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(356) EXPRESSION OF GROWTH HORMONE IN THE GOLDFISH GONADS AND OTHER PERIPHERAL TISSUES. Ajamian, Farzam1, Wong, Sui-Lam1, Habibi, Hamid1, 1 University of Calgary, Department of Biological Sciences, Calgary, AB, Canada ABSTRACT- The presence of growth hormone (GH) is essential for normal stimulation of growth in vertebrates. While it is well established that GH is primarily produced in the pituitary gland, a number of studies have demonstrated the expression of GH gene in different extrapituitary sites in both neonates and adults in mammals as well as a few non-mammalian species. However, very limited information is available in fish. Previous studies in goldfish demonstrated the presence of two molecular forms of GH, one with five Cys residues (gfGH-I) and the other with four Cys residues (gfGH-II). No information is currently available on functional importance of the two molecular form of gfGH-I and gfGH-II in goldfish. Nor do we know about their specific control other than both gfGH-I and gfGH-II are stimulated by hypothalamic peptides in the goldfish pituitary. Using reverse transcription-polymerase chain reaction (RT-PCR), the expression of GH was investigated in a number of extrapituitary tissues including ovary and testis, as well as brain, muscle, heart and liver in adult goldfish. The PCR amplified transcripts were all sequenced and confirmed to be GH molecules. Although GH expression was observed in all tissues investigated, significant differences were observed in the level of PCR-amplified transcripts. By far the highest expression was observed in the pituitary. High level of GH expression was also observed in the heart and muscle, followed by ovary and testis. In comparison, the expression of GH was found to be low in the goldfish liver and just above detection level in the brain and gut. While we are uncertain about the physiological significance of extrapituitary GH expression in fish, the findings provide a basis for further investigation of tissue specific expression and regulation of different forms of GH in goldfish. This study was funded by NSERC. KEY WORDS: Gene Expression, Pituitary gland, Growth hormone , Goldfish |
