| resistance to cadmium and parasite infection are inversely related in two strains of a freshwater gastropod. | phenotypes that are either resistant or susceptible to infection by the trematode parasite schistosoma mansoni exist in the tropical freshwater snail biomphalaria glabrata. we tested the hypothesis that a cost of parasite resistance in b. glabrata is greater sensitivity to cadmium toxicity, using parasite-resistant and parasite-susceptible strains exposed to cadmium in the laboratory. survival analysis showed that time to death for cadmium was significantly shorter in eggs, juveniles, and adults ... | 2002 | 12109739 |
| the symbiont capsaspora owczarzaki, nov. gen. nov. sp., isolated from three strains of the pulmonate snail biomphalaria glabrata is related to members of the mesomycetozoea. | while investigating the resistance of some strains of biomphalaria glabrata to infection with schistosoma mansoni, a unicellular eukaryotic symbiont was noted in the snail haemolymph. it was similar in appearance to nuclearia sp. reported from b. glabrata. sequences comprising the 18s, its1, 5.8s, its2 and the beginning of the 28s rdna gene regions were obtained from symbionts isolated from three strains of b. glabrata, and compared with the same sequences obtained from a culture of nuclearia sp ... | 2002 | 12117501 |
| in vitro cultivation of cells from ovotestis tissue of pigmented biomphalaria glabrata. | cells derived from ovotestis tissue of pigmented biomphalaria glabrata, puerto rican strain were cultured in double diluted git medium supplemented with modification of amino acids components of pigmented b. glabrata, ovotestis and mid-gut region and 3% inactivated fetal calf serum. as a result, two types of cells, epithelial and fibroblastic like cells increased in number during the cultivation. it seem that the medium used in this study is a suitable medium for cultivation of cells from ovotes ... | 2002 | 12125924 |
| molluscicidal activity against biomphalaria glabrata of brazilian cerrado medicinal plants. | alcoholic extracts of six brazilian cerrado medicinal plants were evaluated for their molluscicidal activity against biomphalaria glabrata, intermediate host of schistosomiasis. stryphnodendron polyphyllum bark extract, rich in condensed tannins, was the most promising as molluscicide. | 2002 | 12165343 |
| molluscicidal and piscicidal activities of venezuelan chrysobalanaceae plants. | extracts of increasing polarity of 6 venezuelan plants belonging to the chrysobalanaceae family were tested for possible letal toxicity against biomphalaria glabrata say, a snail intermediate hosts of schistosoma mansoni sambon. the piscicidal toxicity of the active extracts was also evaluated with the aim of findings compounds without toxicity in nontarget organisms, principally fishes and humans. | 2000 | 10665990 |
| further characterization of passively transferred resistance to schistosoma mansoni in the snail intermediate host biomphalaria glabrata. | a heat-labile plasma factor from genetically resistant 10-r2 biomphalaria glabrata snails confers passively transferred resistance (ptr) to schistosoma mansoni when injected into susceptible snails within 24-hr of exposure to miracidia. however, no additional details on ptr have emerged since the initial 1984 report, nor has the plasma resistance factor been characterized. in the present study, new information is provided on the occurrence of resistance factor in plasma of additional types of sn ... | 2001 | 11780822 |
| evolutionary history and phylogeography of the schistosome-vector freshwater snail biomphalaria glabrata based on nuclear and mitochondrial dna sequences. | the phylogeography of the freshwater snail biomphalaria glabrata remains poorly known, although this species is the major vector of schistosomiasis in the new world. it was here investigated in south america and the lesser antilles, based on partial mitochondrial large ribosomal subunit (16s rdna) and nuclear internal transcribed spacer-2 (its-2) gene sequences. sampling included 17 populations from a large part of the current geographic range of the species (brazil, venezuela and lesser antille ... | 2002 | 12242642 |
| the influence of hydrocortisone on cellular defence mechanisms of biomphalaria glabrata. | since the internal defense system of mollusks consists of cellular and humoral mechanisms, we examined the role of hydrocortisone in mollusks defense cells and the influence of this steroid on the development of schistosoma mansoni in its intermediary host. hydrocortisone had an immunosuppressive action in biomphalaria glabrata, as reflected in the reduced number of defense cells and the altered cell physiology. histopathological analysis showed that hydrocortisone facilitated the intramolluscan ... | 2002 | 12386715 |
| parasite-responsive igsf members in the snail biomphalaria glabrata: characterization of novel genes with tandemly arranged igsf domains and a fibrinogen domain. | two novel genes of the immunoglobulin superfamily (igsf), frep3 and frep7, are reported from the snail biomphalaria glabrata, a prominent intermediate host of the human parasite schistosoma mansoni. they resemble other b. glabrata genes that encode fibrinogen-related proteins (freps), but differ in that they encode proteins with two tandemly arranged igsf domains followed by a c-terminal fibrinogen domain. freps are hemolymph proteins that increase in abundance following exposure to a digenetic ... | 2001 | 11797103 |
| [abundance and infection of biomphalaria glabrata with schistosoma glabrata in the state of rio de janeiro, brazil]. | to investigate the spatial distribution, abundance and natural schistosomiasis infection levels in the snail biomphalaria glabrata, the intermediate host of schistosoma mansoni in an area of the state of rio de janeiro, brazil. | 2001 | 11799465 |
| mixed strain schistosome infections of snails and the evolution of parasite virulence. | mathematical models often propose that within-host competition between parasites can be a major factor in the evolution of increased parasite virulence. kin selection predicts that as the coefficient of relatedness between infecting parasites decreases, the benefits of competition to individual genotypes increases. thus where parasites can adjust their behaviour in response to current conditions, higher virulence is predicted in multiple genotype infections. there is limited experimental data, h ... | 2002 | 11811801 |
| nitric oxide limits parasite development in vectors and in invertebrate intermediate hosts. | nitric oxide (no) possesses antiparasitic effects on both protozoa and metazoa in vertebrate definitive and intermediate hosts. inducible no limits parasite development also in rhodnius prolixus and anopheles stephensi, the natural vectors of human trypanosomiasis and malaria respectively, and in the snail biomphalaria glabrata, a natural invertebrate intermediate host of human schistosomiasis. therefore, no limits trypanosoma, plasmodium, and schistosoma development at all stages of the parasit ... | 2002 | 12049194 |
| toxicity of lapachol and isolapachol and their potassium salts against biomphalaria glabrata, schistosoma mansoni cercariae, artemia salina and tilapia nilotica. | the toxicity of soluble derivatives (potassium salt) of lapachol and isolapachol in different stages of the life cycle of schistosoma mansoni is evaluated. the potassium salts of isolapachol and lapachol showed significant molluscicidal activity against the adult snail (lc90<7 ppm) and snail egg masses (lc90<3 ppm). cercaricidal assays revealed strong activities for both compounds. lethality assays against brine shrimp eggs (artemia salina leach) indicated very high toxicity for the potassium sa ... | 2002 | 12062792 |
| parasite-susceptibility phenotypes of f1 biomphalaria glabrataprogeny derived from interbreeding schistosoma mansoni-resistant and -susceptible snails. | in an effort to investigate the 'flow' of parasite-resistance genes through laboratory snail populations, we determined the susceptibility of progeny snails from freely interbreeding parasite-susceptible and parasite-resistant parents. five parental populations of biomphalaria glabrata were used to generate the progeny snails. three of them contained different proportions of schistosoma mansoni-susceptible albino snails (nmri stock) and s. mansoni-resistant pigmented snails (bs-90), while single ... | 2003 | 12489007 |
| gene expression changes in schistosoma mansoni sporocysts induced by biomphalaria glabrata embryonic cells. | biomphalaria glabrataembryonic (bge) cells have been shown to provide favourable environmental conditions for the development of schistosoma mansoni sporocysts. we investigated the effect of bge excretory-secretory products on metabolic activity and gene transcription in s. mansoni mother sporocysts. using the differential-display technique, we identified several sporocyst transcripts regulated by exposure to bge soluble components. research in databases indicated that six of the eight different ... | 2003 | 12489010 |
| production of reactive oxygen species by hemocytes of biomphalaria glabrata: carbohydrate-specific stimulation. | recognition of specific carbohydrate structures, which occur commonly on the surfaces of invading pathogens, is thought to elicit internal defense mechanisms in invertebrates. to investigate the nature of carbohydrates that evoke a defensive response in hemocytes of the gastropod biomphalaria glabrata, we tested eight different carbohydrates, conjugated to bovine serum albumin (bsa), for generation of reactive oxygen species (ros). six of the carbohydrate moieties tested are thought to be presen ... | 2000 | 10831788 |
| carbohydrate inhibition of biomphalaria glabrata embryonic (bge) cell adhesion to primary sporocysts of schistosoma mansoni. | due to shared characteristics with snail haemocytes, the biomphalaria glabrata embryonic (bge) cell line has been used as a model in vitro system for the study of snail-trematode interactions. in this study, bge cells were used to characterize the adherence of snail host cells to schistosome primary sporocysts, and to test the effect of carbohydrates as inhibitors of this behaviour. bge cells bound to the surface of >90% of schistosoma mansoni sporocysts and, based on a semi-quantitative cell ad ... | 2002 | 12553570 |
| serine protease and phenoloxidase activities in hemocytes of biomphalaria glabrata snails with varying susceptibility to infection with the parasite schistosoma mansoni. | the snail biomphalaria glabrata possesses hemocytes, which are supposed to interact with the larval stages of the human parasite schistosoma mansoni. we describe trypsin-like serine protease(s) and phenoloxidase activities in lysates from these hemocytes. both enzymes have activity optima around ph 9.5. the serine protease was inhibited by edta, pmsf, antipain and aprotinin, and the phenoloxidase activity by diethydithiocarbamate. by comparison, the serine protease activity in secretions of s. m ... | 2002 | 12107469 |
| schistosome invasion of human skin and degradation of dermal elastin are mediated by a single serine protease. | aquatic larvae (cercariae) of the trematode parasite schistosoma mansoni rapidly penetrate human skin by degrading host proteins including elastin. two serine proteases, one chymotrypsin-like and the second trypsin-like, have been proposed to be involved. to evaluate the relative roles of these two proteases in larval invasion, both were purified, identified by sequence, and then biochemically characterized. the trypsin-like activity was resolved into two distinct serine proteases 76% similar in ... | 2000 | 10993899 |
| molluscicidal activity of 2-hydroxy-3-alkyl-1,4-naphthoquinones and derivatives. | in the search for new molluscicidal agents we tested the activity of lapachol and other 2-hydroxy-3-alkylnaphthoquinones possessing nitrogenated alkyl chains, against the snail biomphalaria glabrata. lapachol, isolapachol and nor-lapachol showed strong molluscicidal activity against the adult snail (ld(90)<10 ppm) and significant toxicity against snail egg masses (ld(90)<0.2 ppm). as lapachol is easily extracted, and the derivatives can be synthesised without any difficulty, large-scale synthesi ... | 2000 | 11027788 |
| extra-cellular matrix changes in schistosoma mansoni-infected biomphalaria glabrata. | reactivity of snails against parasites exhibits a primitive focal reaction, with encapsulation, phagocytosis and destruction of parasite larvae by macrophage-like cells - the hemocytes. this reaction mimics granulomatous inflammation seen in higher animals. however, different from the latter, little is known about the participation of extra-cellular matrix in such snail defense reactions. normal and schistosoma mansoni-infected biomphalaria glabrata of different strains were submitted to cytolog ... | 2003 | 12700871 |
| [schistosomiasis in hyperendemic area of taquarendi: i- schistosoma mansoni infection and severe clinical forms]. | the study was carried out in taquarendi (bahia), a caatinga zone with a small irrigated strip of land, where biomphalaria glabrata snails are found. from the 1,532 inhabitants, 1,105 (72.1%) were submitted to clinical examination and 1058 out of them (95.7%) made stool examinations. prevalence of schistosomiasis was 73.1% and 16.2% of these patients eliminated more than 1,000 eggs per gram of stool. by clinical examination, the size and the consistency of the left liver lobe were increased in 54 ... | 2003 | 12806456 |
| comparative studies for development of schistosoma mansoni sporocysts in puerto rican and brazilian biomphalaria glabrata. | the development of sporocysts of schistosoma mansoni was monitored in pigmented and albino biomphalaria glabrata from puerto rico and brazil. the snails were exposed individually to 20 miracidia, and sporocysts were allowed to develop for 3 to 12 weeks. most of the immature sporocysts were found in the seminal receptacle sac and vas deferens during development. in contrast, mature daughter sporocysts were detected everywhere except in the foot at 12 weeks after exposure to the miracidia. it was ... | 2000 | 11043519 |
| altered behavior of the snail biomphalaria glabrata as a result of infection with schistosoma mansoni. | in this comparative behavioral study, the effect of infection with schistosoma mansoni on its snail intermediate host biomphalaria glabrata was investigated. three groups of snails were compared for their activity: (1) uninfected, (2) infected with male parasites, and (3) infected with female parasites. in solitary movement trials, uninfected snails traveled greater distances at faster rates, explored more surface area, and had shorter rest periods than snails infected with either male or female ... | 2003 | 12880237 |
| mechanisms underlying digenean-snail specificity: role of miracidial attachment and host plasma factors. | digenetic trematodes usually show a high degree of specificity for their molluscan intermediate hosts. a panel of 4 digenean species (echinostoma paraensei, e. trivolvis, schistosoma mansoni, and schistosomatium douthitti) and 5 snail species (biomphalaria glabrata, helisoma trivolvis, lymnaea stagnalis, stagnicola elodes, and helix aspersa representing 3 gastropod families) was used to assess the relative contributions of miracidial behavior, host plasma osmolality, and host plasma factors in d ... | 2000 | 11128473 |
| apparent competition through facilitation between melanoides tuberculata and biomphalaria glabrata and the control of schistosomiasis. | interactions between two species that result in reduced growth rates for both and extinction of one of the species are generally considered cases of asymmetric interspecific competition. exploitative or interference competition is the usual mechanism invoked. here we describe another mechanism producing the same result, named apparent competition through facilitation (acf), observed between melanoides tuberculata and biomphalaria glabrata populations. the superior competitor actually gives some ... | 2003 | 12886429 |
| biodegradability of the molluscicidal saponins of phytolacca dodecandra. | the biodegradability of water-extracted saponins of berries from the endod plant, phytolacca dodecandra l'herit, was evaluated under oecd standardized conditions. persistence of the saponins was evaluated by determination of saponin concentrations in water over a 30-day period, using a quantitative hplc method and a semiquantitative hemolytic assay, which is considered a potential field method. the two methods were compared. bioassays were simultaneously conducted using biomphalaria glabrata fre ... | 2000 | 11162718 |
| parasite infection, host resistance and mate choice: battle of the genders in a simultaneous hermaphrodite. | parasites have been proposed to be fundamental in the evolution of mate choice because differential mating on the basis of heritable disease resistance is expected to lead to progeny with a better genome-environment match than random mating. however, direct empirical data in support of this hypothesis are often lacking, and the relative influences of current and potential infection status (i.e. resistance genotype), and of mate choice versus mate conflict, remain largely unknown. we demonstrate ... | 2003 | 12965013 |
| transplantation of in vitro-generated schistosoma mansoni mother sporocysts into biomphalaria glabrata. | specific studies on schistosome gene functions require both access to the parasite stages, preferably the larvae, and to complete the life cycle. in the present study, we investigated whether short-term in vitro cultivation of sporocysts and surgical transplantation into snails could be combined to produce cercariae. miracidia were maintained in vitro in the presence of biomphalaria glabrata embryonic (bge) cells or, alternatively, in bge-cell-conditioned medium. the transformation of miracidia ... | 2003 | 14551763 |
| angiostrongylus vasorum (baillet, 1866) kamensky, 1905: emergence of third-stage larvae from infected biomphalaria glabrata snails. | biomphalaria glabrata snails were experimentally infected with angiostrongylus vasorum first-stage larvae and divided into four groups of 30 snails. to assess the shedding of third-stage larvae (l3), the snails were maintained under different stimuli: group 1 60 w light bulb for 24 h, group 2 37 degrees c water bath for 24 h, group 3 room temperature (23-25 degrees c) for 24 h, group 4 room temperature (23-25 degrees c) for up to 15 days. after 24 h, a total of 512 a. vasorum l3, alive and activ ... | 2003 | 14557873 |
| acute schistosomiasis outbreak in the metropolitan area of belo horizonte, minas gerais: alert about the risk of unnoticed transmission increased by growing rural tourism. | the present article describes the occurrence of 17 cases of acute schistosomiasis in the metropolitan area of belo horizonte, state of minas gerais, brazil. all individuals affected took a bath in a swimming pool of a holiday resort that was provided with water from a nearby brook. the apparently clean water and the absence of snails in the pool gave the wrong impression that there was no risk for infection. during a malacological survey at the site snails of the species biomphalaria glabrata we ... | 2003 | 14595449 |
| effects of the serotonin receptor ligand methiothepin on reproductive behavior of the freshwater snail biomphalaria glabrata: reduction of egg laying and induction of penile erection. | the biogenic monoamine serotonin (5-ht) has been reported to enhance egg laying in the freshwater gastropod biomphalaria glabrata, an intermediate host for human blood flukes. methiothepin, a vertebrate 5-ht(1/2) receptor ligand which binds with high affinity to a 5-ht receptor (5-htlym) in lymnaea stagnalis was tested for its ability to block egg laying in b. glabrata as a possible target for snail control. a single 30-min application of methiothepin (1 microm) was sufficient to prevent egg lay ... | 2001 | 11170017 |
| genome size estimates for two important freshwater molluscs, the zebra mussel (dreissena polymorpha) and the schistosomiasis vector snail (biomphalaria glabrata). | the haploid genome sizes of two important molluscs were assessed by feulgen image analysis densitometry. the genome size of the zebra mussel (dreissena polymorpha), a prolific invader of north american lakes, was estimated to be 1c = 1.70 +/- 0.03 pg, and that of the freshwater snail biomphalaria glabrata, the predominant intermediate vector of the human parasite schistosoma mansoni, was estimated at 0.95 +/- 0.01 pg. these estimates will be important in future efforts in molluscan genomics, whi ... | 2003 | 14608401 |
| the molluscicidal activity of the latex of euphorbia splendens var. hislopii on melanoides tuberculata (thiaridae), a snail associated with habitats of biomphalaria glabrata (planorbidae). | the use of the latex of euphorbia splendens var. hislopii was considered as an effective control method for biomphalaria glabrata in sumidouro, rio de janeiro. however, the appearance and expansion of the snail melanoides tuberculata since august 1997, with the concomitant reduction of the population of b. glabrata suggest that competitive exclusion might be taking place. depending on the susceptibility of the thiarid to the e. splendens toxin, the natural control that is occurring could be inte ... | 2001 | 11285483 |
| male-female larval interactions in schistosoma mansoni-infected biomphalaria glabrata. | this paper investigates schistosoma mansoni male-female larval interactions in simultaneous bi-miracidial biomphalaria glabrata infections. larval interactions were analysed at four levels of infection: (i), miracidial infectivity, estimated by the prevalence of mollusc infection; (ii), mollusc pathology, measured by the mollusc growth and survival; (iii), dynamics of the cercarial sex ratio; and (iv), cercarial infectivity, measured as the success of development into adulthood. our results show ... | 2001 | 11306113 |
| killing of schistosoma mansoni sporocysts by hemocytes from resistant biomphalaria glabrata: role of reactive oxygen species. | the fate of schistosoma mansoni (trematoda) sporocysts in its molluscan host biomphalaria glabrata (gastropoda) is determined by circulating phagocytes (hemocytes). when the parasite invades a resistant snail, it is attacked and destroyed by hemocytes, whereas in a susceptible host it remains unaffected. we used 3 inbred strains of b. glabrata: 13-16-r1 and 10-r2, which are resistant to the pr-1 strain of s. mansoni, and m-line oregon (mo), which is susceptible to pr-1. in an in vitro killing as ... | 2001 | 11318558 |
| miracidia of an egyptian strain of schistosoma mansoni differentiate between sympatric snail species. | the host-finding behavior of miracidia of 2 strains of schistosoma mansoni from egypt and brazil was studied by recording their responses to snail-conditioned water (scw) from the egyptian sympatric snails, biomphalaria alexandrina, physa acuta, lymnaea cailliudi, and balinus truncatus, as well as from biomphalaria arabica and biomphalaria glabrata. miracidia of the egyptian strain significantly preferred scw from their compatible hosts b. alexandrina and b. arabica and showed no or a weak respo ... | 2003 | 14740921 |
| ultrastructural study of the in vitro interaction between biomphalaria glabrata hemocytes and schistosoma mansoni miracidia. | biomphalaria glabrata and schistosoma mansoni relationship was studied by light microscopy (lm) and freeze-fracture replica technique (ffr). we observed very thin cytoplasmic extensions of hemocytes in the lm, which then surround immobilize the miracidia. ffr images showed that the contact site between hemocytes cytoplasmic extensions and the external tegumentary coat involved only superficial layers of miracidia. numerous vacuoles and filopodia were observed in the hemocyte cytoplasm, the latte ... | 2004 | 14762516 |
| schistosoma mansoni miracidia transformed by particle bombardment infect biomphalaria glabrata snails and develop into transgenic sporocysts. | miracidia (and adults) of schistosoma mansoni which had been subjected to particle bombardment with a plasmid dna encoding enhanced green fluorescent protein (egfp) under control of the s. mansoni heat shock protein 70 (hsp70) promoter and termination elements were shown to express the reporter gene. bombarded miracidia were able to penetrate and establish in biomphalaria glabrata the intermediate host snail. gold particles could be detected in the germ balls of parasites in paraffin-sections of ... | 2003 | 14969695 |
| 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-dimet ... | 2004 | 14980598 |
| mitotic responses to extracts of miracidia and cercariae of schistosoma mansoni in the amebocyte-producing organ of the snail intermediate host biomphalaria glabrata. | suspensions of miracidia and cercariae of schistosoma mansoni were subjected to repeated freeze-thaw cycles and then injected into resistant salvador strain biomphalaria glabrata snails. a pronounced increase in the number of mitotic figures, relative to uninjected, sham-injected, or diluent (water)-injected controls, was observed in the amebocyte-producing organ (apo) at 3 days postinjection (pi). after centrifugation of miracidia freeze-thaw extract (fte), the resulting supernatant (fts) and p ... | 2004 | 15040672 |
| effect of miracidial dose on adoptively transferred resistance to schistosoma mansoni in the snail intermediate host, biomphalaria glabrata. | adoptively transferred resistance to schistosoma mansoni in the snail intermediate host biomphalaria glabrata was measured as a function of miracidial challenge dose. schistosome-susceptible snails implanted with the amebocyte-producing organ (apo) from resistant donors showed 29 and 39% prevalences of infection after challenge with 5 and 10 miracidia, respectively, but 68-83% prevalences when exposed to 25-200 miracidia. prevalences in control (untampered) susceptible snails ranged from 97 to 1 ... | 2001 | 11318589 |
| schistosoma mansoni: resistant specific infection-induced gene expression in biomphalaria glabrata identified by fluorescent-based differential display. | the freshwater tropical snail biomphalaria glabrata is an intermediate host for schistosoma mansoni, the causative agent of human intestinal schistosomiasis, and strains differ in their susceptibility to parasite infection. changes in gene expression in response to parasite infection have been simultaneously examined in a susceptible strain (nhm1742) and a resistant strain (nhm1981) using a newly developed fluorescent-based differential display method. such rna profiling techniques allow the exa ... | 2004 | 15208043 |
| freshwater snails and schistosomiasis mansoni in the state of rio de janeiro, brazil: iv - sul fluminense mesoregion. | in this paper, the forth of a series dealing with the survey of freshwater gastropods of the state of rio de janeiro, the results of collections carried out in the sul fluminense mesoregion from 2000 to 2002 are presented and revealed the occurrence of 18 species: antillorbis nordestensis; biomphalaria glabrata; biomphalaria peregrina; biomphalaria straminea; biomphalaria tenagophila; drepanotrema anatinum; drepanotrema cimex; drepanotrema lucidum; ferrissia sp.; gundlachia ticaga; gundlachia sp ... | 2004 | 15273799 |
| differential gene expression and the effects of biomphalaria glabrata embryonic (bge) cell factors during larval schistosoma mansoni development. | | 2004 | 15287597 |
| behavior of schistosoma mansoni-induced histopathological lesions in biomphalaria glabrata submitted to ionizing radiation. | present report demonstrates that repeated radiation of schistosoma mansoni-infected biomphalaria glabrata, totaling 15,000 rads, caused a sudden, albeit transient, suppression of cercarial shedding. initially, sporocysts practically disappeared from the snail tissues. the more resistant developing cercariae presented nuclear clumping and vacuolation, before undergoing lysis. no host tissue reaction was evident at any time. thirty-four days after the last irradiation, the snails resumed cercarial ... | 2004 | 15330060 |
| characterization of an insulin receptor-related receptor in biomphalaria glabrata embryonic cells. | tyrosine kinase receptors play a key role in the communication of cells with their environment. growth hormone receptors, such as insulin receptors, are involved in the regulation of cell growth, differentiation and metabolism in multicellular organisms. insulin-related peptides and members of the insulin receptor subfamily have been described in a wide variety of invertebrates, including freshwater molluscs. in this paper, we describe the metabolic effect of insulin on a mollusc cell line (bge) ... | 2001 | 11342169 |
| differential display analysis of hemocytes from schistosome-resistant and schistosome-susceptible intermediate hosts. | hemocytes from schistosome-resistant and schistosome-susceptible biomphalaria glabrata differ fundamentally in their behavior towards an invading parasite. when the schistosome infects a resistant snail host it is quickly surrounded by hemocytes, encapsulated and destroyed. hemocytes from susceptible hosts fail to kill the parasite. to detect the differences between these two host phenotypes, we used differential-display reverse-transcription pcr (ddrt-pcr), based on rna extracted from isolated ... | 2001 | 11411951 |
| description of the adult worms of a new brazilian isolate of echinostoma paraensei (platyhelminthes:digenea) from its natural vertebrate host nectomys squamipes by light and scanning electron microscopy and molecular analysis. | echinostoma paraensei lie and basch, 1967 (echinostomatidae:platyhelminthes), a 37 collar spine echinostome of the "revolutum group", has been used extensively as a model organism to study the interactions of digenetic trematodes with both their snail and vertebrate hosts. this worm was first isolated from the snail biomphalaria glabrata from belo horizonte (bh isolate), minas gerais state, brazil, by lie and basch [j parasitol (1967) 53:1192-1199]. the natural definitive host for the bh isolate ... | 2001 | 11688891 |
| long-term controlled field experiment on the competition between two species of biomphalaria (mollusca, basommatophora), the snail vectors of schistosoma mansoni in northeastern brazil. | a long-term controlled field experiment on the interactions of the populations of biomphalaria glabrata (target population) and b. straminea (competitor) was carried out in the county of alhandra, state of paraíba, brazil, during the period 1980 through 1989. results obtained in the current paper show that the snail b. straminea has strong competitive advantages over b. glabrata. in six out of nine streams the native population of b. glabrata were totally excluded and replaced by b. straminea. t ... | 2004 | 15448838 |
| genetics of biomphalaria glabrata and its effect on the outcome of schistosoma mansoni infection. | the genetics of the snail biomphalaria glabrata is better characterized than that of any other intermediate host of schistosomes of humans. using techniques of selective breeding, several snail stocks have been developed that consistently display resistant or susceptible phenotypes. investigators using these stocks have learned that several snail and parasite genes influence the course of parasite development. here, charles richards, matty knight and fred lewis discuss the importance of the snai ... | 1992 | 15463608 |
| representation of an immune responsive gene family encoding fibrinogen-related proteins in the freshwater mollusc biomphalaria glabrata, an intermediate host for schistosoma mansoni. | fibrinogen-related proteins (freps) are found in the hemolymph of the freshwater snail biomphalaria glabrata, are up-regulated following exposure to digenetic trematode parasites, and bind to trematode larval surfaces, suggestive of a role in internal defense. southern blot and degenerate-polymerase chain reaction (pcr) analyses were undertaken to better understand the diversity of the frep-encoding gene family. probes corresponding to the n-terminal igsf domains of specific frep gene subfamilie ... | 2004 | 15474308 |
| the initial epidemiological studies in the low endemicity schistosomiasis area in esteio, rio grande do sul, the southernmost brazilian state, 1997 to 2000. | nor biomphalaria glabrata neither schistosoma mansoni were reported from rio grande do sul, the southernmost brazilian state before 1997. their detection next to the sinos river, esteio, confirmed predictions of schistosomiasis expansion to the south. parasitological examinations both in snails and fecal samples from the human population were performed from 1997 to 2000. the last 3 out of 5 surveys were performed after a preliminar serological screening procedure in a risk group identified at a ... | 2004 | 15486639 |
| the relationship between schistosoma mansoni and biomphalaria glabrata: genetic and molecular approaches. | biomphalaria glabrata is a major intermediate host for the helminth parasite schistosoma mansoni. beginning in the mid-20th century, studies were carried out with this snail species to identify the immunological and genetic components that might be involved in controlling schistosome development. a number of genetically well-defined snail stocks were derived as a direct result of these studies and have since played major roles in helping investigators to identify important cellular and humoral c ... | 2001 | 11769281 |
| molecular approaches in the study of biomphalaria glabrata--schistosoma mansoni interactions: linkage analysis and gene expression profiling. | gene mapping and the generation of linkage groups are fundamental to an understanding of the organization and relationships of genes and marker sequences, providing a framework with which to investigate their association with traits of interest. the abundance of techniques available for generating polymorphic molecular markers, and recent advances in high throughput screening, have allowed the extension of map analysis to the tropical freshwater snail biomphalaria glabrata, an important intermed ... | 2001 | 11769282 |
| molecular characterization of brevibacillus laterosporus and its potential use in biological control. | thirty-three strains of brevibacillus laterosporus, including three novel strains isolated from brazilian soil samples, were examined for genetic variability by the use of different pcr-based methods. molecular markers that could characterize bacterial strains with regards to their pathogenic potential were investigated. in addition, toxicity was assessed by the use of insects belonging to the orders lepidoptera and coleoptera and the mollusk biomphalaria glabrata. among the targets tested, biom ... | 2004 | 15528531 |
| molecular ecology of schistosoma mansoni transmission inferred from the genetic composition of larval and adult infrapopulations within intermediate and definitive hosts. | we investigated the genotypic composition of the digenetic parasite schistosoma mansoni for its adult stages within the definitive host (the wild rat, rattus rattus) and for the larval stages within the intermediate host (the snail, biomphalaria glabrata) both collected at the same transmission site. our analyses are based upon the recognition and distribution of 200 different multilocus genotypes generated by rapd markers. while intramolluscan larval infrapopulations are characterized by a low ... | 2004 | 15552402 |
| the mitochondrial genome of biomphalaria glabrata (gastropoda: basommatophora), intermediate host of schistosoma mansoni. | the complete mitochondrial (mt) genome of the gastropod biomphalaria glabrata, a major intermediate host for the human parasite schistosoma mansoni, was sequenced. the circular genome, the first determined from a basommatophoran snail, is at rich (74.6%) and the smallest mt genome (13,670 nucleotides [nt]) characterized from mollusks to date. sequences from 2 b. glabrata strains, m-line and 1742, differed by only 18 nt. phylogenetic analysis of 16s and nd1 sequences confirmed the brazilian ances ... | 2004 | 15562597 |
| identification of transcripts generated during the response of resistant biomphalaria glabrata to schistosoma mansoni infection using suppression subtractive hybridization. | suppression subtractive hybridization (ssh) was used to construct a complementary dna library enriched for transcripts more abundantly expressed in the resistant bs90 strain of biomphalaria glabrata at 12 hr postinfection with schistosoma mansoni as compared with the susceptible m-line strain under the same circumstances. one hundred and twelve clones of the library were sequenced, yielding 88 unique ssh-expressed sequence tags (ests). differential expression screening indicated that 22 of the 8 ... | 2004 | 15562603 |
| schistosomiasis mansoni in areas of low transmission: epidemiological characterization of venezuelan foci. | severe schistosomiasis is a rare event in venezuela nowadays, after a successful national campaign by the schistosomiasis control program. unfortunately, this program has practically disappeared, and snail surveillance in field is not a priority, anymore. thus, schistosomiasis has become a neglected disease in this country. however, surveys in different populations from the endemic area have shown particular epidemiological features described herein. in five communities we evaluated 2,175 person ... | 2002 | 12426585 |
| sequencing of simple sequence repeat anchored polymerase chain reaction amplification products of biomphalaria glabrata. | simple sequence repeat anchored polymerase chain reaction amplification (ssr-pcr) is a genetic typing technique based on primers anchored at the 5' or 3' ends of microsatellites, at high primer annealing temperatures. this technique has already been used in studies of genetic variability of several organisms, using different primer designs. in order to conduct a detailed study of the ssr-pcr genomic targets, we cloned and sequenced 20 unique amplification products of two commonly used primers, c ... | 2002 | 12426589 |
| distribution and schistosoma mansoni infection of biomphalaria glabrata in different habitats in a rural area in the jequitinhonha valley, minas gerais, brazil: environmental and epidemiological aspects. | this paper examines the distribution and infection of biomphalaria glabrata with schistosoma mansoni in all aquatic snail habitats in a rural area in the state of minas gerais, brazil, in relation to physico/biotic and behavioral factors. snail and environmental surveys were carried out semi-annually between july 2001 and november 2002 at 106 sites. collected snails were examined in the laboratory for infection. b. glabrata densities were highest in overflow ponds, irrigation ponds, springs, can ... | 2004 | 15654420 |
| polymerase chain reaction and restriction fragment length polymorphism of cytocrome oxidase subunit i used for differentiation of brazilian biomphalaria species intermediate host of schistosoma mansoni. | the intermediate hosts of schistosoma mansoni, in brazil, biomphalaria glabrata, b. tenagophila and b. straminea, were identified by restriction fragment length polymorphism analysis of the mitochondrial gene cytochrome oxidase i (coi). we performed digestions with two enzymes (alui and rsai), previously selected, based on sequences available in genbank. the profiles obtained with rsai showed to be the most informative once they were polymorphic patterns, corroborating with much morphological da ... | 2002 | 12426594 |
| echinostoma paraensei: differential gene transcription in the sporocyst stage. | the sporocyst stage of trematode development plays the crucial role of establishing a successful infection in the molluscan intermediate host. due to the small size and presence of this stage within the tissues of the host, much of our current knowledge of sporocyst biology relies on cultured specimens. to gain insight into the transcriptional patterns of early sporocysts, suppression subtractive hybridization was employed to identify 69 unique expressed sequence tags likely to be upregulated in ... | 2005 | 15687016 |
| [socio-cultural and ethical factors involved in the diagnosis of schistosomiasis mansoni in an area of low endemicity]. | five annual parasitological surveys and one serological survey, respectively based on the kato-katz and free sedimentation methods and the western blot technique, were conducted in sumidouro, rio de janeiro, brazil, an endemic county for schistosomiasis. possible influences of the use of these methodologies on social, cultural, and ethical aspects of the study population were also evaluated. having the opportunity to choose the different techniques was a conclusive issue influencing participatio ... | 2005 | 15692642 |
| gene discovery and expression analysis of immune-relevant genes from biomphalaria glabrata hemocytes. | the immune effector cells (hemocytes) of the snail host biomphalaria glabrata are known to play a key role in recognition and elimination of larval helminths such as the human blood fluke schistosoma mansoni. to identify novel immune-relevant genes, we undertook an expressed sequence tag program. a hemocyte cdna library was constructed using snails that were not exposed to a particular pathogen or parasite but maintained in non-axenic conditions. putative function could be assigned to 53% of the ... | 2004 | 15707661 |
| the molluscicidal activity of niclosamide (bayluscide wp70(r)) on melanoides tuberculata (thiaridae), a snail associated with habitats of biomphalaria glabrata (planorbidae). | the aim of this study was to determine the toxicity of niclosamide (bayluscide (r)) on melanoides tuberculata and biomphalaria glabrata under laboratory conditions. the latter species is the intermediate host of schistosoma mansoni (sambon 1917). m. tuberculata was successfully used as competitor of b. glabrata in biological control programs in french west indies. both molluscicide and biological control using m. tuberculata have proved to be successful in reducing the population density of b. g ... | 2002 | 12219145 |
| genetic differentiation, dispersal and mating system in the schistosome-transmitting freshwater snail biomphalaria glabrata. | biomphalaria glabrata is the main intermediate host of schistosoma mansoni in america and one of the most intensely studied species of freshwater snail, yet very little is known about its population biology. here, we used seven highly polymorphic microsatellite loci to analyse genetic diversity in populations from three regions (lesser antilles, venezuela and southern brazil). considerable genetic variation was detected, with an average (s.d.) h(0) = 0.32 (0.24). more diversity per population wa ... | 2002 | 12242641 |
| genetic markers between biomphalaria glabrata snails susceptible and resistant to schistosoma mansoni infection. | the analysis of the genetic variability related to susceptibility to schistosoma mansoni infection in the vector of the genus biomphalaria is important in terms of a better understanding of the epidemiology of schistosomiasis itself, the possible pathological implications of this interaction in vertebrate hosts, and the formulation of new strategies and approaches for disease control. in the present study, the genetic variability of b. glabrata strains found to be resistant or susceptible to s. ... | 2002 | 12426595 |
| antigenic community between schistosoma mansoni and biomphalaria glabrata: on the search of candidate antigens for vaccines. | we have previously confirmed the presence of common antigens between schistosoma mansoni and its vector, biomphalaria glabrata. cross-reactive antigens may be important as possible candidates for vaccine and diagnosis of schistosomiasis. sera from outbred mice immunized with a soluble biomphalaria glabrata antigen (sbga) of non-infected b. glabrata snails recognized molecules of sbga itself and s. mansoni awa by western blot. recognition of several molecules of the sbga were inhibited by pre-inc ... | 2002 | 12426602 |
| emergence of cercariae of echinostoma caproni and schistosoma mansoni from biomphalaria glabrata under different laboratory conditions. | release of echinostoma caproni cercariae and schistosoma mansoni from experimentally infected biomphalaria glabrata snails maintained under different laboratory conditions was studied. infected snails were isolated individually for 1 h in stender dishes containing 5 ml of artificial spring water and the number of cercariae released during this time was recorded. of numerous conditions tested, the addition of lettuce, the use of water conditioned by b. glabrata snails and a temperature of 35 degr ... | 2002 | 12498644 |
| comparative gene analysis of biomphalaria glabrata hemocytes pre- and post-exposure to miracidia of schistosoma mansoni. | the internal defense mechanism of the snail biomphalaria glabrata during a schistosome infection is activated and mediated via the immune effector cells known as hemocytes. since resistance and susceptibility to schistosome infection is known to be genetically determined, our interest was to use the est approach as a gene discovery tool to examine transcription profiles in hemocytes of resistant snails pre- and post-exposure to schistosoma mansoni. comparative analysis of the transcripts suggest ... | 2003 | 12615317 |
| identification of the putative mannose 6-phosphate receptor (mpr 46) protein in the invertebrate mollusc. | mannose 6-phosphate receptor (mpr 300) protein was earlier affinity purified on phosphomannan gel from the membrane extracts of whole animal acetone powder of a mollusc, unio, in the presence of edta (udaya lakshmi, y., radha, y., hille-rehfeld, a., von figura, k., and siva kumar, n. (1999) biosci. rep. 19:403-409). in the present study we demonstrate that the unio also contains the putative mannose 6-phosphate receptor (mpr 46) that can be purified on the same gel in presence of divalent metal ... | 2002 | 12635848 |
| effects of plagiorchis elegans (digenea: plagiorchiidae) infection of biomphalaria glabrata (pulmonata: planorbidae) on a challenge infection with schistosoma mansoni (digenea: schistosomatidae). | prior exposure of biomphalaria glabrata to the eggs of an incompatible digenean, plagiorchis elegans, rendered this snail host less suitable to a compatible species, schistosoma mansoni. although p. elegans failed to develop patent infections in b. glabrata, it reduced the production of s. mansoni cercariae by 88%. concomitantly, host attributes such as reproduction, growth, and survival were compromised. the effect of p. elegans infection was most severe among snails that, in addition, had deve ... | 2003 | 12659305 |
| pharmacological and autoradiographical characterization of serotonin transporter-like activity in sporocysts of the human blood fluke, schistosoma mansoni. | the present study focuses on the role of the biogenic monoamine serotonin (5-hydroxytryptamine) in the biology of sporocyst stages of the human blood fluke, schistosoma mansoni, and its importance during obligate development within its snail host biomphalaria glabrata. based on previous work demonstrating that snails infected with s. mansoni have reduced levels of 5-hydroxytryptamine, we hypothesized that sporocysts actively transport this molecule from the host milieu. intact sporocysts isolate ... | 2003 | 12861423 |
| the respiratory properties of biomphalaria glabrata exposed to schistosoma mansoni infection, starvation, co, and choices of different oxygen concentrations. | the oxygen consumption rate (vo(2)) of biomphalaria glabrata populations, using polarometric and manometric methods, when plotted against dried body mass as logarithmic co-ordinates, respectively, fell on a regression line with a slope between 0.933 and 1.02. the slope of the regression line for non-infected schistosoma mansoni populations was found to be 1.04 with no differences in the vo(2) between infected and non-infected snails. the vo(2) of co-treated snails was the same as for the control ... | 2003 | 12880585 |
| the major soluble 19.6 kda protein of the organic shell matrix of the freshwater snail biomphalaria glabrata is an n-glycosylated dermatopontin. | the major biomphalaria glabrata shell matrix protein of 19.6 kda was isolated by preparative electrophoresis and sequenced. the sequence of 148 amino acids showed 32% sequence identity to mammalian dermatopontin sequences and 34-37% identity to two invertebrate dermatopontins described previously. a unique feature of the shell matrix dermatopontin was the presence of a single n-glycosylation consensus sequence, the asparagine of which was completely modified with a pentasaccharide. sequence anal ... | 2003 | 12922172 |
| a comparative parasitologic study on biomphalaria glabrata snail and c3h/he mice infected with human and murine isolates of schistosoma mansoni derived from sumidouro, rio de janeiro, brazil. | experiments were carried out to analyze the biological characteristics of two sympatric isolates of schistosoma mansoni derived from humans and murines in a low endemic transmission area (sumidouro county, state of rio de janeiro, brazil). sympatric reared-laboratory biomphalaria glabrata and c3h/he mice were used as experimental hosts. parameters assessed comprised: precercarial period, infectivity and mortality (snails), prepatent period, infectivity (percentage of cercariae maturation into ad ... | 2003 | 14595456 |
| phylogeography of biomphalaria glabrata and b. pfeifferi, important intermediate hosts of schistosoma mansoni in the new and old world tropics. | the historical phylogeography of the two most important intermediate host species of the human blood fluke schistosoma mansoni, b. glabrata in the new world, and b. pfeifferi in the old world, was investigated using partial 16s and nd1 sequences from the mitochondrial genome. nuclear sequences of an actin intron and internal transcribed spacer (its)-1 were also obtained, but they were uninformative for the relationships among populations. phylogenetic analyses based on mtdna revealed six well-di ... | 2003 | 14629384 |
| schistosoma mansoni and echinostoma caproni excretory-secretory products differentially affect gene expression in biomphalaria glabrata embryonic cells. | biomphalaria glabrata embryonic (bge) cells have been shown to be a valuable in vitro cellular model for the study of snail host-parasite interactions. they both promote the growth and differentiation of various trematode species including schistosoma mansoni, and echinostoma caproni and share some morphological and functional features with circulating haemocytes. as an approach to investigate snail genes potentially regulated following exposure to trematode excretory-secretory (es) products, we ... | 2003 | 14700189 |
| difference in the susceptibility to certain molluscicides and schistosoma mansoni infection of three forms egyptian biomphalaria glabrata. | the first generation of 3 morphologically different forms of b. glabrata collected from giza were compared for lc50 values susceptibility to bayluscide and copper sulphate (chemical molluscicides) and anagallis arvensis and calendula micrantha (plant molluscicides) and to schistosoma mansoni infection. form (2) as juvenile and adult were less sensitive to c. micrantha and a. arvensis. form (3) as juvenile and form (1) as adult were least sensitive to cuso4. approximately the same susceptibility ... | 2003 | 14708851 |
| heredity of specific host-finding behaviour in schistosoma mansoni miracidia. | two strains of schistosoma mansoni were used to investigate the hereditary basis of species-specific host recognition by analysing behavioural responses of miracidia to snail-conditioned water. an egyptian strain of s. mansoni, capable of distinguishing its host snail biomphalaria alexandrina from other snails was cycled repeatedly through biomphalaria glabrata, the intermediate host of a brazilian strain known to respond even to non-susceptible snails with high intensity. after 5 cycles in the ... | 2004 | 15206466 |
| polymerase chain reaction and restriction fragment length polymorphism analysis of the its2 region for differentiation of brazilian biomphalaria intermediate hosts of the schistosoma mansoni. | we sequenced the internal transcribed spacer 2 of the ribosomal dna (its2-dnar) from the three schistosoma mansoni intermediate hosts in brazil: biomphalaria glabrata, biomphalaria tenagophila and biomphalaria straminea. analysis of a restriction map from those sequences allowed us to select putative restriction enzymes able to identify the snail species under study. four restriction enzymes were used and hpaii provided simple species-specific profiles easily visualized in polyacrylamide gels. t ... | 2004 | 15334271 |
| molecular identification of symbionts from the pulmonate snail biomphalaria glabrata in brazil. | the icthyosporean, capsaspora owczarzaki, a known predator of schistosoma mansoni sporocysts in vitro, is more prevalent in laboratory-reared strains of the intermediate snail host, biomphalaria glabrata resistant to s. mansoni, than from the susceptible m line strain. we examined whether b. glabrata resistant to the nih-pr-1 strain of s. mansoni from 2 regions in brazil were also host to c. owczarzaki. symbiont presence was examined using hemolymph culturing and nested polymerase chain reaction ... | 2004 | 15357065 |
| constitutive differences in cu/zn superoxide dismutase mrna levels and activity in hemocytes of biomphalaria glabrata (mollusca) that are either susceptible or resistant to schistosoma mansoni (trematoda). | genetic strains of the snail biomphalaria glabrata vary in their resistance to the parasite schistosoma mansoni. phagocytic cells (hemocytes) circulating in the hemolymph of b. glabrata play an essential role in the snail's innate immune response. hemocytes of resistant b. glabrata kill s. mansoni in vitro via a mechanism which involves a respiratory burst. reactive oxygen species (ros), which are products of the respiratory burst, can act as mediators of both oxidative damage and of immune-rela ... | 2004 | 15383302 |
| spatial distribution of schistosomiasis foci on itamaracá island, pernambuco, brazil. | acute cases of schistosomiasis have been found on the coastal area of pernambuco, brazil, due to environmental disturbances and disorderly occupation of the urban areas. this study identifies and spatially marks the main foci of the snail host species, biomphalaria glabrata on itamaracá island. the chaotic occupation of the beach resorts has favoured the emergence of transmission foci, thus exposing residents and tourists to the risk of infection. a database covering five years of epidemiologica ... | 2004 | 15486640 |
| rural tourism as risk factor for the transmission of schistosomiasis in minas gerais, brazil. | recently, the booming rural tourism in endemic areas of the state of minas gerais was identified as a contributing factor in the dissemination of the infection with schistosoma mansoni. this article presents data from six holiday resorts in a rural district approximately 100 km distant from belo horizonte, mg, brazil, where a possibly new and until now unperceived way of transmission was observed. the infection takes place in swimming pools and little ponds, which are offered to tourists and the ... | 2004 | 15486645 |
| effects of schistosoma mansoni infection on inorganic elements in the snail biomphalaria glabrata. | inductively coupled plasma atomic emission spectrometry (icp-aes) was used to study element ions in whole bodies of uninfected biomphalaria glabrata snails and those experimentally infected with larval schistosoma mansoni trematodes. infected snails were analysed 8 weeks post-infection. cohort snails that were left uninfected were analysed at the same time as the infected snails. sixteen elements (aluminum, boron, barium, calcium, cadmium, copper, iron, potassium, magnesium, manganese, sodium, n ... | 2004 | 15575993 |
| specific identification of egyptian biomphalaria species and possible hybrids using the polymerase chain reaction based on nuclear and mitochondrial loci. | the snail historically implicated in the transmission of schistosoma mansoni in egypt is biomphalaria alexandrina. the problem of schistosomiasis in egypt has been complicated in recent years by the introduction of biomphalaria glabrata, which has been reported to hybridize with b. alexandrina. both introduced and hybrid snails also pose a threat with respect to s. mansoni transmission. as morphological differentiation of these snails is difficult, using three dna loci, nuclear its1 and its2, an ... | 2004 | 15652216 |
| effects of various larval digeneans on the calcium carbonate content of the shells of helisoma trivolvis, biomphalaria glabrata, and physa sp. | the calcium carbonate concentrations in the shells of helisoma trivolvis and physa sp. naturally infected with larval trematodes and biomphalaria glabrata experimentally infected with larval trematodes were analyzed quantitatively. the larval trematode-snail relationships studied were h. trivolvis infected with larval echinostoma trivolvis and physa sp. infected with various larval digeneans, and b. glabrata infected with echinostoma caproni or schistosoma mansoni. the calcium carbonate concentr ... | 2005 | 15678354 |
| a study of the larvicidal and molluscicidal activities of some medicinal plants from northeast brazil. | in a search for natural products that could be used to control the vectors of tropical diseases, 23 extracts of medicinal plants from the northeast of brazil have been tested for molluscicidal activity against egg masses and adults of the snail biomphalaria glabrata, for larvicidal activity against the larvae of the mosquito aedes aegypti, and for general toxicity against the larvae of the brine shrimp artemia salina. of these extracts, two were active against the adult snail, one against snail ... | 2005 | 15707752 |
| dispersal in a parasitic worm and its two hosts: consequence for local adaptation. | characterizing host and parasite population genetic structure and estimating gene flow among populations is essential for understanding coevolutionary interactions between hosts and parasites. we examined the population genetic structure of the trematode schistosoma mansoni and its two host species (the definitive host rattus rattus and the intermediate host biomphalaria glabrata) using microsatellite markers. parasites were sampled from rats. the study was conducted in five sites of the guadelo ... | 2005 | 15807416 |
| a conserved retinoid x receptor (rxr) from the mollusk biomphalaria glabrata transactivates transcription in the presence of retinoids. | retinoid x receptors (rxr) are members of the nuclear receptor superfamily of ligand-activated transcription factors that have been characterized in a wide variety of metazoan phyla. they act as heterodimer partners of other nuclear receptors, and in vertebrates also activate transcription as homodimers in the presence of a ligand, 9-cis retinoic acid. in order to test the hypothesis that retinoic acid signaling pathways involving rxrs are present in the lophotrochozoa, we have sought to isolate ... | 2005 | 15821117 |
| [quantitative study of metal present in the hemolymph of biomphalaria glabrata (gastropoda), infected and uninfected with schistosoma mansoni]. | we conducted a preliminary study to quantify and compare two concentrations of the same metals present in the hemolymph of snail biomphalaria glabrata. in this context, we used induction coupled plasma optical emission spectroscopy technique (icp-oes), to analyze the metals in the two samples (snails infected and not infected with schistosoma mansoni). the metals studied were: aluminum, calcium, cadmium, cobalt, chromium, copper, iron, potassium, magnesium, manganese, lead and zinc. preliminary ... | 2005 | 15821791 |
| intraspecific competition and the evolution of virulence in a parasitic trematode. | intrahost competition between parasite genotypes has been predicted to be an important force shaping parasite ecology and evolution and has been extensively cited as a mechanism for the evolution of increased parasite virulence. however, empirical evidence demonstrating the existence and nature of intraspecific competition is lacking for many parasites. here, we compared within-host competitiveness between genetic strains of schistosoma mansoni with high (high-v) or low (low-v) virulence to thei ... | 2005 | 15856697 |
| differential expression of frep genes in two strains of biomphalaria glabrata following exposure to the digenetic trematodes schistosoma mansoni and echinostoma paraensei. | fibrinogen-related proteins (freps) are hypothesized to function in non-self-recognition in the snail biomphalaria glabrata. to investigate this assumption, the expression of four members of the frep gene family was studied using quantitative pcr at 0.5-16 days following exposure of m line and bs-90 strain b. glabrata to echinostoma paraensei and schistosoma mansoni. both strains react to, but fail to eliminate e. paraensei. only the bs-90 strain is immunologically resistant to s. mansoni. both ... | 2005 | 15859234 |
| common antigenicities between angiostrongylus cantonensis and various species of snails. | studies on common antigenicities were carried out by using rabbit sera immunized with angiostrongylus cantonensis adult worms or the third stage larvae and antigens of various species of snails and vice versa by the immunoblotting technique. the results obtained are summarized as follows: (1) common antigenicities between a. cantonensis adult worms and snails susceptible to a. cantonensis were observed in a range of molecular weights of 14.3 to 200 kda. in puerto rican pigmented biomphalaria gla ... | 2004 | 15916068 |
| respiratory burst of biomphalaria glabrata hemocytes: schistosoma mansoni-resistant snails produce more extracellular h2o2 than susceptible snails. | the production of reactive oxygen species by hemocytes from the gastropod biomphalaria glabrata has been linked to their ability to kill the trematode parasite schistosoma mansoni. for 2 laboratory strains of the snail, 1 resistant (13-16-r1) and 1 susceptible (mo) to the pr1 strain of s. mansoni, we compared hemocyte production of extracellular hydrogen peroxide when stimulated with the protein kinase c agonist phorbol myristate acetate (pma). the time course of the pma-induced response is simi ... | 2005 | 15986600 |
| an expressed sequence tag survey of gene expression in the pond snail lymnaea stagnalis, an intermediate vector of trematodes [corrected]. | the pond snail lymnaea stagnalis is an intermediate vector for the liver fluke fasciola hepatica, a common parasite of ruminants and humans. yet, despite being a disease of medical and economic importance, as well as a potentially useful comparative tool, the genetics of the relationship between lymnaea and fasciola has barely been investigated. as a complement to forthcoming f. hepatica expressed sequence tags (ests), we generated 1320 ests from l. stagnalis central nervous system (cns) librari ... | 2005 | 15991497 |
| a molecular survey of biomphalaria in egypt: is b. glabrata present? | two species of biomphalaria are reported from egypt, the indigenous biomphalaria alexandrina and biomphalaria glabrata, the latter believed to be introduced during the past few decades. both are known to be excellent hosts of schistosoma mansoni, the human-infecting blood fluke common in egypt. given the concerns regarding the spread of the exotic b. glabrata, this study was carried out to get a more current picture of the status of biomphalaria in egypt. snail collections were undertaken during ... | 2005 | 16014848 |