Schistosoma mansoni: distribution and characteristics of alkaline and acid phosphatase

The biochemical distribution and characteristics of the alkaline and acid phosphatase activities in both sexes of Schistosoma mansoni are reported. Alkaline and acid phosphatase activities were found in the epidermis as well as in the internal tissues. Alkaline activity is mostly located within the epidermis in both sexes. The acid activity is high in the epidermis of males and more or less equally distributed in females.Starch gel electrophoresis of worm homogenates revealed two sites of activity for both phosphatases. One is an anodic band which is a soluble phosphatase, the other, a membrane bound phosphatase, which remains at the origin under the electrophoretic conditions used. These findings are discussed in relation to previous results and to the possible roles played by these enzymes in adult S. mansoni.     

Evidence for the presence of active cytochrome P450 systems in Schistosoma mansoni and Schistosoma haematobium adult worms

Extracts of the adult worms of both Schistosoma mansoni and Schistosoma haematobium can metabolise some typical P450 substrates but to differing degrees. S. mansoni worm extracts displayed a approximately 12-fold higher specific activity for an aminopyrine substrate than rat liver microsomes. At 4 mM substrate concentration the demethylation reaction with N-nitrosodimethylamine (NDMA) (5 nmol HCHO/mg protein/min) was only half that of rat liver microsomes, whereas in extracts of S. haematobium, no detectable activity was found towards NDMA. Using ethylmorphine as substrate the demethylation activity of S. mansoni extracts (1.82 nmol HCHO/mg protein/min) was 5.5-fold lower than that of rat liver microsomes. Benzphetamine demethylase activity was also readily detectable in S. mansoni worm extracts at 6.79 nmol HCHO/mg protein/min compared with 10.20 nmol HCHO/mg protein/min in the case of rat liver microsomes. When aniline was used as substrate, surprisingly, no activity was found in worm extracts of either S. mansoni or S. haematobium, whereas rat liver microsomes showed high activity towards this amine. The anti-P450 2E1 and 2B1/2 cross-reacted with both worm homogenates and gave a specific band corresponding to a protein of molecular weight of approximately 50.0 kDa. A study with anti-P450 IVA antibody revealed that while this protein was strongly expressed in S. haematobium worm extracts, no immunoreactivity was observed with extracts of S. mansoni. Immunoblotting analyses with anti-P450 IIIA and P450 1A1 did not detect immunoreactive protein in either S. mansoni or S. haematobium.     

Long-term infection with Schistosoma mansoni (Gezira strain--Sudan) in the Nile rat (Arvicanthis niloticus)

The long-term infection with Schistosoma mansoni (Gezira strain--Sudan) was studied in the Nile rat (Arvicanthis niloticus) to investigate the 'self cure' phenomenon. The results indicated that while a considerable number of worms and eggs were still recovered by week 28 post-infection, elimination of some of the worms occurred by week 20.     

Neuroinflammatory implications of Schistosoma mansoni infection: new information from the mouse model

Schistosoma mansoni infection is known to induce granulomas, not only in the liver and intestine, but also in the brain, resulting in neuropathological and psychiatric disorders. In the past, the interaction between Schistosoma mansoni infection and the nervous system has received little attention. Here, Luigi Aloe and Marco Fiore discuss recent findings from experimental Schistosoma mansoni infection in the mouse nervous system showing that brain granulomas are associated with a significant alteration in the constitutive expression of nerve growth factor, a neurotrophic factor that plays an essential role in growth and differentiation and in preventing neuronal damage. These findings suggest that the neuropathological dysfunctions in neuroschistosomiasis may be linked to changes in the basal levels and/or activity of neurotrophic factors caused by local formation of granulomas.     

Catecholamine-containing neurons in Schistosoma mansoni

Summary Falck's method for the demonstration of monoamines was applied to the flatworm Schistosoma mansoni. Whole mount preparations and sections of frozen dried specimens showed that a primary catecholamine is present in four pairs of large nerve cells and in two longitudinal fiber tracts showing varicosities. Smaller neurons were found along these tracts. They are united by commissures and give off many branches which end in small dilatations.Contribution number 14 from the Schistosomiasis Research Unit, Institute of Biological Sciences, Federal University of Minas Gerais, Brazil. This study has been supported by research grants from the U.S. Army (DAAC 19-70-G-0023 and DAHG-70-G-0028), CAPES and Conselho Nacional de Pesquisas, Brazil. For technical assistance we thank Mr. Rubens Miranda, technician supported by the Conselho Nacional de Pesquisas of Brazil.     

Fucosyltransferases in Schistosoma mansoni development

Glycoconjugate-bound fucose, abundant in the parasite Schistosoma mansoni, has been found in the form of Fucalpha1,3GlcNAc, Fucalpha1,2Fuc, Fucalpha1,6GlcNAc, and perhaps Fucalpha1,4GlcNAc linkages. Here we quantify fucosyltransferase activities in three developmental stages of S. mansoni. Assays were performed using fluorophore-assisted carbohydrate electrophoresis with detection of radioactive fucose incorporation from GDP-[(14)C]-fucose into structurally defined acceptors. The total fucosyltransferase-specific activity in egg extracts was 50-fold higher than that in the other life stages tested (cercaria and adult worms). A fucosyltransferase was detected that transferred fucose to type-2 oligosaccharides (Galbeta1,4GlcNAc-R), both sialylated (with the sialic acid attached to the terminal Gal by alpha2,3 or 2,6 linkage) and nonsialylated. Another fucosyltransferase was identified that transferred fucose to lactose-based and type-2 fucosylated oligosaccharides, such as LNFIII (Galbeta1,4(Fucalpha1,3)GlcNAcbeta1,3Galbeta1,4Glc). A low level of fucosyltransferase that transfers fucose to no-sialylated type-1 oligosaccharides (Galbeta1,3GlcNAc-R) was also detected. These studies revealed multifucosylated products of the reactions. In addition, the effects of fucose-type iminosugars inhibitors were tested on schistosome fucosyltransferases. A new fucose-type 1-N-iminosugar was four- to sixfold more potent as an inhibitor of schistosome fucosyltransferases in vitro than was deoxyfuconojirimycin. In vivo, this novel 1-iminosugar blocked the expression of a fucosylated epitope (mAb 128C3/3 antigen) that is associated with the pathogenesis of schistosomiasis.     

Schistosoma mansoni and Schistosoma japonicum: Utilization of amino acids

, , and 1972. Schistosoma mansoni and Schistosoma japonicum: utilization of amino acids. International Journal for Parasitology 2: 425–430. The production of ¹⁴CO₂ from 12 labeled amino acids by S. mansoni and S. japonicum was studied. No ¹⁴CO₂ was detected from incubations with glycine, isoleucine, leucine, lysine or phenylalanine. Differences were found between sexes and/or species for the other amino acids studied. Species related differences included a greater rate of metabolism of glutamic and aspartic acid by S. mansoni than by S. japonicum. Proline and histidine were utilized by S. mansoni males and females, respectively. S. japonicum male worms did not utilize proline, while histidine was not utilized by the female of this species. Major sex related differences included greater ¹⁴CO₂ production from glutamic acid, aspartic acid and arginine by S. mansoni males than by females, and the utilization of histidine by male S. japonicum but not by females. Incubation in tyrosine resulted in the release of only small amounts of ¹⁴CO₂ by female worms of both species but no ¹⁴CO₂ production by male worms.     

Underestimation of Schistosoma mansoni prevalences

Field methods used for detecting Schistosoma mansoni infection miss a certain proportion of the infections. Prevalences of infection appear to be far under-estimated by faecal screening, with important consequences for control and research. Sake de Vlos and Bruno Gryseels investigate how the number of undetected infections can be statistically inferred from population surveys.