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PubMed1994

[Occurrence of larvae of Protostrongylidae family in terrestrial snails in the woods of Olsztyn and Silesian districts].

During the years 1992-1993 terrestrial snails were examined to the infection with larvae of Protostrongylidae family in the South and North of Poland. Using compressor method 2267 terrestrial snails from two areas (Pszczyna and Iława) were examined. Collected gastropods belonged to the following species: Arion subfuscus (45 specimens), Bradybaena fruticum (9), Cepaea nemoralis (29), Succinea putris (2147), Zonitoides nitidus (37). Larvae of three species of Protostrongylidae family were found: Elaphostrongylus cervi, Varestrongylus sagittatus and V. capreoli. The highest extensiveness of invasion of Protostrongylidae was noticed in Succinea putris and reached 23.5% in one of plots in the Iława Forest District. The highest intensity of infection was found in S. putris and was as follows: E. cervi up to 150 larvae, V. sagittatus up to 41, and V. capreoli up to 132 larvae. Besides Z. nitidus (1 specimen) there were not noticed any larvae of Protostrongylidae in other species of terrestrial snails. Average extensiveness of invasion of Protostrongylidae in 1992 and 1993 amounted to 7.2 and 9.5% in Iława, and 13.9 and 9.4% in Pszczyna, respectively. The highest percentage of infested gastropods was noticed in June and July. Similar results were obtained in both biotopes examined.

Ancylostomatoidea↗

PubMed1997

Evaluation of Bithynia funiculata snail antigens by ELISA-serodiagnosis of human opisthorchiasis.

Four batches of crude somatic antigens from: (1) Opisthorchis viverrini adult worms, (2) Bithynia funiculata-whole body, (3) B. funiculata-head-foot, and (4) B. funiculata-visceral mass were assayed against sera from 81 opisthorchiasis patients, 30 parasite-free healthy individuals, and 50 individuals infected with other helminthic infections, and their antibody levels determined. By IgG-ELISA, the antigenic reactive proteins were found in both the head-foot and the visceral mass of B. funiculata snails, but the whole snail antigens gave the best results. Furthermore, it was as good as when O. viverini antigens were used. Antibody levels of sera from patients with opisthorchiasis assayed against antigens from whole B. funiculata snails were significantly higher than those of the other two groups. The cut-off value for positivity at 0.228 gave 80.2% sensitivity and 81.2% specificity. Cross reactions were observed with sera from patients with paragonimiasis and strongyloidiasis. No cross reactions were found to occur with sera from healthy individuals.

Animals↗

PubMedDate not supplied

[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) infected by Strigeidae (0.6%), Echinostomatidae (0.2%), Clinostomatidae (-0.1%) and two unidentified cercariae; B. tenagophila (1,338), infected by Strigeidae (0.1%) and Physa marmorata (1,776) by Echinostomatidae (1.6%). The snails Biomphalaria peregrina, B. occidentalis, B. schrammi, Drepanotrema depressissimum, D. lucidum, D. cimex, Physa cubensis, Lymnaea columella, Melania tuberculata, Idiopyrgus souleyetianus, Pomacea sp, Anodontites sp and Ancylidae were found noninfected. Snails from 9 municipalities were infected by S. mansoni and from 11 by other trematodes.

Animals↗

PubMed2000

Insights into early molluscan neuronal development through studies of transmitter phenotypes in embryonic pond snails.

Pond snails have long been the subject of intense scrutiny by researchers interested in general principles of development and also cellular and molecular neurobiology. Recent work has exploited both these fields of study by examining the ontogeny of the nervous system in these animals. Much of this work has focussed upon the development of specific transmitter phenotypes to provide vignettes of neuronal subpopulations that can be traced from early embryonic life through to adulthood. While such studies have generally confirmed previous explanations of gangliogenesis in gastropods, they have also indicated the presence of several neurons that appear earlier and in positions inconsistent with classical views of gastropods neurogenesis. The earliest of these cells contain FMRFamide-related peptides and have anteriorly projections that mark the future locations of ganglia and interconnecting pathways that will comprise the postembryonic central nervous system. These posterior, peptidergic cells, as well as certain, apical, monoaminergic neurons, disappear and apparently die near the end of embryonic life. Finally, populations of what appear to be peripheral sensory neurons begin to express catecholamines by around midway through embryonic life. Like several of the neurons expressing a variety of transmitters in the developing central ganglia, the catecholaminergic peripheral cells persist into postembryonic life. Transmitter phenotypes, cell shapes and locations, and neuritic morphologies all suggest that many of the neurons observed in early embryonic pond snails have recognizable homologues across the molluscs. Such observations have profoundly altered our views of neurogenesis in gastropods over the last few years. They also suggest the promise for pond snails as fruitful models for studying the roles and mechanisms for pioneering fibres, cues triggering apoptosis, and contrasting origins and mechanisms employed for generating central vs. peripheral neurons within a single organism.

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↗

PubMed1986

A distinct lethal neonatal chondrodysplasia with snail-like pelvis: Schneckenbecken dysplasia.

We describe the clinical, radiographic, histopathologic, and ultrastructural features of a distinct neonatal lethal chondrodysplasia inherited as an autosomal recessive trait. The characteristic radiographic findings consist of flattened, hypoplastic vertebral bodies; short ribs; hypoplastic iliac bones with "a snail-like" configuration; short, broad long-bones with dumbbell-like appearance; short and wide fibula; and precocious ossification of the tarsus. Chondro-osseous histology is characteristic with hypervascularity, increased cellular density, and normal size chondrocytes with a centrally located round nucleus and absence of lacunar space. Because of the snail-like radiographic appearance of the pelvis in this disorder, we propose the name "Schneckenbecken dysplasia" (ie, German for snail pelvis).

Dwarfism↗

PubMed1991

Neuropeptide schistosomin inhibits hormonally-induced ovulation in the freshwater snail Lymnaea stagnalis.

This study examines the interaction between the caudodorsal cell hormone (CDCH) and schistosomin, a peptide secreted by the central nervous system of the snail (Lymnaea stagnalis) infected with the avian schistosome Trichobilharzia ocellata. Non-infected snails were injected with synthetic as well as native CDCH in the absence or presence of purified schistosomin. The response to 2 pmol of synthetic CDCH was blocked for 90% by coinjection with 3.5 pmol of schistosomin. The ovulation-inducing activity of extracts of cerebral commissures (the storage area of native CDCH) was also blocked by schistosomin. The degree of inhibition (65%), however, was less than that observed with synthetic CDCH. These results show that schistosomin inhibits ovulation and egg laying in Lymnaea. This explains the decrease or absence of egg laying in schistosome-infected freshwater snails.

Animals↗

PubMed2004

Polymeric controlled release formulations of niclosamide for control of Biomphalaria alexandrina, the vector snail of schistosomiasis.

Schistosomiasis is one of the most important public health problems in many developing countries. The present study was conducted to investigate the effect of the polymeric niclosamide formulations against Biomphalaria alexandrina snails, the intermediate host of Schistosoma mansoni in Egypt. Three new polymeric formulations were prepared for the molluscicide niclosamide. The formulations were prepared either by the chemical modifications of poly(glycidyl methacrylate) or by physical entrapment of the niclosamide in calcium alginate beads. The release of the niclosamide from the polymeric formulations was investigated. The activity of the prepared formulations against Biomphalaria alexandrina was investigated. The results obtained revealed higher potency for polymerized niclosamide B3 than B1; the lowest potency was revealed for B2. After an exposure period of 24 hours, LC(50) values were 0.073, 0.098 and 1.09 ppm for B3, B1 and B2, respectively. In addition, the molluscicidal potency of the test polymeric niclosamide was age-dependent, where old snails were more tolerant to the test solutions than young and newly hatched snails. The results also indicated that the molluscicidal activity of B3 was extended for 21 days and 17 days for B1, compared with 5 days for free niclosamide. However, the molluscicidal potency of the polymerized niclosamide was increased after boiling for one hour, and was increased with increasing the pH of the medium to pH 9. In addition, their potency was increased with decreasing the water hardness concentrations (CaCO(3)).Molluscicidal activity of free niclosamide and its polymeric formulations vs. exposure time.

Animals↗

PubMed2005

Effect of binary combination of some plant-derived molluscicides with MGK-264 or piperonyl butoxide on the reproduction of the snail Lymnaea acuminata.

The effects of sub-lethal treatments (20 and 60% of 24-h LC(50)) with plant-derived molluscicides Annona squamosa, acetogenins, Argemone mexicana seed and protopine, in combination (1 + 5) with MGK-264 (ENT 8184) or piperonyl butoxide on the reproduction of Lymnaea acuminata has been studied. The plant-derived molluscicides and their active molluscicidal components, protopine and acetogenins, in combination with ENT 8184 or piperonyl butoxide caused a significant reduction in the fecundity, hatchability and survival of young snails. Combination of A squamosa seed powder with piperonyl butoxide was very effective as it caused a complete arrest of snail fecundity within 24 h of treatment. Removal of the snails to fresh water after the 96-h treatments caused a significant recovery in the fecundity of L acuminata.

Acetogenins↗

PubMed1994

Schistosoma mansoni: modulation of hemocyte surface polypeptides detected in individual snails, Biomphalaria glabrata, following larval exposure.

As an approach to better understand the molecular mechanisms underlying the differential cellular response to larval Schistosoma mansoni observed in Biomphalaria glabrata, we have analyzed hemocyte membrane-associated polypeptides from inbred susceptible and resistant strains of B. glabrata. A combination of techniques involving biotin-labeling of cell surface-exposed polypeptides and a highly sensitive chemiluminescent detection technique has allowed the identification of major polypeptides expressed on nonadherent and adherent hemocyte subpopulations from individual snails and an assessment of the variability in their expression in response to S. mansoni exposure and latex bead injection. Results showed that S. mansoni exposure and latex bead injection differentially modulate the expression of 4 of 10 major hemocyte surface polypeptides with estimated molecular weights of 155/130, 120/110, 85, and 66 kDa. Little correlation was observed between the expression of any given polypeptide and a specific response to S. mansoni exposure. Moreover, the complex pattern of hemocyte surface polypeptides observed in snails subjected to the two treatments suggests that multiple signals may be influencing either the expression of these four polypeptides at the hemocyte surface or the hemodynamic of specific peptide-bearing hemocyte subpopulations released into the circulation. The fact that a natural and an artificial insult in the two snail strains elicit a differential response in the occurrence of these four polypeptides suggests that they may be involved in defense-related activities.

Animals↗

PubMed1997

Schistosoma mansoni: distribution patterns of miracidia among Biomphalaria glabrata snail as related to host susceptibility and sporocyst regulatory processes.

Parasite prevalences, miracidia developmental capacity, mother sporocyst mean intensities, sporocyst distribution patterns, and cercarial production levels were determined after individual exposure of Biomphalaria glabrata snails to increased doses of Schistosoma mansoni miracidia for two geographical strains (Brazilian, BRE, and Guadeloupean, GUA) of host and parasite. For a high level (100%) of host-parasite susceptibility and in the absence of mother sporocyst regulatory processes for the BRE combination, parasites were randomly dispersed among snail hosts with a frequency distribution conforming to a positive binomial. In contrast, for a moderate level (65%) of host-parasite susceptibility and in the presence of mother sporocyst regulatory processes for the GUA combination, parasites were overdispersed among snail hosts with a frequency distribution conforming to the negative binomial. Levels of cercarial production were found to be strain dependent, to be determined during early development of mother sporocysts, and to be correlated with the number of developed mother sporocysts. Results were analyzed in the general context of the infrapopulation dynamics of the intramolluscan stages of trematode and are discussed in terms of their consequences on the distribution of the genetic diversity of adult schistosomes among the definitive host population.

Animals↗

PubMed1999

Internal defenses of the snail Biomphalaria glabrata.

Injection of foreign particles (zymosan, latex beads, living bacteria) and substances (ferritine, horseradish peroxidase) in Biomphalaria glabrata induces the rapid appearance of tubular double-helical filaments in the hemolymph. This rapid induction may be due to the polymerization of precursor proteins of the hemolymph. Tubular helical filaments are also observed in normal snails, especially in the hemal spaces of the proximal kidney; they seem to belong to the extracellular matrix and form bundles of a few parallel units associated with fine fibrils. Hemocytes adhere to these bundles by means of the filopodia tip or by small areas of the cell surface; consequently, they may become temporarily sedentary in the hemal spaces. The deposition of helical filaments seems increased in ageing snails and in snails parasitized by Echinostoma caproni.

Animals↗

PubMed1990

Comparative glucose tolerance studies in the freshwater snail Biomphalaria glabrata: influence of starvation and infection with the trematode Schistosoma mansoni.

The dynamic reactions of B. glabrata on intravasal loads of 20-1000 micrograms glucose.g live fresh wt-1 were studied in standard fed snails (SFS). Starved snails (SS) and snails infected with S. mansoni (IS) were given 100-500 micrograms glucose.g fresh live wt-1. Mean hemolymph glucose level was 12.1 mg.100 ml-1 in SFS. It was not significantly lower in SS (10.7 mg.100 ml-1), but significantly reduced in IS (8.5 mg.100 ml-1). Since hemolymph volumes were significantly increased in SS, the amount of circulating glucose (pool) did not change (75 micrograms.g body weight-1) compared to SFS (62 micrograms.g-1). It was, however, reduced to 41 micrograms.g-1 in IS. In SFS the circulating glucose pool had to be doubled to induce significantly elimination of the injected glucose. Tripled pools were eliminated with half-times of 45 min, whereas lower and higher glucose loads were eliminated significantly slower (half-times: 80-105 min). Glucose tolerance of SS was reduced: half-times were doubled, and metabolization of injected glucose was reduced. Since tissue fresh weights were lowered by 40%, absolute incorporation of 14C from labeled glucose was lowered, but specific incorporation (per mg) was higher than in SFS and IS. Glucose tolerance of IS was increased: metabolic clearance rates rose by 70% and half-times were shortened by 30%, though absolute and specific rates of 14C incorporation were lowered. However, IS lost 25% of the label to the water, whereas SFS lost 12% and SS only lost 8%. Using the antimetabolite 2-deoxyglucose, 80% of the losses proved to be glucose in IS, and 50% in SFS. The present results suggest the existence of a glucostatic regulation in B. glabrata with lower sensitivity and capacity than in mammals. As to glucose tolerance, the often reported parallelism in metabolic shifts induced by starvation and parasitic infection was not confirmed.

Animals↗

PubMed1977

The role of Chaetogaster limnaei in the dynamics of trematode transmission in natural populations of freshwater snails.

Chaetogaster limnaei, an oligochaete was always found infesting Bulinus (Phy.) globosus, B.(B.) forskalii and Lymnaea natalensis in Bo, Sierra Leone, living below the shell or embedded in the mucus of the foot. The worms had no preference for snails with trematode infection. The population was highest in the dry season when fewer snails were infected by trematodes. This is suggested to be a result of the protection the worms give to snails against invading miracidia.

Animals↗

PubMed1980

Experimental epidemiology of schistosomiasis. I. The prepatent period and cercarial production of Schistosoma mansoni in Biomphalaria snails at various constant temperatures.

Laboratory experiments have permitted the quantification of the developmental times (prepatent periods) of Schistosoma mansoni in the snail over the whole possible range of constant temperatures. The basis relationship is satisfactorily described by a hyperbola of the formula y = 268/(x-14.2), y being the minimum time from miracidial infection to cercariae shedding (in days) x the mean temperature, and 14.2 the theoretical temperature threshold (in degrees C). Cercariae production takes place within the limits of +16 degrees C and 35 degrees C, the number of cercariae being low and the mortality of snails high at the extreme values. Long-term alternations between two temperature levels resulted in prepatent periods corresponding exactly to the proportional time-temperature products. However, slight accelerations of up to 7% and more could be observed when the prepatency began in a period of high temperature. The number of cercariae each snail shed during a period of one hour exposure per week decreased from about 1,500 at 18 degrees C to about 250 at 16 degrees C. Shedding ceased completely after 1-2 weeks at 15 degrees C.

Animals↗

PubMed1981

[Investigations on periodic phenomena in the snail Biomphalaria glabrata (author's transl)].

A method was developed to measure the locomotive activity of Biomphalaria glabrata over long periods of time. A snail, radioactively marked with a Co57-source, moves on a circular path. Beneath the experimental vessel a lead disc with a slit revolves (one revolution per minute) over a counter tube. Once every minute the amount of radioactivity emitted falls through the slit onto the counter tube. The position and thence the locomotive activity of the snail is determined from the intervals between the impulses. Under constant conditions the experiments show a distribution of crawling activity over the whole day that is the same for animals infected with Schistosoma mansoni and non-infected molluscs. The snails have more locomotive activity by day than by night, with a distinct maximum in the second hour after exposure to light. Experiments using food marked with I125-labelled fibrinogen revealed that feeding activity is three times as high at night as by day. The experiments also show that Biomphalaria glabrata tends to prefer night-time for egg laying. The results are compared with other known periodic phenomena in B. glabrata in a phase-chart.

Animals↗

PubMed2005

Seasonal transmission of Fasciola hepatica in cattle and Lymnaea (Fossaria) humilis snails in central Mexico.

A 19-month study on the prevalence of fasciolosis in 30 naturally infected cows, the presence of infected and non-infected Lymnaea (Fossaria) humilis snails, and variation in soil temperature and humidity is reported. The prevalence of fasciolosis in cattle declined from around 50% in March to 30% in July, then, it increased from August, reaching a plateau of 100% in November-January, before gradually declining thereafter. A rise in soil humidity and temperature in June and July, respectively, which peaked between August and November was observed. In July, L. (F.) humilis snails appeared, but the infection could only be found in these in August and November. The number of infected snails did not reflect the infestation rate in cows, even though the infestation kinetics in both hosts behaved as predicted from the life cycle of the parasite.

Animals↗

PubMed1999

Effects of snail-conditioned water from Biomphalaria glabrata on hatching of Echinostoma caproni miracidia.

In vitro studies were done on Echinostoma caproni eggs with fully developed miracidia to determine the effects of snail-conditioned water (SCW) from Biomphalaria glabrata on miracidial hatching in the light. Observations were made on miracidial hatching at 4, 8, 12, 16, 20, and 24 h in multiwell chambers in the presence of SCW (experimentals) versus controls in artificial spring water (ASW). The number of hatched eggs was significantly greater (Student's t-test, P<0.05) in SCW at all times as compared with those maintained in ASW. Significantly greater hatching was also obtained when snails were maintained in intact or perforated dialysis sacs in multiwell chambers as compared with sacs without snails. Agar plugs impregnated with SCW or the hydrophilic fraction of SCW that had been extracted in chloroform-methanol (2:1) did not influence significant hatching. However, the lipophilic fraction of the SCW extract caused significant hatching. Substances in SCW significantly increase hatching of E. caproni miracidia, but details on what these compounds are remain obscure.

Animals↗