Fig. 3. rex2Δ results in a defect in U4 snRNA processing. The strains indicated were grown to early- to mid-log phase in YPD at 30°C. RNA was extracted and analyzed by Northern blotting. Numbers to the left of (B) and (C) indicate the position of DNA molecular weight markers. (A) A Northern blot was probed for U4 snRNA. The migration of mature U4 snRNA from wild-type strains is indicated. (B) U4 snRNA was cleaved with oRP756 and RNase H, or treated with RNase H in the absence of any oligonucleotide before electrophoresis. The Northern blot was probed for U4 snRNA. The positions of mature U4 snRNA and the 3′ RNase H cleavage fragment are indicated. (C) A dark (upper panel) and light (lower panel) exposure of the same Northern blot probed for U4 snRNA is shown. The migration of mature U4 snRNA from wild-type strains is indicated.