CLONING THE SHARED COMPONENTS OF COMPLEX DNA RESOURCES

The complex and repetitive nature of mammalian genomes limits the abil ity of conventional molecular techniques to recover sequences of inter est. Here we describe a rapid and simple procedure for the direct clon ing of sequences which are coincident between DNA mixtures of whole ge nome complexity. The system, called end ligation coincident sequence c loning (EL-CSC), can enrich coincident DNA by greater than 10(6)-fold and overcomes problems associated with repetitive elements. Applying E L-CSC to various paired DNA resources enables the facile cloning of bo th genomic markers and novel genes. To demonstrate the power of the me thod we have i) selectively purified single copy sequences from a comp lete genome, and ii) isolated gene fragments from 260 kb of cloned gen omic DNA.