For tens of thousands of years, a microscopic creature lay frozen & immobile underground within the Siberian permafrost.
Yet, when scientists thawed it out, the small tiny multicellular animal didn’t just revive – it reproduced, suggesting that there’s a mechanism whereby multicellular animals can avoid cell damage during the freezing process & awaken able to rumble.
“Our report is that the hardest proof as of today that multicellular animals could withstand tens of thousands of years in cryptobiosis, the state of just about completely arrested metabolism,” said biologist Stas Malavin of the Soil Cryology Laboratory at the Institute of Physicochemical and Biological Problems in Soil Science in Russia.
The creature is one that’s known today – a microscopic invertebrate called a rotifer. These tiny aquatic beasties live life in bodies of water round the world, and their ability to survive conditions like freezing & dehydration is fascinating.
Previous studies and experiments showed that they might survive for years in a state of cryptobiosis, during which the body hits pause on all biological functions – blocked animation , if you wish . For a frozen state, we knew that they might survive for a decade.
The ancient Arctic permafrost has been an unexpectedly rich trove of ancient organisms that have survived millennia. These have included microbes like viruses, also as plants & moss. One exceptional recovery was a multicellular nematode, from permafrost older than 30,000 years.
The recovery of the rotifer, a freshwater species of the genus Adineta, suggests that the nematode’s recovery wasn’t just a wild fluke. The permafrost sample was collected from 3.5 meters (11.5 feet) below ground at the Alazeya River in Northern Siberia. It contained ice-rich loam from the Late Pleistocene; radio-carbon dating confirmed that the sample was around 24,000 years old.
The researchers maintained cultures from this sample, which contained a variety of organisms – including variety of living rotifers. While within the lab, these tiny creatures reproduced by means of parthenogenesis; that’s , asexual cloning, the sole way rotifers can reproduce.
Their presence within the frozen sample – as against contamination – was confirmed by trying to find genetic material within the permafrost & comparing the old rotifers to modern species.
Then, the research team randomly selected 144 individuals of the revived strain and froze them again at a temperature of -15 degrees Celsius for a period of 1 week. The survivors were compared to frozen & revived members of up to date freshwater rotifers. Fascinatingly, the old rotifers didn’t seem to be significantly more freeze-resistant than modern rotifers.
The team’s analysis suggests that, if the freezing process is comparatively slow, the rotifers’ cells can survive the formation of ice crystals with minimal damage, allowing them to survive – although how they could survive for tens of thousands of years remains unknown.
The team hopes to conduct further research into the method within the hopes of identifying the mechanism. this might then – with a really big maybe – help identify how to guard the cells of more complex organisms, the researchers said.
“The takeaway is that a multicellular organism are often frozen and stored intrinsically for thousands of years then return back to life – a dream of the many fiction writers,” Malavin said.
“Of course, the more complex the organism, the trickier it’s to preserve it alive frozen and, for mammals, it isn’t currently possible. Yet, moving from a single-celled organism to an organism with a gut & brain, though microscopic, may be a big breakthrough .”
The research has been published in Current Biology.