MEXICO: Researchers said the DNA likely gets inside the genome randomly but what remains allows water bears to survive in the most hostile environments. Now, this tiny little creature that lives in wet, mossy environments and whose name in Latin means “slow-walker”, can add a new achievement to its molecular makeup-nearly one-sixth or 17.5% of its genome comes from foreign DNA-the most for any currently known animal species.
“We had no idea that an animal genome could be composed of so much foreign DNA”, co-author Bob Goldstein of the University of North Carolina Chapel Hill said in a statement. Researchers are discovering only the ones that have proven useful to the water bears, which suggests tardigrades may swap DNA more often than indicated by the new finding, Mark Welch says.
The researchers also found that numerous tardigrade’s borrowed genes are actually related to stress tolerance and DNA fix.
Defined as the shifting of genetic material materially between organisms, horizontal gene transfer is widespread in the microscopic world.
The eight-legged water bear – a hardy, almost microscopic animal resembling its mammal namesake – gets a huge chunk of its DNA from foreign organisms such as bacteria and plants, scientists have revealed. It can also withstand temperatures from just above absolute zero to well above the boiling point of water, can cope with ridiculous amounts of pressure and radiation, and can live for more than 10 years without food or water.
Many animals are known to acquire foreign genes but the tardigrade possesses the most foreign DNA than any other.
Since we see that many [horizontal gene transfer] genes in tardigrades have known or suspected roles in stress tolerance, it sets up an interesting “chicken and the egg” scenario.
Numerous genes that tardigrades have borrowed help them deal with stress.
Boothby adds that animals that can survive stressful environments and extreme conditions are prone to acquire foreign genes and usually, genes from bacteria can adapt better to stresses than other animals’. My personal speculation is that tardigrades probably originally had some rudimentary ability to survive drying and have increased their ability to survive extremes through the acquisition of foreign genes.
