| Abstract: | For S. pombe cells mutations in the wee1 regulatory gene have been shown previously to allow cells to be smaller than normal at cell division, to endow the cell with a significantly long G1 cell cycle interval, and to alter the timing in the cell cycle of certain mutationally-defined cell cycle steps in G2. We show here that situations which lengthen S phase in proliferating wee1 mutant cells 'suppress' to varying degrees these wee1-mediated cell cycle alterations. Conditions chosen to protract S phase were use of cdc22.M45 mutant cells at semipermissive temperatures, and the presence of sub-arresting concentrations of the S phase inhibitors hydroxyurea or deoxyadenosine. Proliferation in the presence of each of these inhibitors was shown directly to result in protracted S phase. Residual cell division measurements were used to measure the cell cycle timing of G1 and G2 cell-cycle steps. The indirect suppression of the wee1 phenotype shown here can be understood in terms of the proposed role of the wee1+ gene product in coordinating cell division with cellular growth. |
