Uniformly spaced banding pattern in DNA sequencing gels by use of field-strength gradient.

A method is described for casting and operating ultrathin wedge-shaped field-strength gradient gels for DNA sequencing. One of the gradients results in a uniformly-spaced oligonucleotide banding pattern from 60 to 300 nucleotides in a 53 cm long 4% polyacrylamide gel. From these field-strength gradient gels, more sequencing data can be obtained with greater confidence than from gels with uniform thickness. The gel-casting method is fast and simple. At 2.5 kV two gels can be run simultaneously in 2 h with the same power supply.