It looks like a weird alien worm. And it turns out that quite a chunk of its DNA is foreign.
Meet the tardigrade, a nearly indestructible, eight-legged, microscopic worm-like animal that can be found almost anywhere on our planet. They can withstand temperatures of almost absolute zero, survive the radiation of space and extreme pressure.
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New findings published in the Proceedings of the National Academy of Sciences concluded that about 17.5 per cent of a tardigrade’s DNA is foreign. For comparison, the record-holder for foreign DNA had been the rotifer — and it has half as much. And typically, most animals just have about one per cent foreign DNA.
Knowing how strange this creature was, perhaps it shouldn’t have come as a surprise.
“We had no idea that an animal genome could be composed of so much foreign DNA,” co-author of the paper Bob Goldstein said. “We knew many animals acquire foreign genes, but we had no idea that it happens to this degree.”
It turns out that the tardigrade gets about 6,000 foreign genomes from bacteria, in a method that is called horizontal gene transfer. So instead of you getting your DNA from your parents you get it from another species. Which might explain its unique talents.
“Animals that can survive extreme stresses may be particularly prone to acquiring foreign genes — and bacterial genes might be better able to withstand stresses than animal ones,” said one of the paper’s authors, Thomas Boothby.
Though it’s not clear how this happens, the authors believe that when the tardigrade lives in areas of extreme stress, such as a very dry area, their DNA breaks up. Once rehydrated, it picks up the DNA through the cell’s membranes and nucleus. So now the tardigrade, which has survived the extreme conditions, repairs itself and also mixes in the foreign DNA — a pretty neat trick.
Now if only we could create a super hero with this ability.
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