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

Area of Science:

• Microbiology
• Genetics
• Cell Biology

Background:

• Different yeast species and ploidy levels can exhibit distinct responses to mutagenic agents.
• Understanding genotoxicity mechanisms is crucial for microbial research and applications.

Purpose of the Study:

• To investigate the sensitivity of haploid and diploid yeast strains (Saccharomyces cerevisiae, Sacch. ellipsoideus, Pichia pinus) to N-methyl-N itro-N-nitrosoguanidine (MNNG).
• To characterize the survival curves and cellular responses following MNNG treatment.

Main Methods:

• Exposure of haploid and diploid strains of Saccharomyces cerevisiae, Sacch. ellipsoideus, and Pichia pinus to N-methyl-N itro-N-nitrosoguanidine (MNNG).
• Analysis of survival curves and clone formation kinetics post-MNNG treatment.
• Observation of cellular inactivation patterns.

Main Results:

• Significant differences in MNNG sensitivity were observed between haploid and diploid strains within the same species, and between different species.
• All studied yeast strains exhibited exponential survival curves with a characteristic "tail" after MNNG treatment.
• A delay in clone appearance was noted for MNNG-treated cells across all strains.
• Three distinct forms of cell inactivation, analogous to those seen after irradiation, were identified.

Conclusions:

• Ploidy and species significantly influence yeast sensitivity to the mutagen MNNG.
• Yeast strains display consistent patterns of delayed clone formation and inactivation following MNNG exposure, irrespective of their ploidy.
• The observed inactivation forms suggest common cellular responses to DNA damage induced by MNNG and irradiation.