筍殼魚在空氣中的排氨

筍殼魚（Oxyeleotris marmoratus）魚體組織中氨的濃度在空氣中72小時保持不變。

氨排泄在實驗中的速度降低到大約五分之一，相對於浸沒水中控制組。氨沒有轉化為尿素在空氣中時，沒有顯著增加在筍殼魚組織中的尿素含量。

此外，暴露在空氣中24小時後比浸沒水中，魚的尿素排泄率降低到五十分之一。有一個顯著增加肌肉谷氨酰胺含量達到高峰，持續48小時。在谷氨酰胺含量的增加可在空氣中降低氨和尿素排泄量，肝谷氨酸脫氫酶（胺化）和谷氨酰胺合成酶在實驗中具體活性增加了三倍和三十倍，與浸沒水中對照組相比。

因此，筍殼魚似乎是第一個已知的硬骨魚，在空氣暴露中透過激活肝谷氨酰胺合成解毒內部產生的氨。

Ammonia levels in various tissues of the marble goby (Oxyeleotris marmoratus) remained constant throughout a 72h period of air exposure.

The rate of ammonia excretion in these experimental fish decreased to approximately one-fifth of that of the submerged control. Ammonia was not converted to urea during air exposure because there were no significant increases in urea content in the tissues.

Also, urea excretion rate was lowered to one-fiftieth that of the submerged fish. After 24 h of air exposure, there was a significant increase in muscle glutamine content, which peaked at 48 h. The increase in glutamine content could account for the decreases in the amounts of ammonia and urea excretion during air exposure. The specific activities of hepatic glutamate dehydrogenase (amination) and glutamine synthetase in these experimental fish increased threefold and thirtyfold, respectively, in comparison with the submerged controls.

Thus, the marble goby appears to be the first known teleost that responds to air exposure by activating hepatic glutamine synthetase to detoxify internally produced ammonia.

資料來源 ：

THE MARBLE GOBY OXYELEOTRIS MARMORATUSACTIVATES HEPATIC
GLUTAMINE SYNTHETASE AND DETOXIFIES AMMONIA TO GLUTAMINE DURING AIR EXPOSURE

L. Y. JOW, S. F. CHEW, C. B. LIM, P. M. ANDERSON AND Y. K. IP

Department of Biological Sciences, National University of Singapore, Kent Ridge, Singapore 119260, Republic of Singapore,
Biology Division, School of Science, National Institute of Education, Nanyang Technological University, Bukit Timah, Singapore 259756, Republic of Singapore and Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Minnesota, Duluth, MN 55812-2487, USA

Accepted 13 November 1998; published on WWW 11 January 1999