[Behavior of the mitotic apparatus after ultraviolet microirradiation of the spindle pole]

UV-microirradiation of the centrosome (spindle pole) alters behaviour of mitotic cell. Cell reaction strongly depends on the stage of mitosis when irradiation has been made. Irradiation of one pole at metaphase blocked cell in c-mitosis for several hours. The same or even more strong irradiation of the pole at anaphase slightly postponed cytokinesis, but didn't prevent chromosome separation and normal exit of cell into interphase. Irradiation at metaphase resulted in immediate shift of chromosomes towards the nonirradiated pole. Afterwards spindle disassembled. Irradiation at anaphase slowed down chromosome motion towards irradiated pole without prominent effect on the opposite halfspindle. Electron microscopy demonstrated that immediately after irradiation centrosome lost association with kinetochore microtubules. At metaphase irradiated pole moved towards chromosomes, while at anaphase--away from them. Same irradiation of other besides spindle poles regions had no effect on continuation of mitosis.