INTERCONVERSION OF YEAST MATING TYPES III. ACTION OF THE HOMOTHALLISM (HO) GENE IN CELLS HOMOZYGOUS FOR THE MATING TYPE LOCUS

[摘要] Mating type interconversion in homothallic Saccharomyces cerevisiae has been studied in diploids homozygous for the mating type locus produced by sporulation of a / a / a /α and a / a /α/α tetraploid strains. Mating type switches have been analyzed by techniques including direct observation of cells for changes in α-factor sensitivity. Another method of following mating type switching exploits the observation that a /α cells exhibit polar budding and a / a and α/α cells exhibit medial budding.—These studies indicate the following: (1) The allele conferring the homothallic life cycle (HO) is dominant to the allele conferring the heterothallic life cycle ( ho ). (2) The action of the HO gene is controlled by the mating type locus—active in a / a and α/α cells but not in a /α cells. (3) The HO (or HO -controlled) gene product can act independently on two mating type alleles located on separate chromosomes in the same nucleus. (4) A switch in mating type is observed in pairs of cells, each of which has the same change.

[学科分类] 医学（综合）