Rpd3p mediates stress-dependent changes in histone acetylation. Changes in nucleosome occupancy (NucOcc) and histone H4 acetylation (H4Ac) at specific nucleosomes (blue bars) spanning representative repressed (green) and induced (red) ESR genes shown in Figure 2 was measured in wild-type, rpd3Δ and pho23Δ cells responding to 0.4 mM H2O2 treatment (see Materials and methods for details). The log2 changes in (a) nucleosome occupancy and (b) fraction of nucleosomes acetylated on H4 following H2O2 exposure is shown for each gene. Error bars represent the range of two replicates for wild type or the standard deviation of at least three experiments for rpd3Δ and pho23Δ. H4 acetylation levels were normalized to levels of nucleosome occupancy to capture the change in the fraction of acetylated nucleosomes. (c) Expression changes of each gene as measured by microarray experiments at 10, 20, 30, 40, and 60 minutes after H2O2 treatment in wild-type, rpd3Δ and pho23Δ cells, according to the key shown.