Herpetomonas megaseliae: Effect of lipopolysaccharide on cell-surface anionogenic groups

Abstract

Surface anionic groups ofHerpetomonas megaseliae, untreated or treated with lipopolysaccharides (LPS), were analyzed by cell electrophoresis and cytochemistry as well as by identification of sialic acid residues with the aid of thin-layer chromatography. LPS treatment of the trypanosomatids caused a marked decrease in the negative surface charge, as well as in binding to the cell surface of cationized ferritin, colloidal iron hydroxide, and Sendai virus particles. Incubation of LPS-treated and untreated flagellates with neuraminidase resulted in decrease of their mobility to the negative pole. The foregoing findings suggest that sialic acid residues are the major anionogenic groups exposed on the surface of this protozoon. Treatment with LPS markedly alters the nature and number of these residues. OnlyN-acetylneuraminic acid can be detected on untreated flagellates, whereasN-acetyl andN-glycolylneuraminic acid derivatives are found on the organisms exposed to LPS.