New tardigrade species reveal secrets of radiation-resistant powers

A newly identified species of tardigrade is giving scientists insight into what makes these tiny eight-legged creatures so resistant to radiation.

Tardigrades, also known as tardigrades, have long fascinated scientists with their ability to withstand extreme conditions, including radiation levels almost 1,000 times the lethal dose for humans. There are approximately 1,500 known species of tardigrades, but only a handful have been well researched.

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Now scientists have sequenced the genome of a species new to science and revealed some of the molecular mechanisms that give tardigrades their extraordinary resilience. His work has been published in the journal: Science on October 24¹It identifies thousands of tardigrade genes that become more active when exposed to radiation. These processes point to a complex defense system that involves protecting DNA from radiation-induced damage and repairing any breaks that occur.

The authors hope their insights can be used to help protect astronauts from radiation during space missions, clean up nuclear contamination, or improve cancer treatment.

“This discovery may help improve the stress tolerance of human cells and benefit patients undergoing radiation therapy,” says study co-author Lingqiang Zhang, a molecular and cellular biologist at the Beijing Lifeomics Institute.

protective genes

About six years ago, Zhang and his colleagues went to Mount Funiu in China’s Henan province to collect moss samples. Back in the lab and under the microscope, they identified a previously undocumented species of tardigrade and named it. Hypsibius henanensis. Genome sequencing revealed that the species has 14,701 genes, 30% of which are unique to tardigrades.

When researchers revealed H. henanensis They found that when exposed to radiation doses of 200 and 2,000 grays (far beyond what is survivable for humans), 2,801 genes involved in DNA repair, cell division and immune responses were activated.

“It’s like retooling factories in wartime to make only ammunition. “It’s almost a reorganization of how gene expression works,” says cell biologist Bob Goldstein of the University of North Carolina at Chapel Hill, who has studied tardigrades for 25 years. “We are fascinated by how an organism can change gene expression so much that it creates so many transcripts for certain genes.”

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One of the genes, called TRID1It encodes a protein that helps repair double-strand breaks in DNA by recruiting special proteins to sites of damage. “This is a new gene that, to my knowledge, no one has studied,” says Goldstein.

Researchers also estimate that 0.5-3.1% of tardigrade genes were obtained from other organisms through a process known as horizontal gene transfer. A gene called DODA1It appears to be derived from bacteria, enabling tardigrades to produce four types of antioxidant pigments called betalains. These pigments can clear some of the harmful reactive chemicals that cause radiation to occur inside cells and account for 60-70% of the harmful effects of radiation.

The authors treated human cells with one of the tardigrades’ betalains and found that they were much better at surviving radiation than untreated cells.

No expiration date

Studying the molecular mechanisms that enable tardigrades to withstand other harsh conditions, such as extreme temperatures, air deprivation, dehydration and starvation, could have broad applications. For example, it can extend the shelf life of sensitive substances such as vaccines. “All your medications have expiration dates, tardigrades don’t,” says Goldstein.

Comparing these mechanisms between different tardigrades is an important part of this research, adds animal physiologist Nadja Møbjerg from the University of Copenhagen. “We still lack information about the different tardigrade species,” he says.

Goldstein says these animals have “some kind of protective agent that will probably continue to emit more that will be useful and interesting to understand.” “We want to understand how these things work and what potential they have.”