FIG. 5.

High-MID-expressing M. catarrhalis strains express mid mRNA, whereas low-MID-expressing strains are mid mRNA deficient. (A) Northern blot hybridized with a radioactive mid cDNA probe and (B) the filter with ethidium bromide-stained RNA after blotting. The positions of rRNAs are indicated. Six moraxella strains with high-intensity peaks >99% (MID expression, +) representing 1, 2, or 3 triplets of G’s and four strains with high-intensity peaks <1% (MID expression, −) representing 4, 7, 8, or 10 G’s in their poly(G) tracts are shown. Total RNA was isolated and loaded onto a denaturing formaldehyde gel. After separation, RNA was blotted to a nylon filter that was subsequently hybridized with a ³³P-labeled DNA probe originating from the 3′ end of the mid gene.