"He's gone," whispers Chester Zoo vet Gabby Drake - holding a stethoscope to the feathery chest of the XNUMX-year-old bright red parrot.
The bird is a lory - a senior resident of Chester Zoo and a species that the International Union for Conservation of Nature (IUCN) considers to be on the verge of extinction.
It is sad to see this striking, colorful bird go to sleep.
His small, clawed feet were cramped with arthritis that was too advanced to treat.
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It is not, however, the end for the unique genetic code hidden in his cells.
Several small pieces of his body will be placed along with specimens of more than 100 species.
They will be frozen, stored indefinitely, in Britain's largest living tissue biobank, Safe of nature.
In ampoules of nutrient-rich, cell-friendly antifreeze, causes are stored at -196 degrees Celsius, when all natural chemical processes in cells stop and remain frozen in motion.
The idea is that, at some point in the future, perhaps even centuries later, they can be revived.
This is a frozen reserve in case of extinction.
Life starts all over again
Conservationists say we are losing species faster now than before.
In the midst of a biodiversity crisis, which the UN estimates threatens one million species of plants and animals with extinction, some scientists are currently working on choosing what to put in the freezer for the future.
"It won't stop extinction, but it will certainly help," says Tulis Mattson, founder of Sefa Nature.
Tulis is tall, warm-hearted and a passionate enthusiast of his charity's mission - to preserve the living tissue of wild animals.
"Life starts all over here," he says cheerfully, showing a shot of an ampoule of skin cells under a microscope.
The monitor is teeming with tightly packed skin cells - the building tissue of the body.
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The black dot in the center of each spiky, connected cell is the nucleus that contains the unique set of genetic instructions of, in this case, a deceased cheetah.
"This animal died in 2019," Tulis explains.
"We woke up those cells a few days ago - and now you can see them all over the screen. They multiplied."
Skin cells are well-suited for this type of endeavor, especially a type of connective tissue cell called a fibroblast.
They are key to healing and recovery, and - as they are taken out of the freezer and warmed to body temperature in a bath of essential nutrients - they will divide and multiply in the container.
One possible use for these cells is to clone new animals, with the help of these melted packages of DNA.
Animal cloning is not a new niche.
In 1996, scientists in Scotland cloned Dolly the sheep - by fusing a cell from one sheep with an egg cell from another.
It is a reproductive technology, born in the world of domestic animals and now directed towards conservation.
American biotechnology company Revive & Restore she recently produced a clone using skin cells from an endangered black-footed ferret that had been dead for decades.
His eggs were frozen in 1988.
The fusion of a ferret fibroblast with an egg cell produced an embryo, and a clone - Elizabeth-Ann, a female black-footed ferret - was born in December 2020.
The same basic approach was used to clone Prževaljski's wild horse - a species believed to be the last truly "wild" horse alive, at a cost of $60.000.
A clone, named Kurt, lives at the San Diego Zoo.
"It was actually cheaper for the zoo to clone the horse—to introduce more genetic diversity into the American population of the species—than it would have been to ship the horse from a European zoo," explains the company's lead scientist, Dr. Ben Novak.
What species should we freeze?
Genetic diversity is important.
As the population of a species thins out, inbreeding can occur.
In mammals, offspring have a set of genetic instructions from each biological parent.
And if your parents are related, any genetic diseases they have are more likely to be passed on.
Storing cells in banks, however, is not the cheapest way to resurrect genes, says Dr. Novak.
"Conservationists are fighting to save species, but we can't save everything - the decline is ongoing.
"Reacting in advance and putting things in the banks gives us the opportunity to do the recovery in the future," he says.
"If we don't do this, we'll regret it later."
There is a danger that biobanking sends the message that we don't need to worry about saving species now "because we can always freeze them for later," points out Professor Bill Sutherland, a conservation biologist at the University of Cambridge.
"And then there's the issue of prioritizing what's being stored," he says.
"It would be great if we could get tissue from 20 snow leopards from 20 different locations, but that would be very difficult to do."
Instead, Sef nature works closely with zoos around Europe - and especially with Chester Zoo
Whenever an animal has to be euthanized or dies unexpectedly, zoo veterinarians take some tissue for the bank.
"It's a glimmer of light," Tulis says.
"The death of that animal offers little hope for the future of its species, especially since we can freeze its genetics."
While banking what's available isn't a perfect approach, it has provided the Nature Vault with specimens of species including the mountain chicken frog - a critically endangered amphibian that was recently wiped out by a fungal disease.
And he also has tissue from the Javan green magpie, a bird driven to the brink of extinction by demand in the wild bird trade.
(These vividly beautiful birds possess exceptional and highly sought-after mimicry skills.)
Head of Science at Chester Zoo, Dr Sue Walker, says the bottom line is to preserve as much genetic material as possible.
"If we don't do it when the animal dies, we've lost it," she says.
Earlier this year in Chester, Gosha, a nine-year-old female jaguar, was found dead in her enclosure.
Veterinarian Gabby Drake carefully cut off the big cat's left ear, placed it in cold storage and sent it to the Nature Vault, before sending Gosha for an autopsy.
"Jaguars are not the most endangered species of big cat, but their numbers are declining and they face the same pressures from humans as other large predators," Gebi says.
"She was an exceptional young animal and, unfortunately, she never had cubs. It's sad, but it's nice to know that her living tissue will continue to live."
Now several pea-sized pieces of Gošija's velvet ear - cleaned, prepared and immersed in a protective nutrient solution - are in a canister of liquid nitrogen with an ever-increasing selection of biodiversity.
Tulis is optimistic about what science might do in the future.
"With gene editing technology, we could create new genetic diversity," he muses.
Now watching a solo male jaguar patrol his enclosure, Dr Sue Walker of Chester Zoo says it may be "decades before we have the technology to do what we want with these specimens."
Her hope, and the hope of most conservationists, is that using frozen cells from long-dead animals will never be necessary.
"But if we don't collect them, then those genetics are lost forever," she says.
"We have lost that unique biodiversity forever."
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