Tardigrade, an unlikely Sleeping Beauty

Ashleigh Papp: This is Scientific American’s 60 Second Science. I’m Ashleigh Papp.

cardboard: Imagine a small animal that is not an insect or animal. It’s about a millimeter long, shaped like a jelly bean with eight legs, and covered in hard, almost crunchy-looking scales. Ladies and gentlemen, get to know the tardigrade!

Jessica Ehmann: They basically look more or less like something between a worm and a bear with more legs. They got the name water bears from their sluggish gait, which sways from side to side as they walk, which is quite cute.

cardboard: This is Jessica Ehmann (“ee-mahn”), a research associate and former student assistant at the University of Stuttgart in Germany, and she’s quite obsessed with tardigrades.

husband: So that’s basically when I fell in love with the tardigrade because it was sitting there under my binoculars and standing up in front of the body and waving at me.

cardboard: Tardigrades have been around even longer than dinosaurs—about 200 million years. And in all that time, they’ve developed some pretty nifty ways of surviving harsh environmental conditions. If it gets too dry or too cold, a tardigrade can drop its metabolism to near zero and go dormant for years.

husband: They all take her arms and pull her in and you can’t see her arms anymore; They just look like little tongues. And they pull in all their extremities. And then they basically slow their metabolism to a standstill.

cardboard: And then, when the conditions are right again, they wake up and get on with their lives, almost like Sleeping Beauty who sleeps for a century before her prince arrives.

cardboard: Here’s why that’s important. Researchers are really interested in what happens to tardigrades while they’re in this dormant state they call “cryptobiosis.” If almost everything can be turned off and turned back on decades later and fully functional, the tardigrade and its body clock could hold the keys to the Disney princesses’ hibernating palace we’ve been looking for.

cardboard: A previous study from 2008 by some of Ehmann’s colleagues in Stuttgart looked at how long tardigrades can survive in crazy dry conditions. So Ehmann took a similar approach. But this time she turned the temperature down – like below zero.

cardboard: She and her colleagues used tardigrades of the same species and divided them into four groups. Group one, the control group, enjoyed ambient temperatures that provided the researchers with a baseline for their overall survival rates and the length of their life under these normal temperature conditions.

cardboard: The other three groups were run the gauntlet: the researchers froze these tardigrades at (minus) -30 degrees Celsius, slowly thawed them, counted them to see how many were still alive, and then froze them again.

husband: Basically, I just froze and thawed, fed and cleaned the tardigrades for those six to eight months and noted their survival.

cardboard: In all, the team used about 700 tardigrades and kept up with the freeze-thaw cycles until none of them woke up.

cardboard: And after evaluating the survival rates for the four groups, the researchers found that the frozen tardigrades lived longer than the control group.

husband: In fact, when we evaluated the survival of the tardigrades, we saw that the tardigrades that were frozen every two weeks lived about twice as long as the control group.

cardboard: And as long as they were frozen, they didn’t really age.

husband: But that also made the experiments very, very long because they just lived twice as long as we expected (laughs).

cardboard: The longest living tardigrade in this experiment, for reference, was 169 days old when it died! Meanwhile, the longest-living animal in the control group, the animal with tardigrades that didn’t go in and out of the freezer, was 93 days old. These results were recently published in the Journal of Zoology.

cardboard: And that means the time the tardigrades were frozen didn’t seem to affect their internal clocks, almost as if it were being shut down during their dormant phase. And this offers some interesting avenues to explore for potential human applications.

husband: Now I think a lot of people will think about how to freeze people and send them into space like in the sci-fi movies. I don’t think we have to go that far yet. But one application that I personally find very interesting is, for example, freezing and thawing of tissues or cells – for example stem cells, which we can use for medical purposes.

cardboard: If a cancer patient was able to extract their healthy cells prior to chemotherapy and put them into a tardigrade-like dormant state, those cells could potentially be replanted after the harsh treatment is complete, and normal activity — healthy cell or organ function — could resume be recorded much shorter time.

cardboard: We still have a long way to go. Researchers now need to understand the mechanisms involved in tardigrades switching between waking and resting states before we can study whether we can extrapolate anything to the human side of the story. But this work shows us that solutions to a healthy future can exist in unexpected places and even within a creature like the tardigrade, a highly unlikely Sleeping Beauty.

cardboard: For Scientific American’s 60 Second Science, I’m Ashleigh Papp.

[The above text is a transcript of this podcast.]

Leave a Reply

Your email address will not be published. Required fields are marked *