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Water bear genome mostly uncontaminated by foreign DNA

Only 1 percent of the water bear's DNA has been borrowed from others.

By
Brooks Hays
New research suggests tardigrades, or water bears, don't possess much foreign DNA. Photo by Aziz Aboobaker and Mark Blaxter
New research suggests tardigrades, or water bears, don't possess much foreign DNA. Photo by Aziz Aboobaker and Mark Blaxter

EDINBURGH, Scotland, March 28 (UPI) -- A 2015 study found as much as 17 percent of the tardigrade's genome was comprised of foreign DNA, but new research suggest those foreign fragments were the result of bacterial contamination.

The DNA of tardigrades, or water bears, is relatively pure, scientists at the University of Edinburgh say.

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The original findings created considerable buzz in the scientific community and the media, as they suggested water bears possessed the ability to commandeer genetic fragments from other species.

Edinburgh scientists reanalyzed the data from the original study using complex computational tools and found only 1 percent of the water bear's DNA has been borrowed from others. Most species feature a small percentage of foreign DNA.

"We independently sequenced the genome of Hypsibius dujardini and detected a low level of horizontal gene transfer," researchers wrote in journal PNAS. "We show that the extensive horizontal transfer proposed by Boothby et al. was an artifact of a failure to eliminate contaminants from sequence data before assembly."

Tardigrades have fascinated scientists for many years. The tiny organisms can withstand extreme conditions -- extreme heat and cold, low oxygen levels, intense pressure, ultraviolet radiation.

Earlier this year, researchers reported the successful reproduction of a water bear that had been frozen for 30 years.

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