RNase II regulates RNase PH and is essential for cell survival during starvation and stationary phase

Degradation of rRNA during extended stationary phase. WT, RNase II⁻, RNase PH⁻, and RNase II⁻ RNase PH⁻ cells were grown in 50 mL M9/glucose at either 31°C or 42°C, and sample volumes corresponding to an equal number of cells were taken every 24 h. Cells were collected by centrifugation, and total RNA was extracted and resolved by Synergel/agarose gel electrophoresis, as described in Materials and Methods. The gel was stained with ethidium bromide and visualized by UV.