Right on the heels of previous research that suggested that water bears, also known as tardigrades, are "gene borrowers" that gained 17 percent of their genes from bacteria and other organisms, a new study, conducted by University of Edinburgh scientists, found that foreign genes account for less than 1 percent of their genome, according to Science News.
"We said, 'This is so different from our assembly, something must be wrong,'" said Mark Blaxter, who headed the research.
Blaxter and his team compared the raw data from the previous study to the data that they pieced together on the water bear genome and concluded that the bacterial DNA in their genome mostly stems from contamination, which is completely different from actual gene swapping, or horizontal gene transfer. Furthermore, they claim that approximately 30 percent of the DNA in the previous study's water bear genome could stem from contaminants.
Bob Goldstein and Thomas Boothby, who conducted the previous research that reported the high percentage of foreign DNA, claim that the new findings are cause for concern, although they were not aware that contamination affected their results.
"We thought seriously about the possibility of contamination - it was of course the most likely initial explanation for the large amount of foreign DNA found in our assembly - and much of the analysis in our paper was designed specifically to address this issue," they said in a written comment on Blaxter's study.
"Our conclusion is that the Goldstein lab did the right set of tests, but didn't apply them rigorously enough," Blaxter added.
Further research will need to be conducted to determine which set of results is more accurate and just how much of the water bear's genome is comprised of foreign DNA.
