9723529 Chen Insulin-like growth factors (IGFs) or somatomedins are mitogenic and anabolic peptize hormones that play an important role in growth and differentiation of vertebrates. Results of numerous studies in mammals suggest that while IGF-II is produced in the liver and several other pre-natal and neonatal tissues, IGF-I is primarily produced in the post-natal livers under the modulation of growth hormone (GH). Although the molecular mechanism underling the regulation of IGF-I and IGF-II genes has been extensively studied in mammals, very little has been done in lower vertebrates like fish. The PI's research objectives are to investigate else regulation of IGF gene expression and the involvement of IGF-I and -II in somatic growth, using rainbow trout as model experimental animals. In the previous funding cycle, the PI has isolated and characterized IGF-I and cDNA ahead their genes, and has shown that expressions of these two genes are regulated by growth hormone (GH). In the present application, the PI proposes to study: (1) the biological relevance of IGF I and II mRNA expression during the early embryonic development, and (2) the involvement of CCAAT cis-acting element and its hepatic nuclear binding protein (C/EBP) on the regulation of IGF gene expression. Fish represent the largest and the most diverse group of vertebrates and their unique evolutionary position relative to other vertebrates and their ability to adapt to a wide variety of environments make them ideal for studying the molecular mechanisms of growth regulation. Therefore, results of these proposed studies will advance the knowledge of vertebrate JGF gene regulation and expression in a way that is both easily generalized to vertebrate models, and will provide a phylogenetic perspective that has proved useful in the studies of other complex biological phenomena. Furthermore, results of these studies will be applied to commercial aquaculture.
