Fig. 6. ROS production by dfp1 N-terminal deletion mutants requires a functional Rad3p- and Cds1p-dependent checkpoint pathway, but ROS production by the orp5-H19 strain does not. Double-mutant strains bearing orp5-H19, dfp1_13-193 or dfp1_183-191 together with rad3 or cds1 were generated by crossing. Results are shown for two independently derived isolates of each type. Strains lacking a rad3 or cds1 mutation are indicated by +. Cells in early log-phase were incubated at 30°C for 6 hours. (A) Levels of ROS production. (B) Levels of PI staining.