Quantitative analysis of very long chain fatty acids of bovine retina

Abstract

Background. Bovine retina is known to contain very long chain polyunsaturated fatty acids (VLCPUFA) of chain length >24 carbons and 4–6 double bonds. We carefully quantified the ELCPUFA of bovine retina using modern methods in beef cattle. Methods. Bovine retinas were obtained from a slaughterhouse in Nebraska. Retinas were carefully dissected and 50 were pooled for analysis. Samples were extracted, the phosphatidyl choline (PC) fraction purified, and fatty acid methyl esters prepared. Structures were analyzed by covalent adduct chemical ionization tandem mass spectrometry, and quantified by capillary gas chromatography. High precision isotope ratios of 22:6n-3 and 20:4 were determined. Results. About 1% of the PC were VLCPUFA. They were detected at chain lengths from C24 to C36 and up to 6 double bonds. n-6 LCPUFA were high, especially 20:4 and 22:5, compared to studies published in the 1980s, probably reflecting the high n-6 content of the corn diet. 32:4n-6 was anomalously predominant compared to similar chain lengths and degrees of unsaturation. The δ13C for 20:4n-6 was 10‰ greater than for 22:6n-3. Conclusions. These data form a basis for models of membrane phenomena such as protein-phospholipid interactions that may rely on PUFA and VLCPUFA for activity. They also suggest that the retinas of corn-fed cattle are particularly low in n-3 LCPUFA. Funding: NIH GM071534.