The arctic permafrost, a frozen landscape that has existed since the ice age, is an invaluable resource for study the climates and landscapes of the past. Organic matter from animals and plants is cryogenically preserved, giving scientists a window in the past conditions of the Earth over tens of thousands of years.
Recently, it was reported that two species of Nematode worms (Panagrolaimus sp. and Plectus sp.) were found frozen in the Siberian permafrost, from core samples taken at a depth of 30m. Even though these nematodes had been frozen for 30,000 to 40,000 years, they were found to be viable, and able to reproduce in laboratory settings once defrosted.
Nematodes are worms of the phylum Nematoda (otherwise known as round worms). They have a worldwide distribution, covering virtually every ecosystem, from marine to glacial environments. There are over 25,000 species of Nematode currently defined, and they make up 80% of the life mass on Earth. They are often less than a millimetre long, and around 50% of all species are parasitic.
One famous Nematode is Caenorhabditis elegans, a model organism used to study developmental biology and genetics. The study of C. elegans led to discoveries including apoptosis (controlled cell death), and was the first animal to have its entire genome sequenced.
It’s not unusual to find pollen, amoeba (single celled-organisms), bacteria and fungi in permafrost, however this is the first time that multicellular eukaryotes have been revived! There is still a chance that these worms were a result of contamination during the retrieval process, although the researchers kept all conditions sterile to reduce this possibility.
Previous to this study, laboratory nematodes have survived cryogenic preservation for up to 39 years. This discovery will help improve our understanding of cryobiology, ageing, and physiological adaptations to extreme conditions.
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The paper: Shatilovich et al 2018. Viable Nematodes from Late Pleistocene Permafrost of the Kolyma River Lowland. Doklady Biological Sciences.Vol. 480, pp. 100–102.