'Frozen Zoo' revives animals on the verge of extinction

As a researcher at the University of California San Diego, Kurt Benirschke believes that tools will one day be developed that can save the lives of animals on the brink of extinction, using specimens that are not known. he began collecting in 1972. A few years later, he moved the collection to the San Diego Zoo, and named it the "Frozen Zoo".

An Indian gaur was born from a genetic specimen at the Frozen Zoo in 2001.

Benirschke passed away in 2018, but his unfinished aspirations still abound. Today, the Frozen Zoo has become the largest repository of animal specimens in the world, with more than 10,500 animals from 1,220 different species.

For a long time, the San Diego Zoo was the only project of its kind. However, in recent years, many similar conservation efforts have developed around the world, and the tools that researcher Benirschke wanted are now a reality. At the same time when the clock is ticking before many endangered species.

A black-footed ferret was successfully cloned in 2020 using genetic specimens from ferrets archived since 1988.

"The stock of rare and irreplaceable animals"

Since 1970, populations of mammals, birds, amphibians, reptiles and fish have decreased by an average of 68%, according to the Living Planet report of the International Organization for Conservation of Nature (WWF) 2020 .

This report also indicates that, due to habitat loss from human activities, one million species of animals and plants are on the verge of extinction in the coming decades and centuries.

At the current rate of biodiversity loss, some scientists believe that preserving specimens from species that 'may not be here tomorrow' is no longer a visionary endeavor. again, but this is a matter of urgency.

Since the Frozen Zoo was founded, they have achieved many milestones in the field of genetics, starting with cloning the first animal, said Oliver Ryder, a geneticist at the San Diego Zoo. first, the sheep Dolly in 1996.

Oliver Ryder, geneticist at the San Diego Zoo.

Beginning in 2001, four endangered species were cloned, using genetic specimens from the Frozen Zoo: Indian Gaur - a humpback Asian bison; Banteng – a species of cattle in Southeast Asia; The Przewalski horse – which once inhabited Mongolia and is extinct in the wild and the Black-footed Weasel – was thought to be extinct in the wild until a small population reappeared in Wyoming (USA) in 1981, but was then almost wiped out by an epidemic.

Genetic rescue

While clones aren't perfect, like the cloned Indian Gaur, which only survives for 48 hours, it's still a great tool for reviving endangered species when possible. increase genetic diversity. If the population of a species declines, the remaining individual species will be forced to mate and the genetic pool will shrink, further threatening the very existence of the species itself.

"In an animal, genetic diversity is what gives resilience, the ability to withstand natural disasters, viral attacks and disease," said Brendon Noble, Professor of Medicine. studied regenerative medicine at the University of Westminster in London.

Banteng - an endangered wild cattle species in Southeast Asia was cloned in 2003.

Professor Noble is also the Chairman of the Board of Directors at Frozen Ark – an animal freezing bank founded in 2004 in the UK, with the same purpose as the 'Frozen Zoo' but with a different structure. .

It currently stores 48,000 samples from 5,500 species - about 90% of which are made up of DNA instead of living cells, and must be stored at much lower temperatures.

But with the DNA sample alone, scientists wouldn't be able to clone the animals. However, DNA is very important in capturing the genetic design of species that may disappear.

At the San Diego Frozen Zoo, specimens are stored in refrigerators.

Lisa Yon, Associate Professor of Zoos and Wildlife Medicine at the University of Nottingham said: "By conserving these resources, we will enable not only existing scientists but also other future generations of scientists make all kinds of new discoveries".

Challenges ahead

The growing climate crisis will put more pressure on ecosystems, putting the responsibility on the shoulders of storage banks.

The Arabian antelope has been declared extinct in the 21st century.

"I consider freezing storage the absolute cornerstone of conservation," says Tullis Matson of Nature's Safe, a UK-based archival bank that collects live cells and gametes. We're facing a sixth mass extinction, so it's important to provide future generations with a pathway to bring 'probably extinct' species back to life."

There are many practical problems faced by these projects. And "protecting the future of the Frozen Zoo is one of the biggest challenges," said Marlys Houck, curator of the San Diego Zoo.

There are only two remaining northern white rhinos in the world, all female.

"We want to continue to collect more specimens while ensuring that the ones we already have are preserved for the long term. This includes securing a dedicated source of liquid nitrogen to finance freeze DNA and replace freezer compartments as they age."

Another thorny challenge is convincing conservation agencies that animal banking is a valid and well-funded strategy. "Many of us are working without any specific support other than donations or grants, with no support from the government or the country," Associate Professor Yon said.

In the end, the researchers all agreed that close cooperation among all the storage banks was key to success. This is a huge task and no one will be able to do it on their own.

The jaguar is an endangered species.

"There's a million species at risk, which means we need 50 different genetic samples from each species, that's 50 million samples; for each of those species, we'll need five vials of each sample again, because So that's hundreds of millions of samples that need to be stored," Matson pointed out.

Ryder says he himself is working to develop a global storage network: "If we were to have a conversation about the future, I would urge everyone to come together to save as much biodiversity as possible." well, the sooner the better. And do it by any means available."