Scientists have discovered a new DNA modification system in animals. Previously, it was known only in bacteria, bdelloid rotifers, and small freshwater animals.

Scientists have discovered a new DNA modification system in animals, they got it from bacteria more than 60 million years ago.

According to the authors, human DNA contains the blueprint for building the body. But this information is unstable, it can be changed using epigenetic marks.

Epigenetic marks—chemical groups that turn genes on and off—allow the body to produce more than 200 types of cells using the same genetic code. Epigenetic marks usually regulate gene expression—turn genes on or off, especially early in development or when the body is under stress.

In humans and other eukaryotes, two major epigenetic marks are known, and a third has now been discovered.

We discovered back in 2008 that bdelloid rotifers are very good at picking up foreign genes. Now it turns out that rotifers, about 60 million years ago, accidentally picked up a bacterial gene that allowed them to introduce a new epigenetic mark. This is the first time that a horizontally transferred gene alters the gene regulation system in eukaryotes.

Irina Arkhipova, Senior Fellow at the Josephine Bay Paul Center at MBL.
In other words, a piece of bacterial DNA accidentally merged with a piece of eukaryotic DNA. Both joined in the rotifer genome and formed a functional enzyme. It’s not that easy to do, even in the lab. This complex enzyme then created a new regulatory system.

Researchers are now trying to understand how this new property can be exploited.