During the last 18 hours of larval development, the salivary glands of Drosophila melanogaster larvae produce eight to ten major proteins which are used as pupal glue. The structural genes for six of these glue proteins have been mapped. They correspond, in all but one case, to polytene chromosome puffs that are active when the proteins are being synthesized. Cloned sequences corresponding to at least two and perhaps five of these loci have been isolated and used to study the structure of the genes. This proposal outlines experiments to examine the sequences flanking the glue protein gene Sgs-4 in normal and mutant strains of flies. In addition a recently identified transposable element, Nomad 93, will be further characterized and its involvement in chromosomal rearrangements investigated. Finally, newly isolated genomic clones which are complementary to salivary gland RNA will be compared with previously isolated glue protein clones and the new ones further characterized by in situ hybridization and restriction mapping.