Northern blot analysis of processing of mutant pre-18S RNAs. (A) Total RNAs were extracted from Utp9-TAP strains expressing plasmid-encoded wild-type (WT) or mutant pre-18S RNA. RNA (15 µg) was resolved in 1.2% agarose-formaldehyde gel and hybridized against 32P-labeled probes that hybridize the 18S-tag and TOB-tag unique to plasmid-derived RNAs. Mutants are designated by the range of deleted (Δ) or mutated (M) nucleotides. The mutated region is shown on the top of each lane to assist navigation. (B) Quantification of the 18S to pre-18S ratio. Hybridization signals of the 18S-tag probe were measured. Means and standard deviations were calculated from multiple samples (n = 22 for the WT sample, 3–6 for other samples). (C) Illustration of analyzed 5′ ETS mutations. The original and new sequences are shown on sections of 5′ ETS model.
