A pinky is the size of a nail, a species of jellyfish Cladonema A severed tentacle can be regenerated in two to three days -; But how? Regeneration of functional tissue across species, including salamanders and insects, relies on the ability to generate a blastema, undifferentiated cells that can repair damage and grow into the missing appendage. Jellyfish, along with other cnidarians such as corals and sea anemones, exhibit high regenerative abilities, but how they form complex blastema has remained a mystery until now.
A research group based in Japan, stem-like proliferative cells -; They are actively growing and dividing, but have not yet differentiated into specific cell types -; Appears at the site of injury and helps to form blastema.
The findings were published in the journal Science PLOS Biology.
Importantly, these stem-like proliferative cells in the blastema are distinct from the resident stem cells in the tentacle. Repair-specific proliferative cells mainly contribute to the epithelium -; thin outer layer -; of the tabernacle newly made.”
Yushiro Nakajima, corresponding author, is a lecturer at the Graduate School of Pharmaceutical Sciences at the University of Tokyo
Resident stem cells near the tentacle are responsible for generating all cellular lineages during homeostasis and regeneration, meaning they maintain and repair cells needed throughout the jellyfish's lifetime, says Nakajima. Repair-specific proliferative cells appear only during injury.
„Together, resident stem cells and repair-specific proliferative cells allow rapid regeneration of a functional tentacle within a few days,” Nakajima said, adding that jellyfish use their tentacles for hunting and feeding.
The finding informs how researchers understand how blastema formation differs among different animal groups, said first author Sosuke Fujita, a postdoctoral researcher in Nakajima's same lab at the Graduate School of Pharmaceutical Sciences.
„In this study, our aim was to address the mechanism of blastema formation using the tentacle of a cnidarian jellyfish. Cladonema As a reproductive model in non-bilateral or non-bilaterally developed animals -; or left-right -; during embryonic development,” Fujita said, explaining that the work could provide insight from an evolutionary perspective.
Salamanders, for example, are bipedal animals capable of regenerating limbs. Their limbs contain stem cells restricted to specific cell type requirements, which appear to function similarly to the repair-specific proliferative cells found in jellyfish.
„Because the repair-specific proliferative cells are analogs to restricted stem cells in the pilaterian salamander limb, we can speculate that blastema formation by repair-specific proliferative cells is a common feature acquired independently for complex organ and appendage regeneration during animal evolution,” Fujita said.
The cellular origin of the repair-specific proliferative cells found in the blastema is unclear, however, and the currently available tools are too limited to elucidate the source of those cells or to identify other stem-like cells, the researchers say. Cells.
„It is essential to introduce genetic tools that allow the discovery and manipulation of specific cell lineages. Cladonema,” Nakajima said. „Ultimately, understanding the mechanisms of blastema formation in regenerative animals, including jellyfish, will help us identify the cellular and molecular components that enhance our own regenerative abilities.”
The research was supported by the Japan Society for the Promotion of Science Kakenhi, Japan Science and Technology Agency, Japan Agency for Medical Research and Development, and Japan's National Institute for Basic Biology Joint Research Program.
Fujita, S., and many others. (2023) Distinct stem-like cell populations facilitate functional regeneration of Cladonema medusa tentacles. PLOS Biology. doi.org/10.1371/journal.pbio.3002435.
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