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PubMed1980

Hormonal control of head-wart development in the snail, Euhadra peliomphala.

The terrestrial snail, Euhadra peliomphala, has a peculiar organ between the optic tentacles named the head-wart, which releases a sex pheromone just before courtship. The development of the head-wart was closely correlated with the sexual maturity of the snail. Castration led to the atrophy of the head-wart. Subsequent injection of hermaphrodite gland homogenate into the body cavity of castrated individuals induced the development of the head-wart. The peripheral regions of the acini in the hermaphrodite gland showed a positive reaction for 3 beta-hydroxy steroid dehydrogenase. Furthermore, preliminary radioimmunoassay also showed that the hermaphrodite gland of the snail contained testosterone and estradiol. When the immature head-wart was cultured for 10 days in a medium containing testosterone and estradiol respectively, development of the head-wart was found only in medium containing testosterone. From these results, it is concluded that head-wart development in the snail, Euhadra peliomphala, is under direct control from the hermaphrodite gland, probably by means of testosterone.

Animals↗

PubMed1995

Morphological and anatomical studies on larval trematode of genus Brachylaima (Brachylaimidae) from the land snail, Monacha obstructa.

The metacercariae of genus Brachylaima were collected from the kidney of the land snail Monacha obstructa. About thirteen to fifteen metacercariae were collected from each snail. The metacercariae observed were elongated rather than oval. The gonads were no so developed inspite of the great similarity between this larval stage and the adults. No larval stages rather than the metacercariae were observed. The specimens were examined in fresh status and then stained with carmine and fast green as counter stain. The excretory system was developed to very great extent. This seems to be the first record of this larval stage in Egypt since 1899 when Looss collected the adult of B. aequans from Gerbillus aegyptiacus. The heavy infection of snails reflects the higher incidence of this parasite among land snails as intermediate host. Since, the life cycle of this parasite is not yet confirmed experimentally in Egypt, the species has not been identified.

Animals↗

PubMed1994

Study on the life cycle of a sexually transmitted nematode parasite of a terrestrial snail.

A technique for the artificial infection of the snail Helix aspersa by its parasite the nematode Nemhelix bakeri is described. The snail is relaxed by injection of an anesthetic, and 1 gravid female worm is introduced into the genitalia through the genital pore. Half of the injected snails were successfully infected. Following the course of infection over time indicated a 1:1 sex ratio, that the maximum number of progeny produced by injected female worms was 7, and that the development time of female worms was 56 days. The first generation of gravid females was found 100 days after infection. A survey of naturally parasitized snails was also conducted. The sex ratio of worms was in equilibrium, with a mean number of 2.4 larvae per female. The development time (56 days) and the body size (2.47-4.00 mm) of female N. bakeri are similar to those of a related species Cosmocercoides dukae (52-57 days and 1.66-4.34 mm), although the life cycle and biogeographic distribution for each of them are distinct.

Animals↗

PubMed1994

[Influence of brain grafts on growth restoration of snail (Helix aspersa) deprived of the midbrain].

Microsurgical removal of the mesocerebrum from the brain of juvenile snails stopped their growth whereas intracerebral implantation of desheathed cerebral ganglia (CG) re-established it. When the animals were grafted with CG from very young snails growth was much more stimulated than with CG from donors of the same age or from adults. Furthermore, young CG of juvenile fast growing specimens of the large species (Helix aspersa maxima) induced a higher growth rate than the CG of the ordinary small garden snails (Helix aspersa aspersa). Labelling of the neural grafts with the vital fluorescent dye fast blue enabled us to follow the repopulation of the lesioned area of the brain of the host during the functional integration of the implanted neurons into the circuits that control growth in snails.

Age Factors↗

PubMed1994

Carriage of Yersinia species by snails (Achachatina marginata): an epidemiological survey.

Three Yersinia species Yersinia enterocolitica, serogroup 0:9, Yersinia intermedia, serogroup 0:52.54 and Yersinia fredricksenii, serogroup 0:44.45 were experimentally inoculated into 249 giant African snails, Achachatina marginata, and the rate of recovery, as well as change (loss or gain) in weight determined. Results obtained showed that there was a high recovery rate of the inoculated Yersinia serogroups. Also, the snails showed loss in weight which increased with increase in recovery rate. No death of the infected snail was recorded. This study has revealed that snails (Achachatina marginata) could be potential carriers of Yersinia spp. and may therefore, play a role in the epidemiology of yersiniosis in our environment.

Animals↗

PubMed1977

Studies on the fresh water cercariae in Leyte Island, Philippines. I. Collection of snails.

During the past two years of 1975 and 1976, approximately sixteen thousand specimens of fresh water snails were examined for the presence of cercariae in Leyte Island, Philippines. These snails comprised about 14 species belonging to 7 families, and ultimately 43 species of cercariae were found, namely, 6 species from Oncomelania quadrasi, 13 species from Thiaridae, 9 species from Viviparidae and Pilidae, 8 species from Planorbidae, and 7 species from Lymnaeidae and Bulinidae. As a total, out of 15,925 snails examined, 761 or 4.78% were found infected with cercariae. Up to the present, 22 species of cercariae had been reported from the Philippines, and almost all of them are from Luzon Island only. Therefor, except for the cercaria of Schistosoma japonicum, all of the cercariae in the present study are new discoveries, and most of them are considered as new species. In this paper, the historical review on the cercarial study in the Philippines was made first, then dates and localities of snail collection in the present study were shown in details with some map and table, and general method of cercarial observation was described for the benefit of succeeding reports of this series.

Animals↗

PubMedDate not supplied

[Serotonin simulates the neuronal effects of nociceptive sensitization in the snail].

Serotonin (5-HT) application (10 mcM) onto L-PPl1 neurons of the pleural ganglia of land snail Helix lucorum produced the synaptic facilitation of the neuronal response evoked by sensory stimulation. At the same time, it did not change the parameters of the neuronal membrane (resting potential and membrane excitability). In addition to synaptic facilitation, the higher 5-HT concentration (100 mcM) produced an increase in membrane excitability and a slight membrane depolarization. The 5-HT effects were modality-dependent: the duration of facilitation of the response evoked by tactile stimulation of the snail head was about 1 h while that of the response evoked by quinine application (0.3% solution) onto the snail lip was 2-3 h. The 5-HT effects were site-specific: its application facilitated only the neuronal responses evoked by tactile stimulation of the snail head but not other body sites. The dynamics of the electrophysiological effects and the level of bound calcium were similar in L-PPl1 neurons. The described neuronal effects resemble those observed after the nociceptive sensitization of these neurons. The data obtained suggest the 5-HT involvement in the mechanisms of short-term changes and consolidation of long-term plasticity underlying the sensitization in Helix L-PPl1 neurons.

Animals↗

PubMed1997

Planorbid snails as potential molluscan intermediate host of a human intestinal fluke, Neodiplostomum seoulensis (Trematoda : Diplostomatidae) in Korea.

Three species of the pulmonate snails of the family Planorbidae have been reported from Korea; Gyraulus convexiusculus, Hippeutis (Helicorbis) cantori and Segmentina (Polypylis) hemisphaerula. Of these 3 species, only H. cantori is reported as the molluscan intermediate host of Neodiplostomum seoulensis, one of the important snail-borne human intestinal trematodes in Korea. However, S. hemisphaerula was also found to be an intermediate host for N. seoulensis. In field-collected snails, H. cantori and S. hemisphaerula were found shedding bifurcated cercariae of N. seoulensis, whereas no G. convexiusculus was found shedding cercariae. In experiments with laboratory-bred snails, only S. hemisphaerula was susceptible to miracidia of N. seoulensis. Tadpoles of Rana nigromaculata and R. rugosa were exposed to cercariae shed from field-collected and laboratory-bred S. hemisphaerula. All tadpoles of R. nigromaculata were found to be massively infected, but none of the tadpoles of R. rugosa were infected with larvae of N. seoulensis. Metacercariae from tadpoles of R. nigromaculata and the snake Rhabdophis tigrinus tigrinus were fed to rats, and eggs of N. seoulensis were detected in the rat feces one-week later. These rats were killed and adult N. seoulensis recovered from the small intestines. This is the first report of S. hemisphaerula as a molluscan intermediate host for N. seoulensis in Korea.

Animals↗

PubMedDate not supplied

Histopathological effects in tissues of snail Lymnaea stagnalis (Gastropoda, Pulmonata) exposed to sublethal concentration of Thiodan and recovery after exposure.

Histopathological alterations induced by Thiodan in three tissues, namely, digestive gland, foot and mantle, of the freshwater snail Lymnaea stagnalis were investigated. Specimens of Lymnaea stagnalis were exposed to 0.36% and 0.72% Thiodan 35 EC, a commercial grade of endosulfan, for 96 h followed by a recovery period of 30 days. Thiodan caused significant dose dependent histopathological changes in all the tissues of the snail. Irreversible necrotic changes occurred in the digestive gland of the snail following Thiodan exposure. Degenerative changes in the muscle fiber of the foot, protein and pigment cells of the foot and the connective tissue element of the mantle were recovered after 30 days of recovery of the snail in pesticide-free freshwater.

Animals↗

PubMed1999

Schistosoma mansoni: continuous variation in susceptibility of the vector snail of schistosomiasis, Biomphalaria tenagophila I. Self-fertilization-lineage.

Mascara, D., Kawano, T., Magnanelli, A. C., Silva, R. P. S., Sant' Anna, O. A., and Morgante, J. S. 1999. Schistosoma mansoni: continuous variation in susceptibility of the vector snail of schistosomiasis, Biomphalaria tenagophila I. Self-Fertilization-Lineage. Experimental Parasitology 93, 133-141. Artificial selection of Biomphalaria tenagophila snails for susceptibility to infection by Schistosoma mansoni (Brazilian SJ strain) was carried out from natural populations. After five self-fertilization generations, two lineages were isolated and were designated as SUSC (highly susceptible 93-100%) and RES (nonsusceptible 5-0%). Length of the prepatent period, cercarial production, and mortality of the hosts in postexposure were determined in all generations (F(1)-F(8)) and were analyzed as quantitative traits related to host susceptibility. Distribution patterns of frequencies were observed within snail families (samples derived from one F(0) snail), these traits showing a significant influence by selection applied to susceptibility. The multiple quantitative classes were described in terms of continuous variation. During the selection of SUSC lineage, classes with higher values of prepatent length and lower cercarial production were eliminated, and the heritability calculated for these two traits was 0.811 and 0.709, respectively. Experimental results were correlated with an increase in the level of susceptibility in the generations selected and are discussed in relation to inheritance patterns as well as the quantitative variation of susceptibility.

Animals↗

PubMed1999

Laboratory screening of nematodes isolated from south australia for potential as biocontrol agents of helicid snails

The helicid snails Cernuella virgata, Theba pisana, Cochlicella acuta, and Cochlicella barbara are introduced pests in grain crops and pastures in southern Australia. A survey for nematodes with potential for biocontrol of these snails was carried out and six local nematode isolates were tested for their ability to kill C. virgata, T. pisana, and C. acuta using a soil-based laboratory bioassay. The rhabditid isolate R 954 was highly pathogenic to all three snail species with mortality increasing with increasing nematode densities and exposure time. C. acuta was most susceptible to R 954. In addition, high mortalities followed exposure of C. acuta to two cephalobid isolates, C 916 and C 920. Snail mortality caused by the other nematode isolates tested was too low for further consideration as possible biocontrol agents. Copyright 1999 Academic Press.

Journal Article↗

PubMedDate not supplied

Comparative toxicokinetics of 2,2'- and 4,4'-dichlorobiphenyls in the pond snail Lymnaea stagnalis (L.).

Pond snails (Lymnaea stagnalis (L.)) were treated with 2,2'-dichlorobiphenyl (DCB) or 4,4'-DCB, to examine the toxicokinetic profile of these compounds. Snails were treated orally with 210 micrograms 4,4'-DCB (impregnated on food) for 14 hr, or snails were injected with 50 micrograms of 2,2'-DCB or 4,4'-DCB in the foot. At different times after starting feeding or injection, tissues (albumen gland, digestive gland and digestive tube, central nervous system, remainder parts), hemolymph and faeces were analyzed for unchanged 2,2'- or 4,4'-DCB. The results showed that in case of oral administration of 4,4'-DCB after 144 hr, 97.5% of the dose was excreted unchanged in the faeces. During the first 48 hr 4,4'-DCB was found in all tissues. Thereafter, an exponential elimination was found (the rate constant of elimination (kel) varied from 0.010-0.021 per hr, t1/2 from 33-60 hr and the apparent clearance from 0.02-0.3 g/hr for the different tissues). After injection, the compounds were found in all the above mentioned tissues, especially in the digestive gland. There was a clear difference between snails injected with 2,2'- and 4,4'-DCB. Firstly, kel for 2,2'-DCB was higher (0.028 per hr vs 4,4'-DCB: 0.001 per hr). Secondly, 2,2'-DCB was lethal; 63% of the animals died after 72 hr.

Animals↗

PubMed2000

Synthesis of new uracil-5-sulphonamide-p-phenyl derivatives and their effect on Biomphalaria alexandrina snail's nucleoproteins.

In continuation of the previous work (Fathalla, 1992) on the synthesis of some heterocycles containing uracil moiety, we report herein the incorporation of uracil moiety into cyanopyridine thione, thiosemecarbazone, semicarbazone, cyanopyridine, aminocyano pyridine, isoxazoline, pyrazoline, pyrimidine, triazolo pyrimidine, pyran, selena and thiazole derivatives which might modify their biological activities. The biological studies revealed that the chemical compound III f showed high molluscicdal activity than other compounds. The profile of the nucleoprotein extracted from chemically (compound IIIc, e, f and g) treated or UV-irradiated B. alexandrina snails did not show appreciable differences when compared to non-treated (native) snails by using SDS-PAGE, where no obvious qualitative or quantitative differences were observed. Immunization of experimental animals with the nucleoprotein extracted from native, chemically (compound III f & g) treated or physically treated B. alexandrina snails induced significant protection against challenge with normal S. mansoni cercariae, as compared to the non-immunized challenged control. As well as, a decrease in the number of granuloma formation and the size range of granuloma was also observed in immunized animals. It is concluded that, compounds III f and g have a potent molluscicidal activity. They also induced chemical modification comparable to that induced by physical treatment in the snail's nucleoprotein, which could possibly be used in immunization against S. mansoni infection.

Animals↗

PubMed2004

Effect of herbal molluscicides and their combinations on the reproduction of the snail Lymnaea acuminata.

Effects of sublethal treatment (20 and 60% of LC50/24 h) of the plant-derived molluscicides Annona squamosa Linn. and Lawsonia inermis Linn. and their combinations with other herbal molluscicides, such as Cedrus deodara Roxb, Azadirachta indica A. Juss, bulb powder of Allium sativum Linn. and Polianthes tuberosa Linn., and oleoresin of Zingiber officinale Rosc., and acetogenins extracted from the seeds of A. squamosa Linn., on the reproduction of the snail Lymnaea acuminata have been studied. It was observed that the plant-derived molluscicides singly and in binary combinations with other herbal molluscicides and the extracted acetogenins caused a significant reduction in the fecundity, hatchability, and survival of young snails. Withdrawal of the snails to fresh water after the above treatment caused a significant recovery in the fecundity of the snail Lymnaea acuminata. Twenty-four-hour sublethal treatment with the acetogenins caused a maximum reduction in the protein, amino acid, DNA, and RNA in the ovotestis of treated Lymnaea acuminata.

Amino Acids↗

PubMed2000

Prevalence of Haplometra cylindracea infection in three species of Lymnaea snails in central France.

Field investigations were performed over a 2- or 3-year period at five sites in central France to determine the prevalence of Haplometra cylindracea infection in three species of adult Lymnaea, and to compare it with that of Fasciola hepatica infection recorded in the same snails. L. glabra, L. palustris, and L. truncatula harboured Haplometra larval forms but the prevalence of this infection varied according to the site and snail species studied. The prevalences in May ranged over 0-66.9% in L. glabra, 3-7.7% in L. palustris, and 0-31.5% in L. truncatula. The mean intensity of H. cylindracea infection in May did not show any significant variation, whatever the site and species studied. The prevalence of F. hepatica infection was significantly lower in snails collected in sites known for H. cylindracea infection than in those originating from nearby meadows (0-1% instead of 1-5%). H. cylindracea could develop in some Lymnaea species and its occurrence had an impact in snails by decreasing the prevalence of F. hepatica infection.

Animals↗

PubMed1993

Detection of genetic diversity within snail intermediate hosts of the genus Bulinus by using random amplified polymorphic DNA markers (RAPDs).

A polymerase chain reaction-based polymorphic assay procedure (RAPD) was used to study the genetic diversity of intermediate host snails within the genus Bulinus. Genetic differentiation was detected between two closely related species: Bulinus globosus and Bulinus umbilicatus. Evidence is presented demonstrating the potential of RAPD markers for differentiating populations of B. forskalii from different countries (Cameroon, Equatorial Guinea and Ivory Coast) or from the same country (Cameroon). RAPDs may be also used to identify offspring from cross- and self-fertilized hermaphrodite bulinid snails. RAPDs provide a cost-effective and routine method for genetic studies of snails transmitting schistosomiasis and for the evaluation of diversity between snail populations.

Animals↗

PubMed1983

Chronic intoxication by an herbicide, 2,4,5-trichlorophenoxyacetic acid, in the pond snail, Lymnaea stagnalis L.

Experiments of chronic intoxication with three concentrations (10, 20, and 40 ppm) of 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) were conducted in the freshwater mollusc Lymnaea stagnalis. Snail survival was concentration dependent. In all cases the growth can be described by the von Bertalanffy pattern (ht = h (1 - e-k(t-to)) and the variations of the k values showed that growth was significantly altered in all the groups treated. The overall fecundity (F) was always reduced; the decrease was due both to a lower number of eggs per egg mass (-7.8 to -12%) and to an earlier death of the intoxicated snails. Fecundity studied in terms of size, according to the law F = ahz, points out the loss of equilibrium between growth and fecundity: in all groups treated the values of the exponent z were increased. The importance of these perturbations can be quantified by the calculation of a "Snail Yield" which is reduced by 72.6% in the 40 ppm group. Egg fertility was also reduced. It can be concluded that 2,4,5-T disturbs the physiological equilibrium of Lymnaea stagnalis leading even to earlier death of the snails.

2,4,5-Trichlorophenoxyacetic Acid↗

PubMed1984

Schistosoma mansoni: passive transfer of resistance by serum in the vector snail, Biomphalaria glabrata.

Passive transfer of natural resistance to Schistosoma mansoni (PR-1 strain) has been successfully accomplished in the snail intermediate host, Biomphalaria glabrata (PR albino, M-line strain). Injection of serum (cell-free hemolymph) from a naturally schistosome-resistant strain of B. glabrata (10-R2) into PR albino snails induced a complete protection from a primary infection with the parasite in 29 of 48 snails (60.4%). In comparison, inoculation of homologous PR albino serum or heterologous proteins (fetal calf serum) had no effect. Moreover, this protection could be induced 24 hr prior to, or 24 hr after, exposure to the parasite, although heating of 10-R2 serum to 70 C for 30 min destroyed its protective ability. When in vitro transformed sporocysts were preincubated in 10-R2 or PR albino serum and then were injected into susceptible snails, a high level of infection (88.5 and 83.3%, respectively) was produced in both groups. Thus, the 10-R2 serum factor does not appear to be mediating specific parasite recognition by host hemocytes. Alternatively, our results suggest that 10-R2 serum possesses a heat-labile factor which specifically activate B. glabrata hemocytes to encapsulate and destroy sporocysts whereas PR albino serum lacks this factor.

Animals↗