Regulation Of Protein Metabolism By Cellular Signaling Pathways In Stressed Fish

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Animals produce soft tissues by synthesizing proteins and retaining a proportion as protein growth; the remainder being degraded and the amino acids recycled. These interrelated processes of protein synthesis, protein growth and protein degradation are collectively called protein metabolism. In fish, protein metabolism is highly sensitive to a wide variety of biotic and abiotic factors including temperature, pollution, food availability and probably to the individual's social status. Protein metabolism is highly regulated and, at the cellular level, this regulation involves the signal transduction pathways. In the last decade, our understanding of the roles of the signal transduction pathways in the control of protein metabolism has greatly progressed however much remains to be understood, especially in non-mammalian animals. The long-term goals of my research program are; 1) to characterize the cellular mechanisms involved in the control of protein metabolism and 2) to use these cellular mechanisms to extract information on the physiological status of animals that are either farmed or collected from the wild. In the next five years, I will apply a multidisciplinary approach to study the control of protein metabolism using the growth depression observed in subordinate fish following the establishment of social hierarchy as a model. This growth depression is primarily caused by a dramatic reduction of food consumption however the stress hormone cortisol also plays a role in it. The short term objectives of the proposed research activities are 1) To characterize the cellular mechanisms involved in the adjustments of protein metabolism during starvation, 2) To characterize the effects of acutely and chronically elevated cortisol on protein metabolism, 3) To evaluate the respective contribution of starvation and chronically elevated cortisol on growth depression in subordinate fish. This research program addresses an important aspect of fish physiology that is highly relevant to current industrial (aquaculture) and environmental issues.