FIG. 3.

Regulation of virulence factor gene expression in CsrR mutant strains. Autoradiography of RNA blot hybridizations demonstrates increased cylE (beta-hemolysin) and scpB (C5a peptidase) transcripts, reduced cfb (CAMP factor)transcript, and slightly increased alp1 (alpha-like protein 1) and rib (protein Rib) transcripts in CsrR mutant strains 515csrRΔ and/or 2603csrRΔ. Indicated amounts of RNA were blotted onto nylon membranes, which were then hybridized with ³²P-labeled DNA probes from the indicated genes. No significant difference was observed between wild-type and mutant strains in expression of control genes recA and rpsL. Each blot is representative of two to four independent experiments.