(A) Capsule size is shown by staining with India ink for the WT and mutant strains. Cells were cultured either in liquid LIM or on DMEM plates (for capsule induction) at 30 °C. The photographs are of cells cultured for 48 h in LIM, and the same results were obtained in several independent trials. Bar = 10 μM.
(B) Sixty cells from the cultures used for (A) were measured for cell diameter and capsule radius. Each bar represents the average of 60 measurements. The capsule sizes were statistically different (p <0.001) for all pair-wise comparisons except WT versus pka1ova1, and pka1 versus pka1ova1+OVA1.
(C) Melanin formation was tested in the strains indicated by inoculation of cultures on L-DOPA or YPD plates (as a control to demonstrate equal growth) and incubation for 2 d at 30 °C.
(D) Sensitivity of the pka1 mutant and the pka1 ova1 double mutant to LiCl. Cells were washed and 10-fold serial dilutions of a 106 cells/ml suspension were plated on either YPD or YPD + 75 mM LiCl.