Abstract
We recently reported our findings in regard to the physiological function that modulates cell mutability under 1 G conditions, and in this study we investigated the mutation-modulating activity in human and cultured cells after gravity-changing conditions produced by parabolic flight or by free-fall. The mutation-modulating activity was detected in serum from volunteers who underwent parabolic flight. Cultured human cells also showed the modulation-associated alteration, such as the induction of protease activity and gene expression, when they were exposed to gravity-changing stress produced by parabolic flight and by free fall. Thus, we hypothesized that the mutation-modulating function may proceed as follows; when humans are exposed to gravity-changing stress, serum factors are first released into blood, proteases in cells are activated by the factors, expression levels of genes are altered, and finally cellular mutability is regulated.
