Impaired induction of GAL loci in cells deficient in Paf1 or Ctr9. (A) Induction of GAL1 transcripts. Wild-type (HM200), ctr9Δ (HM201) and paf1Δ (HM202) strains were grown at 30°C in YEP supplemented with 2% raffinose. Galactose was added to a final concentration of 2%. RNA was isolated at 0, 5, 15, 30, 45 and 60 min after addition of galactose and GAL1 (upper panels) and ACT1 (lower panels) transcripts were detected by northern blotting (above). The GAL1 signal intensities were normalized to those of ACT1 and plotted as a function of time (below). Filled squares, wild-type; filled triangles, ctr9Δ ; filled circles, paf1Δ. (B) Induction of GAL10 transcripts. Isolates of wild-type (HM200), ctr9Δ (HM201) and paf1Δ (HM202) were grown at 24°C in media indicated above. Galactose was added as described and RNA was isolated at 0, 15, 30, 45 and 60 min after addition. GAL10 (upper panels) and ACT1 (lower panels) transcripts were detected by northern blotting (above). GAL10 signal intensities were normalized as in (A) and plotted together with data obtained from an independent experiment using a second set of wild-type, ctr9Δ and paf1Δ isolates. Filled and open squares, wild-type; filled and open triangles, ctr9Δ; filled and open circles, paf1Δ.