CLONING: Bringing Back Endangered Species

Applied Genetics News, Oct, 2000

The first successful cloning of an endangered animal to late-stage fetal development has been reported. Advanced Cell Technology's (ACT, One Innovation Dr., Worcester, MA 01650; Tel: 508/756-1212, Fax: 508/756-0931; Website: www.advancedcell.com) cross-species nuclear transfer to clone the endangered gaur used eggs derived from cows. In late November, a domestic cow named Bessie (Sioux City, IA) is due to give birth to a baby gaur bull, which the company hopes to name "Noah."

The gaur is a large, wild ox species with a hump-like ridge on its back and with white or yellow stockings on all four legs. Adult males have shoulder heights of up to 7 ft. and weigh up to 2,200 lb. Males and females both have horns, which are flattened at the base, strongly curved and sweep backward and inward. Hunted for sport for generations, and with reduced natural habitats in its homelands in India and southeast Asia, the species is now on the list of endangered species.

ACT researchers and their collaborators fused somatic cells of the endangered gaurs (B. gaurus) with the enucleated oocytes from domestic cows (B. taurus). The resultant embryos were transferred to surrogate domestic cows and have continued gestation for well over half a year. DNA analyses have confirmed that the nuclear genomes of the fetuses are B. gaurus in origin, and the cloned gaurs have exhibited typical embryonic and fetal development through the normal differentiation into complex tissues and organs. Noah is due to be born in late November. Details of the cloning are published in the journal Cloning.

"These results represent an important milestone," says Ian Wilmut of Scotland's Roslin Institute, editor-in-chief of Cloning. "The success of this new method shows promise for rescuing rare and endangered species and populations, and possibly even extinct animals and birds in cases where a relative is available."

"This study presents exciting possibilities for those of us working to preserve endangered species," says Robert P. Lanza, vice president of medical and scientific development at ACT and the article's lead author. "We have provided proof of principle that it is possible to successfully clone an endangered mammalian species with normal karyo- and phenotypic development throughout implantation and the late stages of fetal growth."

Cloning techniques may become instrumental in rescuing endangered species - and possibly reversing extinctions that have already occurred. Conservations have used captive propagation programs to preserve endangered species in captivity. Limitations such as restricted physical space for animals, problems with animal husbandry, and general reproductive failure of the animals have created the need for additional propagation programs. Most ethicists who strongly oppose human cloning see no problem in using the technique to rescue endangered species.

"ACT's interspecies nuclear transfer technology also creates the possibility for restoring already extinct species from which intact cell lines are available," notes Lanza. "This underscores the importance of establishing repositories of the cell lines of endangered species, which are imperative to create a 'genetic trust' for future cloning efforts." ACT is collaborating with the Soma Foundation, a nonprofit organization that has been organized to provide funding for collaborations with zoos to preserve endangered species through cloning.

ACT has reached an agreement with the Spanish government to clone the now-extinct bucardo mountain goat. In January of this year, the last of the species was killed by a falling tree at Ordesa National Park in Spain. Tissue from the last animal was preserved before the animal was killed.

The bucardo mountain goat (Capra pyrenaica) was native to the Pyrenees mountain range in northern Spain and had a distinctive thick coat to protect it from frigid mountain air. The bucardo had been listed as an endangered species since 1973, but officials were not able to end the poaching and habitat destruction that eventually led to the bucardo's extinction.

Another animal in which cloning is likely to be used is the Chinese panda, of which there are few remaining.