Posted on 11/28/2015 7:54:46 AM PST by rickmichaels
Everything about tardigrades sounds like a riddle: What creature can survive both freezing and boiling temperatures; you can't see it, but it's everywhere; it can survive outer space; and after being dried up for years, it can reanimate in water within a few minutes?
The answer is just as puzzling: tardigrades, which are also called "water bears" or "moss piglets," are aquatic, microscopic invertebrates that have recently captivated evolutionary biologists and science enthusiasts alike for their unique ability to withstand extreme conditions. There is photographic evidence too that tardigrades are adorable.
Now, researchers at the University of North Carolina at Chapel Hill have found another reason to love the tardigrade - it's a genetic marvel. After sequencing the tardigrade's genome, the team discovered that a whopping 17.5 per cent is composed of foreign DNA. By comparison, the previous record-holder was a microscopic animal called the rotifier, which has half as much foreign DNA; most animals have less than one per cent.
The research, which was published this week in the Proceedings of the National Academy of Sciences, is significant because it demonstrates the potential prowess of "horizontal gene transfer" - the process by which genetic material is traded between unrelated species rather than through parental inheritance. The tardigrade's genome includes DNA from plants, fungi and single-celled micro-organisms called Archaea.
The biologists suspect that when a tardigrade encounters a harsh environment, such as severe dryness, its DNA breaks into pieces; when the cell rehydrates, its membrane and nucleus become "leaky" and DNA from other species can enter it. As tardigrades fix their own DNA, they can incorporate foreign material too. "Animals that can survive extreme stresses may be particularly prone to acquiring foreign genes," says Thomas Boothby, the study's first author. Tardigrades may keep the best ones to enhance their survival.
As horizontal gene transfer becomes more understood, researchers are beginning to rethink the proverbial "tree of life" metaphor for how genes are swapped "vertically" from mother and father to child. "Instead we can think about the web of life and genetic material crossing from branch to branch," says Boothby. "So it's exciting. We're just beginning to adjust our understanding of how evolution works." And tardigrades are proving to be the perfect specimen.
#WaterbearLivesMatter
looks like God did another “gene splice” miracle ...
From
Tardigrades have a huge amount—17.5 percent—of foreign DNA, a new study says.
A team sequenced the genome of a tardigrade species Hypsibius dujardini "to try to understand how it is that some animals can survive some amazingly extreme conditions,†co-author Bob Goldstein, a biologist at the University of North Carolina at Chapel Hill, says via email.
They found the H. dujardini genome is material from several entirely different kingdoms—mostly bacterial (16 percent) but also fungal (0.7 percent), plant (0.5 percent), archaeal (0.1 percent), and viral (0.1 percent).
“We never expected to find that an animal genome would be quite so littered with foreign genes," said Goldstein, whose study was published November 23 in the journal Proceedings of the National Academy of Sciences.
The tardigrade acquires foreign DNA via a process called horizontal gene transfer, in which genetic material is transferred directly between organisms instead of being passed down from parent to offspring.
The discovery of other DNA in the tardigrade is "really peculiar," says co-author Thomas Boothby, also a biologist at UNC.
“Many animals appear to have a small degree of horizontal gene transfer, including humans,†Boothby says. “But nowhere close to the proportion [about one-sixth of genes) that we see in the tardigrade genome.â€
“What this tells us is that instead of thinking about a tree of life, we can start to think more about a web of life, where genetic material from one branch, say the bacterial branch, can cross over to the animal branch.â€
I don’t want to be the one to break the news to honey badger.
Ewwww!!! Thanks
Much appreciated. I understood the highest mountain, deepest ocean bit, just wondered if they are literally everywhere...ie. in my lawn, in my hot tub etc.
Ummmmm.....Maybe it's better that you don't pursue the answer to that question...lol
Even after being completely dried, they can reconstitute themselves with water.
They really need to be active to spot them, so if your hot tub is treated, and there is nothing for them to eat, you probably won't find them...
•Tardigrades are also known as Water Bears, and Moss Piglets
•Tardigrades have been found in Antarctica, 5m below solid ice!
•Tardigrades can withstand 1000x the radiation that a human can!
•Tardigrades can live for over 100 years in cryptobiosis!
•Tardigrades can survive heat for minutes at 151°C or being chilled for days at -200°C, or for a few minutes at -272°C
• Tardigrades can survive in the vacuum of space!
•Tardigrades can survive at pressures 6x greater than those on the ocean floor!
•Tardigrades can survive being boiled in alcohol!
Makes my butt itch.
Thank you for breaking it down. I still have the creeps just reading this, and that picture is stuck in my mind!
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