SEARCH · PubMed Health

Results for “Snails”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 883 records · Page 49Linked to original sources

PubMed2005

Update of fasciolosis-transmitting snails in Egypt (review and comment).

Several snail species may contribute in transmission of fasciolosis in Egypt. These molluscs show a variable sensibility to natural infections with Fasciola species. Radix natalensis is considered to be the essential intermediate host for F. gigantica based on field and experimental studies. Cercarial production from R. natalensis experimentally infected with F. gigantica is affected by the species of definitive host from which the eggs are obtained, as well as the different laboratory conditions. Another lymnaeid, Galba truncatula, may play a role in transmitting this parasite in Egypt, as it was found naturally infected with F. gigantica. Latter snail species, originated from France, was susceptible to experimental infections with Egyptian miracidia of F. gigantica and it had a cercarial production close to that of local R. natalensis. Two other snails, Pseudosuccinea columella and Biomphalaria alexandrina, were naturally found harboring larvae of Fasciola sp. At the level of intermediate hosts of F. gigantica, the conditions are thus favorable in Egypt to transmit fasciolosis which could also be caused by another fasciolid, F. hepatica, as the existance of this fluke was confirmed in Egypt.

Animals↗

PubMed2005

Impact of certain plants and synthetic molluscicides on some fresh water snails and fish.

The LC50 (78, 85 ppm) and LC90 (88, 135 ppm) of Anagalis arvensis and Calendula micrantha respectively against Biomphalaria alexandrina were higher than those of the non-target snails, Physa acuta, Planorbis planorbis, Helisoma duryi and Melanoides tuberculata. In contrast, the LC50 of Niclosamide (0.11 ppm) and Copper sulphate (CuSO4) (0.42 ppm) against B. alexandrina were lower than those of the non-target snails. The mortalities percentage among non-target snails ranged between 0.0 & 20% when sublethal concentrations of CuSO4 against B. alexandrina mixed with those of C. micrantha and between 0.0 & 40% when mixed with A. arvensis. Mortalities ranged between 0.0 & 50% when Niclosamide was mixed with each of A. arvensis and C. micrantha. A. arvensis induced 100% mortality on Oreochromis niloticus after 48 hrs exposure and after 24 hrs for Gambusia affinis. C. micrantha was non-toxic to the fish. The survival rate of O. niloticus and G. affinis after 48 hrs exposure to 0.11 ppm of Niclosamide were 83.3% & 100% respectively. These rates were 91.7% & 93.3% respectively when each of the two fish species was exposed to 0.42 ppm of CuSO4. Mixture of sub-lethal concentrations of A. arvensis against B. alexandrina and those of Niclosamide or CuSO4 at ratios 10:40 & 25:25 induced 66.6% mortalities on O. niloticus and 83.3% at 40:10. These mixtures caused 100% mortalities on G. affinis at all ratios. A. arvensis CuSO4 mixtures at 10:40 induced 83.3% & 40% mortalities on O. niloticus and G. affinis respectively and 100% mortalities on both fish species at ratios 25:25 & 40:10. A mixture of sub-lethal concentrations of C. micrantha against B. alexandrina and of Niclosamide or CuSO4 caused mortalities of O. niloticus between 0.0 & 33.3% and between 5% & 35% of G. affinis. The residue of Cu in O. niloticus were 4.69, 19.06 & 25.37 mg/1kgm fish after 24, 48 & 72 hrs exposure to LC0 of CuSO4 against B. alexandrina respectively.

Anagallis↗

PubMed2005

[Estimating the gene pool condition in natural populations of invertebrates in the fragmented landscape of Moscow and Moscow district with special reference to shrub snail Bradybaena fruticum Müll].

Using shrub snail Bradybaena fruticum Müll (20 populations) as a model, we were the first in Russia and in the world to develop a system of urban ecological genetic monitoring of the gene pool of an invertebrate species. The results of isozyme polymorphism studies in shrub snail populations showed a dramatic (up to 70%) reduction in genetic diversity in small isolates from the urbanized environment as compared to large natural populations. In urban populations, genetic diversity parameters were demonstrated to be lower than in natural ones: the mean heterozygosity per locus was reduced up to 0.08 (0.15-0.20 in natural populations); the mean allele number, to 1.9 (2.7 in natural populations); and the number of polymorphic loci, to four, i.e., 2.2-fold (nine in natural populations). In Moscow district, the number of polymorphic loci also decreased to five in the population subjected to anthropogenic pressure. The changes in the population gene pool (as shown by the number of polymorphic loci) were different in Moscow and Moscow district. The percentage of populations with the number of polymorphic loci as low as four to six was 76.9 in Moscow and 23.1% in Moscow district. The gene pool quality of 80% of the urban snail populations was estimated as unsatisfactory, and in half of them, as critical. The main reason for these changes seems to be genetic drift accompanied by inbreeding, caused by fragmentation of the range and reduction in the abundance of populations of the species, due to the anthropogenic pressure. The results of the study were employed in the program of the Moscow government for restoring the gene pools of endangered animals species on the preserved territories of the city.

Animals↗

PubMed2006

Infectivity of Echinostoma friedi miracidia to different snail species under experimental conditions.

The infectivity of Echinostoma friedi (Trematoda: Echinostomatidae) miracidia was studied experimentally in a range of laboratory-reared snails that coexist in the same natural locality, namely Radix peregra, Lymnaea fuscus, L. truncatula (Lymnaeidae), Gyraulus chinensis, Helisoma duryi (Planorbidae) and Physella acuta (Physidae), and snails from different geographical origins acting naturally or experimentally as intermediate hosts of Schistosoma spp., namely Planorbarius metidjensis (from Málaga, Spain), Biomphalaria glabrata (Guadeloupe), B. alexandrina (Egypt) (Planorbidae), Bulinus cernicus (Mauritius), B. globosus (Zambia), B. natalensis (South Africa) and B. truncatus (Niger) (Bulinidae). Six species of snails were found to be susceptible, with the rate of infection ranging from 0 to 36.7%. The highest infection was detected in R. peregra. The low host specificity of E. friedi might have an epidemiological significance as a requisite for a recent establishment in a new geographical area.

Animals↗

PubMed1991

Preliminary observation of the susceptibility of some freshwater snails to the infection with Varestrongylus sagittatus (Nematoda: Protostrongylidae).

Under laboratory conditions, the freshwater snails Galba truncatula Müll.), Radix peregra (Müll.) and Planorbarius corneus (L.) have been successfully infected with the first stage larvae of the protostrongylid nematode Varestrongylus sagittatus (Mueller, 1890) Dougherty, 1945. The net rate of the infection (mean number of larvae per snail examined - l/s) was 6.2 l/s in R. peregra and 3.5 l/s in P. corneus. G. truncatula was susceptible to the infection too (36.3 l/s). However, this result can be considered as pilot only, because of the low number of the specimens of this species examined. At 25 degrees C 50% of V. sagittatus larvae reached the 3-rd stage of development by 12.5 days post infection (DPI) in R. peregra and by 17.8 DPI in P. corneus. It was confirmed that the snail species of the Basommatophora that were studied can act as intermediate hosts of the nematode V. sagittatus under laboratory conditions.

Animals↗

PubMed1991

[Effects of dephosphorylated core of 2',5'-oligoadenylate (2',5'-ApApA) on the electric activity of snail neurons].

On nervous ganglion of snail Helix pomatia was shown the effect of dephosphorylated core of 2',5'-oligoadenylate (2',5'-ApApA) on pacemaker electrical activity of RPa2 snail neurons. In experiments, solution of 2',5'-ApApA in concentration 5 x 10(-5) mol/l effected snail nervous ganglion in the course of 2 min then it was washed in the course of 2 hours.

Adenine Nucleotides↗

PubMed1990

[Preliminary studies on transaminase of Oncomelania snail].

By paper chromatography, the tissue homogenate of Oncomelania snails was shown to form glutamic acid at the expense of alpha-ketoglutarate plus aspartic acid, alanine or arginine respectively. The existence of alanine-glutamate, aspartate-glutamate and arginine-glutamate transaminase in Oncomelania snail was demonstrated. By using colorimetric method, the activity of aspartate-glutamate transaminase (GOT) and alanine-glutamate transaminase (GPT) of Oncomelania snail was 1.64 +/- 0.01 and 0.99 +/- 0.01 mumol/h.mg protein respectively. GOT and GPT were not inhibited by 2 ppm bromoacetamide, but the activity of GPT was suppressed (40%) by 2 ppm nicotinanilide. A combination of 0.5 ppm bromoacetamide and 0.5 ppm nicotinanilide had no synergitic molluscicidal effect.

Acetamides↗

PubMed1990

Single and dual infections of the land snail Helix aspersa with Muellerius capillaris and Alloionema appendiculatum (Nematoda).

Helix aspersa, a land snail, has been experimentally infected with 2 species of nematodes Muellerius capillaris and Alloionema appendiculatum. A significant reduction of infection with M. capillaris was recorded in snails preinfected with A. appendiculatum, whereas snails preinfected with M. capillaris were as susceptible to A. appendiculatum.

Analysis of Variance↗

PubMed1986

Snail control in relation to a strategy for reduction of morbidity due to schistosomiasis.

The control of schistosomal disease is now distinctly feasible in endemic situations where a capable health care delivery system exists. Effective integrated control of schistosomiasis morbidity, within available resources at national level, is now being carried out in many countries. The control of snail hosts by chemical, environmental and/or biological means can still play a significant supporting role in many endemic situations. Today, however, as compared to earlier decades when disease control procedures were far less advanced, there is need for reappraisal of snail host control strategies to ensure that objectives are now correctly set, that the potential operational mechanisms are carefully chosen under the headings of desirability, feasibility and cost-effectiveness and that implementation and evaluation of the operations have, as far as possible, both theoretical and practical validity. Nowadays snail host control procedures must be intimately linked to knowledge of transmission sites and seasonal patterns, focal and periodic transmission being the rule rather than exception; in particular, they must be associated with local schemes for the delivery and evaluation of population based chemotherapy campaigns.

Animals↗

PubMed1987

Immunological aspects of snail-trematode interactions.

After penetration into its snail host the trematode not only has to find a suitable environment, it also has to circumvent the activities of its host's internal defence system to survive and to develop normally. Immunological compatibility of snails and trematodes is dependent on the capability of the parasite to evade and/or suppress the defence activities of its host. The possible role of physicochemical properties of the surfaces of the parasite and the host defence cells in evasion of host responses remains unknown; a role is indicated for molecular mimicry in the miracidium and the young mother sporocyst and for masking in the cercaria. Strong evidence exists that trematodes secrete substances which suppress anti-trematode activities of snail haemocytes.

Animals↗

PubMed1976

[The disulfide bridges of the trypsin-kallikrein inhibitor K from snails (Helix pomatia). Thermal inactivation and proteolysis by thermolysin (author's transl)].

Isoinhibitor K is the main component of the complex mixture of isoinhibitors of broad specificity secreted into the mucus by the Roman snail (Helix pomatia). The disulfide pairing was determined after the amino acid sequence had been elucidated. Two cystine-containing peptides with the disulfide bridges Cys32-Cys53 and Cys32-Cys53 plus Cys7-Cys57 were obtained after thermolytic hydrolysis of the native inhibitor at 80 degrees C and chromatographic separation of the peptides using SE-Sephadex. The Cys16-Cys40 disulfide bridge could be reduced selectively by sodium borohydride with no loss in biological activity. This property and the covalent structure correspond to that of the intracellular inhibitor from bovine organs, which is largely homologous in its amino acid sequence to the secretory inhibitor from the snail. The complete covalent structure of isoinhibitor K will be presented. The snail inhibitor is less stable against proteolytic inactivation by thermolysin and against thermal denaturation at pH 8.0 than the inhibitor from bovine organs (Kunitz inhibitor).

Amino Acid Sequence↗

PubMed1966

Host-parasite relationship of Bulinus truncatus and Schistosoma haematobium in Iran. 3. Effect of water temperature on the ability of miracidia to infect snails.

Laboratory studies were made in Iran to test the effect of water temperature on the ability of the miracidia of S. haematobium to penetrate B. truncatus. Snails three to four weeks old were exposed to two miracidia each for two hours at nine water temperatures ranging from 10 degrees C to 38 degrees C. After exposure, all the snails were kept in aquaria at room temperature. The cercaria-positive rates of these nine groups of snails showed that the optimum exposure temperature was in the range 20 degrees C-30 degrees C. The infection rate was low at temperatures outside this range. It is concluded that the optimum transmission seasons in bilharziasis-endemic areas in Iran are spring and autumn but that transmission still occurs in hot summer and cold winter months although to a much smaller extent.

Animals↗

PubMed1983

[Model study of neuronal mechanisms of distinguishing 2 tactile stimuli in the snail].

A simple two-layered neuronal network model consisting of afferent and efferent neurons was constructed on the basis of a study of neuronal structure of defensive reactions in snail. Synaptic and spike reactions of the efferent neurons in response to stimulation of the receptive fields of afferent neurons were studied. It has been shown that a reduction in the distance between two points of stimulation results in a gradual transformation of a bimodal distribution of synaptic and spike reactions of the efferent neurons to the one-modal. These changes in synaptic and spike reactions were in agreement with the reaction of the snail leg muscle to two tactile stimuli simultaneously applied to the skin of the leg. The ablation of the snail central nervous systems resulted in a more diffuse contractile reaction. It is suggested that the central and peripheral neuronal networks differ in the exactness of defensive reflex realizations.

Animals↗

PubMed1984

Effect of gamma irradiation on the reproductive system of the pond snail Physa acuta.

Changes in the survival rate in adults and embryos of the pond snail Physa acuta were studied after acute whole-body gamma irradiation. The LD50 value of the adult snails was about 40 kR. The LD50 values of the embryos irradiated 0 and 1 day after oviposition were about 0.9 and 2 kR, respectively. Histological changes in the ovotestis, the number of eggs laid, and their hatchability were examined in the irradiated adult snails. A fall and a subsequent recovery were observed for these characteristics after irradiation with 8 kR of gamma rays. The relative constitution of the germ-cell populations was greatly changed by the same dose of gamma rays. The proportion of immature germ cells was reduced, and the total number of germ cells also diminished 11 days after irradiation. After depletion, the ovotestis was first repopulated with gonia , and then with oocytes, spermatocytes, and spermatids.

Animals↗

PubMedDate not supplied

[Long-term results of biological control by predation. Experimental study of population development of several species of snails (author's transl)].

The evolution of malacological fauna, which is subject to prediation of Zonitidae snails, is studied on two types of habitats of Lymnaea truncatula: swampy meadows and banks of river maintained by a periodical grass-mowing. Two years are necessary for obtaining an entire elimination of Lymnaea truncatula. Then other species of Lymanaeidae and Succinea are affected by predation, but Succinea snails do not pass away completely. The other snails are not affected or little by predation.

Animals↗

PubMed1982

Freshwater snails survey in and around the Cambodian refugee camp, Sakaeo District, Prachinburi Province, Thailand.

The freshwater snails surveys were carried out during September 15, 1981 to December 15, 1981, especially for the intermediate or possible intermediate host of Schistosoma mekongi in and around the Cambodian refugee camp at Ban Kaeng Holding Centre, Sakaeo District, Prachinburi Province. A total of 30 localities were visited and 15 species of freshwater snails were collected. The snails did not shed any cercaria of S. mekongi and none of these was the intermediate host of S. mekongi.

Animals↗

PubMed1982

Comparative study of cholinesterase in two snails Pila globosa and Lymnaea acuminata.

Enzymatic activity of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) was measured in the nervous and cardiac tissue of two snails Pila globosa and Lymnaea acuminata. Data on substrate specificity, enzyme kinetic constants and specific enzyme inhibitors indicated that, L. acuminata possessed both AChE and BuChE, while, P. globosa had only AChE. Pharmacological experiments carried out on isolated organs of the two snails indicated that isolated organs of P. globosa were sensitive to low doses of acetylcholine (ACh) and to relatively higher doses of butyrylcholine (BuCh). The responses elicited by ACh could be enhanced by eserine but that of BuCh could not be increased by ethopropazine which has been shown to be a specific inhibitor of BuChE in snails. Isolated hearts of L. acuminata on the other hand, were more sensitive to BuCh as compared to ACh. The BuCh effect was enhanced by ethopropazine while the effect of both ACh and BuCh increased by prior application of eserine. There is a correlation between the occurrence of the two types of cholinesterase (ChE) and the sensitivity of the isolated organs to a specific substrate of these enzymes suggesting a possible correlation between transmitters and cholinesterase system.

Acetylcholinesterase↗

PubMed1994

[Snail hosts of Paragonimus in Asia and America].

This is a comprehensive review of snail hosts of Paragonimus distributed worldwide exclusive of Africa. Fifty-eight species of snails are listed, of which 67% occur in China. Most of the Chinese snails are classified as Pomatiopsinae Erhaiini or Triculinae of the family Pomatiopsidae. Problems associated with a number of names and concepts have been clarified.

Americas↗