Producer: Popular Science China
Producer: Kansai Kejian Industrial Research Institute
Producer: Computer Network Information Center, Chinese Academy of Sciences
At the end of July, the world's media focused on a laboratory at the Institute of Soil Physicochemical and Biological Problems of the Russian Academy of Sciences. Here, two nematodes, which have been frozen in the Siberian permafrost for tens of thousands of years, re-thaw and revive, starting a new journey of life.
This is the first time that humans have revived a multicellular organism that has been frozen for so long, and the two nematodes have also successfully reached the top of the list of existing animal lifespans with their own unique "frozen age" secret techniques. At the beginning of their long slumber, the woolly mammoths still roam the tundra of Siberia.
Siberian permafrost – a natural cold storage for the remains of paleontologists
The English name permafrost comes from the abbreviation for permanently frozen ground, which literally means permafrost land. Permafrost occupies 20% of the land area of the northern hemisphere, most of which is concentrated in Siberia in Russia, Alaska in the United States, northern Canada and Greenland, and the thickest point can reach 650 meters (Prudhoe Bay, Alaska).
Vast Siberian permafrost, by Jing Bo
Previously, in permafrost samples in Siberia, scientists have successfully revived a series of frozen ancient creatures. However, what they have in common is that they belong either to single-celled animals or to seeds that have the ability to germinate. Aerobic/anaerobic bacteria, blue-green algae, actinomycetes, single-celled green algae, yeast, amoeba, heterotrophic flagellar, ciliates, bryophytes and even higher plant seeds are on the list.
However, the resurrection of frozen multicellular organisms has not made substantial progress. Although there has been a precedent for the successful emergence of nematodes in frozen specimens for 20 or 30 years, after all, the time is not long enough, and related research has not been able to trigger a greater impact.
On the other hand, due to special natural geographical conditions, well-preserved remains of ancient animals were found in Siberia. In this extremely cold land, large animals such as long-haired mammoths, long-haired rhinos, and burrowing lions that were extinct in the Pleistocene (about 2.6 million to 12,000 years ago, the early Quaternary period of the Geological Age) have all been unearthed, and their integrity is often surprising.
Carcass of a juvenile woolly mammoth found in the Siberian permafrost by James St. John on VisualH
However, when they are excavated from the dark and cold underground, even if they still retain their original appearance, they have long lost their vitality. So, when the two nematodes began to slowly squirm in the Petri dish, the researchers' excitement could be imagined.
Resurrection of nematodes – scientific exploration that is neither simple nor simple
The younger of the two nematodes was collected from the remains of a squirrel cave in Duvanny Yar downstream of the Kolyma River, dating 32,000 years ago by carbon isotopes.
Another nematode was collected from a core drilling of a glacial sediment along the Alazeya River. The sample was taken from a core at a depth of 3.5 meters above the surface and isotopic determination of carbon, dating back about 42,000 years.
The two samples were collected in 2002 and 2015 respectively and have since been kept in the laboratory at -20 degrees Celsius. It is also worth mentioning that the scientists who conducted the study simultaneously collected 300 similar permafrost sediment samples, but only successfully revived ancient nematodes in the above two samples.
The location of the extraction of two samples, author: Jing Bo
The Russian scientific research institutions that led the study are unique in terms of resources for collecting permafrost samples containing biological components, but a series of technical difficulties such as the preservation conditions of samples containing potential resurrection objects during transportation and storage and the antibacterial treatment process have only recently been overcome, clearing the way for the resurrection of ancient nematodes.
The scientists first placed about 2 grams of soil samples containing frozen nematodes in a Petri dish to create conditions suitable for the survival of nematodes in order to allow their populations to proliferate as quickly as possible. Finally, after weeks of meticulous cultivation, two of the more than three hundred Petri dishes appeared alive nematodes that were only a few hundred microns long. These precious tiny creatures are then transferred to agar and special nutrient solutions, where they continue to be carefully cultured with E. coli as a staple food.
Although both species of nematodes have a male form in recent populations, all nematodes that have been reborn this time are females. Since females have fewer anatomical features than males, there is little scientific rigor in taxonomic research based solely on morphology. To this end, the scientists also sequenced a gene on their chromosomes named 18S rRNA after detailed characterization of the morphology and morphology measurements of the two reborn nematodes. After comparing the nematodes 18S rRNA sequences in the gene database, the germline classification of the two nematodes came to an end. The results of the germline analysis show that the two nematodes belong to the Panagrolaimus detritophagus and Plectus parvus species, respectively, and their modern populations have been confirmed in 1930 and 1865, respectively.
A nematode within the genus Panagrolaimus.
△ The nematodes of this genus are generally about 50 microns in diameter, and the S in the figure represents sperm, E is the egg, and O is the oocyte
At present, these two nematodes already have their own pages on Wikipedia, and their deeds, the world's first long-term frozen and revived multicellular animal, are also listed in them. Compared to the insignificant presence of most nematodes, these two nematodes can already be said to be famous.
Ancient Nematode Seal Lifted – Is It Far From Waking up the Frozen Human Body?
Putting the cryonics into hibernation and thus spending the long time of interstellar travel is a classic of many space science fiction works. In this frozen state described in the film, most of the life activities of the human body can be suspended until they are awakened, which is equivalent to an invisibly prolonged lifespan.
Although higher life forms and nematodes belong to the same multicellular organisms, in practice, once the human body enters the freezing dormant mode, life will die, because the complexity of the human body is by no means comparable to that of nematodes. The awakening in the movie is tantamount to bringing people back from the dead, but also alive and well, and the science fiction attributes are clear at a glance. Common sense tells us that it is extremely difficult for advanced life forms after long-term freezing to be resurrected again.
First of all, the tissues and organs of the human body have great diversity, and their constituent elements mainly include water, proteins, fats, inorganic salts and so on from the perspective of substances and materials. The reaction and tolerance of these substances in the face of cryogenic treatment are also different, for example, proteins with complex structures are likely to lose their original biological activity after freezing, and this process is almost irreversible. Cells like nematode cells that are well tolerated for freezing must exist in the human body, but not all parts of the human body can withstand freezing and thawing.
In addition, the extent to which the brain can regain its function is also pessimistic, once the astronomical protein molecules in the human brain are denatured, can this sophisticated machine function normally? Can a series of autonomic nerves that are not controlled by consciousness return to normal function after resuscitation and regulate the most basic physiological activities? Can relatively higher brain functions such as thought, consciousness, and memory be fully restored to pre-freezing levels? I have to say that the answers to these questions are frustrating to think about...
Author:Прокопюк Владимир Юрьевич
△ Low-temperature bank located at the Institute of Cryobiology and Cryogenic Medicine of the National Academy of Sciences of Ukraine
In fact, the scientists who conducted the study have made rational and objective notes on its significance in the paper, "This study reveals the possibility that multicellular organisms can successfully recover after undergoing long-term natural freezing." Certain adaptation mechanisms of Pleistocene nematodes in response to freezing may inspire areas such as cryogenic medicine, cryobiology, and astrobiology. "
What we can see from this is that the historical breakthrough in the cryonic recovery of multicellular animals is indeed true, but the research objects are still only relatively low-level organisms such as nematodes. So, can we question the value of the study?
In fact, as the authors argue, the biggest potential value of this study is that it suggests that future research should focus on the defense mechanisms of nematode cells and tissues in response to freezing. It is this kind of basic research that seems to have little immediate value that is constantly advancing human cognition and utilization of the laws of nature.
In the long run, research in the fields of cryobiology and cryogenic medicine, such as advanced cold protection technology, frostbite tissue repair, and freezing and preservation of biologically derived foods, will also benefit from this process. Compared with space dormancy, the relevance of these topics to human life cannot be said to be inextricably linked.
Permafrost accelerates thawing – the haze of global warming
In an interview with the Siberian Times, the scientists involved in the study used the word mixed when evaluating their mood. This so-called "worry" is the accelerated thawing of permafrost brought about by global warming.
The constant thawing permafrost will bring researchers more precious specimens of ancient animals, plants and bacteria, and such a feast will certainly delight researchers. However, the many environmental consequences of global warming on the permafrost of Siberia are beginning to show.
For example, the remains of ancient animals that decay after thawing are likely to become a breeding ground for deadly pathogens, putting new pressure on local epidemic prevention and control departments. An anthrax outbreak in northern Russia at the end of August 2016 was most likely caused by the remains of an ancient reindeer who died of anthrax. When the average temperature rises, the permafrost gradually thaws, and the remains frozen in the frozen soil are exposed, the dormant bacteria and pathogenic bacteria present in predators will be cross-infected with the corpse as the center. When humans come into contact with infected animals, many zoonotic diseases are further transmitted to humans.
Permafrost in ablation, source: NPS Climate Change Response on Visual
Finally, in any case, we should pay tribute to the tenacious vitality of this group of nematodes. The last time they "breathed" in the fragrance of the earth, the footprints of the cave lions were probably not far away. Today, they are writhing in the Petri dish with their 40,000-year-old bodies, and the time seems to go back to the days when the woolly mammoth was still running on the Siberian wasteland. Forty thousand years of slumber, forty thousand years of heaven and earth, this awakening of forty thousand years, will this curtain open a new era for mankind?
bibliography:
1.
2.
3.http://buzz-plus.com/article/2018/07/27/42000-worm-news/
4.
5.
6.
(The images indicated in this article are authorized)