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At least 217 records · Page 12Linked to original sources
PubMed1995

Characterization of Biomphalaria alexandrina-derived lectins recognizing a fucosyllactose-related determinant on schistosomes.

Two novel lectins that bind selectively to a schistosome-associated fucosyllactose-related determinant have been characterized and purified from the hemolymph of Biomphalaria alexandrina, the snail vector of Schistosoma mansoni. Both lectins were purified by affinity chromatography on a column of equimolar mixture of D- and L-glucose coupled to epoxy-activated Sepharose 6B and sequential elution by D-glucose (designated BaSI) and L-fucose (designated BaSII). Assessment of the structural characteristics, by one- and two-dimensional polyacrylamide gel electrophoresis, indicated that BaSI and BaSII were structurally distinct, and exist in their native forms as multimers of non-covalently associated subunits, that were of different sizes in BaSI and of equal size in BaSII. Removal of N-linked glycans by Endo-beta-N-acetylglucosaminidase F resolved the heterodisperse pattern of BaSI subunits into two spots of 13.2 kDa (pI 7.2) and 10.1 kDa (pI 5.8), and collapsed the acidic charge microheterogeneity of the BaSII subunit into a single spot that corresponded in terms of molecular weight and pI to the basic 13.2-kDa subunit of BaSI. In miracidial binding and inhibition assays with different sugars, both lectins exhibited selectivity towards a fucosyllactose sequence, but BaSII had a higher binding preference to fucose moieties. BaSII-Sepharose 4B affinity chromatography and analysis on two-dimensional gels indicated that multiple copies of the fucosyllactose-related determinant were expressed by heterogeneous, acidic glycoproteins in the miracidial stage of S. mansoni.

Animals↗
PubMed1983

Isolation and characterization of a lectin from the snail Biomphalaria glabrata and a study of its combining site.

The hemagglutinins from the spawn of the water snail Biomphalaria glabrata were isolated by affinity chromatography on hog gastric mucin coupled to Sepharose 4B. The N-acetyl-D-glucosamine eluate (0.1 M) was fractionated further on Bio-Gel P-300, yielding two fractions. Fraction 1 had an Mr of 350 000 and displayed one band in immunoelectrophoresis, but was heterogeneous in discontinuous electrophoresis. It agglutinated human red blood cells with A1 and B specificity at concentrations of 12 and 72 micrograms nitrogen/ml, respectively. Fraction 2 had an Mr on gel filtration of 67 000 and was homogeneous in immuno- and polyacrylamide electrophoresis, and in isoelectrofocusing. It is composed of three subunits with Mr of 17 000 and one smaller subunit of 15 000. This fraction (lectin I) is a glycoprotein containing 6% hexoses and 2.5% hexosamines. For minimal agglutination of human A1 and B red blood cells 2.4 and 72.0 micrograms nitrogen/ml, respectively, of lectin I were required. O red blood cells were not agglutinated. Lectin I precipitated well with a human blood group substance of A1 specificity, moderately with a B- and poorly with an H-substance. Precipitin-inhibition studies revealed that among other sugars N-acetylneuraminic acid was the most potent inhibitor. Immunofluorescence studies confirmed the good interaction of lectin I with receptors of A1 and B erythrocytes and the failure of lectin I to attach to O-erythrocytes. Since N-acetylneuraminic acid is present on the cell surface of all human erythrocytes, it cannot be the dominant part of the receptor for the B. glabrata lectin I, despite its effectiveness as an inhibitor.

ABO Blood-Group System↗
PubMed1987

Biomphalaria glabrata: respiration, calcium and end products of carbohydrate metabolism.

1. Lactic acid and succinic acid (end products of anaerobiosis) also occur under aerobic conditions in the haemolymph and excretion products of Biomphalaria glabrata. This phenomenon has been investigated in more detail. 2. Experiments on oxygen uptake, and analyses of organic acid, amino acid and calcium were carried out under various aerating conditions, various temperatures and in various water qualities. 3. No differences were found in the concentrations of the organic acids and calcium in the haemolymph under different aerating conditions. 4. Neither snail-conditioned water, nor artificial crowding effects played a role in the initiation of anaerobic respiration. 5. A low exposure temperature (4 degrees C) initiated anaerobic respiration in spite of the aeration.

Aerobiosis↗
PubMed1989

The biochemical ecology of Biomphalaria glabrata, a snail host of Schistosoma mansoni: short chain carboxylic and amino acids as phagostimulants.

1. A buccal mass olfactometer was used to investigate the responses of the fresh-water pulmonate snail Biomphalaria glabrata to carboxylic and amino acids. 2. The snails proved very discriminating as only 6 (14.6%) of the 41 chemical species tested were effective as phagostimulants. These are ranked as follows in order of potency:- butanoate greater than propanoate greater than D-malate greater than 2-hydroxybutanoate = L-tartrate = L-aspartate. 3. The structure-activity relationships of the active compounds, and their significance to the ecology and control of the snails are discussed.

Amino Acids↗
PubMed1991

Reversal of dietary-induced hyperlipidemia in Biomphalaria glabrata (Gastropoda).

1. To determine if dietary induced hyperlipidemia in snails could be reversed, thin-layer chromatography studies were done on lipids in the digestive gland-gonad (DGG) complex of Biomphalaria glabrata fed either hen's egg yolk for 2 weeks (Group A), yolk for 1 week followed by leaf lettuce for 1 week (Group B), or lettuce for 2 weeks (Group C). 2. The major lipid fractions in Group A were triacylglycerols, phosphatidylethanolamine, and phosphatidylcholine, along with lesser amounts of sterol esters, methyl esters, free fatty acids, free sterols and unidentified phospholipids. 3. Groups B and C had about one-half the amount of triacylglycerols than Group A and did not show sterol esters or methyl esters. 4. The triacylglycerol increase of the DGG resulting from the hen's egg diet could be reversed by returning the snails to the lettuce diet.

Animals↗
PubMed1996

Biogenic monoamines in the freshwater snail, Biomphalaria glabrata: influence of infection by the human blood fluke, Schistosoma mansoni.

The biogenic monoamines, serotonin (5-HT), dopamine (DA) and L-dopa were measured using high performance liquid chromatography with electrochemical detection (HPLC-ED) in the extracts of the central nervous system (CNS) and plasma of uninfected freshwater snails, Biomphalaria glabrata, and in snails at 7, 14, 21 and 28 days postexposure (PE) to the miracidia of the human blood fluke, Schistosoma mansoni. Relative to age-matched uninfected snails, a general depression of biogenic amine levels was observed in the plasma (cell-free haemolymph) and the CNS of infected snails, especially during the latter phase of the prepatency period. Significant decreases were first observed in the CNS of infected snails beginning at Day 14 PE for DA and 5-HT and Day 21 PE for L-dopa. Parasite-exposed snails also exhibited an early and persistent suppression of plasma 5-HT concentrations, starting at 7 days PE and continuing throughout the infection test period. In order to determine the effect of 5-HT on reproduction and, thereby, establish a possible relationship between the observed parasite-induced reduction in 5-HT levels and parasitic castration, the effect of exogenous 5-HT on individual infected and uninfected B. glabrata was investigated. Repeated treatment with 10 microM 5-HT promoted both ovulation and oviposition in B. glabrata. Snails treated with 5-HT consistently layed more eggs than did sham-treated controls. Infected snails that were treated with 5-HT exhibited similar egg-laying rates as those of both serotonin-treated and untreated, uninfected snail groups, thus reversing the castrating effects of larval infection. These findings suggest that 5-HT acts as a stimulant for egg production in B. glabrata, and that parasitic castration may be due, at least in part, to larval-induced suppression of 5-HT in the snail's CNS and plasma during the course of infection with S. mansoni.

Animals↗
PubMed1979

Alterations of the free amino acid content in the hemolymph of Biomphalaria glabrata (Pulmonata) in starvation and after infection with Schistosoma mansoni (Trematoda).

1. Analysing the free amino acid content of the hemolymph of normally fed, starved and schistosome-infected Biomphalaria glabrata we identified 22 amino acids and amines, respectively. 2. In comparison with normally fed snails the free amino acid content of starved and infected snails was significantly reduced. 3. However, only slight differences between the ornithine and citrulline content occurred in the three test groups.

Amino Acids↗
PubMed1987

Effect of Schistosoma mansoni on the gross lipid composition of its vector Biomphalaria glabrata.

1. The total lipid level of the digestive gland-gonad complex of Biomphalaria glabrata was reduced by starvation and elevated following infection with Schistosoma mansoni. 2. The lipid classes of B. glabrata were phospholipid, monoglyceride, free fatty acid, triglyceride, sterol ester and wax and a single unidentified lipid. The major lipid present in control, starved and infected tissue was sterol. Triglyceride was a minor component of control tissue. 3. Starvation reduced the relative level of the unidentified lipid but had little effect on triglyceride. 4. Infection also caused a decrease in the unidentified component but the triglyceride level was sharply elevated. 5. The phospholipid fraction of tissue from all groups was composed of phosphatidyl choline, phosphatidyl ethanolamine and phosphatidyl serine. Infection and starvation had little effect on the composition.

Animals↗
PubMed1987

Metabolism of 2-aminoethylphosphonic acid during embryonic development of the schistosomal vector Biomphalaria glabrata.

1. Egg masses of the Planorbid snail Biomphalaria glabrata contain 2-aminoethylphosphonic acid (AEP) in three different chemical environments, as determined by 31P nuclear magnetic resonance spectroscopy, giving signals at 20.9, 21.0 and 23.4 delta. 2. The signal at 21.0 delta decreased in intensity during embryonic development, whereas the other two did not change significantly. 3. The following relationship is suggested: Extraembryonic AEP--------Intraembryonic AEP--------Phosphates. 4. pH Titration behavior of macromolecularly-bound AEP and synthetic derivatives of AEP was examined and indicates that AEP is found in the egg masses linked to other molecules in the following ways: (a) R2-NH-CH2CH2-P(O)(OH)(OR1), (b) R3-NH-CH2-P(O)(OR2)(OR1), (c) NH2-CH2CH2P(O)(OH)(OR1).

Aminoethylphosphonic Acid↗
PubMed1988

Comparison of haemolymph proteins from Schistosoma mansoni (Trematoda)-susceptible and resistant Biomphalaria glabrata (Gastropoda).

1. Whole and haemoglobin (Hb)-depleted serum fractions from Schistosoma mansoni-resistant (10-R2) and schistosome-susceptible (PR albino, M-line) strains of Biomphalaria glabrata were studied using sodium dodecyl sulphate-polyacrylamide gel electrophoresis, immunoblotting and protein assays. 2. Whole serum of the PR albino strain had more total protein (11.4 +/- 1.9 mg protein/ml) than the 10-R2 strain (7.8 +/- 3.0 mg protein/ml). 3. There are specific differences in the polypeptide profiles of the Hb-depleted fractions between the 10-R2 and PR albino strains of B. glabrata. 4. Antibodies against whole 10-R2 or PR albino serum reacted similarly when incubated with whole or Hb-depleted snail sera although differences in staining intensities were observed. 5. Antibodies against snail Hb reacted with many proteins in whole sera and Hb-depleted fractions from both B. glabrata strains indicating that they may be Hb-associated polypeptides. 6. Polypeptides in whole or Hb-depleted snail serum are modified by reduction indicating the presence of disulphide bonds.

Animals↗
PubMed1989

Structural analysis of hemolymph proteins from Schistosoma mansoni (Trematoda)-susceptible and resistant Biomphalaria glabrata (Gastropoda).

1. Five different molecular weight polypeptides from serum (cell-free hemolymph) of Schistosoma mansoni-resistant and susceptible strains of Biomphalaria glabrata, were examined by two-dimensional 125I-peptide mapping and high performance liquid chromatography (HPLC). 2. Peptide mapping indicated that all five radiolabeled polypeptides within and between the two snail strains had similar migration patterns when cleaved with pepsin or alpha-chymotrypsin, thus revealing a shared structural homology. All peptides chosen for analysis appeared to be structurally similar to the 160 kDa hemoglobin molecule. 3. Separations of the radiolabeled enzyme digests by HPLC confirmed results seen in the mapping experiments since all chromatograms had similar elution patterns. 4. Minor differences in the peptide maps and chromatograms within and between snail strains may be due to quantitative differences in the amount of protein present and/or variations in the primary amino acid sequences of the proteins chosen for analysis.

Amino Acid Sequence↗
PubMed1990

Sterols in the plasma and digestive gland-gonad complex of Biomphalaria glabrata snails, fed lettuce versus hen's egg yolk, as determined by GLC.

1. Gas-liquid chromatography studies were done on sterols in plasma and the digestive gland-gonad (DGG) complex of Biomphalaria glabrata snails fed lettuce vs hen's egg yolk. 2. The major sterols present in the DGG of both populations were cholesterol, stigmasterol, beta-sitosterol, campesterol, and desmosterol. 3. The percentage composition of cholesterol in the DGG of yolk vs lettuce fed snails was 82 and 51, respectively. 4. The elution profiles of sterols in the plasma of yolk vs lettuce fed snails were similar; both contained desmosterol, campesterol, and stigmasterol, negligible amounts of cholesterol, and unidentified sterols. 5. The high lipid diet increased the level of cholesterol in the DGG but not in the plasma.

Animals↗
PubMed1991

Schistosoma mansoni and Biomphalaria glabrata have some common epitopes. I. Common epitopes are present on the surface of early stages of S. mansoni.

1. The presence of snail and glycocalyx antigens in the Schistosoma mansoni cercarial surface and their permanence throughout development in vitro and in vivo was investigated. 2. Rabbit antisera raised against two fractions of glycocalyx released from cercariae and Biomphalaria glabrata soft tissues or haemolymph were obtained. 3. All four antisera bound to cercariae and schistosomula kept in vitro or in vivo for up to 24 hr. 4. No binding to schistosomula kept in vivo for 5 days or longer was observed. 5. Schistosomula cultured in vitro for up to 12 days bound the antisera throughout the period of culture.

Animals↗
PubMed1992

Identification, comparison and partial characterization of glycoproteins in the hemolymph of Schistosoma mansoni (Trematoda)-susceptible and resistant Biomphalaria glabrata (Gastropoda).

1. Glycoproteins in the plasma (cell-free hemolymph) of Schistosoma mansoni-resistant and susceptible strains of Biomphalaria glabrata were identified, characterized and compared using sodium dodecyl sulfate-polyacrylamide gel electrophoresis, electroblotting and a series of peroxidase-labeled lectins with different sugar specificities. 2. Schistosome-resistant snails possessed at least three glycoproteins (70, 116, 205 kDa) that were not present in plasma from susceptible snails. 3. Sporocysts (larval S. mansoni) preincubated in plasma from schistosome-resistant or susceptible B. glabrata adsorbed certain glycoproteins to their surface and some altered the binding of lectin probes to the parasite. 4. This study indicates that glycoproteins in the plasma of B. glabrata are associated with S. mansoni-susceptibility and resistance.

Animals↗
PubMed1993

Comparison of hemocyte components from Schistosoma mansoni (Trematoda)-susceptible and resistant Biomphalaria glabrata (Gastropoda) that cross-react with larval schistosome surface proteins.

1. Cross-reactive antigens between larval Schistosoma mansoni and hemocytes from schistosome-resistant and susceptible strains of Biomphalaria glabrata were identified and compared using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), immunoblotting and surface radioiodination. 2. Four sporocyst (larval S. mansoni) surface antigens (27, 39, 40 and 70 kDa) reacted with antibodies to hemocytes from resistant snails whereas only one surface antigen (70 kDa) was recognized by antibodies to hemocytes from susceptible B. glabrata. 3. The wider distribution and greater frequency of cross-reactive antigens between resistant hemocytes and sporocysts suggests that such cross-reactivity may be involved in the hemocyte-mediated killing of larval schistosomes that occurs in this host-parasite system.

Animals↗
PubMed1995

Effects of diet on the lipid composition of the digestive gland-gonad complex of Biomphalaria glabrata (Gastropoda) infected with larval Echinostoma caproni (Trematoda).

This study examined the effects of a larval Echinostoma caproni infection on the neutral lipid composition of the digestive gland-gonad complex (DGG) of Biomphalaria glabrata snails fed hen's egg yolk supplemented with lettuce (Y-L) or lettuce supplemented with Tetramin (L-T). Snails were experimentally infected with the miracidial stage of this echinostome, and their DGGs containing daughter rediae were analyzed for neutral lipids five weeks post-infection by qualitative and quantitative thin-layer chromatography. Light microscopy using Oil Red O (ORO) staining and transmission electron microscopy (TEM) were used to localize neutral lipids in the rediae. The DGGs of infected snails maintained on the Y-L diet showed a significant increase in free sterols and a significant decrease in triacylglycerols compared to uninfected snails maintained on the Y-L diet. The DGGs of infected snails maintained on the L-T diet showed no significant difference in free sterols or triacylglycerols compared to uninfected snails maintained on the L-T diet. ORO staining and TEM showed the presence of lipid droplets in rediae from snails on the Y-L diet. The significant decrease in triacylglycerols in the DGGs of infected snails maintained on the Y-L diet suggests that triacylglycerols were utilized by the rediae.

Animals↗
PubMed1996

Phenoloxidase activity in the reproductive system and egg masses of the pulmonate gastropod, Biomphalaria glabrata.

Phenoloxidase (PO) activity in the albumen gland (AG) and egg masses (EM) of Biomphalaria glabrata was assessed using high-performance liquid chromatography combined with electrochemical detection and colorimetric techniques. Both AG and EM extracts catalyzed the hydroxylation of L-tyrosine (monophenol oxidase activity, MPO) and oxidation of L-dopa (diphenol oxidase activity, DPO). However, no PO activity was found in the ovotestis. Both MPO and DPO activities in AG and EM were significantly inhibited by 1-phenyl-2-thiourea and inactivated by boiling. Approximately 35% of MPO and 44% of DPO activities were detected in the soluble fraction of homogenized EM, in contrast to that of homogenized AG, which contained about 5% and 12%, respectively, of MPO and DPO activities. N-acetyl-dopamine, a diphenolic compound, enhanced the hydroxylation of tyrosine by the PO. The presence of both MPO and DPO activities also was confirmed by the accelerated accumulation of dopachrome during incubation of EM extracts with L-tyrosine in the absence of ascorbate. Temperature and pH optima for this enzyme were 30 degrees C and 7.5, respectively. The potential roles of PO in egg formation in B glabrata are discussed.

Animals↗
PubMed1992

Identification of a repetitive element in the snail Biomphalaria glabrata: relationship to the reverse transcriptase-encoding sequence in LINE-1 transposons.

BamHI-digested Biomphalaria glabrata DNA contains a repetitive 2.0-kb fragment which is readily discernible by ethidium bromide staining. We present evidence that this repetitive element is related at both the nucleotide and amino acid levels to long interspersed nuclear element (LINE)-like transposons. Although comparable elements have been described in several invertebrates, this is the first report of a molluscan homologue. In common with LINE transposons, an open reading frame in the B. glabrata element shows significant homology to reverse transcriptase--a feature believed to allow the dissemination of these elements in the eukaryotic genome.

Amino Acid Sequence↗