FIG. 1.

Expression of sigM in M. tuberculosis. (A) Analysis of the expression of the sigM gene at different growth phases in M. tuberculosis. Total RNA was isolated from M. tuberculosis CDC1551 cultures grown to the OD₆₀₀ shown. Phases of growth were identified as described earlier (11). Quantitative RT-PCR was performed, and the relative expression of sigM was calculated using sigA transcript as normalization for RNA amounts and a 0.2 OD growth phase as a control. The graph shown represents an average of three experiments. (B) Analysis of the expression of the sigM gene under various stress conditions in M. tuberculosis. Total RNA was isolated from M. tuberculosis CDC1551 cultures grown to an OD₆₀₀ of 1.0 and treated with various stresses for 3.0 h as described in Materials and Methods. Quantitative RT-PCR was performed, and the relative expression of sigM was calculated using normalization to sigA transcript levels, which remained constant under these conditions. The graph shown represents an average of three experiments. Error bars indicate standard deviations.