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A number of lipopolysaccharides derived from Salmonella and Escherichia coli S and R mutant strains were tested for toxicity and anticomplementary activity in the absence of added antiserum. Although all preparations were toxic, only a few exhibited high anticomplementary activity, while others proved to be of low or negligible activity. It was found that isolated lipid A from both active and reactive lipopolysaccharides was strongly anticomplementary as well as toxic, when made water-soluble with the aid of suitable carriers. Treatment of R form lipopolysaccharide with Mg2+ or Ca2+ led to complete precipitation of the lipopolysaccharide with consequent loss of toxicity and anticomplementary activity. This treatment had practically no effect on the anticomplementary activity and toxicity of S form lipopolysaccharides. When lipopolysaccharide, after reaction with complement, was reisolated and purified, the resulting preparation was found to be non-toxic and of negligible anticomplementary activity. No detectable alterations in either the sugar or the fatty acid composition could be detected. The only significant change was the loss of solubility in water. Treatment of the reisolated lipopolysaccharide with EDTA completely restored solubility m water, toxicity, and anti-complementary activity. [ABSTRACT FROM AUTHOR]

The "Quacking" mouse in a mutant which has an inherited disease involving the process of myelination in the central nervous system. Fractionation of brain lipids and fatty acid methyl ester analysis of each lipid isolated have been performed. No qualitative abnormalities have been detected, either in ethanolamine, serine and choline phospphoglycerides, or in cholesterol. Proof has now been obtained that the considerable reduction in long chain fatty acid (C24), occurs in cerebrosides, sulphatides (where they are normally major constituents) and in sphingomyelin. Long chain hydroxylated fatty acids are comparatively less diminished than non-hydroxylated one. This metabolic defect, detected in all the sphingolipids that contain this type of fatty acids could be in favour of a mutation related to fatty cid elongation which is very important at the time of myelin formation. [ABSTRACT FROM AUTHOR]