Recently awoken 46,000-year-old nematodes already have 100 generations of babies

The last time these specimen were squirming about, Neanderthals were still around.
A scanning electron picture of a female Panagrolaimus kolymaensis nematode.

A scanning electron picture of a female Panagrolaimus kolymaensis nematode. Alexei V. Tchesunov and Anastasia Shatilovich / Institute of Physicochemical and Biological Problems in Soil Science RAS

A group of scientists uncovered a 46,000-year-old soil nematode from Siberian permafrost, and in an Sleeping Beauty-esque experiment woke the microscopic organism up from a millenniums’ long rest. The findings are described in a study published July 27 in the open access journal PLOS Genetics.

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Also called roundworms, nematodes are a very adaptable group of sometimes microscopic animals. In addition to tardigrades and rotifers, some nematodes can survive harsh conditions by entering a dormant state known as cryptobiosis. This process basically shuts down the animals’ metabolic systems until they can be revived when environmental conditions become more favorable. 

After uncovering the animals in Siberia’s northern Kolyma River, the team successfully woke them from this frozen-in-time state. Radiocarbon analysis dated the roundworms to 45,839 to 47,769 years ago, when direwolves and Neanderthals were still on Earth

Sequencing the genome revealed that the roundworm is a new species of nematode. Panagrolaimus kolymaensis is a functionally extinct species and joins the ranks of some of Earth’s most ubiquitous organisms that dwell in water, soil, and on the ocean floor. 

P. kolymaensis‘s highly contiguous genome will make it possible to compare this feature to those of other Panagrolaimus species whose genomes are presently being sequenced by Schiffer’s team and colleagues,” study co-author and Director Emeritus at the DRESDEN-concept Genome Center Eugene Myers said in a statement

According to the team, nematodes do not require a lot of coaxing to wake up and wiggle around and make more little roundworms. They have since nurtured more than 100 generations of P. kolymaensis in the lab, where each new generation lasts about 8 to 12 days.

“Basically, you only have to bring the worms into amenable conditions, on a culture (agar) plate with some bacteria, some humidity and room temperature,” study co-author and University of Cologne zoologist Philipp Schiffer explained to Vice. “They just start crawling around then. They also just start reproducing. In this case this is even easier, as it is an all-female (asexual) species. They don‘t need to find males and have sex, they just start making eggs, which develop.”

In addition to the excitement of reviving a species that has been sleeping deep within the earth this long, studying these small spindle-shaped creatures may help scientists better understand how animals can adapt to habitat changes due to global warming and shifting weather patterns at a molecular level. 

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They found that mild dehydration exposure before freezing helped P. kolymaensis prepare for cryptobiosis and increased survival at -112 degrees Fahrenheit. The nematodes produced a sugar called trehalose when it was mildly dehydrated in the lab, potentially enabling it to endure these freezing and intense dehydration. 

“Our findings are essential for understanding evolutionary processes because generation times can range from days to millennia and because the long-term survival of a species’ individuals can result in the re-emergence of lineages that would otherwise have gone extinct,” study Schiffer said in a statement