Inactivation of Cic1p/Nsa3p inhibits growth and rRNA synthesis. (A) Growth rate of cic1–2 (open squares) and wild-type (closed diamonds) strains following a shift from permissive to restrictive temperature. (B, C) Strains cic1–2 and wild type were growth at 25°C in YPD then shifted to 37°C for 4 h. Cell were pulse labeled with [5,6-3H] uracil for 1 min and then chased with an excess of cold uracil. Total RNA was extracted from cell samples harvested at the indicated time points and resolved on a 1.2% agarose/formaldehyde (B) and 6% acrylamide/urea gels (C). The position of mature rRNAs, pre-rRNAs, and tRNA species are indicated. Incorporation of [5,6-3H] uracil in the mutant strain was lower than in the wild type, and a twofold longer exposure of these lanes is shown.
