Transcriptional expression of virulence-associated genes in RDN02 (wild-type M19 strain) and RDN306 (isogenic luxS -deficient mutant). Northern blot analysis was performed with total RNA isolated from strains grown to (1) lag, (2) early-logarithmic, (3) mid-logarithmic, (4) mid-late-logarithmic, (5) late-logarithmic, (6) early-stationary and (7) stationary phase (O/N). Blots were hybridized with probes specific to fasX (A) and sibA (psp) (B) with a probe specific to 16S rRNA as loading control. The estimated sizes of transcripts are indicated. Pixel rates of signals (pixel counts obtained with probe of interest versus pixel counts obtained with the 16S rRNA probe) are shown for the different time points during growth. The blots shown are representative of three independent experiments.