Cover image

The changes in the 3D organization of chromatin after differentiation in Drosophila cell lines are illustrated. Topologically associating domains (TADs; represented by yellow pyramids) are associated with both divergent transcription at their borders (represented by taller ancient Egyptian men pointing to the direction of transcription) and active transcription by RNA polymerase II (represented by working men in white loincloths). In embryonic cells (top row), the TAD borders are separated by an architectural protein called BEAF-32 (represented by ibis birds). Upon differentiation in neuronal cells (middle row), BEAF-32 is reduced and replaced by CTCF (represented by Sphynx cats), leading to only a subset of TAD borders being maintained and the appearance of larger TADs (bottom row). (Cover artwork by Liudmila Mikheeva, lm17047{at}essex.ac.uk. [For details, see Chathoth et al., pp. 613–625.])