A. Reporter assay of virF promoter activity in an hns mutant. An hns deletion mutant of S. sonnei strain MS4841 carrying virFTL-lacZ (striped bars) was grown in YENB media with or without 150 mM NaCl were subjected to the β-galactosidase assay. For a comparison of activities, the data from Figure 1C, Graph 1, which was derived from simultaneous assays, is indicated by three solid bars on the left side of the graph. Strain and concentration of NaCl are indicated at the bottom of the graph as follows: Wt, wild-type strain (solid bars); hns, hns deletion mutant (striped bars); YENB medium, 0 (white bars); YENB medium with 150 mM NaCl, 150 mM (gray bars). B. Western blot analysis of H-NS and CpxR expression. An overnight LB culture of MS390 at 30°C was inoculated into fresh media and then the cells were cultured until they reached mid-log phase (A600 = 0.8). Media, temperature (YENB at 37°C; LB at 30°C and 37°C) and the concentration of NaCl are indicated on the top of the panel. Antibodies used for detection are indicated on the right side of the panels. A cross-reactive unknown protein detected by the anti-H-NS antiserum was used as a loding control.