New Nucleotide In DNA Could Revolutionize Epigenetics

Anyone who studied a little genetics in high school has heard of adenine, thymine, guanine and cytosine -- the A,T,G and C that make up the DNA code. But those are not the whole story. The rise of epigenetics in the past decade has drawn attention to a fifth nucleotide, 5-methylcytosine, that sometimes replaces cytosine in the famous DNA double helix to regulate which genes are expressed. And now there's a sixth: 5-hydroxymethylcytosine. Biologists reveal an additional character in the mammalian DNA code, opening an entirely new front in epigenetic research.