The effect of heat shock on nucleosome positioning. (A) Kernel density plot showing the distributions of +1,+2,+3, and +4 nucleosome dyads at the downstream of TSS before and after heat shock. Red lines show the centre of nucleosome distributions in heat shocked cells, and blue lines show that of in normally growing cells, respectively. The arrows indicate the distribution changes after heat shock at the stable equilibrium points. (B) Bar graph depicting the average sliding distances of positioned-nucleosomes after heat shock. Genes are divided into two groups according to their responding to environmental stress. Red bar presents nucleosome sliding range at the activated promoters, green bars show nucleosome sliding range at all promoters, and blue bars show nucleosome sliding range at the repressed promoters . (C), (D) The average distances between the nucleosome dyads and correspondingly stable equilibrium points at the two classes of promoters before and after heat shock. Blue bar indicates nucleosomes in normally growing cells, and red bar indicates nucleosomes under heat shock. All error bars were calculated by bootstrapping. (The stable equilibrium points : -559, -393, -228, +60, +225, +392, +559 and +725 bp relative to TSS).