Segregation and DNA repair defect of ΔrecU, recU56 or recU71 cells. (A) Exponentially growing WT, ΔrecU, recU56 or recU71 cells in LB were fixed, stained with DAPI, and analyzed by fluorescence microscopy to visualize the nucleoid. (B and C) Survival of strains after exposure to MMS. Exponentially growing cells in LB were exposed to 10 mM MMS for a variable time, and serial dilutions were plated to measure survival rates. (B) rec⁺, ΔrecU, recU56, recU71 and ΔruvAB cells; (C) ΔrecA, ΔrecA ΔrecU, ΔrecA recU56 and ΔrecA recU71 cells.