Deletion of CTR9 or PAF1 impairs displacement of histones from the GAL1 locus upon induction. Wild-type (HM200), ctr9Δ (HM201) and paf1Δ (HM202) strains were grown at 24°C in YEP supplemented with 2% raffinose. Galactose was added to a final concentration of 2%. Nuclei were isolated at 0, 10 and 90 min after induction and digested with 0, 7, 15, 50 or 100 U of micrococcal nuclease. (A) Micrococcal nuclease digests of nuclei from wild-type (left), ctr9Δ (middle) and paf1Δ (right) strains were deproteinized and fractionated by agarose gel electrophoresis; DNA was detected by ethidium bromide staining. Inverse images of the stained gels are shown. Positions of markers and their sizes (in kb) are indicated at left. (B) Distribution of micrococcal nuclease digestion products at the GAL1 locus. DNA from gels in (A) was transferred to nylon and hybridized to a probe representing basepairs +422 to +925 of the GAL1 gene. Signal was detected by phosphorimaging. (C) Distributions of micrococcal nuclease products from the 50 U micrococcal nuclease reactions in (B) were quantified by densitometry for each strain at each time point. The signal intensities are plotted in arbitrary units.