Scientists wake worm from 46,000 year Siberian slumber

European researchers have revived a 46,000 year-old Siberian roundworm preserved in permafrost.

The animal was collected from the frozen burrow of Arctic gophers located about 40 metres below the surface, in never-thawed late Pleistocene permafrost in the northeastern Arctic.

Roundworms, or nematodes, are known for their ability to survive long periods of time in cryptobiosis – a state of suspended metabolism – enabling animals to survive desiccation and freezing.

Researchers used radiocarbon analysis of nearby plant material to determine the worm’s age as around 46,000 years old. They published their results in PLOS Genetics

According to the paper, previously known records for cryptobiosis in nematodes include about 25 years for an Antarctic species Plectus murrayi (surviving in moss frozen at -20oC) and 39 years for species Tylenchus polyhyphus (surviving in a herbarium specimen).

The researchers described the nematode as a new species Panagrolaimus kolymaensis, following investigations using genome sequencing and analysis comparing the specimen to modern species. 

Permafrost is an ecosystem uniquely capable of preserving life forms at temperatures below freezing for thousands of years.

Although research aimed at reanimating animals from permafrost has grown during the last decade, the paper explains the possibility was first recognised by GULAG prisoner P. N. Kapterev after discovering a viable crustacean Chydorus sphaericus while working at scientific station Skovorodino in 1930s.

Low res journal. Pgen. 1010798. G002
Images showing Panagrolaimus kolymaensis / Credit: Shatilovich et al 2023 / PLOS Genetics / CC-BY 4.0

The paper says given individual worms can survive over geological timeframes, this “raises the question of whether there is an upper limit to the length of time an individual can remain in the cryptobiotic state”.

If generation times can stretch from days to millennia, the findings may have implications for understanding of evolutionary processes, the authors say.

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