Figure 3.

Viability of an elo3Δ erg6Δ double mutant is rescued by supplementation with ergosterol but not by cholesterol. (A) Viability of the elo3Δ erg6Δ double mutant was assessed by loss of a plasmid-borne wild-type copy of either the ERG6 gene (pRS426-ERG6, p[ERG6]) or the ELO3 gene (pPS2, p[ELO3]) on media containing 5-FOA and supplemented with various sterols. Cells of indicated genotype were serially diluted 10-fold and replica plated on solid media supplemented with the indicated sterols (20 μg/ml), a combination of bulk concentrations of cholesterol (20 μg/ml) and sparking concentrations of ergosterol (10 ng/ml), or sparking concentra-tion of ergosterol only. Plates were incubated under anaerobic conditions for 5 d. (B) Structural requirements of sterols for the rescue of the elo3Δ erg6Δ double mutant was assessed by plasmid loss on media containing 5-FOA and supplemented with dehydroergosterol (dehydroergost.), 7-dehydrocholestrol (7-dehydrochol.), or sitosterol at bulk concentrations (20 μg/ml), or no sterols.