FIG. 4.
Northern blots of P. aeruginosa wild-type and (SigX+) and sigX mutant (SigX−) RNA obtained from log-phase (log) and stationary-phase (stat.) cells. The RNA was probed with sigX (A) and oprF (B) sequences. The arrows mark the bands corresponding to a proposed sigX-oprF transcript. The thicker bands observed in the blots probed with oprF correspond to the monocistronic oprF transcripts.