| [the resistance of biomphalaria glabrata to schistosoma mansoni infection: variations in the prepatent period and in compatibility]. | biomphalaria glabrata from belo horizonte, minas gerais, brazil, reared in laboratory, has a level of infection of 90% when exposed to 20 miracidia of the autochibonous le strain. the prepatent period was of 5 to 7 weeks whereas 5 to 10% of exposed snails do not shed cercariae. the eggs of negative snails were collected and the progeny was again submitted to individual infection with 20 miracidia. the mean of infection from f14 to f20 was of 43.6%. histological sections from f12, f14 and f15 sna ... | 1997 | 9265222 |
| partially degraded dna of parasitological interest serves as an adequate template for the production of random amplified polymorphic dnas (rapds). | genomic dna was extracted from schistosoma mansoni adult worms and deliberately degraded by sonication. samples with varying average molecular weight were subjected to rapd (randomly amplified polymorphic dna) analysis using the primer 3307 (5'-agtgctacgt-3') and other primers. reproducible and complex dna banding patterns were obtained, irrespective of the extent of dna degradation. the same amplification protocol was employed with naturally degraded biomphalaria glabrata genomic dna and the pr ... | 1997 | 9267422 |
| schistosoma japonicum: in vitro cultivation of miracidium to daughter sporocyst using a biomphalaria glabrata embryonic cell line. | in vitro cultivation of schistosoma japonicum miracidia to the mother sporocyst (ms) and then to the daughter sporocyst (ds) stage was achieved using the biomphalaria glabrata embryonic (bge) cell line as a coculture system. when comparing the effect of bge cell and ms density on ms development, it was apparent that bge cell density had a highly significant effect on both ms viability and growth. viability and growth rate of ms cultured under high cell density conditions (350 cells/mm2) were alm ... | 1997 | 9326883 |
| a comparative study of the organic acid content of the hemolymph of schistosoma mansoni-resistant and susceptible strains of biomphalaria glabrata. | the freshwater snail biomphalaria glabrata is an intermediate host of the trematode schistosoma mansoni. however, some strains of b. glabrata are resistant to successful infection by s. mansoni larvae. the present work examines the profile of organic acids present in s. mansoni-resistant and -susceptible strains of b. glabrata, in order to determine whether the type of organic acid present is related to susceptibility. the organic acids were extracted from the hemolymph of two susceptible b. gla ... | 1997 | 9332612 |
| comparative histopathology of biomphalaria glabrata, b. tenagophila and b. straminea with variable degrees of resistance to schistosoma mansoni miracidia. | a comparative histopathological study of three snails species--biomphalaria glabrata, b. tenagophila and b. straminea--which had been infected with schistosoma mansoni miracidia revealed similar qualitative features; consisting of areas of sporocyst proliferation and differentiation associated with reactive host reaction, at the time they were actively eliminating great number of cercariae. however, in specimens that were exposed to miracidia but failed to eliminate cercariae later on, different ... | 1997 | 9361747 |
| heat-shock response in a molluscan cell line: characterization of the response and cloning of an inducible hsp70 cdna. | sublethal heat-shock of cells of the bge (biomphalaria glabrata embryonic) snail cell line resulted in increased or new expression of metabolically labeled polypeptides of approximately 21.5, 41, 70, and 74 kda molecular mass. regulation of this response appeared to be at the transcriptional level since a similar protein banding pattern was seen upon sds-page/fluorographic analysis of polypeptides produced by in vitro translation of total rna from cells subjected to heat shock. using a yeast (sa ... | 1997 | 9367731 |
| phenoloxidase activity in the reproductive system of biomphalaria glabrata: role in egg production and effect of schistosome infection. | infection by larval trematodes often causes a cessation of egg production in its molluscan intermediate host and is referred to as parasitic castration. because phenoloxidase (po) has been shown to be involved in egg formation in other invertebrate species, we investigated the role of po in normal egg production in the snail, biomphalaria glabrata, and the effects of schistosoma mansoni infection on the po pathway in this snail. our data showed that po activity in the albumen gland (ag) is initi ... | 1997 | 9379290 |
| human schistosomiasis in puerto rico: reduced prevalence rate and absence of biomphalaria glabrata. | a combined epidemiologic and malacologic survey of schistosomiasis in puerto rico was carried out in areas where previous surveys had reported the prevalence of the disease. this limited survey, with 495 persons examined, found a low prevalence (0.6%) of schistosoma mansoni infections. the infections were restricted to three people more than 36 years of age. no infections were detected in children 16 years of age or less, and this cohort comprised 57.8% of the study group. malacologic surveys of ... | 1997 | 9392596 |
| schistosoma mansoni infection inhibits maturation of ovotestis allografts in biomphalaria glabrata (mollusca:pulmonata). | the posterior tip of juvenile snails, consisting of immature ovotestis, vesicular connective tissue, and digestive gland acini, all surrounded by body wall, was implanted into the hemocoel of allogeneic adult biomphalaria glabrata. recipient snails were either uninfected or had been infected 15 days previously with schistosoma mansoni. graft recipients were dissected at 30 or 60 days postimplantation (dpi), and the implants, along with preimplantation controls, were examined histologically. the ... | 1998 | 9488342 |
| observations on the miraxonal attraction exercised by sexually immature or adult biomphalaria glabrata infected or not by schistosoma mansoni. | the influence of age and the presence of secondary sporocysts in the miraxonal attraction exercised by biomphalaria glabrata on miracidia of schistosoma mansoni of the bh strain were studied. | 1997 | 9497557 |
| characterization of an intracellular receptor for activated protein kinase c (rack) from the mollusc biomphalaria glabrata, the intermediate host for schistosoma mansoni. | a receptor for activated protein kinase c (rack) was characterized from the mollusc biomphalaria glabrata, the intermediate host for the human parasite schistosoma mansoni. this protein was shown to possess structural and functional characteristics of other rack proteins from various cells and organisms. its ability to bind mammalian pkcs also confirmed the conservation of pkc and rack interactive domains throughout evolution. results of immunolocalization indicated the presence of bg rack in th ... | 1998 | 9562422 |
| a laboratory-based approach to biological control of snails. | development of schistosoma mansoni in the intermediate host biomphalaria glabrata is influenced by a number of parasite and snail genes. understanding the genetics involved in this complex host/ parasite relationship may lead to an often discussed approach of introducing resistant b. glabrata into the field as a means of biological control for the parasite. for the snail, juvenile susceptibility to the parasite is controlled by at least four genes, whereas one gene seems to be responsible for ad ... | 1997 | 9566236 |
| comparison of echinostoma caproni mother sporocyst development in vivo and in vitro using biomphalaria glabrata snails and a b. glabrata embryonic cell line. | biomphalaria glabrata embryonic (bge) cells have previously been shown to permit a successful cocultivation of schistosoma mansoni and schistosoma japonicum from miracidia to mother sporocysts (ms) and then to the production of daughter sporocysts (ds). to investigate further the properties of the bge culturing system we used echinostoma caproni under identical in vitro conditions. in vitro-derived miracidia were used either for experimental infections of b. glabrata snails, or for in vitro cult ... | 1998 | 9576492 |
| integrin-like rgd-dependent binding mechanism involved in the spreading response of circulating molluscan phagocytes. | circulating phagocytic cells (hemocytes) of the snail biomphalaria glabrata, intermediate host of the human blood fluke schistosoma mansoni, were treated with the tetrapeptide, arg-gly-asp-ser (rgds), an integrin-specific adhesion inhibitor, and assessed for their ability to adhere and spread on uncoated and snail plasma protein-coated glass slides. although cells were capable of adherence, rgds significantly inhibited the spreading ability of hemocytes in both a time and rgds concentration-depe ... | 1998 | 9617582 |
| [relationship between pathogenicity of schistosoma mansoni in mice and the susceptibility of the vector mollusk. iv--infectiousness of miracidia]. | the infection ability of miracidia of bh and sj strains of s. mansoni, obtained from mice infected with cercariae taken from biomphalaria glabrata and biomphalaria tenagophila, genetically selected for susceptibility is compared with the infection ability of miracidia obtained from mice infected with larvae from non-selected mollusks. | 1997 | 9629726 |
| quantification of the population and phagocytary activity of hemocytes of resistant and susceptible strains of biomphalaria glabrata and biomphalaria tenagophila infected with schistosoma mansoni. | among the determinant factors in the resistance and susceptibility of biomphalaria to schistosoma mansoni, hemocytes play an important role. aiming at studying s. mansoni/biomphalaria interactions related to hemocytes, the first step is certainly connected with the standardization of this cell population in uninfected biomphalaria. in this way, quantification of this cell population in hemolymph, as well as its phagocitary capacity, have been determined for the first time. furthermore, using sus ... | 1997 | 9640781 |
| first report of biomphalaria glabrata in the state of rio grande do sul, brazil. | | 1998 | 9698841 |
| invasion of the nile valley in egypt by a hybrid of biomphalaria glabrata and biomphalaria alexandrina, snail vectors of schistosoma mansoni. | two years (1996-1997) of systematic survey showed that a hybrid of biomphalaria glabrata and biomphalaria alexandrina has invaded the irrigation and drainage systems in the nile delta and the valley nor the of el-menya. however, the infestation of water courses by and the population density of this snail were variable in various localities. the infestation rate ranged between 7.1% in el-fayoum governorate and 52.6% in el-dakahliya governorate and the snail density from 2 snails/site to 69.7 snai ... | 1998 | 9707685 |
| transfection and heat-inducible expression of molluscan promoter-luciferase reporter gene constructs in the biomphalaria glabrata embryonic snail cell line. | studies were initiated to begin developing a genetic transformation system for cells derived from the freshwater gastropod, biomphalaria glabrata, an intermediate host of the human blood fluke schistosoma mansoni. using a 70-kd heat-shock protein (hsp70) cdna probe obtained from the b. glabrata embryonic (bge) cell line, we cloned from bge cells a complete hsp70 gene including a 1-kb genomic dna fragment in its 5'-flanking region containing sequences indicative of a hsp promoter. identified in t ... | 1998 | 9749636 |
| host choice by larval parasites: a study of biomphalaria glabrata snails and schistosoma mansoni miracidia related to host size. | within snail/trematode associations the age/size of the host at infection has consequences with regard to miracidial infection success, further intramolluscan parasite development and reproduction, and the host response, mainly in terms of growth and reproductive effort. taking into account these differences, we were interested in determining whether miracidia could discriminate and make a choice between snails of different sizes. using the schistosoma mansoni/biomphalaria glabrata system, we co ... | 1998 | 9766901 |
| failure of schistosoma mansoni to reinfect biomphalaria glabrata snails: acquired humoral resistance or intra-specific larval antagonism? | failure of snail reinfection by schistosoma mansoni has been demonstrated in susceptible biomphalaria glabrata infected with 1 miracidium and subsequently re-exposed to 1 or 5 homologous parasite larvae. the acquisition of 'resistance' to secondary parasite infection was time dependent since complete inhibition was observed at 2 weeks and longer following monomiracidial exposure. this phenomenon was still observed in snails challenged 8 weeks after primary infection. histological observations re ... | 1998 | 9778633 |
| [lymnic snails from the microregion of belo horizonte, minas gerais, brazil with an emphasis on parasite disease vectors]. | a malacological survey to detect foci of transmission of schistosomiasis and other parasitic diseases was undertaken into water-courses from 13 municipalities of microregion of belo horizonte, mg, brazil. from 1990 to 1996, 22,066 snails were collected. from those, 378 (1.7%) were found infected by trematodes: biomphalaria glabrata (7,920), infected by schistosoma mansoni (1.9%), echinostomatidae (1.2%), strigeidae (0.6%), cercaria minense (0.1%) and derogenidae (-0.1%); b. straminea (4,093) inf ... | 1998 | 9789443 |
| recombinant human interleukin-1-mediated killing of schistosoma mansoni primary sporocysts in biomphalaria glabrata. | previous work has indicated that injection of recombinant-human interleukin (rhil)-1beta in schistosoma mansoni-infected m-line biomphalaria glabrata resulted in a significant reduction in the number of cercariae shed. the purpose of the present work was to determine if primary sporocysts were killed following rhil-1beta injection in susceptible snails and, if so, to determine if killing was the direct result of hemocyte activity. counting of primary sporocysts indicated a 50% reduction in the n ... | 1998 | 9794631 |
| compatibility of biomphalaria alexandrina, biomphalaria glabrata and a hybrid of both to seven strains of schistosoma mansoni from egypt. | the susceptibility of biomphalaria alexandrina, biomphalaria glabrata and a hybrid snail of both, all obtained from natural habitats in egypt, to infection with six human local strains of schistosoma mansoni and a laboratory strain of human origin was determined. the infection rate, prepatent period, periodic cercarial production and duration of cercarial shedding were compared in all cases. the results showed that each of the three studied biomphalaria snails had different rates of infection an ... | 1998 | 9914708 |
| molecular characterisation of intermediate snail hosts and the search for resistance genes. | the relationship between schistosomes and their intermediate hosts is an extremely intricate one with strains and species of the parasite depending on particular species of snail, which in turn may vary in their susceptibility to the parasites. in order to gain a better understanding of the epidemiology of the disease we have been investigating the use of molecular markers for snail identification and for studying host-parasite relationships. in this paper we will draw on examples concerning sch ... | 1998 | 9921331 |
| possible hybridization of brazilian planorbid snails and its importance in population dynamics. | this study focuses on the possibility of experimental hybridization among host snail species for schistosoma mansoni in brazil, with morphological characterization of the hybrids found. by using albinism as a genetic marker, intraspecific crossbreedings were performed between two strains of each species involved, in addition to interspecific crossbreedings; the only viable crossbreeding was between pigmented biomphalaria glabrata (paulista, pe) and albino b. tenagophila (joinville, sc), with the ... | 1998 | 9921356 |
| susceptibility of nectomys rattus (pelzen, 1883) to experimental infection with schistosoma mansoni (sambon, 1907): a potential reservoir in brazil. | the aim of the present research was to evaluate the potential of nectomys rattus, the "water rat", to develop schistosoma mansoni infection. comparison with n. squamipes was carried out. both species of rodents were submitted to transcutaneous infection using different infective cercariae loads: 50, 100 or 500. n. rattus showed high susceptibility to s. mansoni, with an infection rate of 71%. rodents were able to excrete viable eggs of s. mansoni in the faeces during all infection period. for bo ... | 1998 | 9921374 |
| effect of biomphalaria straminea plasma in the phagocytosis of biomphalaria glabrata hemolymph cells. | | 1998 | 9921375 |
| the identification of markers segregating with resistance to schistosoma mansoni infection in the snail biomphalaria glabrata. | both snail and parasite genes determine the susceptibility of the snail biomphalaria glabrata to infection with the trematode schistosoma mansoni. to identify molecular markers associated with resistance to the parasite in the snail host, we performed genetic crosses between parasite-resistant and -susceptible isogenic snails. because resistance to infection in adult snails is controlled by a single locus, dna samples from individual f2 and f1 backcross progeny, segregating for either the resist ... | 1999 | 9990054 |
| biomphalaria glabrata embryonic (bge) cell line supports in vitro miracidial transformation and early larval development of the deer liver fluke, fascioloides magna. | a bge cell co-culture system, previously shown to support the in vitro production of daughter sporocysts from mother sporocysts of schistosoma mansoni and s. japonicum, has proven capable of supporting the in vitro development of intramolluscan stages of the deer liver fluke, fascioloides magna. miracidia commenced transforming within 4 h of incubation with bge cells, and had completely shed their epidermal plates within 18-24 h. redial stages were visible inside in vitro-transformed mother spor ... | 1999 | 10028533 |
| cloning of a beta integrin subunit cdna from an embryonic cell line derived from the freshwater mollusc, biomphalaria glabrata. | a cdna encoding an integrin subunit was cloned and structurally characterized from an embryonic cell line derived from biomphalaria glabrata, snail intermediate host of the human blood fluke schistosoma mansoni. cells of the b. glabrata embryonic (bge) snail cell line were initially tested for their sensitivity to the integrin-specific tetrapeptide inhibitor arg-gly-asp-ser (rgds). washed bge cells when exposed to 0.5 to 2.0mm of rgds were significantly inhibited in their ability to spread on a ... | 1999 | 10072774 |
| comparative study on the effect of cyclic nucleotides related to the function of biomphalaria glabrata hemocytes and human granulocytes. | the biochemical processes linked up to cyclic nucleotides related to the phenomenon of phagocytosis in biomphalaria glabrata hemocytes were studied. in hemocytes the results suggest the presence of a phagocytic capacity similar to that observed in human cells related to regulation by cyclic adenylate monophosphate (camp), but not by cyclic guanylate monophosphate (cgmp). this similarity and differences in the metabolic process of phagocytary capacity between human phagocytary cells and hemocytes ... | 1999 | 10232783 |
| biomphalaria glabrata embryonic cells express a protein with a domain homologous to the lectin domain of mammalian selectins. | we have cloned from biomphalaria glabrata, the intermediate host of the helminth parasite schistosoma mansoni, a 36-kda apparent-molecular-mass molecule (bgsel) that shares sequence identity with selectins of the cell-adhesion-molecule superfamily. bgsel exhibited in its c-terminal part a putative c-type lectin domain similar to the selectin lectin domain. using antibodies to the recombinant bgsel protein, we demonstrated the presence of bgsel in snail hemocytes as well as in the cell line deriv ... | 1999 | 10344542 |
| partial lack of susceptibility to schistosoma mansoni infection of biomphalaria glabrata strains from itanhomi (minas gerais, brazil) after fourteen years of laboratory maintenance. | | 1999 | 10348995 |
| genetic diversity and recruitment pattern of schistosoma mansoni in a biomphalaria glabrata snail population: a field study using random-amplified polymorphic dna markers. | random-amplified polymorphic dna markers have been used to assess the amount and the distribution of the genetic diversity of schistosoma mansoni within a natural population of biomphalaria glabrata at a transmission site of the murine schistosomiasis focus of guadeloupe. despite high infection rate and heavy schistosome load within the definitive hosts (ratus rattus), prevalences within intermediate snails ranged from 0.2 to 4.8%. whatever the transmission season may be (rainy vs. dry), most of ... | 1999 | 10386434 |
| cellular response to echinostoma caproni infection in biomphalaria glabrata strains selected for susceptibility/resistance. | the biomphalaria glabrata/schistosoma mansoni system represented the only model available so far, for investigating snail resistance to parasites. a new host parasite model has been recently provided by selection of b. glabrata strains that are genetically resistant and susceptible to echinostoma caproni. as a first approach in investigating resistance mechanisms in this model, we compared the hemocytic response and its effect on e. caproni development in a susceptible and a resistant strains. h ... | 1999 | 10402206 |
| population biology of schistosoma mansoni in the black rat: host regulation and basic transmission rate. | a simple mathematical model was built to investigate the population biology of schistosoma mansoni in its natural definitive host, the black rat (rattus rattus). prevalence and parasite abundance over 13 years from field studies and data from laboratory experiments were used to set up the model. sensitivity analysis showed that the abundance of parasites is strongly influenced by variation in the values of infection parameters. the model shows that the parasite is able to control populations of ... | 1999 | 10404261 |
| contribution to the histology of biomphalaria glabrata. | a combination of histological techniques applied to the study of biomphalaria glabrata yielded some interesting new data about the histology of this snail, a major intermediate host of schistosoma mansoni in brazil. three kinds of pigments were identified: a dark pigment which bleached following oxidation with potassium permanganate; a lipofuchsin-like, diastase-resistant pas-positive pigment and an iron-containing pigment, probably related to hemosiderin. calcium was detected in small deposits ... | 1999 | 10495661 |
| profile of organic acid concentrations in the digestive gland and hemolymph of biomphalaria glabrata under estivation. | using high performance liquid chromatography (hplc) analysis it was possible to determine simultaneously the concentration of organic acids (pyruvate, lactate, succinate, fumarate, malate, acetate, propionate, acetoacetate, and ss-hydroxybutyrate) in the digestive gland and the extracellular concentration of these same acids in the hemolymph of estivating biomphalaria glabrata, the intermediate host of schistosoma mansoni. after a 7 day period of estivation, there was a significant increase in t ... | 1999 | 10585654 |
| a review of performance and pathogenicity of male and female schistosoma mansoni during the life-cycle. | the sexual life-history traits of schistosoma mansoni have been reviewed to compare male and female performance and pathogenicity against biomphalaria glabrata during the life-cycle. a meta-analysis was used on pooled results from different experiments. in most cases, there was no difference between males and females but male cercariae were significantly more infectious than female cercariae. conversely, cercarial production and cercarial life-span were significantly greater for females than for ... | 1999 | 10599077 |
| flukes without snails: advances in the in vitro cultivation of intramolluscan stages of trematodes. | in vitro cultivation of parasitic helminths, including the digenetic trematodes, has long been a valuable tool in medical and veterinary parasitology, permitting and/or facilitating the development of diagnostic reagents, chemotherapeutic agents, and vaccines and providing insights into naturally complex host-parasite interactions. in vitro cultivation of the intramolluscan stages of trematodes has been particularly challenging, given the ontogenic complexities involved in the production of mult ... | 2000 | 10631085 |
| isolation and characterization of microsatellite loci in the freshwater gastropod, biomphalaria glabrata, an intermediate host for schistosoma mansoni. | | 1999 | 10632870 |
| glycosidase activities in plasma of naive and schistosome-infected biomphalaria glabrata (gastropoda). | activity of the following glycosidases was detected in the plasma of the freshwater snail biomphalaria glabrata: beta-d-fucosidase, beta-d-glucosidase, beta-d-galactosidase, beta-d-mannosidase, beta-d-glucuronidase, n-acetyl-beta-d-galactosaminidase, n-acetyl-beta-d-glucosaminidase, and lysozyme. at the physiological ph (7.2-7.4) of snail haemolymph, enzymatic activity was about 10-50% of the maximum activity at each enzyme's respective acid ph-optimum. schistosome-susceptible b. glabrata showed ... | 1999 | 10633917 |
| factors affecting adoptive transfer of resistance to schistosoma mansoni in the snail intermediate host, biomphalaria glabrata. | we examined potential variables affecting adoptive transfer of resistance to schistosoma mansoni in biomphalaria glabrata implanted with amebocyte-producing organs (apos) from resistant snails. transplants of 7 tissues other than the apo (heart, kidney, mantle, albumin gland, brain, digestive gland, and gonad) did not transfer resistance, suggesting a unique property of this structure. only apos from donors previously exposed to miracidia transferred resistance, although whether this is evidence ... | 1999 | 10647038 |
| 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 |
| screening of mediterranean rosaceae plants for their molluscicidal and piscicidal activities. | extracts of increasing polarity of 13 plants belonging to mediterranean rosaceae were tested for possible lethal toxicity against biomphalaria glabrata say, a snail intermediate host of schistosoma mansoni sambon. due to the search for compounds without toxicity in nontarget organisms, principally fish and humans, the piscicidal toxicity of the active extracts was also evaluated. | 2000 | 10685112 |
| molecular studies of biomphalaria glabrata, an intermediate host of schistosoma mansoni. | the freshwater gastropod biomphalaria glabrata is one of the most important invertebrate hosts of the helminth parasite schistosoma mansoni. investigators are using different strategies to determine the molecular basis of this snail-parasite relationship. of particular interest are the identification of parasite resistance genes in the snail, and the application of molecular probes to better understand the epidemiology of schistosomiasis. this review will focus on recent advances that have been ... | 2000 | 10731574 |
| rescue of sporocysts of schistosoma mansoni in nonsusceptible biomphalaria by head-foot transplantation into susceptible snails. | to measure the longevity of sporocysts of schistosoma mansoni in nonsusceptible snails (13-16-r1 and salvador strains of biomphalaria glabrata, and biomphalaria obstructa), the head-foot (hf) of miracidia-exposed snails was transplanted into the hemocoel of a susceptible nih albino recipient at 1-36 days postexposure (dpe). recipient snails which were not exposed to miracidia then were monitored for infection transferred by the implant, and infection prevalences in recipients of hf transplants f ... | 2000 | 10780550 |
| use of differential display to detect changes in gene expression in the intermediate snail host biomphalaria glabrata upon infection with schistosoma mansoni. | changes in gene expression in biomphalaria glabrata following infection with schistosoma mansoni have been investigated using a modified differential display approach. rna was extracted from ovotestis, mantle tissue and anterior nephridium of control and exposed snails at 2 time-points (4 h and 24 h) post-exposure and analysed by rna fingerprinting. a number of transcripts were identified; some novel and some homologous to mrnas in genembl that were previously unknown in b. glabrata. down regula ... | 2000 | 10811281 |
| 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 |
| [compatibility between nine strains of biomphalaria glabrata coming from endemic and non-endemic areas and one strain of schistosoma mansoni from venezuela]. | nine lots of 32 b. glabrata snails (5-7mm in diameter) from the following strains from the endemic area: cagua, valencia lake (puerta negra sector), ingenio bolívar (aragua state), mariara, caserío el 25 and güigüe (carabobo state), and from the non-endemic area: anzoátegui (lara state), chabasquén (portuguesa state) and caripe (monagas state) were experimentally infected (5 miracidiums/snail) with c5 schistosoma mansoni strain. the intramolluscal prepatent period oscillated between 23 and 25 da ... | 1999 | 10881105 |
| [a malacological survey in city parks in belo horizonte, minas gerais, brasil] | the greater metropolitan area of belo horizonte currently contains 18 city parks (also known as "ecological parks") with various bodies of water (lakes, springs, streams, etc). initial research in 17 of these parks showed the occurrence of intermediate mollusk hosts for schistosoma mansoni in at least 4. monthly captures done from august 1994 to february 1996 showed the following results for these planorbids: julien rien park: 1,145 specimens of biomphalaria glabrata (2 to 13 mm); betânia park: ... | 1997 | 10886861 |
| toxic activities of the plant jatropha curcas against intermediate snail hosts and larvae of schistosomes. | the aim of studies on plant molluscicides is to complement methods for controlling snails acting as intermediate hosts of schistosomes. we report on the toxic activity of extracts from jatropha curcas l. (euphorbiaceae) against snails transmitting schistosoma mansoni and s. haematobium. we studied different extracts' effects on infectious larvae, cercariae and miracidia of s. mansoni. compared to aqueous extract, methanol extract showed the highest toxicity against all tested organisms with lc10 ... | 2000 | 10929142 |
| [susceptibility of biomphalaria glabrata to schistosoma mansoni from venezuela and brazil]. | schistosoma mansoni partially develops its life cycle into snails of the family planorbid. biomphalaria glabrata represents an important host-intermediate. this paper reports experimental infection with miracidia vs. snail in sympatric and parapatric combination. the infection assay to sympatric combination were: bh snail (belo horizonte, brasil) vs. a common geographic origin parasite, and barbula, carabobo state, venezuela vs. sm venezuela parasitic. the parapatric combination were: bh snail v ... | 1999 | 10932760 |
| [ecoepidemiology of urban schistosomiasis in itamaracá island, pernambuco, brazil]. | in 1988, 22 autochthonous cases from accidental exposure were registered in forte orange beach, itamaracá island, pernambuco, brazil. all cases occurred in middle-to-upper class individuals who were vacationing in the island. after the cases were identified, the major objective was to find breeding sites of schistosomiasis vectors and correlate the biological factors with the environmental conditions. | 2000 | 10973151 |
| 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 |
| 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 |
| [assessment of schistosomiasis and other intestinal parasitoses in school children of the bambuí municipality, minas gerais, brazil]. | this work was carried out with the purpose of determining the prevalence of intestinal parasitoses in the school children of bambuí, through parasitological examinations (direct and kato-katz methods) and reevaluating the snails' breeding places described in the county. of the 2,091 school children examined, 20.1% had at least one parasitic infection. giardia lamblia, entamoeba coli, ascaris lumbricoides and hookworm are the most frequent parasites, with a prevalence of 6.2%, 6.2%, 4.8% and 1.4% ... | 2000 | 11064579 |
| 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 |
| a comparative study of mechanisms underlying digenean-snail specificity: in vitro interactions between hemocytes and digenean larvae. | a panel of 4 digenetic trematode 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) was examined to determine if known patterns of host specificity could be explained by the tendency of digenean larvae to be bound by snail hemocytes, or by the ability of larvae to influence the spreading behavior of hemocytes. in short-term (1 hr) ... | 2000 | 11128474 |
| molecular evidence supports an african affinity of the neotropical freshwater gastropod, biomphalaria glabrata, say 1818, an intermediate host for schistosoma mansoni. | freshwater snails of the genus biomphalaria, preston 1910, are the most important and widely distributed intermediate hosts of schistosoma mansoni, the blood fluke responsible for human intestinal schistosomiasis, in africa and the neotropics. s. mansoni is thought to have been imported repeatedly into the americas during the last 500 years with the african slave trade. surprisingly considering that the new and old world separated 95-106 million years (myr) ago, the disease rapidly became establ ... | 2000 | 11133023 |
| effects of diet on the development of schistosoma mansoni in biomphalaria glabrata and on the neutral lipid content of the digestive gland-gonad complex of the snail. | in a previous study, when the snail biomphalaria glabrata was infected with schistosoma mansoni and maintained on a diet of hen's egg yolk, it produced fully developed cercariae in about one-half the time taken by snails fed romaine lettuce. increased lipids were also noted in the snails fed the yolk diet. the purpose of the present study was to further investigate nutritional effects of a high-lipid diet on larval schistosome development and to reexamine the time to cercarial patency in infecte ... | 2001 | 11227897 |
| 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 |
| 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 |
| differential gene expression in haemocytes of the snail biomphalaria glabrata: effects of schistosoma mansoni infection. | parasite encapsulation and destruction in biomphalaria glabrata has been shown to involve the cellular component of the snail's internal defence system, the haemocytes. to identify genes involved in the immunobiology of these cells, we used the method of differential display reverse transcriptase polymerase chain reaction (ddrt-pcr) to investigate differential gene regulation in haemocytes isolated from schistosoma mansoni exposed and unexposed snails. rna isolated from circulating haemocytes fr ... | 2001 | 11336750 |
| [host parasite relationship among 3 schistosoma mansoni and 6 biomphalaria glabrata strains from epidemic and no epidemic venezuelan areas is studied]. | six lots of 18 b. glabrata from: la victoria, turmero, cagua in aragua state; caserío el 25 in carabobo state, chabasquén in portuguesa state and humocaro bajo in lara state, were experimentally infected with miracidia of sm, c5 and c6 strains of schistosoma mansoni (18 snails/schistosoma mansoni strain). the averages of the intramolluscal period (imp) obtained for the s. mansoni strains were very similar and comprised between 35.4 and 36.1 days. no significative statistical differences in the i ... | 2000 | 11338975 |
| 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 |
| the control of the schistosome-transmitting snail biomphalaria glabrata by the plant molluscicide euphorbia splendens var. hislopii (syn milli des. moul): a longitudinal field study in an endemic area in brazil. | under laboratory conditions, latex from euphorbia splendens has shown promise as a plant molluscicide for control of biomphalaria species, intermediate hosts for schistosoma mansoni. the purpose of this study was to evaluate its efficiency under field conditions. application of filtered latex at 12 ppm to one stream in an endemic rural area in minas gerais state, brazil, in september 1995, did result in a reduction in snail density as compared to an untreated stream but the snail population reco ... | 2001 | 11369309 |
| structure of two frep genes that combine igsf and fibrinogen domains, with comments on diversity of the frep gene family in the snail biomphalaria glabrata. | upon exposure to infection with digenetic trematodes such as echinostoma paraensei, the freshwater snail biomphalaria glabrata produces increased quantities of hemolymph lectins, some of which are unique polypeptides containing both immunoglobulin superfamily (igsf) and fibrinogen domains. these unusual lectins have been termed fibrinogen-related proteins (freps), and recognize and precipitate digenean antigens. we here report 11 distinct frep-encoding sequences from b. glabrata, and provide the ... | 2001 | 11376947 |
| genetic variability in brazilian populations of biomphalaria straminea complex detected by simple sequence repeat anchored polymerase chain reaction amplification. | biomphalaria glabrata, b. tenagophila and b. straminea are intermediate hosts of schistosoma mansoni, in brazil. the latter is of epidemiological importance in the northwest of brazil and, due to morphological similarities, has been grouped with b. intermedia and b. kuhniana in a complex named b. straminea. in the current work, we have standardized the simple sequence repeat anchored polymerase chain reaction (ssr-pcr) technique, using the primers (ca)8ry and k7, to study the genetic variability ... | 2001 | 11391428 |
| parasite (schistosoma mansoni) and host (biomphalaria glabrata) genetic diversity: population structure in a fragmented landscape. | random amplified polymorphic dna (rapd) markers were used to quantify genetic diversity within and between 5 populations of schistosoma mansoni within its definitive host (rattus rattus) and the 5 corresponding populations of the snail intermediate host (biomphalaria glabrata) from a limited endemic area of murine schistosomiasis on the island of guadeloupe. analysis of molecular variance (amova) and canonical correspondence analysis (cca) were used to test the significance of genetic differenti ... | 2001 | 11393828 |
| 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 |
| [freshwater snails of the campus of manguinhos, oswaldo cruz foundation, rio de janeiro, rj]. | a survey of freshwater gastropods of the campus of manguinhos, fundação oswaldo cruz, rio de janeiro, was carried out during the last two years aiming to compare the current species with those found at the beginning of this century. among 18 breeding sites in 880,000m2 of the surveyed area, 13 showed the following species: antillorbis nordestensis; biomphalaria glabrata; biomphalaria straminea; lymnaea columella; melanoides tuberculatus; physa cubensis; pomacea glauca and pomacea lineata. notabl ... | 2001 | 11460215 |
| hematopoietic tissue allografts in biomphalaria glabrata (mollusca: pulmonata) induce humoral immunity to schistosoma mansoni. | we examined a potential mechanism for adoptively transferred resistance against schistosoma mansoni in schistosome-susceptible snails receiving allografts of the hematopoietic amebocyte-producing organ (apo) from a schistosome-resistant strain of biomphalaria glabrata. susceptible nih albino snails first were implanted with the apo from resistant salvador strain donors. at 14 days post-implantation, cell-free plasma was isolated from apo recipients and injected into a second group of nih albino ... | 2001 | 11472778 |
| sequential histological changes in biomphalaria glabrata during the course of schistosoma mansoni infection. | biomphalaria glabrata, highly susceptible to schistosoma mansoni, were seen to shed less and less cercariae along the time of infection. histological examination kept a close correlation with this changing pattern of cercarial shedding, turning an initial picture of no-reaction (tolerance) gradually into one of hemocyte proliferation with formation of focal encapsulating lesions around disintegrating sporocysts and cercariae, a change that became disseminated toward the 142nd day post miracidial ... | 2001 | 11500778 |
| involvement of nitric oxide in killing of schistosoma mansoni sporocysts by hemocytes from resistant biomphalaria glabrata. | in strains of the snail biomphalaria glabrata (gastropoda) that are resistant to the parasite schistosoma mansoni (trematoda), hemocytes in the hemolymph are responsible for elimination of s. mansoni sporocysts. the defensive role of reactive nitrogen species was investigated in in vitro interactions between hemocytes derived from the resistant 13-16-r1 strain of b. glabrata and the parasite. the nitric oxide synthase (nos) inhibitor n(omega)-nitro-l-arginine methylester (l-name) and the nitric ... | 2001 | 11534641 |
| larval schistosoma mansoni excretory-secretory glycoproteins (esps) bind to hemocytes of biomphalaria glabrata (gastropoda) via surface carbohydrate binding receptors. | flow cytometric analysis of circulating blood cells (hemocytes) of biomphalaria glabrata, molluscan intermediate host of schistosoma mansoni, revealed the presence of 2 overlapping hemocyte subpopulations, designated r1 and r2. r1 hemocytes are characterized by their smaller size, reduced granularity, and the presence of the bgh1 surface epitope, whereas r2 cells are larger, more granulated, and generally lack the bgh1 cell marker. both hemocyte subpopulations bound fluorescent dye (oregon green ... | 2001 | 11534642 |
| axenic culture of schistosoma mansoni sporocysts in low o2 environments. | recent successes in culturing intramolluscan larval stages of schistosoma mansoni have relied on synxenic culture with a cell line (bge) developed from embryos of a molluscan host biomphalaria glabrata. to further facilitate progress toward control of schistosomiasis, a system for axenic in vitro culture of the parasite has now been developed. when culture media were preconditioned by bge cells, sporocysts lived longer in vitro and produced more offspring. because bge-derived components could be ... | 2001 | 11695386 |
| evolutionary relationships and biogeography of biomphalaria (gastropoda: planorbidae) with implications regarding its role as host of the human bloodfluke, schistosoma mansoni. | the wide geographic distribution of schistosoma mansoni, a digenetic trematode and parasite of humans, is determined by the occurrence of its intermediate hosts, freshwater snails of the genus biomphalaria (preston 1910). we present phylogenetic analyses of 23 species of biomphalaria, 16 neotropical and seven african, including the most important schistosome hosts, using partial mitochondrial ribosomal 16s and complete nuclear ribosomal its1 and its2 nucleotide sequences. a dramatically better r ... | 2001 | 11719572 |
| 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 |
| 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 |
| biological characteristics of praziquantel-resistant and -susceptible isolates of schistosoma mansoni. | if there is a change in the biological characteristics of schistosomes associated with the development of resistance to praziquantel, this could affect the transmission and pathology of the diseases they cause. to investigate this possibility, the host-parasite relationships of five praziquantel-resistant and five praziquantel-susceptible isolates of schistosoma mansoni were compared in biomphalaria glabrata snails and outbred cd(1) albino mice. whether praziquantel-resistant or -susceptible, al ... | 2001 | 11784425 |
| 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 |
| fine-scale population structure and dispersal in biomphalaria glabrata, the intermediate snail host of schistosoma mansoni, in venezuela. | biomphalaria glabrata is the main intermediate host of schistosoma mansoni in america and one of the most intensely studied species of freshwater snails, yet very little is known about its population biology. here, we used seven highly polymorphic microsatellite loci to analyse genetic diversity in the valencia lake basin, which represents the core of the endemic area for schistosomiasis in venezuela. populations were sampled at short spatial scale (a few kilometres), both inside the lake and in ... | 2002 | 11975704 |
| [influence of hydrocortisone on schistosoma mansoni development in biomphalaria glabrata]. | the effect of hydrocortisone on the development of bh strain of s. mansoni in b. glabrata snails is evaluated. snails in a randomly chosen group were submitted to hydrocortisone during four days. in the second day of hydrocortisone exposure, the snails were exposed, each, to ten s. mansoni miracidia. another group, not treated with hydrocortisone, was exposed to miracidia and observed in the same manner. various items of data were observed: the infection rate, survival time, prepatent period and ... | 2002 | 12011923 |
| interaction between the intermediate host of schistosomiasis in brazil biomphalaria glabrata (planorbidae) and a possible competitor melanoides tuberculata (thiaridae): i. laboratory experiments. | the biological control of biomphalaria glabrata, intermediate host of schistosoma mansoni, is one the accepted options to fight schistosomiasis. one of the most promising candidates to control b. glabrata is the snail melanoides tuberculata, a potential competitor. however, the mechanisms of interaction between the two species are not clear. our objective is to determine if m. tuberculata indeed compete with b. glabrata, using two laboratory experiments. in experiment 1, we tested the effect of ... | 2002 | 12048567 |
| schistosoma mansoni sporocysts in culture: host plasma hemoglobin contributes to in vitro oxidative stress. | the initiation and promotion of sporocyst propagation and subsequent production of cercariae by intramolluscan larval stages of digenic trematodes are thought to depend on mollusc-derived factors. the ability to investigate this using in vitro cultures of schistosoma mansoni sporocysts has been impeded by the fact that plasma from the host, biomphalaria glabrata, becomes toxic to the parasite in long-term cultures. the present study identifies hemoglobin as the plasma component responsible for t ... | 2002 | 12053954 |
| distribution of schistosome infections in molluscan hosts at different levels of parasite prevalence. | biomphalaria glabrata snails infected with schistosoma mansoni were collected during consecutive seasons from a site in brazil known to have a very high percentage of infected snails. schistosoma mansoni cercariae from single snails were used to infect individual mice, and the recovered adult worms were genetically assessed using a mtvntr marker. the number of unique parasite genotypes found per snail was compared to expected abundance values, based on the infection prevalence at the site, to de ... | 2002 | 12053991 |
| genetic variability of the main intermediate host of the schistosoma mansoni in brazil, biomphalaria glabrata (gastropoda: planorbidae) assessed by ssr-pcr. | the genetic variability of brazilian biomphalaria glabrata populations was studied using ssr-pcr. this technique is a variant of the polymerase chain reaction (pcr), which consists of using a single primer directed towards microsatellite regions under high stringency reaction conditions. twenty snails of each population from eight distant brazilian localities were analyzed. morphology and pcr-rflp were used for previous specific identification of the snails. bands generated after gel electrophor ... | 2002 | 12062789 |
| 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 |
| molluscicidal activity of plants from puerto rico. | overall, 173 tropical plants from 72 different families, collected from the north-western and western regions of puerto rico, were screened for their molluscicidal properties against biomphalaria glabrata, the intermediate host of schistosoma mansoni. six plant extracts were effective at 50 ppm. the two most effective extracts were those from the leaves of didymopanax morototoni (araliaceae) and mammea americana (guttiferae), which, at 50 ppm, killed all snails after 24 h of exposure and a day f ... | 2002 | 12080983 |
| 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 |
| 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 |
| 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 |