ASGSB 1999 Annual Meeting Abstracts

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IN SEARCH OF THE PHYSICAL AND CHEMICAL LIMITS FOR LIFE.  J.D. Trent.  Exobiology Branch, NASA Ames Research Center,  Moffett Field, CA 

   As we consider the possibilities of finding life on other planets it behooves us to evaluate what we know about the limits for life on planet Earth.  In our continued exploration of the Earth we are finding microbes in a variety of unexpected habitats.  For example, in geothermal hot springs, we have discovered organisms thriving at temperatures near the boiling point of water and at pH values down to 0.5.  In the deepest parts of the oceans we have discovered organisms growing optimally at pressures >1000 bars that die at pressures below 500 bars. At the poles we have discovered growing below the freezing point of water that die at temperatures above 10EC.  All of these organisms are living proof that the biochemical ‘machinery’ of life can be adapted to conditions that from our anthropocentric perspective appear to be extreme.

   By studying the molecular adaptations of extremophiles we begin to identify the critical cellular components that expand the envelope for life.  As an example, I will discuss what we have learned about the role of proteins, known as heat shock proteins, in pushing the upper temperature limit of life and how our studies helped to unravel the function of these proteins in general.

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