The long-term objectives of this study are to define lipid mobilization, transport and metabolism in insects and to characterize the biochemical processes involved in formation of the insect egg. The relationship of these studies to human health is two fold. First, the processes of mobilization, transport and metabolism of lipids in insects has direct counterpoints in mammals, and study in the invertebrate animal model can provide new insight into the mammalian processes. Second, detailed studies of egg production and lipid metabolism in insects can suggest new general methods of insect control that will be applicable to insect vectors of disease. Using the tobacco hornworm, Manduca sexta, we will study lipid mobilization in an in vitro fat body system. Factors involved in mobilization (lipoproteins, apoproteins, lipid transfer factor, adipokinetic hormone) will be defined by varying their structure and lipid composition. Specific delivery of lipids to different peripheral tissue, especially flight muscle and prothoracic glands (site of steroid hormone synthesis) will also be studied in vitro. Factors involved in specific lipid delivery (e.g. diacylglycerol to flight muscle, cholesterol to prothoracic glands) will be defined and characterized. Endocytotic receptors in the ovary that are responsible for selecting specific hemolymph proteins and internalizing them in the oocyte will be isolated, characterized, cloned and sequenced. This should provide information on evolution and diversity of membrane receptors. Specific inhibitors (antibodies, peptides) of endocytosis will be obtained and used to produce eggs lacking specific proteins in order to determine the function of these materials in developing embryos.
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