Do nuclear dot-like RNA signals correspond to single RNA molecules?
The structural organisation of Bsr punctuated signals is puzzling. They might correspond either to clusters of multiple spliced Bsr RNAs in an unknown nuclear structure, or they might be single RNA molecules diffusing through the nucleoplam. To distinguish between these two possibilities, the number of hybridized Cy3-labelled spliced-probes within 285 individual nuclear dots in 8 different nuclei was quantified by using the method described in (Femino et al., 1998), see also below). We reasoned that a large number of probes (i.e. largely exceeding 85, the largest theoretical number of hybridized probes) will formally exclude the single RNA molecule hypothesis. We found that 48% of the nuclear dots do not contain more than 10 probes, with a range of 1 to 124 probes hybridized per dot. These results are consistent with the notion that each nuclear dot might represent a single (or a few) RNA molecule(s). Fluorescence signal quantification method. Digital images from a series of 10 to 14 f
