Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Biomphalaria”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,243 records · Page 69Linked to original sources
PubMed1996

In vitro cultivation of Angiostrongylus costaricensis eggs to first stage larvae in chemically defined medium.

Angiostrongylus costaricensis eggs were successfully cultured to first stage larvae in a chemically defined medium. The most suitable medium for development was Ham's F-12 among 7 chemically defined media and 10 serum supplemented media examined. The addition of serum to Ham's F-12 did not provide any further benefits for egg development. When the eggs were cultured in this medium under 8% CO2 in air, they developed and formed larvae inside the eggs 5 days later. Thereafter, the eggs began to hatch to first stage larvae. Ten days after cultivation, 34% of the eggs had developed to first stage larvae. When these first stage larvae were infected to the snail intermediate host, Biomphalaria glabrata, they developed to third stage larvae.

Angiostrongylus↗
PubMedDate not supplied

The epidemiology of schistosomiasis in Burundi and its consequences for control.

This paper summarizes the results of a series of studies on the epidemiology, morbidity and transmission of Schistosoma mansoni in Burundi, and discusses their consequences for control. The main endemic area is the Imbo lowland, consisting of the Rusizi plain, the urban focus of Bujumbura, and the shores of lake Tanganyika; a small, new focus was discovered in the highlands, around lake Cohoha. Distribution studies on 5-10% population samples with duplicate 28 mg Kato smears in these 4 foci showed prevalences of 33%, 26%, 17%, 19% and mean (positive) egg loads of 110, 105, 92, 144 eggs/g, respectively. The combined population at risk was estimated to be 400,000 people, the total number of detectable cases 90,000. Prevalences and intensities varied greatly at the subregional, local and even sublocal level. The age- and sex-related prevalences and intensities of infection showed typical peaks in children and adolescents, but remained relatively high in adults in many areas; these patterns varied from one area to another and could be related to ecology and water contact. Morbidity studies showed that, in children as well as in adults, schistosomiasis-related morbidity such as (bloody) diarrhoea, hepatomealy and splenomegaly was apparent mainly in areas with prevalences over 30-40%. The intermediate hosts were Biomphalaria pfeifferi (Imbo), B. sudanica (Tanganyika marshes) and B. stanleyi (Cohoha). Population dynamic studies showed strong seasonal variations, the patterns of which were focal and even erratic in space and time. Snail densities and cercarial infection rates (0.85% overall in B. pfeifferi) were low.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMedDate not supplied

Schistosomiasis in Dogon country, Mali: identification and prevalence of the species responsible for infection in the local community.

The prevalence of schistosomiasis amongst the Dogon people in 4 villages and one school of the Bankass district of Mali was determined during 2 surveys in 1992; 1398 urine and 1199 stool samples were examined. The most common schistosome was Schistosoma haematobium, with an overall prevalence of 51.3%; S. mansoni had a prevalence of 12%. No S. intercalatum egg was seen in the stools. Biomphalaria pfeifferi and Bulinus truncatus were found in pools at the base of the Dogon cliffs; Bulinus forskalii was found in smaller numbers in brick pits. Two isolates from urine samples of children were identified as S. haematobium in the laboratory using an alpha-glycerophosphate marker, restriction enzyme analysis of ribosomal deoxyribonucleic acid (rDNA) and random amplification of polymorphic DNA. The isolates did not develop in Bulinus forskalii or B. crystallinus of the B. forskalii group. Some evidence for past hybridization of S. haematobium and S. intercalatum is provided by the enzyme and rDNA results as well as the positive Ziehl-Neelsen staining of polymorphic eggs in urine samples. The findings are discussed in relation to the published observations concerning schistosomiasis in travellers returning from this region of Mali.

Adolescent↗
PubMed1987

Widespread antigenic cross-reactivity between plasma proteins of a gastropod, and its trematode parasite.

Evidence obtained earlier with immunofluorescence and immunoelectron microscopy was interpreted to imply molecular mimicry of the host Biomphalaria glabrata by the parasite Schistosoma mansoni. Using Western Blotting, we find that "mimicry" is due to widespread shared epitopes. Furthermore, at least one individual plasma protein of B. glabrata shares epitopes with the majority of plasma proteins in the mollusc. The widespread antigenic determinants may be carbohydrates. Caution is warranted when antisera, raised in mammals against heterogeneous invertebrate extracts, are used to screen for related antigenic determinants.

Animals↗
PubMedDate not supplied

An invertebrate (Molluscan) plasma protein that binds to vertebrate immunoglobulins and its potential for yielding false-positives in antibody-based detection systems.

Commercial immunoassay kits that incorporate monoclonal antibodies are being used increasingly to screen tissues and plasma from invertebrates for the presence of antigens that are taken to be homologues of the vertebrate immunogen. We report the presence of a protein (BgL115r) in the plasma of Biomphalaria glabrata that binds to immunoglobulins from a variety of vertebrates. BgL115r (ca. 230 kD non-reduced, ca. 115 kD reduced on SDS-PAGE) binds to the F(ab')2-region of murine IgG. Binding could be inhibited with high concentrations of N-acetyl-D-glucosamine (GlcNAc). BgL115r was found to yield false positive signals in an ELISA based assay.

Animals↗
PubMed1991

Isolation and functional characterization of snail hemocyte-modulating polypeptide from primary sporocysts of Schistosoma mansoni.

Infection with larval trematodes has been shown to inhibit several snail-host defences, including hemocyte phagocytosis, cytotoxicity, motility, and adherence. Certain plasma factors which mediate snail defence responses, and which may be produced by host hemocytes, also appear to be altered by these parasites. In this study we present protocols for the isolation of 2 proteins from larval Schistosoma mansoni excretory-secretory (ES) products and detail the effects of these components on Biomphalaria glabrata hemocyte protein synthetic/secretory (S/S) activity. Schistosome ES proteins, separated with a combination of membrane ultrafiltration, size exclusion, and ion exchange chromatography, were tested for their in vitro effect on cultured snail hemocytes, in the presence and absence of homologous plasma. A high-molecular-weight ultrafiltration fraction of parasite ES products (H30), in combination with plasma, was found to differentially affect susceptible (M-line) and resistant (10-R2) snail hemocytes. Secretion of metabolically labeled polypeptides by M-line cells was inhibited significantly while the S/S response of 10-R2 hemocyte polypeptides was not affected. In the absence of homologous plasma, little or no differential affect of ES polypeptides on hemocyte S/S activity was seen. Much of the inhibitory activity of H30 was attributable to a partially purified fraction, Peak I (PkI), of ES products. Evidence suggests that, in its native state, PkI is a high-molecular-weight protein aggregate comprising subunits of approximately 22-24 kDa. Thus, PkI, in the presence of homologous plasma components, is a potential mediator of schistosome-induced suppression of polypeptide synthesis or secretion in hemocytes of susceptible snails. In combination with other parasite and host factors, PkI may be involved in the host-parasite interaction which leads to the state of susceptibility or resistance found in our strains of B. glabrata.

Animals↗
PubMed1988

Schistosomiasis in Ethiopia.

The literature on schistosomiasis in Ethiopia is reviewed with the objective of bringing together in one paper diverse sources which may not be available to those interested in schistosomiasis. Particular attention is given to the influence of altitude and climate, snail ecology and government economic programs on the distribution of schistosomiasis. Out of 365 communities studied between 1961 and 1986 for Schistosomiasis mansoni, cases were reported from 225 (62%), and in 85 (23%) the prevalence ranged from 10 to 92%. Most transmission sites and S. mansoni infections are in agricultural communities along streams between 1300 and 2000 m altitude infested with Biomphalaria pfeifferi, the major snail intermediate host. S. mansoni transmission above 2200 m and below 800 m is precluded in many parts of Ethiopia by low and high water temperatures, respectively. Schistosomiasis haematobium cases have been reported from 30 of the 54 communities studied, 17 of them with infection rates between 14 and 75%. Endemic S. haematobium appears to be confined in its distribution to lowlands below 800 m altitude. The highly focal distribution of S. haematobium transmission is largely due to the nonsusceptibility of most bulinine snails to the Ethiopian strain of the parasite and low water temperatures in the highlands. Water resources development, resettlement programs, refugee migration and other population movements may result in the spread of endemic S. mansoni. Lack of information on snail host/parasite relationships and the ecology of proven and suspected snail hosts does not permit predictions on the spread of endemic S. haematobium. Past and present schistosomiasis control programs in Ethiopia are reviewed and recommendations made for the national control program.

Adolescent↗
PubMed1992

Miracidium of Schistosoma mansoni: a macromolecular glycoconjugate as signal for the behaviour after contact with the snail host.

1. The behaviour of the miracidium of Schistosoma mansoni after contact with agar blocks containing Biomphalaria glabrata snail conditioned water (SCW) or its components, was studied. 2. "Repeated investigation" was the most specific response at contact with the snail host. 3. Fractionation and specific chemical treatment of SCW revealed that this response was stimulated by a lysozyme sensitive glycoconjugate with a mol. wt greater than 300,000. 4. Low molecular weight components of SCW had no stimulatory effect on the miracidia, although MgCl2 offered as pure chemical did so.

Animals↗
PubMed1988

The host-parasite interface in molluscan schistosomiasis: biotin as a probe for sporocyst and hemocyte surface peptides.

Hemocytes of Biomphalaria glabrata mediate the internal defensive response which, in resistant snail strains, kills sporocysts of Schistosoma mansoni. Lacking a gut, the sporocyst has only its tegument to interact with the host milieu (hemolymph). We have, therefore, focused our study on the surface-exposed proteins of hemocytes and sporocyst tegument. Using gentle biotinylation of living systems, labelled proteins were studied after SDS-PAGE electrophoresis and transfer to nitrocellulose. Results validate the utility of surface biotinylation in studies of host and parasite interfaces. A low diversity characterizes hemocyte surfaces and strain-specific differences are not in evidence. Hemocyte surfaces differ distinctly from the plasma in which these cells reside. In contrast, sporocyst surfaces expose a wide variety of peptides. These are remarkably stable even when sporocysts procured in snail plasma-free media are exposed to plasma. Thus, antigenic differences seen previously when Western immunoblotting was used to study sporocyst surfaces appear to be manifestations of minor changes in the exposed peptides or changes not detectable with this methodology. Hemoglobin, acquired by sporocysts from snail plasma, is processed and disappears from the surface during an overnight chase in culture medium.

Animals↗
PubMed1982

Molluscicidal steroid glycoalkaloids possessing stereoisomeric spirosolane structures.

Both the steroidal glycoalkaloid mixture obtained from Solanum mammosum fruits (solasonine 1 and solamargine 2) and the stereoisomeric glycosidic alkaloid tomatine 3 are toxic at 10 and 25 ppm to Lymnaea cubensis and Biomphalaria glabratus, respectively. Their aglycones solasodine 4 and tomatidine 5 obtained by hydrolysis of the glycosides showed no toxicity to either mollusk under the test conditions used. Preliminary structure-activity correlations indicate that the molluscicidal properties depend on the type of aglycones and on the glycoside bond. A common molecular structure in molluscicidal spirosolane and spirostane glycosides is recognized.

Alkaloids↗
PubMed1994

Hirudinicidal activities of some natural molluscicides used in schistosomiasis control.

Experiments were conducted with (molluscicides) aridanin isolated from Tetrapleura tetraptera, aridan, an extract from T. tetraptera, endod, an extract from Phytolacca dodecandra and niclosamide on non-target aquatic organisms such as leech, hydra, tadpoles, anopheline mosquito larvae and brine shrimps and compared with their toxicity to the target snail. Biomphalaria glabrata. Aridanin, aridan, endod, and niclosamide produced rapid knockdown effects on B. glabrata at 0.04, 1.00, 30.00, and 40.00 ppm, respectively. All the molluscicides killed the leech, a pest of animals and man at molluscicidal concentrations. The hydra and tadpoles tested were sensitive to the molluscicides except aridanin but the shrimps and anopheline mosquito larvae were resistant to all the molluscicides.

Animals↗
PubMed1995

Biological screening of traditional medicinal plants from Papua New Guinea.

Based on ethnopharmacological literature, 17 species of medicinal plants used in the traditional medicine in Papua New Guinea were collected. Extracts of different polarities were tested in a preliminary biological screening for their antimicrobial (Escherichia coli, Bacillus subtilis, Micrococcus luteus and Penicillium oxalicum) and molluscicidal activity against Biomphalaria glabrata as well as for their toxicity to brine shrimp. The pretreated plant extracts were also investigated for their ability to inhibit protein kinase C and tyrosine-specific protein kinase of epidermal growth factor receptor. Furthermore, all plants were screened for the presence of alkaloids.

Alkaloids↗
PubMedDate not supplied

Efficient RNAi-based gene family knockdown via set cover optimization.

OBJECTIVE: We address the problem of selecting an efficient set of initiator molecules (siRNAs) for RNA interference (RNAi)-based gene family knockdown experiments. Our goal is to select a minimal set of siRNAs that (a) cover a targeted gene family or a specified subset of it, (b) do not cover any untargeted genes, and (c) are individually highly effective at inducing knockdown. METHODS AND MATERIAL: We give two formalizations of the gene family knockdown problem. First, we show that the problem, minimizing the number of siRNAs required to knock down a family of genes, is NP-Hard via a reduction to the set cover problem. Second, we generalize the basic problem to incorporate additional biological constraints and optimality criteria. To solve the resulting set-cover variants, we modify the classical branch-and-bound algorithm to include some of these biological criteria. We find that in many typical cases these constraints reduce the search space enough that we are able to compute exact minimal siRNA covers within reasonable time. For larger cases, we propose a probabilistic greedy algorithm for finding minimal siRNA covers efficiently. We apply our methods to two different gene families, the FREP genes from Biomphalaria glabrata and the olfactory genes from Caenorhabditis elegans. RESULTS AND CONCLUSION: Our computational results on real biological data show that the probabilistic greedy algorithm produces siRNA covers as good as the branch-and-bound algorithm in most cases. Both algorithms return minimal siRNA covers with high predicted probability that the selected siRNAs will be effective at inducing knockdown. We also examine the role of "off-target" interactions: the constraint of avoiding covering untargeted genes can, in some cases, substantially increase the complexity of the resulting solution. Overall, we find that in many common cases our approach significantly reduces the number of siRNAs required in gene family knockdown experiments, as compared to knocking down genes independently.

Algorithms↗
PubMed2004

Synthesis and evaluation of the molluscicidal activity of the 5,6-dimethyl-dihydro-pyran-2,4-dione and 6-substituted analogous.

Five dihydro-piran-2,4-diones, including 5,6-dimethyl-dihydro-piran-2,4-dione one of the intermediates of the synthesis of caloverticilic acid, were synthesized and submitted to molluscicidal bioassay. The compound's yields varied from moderate to good (42%- 80%) and were achieved through the preparation of the dianion of ethyl acetoacetate, reaction with and aldehyde followed by hydrolysis of the ester (NaOH, H(2)O, 2 h, T.A.) and lactonization in acidic medium (HCl, 0 degrees C). The 5,6-dimethyl-dihydro-piran-2,4-dione and three analogous dihydro-piran-2,4-diones 6-substituted,-phenyl, (4-methoxy-phenyl), and -propenyl, showed significant activities against the Biomphalaria glabrata egg masses, while the analogous 6-(3,4-dimethoxy-phenyl) was inactive as molluscicide. This activity is reported for the first time, extending the range of biological activities of this group.

Animals↗
PubMed2005

Synthesis and evaluation of molluscicidal and larvicidal activities of some novel enaminones derived from 4-hydroxyquinolinones: part IX.

A series of 10 3-(hetarylaminomethylene)quinolinediones, 12 3-(substituted aminopropenoyl)-4-hydroxyquinolinones, and 10 3-(substituted aminomethylene-5-oxo-pyrazolinyl)-4-hydroxyquinolinones were synthesized as novel enaminones derived from 3-(un)substituted 4-hydroxyquinolin-2(1H)-ones in 72-94% yields and assayed for their molluscicidal activities against Biomphalaria alexandrina and Lymnaea natalensis snails. Some of the tested enaminones presented high molluscicidal activities (LC(50)20ppm). The new compounds showed more potency against hatchability of B. alexandrina egg masses, the infection rate and prepatent period of the snails. In addition, these derivatives revealed potential larvicidal effects (100% mortality) on both miracidia and cercariae of Schistosoma mansoni at reduced exposure time. The selected active derivatives were examined against Daphnia magna and their nontoxic effect at all sublethal, lethal, and higher concentrations suggests that these compounds can play an important role as molluscicides and larvicides with environmental safe properties.

Animals↗
PubMed2006

Novel bis(1-acyl-2-pyrazolines) of potential anti-inflammatory and molluscicidal properties.

A variety of bis[3-aryl-4,5-dihydro-1H-pyrazol-1-carboxaldehydes] 4a-h were obtained via reaction of bis[1-aryl-2-propen-1-ones] 3a-h with hydrazine hydrate in refluxing formic acid. In addition, the corresponding bis[1-acetyl-3-aryl-4,5-dihydro-1H-pyrazoles] 4i-m were formed through conducting the reaction of 3 with hydrazine hydrate in refluxing acetic acid. The starting bis(2-propen-1-ones) 3a-h were prepared stereoselectively as E,E'-geometric isomer via condensation of bisbenzaldehydes 1a,b with (un)substituted acetophenones 2 in ethanolic KOH solution. Anti-inflammatory as well as ulcerogenic activities of the prepared pyrazolines were evaluated in vivo and compared with that of a standard drug (indomethacin). Many of the tested compounds show remarkable anti-inflammatory properties with an ulcerogenic liability (especially 4f, g, j, and k) lower than that of the standard used drug. Compound 4f was established to be the best effectively prepared anti-inflammatory active pyrazoline derivative and safer than indomethacin with respect to its ulcerogenic liability. Molluscicidal activity of the prepared compounds against Biomphalaria alexandrina snails (the intermediate host of Schistosoma mansoni) was screened. Where, some of the prepared compounds show considerable activities.

Animals↗
PubMed2006

Specific inhibitors of mitogen-activated protein kinase and PI3-K pathways impair immune responses by hemocytes of trematode intermediate host snails.

To characterize molecular mechanisms regulating snail cellular immune responses, the contributions of mitogen-activated protein kinases (MAPKs) and phosphatidylinositol 3-kinase (PI3-K) were examined in hemocytes of the trematode intermediate host snails Biomphalaria glabrata and Lymnaea stagnalis. Simultaneous measurement of phagocytosis/encapsulation and H2O2 production by hemocytes in the presence or absence of specific signal transduction inhibitors was used to assess the role of extracellular-signal regulated kinases 1 and 2 (ERK1/2), p38, JNK and PI3-K. Hemocyte spreading was significantly reduced in a dose-dependent manner by the ERK inhibitor, PD098059, and by wortmannin, a potent PI3-K inhibitor. The JNK inhibitor, SP600125, and the p38 kinase inhibitor, SB203580, had no effect on hemocyte spreading. Sheep red blood cell phagocytosis was significantly impaired by PD098059, SP600125, and SB203580. Hydrogen peroxide production during phagocytosis was severely inhibited by PD098059. Additionally, PD098059, but not the other inhibitors, significantly impaired the cellular encapsulation of trematode larvae and H2O2 production during encapsulation. These results suggest that MAPK and PI3-K signal transduction pathways play a pivotal role in the immune responses of snail hemocytes. PI3-K and ERK appear to strongly regulate cell motility. ERK, JNK and p38 contribute to phagocytosis-mediated signal transduction. ERK also play a major role in oxidative burst activation and the encapsulation of trematode larvae by snail hemocytes.

Animals↗
PubMed2026

Snail immunity to schistosomes: insights from omics studies.

Schistosomiasis is a serious public health concern, with transmission facilitated by a small number of freshwater snail intermediate host species. Infection outcomes vary greatly across the primary vector genera, Biomphalaria (for Schistosoma mansoni), Bulinus (for S. haematobium), and Oncomelania (for S. japonicum), even within species, ranging from full resistance to high compatibility. Omics methods have altered this field by correlating host genotype, baseline immunological status, and time-resolved responses to whether invading miracidia are eliminated or develop sporocysts. Evidence from genomes, transcriptomics, proteomics, and epigenomics suggests that resistance is frequently primed prior to exposure. However, the clearest divergence between resistant and susceptible trajectories occurs during a small early window (<12-48&#x202f;h) after penetration. During this time, recognition, hemocyte recruitment, and soluble effector deployment either come together quickly or are delayed and guided by parasite-derived modulators. Established infections cause the host to adapt to chronic conditions through immune regulation, metabolic reprogramming, tissue and neuroendocrine remodeling, microbiome modification, and parasite castration. Comparative genomics reveals that each vector genus has evolved its own immunogenomic profile, which includes lineage-specific expansions of recognition and effector gene families. Together, these findings can help with field surveillance and intervention by providing molecular compatibility markers, functional tools for testing candidate genes, and tactics that target parasite-derived immune modulators. Integrated multi-omics approaches are a top priority, yet they are still limited in snail vectors compared to other disease vector systems.

Animals↗