Rim101-mediated metal resistance. (a) Serial dilution assays documenting the cadmium and nickel resistance of rim101Δ and of representative Rim101-related mutants. Wild-type (WT) and mutant strains were grown in the absence of exogenously supplied metals or in the presence of the indicated concentrations of cadmium and nickel. (b) Over-expression of Nrg1, but not Smp1 (two transcription factors negatively regulated by Rim101), enhances tolerance to both cadmium and nickel compared with WT cells. Scaled down concentrations of cadmium and nickel were utilized for these assays, which were conducted under selective, synthetic dextrose medium conditions. (c) Increased cadmium/nickel tolerance of a strain disrupted in TAT1, a membrane transporter negatively regulated by Nrg1. (d) Intracellular nickel accumulation by WT, rim101Δ, and tat1Δ cells analyzed by Newport Green staining (see 'Materials and methods' for details); the percentage of fluorescent cells (average ± standard deviation of three independent experiments) is expressed relative to WT (100%).