FIG. 1.

Relative levels of cDNA for opuCA, expressed as log (opuCA mRNA copy number/mean housekeeping gene [HKG] copy number) for L. monocytogenes wild-type strain 10403S (solid bars), ΔsigB (shaded bars), ΔrsbT (cross-hatched bars), and ΔrsbV (open bars) exposed to salt stress (BHI broth containing 0.3 M NaCl). Following addition of the NaCl, cells were collected by centrifugation (5 min, 2,520 × g) either immediately (“no incubation”) or following exposure to NaCl for 5 min. RNAprotect was added to stop transcription and stabilize the RNA following centrifugation. The values are the means from three independent experiments. Comparisons of the four strains under each condition (e.g., normalized opuCA transcript levels in BHI broth with no incubation for the wild-type and three mutant strains) using Fisher's LSD resulted in identification of strains whose opuCA transcript levels differed; the bars for strains whose opuCA transcript levels differed (within a given condition) are labeled with different letters.