Polymer models of chromatin organization

The exploration of the spatial organiza-tion of chromosomes in the cell nucleushas been greatly enhanced by genome-scale technologies such as Hi-C methods.Polymermodels arehelpingto understandthe new emerging complex scenarios andhere we review some recent developments.In the cell nucleus of eukaryotes, chro-mosomes have a complex spatial organi-zation serving vital functional purposes,with structural disruptions being linkedto disease (Fraser and Bickmore, 2007;Lanctot et al., 2007; Misteli, 2007; Pomboand Branco, 2007). The development oftechnologies such as Hi-C ( Lieberman-Aiden et al., 2009) has opened the wayto mapping chromatin interactions ata genomic scale. It is emerging thatchromosomes tend to form 1Mb sizeddomains with increased levels of intra-interactions (known, e.g., as TopologicalDomains, TDs) (Dixon et al., 2012; Noraet al., 2012), but contacts extend acrossentire chromosomes (Branco and Pombo,2006; Shopland et al., 2006; Fraser andBickmore, 2007; Kalhor et al., 2011;Sexton et al., 2012), as highlighted bythe average contact probability of twosites,