Manganese mutagenesis in yeast: II. Conditions of induction and characteristics of mitochondrial respiratory deficientSaccharomyces cerevisiaemutants induced with manganese and cobalt

SUMMARY Manganese and cobalt are capable of inducing ρ−mutations* in non-growing cells ofSaccharomyces cerevisiae, but their mutagenic action is much stronger in growing cells. At a given concentration cobalt and manganese can be either strongly mutagenic or non-mutagenic, depending on the cell density. Most of the ρ−mutants induced with manganese and a considerable proportion of those induced with cobalt are suppressive and/or transmit drug resistance markers, so they must still carry mitochondrial DNA. Cobalt can decrease suppressiveness with low efficiency and eliminate drug resistance markers from established ρ−clones.