Science

Weird "wheel animals" wriggle back to life after 24,000 years frozen

Weird "wheel animals" wriggle ...
Bdelloid rotifers can survive being frozen for long periods by entering a state called cryptobiosis
Bdelloid rotifers can survive being frozen for long periods by entering a state called cryptobiosis
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A close up of a bdelloid rotifer
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A close up of a bdelloid rotifer
Bdelloid rotifers can survive being frozen for long periods by entering a state called cryptobiosis
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Bdelloid rotifers can survive being frozen for long periods by entering a state called cryptobiosis
The experimental setup designed to test how the rotifers could withstand being frozen and thawed
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The experimental setup designed to test how the rotifers could withstand being frozen and thawed
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Scientists have managed to revive microscopic animals that had been frozen in the Siberian permafrost for 24,000 years. The Bdelloid rotifers, or “wheel animals” as they’re sometimes called, shook off their long sleep and went right back to moving, eating and reproducing like the Ice Age was only yesterday.

Bdelloid rotifers are tiny tubular creatures that are surprisingly tough. In that way, rotifers are a lot like tardigrades, except that the latter eats the former. When conditions get too cold or dry for them, rotifers will curl up into a ball and dry out, hibernating for months or years until conditions become more favorable again.

A close up of a bdelloid rotifer
A close up of a bdelloid rotifer

But now the little critters have absolutely smashed their previous record of about 10 years. In this case, the researchers used radiocarbon dating to determine that the permafrost from which they were recovered was between 23,960 and 24,485 years old. As if that wasn’t impressive enough, the rotifers were still able to reproduce through their usual asexual process, called parthenogenesis.

The researchers examined these second generation rotifers more closely, and found that while they were very closely related to modern ones, they’re different enough to constitute a new species. Next, to examine just how the animals might survive such extreme conditions, the researchers froze some of these rotifers at -15 °C (5° F) for one week, then thawed them out and watched them reawaken.

While most multicellular forms of life are damaged by the formation of ice crystals, rotifers seem to be able to protect their cells and organs from this damage. Exactly how remains unknown at this point, the team says.

The experimental setup designed to test how the rotifers could withstand being frozen and thawed
The experimental setup designed to test how the rotifers could withstand being frozen and thawed

As impressive as a 24,000 year slumber is, these rotifers don’t actually hold the record. Worms called nematodes have wriggled back to life after about 40,000 years, while a batch of bacteria has them both beat at an astonishing 100 million years. Still, rotifers may be the most complex creatures in the club so far.

"The takeaway is that a multicellular organism can be frozen and stored as such for thousands of years and then return back to life – a dream of many fiction writers," says Stas Malavin, an author of the study. "Of course, the more complex the organism, the trickier it is to preserve it alive frozen and, for mammals, it's not currently possible. Yet, moving from a single-celled organism to an organism with a gut and brain, though microscopic, is a big step forward.”

The research was published in the journal Current Biology.

Source: Cell Press via Scimex

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5 comments
5 comments
WB
hmm what could go wrong... they made some horror flicks about this type of thing....
VicCherikoff
Not hard to work out how they do it. Just measure the concentration of trehalose (Resurrection Sugar). This amazing sugar surrounds each molecule with water and stops the water from freezing or getting lost from dehydration. During the freezing, the organism's proteins and lipids are preserved. Trehalose is common in many different species, including plants.
Ralf Biernacki
I can't shake the feeling that both rotifers and tardigrades are actually extraterrestrial lifeforms that have been seeded to Earth by meteorites. Intelectually I know that this is silly, and that their genetics fit into the terrestrial tree of life, but they are just so alien.

On a more serious note, most of the creatures that are astonishingly resilient to radiation, freezing, cancer, and harsh conditions have gotten so through one line of development: becoming resistant to drying out. It turns out that adaptations to dehydration have one thing in common: preserving and repairing DNA and cell structure. By happy coincidence, these repair mechanisms also bring about longevity, cancer resistance, and radiation resistance. These adaptations have been successful in creatures as diverse as Deinococcus radiodurans bacteria, Welwitschia mirabilis plants, rotifers, tardigrades, and naked mole rats. If these anti-dehydration genetic mechanisms were available as a gengineering modification, I would sign up right away.
Ralf Biernacki
@Vic: For most other such organisms, trehalose is a major factor in cryptobiotic survival, but not for rotifers. That is what makes them so interesting. To quote from the Cryptobiosis article on Wikipedia: "In some creatures, such as bdelloid rotifers, no trehalose has been found, which has led scientists to propose other mechanisms of anhydrobiosis".
Kevin Ritchey
I’m curious as to how complex the brain system is and how much damage it takes on after a freezing episode. I’m guessing if there are even the slightest higher functionality, it must get damaged leaving the most basic behind such as feeding, movement, and reproduction.