Retrovirus found to be a key player in ancient myelination -- LL

 https://www.sciencenews.org/article/ancient-retrovirus-myelin-speedy-nerves-evolve 

Retrovirus found to be a key player in ancient myelination

Research shows that an ancient retrovirus helped activate the production of a protein encoding myelin. Myelin helps insulate nerve fibers, and is a coating of fat and protein which protects axons, which may have increased the complexity and speed of the brain. These coated nerves also allowed fibers to grow thinner and longer, which may have contributed to an augmentation in the size of animals. The retrovirus is embedded in the DNA of jawed vertebrates. Retroviruses are RNA viruses that embed themselves in the DNA of cells, meaning they can occasionally (albeit rarely) become part of the genetic material passed down from generation to generation. 

The researchers were able to make this connection since they found high levels of the retrovirus in cells that compose myelin. Though the RNA (dubbed RetroMyelin) from the retrovirus doesn’t directly code the information for making myelin, it latches on to a protein that starts myelin production. Furthermore, when quantities of RetroMyelin were reduced in jawed vertebrates, the production of myelin dropped.

-LL