Hybridization within agarose gels using oligonucleotide probes has bee
n described in several publications; genomic DNA probes, however, have
been used rarely and only with limited success. Here we present a sim
ple and convenient procedure for in-gel hybridization using radiolabel
ed genomic DNA fragments. The protocol was improved by the use of form
amide in the hybridization as well as in the washing step. This method
was compared with the conventional Southern blotting technique and wa
s shown to produce good results in restriction pattern analysis, as we
ll as in chromosomal localization with the help of pulsed field gel el
ectrophoresis.