Researchers Discover Extra DNA Base

Adenine, guanine, cytosine, and thymine. How these four DNA bases are ordered determines the makeup of a genome. And now, researchers have discovered an extra DNA base, called 5-Formylcytosine, or 5fC. They’re not sure what it does just yet, but it’s stable in every living tissue in the bodies of mice. The findings were published in Nature Chemical Biology this week.

In addition to the familiar A, G, C, and T, there are also many small chemical modifications to DNA that affect how sequences are interpreted. These are known as epigenetic marks, and they can control when certain genes are switched on or off. For example, when methyl groups – a chemical tag with one carbon and two hydrogen atoms – were added to a particular gene in ants, researchers doubled their size. In humans, babies born to mothers who smoke show epigenetic changes that aren’t seen in the babies of nonsmokers.

First discovered in 2011, 5fC is one of these marks. It’s formed when enzymes add oxygen to methylated DNA, specifically DNA with methyl attached to cytosine. But at the time, researchers thought that 5fC was just a transitional state of cytosine, which was being removed by repair enzymes. As it turns out, 5fC isn’t temporary: It’s stable in living tissue, which means that it likely plays an important role... read more>>>...