Pulsed field gel electrophoresis and investigations into mammalian genome organization.

Pulsed field gel (PFG) electrophoresis can resolve DNA molecules as large as several million base pairs (mbp) in size (Schwartz and Cantor, 1984; Carle and Olson, 1984; Gardiner et al. 1986; Carle et al. 1986; Chu et al. 1986; Clark et al. 1988; Anand, 1986; Gardiner and Patterson, 1988; Orbach et al. 1988). This is in contrast to conventional electrophoresis where the practical upper limit is 50-100 kb (lkb=10bp). This increased resolving power has especially important ramifications for the study of complex genomes, allowing new questions to be asked and providing faster solutions to older ones. It is now possible, for example, to examine gene organization, physically link and size mammalian genes, and search for translocation breakpoints by means that are far more rapid and reliable than conventional methods. PFG has made the cloning of large genes, or groups of genes, possible via the yeast artificial chromosome (YAC) method (Burke et al. 1987), and it also makes the mapping of the human genome a realistic endeavour. The purpose of this commentary is to discuss how this technique can be applied to the study of mammalian genomes, and to describe some of the insights into human genome organization that are beginning to emerge.