CHEMICAL EVOLUTION OF SIMPLE BIOMOLECULES IN HYDRODYNAMICALLY COLLAPSING INTERSTELLAR GAS IN PRESENCE OF GRAINS.

Kinsuk Acharyya
Centre for Space Physics
P-61 Southend Garden, Garia, Kolkata 700084, INDIA

ABSTRACT
We present time dependent results of how interstellar grains help to produce H2 molecules in the interstellar gas. We include standard size distribution of grains in our computation. We compute saturation ratio of H:H2 on grain surfaces and in gas phase respectively at various radii of a typical interstellar cloud. We then compute the time evolution of the lighter bio-molecules as a result of the hydrodynamic collapse of the cloud in presence of the grains and show that grains affect the abundances of lighter bio-molecules very significantly.

ON THE QUESTION OF CONVERGENT EVOLUTION IN BIOCHEMISTRY

Afolabi Akintunde AKINDAHUNSI (1,2) and Julian CHELA-FLORES (3)
(1) Department of Biochemistry,
Biophysics and Macromolecular Chemistry
University of Trieste, Via Giorgieri, 1,
I-34127, Trieste, Italy

(2) Permanent Institute: Department of Biochemistry
Federal University of Technology, Akure, Nigeria

(3) The Abdus Salam ICTP, I-34014, Trieste, Italy and
Instituto de Estudios Avanzados, Caracas 1015A, Venezuela.

ABSTRACT
Since the time of Darwin, biologists have gradually learnt that convergent evolution is an ubiquitous phenomenon, since it occurs at the levels of morphology, physiology and behavior (Eisthen and Nishikawa, 2002). The case has been particularly well documented at the multicellular level. A good example is the wings of the bat, birds and those of the extinct pterodactyl. But with the advent of molecular biology in the middle of last century, evolutionary convergence (otherwise known as homoplasy) has been well documented at the microscopic level (Pace, 2001). Evolutionary convergence is significant for the central problem of astrobiology (Chela-Flores, 2003). Since all forms of life known to us are terrestrial, it is relevant to question whether the science of biology is of universal validity (Dawkins, 1983), and whether the molecular events that were precursors of the origin of life are bound to occur elsewhere in the universe wherever conditions are similar to the terrestrial ones. Natural selection, a mechanism for evolution, is a consequence of the competing drives for self-replication that are manifest in all organisms. Convergence is a significant evolutionary phenomenon, which implies a strong role for natural selection. Convergent evolution is a principle, which provides insights into biological evolution in extraterrestrial environments. It is manifest at the active sites of enzymes, in whole proteins, as well as in the genome itself. In this paper, we discuss evolutionary convergence in its classification into functional, mechanistic, structural and sequence convergence (Doolittle, 1994), which should help us in the context of astrobiology, particularly in the urgent problem of defining bioindicators that may be used in the exploration of the solar system.

References
Chela-Flores, J. (2003) Testing Evolutionary Convergence on Europa. International Journal of Astrobiology (Cambridge University Press), in press.
Dawkins, R. (1983) Universal Darwinism, in Evolution from molecules to men, Bendall, D.S. ed., London, Cambridge University Press, pp. 403-425.
Doolittle, R. F. (1994) Convergent evolution: the need to be explicit. Trends Biochem. Sci., 19, 15-18.
Eisthen, H.L. and Nishikawa K.C. (2002) Convergence: Obstacle or Opportunity? Brain Behav. Evol. 59 (5-6), 235-239.
Pace, N. R. (2001) The universal nature of biochemistry. Proc. Natl. Acad. Sci. USA 98, 805-808.

ASTROBIOLOGY AND BIOCENTRISM

ROBERTO ARETXAGA, Ph.D.
Philosophy Department, School of Philosophy and Educational Sciences
University of Deusto, Bilbao, Spain

ABSTRACT
The term "biocentrism" may be defined from three different perspectives: philosophical, environmental and astrobiological. Some of the main implications of the philosophical and environmental usage of the term will be considered with respect to astrobiology. In this context, biocentrism will be defined and assessed. We will also consider the impact of its decline as a result of the contributions of this new science. This will make it necessary for scientists and humanists to collaborate more if they are to approach, understand and incorporate in the best possible way the impact and consequences that the aforementioned decline is going to have on all aspects of our culture and society.

References
Aretxaga, R. (2003) "La ciencia astrobiológica. Un nuevo reto para el humanismo del siglo XXI". In Humanismo para el siglo XXI. Congreso Internacional (Bilbao, marzo 2003). Proceedings (CD-Rom), University of Deusto, Bilbao, 2003.
Billingham, J., Heyns, R., Milne, D., Doyle, S., Klein, M., Heilbron, J., Ashkenazi, M., Michaud, M., Lutz, J. and Shostak, S. (1994) "Social Implications of the Detection of an Extraterrestrial Civilization", SETI Press, SETI Institute, California. pp. 146.
Chela-Flores, J. (1998) "Search for the Ascent of Microbial Life towards Intelligence in the Outer Solar System". In: Origin of the life in the universe. Eds. R. Colombo, G. Giorello and E. Sindoni. Edizioni New Press: Como. pp. 143-157. Reference 32.
Chela-Flores, J. (2001) "La astrobiología, un marco para la discusión de la relación hombre-universo". Principia (Universidad Centro Occidental L. Alvarado, Barquisimeto, Venezuela), 18 (2001) pp. 12-18.
Chela-Flores, J. (2003) "Marco cultural de la astrobiología". In: "Astrobiología y Filosofía". Letras de Deusto (University of Deusto, Bilbao, Spain), Nº 98, Vol. XXXIII, enero-marzo de 2003: pp. 199-215.
Norton, Bryan G. (1984) "Environmental Ethics and Weak Anthropocentrism", Environmental Ethics 6 (1984) pp. 131-148.
Dick, S. J. (1984) Plurality of Worlds: The Origins of the Extraterrestrial Life Debate from Democritus to Kant. Cambridge University Press, 1984.
Tough, A. (2000) Workshop "When SETI Succeeds: The Impact of High-Information Contact", Foundation for the Future, Washington, USA, pp. 182.

THE DISCOVERY OF ORGANICS IN EARTH'S DEEP MATERIALS (SUB-BASEMENT RED PALEOSOLS) DRILLED IN THE NORTH PACIFIC (ODP LEG 197): IMPLICATIONS FOR ASTROBIOLOGY RESEARCH.

Rosalba Bonaccorsi (1) & Rocco L. Mancinelli (2)
(1) Dip. di Scienze Geologiche, Ambientali e Marine (DiSGAM), University of Trieste Via E. Weiss, 2 34127, TS Italy < bonaccor@univ.trieste.it >
(2) SETI Institute, NASA Ames Research Center, Mail Stop 239-4, Moffett Field, CA 94035, USA <rmancinelli@mail.arc.nasa.gov>

ABSTRACT
Although the recovery of sub-basement red paleosols dates back to the 1980's [1-2], the search for organics preserved in material retrieved from such a depth has been systematically initiated during the Ocean Drilling Program (ODP) Leg 197 (Emperor Seamounts, north Pacific Transect) [3].
We present here evidence that the composition of organics from extremely deep soils in isolated diagenetic settings [3-4] makes them potential excellent Mars analogs [5]. Additionally, the same samples could be used as suitable test beds to develop hypotheses for future Deep Earth biosphere research [4].
Identifying organics throughout earth's subsurface materials has implications relevant to Astrobiological research. In fact, the detection of organics buried deep beneath the surface of a planet is a fundamental step to constrain the presence and evolution of life on that planet. This is especially true for Mars where high near-surface UV flux, low atmospheric pressure (i.e., 4-10 mbar) and very low surface temperatures (e.g., down to -125 C) are likely to prevent the stability and flourishing of near-surface present-day life. Nevertheless, first-rate biosignatures and organics could be preserved with depth on Mars [5-6], and/or potentially (meta)stable microbial communities still be resilient at some deeper locations on the planet.
Early Eocene(?) red paleosols were cored deeply beneath volcanic basement at Site 1205 (Nintoku Seamount, 41° 20.00'N; 170° 22.70'E) and Site 1206 (Koko Seamount, 34° 55.55'N; 172° 8.75'E). These Fe oxides/oxyhydroxide-rich soil interbeds represent the weathering product (tropical conditions) of mafic igneous rocks and flood basalts (Breccia and Plagioclase-Olivine basalts) and also contain hematite, magnetite, various clay minerals and palagonite [3]. Very importantly, they contain very low, but reliable amounts of total organic carbon (i.e., TOC = 0.12-0.01%, ± 0.02%, N = 36) [3-5] and ultra-low nitrogen (i.e., 0.01 to 0.006, N-tot wt%). Furthermore, their stable isotope signature (_13C_org = ~ -25 to ~ -26 , and negative to positive _15N_tot) would suggest mixed sources of organics (i.e., plant and primary/secondary bacterial) and microbial-induced processes (e.g., nitrogen fixation, nitrification, and denitrification). However, the existing elemental and stable isotope data-set [3-4] need to be compared with results obtained from standard microbiological techniques in order to establish the potential for those Eocene soils to serve as a suitable analog for a possible Mars near-surface to deep biosphere [5].
More specifically: a) Preservation of organic traces in a deep earth system (no sun light, and reducing conditions) which remained isolated and decoupled from the ocean and the atmosphere for millions of years. b) The soil sequences are difficult to access (they are deeply buried -300 to -350 metres below volcanic basement, [e.g., 3]) and sample (only from deep drilling; eg., [7]), and thus relatively rare in geologic collections. c) The soil samples underwent initial heating by overrunning lava flows that may have partially altered/destroyed their original composition (e.g., organics and former microbial communities) throughout [5]. These heating effects could be understood on those soil samples and then applied to Mars.
Finally, integrating microbial ecological and geochemical studies on the ODP soil samples to develop a model for understanding what types of organic material may serve as potential biomarkers for a future Mars deep drilling project. This combination would indeed, would help shape future exploration and deep to near-surface drilling missions (i.e., soils sampling during landed missions) on Mars [8].

References
[1] Karpoff, A.M., 1980. Init. Repts. DSDP, 55: Washington, 707-711. [2] Shipboard Scientific Party, 1993a Site 871, Proc. ODP, Init. Repts. 144: College Station, TX (Ocean Drilling Program), 41-103. [3] Tarduno, J.A., et al., 2002. Proc. ODP, Init. Repts., 197 [Online]: http://www-odp.tamu.edu/publications/197_IR/197ir.htm. [4] Bonaccorsi, R., 2002. EOS Trans AGU, 83(47), Fall Meet. Suppl. Abstract. [5] Bonaccorsi, R., et al., 2002 Bioastronomy 2002: Life Among The Stars Conference, 8-12 July 2002, Great Barrier Reef, Australia]. (Abstract). [6] Kanavarioti, A, and Mancinelli, R.L. 1990. Icarus. 84:196-202. [7] http://www.iodp.org:16080/iwg. [8] Mancinelli, R.L, 2000. Accessing the Martian deep sub-surface to search for life. Planet. Space Sci., 48:1035-1043.

EXPERIMENTAL STUDY OF THE DEGRADATION OF COMPLEX ORGANIC MOLECULES. APPLICATION TO THE ORIGIN OF EXTENDED SOURCES IN COMETARY ATMOSPHERES.

Fray N., Bénilan Y., Cottin H., Gazeau M.-C., and Raulin F.
LISA, UMR 7583, Universités Paris 7 and Paris 12
fray@lisa.univ-paris12.fr / Fax : 33-(0)1.45.17.15.68

ABSTRACT
Some molecules or radicals observed in cometary atmospheres present so-called "extended sources". It means that their distribution in comae cannot be explained by a direct sublimation from the nucleus, but rather by a production in the coma. The origin of those extended sources is still an unsolved question.
Some complex organic molecules, like HCN polymers, HMT (C6H12N4) or polyoxymethylene [formaldehyde polymers: (-CH2-O-)n], are sometime evoked as possible parents for the extended sources of CN and H2CO respectively. These polymers in solid state on cometary grains could release volatiles through thermal and photolytic degradation.
We have developed an experimental program in order to study the chemical reactions of degradation of solid polymers by UV irradiation and heat. The production of resulting small gaseous molecules is studied through MS, GC and IR analyses and provide identification of the degradation products and the determination of the photo-degradation quantum yields or the thermal degradation kinetics. Those fundamental data are then included into a model of the outer coma in order to interpret observations.
We will present our latest results on the degradation of HCN polymers, HMT and polyoxymethylene. We show that the degradation of organic polymers is a possible source of molecules and radicals which present an extended source. And thus we can infer the presence of complex organics in the nucleus from the modelling of the extended source phenomenon.

OBSERVATION, MODELING AND EXPERIMENTAL SIMULATION : UNDERSTANDING TITAN'S ATMOSPHERIC CHEMISTRY USING THESE THREE TOOLS

J.-M. Bernard (1) , P. Coll (1) , A. Jolly (1) , Y. Bénilan (1) , G. Cernogora (2) , C.D. Pintassilgo (3) , F. Raulin (1)
(1) LISA, UMR 7583, France, e-mail: bernard@lisa.univ-paris12.fr
(2) S.A., UMR 7620, France
(3) Centro de Fisica dos Plasmas and Departamento de Fisica, Lisboa, Portugal

ABSTRACT
Since several years, Titan, the largest satellite of Saturn, is studied like an exo/astrobiological object. Its dense atmosphere is made of nitrogen and a few percent of methane. Since Miller's experiment, we know that N2/CH4 atmospheres have a strong interest for prebiotic organic chemistry. Under the energetic particles (coming from solar radiations and Saturn magnetosphere), both hydrocarbons, nitriles (like HCN, precursor of amino-acids) and aerosols are produced in notable amounts.
However, the chemistry of this object is very difficult to understand. The coupling between modeling, experimental simulations and observations allows to have a better knowledge about this satellite.
At LISA, in France, the atmospheric chemistry on Titan is reproduced during laboratory simulation experiments since several years. In order to simulate as well as possible Titan's atmosphere, these simulations are done by initiating a glow discharge in a continuously flowing N2/CH4 mixture at low temperature. Aerosols, gas, radicals and ions produced in the reactor can be analyzed by different techniques.
First I will describe the experimental simulation. Next I will present the latest results about this experimental simulation and their implications on modeling and observations.

SEARCH FOR BACTERIAL WASTE AS A POSSIBLE SIGNATURE OF LIFE ON EUROPA

Aranya B Bhattacherjee*
INFM, Dipartimento di Fisica E.Fermi, Universita di Pisa, Via Buonarroti 2, I-56127, Pisa, Italy
and
Julian Chela-Flores
The Abdus Salam International Centre for Theoretical Physics, Trieste, Italy and Instituto de Estudios Avanzados, Caracas 1015A, Venezuela.
* Permanent Institute: Department of Physics, A.R.S.D College, University of Delhi, Dhaula Kuan, New Delhi-110021, India.

"It is strange that as "more intelligent beings", we try to understand the 'origin of life' but when we merge back into our creator, then we will understand the 'why' of the creation, but we know then, we will not wish to know this any longer"

(Original quotation from the dialogues
of the philosophical poem
"Bhagawad-Gita", 1st-2nd century AD)

ABSTRACT
If Europa has a liquid water ocean beneath the outer ice crust as a result of interior volcanic heating, then it is possible that hydrothermal vents located on the seafloor may provide the necessary conditions for simple ecosystems to exist. Bacteria's present in the water are known to extract nutrients directly from sulphur via chemosynthesis, making sunlight and oxygen unnecessary. Geochemical models have been proposed to explore the possibility that lithoautotropic could be a source of metabolically useful chemical energy for the production of biomass at putative Europan hydrothermal systems. In the absence of oxygen, anaerobic decomposition takes place in these hydrothermal vents. As a result of putrefactive breakdown of organic material (proteins), some elements are produced, such as hydrogen sulfide, methane, ammonia and mercaptans (any sulphur containing organic compound. Evidence has been provided for the presence of mercaptans on the surface of Europa using reflectance spectra returned by the Galileo near infrared mapping spectrometer (NIMS). Absorption was observed at 3.88 mm, attributed to S-H bond of mercaptans, which could be the result of extant bacterial activity. A major scientific question to be answered about the possible existence of life is: If biological process such as methanogenesis and putrefaction are at work then how do they affect observable or measurable quantities? What would be the best way to detect these organisms? Thus the detection and characterization of any bacterial excreta is an integral part of our search for evidence of life on Europa. Any point on the surface of Europa which exhibits properties typical of contamination by bacterial waste should serve as a window to the underlying ocean. Before embarking upon any ambitious project, it would be helpful if we could test this proposal in the laboratory by mimicking the surface of Europa. This could be done by allowing for bacteria to grow for a prolonged period in an artificial pond and then freezing the water. Subsequently one can measure the various physical and chemical properties on the surface of this pond. This will help to understand what we should expect on the surface of Europa and whether the marcaptan signal observed by NIMS can be attributed to the presence of micoorganisms under the forzen surface of Europa. The dry valley lakes of southern Victoria Land of Antarctica (77°S, 163°E) are perennially ice-covered. Surface ice has endogenic sulphur compounds deposited by processes which could be conjectured to be analogous to the ones we describe here.

ORIGIN AND EVOLUTION OF METABOLIC PATHWAYS

Matteo Brilli and Renato Fani*
Dipartimento di Biologia Animale e Genetica,
Via Romana 17-19, 50125 Firenze, Italy
*tel +39 055 2288244
fax +39 055 2288250
email r_fani@dbag.unifi.it

ABSTRACT

The building up of metabolic pathways represented a crucial step in molecular and cellular evolution. In fact, if the Oparin's idea on the origin of life is correct, we can imagine that the exhaustion of the prebiotic supply of amino acids, bases, and other compounds must have imposed an important pressure favouring those primordial heterotrophic cells which became capable of synthesizing those molecules. Thus, the emergence of biosynthetic pathways allowed primitive organisms to become increasingly less-dependent on exogenous sources of organic compounds.
Several different theories have been suggested accounting for the establishment of metabolic routes. These explanations include: i) the retrograde hypothesis (Horowitz, 1945; 1965) according to which the present biosynthetic pathways were organized stepwise and backwards from the final metabolites of the pathways; ii) the possibility that at least some biosynthetic routes evolved forwards (Granick, 1965); iii) the idea that metabolic pathways appeared as a result of the gradual accumulation of mutant enzymes with minimal structural changes (Waley, 1969); and iv) the patchwork theory, according to which metabolic routes are the result of the serial recruitment of relatively small, inefficient enzymes endowed with broad-specificity that could react with a wide range of chemically related substrates (Ycas, 1974; Jensen, 1976).
The origin and evolution of metabolic pathways can be studied by sequence comparisons and by the "directed evolution" experiments. The comparative analysis of different metabolic routes (nitrogen fixation, bacteriochlorophyll and histidine biosynthesis) suggested that: i) in the course of molecular evolution different mechanisms might have concurred in the arisal of new metabolic abilities; ii) gene duplication is a major force in genome evolution and paralogous duplications of DNA stretches may have played an essential role in shaping the main metabolic pathways during the early stages of molecular evolution; iii) duplication may concern gene portions, coding for protein domains and motifs, entire genes, and entire operons.
Case study 1. Nitrogen fixation: a cascade of gene and operon duplication.
Nitrogen fixation is a complex metabolic process involving several genes (nif), but very little is known about its origin and evolution. A detailed analysis of nif gene products revealed that nifDK and nifEN, encoding the a and b subunits of nitrogenase, and the components of the NifEN enzymatic complex, involved in FeMo-Co biosynthesis, belong to a paralogous gene family. This analysis also permitted to trace their possible evolutionary history; according to the proposed model the four genes are the result of two successive duplication events, very likely predating the appearance of the Last Universal Common Ancestor (LUCA). The first paralogous duplication event involved an ancestral gene (encoding a low specificity ezyme able to catalyze several reactions) leading to a bicistronic operon which, in turn, underwent a paralogous operon duplication event originating the ancestors of the present-day nifDK and nifEN operons. A further analysis revealed that these genes exhibited a significant degree of sequence similarity to the bacterial bchB and bhcN genes, which code for two components of protochlorophyllide reductase, and to the products of bchY and bchZ, encoding two components of chlorin reductase. Data obtained strongly suggested that bchB, bchN, bchY, and bchZ belong to the nifDKEN paralogous gene family, that they might have arisen from two successive duplications involving one of the two operons above mentioned, and established an evolutionary link between nitrogen fixation and bacteriochlorophyll biosynthesis.
Case study 2. Histidine biosynthesis: a paradigm for the study of the origin and evolution of metabolic pathways.
The histidine biosynthetic pathway is one of the best characterized anabolic pathway. There are many clues indicating the antiquity of this pathway, suggesting that it might have been completely assembled before the appearance of the last common ancestor and that its origin probably started in the early stages of molecular evolution. The availability of completely sequenced genomes from different (micro)organisms belonging to the three cell domains permitted a deep analysis of his genes, which revealed that paralogous gene elongation and duplication events occurred frequently and that they played a major role in shaping the pathway. Moreover, we found that (at least) seven his genes underwent different gene fusion events in some bacterial and eucaryal lineages, but not in Archaea, suggesting that the ancestral his pathway was constituted by mini-genes which underwent different rearrangements during evolution. Data obtained also suggested that some his genes are the descendants of genes encoding less specific enzymes, supporting the Patchwork hypothesis.

TEN YEARS OF TRIESTE CONFERENCES ON CHEMICAL EVOLUTION AND ORIGIN OF LIFE: A PICTORIAL OVERVIEW

Mohindra S. Chadha
Mumbai; INDIA

ABSTRACT
In this presentation, aimed at re-capitulation of ten years of Trieste Conferences, on Chemical Evolution and Origin of Life, an attempt will be made to highlight the Scientific, Educational and Cultural aspects (through pictures taken) at the six Conferences held so far. To have been present at the First Trieste Conference held in October 1992 and now at the Seventh Conference and all the others in between has provided with a perspective which I wish to share.
The first Trieste Conference which was the brain-child of Prof. Abdus Salam and Prof. Cyril Ponnamperuma was held in October 1992 in Trieste under the joint umbrella of International Atomic Energy Agency and the United Nations Educational, Scientific and Cultural Organisation and was attended by both the stalwarts. This inter-disciplinary international conference was entitled Chemical Evolution: Origin of Life and defined the scope and objectives of this novel effort.
The second Trieste Conference (Oct. 1993) was entitled Chemical Evolution: Self-organisation of the Macromolecules of Life and was dedicated to Cyril Ponnamperuma on his 70th birthday. At this conference many of the erstwhile collaborators of Cyril Ponnamperuma participated and the proceedings of the conference were edited by Julian Chela-Flores and Cyril Ponnamperuma's former collaborators namely: Mohindra S. Chadha, Alicia Negron-Mendoza and Tairo Oshima.
The third Trieste Conference (Sept. 1994) was entitled Chemical Evolution: Structures and Model of the First Cell and was designated as the Alexander Ivanovich Oparin 100th Anniversary Conference. This was the best attended conference of the three Trieste conferences till then and the presentations on planetary, extraterrestrial and interstellar conditions broke a lot of new ground.
The fourth Trieste Conference (Sept. 1995) was the first conference of the series which was held after the untimely and sudden demise of Cyril Ponnamperuma, the co-founder of this series of conferences. He was involved in the early part of the preparation of this conference but unfortunately was not to live to witness it's deliberations. Such is Life! The Conference was entitled Chemical Evolution: Physics of the Origin and Evolution. The Conference was aptly dedicated to the memory of Cyril Ponnamperuma. There were general overview presentations by John Oro on Cosmic Evolution and Sidney Fox entitled Experimental Retracement of Terrestrial Origin of An Excitable Cell: Was it Predictable? In a special session, homage was paid to Cyril Ponnamperuma and excerpts of letters received from various academies, institutions and admirers of Cyril Ponnamperuma were read out. A touching note received from his wife (Valli) and daughter (Roshini) was also shared.
The fifth Trieste Conference (Sept. 1997) was entitled Exobiology, Matter, Energy and Information in the Origin and Evolution of Life in the Universe and was dedicated to the memory of Abdus Salam the co-founder of the Trieste series of Conferences and Director of ICTP, who had unfortunately passed away after prolonged illness. This conference had as many as 12 sponsors and was largely attended. The highlights were talks by: Chela-Flores entitled: Abdus Salam - From Fundamental Interactions to the Origin of Life. The Abdus Salam lecture by John Oro entitled: Cosmocological Evolution ­ A Unifying and Creative Process in the Universe. The Cyril Ponnamperuma lecture by Frank Drake, namely The Search for Intelligent Life in the Universe. The opening lecture: The Theory of Common Descent by Richard D. Keynes and a Public Lecture: Are We Alone in the Universe by Paul Davies. This Conference was unique in focussing on Exobiology in general and on Comets, Planets and the Interstellar Medium in particular.
The sixth Trieste Conference (Sept 2000) was entitled First Steps in the Origin of Life in the Universe and was dedicated to Giordano Bruno whose intuitive concepts have relevance to current enquiries related to the First Steps in the Origin of Life in the Universe. This conference had as many as 11 sponsors. The conference featured a special lecture by Stanley Miller who presented the possibility of Peptide Nucleic Acids as A Possible Primordial Genetic Polymer. The Abdus Salam lecture entitled: Physics and Life was delivered by Paul Davies and the Cyril Ponnamperuma lecture by J. William Schopf entitled: Solutions to Darwin's Dilemma: Discovery of the Missing Precambrian Records of Life. All the three presentations were quite scintillating. A new feature of the sixth Trieste Conference was inclusion of a section entitled: Historical Aspects which featured work of Sidney Fox (by Aristotle Pappalis), Theories on Origins of Life between 1860-1900 (by F. Raulin-Carceau) and Reminiscences- Pont-a-Mousson- 1970 to Trieste-2000 (by Mohindra Chadha).
The other main topics of the conference dealt with Life without Starlight and questions asked were: Can Life Originate in the absence of Starlight? In a Pre-Dinner lecture entitled NEW PARADIGMS OF SETI, Frank Drake brought the audience up to date in this challenging and thrilling venture of scientific endeavour. The Sixth Trieste conference had all the embellishments of the previous conferences as envisioned by the two founders (Abdus Salam and Cyril Ponnamperuma).The Keynote addresses given by leading researchers in their respective fields were authoritative. Many young scientists from both the industrialised countries and those from developing countries, coming from different parts of the Globe enriched themselves greatly from their participation in this conference as the earlier ones. In all over 500 participants have benefited from the Trieste Conferences so far.
The last Six Trieste Conferences have brought together scientists (both experimental and theoretical), philosophers and theologians of repute. The intellectual content of the discussions and many debates has been of a high order and the future for these inter-disciplinary international deliberations seems to be very bright. Our thanks are due to Julian Chela-Flores, Tobias Owen and Francois Raulin who have continued to carry the torch lit by Cyril Ponnamperuma and Abdus Salam. The sponsors and the organising committee also deserve an applause. This tribute to the activities of a decade of Trieste Conferences on Chemical Evolution and Origin of Life will be presented through a Pictorial Overview.

FATE OF GLYCENE AND OTHER COMPLEX BIO-MOLECULES DURING INTERSTELLAR COLLAPSE

Sandip K. Chakrabarti
S.N. Bose National Centre for Basic Sciences and Centre for Space Physics
P-61 Southend Garden, Garia,
Kolkata 700084,
INDIA

ABSTRACT
We present results of time evolution of complex bio-molecules including glycene, amino acid etc. through a chemical evolution of over 430 species in a collapsing interstellar cloud. We include grain and surface chemistry for efficient evolution of lighter elements at each shell of the cloud. We include effects of radiative processes as well. Our conclusion is that glycene should have a sigificant abundance and it should be detectable.

A FUNCTIONAL AND SELF-REFERENTIAL MODEL FOR THE GENETIC CODE

Romeu Cardoso Guimarães1, Carlos Henrique Costa Moreira2
Univ. Federal Minas Gerais, Inst. Ciências Biológicas, Dept. Biologia Geral1, Dept. Matemática2 31270.901 Belo Horizonte MG Brasil. TelFax +55-31-3499.2570; romeucg@icb.ufmg.br

ABSTRACT
The structure of the genetic code is based on palindromic pairs of anticodons, where the central and 3' bases (principal dinucleotides, pDiN) are complementary to each other but the 3' bases are paired with the wobble bases: 5'-central-3' : 3'-central-5'. The matrix is divided into homogeneous (Ho; RR:YY quadrants) and mixed (Mx; RY:YR quadrants) pDiN sectors. Sectors are composed of axial (Ho, AA:UU, GG:CC; Mx, AU:UA, GC:CG) and non-axial (Ho, GA:CU, AG:UC; Mx, AC:UG, GU:CA) pDiN boxes. The degeneracy distribution follows (1) in the axial boxes, the pDiN base composition and thermodynamic stability: core boxes are simple (GG Pro:CC Gly, GC Ala:CG Arg), the tips complex (AA Phe, Leu:UU Asn, Lys; AU Ile, Met:UA Tyr, X) and (2) the central base type, with purine precedence, in non-axial boxes: central R simple (GA Ser, AG Leu, AC Val, GU Thr), central Y complex (in the pair order: CU Ser, Arg; UC Asp, Glu; UG His, Gln; CA Cys, Trp, X). Complex boxes also obey the purine precedence rule. 5' R anticodons were maintained by first occupants and 5' Y conceded to new occupants: YAA and YCU to the hexacodonic expansions of Leu and Arg; YAU to Met and fMet, YUA to X, and YCA to Trp and X; in the other central U boxes, YUG to Gln, YUC to Glu and YUU to Lys.
Our model for generation of the code indicates: it was preceded by the peptidyl-transferase activity; attributions were gradually added; tRNA dimers (palindromic pairs) were formed and directed the order of entry of attributions. In an early stage, the mRNA function was accomplished either by one member of a pair of tRNAs, entering the ribosome as tRNA dimers, or by a ribosomal correlate of codons or anticodons, in which case tRNA dimers would not enter the ribosome. In the absence of mRNA, protein synthesis was not a process of translation and was self-referential (referring only to the existing components of the system); there were also no problems with non-sense or ambiguous codons. After the entrance of mRNA, protein synthesis became translational and referring to the larger system which produced the mRNA.
Among the first functions of peptides produced were those of belonging to the protein synthesis system, being intrinsically stable and RNA binders, so that RNA became stabilized as ribonucleoprotein. Evolution of protein conformations was from coils and turns to helices then strands. Stage 1. First attributions were of the hydropathy correlation outliers, (GlyCC:GGGly, the latter displaced afterwards by Pro, and SerGA:CU); these are now catalyzed by synthetases class 2 (aRS2) but could have started ribozymic; all other attributions obey the hydropathy correlation. Stage 2 completed the Ho sector: AspUC was followed by the aRS1 pair GluUC:AGLeu; AsnUU, derived from Asp, was followed by the unique LysUU:AAPhe pair of bulky amino acids (Lys may be class 2 or 1, PheRS2 acylates at 2', as done by all aRS1). Stage 3 took AlaGC:CGArg and the aRS1 pair ValAC:UGGln, after HisYUG concession to Gln. Stage 4 took ThrGU:ACCys, Trp, then the aRS1 pair Ile, MetAU:UATyr. Of the 8 pDiN pairs, 2 are aRS class discordant: Ala/Arg and Thr/Cys, Trp.
Punctuation was achieved non-specifically in Stage 2, at the Ho axis, through polar organization of protein sequences, concentrating protein N-end-stabilizing (Gly, Pro) and -destabilizing (Lys, Phe) amino acids at the N-ends and C-ends, respectively. Specific punctuation (last step of Stage 4; tips of the Mx axis plus the CA box) was derived from the functional pDiN slippage of fMet to CAU and of the initiation codon to AUG, which led to interference of the CA (Cys, Trp box) and UA (Tyr box) with the pairing of fMet to the initiation codon. Therefore, X tRNAs were deleted.
Support: CNPq, FAPEMIG.

References
Guimarães 2001 In: First steps in the origin of life in the universe. Ed. J Chela-Flores, T Owen, F Raulin; Kluwer, Dordrecht, 91-4; Guimarães, Moreira 2002 In: Fundamentals of life. Ed. G Pályi, C Zucchi, L Caglioti; Elsevier, Paris, 249-76; Abstrs. 13th Internat. Conf. Orig. Life, Oaxaca MX 2002

PHOSPHATE IMMOBILIZATION BY OXIDE PRECURSORS AND PYRITE: IMPLICATIONS ON PHOSPHATE AVAILABILITY BEFORE LIFE ON EARTH

Fernando de Souza-Barros c, Ana C. Tessis d, Marisa B. M. Monte a, Ana C. P. Duarte a, José A. P. Bonapace b , Manoel R. do Amaral Jr. c,*, Raphael Braz Levigard d, Yonder A. Ching-San Jr. d, and Adalberto Vieyra d .

a Centro de Tecnologia Mineral (CETEM), Ministério da Ciência e da Tecnologia;
b Instituto de Química, Universidade Federal do Rio de Janeiro;
c Instituto de Física, Universidade Federal do Rio de Janeiro;
d Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro.

ABSTRACT
We present recent studies1, 2 based on the proposal that if the aqueous phosphorous-capture mechanism by iron oxide precursors was inhibited in prebiotic anoxic scenarios then soluble phosphates could have been more available than what is observed now. In this communication we examine trapping mechanisms of orthophosphate (Pi) and pyrophosphate (PPi) by Fe/S minerals. The attachment of (Pi) onto aggregates of iron-3 oxyhydroxide is compared with the one reported for the product of its condensation, PPi. The electrophoretic profiles of the Pi- and PPi-aggregate complexes reveal different pH-modulated interactions of the phosphorylated compounds with both the aggregate and its aqueous surrounding layers. On the other hand, pyrite sorption properties revealed that acidic media favoured Pi sorption whereas desorption is facilitated if mild alkaline conditions are present. In addition it has been observed that pyrite surface charges are sensitive to pH, Mg and SO4, thus affecting the Pi sorption properties. All together, these results support the hypothesis that the availability of Pi and PPi in prebiotic eras would have been modulated by prevailing trapping mechanisms in anoxic environments, by local variations of Mg and SO4 and by acidic¦mild-alkaline transitions.
1."Phosphate immobilization by oxide precursors: Implications on phosphate availability before life on Earth", Monte et al., Orig. Life Evol. Biosphere, in the press, 2003
2."Pyrite sorption and desorption of inorganic phosphates in primitive aqueous scenarios" Levigard et al., in preparation

# Author for correspondence, e-mail: fsbarros@if.ufrj.br; FAX: +55-21-2562-7368
* Deceased
Financial support: CNPq, FUJB-UFRJ, Finep (Brazil)

A MECHANISM FOR THE PREBIOTIC EMERGENCE OF PROTEINS:
THE ROLE OF PROTON GRADIENTS AND HIGH TEMPERATURE IN THE POLYMERIZATION OF
AMINO ACIDS EMBEDDED IN BILAYERS

P. De Vladar, Harold, 1*, Cipriani, Roberto,2**, Scharifker, Benjamin 3***,
and Bubis, Jose 4****

1 Centro de Biotecnologia, Fundacion IDEA, Caracas, Venezuela,
2 Laboratorio de Evolucion Morfologica, Departamento de Estudios Ambientales,
3 Laboratorio de Electmquimica, Departamento de Quimica,
4 Laborario de Quimica de Proteinas, Departamento de Biologia Celular,
Universidad Simon Bolivar, Caracas, Venezuela.

ABSTRACT
One of the most intriguing problems in the study of the origin of life is how complex macromolecules, and the processes in which they are involved, arise from simple molecules commonly available in prebiotic environments. The resulting prebiotic processes, either compartmentalized by amphiphilic molecules arranged in bilayers or spread across physical interfaces, become potential targets for selective mechanisms. The origin of complex macromolecules depends upon a variety of conditions abundantly described in models of prebiotic scenarios or worlds, such as those in which RNA and
thioesters dominate the fundamental processes of catalysis and polymerization. Autocatalysis and transmission of genetic information are the simultaneous functions of the ribonucleic acid precursor in the RNA world. On the other hand, spontaneous protein synthesis resulting from the polymerization of thioesters is the main process in a world dominated by these molecules. In any of these worlds, acidic, low-oxygen environments and extreme temperatures could have increased the velocity of chemical reactions and the stability of their products. In this study we propose that peptide formation might have occurred by the polymerization of amino acids embedded in amphiphilic bilayers. This polymerization could have been driven by a flux of protons through the bilayer and under conditions of high temperature. Our conceptual model involves a bilayered membrane separating two environments with different pH values at high temperatures. Given that under certain conditions, (a) differences in proton concentrations are capable to produce enough free energy to couple chemical reactions, and (b) the formation of peptide bonds will release OH ions, then a continuous influx of protons can be coupled with the formation of the peptide bond. Protons could bind to the hydroxile ions producing water and continuously displacing the reaction from equilibrium. We developed a mathematical model, using phenomenological equations and computer simulations, in which the proton flux is proportional to the polymerization of amino acids. From the results of these simulations, we estimated the size distribution of the oligopeptides and designed two possible experimental setups to test our theoretical results. One of these experiments is currently underway. The mechanism that we propose is a novel process that describes the early origin of proteins as macromolecules embedded in the bilayer, and links the origin of membrane proteins to the emergence of their functionality.

* E-mail: hperez@idea.org.ve
** E-mail: rcipri@usb.ve
*** E-mail: benjamin@usb.ve
**** E-mail: jbubis@usb.ve

A SURFACE-MEDIATED ORIGIN OF THE RNA WORLD: "BIOLOGICAL" ACTIVITIES OF CLAY-ADSORBED RNA MOLECULES

Marco Franchi, Elisa Biondi, and Enzo Gallori
Department of Animal Biology and Genetics, University of Florence - Florence (Italy)
marco.franchi@dbag.unifi.it

ABSTRACT
Studies carried out in different fields in the last twenty years have indicated that RNA could have played a pivotal role in the origin of life on Earth. In fact, the RNA molecule can act both as an information repository and as a catalyst necessary for cellular reactions ("ribozyme"). Moreover, its building blocks are distributed in many important metabolic pathways. These observations led to the concept of an "RNA World" during the firsts stages of the appearance of life.
If the RNA World ever existed, however, it seems improbable that it developed in "free" aqueous solution, due to the difficulty of polymerization reactions and the instability of polymers in an aqueous environment. In recent years, numerous observations have suggested the hypothesis of a surface-mediated origin of the RNA World. For example, clay minerals can favour the formation of considerably long oligonucleotides (Ferris et al., 1996) and can increase the environmental persistence of adsorbed nucleic acids (Gallori et al., 1998; Franchi et al., 1999).
At present, it is crucial to understand if and how RNA-like molecules adsorbed on clays, in the prebiotic environment, were in the right conditions to undergo chemical evolution leading to primitive biological self-replicating systems. In other words, to evolve these polymers must have been able to store genetic information, to specifically interact with other biopolymers, and to catalyse "biologically relevant" reactions.
In this communication, we present preliminary results of our studies on the biological activity of RNA molecules adsorbed on clay minerals, particularly with regard to: i) their enzymatic replication by RT-PCR (storage and transmission of genetic information); ii) their specific interaction with complementary RNA strands (interaction with other biopolymers); and iii) the catalytic activity of adsorbed oligonucleotides like "hammerhead" ribozymes (specific catalysis).

References
Franchi et al., 1999, Orig Life Evol Biosph 29: 297-315;
Ferris et al., 1996, Nature 381: 59-61;
Gallori et al., 1998, Symbiosis 25: 311-322.

SOME ENGINEERING CONSIDERATIONS ON THE CONTROVERSIAL ISSUE OF HUMANOIDS

Giancarlo Genta
Department of Mechanics, Politecnico di Torino,
C. Duca degli Abruzzi 24, 10129, Torino, Italy
giancarlo.genta@polito.it / fax: ++39 011 564 6999

ABSTRACT.
Many papers have been published in the past on the issue of the possible existence of humanoid extraterrestrial intelligence (ETI). The issue is very old: the first to take a firm stance on the subject was Galileo Galilei, who in his Istoria e dimostrazioni intorno alle macchie solari e loro accidenti (history and demonstrations on the sunspots and their details) (1613) states that he considered as a false and condemnable point of view to assume the existence of inhabitants on Jupiter, Venus, Saturn and the Moon, intending for 'inhabitants' animals like ours, and particularly men. But then he states that it is possible to believe that living beings and plants exist on the Moon and the planets, whose characteristics are not only different from those of the beings on the Earth, but also from what our wildest imagination can produce.
The prevalent opinion is now that the humanoid form is rather an exception than a rule.
The aim of the present paper is to consider an intelligent being as a sort of machine which has to perform a number of tasks, and to discuss whether the humanoid form and humanoid intelligence (intended as an intelligence accompanied by consciousness similar to those of humans) is dictated by them. While not intending to supply answers but only to formulate some problems, it is suggested that, although there is no doubt that a close relationship between our layout and our essence of intelligent beings exists, this is not enough to support any claim that the humanoid form is prevalent or even that it may exist outside our planet.

STUDIES ON COPPER ­ CHROMICYANIDE AS PREBIOTIC CATALYST

Kamaluddin and Shah Raj Ali
Department of Chemistry
Indian Institute of technology Roorkee, Roorkee ­ 247 667, India
(e-mail: kamalfcy@iitr.ernet.in)

ABSTRACT
Processes in chemical evolution must have involved several catalysts multifunctional in nature. We proposed that metal­cyanogen complexes of general formula M2[M(II) (CN)6] formed in the primeval seas might have catalysed a class of reactions essential for the origin and evolution of life. Based upon this hypothesis we have synthesized a series of metal cyanogen complexes and have shown them to have strong affinity towards several organic molecules of evolutionary importance.
Recently, we found that copper-chromicyanide, Cu3[Cr(CN)6]2. 14H2O possesses high adsorption capacity for ribose nucleotides and able to catalyze formation of disulfide bond through dimerisation of cysteine. Cu-chromicyanide was also found to facilitate conversion of fructose to pyruvaldehyde.
The present study suggests that the metal chromicyanides might have stabilized the organic molecules of prebiotic relevance and have catalysed a class of reactions essential for evolution of life.

COENZYMES IN EVOLUTION OF THE RNA WORLD

Mikhail S. Kritsky
A. N. Bach Institute of Biochemistry, Russian Academy of Sciences,
Leninsky Prospekt 33, Moscow 119071, Russia,
e-mail mkritsky@inbi.ras.ru

ABSTRACT
According to the RNA-world hypothesis, the early life was based on polyribonucleotides. That is, RNAs, which could have served as their own genes also performed catalytic functions in the absence of genetically ordered proteins. The analysis of both natural and selected ribozymes indicates that certain types of catalytic activities, e.g. oxidoreductases, are absent in polyribonucleotides. A possible way the RNA world could compensate for their absence to maintain a primitive metabolism was the attachment of nucleotide-like coenzymes to polynucleotides. Molecules such as flavin, pterin and nicotinamide coenzymes are structurally similar to canonic ribonucleotides and their ability to attach nucleic molecules both covalently and by non-covalent high-affinity binding have been experimentally demonstrated. Due to high activity of excited flavin, pterin and nicotinamide coenzymes in energy and electron transfer processes such attachment could have a dualistic significance for evolution. Since light dramatically elevates reactivity of these compounds, especially as redox catalysts, it is suggested that the presence in proto-RNAs of nucleotide-like coenzymes capable to perform photocatalytic functions could expand the repertoire of catalytic activities in the RNA world. On the other hand, the coenzyme attachment to polynucleotide had to increase risk of its coenzyme-sensitized degradation.

The support by Russian Foundation for Basic Research Grant 01-04-48268_ is appreciated

FACTORS AFFECTING THE GROWTH OF CHEMOLITHOAUTOTROPHS AND COMPLEX PHOTOAUTOTROPHS IN THE TROPICAL ANDEAN HIGH MOUNTAIN AND ITS EXOBIOLOGIAL IMPLICATIONS

Vicente Marcano 1, Paula Matheus 1, Alirio Balza1, Nelly Garcia 1, Rafael Navarro-Gonzalez 2, Christopher McKay 3, Wanda Davis 4 and Ernesto Palacios-Prü 1
1 Laboratorio de Biología y Química Evolutiva, Centro de Microscopía Electrónica,
Universidad de Los Andes, P. O. Box 163, Mérida, Venezuela.
2 Laboratorio de Química de Plasma y Estudios Planetarios, Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, México D.F, México.
3 Space Science Division, NASA Ames Research Center, Moffet Field, CA 94035 USA
4 SETI Institute- Space Science Division, NASA Ames Research Center, Moffet Field, CA 94035 USA

ABSTRACT
Surface and subsurface biota in the Andean high mountain are near the limits of photoautotrophic and chemolithotrophic life in the tropical region. Therefore, the relationship between N2, O2, and CO2 partial pressures, nitrogen fixation at soils, chlorophyll content, biological productivity (P/Pmax), and surface and subsurface thermal variation at the Andean high mountain was evaluated during the rainy and dry periods (2002 year) in order to determine the main factors affecting the growth of organisms living at that region. Climatic data including relative humidity and precipitation were obtained from 9 meteorological stations placed between 2448 and 4800 m at the Sierra Nevada de Mérida, Venezuela. These data were related to the metabolic activity (viz. ammonification, nitrification and CO2 assimilation) investigated in several plant species and soil microorganisms.
The obtained results suggest that the poor development of the plants correlated to the altitude could be a direct consequence of the low O2 and CO2 levels recorded in the higher altitudes, which reduce the photosynthetic activity, biological productivity, and the production of NO3- at the soils. Hence, chlorophyll content was inversely correlated to the increment of the altitude (2.3 x 10-2 mg Chl (a+b) g-1 dry weight m-1). Even chemolithotrophic bacteria cannot carry out the fixation process by nitrification at the snow zone (> 4700 m) because this process require aerobic conditions while the high concentrations of NH3 found in the snow zone correspond to the anaerobic nature of bacterial ammonification. Environments with a PO2 < 125 mbar showed a very low frequency and diversity of complex photosynthesis-based life forms due to the aerobic feature of bacterial nitrification. Altitudinal distribution of mean NO3- values revealed the existence of a "critical nitrogen-fixing zone" localized at timberline (~ 3250 m). Wider daily surface thermal oscillations (up to 52°C) were recorded between 3700 and 4270 m having 20 x 10-2 and 18 x 10-2 mbar of CO2 whereas lower or higher places showed reduced daily oscillations. Minimum PCO2 suitable for the occurrence of C3-advanced photosynthesis-based life forms in these environments had have values > 17 x 10-2 mbar corresponding to a mean temperature > 277 K and to a biological productivity rate P/Pmax ~ 0.27 whereas that minimum PCO2 suitable for the occurrence of C4-advanced photosynthesis-based life forms in those environments not exceeded values ~ 14 x 10-2 mbar. Further, a "critical photosynthetic boundary" also localized at timberline was defined having a mean surface temperature of ~ 11°C, P/Pmax ~ 0.64, and a PCO2 of ~ 21 x 10-2 mbar. On the other hand, reactions between N2 and H2O in the atmosphere surrounding lightning discharges can provide an important source of NOx even at altitudinal ranges where O2 is a minor atmospheric constituent (viz. snow zone), and therefore could allow the availability of fixed nitrogen for complex photosynthesis-based organisms living in the tropical Andean high mountain.

SPACE WEATHER AND SPACE CLIMATE: LIFE INHIBITORS OR CATALYSTS?

Mauro Messerotti,
INAF-Osservatorio Astronomico di Trieste,
Loc. Basovizza n. 302, 34012 Trieste, Italy
and Dept. of Physics, Trieste University.

ABSTRACT
In the present evolutionary stage the Sun as a star exhibits an almost stable radiation output, which is expected to endure on a long time scale and characterizes the Space Climate (SpC). On a short tine scale the solar activity perturbs instead the heliosphere by originating radiation outbursts, highly energetic particle emissions and magnetized plasma clouds, which characterize the Space Weather (SpW). A similar phenomenology can be typical in solar-like active stars, where it can be even more pronounced according to the star type, and strongly affects the planetary environments. In this work we speculate on the possible mutual role of SpW and SpC on life birth and evolution in a planetary environment, stressing the inadequacy of the basic concept of Habitability Zone and the relevance of SpW and SpC to life-genicity and life-sustainability.

SEARCHING FOR DYSON SPHERES IN THE MILKY WAY

Dante Minniti
Universidad Catolica;
Departamento de Astronomia
email: dante@astro.puc.cl
Casilla 306, Santiago
Phone +56 2 686 4946
Fax +56 2 686 4948
E-mail: dante@astro.puc.cl

ABSTRACT
A new search for Dyson spheres in the Milky Way is being carried out. This is based on massive datasets that cover different wavelengths, including optical (BVRI), near-IR (JHK), and mid-IR bands. The first results will be presented and discussed. The results are compared with similar surveys that have been made so far.

MARS-LIKE SOILS ON EARTH IN THE ATACAMA DESERT,
NORTHERN CHILE

Rafael Navarro-González1,2, Fred A. Rainey3, Paola Molina1, Danielle R. Bagaley3, Becky J. Hollen3, José de la Rosa1, Alanna M. Small3, Richard C. Quinn4, Frank J. Grunthaner5, Luis Cáceres6, Benito Gomez-Silva7, Arnaud Buch2, Robert Sternberg2, Patrice Coll2, Francois Raulin2, and Christopher P. McKay8,
1 Laboratorio de Química de Plasmas y Estudios Planetarios, Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, Apartado Postal 70-543, México D.F. 04510, México.
2 Laboratoire Inter-Universitaire des Systèmes Atmosphériques, UMR CNRS 7583, Universités Paris 12 & Paris 7, CMC, 61 Avenue du Général de Gaulle F 94010 Créteil Cedex, France.
3 Department of Biological Sciences, 202 Life Sciences Building, Louisiana State University, Baton Rouge, LA 70803, USA.
4 SETI Institute, NASA Ames Research Center, Moffett Field, CA 94035-1000, USA.
5 Jet Propulsion Laboratory, Pasadena CA, 91109, USA.
6 Instituto del Desierto y Departamento de Ingeniería Química, Facultad de Ingeniería, Universidad de Antofagasta, PO BOX 170, Antofagasta, Chile.
7 Instituto del Desierto y Unidad de Bioquímica, Departamento Biomédico, Facultad Ciencias de la Salud, Universidad de Antofagasta, PO BOX 170, Antofagasta, Chile.
8 Space Science Division, NASA-Ames Research Center, Moffett Field, CA 94035-1000, USA

 

ABSTRACT
The Viking Missions to Mars showed the Martian soil to be lifeless and depleted in organic material, and indicated the presence of one or more reactive oxidants. Here we report the presence of Mars-like soils in the extreme arid region of the Atacama Desert. Chemical and microbiological studies indicate the presence of organics at trace levels composed primarily of highly oxidized organic refractory material, extremely low levels of culturable bacteria and no recoverable DNA in the soil. We have simulated the Viking Labeled Release experiment in Atacama using formate and separate biological and non-biological isomers of alanine and glucose, and found that there is active decomposition of organics and it is entirely non-biological.

THE IMPORTANCE OF BIASED SYNTHESIS IN CHEMICAL EVOLUTION STUDIES.

A. Negron-Mendoza1, S. Ramos-Bernal1, and G Mosqueira2
1Instituto de Ciencias Nucleares, UNAM, A.P. 70-453, Mexico, D.F 04510
2Dirección General de Divulgación de la Ciencia, UNAM. Cd. Universitaria, A.P. 70-487, 04510
México D.F., México.

ABSTRACT
For the appearance of life, a physical and chemical preamble was needed. Today, there is a large variety of experimental data to support the hypothesis for the abiotic formation of organic compounds. Although much knowledge has been gain, still many questions remain.
One important factor in chemical evolution is biased synthesis. These led selectivity in the formation of organic compounds in order to reach the complex system that we call life.
In this paper, we propose a simple chemical system, decarboxylation of fatty acids, or deamination of amino acids that follow a preferential pathway over others possibilities in which both solid surfaces and radiation play an important role.
Fatty acids undergo a complex decomposition in the presence of radiation. Thus, radiation-induced reactions produce dimers and oligomeric products. Fatty acids present a very slow decarboxylation in the presence of montmorillonite alone. The reaction is accelerated at higher temperatures, but it is enhanced in many folds in the presence of ionizing radiation. Drastically, the normal way of radiation -decomposition reactions changes if the system contains a clay mineral.

ENANTIOSELECTION CAUGHT ON THE ACT: CHIRAL CONFORMERS FROM ACHIRAL COMPLEXES

Gyula Pályi,a Claudia Zucchi,a Roland Boese,b Lajos Bencze,c Luciano Caglioti,d
a Department of Chemistry, University of Modena and Reggio Emilia, Via Campi 183; I-41100 Modena, Italy; palyi@unimo.it
b Institute of Inorganic Chemistry, University of Essen, Universitätsstrasse 5-7, D-45117 Essen, Germany
c Müller Laboratory, Department of Organic Chemistry, University of Veszprém, Egyetem-u.6, H-8200 Veszprém, Hungary
d Department of Chemistry and Technology of Biologically Active Compounds, University "La Sapienza" Roma, P.zale Moro 5, I-00185 Roma, Italy

ABSTRACT
Prebiological or early biological enantioselection, leading to so-called biological homochirality is one of the most exciting challenges of molecular sciences [1]. The various theories about this problem are characterized by intellectual excellence [2], but the experimental verification is still in initial stage [3].
Our approach takes in consideration the recently recognized role of transition metal ions in the origins of life [4]. We report here on the development of chiral conformations by the long-range interaction of achiral ligands coordinated to cobalt (I) ions. Systematic structural changes and MO calculations identified concerted intramolecular movements, which lead to partial or even quantitative symmetry splitting in these complexes. This self-organization occurs both by ligand-ligand and ligand-metal-ligand interactions.

[1] Reviews: (a) Keszthelyi, L., Quart. Rev. Biophys., 1995, 28, 473-507. (b) Pályi, G., Zucchi, C., Caglioti, L. Advances in Biochirality (Pályi, G., Zucchi, C., Caglioti, L., Eds.), Elsevier, Amsterdam, 1999, pp. 3-12.
[2] Most recent results: Keszthelyi, L., Fundamentals of Life (Pályi, G., Zucchi, C., Caglioti, L., Eds.), Elsevier, Paris, 2002, pp. 99-103.
[3] E.g., (a) Szabó-Nagy, A., Keszthelyi, L., Proc. Natl. Acad. USA, 1999, 96, 4252-4255. (b) Singleton, D.A., Vo, K.L., J. Am. Chem. Soc., 2002, 124, 10010-10011.
[4] e.g., Huber, C., Wächtershäuser, G., Science, 1997, 276, 245-247; 1998, 281, 670-672.

MINIMAL UNIT OF TERRAFORMING
AN ALTERNATIVE FOR REMODELLING MARS

Héctor Omar Pensado Díaz
Instituto de Ciencias Avanzadas, A. C.
Xalapa, Ver.
México
e-mail: hpensado@secver.gob.mx

ABSTRACT
Several decades ago certain models for terraforming Mars for its optimal condition for life had been proposed. These stated models outline the alternative of raising the global temperature of the red planet by emiting green house type gases and cold weather adapted plants (Sagan1973; Averner and MacElroy 1976; McKay 1982) as well as super green house gases as a first stage on the terraforming process (Lovelock and Allaby 1984; Marinova 2000; Gestell 2001) and the usage of chemical factories and orbital mirrors (Zubrin and McKay 1997) with the same purpose. These approaches would densify the atmosphere by reactivating the hydrological cycle followed by the next stage on the terraforming process, the introduction of photosynthetic microorganisms.
The current tendency for Mars terraforming is the global warming of the planet. However, this document suggest a model for terraforming Mars in sections with a tool called the Minimal Unit of Terraforming (MUT) which comprises dome shaped structures built from translucid plastic trends stuck on the ground, so they could generate an inner greenhouse effect by raising the pressure. By this, it would have an inner environment which would interact with the surroundings helped by the gas exchange and biological ground prosecution. Then, the MUT collaborate as well on the ground gas reduction process creating a difference in the temperature and releasing the gases out of the atmosphere. Mars terraforming would begin with the processes listed above, considering that the MUT would serve Mars just as cells serve the photosynthetic organisms. And so, the atmosphere reconvertion and the ground microterraforming would start, but with consequences for the planet.
Gaia principles by J. Lovelock and L. Margulis had been considered for the establishment of an environment inside the MUT since life means plasticity and it can be adapted and adapt the surroundings by bringing climate and biological balance. This is important since life sown inside the MUT would not have an environment like that of the Earth and Mars, but a neutral environment which would be in thermodynamic lack of equilibrium with the Martian surface, just like a cell is protected by its membrane from the outside world. In that case, the membrane would be the dome shaped structure which would partially isolate the environment from the surroundings letting the gas exchange from the inside to the outside and vice versa by auto regulated valves, which would respond to the amount of millibars in the inside. Inner life would respond then to the dome weather conditions helped by life plasticity and would begin to adapt the inside according to its needs. Then, these structures would be all over the Martian surface and would begin the oxygenation, gas release and biological processes. Once in activity, they would be independent to the Martian atmosphere´s moisture for optimal water and electric power production via the source of solar energy. An acclimatization process of extreme weather condition and drought resistant organisms would have to be held before the installation of the MUT.
The MUT are factories that would create a thermodynamic lack of equilibrium in the surroundings by the generation of and energy wealthy environment in which life would be developed properly. And then, that new life would affect the Martian and its genotypes, creating a feedback system.
The MUT would be independent and could be installed all over Mars. They would take advantage of the natural resources in situ to use them in order to reactivate the different biochemical mechanisms for life. Moreover, the MUT would gradually terraform Mars by building an oasis and oasis areas apparently isolated, but in fact affecting the atmosphere and ground directly. They would transform the atmosphere and the surface. A species spread process affected by the Genotype + Environment interaction would transform the Martian environment, leading to the remodeling of the whole planet. Future crew expeditions could install the MUT with light weight materials from Earth. Then, the in situ natural resources would be taken for the MUT generation, then portable factories would use the silicon and iron form he surface sand to build the MUT in Mars.

ON THE APPARENTLY CONSISTENT L-BIASED ENANTIOMERIC EXCESSES IN METEORITIC EXTRACTS AS REPRESENTING A FORM OF ATTENUATED FORENSIC STEREOCHEMICAL EVIDENCE OF CHIRAL INFORMATION DERIVED FROM TERRESTRIAL CONTAMINATION.

Simon Nicholas PLATTS(1, 2)
(1.)Geophysical Laboratory (GL),
Carnegie Institution of Washington (CIW/NAI),
5251 Broad Branch Road, NW,
Washington DC 20015-1305 USA
(2.)Dept. of Chemistry,
Rensselaer Polytechnic Institute (RPI/NSCORT),
110 Eighth Street,
Troy NY 12180-3590 USA

ABSTRACT
We are investigating one possible and seemingly plausible chemical explanation for the significant and very curious L-enantiomeric excesses being reported (Pizzarello et al., ASU/NAI) for the amino acid complements extracted/derived from (especially) Murchison material. Given that reported analyses among the chiral small-molecule inventories of carbonaceous chondritic materials are necessarily limited by both sample size/availability and by these precious samples' curatorial/custodial histories, and given that terrestrially-derived contaminants (many of which in fact contain asymmetric centers) have recently been shown (Watson et al.) to have entered into the free/extractable organic component of Orgueil material, it would seem chemically reasonable now to suppose that imported terrestrial and chirally-biased molecular information will necessarily have 'impressed' itself during the effective 'titration' of available prochiral functionalities contained, perhaps, in native meteoritic macromolecular material; and that such a situation will obtain both during various wet extractive protocols in the lab, and over the longer-term (storage time) during in situ mineral-surface-mediated organic reactions (e.g. slow hydrolyses, ammonolyses, reductions, etc.). In our experimental attempt to at least qualitatively illustrate the essential feasibility of such an explanation in terms of known physical organic chemistry, stereochemistry, and the various methods of achieving variable degrees of stereo- and enantio-controls during organic syntheses, we are attempting to show that the 'titration' of prochiral functionalities (e.g. alkenyl & amidine-type functions) in a 13C-labelled 'HCN-polymer' material (prepared at PSU/NAI, and modeling here for general hydrolysable meteoritic macromolecular material, GHMMM) can be informationally/chirally-biased during typical chemical derivatisations (especially hydrolyses) made in the deliberate presence of an unreactive chiral auxiliary and solvating species, which is commercially-available in both (essentially pure) enantiomeric forms, and which stands as proxy for general terrestrial chiral contamination. While oligomeric HCN compounds, (HCN)x, are certainly too N-rich to stand as realistic model materials for GHMMM, this is actually of secondary concern in the present investigations, as is specific knowledge of the exact nature of the prochiral functions contained.

References
Pizzarello, S., Zolensky, M. and Turk, K.A. (2003) Nonracemic isovaline in the Murchison meteorite: Chiral distribution and mineral association. Geochimica et Cosmochimica Acta, 67, pp. 1589-1595.
Watson, J.S., Pearson, V.K., Gilmour, I. and Sephton, M.A. (2003) Contamination by sesquiterpenoid derivatives in the Orgueil carbonaceous chondrite. Organic Geochemistry, 34, pp. 37-47.

THERMOCHEMISTRY OF THE DARK AGE

Denis Puy
Observatory of Geneva
Chemin des Maillettes, 51
1290 Sauverny (Switzerland)

ABSTRACT
The dark age of the Universe is generally pointed out as the period between the hydrogen recombination epoch and the horizon of current astrophysical observations. The arrow of time in the cosmic history describes the progression from simplicity to complexity, because the present Universe is clumpy and complicated unlike the homogeneous early Universe. Thus it is crucial to know the nature of the constituents, in order to understand the conditions of the formation of the first bound objects. I will analyse the chemical history of this dark age through the creation of the primordial nuclei to the formation of the first atoms and molecules. Then I will describe the consequences of the molecular formation on the birth of the first stars. In this context I will show that contamination of heavier elements early appeared in the history of the Universe.

CHEMICAL CHARACTERIZATION OF AEROSOLS IN SIMULATED PLANETARY ATMOSPHERES. TITAN'S AEROSOL ANALOGUES

Sandra I. Ramírez 1, Rafael Navarro-González 2, Patrice Coll 3 and François Raulin 3
1Centro de Investigaciones Químicas, Universidad Autónoma del Estado de Morelos. MEXICO
2Laboratorio de Química de Plasmas y Estudios Planetarios, Instituto de Ciencias Nucleares, UNAM, MEXICO
3Laboratoire Interuniversitaire des Systèmes Atmosphériques, UMR 7583 Université Paris XII, FRANCE

ABSTRACT
Titan's surface is hidden , in visible light, by two aerosol layers. The composition of the haze has been studied through ground-based and spacecraft observations, by modeling, and by different experimental approaches.
Tentative analogues of Titan's aerosols have been synthesized in laboratory experiments in order to determine their physical and chemical properties. Photochemistry of atmospheric methane and its decomposition products (ethene and ethyne) is likely at the origin of the production of aerosols (Scattergood et al., 1992). However, a careful determination of the optical properties of the produced polymers in the laboratory shows that they do not match very well with the stratospheric Titan's aerosols. It was found that the solid product that reproduces the satellite's optical properties at best, specifically the geometric albedo, was produced by electrical discharges (Khare et al., 1984; McKay and Toon, 1992; Ramírez et al., 2002). Very little work has been published so far about the chemical properties of these apparently good analogues for the Titan's atmospheric aerosols. Hence there is a need for systematic studies of the solid products synthesized during electrical discharge simulation experiments in order to better understand the chemical properties of the aerosol constituents. This need is particularly important, in the perspective of the exploration of Titan by the Cassini-Huygens (NASA-ESA) mission, which is expected to provide a tremendous amount of new observational data of Titan's environments, starting in 2004. An efficient retrieving of these data requires the availability of many laboratory data, concerning specifically Titan's aerosol analogues.
The description of the initial steps of a systematic study focused in the characterization, by analytical techniques, of laboratory aerosol analogues synthesized from 1hour laser irradiation of a Titan's canonical atmosphere will be presented. How close the solids obtained experimentally represent Titan's aerosols (tholins) is still in debate, but understanding the chemical process which makes tholins and approaching to their chemical constitution can certainly help to easily interpret their role in Titan's atmosphere.

REFERENCES
Coll P., Coscia D., Smith N., Gazeau M.-C., Ramírez S. I., Cernogora G., Israël G. and Raulin F. (1999) Experimental laboratory simulation of Titan's atmosphere (aerosols and gas phase). Planet. Space Sci. 47(10-11), 1331-1340.
Khare B. N., Sagan C., Thompson W. R., Arakawa E. T., Suits F., Callcott T. A., Williams M. W., Shrader S., Ogino H., Willingham T. O. and Nagy B. (1984) The Organic Aerosols of Titan. Adv. Space Res. 4(12), 59-68.
McKay C. P. and Toon O. B. (1992) Titan's organic haze. In Proceedings, Symposium on Titan, pp. 185-190. ESA SP-338.
Ramírez S. I., Coll P., Da Silva A., Navarro-González R., Lafait J. and Raulin F. (2001a) Complex refractive index of Titan's aerosols analogues in the 200-900 nm domain. Icarus 156, 515-529.
Raulin F., Coscia D., Ramírez-Jiménez S., Navarro-González R. and Coll P. (1999) Exobiological Importance of Tholins. In The dark matter in the Solar System, Meudon, France.
Scattergood, T.W., Lau E. Y. and Stone B. M. (1992) Titan's aerosols I. Laboratory investigations of shapes, size distributions, and aggregation of particles produced by UV photolysis of model Titan atmospheres. Icarus 99, 98-112.

KINETIC MODELING OF THE SOAI-TYPE ALKYLZINC ADDITION AS A MODEL SYSTEM FOR EFFICIENT CHIRAL AUTOAMPLIFICATION

Jesús Rivera Islas a, Jean-Claude Micheau b and Thomas Buhse a

a Centro de Investigaciones Químicas, Universidad Autónoma del Estado de Morelos,
Av. Universidad Nº 1001, Col. Chamilpa, 62210 Cuernavaca, Morelos, México. b Laboratoire des IMRCP, UMR au CNRS Nº 5623, Université Paul Sabatier, 118, route de Narbonne, F-31062 Toulouse Cedex, France

ABSTRACT
Experimentally observed chiral autoamplification in specific chemical systems has attracted close scientific interest as a possible explanation for the origin of biomolecular homochirality [1]. Among these few systems, the addition of di-iso-propylzinc (Zn) to a pyrimidine carbaldehyde (CHO) yielding a chiral pyrimidyl alkoxide (COZn) is one of the most prominent examples for autocatalytically driven enantioselective amplification that involves the formation of a chiral carbon [2]. The reaction can be regarded as a prototype system for the dynamics of chiral amplification that is believed to have played a key role in the prebiotic evolutionary pathway from very small enantiomeric imbalances to the virtually homochiral state of the biomolecules. Based on a simplified kinetic model [3] (Fig. 1), the dynamics of this system have been analyzed and the possible mechanism of chiral autoamplification is discussed. The kinetic model outlines the dynamics of the reaction system similar to a recently analyzed template-directed self-replicating system [4]. In the present case, a 'selfish' autocatalyst, (COZn)2, is embedded in a monomer-dimer equilibrium, 2 COZn ´ (COZn)2 that globally leads to a strong cubic autocatalytic effect resulting in highly nonlinear chiral amplification while the template effect ensures a sufficiently high degree of stereoselectivity. Experimentally observed chiral amplification can be reproduced by the model and further predictions of chiral implications in an open flow system are evaluated. Under these conditions, it is predicted that the system passes through a bifurcation scenario in which the racemic state becomes unstable and the emerging optically active state may show kinetic bistability.

References
[1] Buhse, T.; Lavabre, D.; Micheau, J. C.; Thiemann, W. Chirality 1993, 5, 341-345; Keszthely, L. Quart. Rev. Biophys. 1995, 28, 473-507; Avalos, M.; Babiano, R.; Cintas, P.; Jiménez, J. L.; Palacios, J. C. Tetrahedron: Asymmetry 2000, 11, 2845-2874; Kondepudi, D. K.; Asakura, K. Acc. Chem. Res. 2001, 34, 946-954.
[2] Soai, K.; Shibata, T.; Morioka, H.; Choji, K. Nature 1995, 378, 767-768; Soai, K.; Shibata T.; Sato, I. Acc. Chem. Res. 2000, 33, 382-390; Blackmond, D. G.; McMillan, C. R.; Ramdeehul, S.; Schorm, A.; Brown, J. M. J. Am. Chem. Soc. 2001, 123, 10103-10104; Sato, I.; Omiya, D.; Tsukiyama, K.; Ogi, Y.; Soai, K. Tetrahedron: Asymmetry 2001, 12, 1965-1969.
[3] Buhse, T. Tetrahedron: Asymmetry 2003, 14, 1055-1061.
[4] Rivera Islas, J; Pimienta, V.; Micheau, J. C.; Buhse, T. Biophys. Chem. 2003, 103, 191-200; Rivera Islas, J; Pimienta, V.; Micheau, J. C.; Buhse, T. Biophys. Chem. 2003, 103, 201-211; Rivera Islas, J; Micheau, J. C.; Buhse, T. Origins Life Evol. Biosphere, to be published.

WHEN DID INFORMATION FIRST APPEAR IN THE UNIVERSE?

Juan G. Roederer
Geophysical Institute,
University of Alaska-Fairbanks
Fairbanks AK 99775,
e-mail: jgr@gi.alaska.edu
and
The Abdus Salam
International Centre for Theoretical Physics

ABSTRACT
To answer this question it is necessary to define the concept of information in a strictly objective and general way, detached from human artifacts and related algorithms and semantics, and not based on any mathematical formula. To accomplish this we turn to the concept of interaction as the primary concept. We identify two fundamentally different classes, with information and information-processing appearing as the key discriminator: force-field driven interactions between elementary particles and ensembles of particles in the macroscopic physical domain, and information-based interactions between certain kinds of complex systems that form the biological domain. We shall argue that in an abiotic world, information plays no role; physical interactions just 'happen', they are driven by energy exchange between the interacting parts and do not require any operations of information processing. Information only enters the non-living physical world when a living thing, or an artifact constructed by an intelligent being interact with it. In information-based interactions, a form or pattern, not energy or force, is the controlling factor. They comprise biomolecular information processes controlling the metabolism, growth, multiplication and differentiation of cells, and neural information processes controlling animal behavior and intelligence. The only way new information can appear is through the process of biological evolution and, in the short term, through sensory acquisition and the manipulation of images in the central nervous system.
Clearly, only physical systems, albeit complex ones, are involved in information-driven interactions; what appears to be irreducible to presently known physical laws, though, is the way the mechanisms responsible for information-driven interactions actually arise in the natural world. The ultimate question of the origin of biological information is how under prebiotic conditions the nucleotide sequence of the protogene was selected out of innumerable, energetically equivalent, alternatives. In summary, to answer the question in the title: during the evolution of the Universe information begins when and where life begins.

DIVERSITY OF MICROBIAL LIFE ON EARTH AND BEYOND

Joseph Seckbach,
P.O.Box 1132, Efrat 90435, Israel.
e-mail: seckbach@huji.ac.il

ABSTRACT
Microbial Life occurs in all environmental conditions on Earth. Microorganisms are abundant not only in "normal" environments but also thrive under very harsh habitats. These organisms that are found at the edge of the living limits have been designated as extremophiles. Such microbes have been observed in various severe conditions (from the anthropocentric point of view) far from the typical, "regular" known conditions of Life.
Those extremophiles that grow in more than one rigorous factor are termed Polyextremophiles (such as Prokaryotes under high pressure and low temperature, or those Bacteria, Archaea and certain algae under high temperature and low pH ranges). Barophilic thermophiles exist in deep-sea hot vents; other organisms live in soda lakes, which may be saturated with salt while reaching pH values as high as 11-12. Archaea and Bacteria are able to survive and grow in various temperature ranges (from ­20 °C [the psychrophiles] to 113°C [the hyperthermophiles]). Some unicellular thermophiles thrive in very acidic (at pH 0-2) solution and other in alkaline media (pH ~ 10 and higher). Some bacteria are resistant to high doses of harmful radiation of UV.
Bacteria occur at the subsurface depths where the temperature and the pressure are very high. In the depths of the ocean are the piezophiles (or barophiles) that grow a few kilometers under the surface. Such weight-bearing microbes have to resist not only high pressures (of several hundreds atmospheres) but also low temperatures (1- 3°C ). It has been reported elsewhere that some algae are able to grow under an atmosphere of pure CO2, while bacteria have been kept alive in ammonia and are well known to thrive in anaerobic conditions.
Life has existed on Earth at least for 3.8 billion years. Assumedly, the atmospheric conditions during the early period on Earth were different from those of today. The Origin of Life may have taken place in the hot sub-surfaces of Earth and under oceanic hydrothermal vents. Under such conditions, the first pioneers of Life would have been protected from the harmful UV irradiation and shielded from the inter-celestial rocks and meteorites bombarding young Earth.
Thus, the extremophiles could represent the first microorganisms on Earth with their severe and ancient environments. Furthermore, they could perhaps also serve as models for living microbes under the harsh conditions that exist on extraterrestrial bodies, such as on our neighboring planet Mars, or on the Jovian satellite Europa or even on Titan, the moon of Saturn.

References
Oren, A. and Seckbach, J. 2001. Oxygenic photosynthetic microorganisms in extreme environments. In: J. Elster, J. Seckbach, W. Vincent, and O. Lhotsky (eds.). Algae and Extreme Environments-Ecology and Physiology. Nova Hedwigia Beiheft 123: 13-31.

Seckbach, J. (ed.) 1999. Enigmatic Microorganisms and Life in Extreme Environments. Kluwer Academic Publishers, Dordrecht, The Netherlands.

Seckbach, J. (ed.) 2000. Journey to Diverse Microbial Worlds, Kluwer Academic Publishers, Dordrecht, The Netherlands.

Seckbach, J and Oren, A. 2003/4. Introduction to the extremophiles, In: J. Seckbach (ed) Origins, Kluwer Academic Publishers, Dordrecht, The Netherlands (in press).

EXOBIOLOGY OF TITAN

Michael B Simakov
Group of Exobiology, Institute of Cytology RAS, Russia

ABSTRACT
Titan, the largest satellite of Saturn has a dense nitrogen atmosphere and a large quantity of liquid water under ice cover and so has a great exobiological significance. The putative internal ocean along with complex atmospheric photochemistry provide some new exobiological niches on this body: (1) an upper layer of the internal water ocean; (2) pores, channels and pockets filled with brines inside of the lowest part of the icy layer; (3) the places of cryogenic volcanism; (4) set of caves in icy layer; (5) the brine-filled cracks in icy crust caused by tidal forces; (6) liquid water pools on the surface originated from meteoritic strikes; (7) the sites of hydrothermal activity on the bottom of ocean. All conditions needed for exobiology - liquid water, complex organic chemistry and energy sources for support of biological processes - are on the Saturnian moon. All these environments will be considered along with properties of many kinds of Earth extremophiles which could survive in such environments. Possible metabolic processes, such as nitrate/nitrite reduction, sulfate reduction and methanogenesis could be suggested for Titan. Excreted products of the primary chemoautotrophic organisms could serve as a source of the nutrients for other types of microorganisms (heterotrophes).

EXTRATERRESTRIAL IMPACTS ON EARTH AND EXTINCTION OF LIFE
IN THE HIMALAYA

Vinod Chandra Tewari
Wadia Institute of Himalayan Geology, India and
The Abdus Salam ICTP, Italy

ABSTRACT
The comets, meteorites and asteroids have collided with the Earth throughout geological history. The mass extinction at Permian ­ Triassic boundary and Cretaceous ­ Tertiary boundary is strongly supported by the extraterrestrial asteroidal impact theory in the Indian Himalayan sequences well exposed at Spiti in Western Himalaya and Um Sohryngkew section in Meghalaya, northeastern Himalaya. The Carbon isotopic and palaeobiological events suggest extraterrestrial impacts at P/T and K/T boundaries all over the world. The early evolution of life, its diversification, carbon isotope chemostratigraphy, amino stratigraphy and extinction events have been discussed from the Indian Himalaya.

THE HABITABILITY OF THE NEAREST STARS TO COMPLEX LIFEFORMS

Margaret C. Turnbull
University of Arizona, Steward Observatory, 933 N. Cherry Ave, Tucson, AZ, 85721, USA
and
Jill C. Tarter
SETI Institute, Mountain View, CA, USA

ABSTRACT
In this presentation we will take a look at the Solar Neighborhood from the perspective of biology, in order to decide which systems are more likely to be habitable to complex lifeforms. We define a "habstar" as a star whose physical properties make it a good host for planets bearing life like that found on Earth. For a star to be granted "habstar" status, it must satisfy an extensive list of criteria which we have formulated based on our knowledge of life on Earth and the characteristics of the Earth-Sun system. These criteria can be translated into observable stellar characteristics which include stellar age, spectral type, variability, metallicity, stellar kinematics, multiplicity and the presence of known giant planets. Here we describe each of these characteristics and discuss its relevance to life, and we will show how we created criteria for selection of "habstars" to assemble target lists for the Terrestrial Planet Finder and for the Search for Extraterrestrial Intelligence.

In order to carry out this analysis, a vast amount of astronomical data was required. We began this project with the Hipparcos Catalogue, a database of about 120,000 stars whose distances have been accurately determined via parallax measurements. We then supplement this database with data from many other catalogs, each of which provides some information about the stellar characteristics listed above. While it is not possible to know for sure whether any given star has all the requirements for a habitable environment (including terrestrial planets in the habitable zone), we can use these data to eliminate stars that have one or more undesirable characteristics. After doing so, we find that, to the best of our current knowledge, there are at least 17,000 stars within about 1,000 light years that could host complex life. This list comprises the new target list for use with SETI's Allen Telescope Array.

This type of work is unusual in that it inspires discussion of an extremely wide array of astronomical, planetary, and biological topics (e.g., extrasolar planets, galactic structure, supernovae, the Solar Cycle, climate change, plate tectonics, the origin of life, evolution of complex life, etc), and it engages a broad cross-section of the scientific community. From the student's perspective, this exploration requires a combination of imaginative thinking with critical analysis. In the process of carrying out this work, it has become clear that we have very much to learn about even the nearest stars, about the history of life on Earth, and about how our own technological civilization came to be.

SULPHATE VOLUMES AND THE FITNESS OF SUPCRT92 FOR CALCULATING DEEP OCEAN CHEMISTRY

Steven Vance1, Everett Shock2, Tilman Spohn3
1 University of Washington, Seattle, Washington, USA. svance@ess.washington.edu
2 Arizona State University, Tempe, Arizona, USA.
3 Westfälische Wilhelms Universität, Münster, DE.

ABSTRACT
Comparing experimentally obtained volumes for dilute solutions of sodium sulphate obtained at high pressure and temperature, we show that the supcrt92 program for modeling aqueous chemistry accurately predicts solution properties for all measured temperatures, but fails in the pressure range above 2000 bar. A fix to the governing equations is not readily apparent. However, accuracy to 2000 bar is sufficient for simulating the formation and stable composition of Europa's ocean, if not for the deeper oceans in Ganymede or Callisto. In this way having validated supcrt92 as a tool for explorating Europa's ocean in both the regimes of pressure and temperature, we discuss a calculation of temperature and composition in the ocean. The new calculation is based on pressure distribution dictated by the assumption of hydrostatic equilibrium. Temperature and composition are based on tidal dissipation in Europa's mantle and ocean by Hussman (2003), differentiation as estimated by Sohl et al (2002). We then look at the implications for ecosystems at the ocean's ceiling and floor.

References
HUSSMAN, H., 2003. Europa's Ocean and the Orbital Evolution of the Galilean Satellites. Dissertation Thesis, Institut für Planetologie, University of Münster.

SOHL, F., T. SPOHN, D. BREUER, and K. NAGEL 2002. Implications from Galileo observations on the interior structure and chemistry of the Galilean satellites. Icarus, 157, 104-119.

CHANCE OR DESIGN IN THE ORIGIN OF LIVING BEINGS
AN EPISTEMOLOGICAL POINT OF VIEW

Rafael Vicuña 1 and Alejandro Serani-Merlo 2,

1. Pontificia Universidad Catolica de Chile
and Millenium Institute for Fundamental and Applied Biology, Chile,

2. Facultad de Medicina,
Universidad de los Andes, Santiago, Chile.

ABSTRACT
The fact that the natural world is primarily composed by living and non-living entities constitutes one of the humankind commonsense most ancient spontaneous intuitions. The adequate intellectual understanding and the formal conceptual expression of the uniqueness of living beings, has intrigued biologists and natural philosophers at least since the time of the first Greek naturalists.

The question about the origin of living beings was always viewed then -as it is also nowadays-, as tightly linked to the question about the definition and explanation of the uniqueness of life. If living beings are no more than complex material devices, organized fortuitously by the free interaction of blind mechanical forces, and whose survival was submitted to natural selection, as Empedocles first sustained, then the complete understanding of the origin of life must lie on strictly mechanical explanations. If, on the other side, living beings are unique natural entities, formally different from non-living beings, even if materially composed by them, as philosophers like Plato and Aristotle sustained, then the explanation of their origins must revert to supra-mechanical causes in addition to mechanical ones. These supramechanical causes not being conceived as supramechanical forces as in later vitalism but as real formal aspects, as opposed to material aspects, of physical realities.

In the Greek non-creationist cosmological context, the particular origin of life reverted to chance -in the materialistic view-, and to some kind of intentional non-mechanical formal causality -in the non-materialistic view-. Underlying the many nuances that the huge development of modern biology has introduced through the centuries, to the statement of the problem, the opposing philosophical views seem to remain virtually untouched. Some authors, in the line of Oparin and others, adhering explicitly to philosophically materialistic views, have tried to find in the experimental evidences that modern science provides the grounding for their theoretical speculations on a purely mechanistic explanation for the origin of life. On the other hand, and also intending to ground their speculations in data provided by contemporary biological knowledge, an increasing number of authors try to substantiate the thesis that the origin and diversification of living beings on earth would have been impossible without the recourse to other kind of causes (non-reductionism) or the intervention of an intentional intelligent cause (creationism).

In this study we don't intend to arbitrate the ontological dispute between materialistic and non-materialistic positions; we only intend an epistemological clarification that could open the way to conciliate in some way both views, recognizing the part of truth that both positions seem to contain.

We propose to distinguish in actual discussions on the origin of life on earth at least four different epistemological categories of statements: a) direct experimental evidence; b) interpretation of primary experimental data through theoretical modelling; c) interpretation of primary evidence through ontological or philosophical speculation; d) paleontological theoretical speculation based on the three previous kind of statements.

Considering that the rise of living beings from material components is not a directly verifiable event, we must accept that the origin of life is at present out of the reach of experimental evidence. Actual experimental data then provides nowadays only indirect evidence for theoretical reasoning on levels b), c) and d) previously described.

We sustain in this proposal that paleontological speculations, based on actual experimental data are not necessarily contradictory with philosophical reasoning also based in primary experimental evidence. What seems to be indeed contradictory are mechanistic versus non mechanistic philosophical statements. If what we affirm is correct, that means that it could be accepted as legitimate for a biologist, -while thinking 'paleontologically'-, to reason purely or mainly on strictly empirical basis, while on the other hand, the same person thinking as a philosopher, could perfectly reason on non-mechanistic or intentional design grounds. Only if a biologist affirm as a philosopher the truth of an empirical view, an intelligent design position can be regarded as contradictory to his statements.

In summary, we affirm that it is in principle non-contradictory for a biologist to reason as a paleontologist on strictly empirical terms, while thinking as a philosopher on intentional design grounds. If intentional design thinking is really true or not, that must be decided on strict philosophical terms, not on scientific ones.

ADSORPTION AND CATALYSIS OF NUCLEOTIDE HYDROLYSIS BY PYRITE IN MEDIA SIMULATING PRIMEVAL AQUEOUS ENVIRONMENTS

Adalberto Vieyra1,#, Ana C. Tessis1, Mila Pontes Buarque1, José A. Bonapace2, Marisa B. M. Monte3, Hélio Salim de Amorim4 and Fernando de Souza Barros4

1Instituto de Biofísica Carlos Chagas Filho, 2Instituto de Química and 4Instituto de Física, Universidade Federal do Rio de Janeiro; 3Centro de Tecnologia Mineral, Ministério da Ciência e Tecnologia, Rio de Janeiro, Brazil.

ABSTRACT
Minerals of Fe/S have been implicated in different catalytic processes during chemical evolution. In this communication we report work regarding Fe/S-nucleotides interaction. We investigated whether pyrite (FeS2) can adsorb nucleotides and oxo acids in the potentially mild prebiotic conditions that could have existed in the neighborhood of hydrothermal vents. It is shown that pyrite strongly adsorbs adenosine 5'-monophosphate (5'-AMP) and adenosine 5'-triphosphate (ATP) in an artificial medium that simulates that environment. Adsorption of nucleotides is modulated by divalent cations, pH, molecules of high dipolar moment (such as cyano compounds), and by acetate ­ an organic precursor of complex metabolic pathways. The adsorption of nucleotides also depends on the net surface charge of the mineral modulated by the pyrite-aqueous solution interface. Upon adsorption, FeS2 catalyzes the sequential hydrolysis of the g and b phosphoanhydride bonds of ATP, with a kinetics and metal-dependence that could have pre-empted by more evolved energy-transducing systems. These results show that complex and flexible iron-sulfide/biomonomers interactions - in one of the proposed primordial environments - could have played a significant role during chemical evolution.

# Author for correspondence, e-mail: avieyra@biof.ufrj.br; FAX: +55-21-22808193

Financial support: CNPq, FUJB-UFRJ, Finep (Brazil)

QUASAR ABSORPTION LINE SYSTEMS AND ASTROBIOLOGY

Giovanni Vladilo
Osservatorio Astronomico di Trieste
Istituto Nazionale di Astrofisica

ABSTRACT
Quasar absorption line systems probe the diffuse gas in the universe and are observed over a large interval of cosmic time, up to ~12 Gyr before the present. Most absorptions arise in the intergalactic medium where the physical conditions are too harsh to host life. However, the absorptions with the highest column density of neutral gas, called Damped Lyman alpha systems (DLAs), arise inside galaxies observed at the early stages of their evolution and offer new perspectives in studies of astrobiology. In fact, as I show in this contribution, observations of DLAs provide unique data on the build-up of biogenic elements, molecules and dust in galaxies, as well as on the effects of ionizing radiation fields. The analysis of these data as a function of cosmic time can provide fresh clues in the search for continuously habitable zones.