Evaluation of a gas chromatographic method for the quantitative estimation of hexoses from neutral glycolipids

Long-chain O-ascarosyl-alkanediols are constitutive components of Caenorhabditis elegans but do not induce dauer larva formation

Two long-chain ascarosides, O-ascarosylnonacosane-2,28-diol and O-ascarosyluntriacontane-2,30-diol, were isolated from Caenorhabditis elegans and detected in all developmental stages of the worm. The long-chain ascarosides were shown to be minor lipid components, and it was also shown that they do not induce dauer larva formation.

Lipid composition of metacestodes of Taenia taeniaeformis and lipid changes during growth

A lipid analysis was performed on developing metacestodes of Taenia taeniaeformis removed from the livers of rats at times varying from 3 to 35 weeks post infection. Lipid accounted for 7-21% of the dry weight of the parasites. The highest proportions were found at the earlier stages. The distribution was as follows; neutral lipid 27-45%; glycolipid 5-11%; and phospholipid 50-61%. The major neutral lipid was cholesterol, and minor neutral lipids were sterol esters, triglycerides, diglycerides and monoglycerides. Hydrocarbons were present throughout development, but in the highest amounts at the earlier stages. Five different glycolipids were found, all of which were identified as glycosphingolipids. An increase in the proportion of more complex glycolipids was noted as parasites grew older. Ten different phospholipids were identified, with the major components being phosphatidylcholine, phosphatidylethanolamine, and phosphatidylserine. Other phospholipids were: lysophosphatides, phosphatidylinositol, phosphatidic acid, diphosphatidylglycerol, sphingomyelin, and an unknown phospholipid component. Changes in the relative amounts of the two major phospholipids were found when the early and late stages were compared. Two lipids found throughout development were identified as glycosylated dolichol phosphates, and they comprised between 1 and 3% of the total phospholipid fraction. Nineteen fatty acids were detected, and the fatty acid distribution for each lipid class at each stage was determined. Seven major fatty acids were common to each. These were: hexadecanoic, octadecanoic, oleic, linoleic, arachidonic, docosanoic, and docosahexaenoic.

Critical study of the alditol acetate method for quantitating small quantities of hexoses and hexosamines in gangliosides

An extensive investigation of and improvement in the method for quantitating the carbohydrates of glycolipids by the gas--liquid chromatography of their alditol acetate derivatives is described. The effects of duration and temperature of hydrolysis, neutralization after hydrolysis, and acetylation time and temperature on the relative detector responses of mixtures of free as well as ganglioside hexoses and hexosamines were extensively studied. It is concluded that optimum results are obtained with the following conditions: hydrolysis at 100 degree C for 8 to 12 h, a 40--60 min reduction, acetylation at 100 degree C for 30 min. When quantitating the carbohydrate components of gangliosides, the most reliable results will be obtained using as an external standard a glycolipid whose chemical structure is similar to that of the sample. Using this procedure, reliable results can be obtained with the initial glycolipid sample containing as little as 1 microgram of each sugar.