Researchers Discover New Clues to how Tardigrades can Survive Intense Radiation

Courtesy of UNC-Chapel Hill University Communications

Courtney Clark-Hachtel, assistant professor of biology at UNC Asheville, discovered that tardigrades - microscopic animals famed for surviving harsh extremes - have an unusual response to radiation.

Her research, conducted in UNC-Chapel Hill researcher Bob Goldstein's lab, was published on April 12 in "Current Biology," revealing new details on tardigrades' responses to radiation. Radiation has long been known to damage DNA, and in humans, DNA damage from excessive radiation exposure can lead to diseases. But the tardigrades have an unexpected way to correct the damage.

"What we saw surprised us," said Goldstein. "The tardigrades are doing something we hadn't expected."

Goldstein's lab has developed lab methods for studying tardigrades for the past 25 years. The lab has identified several tricks that tardigrades have for surviving conditions that would be life-threatening for humans and most animals.

Sixty years ago, researchers discovered that tardigrades could survive about 1,000 times more intense radiation than humans are known to survive. Clark-Hachtel, a former postdoctoral scholar in the lab, joined the group to examine how tardigrades can survive intense radiation. She found that a species of tardigrade is not immune to DNA damage - irradiation does damage their DNA - but the tardigrades can repair extensive damage.

Clark-Hachtel and Goldstein were surprised to find that tardigrades can increase the volume of production from DNA repair genes. Unlike humans, tardigrades can ramp up the level of DNA repair genes' products to such an extreme extent that they become some of the most abundant gene products in animals.

"These animals are mounting an incredible response to radiation, and that seems to be a secret to their extreme survival abilities," said Clark-Hachtel. "What we are learning about how tardigrades overcome radiation stress can lead to new ideas about how we might try to protect other animals and microorganisms from damaging radiation."

As the UNC-Chapel Hill scientists completed the work, researchers in France found similar results in independent experiments. Museum of Natural History Paris researchers Jean-Paul Concordet and Anne de Cian and their coworkers also found a new tardigrade protein that could protect DNA. Their results are reported in the journal "eLife."

"We were thrilled to see that each lab's results could independently confirm each other," Goldstein adds.

Clark-Hachtel will be continuing research on tardigrades in her lab at UNC Asheville. With the help of three undergraduate student research assistants this summer, she will be expanding on knowledge of tardigrade radiation tolerance using local species of tardigrades in Asheville. The hope is to apply this knowledge to DNA protection and repair in other microscopic organisms, bacteria and even human cells.

"My research seeks to involve students in discovering mechanisms of exceptional genome stability and provides students with the opportunity to engage with biological science in diverse ways, from field collection to molecular biology to coding," Clark-Hachtel said.

"This research will expand our understanding of the mechanisms that animals use to maintain DNA integrity under destructive conditions," she added, "and can provide potential new routes forward to improving DNA stability in other systems."