OVERVIEW OF COSMIC EVOLUTION
George V. Coyne, S.J.
Specola Vaticana,
Citta' del Vaticano
00120 Roma, Italy.
FAX: (06) 6988 4671
email : gcoyne@specola.va
ABSTRACT
The most significant fields
in the study of cosmic evolution extend over a wide range of topics
including the physics of the early universe to the search for
extra-solar planetary systems. In this overview I wish to emphasize
two general conclusions which can be drawn from the most recent
research: (1) public opinion to the contrary, our scientific knowledge
of the universe is very limited; (2) there is increasing evidence
that we may not be alone in the universe.
(1) By combining elementary particle physics with quantum cosmological models we have a solid understanding of the very early universe. Less well known are the epochs of the formation of structure in the universe: galaxies and clusters of galaxies. The deep field observations with the Hubble Space Telescope challenge all theories accepted to date for the development of structure. A principal difficulty is that the observations indicate that structure developed much earlier than can be accounted for in any of the expanding universe cosmologies. The detection of non-homogeneity challenges inflationary models. Despite intense efforts to determine the ultimate fate of the universe, we are more confused than ever by the discovering that the universe at large distances is accelerating. More than a decade of attempts to identify the dark matter in the universe have left us still in doubt, although the observational evidence for its existence is overwhelming.
(2) We must be very careful in our formulation of the extra-terrestrial life debate. The question to be addressed is not whether there is extraterrestrial intelligence, since there is no scientific data whereby to even approach an answer. The question is rather: Are there the physical conditions for Earthlike life elsewhere in the universe? In other words, is there any evidence that there are planets like the Earth about stars like the Sun with the macrophysical conditions for life? Research over about the past decade has led to the discovery of more than one hundred planets about other stars. These planets have been discovered by analyzing the systematic oscillations in the motion of the parent star. Only massive planets near to their parent star can be discovered in this way. Other techniques, such as high-resolution imaging in space and from the Earth, spectroscopic detection of extra-solar planetary atmospheres. etc, are being developed. Much progress is being made in the search by spectroscopy for biotic or pre-biotic conditions in extra-solar planets. Within the next decade we will undoubtedly discover hundreds more extra-solar planets. It appears, therefore, from an observational point of view, that the existence of planetary systems is a not uncommon phenomena. Do any of them nurture the physical conditions for life?
EUROPA: OVERVIEW OF FUTURE MISSIONS
Torrence JOHNSON
Jet Propulsion Laboratory, 4800 Oak Grove Dr., Pasadena CA 91109, USA
ABSTRACT
There is significant evidence
from the Galileo exploration of the Jupiter system, and other
planetary studies, that the icy moons of Jupiter, Europa, Ganymede,
and Callisto, have global, liquid water oceans beneath their icy
crusts. These environments are critical targets for exploration
related to the origin and evolution of life outside the Earth.
The key ingredients for support and possibly for the origin of
life as we know it liquid water, organic molecules, and
energy are probably available in varying degrees on each
of these bodies. Europa is particularly interesting since on this
moon a global water ocean about 100 km deep may overlie a rocky,
silicate mantle heated by both radioactive decay and tidal energy,
raising the possibility of environments similar in many ways to
terrestrial seafloor hydrothermal systems.
The US National Academy of Sciences' National Research Council has recently completed a survey of solar system exploration in the coming decade. Their recommendations include a very high priority for future exploration of Europa with a 'flagship' class Geophysical Explorer mission as well as increased emphasis on the other icy moons that may harbor sub-surface oceans. NASA has responded with a proposal for a Jupiter Icy Moon Orbiter mission that would send a spacecraft with a sophisticated payload to the Jupiter system, capable of going into orbit around each of the icy moons and conducting detailed scientific investigations. The mission concept involves use of electric powered ion-drive (pioneered for deep space use by NASA's Deep Space 1 mission) propulsion system powered by a small, highly efficient nuclear reactor. Launched with a conventional heavy-lift rocket, the spacecraft's power system would not be activated until after orbit has been achieved.
Studies of the JIMO mission are
now underway, including detailed definition of the science objectives
by a Science Definition Team. Based on a competitive selection
within the next two years, the science investigations are expected
to include geodetic and geophysical studies of the tides raised
by Jupiter, induced and intrinsic magnetic fields, detailed geologic
and geochemical mapping of the surfaces at high spatial resolution,
studies of the interactions of the satellites with the Jupiter
magnetosphere as well as studies of the Jupiter system as whole.
THE NEW UNIVERSE, DESTINY OF LIFE AND CULTURAL IMPLICATIONS
Steven J. Dick,
US Naval Observatory,
3450 Massachussetts Av.
NW, Washington, DC 20392-5420
United States of America
ABSTRACT
I intend to have a double
thrust, both in the context of cosmic evolution:
1) that if cosmic evolution commonly ends in life and intelligence,
this "biological universe" has many implications for
our terrestrial culture(s), which I will address, and 2) that
we need to take more seriously the cultural evolution component
of cosmic evolution. On Earth cultural evolution totally dominates
biological evolution, and in a universe where civilizations may
be billions of years old, cultural evolution may have led to a
"postbiological universe", dominated by artificial intelligence,
with great implications for SETI. I will argue that we need to
take a long-term "Stapledonian" view of cultural evolution
in the universe.
ORIGIN AND EVOLUTION OF VERY EARLY SEQUENCE MOTIFS IN ENZYMES
HERRICK BALTSCHEFFSKY, BENGT PERSSON#, ANDERS SCHULTZ, JOSÉ R. PÉREZ-CASTIÑEIRA* and MARGARETA BALTSCHEFFSKY
Department of Biochemistry and Biophysics, Arrhenius Laboratories, Stockholm University, S-106 91 Stockholm, Sweden, # IFM Bioinformatics, Linköping University, S-581 83 Linköping and Centre for Genomics and Bioinformatics, Karolinska Institutet, S-171 77 Stockholm, Sweden, *Instituto de Bioquímica Vegetal y Fotosíntesis, CSIC-Universidad de Sevilla, Sevilla, Spain
e-mail: herrick@dbb.su.se
ABSTRACT
Conserved amino acid sequence
motifs in enzymes often indicate involvement in the binding of
metal ion(s) and/or in the binding and/or reactions of substrate(s).
The four very early proteinaceous amino acids are glycine (G),
alanine (A), aspartic acid (D) and valine (V) (Eigen and Schuster,
1979, The Hypercycle, Springer, Berlin). Aspartic acid stands
out as the unique very early amino acid containing an additional,
highly reactive free charge, suitable i. a. for cation
binding. Active site motifs, that are rich in any or all of these
four amino acids, may well be of early evolutionary significance.
Some "early" proteins appear to harbour or reflect very early sequence motifs. For example, certain enzymes involved in PPi metabolism, as well as in that of ATP, seem to be of great significance in this connection. Special attention has recently been given to the integrally membrane-bound, proton-pumping PPi synthase, which in bacterial photophosphorylation is the first and still only known alternative to the ubiquitous ATP synthase in biological electron transport coupled phosphorylation (Baltscheffsky et al. (1998) FEBS Lett. 457, 527-533). The putative active site of the PPi synthase has two nonapeptidyl sequences (DVGADLVGK and DNVGDNVGD), which are strongly conserved in the homologous enzyme family, which furthermore contain unusually many very early amino acids and which importantly have charged amino acids regularly arranged in positions 1, 5 and 9, five of these six being aspartic acid. Similar very early motifs are found in some other PPi metabolizing enzymes, and also, more or less similar, in some ATP metabolizing enzymes.
Based on plausible early motif evolution and also on results from both biochemical and geological investigations, emphasizing the emergence of selected homopolymers as probably being significant intermediate stages between monomers and heteropolymers in connection with the origin of life, a tentative, detailed outline of a stepwise molecular origin and evolution of biological energy conversion, with particular emphasis on its early phosphate metabolism, will be presented.
EANA, THE EUROPEAN EXO/ASTROBIOLOGYNETWORK ASSOCIATION
André Brack, President
Centre de biophysique moléculaire, CNRS, brack@cnrs-orleans.fr
ABSTRACT
The European Exo/Astrobiology
Network Association, EANA, was created to co-ordinate the different
European centres of excellence in exo/astrobiology or related
fields already organised in national networks. The specific objectives
of EANA are :
- to bring together European researchers interested in exo/astrobiology
programmes and to foster their cooperation
- to attract young scientists to this quickly evolving, interdisciplinary
field of research
- to create a website establishing a database of expertise in
different aspects of exo/astrobiology
- to interface the Network with European bodies such as ESA, ESF,
the European Commission and with non European institutions active
in the field
- to popularise exo/astrobiology to the public and to students.
EANA is run by an Executive Council
consisting of national members presently representing 12 European
nations active in the field (Austria, Belgium, Denmark, France,
Germany, Italy, Portugal, Spain, Sweden, Switzerland, The Netherlands,
United Kingdom) on the basis of one representative per nation,
and elected members in a number equal to the number of active
nations.
EANA is affiliated to the NASA Astrobiology Institute. The formal
affiliation was signed in 2002 at the Graz Workshop by Rosalind
Grymes, Deputy Director of NAI, during a reception hosted by the
Governor of Styria in the historical Eggenberg Castle.
EANA is member of the International Astrobiology Circle, IAC,
including the Australian Centre for Astrobiology (ACA), the Spanish
Centro de Astrobiologia (CAB), the French Groupement de Recherche
en Exobiologie (GDR Exobio), the American NASA Astrobiology Institute
(NAI), and the United Kingdom Astrobiology Forum (UKAF). The IAC
has been implemented to facilitate international exchange between
established bodies dedicated to astrobiology and to harmonise
the planning of joint astrobiology meetings.
Collaborative researches are developed
in the different fields covered by exo/astrobiology:
- Terrestrial life as a reference (Origins of life, environmental
context, ingredients for primitive life, life in a test tube,
diversity of bacterial life, life in the extremes, panspermia)
- Exploring the Solar System (Mars, Europa, Titan, Comets)
- Search for life beyond the Solar System (exoplanets, Corot and
Darwin missions)
The First European Exo/Astrobiology
Workshop held in Frascati, 21-23 May 2001, was attended by 200
scientists. The national and international activities in Exo/Astrobiology
were presented, as well as the European achievements in the different
fields covered by Exo/Astrobiology. Plenary, splinter and poster
sessions cemented the European community.
The Second European Workshop on Exo/Astrobiology was organised
in Graz, Austria, September 16-19, 2002. The workshop, attended
by 320 participants, was oriented particularly to the planetology
aspects of exo/astrobiology, in acknowledgement of the expertise
of the local organisers.
Third European Exo/Astrobiology Workshop (in preparation), will
be hosted by the Centro de Astrobiologia in Madrid, November 18-20,
2003.
The EANA Web Page is under construction. It will be hosted as
part of the ESA pilot Virtual Institute at ESA/ESTEC in Noordwijk,
The Netherlands.
SEARCH FOR LIFE ON MARS:
THE BEAGLE 2 LANDER AND THE STONE EXPERIMENT
André Brack
Centre de biophysique moléculaire, CNRS, brack@cnrs-orleans.fr
ABSTRACT
The search for traces
of life on Mars encompasses a large number of disciplines (Brack
et al., 1999; Westall et al., 2000). Beagle-2, the exobiology
lander of ESA 2003 Mars Express mission, comprises an integrated
suite of instruments to optimize the search for evidence of life
on Mars in subsurface and rock interior samples. The package includes
instruments to study sample mineralogy (composition, macroscopic
and microscopic structural and textural features), organics (elemental,
molecular), oxidation state and petrology (major and minor element
composition). Environmental characteristics will also be measured
(atmosphere, radiation budget, temperature, pressure, wind speed
and direction, humidity, dust activity). The material will be
sampled from protected sites (subsurface and rock interiors) with
a mole and a small surface rock grinder and corer mounted on a
robotic arm (Sims et al., 1999). The solid sample (soil or rock)
will be heated in steps of increasing temperature, each increment
being supplied with freshly generated oxygen. Any carbon compound
present will burn to give carbon dioxide. The gas generated at
each temperature will be analysed by the mass spectrometer. The
instrument can distinguish between the two stable isotopes of
the carbon and quantify the ratio. Other gases can be analysed
by the same instrument including methane.
The 'STONE' experiment, flown by ESA, was designed to test whether
Martian sedimentary material could survive terrestrial atmospheric
entry. A basalt (inflight control), a dolomite (sedimentary rock)
and artificial Martian regolith were embedded into the ablative
heat shield of Foton 12, which was launched on September 1999.
The collected entry samples have been analysed for their chemistry,
mineralogy and isotopic compositions by a European consortium.
Modifications due to atmospheric infall were tested by reference
to the untreated samples. The dolomite sample was retrieved intact,
although reduced to a depth of about 30% of its original thickness,
suggesting that some Martian sediments could, in part, survive
terrestrial atmospheric entry from space. Some kinetic isotopic
fractionation accompanied the thermal degradation of the dolomite
during re-entry, as evidenced by bulk isotopic measurements on
different zones of the residual carbonate. The silica 'fusion
crust' from the associated sample holder exhibited a significant
degree of isotopic exchange with atmospheric oxygen during re-entry
(Brack et al., 2002).
References
Brack, A., Fitton, B., Raulin,
F. (1999). Exobiology in the Solar System and the search for life
on Mars, ESA Special Publication SP 1231.
Brack, A., Baglioni, P., Borruat, G., Brandstätter, F., Demets,
R., Edwards, H.G.M., Genge, M., Kurat, G., Miller, M.F., Newton,
E.M., Pillinger, C.T., Roten, C.-A. and Wäsch, E. (2002).
Do meteoroids of sedimentary origin survive terrestrial atmospheric
entry? The ESA artificial meteorite experiment STONE, Planet.
Space Science, in press.
Sims, M.R., Pillinger, C.T., Brack, A. and 26 co-auteurs (1999).
Beagle 2 : a proposed exobiology lander for ESA'S 2003 Mars Express
Mission, Adv. Space Res. 23, No. 11, 1925-1928.
Westall, F., Brack, A., Hofmann, B., Horneck, G., Kurat, G., Maxwell,
J., Ori, G.G., Pillinger, C., Raulin, F., Thomas, N., Fitton,
F., Clancy, P., Prieur, D., Vassaux, D. (2000). An ESA study for
the search for life on Mars Planet. Space Sci. 48, 181-202.
EVOLUTION OF INTELLIGENT BEHAVIOR:
IS IT JUST A QUESTION OF TIME?
Julian Chela-Flores
The Abdus Salam International Centre for Theoretical Physics
Strada Costiera 11; 34014 Trieste, Italy and
Instituto de Estudios Avanzados,
Caracas 1015A, Venezuela.
ABSTRACT
Two issues have been discussed
in the past regarding the nature of biology in a universal context:
(1) life may be a cosmic imperative (De Duve, 1995); (2) multicellular
life may be a rare phenomenon in the cosmos, although the existence
of microbial life may still be widespread (the 'Rare-Earth' hypothesis,
Ward and Brownlee, 2000; Ward, 2003). We shall discuss a third
issue: (3) evolution of intelligent behavior may be just a question
of time (and preservation of steady planetary conditions), and
hence ubiquitous in the universe. We will suggest an experimental
approach to the earliest stages of the evolution of intelligent
behavior. Widespread intelligence in the universe has far-reaching
implications, even in the frontier with the humanities (Aretxaga,
2003; Vicuña, R. and Serani-Merlo, A., 2003). Darwin's
theory of evolution is assumed to be the only theory that can
adequately account for the phenomena that we associate with life
anywhere in the universe (Dawkins, 1983). We argue in favor of
the inevitability of the origin and evolution of life by assuming
that Darwinian evolution is a universal process and that the role
of contingency has to be seen beyond the restricted context of
parallelism and evolutionary convergence (Akindahunsi and Chela-Flores,
2003), not only in biology, but also in other realms of science,
such as in the early stages (high red-shift) of the evolution
of the universe itself (Vladilo, 2003). Finally, we suggest that
in the Europan Ocean, or possibly on the icy shell itself, we
are presented with the problem of deciding whether some feasible
experiments may throw some light on the deeper question of the
eventual evolution of intelligent behavior elsewhere in the universe.
We comment on some possible biosignatures of biochemical nature
(Bhattacherjee and Chela-Flores, 2003) and discuss some possible
ways of testing evolutionary biosignatures on or beneath the icy
shell of Europa (Chela-Flores, 2003; Gatta and Chela-Flores, 2003).
References
Akindahunsi, A. A. and Chela-Flores, J. (2003) On the question
of convergent evolution in biochemistry, in this volume.
Aretxaga, R. (2003) Astrobiology and biocentrism, in this volume.
Bhattacherjee, A. B and Chela-Flores, J. (2003) Search for bacterial waste as a possible signature of life on Europa, in this volume.
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.
De Duve, C. (1995) Vital Dust. Life as a cosmic imperative, New York, Basic Books, A Division of HarperCollins Publishers, pp. 296-297.
Gatta, R. and Chela-Flores, J. (2003) Application of molecular biology techniques in astrobiology, in this volume.
Vicuña, R. and Serani-Merlo, A. (2003) Chance or Design in the Origin of Living Beings An epistemological point of view, in this volume.
Vladilo, G. (2003) Interstellar dust as a tracer of environments favourable to planet formation: evidence for the existence of a metallicity threshold, in this volume.
Ward, P.D. (2003) Factors leading to the appearance and survival of metazoan equivalents on habitable planets, in this volume.
Ward, P.D. and Brownlee, D. (2000)
Rare Earth: Why Complex Life is Uncommon in the Universe. Copernicus,
New York.
SEARCH FOR WATER OUTSIDE THE SOLAR SYSTEM
Cristiano Cosmovici
Istituto di Fisica dello Spazio Interplanetario
CNR,Roma,Italy
cosmo@ifsi.rm.cnr.it
ABSTRACT
Since the first discovery
of a Jupiter-mass exoplanet in 1995, a total of 101 planetary
systems with 116 planets (July 2003) are known to exist around
main sequence stars. Most of the detections are based on the radial
velocity method which involves the measurement of the wobbling
of the stars induced by the gravitational field of the orbiting
giant planets. No information can be thus derived on the chemical
composition of the planetary atmospheres and on the existence
of terrestrial-type planets where life may evolve. The ITASEL
programme (Italian Search for Extraterrestrial Life) started in
1994 after the discovery of the first water emission in the atmosphere
of Jupiter induced by a cometary impact (Cosmovici et al,
1996). Our measurements have shown that the water maser line at
22 GHz can be used as a powerful diagnostic tool for planetary
search outside the solar system, as comets are able to deliver
very large amounts of water to planets raising the fascinating
possibility of extraterrestrial life evolution. In 1999 we started
the search for water in 17 different targets up to 50 light years
away from the Sun by using a new developed fast multichannel spectrometer,
coupled to the 32 meter dish of the Medicina radiotelescope, near
Bologna, Italy. Here we report the possible detection of water
emission in the atmospheres of planets orbiting Ups And, 47 CMa
and Eps Eri and the work to be carried out in order to confirm
and extend the discovery.
Reference
1) Cosmovici, C.B., Montebugnoli,
S., Orfei, A., Pogrebenko, S. and Colom, P. (1996) "First
evidence of planetary water maser emission induced by the Comet/Jupiter
catastrophic impact, Planet. Space Sci, 44, 735-739
MINERAL SURFACES AS A CRADLE OF PRIMORDIAL GENETIC MATERIAL
Enzo Gallori
Department of Animal Biology and Genetics, University of Florence, Florence, Italy.
gallori@dbag.unifi.it
ABSTRACT
Molecules which store
genetic information (DNA and RNA) are central to all life on Earth.
The formation of these complex molecules, and ultimately life,
required specific conditions, including the synthesis and concentration
of precursors (nucleotides), the joining of these monomers into
larger molecules (polynucleotides), their protection in critical
conditions (like those probably existing in primeval habitats),
and the expression of the biological potential of the informational
molecules (their capacity to multiply and evolve). Determining
how these steps occurred and how the earliest genetic molecules
originated on Earth is a problem that is far from being resolved.
Classical research in this field has focused on processes in aqueous
solution; however it is difficult to conceive that complex molecules
can be obtained by random collisions in a fully aqueous environment.
We believe that mineral surfaces, e.g. clay minerals, could have
played a crucial role in the prebiotic formation of the biomolecules
basic to life.
In this communication, I will discuss recent data from different
fields strengthening the hypothesis, originally suggested by J.D.
Bernal in 1951, of a surface-mediated origin of life.
THE LIPID WORLD: FROM CATALYTIC AND INFORMATIONAL HEAD-GROUPS TO MICELLE REPLICATION AND EVOLUTION WITHOUT NUCLEIC ACIDS
Doron Lancet, Barak Shenhav, Arren Bar-Even and Ron Kafri,
Dept. Molecular Genetics and the Crown Human Genome Center,
The Weizmann Institute of Science, Rehovot 76100, Israel.
ABSTRACT
A widespread notion is
that life arose from a single molecular replicator, probably a
self-copying polynucleotide in an "RNA world". We have
proposed an alternative "Lipid World" scenario as an
early evolutionary step in the emergence of cellular life on Earth.
This concept combines the potential chemical activities of lipids
and other amphiphiles, with their capacity to undergo spontaneous
self-organization into supramolecular structures such as micelles
and bilayers. In quantitative, chemically-realistic computer simulations
of our Graded Autocatalysis Replication Domain (GARD) model, we
have shown that prebiotic molecular networks, potentially existing
within assemblies of lipid-like molecules, manifest a behavior
similar to self reproduction or self-replication. What is being
propagated is an epigenetic "compositional genome",
i.e. the tally of each of the molecular species included.
In our model, lipids-like amphiphiles may possess a very large variety of chemical structures, including head-groups that resemble amino-acids or nucleotides. Catalysis is proposed to be exerted by such diverse chemical moieties, enhancing amphiphile exchange rates as well the formation of more complex head-groups with similarity to peptides or oligonucleotides. In a more recent version of our model (Polymer GARD or P-GARD), a path is delineated for the gradual transfer of from purely compositional information-storage capacity to increased dependence on linear molecular sequences. Our studies analyze in detail the properties of the emergent mutually catalytic networks within GARD assemblies, and show points of similarity and difference compared to present day cellular networks. We show that within a specific range of physicochemical interaction parameters, homeostatically stable stationary states ("composomes") emerge, capable of evolution-like progression towards higher complexity. Intriguingly, GARD may also provide a natural pathway for enantiomer selection in early biological systems.
Because amphiphile assemblies may form readily and spontaneously under prebiotic conditions, the Lipid World scenario may represent an intermediate "mesobiotic" phase, bridging an a-biotic random collection of organic molecules with a biotic protocell that contains long biopolymers, as well as more intricate information storage, catalysis and replication.
References
1. Segre, D., Ben-Eli,
D., Deamer, D., Lancet, D. The lipid world. Origins Life Evol
Biosphere, 31:119-145 (2001).
2. Segre, D., Ben-Eli, D., and Lancet, D. Compositional genomes:
prebiotic information transfer in mutually catalytic non-covalent
assemblies. Proc. Natl. Acad. Sci (USA) 97 (8): 4112-4117 (2000).
3. Segre, D., Shenhav, B., Kafri, R., and Lancet, D. The molecular
roots of compositional inheritance. J. Theoret. Biol.. 213:481-491
(2001).
4. Shenhav, B.; Segre, D.; and Lancet, D. Mesobiotic emergence:
molecular assemblies that self-replicate without biopolymers.
Adv. Complex Systems 6(1): 15-35 (2003).
5. Segre, D., Lancet, D. Composing Life EMBO Reports, 1(3):
217-222 (2000).
HISTORY OF WATER ON MARS
Philippe L. Masson
Université Paris-Sud
Département des Sciences de la Terre
Laboratoire OrsayTerre (FRE CNRS 2566)
Bât. 509, F-91405 Orsay Cedex (France)
masson@geol.u-psud.fr
ABSTRACT
Besides Earth, Mars is
the only planet with a record of resurfacing processes and environmental
circumstances that indicate the past and possibly recent operation
of hydrologic activity. However the present-day conditions on
Mars are far apart of supporting liquid water on the surface.
Although the large-scale morphology of the Martian channels and
valleys show remarkable similarities with fluid-eroded features
on Earth, there are major differences in their size, small-scale
morphology, inner channel structure and source regions indicating
that the erosion on Mars has its own characteristic genesis and
evolution. The different landforms related to fluvial, glacial
and periglacial activities, their relations with volcanism, and
the chronology of water-related processes, are presented.
A warmer, wet Mars with a dense atmosphere at the time after the
heavy bombardment is supposed to provide the conditions for valley
formation by running water. However, recent images obtained by
the MOC experiment onboard Mars Global Surveyor show relatively
young small-scale alcove-like gullies combined with small channels
and aprons in the walls of impact craters, thus indicating even
recent groundwater seepage and probably short-term surface runoff
under almost current climatic conditions.
THE ORIGIN OF BIOGENIC ELEMENTS
F. Matteucci
Dipartimento di Astronomia
Facolta' di Scienze Matematiche, Fisiche e Naturali
Universita' di Trieste, Italy
ABSTRACT
I will discuss the cosmic
origin of biogenetic elements such as H, C,N,O,
and Fe.
Most of the elements heavier than He are produced by nuclear fusion
inside
stars, whereas the light elements (H, D, He, Li)
have originated in the Big Bang.
I will review the main nuclear processes responsible for the
production of
biogenic elements and discuss which stars are likely to have produced
these elements and how they have been subsequently mixed with
the
interstellar medium. Finally, I will show how all of these processes
can account for the Solar System chemical composition by comparison
with models for the chemical evolution of our Galaxy, and discuss
the
distribution of the biogenic elements along the disk of our Galaxy.
CURRENT STATUS OF THE SEARCH FOR EXTRASOLAR PLANETS
Michel Mayor,
Geneva Observatory, Switzerland
ABSTRACT
More than hundred extrasolar
planets, orbiting other solar-type stars have been discovered
on the last few years. These detections are not a priori surprising
for astronomers. However the orbital properties of these exoplanets
are really unexpected (very short orbital period, large eccentricities
and in a few cases "supermassive" planets). That observed
diversity of planetary systems has forced a rediscussion of scenarios
of planetary formation.
Some attention will also be given to the most recent and unbiased comparisons of chemical properties of stars ,with or without giant planets. It is also interesting to consider first results on the role of stellar multiplicity on properties of exoplanets.
The observation of a planetary transit in 1999 allows the direct measurement of the radius and mean density of an exoplanet: the direct proof that these objects are really gaseous giant planets like Saturn or Jupiter in our own Solar System. New complementary spectroscopic observations begin to reveal physical properties of the planet itself as its chemical composition and properties of its atmosphere.
More and more extrasolar planetary systems with two or three planets are discovered . A fraction of them are systems with planets on resonant orbits.
Apart from the discussion of the status of the research on exoplanets, I would present the most exciting future experiments in that field.
SPONTANEOUS GENERATION OF AMINO
ACID STRUCTURES
IN THE INTERSTELLAR MEDIUM
Dr. Uwe Meierhenrich
Univ. Bremen
Leobener Str.
D- 28359 Bremen
phone: +49-421 218 3401
ABSTRACT
In order to understand
availability and distribution of molecular building blocks of
biological systems during defined phases of the Chemical Evolution
we studied and simulated interstellar processes in the laboratory.
In dense interstellar clouds dust particles accrete ice mantles.
As seen in infrared (IR) observations, this ice layer consists
mainly of water ice, but also of carbon and nitrogen containing
molecules. We deposited a gas mixture consisting of H2O, CO2,
CO, CH3OH and NH3 onto an aluminium surface at 12 K under high
vacuum, 10-7 mbar. During deposition the molecules were subjected
to ultraviolet radiation with main intensity at Lyman-a. After
warm-up, the refractory material was extracted from the aluminium
block, hydrolysed for 24 h at 110 °C with 6 M HCl, derivatized
and finally analysed by enantioselective gas chromatography coupled
to a mass spectrometer. We were able to identify 16 amino acids
in the room temperature products of irradiation [1]. The results
were confirmed by parallel experiments using 13C-labelled ices
in order to exclude contamination. A first 'group' of the identified
amino acids was suggested to serve as the precursors of peptides
and proteins. A second 'group' namely the diamino carboxylic acids
is assumed to contribute to the development of the first genetic
material, the peptide nucleic acid PNA. Beside the two groups
of amino acids, N-heterocyclic organic molecules were identified
that resemble the molecular building block of biological cofactors.
The obtained results support the assumption that the photochemical
products could be preserved in interstellar objects, and in term
be delivered to the Earth during the heavy bombardment which ended
about 3.8 Gyr ago. The remaining organic molecules might have
played an important role on the appearance of primitive life on
Earth. The identification of amino acids in interstellar ice analogues
is suggested to be linked with the prebiotic development of proteins,
genetic material and biological cofactors on Earth.
[1] G.M. Muñoz Caro, U.J. Meierhenrich, W.A. Schutte, B. Barbier, A. Arcones Sergovia, H. Rosenbauer, W.H.-P. Thiemann, A. Brack, J.M. Greenberg: Amino acids from ultraviolet irradiation of interstellar ice analogues. Nature 416 (2002), 403-406.
RECENT ADVANCES AND SETBACKS
IN SEARCHING FOR THE OLDEST LIFE ON
EARTH A GEOLOGIST'S VIEWPOINT
Stephen Moorbath
Department of Earth Sciences, University of Oxford, Oxford OX1 3PR, UK
stephen.moorbath@earth.ox.ac.uk
ABSTRACT
In recent technical and popular scientific literature it has become
almost axiomatic to claim that life began on Earth at least 3.9
- 4.0 billion (Ga) years ago. The most intense debate on earliest
life centres around early Precambrian (Archaean) rocks from West
Greenland, whose exact age, field relationships to dated rocks,
geological identification, mode of genesis, interpretation of
trace element abundances as well as carbon-isotopic abundance
ratios, are in major dispute. These topics will be briefly discussed
in the talk, and it is concluded that the most strongly disputed
rocks (on Akilia Island, West Greenland) contain no record of
biological activity whatever. Indeed, recent work (1) demonstrates
that the crucial carbon-bearing rocks on Akilia Island, identified
by several workers (2,3) as chemical sediments closely related
to banded iron-formation (BIF), are actually banded quartz-pyroxene
rocks of mixed igneous and metasomatic parentage which have no
intrinsic biological significance.
Elsewhere in West Greenland, within the 3.73.8 Ga Isua Greenstone
Belt (IGB), 13C depletion in graphite particles in a genuine
BIF has been claimed as evidence for biological activity (2).
However, it has been shown (4) that this particular BIF was infiltrated
by metasomatic carbonate fluids, in which metamorphic (thermal)
disproportionation to elemental carbon has occurred. A further
occurrence of IGB metamorphosed sedimentary rocks is claimed (5)
to contain biogenic 13C - depleted graphite, possibly derived
from the detritus of planktonic organisms. This occurrence is
still under debate, but the overall evidence is highly speculative
and requires much stronger evidence.
Repeated claims (e.g. 6) for 3.7 - 3.8 Ga spherical microbes in
a horizon of IGB chert are implausible. These spheres occur in
rocks which are extremely strongly deformed by stretching, and
no spherical shape could possibly have been preserved from time
of deposition. The spheres are almost certainly recent biological
contaminants residing on the rock's surface and in cracks (7).
Thus it is essential that all analysed ancient sedimentary rocks
must be completely decontaminated from younger organisms before
being tested by any technique for genuinely ancient biological
activity. This is just as important for terrestrial rocks as it
is for planetary samples. Indications are that such decontamination
was not adequately carried out in some, or all, of the rocks discussed
here.
Brief mention will be made of ongoing debate concerning the biogenicity
of putative bacterial or cyanobacterial microfossils from 3.47
Ga Apex cherts in western Australia, long thought to provide the
oldest morphological evidence for life on Earth (8). These microstructures
have recently been reinterpreted (9) as secondary artefacts formed
from amorphous graphite within multiple generations of metalliferous
hydrothermal vein chert and volcanic glass, thus offering no support
for primary biological morphology. Just as in Greenland (see above),
a more realistic geological identification of the occurrence has
cast severe doubt on the biological interpretation of these Apex
chert microstructures.
Despite much effort, albeit hampered by varied geological misidentifications,
there still appears to be no undisputed geological evidence for
when and where life started on Earth. At any rate, popular suggestions
for creation, or survival, of life in supposedly (and implausibly)
sheltered environments during the putative, massive Late Heavy
Bombardment of the Earth at around 3.9 4.0 Ga need no longer
hold credence. We know for sure from the evidence of surviving
rocks that by 3.7 3.8 Ga geological processes at and near
the surface of the Earth were rapidly becoming recognisably uniformitarian,
perhaps allowing life to get started in a more leisurely and unmolested
fashion on mineral surfaces in Darwinian "warm little ponds".
References
(1) Fedo, C.M. and Whitehouse,
M.J. (2002). Metasomatic origin of quartz pyroxene rock,
Akilia, Greenland, and implication for Earth's earliest life.
Science 296, 1448 1452.
(2) Mojzsis, S.J., Arrhenius, G., McKeegan, K.D., Harrison, T.M.,
Nutman, A.P. and Friend, C.R.L. 1986. Evidence for Life on Earth
before 3,800 million years ago. Nature 384, 55 59.
(3) Nutman, A.P., Mojzsis, S.J. and Friend, C.R.L. 1997. Recognition
of > 3850 Ma water-lain sediments in West Greenland and their
significance for the early Archaean Earth. Geochim. et Cosmochim.
Acta 61, 2475 2484.
(4) Van Zuilen, M.A., Lepland, A. and Arrhenius, G. 2002. Reassessing
the evidence for the earliest traces of life. Nature 418, 627
630.
(5) Rosing, M.T. 1999. 13C depleted carbon microparticles
in > 3700 Ma sea-floor sedimentary rocks from West Greenland.
Science 283, 674 676.
(6) Pflug, H.D. 2001. Earliest organic evolution. Essay to the
memory of Bartholomew Nagy. Precambrian Res. 106, 79-91.
(7) Appel, P.W.U., Moorbath, S. and Myers, J.S. 2003. Isuasphaera
isua (Pflug) revisited. Precambrian Res. In press.
(8) Schopf, J.W. 1993. Microfossils of the Early Archean Apex
Chert: New evidence of the antiquity of life. Science 260, 640
646.
(9) Brasier, M.D. et al. 2002. Questioning the evidence for Earth's
oldest fossils. Nature 416, 76 81.
PLANETS WITH DETECTABLE LIFE
Tobias Owen
Institute for Astronomy
University of Hawaii
Honolulu, HI, USA
ABSTRACT
We now know that more
than 100 planets exist around stars other than the sun. Yet it
appears that only one of these planetary systems may contain a
planet with detectable life. This means it could have an Earth-like
planet in its habitable zone. This outcome is less disturbing
than it may appear, however, given the observational difficulties
for finding such systems. Using ourselves as an example, we can
assess the probability that such a planet will have acquired the
necessary water and biogenic elements for life to begin. We can
then consider the strategies for determining whether or not life
exists on that planet at the present time.
CURRENT STATUS & EXPECTED
EXOBIOLOGICAL RETURN
OF THE CASSINI-HUYGENS MISSION
François RAULIN
LISA - UMR 7583, CNRS & Universités Paris 12 et Paris 7, 61 Avenue du Général de Gaulle, 94010 Créteil Cedex France
ABSTRACT
The NASA-ESA Cassini-Huygens
mission was successfully launched in October 1997. The spacecraft
includes a Saturn orbiter and a Titan atmospheric probe. It has
then been on an interplanetary trajectory toward Saturn. The Cassini
Spacecraft flied-by Jupiter on December 2000 and will reach the
Saturn system in 2004. Cassini will then become a Saturn orbiter
and will fly-by its satellites, including the largest one, Titan.
At the end of 2004, it will release the Huygens probe which will
penetrate Titan's atmosphere on January 14, 2003. In 2000 an anomalous
behavior concerning the relay link between the probe and the orbiter
was identified, due to Doppler effect. It was putting into great
danger the data transfer of the probe, and thus the whole Huygens
probe mission. A joint ESA-NASA task force, the Huygens Rocovery
Task Force was established in January 2001. The HRTF work was
successfully conducted and a solution was identified, based on
changing the Cassini trajectory. The trajectory now includes three
new Titan fly-bys allowing to have a probe delivery at higher
altitude of the orbiter, drastically reducing the Doppler effect
and the resulting problem of data transfer. The Huygens mission
is now safe again, as is the rest of the mission.
One of the main objectives of the Cassini-Huygens mission is to
explore Titan in great detail and to study in particular the many
exobiological aspects of Titan, this strange and exotic world
which presents so many analogies with our planet. The Cassini
orbiter and the Huygens probe, in a complementary way, will systematically
study the many chemical and physical aspects of the different
parts of what can be called the « geofluid » of Titan.
Many of the twelve instruments of the Cassini orbiter and most
of the six instruments of the Huygens probe will provide much
information of crucial importance for our knowledge of the complexity
of Titan's organic chemistry.
Indeed, because of the presence of a dense atmosphere, mainly
made of N2 with noticeable fraction of CH4, and of an environment
very rich in organics, and of many couplings involved in the various
parts of its geofluid, in spite of low temperatures and the absence
of liquid water, Titan is a reference for studying prebiotic chemistry
on a planetary scale. Many programs have recently been developed
to study in detail Titan's chemistry, in direct connection with
the Cassini-Huygens mission (and even post-Cassini exploration
of Titan ! !). They include new observations, development of photochemical
models, laboratory determination of IR and UV spectra of organics
of interest for Titan's atmosphere, and experimental studies,
such as laboratory simulation of Titan's gas and aerosol organic
chemistry.
The paper will present the current status of the Cassini-Huygens
mission and will review the exobiological aspects of Titan. It
will also present some of the new data concerning Titan's organic
chemistry that have been obtained through the several possible
approaches and discuss the exobiological implication of the potential
scientific return of the Cassini-Huygens mission.
References
Coll et al, (2003), Oxirane:
An exotic oxygenated organic compound in Titan? Astrophys.
J, in press.
Lebreton, J.P., European Space Agency (1997). Huygens : Science,
Payload and mission, ESA SP- 1177.
Lorenz, R. (2000). Post-Cassini Exploration of Titan : Science
rational and mission concepts, J. Brit. Planet. Soc. 53,
218-2344.
Lorenz, R. and Mitton J. (2002).
Lifting Titan's Veil. Cambridge Univ. Press, Cambridge,
UK.
Raulin F. and T. Owen (2003). Organic chemistry
and exobiology on Titan, Space Science Review., in press.
Ramirez et al, (2002). Complex Refractive Index of Titan's Aerosol
Analogues in the 200-900 nm domain, Icarus, 156(2),
515-530 (2002).
VIABLE HALOBACTERIA FROM PERMIAN SALT DEPOSITS - AND IN OUTER SPACE ?
Helga Stan-Lotter
Institute of Genetics and General Biology, University of Salzburg, Hellbrunnerstr. 34, A-5020 Salzburg, Austria
ABSTRACT
From rock salt of Permo-Triassic
age in an Austrian salt mine we isolated viable halophilic archaebacteria
in recent years. Chemotaxonomic and molecular characterization
of several strains led to their recognition as novel species.
Two of those were designated Halococcus salifodinae and
Halococcus dombrowskii. Several other coccoid isolates
from British and German salt sediments of similar geological age
proved to be members of the species H. salifodinae, as
judged from their molecular, chemical and physiological properties.
These microorganisms have apparently survived in the salt sediments
over extremely long periods of time. Halobacteria could therefore
be suitable model organisms for exploring the possibility of long-term
survival of microbes on other planets. This notion appears all
the more plausible since extraterrestrial halite has been detected
in meteorites and is assumed to be present in the subsurface ocean
on Europa. Our efforts are directed at the identification of the
microbial content of ancient rock salt and the development of
procedures for the investigation of the halobacterial response
to extreme environmental conditions. The exploration of Mars is
a target of space missions in the 21st century; therefore, testing
the survival of haloarchaea under conditions comparable to present-day
Mars, using a simulation chamber, was begun. Preliminary results
with Halococcus and Halobacterium species suggested
at least tenfold higher survival rates when cells were kept in
liquid brines than under dry conditions; staining of cells with
the LIFE/DEAD kit, which discriminates between damaged and intact
membranes, corroborated these results.
ANCIENT LIFE ON EARTH AND MARS
1Mark A. van Zuilen, 2Aivo Lepland, 3Gustaf Arrhenius 1Centre de Recherches Pétrographiques et Géochimiques, 15 Rue Notre Dame des Pauvres, BP-20, 54501 Vandoeuvre les Nancy, France(markvz@crpg.cnrs-nancy.fr),
2Geological Survey of Norway, Leiv Eirikssonsvei 39, 7491 Trondheim, Norway, (aivo.lepland@ngu.no)
3University of California, San Diego, La Jolla CA 92093-0236, USA (arrhenius@ucsd.edu)
ABSTRACT
The search for signatures
of extinct life on the early Earth is made difficult if not impossible
due to poor preservation of the rock record. The very few exposed
formations that date back beyond 3.5 Ga ago, have all been subject
to high or intermediate grade metamorphism. This would have transformed
the shapes of any microfossils beyond recognition, turned organic
matter into kerogen and ultimately crystalline graphite. The search
for life in Early Archean rocks therefore depends entirely on
chemical and isotopic indicators. It is widely assumed that carbon
isotope signatures of carbonaceous matter can be used to distinguish
a biologic origin. However, such interpretations about ancient
traces of life can only be made within the context of specific
geologic circumstances requiring (1) control on recent contamination
in the rock sample (is the carbonaceous material indigenous or
exotic), (2) reliable protolith interpretation and control of
secondary, metasomatic processes, (3) understanding of alternative
abiogenic mechanisms that produce carbonaceous matter, and (4)
understanding of the carbon isotopic systematics related to such
processes.
A detailed study is presented of graphite occurring in different rock types in the 3.8 Ga Isua Supracrustal Belt (ISB), southern West Greenland. It will be shown that most graphite in Isua rocks is formed epigenetically either by dehydration and cooling of metamorphic fluids during serpentinization of ultramafic rocks, or by thermal disproportionation of siderite in secondary carbonate veins. Thermodynamic constraints of these processes and associated carbon isotope systematics are discussed.
The absence of an unambiguous record of life during Earth's earliest history, may be supplemented by a record of life on Mars. In the first billion years after formation this planet may have had an ocean and an active geological setting. Traces of early Martian life have been claimed in Martian meteorite ALH84001. However, it will be shown that biosignatures found in this meteorite can easily be explained by processes accompanying the thermal disproportionation of Fe-carbonates that is observed in the Isua Supracrustal Belt.
These problems, encountered with
the tracing of life in altered rocks (either meteorites from Mars
or highly metamorphosed Archean rocks), therefore highlight the
need for in-situ analysis, or sample return of potentially relatively
unaltered Martian marine or lacustrine sedimentary deposits, protected
against radiation induced oxidation in the subsurface domain.
FACTORS LEADING TO THE APPEARANCE AND SURVIVAL OF METAZOAN EQUIVALENTS ON HABITABLE PLANETS
Peter D. Ward,
Department of Biology,
The University of Washington,
Seattle, USA 98195.
ABSTRACT
There is much new evidence
supporting the hypothesis that metazoan equivalents require a
narrow range of environmental conditions maintained over long
periods of time, and that these two factors result in there being
a relatively low percentage of metazoan-bearing planets. Microbial
life, on the other hand, is probably widespread in the Universe,
as evidences by the presence of extremophiles in a wide range
of terrestrial environments. The requirements of metazoan life
may include the following. In addition to a planet residing in
the Continuous Habitable Zone allowing the existence of liquid
water on its surface, additional requirements might include a
relatively metal-rich star, plate tectonics, and a large Jupiter-type
planet in a stable orbit outboard of the habitable planet. In
the case of the Earth, additional elements fostering a diverse
assemblage of animals and higher plants have been the presence
of a large moon, an ocean that is only partly planet-covering,
a magnetic field, and a position in the galaxy ensuring an abundance
of metal, but a low incidence of nearby supernovae and close stellar
encounters that cause mass extinctions. It is clear that our own
planet has undergone very few mass extinction episodes. Here I
will examine possibilities of the origin of life not on new planets,
but on planets that have undergone sterilization due to large
body impact or high energy bombardment from nearby supernova or
gamma ray bursts. While most models for the origin of life start
with planets with early Earth conditions, there may be quite
different pathways on planets that already have oxygen and abundant
organic constituents from the newly deceased.
EARLY LIFE AND HYDROTHERMAL
ENVIRONMENTS
Frances WESTALL,
Centre de Biophysique moléculiare
CNRS
Rue Charles Sadron
45071 Orléans cedex 2,
France
ABSTRACT
The oldest rocks to provide
information about the environment of early life, together with
clear evidence of life, come from the Early Archaean greenstone
terrains of Barberton in W. South Africa and the Pilbara in NW
Australia. Geological investigations of these terrains document
a sedimentary environment dominated by volcanic and hydrothermal
(hot spring) activity that occurred both underwater and on land.
Microbial mats formed at the edges of the vents and even on the
cupola crowning the vent exits. Mats that formed further away
from vent openings were, nevertheless, influenced by their effusions.
It, thus, appears that early life on Earth was, by definition,
thermophilic.
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.
DYNAMICAL EVOLUTION OF EXOPLANETS IN RESONANCES
Andrea Sanchez and Julio A. Fernandez
Departamento de Astronomia, Facultad de Ciencias
Montevideo, URUGUAY
ABSTRACT
The global properties
of the 101 extrasolar planets (or exoplanets
for short) so far discovered, which include 88 single-planets
and
11 multiple-planet systems, are discussed and compared with our
standard ideas of planet formation, as have been developed for
explaining the main features of our solar system.
The discovered exoplanets have masses around that of Jupiter or
larger but, in sharp contrast with Jupiter, most of them are
close to their central stars and have large eccentricities.
The different alternatives that could explain why the discovered
exoplanets have orbital properties so different from those of
the
Jovian planets are analyzed, as well as the dynamical stability
of multiple planet systems, In particular those having two planets
locked in the 2:1 mean-motion resonance.
Since the current most widely used search technique (spectroscopy)
strongly favors the discovery of massive planets close to their
central stars, it is possible that they are very weird
cases, uncommon in comparison with regular planetary systems like
ours.
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
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.
ISOTOPIC EVIDENCE FOR MICROBIAL SULFATE REDUCTION AND METHANOTROPHY DURING THE LATE ARCHEAN, WITWATERSRAND BASIN, SOUTH AFRICA
A. Erik Boice, Brett J. Tipple and Lisa M. Pratt,
Department of Geological Sciences, Indiana University,
1001 East 10th Street, Bloomington, IN 47405
ABSTRACT
Stable isotope ratios
were determined for carbon (d13C) in organic matter and carbonate
and for sulfur (d34S) in pyrite for a stratigraphic profile from
a core containing 60 meters of the late Archean Booysens/Kimberly
(B/K) Shale Formation and a portion of the underlying Krugersdorp
Quarzite Formation. The studied core was collected at a subsurface
depth of 1.8 km in Evander shaft #8 operated by Harmony Gold Inc.
The Evander sub-basin is located on the northeast rim of the Witwatersrand
Basin. Silty shales are the dominant lithofacies in the core but
interbedded siltstones and several meters of underlying gray quartzites
are present. Carbonate (Ccarb) and Organic carbon (Corg) contents
in core samples range from <0.05 to 2.26 wt% and <0.05 to
0.42 wt%, respectively. Values of d13C for organic matter (d13Corg)
and carbonate minerals (d13Ccarb) range from -42 to -35 and 14.6
to -10.1, respectively. Distinct negative shifts in d13Corg values
occur in laminated clay-rich intervals while positive shifts occur
in carbonaterich intervals. Values of d34S for Cr-reducible
disulfide minerals (predominantly pyrite) range from -3.2 to +2.3.
The most negative d34S values occur in the laminated intervals
that contain the most negative d13Corg values. d13Ccarb values
lower than -10 are inferred to reflect bicarbonate derived from
methane. Microprobe imaging shows partial to complete chlorite
replacement of original rhombohedral carbonate grains. The combined
carbon and sulfur isotopic evidence suggest a thriving community
of methanotrophic and sulfate-reducing bacteria in laminated,
muddy sediment deposited during maximum marine flooding of the
Witwatersrand Basin.
THE ROLE OF CLAY MATERIAL IN SHIELDING DNA AGAINST X-RAY RADIATION.
Ciaravella A., Barbera M., Micela G., Candia R., INAF-Osservatorio Astronomico, Palermo
Scappini F, ISMN-CNR, Bologna
Cecchi-Pestellini C., ISAC-CNR, Firenze
Franchi M., Gallori E., Universita', Firenze
ABSTRACT
X-ray experiments have
been conducted on water solutions of free DNA and clay absorbed
DNA. The level of damage has been analyzed using biological transformations.
Results will be presented and discussed in the context ofthe origin
of life.
PREBIOTIC CHIRALITY TRANSFER FROM EXTRATERRESTRIAL Ca-TETRASUBSTITUTED a-AMINO ACIDS TO PROTEIN AMINO ACIDS
Marco Crisma a, Alessandro Moretto a, Fernando Formaggio a, Claudio Toniolo a, Bernard Kaptein b, Quirinus B. Broxterman b
a. Institute of Biomolecular Chemistry, CNR, Department of Organic Chemistry, University of Padova, Via Marzolo 1, 35131 Padova, Italy
b. DSM Research, Life Sciences, Advanced Synthesis and Catalysis, P.O. Box 18, 6160 MD Geleen, The Netherlands
ABSTRACT
A recent analysis of the amino acid content of the Murchison meteorite,
fallen over Australia in
1969, revealed the presence of four chiral Ca-tetrasubstituted
a-amino
acids, namely isovaline (Iva), Ca-methyl norvaline (Me)Nva], Ca-methyl
isoleucine [(aMe)Ile], and Ca-methyl alloisoleucine [(aMe)aIle]
with a small, but significant, L(S) enantiomeric excess (up to
9%). Related findings in the protein amino acid fraction were
considered of no significance in view of a possible terrestrial
contamination. On the contrary, this possibility is quite remote
for these Ca-tetrasubstituted a-amino acids, the occurrence
of which on terrestrial compounds was reported only for Iva. Moreover,
Ca-tetrasubstitution protects amino acids against
racemization. These results suggest that Ca-tetrasubstituted
a-amino
acids of extraterrestrial origin could have been the homochirality
seeds for life in our planet. However, this hypothesis implies
that the enantiomeric excesses would have been somehow transferred
from Ca-tetrasubstituted a-amino acids to protein amino acids. In
this connection, we have planned a detailed study aimed at determining
if and how derivatives or peptides based on Ca-tetrasubstituted
a-amino acids could have reacted with protein amino acids and
favoured one of their enantiomers over the other.
In this Communication we report on the synthesis and conformational
studies of the Iva, (aMe)Nva, and (aMe)Val, homochiral homopeptides. These
Ca-tetrasubstituted residues bear either a linear [Iva and (aMe)Nva]
or a b-branched [(aMe)Val] side chain. Solution (FT-IR absorption,
CD, 1H NMR) and crystal-state (X-ray diffraction) conformational
analyses indicate that these homo-peptides tend to fold in b-turn
and 310-helical structures (depending upon main-chain length).
Homochiral homopeptide sequences from Iva, (aMe)Nva, and
(aMe)Val, activated as Ac-(AA)n-OXL [Ac, acetyl; OXL,
5(4H)-oxazolone; n = 2-8] were allowed to react with a
racemic mixture of a protein amino acid, H-D,L-Val-OMe. The competitive
formation of the resulting diastereomers was quantified. The effects
of temperature and reaction time were also examined. We have found
variable amounts of diastereomeric excesses [up to 58% for the
longest (aMe)Val homo-peptides]. Our results clearly show that
the incorporation of the heterochiral protein amino acid
is increasingly preferred with: (i) increasing difference in size
between the two side chains of the Ca-tetrasubstituted a-amino acid,
and (ii) increasing main chain length of the peptide oxazolone,
which in turn favours the onset of stable secondary structure
elements.
Thus, it is reasonable to conceive a racemic primordial soup of
protein amino acids which in the long run is converted to a soup
with a more and more abundant L enantiomeric excess due to the
depletion of the other isomer by the Ca-tetrasubstituted oligomers. At this stage,
various possible mechanisms of peptide bond formation may have
further amplified this phenomenon, eventually producing the first
functional proteins.
SOME STATISTICAL ASPECTS RELATED
TO THE STUDY OF TREELINES
IN PICO DE ORIZABA
LUIS CRUZ-KURI
Instituto de Ciencias Básicas. Universidad Veracruzana
Carr. Xalapa-Ver., Km. 3.5, Las Trancas, Xalapa, Ver., MEXICO
CHRISTOPHER P. MCKAY
NASA-Ames Research Center
Moffett Field, CA 94035, USA
RAFAEL NAVARRO-GONZALEZ
Laboratorio de Química de Plasmas y Estudios Planetarios
Instituto de Ciencias Nucleares, UNAM, Circuito Exterior,
Ciudad Universitaria, Apartado Postal 70-543, MEXICO
ABSTRACT
Pico de Orizaba, Mexico's highest peak, is the fourth highest
volcano in the Northern Hemisphere, it has a glacier on the north
face and it has the highest tree line in the world (> 4200
m). Pico de Orizaba (19º N) has environmental conditions
that probably could have occurred in ancient Mars. Therefore,
related to the survival of ecosystems in extreme environments,
with possible applications to life on Mars, we started to monitor
the mountain in several sites, above, below and within the tree
line of the domineering species P. hartweggi. Since March
of 1999 we have been studying physical and chemical properties
of soil as well as those of microbial activity. Of particular
interest is to study tree lines at thermal gradients, for which,
soil temperatures at various depths, as well as external temperatures,
tree-trunk temperatures and other measurements such as air humidity,
etc., are being recorded hourly since then, in an ongoing process
to continue for several years. The present is a report of some
of the continuing statistical analysis performed on the data,
in an effort to detect spatial and temporary patterns.
THE HUNT FOR "BIOLOGICALLY
ACTIVE" BIOPOLYMERS:
SPONTANEOUS FOLDING OF RANDOM RNA OLIGOMERS
Marco Franchi*, Davide De Lucrezia§, Cristiano Chiarabelli§, PierLuigi Luisi§, Enzo Gallori *
Department of Animal Biology and Genetics, University of Florence - Florence (Italy)
§ Institute of Polymers, Swiss Federal Institute of Technology, ETH Zurich - Zurich(Switzerland)
marco.franchi@dbag.unifi.it
ABSTRACT
The probability of occurrence
of biopolymers with a well defined steric conformation is one
of the central questions concerning the origin of life on Earth.
In fact, whatever was the nature of primitive "biological"
polymers, their chemical activity and specialized functions depended
on the acquisition of durable and stable secondary and tertiary
structures.
Because of the possible pivotal role of RNA in the evolution of
life on Earth, we have studied the folding properties of RNA oligonucleotides
with random sequences. We developed a plasmid library for in vitro
transcription of random RNAs, 150 nucleotides long. The resulting
RNA molecules were tested for their sensitivity to S1 nuclease
at different temperatures ranging from 37 to 60°C in order
to evaluate their ability to form internal double helices and
to acquire secondary and tertiary structures.
Preliminary results of these studies suggest that most (~70%)
random oligomers acquired a secondary structure stable up to 50°C
but lost their folding at higher temperatures. Interestingly,
a small percentage (~9%) of the oligomers were very stable even
at relatively high temperatures (55-60°C), suggesting a possible
role of these thermostable steric structures in the hot environments
of the primeval Earth.
CHARACTERIZATION OF EXTRASOLAR PLANET CANDIDATES
Jose Gallardo and Dante Minniti.
Departamento de Astronomia y Astrofisica,
Facultad de Fisica,
P. Universidad Catolica de Chile.
Av. Vicuna Mackenna 4860.
Santiago Chile.
ABSTRACT
We report photometric
classifications of 62 stars where OGLE found transits in order
to classify the most promising candidates to have extrasolar planets.
We use the difference of stellar flux dF, delivered by OGLE data,
and the stellar radius R_star, derived from the spectral type
found by our IR photometry, to determine the companion's radius
R_planet. Besides, we present a stellar environment study to verify
properties of these candidates like distance, metallicity and
stellar populations. Follow up spectroscopic observations will
enable us to obtain their masses and to discriminate among white
and brown dwarf and giant planets.
PROPOSING A UNITED NATIONS SECRETARY GENERAL SETI INTERNATIONAL ADVISORY BOARD
Genta G.
Department of Mechanics, Politecnico di Torino,
C. Duca degli Abruzzi 24, 10129, Torino, Italy
genta@polito.it / fax: ++39 011 564 6999Picco G.
Advisor to the United Nations Secretary General at the Level of Under-secretary New York USAGaleotti P.
Department of Physics, University of Torino, Torino, ItalyNoventa D.
Non Govermental Peace Strategies Project Geneve Switzerland
ABSTRACT
SETI's Post-Detection
Protocols have recently identified a novel means of interaction
between SETI and the United Nations.
Through this proposal, the Italian
SETI Study Center hopes to realize the following:
1) The preparation of an ad hoc study on SETI by an international
panel of experts of various disciplines for the United Nations,
addressed to the Secretary General;
2) The identification and formalization of the role of the United
Nations Secretary General and his International Advisory Board
in the functions of decision-making, management of/communication
with the international media system vis-à-vis the possible
detection of artificial signals of proven extraterrestrial origin.
SETI's work program includes the
following:
1. TARGET: To create an effective, temporary board for the United
Nations Secretary General, with information and situation support
capabilities per SETI.
2. ACTIVITY:
To prepare a state of the art document on SETI, covering all possible
aspects (including scientific, philosophical, social, media, intelligence
and security aspects);
To update this document on a bi-annual basis;
To act as the United Nations Secretary General's situation support
staff in instances of extraterrestrial signal detection and, in
particular, to assist him in the decision-making process upon
successful detection of such signals.
The board will, in effect, develop, and make official, the contents
of the SETI Post-Detection Protocols, expanding its activity to
managing communication of any signal detection to the international
media system.
3. COMPOSITION of the International
Advisory Board: experts with internationally recognized credibility
and competence in the following areas:
Astrophysics and Cosmology
Bioastronomy
Radioastronomy
Astronautics and Space Exploration
Mathematics and Informatics
International Space Law
Social Sciences
International Relationships
Philosophy of Science
Religious Aspects
Mass Media
Intelligence and Military Aspects
4. AGENDA: The International Advisory Board expects to meet every
two years to update and follow-up on current needs.
FUNDING: The funds required to
create, maintain and support the activities of the international
advisory board will not be provided by the United Nations but
rather will be raised in the private sector, through various foundations,
companies and associations with adequate international standing.
EFFECTS OF NON-CARBONACEOUS METEORITIC EXTRACTS ON THE GERMINATION, GROWTH AND CHLOROPHYLL CONTENT OF EDIBLE PLANTS
VICENTE MARCANO1, PAULA MATHEUS1, CESYEN CEDEÑO2, NELSON FALCON3 AND ERNESTO PALACIOS-PRÜ1,4
1 Evolutionary Biology and Chemistry Laboratory, Electron Microscopy Center, University of the Andes, P. O. Box 163, Mérida, Venezuela.
2 Crystalography Laboratory, Faculty of Sciences, University of the Andes, Mérida, Venezuela.
3 Department of Physics, Faculty of Science and Technology, University of Carabobo, Valencia, Venezuela.
4 International Institute of Advanced Studies, Simón Bolívar University, Caracas, Venezuela.
ABSTRACT
Several scenarios have
been conceived in order to establish eventually human settlements
in space stations or on planetary bodies or satellites, using
indigenous space resources. Nutrients for plant cultures in space
could be obtained mining asteroids or collecting micrometeorites.
Carbonaceous and non-carbonaceous meteorites contain nutrients
needed for biological activity. Experiments utilizing non-carbonaceous
material are not known. Selection of edible plants by human settlements
in the space should take in account their capacity to compensate
the effects that the unfiltered solar radiation, galactic radiation
and negligible gravity would produce on humans. We focus our investigation
on the effects that non-carbonaceous meteoritic extracts could
has on the germination and growth of these plants and the ability
of non-carbonaceous meteoritic resource to serve as nutrient source
for young plants having edible uses. Selected plants were two
dicotyledons (Lycopersicon esculentum and Daucus carota)
and one monocotyledon (Zea mays). Solution cultures were
developed using seeds and seed-embryos. Meteoritic powder was
obtained from the Vigirima mesosiderite, which was analyzed by
X-ray diffraction and atomic absorption spectrometry (AAS).
Results showed that extracts having variable concentrations of
meteoritic matter produced an earlier germination in some plant
species but the increase of the concentrations produced a decreased
germination. However, total germination rate was higher in the
presence of meteoritic extracts than in the presence of blanks
in the all species. A high metabolic yield in the protein synthesis
was seen in dicotyledons utilizing Type-A and B extracts having
concentrations of 4.16-8.33 x 103 mg l-1. Phaeophytinization index
and chlorophyll a/b ratio, suggested an negative effect of the
heavy metals or acidic ions over the photosynthetic activity when
extracts having high meteoritic concentrations were utilized.
However, a higher chlorophyll (a) production in comparison to
that of chlorophyll (b) was seen in extracts (Type-A and B) having
low concentrations of meteoritic matter. On the other hand, Z.
mays seed-embryos growing in extracts (Type-D) having 3.53
x 104 mg l-1 of meteoritic matter showed a protein production
(9.81 x 10-2 mg protein mg wet wt.-1) higher than that observed
in seed-embryos coming from extracts having lower concentrations.
However, in Murashige medium, the seed-embryos exhibited a enhanced
growth and a relatively higher protein production (10.3 x 10-2
mg protein mg wet wt.-1). Further, chlorophyll (a+b) synthesis
was higher in Murashige medium than in meteoritic extracts but
chlorophyll a/b ratio was < 1 in the all extracts and blanks.
Our results suggest the usefulness of the non-carbonaceous meteoritic
resource as a complementary soil component or fertilizers for
culture of edible plants in space human settlements and mainly
for the production of young plants due to the positive metabolic
effects on the chlorophyll synthesis, mitochondrial metabolism
and cellular division caused by PO43-, Fe2+, Cu2+ and Ca2+ ions.
Earlier germination responses obtained in the experiments showed
the possibilities to utilize in space germination chambers having
wet substrates containing meteoritic-powder solutions to obtain
a higher number of seedling in a minimum degree of time. Utilization
of seed-embryos could be considered an efficient alternative to
develop in space stations or human settlements on Mars or Moon.
These results reveal also the biological potential of the non-carbonaceous
meteoritic matter for the growth of organisms in the early Earth,
Mars, and probably in other planetary bodies beyond our Solar
system.
HOW ADVANCED IS ETI?
ARE SCIENTIFIC AND TECHNOLOGICAL PROGRESS LIKELY TO BE ENDLESS?
PAOLO MUSSO
Pontifical University of the Holy Cross of Roma
V. Montevideo 2A/-6, 16129 Genova (GE) - Italy
musso@nous.unige.it
ABSTRACT
One of the most widespread
commonplace in discussing about the possible existence of other
technological civilizations is that they should be very more advanced
than ours.
At a cosmic scale, indeed, mankind was born just yesterday. So,
it is very likely that almost any other civilization we could
ever detect will be much older than ours. But does it necessarily
imply that it should be also much more advanced?
Since we are just at the dawn of our technological age, but nonetheless
in only four centuries have achieved such a great progress, a
positive answer may seem to be obvious. But, in fact, this implies
the assumption that both scientific and technological progress
are endless processes, which is not obvious at all. In
this paper this point will be discussed, with the help of two
diagrams analyzing the only example of scientific and technological
progress we know, that is the one of our own terrestrial society.
PREBIOTIC POLYMERIZATION OF AMINOACIDS. A MARKOV CHAIN APPROACH
S. Ramos-Bernal1, G Mosqueira2 and A. Negron-Mendoza1
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
The principle of self-ordering
of amino acids, as related to the origin of life research, has
been extensively studied and interpreted by S. Fox and collaborators
(Fox and Dose, 1977). Such principle establishes that the reactivity
between different amino acids is not even.
The relevance of the self-ordering principle to the emergence
to minimal self-reproducible chemical systems has been already
analyzed in probabilistic terms. These considerations concluded
that the polymerization phenomena associated to the origin of
life had to be strongly biased. Otherwise the probability of nucleation
of a "minimum life would be excluded (Mosquiera, 1988).
In the present work, we study the Markov chain approach for the
oligomerization of amino acids based on the physicochemical and
volume differences among reacting amino acids. The results found
may be of importance as it makes more accessible the replication
of minimal chemical machinery compatible with life processes.
References
Fox, S. and Dose, K. (1977),
Molecular evolution and the origin of life, Marcel Dekker,
Inc., New Yor.
Mosqueira, G. (1988), Origins
of Life and Evol. Biosphere, 18, 143-156.
ANALYSIS OF THE WORKS OF THE
GERMAN NATURALIST
ERNST HAECKEL (1834-1919)
ON THE ORIGIN OF LIFE
Florence Raulin-Cerceau
Centre Alexandre Koyré
(CNRS-EHESS-MNHN-UMR 8560)
Muséum national d'Histoire naturelle
57 rue Cuvier - F-75005 Paris
e-mail : raulin@mnhn.fr
ABSTRACT
During the second part of the nineteenth century, the problem
of the emergence of living beings was much debated. The theory
of natural selection (The Origin of Species, Darwin, 1859)
led to wonder about the beginning of life, while the theory of
spontaneous generation for microorganisms still persisted. However,
Pasteur's series of experiments (Mémoire sur les corpuscules
organisés qui existent dans l'atmosphère, Annales
des Sciences Naturelles, 1861) proved that preexistent germs in
the atmosphere were the response to the question of spontaneous
generation and then, that life was always antecedent to life.
Despite this demonstration, however, many scientists adopted the
evolutionist point of view while accepting that a primitive life
could arise from continual spontaneous generation. Therefore,
because of this link between evolution and spontaneous generation
(at some period or other of the Earth's history) it appears that,
between 1860 and the end of the nineteenth century, the question
of the origin of life was rather complex.
In Germany, the materialist philosophers and the naturalist Ernst
Haeckel (1834-1919) were enthusiastic about Darwin's theory precisely
because one type of spontaneous generation (abiogenesis:
organic matter- in terms of belonging to living organisms- emerging
from inorganic matter) and the unification of the organic and
inorganic world into " one great fundamental conception "were
implied (Farley, 1977). Acceptance of abiogenesis became
naturally a cornerstone of materialist philosophy. In several
of his numerous writings, Haeckel took an active interest in the
topic of the origin of life (a primeval abiogenesis, in
a distant past). Haeckel's views on the origin of life mainly
came from his philosophy (monism) and his concept about the nature
of the simplest organisms, made of one single substance, named
protoplasm.
In this work, we propose to analyze more precisely the following
Haeckel's writings:
- Generelle Morphologie der Organismen (General Morphology
of Organisms) (1866)
- Natürliche Schöpfungsgeschichte (Natural History
of Creation) (1868)
- Die Welträthsel (The Riddles of the Universe) (1899)
- Die Lebenswunder (The Wonders of Life) (1904)
Reference:
- Farley, J. (1977) Spontaneous Generation Controversy from
Descartes to Oparin, The John Hopkins University Press, Baltimore
and London.
HORIZONTAL GENE TRANSFER IN THE EVOLUTION OF NITROGEN FIXATION
Janet Siefert, PhD
Rice University
Department of Statistics MS 138
PO Box 1892
Houston, Texas 77251-1892, USA
Office 713-348-3891
Fax 713-348-5476
Web site: http://www.stat.rice.edu/%7Emathbio/siefert.html
ABSTRACT
Whole genome sequences
for nearly twenty nitrogen-fixing prokaryotes are now available,
and we have analyzed each of these organisms for presence of one
or more nif (nitrogenase-gene encoding) operons and conserved
synteny. Additionally, we have used standard tools of sequence
analysis to evaluate the evolutionary history of every characterized
gene found in these nif operons and observe that the core genes
segregate phylogenetically into the known metal-binding classes
(iron-, vanadium-, or molybdenum-containing) of nitrogenase. We
have also used molecular phylogenetic techniques to analyze a
fourth group of yet-uncharacterized nitrogenase homologs, found
in archaea and in a limited number of phototrophic bacteria, that
appear to be ancestral to nitrogenase genes and to essential genetic
components of chlorophyll and bacteriochlorophyll biosynthesis
found in all known phototrophs. This fourth group of nitrogenase
homologs may function as an electron sink or possibly as a non-specific
detoxyase or reductase, and is likely a relic of some ancient
metabolic trait. Here we trace the early origins of nitrogenase
genes and the subsequent horizontal gene transfer events that
have resulted in the current distribution of prokaryotic nitrogen
fixation.
PALAEOBIOLOGY AND BIOSEDIMENTOLOGY OF THE STROMATOLITIC BUXA DOLOMITE, RANJIT WINDOW, SIKKIM, NE LESSER HIMALAYA, INDIA
Vinod Chandra Tewari *+
*Wadia Institute of Himalayan Geology, India
+The Abdus Salam ICTP, Italy
ABSTRACT
The Mesoproterozoic (Riphean)
stromatolite taxa are recorded from the Buxa Dolomite of the Ranjit
Window, Sikkim Lesser Himalaya India. The Riphean characteristic
taxa are Omachtenia, Colonnella columnaris, Kussiella kussiensis,
Conophyton, cylindricus, C. garganicum, Rahaella elongata Tewari,
Jacutophyton, Baicalia nova, Tungussia, Jurusania, Inzeria, Gymnosolen,
Minjaria, Stratifera and Gongylina. The Neoproterozoic-Terminal
Proterozoic (Vendian) stromatolite assemblage Paniscollenia,
Aldania, Tungussia, Linella, Colleniella, Linocollenia, Boxonia
linked Conophyton, Conistratifera, microstromatolites,
Stratifera, Irregularia, Nucleella, digitate stromatolites
and oncolites are well developed in the Buxa Dolomite, Ranjit
Window, Sikkim and its equivalents (Menga Limestone/Dedza Limestone/Chillipam
Limestone) in the adjoining Arunachal and Bhutan Lesser Himalaya.
The Mesoproterozoic to Terminal Proterozoic stromatolite diversification
has been recorded for the first time from the Buxa Dolomite of
the Sikkim Lesser Himalaya, India. The Palaeobiological and biosedimentological
significance of the stromatolites in the Buxa Dolomite has been
discussed.
CHEMICAL ABUNDANCES OF COMETARY METEOROIDS FROM METEOR SPECTROSCOPY: IMPLICATIONS TO THE EARTH ENRICHMENT
Josep Mª Trigo-Rodríguez 1, Jordi Llorca 2,3 and Joan Oró 4
1 Departament Ciències Experimentals, Universitat Jaume I.
2 Institut d'Estudis Espacials de Catalunya.
3 Departament Química Inorgànica, Universitat de Barcelona.
4 Fundació Joan Oró
ABSTRACT
The overabundance of comets
and chondritic bodies during the first stages of the primeval
Solar System produced a constant rain of material over our planet,
that could have direct implications to the origin of life in it
(Oró 1961). Nowadays we know that cometary matter in these
encounters suffers important alteration processes, the collision
of comet Shoemaker-Levy 9 with Jupiter provided us interesting
information about these violent processes. Probably the most important
source of Earth enrichment in volatile and organic compounds has
been therefore the constant entry of meteoroids from dense meteoroid
streams produced during hard fragmentation processes of their
parent bodies. At present, meteor storms are unusual but we believe
that fragmentation of comets and chondritic bodies produced dense
cometary streams during the first stages of the Solar System.
Important evidences have been obtained in the last decade studying
young protoplanetary disks. The observation of fast spectral changes
in their respective central stars has induced the development
of the so-called model of Falling Evaporating Bodies. Only a turbulent
stage where minor bodies are in constant fragmentation can be
able to explain some of the most important characteristics of
these young planetary systems.
Actually, meteor storms are usually produced by relatively long
period comets with high inclination orbits that produce violent
encounters of the meteoroids with the terrestrial atmosphere.
In the past, it is likely that meteor storms were produced from
orbits of low inclination and eccentricity, typical of ice and
chondritic minor bodies formed in the inner Solar System or perturbed
from outer regions due to the high matter density of bodies in
the young solar system. An important consequence is that the low
geocentric velocities allowed this matter to arrive to the Earth
without be completely degraded as occurs for high-velocity meteoroids.
We have analysed the temperature and volatilisation processes
from the study of spectra of fireballs produced by cometary meteoroids.
From these spectra we have derived the relative abundance of Na,
Mg, Ca, Si, Ti, Cr, Mn, Fe, Co and Ni in the parent meteoroids
by averaging the composition of the radiating gas along their
respective fireball paths produced during atmospheric entry. Data
reduction and relative chemical abundance were obtained following
Borovicka (1993) procedure. According to their orbital elements
these meteoroids were principally of cometary origin. We have
found important chemical differences between these cometary meteoroids
and the 1P/Halley dust analysed in situ by Giotto spacecraft (Jessberger
et al., 1988). Between these differences is important to note
that the deduced abundances of Si-Mg-Fe are in accordance to the
hierarchical dust accretion model developed by Rietmeijer (2002).
Moreover, other interesting result is the larger sodium abundance
compared to the expected for IDPs and chondritic meteorites. It
shows that 1P/Halley can not be used as type sample of cometary
dust, suggesting important differences between comets, as was
already pointed out by Greenberg (2000).
Finally, we focus our attention into the direct implications that
this cometary matter, reaching the atmosphere as meteoroid streams,
had in the primeval enrichment of exogenous material into the
Earth. Our results support the idea that there are, in fact, substantial
chemical differences among comets, probably related with the origin
of the different families as was proposed by Delsemme (2000).
REFERENCES
Borovicka J. (1993) "A fireball spectrum analysis", Astronomy & Astrophysics 279, 627-645.
Delsemme A.H. (2000) "1999 Kuiper Prize Lecture: Cometary Origin of the Biosphere", Icarus 146, 313-325.
Greenberg J.M. (2000) "From comets to meteors", Earth, Moon and Planets 82-83, 313-324.
Jessberger E.K., J. Kissel & J. Rahe (1988b) "The composition of comets", in Origin and Evolution of Planetary and Satellite atmospheres, 167-191, Univ. of Arizona Press, Tucson, EUA.
Kissel J. y F.R. Krueger (1987), "The organic component in dust from comet Halley as measured by the PUMA mass spectrometer on board Vega 1", Nature 326, 755-760.
Oró J. (1961) "Comets and the formation of biochemical compounds on the primitive Earth", Nature 190, 389-390.
Rietmeijer F. J. M., (2002) "The Earliest Chemical Dust Evolution in the Solar Nebula", Chemie der Erde 62-1, 1-45.
CONSERVED OLIGOPEPTIDES IN RIBULOSE-1,5-BISPHOSPHATE CARBOXYLASE LARGE CHAINS : AN EVOLUTIONARY PERSPECTIVE.
P.B.Vidyasagar 1, Pratip Shil 2 and Sarah Thomas 3
1 Professor, Biophysics Section, Department of Physics, University of Pune,
2 Research student, Biophysics Section, Department of Physics, University of Pune,
3 Lecturer, Bioinformatics Center, University of Pune.
Ribulose1,5-bisphosphate
carboxylase/Oxygenase (RuBisCO) is the largest multimeric protein
on the Earth and it catalyses the first step in the CO2 assimilation
in photosynthesis. Analysis of RuBisCO large chain sequences from
different species spanning from lower to higher plants (viz. Archea,
Bacteria, Alga and Higher plants) have been carried out using
Bioinformatics techniques viz multiple sequence alignment (CLUSTALW)
and secondary structure prediction tools. Secondary structure
prediction from the Predict Protein package show the occurrence
of conserved oligo-peptides in different secondary structures
in different groups of sequences. The study also reveals the occurrence
of conserved oligopeptides specially '-KDDEN-" and '-SGGIH-'
in almost all the sequences. The advanced analysis and comparison
of these sequences with those from tobacco and spinach (with known
3D structures) reveal the existence of close interaction of these
oligopeptides and other conserved amino acids. The conservation
of the oligopeptides indicates their probable decisive role in
the active site configuration.
The present study reveals that in the evolutionary pathway the
RuBisCO large chain sequences have stabilized in higher plants
after initial variations in the lower plants.
The present study reveals some of the aspects related to the structural
changes during evolution of plants.
INTERSTELLAR DUST AS A TRACER OF ENVIRONMENTS FAVOURABLE TO PLANET FORMATION: EVIDENCE FOR THE EXISTENCE OF A METALLICITY THRESHOLD.
Giovanni Vladilo
Osservatorio Astronomico di Trieste
Istituto Nazionale di Astrofisica
ABSTRACT:
Dust occupies a central
position along the astrophysical route that, starting from the
stellar production of chemical elements, leads to the formation
of molecules and pre-biotic material in the interstellar space
and to the building up of proto-planetary disks around stars.
Tracing the formation and evolution of dust in galaxies is therefore
an important step in the quest for environments capable of developing
life. I report here the results of a study of the dust content
in primordial galaxies observed by means of absorption spectroscopy
of background quasars. This study provides evidence for the early
build-up of dust, consequent to the stellar production of metals,
in primordial galaxies seen between ~8 and ~12 billion years before
the present. The analysis of the data indicates a severe deficiency
of the dust-to-metal ratio in the very early stages of metal production.
However, when the metallicity level increases above ~10% of the
solar value, the dust content approaches the values typical of
the nearby interstellar medium, where planets and life managed
to emerge. This suggests that galaxies with metallicities >10%
of the solar one may have a dust content sufficient to develop
pre-biotic material and planets.
THE ELECTROCHEMICAL CO2 REDUCTION TO FORMATE IN HYDROTHERMAL SULFIDE ORE DEPOSIT AS A NOVEL ABIOTIC SOURCE OF ORGANIC MATTER (A HYPOTHESIS AND THE LABORATORY MODEL).
M. G. Vladimirov1 *, Yu. F. Ryzhkov 2, V. A. Alekseev 2, V. A. Bogdanovskaya 3,
V. A. Otroshchenko 1, and M. S. Kritsky 11 A.N.Bach Institute of Biochemistry, Russian Academy of Sciences (RAS), Moscow; 2 The Russian Federation State Research Center "Troitsk Institute for Innovation and Fusion Research", Troitsk, Moscow Region; 3A.N.Frumkin Institute of Electrochemistry, RAS, Moscow; Russia.
*<mgv@inbi.ras.ru>
ABSTRACT
A wide spectrum of electrode
potentials of minerals that compose sulfide ores to enable the
latter, when in contact with hydrothermal solutions, to form galvanic
circuits with cathode potentials up to several volts sufficient
for electrochemical reduction of CO2.
Before our study pyrite was not investigated as cathode material,
hence the combination of semiconductor properties with the low
adsorption activity and a presence of traces of transient metals
pointed to this mineral as to a probably good cathode material.
The experiments performed demonstrated the increase of cathode
current on rotating pyrite electrode in a range of potentials
more negative than 800 mV in presence of CO2 and revealed
the dependence of this current from the CO2 diffusion rate, temperature
and ionic composition of aqueous phase.
The numerous studies of the CO2 reduction on cathode materials
other than pyrite have formed the notion on the chemistry of this
process. According to it, the reduction process involves an electron
tunneling from cathode surface to a CO2 molecule with the production
of an active particle, the radical-ion __2- and the further reduction
of this radical to formate (and, under certain conditions, to
more complex molecules).
To verify our hypothesis on the CO2 electrochemical reduction
on pyrite in modeling experiment, the installation was constructed
which consisted of a fluorocarbon electrochemical cell with two
separated electrode chambers installed into a high-pressure autoclave
permitting a continuous CO2 flow (50 atm, 10 ml_min1) through
cathode chamber. The cathode (7 cm2) was manufactured of a hydrothermal
pyrite monocrystal and anode was a platinum plate. The cell's
electrodes were connected with a programmed potentiostate and
the recording unit. The cell was filled with 0.1 M KHCO3 electrolyte,
and the CO2-saturated solution was subjected to electrolysis (24
hrs, room temperature).
Starting with a cathode potential about 800 mV (vs. saturated
Ag|AgCl r.e.), the accumulation of formate in electrolyte was
observed by a color reaction with chromotropic acid. No formate
production was registered under normal atmospheric pressure and
in the absence of imposed cathode potential. Neither in experiments,
nor in control formaldehyde was found. The yield of formate demonstrated
an exponential growth as a function of cathode potential value
at least up to 1200 mV. The maximal faradaic efficiency of formate
synthesis (0.12%) was observed at 1000 mV. The results point to
geoelectrochemical systems capable to the CO2 cathode reduction
as a novel source of abiogenic organics.