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PubMed2005

Wnt, hedgehog and snail: sister pathways that control by GSK-3beta and beta-Trcp in the regulation of metastasis.

The epithelial-mesenchymal transition have begun to attracted many attentions as a potential mechanism for metastasis. The phenotypic changes of increased motility and invasiveness of cancer cells are reminiscent of epithelial-mesenchymal transition (EMT) that associates with the downregulation of E-cadherin. Snail, zinc finger transcription factor, triggers this process by repressing E-cadherin expression. Recently Snail was found to be dually regulated GSK-3beta through protein stability and cellular localization. The involvement of GSK-3beta and beta-Trcp in the regulation of Snail is particular interesting, because these two molecules are also known to involve in the regulation of Wnt and hedgehog pathways that are known to control cell fate and morphogenesis during development and tumorigenesis. Here, we briefly compare these pathways and propose the possibility of cross-talk among these pathways in the regulation of cell adhesion, cell fate, and migration during metastasis.

Glycogen Synthase Kinase 3↗

PubMed1970

Control methods for snail-borne zoonoses.

All trematodes which cause infections and diseases in humans (zoonoses) require snails for their first intermediate host. Some have additional intermediate hosts such as crustaceans, fishes and frogs. In this paper I have discussed the use of various procedures for controlling snail populations thereby reducing the population of trematodes whose cercariae penetrate the skin of man, or which are acquired by eating raw aquatic vegetation such as watercress, or which cause pathology in fish. Biological, chemical, and physical snail control techniques are discussed. The most promising molluscucides are copper compounds, Bayluscide, biocidal rubber and molluscicidal bait.

Animals↗

PubMed1999

Effects of naloxone on c-jun/AP-1 in met-enkephalin-and FMRFamide-immunreactive neurons of a gastropod snail.

1. Opioid- and FMRFamide (FMRFa)-ergic systems are believed to play antagonistic behavioral roles in both higher and lower animals. In our previous experiments on a snail, behavioral choice has been demonstrated to be dependent on a balance between FMRFa and enkephalins [7]. Here, we examined if the disturbance of the balance causes changes in the activity of both systems. Opiate receptor blocker naloxone was applied and its effect on c-jun expression of met-enkephalin (MEnk)- and FMRFa-ergic neurons was examined immunocytochemically in terrestrial gastropod snail Cepaea nemoralis. 2. In control, untreated snails, central neurons with c-jun/AP-1-like-immunoreactivity were found to occur. These included MEnk-, FMRFa- and 5HT-immunoreactive (-ir) neurons, as was revealed by double-labelling. 3. After treatment with naloxone for 4 h, the following changes were observed: (i) increase in the number of MEnk-ir neurons; increase in the number of neurons showing c-jun/AP-1 and MEnk double-labeling; (ii) disappearance of c-jun/AP-1-immunoreactivity from some FMRFa-ir neurons. 4. It is suggested that immediate early genes are involved in the mechanisms responsible for the reciprocal regulation of the opioid and antiopioid neuropeptide systems.

Animals↗

PubMed2000

[Somatic polyploidy in neurons from gastropod mollusks. I. Morphological characteristics of ganglia and neurons in the CNS of the snail Succinea lauta].

A study was made of general anatomy and histological organization of the central nervous system in Succinea lauta, a gastropod pulmonate snail. Neurons grow by means of polyploidy during the postnatal succineid ontogeny. In the adult individuals diameters of perikaria of large neurons increase 2.5 to 5 times, in comparison with young individuals. As a whole, in adult snails sizes of ganglian cells vary from 3 to 380 mkm. Most of giant neurons are in parietal, abdominal and pallial ganglia. The chromatin structure has been described in neurons of young and adult snails. The endomitotic mechanism of polyploidization in the succineid ganglioneurons is proposed.

Animals↗

PubMedDate not supplied

[Effect of the population density on growth and regeneration in the snail Achatina fulica].

In the laboratory, the growth rate of the giant African snail Achatina fulica, as estimated by the weight and shell length was shown to decrease when the population density increased from 10 to 60 snails/m2 of the total terrarium area for five months. In the second experiment, when the population density increased from 48 to 193 snails/m2, the growth rate had already decreased by six weeks. In the groups with a high population density the feeding behavior was weakened, expressed by a greater amount of nonconsumed food, according to visual observations, than in the groups with lower population densities. At the population density of 10 to 60 snails/m2, the proliferative activity in the course of the optic tentacle regeneration, as expressed by the mitotic index, did not differ reliably within five months. In the second experiment, the mitotic indices at the population densities of 96 and 193 snails/m2 within 1.5 months exceeded that of 48 snails/m2. Recommendations are given concerning the population density from the viewpoint of commercial growth of the snails. It was proposed that, based on the analysis of the mechanism underlying the inhibition of feeding behavior in populations with extra high densities, one may develop a new approach to the production of chemical agents to control land snails as agricultural pests.

Animals↗

PubMed1975

Aroapyrgus costaricensis, hydrobiid snail host of paragonimiasis in Costa Rica.

A small freshwater hydrobiid snail found in narrow shallow steams at various altitudes in Costa Rica is the intermediate host of Paragonimus mexicanus. Based on the morphology of its shell and soft parts the snail is assigned to the species Aroapyrgus costaricensis (Mörch). It is easily maintained in the laboratory; the female is ovoviviparous, carries up to 40 embryos in its brood pouch, and young-to-young cycle is about 10 weeks. Natural infection rates with rediae and cercariae of Paragonimus mexicanus are less than 1%, the majority of the naturally infected snails are of medium size (about 2 mm in height), but all sizes (ages) can be experimentally infected. The microcercous cercairae of P. mexicanus emerge from A. costaricensis in late afternoon and evening, about 2 months after exposure to the miracidia.

Animals↗

PubMed1975

Active transport of sugars by the intestine of snail (Cryptomphalus hortensis Müller).

Sugar transport by sacs of everted intestine of snail have been measured in vitro at 30 degrees C. D-galactose, D-glucose and 3-O-methylglucose were actively transported against a concentration gradient from the mucosal to the serosal compartment. The transport of these sugars was inhibited by 5 times 10(-8) to 10(-6) M phlorizin. L-arabinose was also accumulated in the serosal compartment against a concentration gradient; in this case, transport was not affected by phlorizin. The snail intestine did not show any ability for D-fructose active transport but there was a clear uptake of this sugar by the tissue. The O2 uptake of the snail intestine was not significantly affected by the presence of either sugars or phlorizin.

Animals↗

PubMed2002

Atrial natriuretic peptide in the granular cells of the snail heart.

UNLABELLED: Cardiomyocytes of vertebrates combine contractile and endocrine functions. They synthesize and secrete atrial natriuretic peptide (ANP), which is localized in their specific granules. The presence of ANP has been shown in some tissues of invertebrates, including the heart of molluscs. We have studied localization of ANP in cells of the snail heart. METHOD: The atrial and ventricular tissues of the snail Helix pomatia were studied by electron microscope immunocytochemistry, using anti-ANP antibodies. ANP-immunoreactivity has been detected in granules of granular cells located on the luminal surface of the snail myocardium. These cells are abundant in the atrium being very rare in the ventricle. Granular cells at different stages of maturation were revealed. Immature granular cells have light granules of moderate size with homogeneous tight content, while mature granular cells are huge in size and all their granules are fused together. The material of these granules loosens up and almost completely fills up the cytoplasm. No ANP-immunoreactivity was observed in muscle cells or nerve fibers. A possible origin of granular cells from the cardiac endothelial cells is discussed. The molluscan heart, similar to that of vertebrates, is a bifunctional organ. However, contrary to the heart of vertebrates, in the molluscan heart contractile and endocrine functions are separated between different types of cells.

Animals↗

PubMedDate not supplied

[Prospects for studies on morphological variability of land pulmonate snails].

The main goal of modern investigations into the morphological variability of land pulmonate snails was defined as designing the patterns of taxa structure on the basis of historical analysis of their taxonomic studies. Transition from the investigation of individual characters to an analysis of the organism as a whole assumes the application of the system approach. Systemic properties of the organism can be revealed through the key characters reflecting the process of evolutionary transformation of the correlation chains. In the case of land pulmonate snails, the relationship between the operative and conservative subsystems of the organism can serve as such a key character. The operative subsystem-cephalopodium-fulfills the function of active contacts with the environment; the conservative subsystem--the shell and its content-exercises protective functions. The subsystems are in conflict, and its resolution establishes the main patterns of the organization of pulmonate snails.

Animals↗

PubMed2002

[Spatial autocorrelation analysis on schistosomiasis cases and Oncomelania snails in three provinces of the lower reach of Yangtze River].

OBJECTIVE: To explore the spatial distribution of schistosomiasis cases and Oncomelania snails in the provinces of Jiangsu, Anhui and Jiangxi with the assistance of geographic information systems (GIS). METHODS: Epidemiological data of schistosomiasis in recent 20 years were collected, and the relevant GIS databases were established. The spatial autocorrelation analysis was carried out with ArcView 3. x, S-Plus, and Spatial Statistics software. RESULTS: Except for schistosomiasis cases in Jiangsu, the spatial distribution of schistosomiasis cases and Oncomelania snails in the three provinces were fitted to the spatial autocorrelation at a certain degree. Generally the autocorrelation coefficients (Moran's I) in Oncomelania snails were higher than that in schistosomiasis cases. CONCLUSION: Spatial autocorrelation analysis can be used to estimate the value of one variable in different spatial position, and it is a good way to find out the spatial cluster distribution in different stages.

Animals↗

PubMed2003

A longitudinal study of schistosome intermediate host snail populations and their trematode infection in certain areas of Egypt.

Seasonal variation of Biomphalaria alexandrina and Bulinus truncatus populations and their infection rates with schistosome and other trematode cercariae were studied longitudinally in four water courses located in Giza and Faiyoum Governorates. Abundance of both species varied from year to year and according to the type of habitat. The mean prevalence of Schistosoma mansoni in Biomphalaria was 0.29%, that of S. haematobium in Bulinus was 1.36%. Seasonal variations of age structure of the 2 vector snails were monitored throughout the survey period. Infection rates with schistosome and other trematodes among Bulinus and Biomphalaria increased with the increase in snail size. Data suggest the occurrence of an antagonistic interaction between schistosome and non-human cercariae, especially echinostome, in infected snails.

Animals↗

PubMed1992

[14C]-glucose metabolism of Oncomelania snails.

To elucidate the importance of glucose metabolism in Oncomelania snails, uniformly labelled D (14C)-glucose [(U-14C)-glucose] has been used as a tracer for observing glucose uptake, incorporation into macromolecules and the activity of enzymes involved in its metabolic pathway. Radioactivity of Oncomelania increased with time of exposure (3, 6, 12 and 24 h) to [(U-14C)-glucose] solution. In snails treated with 2 ppm bromoacetamide for 24 h, the radioactivity of soft tissues was markedly less than that of normal snails. Oncomelania can synthesize glycogen from absorbed glucose, and the absorbed (U-14C)-glucose may be incorporated into nucleic acid, protein and lipid, with 14CO2 excreted as an end metabolic product. 6-phosphoglucose dehydrogenase and 6-phosphogluconate dehydrogenase activities were demonstrated by the reduction of NADP and determination of 14CO2 from (1-14C)-glucose, respectively. The results indicate that there exists a phosphopentose pathway in Oncomelania.

Acetamides↗

PubMed2003

D-amphetamine-elicited action potential bursts in central snail neurons: role of second messenger systems.

BACKGROUND AND PURPOSE: Neuronal bursts of action potentials are closely related to seizure activity. Amphetamine rarely induces seizures at therapeutic doses, but seizure may occur after the first dose. This study investigated factors affecting d-amphetamine-elicited action potential bursts in isolated central snail neurons. METHODS: The central right parietal neuron 1 (RP1 neuron) from the subesophageal ganglia of the African snail Achatina fulica Ferussac was used to evaluate neurotransmitter systems involved in d-amphetamine-elicited potential burst activity by use of conventional electrophysiological and general pharmacological techniques. RESULTS: d-Amphetamine (135 and 270 microM) elicited bursts of action potentials in the RP1 neuron in a concentration dependent manner. The burst activity was not blocked by pretreatment with prazosin (100 microM), yohimbine (100 microM), propranolol (100 microM), atropine (1 mM), or by continuous perfusion of calcium-free solution. These results suggest that the burst activity elicited by d-amphetamine was not due to activation of the cholinergic or adrenergic receptors of the excitable membrane. The burst firing of action potentials was decreased following extracellular application of the specific protein kinase A inhibitors H89 (N-[2-(p-bromocinnamylamino)-ethyl]-5-isoquinoline sulfonamide, 10 microM), or KT-5720 (10 microM). However, the burst firing of action potentials was not affected after extracellular application of the specific protein kinase C inhibitors Ro 31-8220 (10 microM) or chelerythrine (10 microM). Forskolin (10 microM), an activator of adenylyl cyclase, facilitated the burst firing of action potentials elicited by d-amphetamine. However, in the absence of d-amphetamine, a higher concentration of forskolin (100 microM) was able to elicit burst firing of action potentials. CONCLUSIONS: These results suggest that the action potential bursts elicited by d-amphetamine are associated with the cyclic adenosine monophosphate (cAMP) second messenger system and are not related to the cholinergic or adrenergic receptors or protein kinase C activity in the RP1 snail neuron.

Action Potentials↗

PubMedDate not supplied

[Vision in the edible snail. The morphology and total electrical activity of the retina].

Recording of the integrative electrical activity of the retina of the snail and electron microscopic study of its eye have shown the following. The electrical activity of the photoreceptors is a source of the retinogram (ERG) of the snail. ERG reaction form is characterized by two phases of a response: the initial spike and the following slow fading. For each given value of the photometric brightness of a light signal there exists a low limit of its length, beginning from which the ERG reaction of the snail assumes the form described. The value of the ERG response is a logarithmic function of brightness of the light stimulus.

Animals↗

PubMed2002

Storage excretion in the Indian apple snail, Pila globosa (Swainson), during aestivation.

Uric acid accumulates in several tissues of the Indian apple snail, P. globosa, during aestivation. This accumulation is particularly high in the foot muscle and reproductive organs. Since the kidney, a tiny organ in the snail, has only a limited capacity to store uric acid, extrarenal tissues are used as storage depots of uric acid during aestivation. It is suggested that the aestivating snail, faced with a cleidoic situation, resorts to storage excretion, a phenomenon well documented in insects.

Adaptation, Physiological↗

PubMed2004

Feeding ecology and food composition of the black carp Mylopharyngodon piceus and the grass carp Ctenopharyngodon idella inhabiting the fish pond of Al-Abbassa fish hatchery with emphasis given to vector snails.

Stomach contents of M. piceus and C. idella collected from earthen fish ponds at Al-Abbassa fish hatchery during different seasons were examined. Food items were analyzed by three methods; the numerical (N%) percentage of point assessment (P%) and frequency of occurrence (F%). A comparison of the different methods emphasized the importance of snails as the major food resources in the diet of M. piceus during all seasons. During winter, stomachs of the most fish samples collected from fish ponds were empty or had traces of food. The index of relative importance (I.R.I) indicated that snails were the major food category in the diet of M. piceus during summer, autumn and spring represented by 7331, 9696 and 11670 respectively. Plants were the main food item in the diet of C. idella during summer (4604), meanwhile they came 3rd in relative importance in the diet during autumn and spring. Artificial fish food came as the 2nd food item in the diet of M. piceus during summer (1398.9) and autumn (5896.3) but it completely absent in spring. It is considered the main food item in diet of C. idella during autumn (10384.3) and spring (6293.5) and being 3rd in summer (1395.5). The results showed that snails reached highest level in the diet of M. piceus during spring (about 80% of all diet, decreased during summer (about 70%) and reached lowest proportion in autumn (50%). Plants exhibited marked seasonal variation in abundance with maximum level during summer (about 41% of all diet decreased during spring (27%) and autumn (22%). Artificial fish food was the highest in the diet of M. piceus during autumn (39%), decreased in summer (22%) until disappeared during spring. It reached highest level in diet of C. idella during autumn (49%), decreased in spring (38%) and reached lowest proportion during summer (21 %).

Animals↗

PubMed1992

Succinate-DCPIP and NADH-fumarate oxidoreductases in fresh water snails susceptible and non susceptible to schistosoma infection.

The activities of succinate-DCPIP oxidoreductase (SO) and NADH-fumarate oxidoreductase (FR) were determined in tissue homogenate of Biomphalaria alexandrina and Bulinus truncatus, the snail vectors of Schistosomiasia. A parallel study was done on Lymnea truncatula snails which are not susceptible to Schistosoma infection. The Michaelis constant (Km) and maximum velocities (Vmax) for fumarate reduction and succinate oxidation by the tissue homogenates from the three species were determined. The results obtained showed that both susceptible species are aerobic and lactate is the sole end product of anaerobic glycolysis. Lymnea truncatula snails are facultative anaerobic producing succinate as a major end product in the glycolytic pathway.

Animals↗

PubMed2004

Seasonal changes in sex ratio, maturation, and size composition of fresh water snail, Sinotaia quadrata histrica, in Lake Kasumigaura.

Sinotaia quadrata histrica is a fresh water viviparous snail distributing from the Kanto region to Kyushu Island, Japan. About 7000 snails were collected in Lake Kasumigaura (L. Nishiura and L. Kitaura) in 2001 and 2002, and the sex ratio, maturity in terms of the gonad-somatic index (GSI) and operculum diameter were determined. The total female proportion was 55.2% in 2001, 53.0% in 2002 in L. Nishiura, and that of L. Kitaura was 60.4% in 2002. Comparing the season, the female proportion was the highest during early summer in both 2001 (59.6%, July in L. Nishiura) and 2002 (61.6%, June in L. Nishiura, 65.8%, July in L. Kitaura). The GSI of females in L. Nishiura significantly increased from April to May and significantly decreased from June to August. The GSI of males was higher in spring, but significantly lower from June to August. The mean female operculum diameter was consistently larger than that of males for each month and year, and a particularly significant difference was found between females and males from April to August 2001, and from April to September 2002. The number of resting zones on the operculum correlates with the operculum diameter and the female proportion was larger in the snails, which have a high number of resting zones, suggesting a sex-dependent difference in age composition. This study estimated that the sex ratio and seasonal maturation of S. quadrata histrica and the sex-dependent difference in age composition might contribute to the population structure in L. Kasumigaura.

Animals↗