This research project proposes to use a selective screening procedure to accumulate large numbers of mutations which specifically affect myogenesis in Drosophila. These mutant genes will be located in the genome in order to determine if there is any spatial organization of genes controlling the development of the muscles and will be introduced into the genome in various combinations in an effort to discover functional organization of genes controlling myogenesis. It will be determined whether or not the same genes control the development of muscle during embryogenesis and metamorphosis. Various techniques will be used to discover what steps in myogenesis are affected by these mutations. These include light and electron microscopy, histochemistry, an analysis of muscle proteins, and an investigation of the ability of these mutant tissues to grow in vitro.