FIG 7.

Expression of protease genes in wild-type Serratia sp. SCBI under different environmental conditions. qRT-PCR was performed on RNA extracted from Serratia sp. SCBI during exponential-phase growth (Exp.) in LB medium, during hemolysis of SRBCs, during active infection of M. sexta, and following death of M. sexta. mRNA levels were normalized to the mRNA level of rplU housekeeping gene and compared to the calibrator (exponential-phase cells). Data are presented as the relative changes in gene expression between the values obtained with the test conditions and the calibrator. (A to D) Expression levels of prtA1 and prtA2 (A), prtA3 and prtA4 (B), serine protease 1 and serine protease 2 (C), and yfgC and the secreted metalloprotease (D). Values are means ± standard deviations (error bars) from at least two independent experiments. Relative gene expression values that are significantly different (P < 0.05) from the value for the calibrator (exponential-phase cells) are indicated by an asterisk.