Fig. 2. Ergosterol biosynthesis is important for filamentation.

(A) Transcriptional repression of most ergosterol biosynthesis genes with 0.05 μg mL⁻¹ DOX blocks filamentation induced by serum. An asterisk (*) indicates strains where 1 μg mL⁻¹ DOX was used to repress target gene transcription. For all images, scale bar is 20 μm.Ergosterol biosynthetic pathway adapted from S. cerevisiae²⁰. (B) Clustering analysis of GRACE strains for ergosterol biosynthesis genes and phenotypes observed in distinct filament-inducing conditions with 0.05 μg mL⁻¹ DOX. White boxes indicate a lack of growth in that condition. Clustering was performed using the Heatmap function in R. (C) Treatment with sub-lethal concentrations of specific antifungal drugs reversibly blocks filamentation induced by serum. Top panels: morphology in the presence of drug. Middle panels: morphology after removal of drug. Bottom panels: growth kinetics analysis demonstrates that the drugs do not significantly inhibit growth at the concentrations used.