Zoo builds frozen Noah's Ark

A bank of animal sperm and tissue samples was begun recently, with the ultimate aim of cloning exotic animals

By Chang Ai-Lien

SINGAPORE is creating its own frozen zoo.

HOT AND HIP HAPPENINGS: Besides its foray into cyrogenics, the zoo deals in population control. Attending to a lioness are (from left) Mr Krishnan, a senior zookeeper, Dr Karen Ng, Dr Serena Oh and Dr Martelli. Photo by TAN SUAN ANN

This is a bank of genetic material made up of sperm and tissue samples of the wildlife in captivity here.

The project, started recently at the Singapore Zoological Gardens, will at some stage be used to clone its animals, said Mr Bernard Harrison.

'We're ultimately moving towards cloning,' added the chief executive officer of Wildlife Reserves Singapore (WRS), which runs the Singapore zoo, the Jurong BirdPark and the Night Safari.

Not only would this provide a safety net against extinction, but it would also combat infertility in animals and help the zoo to recreate animals which died prematurely.

So far, said Dr Paolo Martelli, WRS director (veterinary, conservation and research), tissue and sperm samples have been collected from seven animal species. These include monkeys - marmosets, lion-tailed macaques and orang utans.

To get tissue samples, Dr Martelli takes skin scrapings from the animals and grows the cells in petri-dishes.

Sperm is collected via electro-ejaculation. In such a situation, a probe is inserted into the animal's rectum to stimulate ejaculation.

The samples are then frozen at minus 170 deg C and stored in liquid-nitrogen tanks.

CRYOGENICS: Dr Martelli demonstrates how sperm and tissue samples are stored frozen at minus 170 deg C in a liquid-nitrogen tank. Photo by TAN SUAN ANN

At present, the unit can store sperm and tissue samples from about 50 animals.

But Dr Martelli is looking to increase the number to three such tanks and also wants a cold freezer that can store tissue samples.

He is also trying to get a dry shipper - a unit that can be transported on planes - so that he can eventually have a representation of about 500 animals.

Some experts estimate that one animal species is wiped off the face of the Earth every hour. With the ravages of pollution, shrinking habitats and the ever-expanding human population, the situation is likely to get worse.

So zoos are turning to this freezing technique, called cryogenics, in their efforts to stockpile genetic material and preserve a Noah's Ark for future generations.

Said Dr Martelli: 'Cloning has a place in conservation. We're looking into adapting it to use for our exotic animals, but the work being done is still preliminary.'

The genetic material is not stored just for cloning, though. Frozen sperm can already be used in assisted reproduction techniques, such as artificial insemination, in-vitro fertilisation and intro-cytoplasmic sperm injection (ICSI).

In this last process, a single sperm is fused with an egg, and the embryo is implanted in the animal.

These techniques have all been used to impregnate zoo animals here.

Another plan is to use more common species as surrogate mothers to endangered ones, through ICSI.

Dr Martelli said the zoo is working on doing this with the common long-tailed macaque, which would be implanted with the embryo of other highly-endangered macaque species.