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PubMed1978

[Data on the life cycle of Ribeiroia marini guadeloupensis n. ssp., a trematode sterilizing Biomphalaria glabrata in Guadeloupe].

Data on the life cycle of Ribeiroia marini guadeloupensis n.ssp., Trematode sterilizing Biomphalaria glabrata in Guadeloupe. Maintenance of the life cycle with a view to an eventual control of the populations of Molluscs. In Guadeloupe (French West Indies), the definitive hosts of Ribeiroia marini guadeloupensis n.ssp. are the two species of rats: Rattus rattus and R. norvegicus. The first intermediate host is Biomphalaria glabrata, the vector of intestinal schistosomiasis. The second intermediate host is a fish (Tilapia mossambica, Poecilia reticulata). The different stages of the life cycle are described; the transmission is studied experimentally and in natural conditions. A method for producing eggs of this Trematode in large quantities is described.

Animals↗
PubMed1975

Intraspecific variations in the hemolymph of Biomphalaria glabrata, a snail host of Schistosoma mansoni.

An attempt was made to characterize the hemolymph of Biomphalaria glabrata with reference to "normal" intra-specific variation, i.e., both inter- and intra-strain differences. Total protein concentration, per cent hemoglobin, pH, and osmolarity were studied. Seven geographic strains of B, glabrata were examined. In addition, observations were made on the hemolymph of Biomphalaria straminea, several strains of Helisoma caribaeum, and on B. glabrata subjected to infection with Schistosoma mansoni or to periods of starvation. Intra-strain differences in total protein concentration and total hemoglobin concentration in B. glabrata appeared to be more closely related with snail size than with absolute age. Inter-strain variation in B. glabrata was also noted, but the differences were of the same magnitude as those from intra-strain samples. Significant differences in total protein concentration were observed, however, between the means of similar size B. glabrata, B. straminea and H. caribaeum. The osmolatity of the hemolymph from different size B. glabrata was similar as were the osmolalities of the hemolymph from similar size snails of different strains. However, all B. glabrata strains exhibited hemolymph osmolalities lower than observed in strains of H. caribaeum. Infection with S. mansoni reduced the protein concentration of B. glabrata hemolymph. Differences were noted as early as 1.5-24 hr post-infection, with significant alterations occurring at about 11 days post-infection. To a lesser extent, starvation also depleted the protein content of the hemolymph.

Animals↗
PubMed1982

Elimination of Biomphalaria pfeifferi, Bulinus tropicus and Lymnaea natalensis by the ampullarid snail, Marisa cornuarietis, in a man-made dam in northern Tanzania.

Marisa cornuarietis is a well known ampullarid competitor/predator of Biomphalaria glabrata in Puerto Rico. For the first time in Africa a flourishing population of Marisa has been established in a small, permanent, man-made dam at Kisangara, near Moshi, Tanzania. Prior to the release of M. cornuarietis in June 1977, this dam supported thriving populations of the pulmonate snail hosts Biomphalaria pfeifferi and Lymnaea natalensis; Bulinus tropicus and the melaniid Melanoides tuberculata were also common. Some 24 months after the establishment of Marisa the three pulmonate species had been eliminated; only M. tuberculata remained at about the same population density as originally recorded. Marisa has not caused any obvious adverse environmental impact in the dam. There is at present no valid evidence that this ampullarid would be a threat to local rice production, which is the only crop at risk, but carefully designed field trials should be undertaken to confirm or refute this view. In view of the vast number of permanent, lentic habitats throughout the Afrotropical region, which act as important transmission sites of schistosomiasis and fascioliasis, the role of Marisa cornuarietis as a cost-effective biological control agent in integrated control operations deserves henceforth to be energetically explored.

Animals↗
PubMed1978

Ecological studies in Madagascar of Biomphalaria pfeifferi, intermediate host of Schistosoma mansoni. 2. Biology and dynamics in the non-endemic area of Antananarivo.

The region of Antananarivo, where Schistosomiasis is not yet endemic, is compared to Ambositra, a well established focus of S. mansoni, with regard to climate, hydrology and snail habitats. Higher mean temperatures and a more pronounced dry season in Antananarivo contribute to sometimes less favourable hydrological conditions. Biomphalaria is found in very few and limited habitats. Population dynamics were followed up in selected habitats and showed ecological parameters comparable to those of the Ambositra-strain. Trematode infections were very scarce. Both strains of Biomphalaria are equally susceptible to infections with the malagasy strain of S. mansoni (up to 100 p. 100). Mortality rates, prepatency periods and the electrophoretic pattern of egg proteins are very similar. Foreign snail species like B. glabrata (albino strain) and B. pfeifferi (South African strain) are hardly susceptible to malagasy S. mansoni. Some cases of S. mansoni-infections are mentioned, which presumably had been contracted in non-endemic areas of the province of Antananarivo. The possibility and risk of implantation of schistosomiasis in this region and in the town is evaluated following the discussion of epidemiological details. The author concludes that in spite of some unfavourable conditions for S. mansoni the establishment of the cycle can locally not be excluded. Attention is all the more important, as control of endemic schistosomiasis would be particularly difficult under malagasy conditions of geography, climate, snail dynamics and human behaviour.

Adult↗
PubMed1995

Experimental infection of juvenile Biomphalaria glabrata with cercariae of Echinostoma trivolvis.

Infectivity studies were done on laboratory-reared Biomphalaria glabrata juvenile (neonatal) snails exposed to cercariae of Echinostoma trivolvis. Of the 40 snails, 0.7-1.0 mm in shell diameter, which were exposed to a total of 1,000 cercariae for 24 hr, all were infected with 1-29 viable encysted metacercariae per snail. Biomphalaria glabrata, 1-2 mm in shell diameter, were used to determine the effects of an infectious dose of 25 cercariae/juvenile on subsequent snail survival. The median survival time of 24 exposed snails occurred between day 3 and 4 postinfection, at which time more than 90% of 24 control (unexposed) snails were alive. The high mortality in the E. trivolvis-infected B. glabrata juveniles was probably related to cercarial penetration and encystment in the snail tissue, although histological examination of snails after exposure would be required to determine the actual cause of the observed mortality.

Animals↗
PubMed1978

Immunodiffusion studies on Schistosoma mansoni and its intermediate host stage specific antigens. 3. Immunoelectrophoresis cross-reactions between S. mansoni stages and Biomphalaria sp. hepato-pancreas antigens.

IMMUNOELECTROPHORESIS was applied for cross-wise checking of the different stages in the life cycle of schistosoma mansoni with extracts of hepato-pancreas from its intermediate host snails Biomphalaria glabrata and Biomphalaria alexandrina. Only few fractions were common to non infected snail organ and parasite development stage, while more crossreactions were detected with infected snail hepato - pancreas.

Animals↗
PubMed1993

Ecology of Biomphalaria alexandrina the snail vector of Schistosoma mansoni in Egypt.

The patterns of spreading and seasonal variation of population density of Biomphalaria alexandrina, the snail vector of Schistosoma mansoni in Egypt, in correlation with some environmental parameters were studied for 1988-1990 in four irrigation canals in Giza and Qalyoubiya Governorates. Results shown that the spreading patterns of snails along canals are changeable because of water current and irrigation activities. The snail population density showed two peaks, different in height, in April-May and November-December separated by two bottoms following the Winter Closure and during the hot summer season. The height of the peaks appears to be dependent on the extent of the "Winter Closure" and the prevailing water temperature. Two snail sampling tools, the dip-net and drag scoop, were used concurrently in this study. No considerable difference in sampling efficacy was recognized between these tools in the case of Biomphalaria. However, the dip-net appears to be more efficient in sampling other pulmonates while the drag scoop is more efficient in sampling prosobranchs. It is also realized that double sampling of 50% of sampling sites the next day should be satisfactory as a quality control system in snail population studies.

Animals↗
PubMed1996

Biomphalaria glabrata: a new threat for schistosomiasis transmission in Egypt.

This is the first report on the infestation of irrigation and drainage systems at Giza, Qalyoubiya and Kafr El Shiekh Governorates, with Biomphalaria glabrata (the snail host of Schistosoma mansoni in the new world). Identification of this snail species was based on morphometry of the shell, shape of the radular lateral teeth and presence of the characteristic renal ridge. B. glabrata snails collected from natural water courses in Egypt proved to be susceptible to a local strain of S. mansoni. These snails were infected by 52% versus 75% for Biomphalaria alexandrina (the only local host) under the same laboratory conditions. Meanwhile the periodic total cercarial production was higher in B. glabrata than in B. alexandrina (252 +/- 110 cercariae/snail versus 203 +/- 86 cercariae/snail, respectively). Differences in infection rate, length of schistosome incubation period, duration of cercarial shedding and cercarial production in various sizes of the two snail species are reported and discussed.

Animals↗
PubMed1996

Fate of Schistosoma mansoni in Biomphalaria obstructa.

Histological sections of Biomphalaria obstructa snails exposed to miracidia of Schistosoma mansoni revealed that although viable sporocysts occurred in 6 of 9 snails at 3 days postexposure (DPE), all were dead by 7 DPE. Most dead sporocysts appeared to have degenerated slowly rather than having been killed by host hemocytic responses, which were minimal. What appeared to be amorphous remnants of sporocysts could still be found at 31 DPE. In 7 of 10 snails infected simultaneously with S. mansoni and Echinostoma paraensei, viable schistosome sporocysts occurred at 7 DPE, possibly as a result of interference with hemocyte function by the echinostome. However, in snails exposed to E. paraensei 48 hr prior to S. mansoni, no viable schistosome sporocysts were found at 7 DPE. Biomphalaria obstructa may be only temporarily susceptible to infection with E. paraensei, rediae of which undergo degeneration, hemocyte-mediated destruction, or both by 7-9 DPE.

Animals↗
PubMed1997

PCR amplification of the mitochondrial DNA minisatellite region to detect Schistosoma mansoni infection in Biomphalaria glabrata snails.

Schistosoma infection in Biomphalaria glabrata can be detected by either exposing snails to light to induce cercarial shedding or by squeezing them between glass slides to detect parasites in the digestive gland and other regions. The methods available are inefficient for identification of prepatent infections and do not allow the diagnosis of infection in snails that die before arriving in the laboratory. Furthermore, infection is undetectable after migration of sporocysts from the head-foot region of the snail. We examined the use of polymerase chain reaction (PCR) amplification of minisatellite repeats from Schistosoma mansoni mitochondrial DNA (mtDNA) to identify snail infection. We found that amplification of mtDNA under low stringency conditions (LS-PCR) allowed for the identification of specific S. mansoni infection in Biomphalaria snails. To confirm these results, specific amplification reactions were performed using 2 sets of primers that allowed for the diagnosis of infection and an internal control of the reaction (multiplex PCR). Results obtained using multiplex PCR demonstrated the ability of the assay to detect S. mansoni-specific infection. Thus, LS-PCR as well as specific multiplex PCR allow for the detection of prepatent infections and show high specificity for S. mansoni in comparison with other trematode infections in either living or dead snails.

Animals↗
PubMed1997

Effect of the plant Azolla pinnata on survival, growth rate, fecundity and hatchability of egg-masses of Biomphalaria alexandrina snails.

Data indicated that Azolla pinnata plants variously reduce the growth rate of Biomphalaria alexandrina snails expressed as net increase in shell diameter (direct or indirect exposure). The plant density played an important role in this respect. The higher the plant density was the lower the growth rate and vice versa. Too, indirect exposure of newly hatched B. alexandrina resulted from exposed treated eggs reduced the growth rate of these snails. Data revealed that direct and/or indirect exposure to the abnormal high density (50,000 plants/L) resulted in complete kill of B. alexandrina snails after two weeks from continuous exposure. Snails exposed directly to Azolla at 50,000 and 25,000 plants/L failed to lay eggs. On the other hand, sanils exposed to 10,000 plants/L laid few eggs, resulted in low reproductive rate (57.94) compared with unexposed ones (110.6). The same trend of results was recorded with hatchability of Biomphalaria eggs.

Animals↗
PubMed1998

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 cultivation with Bge cells. Histological analysis showed that the development of MS in B. glabrata was similar to the previously described development in Biomphalaria pfeifferi in terms of final site of infection, development dynamics, growth dynamics, reproduction intensity, and life spans. Only short delays in migration dynamics were observed in B. glabrata. When cultivated under in vitro conditions, E. caproni MS could live for up to 17 wk in the presence of Bge cells, as compared with 2 wk in cell-free Bge medium. The presence of Bge cells also permitted significant growth of MS and development through complete embryogenesis of the next intramolluscan stage (embryos of 100-110 cells). However, degeneration of MS consistently occurred before production of this second generation. During the entire cultivation period, no visible contact was observed between MS and Bge cells, suggesting that development of MS was only triggered by soluble factors released by Bge cells.

Animals↗
PubMed1999

Impact of geographical origin on mating behaviour in two species of Biomphalaria (Planorbidae: Gastropoda).

Studies of inbreeding and outcrossing have traditionally concentrated on matings within populations. The influence of geographical origin on mate choice in animals from different populations has received less attention. We investigated whether planorbid snails mated preferentially within their own population or with snails from other populations. Snails from three Biomphalaria pfeifferi strains and three B. glabrata strains were allowed to mate with conspecifics in the laboratory. We recorded their matings at night using time-lapse video. When they could choose between sympatric and allopatric snails, Biomphalaria snails significantly preferred the former: snails of each population mated more often with sympatric than with allopatric snails. This tendency to avoid outcrossing may indicate that, in some species, local adaptations can be more valuable than genetic novelties. Copyright 1999 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1998

Characterization of the myoglobin and its coding gene of the mollusc Biomphalaria glabrata.

A cDNA clone isolated from a Biomphalaria glabrata (Mollusca, Gastropoda) neural cDNA library was identified as encoding a myoglobin-like protein of 148 amino acids with a single domain and a calculated mass of 16,049.29. Alignment with globin sequences with known tertiary structure confirms its overall globin nature. The expressed myoglobin was identified in the radular muscle and isolated. Oxygen equilibrium measurements on the protein reveal a high oxygen affinity. Val-B10 and Gln-E7, important residues for the determination of the oxygen affinity, are strikingly different from the standard molluscan pattern (Conti, E., Moser, C., Rizzi, M., Mattevi, A., Lionetti, C., Coda, A., Ascenzi, P., Brunori, M., Bolognesi, M. (1993) J. Mol. Biol. 233, 498-508). The single gene encoding the globin chain is interrupted by three introns at positions A3.2, B12.2, and G7.0. Comparison with other nonvertebrate globin genes reveals on the one hand conservation (B12.2 and G7.0) and on the other hand variability of the insertion positions (A3.2). The Biomphalaria myoglobin sequence was used together with all other molluscan globin sequences available to assess the origin and phylogeny of the phylum. Our results confirm the doubts raised about monophyletic origin of the Mollusca, which was first observed using SSU rRNA as a molecular marker.

Amino Acid Sequence↗
PubMedDate not supplied

Effects of restricted food intake on neutral lipid and free fatty acid levels in the digestive gland-gonad complex and faeces of Biomphalaria glabrata (Gastropoda).

High-performance thin-layer chromatography (HPTLC) was used to determine neutral lipids and free fatty acids in the digestive gland-gonad complex (DGG) and faeces of Biomphalaria glabrata. Three populations of B. glabrata were given varying food intakes for one week. They were either unrestricted (lettuce ad libitum plus a weekly feeding of Tetramin), restricted (15-17 mg of lettuce every two days), or starved (no food). Samples were prepared by extraction in chloroform:methanol (2:1), followed by a Folch wash (0.88% aqueous KCl). The major lipids detected in the DGG were triacylglycerols, free fatty acids and free sterols. Free fatty acids and free sterols were the major lipids detected in the snail faeces. Analysis by TLC-densitometry showed a statistically significant difference in the DGG levels of triacylglycerols and free sterols between the unrestricted and restricted groups, as well as between unrestricted and starved groups. Analysis of faecal samples revealed a significant difference in free fatty acids between unrestricted and starved groups on the seventh day.

Animals↗
PubMed2000

Calcium carbonate modifications in the mineralized shell of the freshwater snail Biomphalaria glabrata.

The mineralized shell (consisting of calcium carbonate) of the tropical freshwater snail Biomphalaria glabrata was investigated with high resolution synchrotron X-ray powder diffractometry and X-ray absorption spectroscopy (EXAFS). Parts from different locations of the snail shell were taken from animals of different age grown under various keeping conditions. Additionally, eggs with ages of 60, 72, 120, and 140 hours were examined. Traces of aragonite were found as first crystalline phase in 120 h old eggs, however, Ca K-edge EXAFS indicated the presence of aragonitic structures already in the X-ray amorphous sample of 72 h age. The main component of the shell of adult animals was aragonite in all cases, but in some cases minor amounts of vaterite (below 1.5%) are formed. The content of vaterite is generally low in the oldest part of the shell (the center) and increases towards the mineralizing zone (the shell margin). In juvenile snails, almost no vaterite was detectable in any part of the shell.

Aging↗
PubMed2003

Small angle x-ray scattering of the hemoglobin from Biomphalaria glabrata.

The hemoglobin from Biomphalaria glabrata is an extracellular respiratory protein of high molecular mass composed by subunits of 360 kDa, each one containing two 180 kDa chains linked by disulfide bridges. In this work, small angle x-ray scattering (SAXS) measurements were performed with the hemoglobin at pH 5.0 and 7.5. Radii of gyration of 98.6 +/- 0.5 and 101.8 +/- 0.2 A and maximum diameters of 300 +/- 10 and 305 +/- 10 A, respectively, were obtained from Guinier plot extrapolation and analytical curve fitting. The pair distance distribution functions p(r) corresponded to globular particles with a somewhat anisotropic shape for both preparations. Computer analysis of the low angle part of the scattering curve led to the determination of the low resolution envelope of the protein, revealing a P(222) symmetry. Shape reconstruction from ab initio calculations using the complete scattering curve furnished a compact prolate three-dimensional (3D) bead model for the protein. Hydrodynamic parameters were obtained from experiments and theoretical calculations using the 3D model. The results of the structural and biochemical studies reported herein indicate that the multisubunit structure of this hemoglobin is compatible with a tetrameric arrangement.

Animals↗
PubMed1990

Humoral response of the snail Biomphalaria glabrata to trematode infection: observations on a circulating hemagglutinin.

The hemolymph of invertebrates often contains molecules that agglutinate vertebrate erythrocytes and that may function as humoral mediators of "non-self" recognition. The objectives of this study were to 1) determine if exposure of M line or 10-R2 strain Biomphalaria glabrata snails to infection with the trematodes Echinostoma paraensei and Schistosoma mansoni could increase agglutinating activity in snail hemolymph, and 2) identify particular hemolymph molecules with such activity. In some host-parasite combinations, such as juvenile M line snails and E. paraensei, infection provoked significant elevations in titer from as early as 2 days postinfection (dpi) through 15 dpi. In other combinations, as with 10-R2 snails and E. paraensei or S. mansoni, host responses were comparatively modest, yet still measurable. In general, E. paraensei and S. mansoni elicited different responses from the same host strain, and M line and 10-R2 snails responded differently to the same parasite. Further study of the response of juvenile M line snails to E. paraensei indicated that hemolymph agglutinating activity could be inhibited by several monosaccharides (including L-fucose) and by EDTA and EGTA. An affinity column containing L-fucose agarose beads was used to purify molecules with agglutinating activity from the hemolymph of such snails. The fraction eluted from the column by 0.2 M L-fucose was shown by SDS-PAGE to contain a broad band of 80-120 kD and, less consistently, a 200 kD band. Following extensive dialysis to remove L-fucose, this fraction had agglutinating activity. As a previous study has shown that the hemolymph of E. paraensei-infected snails contains significantly increased quantities of 80-120 kD polypeptides, it is concluded that polypeptides in this size range are responsible, at least in part, for the increased hemolymph agglutination activity in such snails.

Animals↗