Conclusions

Assuming that life originated on Earth, it is highly unlikely that the precursors for this event were racemic or that homochirality emerged by random event(s) during the earliest stages of life's origin 53,54 . There have been no successful experiments for the abiotic synthesis of non-racemic amino acids under early Earth conditions, although the recent report by Hazen et al. 55 on selective adsorption of D- an L-enantiomers on mirror-related crystal growth surfaces of calcite certainly merits...

List of Student Participants

NEMLIHER Yuri, 3. SIK Andreas, 4. ARMSTRONG John, 5. KOCZOR Ronald, 6. ENGEL Michael, 7. SERUSHKIN Yuri, 8. TOPORSKI Jan, 9. BLASQUEZ Jesus, 10. MCKAY David, II. ZAVARZIN Georgiu, 12. QIQEK Caner, 13. KAYE Jonathan, 14. SIMAKOV Michael, 15. RETTEBERG Petra, 16. MARKOPOULOS Theodoras, 17. PERRY Randall, 18. PEREZ-MERCADER Juan, 19. ROZANOV Alexei, 20. GUTIERREZ Jordi, 21. OMAROV Bigaliev, 22. KOLB Vera, 23. HUBER Julie, 24. TURNBULL Margaret, 25. HOOVER Richard, 26....

References

Alternative bases in the RNA world the prebiotic synthesis of urazole and its ribosides. J. Mol. Evol. 1994 38 549-57. 2 Robinson PD, Meyers CY, Kolb VM, Colloton PA. First example of a crystalline urazole nucleoside. (1R, Acta Cryst. 1996 C52 1215-8. 3 Kolb VM, Colloton PA, Robinson PD, Lutfi HG, Meyers CY. (1R, Acta Cryst. 1996 C52 1781-4. 4 Kolb VM, Colloton PA. On the mechanism of formation of urazole nucleosides reaction of open-chain and cyclic analogs...

Results

MDGS contain higher TOC (0.36-0.77 0.57 0.09 n 16) than the supporting matrix (0.29-0.51 0.40 0.06 n 15) and SRP (0.16-0.43 0.32 0.09 n 10) (Fig. 4 (c)). In MDGS, CaCOs is the most variable parameter (0.09-54.4 0.32 0.09 ) (Fig. 4 (a)) biogenic opal is constant throughout the matrix (12.91 16.43 15.1 1.1 n 8) (Fig. 4(b) Figure 4. XY diagrams showing (a) TOC versus Opal, (b) CaCO3 versus Opal, (c) TOC versus CaCO3, (d) TOC matrix versus TOC component. See Section 4 for explanation. Figure 4. XY...

Bioapatite Properties as Biosignature

Considering the astrobiological definition of biosignature as being any measurable property of a planetary object, its atmosphere, oceans, geologic formations, or sample that suggests that life is or was present (McKay, from lecture on the Astrobiology Conference, Chania 2002), the complex mineral properties are well suitable as being detected as a biosignature. The properties of ferric minerals have been considered as biosignatures of life activity of magnetotactic bacteria 13,14 . In this...

Bioindicators and Biomarkers in Rocks and Meteorites

The heated debate that followed the reported detection of biomarkers and possible microfossils in ALH84001 was reminiscent of the debate after the 1961 detection by Claus and Nagy 37,38 of organic biomarkers and possible microfossils in carbonaceous meteorites. Critics advanced a wide array of objections to the evidence for biomarkers and microfossils and the proponents ultimately retreated. Studies 39 established that forms such as Clause and Nagy had called organized elements are readily...

Tikhovs Astrobotany as a Prelude to Modern Astrobiology

TASHENOV Astrophysical Institute, Almaty, 480020 Kazakhstan Abstract. Development of astrobotanical research by G.A. Tikhov in the Kazakh Academy of Sciences is considered seminal to today's astrobiology. In 1949, in Kazakhstan, Gavriil A. Tikhov published a book entitled Astrobotany 1 . Later in 1953, the author published a paper, The Possibility of Life in the Other Worlds 2 and a book Astrobiology 3 . These works of Tikhov were the results of research activity by...

The Murchison Meteorite

On the morning of September 28, 1969, a bright orange fireball with a silvery rim and a dull orange conical tail illuminated the sky over Victoria, Australia. Hundreds of black stones fell in a 1-mi wide and 10-mi long scatter ellipse at around the town of Murchison (36 37' S, 145 14' E). In December 2000, Hoover visited Murchison, Australia and discussed the event with several individuals who had witnessed the fireball and collected stones soon after their fall. Several reported hearing a...

Bacterial Paleontology

Paleontological Institute RAS, Profsoyuznaya 123, Moscow, 117997, Russia Abstract. Bacterial paleontology is rather young branch of paleontological studies. Bacteria and microbes in general could be perfectly preserved as fossils. The major part of the sedimentary rocks formed in the photic zone of epicontinental basins of the past originated under the influence of microorganisms. Studies have increased the number of minerals known to be formed with the participation of microorganisms to >...

Microfossils of Cyanobacteria and Acritarchs in Carbonaceous Meteorites

The search for microfossils in freshly fractured samples of carbonaceous meteorites has been carried out at MSFC using the Hitachi FESEM and the ElectroScan Corp. ESEM. Numerous samples from museums and meteorites collected during the Antarctica 2000 Expedition were studied. Mautner et al. 120 have shown that meteorite organic matter is a suitable nutrient for organotrophs and the meteorite fusion crust and old fractures are very susceptible to contamination by recent fungi, actinomycetes, and...

Pyrite

Pyrite is spread in different layers of rocks under investigation. The pyrite exists both in framboid shape that is typical for thermophile cyanobacterial mats 6 . The presence of pyrite automatically suggests the process of sulfate reduction that is produced by SRB. These bacteria use elemental sulfur and sulfates, which are formed as a result of photosynthesis, and trophically SRB are closely connected with the purple sulfur bacteria. In the presence of sulfates, SRB produce H2S that in turn...

Biochemical Markers in Rock Coatings

KOLBb 2Department of Earth and Space Science University of Washington, Seattle WA 98195-1310, USA bDepartment of Chemistry University of Wisconsin-Parkside, Kenosha, WI53141-2000, USA Abstract. Rock coatings are ubiquitous in arid regions of the world. Amino acids in desert varnish coatings have been measured, and other organic compounds have been considered as chemical biosignatures in coatings. Understanding the mechanisms of formation or rock coatings and...

Thermophiles and Psychrophiles as Analogs for Life on Mars and Europa

It is now known that microbial extremophiles thrive in a wide range of environments on Earth. The discovery of these hardy life forms greatly enhances the possibility that viable microbiota might have existed in the ancient oceans or rivers of Mars or the oceans that exist today beneath the ice crust of Europa. Psychrophiles and thermophiles might also survive today, living within the hydrothermal vents, fumaroles, and deep crustal rocks of Mars. Psychrophiles may live or be cryopreserved in...

Statement of Problem

For any forthcoming fossil hunt on Mars, we would be well advised to make full use of the information stored in the micropaleontological and biogeochemical inventories of the oldest (Archean) terrestrial sediments, that is, those covering the time window of 3.3-3.8 Ga. These rocks are roughly coeval with the sedimentary formations deposited in the water-rich environment of juvenile Mars as documented by the water-carved surface morphology that is exposed on large parts of the outer face. If it...

Shales the Cambrian of the Siberian Platform and the Permian of the Barents

Framboidal structures are common in Earth rocks and meteorites carbonaceous chondrites. There is little doubt that the origin of fTamboids in astromaterial is the same as in Earth rocks. But up to now, there is still not a common opinion concerning the origin of framboids, i.e. whether they are biogenic or not, so it is very important to solve the problem of the nature of framboids in Earth rocks. Framboids are spherical aggregates of microcrystals. They are characterized by a complicated,...

Reactions of Urazole and its Analogs with Sugars and Metals under Prebiotic Conditions

COLLOTON and Kevin J. RAPP Department of Chemistry, University of Wisconsin-Parkside Kenosha, Wisconsin 53141-2000, USA Abstract. This work reports the selectivity of urazole, a prebiotic mimic of uracil, in its reactions with sugars. This selectivity is important in prebiotic synthesis of nu-cleosides. Urazole makes metal complexes. Thus, it may exist on meteorites as such. Some physical properties of urazole-metal complexes that are relevant for their recovery from...

Bacterial Endospores as Test Organisms

Many microorganisms found in terrestrial soils are capable of forming spores to cope with unfavorable environmental conditions particularly, bacterial endospores withstand extremely hostile conditions in the dormant state. They exhibit a high degree of resistance to inactivation by various physical and chemical stresses, such as desiccation, extreme temperatures, UV and ionizing radiation, and various aggressive chemical insults including alcohol, acid and basic solutions, and oxidizing agents....