Genetics: The Mod Squad.

The article focuses on the research on different combinations of chemical modifications that affect the expression of almost 12,500 genes in CD4⁺T cells conducted by Keji Zhao of the U.S. National Institutes of Health in Bethesda, Maryland and his colleagues. It states that section of its DNA that a cell expresses lies in part on chemical modifications to the histone proteins around which DNA is wound. The authors discovered that a set of 17 chemical modifications is associated with a quarter of all promoters in human immune cells. However, acetylation does not directly determine whether a gene is "read," as had been surmised, but appears to prime the gene for activation.