[Extranuclear sites of action in UV-irradiated Fumaria hygrometrica (author's transl)].

Isolated filaments of Funaria hygrometrica have been treated by whole-cell UV irradiation (265 nm) as well as by microirradiation of the nucleus. 4 to 5 hrs thereafter the cells showed a depression in length growth. The intensity of this depression remarkably depends on the absorbed energy only. It does not matter whether the nucleus and its environcence or the whole cell are irradiated. The effect does not show photoreactivation and is rather independent from the cell cycle and hence from the DNA content of the nucleus. After X-irradiation supplying the same amount of absorbed energy no damage is detectable. The authors conclude that the site of the primary radiation effect is situated mainly outside the nucleus and that it may be a damage of the m-RNA, r-RNA or of membranes.