His method involves inserting the nucleus from an egg with faulty mitochondria into a donor egg that has had its nucleus removed.

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Although the transplanted nucleus enters the egg properly imprinted, reprogramming messes this up.

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In order to clone a human, scientists would remove the nucleus of an egg and extract its genetic material, leaving just its shell.

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Sir Ian and his team fused the genetic information from an adult sheep cell nucleus with an egg cell to form an embryo that developed into a genetically identical copy of the original adult.

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This begins with a stimulus, such as an electric shock, that promotes the fusion of an egg cell that has had its nucleus removed with a donor cell whose nucleus it will assume.

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The adult cell whose nucleus was transferred into the egg that became Dolly had a male imprinted genome that was inherited at birth and copied to every cell of the donor's body.

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Certainly, something unusual is happening in the process by which the egg cell sends out signals to reprogram its new nucleus and put the developmental genes back into action.

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Reproductive cloning, which created Dolly the sheep in 1997, involves transferring the nucleus of an adult cell into an egg, giving the resulting embryo a full set of genes without the normal sperm-meets-egg fertilisation step.

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In the case of the northern wombat, the nucleus could be taken from an easily accessible skin cell, and the egg could be provided by a common wombat.

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