Researchers from Harvard shed new light on the enigma of how there are animals that are able to regenerate their entire bodies, and explained why, despite the existence of the genes, the ability to regenerate in vertebrates, including humans, is limited
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When it comes to regeneration, some animals are capable of amazing things. If we cut off a salamander's leg, it will grow back. When threatened, some species of geckos drop their tails to distract the predator, and later regrow them.
Other animals take the process even further. Some types of worms, jellyfish and sea urchins can actually regenerate their entire bodies after being cut in half.
A team of Harvard researchers led by Andrew Gehrke and led by Professor of Organismic and Evolutionary Biology Mansi Srivastava has shed new light on how animals pull off the feat, uncovering several DNA switches that appear to control genes for whole-body regeneration . The research is described in an article published on March 15 in the journal Science.
The researchers examined worms from the three-striped panther worm species, and discovered that a piece of non-coding DNA controls the activation of a "master control gene" that the researchers called "early response to growth", or EGR. After the genes are activated, EGR controls several other processes by turning other genes on or off.
For the process to work, Gerke said, the DNA in the worm's cells, which is normally folded and compacted, must change, making new regions of it active.
"Many, many well-packaged parts of the genome can be more open because there are regulatory switches that turn the genes on or off." said. "So one of the big findings in this paper is that the genome is very dynamic and really changes during regeneration when different parts open and close."
But before Gerka and Sryastava could understand the dynamic nature of the worm's genome, they had to sequence it. This tiling formed a large part of the article. "We are releasing the genome of these species, which is important because this is the first of these worms," said Srivastava. "Until now, no complete genome sequence was available." Thus the panther worms can now be used as a new model to study regeneration.
"Previous work on other species helped us learn a lot about regeneration," he said. "But there are several reasons to work with these new worms, one of which is that they are in an important phylogenetic position, so the way they are related to other animals allows us to draw conclusions about evolution.
The results showed that EGR acts like an on-off switch for regeneration - once it is turned on, other processes can occur, but without it, nothing happens. We were able to reduce the activity of this gene in the worms and discovered that when it is turned off, the worms are simply unable to regenerate." says Gerka.
While the research reveals new information about how the process works in worms, it may also explain why it doesn't work in humans. "It turns out that RGR, the master gene, and the other genes are found in most species that evolved after worms, including humans," Gerka said. "When you put human cells in petri dishes and apply mechanical pressure to leaves or poison them they will express EGR immediately."
"The question is, can humans activate EGR when our cells are injured? What prevents us from renewing? Sriastava asked. "The answer could be that if EGR is the ignition switch, we think the wiring is different. What EGR controls in human cells may be different from what it controls in the panther worm. We want to understand what these relationships are, and then examine how the phenomena occur in other animals, including vertebrates whose regenerative capacity is more limited."
for the scientific article
For a statement from Howard University
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