CELLULAR CONTENT OF P53 PROTEIN IN RAT SKIN AFTER EXPOSURE TO THE SPACE ENVIRONMENT

The effects of stress in space, microgravity and space radiation, on l iving organisms are still unknown. We have examined the cellular conte nt of p53 protein, a tumor-suppressor gene product, in skin from rats by the Western blot method using a blotting-amplification system. Thre e groups of rats were used. The first group was kept on Earth normally and showed hardly any detectable p53 protein. The second group made a 14-day flight into space on the second Spacelab Life Sciences-2 missi on (F). The last group was subjected to the same kinds of stress as th e rats in the second group except for spaceflight (SC). The F and the SC rats were killed on day zero (F-O and SC-O groups) and day nine (F- 9 and SC-9 groups) after return. F-O rats showed marked accumulation o f p53 protein, whereas SC-O rats showed a slight decrease. F-9 and SC- 9 rats showed almost the same amount of p53 protein, but F-9 rats show ed a slightly higher expression. From these results, it is suggested t hat the accumulation of cellular p53 protein is induced in rat skin ce lls by exposure to the space environment.