Insects are encased in a semi-rigid exoskeleton. To allow for growth and metamorphosis, periodically insects molt and shed their old exoskeleton. After each molt, the newly formed exoskeleton usually is soft, flexible, and lacks physical strength to provide protection. Insects cannot survive without the proper hardening of the exoskeleton after each molting cycle. It has been reported that a brain neuropeptide regulates the cuticular hardening process. Despite many efforts over the past four decades, a functional neuropeptide responsible for insect cuticular hardening has not been cloned and characterized successfully. Using a specific monoclonal antibody, a 56 kDa neuropeptide (the p56) has been identified and localized to a pair of posterior lateral neurosecretory cells in the brain of the housefly, Musca domestica. Preliminary results from developmental and functional analyses suggest that the p56 could be a putative neuropeptide responsible for cuticular hardening. Dr. Song proposes to use biochemical and molecular techniques to (1) purify the p56 from the model insect, Drosophila melanogaster, for partial amino acid sequencing, (2) clone and characterize the p56 gene, (3) investigate developmental profiles of the p56, and (4) identify the role of the p56. Successful completion of the proposed research will lead to identifying the p56 neuropeptide gene and determining its role in cuticular hardening. Elucidation of the role of the p56 neuropeptide will add important new knowledge about the regulation of insect growth and development, and should be helpful in the design of biorational control agents to disrupt the cuticular hardening process in insects. This work will also result in graduate and undergraduate student training.