Nature has the details on what it takes to come back from a decapitation:
Knocking out a single gene can switch on a worm’s ability to regenerate parts of its body, even enabling it to grow a new head. The fact that such a simple manipulation can restore healing abilities provides new insight into how the stem cells involved in this process are marshalled in animals.
Scientists already knew that the Wnt genes are expressed in a gradient along the worms’ bodies — from high at the tail to low at the head — and suspected that the genes were involved in directing stem cells during healing. In the latest studies, researchers wanted to find out if a lack of Wnt gene expression was responsible for the poorer regenerative abilities in particular worm species.
To explain the disparity, Jochen Rink, a molecular biologist at the Max Planck Institute of Molecular Cell Biology and Genetics in Dresden, Germany, sliced a worm called Dendrocoelum lacteum at different positions along its body. He and his team then sequenced RNA from the various wounds1. The researchers found that, in wounds that did regrow heads, genes coding for a series of enzymes involved in the Wnt pathway had their expression turned up. But in the pieces that couldn’t regrow, the Wnt genes “didn’t even twitch”, Rink says.
But perhaps most surprisingly, both teams found that by suppressing a gene that regulated Wnt function in their flatworms, they could get chunks of the normally non-regenerative tissue to grow fully functional heads.
“This is a fantastic advert for our field,” says Aziz Aboobaker, a biologist who studies planarian worms at the University of Oxford, UK, but was not involved in any of the studies. “Here’s a scenario where these animals don’t regenerate a brain, and then by knocking out just one gene, it’s possible to rescue that.”
One gene. Knock it off, and suddenly – regeneration happens.