Meet the indestructible tardigrade

Researchers want to know why tardigrades are so resilient and how that can be used to preserve biological samples.

CHAPEL HILL—Tardigrades-article It’s time for a quiz. Name a creature that can be found, in the ocean, in a dry desert such as the Sahara Desert, in Antarctica, in a rainforest, and even on a mountaintop. Not sure. Here’s a hint. Wherever you are as you read this, if we went outside right now and found some moss or lichen on a brick and brought it inside to look at under a powerful microscope, within ten minutes you would likely find one of the creatures. Give up? The creature is called a tardigrade.

Biologist Thomas Boothby’s has a tardigrade farm in his lab on the third floor of the Genome Sciences building at the University of North Carolina at Chapel Hill. The farm is on a counter in the lab. All the creatures are munching on algae in about one dozen petri dishes.

“The green stuff in the dishes is the algae, the tiny specks around the algae are the tardigrades,” explains Boothby. “The ones you can see are the largest tardigrades which are around one millimeter. That’s about the size of a speck of dust. The smallest species is 50 microns, which is smaller than some cells.”

Looking through the microscope in the lab, the tardigrade doesn’t look real. Yes its legs are moving and it is clearly eating the algae, but it is clear. The organs are visible.

“They’re animals, they are multi-cellular, they are complex with a nervous system and a brain,” explains Boothby, as he looks over his tardigrade farm. “Some species have eye spots, they have digestive track and a reproductive systems, so they are very small but very complex.”

There are about 12-hundred species of tardigrades. The tiny creatures have been around for 500- million years. Researchers are trying to figure out just how tardigrades have become the most resilient creatures on Earth.

“They are really cool, they are really weird, and the proteins that I work with from tardigrades are really weird and don’t behave like the average protein,” explains Samantha Piszkiewicz, a Ph.D. Candidate in Chemistry who is working with Boothy on his tardigrade research. “We get thrown a lot of curve balls."

That’s because tardigrades have a unique family of genes that produce what are called intrinsically disordered proteins. Those are proteins that are dynamic and constantly moving with no stable consistent structure. Scientists believe those proteins produce a gel-like fiber that protects other proteins under extreme conditions. It gives tardigrades an almost supernatural ability to survive.

“I thought I would spend the rest of my career doing pretty standard chemistry,” explains an excited Gary Pielak, Ph.D., Kenan Distinguished Professor or Chemistry at UNC-Chapel Hill. “Don’t get me wrong, I love what I do, but Thomas had led us on this adventure and these proteins are the strangest things I’ve ever worked with.”

Researchers believe those proteins are what allows tardigrades to survive being dried out completely, being heated up past the boiling point of water and being frozen to one degree above zero which is the temperature when all life stops. They can also survive in vacuum of space and survive being exposed to twice as much radiation as humans can survive. And tardigrades can do all of that at every life stage.

So Boothby and his team are trying to better understand and utilize some of the tricks that tardigrades use to protect their cells and their cellular components when they dry out to stabilize pharmaceuticals and other biological materials.

Here’s a real world example of why that could be so important. It’s estimated that 80-90 percent of the cost of vaccination programs in developing parts of the world is because vaccines have to remain cold.

If the vaccine serum gets too warm, the vaccine is ruined and must be thrown out. If scientists could understand how tardigrades are able to stabilize their proteins when they dry out, those same techniques could be applied to vaccines.

The goal is to learn how to dry out vaccines so they could remain stable at ambient or even above normal temperatures. That way, medicines would be able reach everybody, everywhere, cheaply and easily. And so far, the work is showing promising results.

The team has identified a family of proteins that tardigrades make when they dry out. It’s no surprise those proteins are unique to tardigrades. The team has also found that the tardigrades themselves need those proteins to survive. If the genes that control the protein creation are disrupted, the animals don’t survive being dried out. The bottom line: there is something about the proteins that makes them very efficient at protecting biological material. But just what that is remains a mystery.