Abstract

Spatial organization inside the nucleus In eukaryotic cells, DNA is packaged into a complex macromolecular structure called chromatin. Wang et al. have developed an imaging method to map the position of multiple regions on individual chromosomes, and the results confirm that chromatin is organized into large contact domains called TADS (topologically associating domains). Unexpectedly, though, folding deviates from the classical fractal-globule model at large length scales. Science , this issue p. 598