Modification of spleen phospholipid fatty acid composition by dietary fish oil and by n-3 fatty acid ethyl esters.

We have compared the effects of diets containing purified ethyl esters of either eicosapentaenoic acid, docosahexaenoic acid, or a mixture of both of these compounds, with diets containing either purified fish oil or beef tallow on spleen phospholipid fatty acid composition. Autoimmune mice, the (NZB x NZW)F1 strain, were fed with experimental diets for 14 weeks, after which spleen phospholipids were extracted and separated into classes by HPLC, and the alkenylacyl, alkylacyl, and diacyl subclasses of glycerylphosphatidylethanolamine and glycerylphosphatidylcholine were resolved as their benzoyl esters by HPLC. Fatty acids were analyzed by capillary gas-liquid chromatography of their methyl esters. Each of the marine lipid diets suppressed n-6 fatty acids and elevated n-3 fatty acids in all phospholipids. The eicosapentaenoic acid ethyl ester diets led to high levels of eicosapentaenoic acid and docosapentaenoic acid (C22:5n-3), but little or no increase in docosahexaenoic acid. The docosahexaenoic acid ethyl ester diets elevated docosahexaenoic acid, docosapentaenoic acid, and eicosapentaenoic acid in all phospholipids, indicating that extensive retroconversion of 22 carbon n-3 fatty acids had occurred. These results document changes in the fatty acid composition of mammalian phospholipids that are induced by dietary fish oil triglycerides and by dietary long chain n-3 fatty acid ethyl esters.

Dietary marine lipids suppress murine autoimmune disease.

Dietary marine lipids reduce both mortality and the severity of glomerulonephritis in inbred murine strains which develop spontaneous autoimmune disease. The protective effects of marine lipids appear to be accounted for by the major n-3 fatty acids in these preparations, 20:5 and 22:6. The n-3 fatty acids in dietary fish oil are extensively incorporated into several lipid classes in the spleen of autoimmune mice, including phosphatidylinositol, phosphatidylethanolamine, plasmalogens and saturated ether-linked phospholipids as well as diacylphosphoglycerides. The effects of dietary marine lipids on autoimmune disease in experimental models are highly specific. Careful controlled trials will be required to establish the role of dietary marine lipids in the therapy of human autoimmune disease.

Are protein synthesis inhibition and phase shifting of the circadian clock in Gonyaulax correlated?

We describe a method whereby the effect of protein synthesis inhibitors upon protein synthesis in Gonyaulax cultures may be reliably measured. Using this method, we found that protein synthesis inhibition and clock resetting were correlated, but that the correlation was not as close as has been reported in other systems. The effect of the inhibitors anisomycin and cycloheximide upon phase shifting of the circadian clock was a function of the illumination and temperature conditions to which the cells were subjected, but these factors did not appear to influence the inhibition of protein synthesis by these drugs. Cellular protein synthesis did not recover immediately from the inhibitors' effects; depending upon the previous concentration of the inhibitor, translational recovery from the drugs may require hours. This observation has important implications for the analysis of any phase response curve when the stimulus is a chemical.