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Endangered wild sheep clone reported to be healthy
  
By
Edward R. Winstead


Scientists have revealed the existence of a seven-month-old lamb that is the genetic clone of an endangered wild sheep, the mouflon. The lamb is apparently healthy and lives on a nature preserve in Italy with her birth mother, a domestic ewe. She is the first genetic clone of an endangered mammal to survive beyond infancy.


Cloned female mouflon with her foster mother.

Created through the same reproductive techniques as the cloned sheep Dolly, the lamb has DNA from one of two female mouflons that died in a Sardinian wildlife refuge. Researchers recovered cells from the animals' ovaries shortly after their deaths. Later, Pasqualino Loi, of the University of Teramo, Italy, and colleagues injected the nuclei from these cells into domestic sheep egg cells whose nuclei had been removed. The engineered embryos were surgically implanted in four domestic ewes, and one gave birth to the genetic clone.

The lamb is a kind of hybrid, with genomic and mitochondrial DNA from two different species. (Mitochondria are organelles outside the nucleus that have their own genomes.) Tests confirmed that the clone's genomic DNA came from the endangered species and her mitochondrial DNA from the domestic sheep. The research is reported in Nature Biotechnology.

Some wildlife conservationists oppose cloning as a tool for preserving dwindling animal species because, they argue, it cannot preserve or revive the genetic diversity of a species. Nonetheless, research teams have attempted to clone endangered species. For example, last January, a clone of the ox-like guar was born to a cow in Iowa, however, it died of dysentery within 48 hours.

The mouflon is a mountain sheep found on the islands of Sardinia, Corsica, and Cyprus; though endangered, the breed has been successfully introduced into parts of central Europe. Loi and colleagues argue that by collecting and storing the DNA of threatened species when population numbers are high, researchers might be able to restore the original level of genetic variability through cloning.

"Although the nuclear donor cells were recovered from dead animals and considered nonviable, they were able to generate normal embryos and offspring," they write. "Our findings support the use of cloning for the expansion of critically endangered populations, both within a concerted conservation program and in extreme situations involving sudden death."

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Loi, P. et al. Genetic rescue of an endangered mammal by cross-species nuclear transfer using post-mortem somatic cells. Nat Biotechnol 19, 962-964 (October 2001).
 

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