News

Molecular sensor enables water bear hardiness by triggering dormancy

Free radicals sensor triggers tardigrades to enter a dehydrated tun state to withstand extreme stress
Patricia Waldron
By Patricia Waldron
April 6, 2024

Tardigrades – hardy, microscopic animals commonly known as “water bears” – use a molecular sensor that detects harmful conditions in their environment, telling them when to go dormant and when to resume normal life. A team led by Derrick R. J. Kolling of Marshall University and Leslie M. Hicks of the University of North Carolina at Chapel Hill report these findings in a new study published January 17 in the open-access journal PLoS ONE.

SMYTHERS ET AL., 2024, PLOS ONE, CC-BY 4.0
A tardigrade, observed using a confocal fluorescent microscope, was overexposed to 5-MF, a cysteine selective fluorescent probe, that allows for visualization of its internal organs.

Water bears are famous for their ability to withstand extreme conditions, and can survive freezing, radiation, and environments without oxygen or water. They persist by going dormant and entering a tun state, in which their bodies become dehydrated, their eight legs retract and their metabolism slows to almost undetectable levels. Previously, little was known about what signals water bears to enter and leave this state.

In the new study, researchers exposed water bears to freezing temperatures or high levels of hydrogen peroxide, salt or sugar to trigger dormancy. In response to these harmful conditions, the animals’ cells produced damaging oxygen free radicals. The researchers found that water bears use a molecular sensor—based on the amino acid cysteine—which signals the animals to enter the tun state when it is oxidized by oxygen free radicals. Once conditions improve and the free radicals disappear, the sensor is no longer oxidized, and the water bears emerge from dormancy. When the researchers applied chemicals that block cysteine, the water bears could not detect the free radicals and failed to go dormant.

Altogether, the new results indicate that cysteine is a key sensor for turning dormancy on and off in response to multiple stressors, including freezing temperatures, toxins and concentrated levels of salt or other compounds in the environment. The findings suggest that cysteine oxidation is a vital regulatory mechanism that contributes to water bears’ remarkable hardiness and helps them survive in ever-changing environments.

"Our work reveals that tardigrade survival to stress conditions is dependent on reversible cysteine oxidation, through which reactive oxygen species serve as a sensor to enable tardigrades to respond to external changes," the authors stated.

Enjoy reading ASBMB Today?

Become a member to receive the print edition monthly and the digital edition weekly.

Learn more
Patricia Waldron
Patricia Waldron

Patricia Waldron is a science writer in upstate New York. She wrote this article on behalf of PLOS.

Get the latest from ASBMB Today

Enter your email address, and we’ll send you a weekly email with recent articles, interviews and more.

Latest in Science

Science highlights or most popular articles

Snaking toward a universal antivenom
News

Snaking toward a universal antivenom

May 26, 2024

Scientists at Scripps Research have discovered antibodies that protect against a host of lethal snake venoms.

Cell’s 'garbage disposal' may have another role
News

Cell’s 'garbage disposal' may have another role

May 25, 2024

Researchers at Johns Hopkins University have determined that the proteasome could be helping neurons near skin sense the environment.

Clues from bird flu’s ground zero on dairy farms in the Texas panhandle
News

Clues from bird flu’s ground zero on dairy farms in the Texas panhandle

May 25, 2024

Dairy farmers and veterinarians in northern Texas furiously investigated a mysterious illness among cattle before the government got involved.

Universal tool for tracking cell-to-cell interactions
News

Universal tool for tracking cell-to-cell interactions

May 19, 2024

A team of researchers has developed LIPSTIC, which can lay the groundwork for a dynamic map tracking physical interactions between different cells — the elusive cellular interactome.

Weedy rice gets competitive boost from its wild neighbors
News

Weedy rice gets competitive boost from its wild neighbors

May 18, 2024

Rice feeds the world. But researchers have found that a look-alike weed has many ways of getting ahead.

From the journals: JLR
Journal News

From the journals: JLR

May 17, 2024

A “T” makes a difference in blood clotting. High cholesterol: two screens are better than one. Biomarkers for cardiovascular risk. Statin-induced changes to the HDL lipidome. Read about recent papers on these topics.