“He’s gone,” mutters veterinarian Gabby Drake of the Chester Zoo, England, as she holds her stethoscope to the chest of a 28-year-old red parrot.
The bird is a love-lory (lorius garrulus), an elderly resident at Chester Zoo and a species listed by the International Union for Conservation of Nature (IUCN) as vulnerable to extinction.
It’s sad to see a bird full of personality like this having to be “put to sleep”. Its small, clawed feet are twisted with arthritis, which has reached a stage too severe to treat.
But it won’t be the end of the unique genetic code contained in your cells. Some small fragments of his body will join samples from another 100 species that will be frozen and stored indefinitely in the UK’s largest living tissue biobank, Nature’s Safe.
In vials of a nutrient-rich, cell-friendly antifreeze, samples are kept at -196°C, at which point all natural chemical processes in the cells stop.
The idea is that sometime in the future, in decades, maybe even centuries, they might be resurrected. It is a kind of “frozen backup” in case of extinction.
life starts over
Conservationists say that right now we are losing species faster than ever before. In the midst of a biodiversity crisis that, according to UN estimates, threatens a million species of plants and animals with extinction, some scientists are working by selecting what goes into the freezer that will store samples for the future.
“It won’t stop extinction, but it will certainly help [em alguma medida a atenuar os efeitos negativos]”says Tullis Matson, founder of Nature’s Safe. He is passionate about the nonprofit’s mission: to preserve living tissue from wild animals.
“This is where life begins again,” he smiles as he displays an image of a vial of cheetah skin cells under the microscope.
The monitor is filled with densely packed epidermal cells, one of the building blocks of an organism. The black dot in the middle of each cell is a nucleus, containing a unique set of genetic instructions that made, in this case, a cheetah.
“This animal died in 2019,” explains Matson. “‘We woke up’ these cells a few days ago. And — you can see it now — they’re all over the screen. They’ve multiplied and multiplied.”
Skin cells are very useful for this strategy, particularly a type of connective tissue cell called a fibroblast. These are critical for curing and repair, and after being removed from the freezer and warmed to body temperature in a nutrient bath, they will divide and multiply in a container.
One of the possible future uses for these cells that come from frozen DNA is the cloning of new animals.
Animal cloning is not new. In 1996, scientists in Scotland cloned Dolly the sheep by fusing a cell from one sheep with an egg from another. It’s reproductive technology, born in the domestic animal kingdom and now being channeled into conservation.
American biotechnology company Revive and Restore recently produced a clone using skin cells from an endangered black-footed ferret that had been dead for decades. Her eggs were frozen in 1988.
Fusion of a ferret fibroblast with an egg produced an embryo, and a clone —Elizabeth Ann, the black-footed ferret—was born in December 2020.
They used the same basic approach to clone a Przewalski horse — a species considered the last truly “wild” living horse — at a cost of $60,000. The clone, named Kurt, lives at the San Diego Zoo in the USA.
“It was actually cheaper for the zoo to clone a horse — to bring more genetic diversity to the American population of the species — than it would be to send a horse from a European zoo,” explains Revive and Restore Chief Scientist Ben Novak. .
Which species should we freeze?
Genetic diversity matters. As the population of a species decreases, this can lead to inbreeding. In mammals, offspring have a set of genetic instructions from each biological parent. And if those parents are related, which is the case with inbreeding, any genetic diseases they have are much more likely to be passed on.
But cell banking is not the cheapest way to resurrect genes, says Novak.
“Conservationists are fighting to save the species, but we haven’t been able to save everything — destruction is ongoing. Getting ahead and putting things on the bench gives us the opportunity in the future to do the restoration,” he says. “If we don’t, we’ll regret it later.”
There are fears, for example, that the biobank will send a message that we don’t need to worry about saving species now “because we can freeze them for later”, says Professor Bill Sutherland, a conservation biologist at the University of Cambridge, UK. .
“And there is the issue of prioritizing what is stored,” he says. “It would be wonderful to get fabric from 20 snow leopards from 20 different locations, but it would be very difficult.”
Instead, Nature’s Safe works closely with zoos across Europe, in particular Chester Zoo.
Whenever an animal has to be “put to sleep” or dies unexpectedly, the zoo’s veterinarians take some tissue to the bank.
“It’s like a ray of sunshine,” says Tullis. “This dying animal actually gives a little bit of hope for the future of this species, because we can freeze that genetics.”
While banking what is available is not a perfect approach, she has provided Nature’s Safe with samples of species such as the mountain toad, a critically endangered amphibian nearly wiped out by a fungal disease, or the Javan green magpie. , a bird driven to the brink of extinction by the illegal wild bird trade. (Some absurdly beautiful birds have remarkable mimicry skills and are also in high demand.)
Chester Zoo Chief Scientist Sue Walker says it’s about saving as much genetic material as possible. “If we don’t do that when the animal dies, we’ve just lost it,” she says.
Earlier this year, in Chester, Goshi, a nine-year-old jaguar, was found dead. Veterinarian Gabby Drake carefully cut off the big cat’s left ear, placed it in a cold pack and placed it in Nature’s Safe, before sending Goshi for an autopsy.
“Jaguars are not the most endangered big cats, but they are in decline and face the same human pressures as other big predators,” says Drake. “She was a very young animal and never had pups, unfortunately. It’s sad, but it’s good to know that her tissue will live on.”
Now, a few pea-sized pieces of Goshi’s velvety black ear, cleaned, prepared and bathed in a protective nutrient solution, are in an increasingly biodiverse repository of liquid nitrogen.
Tullis is optimistic about what science might be possible in the future. “With gene editing technology, we might even be able to create new genetic diversity,” he speculates.
Looking at the now lone male jaguar patrolling his area, Sue Walker of the Chester Zoo says it could be “decades before we have the technology to do what we want with these specimens.”
Her hope, and that of most conservationists, is that the use of frozen cells from long-dead animals will never be necessary.
“But if we don’t collect them, those genetics will be lost forever,” says Walker. “We’ve lost all this unique biodiversity.”
