For those who dream of immortality, there are three pieces of news. First — good: immortality exists. The second — bad: to get it, you need to be a jellyfish of the species Turritopsis dohrnii. Third — good again: scientists have deciphered its genome and come closer to understanding how to save a person from aging and radically extend his life.
The tiny jellyfish Turritopsis dohrnii, only half a centimeter in size, has long attracted the attention of scientists, because she knows how to reverse her life cycle and get younger. This multicellular organism is theoretically capable of achieving biological immortality by “cancelling” own aging. Who among us does not dream of the same superpower?
While most species of jellyfish have a fixed lifespan of no more than a few months, Turritopsis dohrnii is known to revert to a polyp when it reaches sexual maturity. This is the stage in the life cycle of cnidarians (a type of aquatic creature that has unique, stinging cells that they use to hunt and protect themselves from predators – ed.) when they attach themselves to the bottom and do almost nothing – mdash; only eat and sway from side to side. Moreover, they clone themselves, forming large colonies, until they turn into free-swimming jellyfish.
Numerous experiments by scientists have shown that Turritopsis dohrnii is able to restart its life cycle in the opposite direction at any time, but this happens, as a rule, under adverse conditions — in case of starvation, sudden changes in temperature or salinity of water, body injury. At the jellyfish, the dome and tentacles stop growing, then processes and shoots appear on the body, and it attaches to the bottom, returning to the polyp stage, that is, becoming “youthful”; adult version. You can compare it to how a butterfly turns into a caterpillar again.
It is noteworthy that such cycles of maturation-rejuvenation can be repeated indefinitely. True, environmental conditions do not allow this biological species to gain true immortality, because it has enough natural enemies — predatory fish and larger jellyfish, and no one canceled the disease. In other words, the animal eventually dies.
Nevertheless, the unique skill of Turritopsis dohrnii theoretically makes this creature capable of eternal life, so the interest of scientists in it is quite understandable. A group of researchers from the University of Oviedo (Spain) deciphered the genome of the “immortal” jellyfish and compared it with the genomes of other species that do not have such a “superpower”.
Running to childhood and back
The scientists focused on genes associated with DNA repair and protection. They analyzed almost a thousand genes involved in the aging process, and found that the “immortal” Turritopsis dohrnii has twice as many of them as her “mortal” sisters of Turritopsis rubra. This allows it to cheat death, biologists say: the more such genes, the more negative effects of aging are reduced, the better cell cycles are regulated and the more stable the supply of stem cells. Gene duplicates simply help to produce more protective and repair proteins that the body needs so much.
As it turned out, in the process of rejuvenation of the jellyfish, the activity of some genes is suppressed, while others — intensifies. As a result of this invisible work, the cells are reprogrammed into the original, “youthful” condition. A mechanism is activated that allows the stem cell to turn into any other cell that it wants to become, or rather — what it needs to become for the benefit of the body. & nbsp;
The researchers also noticed that the jellyfish Turritopsis dohrnii activates its “superpower” when he feels threatened, namely — when she needs to avoid predators. Then it turns into a thin layer of cells and tissues that floats in the water, clings to the bottom and turns into a polyp. And when the threat disappears, the jellyfish restarts the biological clock and begins to grow up.
One of the authors of the study, biologist Maria Pascual-Torner, claims that in the course of laboratory experiments, almost all “immortals” jellyfish, having reached puberty and the stage of reproduction, rejuvenated and returned to the state of a cyst, which looks like a kind of ball. This stage precedes the transformation into a polyp. “The process of rejuvenation is accompanied by a change in tissues — the cells of a jellyfish in the state of a cyst are not similar to those that it acquires when it becomes a polyp, — says Pascual-Thorner.
The researchers say their findings will help to understand the mechanisms of aging and the possibility of extending human lifespan. They are sure that there is a connection between the genes responsible for the plasticity of the life cycle of the “immortal” jellyfish, and processes in our body that contribute to longevity. Perhaps eventually methods will be developed that will slow down human aging and cure associated diseases.
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