The world's first cloned rabbit produced from the somatic cells of a rabbit fetus passed a molecular biology test at the Chinese Academy of Agricultural Sciences last week.

Born on February 12, the female rabbit, which weighed 60 grams at birth, is now growing normally at an animal center in Shanghai.

The cloning experiment was conducted by Dr Li Shangang, a researcher at the National Center for Molecular Genetics and Animal Breeding of the Beijing Institute of Animal Sciences.

Since the first somatic cell-cloned sheep, Dolly, was born in 1996, scientists have cloned mice, cattle and pigs.

But it was only in 2002 that French scientists produced the world's first cloned rabbit using ovum cumulus cells from an adult female rabbit.

But the one in China is quite different as it is the first cloned using fibroblast cells from a fetal rabbit.

"Fibroblast cells from fetal rabbits can be cultured for longer periods than those from adult rabbits; so they are better materials for gene modification and gene targeting research," Li told China Daily.

Li and his colleagues selected the back skin cells of a 20-day old rabbit embryo and cultured them into fibroblast cell lines. They then used the fibroblast cells as the donor cell and fused it with an enucleated rabbit's oocyte (immature egg cell of animal ovary) through electric pulse.

Finally, they transferred the cloned embryos into the rabbit's oviduct. After a month-long normal pregnancy, the cloned rabbit was born.

Rabbits are an important research tool as they have a much shorter gestation period than larger mammals such as sheep or cows.

"The advantage is that rabbits reproduce so quickly. Combined with the cloning technique, this would allow researchers to create genetically modified rabbits for medical research very quickly," Li said.

For example, scientists have conducted research on creating a rabbit model for cystic fibrosis caused by a gene defect to improve progress on understanding and treating the disease.

China began cloning research more than three decades ago and produced the first cloned animal, a goat, in 2000.

"Chinese cloning research has reached a global advanced level," Wang Hongguang, director of the China Center for Biotechnology Development affiliated to the Ministry of Science and Technology, said.

"We can reproduce almost all the cloning results in top-class laboratories around the world. However, we are lacking in original creations such as the newly cloned rabbit," Wang told China Daily.

China has announced at the United Nations that it opposes human cloning for reproduction but backs life extension such as therapeutic cloning of human organs and creating new tissues to replace defective ones.

(China Daily 07/24/2007 page1)