FIG. 1.

Hyphal induction by exogenous H₂O₂. (A) Microscopic images of H₂O₂-induced hyphae. Wt cells were grown on YPD solid plates supplemented with the indicated concentrations of H₂O₂ at 30°C for 6 days. Representative colonies were photographed with a stereomicroscope (top). Cells in the mid-log phase were cultured in YPD liquid medium containing H₂O₂ for 6 h at 30°C and observed with a light microscope (bottom). (B) Cytotoxicity of H₂O₂. Standardized cell suspensions were challenged with the indicated concentrations of H₂O₂ for 30 min, plated onto YPD solid medium, and incubated at 30°C for 2 days. The survival rate was expressed as a percentage of the number of colonies in the presence of H₂O₂ divided by the number of colonies in the absence of H₂O₂. (C) Efficiency of hyphal differentiation. Cells were grown on YPD solid medium containing the indicated concentrations of H₂O₂ and incubated at 30°C for 6 days. The percentage of hyphal differentiation was expressed as the number of hyphal colonies divided by the total number of colonies.