Jellyfish can regenerate functioning tentacles in just a few days

Imagine a creature so small that it fits on your pinkie nail, yet so remarkable that it can regrow an amputated tentacle in just a few days. This is the reality for the jellyfish species Cladonema, a subject of fascination in the scientific community due to its extraordinary regenerative abilities.

Until recently, the mechanisms behind this rapid healing remained a puzzle. Now, an intriguing study by a Japanese research team offers unprecedented insights into this process, transforming our understanding of regeneration across species.

Stem-like cells help jellyfish regenerate

The team’s discovery uncovers the role of special stem-like cells in jellyfish regeneration. These cells, found at the injury site, are pivotal in forming a blastema — a cluster of undifferentiated cells essential for tissue repair.

This finding is significant because, unlike salamanders and insects that rely on similar processes, the exact nature of blastema formation in jellyfish and related cnidarians like corals and sea anemones was unknown.

According to Yuichiro Nakajima, a lecturer at the University of Tokyo‘s Graduate School of Pharmaceutical Sciences and the study’s corresponding author, these stem-like cells differ from the resident stem cells in the jellyfish tentacles.

“Importantly, these stem-like proliferative cells in blastema are different from the resident stem cells localized in the tentacle,” said Nakajima. “Repair-specific proliferative cells mainly contribute to the epithelium — the thin outer layer — of the newly formed tentacle.”

Distinct cellular roles discovered

While resident stem cells are responsible for generating various cell types during the organism’s life, the newly identified cells are specialized to repair and regenerate, contributing mainly to the jellyfish tentacle’s outer layer.

This distinction is crucial, as Nakajima points out. It’s the synergy between the resident stem cells and these repair-specific cells that enables the jellyfish to swiftly regenerate a functional tentacle, a vital organ for hunting and feeding.

“Together, resident stem cells and repair-specific proliferative cells allow rapid regeneration of the functional tentacle within a few days,” Nakajima said, noting that jellyfish use their tentacles to hunt and feed.

Broader implications of Cladonema jellyfish

Sosuke Fujita, the study’s first author and a postdoctoral researcher in Nakajima’s lab, highlights the broader implications of their work. By studying Cladonema jellyfish, a non-bilaterian animal, they aim to understand blastema formation from an evolutionary perspective.

“In this study, our aim was to address the mechanism of blastema formation, using the tentacle of cnidarian jellyfish Cladonema as a regenerative model in non-bilaterians, or animals that do not form bilaterally — or left-right — during embryonic development,” Fujita said, explaining that the work may provide insight from an evolutionary perspective.

Their findings suggest parallels between the jellyfish’s repair cells and the restricted stem cells in bilaterian animals like salamanders, hinting at a common regenerative feature evolved independently across different animal groups.

However, the journey doesn’t end here. The origin of these repair-specific cells remains a mystery, and current research tools are limited in tracing their lineage.

More study on jellyfish regeneration

Nakajima emphasizes the need for advanced genetic tools to delve deeper into Cladonema’s cellular dynamics. Understanding these mechanisms in regenerative animals like jellyfish could be the key to unlocking new methods to enhance human regenerative abilities.

In summary, this study not only unravels a part of the mystery surrounding jellyfish regeneration but also sets the stage for future discoveries that could have far-reaching implications for regenerative medicine.

The Cladonema jellyfish, once an enigma, is now at the forefront of a scientific breakthrough, offering a glimpse into the potential of life’s remarkable ability to heal and renew.

The full study was published in the journal PLoS Biology.

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