Efficient screening of recombinant DNA junctions afforded by probing with synthetic "bridge" oligonucleotides.

Procedures have been developed which simplify and expedite the screening of recombinant DNA constructions for those which only exhibit the desired DNA-DNA junctions. A synthetic DNA oligonucleotide designed to span (or "bridge") sequences around correct restriction enzyme junctions was used as a hybridization probe for the rapid identification of those sequences in several molecular cloning methodologies. It facilitated analyses of the products of random ligation reactions, as well as constructions harbored in bacteria and bacteriophage. "Bridge" probes, [32P]-end-labeled to very high specific activity, remained useful after several hybridizations and often circumvented lengthy restriction analyses.