[The effect of ultraviolet microbeam irradiation of the centrosome on cellular behavior. IV. Synthetic activity, cell spreading and growth with an inactivated centrosome].

One of the spindle poles of mitotic PK cells was irradiated with UV microbeam at anaphase. After irradiation, cell division completed with a minor delay and two daughter cells were spreading synchronously. Later on, cells with irradiated centrosomes slightly shrunk, while their sister cells enlarged normally. Sister cells entered S-phase, some of them undergoing mitosis. In the cells with irradiated centrosomes the formation of nucleoli was disturbed and numerous primary nucleoli remained for 50 h (the maximum time of observation). RNA synthesis in the cells with irradiated centrosomes was twice less than in the sister cells, with ribosomal RNA synthesis being suppressed predominantly. Cells with irradiated centrosomes did not enter S-phase for as long as 24 h. The same irradiation of a portion of cytoplasm outside the spindle performed during anaphase did not change the pattern behaviour in daughter cell. In is concluded that the centrosome regulates progression throughout the cell cycle, and that centrosome irradiation induces specific and irreversible damage of interphase cells.