FIG. 2.

Production of the U18 snoRNA from wild-type (wt) EFB1 and its splicing mutant derivatives. (A) Total RNA was extracted from strain CH1462 transformed with the pGALU18wt (wt lanes), pGALU18C5 (C5 lanes), and pGALU18Cbs (Cbs lanes) plasmids at different times of galactose induction (hr-gal). Samples of 5 μg were run on a 6% acrylamide–7 M urea gel, electroblotted onto a nylon membrane, and hybridized with the anti-tag oligonucleotide. The different products are indicated on the right, together with their schematic representations (dark boxes are exons, open boxes are U18, and lines are intronic sequences plus the 5′ UTR). The numbers above the lanes indicate hours of galactose induction. The same filter was rehybridized with oligonucleotides E5′ (B) and E3′ (C), which are complementary to the 5′ and 3′ exons, respectively. (D) Control hybridization to U1 RNA. Oligonucleotides used in filter hybridizations are indicated below the panels. Lanes M contained MspI-digested pBR322 plasmid DNA. Molecular sizes are indicated on the left in nucleotides.