Title:Geochemical Selection and Accumulation of Prebiotic Reaction Products:Studies on plausible Geological Settings for Chemical Evolution

Speaker: Dr. Yayoi Hongo (ELSI)

Abstract:
I propose to study how environmental fluid flows combined with wet-dry cycle in porous media may have helped separate and accumulate particular compounds from complex mixture of prebiotic reaction products, which may also have helped jumpstart the origin of life. Formations of biomolecules, peptides and nucleic acids, require the specific condensation of respective building blocks, amino acids or nucleotides, to be of fairly high concentration and purity. However due to the poor reaction yields and diverse byproducts formations in prebiotic syntheses, it might be difficult to obtain these degrees of concentration and homogeneity in a primitive environment without some geochemical mechanisms. Geochemical separation and accumulation could help to enrich specific class of organic molecules and point towards the most favorable geochemical settings as steps toward LUCA. I would like to investigate geochromatography under various temperature regimes. Novel custom apparatuses will be constructed to investigate these phenomena. A general outline of the approach is as follows: 1) porous minerals which are unmodified or modified with tar-like organics (e.g., laboratory-generated thermolysis products of glycine, tholins or HCN polymer) will be poured into gravity columns consisting of separable glass segments, 2) elution under constant or changing temperature gradients to examine the potential contributions of thermally driven fluid-flow in confined spaces ("thermophoresis") and eutectic freezing, 3) evaluation of molecular separation and accumulation efficiencies with measuring organics in eluent fractions, as well as by using direct-ionization imaging mass spectrometry to visualize molecular distributions on the solid surfaces after sample loading and elution. I will present the rationale, approach and potential implications of these studies.