Zhao Liying, Castellini Michael A, Schell Donald M
Institute of Marine Science, School of Fisheries and Ocean Sciences, University of Alaska, Fairbanks, Alaska 99775-7220, USA.
Physiol Biochem Zool. 2006 Sep-Oct;79(5):965-76. doi: 10.1086/506005. Epub 2006 Aug 15.
Effects of varying dietary protein intake on serum free amino acid (FAA) concentrations were studied in harbor seals (Phoca vitulina) fed two different prey fish diets: either exclusively low-fat, high-protein walleye pollock (Theragra chalcogramma) or high-fat, relatively high-energy-density Pacific herring (Clupea pallasi). Significant differences in FAA concentrations and patterns were observed between the two diets. All essential amino acids (EAA), except methionine and phenylalanine, and two nonessential amino acids (NEAA), glycine and tyrosine, decreased when the diet was switched from herring to pollock and increased on switching back to herring. Both total EAA concentrations and EAA : NEAA ratios decreased with the elevated protein intake typical of a low-fat pollock diet, indicating an inverse correlation between EAA concentrations and dietary protein intake levels. We propose that differing dietary protein intake, caused by differences in macronutrient composition of the two prey fish species, induced a change in protein metabolism that was reflected in blood-circulating amino acids. These findings suggest that surveys of amino acid profiles may be useful to partially determine the protein metabolic status of harbor seals.
在以两种不同的猎物鱼为食的斑海豹（Phoca vitulina）中，研究了不同饮食蛋白质摄入量对血清游离氨基酸（FAA）浓度的影响：要么只喂食低脂、高蛋白的狭鳕（Theragra chalcogramma），要么喂食高脂肪、相对高能量密度的太平洋鲱（Clupea pallasi）。在两种饮食之间观察到FAA浓度和模式存在显著差异。当饮食从鲱鱼换成狭鳕时，除蛋氨酸和苯丙氨酸外的所有必需氨基酸（EAA）以及两种非必需氨基酸（NEAA），即甘氨酸和酪氨酸，都会减少，而换回鲱鱼时则会增加。随着低脂狭鳕饮食中典型的蛋白质摄入量增加，总EAA浓度和EAA:NEAA比率均降低，表明EAA浓度与饮食蛋白质摄入量水平呈负相关。我们认为，两种猎物鱼物种的常量营养素组成差异导致的不同饮食蛋白质摄入量，引发了蛋白质代谢的变化，这反映在血液循环氨基酸中。这些发现表明，氨基酸谱的调查可能有助于部分确定斑海豹的蛋白质代谢状态。
