Drugs that prevent or reverse the effects of ionizing radiation have long been a sci-fi pipedream, but the gene sequencing of a newly discovered species of tardigrade could change all that.
Tardigrades – also known as “water bears” – have an incredible tolerance for extreme conditions, including their ability to survive doses of radiation nearly 1,000 times higher than that which would kill a human.
Just how the microscopic eight-legged critters survive is a mystery, but Chinese researchers mapping the genome of Hypsibius henanensis, a newly discovered species of tardigrade, have a few ideas and hope their findings could have practical applications outside the lab.
According to the researchers, 2,801 separate genes were activated when H. henanensis was exposed to radiation – all having to do with DNA repair, immune responses, and cell division control.
One such gene, DODA1, is believed by the researchers to have been acquired by H. henanensis from bacteria through horizontal gene transfer – essentially non-reproductive acquisition of genes across species boundaries (it’s the mechanism that allows various bacteria strains to acquire antibiotic resistance). DODA1 only activates in response to radiation and allows H. henanensis to create pigment compounds known as betalains – typically found in bacteria, fungi, and plants.
Betalains absorb radiation, and the researchers note the pigments are quite adept at accumulating radioactive particles found within cells.
The researchers also discovered the tardigrade creates a disordered protein, TRID1, through exposure to radiation. TRID1 “accelerates DNA damage repair by means of a process that encompasses phase separation,” allowing the tardigrade to repair double-strand breaks in DNA that occur due to radiation damage.
The third finding involves a pair of proteins generated on exposure to radiation that speed up the generation of adenosine triphosphate (ATP), the energy used by all living cells, and NAD+, a coenzyme that’s central to metabolism. Both are also involved in regulating DNA repair necessary to recover from excess exposure to radiation.
“Functional research on these radiotolerance mechanisms of tardigrades will broaden our understanding of cell survival under extreme conditions,” the researchers note in their conclusion.
RadX or RadAway?
According to the Chinese team, human cells exposed to tardigrade betalains showed improved survival when exposed to radiation – suggesting an interesting possible application of the findings.
Whether a tardigrade-derived radiation treatment would be preventative or administered after exposure isn’t as clear.
Researchers at the University of North Carolina at Chapel Hill studying tardigrades may have an answer, though. Radiation still hurts water bears – they just have the gene power to ratchet up the repair efforts after exposure.
“These animals are mounting an incredible response to radiation, and that seems to be a secret to their extreme survival abilities,” explained Courtney Clark-Hachtel, an assistant professor of biology at UNC Asheville who was part of the Chapel Hill research team. “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.”
The Chinese team, for example, hopes its research will help protect astronauts from damaging radiation exposure, help eliminate pollution, and make radiation therapy easier to cope with.
As is always the case when these sorts of discoveries are made, results are probably years off, and the creation of an easy-to-use treatment for an excess dose of rads while wandering a post-apocalyptic wasteland is probably even further off. So don’t crawl out through the fallout just yet. ®
