How to Make Your Own Transgenic Animal
While the technique of cloning has changed dramatically over the years, the basic principle remains the same [2]. Take a blood clotting factor protein we would like to clone in a cow as an example. Essentially, the gene for the factor would be linked to a promoter specific for a milk protein. This promoter is responsible for ensuring that the gene is only expressed in the milk of the animal. Many copies of this promoter-gene combo are then introduced into a cow’s egg, which is allowed to develop in a surrogate animal (see Figure 1). A technique called ‘Pronuclear injection’ is used to do this and involves injecting the DNA directly into fertilized eggs using a very fine glass needle ( transfection).