Figure 5. Chromosomal interfaces.

a, All trans-chromosomal contacts formed by chromosome 2 in real cells (blue) and reshuffled (red). b, Schematic diagram of a chromosomal interface between linearly adjacent domains, their borders marked in black on two chromosomes, A and B. We considered each of the two contacting fragments of every trans-chromosomal contact and classified every nearby trans-chromosomal contact as domain-domain, domain-chromosome and chromosome-chromosome, the latter being used as background for normalisation (Supplementary Information). Contact under consideration (red), nearby contacts (blue). Fold enrichments shown for each group type (error bars, standard deviation). c, Trans-chromosomal contacts are highly significantly enriched between active domains (H3K4me3 enriched) or between inactive domains, but not mixed interaction (chi-square test; p = 5.8e-18; even after taking account of the generally higher connectivity of active domains). d, Bar graph depicting mouse autosomes ordered by size with number of interacting chromosomes per single cell (black circles depict the distribution over individual cells). Mean number of interacting chromosomes changes modestly (30%) with chromosome size, suggesting a highly organized territory structure with surface that is not scaling with chromosome length.