Pulsed-field gel electrophoresis

Abstract

Pulsed-field gel electrophoresis is a technique making its first impact at the International Congress of Genetics meetings. Much progress has been made since the first demonstrations of this revolutionary technique separating intact yeast chromosomes (Schwartz et al. 1983). Currently, pulsed-field gels can separate and allow the analysis of DNA fragments as large as several thousands of kilobase (kb) pairs, and their use is rapidly increasing in both plant and animal genetics. As yet, pulsed-field gel electrophoresis is not able to separate intact mammalian chromosomes, which range in size from 30 to 180 Mb. However, it is forming the basis of major efforts from many laboratories to restriction map entire mammalian chromosomes using enzymes, containing CpG recognition sequences, that cleave infrequently in mammalian DNA generating DNA fragments up to 4 Mb in length. These maps are used as a preliminary step in the isolation of genes that have potentially informative mutant alleles, or to provide information on the structural basis of chromosome abnormalities. This workshop considered the practicalities of using pulsedfield gel electrophoresis to r&striction m p entire m m m l i a n chromosomes. However, it was noted that attempts to restriction map chromosomes require concurrently the generation of a large number of chromosome-specific DNA markers and some means of rapid genetic mapping to localize markers to specific chromosome subregions.