We have to admit, we’re kind of not surprised.
Tardigrades, as researchers have scientifically named them, are highly resistant water micro-organisms that can resist even in the hardest conditions. Basically, it’s almost impossible to kill, and now scientists have shown that its DNA is just as freakish as it is.
The tardigrade, which is nearly invisible to the naked eye with a maximum body length of 1.5mm, is one of the toughest animals on the planet and is known for its ability to survive in extreme weather. Conditions ranging from a single degree above absolute zero to well above 100C, and can withstand six times more pressure of that of the deepest ocean trenches. 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 tardigrade blows these averages – as well as the previous record holder for foreign DNA, the rotifer – out of the water. As if these water species hadn’t been sufficiently strong, the fact that they have 17.5% foreign DNA also contributes to reinforce their durability.
Researchers said the DNA likely gets inside the genome randomly but what remains allows tardigrades to survive in the most hostile environments. About 17.5 per cent of tardigrade genes closely resembled genes from non-animal organisms like plants and bacteria. According to the lead author of the study, Thomas Boothby, the tardigrades possess more than 6,000 foreign genes, which are taken from bacteria, fungi and Archaea via a process called horizontal gene transfer where two species exchange genetic material as opposed to inheriting all DNA from their parents. 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.
“Animals that can survive extreme stresses may be particularly prone to acquiring foreign genes – and bacterial genes might be better able to withstand stresses than animal ones”, he said.
When this desiccation happens, scientists know that their DNA breaks down into tiny pieces.
Once the cell rehydrates, its membrane and nucleus housing the DNA temporarily becomes leaky and allows other large molecules to pass through easily. That means that while the tardigrade is quickly patching up its own genome, it may accidentally be stitching in another organism’s genes. The tiny animals can survive extremes of temperature, dryness and even the vacuum of outer space.
Biologist Bob Goldstein, who worked with Boothby on the paper, told Gizmodo via email that they couldn’t be sure of the exact species that donated DNA to the tardigrade, partly because some of the species’ genomes may not have been sequenced yet. However, what’s really exciting is that it provides new insight into exactly how life evolves. “But with horizontal gene transfer becoming more widely accepted and more well known, at least in certain organisms, it is beginning to change the way we think about evolution and inheritance of genetic material”, said Boothby.
