ИСТИНА

Viable ancient microorganisms are known to be present within the Arctic and Antarctic permafrost. For the first time, the viable metazoan organisms have been discovered in subsurface frozen layers, and their ability to survive within permafrost during dozen thousands years is shown. Two species of free-living soil nematodes, Panagrolaimus kolymensis (Rhabditida) and Plectus aff. parvus (Plectida), were obtained from samples of Pleistocene permafrost deposits of northern Yakutia. Panagrolaimus were isolated from the frozen material of the buried fossil burrows while Plectus from a sample of permafrost deposits obtained during drilling of the Late Pleistocene ice complex. The age estimate of the deposits was based on stratigraphy and radiocarbon dating. The longevity of nematodes cryoconservation corresponded to the permafrost age and reached about 30 thousand years. Revitalization of ancient viable nematodes was observed during enrichment cultivation at 20°C without nutritional supplementation. All adult animals were represented by females. The phylogenetic analysis based on 18S rRNA gene sequences nests the investigated species within the genera Panagrolaimus and Plectus, respectively.