24,000-year-old creature found frozen in permafrost may still breed
Multicellular invertebrates called bdelloid rotifers are a class of rotifers made up entirely of females. These microscopic worm-like creatures are labeled “Evolutionary scandal” by biologists for thriving for millions of years without having sex. Recently, researchers found that bdelloid rotifers can persist for at least 24,000 years in Siberian permafrost and then reproduce.
Rotifers are well known for their extreme radiation resistance and the ability to endure unwelcoming environments, such as lack of oxygen, drying out, and starvation. They have been around for at least 35 million years and can be found today in freshwater ponds, lakes, streams, and moist terrestrial habitats such as soil, lichen, tree bark and grass. foam.
These tough little creatures – who have a complete digestive tract including a mouth and anus – can survive harsh environments by stopping all activity and almost completely shutting down their metabolism. This behavior is called cryptobiosis, or “hidden life”. Tardigrades can also suspend their metabolism and fall into cryptobiosis for nearly a decade, allowing them to survive extreme conditions.
Stas Malavin, researcher at the Soil Cryology Laboratory at the Institute of Physico-Chemical and Biological Problems in Soil Science in Pushchino, Russia, describes cryptobiosis:
It is a state, in a way, between life and death.
After recovering samples recovered from remote locations in the Arctic via a drilling rig, Malavin and his colleagues used radiocarbon dating to determine that the rotifers were around 24,000 years old. Previous evidence had revealed that the creatures could survive for up to ten years when frozen.
The researchers note that the rotifers found in the permafrost would have been under the feet of giant woolly creatures, like the woolly rhino, now extinct. Impressively, once the team thawed the samples in the lab, the rotifers were able to reproduce. The results are published in Current biology.
However, scientists have yet to understand the biological mechanisms that allow these tiny organisms to survive on ice for such an extended period. “The result of this article is more questions than answers,” commented Malavin.
Studying these creatures could help researchers find ways to improve cryopreservation of cells, tissues and organs. “Humans cannot conserve organs and tissues for such a long time. These rotifers, along with other organisms found in permafrost, represent the result of a large natural experiment that we cannot replicate, so they are good models for further study, ”Malavin suggested.
Manchester University professor of zoology Matthew Cobb, who was not involved in the study, believe that all kinds of animals frozen in permafrost could wake up when global warming temperatures melt the permafrost. “This doesn’t mean that terrifying things are going to come out and eat us, but it does give scientists the opportunity to study how the rotifer has adapted to withstand the bad effects of frost and the opportunity to explore the difference between existing species and their predecessors, ”he stressed.
This is particularly important in the case of bdelloid rotifers which reproduce by parthenogenesis (the clone of the females themselves). One of the benefits of sex is that you mix genes with each generation – here they’re all copied, so there’s less variability for natural selection to operate on.
We now have the possibility to compare the genome of this group of animals with their modern equivalents, known from Belgium. This will shed light on a key biological curiosity and could reveal why some animals have given up sex altogether.
In February 2020, scientists at the University of Colorado at Boulder found that the sudden thaw of permafrost in the Arctic could double carbon emissions, accelerating climate change. However, in March 2020, scientists in Hamburg concluded that the resettlement of massive herds of large herbivores, including reindeer, horses and bison, could curb this effect and save up to 80% of the world’s permafrost soils as far as possible. ‘in 2100.