Rotifers are microscopic Multicellular organisms inhabiting freshwater.As we all know, they can withstand freezing (even in liquid nitrogen), boiling, drying and radiation, And this group has insisted that it has not had sex for millions of years. This unremarkable but very hardy bdelloid rotifer now surprises researchers again- A recent study Siberian permafrost was unearthed 24,000 years ago, and live (or at least renewable) rotifers were found there. Surviving 24,000 years in deep freezing is a new record for this species.

Rotifers are not the only creatures that emerge from permafrost or ice.The same researchers behind this latest discovery had previously found Vigorous roundworm In the permafrost in the area.Ancient mosses, seeds, viruses and bacteria all show impressive longevity on ice, prompting Reasonable attention Regarding whether any potentially harmful pathogens may also be released Melting of glaciers and permafrost.

However, given that bdelloids generally only pose a threat to bacteria, algae, and debris, there is not much concern about this particular discovery. But as a key player at the bottom of the food chain, the emerging rotifers suggest that perhaps we should consider how species that have not been seen in a thousand years can be reintegrated into modern ecosystems.

The Soil Cryocology Laboratory in Pszczno, Russia has been digging the permafrost in Siberia in search of ancient organisms for about ten years. The team used radiocarbon dating of surrounding soil samples to estimate the age of the organisms it discovered (evidence shows that the permafrost is not moving vertically). For example, last year, researchers reported “Frozen zooThe 35 living protists (creatures that contain nuclei that are neither animals, plants, nor fungi) ranged in age from hundreds to tens of thousands of years.

In their most recent discovery, freezing researchers discovered live bdelloids after culturing soil samples for about a month. Among rotifers, bdelloids have rather unusual parthenogenesis—that is, through cloning—so the original specimens have begun to do so. Although cloning makes the identification of ancient parents challenging, it does greatly facilitate further research on the characteristics and behavior of unfrozen strains.

In all the above-mentioned permafrost studies, there are always modern biological concerns about sample contamination. In addition to using technologies designed to prevent this from happening, the team also solved this problem by looking at the DNA present in soil samples, confirming that contamination is extremely unlikely. Phylogenetic analysis further showed that although a closely related species was found in Belgium, this species did not match any known modern rotifers.

The team is naturally interested in better understanding the freezing process and in-depth understanding of how these rotifers survive for so long. As the first step, the researchers then frozen the selected cloned rotifers at -15°C for a week and filmed the resurrection of the rotifers.

The researchers found that not all clones survived. Surprisingly, compared with contemporary rotifers from Iceland, Alaska, Europe, North America, and even tropical regions of Asia and Africa, these clones are generally not more frost-resistant than modern rotifers. They are more resistant to freezing than their closest genetic relatives, but the difference is small.

The researchers did find that rotifers can survive a relatively slow freezing process (approximately 45 minutes). This is worth noting because it forms gradually, so much so that ice crystals are formed in the cells of animals-this kind of development is usually disastrous for organisms. In fact, anyone engaged in the cryopreservation business strives to seek a protection mechanism against this situation. From this perspective, this latest discovery is particularly tempting.

Although the authors are not fully engaged in this work, they do plan to conduct additional experiments to better understand cryptophytes—a state where the metabolism is almost completely stopped, which makes the survival of rotifers possible. As for the study of cryopreservation of larger organisms, the author believes that this becomes more difficult as the organism in question becomes more complex. In other words, rotifers are by far one of the most complex cryopreserved species-with organs such as the brain and intestines.

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