| Abstract: | The morphology of Paramecium bursaria cells, both originally possessing 2 micronuclei (MI), or one MI, has been studied after a local UV irradiation of the germ nuclei. Elimination of one of the MI in bimicronuclear cells usually did not lead to general cytological damage in the UV progeny. Irradiation of MI in the unimicronuclear cells resulted in the following: producing of amicronuclear (MI-) UV subclones, 86% of which appeared to be non-viable. The MI- cells are characterized by the appearance of somatic deciliation and the loss of mobility, disorganization structures of the oral apparatus, the feeding process and the cell division. It is remarkable that the macronucleus (MA) of cells from those cultures displays fragmentation and aberrant division. The structure of MA was changed. Dimensions of the MI- ciliates decreased (by 1.7--1.8 times in average); sometimes these cells had 3--5 contractile vacuoles with one pore. These data suggest that the MI has important role during the vegetative phase of the cell life. Possible asexual cellular functions of the MI and the role of the break of nuclear interactions in the appearance of the morphological damage are discussed. |
