Dey I, Buda C, Wiik T, Halver J E, Farkas T
Institute of Biochemistry, Hungarian Academy of Sciences, Szeged.
Proc Natl Acad Sci U S A. 1993 Aug 15;90(16):7498-502. doi: 10.1073/pnas.90.16.7498.
The compositions and physical states of the liver phospholipids of marine and freshwater fish adapted to relatively constant but radically different temperatures were investigated. Fish adapted to low temperature (5-10 degrees C) accumulated more unsaturated fatty acids than those in a warm (25-27 degrees C) environment. There were no measurable differences in the gross fatty acid compositions of the total liver phospholipids from identical thermal environments. Docosahexaenoic acid (22:6) did not seem to participate in the process of adaptation. Cold adaptation was coincidental with oleic acid (18:1) accumulation, preferentially in the phosphatidylethanolamine. Determination of the molecular species composition of phosphatidylethanolamine revealed a 2- to 3-fold and 10-fold increase in the level of 18:1/22:6 and 18:1/20:5 species, respectively. ESR spectroscopy revealed a 7-10% compensation in the ordering state of native phospholipids with temperature. Combination of 16:0/22:6 phosphatidylcholine with phosphatidylethanolamines of cold-adapted marine fish showed a drastic fluidization near the C-2 segment of the bilayer, but not in the deeper regions. An appropriate combination (75:25) of phosphatidylcholines from warmth-adapted marine fish with phosphatidylethanolamines from cold-adapted marine fish mimicked a 100% adaptational efficacy in the C-2 segment as compared with the phosphatidylethanolamines of warmth-adapted marine fish. A specific role of 18:1/22:6 phosphatidylethanolamine in controlling membrane structure and physical state with thermal adaptation is proposed.
对适应相对恒定但截然不同温度的海洋和淡水鱼肝脏磷脂的组成和物理状态进行了研究。适应低温（5-10摄氏度）的鱼比处于温暖（25-27摄氏度）环境中的鱼积累了更多的不饱和脂肪酸。来自相同热环境的肝脏总磷脂的总脂肪酸组成没有可测量的差异。二十二碳六烯酸（22:6）似乎没有参与适应过程。冷适应与油酸（18:1）的积累同时发生，优先积累在磷脂酰乙醇胺中。对磷脂酰乙醇胺分子种类组成的测定表明，18:1/22:6和18:1/20:5种类的水平分别增加了2至3倍和10倍。电子自旋共振光谱显示天然磷脂的有序状态随温度有7-10%的补偿。将16:0/22:6磷脂酰胆碱与冷适应海洋鱼的磷脂酰乙醇胺结合，在双层膜的C-2段附近显示出剧烈的流化，但在更深的区域则没有。与适应温暖环境的海洋鱼的磷脂酰乙醇胺相比，将适应温暖环境的海洋鱼的磷脂酰胆碱与适应寒冷环境的海洋鱼的磷脂酰乙醇胺以适当比例（75:25）组合，在C-2段模拟了100%的适应效果。提出了18:1/22:6磷脂酰乙醇胺在热适应过程中控制膜结构和物理状态的特定作用。
