Pools of water in anhydrobiotic organisms: A thermally stimulated depolarization current study.
The ability to survive the removal of water in anhydrous biosystems is especially remarkable as a departure from the manifold structural and functional dependences on the presence of H(2)O molecules. Identifiable pools of water present in dry soybean axes were investigated by means of the thermally stimulated depolarization current method. Samples were examined in the temperature range 100-340 K and over water contents (h, in gram H(2)O per gram sample dry weight) ranging from h = 0.05 to 0.30 g/g. Three water-dependent relaxation mechanisms were detected; one attributed to dipolar reorientation of H(2)O molecules hydrogen-bonded to other water molecules, one to reorientation of CH(2)OH groups, and one to a glass transition in sugar-water domains. These glassy domains can protect intracellular components against destruction in the dehydrated state. Interestingly, protecting glassy domains were not found in dehydration intolerant seeds, supporting the hypothesis that the ability to withstand dehydration is associated with intracellular glass formation. A model for the state of cell water at interfaces is proposed.
Bruni
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Section of Plant Biology, Cornell University, Ithaca, New York 14853 USA.
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