Meeting Abstract
P1.109 Jan. 4 Growth hormone family receptors in a model teleost: quantitative PCR assay development, tissue distribution, and physiological regulation of GHR-1, GHR-2, and PRLR in Mozambique tilapia, Oreochromis mossambicus PIERCE, AL*; FOX, BK; DAVIS, LK; VISITACION, N; KITAHASHI, T; HIRANO, T; GRAU, EG; Univ Hawaii; Univ Hawaii; Univ Hawaii; Univ Hawaii; Monash Univ, Malaysia; Univ Hawaii; Univ Hawaii piercea@hawaii.edu
Piscine pituitary growth hormone family peptide hormones (growth hormone, prolactin and somatolactin) regulate essential physiological functions including osmoregulation, growth, and metabolism. The effects of these hormones are mediated by plasma membrane receptors. A prolactin receptor (PRLR) and two putative growth hormone receptors (GHR-1 and GHR-2) have been identified in several teleost species. Recent phylogenetic analysis and binding studies suggest that GHR-1 is a receptor for somatolactin. We sequenced the Mozambique tilapia GHR-2, and developed quantitative real-time PCR assays for the three receptors. PRLR was most highly expressed in the gill, kidney, intestine, and skin, consistent with the osmoregulatory functions of prolactin. PRLR expression was very low in the liver. GHR-1 was most highly expressed in the fat, liver, and muscle, suggesting a metabolic function. GHR-1 expression was also high in the skin, consistent with a function in chromatophore regulation. GHR-2 was most highly expressed in the muscle, followed by heart, testis, and liver, consistent with functions in growth, metabolism and reproduction. We compared gill, kidney, and liver receptor mRNA levels between freshwater- and seawater-adapted tilapia. PRLR was elevated in the gill in freshwater, consistent with prolactin�s function in freshwater osmoregulation. We compared liver, muscle, fat, and pituitary receptor mRNA levels between fed and fasted (4 weeks) tilapia. The effects of fasting on receptor expression will be presented. (Supported by NRI Competitive Grant 2006-35206-16447 from the USDA CSREES)
