Northern blot analysis of 23S rRNA from various ribonuclease mutant strains. Total cellular RNA was extracted from cells grown in M9/glucose at 31°C to early exponential phase and then either starved for 4 h (−glucose) (B) or grown for 4 h (+glucose) (A) at 42°C. Northern analysis was carried out with probe h complementary to residues 2886–2904 of 23S rRNA. The diagram at the top shows the location of the probe. The arrow indicates the endonuclease cleavage site in 23S rRNA. Note that the WT lane in A was cut and rejoined to the other lanes in the gel. (C) Effect of RNase PH on degradation of 23S rRNA in vivo. Northern blot analysis of total RNA isolated from different strains after 4 h incubation in the presence (+g) or absence (−g) of glucose, as indicated.
