FIG 2 .

NADI/Cox and Cu²⁺ resistance or sensitivity phenotypes of R. capsulatus mutants. (A) NADI staining. Wild type (MT1131), ΔccoA (SE8), ΔccoARev (SE8R1or SE8R2), ΔcopA (SE24), ΔccoA ΔcopA (SE25), ΔccoARevCu^R (SE8R1Cu^R or SE8R2Cu^R) strains were grown under aerobic respiratory conditions at 35°C on enriched MPYE medium (44) alone or supplemented with 5 µM CuSO₄. NADI/Cox-positive (i.e., colonies turn blue immediately [<0.5 min] when exposed to NADI stain) and NADI/Cox-negative (i.e., colonies do not turn blue over a long period of time [over 10 min]) phenotypes are indicated with + and −, respectively. (B) Cu sensitivity. Cu²⁺ response phenotypes of wild-type R. capsulatus (MT1131), ΔccoA mutant (SE8), and its revertant ΔccoARev (SE8R1 or SE8R2) were determined by plate growth assays using filter paper disks (soaked in 10 mM, 20 mM, or 100 mM of Cu²⁺ solutions) placed on top of solidified top agar containing the appropriate strains.