Novel cell cycle regulation in the yeast Schizosaccharomyces pombe. The DNA-division sequence modulates mass accumulation

For wee1 mutant cells of Schizosaccharomyces pombe the DNA-division sequence of the cell cycle can be differentially slowed by the presence of low concentrations of the S-phase inhibitor hydroxyurea, or by semipermissive temperatures for certain wee1 cdc double mutants. Under these conditions the rate of proliferation is decreased, yet still exponential. Relief of these constraints slowing the DNA-division sequence resulted in prompt increases in the exponential rates of mass accumulation, to rates greater than those normally found. These observations suggest that mass accumulation by this yeast is always modulated by performance of the DNA-division sequence.