A YAC-based physical map of the mouse genome

A physical map of the mouse genome is an essential tool for both positional cloning and genomic sequencing in this key model system for biomedical res earch, Indeed, the construction of a mouse physical map with markers spaced at an average interval of 300 kb is one of the stated goals of the Human G enome Project(1). Here we report the results of a project at the Whitehead Institute/MIT Center for Genome Research to construct such a physical map o f the mouse. We built the map by screening sequenced-tagged sites (STSs) ag ainst a large-insert yeast artificial chromosome (YAC) library and then int egrating the STS-content information with a dense genetic map. The integrat ed map shows the location of 9,787 loci, providing landmarks with an averag e spacing of approximately 300 kb and affording YAC coverage of approximate ly 92% of the mouse genome. We also report the results of a project at the MRC UK Mouse Genome Centre targeted at chromosome X. The project produced a YAC-based map containing 619 loci (with 121 loci in common with the Whiteh ead map and 498 additional loci), providing especially dense coverage of th is sex chromosome. The YAC-based physical map directly facilitates position al cloning of mouse mutations by providing ready access to most of the geno me. More generally, use of this map in addition to a newly constructed radi ation hybrid (RH) map(2) provides a comprehensive framework for mouse genom ic studies.