Scientists Resurrect Worms Frozen in Siberia Permafrost for 46,000 Years

A soil nematode has been reanimated from the Siberian permafrost after lying dormant for 46,000 years.

By studying the biology of these ancient worms, we may be able to get one step closer to freezing our own biology.

The term "permafrost" describes earth that has been frozen for two or more consecutive years. Siberia is home to the world's oldest permafrost, some of which has been frozen for over 650,000 years.

While studying this ancient soil in 2017, Anastasia Shatilovich, a researcher at the Institute of Physiochemical and Biological Problems in Soil Science in Russia, came across two frozen nematodes, a group of small, slender roundworms.

Excited by her discovery, Shatilovich brought the frozen worms to the lab of Teymuras Kurzchalia at the Max Planck Institute of Molecular Cell Biology and Genetics in Germany. At the time, Kurzchalia was studying how certain animals—like nematodes, rotifers and tardigrades—can enter into these states of extreme inactivity in response to unfavorable environmental conditions.

In this state, called cryptobiosis, the organism's metabolism stops, preventing any reproduction, development or repair. "I was interested in this state between life and death," Kurzchalia told Newsweek.

After thawing the worms in the lab, the team was able to date the plant material that had been frozen around the worms to between 45,839 and 47,769 years ago. According to Kurzchalia, this makes them the oldest animals to ever be revived in this way.

Next, the team analyzed the genomes of the ancient worms to see how similar it was to the modern model nematode, Caenorhabditis elegans. Through this analysis, the researchers determined that the worms belonged to a previously undescribed species called Panagrolaimus kolymaensis.

C. elegans can only freeze its biology like this in its juvenile form, whereas P. kolymaensis appears to be able to undergo cryptobiosis throughout its life cycle. However, both nematode species appear to use similar physiological mechanisms to enter this suspended state.

While these mechanisms are still unclear, both organisms appear to rely on a sugar called trehalose to survive through these unfavorable conditions. Therefore, trehalose may be acting as some sort of biological antifreeze in these organisms.

"We are only at the very beginning of understanding how this process occurs—how you can halt life and then restart it," Kurzchalia said. "And if we can understand it in nematodes then maybe we will be able to understand it in human cells and human organs. Maybe there are some practical applications that could be done in several decades, like producing cell lines that can be kept on shelves, for instance. Then, maybe centuries later, we will be able to do this for humans, but today that it really science fiction.

"We must understand the mechanism first and then, derived from that mechanism, we can do something applicable."

The full study was published in the journal PLOS Genetics on July 27.