DNA degradation and reduced recombination following UV irradiation during meiosis in yeast (Saccharomyces cerevisiae)

Irradiation of meiotic yeast cells with moderate doses of ultraviolet irradiation (1,600 erg/mm²) leads to the arrest of premeiotic DNA synthesis, massive (5-40%) DNA degradation, and a 40-50% loss of cell viability. In contrast, such doses of UV irradiation had a minor effect on viability (15-20% loss) of logarithmically growing cells, and no comparable DNA degradation was observed in irradiated synchronized vegetative cells. Meiotic recombination is also affected by UV irradiation. When administered at a stage comparable to meiotic prophase, low doses of irradiation result in a reduction in recombination frequency without significantly affecting cell viability.