Figure 5.

Visualized local densities for a fibroblast cell (A) and a HeLa cell of strain I (B). Shown are the densities of blocks of linear dimension b = 500 nm. They display strong deviation from a random distribution, indicating that structure in the histone distribution exists on that scale. (C) Block density distributions, P(ρ/ $\langle \rho \rangle$), for different values of block size b = 200 nm (squares), b = 500 nm (circles), and b = 1000 nm (triangles). Data are scaled with the average density, $\langle \rho \rangle$, to make the distribution independent of labeling efficiency. (D) The cumulants, U_b (Eq. 3), of the density distribution. For a thermodynamically equilibrated system, cumulants should display a value of zero (dashed line) above a block size b larger than the scale of density fluctuations.