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A multicellular animal survived frozen for 24,000 years and reproduced upon awakening


This bdelloid rotifer, which was found in the ice sheets of the Russian Arctic, kept its body in cryptobiosis for tens of thousands of years, a state in which metabolism stops almost completely.

In the movie


, directed by Christopher Nolan, astronauts traveling to unknown planets are frozen to avoid aging and survive for hundreds of years.

A similar mechanism is repeated in

Abre los ojos,

the famous film by Alejandro Amenábar in which César, the protagonist, is frozen after suffering an accident to try to revive him in the future.

This cryogenization process, which consists of preserving living beings for long periods of time at low temperatures and is typical of science fiction, is the same that has allowed a multicellular animal known as a bdeloid rotifer to survive frozen for more than 24,000 years, according to a study published recently in the scientific journal

Current Biology


Once thawed, this microscopic organism was able to reproduce in a process called parthenogenesis, in which the female sex cells are not fertilized by the male, but the ovum segments itself and manages to develop into a new being without being fertilized. by a sperm.

Stas Malavin, a researcher at the Soil Cryology Laboratory of the Russian Institute of Physicochemical and Biological Problems in Soil Sciences and first author of the work, tells by email that this rotifer, found in the permanently frozen soil layers of the Siberian Arctic, lived at the same time as woolly mammoths.

He and his colleagues used radiocarbon dating to determine the age of the recovered rotifer.

"Our report is the most compelling evidence that multicellular animals today could endure tens of thousands of years in cryptobiosis, the state in which metabolism is almost completely stopped," says Malavin.

And he adds: "In the future we could preserve organisms with their organs intact almost forever, but for that we need to study how nature does it."

Multicellular animals could endure tens of thousands of years in cryptobiosis, the state of almost completely stopped metabolism

The Russian scientist says that bdelhoid rotifers are "like tiny worms, but with heads and feet", that move and feed using the cilia or eyelashes that often form two small wheels, "hence the Latin name rotifer", he explains. Malavin.

These small animals measure about half a millimeter and can live in moss, rain puddles or in any body of fresh water on the planet, from the Arctic to the tropics.

According to the researcher, they feed on decaying bacteria and organic matter.

Molecular biologist Matthew Meselson, from Harvard University (USA), explains by mail that bdelloid rotifers are small freshwater invertebrates “really remarkable for their resistance not only to prolonged freezing but also to ionizing radiation, desiccation , starvation and various toxic chemicals, ”says the researcher, who was not involved in the study.

And he jokes: "They are as resistant as Rasputin."

According to Meselson, there are about 500 different species of rotifers in the world.

"Bdeloids have been found preserved in amber from 40 million years ago."

Despite research, males have never been documented.

Therefore, Meselson says, bdeloids are known as "ancient asexuals."

The scientist insists that these microscopic and multicellular animals are important to understand the adaptability and resistance of some organisms under extreme conditions.

He even says that rotifers have been sent into space to see how they survive.

The Soil Cryology Laboratory that found this multicellular rotifer has been isolating microscopic organisms from the coldest and most remote layers of Siberia for more than three decades.

During the process they have identified many single-celled microbes, a thousands of years old nematode worm, and mosses and plants that have also regenerated after tens of thousands of years frozen in ice.

Dr. Nataliia Iakovenko, a zoologist at the University of Life Sciences in Prague (Czech Republic) and co-author of the work, tells by mail that these rotifers “are not parasites, do not harbor dangerous microbes and are completely harmless to humans, animals and plants ”.

The researcher, included in the team because she has been studying polar microscopic animals for more than ten years, affirms that the rotifer originally found was the oldest living animal on the planet.

However, Iakovenko explains that in the active state, the life expectancy of these rotifers is only one month, so after being thawed, the animal died within a few days.

"Imagine a sleeping beauty who slept for many years, then woke up, lived a normal life and then died of old age," says the scientist.

"Before he died, however, he laid eggs that hatched into other rotifers, and now the daughters and granddaughters of the oldest living animal are alive."

Research suggests that these animals have some as yet unknown mechanism to protect their cells and organs from damage at extremely low temperatures.

Iakovenko and Malavin agree that although it is not yet possible to conserve a mammal or a human in these conditions, the study of rotifers is a great step forward.

"Of course, the more complex the organism, the more difficult it is to keep it alive in very low temperatures," says Malavin.

The idea, in the future, is to try to imitate these techniques of nature to cold preserve cell cultures and even living tissues and organs.

The hope is that the knowledge of these small animals offers clues on how to keep other organisms alive over time.

This would be very useful for medicine and life sciences.

Iakovenko, however, is skeptical of these possible advances.

“I am not a specialist in human cryomedicine, but as a polar zoologist I can say that even for rotifers, highly evolutionarily adapted to freezing alive, this process is very stressful: 100% of frozen specimens do not survive, especially if they were already old in the moment of freezing, ”he explains.

And he concludes: “Imagine how stressful and dangerous this must be for humans who are naturally not adapted to this process, even if medicine advances to the point of creating freeze stabilizers that allow it.

I suppose that if this procedure is developed, it will be used in critical situations when there is no other way to preserve human life ”.

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Source: elparis

All news articles on 2021-06-24

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