Evidence for a conserved topologically associated domain (TAD) spanning the Hox gene cluster across Lepidoptera. (A) Species tree of nine representative lepidopteran species on left; Hi-C matrix showing 1 Mb either side of the Hox gene cluster (excluding lab). The location of the Hox gene cluster from (Abd-B to pb) is annotated by a blue bar, along with its orientation. The position of ro is annotated with a short vertical black dash. The intensity of chromatin compaction is represented by a blue (low) to red (high) color gradient. Across the core Hox cluster (pb to Abd-B) in each species a TAD is represented by a region of strong contact, by the more-yellow-shaded regions. Black lines represent TADs or sub-TADs predicted by HiCExplorer. (B, top) The arrangement of the Hox gene cluster (excluding ro and lab) surrounded by a TAD (orange) in Pheosia gnoma (lesser swallow prominent). (Bottom) The Hi-C matrix of Chromosome 10 showing the location of the Hox cluster, represented by a blue bar, along with ro and lab, represented by short vertical black dashes. (C) Schematic showing tologically folded domains in Chromosome 10 (red) interspersed by chromosome regions with less consistent topology (blue) based on the above Hi-C matrix. Shaded gray region shows the location of the condensed TAD containing the Hox cluster.
