Water bears do not have extensive foreign DNA, new study finds

Water bears do not have extensive foreign DNA, new study finds
Tardigrades have not acquired a significant proportion of their DNA from other organisms, a new study shows. Credit: Aziz Aboobaker and Mark Blaxter

Tardigrades, also known as moss piglets or water bears, are eight-legged microscopic animals that have long fascinated scientists for their ability to survive extremes of temperature, pressure, lack of oxygen, and even radiation exposure.

Now, a study has found that, contrary to a previous controversial proposal, tardigrades have not acquired a significant proportion of their DNA from other organisms.

Instead, new analysis from the University of Edinburgh shows that nearly all of what was proposed to be foreign DNA was simply .

Controversy had been prompted by a November 2015 study suggesting that one-sixth - some 17 per cent - of the DNA of freshwater tardigrades could be traced to transfers from bacteria.

The scientific world was abuzz with speculation following this suggestion that tardigrades had the ability to pick up and reuse DNA from other species.

Soon after, the Edinburgh team used DNA sequence data from the same species and found that almost all of the proposed foreign DNA was in fact contamination.

In their latest study, the same team conducted careful analysis of both sets of data using new computational tools. Their findings suggests that less than 1 per cent of tardigrades' genes are likely to have been borrowed from other species. This number is unsurprising - even humans have a few borrowed genes.

Their study is published in Proceedings of the National Academy of Sciences.

Professor Mark Blaxter, of the University of Edinburgh's School of Biological Sciences, who led the study, said: "What would in decades past have taken many months to sort out became the focus of experts around the world and has been swiftly resolved. We hope this paper will finally correct the scientific record. Tardigrades are amazing organisms, but these suggestions about their DNA were a step too far, even for their eight legs."


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A huge chunk of a tardigrade's genome comes from foreign DNA

More information: Georgios Koutsovoulos et al. No evidence for extensive horizontal gene transfer in the genome of the tardigrade , Proceedings of the National Academy of Sciences (2016). DOI: 10.1073/pnas.1600338113
Citation: Water bears do not have extensive foreign DNA, new study finds (2016, March 28) retrieved 18 September 2019 from https://phys.org/news/2016-03-extensive-foreign-dna.html
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Mar 28, 2016
"wonderfully made".... Yeah, THERE's a scientific assessment. (Eyes rolling).

Mar 29, 2016
Frankly, I'm surprised that the plush toy industry hasn't discovered the cuteness of tardigrades and scientific value to fashion a plush toy that would emulate the tardigrade form. They could include an explanation in the box for kids to read that might encourage future scientists to hunt for tardigrades in their natural habitats. Maybe I'll give Mattel a heads-up call to alert them.
:)

Mar 29, 2016
I guess the term 'wonderfully made' would include factors such as arthritis, birth defects, macular degeneration etc. etc. etc. Thank you god for such a perfect design....
Then there's the fact that we suffer from lung and cardiovascular diseases, as well as backaches, hernias, and choking to death because our throats, lungs, hearts, and vascular systems evolved for tetrapods instead of bipeds; the fact that we have tails we do not require buried above our posterior pelvises, wisdom teeth we do nor require buried in our jaws, and piloerector muscles we do not require buried beneath our skins. All this aside from blind spots in our eyes, male nipples, and muscles to uselessly wiggle our ears.

If someone "made" this kludge, they are so totally incompetent that I would be embarrassed to acknowledge them.

Mar 29, 2016
You forgot to mention your appendix, the part of your digestive system. At sometime in the distant past, there may have been a use for it. But it only gets clogged now and has to be surgically removed. :(

Mar 29, 2016
You forgot to mention your appendix, the part of your digestive system. At sometime in the distant past, there may have been a use for it. But it only gets clogged now and has to be surgically removed. :(
Actually, the appendix apparently serves a useful function: it is a repository for gut bacteria, which are made available at the beginning of the colon to enhance digestion.

But I wouldn't expect you to know enough biology to be aware of that, and I note you apparently are not.

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