Isolation and characterization of a neutral glycosphingolipid from the epimastigote form of Trypanosoma mega

Identification of Monohexosylceramides From Euglena gracilis by Electrospray Ionization Mass Spectrometry

To date, the monohexosylceramides present in the eukaryotic alga Euglena gracilis has not been reported. In this study, we extracted and purified a lipid fraction that eluted similarly to other reported monohexosylceramides. The structural determination of the lipid fraction revealed a monohexosylceramide ( m/ z = 889.5 and a loss of m/ z = 162), corresponding to the formula C54H99O8N having moieties corresponding to a monohexose (C6H12O6), a 9-methyl-4,8-sphingadienine (C19H37O2N), and a nonacosanoic acid with 2 double bonds (C29H54O2). This is the first report of the isolation of monohexosylceramides from E. gracilis and will promote its utilization in functional foods and cosmetics.

Structural and immunological characterization of sulphatides: relevance of sulphate moieties in Trypanosoma cruzi glycoconjugates

Sulphoglycosphingolipids, present on the surface of diverse cells, participate in the regulation of various cellular events. However, little is known about the structure and the role of sulphoglycosphingolipids in trypanosomatids. Herein, sulphated dihexosylceramide structures - composed mainly of sphingosine as the long chain base acylated with stearic acid - have been determined for the first time in Trypanosoma cruzi epimastigotes by UV-MALDI-TOF-MS analysis. Interestingly, inhibition ELISA assays using cruzipain as antigen and polyclonal rabbit antibodies specific for cruzipain, the major cysteine proteinase of T. cruzi, or for its C-terminal domain, have demonstrated (i) that sulphate epitopes are shared between cruzipain and sulphatides of T. cruzi, (ii) that cross-reactivity maps to the C-terminal domain and (iii) the existence of other antigenic determinants in the glycolipidic structures. These features provide evidence that sulphate groups are antigenic in sulphate-containing parasite glycoconjugates. Furthermore, IgG2 antibody levels inversely correlate with disease severity in chronic Chagas disease patients, suggesting that IgG2 antibodies specific for sulphated epitopes might be associated with protective immunity and might be considered as potential surrogates of the course of chronic Chagas disease.

Analysis of neutral glycosphingolipids from Trypanosoma brucei

Neutral glycosphingolipids (GSLs) were isolated from Trypanosoma brucei and analyzed by thin-layer chromatography (TLC), TLC/secondary ion mass spectrometry (TLC/SIMS), and liposome immune lysis assay (LILA). Three species of neutral GSLs, designated as N-1, -2, and -3 were separated on TLC. N-1 GSL migrated very close to glucosylceramide (GlcCer) and N-2 GSL showed the same mobility as lactosylceramide (LacCer). On the other hand, the mobility of N-3 GSL on the TLC plate was slower than globotetraosylceramide (Gb4). In order to characterize the molecular species of neutral GSLs from T. brucei, N-1, -2 and -3 GSLs were analyzed by TLC/SIMS. The TLC/SIMS analysis of N-1 of the parasites revealed a series of (M-H)- ions from m/z 698 to 825 representing the molecular mass range of ceramide monohexoside (CMH) (GlcCer or galactosylceramide). On the other hand, the TLC/SIMS spectra of N-2 GSL revealed a series of (M-H)- ions from m/z 944-987 indicating the molecular mass range of LacCer. In the TLC/SIMS analysis of N-3 GSL, however, the characteristic molecular ions that can elucidate the structure of N-3 GSL were not obtained. In order to confirm the results obtained from TLC/SIMS, N-1, -2, and -3, GSLs were tested by LILA with specific antibodies against GlcCer, LacCer, and Gb4, respectively. N-1 GSL had reactivity to anti-GlcCer antibody and N-2 GSL reacted with the antibody against LacCer. However, N-3 GSL was not recognized by anti-Gb4 antibody. Using anti-GlcCer and anti-LacCer antibodies, furthermore, we studied the expression of GlcCer and LacCer in T. brucei parasites. Both GlcCer and LacCer were detected on the cell surface of T. brucei.

Isolation and characterization of gangliosides from Trypanosoma brucei

Gangliosides were isolated from Trypanosoma brucei and analyzed by thin-layer chromatography (TLC) and TLC immunostaining test. Four species of gangliosides, designated as G-1, G-2, G-3, and G-4, were separated by TLC. G-1 ganglioside had the same TLC migration rate as GM3. In contrast, G-2, G-3, and G-4 gangliosides migrated a little slower than GM1, GD1a, and GD1b, respectively. To characterize the molecular species of gangliosides from T. brucei, G-1, G-2, G-3, and G-4 gangliosides were purified and analyzed by TLC immunostaining test with monoclonal antibodies against gangliosides. G-1 ganglioside showed the reactivity to the monoclonal antibody against ganglioside GM3. G-2 was recognized by the anti-GM1 monoclonal antibody. G-3 showed reaction with the monoclonal antibody to GD1a. G-4 had the reactivity to anti-GD1b monoclonal antibody. Using 4 kinds of monoclonal antibodies, we also studied the expression of GM3, GM1, GD1a, and GD1b in T. brucei parasites. GM3, GM1, GD1a, and GD1b were detected on the cell surface of T. brucei. These results suggest that G-1, G-2, G-3, and G-4 gangliosides are GM3 (NeuAc alpha2-3Gal beta1-4Glc beta1-1Cer), GM1 (Gal beta1-3GalNAc beta1-4[NeuAc alpha2-3]Gal beta1-4Glc beta1-1Cer), GD1a (NeuAc alpha2-3Gal beta1-3GalNAc beta1-4[NeuAc alpha2-3]Gal beta1-4Glc beta1-1Cer), and GD1b (Gal beta1-3GalNAc beta1-4[NeuAc alpha2-8NeuAc alpha2-3]Gal beta1-4Glc beta1-1Cer), respectively, and also that they are expressed on the cell surface of T. brucei.

Reactivity of chagasic sera with crude and highly purified glycosphingolipid fractions from Trypanosoma cruzi epimastigotes

The reactivities of sera from patients with Chagas disease or from T. cruzi-immunized rabbits with two different lipid preparations of T. cruzi were assessed using epimastigote antigens. Serum reactivities were determined using a quantitative enzyme-linked immunosorbent assay (ELISA). Antigen 1 represents the lower phase obtained from crude lipid extract after Folch partition (LCL). Antigen 2 is a highly purified glycosphingolipid fraction (GSL). The LCL antigen discriminated quite well the reactivities of Chagasic patients' sera and sera from healthy individuals, as well as between the serum from a T. cruzi-immunized rabbit (TIRS) and normal rabbit serum (NRS). A strong reactivity with GSL was obtained with TIRS. Reactivity with GSL was also obtained with human Chagasic sera. Compared to a group of normal individuals, the reactions of antibodies directed against lipid antigens were considerably increased in sera of patients with Chagas disease. Chagasic sera did not differentiate between glycolipids with terminal beta-glucosyl or beta-galactosyl non-reducing units. They discriminated, however, glucosylceramides with differences in the ceramide structure. To determine the specificity of Chagasic sera, antibodies isolated on LCL-immunosorbent (LCL-Ch Abs) as well as on laminin-immunosorbent (Lam-Ch Abs) were tested against laminin and LCL antigens. We found that Lam-Ch Abs reacted with murine laminin, whereas the reaction was negative with LCL. In contrast, the LCL-Ch Abs reacted either with LCL antigens or with laminin. The reactivity with laminin was strong in comparison with LCL.(ABSTRACT TRUNCATED AT 250 WORDS)

Membrane-associated polysaccharides composition, nutritional requirements and cell differentiation in Herpetomonas roitmani: influence of the endosymbiont

Herpetomonas roitmani, a trypanosomatid containing a bacterial endosymbiont, was cured by high doses of chloramphenicol. Wild-type and cured flagellates were compared as to polysaccharide composition, nutritional requirements and cellular differentiation. Fucose (18.0%), xylose (15.7%), mannose (38.9%), galactose (10.8%), glucose (16.4%) and inositol (< 1.0%) were identified as polysaccharide components of cured H. roitmani as assessed by gas-liquid chromatography. However, the wild-type strain displayed a markedly different sugar profile, in that xylose was absent and inositol preferentially synthesized, whereas the other monosaccharide components remained unchanged. Variations in nutritional pattern also occurred between both strains. The bacterial endosymbiont seems to provide the flagellates with nutritional factors, including usual amino acids, vitamins, purine (as adenine) and hemin. The process of cell differentiation was also significantly influenced by the endosymbiont. Opisthomastigote forms predominate (72.0%) in cured as compared with wild-type H. roitmani (37.0%).

Structural characterization of neutral glycosphingolipids from Trypanosoma cruzi

The major neutral glycosphingolipids from Trypanosoma cruzi ceramide mono- and dihexosides (CMH and CDH, respectively) were analysed after chromatographic purification using 1H 500 MHz nuclear magnetic resonance spectroscopy and fast atom bombardment mass spectrometry. The ceramide monohexoside fraction (CMH) contained both glucosyl- and galactosylceramides. After peracetylation, the CMH fraction was separated into 2 subfractions, CMH-COH and CMH-Cn, containing either hydroxy fatty acids or n-fatty acids. In the CMH-COH fraction glucose and galactose were present in a ratio of 2:1, whereas this ratio was 1:1 in the CMH-Cn fraction. The CDH fraction was identified as lactosylceramide with sphingosine as the long chain base and 16:0, 18:0, and 24:0, 24:4 fatty acids as major components.

Labeling and initial characterization of polar lipids in cultures of Plasmodium falciparum

The present report describes the radioactive labeling of polar lipids in in vitro cultures of Plasmodium falciparum as well as their extraction with organic solvents and their partial characterization by chemical and enzymatic methods. All substances detected could be cleaved by alkali, suggesting that they were esters rather than sphingolipids or compounds containing alkyl groups. Dolichol-cycle intermediates were not detected. Phosphatidylinositol, phosphatidylethanolamine, and phosphatidylcholine were labeled by fatty acids and inositol or ethanolamine, respectively, confirming their de novo synthesis by the parasite. Metabolic labeling with glucosamine and cleavage by phosphatidylinositol-specific phospholipase C provided evidence of the formation of N-acetyl-glucosaminyl-phosphatidylinositol, an obligate precursor in the biosynthesis of glycosylphosphatidylinositol membrane anchors of proteins.

Amphotericin B-induced damage of Trypanosoma cruzi epimastigotes

Amphotericin B (AmB) autoxidation resulted in oxygen consumption, superoxide anion formation and production of thiobarbituric acid (TBA)-reactive material (malondialdehyde). Malondialdehyde formation increased after incubation of the drug with ascorbate-ADP-FeCl3. Growth of Trypanosoma cruzi epimastigotes in the presence of AmB induced a decrease in the free fatty acid content of the cells (57% in control cells vs. 7% in AmB-treated cells), and in the proportion of unsaturated fatty acids as well as cell killing. No changes were detected on sterol content. No evidence was found for lipid peroxidation as a mechanism of cell injury by this antibiotic.

Polysaccharide and glycolipid composition in Tritrichomonas foetus

1. The polysaccharide and glycolipid composition in Tritrichomonas foetus was studied by paper, thin-layer and gas-liquid chromatographic analysis. 2. The carbohydrate components of the polysaccharide were glucose (47%), galactose (34%) and mannose (19%). N-acetylneuraminic acid was the sialic acid derivative characterized in the flagellate whole cells. 3. The sialic acid density was estimated as 2.7 x 10(7) residues/cell. 4. The long-chain base dihydrosphingosine, the carbohydrates galactose (67%), glucose (21%) and mannose (12%) as well as the fatty acids myristic (48%) and palmitic (52%) acids were characterized as components of the total glycolipids of T. foetus. 5. Total glycolipids were fractionated: a galactocerebroside and a ganglioside were identified.

Further characterization of carbohydrate-containing fractions from Trypanosoma mega

Epimastigotes of Trypanosoma mega were submitted to phenol extraction after lipid extraction, providing an extract whose carbohydrate portion (30%) contained fucose, ribose, xylose, mannose, galactose, and glucose. The purified fraction recovered in the void volume of Bio Gel P-150 gave on SDS-PAGE a band of Mr approximately equal to 55,000 positive for protein and carbohydrate and a diffuse band strongly positive for carbohydrate and lipids (Mr approximately equal to 22,000). The structural analysis of the carbohydrate moiety of this fraction by GLC-MS indicated the presence of nonreducing end groups of fucopyranose, mannopyranose, and galactopyranose, 3-O- and 4-O-substituted and 2,3- and 2,4-di-O-substituted galactopyranosyl units. Extraction of this fraction with chloroform/methanol/water provided a soluble fraction that on SDS-PAGE gave rise to a carbohydrate and lipid-positive band (Mr approximately equal to 22,000). This fraction contained fucose, mannose, and galactose (1:1:1). As main branch points, 2,3-di-O-substituted galactopyranosyl units were present according to methylation data. Similar proportions of fucopyranosyl, mannopyranosyl, galactopyranosyl end units were present. The presence of lipids in this fraction was confirmed by methanolysis following isolation and characterization of the corresponding fatty acid methyl esters. Palmitic acid (16:0) and an 18:1 fatty acid were the predominant fatty acids.