Figure 8.

Expression of Cdc42^G12V results in loss of polarity and septin bars. (A) Cells expressing Cdc42^G12V from the regulatable PCK1 promoter are swollen and show tip splitting (arrow) compared with parental cells (B). Septin rings form normally in the first cycle after induction, but in the second cycle septins form longitudinal bars rather than rings (C and D). Mlc1-YFP does not localize to apical spots in the majority of cells; in some cells, it forms a faint crescent and in some cells no apical localization is evident (E). Cells of the indicated genotype were grown overnight to stationary phase in YEPD (CDC42^G12V repressed), washed in distilled water, and reinoculated into media containing 2% Cas amino acids (Difco) 0.67% yeast nitrogen base, 80 mg l⁻¹ uridine, pH 5.0, 35°C (pseudohyphal-inducing conditions, CDC42^G12V induced). Images were recorded after 150 min. Arrow in C indicates cells enlarged in D. Bars, 10 μm (A and B) and 5 μm (C–E). The cells shown in C and D were fixed and stained with concanavalin A–Texas-Red and 4,6-diamidino-2-phenylindole (DAPI). The cells shown in E are unfixed.