[Post-radiation recovery and the ploidy factor].

Radiobiologicae effects on extensively homozygous Sacharomyces cerevisiae strains of different ploidy from haploid to hexaploid (developed by W. Laskovski) were studied. Radiation (gamma-rays of 60Co) inactivation studies showed a minimum of resistance of haploid strains, a maximum of resistance of diploid or triploid strains and a decrease of resistance with further increasing genome number. The explanation of such dependence of radiosensitivity on ploidy is usually due to the increase of dominant lethal damages and the corresponding decrease of recessive lethal damages with the increase of ploidy. All studied strains (except haploids) were capable of recovery of radiation damages after their storage in non-nutrient media during postradiation period. Since haploids are inactivated almost exclusively by recessive lethal damages, one may suppose that reversible part of radiation damages is due to dominant lethal damages. Then an irreversible part of radiation injury must decrease with the increase of ploidy. Indeed, in studied strains an irreversible component of radiation injury was significantly reduced with the increasing genome number. Any correlation of the probability of recovery from the primary damages with ploidy was not discovered.