Fig. 1.

Role of CAT1 in farnesol-induced H₂O₂ survival. (A) Epifluorescence and differential interference contrast (DIC) microscopic views of CAT1-GFP cells in exponential phase treated with 50 μM farnesol for 2 h. (B) Histogram of fluorescence intensities of CAT1 in a farnesol-treated population of C. albicans cells with CAT1-GFP promoter fusion during early exponential-phase growth in liquid culture as revealed by laser scanning cytometry. Three subpopulations visualized on the histogram by the P4, P5, and P6 bars were sorted and challenged with 10 mM H₂O₂. LF, low fluorescence intensity (P6 subpopulation); MF, medium fluorescence (P5); HF, high fluorescence (P4). AU, arbitrary units. (C) Survival of the three subpopulations of cells shown in panel A under 10 mM H₂O₂ treatment. The data are expressed as the mean value (plus standard deviation [SD]) of duplicate samples. (D) Effect of pretreatment with 50 μM farnesol on the survival of cat1/cat1 and WT cells in H₂O₂. Following 2 h of incubation with 50 μM farnesol in YPD at 30°C, cells were harvested and challenged for 90 min with 0.5 mM (Δcat1/cat1) or 10 mM (WT) H₂O₂. Survival was assessed by dilution plating. The fold survival is expressed as the ratio between the survival of farnesol-treated cells and untreated cells. The data are expressed as the mean value (±SD) of three independent cultures. Survival after H₂O₂ exposure and pretreatment with farnesol was significantly higher in CU2 (WT), but not in the cat1/cat1 mutant (t test; P < 0.05).