Where the expressed genes are

Despite widely held beliefs that open and condensed regions of chromatin correlate with active and silent regions of expression, respectively, there is no strict correlation between open chromatin and the activity of a gene, according to a paper in Cell this week. Instead, genes that need to be rapidly activated or switched off are held in regions of open chromatin structure–possibly constraining certain genes to lie within the same genomic region throughout evolution, according to lead author Wendy A. Bickmore of the MRC Human Genetics Unit in Edinburgh.

"Previously, chromatin structures have really only been studied as individual genes, one by one, so we wanted to take a more global approach to ask questions about how chromatin is organized across the whole human genome," Bickmore told The Scientist.

Bickmore's team labelled the DNA from open or closed chromatin by fluorescence in situ hybridization (FISH) so they appeared either green or ...