FIG. 4.

Wild-type cells from an overnight culture in M9 minimal medium were diluted in fresh medium and incubated at 37°C with shaking at 150 rpm. At an OD₆₀₀ of 0.2, NaCl was added to half of the culture, to make a final 500 mM solution, and the rest was used as a control. Samples were collected immediately (<1 min) after the addition of NaCl and at 5, 10, and 15 min of exposure. Samples were frozen with liquid nitrogen, and total RNA was purified as described in Materials and Methods. The fluorescence signal of each PCR product was compared to that of gapA. Data are from an average of eight MPCR amplifications. Values from treated samples were divided by those from the corresponding control. All genes were analyzed, but only those genes for which statistically significant (P < 0.05) increases were observed at a given time are represented. Error bars were estimated from the corresponding SEM.