Scientists may have found the explanation for how tardigrades can withstand nearly anything | CNN

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A tiny tardigrade, also called a water bear, is seen in its active state.

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Tardigrades, also known as water bears, are known for surviving in some of the most extreme environments on Earth. These microscopic creatures are so remarkable that they have even been sent to the International Space Station for research purposes.

When faced with challenging conditions, the incredibly resilient tardigrades can enter a state of suspended animation known as the “tun state” for many years. Now, scientists claim to have unraveled the mystery of the mechanism that triggers the animals’ survival mode — and this discovery could have implications for humans, according to a new study.

In harsh conditions such as extreme cold or other severe environmental factors, the bodies of tardigrades produce unstable oxygen free radicals and an unpaired electron, also known as reactive oxygen species that can cause damage to the body’s proteins and DNA if their levels become too high. (This oxidative stress is the same physiological response that humans experience when stressed, and it is why health experts recommend consuming plenty of antioxidant-rich foods like blueberries during tough times.)

The researchers discovered that the survival mechanism kicks in when cysteines, a type of amino acid that forms proteins in the body, come into contact with these oxygen free radicals and become oxidized. This process is the signal that prompts the tardigrade to enter the protective tun state. In a way, the free radicals act as the trigger that sets off an alarm.

The findings were published on January 17 in the journal PLOS One.

Lead study author Amanda L. Smythers, a postdoctoral research fellow at Dana-Farber Cancer Institute and Harvard Medical School in Boston, stated that this revelation could potentially contribute to the development of materials that can withstand harsh conditions such as outer space, as well as therapies that could neutralize cancer cells.

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An illustration shows a tardigrade in its dormant state when it goes into the protective “tun” mode to combat stressors.

In unforgiving habitats such as Antarctica, mountain peaks, and deep-sea vents, tardigrades encountering extreme temperatures or dehydration will retract their eight arms and decrease the amount of water they store.

The water bears shrink to one-quarter of their normal size. The typically elongated and somewhat stout invertebrates transform into protective, desiccated spheres in the tun state, remaining dormant in environments that would be lethal for most other organisms.

Smythers and researchers from the University of North Carolina at Chapel Hill and Marshall University in Huntington, West Virginia, initially began investigating this phenomenon based on a growing body of literature suggesting that cysteines played a role in initiating the tun process, she noted.

“When we were looking at the list of all these extreme circumstances that tardigrades can survive — space, vacuum, high salt concentration as seen when an ocean begins to evaporate — the common thread in all of these situations was reactive oxygen species,” Smythers said. “It was actually a bit of a eureka moment.”

Over the last decade, researchers have started to realize that reactive oxygen species, which were once thought to be entirely problematic, “may be crucial for our bodies to function and adapt to different stresses,” Smythers said.

Previous studies suggested that rather than the free radicals initiating the tun process as a defense against stressors, tardigrades were protecting themselves from free radicals. However, Smythers and her coauthors determined that the body’s production of free radicals is actually part of the process that helps tardigrades protect themselves by curling up into a resilient, shell-like structure resistant to extreme heat, cold, or other environmental factors.

“We came up with this idea that perhaps it’s these species that are actually signaling to the tardigrades to enter their tun state,” she explained.

Before embarking on the more extensive process detailed in the study, Smythers enlisted an undergraduate student to conduct a quick experiment and test her initial hypothesis about reactive oxygen species and their role in initiating tun formation.

Amanda Smythers

These microscopic invertebrates thrive in diverse habitats such as Antarctica, deep-sea vents, mountain peaks, and tropical rainforests. Two active water bears are depicted.

Smythers asked the student to go to a drugstore and purchase some peroxide — a common free radical. With Smythers observing the experiment via FaceTime, the student dripped some peroxide onto a water bear to observe its reaction.

“Suddenly, it began contracting. Its legs started retracting into its body. It began shrinking down. It became the quintessential tun that we would expect to see,” Smythers recounted.

According to Smythers, the research was not solely aimed at understanding how the animals fare in harsh environments where they usually reside. She said that the findings could aid in the development of materials that can withstand severe conditions, such as creating protective gear for firefighters that can form a resilient shell when conditions become exceedingly extreme, as well as developing more effective chemotherapy drugs to eradicate malignant tumors by disrupting the defensive mechanisms that make cancer cells so challenging to destroy.

Dr. William R. Miller, a research assistant professor at Baker University in Baldwin City, Kansas, finds the discovery to be promising. Miller, who has researched and written about tardigrades but was not involved in this study, stated, “That would be fantastic, discovering other ways that these mechanisms can be utilized to control cancer.”

Miller expressed admiration for Smythers’ ability to envision how the tardigrade research could be applied to cancer research and other fields, saying that it requires a high level of creativity and strategic thinking to connect one technique or combination of factors to a completely different area. He emphasized the need for more of this kind of thinking.

Jenna Schnuer is a freelance writer, editor, and audio producer based in Anchorage, Alaska, focusing mainly on science, art, and travel.

Author: OpenAI