9502221 Davisson This award renews NSF support of the Mouse Mutant Stocks Center (MMSC) at The Jackson Laboratory, an internationally renowned center for genetic studies of the laboratory mouse. The mouse is the primary experimental system for study of a variety of aspects of mammalian genetics and development. The MMSC has two missions: 1) to maintain and distribute strains of mutant mice and information about the strains to the scientific community, and 2) discover and characterize new spontaneous mutations in the mouse. Approximately 950 spontaneous mutations have been detected in the mouse; of these, 121 mutations are represented by the stocks maintained by the MMSC. In addition, the large breeding colonies of genetically well-characterized mice maintained at The Jackson Laboratory are a particularly convenient and inexpensive source of new spontaneous mutations. Each year, the NSF support for this collection benefits a large number of academic, non-profit, government and industrial researchers who request with known or newly detected mutations. ***