A P1-BASED PHYSICAL MAP OF THE DROSOPHILA EUCHROMATIC GENOME

A PCR-based sequence-tagged site (STS) content mapping strategy has be en used to generate a physical map with 90% coverage of the 120-Mb euc hromatic portion of the Drosophila genome. To facilitate map completio n, the bulk of the STS markers was chosen in a nonrandom fashion. To e nsure that all contigs were localized in relation to each other and th e genome, these contig-building procedures were performed in conjuncti on with a large-scale in situ hybridization analysis of randomly selec ted clones from a Drosophila genomic library that had been generated i n a P1 cloning vector. To date, the map consists of 649 contigs with a n STS localized on average every 50 kb. This is the first whole genome that has been mapped based on a library constructed with large insert s in a vector that is maintained in Escherichia coli as a single-copy plasmid.