Figure 3. The cir1 Mutants Are Defective in Expression of Major Virulence Factors.

(A) Strains were grown in low-iron medium (LIM) or RPMI medium at 37 °C under 5% CO₂. Photographs were taken after 24-h incubation and after negative staining using India ink to visualize the capsule. Scale bars denote 10 μm. WT, wild type.

(B) The cir1 mutants of the serotype D strain displayed increased sensitivity to SDS and the antifungal drug amphotericin B. Decreased sensitivity was found to miconazole.

(C) The cir1 mutants of both serotype backgrounds displayed a growth defect at 37 °C; two independently generated mutants show the same phenotype.

(D) Sensitivity of the cir1 mutants to FK506 and CaCl₂ was tested, and mutants in both serotype backgrounds displayed increased sensitivity compared to the wild-type strains.