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Query: UNIPROT:P02794 (ferritin)
 17,525 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Recombinant clones of Schistosoma mansoni cDNA libraries containing the complete coding regions of 2 different ferritin subunits have been isolated and sequenced. This allows for the first time a comparison of ferritin sequences from an invertebrate with those of vertebrates. The deduced amino acid sequences of both Schistosoma ferritin subunit clones show significant homology to vertebrate ferritin H chains. Similarity exceeds 50% identity and includes the recently identified ferroxidase center which is present only in H chains. However, non-conservative substitutions of amino acid residues lining the 3-fold symmetry channel were found, and a gap of 3 successive amino acids unique to the 2 Schistosoma ferritin sequences was identified. Remarkably, for each of the 2 genes, we found a conspicuous difference in the amount of ferritin transcripts between females and males: one of the genes is preferentially expressed in females, the other in males.
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PMID:Ferritins of Schistosoma mansoni: sequence comparison and expression in female and male worms. 174 Oct 11

Separation of the external membranes from freshly converted mechanical schistosomula of Schistosoma mansoni was achieved by osmotic shock under hypertonic conditions, followed by mechanical shearing and ultracentrifugation. Prior to treatment, the schistosomula were surface labeled by introduction of N-DNP-epsilon-aminocaproylphosphatidylethanolamine molecules into their lipid bilayer followed by anti-DNP antibodies and stained with either 125I-protein-A or ferritin labeled secondary anti-DNP antibodies. This label provided a membrane marker by which the purity of the preparation could be assessed at each stage. Fluorescence staining with FITC-conjugated secondary antibodies prior to treatment revealed that the homogeneously stained membrane of the intact schistosomula became swollen and ruptured after the osmotic shock. The isolated membrane pellet was intensely fluorescent. Electron microscopical examination revealed mostly vesicles, some of them with organized multilayer assembly. The vesicles were ferritin labeled, indicating that they originated from the outer surface membrane of the schistosomula. A 100 fold enrichment in the alkaline phosphatase activity and about 300 fold enrichment in acetylcholinesterase activity in the membrane preparations, as compared to the intact schistosomula, was found. The isolated tegument was analyzed by SDS-polyacrylamide gel electrophoresis. The pattern obtained showed three major bands, of molecular weights 69 000, 45 000 and 12 000 alongside with a large number of minor bands. Immunoprecipitation of the isolated 125I-labeled membrane antigens with antisera from chronically infected mice revealed these three major bands together with three other bands of molecular weight 38 000, 23 000 and 16 000.
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PMID:Isolation and partial characterization of the tegumental outer membrane of schistosomula of Schistosoma mansoni. 652 92

Introduction of synthetic antigens into the surface of schistosomula of Schistosoma mansoni was achieved by brief incubation of the worms with liposomes carrying the lipid-bound antigens in their bilayers. Three-hour-old schistosomula were surface-labeled with lipid-conjugated dinitrophenyl (DNP) groups by using liposomes made of egg lecithin-N-dinitrophenil-epsilon-aminocaproyl-phosphatidylethanolamine (5:1). The DNP groups incorporated in this way could be detected for more than 21 hours in vitro by using rabbit anti-DNP antibodies stained with fluorescein isothiocyanate-conjugated goat anti-rabbit IgG. Immunofluorescence microscopy showed the lipid antigen to be uniformly distributed over the entire surface of the worms. Electron microscope studies, performed with purified rabbit anti-DNP antibodies followed by ferritin-conjugated goat anti-rabbit IgG, showed that the DNP groups were evenly and densely distributed over the entire outer membrane of the schistosomula, including spines. The distance between the ferritin molecules and the parasite's surface was 24 +/- 5 nm, indicating that the lipid antigen had been incorporated into the outer membrane of the schistosomula.
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PMID:A method of introducing lipid-conjugated antigens into the surface of schistosomula. 683 44

The outer and inner bilayers of the apical membrane complex of Schistosoma mansoni were sequentially stripped from adult worms by two incubations in 0.1% digitonin solutions. Membrane removal was evaluated by electron microscopy of worms and bilayer material, using Con A-ferritin as a marker for the outer bilayer. Amounts of Con A removed by the digests were measured with a tritiated Con A marker. To measure the purity of the fractions membrane markers were characterised and quantitated for both bilayers. In the absence of the usual enzymatic markers for plasma membrane diazotised [125I]-iodosulfanilic acid was used as a marker for the outer bilayer. Alkaline phosphatase and a Na+, Mg2+-ATPase were localised to the inner bilayer. From these results we can deduce that the inner bilayer is analogous to the typical, apical plasma membrane of other animal epithelia. The outer bilayer does not share these enzymatic similarities. The integrity of the syncytium after removal of the outer bilayer and the increased levels of lactate dehydrogenase in the supernatant after removal of the inner bilayer suggests that the outer bilayer is secondary in maintaining the permeability barrier of the apical membrane complex, with respect to soluble proteins. The possible significance of these results in terms of the destructive action of complement on the parasite are discussed.
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PMID:Sequential removal of outer bilayer and apical plasma membrane from the surface epithelial syncytium of Schistosoma mansoni. 685 11

Schistosoma mansoni possesses two isoforms of the iron storage protein ferritin, Fer1 and Fer2. At the mRNA level as well as at the protein level, Fer1 is much more abundant than Fer2; females contain an about 15-fold excess of Fer1 compared with males. In contrast, nearly equal amounts of Fer2 occur in both sexes. By electron microscopy we identified ferritin as a component of electron dense membrane-bound bodies in cells of the vitellarium. The mode of formation of these inclusions (as inferred from electron microscopy) and the abundance of phospholipid multilayered membranes suggest that these bodies are of a lysosomal nature. Here we interpret these ferritin-containing inclusions as protein yolk platelets. To date, most of the literature does not contain any hints of the existence of protein yolk in trematodes. The possible function of ferritin in embryonic development is discussed.
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PMID:An isoform of ferritin as a component of protein yolk platelets in Schistosoma mansoni. 858 31

Schistosoma mansoni possesses two isoforms of ferritin, soma and yolk ferritin. The soma ferritin occurs at a low level in most cells of both genders, whereas the yolk ferritin is a female-specific gene product that is expressed at high level in the vitellarium. In higher animals, ferritin mRNA is regulated by iron via the interaction of cytoplasmic binding proteins (IRPs) with a specific sequence element in the 5' untranslated region (UTR) referred to as the iron-responsive element (IRE). Sequence studies of the 5' UTRs, gel retardation assays, and hybridization experiments show that neither ferritin mRNAs of S. mansoni is regulated by an IRE/IRP mechanism. It is suggested that ferritins in schistosomes are controlled only at the transcriptional level.
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PMID:Ferritin mRNAs in Schistosoma mansoni do not have iron-responsive elements for post-transcriptional regulation. 889 89

A cross-sectional study of 729 children and adults in western Kenya investigated the impact of infection with hookworm, Ascaris lumbricoides, Trichuris trichiura, Schistosoma mansoni and malaria on iron status. In bivariate analyses, hookworm intensities as low as 300 eggs/g of faeces were negatively related to levels of haemoglobin (Hb) and serum ferritin (SF). Malaria parasitaemia was negatively related to Hb and positively related to SF, while S. mansoni intensities were negatively related to SF. Multivariate regression analysis was done to identify predictors of Hb and SF levels. In children, age (in years) was the only predictor for Hb (B = 1.7 g/L) and only malaria parasitaemia (negative, light, moderate, heavy) was retained in the model for log10 SF (B = 0.097 microgram/L). In adults, hookworm infection and malaria parasitaemia together with age, sex, pregnancy, SF levels < 12 micrograms/L and elevated body temperature were significant predictors of low Hb. The regression coefficient for hookworm egg count (for increments of 100 eggs/g) was -1.3 g/L. Significant interactions between sex and age and between sex and malaria parasitaemia were revealed. Age and malaria parasitaemia were significant predictors only among females, with a regression coefficient for malaria parasitaemia of -6.9 g/L. The regression coefficient for hookworm did not change when SF < 12 micrograms/L was taken out of the model, indicating that the effect of hookworm cannot be explained by low iron stores alone. Using SF as the dependent variable, hookworm and S. mansoni intensities together with age and sex were retained in the model. The regression coefficients for hookworm egg count (increments of 100 eggs/g) and S. mansoni egg count (increments of 10 eggs/g) were -0.011 microgram/L and -0.012 microgram/L, respectively. Iron deficiency was a problem in this population and hookworm infections contributed significantly to this situation.
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PMID:The contribution of hookworm and other parasitic infections to haemoglobin and iron status among children and adults in western Kenya. 1032 10

Biomphalaria glabrata is an intermediate snail host for Schistosoma mansoni, a medically important schistosome. In order to identify transcripts involved in snail-schistosome interactions, subtractive cDNA libraries were prepared, using suppression subtractive hybridization (SSH) between a parasite-exposed schistosome-resistant and a susceptible strain of B. glabrata, and also between schistosome-exposed and unexposed snails from the resistant snail line. Separate libraries were made from both haemocytes and the haemopoietic organ. Subtraction was performed in both directions enriching for cDNAs differentially expressed between parasite-exposed resistant and susceptible samples and up or down-regulated in the resistant line after challenge. The resulting eight libraries were screened and eight genes, differentially expressed between the haemocytes of resistant and susceptible snail strains, were identified and confirmed with reverse transcriptase PCR, including two transcripts expected to be involved in the stress response mechanism for regulating the damaging oxidative burst pathways involved in cytotoxic killing of the parasite: the iron-storage and immunoregulatory molecule, ferritin, and HtrA2, a serine protease involved in the cellular stress response. Transcripts with elevated levels in the resistant strain, had the same expression patterns in the subtracted libraries and unsubtracted controls; higher levels in exposed resistant snails compared to susceptible ones and down-regulated in exposed compared with unexposed resistant snails. Differential expression of two of the transcripts with no known function from the susceptible strain, was independently confirmed in a repeat exposure experiment.
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PMID:Identification of genes involved in interactions between Biomphalaria glabrata and Schistosoma mansoni by suppression subtractive hybridization. 1708 33

Iron deficiency is widespread in sub-Saharan Africa, but its predictors are not fully understood. We conducted a cross-sectional study among adults around Lake Victoria to describe iron status and asses the role of dietary and infectious predictors. Linear regression analyses were used to assess the role of infections and intake of meat, fish, fruit/vegetables, alcoholic beverages, and soil on hemoglobin and serum ferritin, while controlling for elevated serum alpha(1)-antichymotrypsin (ACT). Among 1498 participants, the mean age was 33.3 (14-87) y with 53.9% females. More than one-half ate fish daily, 6% ate fruit/vegetables daily, and only 11% ate meat weekly. One-third consumed alcoholic beverages and one-fifth of females consumed soil. Hookworm (80.3%), Schistosoma mansoni (64.7%), and HIV (7.3%) infection were common. Anemia was found in 48.2% of females (<120 g/L hemoglobin) and 40.1% of males (<130 g/L hemoglobin), and 22.3% of females and 7.0% of males had depleted iron stores (serum ferritin <12 microg/L). In multivariate analyses, alcoholic beverage consumption and HIV were positive, whereas soil eating and hookworm infection were negative predictors of serum ferritin. Alcoholic beverage consumption was a positive predictor of hemoglobin, and soil eating, HIV, and hookworm infection were negative predictors. Intakes of meat, fish, and fruit or vegetables were not predictors. Elevated serum ACT was a predictor of both hemoglobin and serum ferritin. Anemia and depleted iron stores were common, whereas iron overload was rare. In conclusion, the associations between alcoholic beverage intake and hemoglobin and iron status suggest that alcoholic beverages may contain micronutrients essential to erythropoiesis. The role of alcoholic beverage intake and other determinants of hemoglobin and iron status in low-income populations needs to be better elucidated.
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PMID:Intake of alcoholic beverages is a predictor of iron status and hemoglobin in adult Tanzanians. 1770 55

An alternative to identify the critical processes necessary to the parasite establishment of the host is to focus on the evolutionary stage responsible for the primary invasion, i.e. the infection structure. The objective of this study was to ultrastructurally characterize Schistosoma mansoni cercariae, using cytochemical techniques. In order to identify basic proteins, techniques such as ethanolic phosphotungstic acid (EPTA) and ammoniacal silver staining were used. Calcium sites location was achieved using the Hepler technique and to evidence anionic groups, we used cationic ferritin particles and enzyme treatment with trypsin Vibrio cholerae, chondroitinase and neuraminidase. The EPTA technique highlighted the presence of basic tegument proteins, nucleus and nucleolus from subtegumental cells, inclusion bodies and preacetabular glands. After using ammoniacal silver, we observed a strong staining in all infective larvae, particularly in the nuclei of muscle cells, circular muscle tissue and preacetabular glands. Calcium site locations were shown to be uniform, thereby limiting the inner spaces of the larvae, especially muscle cells. Samples treated with cationized ferritin particles presented strong staining at the cuticular level. Neuraminidase treatment did not alter the stained shape of such particles on the trematode surface. However, trypsin or chondroitinase treatment resulted in absence of staining on the larval surface. This information on the biochemical composition of the infecting S. mansoni larvae provides data for a better understanding of the biology of this parasite and background on the intriguing parasite-host relationship.
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PMID:Ultrastructural and cytochemical aspects of Schistosoma mansoni cercaria. 1908 Dec 61


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