碩士 / 國立臺灣大學 / 漁業科學研究所 / 91 / The previous study showed that black porgy（Acanthopagrus schlegeli）and tilapia（Oreochromis mossambicus）showed reverse patterns in the gill of Na+,K+-ATPase upon salinity challenges. Hence, we hypothesize that black porgy and tilapia exhibit different mechanisms of osmoregulation. To test the hypothesis, the experiment were focused on the comparisons in ion balance, water balance and morphology of MR cells between balck porgy and tilapia acclimated to fresh water (FW).
Whole-body chloride content in FW black porgy is significant lower than that in FW tilapia. However, there is no significant difference in calcium or sodium content between FW black porgy and FW tilapia. The chloride influx in FW black porgy is significantly lower than that in FW tilapia, but no significant difference in the chloride efflux was found between the 2 species. As a result, chloride net flux is negative in FW black porgy but is positive in FW tilapia, suggesting differences between the two species in the chloride uptake mechanism in FW. FW black porgy and FW tilapia have no significant difference in water drinking rate or in calcium influx. The apical openings of gill MR cells in FW black porgy are all wavy-convex type, while shallow-basin and deep-hole types occur in gills of FW tilapia. FW black porgy has more numerous MR cells than does FW tilapia. The more MR cells with wavy-convex apical openings (i.e., larger apical surface area) is associated with the higher gill Na+,K+-ATPase activity in FW black porgy. Taking all together into account, FW black porgy seems to be more sensitive to environmental chloride concentrations than FW tilapia. Black porgy may have to develop more MR cells with larger apical surfaces in order to absorb sufficient chloride from normal FW, but a lower chloride influx suggests a different chloride uptake mechanism with lower efficiency in black porgy comparing with that in tilapia.
| Identifer | oai:union.ndltd.org:TW/091NTU00451013 |
| Date | January 2003 |
| Creators | Yu-Chun Wang, 王郁峻 |
| 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 | 54 |
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