Evolutionary wrench: Comb jelly discovery may add new branch to tree of life
Genetic research into these odd creatures could reveal treatments for Alzheimer's, Parkinson's and other neurological disease.
Thu, May 22, 2014 at 03:23 PM
There's no need to look to the skies for alien life. According to University of Florida neurology researcher Leonid Moroz, aliens already exist here on Earth. They're not little green men, though — they're little oceanic creatures made of jelly. Known as jelly combs or ctenophores, these species have unique genetics that set them apart from all other life in the planet. "I can honestly introduce you to the aliens of the sea," Moroz said in a news release this week.
Jelly combs look odd to the naked eye, but what sets them apart on a genetic level? According to research published this week in the journal Nature, a project to map out the ctenophore genome has revealed that they have neurologic, immune and development genes different from every other animal genome. This discovery effectively rewrites some of the understanding of evolution.
"Our concept of nature was that there was only one way to make a neural system," Moroz said. "We oversimplified evolution. There is more than one way to make a brain, a complex neural circuit and behaviors."
Previous research has revealed that most animals carry the same genes to control brain activity. The 10 comb jelly species examined by the researchers either lack these genes or they aren't turned on. Unlike other species, the jellies don't use serotonin, dopamine, acetylcholine or the other typical neural transmitters that control brain activity. Instead they use neurochemical systems, which is unlike any other group of species.
As if this weren't a big enough discovery, the researchers found that comb jellies have an amazing ability to regenerate their brains – not just once but multiple times. "Some ctenophores can regenerate an elementary brain — also known as the aboral organ or gravity sensor — in three-and-a-half days," Moroz said. "In one of my experiments, one lobate ctenophore, Bolinopsis, regenerated its brain four times."
The researchers say that further research into this regenerative ability could lead to new ways to research human neurodegenerative diseases such as Alzheimer's or Parkinson's. Current treatments can only slow or stall such conditions. But Moroz asks, "What if we could not only slow the progressions of Parkinson's or memory loss in aging, but reverse it?"
As for the evolution aspect, Moroz and his fellow researchers wonder if ctenophores should now belong on a new branch of the tree of life, one that would have broken off from all other species at some of the earliest evolutionary stages.
Although there's still more research required to fully understand these unique organisms, Moroz sums up the research pretty well: "Nature is much more innovative than we thought."
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