FIG. 8.

Osmotic stress, but not oxidative stress, increases cell susceptibility to Hst 5. For radial diffusion assays, C. albicans cells (10⁶/ml) were trapped in thin underlay gels, some of which were supplemented with sorbitol (1 M) or H₂O₂ (1 mM). Twofold dilutions of Hst 5 (7.8 to 250 μM) were loaded into 3-mm-diameter wells that had been punched into underlay gels. After overnight incubation at 37°C, the clear-zone diameters indicating antifungal activity (upper panel) were measured to the nearest 0.1 mm and graphed against peptide concentrations (lower panel). Zone diameters are expressed in units (0.1 mm = 1 U). Cells grown under concurrent osmotic stress (1 M sorbitol) (open circles) were significantly more susceptible to Hst 5 at all concentrations tested than cells grown in medium alone (solid squares), while cells grown under concurrent oxidative stress (1 mM H₂O₂) (solid circles) showed no difference in sensitivity to Hst 5 (lower panel).