Science & Technology

How Tardigrades Survive Conditions That Would Kill Almost Everything Else

There's one group of animals that can survive the vacuum of space, deep-sea pressure, blistering radiation, searing heat, and frigid cold. They're called tardigrades — although you could also call them water bears or moss piglets — and in 2017, scientists discovered the protein responsible for their incredible toughness.

Bleed Me Dry

One of the handful of superpowers the tardigrade uses to survive such extreme environments is its ability to shed nearly all of the water from its body and go into what's known as a "tun" state. Researchers have found that tardigrades can survive for up to a decade in that state — and potentially decades more. Typically, when normal cells dry out, all hell breaks loose: the membranes rupture, proteins unfold, and DNA begins fragmenting. But that doesn't happen in tardigrades, and scientists have been trying to figure out why.

Other creatures, such as some yeast and bacteria, can also survive extreme drying, also known as desiccation. They do this by creating large quantities of trehalose, a sugar that takes on a glassy state and protects cell membranes and proteins from damage. Scientists suspected that tardigrades might do the same thing, but no such luck: Only a few tardigrade species produce trehalose. The rest must be doing something different.

Related Video: Tardigrades Are the Toughest Animals on Earth

Heart of Glass

In 2015, scientists found a clue to the mechanism behind tardigrades' tun state: When the tiny creatures shed their water, they produce glassy molecules — a sort of "bioglass" — that coat their cells and protect them from damage.

A few months later, another team got closer to figuring out how that bioglass forms. Biologist Thomas Boothby and his colleagues found tardigrade-specific genes that code for something called intrinsically disordered proteins, or IDPs. IDPs are proteins that are shapeless and flexible most of the time but rearrange themselves into bioglass in the presence of extreme drying.

As ScienceAlert reports, "These newly formed IDP glass structures target specific proteins, molecules, and other essential cell parts when the tardigrade starts losing water, and enclose them in stiff, protective envelopes so they don't fall apart during the desiccation process. When the tardigrade is exposed to water once more, the glass melts and the IDPs return to their floppy, random state." The team announced their discovery at the annual meeting of the American Society for Cell Biology in 2015 and published their findings in the journal Molecular Cell in 2017.

So what does the survival mechanism of a 1-millimeter critter matter to you? Plenty. Scientists hope that we can use tardigrade proteins to stabilize and preserve delicate pharmaceuticals. The refrigeration required to ship vaccines and other medical necessities throughout the world adds cost and risk of damage, and if manufacturers could convert their products into the tardigrade's glass state, they could be stored dry at room temperature until they were ready to use.

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Want to find tardigrades in your own backyard? It's possible! Check out "How To Find Tardigrades and Observe Them Through a Microscope" by Michael W. Shaw and get to hunting. Purchasing through that link supports Curiosity.

Written by Ashley Hamer March 31, 2017

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