First Steps in the Origin of Life in the Universe

EuroConference

Sixth Trieste Conference on Chemical Evolution

Posters

Persistence of living foraminifera in the Antarctic sea ice inferred from a study of an outer slope core (Ross Sea continental margin).

Rosalba Bonaccorsi (1,2) & Romana Melis (1)
(1) Dip. Scienze Geologiche, Ambientali e Marine (DiSGAM), University of Trieste, v. E. Weiss 2, 34127 Trieste ­ Italy
(2) Lamont-Doherty Earth Observatory, Rt. 9W, Palisades, 10964 NY - USA

The occurrence of living planktonic foraminifera such as Neogloboquadrina pachyderma (N. pachy.)-left coiling- in Southern Ocean sea ice has been emphasized by several authors [1-5]. Indeed, they represent one of the most well recognized examples of marine life persistence in extreme polar environments (i.e., frazil ice with interstitial veins of hyper-saline water colder than -2­-15 C).
This work aims to i) illustrate how to constrain such persistence by using micropalaeontological observation, radiocarbon dating and stable isotope measurements as classically applied to paleoceanography and paleoclimate research ([6, 7], ii) Integrate those different approaches into the interdisciplinary new field of astrobiology. In fact, investigating life in extreme marine environments is an essential step to explore the possibilities and limits of life in other worlds' ecosystems [8, 12-13].
The fundamental questions are: Can the sedimentary record be used as proxy for the persistence of living foraminifera in sea-ice from past? Can they record rapid environmental changes which have affected their habitat? The possibility of constraining such proxies depends on: 1) The accumulation and preservation of biogenic carbonates in sediment, 2) A well-known natural history of the investigated species. 3) A paleo environment model for pre-depositional mechanisms responsible for such accumulation.
We present here well-preserved sedimentary records extracted from a deep-sea core to examine the possibility of the persistence of living N. pachy colonies in sea­ice during late Quaternary pulses of the Ross ice shelf (RIS).
ANTA95-89C, a 404-cm length gravity core, was collected in the Ross Sea continental margin (74 29.100'S ­ 175 34.059'W-2058 m depth) in the framework of PNRA (Programma Nazionale di Ricerche in Antartide). Its two units, A and B, include 32 massive to laminated lithofacies (Levels 1 to 32) previously interpreted as pulses of the Antarctic ice sheet during glacials/interglacials [9]. Well-preserved specimens of N. pachy were selected for 14C AMS dating from Level 12, a 22 cm-thick stratified diamicton (gravelly-sand lithofacies) which is almost entirel dominated by this species. Depositional ages are ~ 28,000 (Level 12c at 238 cm depth) and 17,000 (Level 12a at 217 cm depth) yr BP., which bracket the Last Glacial Maximum (LGM). The recovered planktonic assemblage is likely autthonous since a) no association with continental drifts or turbidity flows is evident, b) both juveniles and adult forms are present, and c) they are well preserved (not oxidized or fragmented by dissolution). During the present day Antarctic winter, living colonies of N. pachy inhabit sub glacial ice cavities and pores (frazil ice) and, as a result they are protected by predators and can feed on other microorganisms (i.e., bacteria, diatoms) physiologically adapted to very cold and extreme high-salinity environments. During spring ice melting, associated with rapid seasonal change in their ecosystem, they are released to the water column exploiting the summer feeding resources and continuing their life cycle. This suggests that in sediments from Level 12, high concentrations of N. pachy tests may be related to paleoclimate changes, such as variation in the length and intensity of freeze-thaw cycle both affecting sea ice and water column. The natural history of N. pachy can help to constrain pre-depositional mechanisms responsible for their accumulation and preservation. For instance, sea ice species associated with abundant Iceberg Rafted Detritus (IBRD) could be another proxy for climate induced melting of massive but unstable sea-ice with floating masses [10, 11] affecting extended portions of the Ross Sea continental margin. Additionally, climate induced rapid burial rates and/or lowering of the CCD likely prevented dissolution as testified by similar biogenic layers recognized in other sites [6] and clearly demonstrate that biogenic polar carbonate conservation in deep sea sediment is possible.
In conclusion, biogenic lithofacies associated with floating ice masses can not only record drastic changes in the sedimentary environment, but may also be proxies for the abundance of life capable of exploiting a wide range of extreme conditions. N. pachy offers an additional example that similar life-forms might be (or were) also present on other planets where polar ocean ice cover occurs or occurred (i.e., the Jupiter's moon Europa and oceans one surrounding the Martian's polar caps).This multidisciplinary approach can contribute to some of the investigation items (i.e., questions, goals, and objectives) from the official astrobiology "roadmap" [12].
Finally, one basic but still controversial question which can be further addressed is: Can such an approach be useful for extracting evidence of past marine life-forms in sediment samples returned from other planets? Or, do we additional information? The answer to such a question depends on how many refined biomarker (i.e., morphological, chemical, isotopic and biomineralogical) will be developed by common efforts inside a broad scientific community front [13].

References:
[1] Palmisano and Garrison Antarctic Microbiology, pp 167-218, 1993; [2] Dieckmann et al., J. of Foraminiferal Res. 21, 181-194, 1991; [3] Spindler, et al., pp129-135, in: Antarctic Ecosystem, Ecological change and conservation, 1990; [4] Spindler and Dieckmann, Polar Biology 5, 185-191, 1986; [5] Lipps and Krebbs, J. of Foraminiferal Res. 4, 80-85, 1974;
[6] Quaia and Cespuglio, T. Antartica Rep.,(in Press); [7] Charles et al., Earth Planet. Sci. Lett. 142, 12-27, 1996; [8] Irion, Science 288: 603-605, 2000; [9] Bonaccorsi et al., T. Antarctica Rep. (in Press); [10] Anderson et al., in: Glacial Marine Sedimentation, pp261, 1991;
[11] Kellogg and Kellogg, Palaeogeogr., Palaeoclimatol., Palaeoecol., 67, 51-74, 1988;
[12] AAVV-Astrobiology Roadmap Workshop, NASA Ames Research Center, July 20-22 1998; [13] Kerridge, J.F., In; First Astrobiology Science Conference, April 3-5, 2000 NASA Ames Research Center, Abstract;

A UNIVERSAL BIOSIGNATURE: `GENERALIZED CHLOROPHYLS'

JEAN SCHNEIDER,

Paris Observatory 92195 Meudon,
France

ANTOINE LABEYRIE

College de France.
Place M. Berthelot 75005 Paris,
France

FIORELLA COLIOLO (#)

IRSPS, Universita' d'Annunzio
Viale Pindaro 42
65127 Pescara Italy
Fax. +39-085-4537545
e-mail: coliolo@mesioc.obspm.fr

A broad class of `living organisms' take their energy from the light of the parent star of their home planet. Whatever the physiological details are (including production or not of oxygen), this photosynthesis of organic material must result in the `pumping' of photons in the stellar spectrum. It must therefore lead to absorption bands in the star's spectrum reflected by the planet. We call these features `generalized chlorophylls', as they generalize the green color of terrestrial plants.

In the present communication we discuss:

1 To what extent these absorption bands are present in terrestrial
photosynthetic cells

2 The remote detection of terrestrial chlorophyll from space

3 The artefacts which could mimic generalized chlorophylls'

4 A proposal for a an extension of the Terrestrial Planet Finder toward
the visible (the Epicurus space mission), to detect generalized
chlorophylls and other molecules of biological interest.
______________________________________________________________________
(#) Conference participant

EXOBIOLOGICAL APPROACH IN THE PROJECT 242 ASI/RUBBIA
THE ORIGIN OF LIFE IN THE UNIVERSE: EARTH AND MARS

MARIAISABELLA COLLI,

Politecnico di Torino
c/o Via Vagnono 9
10144 Torino, Italy
Fax 011 48 2101

In this paper we will summarise the origin and evolution of the universe: Earth/Mars life conditions
In this research many questions are very important:

1. How is important the "invention" of "photosynthesis" for the evolution of life? For this question we will begin with discussion of the requirements for the occurrence of life on Earth. which were the environmental condition on the Earth just after its formation? How does life function? How does it obtain energy from its environment and use this energy to power metabolism and reproduction?
2. It's possible this life without starlight?.
At the time of the Big Bang, matter would have consisted of pure energy. As it expanded and began the cool off, the energy would convert into matter, first elementary particles and then to protons, neutrons, and electrons. As mass is created out of energy, about 90% of the mass would be in the form of hydrogen and 10% as helium. As the universe continued to expand and produced regions that were dense enough to begin to collapse under their own gravity. The first galaxy has formed by these clouds collapsed, and within them, the first generation of stars.
The stars were dense enough and hot enough deep within their interiors that nuclear reactions occurred, combining hydrogen atoms together to helium, and then into heavier elements. This nuclear reaction released energy that was emitted by the stars in the form of light.
3. Could life have formed on Mars? Although Mars is relatively cold and dry on its surface today, it certainly was not so in the past. The geological evidence that we see shows that liquid water has been present on Mars throughout much of its history. Liquid water is the single environmental requirement trout to be essential for life, and with abundant water being present, environmental conditions on early Mars's may been similar to the conditions on the Earth at the same time.
This was a time when life was forming on the earth, and life may have been forming on Mars independently from the Earth. If there is no life on Mars, and no evidence for a past existence of life, it would then be important to understand what caused the Earth and Mars to differ so dramatically in their outcomes.
In this perspective the project 242 has an objective that is a respond to a strategic question: are there experiments that only humans could do on Mars? Today Mars is for people of Earth a great terra incognito, but a new scientific co-operation for exploration on red planet open a different perspective astrobiological on the life origin in the universe.
When we will begin to explore the red planet with the original project of Carlo Rubbia in geological, biological end climate condition, for the next generation will be an important and the exploration involved accomplished some significant science and technological researches.; this is a clear and compelling scientific incentive for people: to search for evidence of life.
The challenge is best addressed by perspective of scientific role of the Earth in the solar system localisation.
The topics discussed here represent the opening up of a new frontier.
First in more general terms of life evolution in the universe, we can say that with the Copernican revolution we have realised that the earth is not the centre of the universe, but the same evolution, chemical or atmospheric and climate condition, as biological indicators for the origin of life are the same for the mechanism of origin, but are uncertain.
For this new cultural approach we prefer to say: "The life in the context of the universe"
Searching for life on Mars: the available evidence of life on Mars, results from specific location on solar system and processes of metabolism that could involve CO or CO2.
Searching for life on Earth and Mars: this comparison involve two different conditions in the solar system, for the exobiological approach in the project 242.
Finally, then, with this project, we will turn our attention to the rest of the universe. Based on our understanding of own stars and planets form, do we expect planets and Earth-like planets in particular, to be a common occurrence?
What condition would make other planets habitable, given what we know of the requirements for life?
Chemical evolution
Atmospheric and climate condition and biological indicators are the first steps for the origin of life on Mars.
Exobiological approach
Biological indicators:
1. Water presence
2. Photosynthesis as product of chemical evolution
3. Pyrolysis/ or the carbon assimilation experiment was designed to test for Martian organism that could take in Co2 or CO from their environment and incorporate them into organic material.
The recent discovery of terrestrial organisms living deep within the Columbia River basalts in the Pacific Northwest, bolsters the possibility of organism living in these buried environments on Mars: these organisms survive by metabolising the hydrogen produced by chemical interactions between basalt and water in the pore spaces, completely independent of any input of chemical energy from the surface, surviving completely isolated from the surface.
Similar presence could have occurred on Mars as surface temperatures declined from early higher values to their present cold level..
An experiment on surface of Mars could test for the presence of Martian organism able to assimilate organic compounds from their environment.
4 Ability of adaptation in environment. This the last step, but most important for life continuation on Earth and on Mars surface: this a great biological indicator and it's possible the same condition on Mars?

SPATIAL AND TEMPORAL PATTERNS OF SOME CLIMATE PARAMETERS AROUND THE TIMBERLINE OF PICO DE ORIZABA

LUIS CRUZ-KURI
Instituto de Ciencias Básicas, Universidad Veracruzana
Carr. Xalapa-Veracruz Km 3.5, Las Trancas, Xalapa, Veracruz.

CHRISTOPHER P. MCKAY
NASA-Ames Research Center,
Moffett Field, CA 94035 USA

RAFAEL NAVARRO-GONZALEZ
Laboratorio de Química de Plasmas y Estudios Planetarios
Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de Mexico,Circuito Exterior, Ciudad Universitaria, Apartado Postal 70-543, Mexico

Abstract: Pico de Orizaba, the highest mountain in Mexico, has environmental conditions that probably could have occurred in ancient Mars and may also be relevant to the future introduction of life on Mars. Related to this, we address in this paper the question why life is constrained at high altitudes in our planet; we particularly focus to the search of those factors that determine the timberline. Since March 1999 we started to monitor the environmental conditions of the mountain, recording among other measurements data of soil temperature at various depths in different locations within, above and below the timberline of Pico de Orizaba. This is a preliminary report of some findings related to the search of spatial as well as temporal patterns of these parameters.

ENZYMATIC REPLICATION OF RNA ADSORBED ON CLAY MINERALS

MARCO FRANCHI, CLAUDIA VANDINI AND ENZO GALLORI
Department of Animal Biology & Genetics, University of Florence. Florence, Italy

Recent observations on the polymerization of activated nucleotides on clay surfaces (1) and on the resistance of clay-adsorbed nucleic acids to environmental degradation (2, 3) suggested that clay minerals could have acted as a resting place for the formation and persistence of nucleic acid precursors and for the self-organization of the first auto-replicating systems.
For these processes to occur, the adsorbed biomolecules must have been able to react with each other and to express their biological activities, such as the ability to catalyze specific reactions ("ribozymes") and to undergo pre-enzymatic replication.
In this work, we discuss our preliminary results on enzymatic replication and amplification (RT-PCR) of clay-adsorbed RNA.
16S ribosomal RNA, extracted from Escherichia coli, was adsorbed on two clay minerals, montmorillonite and kaolinite, and then subjected to RT-PCR with AMV-retrotranscriptase. The results indicate that adsorbed RNA is accessible to enzymatic replication, even though the presence of clay particles partially inhibits the reaction.
The observation that RNA can be enzymatically replicated, when adsorbed on a clay mineral surface, suggests that such a system could have been an important step in the early formation of self-replicating systems, promoting the assembly and persistence of informative polymers and allowing their interactions with enzymatic molecules.

1) Ertem, G. & Ferris, J.P. 1996 Nature 379, 238-240.
2) Paget et al. 1992 FEMS Microbiol. Lett. 97, 31-40.
3) Franchi et al. 1999 Orig. Life Evol. Biosph. 29, 297-315.

THE FORMATION AGE OF COMETS: PREDICTED PHYSICAL AND CHEMICAL TRENDS

JOSEPH A. NUTH III, HUGH G. M. HILL AND GUNTHER KLETETSCHKA#,

Astrochemistry Branch, Code 691, NASA's Goddard Space Flight Center,
Greenbelt MD 20771, USA (#Co-located in Code 921)

Dust grains in Herbig Ae/Be stars are continuously replenished by infalling comets. The IR spectra of these cometary grains appear to evolve temporally from initially amorphous astronomical silicates in young protostars to crystalline olivine in much older sources. Hallenbeck et al.1,2 have shown that crystalline olivine can only be produced from amorphous silicates on a time scale of months-to-years via thermal annealing at temperatures near 1000 K. Since such sustained high temperatures only occur near the central star3, dust annealed at 1000 K in inner nebular regions must be continuously transported beyond the nebular snowline to be incorporated into the next generation of cometesimals. The average formation age of a comet can therefore be measured as a ratio of the annealed crystalline olivine dust component to the total dust content of the comet. Comets formed from nearly pristine interstellar materials early in the protostellar nebula stage will contain very little crystalline dust whereas comets formed towards the end of the accretion period will incorporate a much higher percentage of annealed silicate. It is unlikely that only dust grains circulate from the inner to the outer nebula; the gas associated with such dust should also find its way beyond the snowline. Since this gas and dust will have equilibrated in the higher pressure-temperature regime of the inner nebula, it will contain a much higher proportion of hydrocarbons and ammonia than more pristine interstellar ices. Therefore, in addition to a higher fraction of crystalline dust, later forming comets should also contain higher ratios of hydrocarbons to CO and ammonia to N2 than do those formed early in the history of the nebula.

References:

1. Hallenbeck, S. L., Nuth, J. A., Daukantas, P. L. (1998) "Mid-infrared spectral evolution of amorphous magnesium silicate smokes annealed in vacuum: Comparison to cometary spectra", Icarus, 131, 198-209.
2. Hallenbeck S. L., Nuth J. A. and Nelson, R. N. (2000) "Evolving optical properties of annealing silicate grains: From amorphous condensate to crystalline mineral," Astrophys. J (in press).
3. Woolum, D. S. and Cassen, P. (1999), "Astronomical constraints on nebular temperatures: Implications for planetesimal formation," MAPS 34, 897-907.

EVIDENCE FOR ELECTRIC DISCHARGE IN CARBONACEOUS METEORITES

GUNTHER KLETETSCHKA; PETER J. WASILEWSKI
NAS/NRC ­ GSFC/NASA,
Greenbelt, MD, 20771, USA

Abstract: Carbonaceous meteorites contain protein and nonprotein aminoacids who may have served as a prerequisite for the origin of life on Earth and elsewhere in the cosmos. Electric discharge experiments produced essentially all proteins and nonprotein aminoacids that were found in samples of carbonaceous meteorites of CM type. Furthermore, the proportions of aminoacids relative to glycine in the Murchison meteorite are quantitatively similar to those found in the spark discharge experiments (Ring et al. 1972; Wolman et al., 1972; Ring and Miller, 1984; Robertson and Miller, 1995; Nelson et al., 2000,). It is possible to use magnetic signatures to indicate the existence of electric discharges in carbonaceous chondrule materials and consequently address the origin of these aminoacids.
In the terrestrial samples the carriers of remanent magnetization are magnetite, hematite, pyrrhotite and maghemite. In carbonaceous chondrites, in addition to these magnetic minerals we have tetrataenite and kamacite. Those magnetic minerals that were present during any electrical equilibration will be contaminated by magnetic fields. The extent of this contamination depends on the magnitude of the electric event, type and size of magnetic mineral, and interaction among the magnetic minerals.
Demagnetization experiments with the NRM (natural remanent magnetization) in carbonaceous chondrites indicate a reasonably high degree of magnetic stability compared to other groups of meteorites (Sugiura and Strangway, 1988). Thus the values of NRM are considered to provide the best evidence for the presence of magnetic fields in the early solar system. The REM values (ratio of remanent to saturation remanent magnetization) are not uniform for all carbonaceous chondrites and indeed range over 3 orders of magnitude. Since REM is a relative indicator of the efficiency of remanence acquisition, explaining these values is important.
Large REM values have been observed in terrestrial samples that were subjected to a lightning bolt (Wasilewski and Kletetschka, 1999). This remanent magnetization is due to the magnetic field associated with the electric discharge. Electric currents associated with electric discharges in early solar nebula may therefore be responsible for the magnetic remanence and specific records might be associated with the origin of protein and nonprotein aminoacids in carbonaceous chondrites.

References:

Ring, D., Y. Wolman, N. Friedmann and S. L. Miller, Prebiotic synthesis of hydrophobic and protein aminoacids. In Proc. Natl. Acad. Sci., 765-768, USA, 1972.
Ring, D. and S. L. Miller, The Spark Discharge Synthesis of Amino acids from Various Hydrocarbons. Origin Life Evol, B15, 7-15, 1984.
Nelson, K. E., M. Levy and S. L. Miller, Peptide nucleic acids rather than RNA may have been the first genetic molecule. In Proc. Natl. Acad. Sci, 3868-3871, 2000.
Robertson, M. P. and S. L. Miller, An Efficient Prebiotic Synthesis of Cytosine and Uracil. Nature, 375, 772-774, 1995.
Sugiura, N. and D. W. Strangway, Magnetic Studies of Meteorites. In Meteorites and the early solar system, edited by J. F. Kerridge and M. S. Matthews, 595-615, Univ. Ariz. Press, Tuscon, US, 1988.
Wasilewski, P. and G. Kletetschka, Lodestone - Natures Only Permanent Magnet, what it is and how it gets charged. Geophysical research letters, 26, 2275-2278, 1999.
Wolman, Y., W. H. Haverland and S. L. Miller, Non-protein aminoacids from spark discharges and their comparison with the Murchison meteorite amino acids. In Proc. Natl. Acad. Sci., edited by of 809-811, USA, 1972.

STABILITY OF RIBONUCLEIC ACID IN PROTECTIVE ENVIRONMENTS OF ALKANES n-C18 - RESULTS FROM EXPERIMENTS IN LABORATORY

VICENTE MARCANO, PEDRO BENITEZ, LUIS FAJARDO, ERNESTO PALACIOS-PRÜ.
Electron Microscopy Center, University of the Andes, P. O. Box 163, Mérida, Venezuela. prupal@ula.ve

It is generally agreed that the life have originated between 3500-3800 Myr ago (Orgel 1998). Before 3600 Myr, the oceans would probably have been repeatedly vaporized by large impacts, which could sterilize the planet eliminating small and large molecules and life itself (Maher & Stevenson 1988, Sleep et al. 1989, Zahnle & Sleep 1997, Lyons & Vasavada 1999). However, reconstruction of the last heavy bombardment indicates that large impacts up to 100-km in diameter occurred still 3600 Myr ago and generated excessive temperatures on Earth able to melt most of the planet´s mass (Lyons & Vasavada 1999). Though it is difficult to suppose that an accumulation of organic molecules could be possible before of this age, it would be feasible only during the intervals among each impactor fall (Marcano et al. 2000a), which would have surface temperatures between 85-110°C generated mainly by CO2 greenhouse effects (Kasting 1993).
It is frequently stated that the current occurrence of replicative systems based on RNA and DNA suggests an abundance of these molecules and its precursors during the early Earth (RNA world) (Watson et al. 1987). However, a RNA world and an abundance of nucleobases on the Earth´s surface under conditions 85°C are difficult to occur due to the high instability of these molecules (White 1984, Miller & Bada 1988, Lindahl 1993, Bada et al. 1995, Forterre et al. 1995, Levy & Miller 1998, Shapiro 1999). For instance, at pH 7 and 100°C, the half-lives of the nucleobases are: A = 1 yr, G = 0.8 yr, U = 12 yr, T = 56 yr and C = 19 days, whereas at 250°C, they are between 1 and 35 min, and at 350°C between 2 and 15 seconds. Even RNA molecules at pH 7 give a half life of 2 min at 250°C for the hydrolysis of each phosphodiester bond, at 350°C the half life is 4 seconds. The hydrolysis observed for the N-glycosyl bond in adenosine is 1.3 min at 250°C. Finally, the half life of ribose is 73 minutes at pH 7 and 100°C. However, RNA molecules had have other factors inhibiting their survival on the early Earth, such as photodecomposition by UV-radiations in the UVC and UVB regions and probably alterations by electron excitation caused by electric discharges, viz. excessive ion and free-radical production. We show here based in experimental data that the existence of thermostable n-alkane C18 environments on the Earth´s surface ( 3600 Myr) could offer various advantages for the survival of RNA molecules such as occur with other biomolecules (Marcano et al. 2000b). The first advantage would be allow protective and anhydrous conditions against rapid hydrolysis in high temperatures generated by CO2 greenhouse effect or small impacts; second, such coats may avoid or reduce the oxidative decomposition of RNA molecules inmersed in them caused by strong oxidants generated by hydrolysis, electrolysis or photolysis of several gases; third, absorbances of UVC radiations by heavy n-alkanes allow the protection against photolysis, and fourth, due to the low dielectric constant (2.0-2.5 x 106 cycles) and conductivity ( 0.5 µs/cm) of these alkanes, this layer might serve as an insulator thereby protecting the synthesis and accumulation of RNA molecules from alterations by electron excitation caused by excess of ions from electric discharges.
Quantification of RNA molecules (NAQ) was determined using a Gene-Quant pro RNA/DNA Calculator model Amersham Pharmacia Biotech. Products not soluble in organic solvents were studied by fluorescence microscopy and scanning electron microscopy (SEM). This last procedure was found to be especially useful for the study of their surface and density. Material was first heated in 60°C during two days, coated with gold under vacuum and observed with an S-2500 Hitachi microscope at 10 KV. Experiments were carried out in a 2.85-liter glass (Pyrex) reactor containing 100 ml of mineral oil and 500 mg of RNA from Torula yeast (Sigma). Heavy mineral oil was used (d = 0.85 g/cm3) as a model of primordial alkanes n-C18. Simulating the absence of UV atmospheric shielding, the reactor was exposed to UVC-radiations (253.7 nm lamp, 2200 µW cm-2) in a dark room. The experiment was carried out simultaneously under spark discharges (continuous arc) obtained from a high-frequency Tesla coil (50 c/s, 120 V input; 30 kv, 0.35 amp, 10.5 KW output, Electro Technic Products, model BD 10) for 15-45 minutes. Temperatures ranges chosen were between 100-250°C. When heated, the content of the flask reached 100% of their final temperature within 5-10 min. This was measured by a thermocouple inserted into of the flask. One type of prebiotic-like atmosphere was selected for these experiments having H2O + CO2 in equimolar concentrations and pressures ranging between 0.6-0.8 bars. All the raw products were dispersed in Milli-Q water, stirred, separated from the mineral oil by chloroform, decanted, and filtered through Whatman No. 1.
Kinetics of the decomposition of the RNAs indicates constants k = 15.33 mg min-1 at 250°C, k = 10.8 mg min-1 at 200°C, k = 2,91 mg min-1 at 150°, and k = 0.25 mg min-1 at 100°C, whereas activation energy is Ea = 3,42 x 104 J.degree.mg. These data reveal a half life for RNA of 50 min at 250°C, 1.28 hour at 200°C, 1.67 hour at 150°, and 6.98 hour at 100°C. Control data showed a half life < 1 second at 150°C and an activation energy Ea <<< 3 x 104 J.degree.mg in absence of mineral oil. The presence of an amphiphilic component in the heterogenous products was determined by surface tension measurements in aqueous media by microscopy, at 20°C and 1-bar. Superficial tension values have ranges between 1.94 x 106 and 5.82 x 105 dynes cm2 of pressure. This component shows spheroidal shape, dark brown appearance, solid, uniformity of size ranging it between 3-5 µm in diameter. Residues from the simulations dispersed in aqueous media for microscopy and examined by fluorescence revealed negative UV excitation. The absence accretion suggest not the passage of molecules through boundary.
In conclusion, although the half-lives of the RNA molecules were slightly major under protected conditions by n-alkane C18 environments against hydrolytic, electrolytic and oxidative effects at temperatures between 100-250°C, the thermal lability of the N-glycosyl and phosphodiester bonds would present major problems in the accumulation of this essential compound in the early Earth. Therefore, atmospheric models suggesting a cool early Earth rather that a warm one or the occurrence of an RNA-like polymer, with a simpler or more accesible backbone, need to be considered.

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ADAPTATIVE RESPONSE OF A FUNGUS SPECIES TO HYDROCARBON ENVIRONMENTS WITH MINIMUM OXYGEN AND WATER REQUIREMENTS - RESULTS FROM EXPERIMENTS IN LABORATORY

VICENTE MARCANO, PEDRO BENITEZ, AND ERNESTO PALACIOS-PRÜ.
Electron Microscopy Center, University of the Andes,
P. O. Box 163, Mérida, Venezuela. prupal@ula.ve

The growth of microorganisms under extreme environmental conditions such as exposure to UVC and UVB radiations, low or high temperatures, absence of oxygen, minimum or no water supply, and very low pH has been known for many years. This fact motivated the development of studies under in vitro conditions similar to those of the early Earth and extraterrestrial environments during the last five decades (Becquerel 1936, 1948, 1951; Kuiper 1952, Basa & Hawrylewicz 1962, Siegel 1963). Currently, it is well known the capacity of some microorganisms to support extreme conditions in exobiological experiments of spatial simulation (Dose & Klein 1996) and out of the Earth´s atmosphere (Horneck 1993). Even these microorganisms are capable to metabolize abiotic 'tholins', say, laboratory materials that provide good analogues to meteoritic and cometary organics (Chyba et al., 1990). However, most of these studies have been done using prokaryotes, especially bacteria belonging to the Bacillus and Methanobacterium genera. Most recently, Marcano et al. (1999) demonstrated the capacities of extreme biological adaptation of an eukaryotic organism that grows in hydrocarbons media, viz. Fusarium alkanophillum V. Marcano & Palacios-Prü. We showed here additional data relative to the extreme adaptation of this fungus species with minimum oxygen and water requirements.
Fusarium alkanophillum showed a mean growth rate in hydrocarbon and agar media of 1.9 mm hour. Fusarium alkanophillum was able to grow and degrade several hydrocarbons without or minimum water (0.25-1 ml 500 ml hydrocarbon) and oxygen (1.26-4.24 µM/hour, or 5 %/hour) requirements, producing between 0.5-3.6 g (dry weight) of biomass. These hydrocarbons included kerosene, gasoil, mineral oil, paraffin and asphalt. The growth of Fusarium alkanophillum was inhibited in media containing C10 hydrocarbons, viz. toluene, dioxane, hexane, benzene and xylene. It was able to grow aerobically in PDA, MA and CZA culture media. Fusarium alkanophillum showed no growth on several hydrocarbon media with creosote or HgCl2. No growth was observed in several synthetic media containing urea, ammonium carbonate and potasium ferrocianurum as nitrogen sources in the presence of hydrocarbons. This organism is proteolytic, since albumin serum, glycoprotein and gammaglobulin serum served as a good source of carbon and nitrogen in cultures with hydrocarbons, but in media containing other proteins that lack sulphur linkages no growth was observed, e.g. casein, papaine, trypsin. Fusarium alkanophillum showed optimal growth on kerosene media with PDA, MA and CZA culture media. In cultures with kerosene and PDA or sulphur-containing proteins having H2O2 between 0.2-0.6 µl/ml, a notable growth (1.5-2.5 mm/hour) was observed, whereas in higher concentrations, the growth was inhibited. In simulation experiments under reducing atmosphere (NH3 vapours) having 254 and 354 nm UV-radiations, low pressure (-1 atm) and mineral oil in PDA or sulphur-proteins, F. alkanophillum showed a retarded growth ( 0.5 mm/hour). In other experiments under oxidizing atmosphere (CO2) having 254 and 354 nm UV-radiations and mineral oil in PDA or sulphur-proteins, F. alkanophillum showed enhanced growth ( 2.8 mm/hour) whereas in 254 and 354 nm UV-radiations in asphalt having sulphur-proteins, growth was normal ( 2.5 mm/hour). Spore formation was stimulated markedly by exposure to 354 nm UV-radiation. Optimal growth occurs at 25°C. Immersion in mineral oil at all temperatures, from -20°C to 55°C, during 15 days had no deleterious effects on the subsequent growth of the fungus from germinated spores.
Analysis by TEM of F. alkanophillum grown in light hydrocarbon media revealed the presence of a cell wall, however, the absence of plasmalemma, nuclear membranes and other cytomembranes was consistently observed. On the other hand, in heavier hydrocarbon media, vesicles, multivacuolar bodies, vacuoles and groups of parallel membranes resembling smooth endoplasmic reticulum were seen. Mitochondria were not observed in both cases. Samples from heavier hydrocarbon media revealed disperse and irregularlly disposed nuclear material, associated to free ribosomes. Ribosomes were also observed when the fungus grow in lighter hydrocarbons. Aqueous extracts of secreted material from several hydrocarbon-cultures revealed the presence of fatty acids, iodinated derivatives, UV-protective indole pigments, and showed a positive reaction to the Lowry test for protein, including a positive hemagglutinating activity and precipitation of glycoconjugates, suggesting the presence of lectins.
In summary, F. alkanophillum showed diverse typical features of an extremophile organism, such as facultative anaerobism, capacity to grow under oxidizing or reducing atmospheres, minimun water requirement, growth and sporulation stimulated by exposure under UVC and UVB radiations, visible light or dark, enhanced development in several enriched media in hydrocarbons and sulphur, and varied morphological and physiological adaptative changes. The characteristics of the electron-transport system developed in non-aqueous media are not known. The efficient adaptation of F. alkanophillum to grow in hydrocarbon media and the high requirements of sulphur suggest a long evolutionary process that would have occurred in hydrocarbon natural zones, viz. near hot springs and hydrothermal vents, asphalt lakes, ponds.
The absence of lipidic membranes in F. alkanophillum constitute an important finding in the cell biology of the terrestrial species that deserve careful evaluation. Moreover, the study of the physiological mechanisms involved in anhydrous conditions must be of interest in the exobiology of planetary bodies having hydrocarbon potential niches because it offers a different vision related with the understanding of the origins of life including in the Earth.

Basa, K. B. and Hawrylewicz, E. J.: 1962, Ill. Inst. Technol. Armour. Res. Found., Rep. No. 3194.
Becquerel, P.: 1936, C. R. Acad. Sci. 202. 978.
Becquerel, P.: 1948, C. R. Acad. Sci. 226, 1413.
Becquerel, P.: 1951; C. R. Acad. Sci. 231, 261.
Chyba, C. F., Thomas, P. J., Brookshaw, L. and Sagan, C.: 1990, Science 249, 336.
Dose, K. and Klein, A.: 1996, Origins of life and Evol.Biosphere 26: 47-60.
Horneck G. 1993. Origins of life and Evol.Biosphere 23: 37.
Kuiper, G. P.: 1952, in (ed.) G. P. Kuiper, The Atmospheres of the Earth and Planets, Univ. Chicago Press, Chicago, Illinois, pp. 306-405.
Marcano, V, Benitez, P. and Palacios-Prü E.: 1999, in Abstracts of the 12th International Conference on the Origin of Life, ISSOL´99, held in San Diego (USA), p. 112.
Siegel, S. M.: 1963, Nature 197, 329.

PLANETARY HABITABLE ZONES: PHYSICAL ENVIRONMENT REQUIREMENTS AND POTENTIAL DISTRIBUTION OF LIFE IN PLANETARY BODIES

ABEL MÉNDEZ

Department of Physics and Chemistry
University of Puerto Rico at Arecibo
Call Box 4010; Arecibo, PR 00613
email: a_mendez@cuta.upr.clu.edu

A planetary habitable zone (PHZ) is the spatial and temporal region, within a planetary body, which is capable of supporting life. Earth's global PHZ, the biosphere, includes part of the atmosphere, hydrosphere and lithosphere. Microbial life thrives within these regions due to the availability of biogenic elements, liquid water, energy sources, and the right environment state. Temperature and pressure are some of the quantities that define the physical environment state. Although much has been studied about the effects of temperature, little is known about the combined effects of pressure and temperature on microbial growth. Most microorganisms require an environmental temperature for optimum growth of 310 K at standard atmospheric pressure (~1 bar), but microbial growth is possible between 253 and 386 K. Growth of most terrestrial microorganisms is retarded with hydrostatic pressures between 300 and 400 bars. At 600 bars most terrestrial microorganisms are sterilized; only a few species of marine bacteria grow at such pressure or higher. About 85% of the studied microbial diversity have an optimum growth temperature between 295 and 315 K, 14% have an optimum growth temperature over 315 K and only 1% below 295 K. These temperatures are higher than Earth's average surface environment (288 K), but are consistent with subsurface environments. This strong tendency of microbial diversity toward mesophilic environments may have evolutionary and/or physiological reasons. A comparison of these physical requirements of microbial life with the current environments of Mars and Europa shows potential distributions of PHZ within their subsurface.

COSMOPARK ­ A NATURAL ASTRONOMICAL OBSERVATORY

. JOAN ORÓ AND XAVIER PALAU,

Fundació Joan Oró,
Lleida, Spain.

1. THE COSMOPARK PROJECT
The COSMOPARK project involves the construction of an astronomical observatory in a zone of great environmental interest. The place is the mountain of Montsec geographycally located in the North-East of Spain (Latitude 42N, Longitude 1E) south of the Pyrenees and within the Autonomous Region of Catalonia.
The Montsec mountain (altitude 1.600m) has been selected as one of the best sites for astronomical observation because its absence of luminic pollution, great atmospheric transparency, low humidity and an annual pluviometry of less than 500 mm. It is a very dry area, above the fog level that usually settles during the winter in the neigboring city of Lleida. Furthermore, it is quite accessible by road being situated approximately 40 km north of Lleida, and about 150 km west of Barcelona.
In the past the site has been of tremendous interest to geologists because its Triassic sediments which crop out on the surface are well dated and make possible to follow their tectonic and stratigraphic history in great detail for millions of years. From this geological point of view this regional zone has been one of the most visited sites in Europe.
The Montsec mountain is also of significant paleontological interest. In its soil and in the neighboring areas many footprints and fossils of dinosaurs have been found. One year ago the first international meeting on fossilized eggs of dinosaur was held in the town of Tremp, close to the Montsec mountain. The flora and fauna of the region which includes some unique species are also of particular interest.
Recognizing the exceptional qualities of the Montsec mountain and neighboring areas, a Consortium of local institutions (involving the counties of Pallars Jussà, and Noguera and supported by the "Diputació de Lleida", the Government of Catalonia and the European Community) has been established under the name of COSMOPARK which is managed by the Joan Oró Foundation.

2.OBJECTIVES
As suggested by the title and the preceding lines the objectives of the project are twofold. To create an Astronomy Observatory and a Natural History Center. The first is to be constructed on the top of the Montsec mountain near the small town of Sant Esteve de la Sarga, and the second center is to be build, at the base of the mountain, near the city of Ager.
Both centers would be dedicated to research, training and educational activities in their respective areas of knowledge fulfilling the needs of the University of Barcelona, and the Institute of Space Studies (IEEC) and other educational institutions. They would take advantage of their priviledged environment for the observation of the cosmos, and for the study of the geological, paleontological and natural history of the Montsec mountain and its neighboring areas. It is hoped that such a project will also contribute to the economic development of this pre-Pyrenees area of Catalonia.

3.ASTRONOMY OBSERVATORY
The Montsec Astronomic Observatory will develop its own Programs of Research following the tradition of the Fabra observatory in Barcelona. From the Fabra Observatory J. Comas i Sola discovered several comets and asteroids (e.g.Titania, Barcelona). In 1907 he discovered for the first time the presence of an atmosphere in Titan, the largest satellite of Saturn. The new observatory at Montsec will join the European Astronomical network making telescopic observations following the orbits of known asteroids and periodic comets, and will also search for possible unknown minor bodies orbiting the Sun. Other programs of research will concentrate on the outer planets of the Solar System, and also on certain variable stars.
The Infrastructure of the Observatory should include the following equipment.
A 2m telescope for professional use, with camera CCD for direct imaging and photometry, spectrograph with appropiate filters, to be used on site, or robotically guided from the Department of Astronomy of the University of Barcelona, the Institute Space Studies of Catalonia (IEEC) and from other centers.
A 0.8m telescope for professional use as well as for amateur astronomers, with similar accesory equipment as indicated above.
A 0.4m telescope, primarly for the use of amateur astronomers and visiting persons. It should be equipped with comercial CCD camera, photometer, photographic camera, filters, as well as other regular equipment for visual observations.
Technical services for operation and maintenance of the Observatory equipment.
Appropiate Housing for the professional observers and for the maintenance servicemen.
Meteorological observatory, and receiving terminal for the reception of meteorological data from satellites.

4.THE NATURAL HISTORY CENTER
The Natural History Center has to be prepared for scientific lectures and public education in all the areas of knowledge related to the Montsec mountain and its vicinity. Very briefly this should include:
An interactive museum in the areas of geology, paleontology, flora, fauna environmental protection and astronomy as well as research related to the activities of the centers.
A planetarium where in addition to its normal use, lectures and courses can be offered in the area of astronomy.
A laboratory where one can make practical work on equipment, or make experiments in the pertinent areas of research.
An auditorium, or congress hall, where conferences, symposium or educational lectures can be presented.
A computer laboratory with several computers and printers for internet and informational multimedia activities.
Four retractable domes, relatively small, for amateur telescopic observation of the sky. The atmospheric transparency is so good, even in the city of Ager that one can see in clear detail all of our galaxy, the Milky way.
An open site (COSMOPARK OPEN MUSEUM) for the exposition of dinosaurs fossils and our arboretum with different species of plants typical of the area.

PROBLEMS ABOUT THE CURRENT OCCURRENCE OF LIQUID WATER ON THE SURFACE OF MARS

ERNESTO PALACIOS-PRÜ AND VICENTE MARCANO

Electron Microscopy Center,
Evolutionary Biology and Chemistry Laboratory,
University of the Andes, P. O. Box 163,
Mérida, Venezuela. cme@ula.ve, prupal@ula.ve

Abstract. Images of the Martian surface transmitted to Earth by the Mars Global Surveyor spacecraft were recently interpreted as evidence of the presence of liquid water (Malin & Edgett, 2000). This finding would suppose the occurrence of gullies within the walls of a very small number of impact craters, south polar pits, and two of the larger Martian valleys display geomorphic features that could be explained by processes associated with groundwater seepage and surface runoff (Malin & Edgett, 2000). Careful examination of the images acquired by Mars Global Surveyor Mars Orbiter Camera (MOC2-234-245) allowed by JPL/NASA/Malin Space Science Systems, showed features that were far away from those interpretations, because it is difficult to conceive runoff, gullies or outflows as originated from the effects of liquid water running on the current Martian surface. Our observations questioning the above interpretations are the following:
1. Mars has a daily wide thermal oscillation showing mean values of 50°C. Thus, during the day, in Chrysis Planitia and in Utopía Planitia surface temperatures up to ­30°C have been recorded; during the night, temperature may go down as below as _83°C. Wider oscillations have occurred at the subtropical regions, registering 27°C during the day and _89°C during the night in the soils (Tillman et al., 1993; Jakosky et al., 1995). On Earth, the maximum daily thermal oscillations have been recorded in the Andean Páramos, 28.2°C; Guayana´s Highlands, 26.4°C (Azócar & Monasterio, 1980, Vareschi, 1992; Marcano, 1998), and Mojave desert, China Lake, ~ 20°C. In Mars, these temperature changes may give place to fractionations on rocks and soils on cliffs which are transported down the slope, similarly as occur in the desertic Páramos during the night (Schubert, 1980). Further, lapiace and diaclase formations, stripes, and long erosive lines may also be formed from freezing-defrosting cycles. These temperature changes, as occurring in Mars, are able to produce cracks on the ground having polymorphic and convex (pingos) shapes, and thereby outbursting during the day all the hypothetical water retained below ground (permafrost).
2. Pressures recorded on Mars correspond to 6.36 mbars with variations of 37% (Owen et al., 1977). This very low pressure, about 100 times less than it is at sea level on Earth (1 bar), can cause water boiling at temperatures higher than 273 K (0°C). Further, the atmospheric surface pressure on Mars is remarkably close to the triple point pressure 6.1 mbars. Thus, it is very difficult to believe that liquid water run on the surface of Mars forming outflows or gullies without being evaporated, mainly during a warm afternoon. Further, both low pressure and fragility of the soils by wethearing can cause continuous collapses on the surface around the internal margins of craters or valley walls, showing false runoffs or gullies.
3. Because of the high thermal oscillations being recorded daily in Mars, intense winds are generated mainly toward the equatorial region, having mean velocities of 2 m/sec and gusts up to 15 or 19 m/sec (Murphy et al., 1990). These winds are constant during the whole Martian year and can produce an erosive process that continuously modify the topography giving place to news reliefs and formations such as dunes, monticles, channels, polygons, erosive lines (Thomas & Gierasch, 1995), which may be mistaken for and interpreted as erosions produced by liquid water. In Earth, desertic Páramos > 4500 m, show winds with mean velocities of 2.8 m/sec (Azócar & Monasterio, 1980), and gusts with velocities up to 25 m/sec, as occurring on the higher peaks, e.g. Bolívar, Espejo (Marcano, 1994). These winds may occasion modelling processes of granitic rocks and their surfaces (Schubert & Vivas, 1993), including formation of long and depth erosive lines and sorted and non-sorted stripes (Schubert, 1972; Beaty, 1974).
4. Martian atmosphere is mainly composed by 95.32% CO2, 2.7% molecular nitrogen and 1.6% argon (Owen et al., 1977). High oxidative atmosphere would generate deterioration of the soil and therefore would cause the formation of channels or gullies similar to those formed by liquid water running on the surface. This effect would be increased due to the action of intense winds and thermal changes, such as is seen in the Earths's periglacial regions (Schubert, 1972; Beaty, 1974).
5. An intense volcanic activity (Hodges & Moore, 1993) and plate tectonics (Sleep, 1994) would have been demonstrated as occurring on Mars. These processes could originate ruptures of lands over very large distances (faults or graben) and to simulate erosion lines or false runoffs.
6. The residual effects of shock waves, generated by asteroidal impactors having variable mass and diameter during the Martian history (Leighton et al., 1965; Melosch & Vickery, 1989; Squyres & Kasting, 1994), such as kinetic energy deposition, impact pressure and high temperatures could give place to cicatrices that may be mistaken for gullies and runoffs. Sismic and gravity wave oscillation effects may also produce weakening on the surface around the internal margins of craters (Melosh, 1982), which would be mistaken for gullies and runoffs. These effects are very frequent on Hellas Planitia, which is considered the longer second impact basin existing in our solar system (2000 km in diameter) (Leighton et al., 1965).
7. Finally, weakening and deterioration of the ground surface due to frequent impacts, wind action, and thermal fractionation might uncover the subterranean water channels, causing the outflow of boiling water thereby emptying out those subterranean water channels. This process must involve repeated outbursts of water and debris and generate false runoffs and external channels during the geological time.
In conclusion, the occurrence of water on Mars near polar caps, have been suficiently demonstrated by the Mariner IV, VI and VII, Viking I and II and Pathfinder spacecrafts and more recently by the Mars Global Surveyor. Although there is evidence of the existence of subterranean water flows (permafrost) in Mars, it appears that solid evidences of liquid water running on the current surface of Mars are still lacking.

Azócar, A. & Monasterio, M. 1980. Caracterización ecológica del clima en el páramo de Mucubají. In: Estudios Ecológicos en los Páramos Andinos, ed. M. Monasterio, Ediciones de la Universidad de Los Andes, Mérida, p. 207-223.
Beaty, C. B. 1974. Needle-ice and wind in the White Mountains of California. Geology 2, 565-567
Jakosky, B. M., Henderson, B. G. & Mellon. M. T. 1995. Chaotic obliquity and the nature of the Martian climate. J. Geophys. Res. 100, 1579-1584.
Hodges, C. A. & Moore, H. J. 1993. Atlas of volcanic landforms on Mars. U.S. Geological Survey Professional Paper 1534.
Leighton, R. B., Murray, B. C., Sharp, R. P., Allen, J. D. & Sloan, R. K. 1965. Mariner IV photography of Mars: Initial results. Science 149, 627-630.
Malin, M. C. & Edgett, K. S., 2000. Evidence for recent groundwater seepage and surface runoff on Mars. Science 288, 2330-2335.
Marcano, V. 1994. Studies in Venezuelan Andean lichens. Vol. I, Koeltz Scientific Books, Germany, p. 63.
Marcano, V. 1998. Ecophysic study of forested microrrefuges from the Gran Sabana, Venezuela and of their lower plant and fungus communities. Rev. Ecol. Latinoamericana 5, 21-48.
Melosh, H. J. 1982. A schematic model of crater modification by gravity. J. Geophys. Res. 87, 371-380.
Melosch, H. J. & Vickery, A. M. 1989. Impact erosion of the primordial atmosphere of Mars. Nature 338, 487-489.
Murphy, J. R., Conway, B. L. & Tillman, J. E. 1990. Observations of Martian surface winds at the Viking lander 1 site. J. Geophys. Res. 95, 14555-14576.
Owen, T., Biemann, K., Rushneck, D. R., Biller, J. E., Howarth, D. W. & Lafleur, A. L. 1977. The composition of the atmosphere at the surface of Mars. J Geophys. Res. 82, 4635-4639.
Schubert, C. 1972. Suelo estriado, un tipo de suelo pautado en la zona periglacial de los Andes Venezolanos. Acta Científica Venezolana 23, 108-152.
Schubert, C. 1980. Aspectos geológicos de los Andes Venezolanos. In: Estudios Ecológicos en los Páramos Andinos, ed. M. Monasterio, Ediciones de la Universidad de Los Andes, Mérida, p. 29-46.
Schubert, C. & Vivas, L. 1993. El cuaternario de la Cordillera de Mérida, Andes Venezolanos. Universidad de Los Andes y Fundación Polar, Mérida, pp. 345.
Sleep, N. H. 1994. Martian plate tectonics. J. Geophys. Res. 99, 5639-5655.
Squyres, S. W. & Kasting, J. F. 1994. Early Mars: How warm and how wet ? Science 265, 744-749.
Tillman, J. E., Johnson, N. C., Guttorp, P. & Percival, D. B. 1993. The Martian annual atmospheric pressure cycle: Years without great dust storms. J. Geophys. Res. 84, 10963-10971.
Thomas, P. C. & Gierasch, P. J. 1995. Polar margin dunes and winds on Mars. J. Geophys. Res. 100, 5397-5406.
Vareschi, V. 1992. Vegetationsökologie der Tropen. Eugen Ulmer Verlag, Stuttgart, p. 222.

EXPERIMENTAL SIMULATION OF TITAN'S ATMOSPHERE BY COLD PLASMAS

SANDRA I. RAMÍREZ1,2, RAFAEL NAVARRO-GONZÁLEZ1, PATRICE COLL2, FRANÇOIS RAULIN2

1: Laboratorio de Química de Plasmas y Estudios Planetarios. Instituto de Ciencias Nucleares, UNAM, MEXICO
2: Laboratoire Interuniversitaire des Systèmes Atmosphériques. Université Paris XII, FRANCE

Titan, the biggest Saturn's moon, is one of the most interesting bodies in the solar system for Exobiology due mainly to the rich organic chemistry that is being developed into its dense atmosphere constituted by nitrogen and methane. Spacecraft and Earth-based observations have contributed to a better understanding of the characteristics of the satellite. Laboratory simulations and modeling work have also provided a wide range of information that in many cases has helped to give a better interpretation to direct observations. In this work we have studied the gas-phase organics produced by positive and negative corona discharges. We proposed this type of electrical discharges as the mechanism of energy dissipation in Titan's troposphere (Navarro-González and Ramírez, 1997). Corona discharges can develop among the diffuse clouds of methane thought to exist in the lower atmosphere of the satellite (Griffith et al., 1998). We have also studied the optical properties of the analogues of aerosol produced by the irradiation of a simulated stratosphere with a direct current plasma discharge. The complex refractive index of the aerosol analogues form the basis of the radiative transfer models and its parameters n and k, are essential in the interpretation of the atmosphere dynamics and surface composition.
To simulate Titan's troposphere we used a mixture of methane in nitrogen (1:9) at an initial pressure of 670 mbar at 293 K irradiated at different time intervals. Corona discharges were produced in a coaxial array with a variable voltage (11.2-14.5 kV for positive coronas and 7.9-11.2 kV for negative coronas) and constant current (1 ¥ 10-4 A). During the irradiation time (from 2.5 to 60 minutes), measurements of the dissipated power were done and used, together with calibration curves, to compute energy yields of the different products. The identification of the gas-phase products was performed using a GC-MS-FTIR coupled system. 24 hydrocarbons and 6 nitriles were identified. The main products are ethane, propane, n-butane, methanenitrile and ethanenitrile. An enhancement in the energy yields was observed when the simulated troposphere was irradiated with positive coronas suggesting that different chemical mechanisms operate during the propagation of both negative and positive corona discharges. The synthesis of the aerosol analogues was performed using a continuous flow of methane in nitrogen (2:98) at 1 mbar and 293 K in a Pyrex reactor in which the direct current (DC) plasma discharge takes place. Thin films of the aerosol analogues were deposited on quartz slides after 120 and 240 minutes of irradiation with a power of 280 W. Transmittance and reflectance measurements were performed on the films in the 200-900 nm range using a Cary 5 spectrophotometer. From these values we computed the refractive index (n) and the extinction coefficient (k) parameters. We studied the influence of thickness, porosity and light scattered of the samples in the final n and k values. We present a new set of values, with their uncertainties, as a reference for those who study the dynamics of Titan's atmosphere or who aim to explain the satellite' surface characteristics.
We will discuss the implications of our results in the context of Titan's atmosphere and in the light of the future arrival of the Cassini spacecraft and Huygens probe to Titan.

Griffith C. A., Owen T., Miller G. A. and Geballe T. (1998) Transient clouds in Titan's lower atmosphere. Nature 395, 575-578.
Navarro-González R. and Ramírez S. I. (1997) Corona Discharge of Titan's Troposphere. Adv. Space Res. 19(7), 1121-1133.

THEORIES ON ORIGIN OF LIFE BETWEEN 1860 AND 1900, A SHORT TIME AFTER THE WORKS OF PASTEUR ABOUT SPONTANEOUS GENERATION

FLORENCE RAULIN CERCEAU,

Centre Alexandre Koyré &
Muséum national d,Histoire naturelle
Grande Galerie de l,Evolution
36 rue Geoffroy st Hilaire
F-75005 Paris

Pasteur,s views on physiological basis of fermentation led him directly into the spontaneous generation controversy. In 1860, Pasteur presented a series of five notes to the Academie des Sciences on the subject of spontaneous generation, which were brought together in his prize-winning essay, « Memoire sur les corpuscules organises qui existent dans l,atmosphere » (published in the Annales des Sciences Naturelles in
1861). Pasteur concluded from his experiments that the appearance of microorganisms was produced not by spontaneous generation but rather by germs present in the atmosphere.

But the French coup de grace of Pasteur did not completely kill the doctrine of spontaneous generation, which continued to be debated as far as 1900. In particular, this new theory didn,t solve the problem of the origin of the first living organisms, within the context of the theory of transformism and biological evolution. If life has always derived from living organisms, where did primitive life come from ?

In the middle of such a complex situation, a few theories on origin of life began to emerge, showing that life could have arisen from inorganic matter a long time ago. This paper will present the main ideas that have been proposed during the second half of the nineteenth century, which is a period particularly interesting for the study of the first steps of the science of origin of life and of the last steps of the dogma of spontaneous generation.

IS NATURAL INTELLIGENCE CORRELATED WITH CELLULAR COMPLEXITY?

M. RIZZOTTI

Department of Biology,
University of Padova,
Padova, Italy
rizzotti@bio.unipd.it

Any material system which connects receptors and effectors can be considered as intelligent if its effectors modulate their actions so that they usually maximize their success with reference to a given goal. This modulation requires some sort of a feedback circuitry endowed with memory and logic functions; a more refined modulation requires a more complex circuitry.
Artificial intelligent systems can rely on many kinds of functional units such as mechanical ones, vacuum electronic ones, or solid-state electronic ones. In contrast, natural intelligent systems (which are necessarily living things) can only rely on suitable cells (as life itself can only exist in form of cells). The goal of an artificial system is planned by its constructor, while the goal of a living system is an intrinsic and necessary product of natural selection. This evolutionary product, i.e., the goal, is to maximize the spread of the genes of the individual living thing, i.e., to maximize the reproductive expectations of the individuals which are most similar to itself.
With reference to the parameters which "measure" the cellular complexity from different standpoints, we may say that the neurons of animals do not share all of them. For example, they seem to have the highest number of expressed genes per cell, but they do not show any particular complexity in the compartmentalization, which has its highest value in some plastid-containing protists.

TWO POSSIBLE STEPS OF THE CHEMICAL EVOLUTION
ON SURFACE OF SMALL BODIES IN THE SOLAR SYSTEM

M.B. Simakov and E.A. Kuzicheva
Group of Exobiology, Institute of Cytology, St.Petersburg, Russia
exobio@usa.net

The small bodies in the Solar system are rich in organic compounds. The goal of our investigations is to elucidate the role playing of different energy sources of open space in the abiogenic synthesis of these compounds. We would like to establish how far the chemical evolution could develop on the surfaces of space bodies.

We investigated two types of reactions:
_ (1) Abiogenic synthesis of nucleotides from mixtures of nucleoside + inorganic phosphate;
_ (2) Abiogenic synthesis of dipeptides from mixtures of simple amino acids.
The reaction mixture in the form of a solid film contains 1.3 mM of nucleoside and 1.3 mM of dihydrogen phosphate or equimolar quantities of amino acids. Seven different mixtures consisting of nucleoside (thymidine, cytidine, uridin, adenosine or deoxyadenosine, guanosine or deoxyguanosine) and NaH2PO4 and four mixtures of aromatic (tyrosine or triptophan) and aliphatic (glycin or alanine) amino acids are investigated. Mixtures were prepared by air drying of aqueous solutions on special glasses. The films were irradiated by different sources of energy:
_ (1) VUV-light of 145 nm from the lamp with high frequency barrier discharge in Kr;
_ (2) high energy protons from the cyclotron U-120; and
_ (3) were installed on the surface of biosputnik in outstanding container (OC) when they were exposed to the action of all spectra of the open space energy sources during the entire time of flight - 327 hours (24.12.1996-07.01.1997).
As a result of VUV irradiation of the solid mixture of nucleoside and NaH2PO4 the natural monophosphates of corresponding nucleosides were found. The main products were nucleoside-5'-monophosphates and some amount of by-products (2'- and 3'-monophosphates, 2'3'- and 3'5'-cyclomonophosphates). The yields of products were small, within few per cents, however the effectiveness of the abiogenic synthesis on VUV irradiation is higher than on UV-radiation and heat. The films containing a mixture of amino acids yielded various dipeptides after they were exposed to VUV-radiation. Polymerization is an essential step in prebiological evolution and we have shown that this process probably could take place even at early stage of the Solar System formation, before planet accretion, on surface of small bodies. When thin films of organic compounds were irradiated with protons (2-6 MeV) the similar spectra of biochemically important compounds had been synthesized.
It was important to test how far the process of chemical evolution could take place on the surface of space bodies under action of all energy sources of the open space. In space flight experiment on board of "BION ­ 11" satellite the solid films from mixtures of different nucleosides and inorganic phosphate are exposed to space condition. The abiogenic synthesis of the nucleotides as 5'-, 2'- and 3'- monophosphates of thymidine, cytidine, adenosine and deoxyadenosine is observed. The cyclomonophosphates are synthesized also.
The main products of the reactions in all experiments were 5'monophosphates of corresponding nucleosides. Preferable 5'-monophosphate formation is indicative of more advantageous spatial position of 5'hydroxyl group in carbohydrate residue in comparison with 2'- and 3'-hydroxyl groups.

PREBIOLOGICAL SIGNIFICANCE
The results of our previous laboratory investigations on action of UV radiation with different wavelengths (145-260 nm), _-radiation and heat show that many kind of open space energy could be effective in the chemical evolution of nucleic acids precursors and oligopeptides. The abiogenic synthesis of nucleotides and dipeptides can proceeds in open space conditions on early stages of the Solar system evolution. The results of experiment on board of "BION-11" enable us to conclude, that 5'-nucleotides are predominantly formed by action of full spectra of space energy sources on dry thin films of nucleoside plus inorganic phosphate. Other nucleotides (2'- and 3'-) and cyclic ones, such as 2'3'cAMP and 2'3'cCMP also have been found in the investigated films.
So, the organic compounds, which had been delivered on the primordial Earth would have had a very complex structure and reached the second stage of the chemical evolution ­ polymerization.

PROCESSES THAT "COOK" THE INTERIOR OF A COMETARY NUCLEUS

G. TANCREDI AND A. SANCHEZ

Depto. Astronomia .
Fac. Ciencias - Montevideo,
URUGUAY

The low temperature and low pressure enviroments where comets were formed led to the hypothesis that the water ice was in a amorphous state, at least at the time of formation. Furthermore, there were other volatiles that may have been trapped in the amorphous matrix, like CO or CO2. Other constituent of the cometary material is the dust: silicates with minor fraction of other rocky components like radioactive elements. The interior of a cometary nucleus suffered two thermochemical process in very different time-scales: i) the radioactive heating since the time of formation and lasting for several millions of years; ii) the phase transition from crystalline ice triggered by the sun heating at every perihelion passage. There has been a continuing improvement in the modelling of the thermochemical process governing the cometary interior as well as new results regarding key parameters of these models; like the heat conductivity of the amorphous ice, the dust to gas ratio, the porosity of the nucleus, the amount of trapped gas like CO, etc.In view of these results, we come back to the problem of the maximum temperatures attained in the interior of the comet, in particular we discuss the possibility to reach the melting condition.

SPANISH PHOTOGRAPHIC METEOR NETWORK: STATUS AND FUTURE PROSPECTS.

JOSEP Mª TRIGO-RODRIGUEZ 1,2, JUAN FABREGAT1 JORDI LLORCA3, ALBERTO CASTRO-TIRADO4.

1. Departamento Astronomía y Astrofísica, Universidad de Valencia.
2. Dept. Ciencias Experimentales, Universidad Jaume I.
3. Dept. Química Inorgánica, Universidad de Barcelona.
4. Laboratorio de Astrofísica Espacial y Física Fundamental (LAEFF-INTA) and Instituto Astrofísica de Andalucía (IAA-CSIC).

This poster reports the birth of the Spanish Photographic Meteor Network (SPMN) a project initiated in the East of Spain in 1997. During 1998 we extended this initiative around Spain with the help of new meteor workers, professional or amateur astronomers, coinciding with the high activity associated to several stream's outbursts. From 1999 our activities have been increased with the main aim of develop a continuous Fireball Network in Spain in the near future and to obtain detailed information on meteor events. Today the SPMN is a solid project under the auspices of three Universities (University Jaume I, University of Valencia and University of Barcelona) and one Space Institute (Catalonian Institute for Space Studies). In our network also participate El Arenosillo Observatory (LAEFF-INTA). We present here some of our more reliable fireball orbits obtained during the last years.