Changes in production of the mating-type-specific glycoproteins, agglutination substances in association with mating type interconversion in homothallic strains of the yeast, Saccharomyces cerevisiae.

Sexual activity in homothallic strains of Saccharomyces cerevisiae was investigated. We succeeded in culturing homothallic haploid cells without conjugation, by lowering the pH value of the culture medium. In spore cultures of a homothallic strain both a and alpha pheromones were detected. Agglutination substance of a and alpha mating types were detected in homothallic haploid cells from spore cultures in early logarithmic phase regardless of mating type information at the HML and HMR loci, but either a or alpha agglutination substance was detected predominantly in homothallic haploid cells from spore culture in late logarithmic phase, depending on mating type information at the HML and HMR loci.