Composition and characterization of the lipids of garfish ( Lepisosteus osseus) olfactory nerve, a tissue rich in axonal membrane

Abstract

The garfish olfactory and trigeminal nerves were studied for their lipid composition. Cholesterol was the only neutral lipid found in both nerves. The phospholipids constituted about 73, and 64%, respectively, of the olfactory and trigeminal nerve total lipids. Cerebrosides and sulfatide were found only in the myelinated trigeminal nerve. An unidentified glycolipid was found in the olfactory nerve lipid extract. The phospholipid fraction in both nerves was composed mainly of phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine and sphingomyelin. Minor components were phosphatidylinositol, phosphatidic acid and diphosphatidylglycerol. As compared with the phospholipid composition of the myelinated trigeminal nerve, the olfactory nerve had less phosphatidylethanolamine and more phosphatidylcholine and phosphatidylinositol. The phosphatidylethanolamine fraction was rich in plasmalogen but only small amounts of plasmalogen were found in phosphatidylcholine and phosphatidylserine. Substantial amounts of alkyl glyceryl ether types were found in both phosphatidylethanolamine and phosphatidylcholine. A distinctive characteristic of the lipids of the olfactory nerve was the presence of large proportions of long chain, highly unsaturated fatty acids. These fatty acids, namely C 20:4 and C 22:6, were preferentially located in phosphatidylethanolamine, phosphatidylserine and phosphatidylinositol.