Alpha-mating-type-specific suppression and a-mating-type-specific enhancement by tunicamycin of sexual agglutinability in the yeast Saccharomyces cerevisiae.

Effects of tunicamycin (TM) on the sexual agglutinability and zygote formation of Saccharomyces cerevisiae were studied using the two kinds of haploid strains, inducible and constitutive for sexual agglutinability. Induction of sexual agglutinability by opposite mating type sex pheromone of inducible strains was inhibited by TM in alpha mating type but not in a mating type. The recovery by temperature-shift-down from the temperature-suppressed sexual agglutinability of constitutive strains was enhanced by TM in a mating type but rather inhibited in alpha mating type. Pretreatment with TM of constitutive strains enhanced sexual agglutinability in a mating type but not in alpha mating type. The above-mentioned a-mating-type-specific agglutinability-enhancing actions of TM were discussed in relation to the action mechanism of alpha pheromone which induces or enhances the sexual agglutinability of a cells. Zygote formation was inhibited by TM in both constitutive and inducible strains at concentrations which showed only partially inhibitory effect on sexual agglutinability.