A Significant Finding?

New nucleotide could revolutionize epigenetics is a EurekAlert article discussing work accomplished by Nathaniel Heintz's Laboratory. Quoting from the first paragraph:

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 (5-mC), that sometimes replaces cytosine in the famous DNA double helix to regulate which genes are expressed. And now there's a sixth. In experiments to be published online Thursday by Science, researchers reveal an additional character in the mammalian DNA code, opening an entirely new front in epigenetic research.

The author notes that the DNA methylation process involves targeting sites where cytosine precedes guanine in DNA. The enzyme DNA methyltransferase attaches a methyl group to cytosine and in doing so generates a distinct nucleotide called 5-methylcytosine. The process is linked to gene silencing.

An interesting feature of methylation is the effect the environment has on methylation patterns which can be inherited.