碩士 / 國立臺灣大學 / 漁業科學研究所 / 101 / Ca2+ is a vital element that serves various physiological roles in vertebrates. In vertebrates which include fish, Ca2+ homeostasis is an important issue. Freshwater fish normally face fluctuating Ca2+ conditions, and therefore it is critical for fish to control Ca2+ flow (into or out) of their bodies.
Parathyroid hormone has been well documented to be a vital endocrine regulating Ca2+ uptake in mammals, however, remains largely unclear in teleosts. In present study, zebrafish (Danio rerio) was used as a model to investigate the functions of parathyroid hormone on Ca2+ uptake. Zebrafish embryo acclimated to low-Ca2+ freshwater stimulated parathyroid hormone 1 (pth1) expression, but no effects in parathyroid hormone 2 (pth2) expression. The Ca2+ content and the expressions of epithelial calcium channel (ecac) were increased by exogenous human PTH (1-34) but no significant differences on other Ca2+ transporters expression. After the injection of PTH1 cRNA, the ecac expression was stimulated but this phenomenon was not found in PTH2 cRNA injection. Morpholino knockdown of the PTH1 showed Ca2+ uptake function decreased by inhibiting ecac expression. Taken together, PTH1 stimulates Ca2+ uptake by upregulating ecac, and PTH2 seems to be no effects on Ca2+ handling in zebrafish.
Extracellular calcium-sensing receptor (CaSR) could sense Ca2+ level of body fluid and regulate endocrine system to maintain Ca2+ homeostasis in mammals; however, the role of CaSR on Ca2+ handling of fish is still unclear. Morpholino knockdown of zebrafish CaSR was found to stimulate Ca2+ content and ecac expression. To further explore the mechanism behind this, we found gene expressions of stanniocalcin-1 (stc-1) and pth1 were modulated differentially in CaSR-deficient morphants. In conclusion, CaSR downregulates ecac expression decreasing Ca2+ uptake functions and this control pathway is suggested to mediate the secretion of STC-1 and PTH1.
| Identifer | oai:union.ndltd.org:TW/101NTU05451006 |
| Date | January 2012 |
| Creators | Che-Hsien Su, 蘇哲賢 |
| Contributors | Pung-Pung Hwang, 黃鵬鵬 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 61 |
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