ABSTRACT Mutants defective in various steps of the sexual cycle have been isolated from homothallic strains of Schizosaccharomyces pombe by Bresch, Müller and Egel (1968). These mutants include heterothallic h  + and h  - strains. We have isolated additional h  + and h  -mutants from homothallic strains. Those mutants which are due to mutations in the mating-type region were analyzed in detail. Our results show that the mating-type gene mat2 not only has a function in copulation and meiosis, but that it also regulates the formation of the map1 gene product (map1 is a mating-type auxiliary gene). Some of the h  - mutants have lost only one of the three functions while others are defective in at least two, and perhaps all three, functions. Further, we show that the mat1  - allele of h90 strains can mutate to mat1  + but that mutations in mat2 appear to affect the mutational behavior of mat1. Finally, we describe a new inactive mating-type allele, mat2*, which is different from mat2  0 in that it can mutate to mat2  +.

Meade, J. H., & Gutz, H. (1976). MATING-TYPE MUTATIONS IN SCHIZOSACCHAROMYCES POMBE: ISOLATION OF MUTANTS AND ANALYSIS OF STRAINS WITH AN h  - or h  + PHENOTYPE. Genetics, 83(2), 259–273.