Figure 3.

Paradigm shifts in chromatin organization. Fluorescent in situ hybridization experiments (Figure 6) on chromosomes in the 1990s suggested that DNA conformations in interphase chromosomes behave like random polymer coils at equilibrium. Chromosome conformation capture (specifically Hi‐C data at 1 Mb resolution) suggested in 2009 that the chromosomes are in a metastable polymer state, the fractal or crumbled globule. In addition, it mapped 2 sub‐compartments (indicated here by colors). More recently, Hi‐C experiments at 1 kb resolution point toward a loopy globule state, a steady state maintained by the continuous action of molecular motors called loop extrusion complexes. About 6 different sub‐compartments have been identified (3 of which are indicated here by colors, see main text for details)