FIG. 2.

NHEJ is required for resistance to IR in late stationary phase. Wild-type, NHEJ-deficient, HR-deficient, or HR/NHEJ-deficient strains were exposed to gamma irradiation from a ¹³⁷Cs source, and survival was calculated by enumerating surviving colonies compared to a mock-exposed control sample of the same strain. Panel A depicts cells harvested from logarithmically growing cultures in LB medium. Panel B compares logarithmic- and early-stationary-phase cells of wild-type, ΔrecA, and ΔrecA Δku strains in LB medium. Panel C shows late-stationary-phase cells grown in LB medium. Panel D shows late-stationary-phase cells grown in 7H9 medium. For panels C and D, the symbols are identical to those in panel A. Error bars are ± standard errors of the means. WT, wild type.