Effects of autogamy in Paramecium tetraurelia on catalase activity and on radiosensitivity to natural ionizing radiations.

Catalase activity of Paramecium tetraurelia decreased during autogamy and recovered to normal 5 days later. Autogamy also caused changes in the ciliate's sensitivity to natural ionizing radiations--the decrease in cell growth rate previously described in shielded cultures did not occur when autogamous cells were used. Maximum effect of shielding was observed in 11-day-old postautogamous cells. The role of the catalase in the mechanism of natural iradiation effect is discussed.