Traditionally, the study of gene transcription views the nucleus as "molecular machines", and thus primarily focuses on specific gene sequences with a "loci-by-loci" basis. However, the chemical reactions are not taking place in dilute solutions. Quite contrarily, these chemical reactions occur in a high compacted region inside the nucleus. Besides the molecular composition of a gene sequence, the location of this gene on the chromatin also plays a crucial role in the accessibility of this

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... fic gene. It is known that chromatin structure spans across multiple length scales [1] , and the regulation of gene expression by chromatin structure not only relies on the sequence binding motifs, but also on the local environment.