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Image credit: Shatilovich et al., PLOS Genetics, 2023(CC BY 4.0)
Scientists have successfully revived ancient nematodes, or tiny worms, after 46,000 years of being frozen in Siberian permafrost. These hardy microscopic creatures belong to a species previously unknown to science and have been named Panagrolaimus kolymaensis. Nematodes are among the few organisms capable of surviving in extreme environments for extended periods by entering a state known as "cryptobiosis," where all metabolic processes shut down until conditions improve.
This recent discovery extends the known time frame for cryptobiosis survival, with previous records indicating nematodes' revival after 42,000 years. Other organisms, such as tardigrades and rotifers, also exhibit this remarkable survival mechanism. Notably, a bacterial spore has been found preserved in amber for an astonishing 25 to 40 million years.
The nematodes, P. kolymaensis, were discovered 40 meters deep in permafrost on the banks of the Kolyma River in northeastern Siberia. This region has proven to be a treasure trove of ancient finds, including archaic DNA, viruses, and even a fully preserved bear.
Radiocarbon analysis of the permafrost samples indicates they date back to the late Pleistocene period. Genomic analysis revealed that the nematodes belong to an undescribed species.
The researchers cultivated the revived worms for over 100 generations and compared their genome with that of their extant relative, Caenorhabditis elegans. By identifying common genes involved in cryptobiosis, they hope to gain insights into the mechanisms underlying this mysterious state. This understanding could lead to advancements in long-term cell and tissue storage methods. Additionally, scientists are curious about the potential upper limit of nematodes' ability to remain in cryptobiosis.
The implications of this finding extend to our understanding of evolutionary processes, as the extended generation times may stretch from days to millennia. The long-term survival of individuals in cryptobiosis could even lead to the resurgence of otherwise extinct lineages.
