Radiation induced formation of giant cells in Saccharomyces uvarum. III: Effect of X-rays on nuclear division.

Spindle formation and nuclear division of budding and irradiated yeast cells (Saccharomyces uvarum) was investigated by fluorescence microscopy of protoplasted cells. Protoplasts were treated with antitubulin antibodies and DAPI, a fluorescent dye staining DNA. In budding yeast cells, duplication of spindle pole bodies as well as formation of complete 1-micron spindles and elongated 8-micron spindles were documented. In X-irradiated cells, spindle pole bodies were duplicated as well, forming the complete 1-micron spindle. Nuclei of giant cells have lost the elongation ability and remain in a "normal" G2-phase state, thus preventing nuclear as well as cellular division.