FIG. 1.

Northern analysis of sar transcripts of S. aureus RN6390, its isogenic sigB mutant ALC1001, and complemented mutant ALC1497. Northern analysis revealed that the sigB gene was transcribed in ALC1497 (data not shown). Ten micrograms of total cellular RNA obtained at the stationary phase (OD₆₅₀, 1.7, as determined with an 18-mm borosilicate glass tube) was applied to each lane. The probe was a 730-bp sarA fragment (nucleotides 620 to 1349, based on the published sequence) (3). Because the transcription of sarB, the largest transcript within the sar locus, was minimal during the late log and stationary phases, only data for sarA and sarC transcripts are shown.