Exploring Transformation-Associated Recombination Cloning for Selective Isolation of Genomic Regions

Mammalian genome analysis has been advanced considerably by the development of yeast artificial chromosome (YAC) and bacterial artificial chromosome (BAC) cloning systems (1 ,2 ). These techniques have made the isolation of large, random DNA fragments possible, thereby greatly simplifying the physical mapping of chromosomes. However, isolation of entire genes and specific chromosomal regions for functional studies remained a laborious process because it relies on characterization of random clones in libraries comprising YACs or BACs. Even if a YAC or BAC contains an entire gene, the specific recovery of the gene was an arduous process. Often a gene is available as a contiguous set of fragments that must be pieced together.