Some animals have the extraordinary ability to regrow limbs after amputations, others, even more impressively have the ability to perform whole-body regeneration. New research from Harvard has uncovered some of the genetic secrets to animals capable of this incredible process.
The scientists have discovered a number of DNA switches that appear to control genes used in full body regeneration. Animals like salamanders can regrow a limb after it has been amputated, geckos can regrow their tails.
DNA key to regeneration ability
Other animals like Planarian worms, jellyfish, and sea anemones can actually regenerate their bodies after being cut in half. To understand how these animals perform such incredible feats of growth the Harvard researchers examined the DNA of these fast-growing creatures.
To test their theory the researcher's particular three-banded panther worms. They found that a section of noncoding DNA in the worms controls the activation of a “master control gene” called early growth response, or EGR.
Worms possess a genetic 'main switch'
The study shows that once this gene is activated it controls a number of other processes by switching other genes on or off. The research was led by Assistant Professor of Organismic and Evolutionary Biology Mansi Srivastava and Andrew Gehrke, a postdoctoral fellow.
“What we found is that this one master gene comes on [and activates] genes that are turning on during regeneration,” Gehrke said.
“Basically, what’s going on is the noncoding regions are telling the coding regions to turn on or off, so a good way to think of it is as though they are switches.”
Gehrke goes on to explain that for the process to work the DNA in the worms’ cells, has to change from its normally tightly folded and compact shape into something more open, with space available for activation.
“A lot of those very tightly packed portions of the genome actually physically become more open,” he said, “because there are regulatory switches in there that have to turn genes on or off.
So one of the big findings in this paper is that the genome is very dynamic and really changes during regeneration as different parts are opening and closing.”
Big step for biology
To fully understand the amazing attributes of the worm's genome, the hard-working researchers had to sequence it - a challenging task in itself. “That’s a big part of this paper,” Srivastava said.
“We’re releasing the genome of this species, which is important because it’s the first from this phylum. Until now there had been no full genome sequence available.”
Releasing the genome is an important step in the world of biology, because this particular worm represents a new model system for studying regeneration.
“Previous work on other species helped us learn many things about regeneration,” she said.
“But there are some reasons to work with these new worms.” For one thing, they’re in an important phylogenetic position.
“So the way they’re related to other animals … allows us to make statements about evolution.”
The other reason, she said, is, “They’re really great lab rats. I collected them in the field in Bermuda a number of years ago during my postdoc, and since we’ve brought them into the lab they’re amenable to a lot more tools than some other systems.”
Their study shows that EGR acts like a mains power switch for regeneration. Once it's turned on a multitude of complex processes can occur, but without that first singular switch, nothing happens.
The research doesn’t only reveal why worms these worms have this incredible ability, it also shows us why we, humans, can't regrow ourselves or even a simple limb.
The scientists will continue their research into how the EGR works and how understanding its implications can open doors to further research into regeneration.