| 摘要: |
| 采用微型冰点渗透压仪和酶学分析的方法测定了褐牙鲆幼鱼由盐度30向低盐(24、18、12、6)适应过程中血浆渗透压和鳃丝Na+-K+-ATPase活力的变化。结果表明,盐度对褐牙鲆幼鱼血浆渗透压和鳃丝Na+-K+-ATPase活力都有显著的影响(P<0.05)。盐度变化后,各实验组褐牙鲆血浆渗透压、鳃丝Na+-K+-ATPase活力均呈现出不同程度的下降趋势,且随着盐度变化的增加而增大。在6d内,盐度为18、12和6实验组血浆渗透压呈峰值变化,在3d时达到最小值;6d后,各实验组血浆渗透压趋于稳定;而鳃丝Na+-K+-ATPase活力在6d时达到最小值,9d后,各实验组褐牙鲆鳃丝Na+-K+-ATPase活力基本趋于稳定状态,而且在高渗环境(S>14.97)中鳃丝Na+-K+-ATPase活力与外界盐度大小呈正比,在低渗环境(S<14.97)中与盐度呈反比。褐牙鲆幼鱼的等渗点盐度为14.97,等渗压为425.8mOsm/kg。 |
| 关键词: 盐度, 褐牙鲆, 血浆渗透压, 鳃丝Na+-K+-ATPase |
| DOI： |
| 分类号: |
| 基金项目:中国水产科学研究院基金项目, 1999-02-01号; 中国海洋大学海水养殖教育部重点实验室开放课题资助项目,200415号; 胜利油田管理局横向课题, 2005-7号。 |
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| EFFECTS OF SALINITY ON PLASMA OSMOLALITY AND GILL Na+-K+-ATPase ACTIVITY OF JUVINILE JAPANESE FLOUNDERPARALICHTH YS OLIVACEUS |
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PAN Lu-Qing1, TANG Xian-M ing1, LIU Hong-Yu1, TIAN Jing-Bo2
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1.The Key Laboratory of Mariculture, Ministry of Education, Ocean University of China;2.Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences
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| Abstract: |
| Changes in plasma osmolality and gill Na+-K+-ATPase activity o f juvenile Japanese flounder (Paralichthy solivaceus) w ere studied in enzymology analysis at an abrupt change in salinity from 30 to 6 at decrement of 6). The experiment was conducted in 50cm3 × 30cm3 × 40cm3 plastic tanks; each contained 50L water. The sizes and w eights of juvenile Japanese flounder were at (10.98±0.85) cm and (11.90±3.38) g, respectively at the experimental condition of pH 8.2 and temperature (18±0.5) °C. The salinity was adjusted by well-exposed tap water. Constant aeration was provided. Complete water exchange at the same temperature was conducted daily with the residual feed, excrement and dead animals removed. Daily bait was fed at 3%–4% of the body weight. Each treatment tank contained 20 fish and triplicated. The control treatment was set in the salinity of 30. Sampling was conducted at 0h, 12h, 24h, 3d, 6d, 9d and 12d since the beginning. Samples were then stored at -20°C until enzymes were assayed. The results suggest that effects of the salinity on plasma osmolality and activity of gill Na+-K+-ATPase of the fish was significant (P <0.05). Upon the salinity reduction, both plasma osmolality and gill Na+-K+-ATPase activity showed slowly downtrends. In overall, the bigger the salinity dropped, the more remarked trend appeared. In 6 days, peak values of plasma osmolality appeared at the salinity of 18, 12 and 6, and trough value appeared on the third day. 6 days after the experiment start, the plasma osmolality in every group reached their own stable state, and the enzyme activity dipped to the lowest level then resumed slowly to the their previous level. At the end of the experiment, the Na+-K+-ATPase activity in every group stabilized. The Na+-K+-ATPase activity of gill showed a positive correlation to the salinity in hyperosmotic environment (S >14.97), while a multiple correlation to the salinity in hypotonic environment (S < 14.97). The isoosmotic point of flounder was at salinity of 14.97 (isoosmotic pressure, 425.8mOsm/kg). The juvenile Japanese flounder had a great capability of acclimatize to a low salinity setting. The acclimatization had closely relation to the time but independent of salinity. Changes in Na+-K+-ATPase activity of gill (9d) was evidently lagged to the changes in plasma osmolality (6d), indicating that the osmoregulation of the flounder was not fully controlled by Na+-K+-ATPase activity in gill, some other organs such as kidney may have contributed. It is proposed that the acclimatization could consist of two phases. Phase I: short time after salinity change, the plasma osmolality declined rapidly, triggering the change in organism osmoregulation. Phase II: the plasma osmolality reverted to the level before salinity change. In a short term of a few hours, the plasma osmolality was regulated by water-salt exchange between internal and external systems. The increase in weight was because of the absorption of water. While in a longterm of several days, the flounder could regulate osmolality actively to adjustify the imbalance by reducing or stopping water adsorption, and changing skin structure, etc, among which kidney played a significant role. |
| Key words: Salinity, Paralichthys olivaceus, Plasma osmola lity, Gill Na+-K+-Tpase |
