Editing Epigenetics (section)

===Nucleosome positioning===
Eukaryotic genomes have numerous [[nucleosomes]]. Nucleosome position is not random, and determine the accessibility of DNA to regulatory proteins. Promoters active in different tissues have been shown to have different nucleosome positioning features.<ref>{{Cite journal| vauthors = Serizay J, Dong Y, Jänes J, Chesney M, Cerrato C, Ahringer J |date=2020-02-20|title=Tissue-specific profiling reveals distinctive regulatory architectures for ubiquitous, germline and somatic genes |journal=bioRxiv |pages=2020.02.20.958579|doi=10.1101/2020.02.20.958579|s2cid=212943176|doi-access=free}}</ref> This determines differences in gene expression and cell differentiation. It has been shown that at least some nucleosomes are retained in sperm cells (where most but not all histones are replaced by [[protamines]]). Thus nucleosome positioning is to some degree inheritable. Recent studies have uncovered connections between nucleosome positioning and other epigenetic factors, such as DNA methylation and hydroxymethylation.<ref name=Teif_2014>{{cite journal | vauthors = Teif VB, Beshnova DA, Vainshtein Y, Marth C, Mallm JP, Höfer T, Rippe K | title = Nucleosome repositioning links DNA (de)methylation and differential CTCF binding during stem cell development | journal = Genome Research | volume = 24 | issue = 8 | pages = 1285–95 | date = August 2014 | pmid = 24812327 | pmc = 4120082 | doi = 10.1101/gr.164418.113 }}</ref>