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Science Frontiers ONLINE No. 47: Sep-Oct 1986 |
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Earth's womb
Three recent items indicate that scientists are now recognizing how the earth's crust is tailor-made for biochemical reactions of great variety and complexity.
First, E.G. Nisbet explains how subsurface hydrothermal systems are ideal places to make biochemical products, particularly in the light of the discovery that RNA molecules can extrude introns and then behave like enzymes.
"The most likely site for the inorgan ic construction or an RNA chain, which would have occurred in the Archaean, is in a hydrothermal system. Only in such a setting would the necessary basic components (CH4 , NH3 , and phosphates) be freely available. Suitable pH (fluctuating around 8) and temperatures around 40�C are characteristic of hydrothermal systems on land. Furthermore, altered lavas in the zeolite metamorphic facies, which are rich in zeolites, clays and heavy metal sulphides, would provide catalytic surfaces, pores and molecular sieves in which RNA molecules could be assembled and contained. If the RNA could then replicate with the aid of ribozymes and without proteins, the chance of creating life becomes not impossible but merely wildly unlikely."
The article concludes with a statement that self-replicating molecules synthesized in hydrothermal systems would be pre-adapted to "life" in the open ocean if they "learned" to surround themselves with bags of lipids. (Bag of lipids = a membrane.)
(Nisbet, E.G.; "RNA and Hot-Water Springs," Nature, 322:206, 1986.)
It just so happens that D.W. Deamer, University of California, Davis, has now found that the 4.5-billion-year-old Murchison meteorite from Australia contains lipid-like organic chemicals that can self-assemble into membrane-like films. His paper was presented before the International Society for the Study of Origins of Life.
(Raloff, J.; "Clues to Life's Cellular Origins," Science News, 130:71, 1986.)
Comment. Strange that the earth should be "tailor-made" for biochemical operations and that outer space teems with meteorites transporting other ingredients of life-synthesis.
That the earth's crust and deep soil are conducive to life is apparent in recent work done sponsored by DuPont and the Department of Energy. This effort has found that life is abundant at least 850 feet below the surface -- a realm hardly suspected to harbor life.
"'There is life down there, and it is very diverse,' says Carl Fliermans of Dupont's Savannah River Laboratory in Aiken, S.C. The numbers are high enough to affect the chemistry of the environment: Some of the samples contained as many as 10 million organisms per gram of soil. But even more surprising than the high concentrations is the diversity of the microorganisms, according to David Balkwill of Florida State University in Tallahassee. Many varieties of bacteria and fungi have been seen, and there have been indications of amoeba. And the diversity -- which doesn't appear to decrease with depth -- may force a reappraisal of the environment that lies between soil and bedrock."
(Anonymous; "The Bugs beneath Us," Science News, 130:58, 1986.)
Under the GEOLOGY heading in this issue, the subject of abiotic production of petroleum is explored. Where could abiotic petroleum be synthesized? Below the surface, in hydrothermal systems.