Jellyfish can grow their amputated tentacles, and this ability has left experts in awe. However, scientists may have found the reason behind their mysterious ability.
Jellyfish Regeneration Explained
Researchers from the University of Tokyo revealed in a new study how jellyfish regenerate. They learned that these sea creatures have distinct stem-like cell populations that facilitate the regeneration of their Cladonema medusa tentacle.
The Cladonema jellyfish species can regenerate an amputated tentacle in two to three days. It's roughly the size of a pinkie nail, so many wonder how they do it. Although jellyfish and other cnidarians, including corals and sea anemones, are known to have significant capacities for regeneration, the process by which they create the crucial blastema is still unknown.
The research suggests they have stem-like proliferative cells that are rapidly growing and dividing but have not yet differentiated into distinct cell types. They emerge near the site of injury and aid in forming the blastema. Crucially, the resident stem cells found in the tentacle are not the same as these stem-like proliferative cells in the blastema.
All cellular lineages during homeostasis and rejuvenation are generated by the resident stem cells, which means they preserve and repair any cells required for the jellyfish to survive. Only at the moment of injury do proliferative cells specific to repairs emerge.
According to corresponding author Yuichiro Nakajima, a lecturer at the University of Tokyo, resident stem cells and repair-specific proliferative cells work together to enable quick regeneration of the functional tentacle in a few days.
This discovery contributes to understanding the differences in blastema production between various animal species. For instance, salamanders are bilaterian animals, meaning that during embryonic development, they form from left to right and can regenerate limbs. Their limbs are home to stem cells limited to specific cell types' requirements; this mechanism seems to function similarly to the repair-specific proliferative cells seen in jellyfish.
"Given that repair-specific proliferative cells are analogues to the restricted stem cells in bilaterian salamander limbs, we can surmise that blastema formation by repair-specific proliferative cells is a common feature independently acquired for complex organ and appendage regeneration during animal evolution," said the first author, Sosuke Fujita, a postdoctoral researcher in the same lab as Nakajima.
The researchers note that the current techniques available to explore the origins are too limited to clarify those cells' source or uncover other distinct stem-like cells. The cellular origins of the repair-specific proliferative cells observed in the blastema are still unknown.
"It would be essential to introduce genetic tools that allow the tracing of specific cell lineages and the manipulation in Cladonema," Nakajima said. "Ultimately, understanding blastema formation mechanisms in regenerative animals, including jellyfish, may help us identify cellular and molecular components that improve our own regenerative abilities."
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Immortal Jellyfish To Help Us Extend Our Lifespan?
Some creatures might provide light on or point out the key to living longer lives, not immortality. The eternal jellyfish (Turritopsis dohrnii), is one of the creatures that appears to have an unending lifespan. If this 0.18-inch-long jellyfish is physically damaged, it can regenerate into a genetically identical polyp, the beginning stage of its life, giving the appearance that it will live forever.
The American Museum of Natural History claims that because immortal jellyfish have a "reset button" to return to a previous developmental stage in the event of injury or threat, they can withstand severe surroundings.
This is similar to frogs being able to change into tadpoles instantly. The jellyfish can even do this when it is famished, according to the American Museum of Natural History, which implies that if it is not eaten, it can live for a very long time.
This improbable Lazarus-like metamorphosis is caused by transdifferentiation, the process by which a specialized body cell changes into a different type of cell. Scientists are interested in this procedure because it may be used to replace disease-related damaged human cells and potentially extend human lifespan.
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