FIG 3.

Gene expression of low-GC-content genes is induced during exposure to saline hyperosmotic stress. (A) Steady-state mRNA transcript levels of low-GC-content genes in a Y. pestis KIM6⁺ parental strain treated or not treated with 0.5 M NaCl were determined. The data are represented as the fold change in gene expression of treated versus untreated mRNA transcript levels. Error bars represent the mean (±SD) of the results from 3 independent experiments. (B) Activities of the transcriptional fusion plasmids pCS::P55, pCS::P5x, and pCS::P50 carrying the transcriptional fusions of the luciferase genes and predicted promoter regions of y3555, y355x, y3550, respectively, pre-treatment with vehicle (white bars) or 0.5 M NaCl (gray bars) and 100 min post-treatment with vehicle (white dotted bars) or 0.5 M NaCl (gray dotted bars). Error bars represent the mean (±SD) of the results from three independent experiments. Data were analyzed using Student's t test; **, P < 0.01; ****, P < 0.0001; ns, not significant.