A novel nematode species from the Siberian permafrost shares adaptive mechanisms for cryptobiotic survival withC. elegansdauer larva

Some organisms in nature have developed the ability to enter a state of suspended metabolism called cryptobiosis¹when environmental conditions are unfavorable. This state-transition requires execution of a combination of genetic and biochemical pathways^1,2,3that enable the organism to survive for prolonged periods. Recently, nematode individuals have been reanimated from Siberian permafrost after remaining in cryptobiosis. Preliminary analysis indicates that these nematodes belong to the generaPanagrolaimusandPlectus⁴. Here, we present precise radiocarbon dating indicating that thePanagrolaimusindividuals have remained in cryptobiosis since the late Pleistocene (∼46,000 years). Phylogenetic inference based on our genome assembly and a detailed morphological analysis demonstrate that they belong to an undescribed species, which we namedPanagrolaimus n. sp. Comparative genome analysis revealed that the molecular toolkit for cryptobiosis inPanagrolaimus n. sp. and inC. elegansis partly orthologous. We show that biochemical mechanisms employed by these two species to survive desiccation and freezing under laboratory conditions are similar. Our experimental evidence also reveals thatC. elegansdauer larvae can remain viable for longer periods in suspended animation than previously reported. Altogether, our findings demonstrate that nematodes evolved mechanisms potentially allowing them to suspend life over geological time scales.