Understanding the genes that enable this tiny organism to withstand radiation could unlock various applications, from cancer treatment to space exploration.
A newly discovered species of tardigrade is helping scientists gain deeper insights into what gives these eight-legged creatures their extraordinary resistance to radiation.
Tardigrades, also known as water bears, have long fascinated scientists due to their ability to survive in extreme conditions, including radiation levels nearly 1,000 times higher than what is lethal to humans. Among approximately 1,500 known species of tardigrades, only a few have been extensively studied.
Now, scientists have decoded the genome of a new species and revealed the molecular mechanisms behind this organism’s remarkable resilience. The research published in the journal Science on October 24 identified thousands of tardigrade genes that become more active in response to radiation. These processes illustrate a sophisticated defense system that not only protects DNA from radiation-induced damage but also repairs breaks if they occur.
The authors hope that these insights could be applied to protect astronauts from radiation during space missions, address nuclear contamination, or enhance cancer treatment.
“This discovery could help enhance human cells’ stress resistance, benefiting radiation therapy patients,” said Dr. Lingqiang Zhang, a molecular and cell biologist at the Lifeomics Institute in Beijing and co-author of the study.
Tardigrade – A tiny arthropod of the phylum Tardigrada that lives in water. (Image: Earth Life).
“Immortal” Genes
About six years ago, Zhang and his team went to Funiu Mountain (Funiu) in Henan Province, China, to collect moss samples. Under the microscope in the laboratory, they discovered a previously unrecorded species of tardigrade, named Hypsibius henanensis. Genome sequencing revealed that this species has 14,701 genes, with 30% unique to tardigrades.
When researchers exposed H. henanensis to radiation doses of 200 and 2,000 gray—far beyond the survival threshold for humans—they found that 2,801 genes related to DNA repair, cell division, and immune response became active.
“It’s like a wartime factory repurposed to produce only ammunition. The level of gene expression reorganization is quite similar,” noted Bob Goldstein, a cell biologist at the University of North Carolina at Chapel Hill, who has studied tardigrades for 25 years. “We are captivated by how an organism alters gene expression to the extent of generating such large amounts of transcription for specific genes.”
One of these genes, called TRID1, encodes a protein that helps repair double-strand breaks in DNA by recruiting specialized proteins to the site of damage. “This is a new gene, and as far as I know, no one has studied it before,” Goldstein stated.
Researchers also estimated that 0.5-3.1% of tardigrade genes were acquired from other organisms through a process known as horizontal gene transfer. The gene DODA1, seemingly acquired from bacteria, enables tardigrades to produce four types of antioxidant pigments called betalains. These pigments can eliminate some harmful reactive chemicals produced by radiation in cells, accounting for 60-70% of radiation’s harmful effects.
The authors treated human cells with one of the tardigrade betalains and found they survived much better than untreated cells when exposed to radiation.
Potential for Creating Shelf-Stable Drugs
Research into the molecular mechanisms that help tardigrades withstand other extreme conditions, such as extreme temperatures, lack of air, dehydration, and starvation, could have numerous applications. For example, it could improve the shelf life of perishables like vaccines. “All drugs have an expiration date—tardigrades do not,” Dr. Goldstein remarked.
Nadja Møbjerg, a zoologist at the University of Copenhagen, believes that comparing these mechanisms across different tardigrade species is a crucial part of the research. “We still lack knowledge about the various unexplored tardigrade species,” she said.
According to Goldstein, tardigrades contain a treasure trove of protective substances yet to be fully explored. “Our goal is to understand how these substances work and tap into their potential,” he stated.
