Effects of alkali and acidic pH on RNA X. (A) RNA X is extremely alkali-sensitive. The reaction mixture analyzed in the lane on the left (Ctrl) was incubated for 10 min at pH 7.2, whereas the pH of the sample on the right was raised to pH 8.8. The position of RNA X is shown to the left. (B) Quantitative analysis of alkali-sensitivity of RNA X. The reactions are done at pH 9 (triangles), pH 10 (rectangles), pH 11 (diamonds), and pH 12 (squares). (Inset) Comparison of alkali-sensitivity of RNA X (diamonds) versus a phosphodiester bond (circles). (C) RNA X is relatively stable in acidic pHs. Samples were brought to pH 1.0 by addition of HCl to a final concentration of 0.2 N and reactions incubated for 10 min. The temperature of incubation is indicated above each lane. (Ctrl) Sample incubated at pH 7.2. Lanes labeled Br and U6 display input Br and U6 RNAs. The positions of U6, Br, and RNA X are shown to the left.
