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Heat Shock Protein Expression in Response of Pea Seedlings to Altered Gravity.  L.Ye. Kozeko, A.S. Talalaev, E.L. Kordyum. Dept. of Cell Biology and Anatomy, Institute of Botany, National Academy of Sciences of Ukraine.

   Both hypergravity and microgravity as environmental changes during the space flight cause alterations in gene expression and protein patterns of organisms. Heat shock proteins (Hsps) are involved into plant responses to different environmental changes fulfilling a variety of molecular chaperone functions: protein folding and translocation, stabilizing of unfolded proteins etc. We have previously reported that simulated microgravity (clinorotation) results in increasing of the Hsps level in time-dependent way. Therefore, the next step in our investigations was to evaluate the influence of hypergravity on Hsps expression. 5-day old etiolated pea seedlings were exposed to centrifuge-induced hypergravity (from 3g to 14g) for 15 min and 1 h as well as recovery periods after hypergravity conditions up to 24 h. Hsp70, Hsp90 and small heat shock proteins sHsp18.1 and sHsp17.1 expression was analyzed using RT-PCR and Western analysis. Changes in the Hsps expression after exposures to hypergravity were more significant comparatively to the microgravity effect and depended on the g-number and time of exposure, but the changes were specific for each Hsp. The obtained data suggest that the changes in Hsps level can reflect an intensity of adaptive processes to the changes in gravitational forces.

(Supported by NSAU: 1-23/05.)