[Effect of local UV irradiation of the generative nuclei of Paramecium caudatum on the sexual functions of the cells].

A study has been made of the functional pattern of the micronucleus (Mi) during the sexual process in ciliates Paramecium caudatum which are descendants of those individuals whose Mi was locally irradiated with UV in dose of 3060 erg/mm2. It was demonstrated that these descendants (cells of UV-clones) were able to enter into the sexual process whatever morphological type of their Mi might be. In 4 of 14 tested clones, the initial mating type got changed for the opposite one, which may be associated with the Mi genome alteration following UV irradiation. The nuclear reorganization during the sexual process was studied in three UV irradiated clones. The local UV irradiated of the Mi is followed by the number of abnormalities in the derivates of Mi during the metagamic phase of the sexual process in clones whose Mi underwent serious changes. Exconjugants obtained from UV-clones with such changes in Mi and normal test-clones demonstrated a lower viability.