Fig. 5. Cell cycle arrest in the absence of Ini1 is Wee1 dependent. (A) DAPI images of (a) wild-type cells, (b) wee1-50ini1 cells, grown in the absence of thiamine, and (c) ini1 and (d) wee1-50ini1 cells, grown in the presence of thiamine for 12 hours. All cells were shifted to 36°C at the time of thiamine addition to c and d. Arrowheads in d indicate cells that have undergone an aberrant mitosis. Scale bar: 5 µm. (B) Quantitation of the results in A. Cell length was measured for >100 cells from two independent experiments 12 hours after shifting to 36°C in the absence (a,b) or presence (c,d) of thiamine. Data presented as mean ± s.e.m. as indicated by error bars. (C) Viability of ini1 and wee1-50ini1 following repression of ini1⁺ gene expression. All strains grown at 36°C were treated with thiamine for the indicated times. Open circles, ini1–th cells in the absence of thiamine; open squares, wee1-50ini1 in the absence of thiamine; closed squares, ini1 cells in the presence of thiamine; closed circles, wee1-50ini1 in the presence of thiamine. Data presented as mean±s.e.m. as indicated by error bars.