A simple method for filter hybridization of labeled restriction fragments excised from gels

Labeled DNA restriction fragments excised from agarose or bisacrylylcystamine-acrylamide gels can be used for hybridization to nitrocellulose-bound DNA without eliminating the gel matrix. A gel slice containing the labeled fragment is excised, dissolved by heating at 105 degrees C (in the presence of beta-mercaptoethanol for bisacrylylcystamine-acrylamide gels), and added to the hybridization mixture. The presence of agarose or polyacrylamide in the solution does not inhibit hybridization. The method is simple, rapid, and allows complete recovery of the probe.