COORDINATION OF INITIATION OF NUCLEAR DIVISION AND INITIATION OF CELL-DIVISION IN SCHIZOSACCHAROMYCES-POMBE - GENETIC INTERACTIONS OF MUTATIONS

sep1(+) encodes a Schizosaccharomyces pombe homolog of the HNF-3/forkh ead family of the tissue-specific and developmental gene regulators id entified in higher eukaryotes, Its mutant allele sep1-1 causes a defec t in cytokinesis and confers a mycelial morphology. Here we report on genetic interactions of sep1-1 with the M-phase initiation mutations w ee1(-), cdc2-1w, and cdc25-22, The double mutants sep1-1 wee1(-) and s ep1-1 cdc2-1w form dikaryon cells at high frequency, which is due to n uclear division in the absence of cell division, The dikaryosis is rev ersible and suppressible by cdc25-22, We propose that the genes wee1(), cdc2(+), cdc25(+), and sep1(+) form a regulatory link between the i nitiation of mitosis and the initiation of cell division.