Common genes and pathways in the regulation of the mitotic and meiotic cell cycles of Schizosaccharomyces pombe

Summary Cell division cycle mutants defective in G₁, DNA replication or nuclear division were tested for sporulation at semi-restrictive temperatures. In cdc1-7, cdc5-120, cdc17-L16 and cdc18-46 no abnormalities were observed; cdc10-129, cdc20-M10, cdc21-M6B, cdc23-M36 and cdc24-M38 formed four-spored asci but with a low efficiency; cdc22-M45 was completely defective in meiosis, but could conjugate and formed zygotes with a single nucleus. Mutants defective in the mitotic initiation genes cdc2, cdc25 and cdc13 were blocked in meiosis II. None of the wee1-50, adh.nim1⁺ and win1⁺ alleles had any affect on sporulation, suggesting that their interactions with cdc25 and cdc2 are specific to mitosis. The meiotic function of cdc13 is TBZ-sensitive and probably exerted downstream of cdc2. Single mutants in cut1 or cut2 did not effect sporulation, whereas the double mutant cut1 cut2 formed two-spored asci. The results demonstrate that the cell division cycle and the meiotic developmental pathway share common genes and regulatory cascades.