Three basic techniques have emerged for making transgenic mice: two of these, retroviral infection of preimplantation embryos and the manipulation of embryonal stem cells, have attributes which make them desirable in some experiments, but the third technique, microinjection, is by far the most efficient and popular. All but one of the transgenic species described in the present volume are produced by microinjection. The isolation and manipulation of murine Embryonal Stem Cells (ES cells) and the production of chimeric mice are described in Chapters 23 and 24.
An overview of the microinjection protocol is presented here. It is specifically relevant to mice, although the essential elements are similar for all mammalian species, particularly rats. In this context, this chapter is intended to link together the individual elements of the protocol (detailed in seperate chapters) and thus provide new investigators with a summary of the various skills and facilities that are required.
There are two basic requirements for transgenic animal production, namely a healthy colony of animals and a cloned DNA sequence that will form the transgene. Both demand careful preparation if the transgenic experiment is to be successful. The establishment and care of suitable mouse and rat colonies are described in Chapters 12 and
27. Techniques for making transgene constructs are beyond the scope of this volume, and the reader is referred to one of the many manuals available that describe recombinant DNA protocols. Particular care should be given to the final steps in the purification of the DNA construct (see Chapter 11). Attention to the design of the transgene construct is crucial and is discussed in Chapter 10.
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