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Tardigrades, also known as water bears, often survive in some of the world’s most challenging environments. The microscopic animals are so unusual that they even traveled to the International Space Station for research.
When the going gets rough, the surprisingly hardy creatures are capable of entering a form of suspended animation, known for years as the “tuna state.” Now, researchers say they have unlocked the mysterious mechanism that activates the animals’ survival mode – and the work may have implications for humans – according to a new study.
Under stress in extreme cold or other harsh environmental conditions, the bodies of tardigrades produce unstable oxygen and unpaired electron free radicals, which are reactive oxygen species that can damage the body’s proteins and DNA if they accumulate in excess. (Yes, this oxidative stress is the same physiological event that people experience when they are stressed and why health experts recommend that you eat lots of blueberries and other antioxidant foods when you have a hard week at work.)
The survival mechanism begins when cysteines, one of the amino acids that form proteins in the body, come into contact with these oxygen free radicals and become oxidized, the researchers found. That process is the signal that lets the tardigrade know it’s time to go into defense mode. Free radicals are, so to speak, the hammer used to break the glass on a fire alarm.
The results were published January 17 in the journal PLOS One.
The revelation could eventually aid in the development of materials that could respond to harsh conditions such as deep space or therapies that could disarm cancer cells, said lead study author Amanda L. Smythers, a fellow postdoctoral research at Dana-Farber Cancer Institute and Harvard Medical. School in Boston.
‘A eureka moment’
In unmitigated habitats as diverse as Antarctica, mountain peaks and deep-sea vents, tardigrades in the face of extreme temperatures or dehydration will withdraw their eight arms and reduce the amount of water they are storing.
The water gaps shrink to a quarter of their normal size. The usually linear and chunky-looking invertebrates change into their defenses, dried up in the tuna state, lying in environments that would kill most other forms of life.
Smythers and researchers at the University of North Carolina at Chapel Hill and Marshall University in Huntington, West Virginia, first began looking at this phenomenon thanks to a growing body of literature that suggested cysteine was involved in starting the process. tun, she said.
“When we were looking at the list of all these crazy conditions that tardigrades can live in – space, in a vacuum, high salt concentrations like when the ocean starts to evaporate – the one thing that really connected all these things was than reactive oxygen species,” Smythers said. “It was a bit of a eureka moment really.”
In the last decade, researchers have realized that reactive oxygen species, free radicals that were thought to be completely “problematic,” said Smythers, “are very important for our bodies to work and be able to adapt to different stresses.”
Earlier studies suggested that instead of free radicals helping to start the tuna process as a defense against stressors, tardigrades were protecting themselves from free radicals. Instead the body’s production of free radicals, Smythers and her coauthors have discovered, is part of the process of helping the tardigrade to protect itself by curling into a hard-shelled ball that is resistant to extreme heat, cold or environmental factors. another.
“We came up with this idea (that) maybe those species are signaling the tardigrades to go into their tuna state,” she said.
First, an experiment from the book
Before establishing the longer process used in the study, Smythers asked an undergraduate to help conduct a quick experiment and test her early hypothesis about reactive oxygen species and their role in starting tuna formation.
Smythers asked the student to go to a drug store and get peroxide – a common free radical. As Smythers watched the experiment on FaceTime, the student shot peroxide at a water bear to see what would happen.
“Suddenly, it started to squeeze in. His legs began to enter his body. He started to shrink down. It has become an essential wave that we know to look forward to,” said Smythers.
How secret tardigrades could help people
The research was not done just to find out how the animals fare in the often cruel environments they live in. Smythers said the findings could help researchers develop materials that could respond to harsh conditions – such as engineering firefighter gear that could create protection. shell when conditions become overwhelming – or the development of better chemotherapy to destroy malignant tumors by interfering with the defenses that make cancer cells so challenging to kill.
The result is exciting for Dr. William R. Miller, assistant research professor at Baker University in Baldwin City, Kansas. Miller, who has studied and written about tardigrades, was not involved in this research.
“That would be great, to find other ways that these mechanisms can be used to control cancer,” Miller said.
Miller said he was impressed by Smythers’ ability to imagine ways in which the tardigrade research could be applied to cancer research and other fields. He said it takes “a different level of mindset and thinking to get one technique or one combination of things to the very distant future. We need more of that.”
Jenna Schnuer is an Anchorage, Alaska-based freelance writer, editor and audio producer who focuses (primarily) on science, art and travel.
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