9307051 Horodyski Metamorphosis in insects is regulated by juvenile hormone (JH), a compound produced in the corpora allata (CA), a neurohaemal organ attached to the brain by the nerve fibers. Metamorphosis is prevented if the JH levels in the blood are high during a molt. Besides controlling metamorphosis, JH also regulates completely separate physiological processes in the adult female insect, sexual maturation and egg development. In order to control these functions, the levels of JH fluctuate in a characteristic manner during development. JH levels are regulated both by the control of its synthesis by the CA and the control of its degradation by catabolic enzymes present in the blood. Dr. Horodyski wants to further understand the regulation of JH synthesis by the CA. It has previously been shown that JH synthesis is positively and negatively regulated by neuropeptides synthesized in the insect brain. One of these peptides, allatotropin (Mas-AT), has been purified, sequenced and shown to stimulate JH synthesis in CA of adult insects of the order Lepidotera (butterflies and moths). He has isolated the gene for Mas-AT, and has begun to characterize the structure of this neuropeptide and the control of its synthesis using molecular biological techniques. These methods are much more sensitive than traditional biochemical approaches when studying peptides that are present in such small amounts. He has shown that this is synthesized as as part of larger precursor which contains other peptides. The functions of these peptides are not yet known. The Mas-AT gene is expressed in the brain and in the nerve cord, and the mRNA is present during larval life and during adult development. Its presence suggests another role besides the control of JH synthesis, since Mas-AT was inactive in stimulating JH synthesis in larval CA. He will identify the cells in the times in which the gene is expressed. He will initiate studies to characterize the receptor protein which med iates the cellular response to Mas-AT, and to define the target cells for the action of this peptide. ***
