Changes in cell surface anionogenic groups during differentiation ofHerpetomonas samuelpessoai mediated by dimethylsulfoxide

Abstract

The surface anionic groups of untreated or dimethyl sulfoxide (DMSO)-treated Herpetomonas samuelpessoai cells were analyzed by cell electrophoresis, ultrastructural cytochemistry, and identification of sialic acids using thin-layer chromatography. Differentiation of H. samuelpessoai induced by DMSO treatment caused a significant increase in the net negative surface charge. In flagellates exposed to DMSO, more cationized ferritin, colloidal iron hydroxide, and sendai virus particles bound to the cell surface. Treatment of both untreated and DMSO-treated flagellates with neuraminidase decreased markedly the EPM of cells to the cathodic pole. These findings suggest that sialic acid residues are the major anionogenic groups exposed on the surface of H. samuelpessoai. Thin-layer chromatography showed that N-acetyl and N,O-diacylneuraminic acids, in equal proportions, were present in H. samuelpessoai. However, N-acetylneuraminic acid predominates in DMSO-treated cells.

The surface charge of trypanosomatids

“…Treatment of C. deanei with neuraminidase reduced in about 45% the EPM of the protozoan, irrespective of the presence of the endosymbiote (Oda et al 1984). Parasites of the genus Herpetomonas have been used to analyze changes on cell surface during the process of differentiation in vitro, since the composition of the plasma membrane and the surface coat are of primary importance in cell response to environmental stimuli and in the interaction of parasites with their hosts (Soares et al 1988, Lopes et al 1989, Faria-e-Silva et al 1999. Besides these aspects, Herpetomonas sp presents four developmental stages (promastigotes, paramastigotes, opisthomastigotes and opisthomorphs), are non pathogenic for men and show close antigenic similarities to Trypanosoma cruzi Roitman 1971, Souza et al 1974).…”

“…Promastigotes of H samuelpessoai, H. muscarum muscarum, H. megaseliae and H. roitmani display a negative surface charge, with mean EPM varying, according to the species analyzed (Table I). Treatment of Herpetomonas with 2-deoxy-D-glucose (Angluster et al 1977), concanavalin-A (ConA) (Souza et al 1980), dimethylsulfoxide (DMSO) (Castellanos et al 1981), propranolol (Lopes et al 1983) and lipopolysaccharide (LPS) (Fiorini et al 1985) triggers the process of cell differentiation from promastigote to para-and opisthomastigote forms, affecting the composition of membrane-associated polysaccharides (Alviano et al 1981, Soares et al 1984, cell surface charge (Soares et al 1988, Lopes et al 1989) and cell respiration (Fiorini et al 1985). Dimethiylsulfoxide and propranolol caused a significant increase in the net negative surface charge of both H. samuelpessoai and H. muscarum muscarum due to a markedly increase in the number of Nacetylneuraminic acid residues per cell (Soares et al 1988, Lopes et al 1989.…”

“…WGA do not bind or agglutinate bloodstream forms of T. brucei (Steiger 1975), T. equiperdum (Jackson 1977) Soares et al 1988, Lopes et al 1989. a Standard deviation; b mean EPM of control -mean EPM of neuraminidase treated cell / mean EPM of control ×100.…”

“…In these studies parasites were incubated in the presence of substances which induce cell differentiation since it has been observed that the change in form is either accompanied by or preceded by changes in the cell surface composition. Dimethylsulphoxide (DMSO) treated H. samuelpessoai presented a more intense labeling compared with untreated cells (Soares et al 1988). Differentiation of H. muscarum muscarum induced by propranolol caused a significant increase in the negative surface charge.…”

“…Cationic particles bind to the surface of Herpetomonas samuelpessoai (Soares et al 1988), Herpetomonas muscarum muscarum (Lopes et al 1989) and Herpetomonas megaseliae . In these studies parasites were incubated in the presence of substances which induce cell differentiation since it has been observed that the change in form is either accompanied by or preceded by changes in the cell surface composition.…”