Glycolipid Extraction

It is commonly known that lipids, carbohydrates, and glycolipids are present in the Golgi apparatus (27). The determination of the components that react with the ZIO mixture was carried out by removing each component from tissues before incubation in the ZIO mixture. After lipid extraction by acetone (14), chloroform-methanol (15), or propylene oxide (27), no osmium-zinc precipitates could be detected in structures that normally reacted with ZIO. Blumcke et al. (15) summarized the nature of the lipids that react with the ZIO mixture as follows lipids and lipoproteins of cell membranes, neutral fat droplets (41), and lipid globules of type II pneumocytes and alveolar macrophages were, however, not as electron dense as the normally reactive lamellae containing highly unsaturated fatty acids. 

Two-dimensional techniques are usually employed if both phospho-glycerides and glycolipids are present, but it is possible to resolve members of both classes using a diisobutylketone-acetic acid-water mixture (40 25 5). A solvent composed of acetone, acetic acid and water (100 2 1) will separate the mono- and di-galactosyldiglycerides, which are particularly abundant in plant extracts, from phosphoglycerides, which remain at the origin. 

New glycolipids have to be synthesized to get further insights into liquid crystal properties (mainly lyotropic liquid crystals), surfactant properties (useful in the extraction of membrane proteins), and factors that govern vesicle formation, stability and tightness. New techniques have to be perfected in order to allow to make precise measurements of thermodynamic and kinetic parameters of binding in 3D-systems and to refine those already avalaible with 2D-arrays. Furthermore, molecular mechanics calculations should also be improved to afford a better modeling of the conformations of carbohydrates at interfaces, in relation with physical measurements such as NMR. 

The lipid extracts from echinoderms have been found to contain 3.3 to 8.5% of monosaccharides. The only exception is the sea cucumber Cucumaria japonica, whose lipid extract contains 1.6% of monosaccharides, although a related species, C. fraudatrix, has been found to contain the highest proportion thereof (8.5%). It should, however, be noted that some carbohydrate-containing compounds in the lipid extracts of echinoderms may be represented not by glycolipids, but by steroid or triterpene glycosides.275"282... 

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