Figure 2.

Flow cytometry of wild-type and ΔseqA cells. (A,B) Wild-type MG1655 and (C,D) JC326 (MG1655ΔseqA:tet^R) cells were grown in M63+glucose medium (37°C, overnight), diluted into LB medium to an initial culture optical density (A_{600 nm}) of 0.02. The cells were allowed to grow for 3 h at 37°C and maintained at or below an optical density of 0.1 with appropriate dilutions, and then immediately fixed in 77% ethanol. DNA content (A,C) and light scattering (B,D) distributions were determined by flow cytometry, as described previously (Li et al, 2002). Relative DNA/mass ratios (see text) were obtained using Winbrite 2.03 software (Bio-rad, Hercules, CA, USA) with the ratios of population mean values for DNA fluorescence and light scattering calculated. The ratio for the seqA mutant was normalized to that of the wild type to give the relative DNA/mass ratio of the mutant.