FIG. 1.

A dnaA(Sx) mutation reduces chromosome and origin content of dnaX⁺ and Ts strains in glucose-Casamino Acids medium at 34°C. Cells growing exponentially were stained directly (A, C, E, and G) or after incubation in the presence of rifampin and cephalexin to allow replication completion (B, D, F, and H) and analyzed for DNA content by flow cytometry (39). Counts refer to the number of cells. Wild-type (dnaA⁺ dnaX⁺) strain AB21 (A and B), dnaA R432L dnaX⁺ strain AB20 (C and D), dnaA⁺ dnaX(Ts) strain AB27 (E and F), and the double mutant dnaA R432L dnaX(Ts) strain EGC23 (G and H) were analyzed.