Figure 1

Location of Ψ in C. elegans U1 and U4 snRNAs. Total RNA was treated with either 0, 0.041, or 0.167 M CMCT and subsequently treated with mild base (see Materials and Methods). These samples were used as templates in primer extension reactions using ³²P-end-labeled primers and electrophoresed on denaturing polyacrylamide gels. A portion of the autoradiograph is shown in panel (A) and is the result using primer U1RevB. The same primer was also used to generate the sequencing lanes, using C. elegans U1 pGEMT plasmid as the template, on the right of the panel. The lanes are labeled to correspond to the RNA sequence. In (B) the U4RevB primer was used to determine the positions of Ψ in U4 snRNA using treated RNA samples and a U4 pGEMT plasmid for the generation of the sequence. In this and the subsequent two figures, the arrow to the right of the sequence indicates the position of the Ψ and the arrowhead to the left of the panel indicates a stop to reverse transcriptase that is increased in the CMCT treated lanes. The reverse transcriptase stops just before the modified nucleotide.