= Solution
The structural implication is a spectrum of arrangements, not a universal regular fibre. Local <nucleosome> packing, irregular accessible chains, compact domains and interactions between differently modified regions can coexist, and their balance depends on preparation and cellular context. <Nucleosome breathing> changes the sites available for intermolecular contacts and hence the connectivity of an array assembly; it is not merely a uniform change in the size of a rigid bead.<Nucleosome plasticity is a critical element of chromatin liquid-liquid phase separation and multivalent nucleosome interactions by Stephen E. Farr and others>[Comparison of breathing and artificially constrained nucleosomes]{ref}
Reconstituted-array experiments separate contributions that are difficult to disentangle in nuclei. Fluorescent arrays, microscopy, droplet fusion and molecular exchange measurements test condensation and dynamics; changing tails, linker organization or acetylation tests the interaction mechanism. <Bryan A. Gibson> and colleagues found that <histone H1> and <nucleosome> spacing modulate condensation, while acetylation and reader <proteins> can produce different condensed states.<Organization of Chromatin by Intrinsic and Regulated Phase Separation by Bryan A. Gibson and others>[Reconstituted arrays and regulation of condensate properties]{ref}
In cells, combine imaging with contact maps and accessibility assays. <Hi-C> can reveal preferential contacts and <chromatin compartments>, but does not establish liquid behaviour. <Fluorescence recovery after photobleaching> measures recovery kinetics, but recovery alone does not prove equilibrium liquid-liquid demixing. Conversely, an in-vitro droplet is not proof that every nuclear domain forms by the same mechanism. The strongest case combines material behaviour with controlled molecular perturbations and measurements of the resulting organization.
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