Heat-shock induction of radiation resistance in primordial germ cells of the fish Oryzias latipes.

The effects of heat on the radiosensitivity of primordial germ cells at the quiescent stage in the fish Oryzias latipes were studied. The results show: (1) heat preceding but not following irradiation induced radioresistance which was reflected by improved survival; (2) its magnitude was a function of the heating time before irradiation; (3) improved germ-cell survival did not change with time for up to at least 4 hours after heat treatment at 41 degrees C for 30 min; (4) this resistance was more prominently expressed in the subsequent course of proliferation of female germ cells than in the non-proliferating male germ cells. In conclusion, heat induced radiation resistance in primordial germ cells of the female at the quiescent stage; this probably allows the cells subsequently to escape reproductive death.