Nematodes that had been lying dormant in the Siberian permafrost since the late Pleistocene have been reanimated and sequenced in a new study. Researchers from Russia, Germany, and elsewhere used radiocarbon dating to trace the age of the worms, which preliminary analysis had suggested belonged to either the genera Panagrolaimus or Plectus, to find they are approximately 46,000 years old. As they report in PLOS Genetics, the researchers also generated a genome assembly for the nematodes — which they note are triploid — and through further phylogenetic analyses, they determined that their ancient nematodes belong to a previously undescribed species, which they then dubbed Panagrolaimus kolymaensis. In a comparative analysis with the model organism Caenorhabditis elegans, they found that the two nematodes rely on similar biochemical approaches to cryptobiosis. "[O]ur findings indicate that by adapting to survive cryptobiotic state for short time frames in environments like permafrost, some nematode species gained the potential for individual worms to remain in the state for geological timeframes," the researchers add. "This raises the question of whether there is an upper limit to the length of time an individual can remain in the cryptobiotic state."
Genetic research, in the journals, Scan