THE UNIVERSITY OF GEORGIA RESEARCH MAGAZINE : www.researchmagazine.uga.edu

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SUMMER 2002
Charting the Cloning Process
- J.B.P.

At birth, mammals have more than 200 kinds of adult cells, which fulfill very specific roles: nerve, skin, muscle and bone, to name a few. (In cloning, the term adult cell has little to do with age. Instead it refers to any cell that has differentiated into a specific cell type.)

Each adult cell contains a complete package of genetic material in its nucleus. That package consists of two sets of DNA-laden chromosomes — one set inherited from the mother and one from the father — that provide the code for genetic traits like height or color.

Since a cloned animal has the same set of chromosomes as the animal that donated its cells, the clone is an exact genetic duplicate of the donor animal. Here’s how Steve Stice’s lab uses adult cells to clone cattle.

Harvest a cow’s egg — technically an oocyte — from a slaughtered cow (1) and “enucleate” it by removing the chromosomes (genetic material) (2).

Collect a skin or kidney cell from the animal to be cloned (3). Stice applies an inhibitor he developed to synchronize donor cell development and to increase the cloning success rate (4).

Transfer the cell into the enucleated egg, and fuse them with an electrical jolt (5).

Add calcium to mimic the fertilization signal of the sperm (5), so the fused egg begins to behave like a fertilized egg .The fused egg begins to grow and divide (6).

At seven days, a hollow ball of cells or blastocyst-stage embryo forms (7), which is ready to be non-surgically implanted into a surrogate mother (8).

Nine months later, a cloned calf is born (9).

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THE UNIVERSITY OF GEORGIA RESEARCH MAGAZINE : www.researchmagazine.uga.edu