The immortal jellyfish is, true to its name, biologically immortal, capable of reversing its life cycle to perpetually start over.
When the adult forms of the jellies – called jellyfish – are stressed, injured or otherwise in a less than ideal situation, they revert to an earlier stage in their life cycle, becoming a film of cells looking for a place to anchor and grow. into a polyp.
From there, new jellyfish bud, allowing the immortal jellyfish to reproduce asexually and be reborn. And unlike most other jellies which have limited reset abilities before becoming sexually mature, the Immortal Jellyfish can do so even after reproducing sexually as an adult, giving it two different reproductive pathways.
As far as we know, the immortal jellyfish can do this an unlimited number of times – hence its name.
(Note however that it is called immortalnot invincible; they can still totally die. “The fate of anything in the ocean is usually to be eaten at some point,” as Monty Graham, director of the Florida Institute of Oceanography, pointed out to The Wall Street Journal.)
Now researchers from Spain’s University of Oviedo have sequenced the genome of the immortal jellyfish, providing clues as to how it edge of tomorrow‘s himself.
For their study, published in PNAS, the researchers sequenced the genome of jellies at different stages of its life cycle. Next, they compared the sequenced genome of this smaller-than-pink fingernail jelly to the related crimson jelly – but, alas, just as deadly as the rest of us – to unravel the genetic differences that may explain the ability of immortal jellyfish.
“If there was a genetic change during the inversion, that would be significant,” María Pascual-Torner, a marine biologist in Oviedo and co-author of the study, told El País.
In fact, there have been multiple changes to the Immortal Medusa’s genome that make it superior at copying and repairing its DNA over lesser, time-limited creatures. It has twice as many copies of a gene called GLI3, which plays a role in stem cells’ ability to grow into other cells, El País reported.
When the adult forms of jellies – called jellyfish – are stressed, injured or otherwise in a less than ideal situation, they return to an earlier stage in their life cycle.
The immortal jellyfish is also better at maintaining the protective caps at the end of its chromosomes, called telomeres. In other species, including humans, telomeres have been shown to shorten with age.
“What makes this animal special is the synergy of all these changes, which make this jellyfish look younger,” Pascual-Torner said.
“The most interesting thing is that it’s not a single molecular pathway… It’s a combination of several of them,” Jan Karlseder, a molecular biologist at the Salk Institute told the WSJ. affiliated with the study.
“If we’re going to look for lifespan extension, we can’t just focus on one pathway. That’s not going to be enough. We need to look at many of them and how they synergize.
Don’t expect these ideas to unleash our own immortality or result in some miracle cosmetic product; rather, the work is to help us better understand the basic mechanisms of aging, with an extreme example.
“We can’t watch it because, hey, we’re going to harvest these jellyfish and turn them into skin cream,” Graham told Reuters. “This is one of those papers that I think will open the door to a new line of study worth pursuing.”
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