(Bertrand et al. 2008). We present the different preparation steps of samples for the EXPOSE missions and the first analytical results of the ground experiments. Barbier. B., Chabin, A., Chaput, D., and Brack, A. (1998). Photochemical processing of amino acids in Earth orbit. Planet. Space Sci., 46: 391–398. Barbier, B., Henin, O., Boillot, F., Chabin, A., Chaput, D., and Brack, A. (2002) Exposure of amino acids and derivatives in the Earth orbit. Planet. Space Sci., 50:353–359. Bertrand,

M., Chabin, A., Brack and Westall, F. (2008) Separation of amino acid enantiomers VIA chiral derivatization and non-chiral gas chromatography. Journal of Chromatography, A 1180: 131–137. Boillot, F., Chabin, A., Buré, C., Venet, M., Belsky, SP600125 cell line A., Bertrand-Urbaniak, M., Delmas, A., Brack, A., and Barbier, B. (2002) The Perseus Exobiology Mission on MIR: Behaviour of amino acids and peptides in Earth orbit. Origins of Life and Evolution of the Biosphere, 32: 359–385. Cottin, GW-572016 mouse H., Coll, P., Coscia, D., Fray,; N., Guan, Y.Y., Macari, F., Raulin, F., Rivron, C., Stalport, F., Szopa, C., Chaput,

D., Viso, M., Bertrand, M., Chabin, A., Thirkell, L., Westall, F., and Brack A, (in press) Heterogenous solid/gas chemistry of organic compounds related to comets, meteorites, Titan, and Mars: Laboratory and in lower Earth orbit experiments. To appear in the Adv. Space Res. E-mail: annie.​chabin@cnrs-orleans.​fr Experimental Fossilization Induced in Modern Microbial Mats Elizabeth Chacón B1, Mariajose Peña1, Felipe Torres de la Cruz1, A. Negrón-Mendoza2 1Facultad de Ciencias de la Tierra, UANL; 2Instituto de Ciencias Nucleares, UNAM Microbial

fossilization is a key geobiological process to understand the sedimentary record and to design new strategies in the extraterrestrial life search. Although several analysis have been proposed to identify and describe in situ fossilization of different types of microorganisms (Jones et al 1999; Westfall et al 2001), the many factors involved in this complex process still wait for elucidation. By far, the most common microbial GSK126 price fossil preservation process is by silicification, as learn more the numerous ancient cyanobacterial microfossils from Precambrian strata testify. Other less common fossilization processes include phosphate and carbonate replacement. Among the main factors inducing fossilization are a rapid lithification, a rapid burial after cell death, cooling and evaporation of supersaturated mineral waters (mainly in the case of silicification) as well as the biological mediation on the nucleation of specific minerals input from the environment (Konhauser et al 2001). Previous works have suggested that biological organic matter mediates biomineralization; in contrast, other recent observations indicate that mineralization of cyanobacteria is an inorganically controlled process, induced by rapid cooling and evaporation of the spring waters, occurring independent of microorganisms.