A transgenic approach to studying imprinted genes: modified BACs and PACs.

The advantages of using large genomic clones in the analysis of imprinted genes is described in Chapter 4 with particular reference to yeast artificial chromosomes (YACs). These contain on average 500-600 kb of DNA but can be much larger (>1 Mb). YACS are propagated in yeast and are therefore amenable to genetic modification by homologous recombination, and there are now many examples of their use to generate transgenic mice. This chapter describes a relatively new strategy for using large genomic clones that relies on Escherichia coli-based systems.