Rotifers in permafrost: life found in ice after 24,000 years

Rotifers can only be seen under a microscope – but they are quite survivors. Severe dehydration, long periods of starvation, hypoxia and cold do not affect microorganisms with a size of 0.1 to 0.5 mm. In previous studies, researchers were able to show that animals can survive up to ten years in a frozen state.

But this achievement is dwarfed a bit in light of the results of a recently published study: From Siberian Permafrost (Read Here More about this carbon stock at risk) Researchers have recovered viable rotors – and they have been frozen for at least 24,000 years. The special thing about it: After thawing, the multicellular cells began to divide.

“Our study is the clearest evidence to date that multicellular animals can survive for tens of thousands of years in cryptobiosis, the almost completely halted metabolic state,” says Stas Malavin of the Russian Institute of Physical, Chemical and Biological Problems in Soil Sciences. He is the author of an article with others In the journal “Current Biology”.

Institute researchers specialize in isolating microorganisms from Siberian permafrost: to collect samples, wells are made in some remote locations in North Pole Procedure. In this way, researchers have already found many single-celled microbes. Roundworms and algae that were 30,000 years old were regenerated in the ice after several thousand years.

Habitat in and around water

Rotifers are now added to the list of resilient organisms. To date, about 2,000 species, some completely different, have been described around the world, and their body can be roughly divided into three parts: a foot consisting of two appendages with adhesive glands, a trunk and a head with a named wheel organ. This consists of moving eyelash fields or rings in which the animals move on one hand, and on the other hand bring food to them. Its habitat is mainly in and around water, where it feeds mainly on algae and small plankton.

The researchers found rotifers of the genus Adineta in permafrost samples. The age of the animals can be determined using radiocarbon dating. After molting, the animals were able to reproduce by parthenogenesis – a form of bisexual reproduction. With this in mind, the scientists bred a second farm of rotifers, which they used to study the process of freezing and thawing in the lab.

Specifically, they froze the animals at minus 15 degrees Celsius for a week. They also put samples from today’s population on hold for comparison. Experiments have shown that most rotifers can survive the formation of ice crystals that form during slow freezing – an indication that they have a mechanism that protects their cells and organs from damage at extremely low temperatures. Biologist Malavin comments: “This means that a multicellular organism can be frozen and stored in this way for thousands of years, to come back to life again – the dream of many authors of fiction.”

Of course, the difficulty of keeping a frozen organism alive increases with its complexity, which is currently not possible for mammals. “But going from a protozoan to an organism with a gut and a brain, even if it’s microscopic, is a huge step forward,” Malavin says. According to him, it is still not clear what it takes to survive in the ice for only a few years and whether the jump to thousands of years makes much difference. Scientists now want to take more samples from the Arctic in search of other organisms capable of such long-term blinding.