Differences in circadian rhythms of resistance to -rays and heavy-ion beam in

Bolige, A.*; Sakashita, Tetsuya; Kakizaki, Takehiko*; Funayama, Tomoo; Hamada, Nobuyuki*; Wada, Seiichi*; Kobayashi, Yasuhiko; Goto, Ken*

We report here how these rhythms are related to each other. First, irradiation temperatures influenced neither survival after exposure to UV, rays, nor C ions, whereas the incubation at high temperatures (25 C) after irradiation considerably lowered the survival particularly after irradiation, but not after UV irradiation at all. Secondly, although the antioxidants carotene and dimethylsulfoxide (DMSO) increased the survival of the alga at the least resistant phase after UV C and UV B irradiation, respectively, to the level of the most resistant alga, none of these were not so effective for or C ion irradiation. Finally, FITC dextran was incorporated into the alga only after C ion irradiation but not irradiation, suggesting that C ion may perforate cell membranes to kill the alga.