US media: Arctic frozen 24,000-year-old leech rotifer resurrection

On June 7, the American Fun Science website published an article titled "24,000-year-old 'zombies' in the Arctic permafrost are resurrected and cloned." The full text is excerpted below:

They are not afraid of ice and snow anyway.

Some miniature "zombies" that froze in the Arctic permafrost for 24,000 years were recently resurrected and cloned in a laboratory in Russia.

These tenacious creatures are called leech rotifers, so named because of the ring of wheel-shaped cilia around the mouth. Rotifers are multicellular microorganisms that live in freshwater environments and have been around for about 50 million years.

During this long period of time, rotifers have mastered one or two survival skills.

Researchers have previously found that modern rotifers frozen in temperatures as low as minus 20 degrees Celsius can be revived 10 years later. Now, scientists have revived rotifers that were frozen in the permafrost of ancient Siberia late in the Pleistocene (2.6 million to 11,700 years ago). After thawing, these ancient rotifers began to reproduce asexually through parthenogenesis, creating clones with exactly the same genes as the ontology.

A "snapshot" of ancient life

Permafrost — land frozen for at least two years — preserves "snapshots" of life (and death) tens of thousands of years ago. For example, according to the Fun Science website, a 46,000-year-old bird carcass found in the Siberian permafrost in 2020 looks "as if it had only been dead for a few days." In 2020, also in Siberia, a mummified frozen cave bear was discovered, dating back about 39,000 years, with its fleshy black nose and most of its fur preserved.

After thousands of years in the ice, it's amazing how it still looks lifelike. But some of the flora and fauna that were sealed in the ancient permafrost managed to do something even more astonishing: to resurrect themselves from a frozen state.

According to the Fun Science website in 2012, scientists recounted how they re-bred 30,000-year-old plants from immature fruit tissue frozen in the Siberian permafrost. Two years later, the researchers re-cultivated antarctic mosses that had been frozen in Antarctica for 1500 years. Fun Science also reported in 2018 that scientists had found and revived a miniature worm called nematode in two ancient permafrosts in Siberia, one with rocks about 32,000 years old and the other about 42,000 years old.

"Hidden life" skills are strong

Now, scientists have resurrected more frozen animals "zombies" in the permafrost. Before being resurrected, they were in a state of metabolic cessation known as "cryptosomy."

Hirudodons are able to enter a "cryptophytic" state to survive extreme conditions such as severe cold and drought.

Stas Malawin, a researcher at Russia's Institute of Physicochemistry and Soil Biology, says rotifers have evolved "cryptobiosis" because they mostly live in moist habitats that often freeze or dry up.

Speaking to the Fun Science website in an email, Malawin said: "They pause metabolism and accumulate compounds like chaperone proteins that can help them recover from 'cryptobiosis' when conditions improve. Malawin explained that Rotifers also possess certain mechanisms that repair DNA damage and protect their cells from harmful molecules called reactive oxygen species.

In the new study, the scientists drilled 11.5 feet (about 3.5 meters) below the surface of the Araziya River in Siberia and collected permafrost samples there. Using radiocarbon dating, they found that these permafrosts are about 24,000 years old. After thawing the samples, the researchers found a "cryptophytic" state of the genus Rotunda.

Humans are hard to follow

The scientists first isolated and analyzed the permafrost samples to make sure they were not contaminated by modern microbes. To wake up these frozen "sleepers," Malawin said, "we put a piece of permafrost into a Petri dish with the right medium and wait for the creatures to recover from their dormancy, start moving, and reproduce."

Of course, once these thawed survivors begin to clone themselves, scientists can't tell which ones are ancient and which are newborn, because these rotifers are genetically identical. Malawin said that because rotifers typically only survive for about two weeks, the scientists collected data from clones of rotifers 24,000 years ago, not the survivors of the Ice Age themselves.

"Living organisms isolated from permafrost may be the best sample for cryobiological research," Malawin said, and they can provide valuable clues about the mechanisms by which these organisms can survive. These mechanisms could then be validated in cryopreservation tests of human cells, tissues and organs, he said.

However, this does not mean that humans will be able to replicate rotifer's deep-frozen sleep and recovery patterns in the near future.

Malawin said: "The more complex the organism, the more difficult it is to survive in a frozen state. For mammals, this is still not possible. ”

The findings were published on June 7 on the semi-monthly website of Contemporary Biology.

Source: Reference News Network