(A) Growth of gef1, ccc2, fet3, and tfp1 mutants in low-iron-containing medium. Approximately 105 cells of the indicated strains were grown for 3 days on YPD (1% yeast extract/2% Peptone/2% dextrose; Difco) (lane 1), YPEG (2% ethanol/glycerol) supplemented with 1 mM ferrozine (Fluka) (lanes 2 and 3) and with 0.1 mM CuSO4 (Sigma) as indicated. For the tfp1 mutants, the conditions were as above, but the medium was buffered with 50 mM Mes Tris at pH 5 (Sigma). (B) Growth of gef1, ccc2, and fet3 mutants in minimal medium at pH 7. Approximately 104 cells of the indicated strains were grown for 1 day on YPD (Difco) (lane 1), SD (Difco; synthetic medium with 2% dextrose) (19) buffered with 50 mM Mes Tris at pH 7 (Sigma) (lanes 2 and 3), and SGE (synthetic medium with 2% glycerol and ethanol) buffered with 50 mM Mes Tris at pH 7 (Sigma) (lanes 4 and 5). CuSO4 (Sigma) was added to 0.1 mM to lanes 3 and 5.