The occurence of a long-chain ether analogue of phosphatidylethanolamine in brain tissue

Regional changes in CNS and retinal glycerophospholipid profiles with age: a molecular blueprint

We present here a quantitative molecular blueprint of the three major glycerophospholipid (GPL) classes, phosphatidylcholine (PC), phosphatidylserine (PS), and phosphatidylethanolamine (PE), in retina and six regions of the brain in C57Bl6 mice at 2, 10, and 26 months of age. We found an age-related increase in molecular species containing saturated and monoenoic FAs and an overall decrease in the longer-chain PUFA molecular species across brain regions, with loss of DHA-containing molecular species as the most consistent and dramatic finding. Although we found very-long-chain PUFAs (VLC-PUFAs) (C28) in PC in the retina, no detectable levels were found in any brain region at any of the ages examined. All brain regions (except hippocampus and retina) showed a significant increase with age in PE plasmalogens. All three retina GPLs had di-PUFA molecular species (predominantly 44:12), which were most abundant in PS (∼30%). In contrast, low levels of di-PUFA GPL (1-2%) were found in all regions of the brain. This study provides a regional and age-related assessment of the brain's lipidome with a level of detail, inclusion, and quantification that has not heretofore been published.

The incorporation of ethanolamine into ether-containing lipids in rat brain

After intracerebral injection of C(14)-ethanolamine into rats, the ethanolamine phosphoglycerides were isolated and hydrolyzed with mild alkali and acid. The specific radioactivity of the diacyl, acyl alkenyl, and acyl alkyl glyceryl-3-phosphorylethanolamine, the diacyl and acyl alkenyl glyceryl-3-phosphorylcholine, and sphingomyelin was determined at 0.5, 2, 24, and 48 hours. The specific radioactivity-time relationships show that the ethanolamine plasmalogen is not a precursor for the glyceryl ether form but suggest that acyl alkyl glyceryl-3-phosphorylethanolamine is desaturated to form some of the acyl alkenyl glyceryl-3-phosphorylethanolamine. The radioactivity in the choline portion of the choline phospholipids was very low.

Alcohol dehydrogenase-coupled spectrophotometric assay of plasmalogenase

Plasmalogenase has been assayed by conversion of the fatty aldehydes, released by hydrolysis of the vinyl ether bond of plasmalogens, to long-chain alcohols by horse liver alcohol dehydrogenase. The reaction was followed spectrophotometrically by measuring the oxidation of NADH. The assay is sufficiently sensitive to enable plasmalogenase activity to be determined in isolated oligodendroglia and derived membranes and in brain microsomal membranes using 50-250 micrograms protein.

Identification of N-acylethanolamine phosphoglycerides and acylphosphatidylglycerol as the phospholipids which disappear as Dictyostelium discoideum cells aggregate

The cellular slime mold Dictyostelium discoideum contains a phospholipid fraction which comprises 10% of the phospholipids in the early developing amoebae and disappears during the aggregation stage of development. As a first step in studying its metabolism, the composition of the fraction has been determined. It was easily isolated by preparative silicic acid thin-layer chromatography because its Rf was considerably higher than most commonly encountered phospholipids. Its Rf was the same as synthetic phosphatidyl-N-acylethanolamine and synthetic acylphosphatidylglycerol (also called semilysobisphosphatidic acid). Strong absorption peaks characteristic of amide bonds in the infrared spectrum of the isolated D. discoideum phospholipid showed that N-acylethanolamine phosphoglycerides were present. The presence of acylphosphatidylglycerol was revealed when mild alkaline hydrolysis of the lipid fraction produced glycerophosphorylglycerol as the only water-soluble, phosphate-containing product. The composition of the fraction was determined by chemical analysis and thin-layer chromatography of the intact phospholipids and their partially or completely hydrolyzed products. The composition of the fraction was 30% diacylglycerophosphoryl-N-acylethanolamine, 50% alkenylacylglycerophosphoryl-N-acylethanolamine, and 20% acylphosphatidylglycerol. The stereoconfiguration of the glycerophosphorylglycerol moiety of the acylphosphatidylglycerol was found to be sn-3-glycerophosphoryl-sn-1'-glycerol.

Studies on trimethylsilyl derivatives of 1-alkyl-2-acylglycerols by gas-liquid chromatography mass spectrometry

Trimethylsilyl derivatives of 1-hexadecyl-2-decanoyl-, -hexadecanoyl- and -octadecenoyglycerols and 1-octadecyl-2-decanoyl-, hexadecanoyl- and -octadecenoylglycerols as well as 1,2-dihexadecanoylglycerol were analysed by a gas chromatography mass spectrometer system. The following points are characteristic of the fragmentation pattern of these 1-alkyl-2-acyl derivatives: (1) in the spectra of alkyl acyl derivatives, ions at [M -15]+ and [M - 90A1+. are 14 mass units less than those of the corresponding diacyl derivatives; (2) the base peak is m/e 130; (3) alkyl acyl derivatives show fragments due to one acyl group instead of the two acyl groups of diacyl derivatives; (4) ions at m/e 314 and 342, [R1O + 73]+., are characteristic of the trimethylsilyl derivatives of hexadecyl- and octadecylglycerols, respecitvely; (5) the ion [M -R1O]+ is present, but the complementary alkoxy ion is absent.

The polyphosphoinositides and other lipids of peripheral nerves

1. A detailed lipid analysis of the peripheral nerves of the crab (claw, leg), lobster (claw, leg), cow (splenic), hen, rabbit, sheep and monkey (sciatic) is presented. 2. The so-called ;myelinic lipids', cholesterol, sphingomyelin, ethanolamine plasmalogen and phosphatidylserine, occurred in the highest proportion in the lipids of vertebrate myelinated nerves, whereas the percentage of lecithin was greatest in the lipids of non-myelinated nerve fibres of both vertebrates and invertebrates. 3. Triphosphoinositide was found in all nerves examined and its concentration in the extracted lipids supports the concept that it is predominantly localized in the myelin sheath. 4. In crustacean nerve 12-14% of the phospholipids was in the form of alkyl ether phospholipids, which in the lobster were approximately half choline-containing and half ethanolamine-containing.