The cloning process
Holstein World: Walk us through the basic cloning process – beginning with genetic preservation of the animal and leading up to the clone’s first month of life.
Trans Ova Genetics: A clone is a genetic twin of the original (donor) animal. The donor provides the tissue sample from which a cell line is made. The clone has the exact same DNA – genetic material – as the donor. There is no genetic manipulation (genetic engineering or modification) involved.
Trans Ova Genetics starts the process by obtaining cells from the donor animal to be cloned. We prefer to use an ear biopsy, including the cartilage found within the ear.
This sample is deconstructed into small pieces and put into culture media designed to reproduce copies of the diploid cells of the animal. Diploid cells contain two sets of chromosomes, one set from the animal’s dam, and one set from the sire. These cells are cultured for two weeks, or until there is a significant amount of cells to be frozen down. They are placed into multiple storage vials and are then frozen and stored in liquid nitrogen. At least 20 million cells are frozen per sample. These cells can be re-cultured at any time to produce more cells, thus creating an infinite supply of cells from the donor animal. This alone is a genetic preservation, the first step in cloning.
To continue the cloning process, one vial of cells will be thawed. These cells will be placed individually into an oocyte (egg) that has been obtained from a host cow’s ovaries. The nucleus – which includes the DNA – of this oocyte has been removed. Without the nuclear material, the cell is basically cytoplasm. The diploid cell from the donor animal is inserted along side this cytoplasm within the shell of the oocyte. An electrical current is then passed through the media containing the oocyte, and the diploid cell fuses to the cytoplasm, a process know as electro fusion. The diploid cell, containing the original animal’s DNA, will now cleave and divide - like a conventionally created embryo would - and develop into a seven to eight day old embryo.
Then, the embryo is transferred into a synchronized, health-certified recipient cow. The resulting cloned calf will have identical DNA to the original animal that contributed the cell line. The calves will be genetically identical to the original animal; however, they may differ slightly in appearance. In Holsteins, for example, the color patterns will not be identical.