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THE POTENTIALLY IMMORTAL TURRITOPSIS DOHRINII: THE SECRET TO LIVING FOREVER

  By Julia Wojas

Humans have for ages been fascinated by the idea of prolonging one’s life and the concept of eternal existence and immortality. It might just be that the answer to those fantasies can be found right in our oceans, where a tiny, inconspicuous creature lives, that might help us to understand what it takes to live forever.

The turritopsis dohrnii were originally found in the Mediterranean Sea, however, they currently occupy all the oceans around the world (potentially thanks to maritime transport), which might have only been possible thanks to their rebirth abilities. They were first discovered in the 1880s, initially seeming like regular jellyfish, however, it was 100 years later when their magical properties were accidentally uncovered [1]. 

Like most jellyfish, they are formed when the male medusa passes his spermatophore (capsule filled with sperm) through his tentacles to the female. An egg is then formed which later turns into a planula (larva). This later settles on the seabed and begins to form a colony of polyps. Then an ephyra (immature jellyfish) can detach itself from the polyp, and within a week it can become a mature medusa [2] growing to 4.5mm and developing up to 90 tentacles

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What is interesting, is that the number of tentacles the jellyfish forms differ around the world. In tropical regions, turritopsis dohrnii forms only eight tentacles, whereas in more temperate climates they form twenty-four or more, however, it is not clear where such differences come from.[3]

 

What is particularly fascinating about these inconspicuous creatures is their astonishing ability that sets them apart from other jellyfish.

When turritopsis dohrini is damaged or under stress (e.g. starvation) they can go back to being an ephyra, by reabsorbing their tentacles, and then they once more settle on the seabed. After a while, they can again form a polyp from which a new genetically identical ephyra can detach just as before[4]. This process can be repeated many times, possibly enabling turritopsis dohrnii to live eternally. 

However, an adult medusa has a completely different set of specialized cells and organs compared to a polyp[5], which makes this process even more staggering. It is only possible thanks to transdifferentiation, a type of metaplasia[6] which is the “conversion of one cell type to another”[7] or the reversal of differentiation (dedifferentiation) of a differentiated cell into a stem cell, and later differentiation of it into another specialized (differentiated) cell. This allows the turritopsis dohrnii to go back into its polyp state and then become a jellyfish again. For an adult, damaged medusa to go through such a process, it has to differentiate all of its cells to match the types of cells that a polyp has.  This astonishing ability to go back in the development process over and over again is what allows the jellyfish to repair itself and potentially be immortal.

This amazing ability, if researched, might not only help us understand how we can prevent aging, but it might also be a clue to better understanding how cancer cells work and how we can fight the disease. According to a biologist from the University of Salento, Stefano Piraino the cells of the medusa work very similarly to those of cancer: "some cells of this jellyfish that were supposed to [die] … are able to switch off some genes and to switch on some other genes, reactivating genetic programs that were used in earlier stages of the life cycle"[8].

 

The question that arises when discussing the “rebirth” of turritopsis dohrnii is whether an organism with a completely new set of cells, however, the exact same genes is still the same individual?[9] It also shows us just how much there is yet to be discovered in our oceans. 

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