Induction of respiration-deficient mutants by ultraviolet radiation in a synchronous yeast cell culture

Haploid cells ofSaccharomyces cerevisiae in a synchronous culture were exposed in different phases of division to UV radiation lethal for 98% of the cells and the occurrence of respiration-deficient mutants among the survivors was determined. Comparison of the various phases showed significantly higher occurrence of these mutants at the onset of budding. It was concluded that the mitochondrial DNA also replicates synchronously in a synchronous yeast cell culture, but in a different phase from the nuclear DNA.