Aerobic and anaerobic metabolism in oxygen minimum layer fishes: the role of alcohol dehydrogenase
Aerobic and anaerobic metabolism in oxygen minimum layer fishes: the role of alcohol dehydrogenase
复制标题
含氧最低层鱼类的有氧和无氧代谢：乙醇脱氢酶的作用
DOI：
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发表时间：
2012
影响因子：
2.8
通讯作者：
M. Clarke
中科院分区：
文献类型：
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作者：
J. Torres;M. Grigsby;M. Clarke
由于全球环流模式使海洋中层深度的水数百年不与大气接触，世界上所有海洋的中层深度都形成了最低含氧量区。在初级生产力非常高的地区，下沉有机物的微生物氧化导致中间深度的氧浓度非常低。阿拉伯海的情况就是如此，200 m处的O2浓度为零，在该深度以下数百米处保持非常低的水平（<0.1 ml O2 l-1），而在加州边界，700 m处的氧水平达到0.2 ml O2 l-1，在该深度以上和以下300 m处的沃茨的氧水平严重缺氧（<1.0 ml O2 l-1）。尽管氧含量非常低，但生活在阿拉伯海和加州边界的中层鱼类（主要是灯笼鱼）每天都会垂直迁移到低氧层，白天在氧含量最低的区域度过，晚上向上迁移到含氧量正常的沃茨。为了弄清楚鱼类如何能够在每天的最小区域逗留中生存下来，我们测试了四种酶的活性，（乳酸脱氢酶，LDH），作为无氧糖酵解的代理与传统的乳酸终点，第二个（柠檬酸合酶，CS），其指示有氧代谢，第三（苹果酸脱氢酶），其在克雷布斯循环中起作用并作为连接胞质和胞质溶胶的桥梁，以及第四种乙醇脱氢酶（alcohol dehydrogenase，ADH），其催化丙酮酸还原为乙醇的途径中的最终反应。乙醇是一种很容易被鱼类排泄的代谢产物，可以防止乳酸盐积累。ADH途径在脊椎动物肌肉中很少非常活跃;以前只在金鱼和其他能够长期厌氧的鲤科动物中观察到活性。在阿拉伯海和加州鱼类的酶套件的活动进行了比较，在同一家庭的生态类似物，具有相同的生活方式，但生活在系统中具有更高的氧气浓度：墨西哥湾和南大洋。ADH活动在阿拉伯海鱼类相似的金鱼，远远高于那些不太严重的最低限度在墨西哥湾的熟人，这表明阿拉伯海鱼类能够利用新的乙醇终点成为主管厌氧菌。反过来，加州的鱼类表现出更高的ADH活性比他们的南极亲戚。得出的结论是，ADH活性是更广泛的鱼类比以前认为，它可能发挥作用，允许垂直迁移的鱼类利用严重的氧气最低提供的避风港。
SUMMARY Zones of minimum oxygen form at intermediate depth in all the world’s oceans as a result of global circulation patterns that keep the water at oceanic mid-depths out of contact with the atmosphere for hundreds of years. In areas where primary production is very high, the microbial oxidation of sinking organic matter results in very low oxygen concentrations at mid-depths. Such is the case with the Arabian Sea, with O2 concentrations reaching zero at 200 m and remaining very low (<0.1 ml O2 l–1) for hundreds of meters below this depth, and in the California borderland, where oxygen levels reach 0.2 ml O2 l–1 at 700 m with severely hypoxic (<1.0 ml O2 l–1) waters at depths 300 m above and below that. Despite the very low oxygen, mesopelagic fishes (primarily lanternfishes: Mytophidae) inhabiting the Arabian Sea and California borderland perform a daily vertical migration into the low-oxygen layer, spending daylight hours in the oxygen minimum zone and migrating upward into normoxic waters at night. To find out how fishes were able to survive their daily sojourns into the minimum zone, we tested the activity of four enzymes, one (lactate dehydrogenase, LDH) that served as a proxy for anaerobic glycolysis with a conventional lactate endpoint, a second (citrate synthase, CS) that is indicative of aerobic metabolism, a third (malate dehydrogenase) that functions in the Krebs’ cycle and as a bridge linking mitochondrion and cytosol, and a fourth (alcohol dehydrogenase, ADH) that catalyzes the final reaction in a pathway where pyruvate is reduced to ethanol. Ethanol is a metabolic product easily excreted by fish, preventing lactate accumulation. The ADH pathway is rarely very active in vertebrate muscle; activity has previously been seen only in goldfish and other cyprinids capable of prolonged anaerobiosis. Activity of the enzyme suite in Arabian Sea and California fishes was compared with that of ecological analogs in the same family and with the same lifestyle but living in systems with much higher oxygen concentrations: the Gulf of Mexico and the Southern Ocean. ADH activities in the Arabian Sea fishes were similar to those of goldfish, far higher than those of confamilials from the less severe minimum in the Gulf of Mexico, suggesting that the Arabian Sea fishes are capable of exploiting the novel ethanol endpoint to become competent anaerobes. In turn, the fishes of California exhibited a higher ADH activity than their Antarctic relatives. It was concluded that ADH activity is more widespread in fishes than previously believed and that it may play a role in allowing vertically migrating fishes to exploit the safe haven afforded by severe oxygen minima.
影响因子：
56.9
作者：
Stramma, Lothar;Johnson, Gregory C.;Mohrholz, Volker
通讯作者：
Mohrholz, Volker