Fig. 2.

Expression of the sarA gene in the different wild-type strains at various phases of growth. Northern blots were hybridized with 450 bp DNA fragments containing the coding region of the sarA gene. A total of 10 μg cellular RNA was loaded in each lane. Lanes 1–6, total cellular RNA from the growing cultures at OD₆₀₀ 0.3, 0.7, 1.1, 1.4, 1.7 and overnight (stationary) (Fig. 1b). The sarB (1.15 knt), sarC (0.8 knt) and sarA (0.56 knt) transcripts originated from the P2, P3 and P1 promoters of the sarA locus (Bayer et al., 1996). The region containing the 23S and 16S rRNA of the ethidium bromide-stained gel used for blotting is shown as a loading control. The third and sixth panels from the top represent Western blots of intracellular extracts from the different wild-type strains probed with anti-SarA polyclonal antibodies. Equivalent amounts of extracts (20 μg) from the different phases of growth (OD₆₀₀ ∼0.7, early exponential; OD₆₀₀ ∼1.1, exponential; OD₆₀₀ ∼1.7, post-exponential) were used to detect SarA expression.