FIG. 2.

Northern blot comparison of spa transcription in different strain backgrounds. RNA was extracted from strains CHE482, Newman, ZH44, and COLn. WT, wild type; Δ, ΔxdrA deletion mutant; C, mutant complemented with xdrA in trans. Levels of spa transcription differed greatly among the four different strain backgrounds; however, spa levels were significantly decreased in all xdrA deletion mutants and were restored to wild-type levels by trans-complementation. Northern blotting was also performed to compare the levels of spa with levels of xdrA, sarS, sarU, and sarT present in each of the strains. Probes used for hybridization are given on the right. Ethidium bromide-stained 16S rRNA bands are shown beneath the transcripts as an indication of RNA loading.