FIG. 2.

Northern blot analysis of RNA from the sigC operon. RNA was prepared from L. monocytogenes strain 10403S grown to mid-logarithmic phase at 37°C in brain heart infusion and 30 min after temperature upshift or downshift (48°C or 4°C), addition of NaCl (to 4%), ethanol (to 4%), nisin (to 62.5 U/ml), penicillin G (50 μg/ml), or bile (0.08%). Total RNA was extracted from the treated cells and 50-μg samples of RNA were loaded in the appropriate lanes. The blots are derived from independent experiments with 37°C and 48°C included on both blots as a point of reference. Both blots shown were probed with a 293-bp segment of the sigC gene amplified using the Lm423F1 and Lm423R1 primers (the amplicon extends from +121 to +414 of the lmo0423 coding region).