Quantitative Northern analysis of pacC transcript levels at 37°C. RNA was extracted from wild-type (WT), pacC+/−230, nmdA1, and pacC+/−230 nmdA1 strains. Transcription was inhibited prior to commencement of the time course, and samples were taken over a 30-min period, as indicated. (A) pacC mRNA levels were monitored by Northern analysis. The phosphorimager data from triplicate experiments were compiled for further analysis. (B) pacC transcript degradation rates for the four strains were plotted. Over the 30-min time course, the WT (pacC+ nmdA+) (□) pacC transcript appeared to be more labile than those of the pacC+ nmdA1 (○), pacC+/−230 nmdA+ (▪), and pacC+/−230 nmdA1 (•) strains. The standard error is given for each value. (C) The relative levels of pacC in the four strains at time zero were determined from these data. Surprisingly, the pacC+/−230 strain had an expression level similar to that of the wild type; however, in the double mutant significantly higher expression levels were observed.