This project provides one year of partial subsidy for the Mid- America Drosophila Stock Center. Drosophila, or "fruit flies," are essential experimental animals which are used extensively in genetics research. The Mid-America Center maintains 4,061 genetic strains of the most important fruit-fly species, Drosophila melanogaster, which are distributed to institutions around the world for research and teaching purposes. From 1985 to 1989, over 12,000 requests for flies were received and nearly 59,000 stocks were mailed to all 50 states and over 50 foreign countries. These stocks include basic mutants as well as complex mutant combinations and chromosome rearrangements. It is essential that such stocks be maintained because they represent many man-years of genetic research and are difficult, and in some cases impossible, to re- isolate or re-synthesize. In addition, it is much too expensive for each researcher utilizing Drosophila to maintain the full range of stocks it envisions it will need. It is certain that curtailment of the activities of the Mid-America Center would seriously affect genetics research worldwide.