Segunda Escuela de Posgrado Iberoamericana de Astrobiología

Darwin, Oparin y la sopa primitiva: síntesis prebiótica y el origen de la vida

Antonio Lazcano AraujoFacultad de Ciencias, UNAM

MEXICOE-mail: alar@correo.unam.mx

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

3.54.04.5 3.0

fossil records cooling of the Earthimpact frustrations

The age of the Earth (billions of years ago)

?

3.44.5 4.2 4.2 - 4.0 ~ 4.0 ~3.5 ~2.8 - 2.5

formation of Earth

stable hydrosphere

prebiotic chemistry

pre-RNA worlds

RNA world

DNA/RNA/protein world

oxygen-rich atmosphere

origin of life

RNA/protein world

LCA Apex Formation microstructures

sulfate reducers, anoxygenic phototrophs, methanogens (?)

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

1) Proust 1807HCN polímero + adenina (?)

2) Wöhler 1828NH4 NCO urea

3) Strecker 1850CH3 CHO + NH3 + HCN alanina

4) Butlerow 1861HCHO azúcares

OH-

OH-

Síntesis abiótica de compuestos orgánicos en el siglo XIX

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

Reduction of carbon dioxide in aqueous solutions by ionizing radiations

Delete | Reply | Reply to all | Forward | Bounce | Resume | Save as Back to HistoricalDate Sat, 4 Jun 2005 16:44:15 -0700From "Andrew A. Benson" <abenson@ucsd.edu>To alar@correo.unam.mxSubject Nopales, againPartsMessage SourceSo 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 Nopalitosevery 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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k 25 C

C + 2H2 -> CH4 8 x 108

N2 + 3H2 -> NH3 7 x 105

O2 + 2H2 -> H2 O 4 x 1041

CO2 + 6H2 -> CH4 + 2H2 O 6 x 1015

S + H2 -> H2 S 7 x 1021

k = k (T)

Harold C. Urey’s primitive terrestrial atmosphere

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

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; 9- D,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.

Note: identificationswere confirmed by LC-FD/ToF-MS

Types of planetary anoxic atmospheres

Reducing:CH4 , NH3 , N2 , H2 O, H2CO2 , N2 , H2 O, H2CO2 , H2 , H2 O

Neutral: CO2 , N2 , H2 O

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, hydrolyzedwith 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

CH4 , NH3 , H2 , H2 O (Miller, 1953)

CO2 , N2 , H2 O (Cleaves, Chalmers, Lazcano, Miller & Bada, 2008)

1953: Annus mirabilis

Watson & CrickDNA double helix

Sanger & ThompsonSequencing of insulin

Prebiotic synthesis oforganic compounds

Stanley L. Miller

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?

1.Amino acids from Strecker synthesis

2. Purines from HCN polymerization

3. Pyrimidines from cyanoacetylene & urea

4. Sugars from HCHO polymerization

Prebiotic syntheses that work

John Sutherland’s synthesis of pyrimidine ribonucleotides

Szostak 2009

Abiotic synthesis under hydrothermal vent conditions

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-bondsiii) synthesis of ammonia from nitrogen and hydrogen

FeS + H2 S -> FeS2 + H2FeS + H2S = FeS2 + H2

1) reducing/anoxic atmosphere/ocean environments

2) input in comets and meteorites

3) high-temperature vent chemistry

Prebiotic sources of organic compounds:

Miller & Lazcano 2002

Prebiotic syntheses are quite robust!

organics from space

Bada & Lazcano (2002) Science 296: 1982

Base-pairing is for free!

Orgel, 2004

alkenes acid conditions alcohols

Fe3 C + H2 O alkanes + alkenes1)

2)

From hydrocarbons to amphiphilic compounds

hydrophobic

hydrophilic

Putting everything together…

Mansy et al (2008) Nature 454: 122

a wide array of organic compounds of biochemical significance

many inorganic & organic catalysts

purines & pyrimidines(the potential for template-directed polymerizations)

membrane-forming compounds

The evidence suggests that prior to the origin of life the primitive Earth already had:

DNA

DNA RNA protein

replicative polymers+

catalytic polymers

Can coexistence breed a code?

catalytic polymers

replicative polymers

DNA

DNA RNA protein

replicative polymers+

catalytic polymers

Can coexistence breed a code?

catalytic polymers

replicative polymers

DNA

DNA RNA 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)

Bada & Lazcano (2003) Science 300: 745

1924 -

1929 1961

1953

1900

1861

1850

1828

1800 2000

replicative RNA

catalytic RNA

The RNA world hypothesis

plus many other things: amino acids, oligopeptides, lipids, sugars, clays, metallic cations, etc!

RNA world

RNA + proteins

DNA + RNA + proteins

The Aztec pyramid model of the RNA world

la existencia de moléculas de RNA autorreplicativas;

ribozimas con capacidad de interaccionar con aminoácidos;

ribozimas con actividad de peptidil-transferasa;

rutas metabólicas mediadas por ribozimas o, bien,

síntesis prebiótica de ribonucleótidos e intermediariosmetabólicos con residuos de ribonucleótidos.

Si de verdad existió el Mundo de RNA, se puedenhacer una serie de predicciones:

The robustness of the RNA world hypothesis

RNA ribosomal catalyzes peptide-bond formation (Moore & Steitz, 2002)

Self-sustained replication of RNA molecules (Lincoln & Joyce, 2009)

Ribozymes catalyze metabolic reactions (Fusz et al, 2005, Chem. Biol. 12: 941)

Mindell, D. P. (2006) The Evolving World: evolution in everyday life(Harvard University Press, Cambridge)

Evolución

de virus patógenos

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

DNA, RNA & proteins

?

RNA + proteins

RNA world

RNA viruses

DNA viruses

retroviruses

Are viruses primordial entities?

?

?

Cells with DNA, RNA & proteins

RNA & protein biosynthesis

RNA world

?

life

tornadoes

milk

droplets

membrane

bilayers

liposomes

and

micelles

viruses

fire

formose

reaction

Junta de Gobierno

SELF-ORGANIZATION

REPLICATION

AUTOPOIESIS

cyanobacteria

prions

swarming

capsidassembly

NATURAL SELECTIONpopulations

ofRNA molecules

Archaea

Eucarya

Bacteria

LCA

hot origin

of

life?

Catalonian

Spanish Rumanian

FrenchProvençal

Italian

LATIN

Catalonian

Spanish Rumanian

FrenchProvençal

Italian

ancient…but certainlynot primitive

Archaea

Eucarya

Bacteria

LCA

Hyperthermophiles are ancient, not primitive --as shown by the way they replicate, express and regulate their genetic information