[Inactivating effect of N-methyl-N'-nitro-N-nitrosoguanidine on yeasts with different ploidies].

Haploid and diploid strains of Saccharomyces cerevisiae, Sacch. ellipsoideus and Pichia pinus were studied. Differences in N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) sensitivity were detected both between haploids and diploids of the same species and between the corresponding strains of different species. Survival curves after MNNG treatment of all strains irrespectively of ploidy were exponential with "a tail". All the strains also exhibited the delayed appearance of clones from MNNG-treated cells. Three different forms of cell inactivation after MNNG treatment were detected similar to those observed after irradiation.