Slithering Enhancers

Snakes weren't always legless; they evolved the loss of limbs over 100 million years ago and new research from genetics explains why snakes have held on to this limb circuitry through the ages:

"There have been many millions of snake generations since they evolved a legless body, and we would generally expect the DNA associated with limb development to fade away or mutate to do another job, but that doesn't seem to have happened," he said. "Naturally, we wanted to know why snakes had retained DNA that they don't appear to need."

In their experiments, Menke and postdoctoral researcher Carlos Infante examined specific regions of noncoding DNA known as enhancers—a kind of switch that controls the expression of genes, telling them when to turn on or off during embryonic development.

The researchers followed patterns of enhancer activity in embryonic limbs and genitalia of mice and lizards. This revealed that many of the same enhancers are activated during the formation of these different appendages in both species.

DNA sequencing and related technologies are allowing researchers to unlock amazing mysteries of which this is only one. When scientists are able to piece together different aspects of understanding who we are and why, the bigger, whole picture comes that much closer into view. Great work from Menke and Infante in the department of genetics.

Image: Chang Yuchen, Snake (Accordion Book, 2013; etchings on BFK paperaccordion bound, 66 x 48.2 cm