American scientists have cloned the first wild carnivorous species by nuclear transfer. Seventeen African Wildcat kittens (Felis silvestris lybica), born to domestic cats were cloned by the inter-species nuclear transfer technique. The kittens were found to be physically and genetically identical to the somatic cell donor, a male African Wildcat indicating successful cloning process.
This achievement did not come easily to Gomez et al, as there were significant difficulties in successful impregnation in the 50 cats implanted with embryos: twelve of the 50 received a positive pregnancy test at approximately 21 days after ovulation. The cats that fell pregnant received in excess of 30 embryos in order to fall pregnant. Of the twelve successful pregnancies, nine were carried to term with the assistance of hormones to maintain pregnancy. Despite the high number of embryos implanted two kittens died in utero, which is thought to be due to placental separation, and only 17 kittens born.
Although seventeen kittens were successfully carried to term, seven of these were stillborn and eight died in the period between birth and six weeks of age and two were healthy at the time of publication. These deaths were due to incomplete ventral wall closure and exterior organs, premature respiratory systems at birth, bacterial infection or placental separation.
Despite the challenges faced in cloning these African Wildcat kittens, the result was ultimately successful, however there are still numerous obstacles that must be overcome, primarily to refine techniques in order to maximise the number of healthy kittens born.
Gomez, M.C., et al (2004) Birth of African Wildcat cloned kittens born from domestic cats. Cloning and Stem Cells, 6 (3) pp 247 - 258
Pasqualino, L., et al (2007) Cloning of endangered mammalian species: any progress? TRENDS in Biotechnology, 25 (5) pp 196 - 200
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