Fig. 3.

Transcription of bfpA and perA is not affected by a cpxR null mutation. After overnight growth in LB, wild-type and cpxR mutant EPEC strains transformed with the bfpA–lux and perA–lux reporter plasmids were subcultured 1:100 into DMEM/F12 as described in Experimental procedures. Luminescence (cps, counts per second) and optical density of the culture (OD₆₀₀) were measured every 2 h. The normalized luminescence was calculated by subtracting the luminescence reading of a medium blank from the luminescence of the culture sample, then dividing that value by the OD₆₀₀ of the culture, reduced by the OD₆₀₀ of the blank. Experiments were performed in quintuplicate at least twice; the mean and standard deviation from the 4 h reading from one experiment are shown.