| Summary: | Thesis (M.Sc.)--Memorial University of Newfoundland, 2008. Biology Includes bibliographical references (leaves 100-111) In fish, as in all vertebrates, feeding is regulated by complex interactions between brain and peripheral hormonal signals. Brain signals include neuropeptide Y (NPY) and cocaine-amphetamine-regulated transcript (CART), which induces and decreases food intake, respectively. Cholecystokinin (CCK) is a peripheral hormone produced by the intestine that inhibits appetite. The winter flounder, Pleuronectes americanus (Teleostei) and the winter skate, Raja ocellata (Elasmobranchii) are two bottom-dwelling marine fish species inhabiting the coasts of Newfoundland. Both species undergo seasonal cycles in feeding and growth. Nothing is known about the structure or function of NPY, CART and CCK in these species or about the role that these peptides might have in mediating seasonal feeding patterns. In order to characterize NPY, CART and CCK in winter flounder and winter skate, I have identified cDNAs encoding these hormones in both species using RT-PCR and rapid amplification of cDNA ends (RACE). Tissue distribution studies using RT-PCR show that all three peptides are expressed in brain and peripheral tissues, including gut. Gene expression quantification using real-time RT-PCR indicates that these peptides might be involved in nutritional and seasonal feeding adaptations in these two species.
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