[The effect of gamma irradiation on the strain W of Tetrahymena pyriformis].

It the present study the effects of gamma-radiation at doses of 102.1 Gy-1,633.4 Gy were investigated as exerted on the protozoan Tetrahymena pyriformis W strain. An investigation of lethality showed that all irradiated cells survived after the doses of 102.1 Gy and 204.2 Gy, When the doses of 408.4 and 816.7 Gy were applied, 60.6% and 8.8%, resp., of irradiated cells survived. Not a cell survived the dose of 1,633.4 Gy. The effects of gamma-radiation on the generation time of Tetrahymena pyriformis are shown in Tab. II. A markedly longer generation time than in the control was observed if the radiation doses made 408.4 and 816.7 Gy. There were no significant changes there when the effects of irradiated incubation media on the growth of nonirradiated cells of the W strain of Tetrahymena pyriformis were investigated. The results confirmed the relatively high radioresistance of the Tetrahymena protozoon with respect to gamma-radiation; this protozoan is a suitable biological model for a study of the effects of various kinds of ionizing radiation at the level of both cell and population.