Figure 6. Schematic drawing showing the main structural elements of two layers in close contact.

Only a few nucleosomes are shown to illustrate the main dimensions and the interdigitation of two layers. Our results suggest that the two turns of the nucleosomal DNA are oriented slightly tilted with respect to the axis normal to the plate surface, but they may have diverse orientations (not represented in this scheme) with respect to the other two axes of the plate. The thickness of single‐ and double‐layer plates (~ 7.5 and ~ 13 nm, respectively) obtained from cryo‐tomograms (Table 1) is indicated in blue. The main scattering peak at ~ 6 nm observed in SAXS experiments with condensed chromosomes under metaphase ionic conditions (Fig 5B) is probably due to the repetitive distances between nucleosomes (face‐to‐face interactions) and between stacked layers; these distances (~ 6 nm) are indicated in red.