Genetic analysis of two spored asci produced by the spo 3 mutant of Saccharomyces.

Ascospores present in two-spored asci formed by sop3-1 diploids at a semipermissive temperature (30 degrees C) represent random inclusion of haploid genomes into ascospores and exhibit normal viability, meiotic chromosome segregation and recombination. Genetic analysis and ultrastructural studies indicate that the function encoded by the sop3 locus is specifically required for the enclosure of the products of meiosis in prospore walls.