Briefly, an MTT stock solution (5 mg/ml) was prepared in PBS and added to each culture at a final concentration of 10% (v/v). The C. albicans cultures were then incubated with the MTT solution at 30°C for 4 h, after which time the plate GPCR Compound Library screening was centrifuged for 10 min at 1200 rpm
and the supernatant was removed. The remaining pellet from each well was then washed with warm PBS, with 200 μl of 0.04 N HCl in isopropanol added to each well, followed by another incubation for 15 min. Absorbance (optical density, OD) was subsequently measured at 550 nm by means of an xMark microplate spectrophotometer (Bio-Rad, Mississauga, ON, Canada). Results are reported as means ± SD of three separate experiments. Effect of KSL-W on C. albicans transition from blastospore to hyphal form To determine the effect of KSL-W on the yeast-to-hyphae transition, C. albicans (105 cells) was first grown
in 500 ml of Sabouraud dextrose broth supplemented with 0.1% glucose and 10% fetal bovine serum (FBS). KSL-W was then added (or not) to the culture at various concentrations (1, 5, 10, 15, and 25 μg/ml). The negative controls were the C. albicans cultures without antimicrobial peptide, while the positive controls represented this website the C. albicans cultures supplemented with amphotericin B (1, 5, and 10 μg/ml). The hyphae-inducing conditions were previously reported [65], consisting of culture medium supplementation with 10% fetal calf serum and subsequent incubation at 37°C. These conditions were used in our experiments. Following incubation for 4 or 8 h, the cultures were observed microscopically and photographed to record C. albicans morphology (n = 5) and the density of C. albicans transition was measured. Effect of KSL-W on C. albicans gene activation/repression C. albicans was subcultured overnight in Sabouraud liquid medium supplemented with 0.1% glucose, pH 5.6,
in a shaking water bath for 18 h at 30°C. The yeast cells were then collected, washed with PBS, and counted with a hemocytometer, after which time they were co-cultured with or without the antimicrobial peptide under hyphae- or non-hyphae-inducing conditions, as follows. Effect of KSL-W on gene activation when C. albicans was cultured under non-hyphae-inducing conditions C. albicans was co-cultured 2-hydroxyphytanoyl-CoA lyase with either KSL-W (1, 25, 100 μg/ml) or amphotericin B (1 μg/ml) or with none of these molecules (controls) in Sabouraud liquid medium supplemented with 0.1% glucose, pH 5.6. The cultures were maintained at 30°C for 3 and 6 h. Effect of KSL-W on gene activation when C. albicans were cultured under hyphae-inducing conditions C. albicans was co-cultured with either KSL-W (1, 25, 100 μg/ml) or amphotericin B (1 μg/ml) or with none of these molecules (controls) in Sabouraud liquid medium supplemented with 0.1% glucose, pH 5.6.