Budge Suzanne M, Cooper Margaret H, Iverson Sara J
Department of Biology, Dalhousie University, Halifax, Nova Scotia B3H 4J1, Canada.
Physiol Biochem Zool. 2004 Jul-Aug;77(4):682-7. doi: 10.1086/420945.
Radioisotopes are commonly used to study the in vivo metabolism and deposition of dietary fatty acids in adipose tissue. The application of this approach to pinnipeds is problematic because of their large mass and blubber fat content. We have developed a method where labelled lipids can be fed to seals at financially feasible levels, with the radioactivity in individual fatty acids isolated from blubber detected with standard laboratory equipment. A combination of techniques including argentation thin layer chromatography, high performance liquid chromatography with ultraviolet detection, and independent liquid scintillation counting were employed. Juvenile gray seals (Halichoerus grypus) were fed either 0.5 mCi (3)H-labelled triolein (18:1n-9, n=2) or palmitic acid (16:0, n=2). Blubber samples were taken 12 h later, and the radioactivity in individual fatty acids was determined. Radioactivity was detected in only 18:1 from the animals fed (3)H-labelled triolein, indicating direct deposition without modification. Both animals fed (3)H-labelled palmitic acid showed clear peaks of radioactivity in 16:0; however, there was also significant activity (23%-29%) found in the desaturation product 16:1. Our results demonstrate that this method is sufficiently sensitive to track the deposition of labelled dietary lipids as well as modification products of ingested fatty acids and will be important in the application of fatty acid signatures to study predator diets.
放射性同位素通常用于研究膳食脂肪酸在体内的代谢以及在脂肪组织中的沉积情况。由于鳍足类动物体型庞大且脂肪含量高，将这种方法应用于鳍足类动物存在问题。我们开发了一种方法，能够以经济可行的水平向海豹投喂标记脂质，并使用标准实验室设备检测从脂肪中分离出的单个脂肪酸中的放射性。我们采用了包括银化薄层色谱法、带紫外检测的高效液相色谱法以及独立液体闪烁计数法在内的多种技术。给幼年灰海豹（Halichoerus grypus）投喂了0.5毫居里的（3）H标记的三油精（18:1n - 9，n = 2）或棕榈酸（16:0，n = 2）。12小时后采集脂肪样本，并测定单个脂肪酸中的放射性。在投喂了（3）H标记的三油精的动物的脂肪中，仅在18:1中检测到放射性，表明直接沉积且未发生修饰。投喂了（3）H标记的棕榈酸的两只动物在16:0中均显示出明显的放射性峰值；然而，在去饱和产物16:1中也发现了显著的活性（23% - 29%）。我们的结果表明，这种方法足够灵敏，能够追踪标记膳食脂质的沉积以及摄入脂肪酸的修饰产物，对于将脂肪酸特征应用于研究捕食者的饮食具有重要意义。
