臺灣博碩士論文加值系統

本研究以莫三比克吳郭魚為研究材料,探討皮質醇對發育中的仔魚水平衡之影響.
仔魚在經10ppm皮質醇浸泡處理24小時後,進行濕重,含水量及喝水速率的測量.
結果顯示皮質醇處理組的仔魚含水量,濕重及喝水速率較控制組低.而乾重,體長及卵黃囊直
徑,並無顯著差異,表示皮質醇並未對仔魚發育造成抑制.為進一步證實皮質醇對仔魚喝水速
率有抑制性影響,我們將仔魚以皮質醇處理不同時間後進行喝水速率及含水量的測定.
結果顯示皮質醇處理4小時後對海水適應仔魚喝水速率有抑制效果,而在14小時後導致
仔魚含水量的下降.此外,淡水適應仔魚喝水速率也受皮質醇的影響.淡水仔魚經皮質醇
處理8小時後喝水速率降低約50%,而含水量即使在處理32小時後仍未受影響.這些結果顯示
皮質醇對仔魚喝水行為有抑制性影響.

The present study is to study the possible role of cortisol in water balance
in tilapia (Oreochromis mossambicus)larvae. The seawater(SW)- adapted larvae
were immersed in 10 ppm cortisol for 24 h, then wet weight, water cotent, and
drinking rate of larva were determined. Cortisol-immersed group showed lower
values in wate content, wet weight and drinking rate than those of control
group. However, no significant difference was found in dry weight, body length
and yolk-sac diameter,indicating that no developmental delay occurred. To test
the hypothesis that the decreased water content in cortisol-treated group is
due to the inhibition of water drinking by cortisol, we examined the changes
in drinking rater and water content after various time of cortisol treatment
in both freshwater- and SW- adapted larvae. Compared to
control group, decrease
of drinking rate was found after 4h cortisol immersion in SW-adapted larvae,
however water content was decreased at later time of 14h. Interestingly, we
found drinking rate also decreased in FW-adapted larvae after 8h at the degree
of 50%, but still no difference in water content after 32h exposure. These
findings suggest that drinking activity may be inhibited by cortisol in both
FW- and SW- adapted tilapia larvae.