How Water Bears Survive Extreme Dehydration

Sep. 6 () –

For the first time, researchers at the University of Tokyo have described a new mechanism that explains how some tardigrades they can withstand extreme dehydration without dying.

Some species of tardigrades, or water bears, as the tiny aquatic creatures are also known, can survive in different environments, often hostile or even fatal to most life forms.

They explored the proteins that form a gel during cell dehydration. This gel hardens to support and protect cells from mechanical stress that would otherwise kill them. These proteins have also been shown to function in insect cells and even show limited functionality in cultured human cells.

Tardigrades often draw attention to themselves, despite being so small. His uncanny ability to survive in situations that would kill most organisms has captured the public imagination. It can easily be imagined that by unlocking its secrets, we could apply the knowledge to ourselves to make humans more resistant to extreme temperatures, pressures, and even dehydration.

This is just science fiction for now, but nevertheless the researchers, also enthralled by the microscopic creatures, are seeking to understand the mechanisms responsible for their robustness, as this could also bring other benefits.

“Although water is essential for all life we ​​know of, some tardigrades can potentially live without it for decades. The trick is how your cells deal with this stress during the dehydration process.“said Associate Professor Takekazu Kunieda of the Department of Biological Sciences at the University of Tokyo and author of the study, published in PLoS Biology.

“It is believed that as water leaves a cell, some type of protein must help the cell maintain physical strength to keep from collapsing in on itself. After testing several different types, we have found that heat-soluble proteins abundant in the cytoplasm (CAHS, for its acronym in English), exclusive to tardigrades, are responsible for protecting their cells against dehydration“.

Recent research on CAHS proteins reveals that they can sense when the cell that encapsulates them becomes dehydrated, and that’s when they spring into action. CAHS proteins form gel-like filaments as they dry. These form networks that support the shape of the cell as it loses its water. The process is reversible, so as tardigrade cells rehydrate, the filaments regress at a rate that does not put undue stress on the cell. Interestingly, however, the proteins exhibited the same type of action even when isolated from tardigrade cells.

“Trying to see how CAHS proteins behaved in insect and human cells presented some interesting challenges,” he said. it’s a statement lead author Akihiro Tanaka, a graduate student in the lab. “For one thing, in order to visualize proteins, we needed to stain them so they would show up under our microscopes. However, the typical staining method requires solutions that contain water, which obviously confounds any experiment where water concentration is a factor. one seeks control. So we turned to a methanol-based solution to fix this problem.”

Research on mechanisms related to the dry preservation of cells or organisms could have many future applications. Kunieda and her team hope that through this new knowledge, researchers can find ways to improve the preservation of cellular materials and biomolecules in a dry state. This could extend the useful life of materials used for research, drugs with short expiration dates or even whole organs needed for transplants.