A rapid and efficient procedure for the purification of DNA from agarose gels

DNA fragments electrophoresed through a horizontal agarose slab gel can be recovered by inserting strips of filter paper backed by dialysis membrane into slits cut in the gel in front of the DNA bands and continuing electrophoresis until the DNA is collected in the paper. Elution of the DNA from the filter paper is then achieved by low-speed centrifugation. Recovery well above 70% is routinely obtained with this technique and the DNA recovered is biologically active and can be recleaved, ligated, labeled in vitro by nick translation and hybridized to RNA.