Study Reveals that Water Bears Do Not have Extensive Foreign DNA

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

A study has recently found that tardigrades have not acquired a significant proportion of their DNA from other organisms. New findings from the University of Edinburgh show that nearly all of what was previously proposed as foreign DNA was simply bacterial contamination.

Controversy was started by a previous study suggesting that one-sixth of the DNA of freshwater tardigrades could be traced back to bacteria. The scientific world was abuzz with the suggestion that tardigrades have the ability to pick up and reuse DNA from other species.

The Edinburgh team then used DNA sequence data from the same species and found that almost all the proposed foreign DNA was in fact just contamination.

The same team conducted further analysis of both sets of DNA data. Their findings suggest that less than 1 percent of tardigrades' genes are likely to have been borrowed from other species.

To learn more, read the article on the Proceedings of National Academy of Sciences of the United States of America.