FIGURE 7.

The conserved motif of vertebrate Y RNAs is required chromosomal DNA replication in vivo. (A) Quantification of replicating S phase cells after control RNA interference (RNAi) against a nontarget RNA, firely luciferase mRNA. (B) Quantification of replicating S phase cells after RNAi against hY3 RNA. Two hours after transfection of asynchronously proliferating HeLa cells with a control or an hY3 specific siRNA (siRNA hY3c) (Christov et al. 2008), 100 nM of the indicated wild-type and mutant Y RNAs were transfected into the same cells. At 23 h after RNAi, replicating cells in the population were labeled with BrdU for 1 h. At 24 h, percentages of S phase cells incorporating BrdU into their chromosomal DNA were determined by immunofluorescence microscopy. Mean values and standard deviations are shown for n = 3 independent experiments. Similar results were obtained with the independent siRNA hY3b (Christov et al. 2008) (data not shown).