Fig. 8.

Fre8 dependent ROS and the Cdc24 GEF for Cdc42.A–D, germ tubes of the designated strains were formed under conditions to repress MET2-driven CDC24 as described for CDC42 for Figure 7. Cells were imaged (A), FRE8 mRNA analyzed (B), and ROS measured by luminol chemiluminescence (C and D) as for Figure 6. The bars in part A represent 10 microns. Data represent seven (B) or five cultures (D) in three experimental trials. The bar represents mean; error bars represent SD. ∗∗∗∗p < 0.0001 as determined by two-tailed t test. The following strains were utilized: WT, BWP17; cdc24, PY101. E and F, CDC24 and CDC42 mRNA was quantitated by quantitative RT-PCR in the indicated strains induced to form germ tubes in IMDM. Data represent four independent cultures over two trials. Differences were not significant as determined by one-way ANOVA. GEF, guanine nucleotide exchange factor; IMDM, Iscove's modified Dulbecco's medium; ns, not significant; ROS, reactive oxygen species.