Discontinuous polyacrylamide gradient agarose gels resolve a wide range of restriction fragments and optimize the efficiency of nucleic acid transfer

Abstract A vertical electrophoresis procedure utilizing a discontinuous polyacrylamide gradient agarose gel was developed to resolve DNA fragments ranging in size from over 50 kb to less than 300 bp in length. The gel consisted of a polyacrylamide plug at the base of the gel followed by a gradient of agarose ranging from 0.3 to 0.9%. Restriction fragments migrated shorter distances than in a comparable polyacrylamide-0.3% agarose gel, and small fragments were retained. Southern transfer of DNA fragments from the gradient gel onto nitrocellulose was more efficient than transfer of fragments using a nongradient gel.