Novel bacteriophage lambda cloning vector.

A simple method for generating phage collections representing eukaryotic genomes has been developed by using a novel bacteriophage lambda vector, lambda 1059. The phage is a BamHI substitution vector that accommodates DNA fragments 6-24 kilobases long. Production of recombinants in lambda 1059 requires deletion of the lambda red and gamma genes. The recombinants are therefore spi- and may be separated from the spi+ vector phages by plating on strains lysogenic for bacteriophage P2. Random fragments suitable for insertion into lambda 1059 are obtained by partial digestion of high molecular weight eukaryotic DNA with Sau3a. This restriction enzyme cleaves at the sequence G-A-T-C and leaves a 5'-tetranucleotide "sticky end." Because G-A-T-C extensions are also produced by BamHI cleavage, these fragments may be annealed directly to BamHI-cleaved lambda 1059. By using these methods, a set of clones covering the entire Caenorhabditis elegans genome was constructed. DNA segments which include the unc-54 myosin heavy chain gene have been isolated from this collection.