Inaktivierungs-Versuche mit homozygoten Hefestämmen verschiedenen Ploidiegrades

Abstract

In addition to part I of this paper the inactivation of a special series of homozygous Saccharomycesstrains of different ploidy was studied. The same inactivating agents as in I were used but this time the retardation of the formation of the first bud and the frequencies of total budding inhibited cells were observed microscopically. A marked retardation of the formation of the first bud was observed after treatment with UV and organic peroxides. On the other hand applying ionizing radiations resulted mainly in a retardation of the second budding step. Most characteristic for the different inactivating agents proved to be the frequency of total budding inhibited cells. All ionizing radiations produced nearly no total budding inhibition in diploid and polyploid strains in the dose range mainly studied. The haploid strain, on the contrary, showed an increasing frequency of total budding inhibited cells with increasing LET-values. UV-irradiation resulted in frequencies of total budding inhibition increasing with dose. The hypothesis is discussed that radiation induced total inhibition of budding may be taken as a morphological criterion for cytoplasmic inactivation.