Microscopic multicellular animals called bdelloid rotifers are known for their ability to survive extremely low temperatures. They had been reported to survive 6-10 years when frozen between minus 20 and 0 degrees Celsius. Now, an international team of biologists has successfully revived bdelloid rotifers that have been frozen in the Siberian permafrost for 24,000 years.
A bdelloid rotifer. Image credit: Michael Plewka.
In natural, permanently frozen habitats, some organisms may be preserved for hundreds to tens of thousands of years.
For example, stems of Antarctic moss were successfully regrown from an over millennium-old sample covered by ice for about 400 years.
Likewise, whole campion plants were regenerated from seed tissue preserved in relict 32,000-year-old permafrost, and nematodes were revived from the permafrost of two localities in northeastern Siberia, with source sediments dated over 30,000 years ago.
“Our report is the hardest proof as of today that multicellular animals called bdelloid rotifers could withstand tens of thousands of years in cryptobiosis, the state of almost completely arrested metabolism,” said Dr. Stas Malavin, a researcher at the Institute of Physicochemical and Biological Problems in Soil Science.
Dr. Malavin and colleagues used radiocarbon-dating to determine that the rotifers they recovered from the Siberian permafrost were about 24,000 years old.
The microscopic animals belonged to the genus Adineta, and aligned with the contemporary species Adineta vaga collected in Belgium.
Once thawed, the rotifers were able to reproduce in a clonal process known as parthenogenesis.
To follow the process of freezing and recovery of the ancient creatures, the researchers froze and then thawed dozens of rotifers in the lab.
The studies showed the rotifers could withstand the formation of ice crystals that happens during slow freezing.
It suggests they have some mechanism to shield their cells and organs from harm at exceedingly low temperatures.
“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,” Dr. Malavin said.
“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.”
“It’s not yet clear what it takes to survive on ice for even a few years and whether the leap to thousands makes much difference. That’s a question that requires further study.”
The team’s paper was published in the June 7, 2021 issue of the journal Current Biology.
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Lyubov Shmakova et al. 2021. A living bdelloid rotifer from 24,000-year-old Arctic permafrost. Current Biology 31 (11): R712-R713; doi: 10.1016/j.cub.2021.04.077
