FIG. 1.

Northern blotting analysis of soxS expression from strains ATCC 14028 and EM1/pJP105. (A) Northern blotting. A radioactively labeled 450-bp EcoRI-HpaI fragment of plasmid pBCKpn (Martins et al., unpublished data) containing the S. enterica serovar Typhimurium soxS coding region was hybridized with total RNA from strain ATCC 14028 (wild type) treated with increasing concentrations of PQ (0, 25, 100, or 250 μM; lanes 1 to 4, respectively) or strain EM1(ΔsoxRS)/pJP105 treated with increasing concentrations of IPTG (0, 0.125, 0.50, or 1.00 mM; lanes 6 to 9, respectively). The control strain, EM1/pBR322, was treated with 1.00 mM IPTG (lane 5). (B) Quantitation of the soxS radioactive signal. The radioactivity for the soxS band in each lane was quantitated by phosphorimaging. The values are the relative activations for the treatments, normalized to the signal in the absence of treatment in the wild-type samples and to the signal from lane 5 in panel A. The lane numbers correspond to those in panel A. (C) Total RNA loading. Shown is an ethidium bromide stain of a duplicate gel to that used for panel A.