| Summary: | 碩士 === 國立嘉義大學 === 水產生物學系研究所 === 94 === Abstract
It’s undoubtedly that higher hardness in water enhanced the Cd-resistance, and the higher concentration of Na was related with greater Cu-tolerance in fish. However, most of these studies were less discuss and absent direct evidences to explain the reasons. Therefore, there are two objectives in this thesis (1) if higher Cd-resistance was effect by metallothionein expression; (2) external Na and Ca treatment decreased heavy metal accumulation upon Cu and Cd exposure, respectively. Tilapia larvae ( H3 stage : 3 d post hatch) as sample, and treated with 0 (control), 40 ppb Cd (plus Cd), 40 ppb with 80 ppm Ca (plusCd/plusCa), and with 80 ppm Ca (plusCa), respectively. Besides, tilapia larvae treated with 0 (control), 75 ppb Cu (plusCu), 75 ppb Cu with 12 ppM Na (plusCu/plusNa), and with 12 ppM Na (plusNa), respectively. Results of plusCd/plusCa and plusCu/plusNa treatment showed the highest MT expression, the lowest Cd or Cu accumulation, decreased the inhibition of growth in larvae by Cd or Cu and less impact on Na-K-ATPase secretion cells. According to these results, we suggested that effects of hypercalcium and hypersodium in enhancing of Cd- or Cu- resistance since (1) enhanced the MT expression (2) decreased the heavy metal accumulation (3) increased the Ca content of larvae, and (4) less impact on Na-K-ATPase secretion cells by Cu and Cd.
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