Tardigrades Use Cysteine Oxidation to Trigger Dormancy, Researchers Find

The oxidation of the amino acid cysteine by oxygen free radicals signals the microscopic animals to enter a dormant state, enabling them to withstand extreme conditions.

Researchers have discovered that tardigrades, also known as water bears, use a molecular sensor based on the amino acid cysteine to detect harmful conditions in their environment, triggering a dormant state known as a 'tun'.
In this dormant state, tardigrades can withstand extreme conditions such as freezing, radiation, and environments without oxygen or water.
The oxidation of cysteine by oxygen free radicals signals the tardigrades to enter the tun state. Once conditions improve and the free radicals disappear, the sensor is no longer oxidized, and the tardigrades emerge from dormancy.
Blocking cysteine oxidation prevents tardigrades from forming tuns, indicating that cysteine oxidation is a key sensor for turning dormancy on and off in response to multiple stressors.
The findings suggest that cysteine oxidation is a vital regulatory mechanism that contributes to tardigrades' remarkable hardiness and helps them survive in ever-changing environments.