Figure 6.
Effect of RNAi-mediated ablation of Pol-II and Pol-III activities on steady state levels of different RNAs. (A) Growth of uninduced and induced procyclic T. brucei RNAi cell lines downregulated for RPB9 (30) or the largest subunit of Pol-III. Inset: downregulation of the mRNA encoding the largest subunit of Pol-III was verified by northern blot analysis 24 h after induction of RNAi. (B) Northern analyses of total RNA isolated from uninduced (0) and induced (24, 48 h) RPB9 and Pol-III RNAi cell lines. RNA was resolved in 8 M urea on a 10% polyacrylamide gel and hybridized with oligonucleotides specifically detecting the transcripts indicated on the right. The tRNA region of the corresponding ethidium bromide stained gel is shown at the bottom. (C) Quantitation of the northern blots shown in (B). Signals were normalized to the cytosolic M6 rRNAs not affected by ablation of either RPB9 or Pol-III. For tRNASec and tRNAIle the means of three experiments are shown. The signal in the uninduced cells was set to 1. Standard errors and the relevant P-values (Student’s t-test, one-tailed, paired) are indicated.