Microinjection transgenic animals

Fig. 1. Outline of the generation of transgenic mice via pronuclear microinjection. Transgenic animals carry the transgenes randomly integrated (hemizygous, tandems, dominant).

The production of heterologous proteins in transgenic animals has gained much attention in the recent past. The generation of transgenic animals is most often undertaken by directly microinject-ing exogenous DNA into an egg cell. In some instances, this DNA will be stably integrated into... 

In animal cloning, researchers introduce foreign DNA primarily with the use of viral vectors or microinjection. These techniques can produce transgenic animals and provide new methods for human gene therapy. 

In some circumstances the introduction of a cloning vector into a host cell is a trivial process. For example, phage vectors are designed so they introduce recombinant DNA in an infective process called transfection, and some bacteria take up plasmids unaided. However, most host cells must be induced to take up foreign DNA. Several methods are used. In some prokaryotic and eukaryotic cells, the addition of Ca2+ to the medium promotes uptake. In others, a process called electroporation, in which cells are treated with an electric current, is used. One of the most effective methods for transforming animal and plant cells is the direct microinjection of genetic material. Transgenic animals, for example, are created by the microinjection of recombinant DNA into fertilized ova. 

Fig. 3 Somatic cell nuclear transfer strategy for transgenesis. NPs can be used to delivery DNA into somatic cells, which can then be selected for gene expression and microinjected into enucleated oocytes for production of transgenic animals...

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