Figure 1. Growth phenotyping, gene expression analysis, siderophore production, and azole resistance of Aspergillus fumigatus CBC mutants.
(A) Growth pattern of A. fumigatus wild-type (wt), hapEP88L, hapEP88LΔhapX, ΔhapX, and ΔhapC strains on solid minimal medium containing different iron concentrations. Growth was evaluated after incubation at 37°C for 48 h. (B) Production of biomass in submersed cultures (liquid growth at 37°C for 24 h) during iron starvation (−Fe), iron sufficiency (0.03 mM FeSO4, +Fe), and iron excess (2.5 mM FeSO4). (C) Gene expression levels of the CBC and CBC–HapX target genes mirB (siderophore transporter), cccA (vacuolar iron transporter), cycA (cytochrome c), and cyp51A (14-α sterol demethylase Cyp51A) under the indicated iron conditions. Northern blot analyses were performed from liquid cultures grown at 37°C for 20 h under iron starvation (−Fe) or iron sufficiency (0.03 mM FeSO4). Alternatively, mycelia were shifted for 30 min from −Fe to iron sufficiency (0.01 mM FeSO4, sFe) to generate short-term iron excess. As a loading control, ribosomal (r)RNA levels are shown below. (D) Siderophore production (triacetylfusarinine C and fusarinine C) in mutant A. fumigatus strains compared with wt in the absence of iron. (E) Iron-dependent azole resistance of A. fumigatus mutants. Voriconazole (10 μl of 320 μg/ml) was spotted on agar plates inoculated with A. fumigatus spores, and the width of the inhibition zone was observed as a measure of drug resistance after 48 h. The narrower the inhibition zone was, the more resistant the strains were. Data information: In (B, D, E), data are presented as the mean and SD of three biological replicates and analyzed by one-way ANOVA with Tukey’s multiple comparison test (*P ≤ 0.05; **P ≤ 0.01; ***P ≤ 0.001; ns, not statistically significant).
Source data are available for this figure.
