Last week’s excitement about the discovery of “seventh” and “eighth” DNA bases might’ve obscured parts of that work that shed a little more light on a very murky corner of epigenetics’ cytosine modifications — “Where do the methyls go?” And related research also published last week gets a bit closer to answering, “What does 5-hydroxymethyl-C really do, anyway?” The first, a Science paper by Yi Zhang and his group at the University of North Carolina, does introduce two new cytosine modifications, 5-formylcytosine and 5-carboxylcytosine. But more interesting, I think, is that the group gets halfway through proving a plausible mechanism for cytosine demethylation, which no one’s demonstrated yet. And during the same week, researchers at UCLA and New England Biolabs … Continue reading →