The possible role of volcanic aquifers in prebiologic genesis of organic compounds and RNA.
In a volcanic aquifer, a wide range of physical and chemical conditions are not merely possible, but to be expected: relatively oxidizing and reducing environments both are present; hot and moderate temperatures can be expected; distillation and reflux conditions are probable to allow concentration of reactants, stimulation of reaction and fractionation of isotopes; apatite, hydroxides, clays and sulfide minerals are present to act as chromatographic media for separating compounds, to serve as catalytic surfaces and to provide potential energy sources; supersaturated precipitation of optically active crystals is reasonable, allowing for chromatographic separation of racemic mixtures by the resulting fixed chiral phase; and saturated and unsaturated conditions both are present for promotion of constructive reactions and inhibiting destructive hydrolysis reactions. Because the multitude of physical-chemical environments makes the setting robust with respect to circumventing commonly identified problems in origin-of-life theories, even if objections to details proposed herein are identified, the setting is favorable for devising alternatives. This paper describes a theory for the genesis of organic compounds, including RNA, in the mixing zone of juvenile and meteoric waters above a leaky semi-confined aquifer. Starting with basic reactants for best-guess conditions on Archean Earth, parallel sequences of specific reactions are proposed that culminate with RNA oligonucleotides, key molecules in contemporary life. All proposed reactions, or close analogues, are experimentally confirmed and all are set in plausible Archean conditions. Calculations indicate that the proposed reactions would yield C isotopic compositions that are consistent with observed biologic C.
Washington
J
J
USEPA, National Exposure Research Laboratory, Athens, GA 30605-2700, USA. washington.john@epa.gov
D001105:Archaea; D001272:Atmosphere; D002241:Carbohydrates / Q000096:biosynthesis; D002625:Chemistry, Organic; D008962:Models, Theoretical; D055601:Organic Chemistry Phenomena; D000069497:Origin of Life; D011687:Purines / Q000096:biosynthesis; D011743:Pyrimidines / Q000096:biosynthesis; D012313:RNA; D014881:Water Supply
D002241:Carbohydrates; D011687:Purines; D011743:Pyrimidines; D012313:RNA; C010963:formose sugars