Figure 4.

Effect of Mn²⁺ on the mutation rate of the CAN1 forward mutation assay. The CAN1 assay detects any mutation which inactivates the CAN1 gene (arginine permease) and allows cells to grow on plates containing the toxic arginine analog, canavanine. The assay was performed using the wild-type strain in the presence of 1.5 mM Mn²⁺ or cotreated with 1.5 mM Mn²⁺ and 10 mM GSH or 1.5 mM Mn²⁺ and 10 mM NAC as indicated. Appearance of colonies on canavanine containing plates is scored and mutation rates are determined as described in Section 2. and standard deviation is included at the top of each bar.