FIG. 2.

Different phenotypes of the sng1⁻ mutant. (A) Temperature sensitivity. Strains used were wild-type strain SP837 (h⁹⁰ leu1-32 ura4D18 ade6-M216) and mutant strain SPJ107 (h⁹⁰ leu1-32 ura4D18 ade6-M216 sng1⁻). Temperatures at which strains were grown are indicated. h⁹⁰ denotes homothallic strains that undergo sng1-1 efficient mating-type switching. (B) Haploid meiosis. The sng1⁻ mutant cells exhibiting haploid meiosis are indicated by arrows. Wild-type cells produce asci containing four mature spores in zygotic diploid cells which result from switching and mating of cells of opposite mating type. In contrast, the sng1⁻ mutant cells produce aberrant spores in a haploid cell.