Ancient roundworm revived after 46,000 years of being frozen
An international team of scientists has resurrected an ancient roundworm (nematode) that was frozen in the Siberian permafrost for thousands of years. Radiocarbon dating shows these worms have been 'dead awake' in parts of Siberia since around 46,000 years ago. This is much older than what researchers had estimated them to be and potentially creating a new record of its kind.
The worm belongs to a species called Panagrolaimus kolymaensis
Researchers from the Max Planck Institute in Germany revived the frozen worm in a lab and cultivated it for over 100 generations. After running a genome analysis, the team confirmed the ancient roundworm belongs to a species called Panagrolaimus kolymaensis. Back in 2018, scientists resurrected several roundworms of the same genus, Panagrolaimus, which were about 32,000 years old.
Cryptobiosis is a state of extreme inactivity
In response to adverse environmental conditions like freezing or lack of oxygen, certain organisms are known to enter a state of extreme inactivity, known as cryptobiosis. During this phase, all metabolic procedures come to a halt, preventing reproduction, development, and so on. Organisms can remain in this cryptobiotic state almost 'indefinitely,' as they wait for environmental conditions to get better for survival.
Organisms like brine shrimp, tardigrades are known to enter cryptobiosis
Tardigrades, nematodes, rotifers, and brine shrimp are a few of the organisms that are known to enter cryptobiosis. So far, the longest time worms have been known to remain in cryptobiosis is 39 years. However, the recently revived Siberian roundworm, being several thousand years older, is on track for setting the record of having remained in this state for the longest time.
The roundworm was found about 131-feet-deep in Siberian permafrost
The ancient worm was found buried about 131 feet in Siberian permafrost. The team analyzed the plant material in the vicinity of the worm and estimated that it froze between 45,839-47,769 years ago. It breaks the record of another ancient roundworm, of the genus Plectus, which was also found in Siberian permafrost in 2018. That nematode was found to be 42,000 years old.
The roundworm has similar genes as C.elegans
Interestingly, when the team compared the genomes of the recently recovered roundworm, P. kolymaensis, to one of its living relatives, Caenorhabditis elegans, they found a couple of similar genes between the two. Several of these common genes are linked to helping the worms survive in extreme environments. This finding is surprising considering C. elegans usually dwell in temperate regions, unlike P. kolymaensis.
Researchers want to understand the role of common genes
The team explained their 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." Researchers further want to understand what role the common genes have in cryptobiosis, and if there's a limit as to how long organisms can remain cryptobiotic.
The study's findings can enhance our understanding of evolution
"These findings have implications for our understanding of evolutionary processes, as generation times may be stretched from days to millennia, and long-term survival of individuals of species can lead to the refoundation of otherwise extinct lineages," the study claimed. If scientists are able to fully understand how cryptobiosis occurs, that could help find ways to store cells over long periods of time.
