Figure 8.

The U2 locus RNA accumulation contains preU2. Cohybridizations with the U2 4.3-kb probe (green) and preU2 (red) or preU2 opposite-strand (red) oligonucleotide probes in HeLa cells (column A) and WI38 fibroblasts (columns B and C). In the HeLa cells, preU2 signal (red) detects CBs and fainter signals (arrows) overlapping the RNA foci detected with the U2 4.3-kb probe (green). WI38 fibroblasts do not have CBs but show a similar overlap of preU2 signal with U2 4.3-kb signal. The preU2 opposite-strand probe does not produce a signal above background. (Row D) 3′ noncoding oligonucleotide probe (red) that hybridizes to a region 27 nucleotides downstream of the end of the preU2 sequence produces a signal that overlaps the RNA focus seen with the 4.3-kb U2 probe (green) but does not overlap CBs (blue). See Figure 5 for sequences and positions of oligonucleotide probes.