Fig. 8: Proposed model for chromatin density and organization.

Dark regions in the left panel represent chromatin sparse regions (green box). Nucleosomes in these regions form small clusters that are separated by nucleosome free regions and are more mobile than nucleosomes in denser chromatin regions. Their motion can be explained by a combination of passive diffusion and an active stabilizing component due to gene transcription. Bright regions in the left panel represent chromatin dense regions (gray box). Nucleosomes in these regions are more randomly organized and display less motion than those in chromatin sparse regions. Their motion can predominantly be explained by passive diffusion. The diffusion of inert particles (magenta) in the nuclear interior is not affected by the local chromatin density (right column) or perturbations to transcription. Nucleosomes at the nuclear periphery (blue box) display distinct dynamics and organization from the nuclear interior. Nucleosome motion is more constrained but unaffected by local chromatin density. The diffusion of inert particles (magenta) at the nuclear periphery is affected by local chromatin density.