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PubMed1979

Bacterial flora of the schistosome vector snail Biomphalaria glabrata.

The aerobic heterotrophic bacterial flora in over 200 individuals from 10 wild populations and 3 laboratory colonies of the schistosome vector snail Biomphalaria glabrata was examined. Internal bacterial densities were inversely proportional to snail size and were higher in stressed and laboratory-reared snails. The numerically predominant bacterial genera in individual snails included Pseudomonas, Acinetobacter, Aeromonas, Vibrio, and several members of the Enterobacteriaceae. Enterobacteriaceae seldom predominated in laboratory colonies. Our data suggest that Vibrio extorquens and a Pasteurella sp. tend to predominate in high-bacterial-density snails. These snails may be compromised and may harbor opportunistic snail pathogens.

Aerobiosis↗
PubMed2003

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, which at present lags far behind work being carried out with vertebrate and arthropod models. B. glabrata in particular, which has one of the smallest known gastropod genomes, is recommended as a highly suitable target for future genome sequencing.

Animals↗
PubMed1980

Experimental pathogenicity of Vibrio parahaemolyticus for the schistosome-bearing snail Biomphalaria glabrata.

The bacterium Vibrio parahaemolyticus was found to be pathogenic for the schistosome intermediate host Biomphalaria glabrata (Say). When administered topically, a nonenteritis-associated strain of the bacterium had an LD50 (median lethal dose) of 6.8 x 10(7) cells per snail. A 5% trichloroacetic acid (TCA) extract from V. parahaemolyticus was found to kill B. glabrata. Sublethal effects of V. parahaemolyticus include shell deterioration and increased heart rate. Both albino aquarium populations and naturally occurring Puerto Rican wild populations of B. glabrata are susceptible to V. parahaemolyticus. This bacterium provides a useful model for the study of pathogens and biological control of schistosome vector snails, since it causes significant mortality and is recognized as a pathogen of other invertebrates.

Animals↗
PubMed1999

Oxygen binding and its allosteric control in hemoglobin of the pulmonate snail, Biomphalaria glabrata.

Pulmonate snails that experience extreme variations in gas tensions and temperatures possess extracellular, high-molecular mass ( approximately 1.7 x 10(6) Da) hemoglobins (Hbs) that are little known as regards oxygenation and allosteric characteristics. Biomphalaria glabrata hemolymph exhibits a high O2 affinity (half-saturation O2 tension = 6.1 mmHg; pH 7.7, 25 degreesC), pronounced Bohr effect (Bohr factor = -0.5), and pH-dependent cooperativity (Hill's cooperativity coefficient at half-saturation = 1.1-2.0). Divalent cations increase O2 affinity, Ca2+ exerting greater effect than Mg2+. Analyses in terms of the Monod-Wyman-Changeux model indicate novel O2 affinity control mechanisms. In contrast to vertebrate Hb, where organic phosphates and protons lower affinity via decreased O2 association equilibrium constant of Hb in low-affinity state (KT), and to extracellular annelid Hbs, where protons and cations primarily modulate O2 association equilibrium constant of Hb in high-affinity state (KR), in B. glabrata Hb, the Bohr effect is mediated predominantly via KR and the cation effect via KT, reflecting preferential, oxygenation-linked proton binding to oxygenated Hb and cation binding to deoxygenated Hb. CO2 has no specific (pH independent) effect. Nonlinear van't Hoff plots show temperature dependence of the overall heats of oxygenation, indicating oxy-deoxy heat capacity differences. The findings are related to possible physiological significance in pond habitats.

Allosteric Regulation↗
PubMed1975

The cytochemical localization of succinic dehydrogenase in the sperm mitochondria of the gastropod Biomphalaria glabrata. A comparison of two methods.

The mitochondrial derivative of the sperm of the gastropod pulmonate Biomphalaria glabrata was studies to ascertain succinic dehydrogenase localization cytochemically. Two techniques were compared. One technique depends on a tetrazolium salt that yields an osmiophilic formazan upon reduction. The other technique is dependent on the reduction of copper ferricyanide. The effects of several electron transport inhibitors were studied. The reaction product observed in the matrix of the mitochondrial derivative using the former technique is sensitive to rotenone and is believed to be nicotinamide adenine dinucleotide-dependent. The reaction product observed in the intracristal spaces using the copper ferricyanide method is insensitive to rotenone and is believed to cytochemically demonstrate succinic dehydrogenase in this material.

Animals↗
PubMed2005

Experimental control of Biomphalaria pfeifferi, the intermediate host of Schistosoma mansoni, by the ampullariid snail Lanistes varicus.

The biological control of the snail hosts of the trematodes that cause human schistosomiasis appears to be a promising method for achieving sustainable reductions in the transmission of the parasites. The possibility of using the Ghanaian strain of an ampullariid snail, Lanistes varicus, for the biological control of the main snail host of Schistosoma mansoni , Biomphalaria pfeifferi, has now been investigated in laboratory-based experiments. Adult and 2-week-old L. varicus were found to feed voraciously on the egg masses and juveniles of B. pfeifferi (from the Tono irrigation canals in northern Ghana). When single L. varicus were exposed to 20-200 egg masses, they consumed all of the masses over 24 h (if adult) or about 50% of them over 4 days (if 2-week-old juveniles). The effect of the secretions of the ampullariid on the reproduction, growth and mortality of B. pfeifferi was also investigated, by maintaining the two snail species in the same aquarium but separated by nylon netting. The presence of L. varicus in the same aquarium reduced the number of egg masses produced by each B. pfeifferi, although, curiously, the presence of a single L. varicus in the aquarium appeared to have more of an impact, on the egg-mass deposition by 20 B. pfeifferi, than the presence of five or more of the ampullariids. It appears that, under laboratory conditions at least, the Ghanaian stain of L. varicus has the potential to limit populations of B. pfeifferi.

Animals↗
PubMed2005

Molluscicidal activity of some Brazilian Solanum spp. (Solanaceae) against Biomphalaria glabrata.

Plants in the genus Solanum (Solanaceae) produce a great variety of steroidal saponins and glycoalkaloids that confer natural resistance against several pests. Methanolic extracts of 13 Solanum species have now been tested for molluscicidal activity against Biomphalaria glabrata. The extracts investigated were prepared from the fruit of S. asperum, S. capsicoides, S. palinacantum, S. paludosum, S. paniculatum, S. paraibanum and S. sisymbriifolium, the aerial parts of S. asperum, S. capsicoides, S. crinitum, S. diamantinense, S. megalonyx, S. palinacantum, S. paniculatum, S. sisymbriifolium and S. torvum, and the roots of S. asperum, S. asterophorum, S. palinacantum, S. paludosum, S. paniculatum and S. stipulaceum. Encouragingly, the extracts from S. asperum, S. diamantinese, S. paludosum, S. sisymbriifolium and S. stipulaceum showed significant molluscicidal activity, the median lethal concentrations recorded (20-50 microg/ml) falling well below the threshold, of 100 microg/ml, set for a potential molluscicide by the World Health Organization.

Animals↗
PubMed2026

Epigenetic and metabolic reprogramming of innate immune cells establishes immunological memory in the Schistosomiasis vector snail Biomphalaria glabrata.

Innate immune memory enables non-vertebrates to mount faster and more effective immune responses upon re-exposure to a previously encountered pathogen, yet its cellular and molecular bases remain poorly understood. The freshwater snail Biomphalaria glabrata, intermediate host of the human parasite Schistosoma mansoni, provides a powerful model to investigate this phenomenon. Here, we show that innate immune memory in B. glabrata is carried by hemocytes and relies on profound metabolic and epigenetic reprogramming initiated during primary infection. Using an integrative multi-omics approach combining transcriptomics, chromatin accessibility profiling, whole-genome bisulfite sequencing and targeted metabolomics, we reveal that the first parasite encounter induces a stable rewiring of hemocyte metabolism and chromatin landscape. This reprogramming primes hemocytes for a massive and rapid transcriptional response upon secondary challenge, characterized by an immune shift toward highly specific humoral effector pathways. Metabolic analyses demonstrate an early switch toward aerobic glycolysis, altered tricarboxylic acid cycle activity and amino acid metabolism, consistent with a Warburg-like metabolic state previously described in vertebrate trained immunity. Notably, metabolic and epigenetic remodeling occurs primarily during the primary infection and remains stable upon secondary exposure, suggesting that immune memory is encoded prior to pathogen re-encounter. Together, our results identify conserved metabolic and epigenetic mechanisms underlying innate immune memory in a non-vertebrate host and provide direct evidence that hemocyte-mediated innate immune memory in B. glabrata shares core features with trained immunity described in vertebrates.

Animals↗
PubMed1989

[Estivation of Biomphalaria tenagophila (Pulmonata, Planorbidae)].

This study reports the finding of Biomphalaria tenagophila naturally aestived in two municipalities of the State of S. Paulo (Brazil): Ubatuba and Conchas. This ethological characteristic was discovered in 15 specimens collected in Ubatuba, and in 6 specimens collected in Conchas. The snails aestived showed vitality after being placed in water.

Adaptation, Physiological↗
PubMed1989

[Distribution of Biomphalaria tenagophila and B. occidentalis in the State of São Paulo (Brazil)].

The geographical distribution of Biomphalaria tenagophila (d'Orbigny, 1835) and B. occidentalis Paraense, 1981 in S. Paulo State, Brazil, is described. The first species being the most important intermediate host of Schistosoma mansoni Sambon, 1907. The second species is unsusceptible to transmission. The two species inhabit the limnic environments of great areas of S. Paulo, occasionally in simpatria. The 3,160 samples of mollusks collected between September 1981 and March 1986 were examined. B. tenagophila were identified in 1,062 of these samples from 203 municipalities and B. occidentalis in 255 samples from 97 municipalities. Biogeographical circumstances related to the distribution of the planorbids species are commented on.

Animals↗
PubMed1991

[Miracidial attraction by Biomphalaria straminea, Lymnaea columella and Physa sp on miracidia of Schistosoma mansoni BH strain].

The attraction exercised over Schistosoma mansoni miracidia by Biomphalaria straminea, Lymnaea columella and Physa sp using a specially designed apparatus consisting of two circular glass chambers joined by an open channel were studied. The molluscs or their snail-conditioned water (SCW) was placed in one of the chambers (randomly chosen). In the channel ten miracidia was deposited and the count of miracidia in each of the three compartments (the two chambers and the channel) was recorded during fifteen minutes. Ten replications of each experiment with different specimens of molluscs and miracidia were made. Statistical and ad-hoc exploratory data analysis showed that: a) the three species of molluscs and their SCW attract the miracidia; b) Physa sp attract more miracidia then L. columella. There was an isolated single B. straminea specimen that had a repulsive effect to the miracidia.

Animals↗
PubMed1993

[Immunologic and parasitologic aspects of Biomphalaria tenagophila infected by Schistosoma mansoni and other Digenea].

The behavior of Biomphalaria tenagophila amoebocytes was studied in infections produced by Schistosoma mansoni and other Digenea. The resistance to superinfection was also verified in mixed infections. Data on amoebocyte phagocytic activity, on the number of amoebocytes in hemolymph, and on amoebocyte tissue reactions were obtained and electrophoretic and immunodiffusion examinations of the hemolymph were carried out. It was concluded that the snails infected with Digenea show resistance to superinfection with S. mansoni. Apparently sporocysts are not destroyed by the action of amoebocytes. An increase in amoebocyte phagocytic activity was discovered in infected snails. Immunoelectrophoresis shows quantitative and qualitative differences in the hemolymph of the infected snails.

Animals↗
PubMed1996

[Distribution of Biomphalaria straminae in the southern neotropical region of Brazil].

A careful anatomical revision of 10,616 preserved specimens of snails from 76 localities of the State of S. Paulo, Brazil, was made with a view better to determining the geographical distribution of Biomphalaria straminea in the Neotropical Region of Southern Brazil. The analysis has shown that previous determinations were correct. The study was then complemented with a survey of information from the literature about distribution of the species. The distribution pattern of the species has expanded greatly over the last few years, perhaps an account of the construction of new dams, and the navigation system in the upper Paraná Basin. Epidemiological data have shown that B. straminea is a good host to S. mansoni. Continuous schistosomiasis control must be exercised so as to prevent the further expansion of the disease.

Animals↗
PubMed1997

Observations on the miraxonal attraction exercised by sexually immature or adult Biomphalaria glabrata infected or not by Schistosoma mansoni.

OBJECTIVE: 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. MATERIAL AND METHOD: A glass apparatus containing two compartments joined by a tube and previously tested in other experiments, was used. Specimens of B. glabrata or its snail conditioned water (SCW) selected before the first oviposition (sexually immature), after the first oviposition (adult), with or without secondary sporocysts, were used to attract the miracidia. RESULTS: It was noted that snails or their SCW containing secondary sporocysts lost the ability to attract miracidia. The sexual maturity of the snail did not influence miraxonal attraction.

Age Factors↗
PubMed1999

[First occurrence of Biomphalaria straminea in the South Goiano, Brazil].

The objective of this note is to report the occurrence of the Biomphalaria straminea in the county of Cachoeira Dourada in the south of Goiás, and with that enhance the knowledge about its geographical distribution in the state. More than identify the species, the collection of thirty samples helped study and verify the presence of cercariae, especially because they were found in a setting which offers proper conditions to the development of a focal transmission site of schistosomiasis.

Animals↗
PubMed2001

[Abundance and infection of Biomphalaria glabrata with Schistosoma glabrata in the state of Rio de Janeiro, Brazil].

OBJECTIVES: 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. METHODS: In the Pamparrão area, Sumidouro county, RJ, Brazil, snail captures were carried out every other month from June 1991 to November 1995. There were 23 collecting sites along the Pamparrão stream and its three tributaries (A, B and C). Captured snails were examined in the laboratory for infection. Data analyses were performed using Spearman coefficient (0.5% significance level) and Qui-square test. RESULTS: The abundance of B. glabrata was variable in both time and space. Most of the collection sites showed a negative correlation with rainfall. The tributary B had the highest and most steady infection rates (more than 25% in some sites). There were found significantly more infected snail in the dry season (chi2 = 20.08; p=0.001). CONCLUSIONS: B. glabrata population in the Pamparrão valley was negatively influenced by rainfall, especially at the Pamparrão stream. The dry season seems to promote the infection probably due to the lower water volume, increasing the chance of interaction between the intermediate host and the parasite.

Animals↗
PubMedDate not supplied

Schistosomiasis mansoni in the municipality of Pedro de Toledo (São Paulo, Brazil) where the Biomphalaria tenagophila is the snail host. I--Prevalence in human population.

Due to the scarce information about the epidemiological features of schistosomiasis in which the vector is Biomphalaria tenagophila, an investigation was carried in Pedro de Toledo in 1980 where such peculiarity is observed. Stool examinations (Kato-Katz method) were performed in 4,741 individuals (22.8% positive to Schistosoma mansoni eggs) of this 583 had previously received chemotherapy and 4,158 remainders, untreated. The schistosomiasis prevalence in those two groups where respectively 31.7% and 21.6%. Epidemiological investigation showed that 83.6% were autochthonous cases from the studied area: the autochthonous prevalence rate, and the intensity of infection in the untreated autochthonous cases were higher in males than in females; the intensity in the latter untreated group was low, 58.5 eggs/g feces (geometric mean). Moreover, according to the age groups the intensity of infections correlated well (rs = 0.745) with the prevalence rates. Schistosomiasis was verified to occur mostly during the leisure time and by the use of water streams for housework in rural zone. Only 0.4% out of 1,137 snails was positive for S. mansoni cercariae, apparently unchanged from the 1978 study when the human prevalence was 12.0%. The studied area presented differences and similarities in relation to the other Brazilian areas were the main intermediate host is B. glabrata.

Age Factors↗
PubMedDate not supplied

First register of Biomphalaria straminea Dunker, 1848, in Santa Catarina State.

The first register of Biomphalaria straminea, vector species of schistosomiasis, in Santa Catarina State, South Brazil is described. The specimens were obtained from two ornamental aquaria of private residences. In both cases the ornamental plants and/or fishes were bought from the same supplier. The presence of this species was later confirmed in the farm where these plants and fishes are cultivated, in the city of Governador Celso Ramos, also in Santa Catarina State. The occurrence in natural environments was later detected in two different places of the Island of Santa Catarina.

Animals↗