Scientists in Dubai plan 'frozen zoo' for cloning

DUBAI // Scientists in Dubai are keeping a repository of frozen cells they hope can one day be used to create cloned animals that can repopulate species facing the threat of extinction.

Experts at the Camel Reproduction Centre, in al Aweer, are in the initial stages of putting together a "frozen zoo" of cells taken from endangered species.

It is hoped that those cells will bolster dwindling stocks of native species such as the Arabian leopard, the oryx and the tahr, or mountain goat.

"Cloning can help preserve species which are threatened with extinction," said Dr Nisar Wani, the head of the reproductive biology lab at the centre. "We can store millions and millions of cells here. So if tomorrow anything happens to those endangered animals and they become extinct, we can produce millions of embryos from those cells."

The team will next month celebrate the second birthday of the world's first cloned camel, named Injaz, meaning "success" in Arabic. Since then, there have been multiple births of cloned camels. Scientists declined to give figures or success rates, but the majority have been replicas of "genetically elite" racing camels owned by the rulers of Dubai, Dr Wani said.

The centre currently has about a dozen pregnancies, with some in the late stages.

"Last year, our emphasis has mostly been on the camel side," Dr Wani said. "We are going to have an expansion this year with more staff and some other facilities to work on other species as well."

Animal cells are gathered and stored at minus 196°C in a repository that is more than a metre high and looks like an oversized coffee flask.

When the lid is unscrewed, freezing clouds of liquid nitrogen billow out. The scientists cannot put their hands too far down into the steel drum, as the temperature inside is low enough to quickly cause extreme frostbite. The cells, which are stored in dishes vaguely reminiscent of ice cube containers, are attached to metal poles which extend out of the container and hook over the rim. That enables scientists to retrieve whatever is needed without needing to brave the icy temperature inside.

The procedure to get the cells is the same one that created Dolly the sheep, the first cloned mammal, back in 1996.

However cloning an endangered animal is more difficult, because scientists are not allowed to use members of the species as surrogate mothers.

"If there's an endangered species we can't collect the eggs from it," Dr Wani said. "We can't use those limited number of animals which remain for experiments."

Instead, experts are forced to look to other species for surrogates. A cloned baby tahr, for instance, could be carried in the womb of a goat from a different species.

"We have to see what is genetically close to a particular species," said Dr Wani. "The gestation period should be the same, or similar."

Although no animals have yet been produced, the programme is similar to others under way around the world. A member of an endangered species of wild cattle called the banteng was successfully cloned in Massachusetts in 2003 by using eggs from conventional cattle.

In Japan, scientists said in January that they would be able to clone a woolly mammoth from cells taken from the body of an animal preserved for centuries under the Siberian ice. The procedure would be achieved by using eggs from an elephant surrogate, who would also carry the clone to birth.

However, cloning endangered species has not always been successful. Scientists in Spain have been attempting to clone an extinct local species of mountain goat called the bucardo for several years. The first animal to be successfully born two years ago died within days.

Dr Wani is aware of the difficulties.

"If we transfer 100 embryos, sometimes we only get one pregnancy," he said. "Sometimes it's two or three, or other times it's none.

"It can be very frustrating, but we have to be very patient in the cloning process."

Dr Wani declined to say which animals he had already taken samples from, how many, and what species would be the priority in work on endangered species. As for a timetable, he said only that plans are to start using the frozen zoo in the near future.

The Emirates has several indigenous species which are classified as vulnerable or endangered on the red list of the International Union for Conservation of Nature.

An extensive breeding programme both in Jordan and the UAE has brought the Arabian oryx back from the brink of extinction. Several sites, such as the Al Ain Zoo, are actively engaged in returning the animals to the wild and have plans to increase their breeding programme in the coming years.

Mike Maunder, head of conservation strategy development at the zoo, said that cloning could help save endangered species in the future.

"When it gets down to those low tiny numbers, that's when the cloning comes in," he said. "It's not the answer in itself. It's one of a whole series of ways to increase the population of endangered species.

"Cloning is still experimental but it is likely to become increasingly important in the future."

Conventional cloning is done by a process called nuclear cell transfer. The way it works is as follows:

* A skin sample is taken from the original animal. Genetic material is withdrawn from its cells.

* An egg from a surrogate mother also undergoes the same process, where the nucleus is withdrawn.

* The genetic material from the first animal is then implanted into the “empty” egg, and the cells are cultured in the lab before being implanted into the uterus of the surrogate mother.

The procedure is highly precise and involves using tools which are 18 micrometres in width – about a quarter of the size of a human hair – to remove the cell nucleus.

Scientists monitor the entire procedure through a microscope at 400 magnification, and move the tools via a control panel.

Cloning is not always easy and several hundred attempts may be needed before a successful pregnancy. Dolly the sheep, the first animal born through cloning, was created after 277 attempts.

Cloning an endangered species is often even more problematic as it involves using cells from two different species to create a hybrid.

Eggs cells tend to come from species other than the threatened animal. Scientists have been trying for several years to clone a bucardo, a type of Spanish mountain goat which has been extinct.

Using nuclear cell transfer they created 439 bucardo-goat hybrid embryos, of which only 57 were considered suitable for transferring to surrogate mothers.

There were seven pregnancies as a result but only one goat mother gave birth to a live offspring.

UAE’s endangered mammals:

Arabian Leopard - Critically endangered

Arabian Oryx - Endangered

Arabian Tahr - Endangered

Sand Cat - Near Threatened

Saker Falcon - Vulnerable

Houbara Bustard - Vulnerable

* Source: IUCN Red List

mcroucher@thenational.ae