nordic winter school on astrobiology1 synthesis of nucleotides in space natalia gontareva laboratory...

Nordic winter school on Astrobiology

1

Synthesis of Synthesis of nucleotides in nucleotides in

spacespace

Natalia GontarevaNatalia Gontareva

Laboratory of Exobiology, Laboratory of Exobiology, Institute of CytologyInstitute of Cytology

St Petersburg, Russia St Petersburg, Russia

[email protected]@mail.cytspb.rssi.ru


2

BackgroundBackgroundTwo groups of life origin theories:

Terrestrial origin.Extraterrestrial origin. Planets are not isolated in

terms of biology and exchange of organic material could occur between them.Possibility for cosmic delivery of basic molecules:

Amount of micrometeorites (from 50 to 500 m in size) – 50-100 tons daily.

Meteorite flux - 0.03 tons per day. Heavy bombardment in early Earth - 1000 times

more than present amount. High percentage of organic components in

carbonaceous chondritesAvailability of different space energy sourcesPresence of organics in space (molecular

hydrogen, water, CO, HCN, etc.)


3

Organic molecules in spaceOrganic molecules in space


4

Potential sites for organic molecules formation as the result of prebiotic chemical processes.

Localisation Temperature, К Particles concentration

, cm-3

Sources of energy

1. Interstellar clouds

Cold 10 103

Cosmic rays

Hot core 50 105

Cosmic rays

2. Protosolar nebula

External part 60

109 Solar wind

Internal part 600 1012

Solar wind

3. Comets Surface20 or 100

1019 Stellar UV and cosmic rays

Core20 or 500

1019 26Al

4. Comets after capture by

planets

Surface 2-200 1019 Solar vacuum ultraviolet

5. Primordial Earth

Hydrosphere 330 1019 Solar ultraviolet

Lower atmosphere 330

1016 Lightning


5

Hydrogen Cyanide (HCN) As

the Source for Prebiotic Synthesis

1. hydrogen cyanide polymers may be present on different bodies of the outer solar system (comets, Titan)

2. Hydrogen cyanide polymers deposided by comets may have established protein-nucleic acid life on Earth

3. Chemical precursor of both purines and pyrimidines, source for prebiotic synthesis


6

Sugars in spaceSugars in space Ethylene glycol was discovered recently in a Ethylene glycol was discovered recently in a

massive interstellar cloud of dust and gas massive interstellar cloud of dust and gas near the center of the Milky Way Galaxy. near the center of the Milky Way Galaxy.

Scientists used the National Science Scientists used the National Science Foundation's (NSF) 12 Meter Radio Telescope Foundation's (NSF) 12 Meter Radio Telescope

to detect this organic molecule.to detect this organic molecule. Ethylene glycol (a 10-atom molecule made up Ethylene glycol (a 10-atom molecule made up

of carbon, hydrogen, and oxygen) is one of of carbon, hydrogen, and oxygen) is one of the five largest molecules ever discovered in the five largest molecules ever discovered in

space. space. It also is a chemically reduced form of 8-atom It also is a chemically reduced form of 8-atom

glycolaldehyde, the simplest member of the glycolaldehyde, the simplest member of the sugar family. sugar family.

It can be produced from glycolaldehyde by It can be produced from glycolaldehyde by the addition of two hydrogen atoms. Both the addition of two hydrogen atoms. Both

molecules have now been detected in space molecules have now been detected in space by this team.by this team.


7

Molecular structure of Molecular structure of nucleotidesnucleotides


8

Nucleotides base pairingNucleotides base pairing


9

Scheme of nucleotide synthesisScheme of nucleotide synthesis

•5'-mononucleotides are the prevailing derivatives synthesized of certain nucleosides •3’, 2’ and cyclic monophosphates present in similar quantities•Di-and triphosphates also present in the reaction mixture

OBaseHOCH2

O OH

OH

P

O

OBaseHOCH2

OHP

O

O O

OBaseHOCH2

OHP

O

O O O-

O-


10

Possible scenario of life transfer Possible scenario of life transfer in the Solar systemin the Solar system

From Horneck


11

EEnergy sourcesnergy sources in space in space::

Solar electromagnetic radiation from 2*10-12 to 102 m

Solar corpuscular radiation (solar wind – low and high energy solar particle events) – predominantly protons with 10% helium ions and 1% heavy ions and electrons

Cosmic galaxy radiation originates from outside our solar system - 87% protons (hydrogen nuclei), 12% alpha particles (helium nuclei), 1.3% heavy ions (fully ionized ions of all elements from protones to uranium with Z 92), 1% electrons.

Extreme temperatures, from 4K and more

Earth orbit energy: solar radiation (1360 W*m-2), Earth albedo (480 W m-2); terrestrial radiation (230 W*m-2).


12

Solar electromagnetic Solar electromagnetic radiationradiation

Driving force for many biological reactions because of its Driving force for many biological reactions because of its abundanceh. Approximate intensity of UVabundanceh. Approximate intensity of UV254254 radiation in radiation in the lower Martian atmosphere level equals to 10the lower Martian atmosphere level equals to 1055 J m J m-2-2 h h-1-1..

The UV flux: near (300-400 nm) and far (200-300 nm) The UV flux: near (300-400 nm) and far (200-300 nm) Short-wave UVC (less than 280 nm) must be considered Short-wave UVC (less than 280 nm) must be considered

in any extraterrestrial situation when looking for the in any extraterrestrial situation when looking for the possibility of sustaining life.possibility of sustaining life.

Radiation at the wavelength of 254 nm is capable of Radiation at the wavelength of 254 nm is capable of interacting directly with molecular structures. UV radiation interacting directly with molecular structures. UV radiation causes temporary or permanent alterations that result causes temporary or permanent alterations that result from photochemical reactions of UV 254 with different from photochemical reactions of UV 254 with different biological target molecules, the so-called chromophores. biological target molecules, the so-called chromophores.

The response of different biological structures to UV The response of different biological structures to UV exposure is unique. It can be altered by surface exposure is unique. It can be altered by surface composition of space bodies, so the mineral component of composition of space bodies, so the mineral component of environment should not be underestimated.environment should not be underestimated.


13

The The contributioncontribution of short UV to the synthesis of of short UV to the synthesis of nucleotides in different radiation conditionsnucleotides in different radiation conditions

12

34

56

Thymidine

Uridine

Adenosine

0.8

0.27

2.1

0.8

1.45

0.97

0.37

0.110.3

0.08

0.6

0.240.0250.006

0.55

0.3

0.0320.019

0

0.5

1

1.5

2

2.5

Tot

al y

ield

of n

ucle

otid

es, %

fr

om in

itia

l am

ount

Flight data (MIR)

UV 145 UV 254


14

Absorption spectra of DNA, RNA and nucleobasesAbsorption spectra of DNA, RNA and nucleobases

UV UV 254254: The : The absorbing parts absorbing parts of DNA are the of DNA are the bases.There is bases.There is absorption absorption maximum at maximum at 260 nm and a 260 nm and a rapid decline rapid decline towards longer towards longer wavelengths.wavelengths.

UV UV 145145: : Absorption Absorption increases due increases due to phosphates, to phosphates, riboses and riboses and ribophosphatesribophosphates

Fig. 1 – from top to bottom: 1 - DNA spectrum, nucleobases: 2 – Gua, 3 – Ade, 4 – Thy, 5 – Cyt. a and b curves correspond to different concentrations

Fig. 2 – from top to bottom: 1 - RNA spectrum, nucleobases: 2 – Gua, 3 – Ade, 4 – Ura, 5 - Cyt

G

A

T

C

G

A

U

C


15

Possible sites of photocatalytic processes Possible sites of photocatalytic processes in interstellar medium (ISM)in interstellar medium (ISM)

ISM – the space between stars consisting of gas ISM – the space between stars consisting of gas and dust.and dust.

Most probable source of organic molecules – non-Most probable source of organic molecules – non-equilibrium processes driven by photons, cosmic equilibrium processes driven by photons, cosmic rays, shock waves and solid bodies’ collisionsrays, shock waves and solid bodies’ collisions

The dense cold phase of ISM host icy dust grains The dense cold phase of ISM host icy dust grains – important chemical catalyst during its life cycle– important chemical catalyst during its life cycle

Such particles consist of mineral core composed Such particles consist of mineral core composed by silicate or olivine admixed with metal sulfides by silicate or olivine admixed with metal sulfides and oxides, with the water-icy envelope and oxides, with the water-icy envelope containing organic moleculescontaining organic molecules

Organic molecules in the ISM evolve and become Organic molecules in the ISM evolve and become later incorporated in solar system material later incorporated in solar system material (comets and meteorites)(comets and meteorites)


16

UV-irradiation of the molecules adsorbed by mineral matrix of the interstellar dust

• As dust grains with ice mantles are transported to warm, dense, and active protostellar regions, the ultraviolet irradiation may become important and alter the grain composition.

• Spectral selectivity of photocatalyst: short-wave photons are totally adsorbed by a thin outer layer, whereas the photons of longer wavelength can penetrate into much deeper layers

• Photoadsorbtion and photocatalytic memory: the irradiation of some solids creates active photocatalytic centers. These are lattice defects with a trapped photocarrier, electron or a hole. Pre-irradiated particle stays in metha-stable state for a long time

• Excitation energy “concerved” within the solid matrix is released to activate chemical reaction at its surface.

• This phenomenon can compensate the effects of low reagents concentration and temperature


17

Basalt mineral Basalt mineral compositioncomposition


18

LimoniteLimonite

limonite Class: Oxide/HydroxidesColor(s): yellow, brown, glassy,Hardness: 4-5.5SpecGrav: 2.7-4.3Fracture: conchoidal, unevenCrystal: Amorphous, fibrous, botryoidal - limonite is not really a mineral but rather a mixture of hydrated goethite.Envronment: a mixture of secondary iron minerals, alteration product of iron ores, especially sulfidesAssociation: pyrite, hematite, prolusite, psilomelane, calcite, quartz


19

Interaction of montmorillonite (Interaction of montmorillonite ((Na,K,Ca)(Аl,Fe,Мg)(Na,K,Ca)(Аl,Fe,Мg)[(Si,Al)[(Si,Al)44OO1010](OH)](OH)22*nH*nH22O)O) catalytic sites and organic catalytic sites and organic

moleculesmolecules

а – The binding of monomers. The catalysis is ascribed to the orientation of monomers and the acidity of the surface (electrostatic interaction of the protonated base and negatively charged surface)

в – Activation of functional groups of monomers. Adsorption on the clay favors reaction between monomers.

с – The release of oligomers from the mineral surface. Final reaction involves two neighbor activated molecules.

From Ferris


20

Molecular cloudMolecular cloudAAzo-dyes based supermolecules zo-dyes based supermolecules

of fullerene of fullerene (ErSc(ErSc22N@[CHN@[CH22CHCH22NH]CNH]C8080, figure , figure

on left) and a biliverdin (figure on left) and a biliverdin (figure on right) derivatives.on right) derivatives.

Such a molecular cloud may absorb magnetic and light energy from planets and stars, move in the Space by using light wind collecting all necessary molecules for the growing and multiplication.

From Tamulis


21

The aims of MIR space experiments were:

To study the contribution of lunar soil to the processes of prebiotic solid phase synthesis of peptides and nucleotides

To evaluate the role of space energy sources in this synthesis

To test the amount of initial substances’ decay after long-duration space flight

To model the surface of small cosmic body

The aims of laboratory experiments were:

To perform control experiments proving flight data

To study the influence of extraterrestrial minerals over solid phase synthesis of peptides and nucleotides

To evaluate the effect of different energy sources present in cosmic environment


22

Unique property of the Unique property of the experiments at the orbit: experiments at the orbit:

Modeling of the early Earth and space bodies radiation environment

Approximation of the continuos space flight:

1)Energy flux in diffused interstellar medium (photons more than 6 eV) - 108 photon*cm-2*s-1.

2)At the orbit – intensity of solar radiation for 6 eV photons is 9*1015 photon*cm-2*s-1. Hence the amount of radiation gained at the orbit during two weeks flight is equal to the 2*106 years long interstellar flight.


23

Components in carbonaceous chondrites (in %)*.

1) Allende meteorite (CV3)

2) Murchison meteorite powder ( CM2)

3) Lunar soil: significant micrometeoritic component (similar to C1 chondrites).

ComponentComponent CICI CMCM COCO CVCV

MatrixMatrix 9999 4848 3434 4242

Isolated Isolated high-high-

temperature temperature beadsbeads

11 2222 88 22

ChondresChondres 00 22 4040 4444

Olivine Olivine aggregatesaggregates

00 1818 1111 11

Ca-Ti-Al Ca-Ti-Al aggregatesaggregates

00 tracestraces 22 44

*(Rosanov, 1996)

nordic winter school on astrobiology1 synthesis of nucleotides in space natalia gontareva laboratory...

Documents