Gangliosides and phospholipids from frog and duck retina

Successive isolation and separation of the major lipid fractions including gangliosides from single biological samples

Currently available techniques concerning extraction and characterization of the different lipids from biological specimens are designed for particular families and do not address consecutive isolation of lipid constituents in their globality. We describe here a simple, nondestructive chromatographic procedure that allows efficient elution and further analysis of the major lipid classes (neutral lipids, phospholipids, nonsialylated sphingolipids, and gangliosides) in their natural states from the same starting material. The procedure describes the use of solvent mixtures adapted to silicic acid column chromatography and permits 90-97% recovery of each of the above lipid groups. We have particularly concentrated on optimizing the efficient recovery of the diverse minor forms of gangliosides, free of other contaminants, from relatively small amounts of neural tissue. As model systems we have used in vivo and in vitro preparations of mammalian retina for which only fragmentary data are available on lipid composition. We show that relative to brain, retina contains, for example, twofold more sphingomyelin and sixfold more GD3 ganglioside. In turn, cultured retinal glial cells contain twofold higher levels of globoside and eightfold higher amounts of GM3 ganglioside with respect to intact retina. Compared to previously published techniques, we obtain improved total ganglioside recovery, with enrichment of poly-sialogangliosides. The technique presented here should be widely applicable to analyze global lipid composition of diverse biological samples.

Distribution of membrane phospholipids in the rabbit neural retina, optic nerve head and optic nerve

Since diseases of the neural retina and optic nerve can result in alteration of biological membranes, this study determines similarities and differences in the membrane phospholipid content of the neural retina, optic nerve head, and optic nerve to serve as baseline data. Neural retina, optic nerve head, and optic nerve were dissected, isolated as 5 sets from 20 rabbits and frozen in liquid N2. Separate pooled-tissue extracts were prepared for each set of tissues and phosphorus-31 nuclear magnetic resonance (31P NMR) analyses performed. Ten phospholipids were quantified (respective neural retina, optic nerve head, and optic nerve mole % are given for the 5 major phospholipids detected): phosphatidylcholine (PC), 44.61, 27.67, 26.40; PC plasmalogen or alkylacyl PC (CPLIP); phosphatidylinositol (PI); sphingomyelin (SM); phosphatidylserine (PS), 12.63, 14.77, 15.09; phosphatidylethanolamine (PE), 21.21, 9.59, 8.69; PE plasmalogen (EPLAS), 11.07, 30.96, 33.93; an unidentified (unknown) phospholipid (U) at the chemical-shift value of 0.13 ppm; diphosphatidylglycerol (DPG); and phosphatidic acid (PA), 0.46, 2.92, 1.57. Significant differences between the various tissues were determined by the one-way analysis of variance, using a Scheffé range value of P < 0.05. The neural retina in all phospholipids detected except for the uncharacterized (unknown) phospholipid was significantly different from the optic nerve head tissue. The optic nerve head was significantly different from the optic nerve in PC, CPLIP, PE, EPLAS, U, DPG, and PA. The data provide a baseline for studies on pathologically changed neural retina, optic nerve head, and optic nerve.

Phylogeny and ontogeny of vertebrate brain gangliosides

Gangliosides evolved relatively recently in the history of life, thus their contribution to fundamental cellular processes must be ancillary to or superimposed on preexisting mechanisms. Brain ganglioside patterns vary along taxonomic lines in a fairly conservative fashion, indicating that general ecophysiological factors have probably provided the major selective constraints. During brain development in birds and mammals, gangliosides pass through a transient stage of pattern complexity that may reflect their reptilian ancestry. While this ganglioside heterogeneity could provide positional information within the developing tissue, it might merely reflect a necessary but incidental transition to the handful of major gangliosides essential to mature brain function.

Gangliosides in various brain areas of three inbred strains of mice

The ganglioside patterns of cerebellum, cortex, pons-medulla, hypothalamus, hippocampus and caudate nucleus of three inbred strains of mice (C57BL/6J, DBA/2J and BALB/cJ) have been analysed. All brain areas contained both the simple and complex species of gangliosides. GD1a was the major ganglioside in cortex, hippocampus and caudate nucleus whereas GT1b was the major species in cerebellum, hypothalamus and pons-medulla. In hippocampus, the percentages of GT1b and GD1a were quite similar. Pons and medulla exhibited the highest levels of GM1 (which approaches the value of GT1b) and the lowest values of GD1a. A ganglioside, which was present in highest amounts in cerebellum disappeared after alkali treatment. Highly significant differences were observed in the amounts and patterns of gangliosides among brain areas of the three strains. Highly significant differences (p less than 0.001) were also found in the ganglioside distribution of various brain areas among the strains, especially for tri- and tetrasialogangliosides between Balb and DBA. A significant difference of GM1 was observed in the cerebellum when comparing DBA with the two other strains. It is likely that the differences might be related to their relative abundances in certain cell types and for defining synaptic circuits in brain areas of some strains.

Ganglioside patterns and cholera toxin--peroxidase labeling of aggregating cells from the chick optic tectum

2The ganglioside compositions of the chick optic tectum and aggregating tectal cell cultures were examined. Both showed similar trends in changes in ganglioside patterns during development. GD3 and GD1b were the predominant gangliosides early in development, while GD1a and several other multisialogangliosides increased in relative amounts with increasing age in vivo and in vitro. Four gangliosides were present early in development which have not previously been reported. These gangliosides are not present at later developmental times suggesting a possible role for them during the critical early stages of nervous tissue differentiation. Some differences were noted when comparing in vivo versus in vitro ganglioside patterns; these differences may possibly be due to the lack of normal retinotectal connections in the cultures. Cytochemical studies on the localization of the presumed cholera toxin--peroxidase binding site GM1 showed conjugate binding correlates with increasing levels of GM1 in the cultures. In older cultures, the conjugate was uniformly localized on all cells and processes in the aggregates. The conjugate also bound to synaptic membranes and intensely stained the synaptic cleft. This latter observation suggests an enrichment of GM1 in the synaptic cleft region.

Gangliosides and phospholipids of the membranes from bovine adrenal medullary chromaffin granules

The lipid and ganglioside compositions of membranes of chromaffin granules isolated from bovine adrenal medulla have been investigated. The detailed lipid analysis revealed the presence of high levels of lysophosphatidylcholine, in agreement with previous studies, but also of sphingomyelin and plasmalogens. From these membranes, gangliosides have been extracted and separated by thin-layer chromatography and analysed. 95% of the total recovered gangliosides were hematosides (GM3), which migrated as three major species. Sugar analyses have been performed, as well as the fatty acid compositions. The three hematoside gangliosides appeared to differ on the basis of their fatty acid composition. Compared with the brain, chromaffin granule membranes showed a simple ganglioside composition, thus offering a good model for the study of the metabolism and the role of gangliosides. The simple ganglioside composition of chromaffin granule membranes has allowed us to state that there are 60 mol phospholipid and 30 mol cholesterol per mol ganglioside.

Ether lipid content of phosphoglycerides from the retina and brain of chicken and calf

Phospholipid contents and compositions were determined for chicken and calf retinas, chicken brain and calf gray matter. Retinal phospholipid compositions differ from brain phospholipid compositions by including a higher percentage of choline phosphoglycerides and lower percentages of ethanolamine and serine phosphoglycerides. The proportion of sphingomyelin is lower in calf retina than in calf brain. Among the ethanolamine phosphoglycerides, the proportions of the alk-1-enylacyl (plasmalogen) type are lower and the proportions of alkylacyl and diacyl types are higher in retina than in brain. The alkyacyl glycerophosphoethanolamines accounted for 7.6% and 8.9% of the ethanolamine phosphoglycerides from chicken and calf retinas respectively. Lower proportions of plasmalogens in the choline phosphoglycerides were found in retina as compared with brain. The alkylacyl glycerylphosphocholines comprised 4.0% of the retinal choline phosphoglycerides. Overall, a smaller proportion of retinal phosphilipids than of brain phospholipids contained alkyl or alk-1-enyl ether groups and the ratio of alkyl groups to alk-1-enyl groups was greater in retina than in brain.