An immortal species of jellyfish has double copies of genes that protect and repair DNA. The finding could provide clues to human ageing and age-related conditions.

Jellyfish start their lives as drifting larvae. They eventually attach to the seafloor and develop into sprout-like polyps. The bottom-dwellers clone themselves, forming stacked, sedentary colonies that bud off into free-swimming umbrella-shaped medusas.

That stage is a dead end for most jellyfish – but the immortal jellyfish (Turritopsis dohrnii) can reverse the cycle. When times get tough, like in , they melt their bodies into amorphous cysts, reattach to the seafloor and regress into polyps. They can restart the cycle indefinitely to skirt death by old age.

To find out how the immortal jellyfish staves off aging, at the University of Oviedo in Spain and her colleagues sequenced its genome – its full set of genetic instructions – and compared it to that of the related but mortal crimson jellyfish (Turritopsis rubra).

They found the immortal jellyfish had twice as many copies of genes associated with DNA repair and protection. These duplicates could produce greater amounts of protective and restorative proteins. The jellyfish also had unique mutations that stunted cell division and prevented telomeres – chromosomes’ protective caps – from deteriorating.

Then, to pinpoint how T. dohrnii reverts into polyp form, the scientists looked at which genes were active during this reverse metamorphosis. They found the jellies silenced developmental genes to return cells to a primordial state and activated other genes that allow the nascent cells to re-specialise once a new medusa buds off. Together, Pascual-Torner says, these genetic alterations shield the animal from the weathering of time.

But at Texas A&M University at Galveston points out that the crimson jellyfish can also rejuvenate, just not as commonly as T. dohrnii. Using them for comparison might reveal differences in the degree of immortality rather than the key to immortality itself, she says.

Still, Pascual-Torner says the genes they identified could be relevant to human ageing. They could inspire or provide insights into age-related diseases like cancer and neurodegeneration. “The next step is to explore these gene variants in mice or in humans,” she says.

Journal reference: Proceedings of the National Academy of Sciences,

A genetic reservoir of red wolf “ghost DNA” has been found hidden in coyote-wolf hybrids in southwestern Louisiana. The long-lost genes represent genetic diversity that experts thought disappeared when the last 14 wild red wolves were captured and bred in the 1970s.

Red wolves (Canis rufus) are critically endangered. Just over 200 live in captivity, and only one population was reintroduced to the wild in North Carolina in 1987. By 2012, that population reached 120 individuals, but today only 20 remain.

The rewilded wolves are genetically homogeneous and therefore more vulnerable to harmful genetic mutations, changing environments and extinction. The genetically diverse coyote-wolf hybrids may hold the keys to the species’ survival.

“It’s hard for me to feel anything but optimistic,” says at Princeton University in New Jersey.

She and her colleagues sequenced the genomes of more than 30 coyotes from southwestern Louisiana, where red wolves last lived in the wild and where they mingled and mated with coyotes. They found that up to 69 per cent of the genomes originated from red wolves.

The canine chimeras look like intermediates between the two species, but vonHoldt says they behave more like wolves. “I don’t think we should call it a coyote anymore,” she says. “If it looks like a wolf, and it acts like a wolf, maybe we should just call it a wolf.”

The wolf-like coyotes could be the key to conservation. She says that when more red wolves are ready to be reintroduced to the wild, they should be placed close to hybrid carriers of this ghost DNA. Natural matings between the two could increase the genetic diversity of the dwindling gene pool.

Additionally, the researchers are developing biobanks – what vonHoldt calls “frozen zoos” – of coyote cells that could be cloned to resurrect genetic diversity in the natural population. The biobank might also be used to edit red wolf genes back into captive populations, but vonHoldt remains sceptical of that approach.

at the University of Florida, who wasn’t involved with the study, says that biobanking can “absolutely rescue a species”, pointing to successful cloning in endangered black-footed ferrets and Przewalski’s horses.

The study fundamentally challenges how we think about hybrids and conservation. “The US Fish and Wildlife Service doesn’t have a policy on endangered species hybrids,” says at Revive & Restore, a US biotechnology company. “The red wolves could be pioneering that.”

Wisely agrees that preserving ghost genes from hybrids is groundbreaking. “It’s an innovative approach that really calls the US Fish and Wildlife Service to act,” she says. Protecting the coyote-wolf hybrids is well within their regulatory power, even if they don’t designate them as an endangered species, she says. “I’m not sure if people ever talked about conservation in this way.”

Now, vonHoldt is working with nonprofit organisations and government agencies to translate these findings into policy. “There’s a lot to do,” she says, “but the future is bright.”

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