Dee brings home several P.E. bags of Nopalitos
every time she goes to El Cajon for her needlepoint classes. They
are grown in Valley Center not far from Escondido.
I find many articles on the Web, some of them clinical. But none of
them revealed any physiological or biochemical mechanisms.
For half a year I was buying Nopalitos in glass jars; but the fresh
ones are better.
My colleague in Paris is interested and curious. He is in the top
council of Acad. Nationale de Medecine and hopes to understand how
they lower blood clucose levels.
Greetings from Dee, too,
Andy
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Harold C. Urey’s primitive terrestrial atmosphere
k 25 C
C + 2H2 -> CH4
8 x 108
N2 + 3H2 -> NH3
7 x 105
O2 + 2H2 -> H2O
4 x 1041
CO2 + 6H2 -> CH4 + 2H2O
6 x 1015
S +
7 x 1021
H2 -> H2S
k = k (T)
Urey (1952) PNAS 38: 351
A principios de los 1950’s, se creía que:
a) Los organismos se podían clasificar en tres grandes reinos (según
Haeckel): microbios, plantas y animales;
b) Los fósiles más antiguos tenían 600 millones de años;
c) El origen de la biósfera había sido un proceso lento de miles de
millones de años;
d) Los microbios eran sobre todo gérmenes patógenos;
e) Las proteínas jugaban un papel central en la herencia;
f)
Los sistemas planetarios eran muy raros; y
g) La exploración del espacio era muy poco probable
El experimento de Miller de 1953
Mount Redoubt, Alaska, March 22, 2009
Note: identifications
were confirmed by
LC-FD/ToF-MS
Representative cumulative HPLC chromatograms for: (A) classic apparatus design; (B) volcanic
apparatus design; (C) silent discharge apparatus design; and (D) an amino acid standard; peak
identifications 1-D,L-Asp; 2-L,D-Glu; 3-D,L-Ser; 4-Gly; 5-β-Ala; 6-γABA; 7-D,L-β-AIB; 8-D,L-Ala; 9D,L-β-ABA; 10-α-AIB; 11-D,L-α-ABA; 12-D,L-Isovaline; 13-D,L-Norleucine. (* are unidentified
peaks); and (E) a procedural blank.
Types of planetary anoxic atmospheres
Reducing:CH4, NH3, N2, H2O, H2
CO2, N2, H2O, H2
CO2, H2, H2O
Neutral: CO2, N2, H2O
Prebiotic organic synthesis in neutral planetary atmospheres
I. amino acid standard
II.
CO2/N2 not sparked
III.
CO2/N2 + CaCO3, sparked,
hydrolyzed with no
ascorbate
IV. CO2/N2 sparked, hydrolyzed
with no ascorbate
V. CO2/N2 + CaCO3, sparked,
hydrolyzed, ascorbate
(1) DL aspartic acid; (2) DL glutamic acid; (3) DL serine; (4) glycine; (5)
β-alanine; (6) DL alanine; (7) α-amino isobutyric acid; (8) DL norleucine
(internal standard)
Prebiotic synthesis under reducing and neutral conditions
CO2, N2, H2O
(Cleaves, Chalmers, Lazcano, Miller & Bada, 2008)
CH4, NH3, H2, H2O
(Miller, 1953)
1953: Annus mirabilis
Watson & Crick
DNA double helix
Sanger & Thompson
Sequencing of insulin
Stanley L. Miller
Prebiotic synthesis of
organic compounds
During the first twenty years following the Miller
experiment, attempts to understand the origin of life were
shaped to a considerable extent,
1) scientifically,
* by the fact that since the late 1940´s, evolutionary biology
became an established field of research;
* the unraveling of the details of DNA replication & protein
biosynthesis; and
* the development of space programs
2) in socio-political terms, by the atmosphere created by Cold
War tensions.
Prebiotic synthesis of adenine*
a) Oró, 1960; b) Ferris & Orgel, 1966
* Did nucleic acids form in the prebiotic soup?
Prebiotic syntheses that work
1.Amino acids from Strecker synthesis
2. Purines from HCN polymerization
3. Pyrimidines from cyanoacetylene & urea
4. Sugars from HCHO polymerization
John Sutherland’s synthesis of pyrimidine ribonucleotides
Szostak 2009
Abiotic synthesis under hydrothermal vent conditions
FeS + H2S = FeS2 + H2
FeS + H2S -> FeS2 + H2
Mixtures of nickel- and iron sulfides, as well the formation of pyrite
(FeS2) can catalize the:
i) reduction of carbon monoxide (but not of CO2)
ii) formation of organic compounds and peptide-bonds
iii) synthesis of ammonia from nitrogen and hydrogen
Prebiotic sources of organic
compounds:
1) reducing/anoxic atmosphere/ocean
environments
2) input in comets and meteorites
3) high-temperature vent chemistry
Prebiotic syntheses are quite robust!
Miller & Lazcano 2002
organics from
space
Bada & Lazcano (2002) Science 296: 1982
Base-pairing is for free!
Orgel, 2004
From hydrocarbons to amphiphilic compounds
1) Fe3C + H2O
2) alkenes
acid conditions
alkanes + alkenes
alcohols
hydrophobic
hydrophilic
Putting everything together…
Mansy et al (2008) Nature 454: 122
The evidence suggests that prior to the origin
of life the primitive Earth already had:
a wide array of organic compounds of biochemical
significance
many inorganic & organic catalysts
purines & pyrimidines
(the potential for template-directed polymerizations)
membrane-forming compounds
DNA
DNA
RNA
protein
Can coexistence breed a code?
DNA
DNA
RNA
replicative polymers
catalytic polymers
replicative polymers
+
catalytic polymers
protein
Can coexistence breed a code?
DNA
DNA
RNA
replicative polymers
catalytic polymers
replicative polymers
+
catalytic polymers
protein
Mr. Michael Jackson’s putative child:
is Lamarckian inheritance feasible?
During early evolutionary stages RNA molecules played a
major role in heredity and metabolism
Woese (1967)
Orgel (1968) & Crick (1968)
1800
1900
1828
1861
1850
2000
1924 - 1929
1961
1953
Bada & Lazcano (2003) Science 300: 745
The RNA world hypothesis
replicative RNA
catalytic RNA
plus many other things: amino acids, oligopeptides,
lipids, sugars, clays, metallic cations, etc!
The Aztec pyramid model of the RNA world
DNA + RNA + proteins
RNA + proteins
RNA world
Si de verdad existió el Mundo de RNA, se pueden
hacer una serie de predicciones:
la existencia de moléculas de RNA autorreplicativas;
ribozimas
aminoácidos;
con
capacidad
de
interaccionar
con
ribozimas con actividad de peptidil-transferasa;
rutas metabólicas mediadas por ribozimas o, bien,
síntesis prebiótica de ribonucleótidos e intermediarios
metabólicos con residuos de ribonucleótidos.
The robustness of the RNA world hypothesis
Self-sustained replication of RNA
molecules (Lincoln & Joyce, 2009)
RNA ribosomal catalyzes peptide-bond
formation (Moore & Steitz, 2002)
Ribozymes catalyze metabolic reactions (Fusz et al, 2005, Chem. Biol. 12: 941)
Evolución de virus patógenos
Mindell, D. P. (2006) The Evolving World: evolution in everyday life
(Harvard University Press, Cambridge)
1) Los virus no están vivos (tampoco están
muertos)
2) Los virus ni fueron los primeros seres vivos ni
son primitivos
3) Hay virus en todos los reinos biológicos
4) La mayoría de los virus no son patógenos
Un sistema simple no es necesariamente primitivo
Are viruses primordial entities?
DNA viruses
DNA, RNA & proteins
RNA + proteins
RNA world
?
?
retroviruses
?
RNA viruses
Cells with DNA, RNA & proteins
RNA & protein biosynthesis
RNA world
?
populations of
RNA molecules
NATURAL SELECTION
REPLICATION
liposomes and
micelles
capsid
assembly
viruses
prions
life
fire
membrane
bilayers
tornadoes
formose
reaction
swarming
milk droplets
cyanobacteria
SELF-ORGANIZATION
Junta de
Gobierno
AUTOPOIESIS
Eucarya
Archaea
Bacteria
LCA
hot origin of life?
Spanish
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Provençal
French
Rumanian
Italian
Provençal French
Spanish
Rumanian
Italian
Catalonian
LATIN
ancient…but certainly
not primitive
Eucarya
Archaea
Bacteria
LCA
Hyperthermophiles are ancient, not primitive --as shown by
the way they replicate, express and regulate their genetic
information