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RHO-GEF GENE EXPRESSION RESPONDS TO GRAVITY VECTOR CHANGING.  M. Seki¹, A. Higashibata¹, M. Imamizo-Sato¹, and N. Ishioka¹.  ¹Space Development Division, Advanced Engineering Services Co., Ltd, ²Space Utilization Research Center, Space Utilization System, National Space Development Agency of Japan, Tsukuba, Ibaraki, JAPAN.

   In the last meeting, we reported that vector-averaged gravity environment　had　morphologically affected　endothelial cells, including cytoskeletal formations.  The results indicated that Rho was observed just around a nucleus under vector-averaged gravity condition, while Rho was widely distributed in cells cultured under static condition. 　We supposed that Rho expression was affected by gravity vector variation. 

In this study, the variation of mRNA expression level caused by vector-averaged gravity condition was investigated using a finger printing method.  Several cDNA fragments showed different expression level in differential display images.  Some fragments were determined the partial nucleic acid sequences.  A partial fragment of RhoGEF was a typical fragments that was depressed the expression level by gravity vector changing.  These results supported our morphological data and indicated that Rho activation might respond to gravity vector changing.  We are verifying the full cDNA sequence of RhoGEF and are studying gene expression variation of Rho related molecules by gravity vector changing.