Fig. 6. Depletion or inactivation of Rcl1p affects pre-rRNA processing at sites A0, A1 and A2 (A–G and H, lanes 1–8). Northern analysis of pre-rRNAs accumulating in the wild-type strain grown in YPD (lanes 2 and 3) and GAL::rcl1 strain grown either in YPGal (lanes 1) or YPD (lanes 4–8). The following oligonucleotide probes (indicated schematically above the gels) were used: (A) probe a, the 5′ETS upstream of A0; (B) probe b, junction of 5′ETS and 18S rRNA; (C and H) probe c, the ITS1 upstream of A2; (D) probe d, between A2 and A3; (E) probe e, the ITS1 downstream of A3; (F) probe f, the ITS2 upstream of C2; (G) probes g1 and g2, complementary to 18S and 25S rRNA, respectively; (H) lanes 9–12, processing intermediates accumulating in the rcl1-1 ts mutant grown at permissive or restrictive temperature (37°C, 5 h). (I) Primer extension analysis of RNAs accumulating in the GAL::rcl1 strain grown either in YPGal (lane 1) or YPD (lanes 3–7), and in the wild-type strain grown in YPD (lane 2). Oligo g1 was used for primer extension to sites A0 and A1, and oligo f for extension to sites A2, A3 and B1L/S. Positions of primer extension stops corresponding to different pre-rRNA cleavage sites are indicated. The A0 and A1 panels represent different exposures of the same gel.