Control of pulsed field gel electrophoresis at short switching intervals by a microcomputer

Pulsed field gel electrophoresis allows not only the separation of very large DNA molecules (up to 10 megabase pairs) but also gives an enhanced resolution in separations of DNA in the size range of 10-100 kilobase pairs (kbp). For this application, rapid alternation of the electrical field polarity is required. Here we describe equipment for the delivery of short switching pulses that is easy and inexpensive to build and is controlled by a standard microcomputer. It has proved to be useful in the separation of lambda DNA and its fragments. Parameters for enhanced separation of 23- and 48-kbp DNA molecules at high voltage gradients (15 V/cm) are presented and shown to provide superior resolution when compared to those for conventional electrophoresis at both high and low voltage gradients.