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Ecology of freshwater snails in south-western Nigeria. I: Distribution and habitat preferences  

Microsoft Academic Search

Dry and rainy season investigations of diverse freshwater habitats in south-western Nigeria revealed fourteen species of snail comprised of nine pulmonates: Biomphalaria pfeifferi Krauss, Bulinus globosus Morelet, Bulinus rohlfsi Clessin, Lymnaea natalensis Krauss, Physa ( ˜ Aplexa) waterloti Germain, Bulinus forskali Ehrenberg, Gyraulus costulatus Krauss, Ferrissia sp, Segmentorbis sp. and five prosobranchs namely, Lanistes libycus Morelet, Lanistes ovum Peters, Pila

G. T. Ndifon; F. M. A. Ukoli



Thermal Compensation of Respiration in Pulmonate Snails (Pulmonata) of Arion and Deroceras Genera Living in Polar and Temperate Climatic Zone  

Microsoft Academic Search

Comparison of respiration rate in pulmonate snails living in various climatic zones demonstrated higher constant a in representatives of Arion genus (A. subfuscus and A. fasciatus) from Polar Area (Murmansk Region) as compared to inhabitants of temperate latitudes (Moscow Region). The snails of Deroceras genus (D. reticulatum) from these two climatic zones were indistinguishable by relative standard metabolism. Different effects

A. A. Zotin; N. D. Ozernyuk




Microsoft Academic Search

Room-temperature ionic liquids (ILs) are being promoted as environmentally friendly alternatives to volatile organic solvents currently used by industry. Because ILs are novel and not yet in widespread use, their potential impact on aquatic organisms is unclear. We studied the effects of several ILs on the survivorship and behavior (movement and feeding rates) of the freshwater pulmonate snail, Physa acuta.

Randall J. Bernot; Erin E. Kennedy; Gary A. Lamberti



[Thermal compensation of respiration in pulmonate snails (Pulmonata) of Arion and Deroceras genera living in polar and temperate climatic zone].  


Comparison of respiration rate in pulmonate snails living in various climatic zones demonstrated higher constant a in representatives of Arion genus (A. subfucus and A. fasciatus) from Polar Area (Murmansk Region) as compared to inhabitants of temperate latitudes (Moscow Region). The snails of Deroceras genus (D. reticulatum) from these two climatic zones were indistinguishable by relative standard metabolism. Different effects of climatic thermal conditions on respiration rates in representatives of these two snail genera can be due to their specific biology. Representatives of Deroceras genus are short-cycle synanthropic species, while the snails of Arion genus are long-cycle species living mostly in the forest zone. PMID:12400380

Zotin, A A; Ozerniuk, N D



Freshwater snail consumption and angiostrongyliasis in Malaya.  


A survey of the freshwater snails, Pila scutata and Bellamyia ingallsiana, as food consumed by the local population was carried out in Peninsular Malaysia. Of these two species the first is preferred; the sizes favoured are between 25--40 mm. Pila snails were found to be consumed by the three communities, viz. Malay, Chinese and Indian, in different ways. The various methods of preparing the snails for consumption are described. P. scutata is an intermediate host of the rat-lung worm, Angiostrongylus malaysiensis. As this worm presumably is the causative agent of human eosinophilic meningoencephalitis, the eating habits of the three races in consuming the snail in relation to the epidemiology of the disease was also discussed. PMID:726037

Liat, L B; Fong, Y L; Krishnansamy, M; Ramachandran, P; Mansor, S



Oxygen binding and its allosteric control in hemoglobin of the pulmonate snail, Biomphalaria glabrata.  


Pulmonate snails that experience extreme variations in gas tensions and temperatures possess extracellular, high-molecular mass ( approximately 1.7 x 10(6) Da) hemoglobins (Hbs) that are little known as regards oxygenation and allosteric characteristics. Biomphalaria glabrata hemolymph exhibits a high O2 affinity (half-saturation O2 tension = 6.1 mmHg; pH 7.7, 25 degreesC), pronounced Bohr effect (Bohr factor = -0.5), and pH-dependent cooperativity (Hill's cooperativity coefficient at half-saturation = 1.1-2.0). Divalent cations increase O2 affinity, Ca2+ exerting greater effect than Mg2+. Analyses in terms of the Monod-Wyman-Changeux model indicate novel O2 affinity control mechanisms. In contrast to vertebrate Hb, where organic phosphates and protons lower affinity via decreased O2 association equilibrium constant of Hb in low-affinity state (KT), and to extracellular annelid Hbs, where protons and cations primarily modulate O2 association equilibrium constant of Hb in high-affinity state (KR), in B. glabrata Hb, the Bohr effect is mediated predominantly via KR and the cation effect via KT, reflecting preferential, oxygenation-linked proton binding to oxygenated Hb and cation binding to deoxygenated Hb. CO2 has no specific (pH independent) effect. Nonlinear van't Hoff plots show temperature dependence of the overall heats of oxygenation, indicating oxy-deoxy heat capacity differences. The findings are related to possible physiological significance in pond habitats. PMID:9950911

Bugge, J; Weber, R E



Physiological and biochemical responses to cold and drought in the rock-dwelling pulmonate snail, Chondrina avenacea.  


The pulmonate snail Chondrina avenacea lives on exposed rock walls where it experiences drastic daily and seasonal fluctuations of abiotic conditions and food availability. We found that tolerance to dry conditions was maintained at a very high level throughout the year and was mainly based on the snails' ability to promptly enter into estivation (quiescence) whenever they experienced drying out of their environment. Snails rapidly suppressed their metabolism and minimized their water loss using discontinuous gas exchange pattern. The metabolic suppression probably included periods of tissue hypoxia and anaerobism as indicated by accumulation of typical end products of anaerobic metabolism: lactate, alanine and succinate. Though the drought-induced metabolic suppression was sufficient to stimulate moderate increase of supercooling capacity, the seasonally highest levels of supercooling capacity and the highest tolerance to subzero temperatures were tightly linked to hibernation (diapause). Hibernating snails did not survive freezing of their body fluids and instead relied on supercooling strategy which allowed them to survive when air temperatures dropped to as low as -21 °C. No accumulation of low-molecular weight compounds (potential cryoprotectants) was detected in hibernating snails except for small amounts of the end products of anaerobic metabolism. PMID:23516021

Koštál, Vladimír; Rozsypal, Jan; Pech, Pavel; Zahradní?ková, Helena; Šimek, Petr



Recovery of Pasteurella multocida from experimentally-exposed freshwater snails.  


We determined how long Pasteurella multocida could survive in experimentally-exposed freshwater snails. Physa virginea were collected from the Sacramento National Wildlife Refuge, Glenn County, California (USA), an enzootic site for avian cholera. Exposure to water containing up to 10(7) P. multocida per ml did not produce observable changes or mortality in snails. A minimum of 84 P. multocida per snail was necessary for detection among the normal snail bacterial flora. When snails were exposed to P. multocida in vials containing 10(7) bacteria per ml, P. multocida was detected for up to 72 hours in snails. When uninoculated snails were placed in aquaria containing 10(6) P. multocida per ml, P. multocida was not detected within the snails; further, P. multocida was detected in the water for only 24 hours at this level. Based on these results, we propose that P. virginea is not an effective reservoir for P. multocida. PMID:8592357

Miller, S L; Botzler, R G



The influence of diet on the ? 13C of shell carbon in the pulmonate snail Helix aspersa  

NASA Astrophysics Data System (ADS)

The influence of diet and atmospheric CO 2 on the carbon isotope composition of shell aragonite and shell-bound organic carbon in the pulmonate snail Helix aspersa raised in the laboratory was investigated. Three separate groups of snails were raised on romaine lettuce (C3 plant, ? 13C=-25.8‰), corn (C4 plant, ? 13C=-10.5‰), and sour orange ( 12C-enriched C3 plant, ? 13C=-39.1‰). The isotopic composition of body tissues closely tracked the isotopic composition of the snail diet as demonstrated previously. However, the isotopic composition of the acid insoluble organic matrix extracted from the aragonite shells does not track diet in all groups. In snails that were fed corn the isotopic composition of the organic matrix was more negative than the body by as much as 5‰ whereas the matrix was approximately 1‰ heavier than the body tissues in snails fed a diet of C3 plant material. These results indicate that isotopic composition of the organic matrix carbon cannot be used as an isotopic substrate for paleodietary reconstructions without first determining the source of the carbon and any associated fractionations. The isotopic composition of the shell aragonite is offset from the body tissues by 12.3‰ in each of the culture groups. This offset was not influenced by the consumption of carbonate and is not attributable to the diffusion of atmospheric CO 2 into the hemolymph. The carbon isotopic composition of shell aragonite is best explained in terms of equilibrium fractionations associated with exchange between metabolic CO 2 and HCO 3 in the hemolymph and the fractionation associated with carbonate precipitation. These results differ from previous studies, based primarily on samples collected in the field, that have suggested atmospheric carbon dioxide contributes significantly to the shell ? 13C. The culture results indicate that the ? 13C of aragonite is a good recorder of the isotopic composition of the snail body tissue, and therefore a better recorder of diet than is the insoluble shell organic carbon. Because the systematic fractionation of carbon isotopes within the snail is temperature dependent, the ? 13C of the shell could provide an independent technique for estimating paleotemperature changes.

Stott, Lowell D.



Larval digenean community parasitizing the freshwater snail, Biomphalaria peregrina (Pulmonata: Planorbidae), from a temporary pond in Patagonia, Argentina.  


Knowledge of population dynamics of parasites in freshwater snails from South America is scarce. The objective of the present study was to describe the infection dynamics of larval digeneans in the planorbid snail, Biomphalaria peregrina , during 2 sampling periods in a Patagonian temporary pond. In total, 1,003 snails were examined. Rediae of Notocotylus biomphalariae and Echinoparyphium sp., sporocysts of Cotylurus sp., and metacercariae of the 2 latter species were found. The overall prevalence was significantly higher in the second sampling period, always as single-species infections in the hepatopancreas. The presence of larvae in the first sampled snails of the second hydroperiod indicated that parasitized snails survive drought. Both species exhibited different seasonal prevalence patterns, with Echinoparyphium sp. present in all sampling months. Metacercariae of Echinoparyphium sp. occurred in the heart and kidney, and those of Cotylurus sp. between organs. No significant differences in overall prevalence of metacercariae were found, and a progressive rise in prevalence from spring to summer for both species was observed. Almost all size classes of B. peregrina were infected with metacercariae of both species, but rediae and sporocysts were present only in snails larger than 3.1 mm. The predictability of the hydroperiod year after year, the tolerance of B. peregrina to drought, and the survival of infected specimens allows the parasite community to show a similar pattern of infection over time. This is the first study in Argentina analyzing the infection dynamics of digeneans of a pulmonate snail from a temporary pond. PMID:20557212

Flores, Verónica R; Semenas, Liliana G; Veleizán, Aylén A



Comparative Neurobiology of Feeding in the Opisthobranch Sea Slug, Aplysia, and the Pulmonate Snail, Helisoma: Evolutionary Considerations  

PubMed Central

The motor systems that generate feeding-related behaviors of gastropod mollusks provide exceptional opportunities for increasing our understanding of neural homologies and the evolution of neural networks. This report examines the neural control of feeding in Helisoma trivolvis, a pulmonate snail that ingests food by rasping or scraping material from the substrate, and Aplysia californica, an opisthobranch sea slug that feeds by using a grasping or seizing motion. Two classes of neurons that are present in the buccal ganglia of both species are considered: (1) clusters of peptidergic mechanoafferent cells that transmit sensory information from the tongue-like radula/odontophore complex to the central motor circuit; and (2) sets of octopamine-immunoreactive interneurons that are intrinsic to the feeding network. We review evidence that suggests homology of these cell types and propose that their roles have been largely conserved in the control of food-scraping and food-grasping consummatory behaviors. We also consider significant differences in the feeding systems of Aplysia and Helisoma that are associated with the existence of radular closure in Aplysia, an action that does not occur in Helisoma. It is hypothesized that a major adaptation in the innervation patterns of analogous, possibly homologous muscles could distinguish the food-scraping versus food-grasping species. It appears that although core CPG elements have been largely conserved in this system, the neuromuscular elements that they regulate have been more evolutionarily labile.

Wentzell, Margaret M.; Martinez-Rubio, Clarissa; Miller, Mark W.; Murphy, A. Don



Effects of ionic liquids on the survival, movement, and feeding behavior of the freshwater snail, Physa acuta.  


Room-temperature ionic liquids (ILs) are being promoted as environmentally friendly alternatives to volatile organic solvents currently used by industry. Because ILs are novel and not yet in widespread use, their potential impact on aquatic organisms is unclear. We studied the effects of several ILs on the survivorship and behavior (movement and feeding rates) of the freshwater pulmonate snail, Physa acuta. Median lethal concentrations (LC50s) of ILs with imidazolium- and pyridinium-based cations and Br- and PF6- as anions ranged from 1 to 325 mg/L. Toxicity was greatest for ILs with eight-carbon alkyl chains attached to both imidazolium and pyridinium rings and declined with shorter alkyl chains, indicating a positive relationship between alkyl chain length and toxicity. Compared to controls, snails moved more slowly when exposed to butyl- and hexyl-cation ILs at 1 to 3% of LC50 concentrations but were not affected at higher IL concentrations (4-10% of LC50), which is characteristic of U-shaped dose-response curves. Snail movement was not affected by ILs with octyl alkyl groups. Grazing patterns, however, indicated that snails grazed less at higher IL concentrations. Physa acuta egestion rates were reduced in the presence of ILs at 3 to 10% of LC50 concentrations. Thus, nonlethal IL concentrations affected P. acuta behaviors, potentially impacting individual fitness and food web interactions. These results provide initial information needed to assess the potential hazards of ILs should they reach freshwater ecosystems. PMID:16050594

Bernot, Randall J; Kennedy, Erin E; Lamberti, Gary A



Influence of Age and Body Size on Alarm Responses in a Freshwater Snail Pomacea canaliculata  

Microsoft Academic Search

A hypothesis that size selection of prey by predators elicits size-specific responses from prey was examined. Freshwater snails, Pomacea canaliculata, ages 1, 3, 7, 15, 30, or 60 days, were given an extract of 3-day-old snails, and 3-day-old snails were given extracts of snails of the other ages or eggs. Snails 15 days or younger crawled out of the water

Katsuya Ichinose



Arsenic speciation in freshwater snails and its life cycle variation.  


Terrestrial snails are consumed by humans occasionally and they are an important food source for many creatures including fish and birds. Little is known about arsenic speciation in these gastropods, let alone life cycle variations. Here we report on the arsenic speciation in freshwater snails from Pender Island and Vancouver Island, B.C., Canada, which was determined on methanol/water extracts (43-59% extraction efficiency) by using high performance liquid chromatography-inductively coupled plasma-mass spectrometry (HPLC-ICP-MS) and HPLC-electrospray tandem mass spectrometry. The tetramethylarsonium ion, oxo-arsenosugars and thio-arsenosugars are the main arsenic species encountered. Arsenobetaine, which is commonly found in the marine environment, is minor. Live bearing snails Viviparidae sp. from Pender Island were maintained in aquaria and the arsenic speciation in the unborn, newly born, and adult animals was monitored. Oxo-arsenosugars predominate in the adults, whereas thio-arsenosugars seem to predominate in juveniles, suggesting that these arsenicals are snail metabolites. PMID:22193982

Lai, Vivian W-M; Kanaki, Katerina; Pergantis, Spiros A; Cullen, William R; Reimer, Kenneth J



Efficacy of Euphorbia hirta latex as plant derived molluscicides against freshwater snails.  


The toxic effect of binary and tertiary combinations of Euphorbia hirta Linn latex powder with other plant molluscicidal compounds, were evaluated against the freshwater snails Lymnaea (Radix) acuminata and Indoplanorbis exustus in pond. These combinations showed significant time and dose dependent effect against both the snails. These compounds at higher doses were also lethal to freshwater fish Channa punctatus (Bloch) (Channidae {Ophicephalidae}), which shares the habitat with these snails, but the LC90 (24h) doses of snails have no apparent killing properties in fish populations when treated in mixed population of snails and fish. PMID:21537758

Yadav, Ram P; Singh, Ajay



Selective and universal primers for trematode barcoding in freshwater snails.  


Trematodes are significant pathogens of high medical, veterinary, and environmental importance. They are hard to isolate from their intermediate hosts, and their early life stages are difficult to identify morphologically. Therefore, primers were developed for trematodes to create a species barcoding system and allow selective PCR amplification in mixed samples. The specific oligonucleotide primer was universal for trematodes that infected several freshwater snail species in Israel. The diagnostic tool is based on the 18S rDNA gene. In contrast to morphological identification, trematode barcoding is rapid as it is based on a sequence of only 800 bp, and it classifies species accurately due to high polymorphism between conserved areas. PMID:24781022

Routtu, J; Grunberg, D; Izhar, R; Dagan, Y; Guttel, Y; Ucko, M; Ben-Ami, F



Freshwater snails in Asser region, Saudi Arabia with special refernce to the zoonotic trematode.  


The present study gave information about the recent distribution of freshwater snails in Asser region, and the current status of trematode infection specially schistosomiasis within the snails. Fifteen localities were visited from Septeinber 2007 to December 2008 and the collected snails were examined for the presence of trematode infection. Seven species of snails were collected: Biomphalaria arabica, Bulinus truncatus, Bulinus beccari, Physa acuta, Lymnaea palustris, Lymnaea arabica and Melanoides tuberculata. The parasitological examination revealed none trematode immature stages. PMID:19795761

Bin Dajem, Saad M



Angiostrongylus cantonensis : morphological and behavioral investigation within the freshwater snail Pomacea canaliculata  

Microsoft Academic Search

An infection with Angiostrongylus cantonensis, the main causative agent for human eosinophilic encephalitis, can be acquired through the consumption of the freshwater\\u000a snail Pomacea canaliculata. This snail also provides a suitable model to study the developmental morphology and behavior of A. cantonensis larvae, facilitated by the snail’s distinct lung structure. We used microanatomy for studying the natural appearance and\\u000a behavior

Shan Lv; Yi Zhang; He-Xiang Liu; Chao-Wei Zhang; Peter Steinmann; Xiao-Nong Zhou; Jürg Utzinger



Clonal diversity driven by parasitism in a freshwater snail.  


One explanation for the widespread abundance of sexual reproduction is the advantage that genetically diverse sexual lineages have under strong pressure from virulent coevolving parasites. Such parasites are believed to track common asexual host genotypes, resulting in negative frequency-dependent selection that counterbalances the population growth-rate advantage of asexuals in comparison with sexuals. In the face of genetically diverse asexual lineages, this advantage of sexual reproduction might be eroded, and instead sexual populations would be replaced by diverse assemblages of clonal lineages. We investigated whether parasite-mediated selection promotes clonal diversity in 22 natural populations of the freshwater snail Melanoides tuberculata. We found that infection prevalence explains the observed variation in the clonal diversity of M. tuberculata populations, whereas no such relationship was found between infection prevalence and male frequency. Clonal diversity and male frequency were independent of snail population density. Incorporating ecological factors such as presence/absence of fish, habitat geography and habitat type did not improve the predictive power of regression models. Approximately 11% of the clonal snail genotypes were shared among 2-4 populations, creating a web of 17 interconnected populations. Taken together, our study suggests that parasite-mediated selection coupled with host dispersal ecology promotes clonal diversity. This, in return, may erode the advantage of sexual reproduction in M. tuberculata populations. PMID:24118641

Dagan, Y; Liljeroos, K; Jokela, J; Ben-Ami, F



The influence of TCS on the growth and behavior of the freshwater snail, Physa acuta  

Microsoft Academic Search

Triclosan (TCS) is among the top 10 most persistent contaminants found in U.S. rivers, streams, lakes, and aquifers. Although TCS has not been found to be hazardous to humans, it can be toxic to aquatic environments and animals. The effects of TCS on growth rates and the locomotive behavior of the freshwater snail, Physa acuta, were studied by exposing snails

Jenell Brown; Melody J. Bernot; Randall J. Bernot



Effectors of metabolic depression in an estivating pulmonate snail ( Helix aspersa ): whole animal and in vitro tissue studies  

Microsoft Academic Search

We have examined metabolic depression in the land snail (Helix aspersa) during estivation, and have developed a tissue model of metabolic depression using an in vitro mantle preparation. The metabolic\\u000a rate ofH. aspersa is depressed by 84% in vivo within 4 weeks of onset of estivation, and this metabolic depression is accompanied by a decrease\\u000a in haemolymphPO2 and pH, and

S. Pedler; C. J. Fuery; P. C. Withers; J. Flanigan; M. Guppy



The influence of TCS on the growth and behavior of the freshwater snail, Physa acuta.  


Triclosan (TCS) is among the top 10 most persistent contaminants found in U.S. rivers, streams, lakes, and aquifers. Although TCS has not been found to be hazardous to humans, it can be toxic to aquatic environments and animals. The effects of TCS on growth rates and the locomotive behavior of the freshwater snail, Physa acuta, were studied by exposing snails to a range of environmentally-relevant trace concentrations previously documented in freshwater ecosystems. Effects of TCS on snail growth were calculated using a non-linear regression model, and effects on behavior were determined using a two-way analysis of variance. Environmentally relevant concentrations of TCS (0.5 to 1.0 ?g/L) enhanced Physa growth rates at low concentrations, but slowed growth rates at concentrations greater than 5 ?g/L. Acute exposure did not affect immediate snail behavior; however, chronically exposed snails moved more slowly than naïve snails. These data indicate that concentrations of TCS currently found in freshwater ecosystems can potentially affect the growth and behavior of snails. PMID:22702822

Brown, Jenell; Bernot, Melody J; Bernot, Randall J



Snail Snooping.  

ERIC Educational Resources Information Center

Presents an activity in which students in grades 5-8 learn about snail reproduction by observing and charting the activities of land snails, freshwater snails, and slugs. Instructions to implement and extend the activity are provided. (MDH)

Miller, Dorothy



Physiological response to low temperature in the freshwater apple snail, Pomacea canaliculata (Gastropoda: Ampullariidae).  


Cold hardiness of the freshwater apple snail, Pomacea canaliculata, varies seasonally. We investigated lethal factors and physiological changes arising from exposure of P. canaliculata to low temperatures. Snails did not survive freezing. The supercooling point of cold-acclimated (cold tolerant) snails (-6.6+/-0.8 degrees C) did not differ significantly from that of non-acclimated ones (-7.1+/-1.5 degrees C) under laboratory conditions. Furthermore, snails died even under more moderately low temperatures approaching 0 degrees C. These results indicate that indirect chilling injury is a factor in the death of P. canaliculata at low temperatures. Regardless of whether the snails were acclimated to low temperatures, all of the dead, and even some of the snails still alive at 0 degrees C, had injured mantles, indicating that the mantle may be the organ most susceptible to the effects of low temperatures. The concentration of glucose in the posterior chamber of the kidney and concentration of glycerol in the digestive gland were significantly higher in cold-acclimated snails than in non-acclimated ones, suggesting carbohydrate metabolic pathways are altered in snails during cold acclimation. PMID:19648400

Matsukura, Keiichiro; Tsumuki, Hisaaki; Izumi, Yohei; Wada, Takashi



Epidemiology of cercarial stage of trematodes in freshwater snails from Chiang Mai province, Thailand  

PubMed Central

Objective To investigate the epidemiological situation of cercarial trematodes infection in freshwater snails from different water resources in Chiang Mai province, Thailand. Methods The snail specimens were collected from 13 districts of Chiang Mai province during April 2008 to February 2012. The prevalence of cercarial infection in snails was investigated using the crushing method. The drawing was done with the help of a camera lucida for the morphological study. Results A total of 2?479 snail individuals were collected and classified into 7 families, 11 genera, and 14 species, Among them, 8 snails species were found to be infected with an overall prevalence of 17.27% (428/2?479), which infected with nine groups of cercariae; gymnocephalous cercaria, strigea cercaria, megalurous cercaria, monostome cercaria, parapleurolophocercous cercaria (Haplorchis cercaria), pleurolophocercous cercaria, furcocercous cercaria (Transversotrema cercaria), xiphidiocercaria, and virgulate cercaria. The parapleurolophocercous cercaria was found to be the dominant type among the cercarial infection in the snails (64.25%). Conclusions The various species of snails found in the research location act as the intermediate hosts for the high prevalence of parasitic infection of many species of mammals. This work will provide new information on both the distribution and first intermediate host of trematodes.

Chontananarth, Thapana; Wongsawad, Chalobol



Acute combined exposure to heavy metals (Zn, Cd) blocks memory formation in a freshwater snail.  


The effect of heavy metals on species survival is well documented; however, sublethal effects on behaviour and physiology are receiving growing attention. Measurements of changes in activity and respiration are more sensitive to pollutants, and therefore a better early indicator of potentially harmful ecological impacts. We assessed the effect of acute exposure (48 h) to two heavy metals at concentrations below those allowable in municipal drinking water (Zn: 1,100 ?g/l; Cd: 3 ?g/l) on locomotion and respiration using the freshwater snail, Lymnaea stagnalis. In addition we used a novel assessment method, testing the ability of the snail to form memory in the presence of heavy metals in both intact snails, and also snails that had the osphradial nerve severed which connects a chemosensory organ, the osphradium, to the central nervous system. Aerial respiration and locomotion remained unchanged by acute exposure to heavy metals. There was also no effect on memory formation of these metals when administered alone. However, when snails were exposed to these metals in combination memory formation was blocked. Severing the osphradial nerve prevented the memory blocking effect of Zn and Cd, indicating that the snails are sensing these metals in their environment via the osphradium and responding to them as a stressor. Therefore, assessing the ability of this species to form memory is a more sensitive measure of heavy metal pollution than measures of activity, and indicates that the snails' ability to demonstrate behavioural plasticity may be compromised by the presence of these pollutants. PMID:22218978

Byzitter, Jovita; Lukowiak, Ken; Karnik, Vikram; Dalesman, Sarah



The freshwater snails (Gastropoda) of Iran, with descriptions of two new genera and eight new species  

PubMed Central

Abstract Using published records and original data from recent field work and revision of Iranian material of certain species deposited in the collections of the Natural History Museum Basel, the Zoological Museum Berlin, and Natural History Museum Vienna, a checklist of the freshwater gastropod fauna of Iran was compiled. This checklist contains 73 species from 34 genera and 14 families of freshwater snails; 27 of these species (37%) are endemic to Iran. Two new genera, Kaskakia and Sarkhia, and eight species, i.e., Bithynia forcarti, Bithynia starmuehlneri, Bithynia mazandaranensis, Pseudamnicola georgievi, Kaskakia khorrasanensis, Sarkhia sarabensis, Valvata nowsharensis and Acroloxus pseudolacustris are described as new to science; Ecrobia grimmi (Clessin & Dybowski, 1888), Heleobia dalmatica (Radoman, 1974) and Hippeutis complanatus (Linnaeus, 1758) are reported for the first time from Iran. Additional field work is highly desirable for a more appropriate evaluation of the extant freshwater snail biodiversity in Iran.

Gloer, Peter; Pesic, Vladimir



Zinc sensitivity of a freshwater snail, Lymnaea luteola L. , in relation to seasonal variations in temperature  

SciTech Connect

The aquatic environment has numerous physical and chemical parameters that may influence the physiology and chemical toxicity to freshwater organisms. Temperature is one of the these factors having a marked influence on heavy metal toxicity to fishes and macroinvertebrates. There is a limited and scattered information available on temperature induced changes in acute toxicity of zinc compounds to freshwater pond snails. This information is essential because there are large temperature differences with season and latitudes and the aquatic organisms are subjected to seasonal temperature changes of 20-25/sup 0/C or even more. It is proposed to study the effect of seasonal changes in temperature on zinc toxicity to a freshwater pond snail, Lymnaea luteola (Lamarck), which form an important link in aquatic food chain(s) and are widely distributed in lakes, ponds and rivers of India.

Khangarot, B.S.; Ray, P.K.



Ecotoxicological Effect of Sublethal Exposure to Zinc Oxide Nanoparticles on Freshwater Snail Biomphalaria alexandrina.  


Freshwater snails are used as sensitive biomarkers of aquatic ecosystem pollution. The potential impacts of zinc oxide nanoparticles (ZnONPs) on aquatic ecosystems have attracted special attention due to their unique properties. The present investigation was designed to evaluate the possible mechanisms of ecotoxicological effects of ZnONPs on freshwater snail Biomphalaria alexandrina. ZnONPs showed molluscicidal activity against B. alexandrina snails, and the LC50 was 145 ?g/ml. Two tested concentrations of ZnONPs were selected: The first concentration was equivalent to LC10 (7 ?g/ml), and the second was equivalent to LC25 (35 ?g/ml). Exposure to ZnONPs (7 and 35 ?g/ml) for three consecutive weeks significantly induced malondialdehyde and nitric oxide with concomitant decreases in glutathione and glutathione-S-transferase levels in hemolymph and soft tissues of treated snails. Moreover, ZnONPs elicited a significant decrease in total protein and albumin contents coinciding with enhancement of total lipids and cholesterol levels as well as activities of aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase in hemolymph and soft tissues of treated snails. This study highlights the potential ecological implications of ZnONP release in aquatic environments and may serve to encourage regulatory agencies in Egypt to more carefully monitor and regulate the industrial use and disposal of ZnONPs. PMID:24736985

Fahmy, Sohair R; Abdel-Ghaffar, Fathy; Bakry, Fayez A; Sayed, Dawlat A



Predatory Potential of Freshwater Animals on an Invasive Agricultural Pest, the Apple Snail Pomacea canaliculata (Gastropoda: Ampullariidae), in Southern Japan  

Microsoft Academic Search

The apple snail Pomacea canaliculata is an invasive species and a serious pest of rice in many Asian countries. We studied predatory activities of various animals living in Japanese freshwater habitats, by keeping each individual of a potential predator species with 36 snails of various sizes for three days in the aquarium. Forty-six species were tested, and 26 in eight

Yoichi Yusa; Naoyuki Sugiura; Takashi Wada



Electron Spin Resonance Studies of Mn2+ in Freshwater Snail Shells: Pomacea Canaliculata Lamarck and Fossilized Snail Shell  

NASA Astrophysics Data System (ADS)

We study paramagnetic Mn2+ ions present in the nowadays shells of univalve freshwater snails of Pomacea canaliculata lamarck (PCL) and the fossilized freshwater snail (FFS), Viviparus. All these shells are abundant in Thailand. The PCL shells were ground into fine powder. A set of seven samples were then separately annealed for 2 h in air atmosphere at different annealing temperatures while the FFS powder was characterized as-received. The PCL shells mainly consist of aragonite and a fraction of calcite. The heat treatments of the PCL powder samples at temperature higher than 450 degrees C resulted in an irreversible phase transformation from aragonite to calcite. However, it is found that the FFS shell is mainly made of calcite, with a minor fraction of aragonite. The crystal structure of the high-temperature-annealed PCL samples are quite similar to that of FFS, which indicates that the metamorphosis (aragonite ? calcite) in the FFS shell had occurred but was not yet completed, although it had remained under the pressure and temperature of the Earth's crusts over millions of years. Our detailed ESR spectral analyses of PCL and FFS show that Mn2+ ions enter the Ca2+ sites during a biomineralization process. Simulated ESR parameters of PCL-500 of Mn2+ at a uniaxial site of calcite are reported. It is surprising to find that the ratio of Mn2+ concentration present in FFS to those in PCL shells evaluated from ESR spectra is as much as 10:1.

Udomkan, N.; Meejoo, S.; Limsuwan, P.; Winotai, P.; Chaimanee, Y.



Failure of transmission of low-pathogenic avian influenza virus between Mallards and freshwater snails: an experimental evaluation.  


In aquatic bird populations, the ability of avian influenza (AI) viruses to remain infectious in water for extended periods provides a mechanism that allows viral transmission to occur long after shedding birds have left the area. However, this also exposes other aquatic organisms, including freshwater invertebrates, to AI viruses. Previous researchers found that AI viral RNA can be sequestered in snail tissues. Using an experimental approach, we determined whether freshwater snails (Physa acuta and Physa gyrina) can infect waterfowl with AI viruses by serving as a means of transmission between infected and naïve waterfowl via ingestion. In our first experiment, we exposed 20 Physa spp. snails to an AI virus (H3N8) and inoculated embryonated specific pathogen-free (SPF) chicken eggs with the homogenized snail tissues. Sequestered AI viruses remain infectious in snail tissues; 10% of the exposed snail tissues infected SPF eggs. In a second experiment, we exposed snails to water contaminated with feces of AI virus-inoculated Mallards (Anas platyrhynchos) to evaluate whether ingestion of exposed freshwater snails was an alternate route of AI virus transmission to waterfowl. None of the immunologically naïve Mallards developed an infection, indicating that transmission via ingestion likely did not occur. Our results suggest that this particular trophic interaction may not play an important role in the transmission of AI viruses in aquatic habitats. PMID:24502718

Oesterle, Paul T; Huyvaert, Kathryn P; Orahood, Darcy; Mooers, Nicole; Sullivan, Heather; Franklin, Alan B; Root, J Jeffrey



Exposure to parasites increases promiscuity in a freshwater snail  

PubMed Central

Under the Red Queen hypothesis, outcrossing can produce genetically variable progeny, which may be more resistant, on average, to locally adapted parasites. Mating with multiple partners may enhance this resistance by further increasing the genetic variation among offspring. We exposed Potamopyrgus antipodarum to the eggs of a sterilizing, trematode parasite and tested whether this altered mating behaviour. We found that exposure to parasites increased the number of snail mating pairs and the total number of different mating partners for both males and females. Thus, our results suggest that, in host populations under parasite-mediated selection, exposure to infective propagules increases the rate of mating and the number of mates.

Soper, D. M.; King, K. C.; Vergara, D.; Lively, C. M.



Exposure to parasites increases promiscuity in a freshwater snail.  


Under the Red Queen hypothesis, outcrossing can produce genetically variable progeny, which may be more resistant, on average, to locally adapted parasites. Mating with multiple partners may enhance this resistance by further increasing the genetic variation among offspring. We exposed Potamopyrgus antipodarum to the eggs of a sterilizing, trematode parasite and tested whether this altered mating behaviour. We found that exposure to parasites increased the number of snail mating pairs and the total number of different mating partners for both males and females. Thus, our results suggest that, in host populations under parasite-mediated selection, exposure to infective propagules increases the rate of mating and the number of mates. PMID:24759366

Soper, D M; King, K C; Vergara, D; Lively, C M



Prevalence and intensity of Angiostrongylus cantonensis in freshwater snails in relation to some ecological and biological factors.  


The purpose of the study was to record different intermediate hosts of A. cantonensis and to determine the infection prevalence and intensity of this parasite in freshwater snails in relation to some ecological and biological factors. The study was conducted at Al-Salam irrigation Canal and Al-Abtal village (north Sinai) for one year, from March 2004 to February 2005. Thirteen species of freshwater snails of nine families were examined for A. cantonensis infection. Six species were found infected with A. cantonensis larvae. These species were L. carinatus, C. bulimoides, C. cyclostomoides, B. alexandrina, L. natalensis and M. tuberculta. The infection prevalence of A. cantonensis in the examined snails ranged from 0.63 to 2.24%. L. carinatus snail had the highest prevalence, mean abundance and mean intensity of A. cantonensis infection. Positive correlations were found between both prevalence and mean abundance of A. cantonensis and host size in L. carinatus and M. tuberculata. Negative correlations were detected between salinity and prevalence, mean abundance and mean intensity of larvae of A. cantonensis. The results demonstrated seasonal and spatial variation in the prevalence, mean abundance and mean intensity of infection among examined snails. In this study, A. cantonensis larvae were found in a wide range of freshwater snails and M. tuberculata snail was recorded as a new intermediate host for the first time. In conclusion, further investigations in other areas and controlled laboratory experiments of infection approaches are required to evaluate the possible threat of this parasite on humans. PMID:17432058

Ibrahim, M M



Echinostoma revolutum: Freshwater Snails as the Second Intermediate Hosts in Chiang Mai, Thailand  

PubMed Central

The occurrence of 37-collar spined echinostome metacercariae in freshwater snails was investigated in 6 districts of Chiang Mai Province, Thailand, from October 2011 to April 2012. A total of 2,914 snails that belong to 12 species were examined, and 7 snail species (Clea helena, Eyriesia eyriesi, Bithynia funiculata, Bithynia siamensis siamensis, Filopaludina doliaris, Filopaludina sumatrensis polygramma, and Filopaludina martensi martensi) were found infected with echinostome metacercariae. The prevalence of metacercariae was the highest in Filopaludina spp. (38.5-58.7%) followed by B. funiculata (44.0%), E. eyriesi (12.5%), B. siamensis siamensis (8.2%), and C. helena (5.1%). Metacercariae were experimentally fed to hamsters and domestic chicks, and adult flukes were recovered from both hosts at days 15 and 20 post-infection. The adult flukes were identified based on morphological features, morphometrics, host-parasite relationships, and geographical distribution. They were compatible to Echinostoma revolutum or Echinostoma jurini, with only minor differences. As the adults were recovered from both hamsters and chicks, our specimens were more compatible to E. revolutum rather than E. jurini (reported only from mammals). This is the first report for metacercariae of E. revolutum in the snail host, C. helena, and also confirmed that Filopaludina spp., E. eryresi, and Bithynia spp. act as the second intermediate hosts of E. revolutum under natural conditions, which are indigenously distributed in Chiang Mai province.

Chantima, Kittichai; Chai, Jong-Yil



Changes in chemical components in the freshwater apple snail, Pomacea canaliculata (Gastropoda: Ampullariidae), in relation to the development of its cold hardiness  

Microsoft Academic Search

The apple snail, Pomacea canaliculata, is an invasive freshwater snail. It increases its cold hardiness before winter. However, the physiological mechanism of cold hardiness in molluscs is poorly understood, especially in freshwater molluscs. In this study, we examined the changes in low molecular weight compounds, glycogen and lipids, in the body of P. canaliculata in association with the development of

Keiichiro Matsukura; Hisaaki Tsumuki; Yohei Izumi; Takashi Wada



Secondary production and diet of an invasive snail in freshwater wetlands: implications for resource utilization and competition  

Microsoft Academic Search

Invasive species can monopolize resources and thus dominate ecosystem production. In this study we estimated secondary production\\u000a and diet of four populations of Pomacea canaliculata, a freshwater invasive snail, in wetlands (abandoned paddy, oxbow pond, drainage channel, and river meander) in monsoonal\\u000a Hong Kong (lat. 22°N). Apple snail secondary production (ash-free dry mass [AFDM]) ranged from 165.9 to 233.3 g m?2 year?1, and

King Lun Kwong; David Dudgeon; Pak Ki Wong; Jian-Wen Qiu



The symbiont Capsaspora owczarzaki, nov. gen. nov. sp., isolated from three strains of the pulmonate snail Biomphalaria glabrata is related to members of the Mesomycetozoea.  


While investigating the resistance of some strains of Biomphalaria glabrata to infection with Schistosoma mansoni, a unicellular eukaryotic symbiont was noted in the snail haemolymph. It was similar in appearance to Nuclearia sp. reported from B. glabrata. Sequences comprising the 18S, ITS1, 5.8S, ITS2 and the beginning of the 28S rDNA gene regions were obtained from symbionts isolated from three strains of B. glabrata, and compared with the same sequences obtained from a culture of Nuclearia sp. 18S rDNA sequences were identical for all four isolates. 18S rDNA sequences were used in a phylogenetic analysis to produce minimum evolution, maximum parsimony, maximum likelihood and Bayesian trees. All four analyses indicated that the B. glabrata symbiont is not closely related to Nuclearia but instead to the Mesomycetozoea, a recently recognised clade of symbiotic eukaryotes. Based on phylogenetic analysis, life history and morphological differences, the symbiont is described as a new genus and species, Capsaspora owczarzaki. Distinguishing characters are the presence of life cycle stage(s) that occur within snail haemolymph; ability to kill and ingest digenetic trematode larvae; ability to undergo asexual fission to produce daughter cells; absence of flagella, a mucous sheath and membranes containing chitin, elastin, or collagen; and presence of long unbranching pseudopodia and a penetration process. Using both polymerase chain reaction (PCR) and culturing techniques, the S. mansoni-resistant Salvador and 13-16-R1 strains were found to be significantly more likely to harbour the symbiont than the susceptible M line strain. Small but consistent sequence differences were noted among symbiont isolates from different snail strains, raising the possibility that the symbiont has diverged in different snail lineages. This suggests further that the symbiont is not restricted to albino lab-reared snails. A role, if any, of the symbiont in resistance awaits further study. PMID:12117501

Hertel, Lynn A; Bayne, Christopher J; Loker, Eric S



Angiostrongylus cantonensis: morphological and behavioral investigation within the freshwater snail Pomacea canaliculata.  


An infection with Angiostrongylus cantonensis, the main causative agent for human eosinophilic encephalitis, can be acquired through the consumption of the freshwater snail Pomacea canaliculata. This snail also provides a suitable model to study the developmental morphology and behavior of A. cantonensis larvae, facilitated by the snail's distinct lung structure. We used microanatomy for studying the natural appearance and behavior of A. cantonensis larvae while developing within P. canaliculata. The distribution of refractile granules in the larval body and characteristic head structures changed during the developmental cycle. Two well-developed, rod-like structures with expanded knob-like tips at the anterior part were observed under the buccal cavity as early as the late second developmental stage. A "T"-shaped structure at the anterior end and its tenacity distinguished the outer sheath from that shed during the second molting. Early first-stage larvae obtained from fresh rat feces are free moving and characterized by a coiled tail, whereas a mellifluous "Q"-movement was the behavioral trait of third-stage A. cantonensis larvae outside the host tissue. In combination, the distribution of refractive granules, distinct head features, variations in sheaths, and behavioral characteristics can be utilized for differentiation of larval stages, and for distinguishing A. cantonensis larvae from those of other free-living nematodes. PMID:19172296

Lv, Shan; Zhang, Yi; Liu, He-Xiang; Zhang, Chao-Wei; Steinmann, Peter; Zhou, Xiao-Nong; Utzinger, Jürg



Response to Phosphorus Limitation Varies among Lake Populations of the Freshwater Snail Potamopyrgus antipodarum  

PubMed Central

Local adaptation – typically recognized as higher values of fitness-related traits for native vs. non-native individuals when measured in the native environment - is common in natural populations because of pervasive spatial variation in the intensity and type of natural selection. Although local adaptation has been primarily studied in the context of biotic interactions, widespread variation in abiotic characteristics of environments suggests that local adaptation in response to abiotic factors should also be common. Potamopyrgus antipodarum, a freshwater New Zealand snail that is an important model system for invasion biology and the maintenance of sexual reproduction, exhibits local adaptation to parasites and rate of water flow. As an initial step to determining whether P. antipodarum are also locally adapted to phosphorus availability, we examined whether populations differ in their responses to phosphorus limitation. We found that field-collected juvenile P. antipodarum grew at a lower rate and reached an important size threshold more slowly when fed a relatively low vs. a relatively high- phosphorus diet. We also detected significant across-population variation in individual growth rate. A marginally significant population-by-dietary phosphorus interaction along with a two-fold difference across populations in the extent of suppression of growth by low phosphorus suggests that populations of P. antipodarum may differ in their response to phosphorus limitation. Local adaptation may explain this variation, with the implication that snails from lakes with relatively low phosphorus availability should be less severely affected by phosphorus limitation than snails from lakes with higher phosphorus availability.

Krist, Amy C.; Kay, Adam D.; Larkin, Katelyn; Neiman, Maurine



Microsatellites and the Genetics of Highly Selfing Populations in the Freshwater Snail Bulinus Truncatus  

PubMed Central

Hermaphrodite tropical freshwater snails provide a good opportunity to study the effects of mating system and genetic drift on population genetic structure because they are self-fertile and they occupy transient patchily distributed habitats (ponds). Up to now the lack of detectable allozyme polymorphism prevented any intrapopulation studies. In this paper, we examine the consequences of selfing and bottlenecks on genetic polymorphism using microsatellite markers in 14 natural populations (under a hierarchical sampling design) of the hermaphrodite freshwater snail Bulinus truncatus. These population genetics data allowed us to discuss the currently available mutation models for microsatellite sequences. Microsatellite markers revealed an unexpectedly high levels of genetic variation with <=41 alleles for one locus and gene diversity of 0.20-0.75 among populations. The values of any estimator of F(is) indicate high selfing rates in all populations. Linkage disequilibria observed at all loci for some populations may also indicate high levels of inbreeding. The large extent of genetic differentiation measured by F(st), R(st) or by a test for homogeneity between genic distributions is explained by both selfing and bottlenecks. Despite a limited gene flow, migration events could be detected when comparing different populations within ponds.

Viard, F.; Bremond, P.; Labbo, R.; Justy, F.; Delay, B.; Jarne, P.



Understanding the regulation of estivation in a freshwater snail through iTRAQ-based comparative proteomics.  


The apple snail Pomacea canaliculata is a freshwater gastropod with a remarkable ability to withstand seasonal or unpredictable dry conditions by entering estivation. Studies of P. canaliculata using conventional biochemical and the individual gene approaches have revealed the expressional changes of several enzymes and antioxidative genes in response to estivation and arousal. In this study, we applied iTRAQ-coupled two-dimensional LC-MS/MS to identify and quantify the global protein expression during the estivation and arousal of P. canaliculata. A total of 1040 proteins were identified, among which 701 proteins were quantified and compared across four treatments (i.e., control, active snails; short-term estivation, 3 days of exposure to air; prolonged estivation, 30 days of exposure to air; and arousal, 6 h after resubmergence in water) revealing 53 differentially expressed proteins. A comparison of protein expression profiles across treatments indicated that the proteome of this species was very insensitive to initial estivation, with only 9 proteins differentially expressed as compared with the control. Among the 9 proteins, the up-regulations of two immune related proteins indicated the initial immune response to the detection of stress cues. Prolonged estivation resulted in many more differentially expressed proteins (47 compared with short-term estivation treatment), among which 16 were down-regulated and 31 were up-regulated. These differentially expressed proteins have provided the first global picture of a shift in energy usage from glucose to lipid, prevention of protein degradation and elevation of oxidative defense, and production of purine for uric acid production to remove toxic ammonia during prolonged estivation in a freshwater snail. From prolonged estivation to arousal, only 6 proteins changed their expression level, indicating that access to water and food alone is not a necessary condition to reactivate whole-sale protein expression. A comparison with hibernation and diapause revealed many similar molecular mechanisms of hypometabolic regulation across the animal kingdom. PMID:24088062

Sun, Jin; Mu, Huawei; Zhang, Huoming; Chandramouli, Kondethimmanahalli H; Qian, Pei-Yuan; Wong, Chris Kong Chu; Qiu, Jian-Wen



DNA Barcode Identification of Freshwater Snails in the Family Bithyniidae from Thailand  

PubMed Central

Freshwater snails in the family Bithyniidae are the first intermediate host for Southeast Asian liver fluke (Opisthorchis viverrini), the causative agent of opisthorchiasis. Unfortunately, the subtle morphological characters that differentiate species in this group are not easily discerned by non-specialists. This is a serious matter because the identification of bithyniid species is a fundamental prerequisite for better understanding of the epidemiology of this disease. Because DNA barcoding, the analysis of sequence diversity in the 5’ region of the mitochondrial COI gene, has shown strong performance in other taxonomic groups, we decided to test its capacity to resolve 10 species/ subspecies of bithyniids from Thailand. Our analysis of 217 specimens indicated that COI sequences delivered species-level identification for 9 of 10 currently recognized species. The mean intraspecific divergence of COI was 2.3% (range 0-9.2 %), whereas sequence divergences between congeneric species averaged 8.7% (range 0-22.2 %). Although our results indicate that DNA barcoding can differentiate species of these medically-important snails, we also detected evidence for the presence of one overlooked species and one possible case of synonymy.

Kulsantiwong, Jutharat; Prasopdee, Sattrachai; Ruangsittichai, Jiraporn; Ruangjirachuporn, Wipaporn; Boonmars, Thidarut; Viyanant, Vithoon; Pierossi, Paola; Hebert, Paul D. N.; Tesana, Smarn



Field observations of the alarm response to crushed conspecifics in the freshwater snail Pomacea canaliculata : effects of habitat, vegetation, and body size  

Microsoft Academic Search

The freshwater snail Pomacea canaliculata shows alarm responses to chemical cues released from injured conspecifics, but its behavioural responses in the field are\\u000a unknown. We investigated effects of habitat (canals or paddy fields), vegetation, and body size on alarm responses in the\\u000a field. Snails responded to crushed conspecifics within 4 min by burying themselves, but the proportions of self-buried snails\\u000a were

Kahori Aizaki; Yoichi Yusa



Electron Spin Resonance Studies of Mn2+ in Freshwater Snail Shells:  

NASA Astrophysics Data System (ADS)

We have studied paramagnetic Mn2+ ions present in the shells of today's univalve freshwater snails, Sinotaia ingallsiana (FS), Pila ampullaceal (PA), Pomacea canaliculata lamarck (PCL) and the fossilized freshwater snail (FFS), Viviparus which are abundant in Thailand. The FS, PA and AG shells in our study were ground into fine powder. A set of seven samples was each then separately annealed for 2 hours in air atmosphere at 300°C, 400°C, 450°C, 500°C, 550°C, 600°C and 900°C, respectively, while the FFS powder was characterized as received. The FS, PA and PCL shells mainly consist of aragonite and a fraction of calcite. The heat treatments higher than 450°C of the FS, PA and PCL powder samples resulted in an irreversible phase transformation from aragonite to calcite. However, it is found that the FFS shell is mainly made of calcite, with a minor fraction of aragonite. The crystal structure of high temperature annealed FS, PA and PCL samples are quite similar to that of FFS, which indicates that the metamorphosis (aragonite ? calcite) in the FFS shell had occurred but not yet completed, although they remained under the pressure and temperature of the Earth's crust over millions of years. Our detailed ESR spectral analyses of FS, PA, PCL and FFS show that Mn2+ ions enter Ca2+ sites during a biomineralization process. Typical simulated ESR parameters of FS-500 of Mn2+ at a uniaxial site of calcite are gx=gy=2.078±0.001, gz=2.002±0.001, Ax=Ay=87.50±1.00 G, Az=89.00±1.00 G and D=115±1 G, respectively. It is surprising to find that the ratio of Mn2+ concentration present in FFS to those in FS, PA and PCL shells evaluated from ESR spectra is as much as 10:1. It is thus possible to gain some insight of manganese incorporation into the freshwater shells during the biomineralization process.

Meejoo, S.; Udomkan, N.; Winotai, P.; Chaimanee, Y.


Sediment copper bioavailability to freshwater snails in south Florida: risk implications for the Everglade snail kite (Rostrhamus sociabilis plumbeus).  


Many properties being acquired as part of the Comprehensive Everglades Restoration Plan (CERP) are heavily contaminated with copper. Estimated copper bioaccumulation in the Florida apple snail (Pomacea paludosa) has led to the prediction of risk to the Everglade snail kite (Rostrhamus sociabilis plumbeus) at some CERP projects. Field study results presented in this paper examine the relationship between copper levels in sediments, snails, and other biota. Copper concentrations in all biota (snails, aquatic vascular plants, and periphyton) were strongly correlated with those in sediments. No correlation with water copper concentrations was evident. Mean copper concentrations in snails ranged from 23.9 mg/kg at the reference site to 732 mg/kg at a high copper site. Calculated biota-sediment accumulation factors (BSAFs) ranged from 36.7 to 7.0 over the range of copper levels in sediments. BSAFs were highest at low copper levels in sediments and declined sharply as copper levels in sediment increased. Risk for the snail kite is discussed in light of the results of this study. PMID:18679796

Frakes, Robert A; Bargar, Timothy A; Bauer, Emily A



Studies on the morphology of cercariae obtained from freshwater snails at Erawan Waterfall, Erawan National Park, Thailand.  


The morphology of cercariae of freshwater snails from Erawan Waterfall, Erawan National Park, Kanchanaburi Province was studied between December 2002 and August 2003. The snail samples were collected by handpicking using a counts per unit of time sampling method. The cercariae, larva stage of a trematode, were investigated using the shedding method where they were categorized into three groups and six species. The first group, Pleurolophocercous cercariae, consists of Haplorchis pumillo (C1) and Stictodora tridactyla (C3). The second group, Furcocercous cercariae, consisted of Mesostephanus appendicalatus (C2), Transversotrema laruei (C6) and Cardicola alseae(C4). The third group, Xiphidio cercariae, has only one species which is Loxogenoides bicolor (C5). Out of 1163 snails, only 62 were found to be infected by cercariae, equivalent to a 5.33% infection rate. The infections grouped by species of the cercariae are as follows: C, 22 (1.9%), C, 29 (2.5%), C2 1 (0.1%), C6 1 (0.1%), C4 6 (0.5%) and C5 3 (0.3%). The freshwater snail samples consist of four species. From a total of 1163 samples, there are 687 Melanoides jugicostis, 91 Tarebia granifera, 296 Thiara scabra and 89 Melanoides tuberculata. Infections were found in 45 (6.5%), 6 (6.6%), 1 (0.3%) and 10 (11.2%), respectively. PMID:17539280

Ukong, Suluck; Krailas, Duangduen; Dangprasert, Tunyarut; Channgarm, Pasapong



Toxic Effects of Cadmium on Reproduction, Development, and Hatching in the Freshwater Snail Lymnaea stagnalisfor Water Quality Monitoring  

Microsoft Academic Search

The freshwater snailLymnaea stagnaliswas exposed to cadmium concentrations of 0, 25, 50, 100, 200, and 400 ?g liter?1. The influence of this highly toxic metal on various stages of reproduction (number of egg masses, number of eggs, embryo development, and hatching) was studied. Egg production ceased at 400 ?g Cd2+liter?1and hatching was reduced to 0.4% with 200 ?g liter?1at 20°C.

Annette Gomot



The Structure of the Statocyst of the Freshwater Snail Biomphalaria Glabrata (Pulmonata, Basommatophora)  

NASA Technical Reports Server (NTRS)

The structure of the statocyst of the freshwater snail Biomphalaria glabrata has been examined by light and electron microscopy. The two statocysts are located on the dorsal-lateral side of the left and right pedal ganglion. The statocysts are spherical, fluid-filled capsules with a diameter of approximately 60 microns for young and 110 microns for adult snails. The wall of the cyst is composed of large receptor cells and many smaller supporting cells. The receptor cells bear cilia which are evenly distributed on the apical surface. The cilia have the typical 9+2 internal tubule configuration. Striate rootlets originate from the base of the basal body and run downward into the cytoplasm. Side-roots arise from one side of the basal body and a basal foot from the other. For each receptor cell, the basal foot always points to the periphery of the surface, indicating that the receptor cell is non-polarized. The receptor cells contain cytoplasmic organelles such as mitochondria, ribosomes, rough and smooth endoplasmic reticulum, compact Golgi bodies and multivesicular bodies. Supporting cells bearing microvilli are interposed between the receptor cells. The junction complex between the supporting cells and the receptor cells is composed of adherens and septate junctions, while between supporting cells only the adherens junctions are present. The static nerve arises from the lateral side of the cyst and contains axons in which parallel neurotubules and mitochondria are found. The axons arise directly from the base of the receptor cells without synapse. In the cyst lumen there are unattached statoconia. The statoconia have a plate-like or concentric membranous ring structure. Based on the morphology, the function of the statocyst in Biomphalaria is discussed.

Gao, Wenyuan; Wiederhold, Michael L.



No evidence for a critical salinity threshold for growth and reproduction in the freshwater snail Physa acuta.  


The growth and reproduction of the freshwater snail Physa acuta (Gastropoda: Physidae) were measured at various salinity levels (growth: distilled water, 50, 100, 500, 1000 and 5000 microS/cm; reproduction: deionized water, 100, 500, 1000 and 3000 microS/cm) established using the artificial sea salt, Ocean Nature. This was done to examine the assumption that there is no direct effect of salinity on freshwater animals until a threshold, beyond which sub-lethal effects, such as reduction in growth and reproduction, will occur. Growth of P. acuta was maximal in terms of live and dry mass at salinity levels 500-1000 microS/cm. The number of eggs produced per snail per day was maximal between 100 and 1000 microS/cm. Results show that rather than a threshold response to salinity, small rises in salinity (from low levels) can produce increased growth and reproduction until a maximum is reached. Beyond this salinity, further increases result in a decrease in growth and reproduction. Studies on the growth of freshwater invertebrates and fish have generally shown a similar lack of a threshold response. The implications for assessing the effects of salinisation on freshwater organisms need to be further considered. PMID:15620583

Kefford, Ben J; Nugegoda, Dayanthi



Selfing, sexual polymorphism and microsatellites in the hermaphrodititic freshwater snail Bulinus truncatus  

PubMed Central

Studies on the evolution of self-fertilization and sexual polymorphisms (the co-occurrence of several sexual morphs in a species) have focused on plants. Aphally, a sexual polymorphism occurring in gastropods, offers the opportunity to extend study of these issues to animals. We present progeny-array analyses of the selfing rate and correlated matings in the tropical freshwater snail Bulinus truncatus. This study is based on 447 offspring originating from 57 families and five natural populations. To overcome the lack of allozyme polymorphism, four polymorphic microsatellite markers were used. Selfing rates higher than 78 per cent were detected in all populations, and no correlation with the aphally ratio (the proportion of individuals lacking the male copulatory organ per population) was evident. Outcrossing was detected in 17 families only, and individual outcrossing rates were variable and did not depend on the sexual morph of the mother. These results illustrate the power of microsatellites for detailed genetic studies, indicate that high selfing rates may have a strong genetic basis, and unexpectedly suggest that phally polymorphism may be neutral with respect to selfing.

Viard, F.; Doums, C.; Jarne, P.



Neuro-Endocrine Control of Reproduction in Hermaphroditic Freshwater Snails: Mechanisms and Evolution  

PubMed Central

Invertebrates are used extensively as model species to investigate neuro-endocrine processes regulating behaviors, and many of these processes may be extrapolated to vertebrates. However, when it comes to reproductive processes, many of these model species differ notably in their mode of reproduction. A point in case are simultaneously hermaphroditic molluscs. In this review I aim to achieve two things. On the one hand, I provide a comprehensive overview of the neuro-endocrine control of male and female reproductive processes in freshwater snails. Even though the focus will necessarily be on Lymnaea stagnalis, since this is the best-studied species in this respect, extensions to other species are made wherever possible. On the other hand, I will place these findings in the actual context of the whole animal, after all these are simultaneous hermaphrodites. By considering the hermaphroditic situation, I uncover a numbers of possible links between the regulation of the two reproductive systems that are present within this animal, and suggest a few possible mechanisms via which this animal can effectively switch between the two sexual roles in the flexible way that it does. Evidently, this opens up a number of new research questions and areas that explicitly integrate knowledge about behavioral decisions (e.g., mating, insemination, egg laying) and sexual selection processes (e.g., mate choice, sperm allocation) with the actual underlying neuronal and endocrine mechanisms required for these processes to act and function effectively.

Koene, Joris M.



A laboratory and in situ postexposure feeding assay with a freshwater snail.  


Contaminant-driven feeding inhibition has direct and immediate consequences at higher levels of biological organization, by depressing the population consumption and thus hampering ecosystem functioning (e.g., grazing, organic matter decomposition). The present study aimed at developing a short-term laboratory and in situ assay based on the postexposure feeding of the freshwater snail Theodoxus fluviatilis. A method to precisely quantify feeding rates was first developed, consisting of a 3-h feeding period, in darkness, on 150 defrosted nauplii of the brine shrimp Artemia franciscana. Postexposure feeding after a 48-h exposure to cadmium was approximately as sensitive as survival, with the median effective concentration (EC50) and median lethal concentration (LC50) being 85?µg/L and 102?µg/L, respectively, and the 20% effective concentration (EC20) and 20% lethal concentration (LC20) being 41?µg/L and 77?µg/L, respectively. Together, both effects at the LC20 reduced population consumption by 56%. In situ experiments at reference sites covering broad ranges of current velocity, hardness, conductivity, sediment organic matter content, and sediment particle size distribution revealed the influence of these abiotic conditions on postexposure feeding, in the absence of contamination, to be negligible. The effectiveness of the in situ assay was evaluated at 5 sites contaminated with acid mine drainage. Surviving organisms at the single partially lethal site (37% mortality) presented a 54% feeding inhibition relative to the reference, whereas the population consumption would be inhibited by 71%, confirming the integration of survival and feeding to be pertinent for estimating contaminant effects at higher levels of biological organization. PMID:23733247

Correia, Vânia; Ribeiro, Rui; Moreira-Santos, Matilde



Changes in chemical components in the freshwater apple snail, Pomacea canaliculata (Gastropoda: Ampullariidae), in relation to the development of its cold hardiness.  


The apple snail, Pomacea canaliculata, is an invasive freshwater snail. It increases its cold hardiness before winter. However, the physiological mechanism of cold hardiness in molluscs is poorly understood, especially in freshwater molluscs. In this study, we examined the changes in low molecular weight compounds, glycogen and lipids, in the body of P. canaliculata in association with the development of cold hardiness. When snails without cold hardiness were experimentally cold-acclimated, the amount of glycerol, glutamine, and carnosine increased, while glycogen and phenylalanine decreased. Overwintering cold-tolerant snails collected from a drained paddy field in November also showed increased glycerol in their bodies with decreasing glycogen concentration, compared to summer snails collected from a submerged field. Water content also decreased during the cold acclimation, although the water loss was minimal. These results indicate that the freshwater snail, P. canaliculata enhances cold hardiness by accumulation of some kinds of low molecular weight compounds in its body as some insects do. However, the actual function of each low molecular compound is still unknown. PMID:18190902

Matsukura, Keiichiro; Tsumuki, Hisaaki; Izumi, Yohei; Wada, Takashi



The Effect of Aquatic Plant Abundance on Shell Crushing Resistance in a Freshwater Snail  

PubMed Central

Most of the shell material in snails is composed of calcium carbonate but the organic shell matrix determines the properties of calcium carbonate crystals. It has been shown that the deposition of calcium carbonate is affected by the ingestion of organic compounds. We hypothesize that organic compounds not synthesized by the snails are important for shell strength and must be obtained from the diet. We tested this idea indirectly by evaluating whether the abundance of the organic matter that snails eat is related to the strength of their shells. We measured shell crushing resistance in the snail Mexipyrgus churinceanus and the abundance of the most common aquatic macrophyte, the water lily Nymphaea ampla, in ten bodies of water in the valley of Cuatro Ciénegas, Mexico. We used stable isotopes to test the assumption that these snails feed on water lily organic matter. We also measured other factors that can affect crushing resistance, such as the density of crushing predators, snail density, water pH, and the concentration of calcium and phosphorus in the water. The isotope analysis suggested that snails assimilate water lily organic matter that is metabolized by sediment bacteria. The variable that best explained the variation in crushing resistance found among sites was the local abundance of water lilies. We propose that the local amount of water lily organic matter provides organic compounds important in shell biomineralization, thus determining crushing resistance. Hence, we propose that a third trophic level could be important in the coevolution of snail defensive traits and predatory structures.

Chaves-Campos, Johel; Coghill, Lyndon M.; Garcia de Leon, Francisco J.; Johnson, Steven G.



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Biochemical responses to the toxicity of the biocide abamectin on the freshwater snail Physa acuta.  


The toxic effects of abamectin (ABM), an anthelmintic drug, on the snail, Physa Acuta, and the biochemical responses to the exposure stress were evaluated. The activities of superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), acetylcholinesterase (AChE), and nitric oxide synthase (NOS), and the contents of malondialdehyde (MDA) were determined in snail soft tissues (head, foot, visceral mass, and the mantle) for up to 96h of exposure to 3.4, 9.6, 19.2, or 27.4?gL(-1) of ABM. The results showed that SOD and GST activities were promoted by ABM-exposure at the earlier periods of treatment (12-48h) while these activites were inhibited at the end of test. The tendency of CAT activity was similar to that of SOD, but it increased at the end of test. MDA levels of the snail soft tissues increased in all treatment groups, including the recovery group, indicating that lipid peroxidation occurred in snail soft tissues. ABM-exposure inhibited AChE activity. However, NOS activities increased by ABM-exposure. In addition, activities of antioxidant enzymes and AChE from the snail soft tissues resumed the normal levels after 96h of recovery period, but MDA level did not attain the original level. This study provides information on the biochemical mechanism of ABM toxicity on the snail. PMID:24507123

Ma, Junguo; Zhou, Chune; Li, Yao; Li, Xiaoyu



Immunological and molecular detection of digenetic infections in different species of Egyptian freshwater snails.  


Due to the possibility of utilizing different snails in the combat of Schistosoma in Egypt; it is important to study the role it may play in transmitting other trematodes of medical and veterinary importance. Taking this background into consideration, polymerase chain reaction (PCR) assay was designed to identify trematode species at larval stages in intermediate hosts (cercariae in snails) using a combination of standard and molecular methods. This PCR assay was also applied to naturally infected molluscan in order to assess the use of the procedure for detection. The importance of the present study was to demonstrate the epidemiological situation and application in control. PMID:23697024

Saad, Abdel-Hakim; Varjabedian, Kohar G; Abdel-Gaber, Rewaida A; Hassan, Hany M; Abdel-Halim, Noha T



Use of DGT and conventional methods to predict sediment metal bioavailability to a field inhabitant freshwater snail (Bellamya aeruginosa) from Chinese eutrophic lakes.  


In this study, we used the diffusive gradients in thin films (DGT) and conventional methods (including SEM-AVS models, BCR sequential extraction and total metal concentrations) to assess sediment Cr, Ni, Cu, Zn, Cd and Pb bioavailability to field inhabitant freshwater snails (Bellamya aeruginosa) from Chinese eutrophic lakes. The performance of these methods and the relationship between DGT measurements and conventional methods were evaluated. The results showed that DGT-measured metal concentrations have weak correlations with results from tests using SEM-AVS models as well as sequentially extracted European Community Bureau of Reference (BCR) metal fractions. Among the methods used, Cr, Ni, Cu, and Pb measured by DGT were significantly correlated with metal concentrations in the tissue of snails, while SEM-AVS could predict Cr, Ni and Pb bioavailability well, but not SEM-AVS/fOC. Finally, BCR sequential extraction and total metal concentrations only correlated well with Pb bioavailability to snails. Overall, the results of this study indicated that DGT performed best in predicting metal accumulation in snails and which could be used to predict sediment metal bioavailability to field inhabitant snails from freshwater lake sediments due to their simple manipulation and validity. PMID:24295770

Yin, Hongbin; Cai, Yongjiu; Duan, Hongtao; Gao, Junfeng; Fan, Chengxin



A new freshwater snail genus (Hydrobiidae, Gastropoda) from Montenegro, with a discussion on gastropod diversity and endemism in Skadar Lake.  


Karucia sublacustrina a new species of freshwater snails (Hydrobiidae, Gastropoda) is described based on material collected from Skadar Lake (Montenegro, Albania). The new species belongs to monotypic genus Karucia gen. n. The shell morphology and body shape of the new genus resembles Radomaniola Szarowska, 2006 and Grossuana Radoman, 1973, from which it differs in the larger shells with relatively slim and a slightly, but clearly shouldered body whorl. The number of gastropods from Skadar Lake basin tallies now 50 species. The adjusted rate of gastropod endemicity for Skadar Lake basin is estimated to be 38%. By compiling faunal and taxonomic data we also aim to provide information of relevance as to conservation efforts. PMID:23794834

Peši?, Vladimir; Glöer, Peter



Contrasting the distribution of phenotypic and molecular variation in the freshwater snail Biomphalaria pfeifferi, the intermediate host of Schistosoma mansoni  

PubMed Central

Population differentiation was investigated by confronting phenotypic and molecular variation in the highly selfing freshwater snail Biomphalaria pfeifferi, the intermediate host of Schistosoma mansoni. We sampled seven natural populations separated by a few kilometers, and characterized by different habitat regimes (permanent/temporary) and openness (open/closed). A genetic analysis based on five microsatellite markers confirms that B. pfeifferi is a selfer (s?0.9) and exhibits limited variation within populations. Most pairwise FST were significant indicating marked population structure, though no isolation by distance was detected. Families from the seven populations were monitored under laboratory conditions over two generations (G1 and G2), allowing to record several life-history traits, including growth, fecundity and survival, over 25 weeks. Marked differences were detected among populations for traits expressed early in the life cycle (up to sexual maturity). Age and size at first reproduction had high heritability values, but such a trend was not found for early reproductive traits. In most populations, G1 snails matured later and at a larger size than G2 individuals. Individuals from permanent habitats matured at a smaller size and were more fecund than those from temporary habitats. The mean phenotypic differentiation over all populations (QST) was lower than the mean genetic differentiation (FST), suggesting stabilizing selection. However, no difference was detected between QST and FST for both habitat regime and habitat openness.

Tian-Bi, Y-NT; Jarne, P; Konan, J-NK; Utzinger, J; N'Goran, E K



Trait compensation and cospecialization in a freshwater snail: size, shape and antipredator behaviour  

Microsoft Academic Search

We examined relationships between individual differences in antipredator behaviour and prey morphological characters (size, shape) that influence prey vulnerability. Behavioural responses of Physa gyrina to chemical cues associated with predation by crayfish Orconectes rusticus, were assayed in the laboratory for 6 days over a 13-day period. Snails displayed consistent, individually repeatable responses to the predation cues, including hiding (refuge use)

Thomas J. Dewitt; Andrew Sih; Jeffrey A. Hucko



An experimental heat wave changes immune defense and life history traits in a freshwater snail.  


The predicted increase in frequency and severity of heat waves due to climate change is expected to alter disease dynamics by reducing hosts' ability to resist infections. This could take place via two different mechanisms: (1) through general reduction in hosts' performance under harsh environmental conditions and/or (2) through altered resource allocation that reduces expression of defense traits in order to maintain other traits. We tested these alternative hypotheses by measuring the effect of an experimental heat wave (25 vs. 15°C) on the constitutive level of immune defense (hemocyte concentration, phenoloxidase [PO]-like activity, antibacterial activity of hemolymph), and life history traits (growth and number of oviposited eggs) of the great pond snail Lymnaea stagnalis. We also manipulated the exposure time to high temperature (1, 3, 5, 7, 9, or 11 days). We found that if the exposure to high temperature lasted <1 week, immune function was not affected. However, when the exposure lasted longer than that, the level of snails' immune function (hemocyte concentration and PO-like activity) was reduced. Snails' growth and reproduction increased within the first week of exposure to high temperature. However, longer exposures did not lead to a further increase in cumulative reproductive output. Our results show that short experimental heat waves do not alter immune function but lead to plastic responses that increase snails' growth and reproduction. Thus, although the relative expression of traits changes, short experimental heat waves do not impair snails' defenses. Negative effects on performance get pronounced when the heat waves are prolonged suggesting that high performance cannot be maintained over long time periods. This ultimately reduces the levels of defense traits. PMID:24455121

Leicht, Katja; Jokela, Jukka; Seppälä, Otto



An experimental heat wave changes immune defense and life history traits in a freshwater snail  

PubMed Central

The predicted increase in frequency and severity of heat waves due to climate change is expected to alter disease dynamics by reducing hosts' ability to resist infections. This could take place via two different mechanisms: (1) through general reduction in hosts' performance under harsh environmental conditions and/or (2) through altered resource allocation that reduces expression of defense traits in order to maintain other traits. We tested these alternative hypotheses by measuring the effect of an experimental heat wave (25 vs. 15°C) on the constitutive level of immune defense (hemocyte concentration, phenoloxidase [PO]-like activity, antibacterial activity of hemolymph), and life history traits (growth and number of oviposited eggs) of the great pond snail Lymnaea stagnalis. We also manipulated the exposure time to high temperature (1, 3, 5, 7, 9, or 11 days). We found that if the exposure to high temperature lasted <1 week, immune function was not affected. However, when the exposure lasted longer than that, the level of snails' immune function (hemocyte concentration and PO-like activity) was reduced. Snails' growth and reproduction increased within the first week of exposure to high temperature. However, longer exposures did not lead to a further increase in cumulative reproductive output. Our results show that short experimental heat waves do not alter immune function but lead to plastic responses that increase snails' growth and reproduction. Thus, although the relative expression of traits changes, short experimental heat waves do not impair snails' defenses. Negative effects on performance get pronounced when the heat waves are prolonged suggesting that high performance cannot be maintained over long time periods. This ultimately reduces the levels of defense traits.

Leicht, Katja; Jokela, Jukka; Seppala, Otto



Apple Snails (Ampullariidae)  

NSDL National Science Digital Library

This web site provides information on apple snails (family Ampullariidae), the largest living freshwater snails on earth, often kept as aquarium pets because of their attractive appearance and size. Topics include the care of apple snails, their anatomy, species and genera, and information on snail pests, embryology, and genetics. There is also a frequently-asked-questions feature, photos, links to web sites and literature, and an online discussion forum.

Ghesquiere, Stijn A.


Effect of a toxicant on phagocytosis pathways in the freshwater snail Lymnaea stagnalis.  


The disturbance of plasma membrane carbohydrates and of lipopolysaccharide (LPS) ligands in relation to cytoskeletal transformations of haemocytes has been investigated after chronic exposure of pond snails (Lymnaea stagnalis) to the peroxidizing toxicant fomesafen. Neither of the two lectins used (concanavalin A and wheat germ agglutinin) showed any binding modification after incubation of the snails in the presence of the toxicant. However, after exposure of the snails to fomesafen, a clear and persistent reduction in LPS labelling of haemocytes occurred. The actin cytoskeleton of the same cells also appeared to be sensitive to the toxicant. The reduction in LPS-binding sites was related to actin staining, leading to the hypothesis that LPS ligands and actin could be similarly modulated by the toxicant. Damaged cells showed non-adherent membrane portions with reduced filopodial extrusions, exhibiting a smooth surface free of microvilli. These changes could lower the spreading and adhesion of the cells and could therefore account for the loss in their phagocytic capabilities. PMID:18431599

Russo, Jacqueline; Madec, Luc; Brehélin, Michel



Avoidance of aluminum toxicity in freshwater snails involves intracellular silicon-aluminum biointeraction.  


Silicon (Si) ameliorates aluminum (Al) toxicity to a range of organisms, but in almost all cases this is due to ex vivo Si-Al interactions forming inert hydroxyaluminosilicates (HAS). We hypothesized a Si-specific intracellular mechanism for Al detoxification in aquatic snails, involving regulation of orthosilicic acid [Si(OH)4]. However, the possibility of ex vivo formation and uptake of soluble HAS could not be ruled out Here we provide unequivocal evidence for Si-Al interaction in vivo, including their intracellular colocalization. In snails preloaded with Si(0H)4, behavioral toxicity in response to subsequent exposure to Al was abolished. Similarly, recovery from Al-induced toxicity was faster when Si(OH)4 was provided, together with rapid loss of Al from the major detoxificatory organ (digestive gland). Temporal separation of Al and Si exposure excluded the possibility of their interaction ex vivo. Elemental mapping using analytical transmission electron microscopy revealed nanometre-scale colocalization of Si and Al within excretory granules in the digestive gland, consistent with recruitment of Si(OH)4, followed by high-affinity Al binding to form particles similarto allophane, an amorphous HAS. Given the environmental abundance of both elements, we anticipate this to be a widespread phenomenon, providing a cellular defense against the profoundly toxic Al(III) ion. PMID:18409657

White, Keith N; Ejim, Abraham I; Walton, Rachel C; Brown, Andrew P; Jugdaohsingh, Ravin; Powell, Jonathan J; McCrohan, Catherine R



The ITS2 of the genus Bulinus: novel secondary structure among freshwater snails and potential new taxonomic markers.  


The freshwater snail genus Bulinus has been intensively investigated due to its role as intermediate host for trematode blood flukes that cause the debilitating disease schistosomiasis in man and livestock. Owing to taxonomic ambiguities within Bulinus, attention has often focused upon species delineation and several molecular methods have recently been used for identification and characterization purposes. Inspection of compensatory base changes (CBCs) in the secondary structure of the nuclear ribosomal internal transcribed spacer (ITS) has been used to differentiate species in other genera, and here we present a study investigating the presence of CBCs between species in the species groups within Bulinus. CBCs were present within B. forskalii and B. globosus indicating that these widely distributed taxa might constitute cryptic species complexes. However, other currently recognized species could not be distinguished by CBC analysis. The putative secondary structure of the very long ITS2 sequence of the B. reticulatus species group had an additional helix (DIIa) between DII and DIII not seen in other species groups of Bulinus. The accumulation and inspection of further ITS2 sequences will no doubt reveal additional variation between Bulinus populations, and CBCs should be incorporated in future taxonomic work in this group. PMID:22677601

Jørgensen, Aslak; Stothard, J R; Madsen, Henry; Nalugwa, Allen; Nyakaana, Silvester; Rollinson, David



Evolutionary history and phylogeography of the schistosome-vector freshwater snail Biomphalaria glabrata based on nuclear and mitochondrial DNA sequences.  


The phylogeography of the freshwater snail Biomphalaria glabrata remains poorly known, although this species is the major vector of schistosomiasis in the New World. It was here investigated in South America and the Lesser Antilles, based on partial mitochondrial large ribosomal subunit (16S rDNA) and nuclear internal transcribed spacer-2 (ITS-2) gene sequences. Sampling included 17 populations from a large part of the current geographic range of the species (Brazil, Venezuela and Lesser Antilles). Substantial variability was detected, as well as a high amount of phylogenetically informative signal. The molecular phylogeny inferred splits B. glabrata into Northern and Southern clades separated by the Amazon river, and may even suggest a supra-specific status for B. glabrata. Brazilian populations were the most diverse and appeared basal to the other populations. Venezuelan haplotypes formed a single clade, albeit not strongly supported. Two Venezuelan haplotypes appear rather similar to Brazilian haplotypes. Similarly, Lesser Antilles haplotypes clustered in the same monophyletic clade, which suggests that the recent colonisation of the Antilles has a northern South American origin. However, the estimated divergence time between Antilles and Venezuelan sequences is extremely large (conservatively higher than 10(5) years). These results are discussed in the light of (i) phylogeographic patterns at South American scale, and (ii) recurrent introduction of molluscs, especially in the Antilles, as a consequence of human activities. PMID:12242642

Mavárez, J; Steiner, C; Pointier, J-P; Jarne, P



[The neuronal mechanisms of the defensive reaction to stimulation of the cutaneous nerve in the freshwater snail].  


The whole body withdrawal reaction of freshwater snail Planorbarius corneus consists of two phases. In the first phase the shell is rapidly moved down to cover the head, in the second one the body is slowly retracted into the shell. The columellar muscle is involved in this behaviour. Motoneurons of the columellar muscle are identified in the cerebral, parietal and pedal ganglia. In the preparation of the central nervous system connected with the columellar muscle it is demonstrated that stimulation of the lip nerve evoked a biphasic motoneuron excitation responsible for two phases of the muscle contraction. A similar biphasic excitation of the motoneurons could arise spontaneously. This implies that the whole body withdrawal reaction is, at least partly, a fixed act generated by a central mechanism (a central program) which is triggered by a sensory stimulus. The central mechanism of the withdrawal reaction could be also activated by a depolarization of some columellar motoneurons. This suggests that the central mechanism received a feedback from the motoneurons. PMID:2097506

Arshavski?, Iu I; Deliagina, T G; Okshte?n, I L; Orlovski?, G N; Panchin, Iu V



Sole smooth muscle states determine gliding rate in the freshwater snail Lymnaea stagnalis.  


The sole of crawling gastropods is a unique model for studying the function of smooth muscles and ciliated epithelium. The gastropod snail Lymnaea stagnalis glides over the substratum without visible muscular contraction in its sole; consequently, the gliding was thought to be due to sole cilia. However, we have shown that the sole muscles in Lymnaea are phasic smooth muscles. They contribute extensively to gliding rate, which is directly correlated with the sole length (longitudinal sole muscle tonus) that varies widely during gliding. Here, we show that the linear relationship between gliding rate and sole length in Lymnaea may be modified. Serotonin increases gliding rate and has no effect on sole length. Dopamine contracts the sole and, consequently, slows the gliding rate, while ergometrine (a blocker of dopamine receptors) relaxes the sole and increases gliding rate. These influences on locomotion rate and sole length are similar to those obtained earlier for Helix lucorum, in which the substances changed the number and contraction force of muscle cells involved in peristaltic locomotory waves. Taken together, the data obtained here for Lymnaea and earlier for Helix describe the fundamental mechanisms for controlling phasic smooth muscles. PMID:24445444

Pavlova, Galina A



Higher rate of tissue regeneration in polyploid asexual versus diploid sexual freshwater snails.  


Characterizing phenotypic differences between sexual and asexual organisms is a critical step towards understanding why sexual reproduction is so common. Because asexuals are often polyploid, understanding how ploidy influences phenotype is directly relevant to the study of sex and will provide key insights into the evolution of ploidy-level variation. The well-established association between genome size and cell cycle duration, evidence for a link between genome size and tissue regeneration rate and the growing body of research showing that ploidy influences growth rate and gene expression led us to hypothesize that healing and tissue regeneration might be affected by ploidy-level variation. We evaluated this hypothesis by measuring the rate of regeneration of antenna tissue of Potamopyrgus antipodarum, a New Zealand snail characterized by frequent coexistence between diploid sexuals and polyploid asexuals. Antennae of triploid and presumptive tetraploid asexuals regenerated more rapidly than the antennae of diploid sexuals, but regeneration rate did not differ between triploids and tetraploids. These results suggest either that ploidy elevation has nonlinear positive effects on tissue regeneration and/or that factors associated directly with reproductive mode affect regeneration rate more than ploidy level. The results of this study also indicate that the lower ploidy of sexual P. antipodarum is unlikely to confer advantages associated with more rapid regeneration. PMID:23843218

Krois, Nicole R; Cherukuri, Anvesh; Puttagunta, Nikhil; Neiman, Maurine



The effects of engineered nanoparticles on survival, reproduction, and behaviour of freshwater snail, Physa acuta (Draparnaud, 1805).  


Increasing uses of engineered nanoparticles (ENPs) in commercial products and industrial applications has eventually resulted to their releases into atmospheric, terrestrial, and aquatic environments. However, knowledge gaps in ENPs toxicity, fate, and behaviour currently limit our ability to quantify risk assessment of materials with nanoscale dimensions, and therefore, the extent of the resultant environmental impacts remains unknown. In the present study, we evaluated the effects of ?-alumina, ?-alumina, modified TiO(2) (M-TiO(2)), and commercial TiO(2) (C-TiO(2)) ENPs on the survival, behaviour, and early life stages of the freshwater snail Physa acuta (Draparnaud). The toxicity evaluation was carried out after spiking commercial sand with ENPs concentrations of 0.005, 0.05, or 0.5 gk g(-1). Our findings suggest that increases of ?-alumina and ?-alumina concentrations at sub-lethal level concentrations caused significant reduction in the embryo growth rate and embryo hatchability. In addition, these ENPs induced observable developmental deformities of the embryos. In addition, toxicity evaluations using acute 96-h and chronic 28-d tests showed exposure duration may be a significant factor in ENPs-induced toxicity. Therefore, long-term exposure of aquatic organisms to ENPs - potentially can alter certain ecological populations at different trophic levels - and may compromise the entire aquatic ecological functionality. The percentage hatchlings in test chambers containing 0.5 gk g(-1) ?-alumina and ?-alumina concentration was 50% less to those observed in the controls. Our results suggest the embryonic growth and hatchability tests are useful endpoints in chronic sediment toxicity tests for determining the toxic thresholds of ENPs in sediment environment. Although no snail mortalities were observed during the static 96-h test containing sediment spiked with different concentrations of M-TiO(2), C-TiO(2), ?-alumina and ?-alumina - the antioxidant enzymatic assay results indicated a significant change in antioxidant levels which altered peroxidation at 0.05 or 0.5 gk g(-1)concentrations for both ?-alumina and ?-alumina. PMID:20943245

Musee, N; Oberholster, P J; Sikhwivhilu, L; Botha, A-M



Population dynamics of Chaetogaster limnaei (Oligochaeta: Naididae) in the field populations of freshwater snails and its implications as a potential regulator of trematode larvae community.  


The objectives of this work were to study (1) the population dynamics of Chaetogaster limnaei in the field populations of freshwater snails and the implications for the species as a potential regulator of the trematode larvae community and (2) prevalence and intensity of C. limnaei in relation to host species, host size, and season. This study was conducted at Al-Salam Canal and Al-Abtal village (new cultivated area in north Sinai). The samples were collected from March 2004 to February 2005. The natural infection rate by trematodes and C. limnaei was assessed monthly. Thirteen species of snails were examined for C. limnaei infection, five species were found infected. There were positive correlations between host size and both combined prevalence and mean intensity in all hosts. The data demonstrated that prevalence in Bulinus truncatus was higher when compared with other hosts. Bellamya unicolor has higher mean intensity when compared with other host species. A significant difference was found between host species and both prevalence and intensity. There were spatial and temporal variations in prevalence and mean intensity in most hosts, and the data suggest some seasonality. A negative correlation was found between prevalence of C. limnaei and trematode infection. C. limnaei did not co-occur with trematode larvae in infected hosts indicating that the oligochaete may protect the hosts from trematode infection. B. unicolor was recorded for the first time as a host for C. limnaei. C. limnaei may be a potential regulator of the trematode community in freshwater snails. In conclusion, this study demonstrated that C. limnaei, symbiotically associated with snail vector of parasitic diseases, may have important implications with respect to biological control and/or changes in the epizootiology of native parasites in the study area. PMID:17252272

Ibrahim, Mohamed Moussa



Isotopic niche metrics as indicators of toxic stress in two freshwater snails.  


Descriptors of trophic niche and of food web structure and function have been suggested as integrative and sensitive endpoints of toxicant effects. In the present study, carbon and nitrogen stable isotope signatures were used to assess the effects of the dithiocarbamate fungicide thiram (35 and 170?g/L nominal concentrations) and of a petroleum distillate (0.01, 0.4, 2 and 20mg/L nominal loadings as Hydrocarbon Emulsion or Hydrocarbon Water Accommodated Fraction) on the trophic niche of two freshwater gastropods in artificial streams (Radix peregra) and ponds (Lymnaea stagnalis). Results were analyzed using classical univariate statistical methods and recently proposed uni- and multivariate metrics of the realized trophic niche of species. The trophic niche metrics were highly sensitive to both types of chemicals, but exposure resulted in different response patterns according to the nature of the tested compound. Thiram clearly affected gastropod trophic niche leading to a change in the food resources used and resulting in trophic niche expansion (i.e., increase of diversity of used resources, especially dead animals) or trophic niche contraction (i.e., decrease of diversity of used resources) across time. Both gastropod taxa exposed to hydrocarbons showed a clear trophic niche expansion. Trophic niche metrics therefore provide a promising way of investigating non-lethal effects of exposure to organic chemicals on aquatic invertebrates, and subsequent disturbances in food webs. PMID:24691210

Bayona, Yannick; Roucaute, Marc; Cailleaud, Kevin; Lagadic, Laurent; Bassères, Anne; Caquet, Thierry



Comparative analysis of circulating hemocytes of the freshwater snail Pomacea canaliculata.  


Molluscs are invertebrates of great relevance for economy, environment and public health. The numerous studies on molluscan immunity and physiology registered an impressive variability of circulating hemocytes. This study is focused on the first characterization of the circulating hemocytes of the freshwater gastropod Pomacea canaliculata, a model for several eco-toxicological and parasitological researches. Flow cytometry analysis identified two populations of hemocytes on the basis of differences in size and internal organization. The first population contains small and agranular cells. The second one displays major size and a more articulated internal organization. Light microscopy evidenced two principal morphologies, categorized as Group I (small) and II (large) hemocytes. Group I hemocytes present the characteristics of blast-like cells, with an agranular and basophilic cytoplasm. Group I hemocytes can adhere onto a glass surface but seem unable to phagocytize heat-inactivated Escherichia coli. The majority of Group II hemocytes displays an agranular cytoplasm, while a minority presents numerous granules. Agranular cytoplasm may be basophilic or acidophilic. Granules are positive to neutral red staining and therefore acidic. Independently from their morphology, Group II hemocytes are able to adhere and to engulf heat-inactivated E. coli. Transmission electron microscopy analysis clearly distinguished between agranular and granular hemocytes and highlighted the electron dense content of the granules. After hemolymph collection, time-course analysis indicated that the Group II hemocytes are subjected to an evident dynamism with changes in the percentage of agranular and granular hemocytes. The ability of circulating hemocytes to quickly modify their morphology and stainability suggests that P. canaliculata is endowed with highly dynamic hemocyte populations able to cope with rapid environmental changes as well as fast growing pathogens. PMID:23422816

Accorsi, Alice; Bucci, Laura; de Eguileor, Magda; Ottaviani, Enzo; Malagoli, Davide



Species diversity of Plagiorchis Lühe, 1899 (Digenea: Plagiorchiidae) in lymnaeid snails from freshwater ecosystems in central Europe revealed by molecules and morphology.  


Larval stages of Plagiorchis spp. are both ubiquitous and ecologically important parasites in snail populations of freshwater ecosystems in Europe. However, difficulties in distinguishing the morphologically similar cercariae used for species identification, may lead to underestimation of species diversity. In this study, 38 isolates of Plagiorchis spp. infecting two lymnaeid snails, Lymnaea stagnalis (L.) and Radix auricularia (L.), in five central European freshwater ecosystems were subjected to morphological and molecular assessment. Five morphologically homogeneous and genetically distinct lineages of Plagiorchis spp. were identified via matching molecular data for the mitochondrial cytochrome c oxidase subunit I (cox1) gene with detailed morphological and morphometric data of the cercariae. Comparative sequence analysis using partial 28S rDNA and ITS1-5.8S-ITS2 sequences revealed that three distinct cox1 lineages are conspecific with Plagiorchis elegans (Rudolphi, 1802), P. maculosus (Rudolphi, 1802) and P. koreanus Ogata, 1938, respectively, whereas the lineage identified based on cercarial morphology as P. neomidis Brendow, 1970 plus a single isolate that could not be assigned to a described species, did not match any of the available sequences for Plagiorchis spp. A key to the cercariae of Plagiorchis spp. parasitising lymnaeid populations in central Europe is provided to facilitate identification. PMID:24711111

Zikmundová, Jana; Georgieva, Simona; Faltýnková, Anna; Soldánová, Miroslava; Kostadinova, Aneta



Freshwater Ecosystems  

NSDL National Science Digital Library

In this activity, learners create a freshwater ecosystem in a large plastic bottle. Learners cut and prepare bottles, then fill with water, aquatic plants, snails and fish. Learners observe their mini-ecosystem over time to see what changes--such as the color of the water, the water temperature, plant growth, and behavior and/or population of the snails or fish. The activity serves as a model for larger freshwater ecosystems such as ponds, lakes, rivers, streams, wetlands, reservoirs and groundwater.

Jersey, New; Center, Liberty S.; Coalition, New J.



Tricuspid and Pulmonic Valve Disease  

Microsoft Academic Search

\\u000a In the adult, the tricuspid and pulmonic valves are in general less affected by disease states compared to left-sided cardiac\\u000a valves. While right-sided valves are essential in maintaining hemodynamic balance and in dictating long-term prognosis, valvular\\u000a disease is better tolerated compared to left-sided valves. With the common occurrence of trivial regurgitation in right-sided\\u000a valves in normal individuals, noninvasive determination of

Meeney Dhir; William A. Zoghbi


Distribution of freshwater snails in the river Niger basin in Mali with special reference to the intermediate hosts of schistosomes  

Microsoft Academic Search

Snail surveys were carried out in various parts of Mali. All areas surveyed are part of the Niger basin being either affluents\\u000a or irrigation schemes fed by this river. The snail species present varied greatly between areas. The following potential hosts\\u000a of schistosomes were recorded: Biomphalaria pfeifferi, Bulinus truncatus, B. globosus, B. umbilicatus, B. forskalii and B. senegalensis.\\u000a \\u000a In the

Henry Madsen; Godefroy Coulibaly; Peter Furu



First evidence of "paralytic shellfish toxins" and cylindrospermopsin in a Mexican freshwater system, Lago Catemaco, and apparent bioaccumulation of the toxins in "tegogolo" snails (Pomacea patula catemacensis).  


Exposure to cyanobacterial toxins in freshwater systems, including both direct (e.g., drinking water) and indirect (e.g., bioaccumulation in food webs) routes, is emerging as a potentially significant threat to human health. We investigated cyanobacterial toxins, specifically cylindrospermopsin (CYN), the microcystins (MCYST) and the "paralytic shellfish toxins" (PST), in Lago Catemaco (Veracruz, Mexico). Lago Catemaco is a tropical lake dominated by Cylindrospermopsis, specifically identified as Cylindrospermopsis catemaco and Cylindrospermopsis philippinensis, and characterized by an abundant, endemic species of snail (Pomacea patula catemacensis), known as "tegogolos," that is both consumed locally and commercially important. Samples of water, including dissolved and particulate fractions, as well as extracts of tegogolos, were screened using highly specific and sensitive ELISA. ELISA identified CYN and PST at low concentrations in only one sample of seston; however, both toxins were detected at appreciable quantities in tegogolos. Calculated bioaccumulation factors (BAF) support bioaccumulation of both toxins in tegogolos. The presence of CYN in the phytoplankton was further confirmed by HPLC-UV and LC-MS, following concentration and extraction of algal cells, but the toxin could not be confirmed by these methods in tegogolos. These data represent the first published evidence for CYN and the PST in Lago Catemaco and, indeed, for any freshwater system in Mexico. Identification of the apparent bioaccumulation of these toxins in tegogolos may suggest the need to further our understanding of the transfer of cyanobacterial toxins in freshwater food webs as it relates to human health. PMID:19651152

Berry, John P; Lind, Owen



Eye trematode infection in small passerines in Peru caused by Philophthalmus lucipetus, an agent with a zoonotic potential spread by an invasive freshwater snail.  


Until now, four species of eye trematodes have been found in South America. Of them, Philophthalmus lucipetus (synonymized with Philophthalmus gralli) displays a broad host spectrum, with at least 30 bird species (prevalently large water birds), five mammal species and humans serving as definitive hosts, and with snails Fagotia (Microcolpia) acicularis, Amphimelania holandri, Melanopsis praemorsa and Melanoides tuberculata serving as intermediate hosts. When examining a total of 50 birds of ten species in the wetland of Pantanos de Villa, Lima, Peru in July 2011, eye trematodes were identified visually in the edematous conjunctival sac of 11 (48%) out of 23 resident many-colored rush tyrants Tachuris rubrigastra. Based on morphometric characteristics, the trematodes were identified as P. lucipetus. ITS2 and CO1 gene of the examined specimens combined showed a 99% similarity to an Iranian isolate of Philophthalmus sp. from the intermediate host Melanoides tuberculata, an invasive freshwater snail, suggesting that these two isolates represent the same species with a wide geographical range. Moreover, the prevalence of infection with the philophthalmid cercariae was 31% in 744 Melanoides tuberculata examined in Pantanos de Villa in 2010. It is evident that P. lucipetus occurs throughout the world as well as locally, including Eurasia and South America. Here we report this trematode for the first time in Peru, and we were the first to sequence any of the South American eye trematodes. Low host specificity of P. lucipetus and the invasive character of Melanoides tuberculata as a competent intermediate host suggest that eye trematodosis caused by P. lucipetus may emerge frequently in various parts of the world, especially in the tropics. Increase of the zoonotic potential of the P. lucipetus associated with this invasive snail spreading across the world is predictable and should be of interest for further research. PMID:23570701

Literák, Ivan; Heneberg, Petr; Sitko, Jiljí; Wetzel, Eric J; Cardenas Callirgos, Jorge Manuel; ?apek, Miroslav; Valle Basto, Daniel; Papoušek, Ivo



Adaptive Radiation in the Larval Feeding Habits of the Snail-Killing Fly Genus Tetanocera (Diptera: Sciomyzidae)  

NASA Astrophysics Data System (ADS)

The genus Tetanocera consists of 29 species in North America. The genus is unusual in that its larvae occupy five of the 17 feeding groups recognized in the family, as most other genera of the family occupy only one or two trophic guilds. Seven species have larvae that attack pulmonate aquatic snails, three species attack pulmonate snails stranded on shorelines, four species attack amber snails of the family Succineidae, three species attack slugs, and two species are predators of terrestrial snails. The larval feeding behavior of representative species of each of the five trophic guilds will be described and illustrated.

Foote, B. A.



Detection and quantification of schistosome DNA in freshwater snails using either fluorescent probes in real-time PCR or oligochromatographic dipstick assays targeting the ribosomal intergenic spacer.  


Several DNA probes were designed for use in real-time polymerase chain reaction (PCR) assays to target sequence variation within the ribosomal intergenic spacer (IGS) of schistosomes. A sub-section of the IGS (?300bp) was amplified, with cross-specific primers, after which group-specific fluorescent, locked nucleic acid probes were assessed for their ability to differentiate and quantify DNA from Schistosoma haematobium and Schistosoma mansoni group parasites. A number of fluorescent probe candidates were screened and validated against genomic DNA from adult schistosome worms and laboratory infected freshwater snails. Two fluorescent, locked nucleic acid probes ShaemLNA5 and SmanLNA2, of 20-26bp in length, were identified and found to be effective in providing evidence of infection in field-collected snails. To adapt these real-time PCR assays for more resource-poor laboratory settings, a PCR-restriction fragment length polymorphism (RFLP) assay was developed and primer/probe combinations were modified for use in oligochromatography, a DNA 'dipstick' technology. An appropriate dipstick was developed, inclusive of internal amplification and amplicon migration controls that could be of particular importance for assessing schistosome transmission dynamics. These assays and tools also have future potential for use in detection of schistosome infections in humans and livestock. PMID:22100540

Kane, Richard A; Stothard, J Russell; Rollinson, David; Leclipteux, Thierry; Evraerts, Jonathan; Standley, Claire J; Allan, Fiona; Betson, Martha; Kaba, Rehana; Mertens, Pascal; Laurent, Thierry



Aragonite to Calcite Transformation Study by XRD and Esr Studies of Mn2+ in Freshwater Snail Shells:. P. Canaliculata Lamarck  

Microsoft Academic Search

Electron spin resonance spectroscopy (ESR) was used to study the Mn2+ ions in snails of P. canaliculata lamarck (PCL). All these shells are abundant in Thailand. Fractions of aragonite and calcite phase in the shells have been approximately determined by ESR. The PCL shell was ground into fine powders and then four samples were separately annealed for 2 h in

N. Udomkan; P. Limsuwan; Y. Chaimanee



Nonylphenol polyethoxylate adjuvant mitigates the reproductive toxicity of fomesafen on the freshwater snail Lymnaea stagnalis in outdoor experimental ponds.  


The influence of nonylphenol polyethoxylates (NPEO), formulated as the adjuvant Agral 90, on the effects of the diphenyl ether herbicide fomesafen in the pond snail Lymnaea stagnalis was investigated, with particular attention to the reproductive performances and underlying energetic and hormonal processes. Separate short-term exposures to low concentrations of fomesafen and fomesafen-Agral mixture were performed in the laboratory. Outdoor experimental ponds (mesocosms) were used for long-term exposures to higher chemical concentrations. At the concentrations used in the studies, NPEO were known as nontoxic in L stagnalis. Fomesafen was mixed with the adjuvant in the 3:7 ratio recommended for agricultural uses (nominal herbicide concentrations of 22 and 40 microg/L in laboratory and mesocosm, respectively). In mesocosms, multiple application of fomesafen, leading to maximal herbicide concentrations of 60.33 +/- 2.68 microg/L in water, resulted in reduced number of egg masses and altered glycogen metabolism in contaminated snails. These changes, as well as affected steroid-like levels in fomesafen-exposed snails, support the hypothesis of impaired neuroendocrine functions. When Agral 90 was added to the herbicide, results obtained in mesocosms showed that the adjuvant softened the impact of fomesafen. In mesocosms treated with the fomesafen-Agral mixture, significantly lower herbicide levels were found in the water (30.33 +/- 14.91 microg/L at the end of the contamination period). Consequently, internal exposure of the snails to fomesafen was reduced when the herbicide was mixed with the adjuvant. Mitigation of the effects of fomesafen by the adjuvant may therefore result from nonionic surfactant activity of NPEO that prevented fomesafen from reaching the snails. PMID:12206427

Jumel, Audrey; Coutellec, Marie-Agnès; Cravedi, Jean-Pierre; Lagadic, Laurent



A Snail Perspective on the Biogeography of Sulawesi, Indonesia: Origin and Intra-Island Dispersal of the Viviparous Freshwater Gastropod Tylomelania  

PubMed Central

The complex geological history of the Indonesian island Sulawesi has shaped the origin and subsequent diversification of its taxa. For the endemic freshwater snail Tylomelania a vicariant origin from the Australian margin has been hypothesized. Divergence time estimates from a mtDNA phylogeny based on a comprehensive island-wide sampling of Tylomelania fit regional tectonic constraints and support the ‘out-of-Australia’ vicariance hypothesis. The Banggai-Sula region of the Sula Spur, the Australian promontory colliding with West Sulawesi during the Miocene, is identified as a possible source area for the colonization of Sulawesi by the ancestor of Tylomelania. The molecular phylogeny also shows a rapid diversification of Tylomelania into eight major lineages with very little overlap in their distribution on the island. Haplotype networks provide further evidence for a strong spatial structure of genetic diversity in Tylomelania. Distribution boundaries of the major lineages do at best partially coincide with previously identified contact zones for other endemic species groups on Sulawesi. This pattern has likely been influenced by the poor dispersal capabilities and altitudinal distribution limits of this strict freshwater inhabitant. We suggest that late Miocene and Pliocene orogeny in large parts of Sulawesi has been the vicariant event driving primary diversification in Tylomelania.

von Rintelen, Thomas; Stelbrink, Bjorn; Marwoto, Ristiyanti M.; Glaubrecht, Matthias



Dependence on aerial respiration and its influence on microdistribution in the invasive freshwater snail Pomacea canaliculata (Caenogastropoda, Ampullariidae)  

Microsoft Academic Search

The invasive Neotropical snail Pomacea canaliculata is usually regarded as amphibious, although the relative significance of aerial and aquatic respiration is unknown. To investigate\\u000a the degree of dependence on aerial respiration and its influences on microdistribution, experiments were performed in the\\u000a laboratory and under seminatural and natural conditions. Restriction of aerial respiration negatively affected survivorship,\\u000a activity and feeding, its effects

María E. Seuffert; Pablo R. Martín



Heavy metal concentrations in the freshwater snail Biomphalaria alexandrina uninfected or infected with cercariae of Schistosoma mansoni and/or Echinostoma liei in Egypt: the potential use of this snail as a bioindicator of pollution.  


In spite of using aquatic snails as bioindicators for water pollution, little attention has been paid to the effect of parasitism upon the concentration of heavy metals (Al, Cd, Cu, Fe, Mn, Pb and Zn) in these organisms. The present study therefore aimed to compare the concentrations of heavy metals in trematode-infected Biomphalaria alexandrina collected from Kafer Alsheikh and Menofia provinces, Egypt, with uninfected snails from the same sites, in order to assess the effect of parasitism on the use of these snails as bioindicators. The concentrations of heavy metals in the soft parts and shells of snails were measured by flame atomic absorption spectrometry. The results showed that the heavy metal profile in snails infected with Echinostoma liei was very different from that in snails infected with Schistosoma mansoni. The total concentration of heavy metals in E. liei-infected snails collected from Kafer Alsheikh or Menofia province was greater than in uninfected snails. In contrast, the total concentration of heavy metals in S. mansoni-infected snails was reduced compared with uninfected snails. In conclusion, the status of snails with respect to parasitic infection must be taken into consideration when these snails are used as bioindicators. PMID:23710821

Mostafa, O M S; Mossa, A-T H; El Einin, H M A



Binary Combination of Carica papaya, Areca catechu and Myristica fragrans with Piperonyl Butoxide / MGK-264 against Freshwater Snail Lymnaea acuminata.  


Piperonyl butoxide (PB) and MGK-264 were used to enhance the toxicity of the active components papain, arecoline and myristicin from the plants Carica papaya, Areca catechu and Myristica fragrans, respectively, against the vector snail Lymnaea acuminata. A time- and dose-dependent relationship was observed for the toxicity of these combinations. The toxic effects of these plant-derived molluscicides in combination with the synergists PB and MGK-264 were several times higher than the effect of the individual treatments. The highest degree of synergism was observed when MGK-264 was used in combination with C. papaya latex (10.47-fold increase) and PB was used with papain (8.35-fold increase). PMID:24575245

Hanif, Farhat; Singh, Dinesh Kumar



Binary Combination of Carica papaya, Areca catechu and Myristica fragrans with Piperonyl Butoxide / MGK-264 against Freshwater Snail Lymnaea acuminata  

PubMed Central

Piperonyl butoxide (PB) and MGK-264 were used to enhance the toxicity of the active components papain, arecoline and myristicin from the plants Carica papaya, Areca catechu and Myristica fragrans, respectively, against the vector snail Lymnaea acuminata. A time- and dose-dependent relationship was observed for the toxicity of these combinations. The toxic effects of these plant-derived molluscicides in combination with the synergists PB and MGK-264 were several times higher than the effect of the individual treatments. The highest degree of synergism was observed when MGK-264 was used in combination with C. papaya latex (10.47-fold increase) and PB was used with papain (8.35-fold increase).

Hanif, Farhat; Singh, Dinesh Kumar



Disjunct distributions of freshwater snails testify to a central role of the Congo system in shaping biogeographical patterns in Africa  

PubMed Central

Background The formation of the East African Rift System has decisively influenced the distribution and evolution of tropical Africa’s biota by altering climate conditions, by creating basins for large long-lived lakes, and by affecting the catchment and drainage directions of river systems. However, it remains unclear how rifting affected the biogeographical patterns of freshwater biota through time on a continental scale, which is further complicated by the scarcity of molecular data from the largest African river system, the Congo. Results We study these biogeographical patterns using a fossil-calibrated multi-locus phylogeny of the gastropod family Viviparidae. This group allows reconstructing drainage patterns exceptionally well because it disperses very poorly in the absence of existing freshwater connections. Our phylogeny covers localities from major drainage basins of tropical Africa and reveals highly disjunct sister-group relationships between (a) the endemic viviparids of Lake Malawi and populations from the Middle Congo as well as between (b) the Victoria region and the Okavango/Upper Zambezi area. Conclusions The current study testifies to repeated disruptions of the distribution of the Viviparidae during the formation of the East African Rift System, and to a central role of the Congo River system for the distribution of the continent’s freshwater fauna during the late Cenozoic. By integrating our results with previous findings on palaeohydrographical connections, we provide a spatially and temporarily explicit model of historical freshwater biogeography in tropical Africa. Finally, we review similarities and differences in patterns of vertebrate and invertebrate dispersal. Amongst others we argue that the closest relatives of present day viviparids in Lake Malawi are living in the Middle Congo River, thus shedding new light on the origin of the endemic fauna of this rift lake.



The Chemistry of Marine Pulmonate Gastropods  

Microsoft Academic Search

Secondary metabolites from pulmonate molluscs of the genera Siphonaria, Onchidium, and Trimusculus are described. Siphonaria and Onchidium biosynthesize mostly propionate-based metabolites whereas Trimusculus yields diterpene derivatives with a single type of labdane skeleton. The 42 regular polypropionates reported to date from Siphonaria are divided into two classes (class I, class II), based on their observed structural and stereochemical analogy. The

Josè Darias; Mercedes Cueto; Ana Díaz-Marrero


Pulmonic Ingressive Speech in Shetland English  

ERIC Educational Resources Information Center

This paper presents a study of pulmonic ingressive speech, a severely understudied phenomenon within varieties of English. While ingressive speech has been reported for several parts of the British Isles, New England, and eastern Canada, thus far Newfoundland appears to be the only locality where researchers have managed to provide substantial…

Sundkvist, Peter



Animal Mitochondria, Positive Selection and Cyto-Nuclear Coevolution: Insights from Pulmonates  

PubMed Central

Pulmonate snails have remarkably high levels of mtDNA polymorphism within species and divergence between species, making them an interesting group for the study of mutation and selection on mitochondrial genomes. The availability of sequence data from most major lineages – collected largely for studies of phylogeography - provides an opportunity to perform several tests of selection that may provide general insights into the evolutionary forces that have produced this unusual pattern. Several protein coding mtDNA datasets of pulmonates were analyzed towards this direction. Two different methods for the detection of positive selection were used, one based on phylogeny, and the other on the McDonald-Kreitman test. The cyto-nuclear coevolution hypothesis, often implicated to account for the high levels of mtDNA divergence of some organisms, was also addressed by assessing the divergence pattern exhibited by a nuclear gene. The McDonald-Kreitman test indicated multiple signs of positive selection in the mtDNA genes, but was significantly biased when sequence divergence was high. The phylogenetic method identified five mtDNA datasets as affected by positive selection. In the nuclear gene, the McDonald-Kreitman test provided no significant results, whereas the phylogenetic method identified positive selection as likely present. Overall, our findings indicate that: 1) slim support for the cyto-nuclear coevolution hypothesis is present, 2) the elevated rates of mtDNA polymorphims and divergence in pulmonates do not appear to be due to pervasive positive selection, 3) more stringent tests show that spurious positive selection is uncovered when distant taxa are compared and 4) there are significant examples of positive selection acting in some cases, so it appears that mtDNA evolution in pulmonates can escape from strict deleterious evolution suggested by the Muller’s ratchet effect.

Parmakelis, Aristeidis; Kotsakiozi, Panayiota; Rand, David



Aragonite to Calcite Transformation Study by XRD and Esr Studies of Mn2+ in Freshwater Snail Shells:. P. Canaliculata Lamarck  

NASA Astrophysics Data System (ADS)

Electron spin resonance spectroscopy (ESR) was used to study the Mn2+ ions in snails of P. canaliculata lamarck (PCL). All these shells are abundant in Thailand. Fractions of aragonite and calcite phase in the shells have been approximately determined by ESR. The PCL shell was ground into fine powders and then four samples were separately annealed for 2 h in air at 400°C, 450°C, 500°C and 600°C, respectively. The phase transition from aragonite to calcite was monitored by X-ray diffractometer (XRD) and electron spin resonance spectrometer (ESR). Our results show that unheated PCL sample is mainly made of aragonite with only a small fraction of calcite. Annealing of the PCL powder sample at the temperature more than 450°C has resulted in the irreversible phase transformation from aragonite to calcite. The analysis of their ESR spectra has shown that Mn2+ ions partially substituted Ca2+ in the lattices. Finally, the spin Hamiltonian parameters for Mn2+ distributed in both aragonite and calcite were evaluated. Our detailed ESR spectral analyses of PCL show that Mn2+ ions enter Ca2+ sites during a biomineralization process. Typical simulated ESR parameters of PCL-500 of Mn2+ at a uniaxial site of calcite are gx=gy=2.078(1), gz=1.999(1), Ax=Ay=87.0 G, Az=89.00 G and D=115 G, respectively. It is thus possible to gain some insight of manganese incorporation into the fresh water shells during the biomineralization process.

Udomkan, N.; Limsuwan, P.; Chaimanee, Y.


Snail Tales  

NSDL National Science Digital Library

"Snail Tales" is an inquiry-based exploratory lesson for students to investigate learning and memory using common garden snails. This classroom laboratory is based on research by neuroscientists and best classroom practice.

Phelps, Cynthia L.; Willcockson, Irmgard U.; Houtz, Lynne



Progressive multifocal leukoencephalopathy developing in advanced pulmonal sarcoidosis  

Microsoft Academic Search

Coincidence of pulmonal sarcoidosis and progressive multifocal leukoencephalopathy (PML) rarely occurs. So far an entire course has been recorded in only very few cases. We demonstrate the case of a 49-year-old male developing an infratentorial localized PML in the setting of advanced pulmonal sarcoidosis. PML was not included in the diagnostic considerations in the first instance. Regarding the diagnosis of

Hans-Ullrich Völker; Klaus Kraft; Eva Arnold; Silke Steinhoff; Georgios Kolios; Stephanie Sommer



A predatory land snail invades central-western Argentina  

Microsoft Academic Search

The pulmonate land snail, Rumina decollata, is a highly invasive gastropod adapted to arid conditions, and native from the Mediterranean area. It was recorded for the\\u000a first time in Argentina in 1988, in the northeastern Pampas of the Buenos Aires Province, a region characterized by a humid\\u000a mesothermal climate with no water deficit. In the present contribution, we report the

Claudio G. De Francesco; Humberto Lagiglia



Quantitative analysis of total proteins and carbohydrates in the digestive gland-gonad complex (DGG) and hemolymph of the freshwater prosobranch snail Lanistes carinatus.  


Laboratory investigations were carried out to quantify the amount of total proteins, carbohydrates and reducing sugar in the hemolymph and Digestive Gland Gonad- complex (DGG) of infected and uinfected lanistes arinatus. Snails were naturally infected with two different types of trematode la:val stages (rediae of gymnocepahalus cercaria and sporocyst of xiphidiocercaria), collected from the River Nile at Sohag governorate, Egypt. Analysis was carried out using an extraction of the DGGs tissue with buffer solution, while snails' hemolymph was applied directly. The results revealed that snail infection by rediae of gymnocephalus cercariae led to non significant increasing in both total carbohydrates and protein in hemolymph. However, infection by sporocysts of xiphidiocercariae caused a significant increasing only in hemolymph total protein. On the other hand, the amount of both reducing sugar and total proteins in DGG did not increase significantly whenever the infection caused by both types of trematode larvae. However, total carbohydrates in DGG increased significantly. PMID:21246938

Hassan, Amaal Hassan M; Mahmoud, Salim; El-Hamidy, A



Snail Trails  

ERIC Educational Resources Information Center

The slime trails of snails lead the author's students to a better understanding of science as inquiry and the processes of science. During this five-day activity, students get up close and personal with one of her favorite creatures, the land snail. Students begin by observing the organism and recording their observations. After making initial…

Galus, Pamela



Snails home  

NASA Astrophysics Data System (ADS)

Many gardeners and horticulturalists seek non-chemical methods to control populations of snails. It has frequently been reported that snails that are marked and removed from a garden are later found in the garden again. This phenomenon is often cited as evidence for a homing instinct. We report a systematic study of the snail population in a small suburban garden, in which large numbers of snails were marked and removed over a period of about 6 months. While many returned, inferring a homing instinct from this evidence requires statistical modelling. Monte Carlo techniques demonstrate that movements of snails are better explained by drift under the influence of a homing instinct than by random diffusion. Maximum likelihood techniques infer the existence of two groups of snails in the garden: members of a larger population that show little affinity to the garden itself, and core members of a local garden population that regularly return to their home if removed. The data are strongly suggestive of a homing instinct, but also reveal that snail-throwing can work as a pest management strategy.

Dunstan, D. J.; Hodgson, D. J.



Assessment of mercury toxicity by the changes in oxygen consumption and ion levels in the freshwater snail, Pila globosa, and the mussel, Lamellidens marginalis  

SciTech Connect

There are many studies on mercury toxicity in freshwater fishes but very few on freshwater molluscs (Wright 1978) though they serve as bio-indicators of metal pollution. A few reports on marine gastropods and bivalves indicated the importance of these animals in metal toxicity studies. Hence, in the present study, the level of tolerance of the freshwater gastropod Pila globosa and of a freshwater bivalve Lamellidens marginalis mercury at lethal and sublethal levels was determined and compared with the rate of whole animal oxygen consumption and the level of sodium, potassium and calcium ions in the hepatopancreas and the foot of these animals. As the period of exposure is one of the important factors in toxicity studies, the level of tolerance was determined at 120 hours of exposure and the other parameters were analyzed at 1, 3 and 5 days in lethal and at 1, 7 and 15 days in sublethal concentrations.

Sivaramakrishna, B.; Radhakrishnaiah, K.; Suresh, A. (Sri Krishnadevaraya Univ., Andhra Pradesh (India))



Supercharged Snails for Stream Ecology & Water-Quality Studies  

ERIC Educational Resources Information Center

Gill-breathing freshwater snails (Family "Pleuroceridae") are ecologically important, abundant in many streams in the United States, and easy to collect and maintain under classroom conditions. These snails can be used in classroom tests to demonstrate effects of pollutants on aquatic organisms. In more advanced classes, students can cage the…

Stewart, Arthur J.; Ryon, Michael G.



Snails and trematode infection after Indian Ocean tsunami in Phang-Nga Province, southern Thailand.  


The tsunami and non-tsunami affected areas of Takua Pa District, Phang-Nga Province were investigated for fresh- and brackish-water snails that transmit human parasitic diseases during 2006 and 2007. Among 46 snail species found, 17 species of 8 families were freshwater snails, 28 species of another 7 families were brackish-water snails, and 1 species was a land snail. Of these species, 11 freshwater snails, 4 brackish-water snails and 1 land snail were of medical importance. The fresh-water snails were Pomacea canaliculata, Pila angelica, P. gracilis, P. polita, Filopaludina (S.) martensi, F. (F.) s. polygramma, Melanoides tuberculata, Indoplanorbis exuxtus, Radix rubiginosa, Helicorbis umbilicalis, Gyraulus convexiusculus. Four brackish-water snails were Cerithidea cingulata, C. djadjarensis, C. alata, Sermyla riqueti and Achatina fulica was the land snail. I. exutus, M. tuberculata and F. (F.) s. polygramma harbored Xiphidio, Microcercus, Furocercus, Echinostome cercariae, and cercaria without eyespots or tail with hair. Three species of brackish-water snails, Cerithidia cingulata, C. djadjariensis, and C. alata presented with 6 types of trematode cercariae and rediae. Knowledge of medically important snails and their parasitic diseases, and prevention were given to Takua Pa people by poster, pamphlets and broadcasting through community radio. PMID:20578482

Sri-Aroon, Pusadee; Chusongsang, Phiraphol; Chusongsang, Yupa; Pornpimol, Surinthwong; Butraporn, Piyarat; Lohachit, Chantima



Molecular and functional characterization of a tandem-repeat galectin from the freshwater snail Biomphalaria glabrata, intermediate host of the human blood fluke Schistosoma mansoni  

PubMed Central

In the present study, a tandem-repeat type galectin was characterized from an embryonic cell line (Bge) and circulating hemocytes of the snail Biomphalaria glabrata, intermediate host of the human blood fluke Schistosoma mansoni. The predicted B. glabrata galectin (BgGal) protein of 32 kDa possessed 2 carbohydrate recognition domains, each displaying 6 of 8 conserved amino acids involved in galactoside-binding activity. A recombinant BgGal (rBgGal) demonstrated hemagglutinating activity against rabbit erythrocytes, which was specifically inhibited by galactose-containing sugars (lacNAc/lac > galNAc/gal). Although native galectin was immunolocalized in the cytoplasm of Bge cells and the plasma membrane of a subset of snail hemocytes (60%), it was not detected in cell-free plasma by Western blot analysis. The findings that rBgGal selectively recognizes the schistosome-related sugar, lacNAc, and strongly binds to hemocytes and the tegument of S. mansoni sporocysts in a sugar-inhibitable fashion suggest that hemocyte-bound galectin may be serving as pattern recognition receptor for this, or other pathogens possessing appropriate sugar ligands. Based on molecular and functional features, BgGal represents an authentic galectin, the first to be fully characterized in the medically-important molluscan Class Gastropoda.

Yoshino, Timothy P.; Dinguirard, Nathalie; Kunert, John; Hokke, Cornelius H.



Linking embryo toxicity with genotoxic responses in the freshwater snail Physa acuta: single exposure to benzo(a)pyrene, fluoxetine, bisphenol A, vinclozolin and exposure to binary mixtures with benzo(a)pyrene.  


Genotoxic effects on fauna after waterborne pollutant exposure have been demonstrated by numerous research programmes. Less effort has been focused on establishing relationship between genotoxicity and long-term responses at higher levels of biological organization. Taking into account that embryos may be more sensitive indicators of reproductive impairment than alterations in fertility, we have developed two assays in multiwell plates to address correlations between embryo toxicity and genotoxicity. The potential teratogenicity was assessed by analyzing abnormal development and mortality of Physa acuta at embryonic stage. Genotoxicity was measured by the micronucleus (MN) test using embryonic cells. Our results showed that linkage between genotoxicity and embryo toxicity depends on mechanisms of action of compounds under study. Embryo toxic responses showed a clear dose-related tendency whereas no clear dose-dependent effect was observed in micronucleus induction. The higher embryo toxicity was produced by benzo(a)pyrene exposure followed by fluoxetine and bisphenol A. Vinclozolin was the lower embryo toxic compound. Binary mixtures with BaP always resulted in higher embryo toxicity than single exposures but antagonistic effects were observed for MN induction. Benzo(a)pyrene produced the higher MN induction at 0.04 mg/L, which also produced clear embryo toxic effects. Fluoxetine did not induce cytogenetic effects but 0.25mg/L altered embryonic development. Bisphenol A significantly reduced hatchability at 0.5mg/L while MN induction appeared with higher treatments than those that start causing teratogenicity. Much higher concentration of vinclozolin (5mg/L) reduced hatchability and induced maximum MN formation. In conclusion, while validating one biomarker of genotoxicity and employing one ecologically relevant effect, we have evaluated the relative sensitivity of a freshwater mollusc for a range of chemicals. The embryo toxicity test is a starting point for the development of a life cycle test with freshwater snails even for undertaking multigeneration studies focused on transgenerational effects. PMID:22417675

Sánchez-Argüello, Paloma; Aparicio, Natalia; Fernández, Carlos



Cercarial Dermatitis Transmitted by Exotic Marine Snail  

PubMed Central

Cercarial dermatitis (swimmer’s itch) is caused by the penetration of human skin by cercariae of schistosome parasites that develop in and are released from snail hosts. Cercarial dermatitis is frequently acquired in freshwater habitats, and less commonly in marine or estuarine waters. To investigate reports of a dermatitis outbreak in San Francisco Bay, California, we surveyed local snails for schistosome infections during 2005–2008. We found schistosomes only in Haminoea japonica, an Asian snail first reported in San Francisco Bay in 1999. Genetic markers place this schistosome within a large clade of avian schistosomes, but do not match any species for which there are genetic data. It is the second known schistosome species to cause dermatitis in western North American coastal waters; these species are transmitted by exotic snails. Introduction of exotic hosts can support unexpected emergence of an unknown parasite with serious medical or veterinary implications.

Cohen, Andrew N.; James, David; Hui, Lucia; Hom, Albert; Loker, Eric S.



Effects of self-fertilization, environmental stress and exposure to xenobiotics on fitness-related traits of the freshwater snail Lymnaea stagnalis.  


Genetic and ecological factors may interact in their effects on fitness. Such interactions are thus to be expected between inbreeding and exposure of a population to a toxicant. The magnitude of inbreeding depression is thought to increase in stressful environments. To test this hypothesis, we investigated the combined effects of environmental conditions and inbreeding on fitness in the self-fertile snail Lymnaea stagnalis, using a stress gradient (0-2) applied to a 100 isolated and paired lineages: laboratory control (0), outdoor microcosm control (1) and pesticide exposure under outdoor microcosm conditions (2). Outdoor stress conditions were maintained for 28 days prior to measurements of fitness traits (fecundity, hatching success, and size at hatching) under laboratory conditions, so that delayed environmental effects could be estimated. Under laboratory control conditions, we found significant initial family level heterogeneity for most measured traits, including physiological performances as assessed through energetic biomarkers. Whatever the environmental conditions, inbreeding depression was very low for progeny performances. Negative values of self-fertilization depression (SFD) were obtained. Unexpectedly, SFD showed a negative relationship with the assumed stress intensity, reflecting a higher sensitivity under pairing than under selfing, mostly due to parental fecundity. This suggests that stressful conditions may favour selfing. Stress intensity increased the distribution limits of both depression indices, suggesting that changes in fitness are less predictable in a population under stress. Implications of such findings for environmental risk assessment of pesticides are discussed. PMID:16425104

Coutellec, Marie-Agnès; Lagadic, Laurent



Effect of non target snails on some biological of Lymnaea natalensis snails and their infection to Fasciola gigantica.  


The influence of non-target freshwater snails (Melanoides tuberculata and Planorbis planorbis) on the capacity of Fasciola egg production F. gigantica miracidia to infect Lymnaea natalensis and their effect on mortality and growth rates showed that the snails exhibited a competitive ability against L. natalensis. The mortality rate existed in mixed cultures with snails was greatly increased, and increased with increase of snails number. The egg production and growth rate were negatively affected by the presence of M. tuberculata and P. planorbis which was more pronounced when snails were at higher ratio lL: 10D. Also, the snails showed significant degree of reduction in infection rate of L. natalensis with F. gigantica miracidia. PMID:17153707

Bakry, Fayez A; Hamdi, Salwa A H



Invertebrate Invasions on Pacific Islands and the Replacement of Unique Native Faunas: A Synthesis of the Land and Freshwater Snails*Contribution no. 2001-001 of Bishop Museum's Pacific Biological Survey  

Microsoft Academic Search

The once immense diversity of native Pacific island land snail species, with high single island or archipelago endemism, is declining dramatically. The native\\/endemic species are being replaced by a much smaller number of widespread tropical ‘tramps’, that is, those species that are most readily transported by humans. The 82 introduced (including 14 ‘cryptogenic’) land snail species recorded include some that

Robert H. Cowie



Schedule of Spermatogenesis in the Pulmonate Snail Helix aspersa, with Special Reference to Histone Transition  

PubMed Central

The schedule of spermatogenesis is determined from the times necessary for cells labeled with tritium thymidine during premeiotic DNA synthesis to pass through the successive spermatogenic stages. A transition from a typically somatic histone rich in lysine, to a histone rich in arginine is shown to occur during spermatid stages. A later shift to a protamine is observed in the maturing sperm. These changes are characterized by the use of in situ staining methods. The transition to an arginine-rich histone is accompanied by incorporation of tritium-labeled arginine, hence reflects synthesis of new protein. Comparison of the timing of arginine and thymidine incorporation, and independent measurements of DNA, show that in contrast to the case of premitotic chromosome duplication, the histone synthesis in the spermatid is unaccompanied by DNA synthesis. During the initial histone change, fine filaments are formed within the nucleus, which aggregate to form lamellae. This fine structure is lost during maturation of the sperm.

Bloch, David P.; Hew, Howard Y. C.



Environmental impact of the golden snail (Pomacea sp.) on rice farming systems in the Philippines  

Microsoft Academic Search

A summary report of the workshop held at the Freshwater Aquaculture Center, Central Luzon State University, Nueva Ecija, Philippines, on 9-10 November 1989. It discusses the effects wrought by the golden snail since its introduction to the Philippines, particularly on rice farming systems. Ways to control the snail are presented.

B. Acosta; R. S. V. Pullin


Pedal sole immunoreactive axons in terrestrial pulmonates: Limax, Arion, and Helix.  


A century ago histological techniques such as formic acid-gold chloride showed the nerve morphology of the pedal sole in Limax and Helix. There have been no similar descriptions since then of the central nervous system relevant to locomotory pedal waves in the foot of slugs and snails. Topical application of 5-HT affects locomotory waves, but the innervation of the pedal sole with 5-HT axons is not known. Three-dimensional morphology of pedal axons in terrestrial pulmonate embryos is shown herein with modern histological techniques using antibodies and the confocal microscope. In Limax maximus, pedal ganglia are shown with Tritonia pedal peptide (TPep) antibodies. Ladder-like cross bridges in the pedal sole are shown with antibodies to both TPep and 5-HT. In Arion ater, pedal ganglia neurons and their axons that form a plexus in the pedal sole are shown with 5-HT antibodies. In Helix aspersa, 5-HT immunoreactive pedal ganglia neurons and a developing pedal sole axon plexus are seen as in A. ater. Axons in this plexus that grow across the pedal sole can be seen growing into pre-existing nerves. No peripheral 5-HT neurons were identified in these three species. This immunoreactive plexus to 5-HT antibodies in A. ater and H. aspersa spreads over the pedal sole epithelium. Axons immunoreactive to 5-HT antibodies in A. ater and H. aspersa extend the length of the foot, primarily in the rim, so that activity in these axons cannot provide local patterned input to produce locomotory waves, but may provide modulatory input to pedal sole muscles. PMID:24648204

Longley, Roger D



Lemierre's Syndrome: A Rare Case of Pulmonic Valve Vegetation.  


Lemierre's syndrome is an uncommon complication of pharyngitis commonly associated with an anaerobic gram negative bacterium, Fusobacterium necrophorum. The syndrome usually affects young healthy adults with the mean age of 20 and is characterized by recent pharyngitis followed by ipsilateral internal jugular vein thrombosis and septic thromboembolism. The treatment is at least 6 weeks of antibiotics; the role of anticoagulation is unclear. The following presentation is a case of Lemierre's syndrome in a 23-year-old healthy individual who is infected by a rare species: Fusobacterium nucleatum. The case is complicated by septic emboli to the lungs and impressive seeding vegetation to the right ventricular outflow tract (RVOT) at the pulmonic valve of the heart. PMID:23573433

Kwan, Clara; Mastrine, Lou; Moskovits, Manfred



Self-Fertilization and Genetic Population Structure in a Colonizing Land Snail  

PubMed Central

The pulmonate land snail Rumina decollata in its native Mediterranean range is a complex of monogenic or weakly polygenic strains generated by a breeding system of facultative self-fertilization. One strain colonized North America and now occupies much of the southern United States and northern Mexico. No genetic variation within or among populations in the United States was detected in an electrophoretic analysis of proteins encoded by 25 loci. These findings emphasize the potential for adaptive convergence in the genetic systems of hermaphroditic animals and plants.

Selander, Robert K.; Kaufman, Donald W.



Effects of Schistosoma mansoni experimental infection on some inorganic elements in the snail host Biomphalaria alexandrina.  


The alteration in the concentrations of metallic ion Pb, Zn, K, Na, Co, Fe, and Cu in the soft parts of the Biomphalaria alexandrina snails shedding Schistosoma mansoni cercariae was detected by flame atomic absorption spectrometry. Six elements Pb, Zn, K, Na, Co, and Cu were found to be present at significantly higher concentrations in cercariae-shedding snails compared with uninfected snails. The concentration of Fe ion showed non-significant decrease in the tissues of cercariae-shedding snails. Variation in the present results compared with related previous studies lead to the suggestion that the effect of trematode parasitism on fresh-water snails should not be considered universal and might be varies according to the trematode-snail combination, the organs or the tissues analyzed and the analytical method used. PMID:20503598

Mostafa, Osama M S; Dajem, Saad M Bin



Effects of Endocrine Disruptors on Prosobranch Snails (Mollusca: Gastropoda) in the Laboratory. Part III: Cyproterone Acetate and Vinclozolin as Antiandrogens  

Microsoft Academic Search

The effects of suspected endocrine disrupting chemicals on freshwater and marine prosobranch species were analysed in laboratory experiments. In this last of three publications, the responses of the fresh water snail Marisa cornuarietis and of two marine prosobranchs (Nucella lapillus, Nassarius (Hinia) reticulatus) to the antiandrogenic model compounds cyproterone acetate (CPA) and vinclozolin (VZ) are presented. The snails were exposed

Michaela Tillmann; Ulrike Schulte-Oehlmann; Martina Duft; Bernd Markert



Neurogenesis in the procerebrum of the snail Helix aspersa: a quantitative analysis.  


The procerebrum, a specialized structure for olfaction in terrestrial pulmonate molluscs, contains 20,000 to 50,000 small, uniformly sized neurons that increase in number with age. Here I show the likely source of neurons added to the procerebrum of Helix aspersa and that the rate of neuron addition depends on snail weight. After hatching, during the initial exponential growth phase, H. aspersa adds neurons to the procerebral apex by mitosis and from a cerebral tube. In the logistic growth phase beginning 30-40 days post-hatch, neurons also seem to be added to the procerebrum from the peritentacular and olfactory nerves, causing the rate of neuron addition to approximately double; but as in the earlier exponential growth phase, this rate remains a function of snail weight. This neuron addition throughout the life of the snail can be predicted by snail weight. In the two growth phases, the number of neurons in the procerebrum is given by logarithmic functions of snail weight. The results here for H. aspersa provide the basis for experiments to determine the peripheral origin and destination of neuronal precursors that are added to the procerebrum and to determine how neuron addition affects the function of the procerebrum. PMID:22042440

Longley, Roger D




NSDL National Science Digital Library

In this video segment adapted from the Massachusetts Institute of Technology, a team from the Mechanical Engineering Department studies snail movement for inspiration that may lead to new forms of robotic locomotion.

Foundation, Wgbh E.



Effects of Endocrine Disruptors on Prosobranch Snails (Mollusca: Gastropoda) in the Laboratory. Part II: Triphenyltin as a Xeno-Androgen  

Microsoft Academic Search

In laboratory experiments the effects of suspected endocrine disrupting chemicals on freshwater and marine prosobranch species were analysed. In this second of three publications the responses of the freshwater ramshorn snail Marisa cornuarietis and of two marine prosobranchs (the dogwhelk Nucella lapillus and the netted whelk Hinia reticulata) to the xeno-androgenic model compound triphenyltin (TPT) are presented. Marisa and Nucella

Ulrike Schulte-Oehlmann; Michaela Tillmann; Bernd Markert; Jörg Oehlmann; Burkard Watermann; Sandra Scherf



Streptococcus Constellatus Community Acquired Pneumonia with Subsequent Isolated Pulmonic Valve Endocarditis and Abscess Formation in a Structurally Normal Heart  

PubMed Central

Pulmonic valve infective endocarditis in isolation is a rare clinical entity. The formation of an abscess in the right ventricular outflow tract as a consequence of vegetations affecting the pulmonic valve in a structurally normal heart is extremely rare and has not been reported. We report a case of isolated pulmonic valve endocarditis complicated by a regional abscess formed within the right ventricular outflow tract caused by Streptococcus Constellatus (S. Constellatus), a member of the Streptococcus Milleri group in a young male whose risk factor was alcohol abuse and he was treated medically, a comprehensive literature review on the subject is also reported. Our case is the first reported in literature with infective endocarditis caused by S. Constellatus affecting the pulmonic valve, and the first with pulmonic valve endocarditis and perivalvular abscess formation in a structurally normal heart.

Hutchison, Stuart James



Heat shock proteins (Hsp70) and water content in the estivating Mediterranean Grunt Snail (Cantareus apertus).  


Pulmonate land snails often are able to estivate to survive dry hot seasons were water and food are scarce. The aperture of the shell is closed with an epiphragm, and metabolism is depressed to approximately one fourth of basal metabolism. We investigated a molecular aspect of estivation focussing on the heat shock protein 70 (Hsp70) stress response during estivation in the Mediterranean Grunt Snail Cantareus apertus. Sequences of a new inducible hsp70 and of actin are presented and expression of the hsp70 gene as well as Hsp70 protein content was measured in estivating animals. Both Hsp70 protein and mRNA do not show a significant change from the control, although there is a trend that hsp70 mRNA is less abundant in estivating specimens. After heat shock, the expression of hsp70 increased and a higher Hsp70 protein content was detected. Water relations were also investigated. After a period of 6 months in the dormant state, the snails contained 14% less water than active ones, implying a constricted protection against desiccation, compared to the desert snail Sphincterochila zonata, and a Mediterranean-type water economy. PMID:18579425

Reuner, Andy; Brümmer, Franz; Schill, Ralph O



[Expression of genes encoding defense factors in the snail Planorbarius corneus (Gastropoda, Pulmonata) infested with trematodes].  


Because many species of gastropods are intermediate hosts for trematodes, these molluscs are often used as model-organisms in the studies of invertebrate immune system. Revealing of the ways in which the defense factors functioning became possible due to the use of the methods of molecular biology. Contemporary molecular methods allow analyzing the defense factors allocations and levels of their expression. We investigated the expression of genes encoding defense factors in gastropods by the example of the snail Planorbarius corneus from water bodies of the Leningrad Oblast under infestation with trematods. The snails naturally infested with the parthenites of trematode species belonging to the families Strigeidae, Notocotylidae, Plagiorchiidae, and Schistosomatida were used as the experimental sample. Uninfested snails were used as a control sample. Several genes encoding the factors, which have been recently found involved in the anti-trematode defense reactions in pulmonates, were chosen, namely fibrinogen-related protein, C-lectin, calcium-binding protein, and cystatin-like protein. The genes' expression was analyzed on total mRNA samples by the reverse transcription with the polymerase chain reaction. It was shown than expression levels of the genes under consideration are different in uninfested snails and in the snails infested with different trematode species. Thus, in the mollusks infested with the parthenites of Cotylurus sp. and Bilharziella polonica, the expression levels of the genes of all factors under study were increased, while in the infested Notocotylus sp. n Plagiorchis sp., only expression levels of C-lectin and cystatin-like protein were increased. Results of the expression analysis confirm the role of hemocytes and cells of hepatopancreas in the production of humoral defense factors. In the snails infested with trematodes, the expression levels of C-lectin and calcium-binding protein genes are increased in haemocytes, while the genes of fibrinogen-related and cystatin-like proteins are activated in the hepatopancreas. Our data also confirm the role of the factors examined in the anti-trematode defense reactions in pulmonates. PMID:21061590

Prokhorova, E E; Tsymbalenko, N V; Ataev, G L



UNEP: Freshwater  

NSDL National Science Digital Library

This searchable site, from The United Nations Environment Programme, is a clearinghouse for information about freshwater around the globe. The site provides links to UN reports, background guides on key freshwater issues, and many other resources.

The United Nations Environment Programme (UNEP)


Freshwater Macroinvertebrates.  

ERIC Educational Resources Information Center

Presents a literature review of freshwater biology particularly freshwater macroinvertebrates and their effect on water pollution, covering publications of 1976-77. A list of 158 references is also presented. (HM)

Nalepa, T. F.



Small Snails, Enormous Elephants  

NSDL National Science Digital Library

This activity (located on page 2 of PDF) introduces learners to the real size of animals using nonstandard measurement. Learners use Unifix cubes and yarn lengths to measure a variety of animals (photos), from the very small like a snail to the very large like an elephant. As an extension, learners can use the cubes to create a bar graph depicting the animals' lengths.

Museum, Chicago C.




EPA Science Inventory

Presented here are keys and notes on distribution and ecology for the freshwater snails (Gastropoda), mussels (Unionidae), and fingernail clams (Sphaeriidae) which have been collected from the Laurentian Great Lakes. Including subspecies and forms, 121 taxa are discussed: 47 Gast...


The ecology of vector snail habitats and mosquito breeding-places  

PubMed Central

The ecology of freshwater snails—in particular those which act as intermediate hosts of bilharziasis—is reviewed in the light of the much more extensive knowledge available on the breeding-places of anopheline mosquitos. Experimental ecological methods are recommended for the field and laboratory investigation of a number of common problems involved in the study of snail habitats and mosquito breeding-places. Among the environmental factors discussed are temperature, oxygen concentration, water movement, pollution and salinity. Sampling methods for estimating populations of both snails and mosquito larvae are also described. An attempt is made to show how malacologists and entomologists alike would benefit from improved facilities for keeping abreast of general developments in the wider field of freshwater ecology.

Muirhead-Thomson, R. C.



Characterization of the pigmented shell-forming proteome of the common grove snail Cepaea nemoralis  

PubMed Central

Background With a diversity of pigmented shell morphotypes governed by Mendelian patterns of inheritance, the common grove snail, Cepaea nemoralis, has served as a model for evolutionary biologists and population geneticists for decades. Surprisingly, the molecular mechanisms by which C. nemoralis generates this pigmented shelled diversity, and the degree of evolutionary conservation present between molluscan shell-forming proteomes, remain unknown. Results Here, using next generation sequencing and high throughput proteomics, we identify and characterize the major proteinaceous components of the C. nemoralis shell, the first shell-proteome for a pulmonate mollusc. The recent availability of several marine molluscan shell-proteomes, and the dataset we report here, allow us to identify 59 evolutionarily conserved and novel shell-forming proteins. While the C. nemoralis dataset is dominated by proteins that share little to no similarity with proteins in public databases, almost half of it shares similarity with proteins present in other molluscan shells. In addition, we could not find any indication that a protein (or class of proteins) is directly associated with shell pigmentation in C. nemoralis. This is in contrast to the only other partially characterized molluscan-shell pigmentation mechanism employed by the tropical abalone Haliotis asinina. Conclusions The unique pulmonate shell-forming proteome that we report here reveals an abundance of both mollusc-specific and pulmonate-specific proteins, suggesting that novel coding sequences, and/or the extensive divergence of these sequences from ancestral sequences, supported the innovation of new shell types within the Conchifera. In addition, we report here the first evidence that molluscs use independently evolved mechanisms to pigment their shells. This proteome provides a solid foundation from which further studies aimed at the functional characterization of these shell-forming proteins can be conducted.



Baldomero Olivera: Cone Snail Peptides  

NSDL National Science Digital Library

Have you ever considered the venom of a snail? Most people think of snakes when they think of venom but overlook snails. There are, however, almost 10,000 species of venomous predatory snails according to this engaging lecture from Professor Baldomero Olivera. In his talk, Professor Olivera explores how these venoms have been used to understand the nervous system and develop new drugs. The lecture is divided into three different sections, and visitors shouldn't miss Part 2 ("How a Fish Hunting Snail Captures Its Prey"). Visitors are also welcome to download the entire lecture and the accompanying slides.

Olivera, Baldomero


Baldomero Olivera: Cone Snail Peptides  

NSDL National Science Digital Library

Have you ever considered the venom of a snail? Most people think of snakes when they think of venom but overlook snails. There are, however, almost 10,000 species of venomous predatory snails according to this engaging lecture from Professor Baldomero Olivera. In his talk, Professor Olivera explores how these venoms have been used to understand the nervous system and develop new drugs. The lecture is divided into three different sections, and visitors shouldn't miss Part 2 ("How a Fish Hunting Snail Captures Its Prey"). Visitors are also welcome to download the entire lecture and the accompanying slides.

Olivera, Baldomero



Spatial mosaic evolution of snail defensive traits  

PubMed Central

Background Recent models suggest that escalating reciprocal selection among antagonistically interacting species is predicted to occur in areas of higher resource productivity. In a putatively coevolved interaction between a freshwater snail (Mexipyrgus churinceanus) and a molluscivorous cichlid (Herichthys minckleyi), we examined three components of this interaction: 1) spatial variation in two putative defensive traits, crushing resistance and shell pigmentation; 2) whether abiotic variables or frequency of molariform cichlids are associated with spatial patterns of crushing resistance and shell pigmentation and 3) whether variation in primary productivity accounted for small-scale variation in these defensive traits. Results Using spatial autocorrelation to account for genetic and geographic divergence among populations, we found no autocorrelation among populations at small geographic and genetic distances for the two defensive traits. There was also no correlation between abiotic variables (temperature and conductivity) and snail defensive traits. However, crushing resistance and frequency of pigmented shells were negatively correlated with molariform frequency. Crushing resistance and levels of pigmentation were significantly higher in habitats dominated by aquatic macrophytes, and both traits are phenotypically correlated. Conclusion Crushing resistance and pigmentation of M. churinceanus exhibit striking variation at small spatial scales often associated with differences in primary productivity, substrate coloration and the frequency of molariform cichlids. These local geographic differences may result from among-habitat variation in how resource productivity interacts to promote escalation in prey defenses.

Johnson, Steven G; Hulsey, C Darrin; de Leon, Francisco J Garcia



Freshwater Initiative  

NSDL National Science Digital Library

Launched in 1998 by The Nature Conservancy (TNC), the Freshwater Initiative aims "to protect the plants and animals dependent on freshwaters and develop solutions to key causes of freshwater biodiversity decline." To achieve this goal, Freshwater Initiative staff identifies sites that harbor critical aquatic biodiversity, targets conservation activities at several key freshwater sites, and develops expert and informative collaborations to foster freshwater conservation. The homepage is straightforward; the Strategies section outlines the Initiative's fundamental goals and approaches and identifies key regions of interest (see color map). The Indicators of Hydrologic Alteration (IHA) section describes IHA software (not free) used "to statistically characterize environmental regimes" (most commonly used by hydrologists and ecologists to evaluate streamflow data). Finally, a nice selection of links rounds out the site.



Metal distribution and metallothionein induction after cadmium exposure in the terrestrial snail Helix aspersa (Gastropoda, Pulmonata).  


The aim of the present work was to study the effect of Cd2+ exposure on metallothionein (MT) induction and on the distribution of metals (Cd, Cu, and Zn) in the terrestrial pulmonate Helix aspersa. In particular, the soluble and nonsoluble pools of the accumulated metals and their tissue distribution in uncontaminated and contaminated edible snails were investigated after a two-week exposure to Cd2+. In the soluble cytosolic pool of the midgut gland of H. aspersa, three metal-specific putative MT isoforms were separated following a fractionation protocol with diethylaminoethyl cellulose, size-exclusion chromatography, ultrafiltration, and reversed-phase high-performance liquid chromatography (RP-HPLC). Interestingly, one of the above isoforms seems to bind both Cd and Cu, which may in addition mobilize, after induction by Cd2+, some of the intracellular Cu and, thus, perhaps increase the Cu pool in the cytosolic fraction. The cDNA and its translated amino acid sequence of a Cd2+-binding MT isoform from the snail midgut gland was characterized and attributed to one of the putative MT isoforms obtained by RP-HPLC. The amino acid sequence of this Cd-MT isoform of H. aspersa differed from similar sequences described in other terrestrial pulmonates, such as Helix pomatia or Arianta arbustorum, by only a few amino acids (n = 4 and 8, respectively). That the identified Cd-MT from H. aspersa is inducible by Cd2+ also was shown, chromatographic evidence aside, by a specific polymerase chain reaction protocol on a cDNA basis, which included a noninducible housekeeping gene as a control. PMID:18384240

Hispard, Florian; Schuler, Dietmar; de Vaufleury, Annette; Scheifler, Renaud; Badot, Pierre-Marie; Dallinger, Reinhard



Polymorphism in pleistocene land snails.  


Under suitable conditions the colors and patterns of the shells of land snails may be preserved for thousands of years. In a late Pleistocene population of Limicolaria martensiana all the major color forms that occur in modern living snails may be distinguished, and the basic polymorphism is at least 8,000 to 10,000 year old. PMID:17830234

Owen, D F



Alterations of biochemical indicators in hepatopancreas of the golden apple snail, Pomacea canaliculata, from paddy fields in Taiwan.  


The freshwater golden apple snail, Pomacea canaliculata, is one of the world's 100 worst invasive alien species. The snails' wide distribution, high abundance, and sensitivity to environmental pollution make them a potential bioindicator for environmental contamination. In this study, the biochemical status of golden apple snails collected from paddy fields throughout the island of Taiwan was examined. This study found that the biochemical status of apple snails collected from paddy fields differed from that of animals bred and maintained in the laboratory. Furthermore, certain biochemical endpoints of the snails collected from the paddy fields before and after agricultural activities were also different-hemolymphatic vitellogenin protein was induced in male snail after exposure to estrogen-like chemicals, the hepatic monooxygenase (1.97 +/- 0.50 deltaA(650mm) 30 min(-1) mg(-1) protein in control group) and glutathione S transferase (0.02 +/- 0.01 delta A(340mm) 30 min(-1) mg(-1) protein in control group) snails exposed to pesticides, as well as the hepatopancreatic levels of aspartate aminotransferase (450.00 +/- 59.40 U mg(-1) mg(-1) protein in control group) and alanine aminotransferase (233.27 +/- 42.09 U mg(-1) mg(-1) protein in control group) decreased the indicating that xenobiotics destroyed hepatopancreatic. The above findings reveal that apple snail could be used as a practical bioindicator to monitor anthropogenic environmental pollution. PMID:25004751

Chiu, Yuh-Wen; Wu, Jui-Pin; Hsieh, Tsung-Chih; Liang, Shih-Hsiung; Chen, Chien-Min; Huang, Da-Ji



Plasma N-Terminal Pro B-Type Natriuretic Peptide Concentrations in Dogs with Pulmonic Stenosis  

PubMed Central

ABSTRACT The detailed information between plasma N-terminal pro B-type natriuretic peptide (NT-proBNP) concentrations and dogs with pulmonic stenosis (PS) is still unknown. The aim of the present study was to investigate the clinical utility of measuring plasma NT-proBNP concentrations in dogs with PS and to determine whether plasma NT-proBNP concentration could be used to assess disease severity. This retrospective study enrolled 30 client-owned, untreated dogs with PS (asymptomatic [n=23] and symptomatic [n=7]) and 11 healthy laboratory beagles. Results of physical examination, thoracic radiography and echocardiography were recorded. Plasma NT-proBNP concentrations were measured using commercial laboratories. Compared to the healthy control dogs, cardiothoracic ratio was significantly increased in dogs with both asymptomatic and symptomatic PS. Similarly, the ratio of the main pulmonary artery to aorta was significantly decreased in dogs with both asymptomatic and symptomatic PS. The pulmonic pressure gradient in the symptomatic PS dogs was significantly higher than that in the asymptomatic PS dogs. Plasma NT-proBNP concentration was significantly elevated in the symptomatic PS dogs compared to the healthy control dogs and the asymptomatic PS dogs. Furthermore, the Doppler-derived pulmonic pressure gradient was significantly correlated with the plasma NT-proBNP concentration (r=0.78, r2=0.61, P<0.0001). Plasma NT-proBNP concentration >764 pmol/l to identify severe PS had a sensitivity of 76.2% and specificity of 81.8%. The plasma NT-proBNP concentration increased by spontaneous PS, i.e. right-sided pressure overload and can be used as an additional method to assess the severity of PS in dogs.

KOBAYASHI, Keiya; HORI, Yasutomo; CHIMURA, Syuuichi



Parasites alter host phenotype and may create a new ecological niche for snail hosts  

PubMed Central

By modifying the behaviour and morphology of hosts, parasites may strongly impact host individuals, populations and communities. We examined the effects of a common trematode parasite on its snail host, Batillaria cumingi (Batillariidae). This widespread snail is usually the most abundant invertebrate in salt marshes and mudflats of the northeastern coast of Asia. More than half (52.6%, n=1360) of the snails in our study were infected. We found that snails living in the lower intertidal zone were markedly larger and exhibited different shell morphology than those in the upper intertidal zone. The large morphotypes in the lower tidal zone were all infected by the trematode, Cercaria batillariae (Heterophyidae). We used a transplant experiment, a mark-and-recapture experiment and stable carbon isotope ratios to reveal that snails infected by the trematode move to the lower intertidal zone, resume growth after maturation and consume different resources. By simultaneously changing the morphology and behaviour of individual hosts, this parasite alters the demographics and potentially modifies resource use of the snail population. Since trematodes are common and often abundant in marine and freshwater habitats throughout the world, their effects potentially alter food webs in many systems.

Miura, Osamu; Kuris, Armand M; Torchin, Mark E; Hechinger, Ryan F; Chiba, Satoshi



Impacts of an invasive snail (Tarebia granifera) on nutrient cycling in tropical streams: the role of riparian deforestation in Trinidad, West Indies.  


Non-native species and habitat degradation are two major catalysts of environmental change and often occur simultaneously. In freshwater systems, degradation of adjacent terrestrial vegetation may facilitate introduced species by altering resource availability. Here we examine how the presence of intact riparian cover influences the impact of an invasive herbivorous snail, Tarebia granifera, on nitrogen (N) cycling in aquatic systems on the island of Trinidad. We quantified snail biomass, growth, and N excretion in locations where riparian vegetation was present or removed to determine how snail demographics and excretion were related to the condition of the riparian zone. In three Neotropical streams, we measured snail biomass and N excretion in open and closed canopy habitats to generate estimates of mass- and area-specific N excretion rates. Snail biomass was 2 to 8 times greater and areal N excretion rates ranged from 3 to 9 times greater in open canopy habitats. Snails foraging in open canopy habitat also had access to more abundant food resources and exhibited greater growth and mass-specific N excretion rates. Estimates of ecosystem N demand indicated that snail N excretion in fully closed, partially closed, and open canopy habitats supplied 2%, 11%, and 16% of integrated ecosystem N demand, respectively. We conclude that human-mediated riparian canopy loss can generate hotspots of snail biomass, growth, and N excretion along tropical stream networks, altering the impacts of an invasive snail on the biogeochemical cycling of N. PMID:22761706

Moslemi, Jennifer M; Snider, Sunny B; Macneill, Keeley; Gilliam, James F; Flecker, Alexander S



Impacts of an Invasive Snail (Tarebia granifera) on Nutrient Cycling in Tropical Streams: The Role of Riparian Deforestation in Trinidad, West Indies  

PubMed Central

Non-native species and habitat degradation are two major catalysts of environmental change and often occur simultaneously. In freshwater systems, degradation of adjacent terrestrial vegetation may facilitate introduced species by altering resource availability. Here we examine how the presence of intact riparian cover influences the impact of an invasive herbivorous snail, Tarebia granifera, on nitrogen (N) cycling in aquatic systems on the island of Trinidad. We quantified snail biomass, growth, and N excretion in locations where riparian vegetation was present or removed to determine how snail demographics and excretion were related to the condition of the riparian zone. In three Neotropical streams, we measured snail biomass and N excretion in open and closed canopy habitats to generate estimates of mass- and area-specific N excretion rates. Snail biomass was 2 to 8 times greater and areal N excretion rates ranged from 3 to 9 times greater in open canopy habitats. Snails foraging in open canopy habitat also had access to more abundant food resources and exhibited greater growth and mass-specific N excretion rates. Estimates of ecosystem N demand indicated that snail N excretion in fully closed, partially closed, and open canopy habitats supplied 2%, 11%, and 16% of integrated ecosystem N demand, respectively. We conclude that human-mediated riparian canopy loss can generate hotspots of snail biomass, growth, and N excretion along tropical stream networks, altering the impacts of an invasive snail on the biogeochemical cycling of N.

Moslemi, Jennifer M.; Snider, Sunny B.; MacNeill, Keeley; Gilliam, James F.; Flecker, Alexander S.



Permeability barrier in the mantle epithelium lining the testis in the apple-snail Pomacea canaliculata (GASTROPODA: AMPULLARIIDAE)  

Microsoft Academic Search

Intercellular junctions are studied in the epithelium lining the testis of the freshwater snailPomacea canaliculata by conventional staining and lanthanum tracer techniques. The junctional complex consists of belt desmosomes and septate junctions. Septate junctions are of the pleated-sheet type and they are constantly associated with mitochondria. Gap and tight junctions appear to be absent. These septate junctions seem to be

E. A. Albrecht; J. C. Cavicchia



Red blood with blue-blood ancestry: intriguing structure of a snail hemoglobin.  


The phylogenetic enigma of snail hemoglobin, its isolated occurrence in a single gastropod family, the Planorbidae, and the lack of sequence data, stimulated the present study. We present here the complete cDNA and predicted amino acid sequence of two hemoglobin polypeptides from the planorbid Biomphalaria glabrata (intermediate host snail for the human parasite Schistosoma mansoni). Both isoforms contain 13 different, cysteine-free globin domains, plus a small N-terminal nonglobin "plug" domain with three cysteines for subunit dimerization (total M(r) approximately 238 kDa). We also identified the native hemoglobin molecule and present here a preliminary 3D reconstruction from electron microscopical images (3 nm resolution); it suggests a 3 x 2-mer quaternary structure (M(r) approximately 1.43 MDa). Moreover, we identified a previously undescribed rosette-like hemolymph protein that has been mistaken for hemoglobin. We also detected expression of an incomplete hemocyanin as trace component. The combined data show that B. glabrata hemoglobin evolved from pulmonate myoglobin, possibly to replace a less-efficient hemocyanin, and reveals a surprisingly simple evolutionary mechanism to create a high molecular mass respiratory protein from 78 similar globin domains. PMID:16877545

Lieb, Bernhard; Dimitrova, Konstantina; Kang, Hio-Sun; Braun, Sabrina; Gebauer, Wolfgang; Martin, Andreas; Hanelt, Ben; Saenz, Steven A; Adema, Coen M; Markl, Jürgen



Study of the diet effect on ? 13C of shell carbonate of the land snail Helix aspersa in experimental conditions  

NASA Astrophysics Data System (ADS)

This study aims to demonstrate the influence of the metabolic CO 2 derived from the diet and of the atmospheric CO 2 on the shell carbonate ? 13C of the pulmonate snail Helix aspersa maxima raised under controlled conditions. Adult snails were analyzed and compared with three hatching and 1-day old young snails stemming from the same breeding. One day after, the 2-day old individuals were raised during 1 month. Three groups of gastropods were fed with fresh lettuce (C 3 plant, ? 13C=-27.49‰), three groups with corn (C 4 plant, ? 13C=-11.7‰), and three groups ate alternately both (C 3+C 4). The difference between the average ? 13C values of the adult snails on the one hand and the hatched and 1-day old snails on the other hand indicates a depletion of 2.47‰. Therefore, the isotopic parents-offspring signal is not preserved. The depleted ingested albumen by the snail embryo in the egg during the building of the shell could explain this depletion. The C 3 diet experiment gave the expected isotopic composition difference between the diet (lettuce) and the shells (average ? 13C shell-lettuce=13.75‰±0.52). This result shows a clear diet effect on the isotopic composition of the snail shells. For the C 4 experiment, the difference in carbon isotope composition between the corn and the shell (? 13C shell-corn) yielded an average value of 4.89‰±0.87. The main result is that ? 13C is not constant and appears to depend on the type of ingested food. Several hypotheses can arise from this study to explain the different fractionations: (a) differences in the quality of the two diets, (b) differences in turnover rate for C 3 and C 4 feeders. The groups regularly fed with mixed diet yielded ? 13C values showing a preferential use of C 3 food for most values. The C 3-C 4 mixed dietary alternation probably led snails to use mainly the lettuce instead of the corn powder.

Metref, S.; Rousseau, D.-D.; Bentaleb, I.; Labonne, M.; Vianey-Liaud, M.



Nuclear Sex-determining Genes Cause Large Sex Ratio Variation in the Apple Snail  

Microsoft Academic Search

ABSTRACT Evolutionary maintenance,of genetic sex-ratio variation is enigmatic since genes for biased sex ratios are disadvantageous in finite populations (the “Verner effect”). However, such variation could be maintained if a small number,of nuclear sex-determining genes are responsible, although this has not been fully demonstrated experimentally. Brood sex ratios of a freshwater snail Pomacea canaliculataare highly variable among parents, but population

Pomacea Canaliculata; Yoichi Yusa


Metabolism of ovorubin, the major egg lipoprotein from the apple snail  

Microsoft Academic Search

The site of synthesis of molluscs lipoproteins is little known and was investigated for the egg lipoprotein perivitellin 1 (PV1) or ovorubin in the freshwater snail Pomacea canaliculata. Tissues (albumen gland, gonad–digestive gland complex and muscle) of vitellogenic females were incubated in vitro at 25°C for 12 h with 14C Leucine. After that, soluble proteins from tissue homogenates and medium

Marcos S. Dreon; Horacio Heras; Ricardo J. Pollero



Major carbon-14 deficiency in modern snail shells from southern Nevada springs  

USGS Publications Warehouse

Carbon-14 contents as low as 3.3 ?? 0.2 percent modern (apparent age, 27,000 years) measured from the shells of snails Melanoides tuberculatus living in artesian springs in southern Nevada are attributed to fixation of dissolved HCO3- with which the shells are in carbon isotope equilibrium. Recognition of the existence of such extreme deficiencies is necessary so that erroneous ages are not attributed to freshwater biogenic carbonates.

Riggs, A. C.



Freshwater macroinvertebrates  

SciTech Connect

Major aspects of the biology of freshwater macroinvertebrates with emphasis on man-induced environmental changes were reviewed in this report with 183 references. The effects of both chemical and physical environmental alteration are examined. The population dynamics of the macroinvertebrates are controlled by factors such as food and feeding habits, periodicity and drift, productivity and animal-sediment interactions.(KRM)

Quigley, M.A.



Freshwater Wetlands.  

ERIC Educational Resources Information Center

Provides descriptions about freshwater wetlands, such as marshes, swamps, and bogs. Contains three learning activities which deal with unusual wetland plants, the animals and plants in a typical marsh, and the effects of a draught on a swamp. Included are reproducible handouts and worksheets for two of the activities. (TW)

Naturescope, 1986



Changes in gastropod assemblages in freshwater habitats in the vicinity of Basel (Switzerland) over 87 years  

Microsoft Academic Search

The gastropod fauna in 18 freshwater habitats (streams, rivers and ponds) in the vicinity of Basel, first surveyed in 1906\\/1907, was re-examined in 1994. The freshwater snail fauna changed considerably over 87 years. One species (Aplexa hypnorum) recorded in 1906\\/1907 was not found in 1994, most probably it had become extinct in the period between the two surveys. Ten species

Bruno Baur; Birgit Ringeis



A Comparison of Freshwater Macroinvertebrate Communities on Small Caribbean Islands  

NSDL National Science Digital Library

This peer-reviewed article from BioScience is about freshwater macroinvetebrate communities. An ongoing survey of macroinvertebrates inhabiting the relatively unstudied freshwater habitats on 14 small Caribbean islands was initiated in 1991. These collections have yielded almost 200 species; when these species are combined with collections previously made by other researchers, a total of at least 328 freshwater macroinvertebrates are now known from these islands. The dominant taxa on the islands include several species of snails, shrimps, mayflies, dragonflies, damselflies, beetles, and other insects. Many of these species have fairly widespread distributions across the islands. Most stream species are associated with leaf packs, and most pond species are associated with aquatic macrophytes. As is typical of tropical island systems, the macroinvertebrate faunas of these islands are sparse, most likely because of their oceanic origin, their small size, and the frequent disturbances to their freshwater environments.




Estimating isotope fractionation between cercariae and host snail with the use of isotope measurement designed for very small organisms.  


Most studies have reported negative carbon and nitrogen isotope fractionations between hosts and parasites, but isotope values have not yet been determined for many parasite species, such as trematodes, due to their relatively small body sizes. We investigated the carbon and nitrogen isotope values of freshwater snails and trematode parasites by using a method for organisms with very small body sizes. We found negative isotope fractionation values between host snails and trematode parasites, similar to published values for other parasite groups with larger body sizes, which suggest that the mechanisms for determining isotope fractionations between hosts and parasites provide similar results. PMID:19925042

Doi, Hideyuki; Yurlova, Natalia I; Vodyanitskaya, Svetlana N; Kanaya, Gen; Shikano, Shuichi; Kikuchi, Eisuke



Water regulation in aestivating snails  

Microsoft Academic Search

Aestivating snails form abundant lamellate vesicles in the cells of the mantle collar, an epithelium known to regulate the rate at which water is lost from its surface. Since lamellate vesicles are much reduced in hydrated mantle tissue of recently stimulated animals it is tentatively concluded that the vesicles, and their contents, form a barrier to water movement within these

P. F. Newell; J. Machin



Fungal farming in a snail  

Microsoft Academic Search

Mutualisms between fungi and fungus-growing animals are model systems for studying coevolution and complex interactions between species. Fungal growing behavior has enabled cultivating animals to rise to major ecological importance, but evolution of farming symbioses is thought to be restricted to three terrestrial insect lineages. Surveys along 2,000 km of North America's Atlantic coast documented that the marine snail Littoraria

Brian R. Silliman; Steven Y. Newell



Analysis of snail genes in the crustacean Parhyale hawaiensis: insight into snail gene family evolution.  


The transcriptional repressor snail was first discovered in Drosophila melanogaster, where it initially plays a role in gastrulation and mesoderm formation, and later plays a role in neurogenesis. Among arthropods, this role of snail appears to be conserved in the insects Tribolium and Anopheles gambiae, but not in the chelicerates Cupiennius salei and Achaearanea tepidariorum, the myriapod Glomeris marginata, or the Branchiopod crustacean Daphnia magna. These data imply that within arthropoda, snail acquired its role in gastrulation and mesoderm formation in the insect lineage. However, crustaceans are a diverse group with several major taxa, making analysis of more crustaceans necessary to potentially understand the ancestral role of snail in Pancrustacea (crustaceans + insects) and thus in the ancestor of insects as well. To address these questions, we examined the snail family in the Malacostracan crustacean Parhyale hawaiensis. We found three snail homologs, Ph-snail1, Ph-snail2 and Ph-snail3, and one scratch homolog, Ph-scratch. Parhyale snail genes are expressed after gastrulation, during germband formation and elongation. Ph-snail1, Ph-snail2, and Ph-snail3 are expressed in distinct patterns in the neuroectoderm. Ph-snail1 is the only Parhyale snail gene expressed in the mesoderm, where its expression cycles in the mesodermal stem cells, called mesoteloblasts. The mesoteloblasts go through a series of cycles, where each cycle is composed of a migration phase and a division phase. Ph-snail1 is expressed during the migration phase, but not during the division phase. We found that as each mesoteloblast division produces one segment's worth of mesoderm, Ph-snail1 expression is linked to both the cell cycle and the segmental production of mesoderm. PMID:22466422

Hannibal, Roberta L; Price, Alivia L; Parchem, Ronald J; Patel, Nipam H



Growth, fecundity and glycogen utilization in Lymnaea palustris exposed to atrazine and hexachlorobenzene in freshwater mesocosms  

SciTech Connect

Freshwater mesocosms were used to study the long-term sublethal effects of atrazine and hexachlorobenzene (HCB) on a basommatophoran gastropod, Lymnaea palustris (Mueller). Growth, fecundity, and biochemical parameters related to polysaccharide metabolism of pesticide-exposed snails were compared with those of control animals maintained in untreated mesocosms. HCB inhibited body growth and stimulated egg production, whereas atrazine had no relevant effect on these physiological parameters. Also, HCB stimulated the activity of polysaccharide-hydrolyzing enzymes, suggesting that changes in the metabolism of reserve polysaccharides (glycogen) may be involved in the inhibition of growth and increase of fecundity. In contrast, atrazine had no effect on the metabolism of polysaccharides. It is concluded that the effects of HCB are related to its neurotoxicity that would have affected the neurohormonal control of growth and reproduction of exposed snails. It is suggested that polysaccharide-hydrolyzing enzymes may be used as biomarkers to predict the effects of neurotoxic pesticides on freshwater snail populations.

Baturo, W.; Lagadic, L.; Caquet, T. [Univ. de Paris-Sud, Orsay (France). Lab. d`Ecologie et de Zoologie



Factors affecting the distribution and abundance of the commensal Temnocephala iheringi (Platyhelminthes: Temnocephalidae) among the southernmost populations of the apple snail Pomacea canaliculata (Mollusca: Ampullariidae)  

Microsoft Academic Search

Temnocephala iheringi is the most common temnocephalan inhabiting the mantle cavity of the apple snail Pomacea canaliculata, a freshwater neotropical gastropod that has become a serious rice pest in Southeastern Asia. T. iheringi has been recorded from Mato Grosso (Brazil) to water bodies associated with the Río de la Plata river (Argentina). During an extensive survey in the southern limit

Pablo R. Martín; Alejandra L. Estebenet; Silvana Burela



Light-dependent and -independent behavioral effects of extremely low frequency magnetic fields in a land snail are consistent with a parametric resonance mechanism  

SciTech Connect

Exposure to extremely low frequency (ELF) magnetic fields has been shown to attenuate endogenous opioid peptide mediated antinociception or analgesia in the terrestrial pulmonate snail, Cepaea nemoralis. Here the authors examine the roles of light in determining this effect and address the mechanisms associated with mediating the effects of the ELF magnetic fields in both the presence and absence of light. Specifically, they consider whether the magnetic field effects involve an indirect induced electric current mechanism or a direct effect such as a parametric resonance mechanism (PRM). They exposed snails in both the presence and absence of light at three different frequencies (30, 60, and 120 Hz) with static field values (B{sub DC}) and ELF magnetic field amplitude (peak) and direction (B{sub AC}) set according to the predictions of the PRM for Ca{sup 2+}. Analgesia was induced in snails by injecting them with an enkephalinase inhibitor, which augments endogenous opioid (enkephalin) activity. They found that the magnetic field exposure reduced this opioid-induced analgesia significantly more if the exposure occurred in the presence rather than the absence of light. However, the percentage reduction in analgesia in both the presence and absence of light was not dependent on the ELF frequency. This finding suggests that in both the presence and the absence of light the effect of the ELF magnetic field was mediated by a direct magnetic field detection mechanism such as the PRM rather than an induced current mechanism.

Prato, F.S.; Thomas, A.W. [Univ. of Western Ontario, London, Ontario (Canada)] [Univ. of Western Ontario, London, Ontario (Canada); [St. Joseph`s Health Centre, London, Ontario (Canada); Kavaliers, M. [Univ. of Western Ontario, London, Ontario (Canada)] [Univ. of Western Ontario, London, Ontario (Canada); Cullen, A.P. [Univ. of Waterloo, Ontario (Canada). School of Optometry] [Univ. of Waterloo, Ontario (Canada). School of Optometry



Exploring Species Level Taxonomy and Species Delimitation Methods in the Facultatively Self-Fertilizing Land Snail Genus Rumina (Gastropoda: Pulmonata)  

PubMed Central

Delimiting species in facultatively selfing taxa is a challenging problem of which the terrestrial pulmonate snail genus Rumina is a good example. These snails have a mixed breeding system and show a high degree of shell and color variation. Three nominal species (R. decollata, R. saharica and R. paivae) and two color morphs within R. decollata (dark and light) are currently recognized. The present study aims at evaluating to what extent these entities reflect evolutionary diverging taxonomic units, rather than fixed polymorphisms due to sustained selfing. Therefore, a phylogenetic analysis of nuclear (ITS1, ITS2) and mitochondrial DNA (COI, CytB, 12S rDNA, 16S rDNA) sequences was performed. Putative species in Rumina, inferred from the mitochondrial DNA phylogeny, were compared with those proposed on the basis of the COI gene by (1) DNA barcoding gap analysis, (2) Automatic Barcode Gap Discovery, (3) the species delimitation plug-in of the Geneious software, (4) the Genealogical Sorting Index, and (5) the General Mixed Yule Coalescent model. It is shown that these methods produce a variety of different species hypotheses and as such one may wonder to what extent species delimitation methods are really useful. With respect to Rumina, the data suggest at least seven species, one corresponding to R. saharica and six that are currently grouped under the name R. decollata. The species-level status of R. paivae is rejected.

Prevot, Vanya; Jordaens, Kurt; Sonet, Gontran; Backeljau, Thierry



Study of the diet effect on d13C of shell carbonate of the land snail Helix aspersa in experimental conditions  

NASA Astrophysics Data System (ADS)

This study aims to demonstrate the influence of the metabolic CO2 derived from the diet and of the atmospheric CO2 on the shell carbonate d13C of the pulmonate snail Helix aspersa maxima raised under controlled conditions. Adult snails were analyzed and compared with three hatching and one-day young snails stemming from the same breeding. One day after, the two-days old individuals were raised during one month. Three groups of gastropods were fed with fresh lettuce (C3 plant, d13C = -27.49 ppt), three groups with corn (C4 plant, d13C = -11.7 ppt), and three groups ate both (C3 + C4). The difference between the mean d13C values of the adult snails on one hand and the hatched and one-day snails on the other hand indicates a depletion of 2.47 ‰. Therefore, the isotopic parents offspring signal is not preserved. The depleted ingested albumen by the snail embryo in the egg during the built of the shell could explain this depletion. The C3 diet experiment gave the expected isotopic composition difference between the diet (lettuce) and the shells (mean D13Cshell-Lettuce = 13.75 ppt +- 0.52). This result shows a clear diet effect on the isotopic composition of the snail shells. For the C4 experiment, the difference in carbon isotope composition between the corn and the shell (D13Cshell-corn) yielded a mean value of 4.89 ppt +- 0.87. The main result is that D13C is not constant and appears to depend on the type of ingested food. Several hypothesis can raise from this study to explain the different fractionations : a) The differences in quality of the two diets seem to have placed the animals in different growth states, b) Differences in turnover rate for C3 and C4 feeders. The groups regularly fed with mixed diet yielded d13C values, showing a preferential use of C3 food for the most values. The C3-C4 mixed dietary alternation probably led snails to use mainly the lettuce instead of the corn powder.

Metref, S.; Rousseau, D. D.; Bentaleb, I.; Labonne, M.; Vianey-Liaud, M.



Snail modulates cell metabolism in MDCK cells  

SciTech Connect

Highlights: ? MDCK/snail cells were more sensitive to glucose deprivation than MDCK/neo cells. ? MDCK/snail cells had decreased oxidative phosphorylation, O{sub 2} consumption and ATP content. ? TCA cycle enzyme activity, but not expression, was lower in MDCK/snail cells. ? MDCK/snail cells showed reduced PDH activity and increased PDK1 expression. ? MDCK/snail cells showed reduced expression of GLS2 and ACLY. -- Abstract: Snail, a repressor of E-cadherin gene transcription, induces epithelial-to-mesenchymal transition and is involved in tumor progression. Snail also mediates resistance to cell death induced by serum depletion. By contrast, we observed that snail-expressing MDCK (MDCK/snail) cells undergo cell death at a higher rate than control (MDCK/neo) cells in low-glucose medium. Therefore, we investigated whether snail expression influences cell metabolism in MDCK cells. Although gylcolysis was not affected in MDCK/snail cells, they did exhibit reduced pyruvate dehydrogenase (PDH) activity, which controls pyruvate entry into the tricarboxylic acid (TCA) cycle. Indeed, the activity of multiple enzymes involved in the TCA cycle was decreased in MDCK/snail cells, including that of mitochondrial NADP{sup +}-dependent isocitrate dehydrogenase (IDH2), succinate dehydrogenase (SDH), and electron transport Complex II and Complex IV. Consequently, lower ATP content, lower oxygen consumption and increased survival under hypoxic conditions was also observed in MDCK/snail cells compared to MDCK/neo cells. In addition, the expression and promoter activity of pyruvate dehydrogenase kinase 1 (PDK1), which phosphorylates and inhibits the activity of PDH, was increased in MDCK/snail cells, while expression levels of glutaminase 2 (GLS2) and ATP-citrate lyase (ACLY), which are involved in glutaminolysis and fatty acid synthesis, were decreased in MDCK/snail cells. These results suggest that snail modulates cell metabolism by altering the expression and activity of key enzymes. This results in enhanced glucose dependency and leads to cell death under low-glucose conditions. On the other hand, the reduced requirements for oxygen and nutrients from the surrounding environment, might confer the resistance to cell death induced by hypoxia and malnutrition.

Haraguchi, Misako, E-mail: [Department of Biochemistry and Molecular Biology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8544 (Japan)] [Department of Biochemistry and Molecular Biology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8544 (Japan); Indo, Hiroko P. [Department of Maxillofacial Radiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8544 (Japan)] [Department of Maxillofacial Radiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8544 (Japan); Iwasaki, Yasumasa [Health Care Center, Kochi University, Kochi 780-8520 (Japan)] [Health Care Center, Kochi University, Kochi 780-8520 (Japan); Iwashita, Yoichiro [Department of Maxillofacial Radiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8544 (Japan)] [Department of Maxillofacial Radiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8544 (Japan); Fukushige, Tomoko [Department of Dermatology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8544 (Japan)] [Department of Dermatology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8544 (Japan); Majima, Hideyuki J. [Department of Maxillofacial Radiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8544 (Japan)] [Department of Maxillofacial Radiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8544 (Japan); Izumo, Kimiko; Horiuchi, Masahisa [Department of Environmental Medicine, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8544 (Japan)] [Department of Environmental Medicine, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8544 (Japan); Kanekura, Takuro [Department of Dermatology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8544 (Japan)] [Department of Dermatology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8544 (Japan); Furukawa, Tatsuhiko [Department of Molecular Oncology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8544 (Japan)] [Department of Molecular Oncology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8544 (Japan); Ozawa, Masayuki [Department of Biochemistry and Molecular Biology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8544 (Japan)] [Department of Biochemistry and Molecular Biology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8544 (Japan)



Salinity adaptation of the invasive New Zealand mud snail (Potamopyrgus antipodarum) in the Columbia River estuary (Pacific Northwest, USA): physiological and molecular studies  

USGS Publications Warehouse

In this study, we examine salinity stress tolerances of two populations of the invasive species New Zealand mud snail Potamopyrgus antipodarum, one population from a high salinity environment in the Columbia River estuary and the other from a fresh water lake. In 1996, New Zealand mud snails were discovered in the tidal reaches of the Columbia River estuary that is routinely exposed to salinity at near full seawater concentrations. In contrast, in their native habitat and throughout its spread in the western US, New Zealand mud snails are found only in fresh water ecosystems. Our aim was to determine whether the Columbia River snails have become salt water adapted. Using a modification of the standard amphipod sediment toxicity test, salinity tolerance was tested using a range of concentrations up to undiluted seawater, and the snails were sampled for mortality at daily time points. Our results show that the Columbia River snails were more tolerant of acute salinity stress with the LC50 values averaging 38 and 22 Practical Salinity Units for the Columbia River and freshwater snails, respectively. DNA sequence analysis and morphological comparisons of individuals representing each population indicate that they were all P. antipodarum. These results suggest that this species is salt water adaptable and in addition, this investigation helps elucidate the potential of this aquatic invasive organism to adapt to adverse environmental conditions.

Hoy, Marshal; Boese, Bruce L.; Taylor, Louise; Reusser, Deborah; Rodriguez, Rusty



Modelling spatial distribution of snails transmitting parasitic worms with importance to human and animal health and analysis of distributional changes in relation to climate.  


The environment, the on-going global climate change and the ecology of animal species determine the localisation of habitats and the geographical distribution of the various species in nature. The aim of this study was to explore the effects of such changes on snail species not only of interest to naturalists but also of importance to human and animal health. The spatial distribution of freshwater snail intermediate hosts involved in the transmission of schistosomiasis, fascioliasis and paramphistomiasis (i.e. Bulinus globosus, Biomphalaria pfeifferi and Lymnaea natalensis) were modelled by the use of a maximum entropy algorithm (Maxent). Two snail observation datasets from Zimbabwe, from 1988 and 2012, were compared in terms of geospatial distribution and potential distributional change over this 24-year period investigated. Climate data, from the two years were identified and used in a species distribution modelling framework to produce maps of predicted suitable snail habitats. Having both climate- and snail observation data spaced 24 years in time represent a unique opportunity to evaluate biological response of snails to changes in climate variables. The study shows that snail habitat suitability is highly variable in Zimbabwe with foci mainly in the central Highveld but also in areas to the South and West. It is further demonstrated that the spatial distribution of suitable habitats changes with variation in the climatic conditions, and that this parallels that of the predicted climate change. PMID:24893011

Pedersen, Ulrik B; Midzi, Nicholas; Mduluza, Takafira; Soko, White; Stensgaard, Anna-Sofie; Vennervald, Birgitte J; Mukaratirwa, Samson; Kristensen, Thomas K



The cephalic sensory organ in veliger larvae of pulmonates (Gastropoda: Mollusca).  


The apical area of larvae of four primitive pulmonate species was investigated by means of serial ultrathin and light microscope sections. Cephalic sensory organs (CSOs) were found in the larvae of Onchidium cf. branchiferum (Onchidiidae) and Laemodonta octanfracta (Ellobiidae), while no trace of the organ was present in the larvae of Ovatella myosotis (Ellobiidae) or Williamia radiata (Siphonariidae). TEM investigation revealed very similar CSOs in O. cf. branchiferum and L. octanfracta, with characteristic putative sensory cell types: ampullary cells with an internal ampulla containing densely packed cilia, para-ampullary cells with external cilia parallel to the surface, and ciliary tuft cells, bearing short ciliary tufts. The epithelium covering the organ has a thick microvillar border with microvilli laterally bearing a pair of electron-dense accumulations and a glycocalyx with interspersed flat plaque-like elements. While homologues of all major elements of the CSO can be found in other gastropod taxa, for example caenogastropods and opisthobranchs, the homology of the ampullary cell with similar cells in nongastropods appears unlikely. The CSO of L. octanfracta is associated with an additional structure, an epithelial external protrusion, lying ventral to the CSO. The absence of the organ in W. radiata weakens hypotheses on the organ's function of examining settlement conditions and velar control. PMID:11746470

Ruthensteiner, Bernhard; Schaefer, Kurt



Use of black carp (Mylopharyngodon piceus) in biological control of intermediate host snails of fish-borne zoonotic trematodes in nursery ponds in the Red River Delta, Vietnam  

PubMed Central

Background The risks of fish-borne zoonotic trematodes (FZT) to human health constitute an important problem in Vietnam. The infection of humans with these trematodes, such as small liver trematodes (Clonorchis sinensis and Opisthorchis viverrini), intestinal trematodes (Heterophyidae) and others is often thought to be linked to fish culture in areas where the habit of eating raw fish is common. Juvenile fish produced in nurseries are often heavily infected with FZT and since fishes are sold to aquaculture facilities for growth, control of FZT in these fishes should be given priority. Controlling the first intermediate host (i.e., freshwater gastropods), would be an attractive approach, if feasible. The black carp, Mylopharyngodon piceus, is a well-known predator of freshwater snails and is already used successfully for biological control of snails in various parts of the world including Vietnam. Here we report the first trials using it for biological control of intermediate host snails in nursery ponds stocked with 1-week old fry (10–12 mm in length) of Indian carp, Labeo rohita. Methods Semi-field and field experiments were set up to test the effect of black carp on snail populations. In the semi-field experiment a known quantity of snails was initially introduced into a pond which was subsequently stocked with black carp. In the field trial in nursery ponds, density of snails was estimated prior to a nursing cycle and at the end of the cycle (after 9 weeks). Results The results showed that black carp affect the density of snail populations in both semi-field and field conditions. The standing crop of snails in nursery ponds, however, was too high for 2 specimens to greatly reduce snail density within the relatively short nursing cycle. Conclusions We conclude that the black carp can be used in nursery ponds in Northern Vietnam for snail control. Juvenile black carp weighing 100 - 200g should be used because this size primarily prey on intermediate hosts of FZT and other studies have shown that it does not prey on fish fry of other species. It may be necessary to use a high stocking density of black carp or to reduce snail density in the nursery ponds using other measures (e.g. mud removal) prior to stocking fry in order for the black carp to keep the density of intermediate host snails at a very low level.



Celss nutrition system utilizing snails  

NASA Astrophysics Data System (ADS)

At the 40th IAF Congress in Malaga, a nutrition system for a lunar base CELSS was presented. A lunar base with a total of eight crew members was envisaged. In this paper, four species of plants—rice, soybean, lettuce and strawberry—were introduced to the system. These plants were sufficient to satisfy fundamental nutritional needs of the crew members. The supply of nutrition from plants and the human nutritional requirements could almost be balanced. Our study revealed that the necessary plant cultivation area per crew member would be nearly 40 m 3 in the lunar base. The sources of nutrition considered in the study were energy, sugar, fat, amino acids, inorganic salt and vitamins; however, calcium, vitamin B 2, vitamin A and sodium were found to be lacking. Therefore, a subsystem to supply these elements is of considerable value. In this paper, we report on a study for breeding snails and utilizing meat as food. Nutrients supplied from snails are shown to compensate for the abovementioned lacking elements. We evaluate the snail breeder and the associated food supply system as a subsystem of closed ecological life support system.

Midorikawa, Y.; Fujii, T.; Ohira, A.; Nitta, K.


Fungal farming in a snail.  


Mutualisms between fungi and fungus-growing animals are model systems for studying coevolution and complex interactions between species. Fungal growing behavior has enabled cultivating animals to rise to major ecological importance, but evolution of farming symbioses is thought to be restricted to three terrestrial insect lineages. Surveys along 2,000 km of North America's Atlantic coast documented that the marine snail Littoraria irrorata grazes fungus-infected wounds on live marsh grass throughout its range. Field experiments demonstrate a facultative, farming mutualism between Littoraria and intertidal fungi. Snails graze live grass primarily not to feed but to prepare substrate for fungal growth and consume invasive fungi. Fungal removal experiments show that snails and fungi act synergistically to suppress marsh grass production. These results provide a case of fungus farming in the marine environment and outside the class Insecta and reveal a previously undemonstrated ecological mechanism (i.e., facilitation of fungal invasion) by which grazers can exert top-down control of marine plant production. PMID:14657360

Silliman, Brian R; Newell, Steven Y




Microsoft Academic Search

THE transfer of a sample of Bulinus (Physopsis) africanus from water in their natural habitat containing 490 ppm TDS to a laboratory culture medium of 126 ppm TDS was found to be accompanied by a marked increase in the variability of the rate of oxygen consumption among individuals, and resulted in a 46% mortality. Transfer through the same gradient, but




Alarm response of hatchlings of the apple snail, Pomacea canaliculata (Gastropoda: Ampullariidae), to aqueous extracts of other individuals  

Microsoft Academic Search

We examined how hatchlings of the freshwater snail, Pomacea canaliculata, responded to aqueous extracts of conspecific hatchlings. Three, 3-day-old hatchlings were macerated in deionized water (1?mg hatchling per 1?ml water). When 0.5?ml of the aqueous extract was added to a test tube containing 10 hatchlings of the same age and 50?ml of water, the hatchlings in the water began to

Katsuya Ichinose; Yoichi Yusa; Kazuhiro Yoshida



Land Snails of the Lucile Caves ACEC.  

National Technical Information Service (NTIS)

A land snail survey was conducted on the Lucile Caves ACES and vicinity in 1993-1994 as part of a larger survey of the Lower Salmon River valley land snail fauna. Information gathered from earlier surveys in 1989 - 1993 was also included. The area was kno...

T. J. Frest E. J. Johannes



Latitudinal variation of freeze tolerance in intertidal marine snails of the genus melampus (gastropoda: ellobiidae).  


Abstract Low temperatures limit the poleward distribution of many species such that the expansion of geographic range can only be accomplished via evolutionary innovation. We have tested for physiological differences among closely related species to determine whether their poleward latitudinal ranges are limited by tolerance to cold. We measured lower temperature tolerance (LT50) among a group of intertidal pulmonate snails from six congeneric species and nine locales. Differences in tolerance are placed in the context of a molecular phylogeny based on one mitochondrial (cytochrome oxidase subunit I) and two nuclear (histone 3 and a mitochondrial phosphate carrier protein) markers. Temperate species from two separate lineages had significantly lower measures of LT50 than related tropical species. Range differences within the temperate zone, however, were not explained by LT50. These results show that multiple adaptations to cold and freezing may have enabled range expansions out of the tropics in Melampus. However, northern range limits within temperate species are not governed by cold tolerance alone. PMID:24940916

Dennis, A B; Loomis, S H; Hellberg, M E



Environmental calcium modifies induced defences in snails.  

PubMed Central

Inducible defences are adaptive phenotypes that arise in response to predation threats. Such plasticity incurs costs to individuals, but there has been little interest in how such induced traits in animals may be constrained by environmental factors. Here, we demonstrate that calcium availability interacts with predation cues to modify snail shell growth and form. Small snails increased their growth and were heavier when exposed to fish chemical cues, but this response was calcium limited. There was also an interactive effect of fish cues and calcium on the shell growth of larger snails, but shell strength and aperture narrowness were affected by calcium alone. For small snails, behavioural avoidance was greatest for snails exhibiting least morphological plasticity, suggesting a trade-off. There was no trade-off of somatic growth with plasticity. We suggest that the expression of defensive traits in molluscs can be constrained by calcium availability, which has implications for molluscan ecology and evolution.

Rundle, Simon D; Spicer, John I; Coleman, Ross A; Vosper, Jo; Soane, Julie



Morphological and Molecular Characterization of Lymnaeid Snails and Their Potential Role in Transmission of Fasciola spp. in Vietnam  

PubMed Central

Freshwater snails of the family Lymnaeidae play an important role in the transmission of fascioliasis worldwide. In Vietnam, 2 common lymnaeid species, Lymnaea swinhoei and Lymnaea viridis, can be recognized on the basis of morphology, and a third species, Lymnaea sp., is known to exist. Recent studies have raised controversy about their role in transmission of Fasciola spp. because of confusion in identification of the snail hosts. The aim of this study is, therefore, to clarify the identities of lymnaeid snails in Vietnam by a combination of morphological and molecular approaches. The molecular analyses using the second internal transcribed spacer (ITS2) of the nuclear ribosomal DNA clearly showed that lymnaeids in Vietnam include 3 species, Austropeplea viridis (morphologically identified as L. viridis), Radix auricularia (morphologically identified as L. swinhoei) and Radix rubiginosa (morphologically identified as Lymnaea sp.). R. rubiginosa is a new record for Vietnam. Among them, only A. viridis was found to be infected with Fasciola spp. These results provide a new insight into lymnaeid snails in Vietnam. Identification of lymnaeid snails in Vietnam and their role in the liver fluke transmission should be further investigated.

Doanh, Pham Ngoc; The, Dang Tat; Loan, Ho Thi; Losson, Bertrand; Caron, Yannick



Snail Protein Family in Drosophila Neurogenesis: a Dissertation  

Microsoft Academic Search

The Snail protein functions as a transcriptional regulator to establish early mesodermal cell fate in Drosophila. Later, in germ band-extended embryos, Snail is considered a pan-neural protein based on its extensive expression in neuroblasts. The evidence presented in thesis links snail expression and function in CNS. Cloning and functional characterization of a novel snail homologue, in Drosophila, are also described

Shovon I. Ashraf



Phylogenomics supports Panpulmonata: opisthobranch paraphyly and key evolutionary steps in a major radiation of gastropod molluscs.  


Pulmonates, with over 30,000 described species, represent the largest radiation of non-marine animals outside of Arthropoda. The pulmonate lung was a key evolutionary innovation enabling diversification of terrestrial and freshwater snails and slugs. However, recent studies drew conflicting conclusions about pulmonate monophyly, and support for a sister group is lacking, hindering our understanding of this major animal radiation. Analyses of mitochondrial protein-coding genes recovered a paraphyletic Pulmonata grading into a monophyletic Opisthobranchia, a traditional group of sea slugs long considered sister to pulmonates. Conversely, analyses of datsets dominated by nuclear rDNA indicated Opisthobranchia is paraphyletic with respect to Pulmonata. No study resolved the placement of two key taxa: Sacoglossa, an opisthobranch group including photosynthetic sea slugs, and Siphonarioidea, intertidal limpet-like snails traditionally in Pulmonata. To examine evolutionary relationships at the base of the pulmonate radiation, we performed a phylogenomic analysis of 102 nuclear protein-coding gene regions for 19 gastropods. Opisthobranchia was recovered as paraphyletic with respect to Panpulmonata, a clade in which Sacoglossa was sister to Pulmonata, with Siphonarioidea as the basal pulmonate lineage. Siphonarioideans share a similar gill structure with shelled sacoglossans but lack the contractile pneumostome of pulmonates, suggesting descent from an evolutionary intermediate that facilitated the pulmonate radiation into non-marine habitats. PMID:23850501

Kocot, Kevin M; Halanych, Kenneth M; Krug, Patrick J



Snail Destabilizes Cell Surface Crumbs3a  

PubMed Central

During Epithelial to Mesenchymal Transition (EMT), cells modulate expression of proteins resulting in loss of apical-basal polarity. Effectors of this EMT switch target the polarity protein Crumbs3a, a small transmembrane protein that is essential for generation of the apical membrane and tight junctions of mammalian epithelial cells. We previously showed that the Crumbs3 gene is a direct target of transcriptional regulation by Snail, a potent inducer of EMT. However, Snail has also been shown to have multiple non-transcriptional roles, including regulation of cell adhesion, proliferation and survival. Using SNAP-tag labeling, we determined that cell surface Crumbs3a has a half-life of approximately 3 hours and that this cell surface half-life is significantly reduced when EMT is induced by Snail. We further observe that Snail induces differential glycosylation of Crumbs3a, including sialylation, suggesting a mechanism by which Crumbs3a may be destabilized. These results indicate that Crumbs3a is a post-translational target of Snail, in addition to being a transcriptional target. We conclude that Snail’s ability to post-translationally modify and destabilize Crumbs3a augments the depolarizing process of EMT.

Harder, Jennifer L.; Whiteman, Eileen L.; Pieczynski, Jay N.; Liu, Chia-Jen; Margolis, Ben



Freshwater molluscs as indicators of bioavailability and toxicity of metals in surface-water systems  

SciTech Connect

Freshwater molluscs--snails and bivalves--have been used frequently as bioindicator organisms. With increasing needs for research on contaminant effects in freshwater ecosystems, this kind of biomonitoring is likely to develop further in the future. Molluscs can be used effectively for studies of both organic and inorganic contaminants; this review focuses on studies involving bioaccumulation and toxicity of metals. Two important advantages of snails and bivalves over most other freshwater organisms for biomonitoring research are their large size and limited mobility. In addition, they are abundant in many types of freshwater environments and are relatively easy to collect and identify. At metal concentrations that are within ranges common to natural waters, they are generally effective bioaccumulators of metals. Biomonitoring studies with freshwater molluscs have covered a wide diversity of species, metals, and environments. The principal generalization that can be drawn from this research is that bioaccumulation and toxicity are extremely situation dependent; hence, it is difficult to extrapolate results from any particular study to other situations where the biological species or environmental conditions are different. Even within one species, individual characteristics such as size, life stage, sex, and genotype can have significant effects on responses to contaminants. The bioavailability of the metal is highly variable and depends on pH, presence of organic ligands, water hardness, and numerous other controlling factors. Despite this variability, past studies provide some general principles that can facilitate planning of research with freshwater snails and bivalves as metal bioindicators. These principles may also be useful in understanding and managing freshwater ecosystems.

Elder, J.F.; Collins, J.J. (U.S. Geological Survey, Madison, WI (United States))



Epigenetic regulation of EMT: the Snail story.  


While the epithelial-mesenchymal transition (EMT) plays a fundamental role during development, its deregulation can adversely promote tumor metastasis. The phenotypic and cellular plasticity of EMT indicates that it is subject to epigenetic regulation. A hallmark of EMT is E-cadherin suppression. In this review, we try to embrace recent findings on the transcription factor Snail-mediated epigenetic silencing of E-cadherin. Our studies as well as those of others independently demonstrated that Snail can recruit various epigenetic machineries to the E-cadherin promoter. Based on these results, we propose a model of epigenetic regulation of EMT governed by Snail. Briefly, recruitment of the LSD1/HDAC complex by Snail facilitates histone H3K4 demethylation and H3/H4 deacetylation. Histone deacetylation may promote subsequent recruitment of PRC2 to methylate H3K27, while H3K4 demethylation favors the association of H3K9 methyltransferases G9a and Suv39H1. Finally, DNA methyltransferases (DNMTs) can be recruited to the promoter area in a G9a/Suv39H1-dependent manner. Together, these chromatin-modifying enzymes function in a Snail-mediated, highly orchestrated fashion to suppress E-cadherin. Disruption of the connection between Snail and these epigenetic machineries may represent an efficient strategy for the treatment of EMT-related diseases, including tumor metastasis. PMID:23888971

Lin, Yiwei; Dong, Chenfang; Zhou, Binhua P



The role of Snail in prostate cancer  

PubMed Central

Prostate cancer is the second most frequently diagnosed cancer and the sixth leading cause of death from cancer in men. Epithelial-mesenchymal transition (EMT) is a process by which cancer cells invade and migrate, and is characterized by loss of cell-cell adhesion molecules such as E-cadherin and increased expression of mesenchymal proteins such as vimentin; EMT is also associated with resistance to therapy. Snail, a master regulator of EMT, has been extensively studied and reported in cancers such as breast and colon; however, its role in prostate cancer is not as widely reported. The purpose of this review is to put together recent facts that summarize Snail signaling in human prostate cancer. Snail is overexpressed in prostate cancer and its expression and activity is controlled via phosphorylation and growth factor signaling. Snail is involved in its canonical role of inducing EMT in prostate cancer cells; however, it plays a role in non-canonical pathways that do not involve EMT such regulation of bone turnover and neuroendocrine differentiation. Thus, studies indicate that Snail signaling contributes to prostate cancer progression and metastasis and therapeutic targeting of Snail in prostate cancer holds promise in ?future.

Smith, Bethany N.; Odero-Marah, Valerie A.



New Pest Response Guidelines: Giant African Snails: Snail Pests in the Family Achatinidae.  

National Technical Information Service (NTIS)

Use New Pest Response Guidelines. Giant African Snails: Snail Pests in the Family Achatinidae as a guide when designing a program to detect, monitor, control, contain, or eradicate an infestation of achatinids. If these pests are detected in the United St...



Identification and characterization of a goose-type lysozyme from sewage snail Physa acuta.  


Freshwater snail Physa acuta has been considered as an important invasive species and medical mollusc. Field investigation has shown that this snail could survive better than other snails in polluted water bodies. To understand the immune mechanisms of P. acuta, suppression subtractive hybridization hepatopancreas cDNA library has been constructed with bacterial challenge. In this study, a full-length cDNA of a novel goose-type lysozyme (PALysG) has been identified from P. acuta by EST and RACE technique. The conservative structure domains share high homology with other molluscan g-type lysozymes including the SLT domain, the substrate binding sites, the catalytic residues, three alpha-helices structures and six molluscan specific cysteines. Meanwhile, PALysG is the first record of goose-type lysozyme in Gastropoda. Real-time PCR indicated that PALysG mRNA had been expressed significantly at high levels in hepatopancreas for 8-48 h. PALysG recombinant protein displayed the lytic activity of g-type lysozyme with other organisms against Micrococcus lysodikicus. PMID:24882016

Guo, Yunhai; He, Hongxuan



Behavioural responses of the snail Lymnaea acuminata to carbohydrates in snail-attractant pellets  

NASA Astrophysics Data System (ADS)

Snail control is one of the most important tools in the campaign to reduce the incidence of fascioliasis. In order to attain this objective, the method of bait formulation in order to contain an attractant and a molluscicide is an expedient approach to lure the target snail population to the molluscicide. This study identifies certain carbohydrates, namely sucrose, maltose, glucose, fructose and starch, for preparing such baits. These were tested on Lymnaea acuminata, an intermediate host of the digenean trematodes Fasciola hepatica and Fasciola gigantica. The behavioural responses of snails to these carbohydrates were examined. Significant variations in behavioural responses were observed in the snail even when the five carbohydrates were used in low concentrations in snail-attractant pellets. Starch emerged as the strongest attractant for Lymnaea acuminata, followed by maltose.

Tiwari, Farindra; Singh, D. K.


The Apple Snail Pomacea canaliculata, a Novel Vector of the Rat Lungworm, Angiostrongylus cantonensis: its Introduction, Spread, and Control in China  

PubMed Central

The freshwater apple snail Pomacea canaliculata was introduced to Taiwan then to mainland China in the early 1980s from Argentina, its native region, for the purpose of aquaculture. Because of the lack of natural enemies and its tolerance of a wide range of environmental conditions, both its abundance and distribution have dramatically increased and it has become a harmful species to local agriculture and other native species in many areas of China. Unfortunately, the snail also acts as an intermediate host of Angiostrongylus cantonensis, and has been implicated in transfer of the parasite to people, resulting in angiostrongyliasis manifested as eosinophilic meningitis. Efforts to prevent its further spread and population expansion were initiated many years ago, including the use of chemicals and biological control agents to control the snail.

Wu, Zhong-Dao; Lun, Zhao-Rong



Testosterone levels and fecundity in the hermaphroditic aquatic snail Lymnaea stagnalis exposed to testosterone and endocrine disruptors.  


Endocrine disruptors are known to alter endogenous free and esterified levels of androgenic and estrogenic steroid hormones in aquatic mollusks. The origin of steroids in these animals, however, remains controversial. In the present study, free and esterified testosterone concentrations were measured in the hermaphroditic aquatic gastropod Lymnaea stagnalis exposed to molecules known for their androgenic (testosterone and tributyltin), anti-androgenic (cyproterone-acetate), and estrogenic (chlordecone) properties, by reference to their mode of action in vertebrates. In parallel, snail oviposition and fecundity were followed over a 21-d exposure period. Testosterone exposure resulted in increased esterified testosterone levels, whereas free testosterone concentrations remained stable. In contrast, cyproterone-acetate significantly increased the free form of testosterone with no changes in the esterified form, whereas chlordecone showed a tendency to reduce (though not significantly) esterified testosterone concentrations without changing free testosterone levels. Finally, tributyltin did not alter testosterone homeostasis. The production of egg clutches and eggs was significantly reduced only in the snails exposed to the highest concentrations of chlordecone (19.6?µg/L) and tributyltin (94.2?ng Sn/L). Overall, the present study demonstrates that uptake of testosterone from the exposure medium occurs in L. stagnalis. Moreover, it shows that cyproterone-acetate and, to a lesser extent, chlordecone can alter endogenous testosterone levels in this freshwater snail. However, the relationship between hormonal changes and snail reproduction has not been established. Environ Toxicol Chem 2013;32:1740-1745. © 2013 SETAC. PMID:23564527

Giusti, Arnaud; Ducrot, Virginie; Joaquim-Justo, Célia; Lagadic, Laurent



Exposure of the snail Potamopyrgus antipodarum to herbicide boosts output and survival of parasite infective stages.  


Anthropogenic stressors such as pollutants can modulate levels of parasitic infections in aquatic animals by suppressing host immunity or through some other mechanisms. One such mechanism could involve increases in either the quantity or quality of infective stages produced by parasites. We investigated the effect of exposure of infected snails, Potamopyrgus antipodarum, to different concentrations of the widely-used herbicide glyphosate, on (i) the production of infective cercariae by three trematode species, Coitocaecum parvum, Apatemon sp. and an undescribed renicolid, and (ii) the survival of cercariae of the latter species. For all three trematode species, infected snails exposed over a month to low (0.36 mg a.i. L(-1)) or medium (3.6 mg a.i. L(-1)) formulated glyphosate concentrations released between 1.5 and 3 times more cercariae per day than snails under control conditions. The similar pattern seen in all trematodes suggests a general weakening of the host benefiting any of its parasites rather than some parasite species-specific mechanism. In addition, the survival of renicolid cercariae improved with increasing glyphosate concentrations, with cercariae living about 50% longer in the medium concentration (3.6 mg a.i. L(-1)) than in control conditions. Our results demonstrate a clear interaction between glyphosate pollution and parasitism by trematodes in freshwater systems, occurring at glyphosate concentrations recorded in aquatic habitats, and within the environmental exposure limit allowed in New Zealand freshwaters. Future risk assessments and toxicity tests need to consider indirect impacts resulting from infections to invertebrate and vertebrate species penetrated by cercariae and serving as second intermediate hosts of trematodes. PMID:24533309

Hock, Sabrina D; Poulin, Robert



Exposure of the snail Potamopyrgus antipodarum to herbicide boosts output and survival of parasite infective stages?  

PubMed Central

Anthropogenic stressors such as pollutants can modulate levels of parasitic infections in aquatic animals by suppressing host immunity or through some other mechanisms. One such mechanism could involve increases in either the quantity or quality of infective stages produced by parasites. We investigated the effect of exposure of infected snails, Potamopyrgus antipodarum, to different concentrations of the widely-used herbicide glyphosate, on (i) the production of infective cercariae by three trematode species, Coitocaecum parvum, Apatemon sp. and an undescribed renicolid, and (ii) the survival of cercariae of the latter species. For all three trematode species, infected snails exposed over a month to low (0.36 mg a.i. L?1) or medium (3.6 mg a.i. L?1) formulated glyphosate concentrations released between 1.5 and 3 times more cercariae per day than snails under control conditions. The similar pattern seen in all trematodes suggests a general weakening of the host benefiting any of its parasites rather than some parasite species-specific mechanism. In addition, the survival of renicolid cercariae improved with increasing glyphosate concentrations, with cercariae living about 50% longer in the medium concentration (3.6 mg a.i. L?1) than in control conditions. Our results demonstrate a clear interaction between glyphosate pollution and parasitism by trematodes in freshwater systems, occurring at glyphosate concentrations recorded in aquatic habitats, and within the environmental exposure limit allowed in New Zealand freshwaters. Future risk assessments and toxicity tests need to consider indirect impacts resulting from infections to invertebrate and vertebrate species penetrated by cercariae and serving as second intermediate hosts of trematodes.

Hock, Sabrina D.; Poulin, Robert



Comparison of long-term postoperative sequelae in patients with tetralogy of fallot versus isolated pulmonic stenosis.  


Patients with tetralogy of Fallot (TOF) after complete repair and pulmonic stenosis (PS) after surgical valvotomy often develop significant pulmonic regurgitation (PR) that eventually requires valve replacement. Although criteria exist for the timing of pulmonary valve replacement in TOF, it remains less clear when to intervene in valvotomy patients and whether TOF recommendations can be applied. Our aim was to compare the structural and functional sequelae of valvotomy for PS with complete repair for TOF. We compared the clinical characteristics, electrocardiograms, echocardiograms, cardiac magnetic resonance imaging (MRI), and invasive hemodynamics of 109 adults (34 PS and 75 TOF) newly referred to a congenital heart disease center for evaluation of PR between 2005 and 2012. Both cohorts were similar in terms of baseline demographics and presenting New York Heart Association function class. Valvotomy patients had a slightly greater degree of PR by echocardiogram, although it was similar by cardiac MRI. Electrocardiography QRS width was greater in patients with TOF (114 ± 27 vs 150 ± 28 ms, p <0.001). MRI right ventricular ejection fraction (49 ± 8 vs 41 ± 11%, p = 0.001) and left ventricular ejection fraction (59 ± 7 vs 52 ± 10%, p = 0.002) were lower in patients with TOF. Pacemaker or defibrillator implantation was significantly greater in patients with TOF (3% vs 23%, p = 0.011). In conclusion, patients postvalvotomy and complete repair present with similar degrees of PR and severity of symptoms. Biventricular systolic function and electrocardiography QRS width appear less affected, suggesting morphologic changes in TOF and its repair that extend beyond the effects of PR. These findings suggest the need for developing disease-specific guidelines for patients with PR postvalvotomy. PMID:24878128

Zdradzinski, Michael J; Qureshi, Athar M; Stewart, Robert; Pettersson, Gosta; Krasuski, Richard A



Relationships between nutrient enrichment, pleurocerid snail density and trematode infection rate in streams  

USGS Publications Warehouse

Summary 1. Nutrient enrichment is a widespread environmental problem in freshwater ecosystems. Eutrophic conditions caused by nutrient enrichment may result in a higher prevalence of infection by trematode parasites in host populations, due to greater resource availability for the molluscan first intermediate hosts. 2. This study examined relationships among land use, environmental variables indicating eutrophication, population density of the pleurocerid snail, Leptoxis carinata, and trematode infections. Fifteen study sites were located in streams within the Shenandoah River catchment (Virginia, U.S.A.), where widespread nutrient enrichment has occurred. 3. Snail population density had a weak positive relationship with stream water nutrient concentration. Snail population density also increased as human activities within stream catchments increased, but density did not continue to increase in catchments where anthropogenic disturbance was greatest. 4. Cercariae from five families of trematodes were identified in L. carinata, and infection rate was generally low (<10%). Neither total infection rate nor the infection rate of individual trematode types showed a positive relationship with snail population density, nutrients or land use. 5. There were statistically significant but weak relationships between the prevalence of infection by two trematode families and physical and biological variables. The prevalence of Notocotylidae was positively related to water depth, which may be related to habitat use by definitive hosts. Prevalence of Opecoelidae had a negative relationship with orthophosphate concentration and a polynomial relationship with chlorophyll a concentration. Transmission of Opecoelid trematodes between hosts may be inhibited by eutrophic conditions. 6. Leptoxis carinata appears to be a useful species for monitoring the biological effects of eutrophication and investigating trematode transmission dynamics in lotic systems.

Ciparis, Serena; Iwanowicz, Deborah D.; Voshell, J. Reese, Jr.




Microsoft Academic Search

SUMMARY The secretory cells of the salivary glands of the snail, HeUsoma trivolvis, exhibit regenerative, overshooting action potentials whose amplitude may exceed 100 mV. The salivary glands consist of paired, tubular, epithelial structures with acinar outpocketings. The secretory cells display extensive electrical coupling which allows action potentials to propagate along the glandular epithelium. Salivary glands from nine genera of gastropod



Snail depletes the tumorigenic potential of glioblastoma  

PubMed Central

Glioblastoma multiforme (GBM) is an aggressive brain malignancy characterized by high heterogeneity and invasiveness. It is increasingly accepted that the refractory feature of GBM to current therapies stems from the existence of few tumorigenic cells that sustain tumor growth and spreading, the so-called glioma-initiating cells (GICs). Previous studies showed that cytokines of the bone morphogenetic protein (BMP) family induce differentiation of the GICs, and thus act as tumor suppressors. Molecular pathways that explain this behavior of BMP cytokines remain largely elusive. Here, we show that BMP signaling induces Smad-dependent expression of the transcriptional regulator Snail in a rapid and sustained manner. Consistent with its already established promigratory function in other cell types, we report that Snail silencing decreases GBM cell migration. Consequently, overexpression of Snail increases GBM invasiveness in a mouse xenograft model. Surprisingly, we found that Snail depletes the GBM capacity to form gliomaspheres in vitro and to grow tumors in vivo, both of which are important features shared by GICs. Thus Snail, acting downstream of BMP signaling, dissociates the invasive capacity of GBM cells from their tumorigenic potential.

Savary, K; Caglayan, D; Caja, L; Tzavlaki, K; Bin Nayeem, S; Bergstrom, T; Jiang, Y; Uhrbom, L; Forsberg-Nilsson, K; Westermark, B; Heldin, C-H; Ferletta, M; Moustakas, A



Larval trematodes: double infections in common mud-flat snail.  


Larvae of the trematode Zoogonus lasius are involved in most double infections of Nassarius obsoleta. The two most common trematode parasites of this snail do not occur together in double infections. Double infections were found in 14 of 340 infected snails in a total sample of 5025 snails. PMID:5770621

Vernberg, W B; Vernberg, F J; Beckerdite, F W



Extinction or survival: partulid tree snails in American Samoa?  

Microsoft Academic Search

Four partulid tree snail species are known from American Samoa. In 1998, we surveyed the recently established National Park (units on three islands: Tutuila, Tau, Ofu) and neighboring areas for partulids. On Tutuila, Samoana abbreviata, previously considered probably extinct, was extremely rare (15 snails seen); Samoana conicawas more common (288 snails) but still rare; Eua zebrina was the most common




Induced chemical defenses in a freshwater macrophyte suppress herbivore fitness and the growth of associated microbes.  


The freshwater macrophyte Cabomba caroliniana induces a chemical defense when attacked by either the crayfish Procambrus clarkii or the snail Pomacea canaliculata. Induction by either consumer lowers the palatability of the plant to both consumers. When offered food ad libitum, snails feeding on non-induced C. caroliniana grew 2.6-2.7 times more than those feeding on induced C. caroliniana. Because snails fed less on induced plants, this could be a behavioral effect (reduced feeding), a physiological effect of the induced metabolites on the consumer, or both. To assess these possibilities, we made artificial diets with lipid extracts of induced versus non-induced C. caroliniana and restricted control snails to consuming only as much as treatment snails consumed. Growth measured as shell diameter was significantly lower on the diet containing extract from induced, as opposed to non-induced, plants; change in snail mass was more variable and showed a similar, but non-significant, trend. Thus, snails may reduce feeding on induced plants to avoid suppression of fitness. The induced defenses also suppressed growth of co-occurring microbes that might attack the plant through herbivore-generated feeding scars. When two bacteria and three fungi isolated from C. caroliniana surfaces were cultured with the lipid extract from induced and non-induced C. caroliniana, both extracts inhibited the microbes, but the induced extract was more potent against three of the five potential pathogens. Thus, induced plant defenses can act against both direct consumers and microbes that might invade the plant indirectly through herbivore-generated wounds. PMID:20927537

Morrison, Wendy E; Hay, Mark E



Snail phenotypic variation and stress proteins: do different heat response strategies contribute to Waddington's widget in field populations?  


On the basis of studies with laboratory strains of Drosophila and Arabidopsis, it has been hypothesized that potential buffers to the expression of phenotypic morphological variation, such as Hsp90 and possibly Hsp70, represent important components of Waddington's widget, which may confer capacitive evolution. As studies on field populations of living organisms to test this hypothesis are lacking, we tested whether a heat response strategy involving high stress protein levels is associated with low morphological variation and vice versa, using four natural populations of Mediterranean pulmonate snails. In response to 8 hr of elevated temperatures, a population of Xeropicta derbentina with uniform shell pigmentation pattern showed remarkably high Hsp70 but low Hsp90 levels. In contrast, a highly variable population of Cernuella virgata kept both Hsp90 and Hsp70 levels low when held at diverse though environmentally relevant temperatures. Two other populations (Theba pisana and another X. derbentina population) with intermediate variation in shell pigmentation pattern were also intermediate in inducing Hsp70, though Hsp90 was maintained at a low level. The observed correlation of stress protein levels and coloration pattern variation provide the first indirect evidence for an association of stress proteins with Waddington's widget under natural conditions. PMID:19065565

Köhler, Heinz-R; Lazzara, Raimondo; Dittbrenner, Nils; Capowiez, Yvan; Mazzia, Christophe; Triebskorn, Rita



Rapid upregulation of heart antioxidant enzymes during arousal from estivation in the Giant African snail (Achatina fulica).  


Estivation is an adaptive response to environments characterized by elevated temperatures and desiccative stress, as may occur during summer dry seasons. Similar to diapause and hibernation, it is characterized by low levels of activity, a drastically suppressed metabolic rate and enhanced stress resistance. We tested the hypothesis that Achatina fulica, a pulmonate land snail, enhances stress resistance during estivation and/or arousal by upregulating intracellular antioxidant defenses in the heart, kidney, hepatopancreas and foot tissues. No statistically significant changes in mitochondrial or cytosolic superoxide dismutase levels or activities, or glutathione peroxidase, glutathione reductase or catalase activities were associated with estivation in any tissue, however. In contrast, during arousal from estivation, activities of several antioxidant enzymes increased in heart, hepatopancreas and foot. In heart, a rapid increase in MnSOD protein levels was observed that peaked at 2h post arousal, but no such change was observed in CuZnSOD protein levels. Glutathione peroxidase activity was upregulated at 1h post arousal and remained elevated until 8h post arousal in heart tissue. Glutathione peroxidase was also upregulated at 24h post arousal in foot tissue. Glutathione reductase activity was upregulated at 4h post arousal in heart and foot tissues whereas catalase activity showed no changes. Markers of lipid peroxidation and protein damage revealed no significant increases during estivation or arousal. Therefore, antioxidant enzymes may play a role in oxidative stress defense specifically during arousal from estivation in A. fulica. PMID:20621194

Salway, Kurtis D; Tattersall, Glenn J; Stuart, Jeffrey A



Epigenetic Regulation of EMT: The Snail Story  

PubMed Central

While the epithelial-mesenchymal transition (EMT) plays a fundamental role during development, its deregulation can adversely promote tumor metastasis. The phenotypic and cellular plasticity of EMT indicates that it is subject to epigenetic regulation. In this review, we try to embrace recent findings on the mechanisms of the transcription factor Snail-mediated E-cadherin silencing, which is a hallmark of EMT. Our studies as well as those of others have clearly demonstrated that Snail can recruit multiple chromatin enzymes including LSD1, HDAC1/2, PRC2, G9a and Suv39H1 to the E-cadherin promoter. These enzymes function in a highly orchestrated fashion to generate heterochromatin and promote DNA methyltransferase (DNMT)-mediated DNA methylation at the promoter region. Disruption of the connection between Snail and these chromatin-modifying enzymes may represent an efficient strategy for the treatment of EMT-related diseases.

Lin, Yiwei; Dong, Chenfang; Zhou, Binhua P.



Conserving Madagascar's Freshwater Biodiversity  

NSDL National Science Digital Library

This peer-reviewed article from BioScience is about conserving freshwater diversity in Madagascar. The island nation of Madagascar, an international conservation priority, is now also recognized as a global hotspot for freshwater biodiversity. Three emerging characteristics of Madagascar's threatened freshwater biota deserve increased attention from the scientific and conservation communities. First, species richness is not low, as was once assumed for both the freshwater fishes and the invertebrates. Second, many species are restricted to a specific region or even to single river basins. Often these species are also limited to streams or rivers draining primary forest habitat. Finally, many of the island's freshwater fishes are basal taxa, having diverged earlier than any other extant members of their clade. As such, these taxa assume disproportional phylogenetic importance. In the face of ongoing environmental threats, links among microendemism, forest stream specialization, and basal phylogenetic position highlight the importance and vulnerability of these species and provide a powerful incentive for immediate conservation action.




Mate desertion in the snail kite  

USGS Publications Warehouse

Mate desertion during the breeding cycle was documented at 28 of 36 (78%) snail kite, Rostrhamus sociabilis nests in Florida between 1979 and 1983. Offspring mortality occurred at only one deserted nest, however. Parents that were deserted by their mates continued to care for their young until independence (3?5 additional weeks) and provided snails at a rate similar to that of both parents combined before desertion. Males and females deserted with nearly equal frequency, except in 1982 when more females deserted. No desertion occurred during drought years, whereas desertion occurred at nearly every nest during favourable conditions. The occurrence of mate desertion was generally related to indirect measures of snail abundance: foraging range, snail delivery rates to the young and growth rates. Small broods were deserted more frequently by females than by males and tended to be deserted earlier than large ones. After desertion, deserters had the opportunity to re-mate and nest again since breeding seasons were commonly lengthy, but whether they did so was impossible to determine conclusively in most cases. The deserted bird sometimes incurred increased energetic costs and lost breeding opportunities during periods of monoparental care.

Beissinger, S.R.; Snyder, N.F.R.




Microsoft Academic Search

Madagascar's known native land-snail fauna is currently classified into 540 species (97% endemic) in 68 genera (29% endemic) in 25 families (0% endemic). Recent survey work throughout the island may as much as double this number of species and should provide, for the first time, adequate material and distributional data for robust cladistic and biogeographic analyses. Preliminary analysis of existing




What happens when snails get sick?  

NSDL National Science Digital Library

Scientists used to think that the two major groups of animals, vertebrates and invertebrates, protected themselves from getting sick in very different ways. A new study in snails suggests that both groups' immune systems might be slightly more similar than previously thought.

American Association for the Advancement of Science (AAAS;)



A 3' enhancer controls snail expression in melanoma cells.  


The snail gene encodes a transcriptional repressor that functions during animal development and in cancer progression to promote epithelial-mesenchymal transitions. Strict spatial and temporal boundaries of Snail expression in development imply precise transcriptional control, which becomes inappropriately activated in many cancer subtypes. To gain insight into the molecular mechanism(s) governing transcriptional control of Snail, we analyze chromatin structural changes associated with Snail transcription in melanoma cells. Regardless of transcriptional status, the Snail promoter displays three constitutive DNase hypersensitive sites (HS) and a moderate level of histone H3 Lys(4) dimethylation. A robust HS is found in the 3' region of A375 melanoma cells, in which Snail is highly expressed, but is absent in cells not expressing Snail. This element is conserved throughout the mammalian lineage and strongly activates expression of a reporter in A375 and Colo829 melanoma cells, but not in keratinocytes or primary melanocytes. Activity of this enhancer is associated with enrichment of H3 Lys(4) dimethylation and H3 acetylation at both the enhancer and the promoter. Additionally, enhancer activity is associated with H3 Lys(4) trimethylation at the promoter. A physical interaction between the 3' enhancer and promoter was observed in Snail-expressing cells, demonstrating a direct role for the enhancer in Snail expression. These results suggest a model in which the Snail promoter is constitutively packaged in a poised chromatin structure that can be activated in melanoma cells by a tissue-specific enhancer, which physically contacts the promoter. PMID:17616667

Palmer, Matthew B; Majumder, Parimal; Green, Myesha R; Wade, Paul A; Boss, Jeremy M



Climate and pH predict the potential range of the invasive apple snail (Pomacea insularum) in the southeastern United States.  


Predicting the potential range of invasive species is essential for risk assessment, monitoring, and management, and it can also inform us about a species' overall potential invasiveness. However, modeling the distribution of invasive species that have not reached their equilibrium distribution can be problematic for many predictive approaches. We apply the modeling approach of maximum entropy (MaxEnt) that is effective with incomplete, presence-only datasets to predict the distribution of the invasive island apple snail, Pomacea insularum. This freshwater snail is native to South America and has been spreading in the USA over the last decade from its initial introductions in Texas and Florida. It has now been documented throughout eight southeastern states. The snail's extensive consumption of aquatic vegetation and ability to accumulate and transmit algal toxins through the food web heighten concerns about its spread. Our model shows that under current climate conditions the snail should remain mostly confined to the coastal plain of the southeastern USA where it is limited by minimum temperature in the coldest month and precipitation in the warmest quarter. Furthermore, low pH waters (pH <5.5) are detrimental to the snail's survival and persistence. Of particular note are low-pH blackwater swamps, especially Okefenokee Swamp in southern Georgia (with a pH below 4 in many areas), which are predicted to preclude the snail's establishment even though many of these areas are well matched climatically. Our results elucidate the factors that affect the regional distribution of P. insularum, while simultaneously presenting a spatial basis for the prediction of its future spread. Furthermore, the model for this species exemplifies that combining climatic and habitat variables is a powerful way to model distributions of invasive species. PMID:23451090

Byers, James E; McDowell, William G; Dodd, Shelley R; Haynie, Rebecca S; Pintor, Lauren M; Wilde, Susan B



Inheritance of Schistosoma mansoni infection incompatibility in Biomphalaria alexandrina snails.  


In this study, we looked at the inheritance of susceptibility and resistance to Schistosoma mansoni infection in the first generation of crossbred Biomphalaria alexandrina snails. Our ultimate goal is to use such information to develop a biological method of controlling schistosomiasis. We infected laboratory-bred snails with S. mansoni miracidia and examined cercarial shedding to determine susceptibility and resistance. Five parental groups were used: Group I contained 30 susceptible snails, Group II contained 30 resistant snails, Group III contained 15 susceptible and 15 resistant snails, Group IV contained 27 susceptible and three resistant snails and Group V contained three susceptible and 27 resistant snails. The percentage of resistant snails in the resulting progeny varied according to the ratio of susceptible and resistant parents per group; they are 7%, 100%, 68%, 45% and 97% from Groups I, II, III, IV and V, respectively. On increasing the percentage of resistant parent snails, the percentage of resistant progeny increased, while cercarial production in their susceptible progeny decreased. PMID:20428673

El Naga, Iman F Abou; Eissa, Maha M; Mossallam, Shereen F; El-Halim, Safaa I Abd



Fascioliasis of livestock and snail host for Fasciola in the Altiplano Region of Bolivia.  


Fascioliasis caused by Fasciola hepatica was a serious problem for sheep and alpacas in the Altiplano Region of Bolivia. In some provinces close to Lake Titicaca, the raising of sheep was forced to discontinue, because infection with the fluke made it unprofitable and almost impossible. It was proved that in the Altiplano Region, two species of freshwater snails, Lymnaea viatrix and L. cubensis var., served as intermediate hosts for F. hepatica. In some subtropical areas of Bolivia, these snails could not be found, although other Lymnaea sp. was widely distributed there. As it is possible for Lymnaea sp. to be intermediate host for the fluke, further studies are required on the identification. Acute fascioliasis of sheep occurred in the Altiplano Region principally during a period from May to July, or the dry season. In some areas, the mortality rate of infected sheep was roughly estimated as 15 to 25% annually. Contamination with Fasciola metacercariae of herbage and semi-aquatic plants grown in a swamp in one of these areas was biologically assessed, using guinea pigs. Plants of Compositae and Eleocharis sp. were contaminated most intensely and those of Senicio sp. and Vallisneria sp. carried a fairly large number of cysts, while plants of Scirpus sp. and Ranunclaceae carried only a few cysts. No signs of Fasciola infection were observed in any animal given the plants of Liliaceae. PMID:1182037

Ueno, H; Arandia, R; Morales, G; Medina, G



The Biological Control of the Snail Hosts of Schistosomes: The Role of Competitor Snails and Biological Invasions  

Microsoft Academic Search

\\u000a Biological control of the snail hosts of schistosomes has been ­considered in the last few decades as an alternative to molluscicides.\\u000a Several groups of organisms have been proposed to control snail hosts, but very few have proven their efficacy in the field.\\u000a Competitor snails can be considered as the most efficient biological control agents and numerous promising laboratory studies\\u000a and

Jean-Pierre Pointier; Patrice David; Philippe Jarne


Crayfish predation on the common pond snail (Lymnaea stagnalis): the effect of habitat complexity and snail size on foraging efficiency  

Microsoft Academic Search

Optimal foraging theory was used to explain selective foraging by the introduced signal crayfish (Pacifastacus leniusculus)\\u000a on the thin-shelled common pond snail (Lymnaea stagnalis). Crayfish predation efficiency was studied in relation to habitat\\u000a complexity and snail size. In a pool experiment (area 1.3 m2) single adult crayfish were allowed to feed on four size classes of snails for one week.

Per Nyström; Jose R. Pérez



Variation of snail's abundance in two water bodies harboring strains of Pseudosuccinea columella resistant and susceptible to Fasciola hepatica miracidial infection, in Pinar del Río Province, Cuba.  


The abundance of freshwater snails in two rural sites of Pinar del Río, Cuba, which harbor Pseudosuccinea columella susceptible and resistant to miracidia of Fasciola hepatica was followed for one year. Susceptible snails were found in the most anthropic site (IPA) whereas the resistant population inhabited the most preserved one (El Azufre). Only two snail species coexisted with P. columella at IPA site (Physa cubensis and Tarebia granifera) while five species were found at El Azufre, including an endemic from that province (Hemisinus cubanianus). Populations of both resistant and susceptible snails showed stable densities throughout the year, although the susceptible strain attained higher abundance. The highest densities were observed in April-May 2004 for the susceptible population whereas the resistant strain attained its highest abundance in January 2004. No record of Fossaria cubensis was made and the thiarid T. granifera occurred only at low densities. One of the sampled sites (IPA) meets all the conditions for the first report of P. columella naturally infected with larvae of F. hepatica. PMID:16410958

Gutiérrez, Alfredo; Hernandez, Dagmar F; Sánchez, Jorge



Acute toxic effects of two lampricides on twenty-one freshwater invertebrates  

USGS Publications Warehouse

We conducted laboratory static bioassays to determine acute toxicity of two lampricides -- a 70% 2-aminoethanol salt of 5,2'dichloro-4'-nitrosalicylanilide (Bayer 73) and a mixture containing 98% 3-trifluoromethyl-4-nitrophenol (TFM) and 2% Bayer 73 (TFM-2B) -- to 21 freshwater invertebrates. LC50 values were determined for 24-h exposure periods at 12.8 C. Organisms relatively sensitive to Bayer 73 were a turbellarian (Dugesia tigrina), aquatic earthworms (Tubifex tubifex and Lumbriculus inconstans), snails (Physa sp.) and (Pleurocera sp.), a clam (Eliptio dilatatus), blackflies (Simulium sp.), leeches (Erpobdellidae), and a daphnid (Daphnia pulex). The invertebrates most sensitive to TFM-2B were turbellarians, aquatic earthworms (Tubifex), snails (Physa), blackflies, leeches, and burrowing mayflies (Hexagenia sp.). Bayer 73 was generally much more toxic to the test organisms than TFM-2B. At lampricidal concentrations, TFM-2B was more highly selective than Bayer 73 against larval sea lampreys (Petromyzon marinus).

Rye, Robert P., Jr.; King, Everett Louis, Jr.



Nimbus (BgI): an active non-LTR retrotransposon of the Schistosoma mansoni snail host Biomphalaria glabrata.  


The freshwater snail Biomphalaria glabrata is closely associated with the transmission of human schistosomiasis. An ecologically sound method has been proposed to control schistosomiasis using genetically modified snails to displace endemic, susceptible ones. To assess the viability of this form of biological control, studies towards understanding the molecular makeup of the snail relative to the presence of endogenous mobile genetic elements are being undertaken since they can be exploited for genetic transformation studies. We previously cloned a 1.95kb BamHI fragment in B. glabrata (BGR2) with sequence similarity to the human long interspersed nuclear element (LINE or L1). A contiguous, full-length sequence corresponding to BGR2, hereafter-named nimbus (BgI), has been identified from a B. glabrata bacterial artificial chromosome (BAC) library. Sequence analysis of the 65,764bp BAC insert contained one full-length, complete nimbus (BgI) element (element I), two full-length elements (elements II and III) containing deletions and flanked by target site duplications and 10 truncated copies. The intact nimbus (BgI) contained two open-reading frames (ORFs 1 and 2) encoding the characteristic hallmark domains found in non-long terminal repeat retrotransposons belonging to the I-clade; a nucleic acid binding protein in ORF1 and an apurinic/apyrimidinic endonuclease, reverse transcriptase and RNase H in ORF2. Phylogenetic analysis revealed that nimbus (BgI) is closely related to Drosophila (I factor), mosquito Aedes aegypti (MosquI) and chordate ascidian Ciona intestinalis (CiI) retrotransposons. Nimbus (BgI) represents the first complete mobile element characterised from a mollusk that appears to be transcriptionally active and is widely distributed in snails of the neotropics and the Old World. PMID:17521654

Raghavan, Nithya; Tettelin, Hervé; Miller, André; Hostetler, Jessica; Tallon, Luke; Knight, Matty



Sudden death in supravalvular aortic stenosis: fusion of a coronary leaflet to the sinus ridge, dysplasia and stenosis of aortic and pulmonic valves.  


Supravalvular aortic stenosis (SVAS) is an uncommon congenital cardiac anomaly. We report sudden death, occurring during exercise, of a child who had SVAS with fusion of the right coronary aortic leaflet to the supravalvular aortic ridge, resulting in a closed sinus of Valsalva except for a few pinpoint fenestrations in the dysplastic leaflet. In addition, both aortic and pulmonic valves were dysplastic and stenotic. We postulate that near total isolation of the right coronary artery ostium from the aortic lumen compromised the blood supply to the hypertrophied ventricles. We emphasize the importance of other cardiac anomalies associated with SVAS as well as the development of coronary insufficiency. PMID:1437889

Sun, C C; Jacot, J; Brenner, J I



Biomes: Freshwater and Seawater  

NSDL National Science Digital Library

This lesson plan is part of the lesson plan library for grades 6-8. Students conduct research by sampling organisms in a nearby freshwater habitat to determine how an organism's behavior and adaptation relate to its habitat, and how freshwater habitats have different characteristics depending on whether water is still or moving. Included are objectives, materials, procedures, discussion questions, evaluation ideas, suggested readings, and vocabulary. There are videos available to order which complement this lesson, an audio-enhanced vocabulary list, and links to teaching tools for making custom quizzes, worksheets, puzzles and lesson plans.


Freshwater and Marine Image Bank  

NSDL National Science Digital Library

The Freshwater and Marine Image Bank is an ongoing digital collection of images related to freshwater and marine topics, in all their diversity. It includes images of fish, shellfish, and marine mammals, pictures of fish hatcheries and dams and vessels, materials related to polar exploration, regional and traditional fisheries, and limnological (freshwater) subjects. Its scope is global.

Washington, University O.



Effects of Molluscicidal Constituents in Spices on Reproduction in Snails  

Microsoft Academic Search

Sublethal treatment (20% and 60% of 24 hr LC50) of young snails (Lymnaea acuminata) with the active molluscicidal constituents ferulic acid and umbelliferone from Ferula asafoetida, eugenol from Syzygium aromaticum, and limonene from Carum carvi caused a significant reduction in the fecundity, hatchability, and survival of the snails. Treatment with the constituents also increased the length of time to hatching

Pradeep Kumar; Vinay K. Singh; Chandra P. M. Tripathi; Dinesh K. Singh



Outgrowths from Pieces of Helix aspersa, the Common Snail  

Microsoft Academic Search

IN connexion with a cytological problem now being investigated, an attempt has been made to culture snail tissue. It is well known that snails are able to repair extensive injuries under what must be extremely septic conditions. The epithelium beneath the shell and elsewhere is not keratinised or otherwise protected, except perhaps for its faculty to produce mucus. It follows

J. Brontë Gatenby



Phenotypic Plasticity of the Introduced New Zealand Mud Snail, Potamopyrgus antipodarum, Compared to Sympatric Native Snails  

PubMed Central

Phenotypic plasticity is likely to be important in determining the invasive potential of a species, especially if invasive species show greater plasticity or tolerance compared to sympatric native species. Here in two separate experiments we compare reaction norms in response to two environmental variables of two clones of the New Zealand mud snail, Potamopyrgus antipodarum, isolated from the United States, (one invasive and one not yet invasive) with those of two species of native snails that are sympatric with the invader, Fossaria bulimoides group and Physella gyrina group. We placed juvenile snails in environments with high and low conductivity (300 and 800 mS) in one experiment, and raised them at two different temperatures (16°C and 22°C) in a second experiment. Growth rate and mortality were measured over the course of 8 weeks. Mortality rates were higher in the native snails compared to P. antipodarum across all treatments, and variation in conductivity influenced mortality. In both experiments, reaction norms did not vary significantly between species. There was little evidence that the success of the introduced species is a result of greater phenotypic plasticity to these variables compared to the sympatric native species.

Levri, Edward P.; Krist, Amy C.; Bilka, Rachel; Dybdahl, Mark F.



The introduction of Melanoides tuberculata (Mollusca: Thiaridae) to the island of Saint Lucia (West Indies) and its role in the decline of Biomphalaria glabrata, the snail intermediate host of Schistosoma mansoni.  


A malacological survey was carried out in May 1992 in the whole hydrographic system of Saint Lucia 11 years after the end of a biological control programme to eliminate Biomphalaria glabrata, the snail intermediate host of Schistosoma mansoni. A competitor snail, Melanoides tuberculata, was introduced to Saint Lucia in 1978 and field experiments in several habitats were conducted by Prentice between 1978 and 1986. At the present time M. tuberculata is the most common freshwater snail in Saint Lucia. The results of the survey, undertaken in sites where B. glabrata occurred in large populations in the past showed (i) the absence of the snail hosts from seven sites now extensively colonized by the competitor (ii) the presence of B. glabrata in low or very low densities in 17 sites together with the competitor and (iii) the presence of the intermediate hosts in large populations in only two sites where M. tuberculata was absent. These results confirm the positive results observed by Prentice. The presence of another planorbid snail, B. straminea, is reported for the first time in Saint Lucia. PMID:8103624

Pointier, J P



Black Rat ( Rattus rattus ) Predation on Nonindigenous Snails in Hawai‘i: Complex Management Implications 1  

Microsoft Academic Search

Understanding interactions among nonindigenous species that pose a threat to native species is crucial to effectively preserve native biodiversity. Cap- tive feeding trials demonstrated that the black rat, Rattus rattus, will readily con- sume two of the most destructive nonindigenous snails, the giant African snail, Achatina fulica (100% predation), and the predatory snail Euglandina rosea (80% predation). Rats consumed snails

Wallace M. Meyer; Aaron B. Shiels



Loons in freshwater lakes  

Microsoft Academic Search

Loons (Gaviidae) divide their annual cycle between salt and freshwater habitat, the latter being the site of breeding activites. Territorial requirements include sufficient size to permit runs of more than 100 m for take-off and landings; food for chicks and water clarity sufficient to permit foraging for it at depths generally = 5 m; protected nest sites, preferably islands; and

Judith W. McIntyre



Freshwater Marsh. Habitat Pac.  

ERIC Educational Resources Information Center

The materials in this educational packet are designed for use with students in grades 4 through 7. They consist of an overview, three lesson plans and student data sheets, and a poster. The overview describes how the freshwater marsh is an important natural resource for plant, animal, and human populations and how the destruction of marshes causes…

Fish and Wildlife Service (Dept. of Interior), Washington, DC.


Relationship between Snail Population Density and Infection Status of Snails and Fish with Zoonotic Trematodes in Vietnamese Carp Nurseries  

PubMed Central

Background Fish-borne zoonotic trematodes (FZT) are a food safety and health concern in Vietnam. Humans and other final hosts acquire these parasites from eating raw or under-cooked fish with FZT metacercariae. Fish raised in ponds are exposed to cercariae shed by snail hosts that are common in fish farm ponds. Previous risk assessment on FZT transmission in the Red River Delta of Vietnam identified carp nursery ponds as major sites of transmission. In this study, we analyzed the association between snail population density and heterophyid trematode infection in snails with the rate of FZT transmission to juvenile fish raised in carp nurseries. Methodology/Principal Findings Snail population density and prevalence of trematode (Heterophyidae) infections were determined in 48 carp nurseries producing Rohu juveniles, (Labeo rohita) in the Red River Delta area. Fish samples were examined at 3, 6 and 9 weeks after the juvenile fish were introduced into the ponds. There was a significant positive correlation between prevalence of FZT metacercariae in juvenile fish and density of infected snails. Thus, the odds of infection in juvenile fish were 4.36 and 11.32 times higher for ponds with medium and high density of snails, respectively, compared to ponds where no infected snails were found. Further, the intensity of fish FZT infections increased with the density of infected snails. Interestingly, however, some ponds with no or few infected snails were collected also had high prevalence and intensity of FZT in juvenile fish. This may be due to immigration of cercariae into the pond from external water sources. Conclusions/Significance The total number and density of potential host snails and density of host snails infected with heterophyid trematodes in the aquaculture pond is a useful predictor for infections in juvenile fish, although infection levels in juvenile fish can occur despite low density or absence infected snails. This suggests that intervention programs to control FZT infection of fish should include not only intra-pond snail control, but also include water sources of allochthonous cercariae, i.e. canals supplying water to ponds as well as snail habitats outside the pond such as rice fields and surrounding ponds.

Clausen, Jesper Hedegaard; Madsen, Henry; Murrell, K. Darwin; Phan Thi, Van; Nguyen Manh, Hung; Viet, Khue Nguyen; Dalsgaard, Anders



Potential impacts of the invasive flatworm Platydemus manokwari on arboreal snails  

Microsoft Academic Search

The introduction of the snail-eating flatworm Platydemus manokwari (Tricladida: Rhynchodemidae) has been considered a cause of the extinction of native land snails on several Pacific islands.\\u000a Although P. manokwari is known to attack land snails on the ground, whether P. manokwari attacks snails on trees remains unclear. To clarify the effect of P. manokwari on arboreal snails, we examined survival rates of land

Shinji Sugiura; Yuichi Yamaura



Potential impacts of the invasive flatworm Platydemus manokwari on arboreal snails  

Microsoft Academic Search

\\u000a The introduction of the snail-eating flatworm Platydemus manokwari (Tricladida: Rhyn-chodemidae) has been considered a cause of the extinction of native land snails on several Pacific islands.\\u000a Although P. manokwari is known to attack land snails on the ground, whether P. manokwari attacks snails on trees remains unclear. To clarify the effect of P. manokwari on arboreal snails, we examined survival

Shinji Sugiura; Yuichi Yamaura


Acquisition of Ca 2+ and HCO 3 ? \\/CO 3 2? for shell formation in embryos of the common pond snail Lymnaea stagnalis  

Microsoft Academic Search

Embryos of the freshwater common pond snail Lymnaea stagnalis develop to hatch within 10 days under control conditions (22°C, Miami-Dade tap water) and this development is impaired by\\u000a removal of ambient calcium. In contrast, embryos did not exhibit dependence upon an ambient HCO3\\u000a ?\\/CO3\\u000a 2? source, developing and hatching in HCO3\\u000a ?\\/CO3\\u000a 2?-free water at rates comparable to controls. Post-metamorphic, shell-laying

Sue C. Ebanks; Michael J. O’Donnell; Martin Grosell



[Study on morphological and functional characterization of hemocytes in snails].  


Snails are the intermediate host of Schistosoma and they play an important role in the transmission of schistosomiasis. The snails in different areas present various susceptibilities, which are related to the different hemocytes in the snails. There is not a common standard in the classification of hemocytes, and generally the hemocytes are divided into two categories: a granulocyte and a hyalinocyte. The granulocyte plays an important role in immunization, while hyalinocyte shows a less effect. Besides, soluble factors may also play a role in immunization. PMID:24490414

Zheng, Sheng-Bang; Zhou, Yi-Biao; Jiang, Qing-Wu



The Role of Snail in EMT and Tumorigenesis  

PubMed Central

Epithelial-mesenchymal transition (EMT) is a highly conserved process in which polarized, immotile epithelial cells lose adherent and tight junctions, and become migratory mesenchymal cells. As a key transcriptional repressor of E-cadherin expression in EMT, Snail plays an important role in embryonic development and cancer progression. Emerging evidences indicate that Snail confers tumor cells with cancer stem cell-like traits, and promotes drug resistance, tumor recurrence and metastasis. In this review, we summarize recent developments underlying the regulation and functions of Snail in tumor progression, and discuss new approaches against EMT in preventing metastatic cancers.

Chai, Kequn; Ying, Xuhua; Zhou, Binhua P.



Seasonal changes in cryoprotectants concentrations in Helix pomatia snails.  


Terrestrial snails are often exposed to freezing. Therefore, we investigated seasonal shifts in hemolymph concentrations of cryoprotectants such as glycerol and glucose. We also investigated whether summer acclimation to cold and short-day photoperiod induced synthesis of cryoprotectants in Helix pomatia snails. Concentrations of the both cryoprotectants were elevated in winter and reduced in summer. These changes, however, were not correlated with shifts in liver glycogen content. Summer acclimation to cold (5 degrees C) and short-day photoperiod evoked a selective increase in glycerol concentration. In conclusion, glycerol may play a role in adaptation of the snails to winter cold and glucose is rather unlikely to provide the cryoprotection. PMID:17242476

Nowakowska, A; Caputa, M; Rogalska, J



Comparison of extraction methods for the determination of atrazine accumulation in freshwater molluscs ( Physa acuta Drap. and Ancylus fluviatilis Müll, Gastropoda)  

Microsoft Academic Search

Three simple extraction methods were evaluated for the measurement of atrazine in the tissues of two species of freshwater snail. One-way analysis of variance (ANOVA) showed that the highest significant concentrations were measured following extraction by manual trituration and sonication, with methanol as solvent. Accumulation of atrazine was measured for 20 days of toxicant exposure. Physa acuta had 11.74±0.12 mg kg?1

I Muñoz; N Rosés



Causes of Late Pleistocene water level change in Lake Victoria, Equatorial East Africa, derived from clumped isotopes of land snails and fresh water mollusks. (Invited)  

NASA Astrophysics Data System (ADS)

Carbonate clumped isotope thermometry is based on the dependence of 13C-18O bond abundance in the carbonate lattice (measured as ?47) on the carbonate formation temperature. Most marine and freshwater biogenic carbonates are found to be in agreement with the clumped isotopes - temperature calibration. Clumped isotope thermometry is particularly useful in terrestrial environments where the interpretation of carbonate ?18O is limited due to difficulty in estimating the paleo-water isotopic composition. Clumped isotope-derived temperatures from land snails are generally higher than the ambient environmental temperatures, but show no evidence for disequilibrium. We attribute these higher body temperatures to snail eco-physiological adaptations through shell color, morphology, and behavior. We use the clumped isotope-derived temperatures in combination with shell ?18O to calculate snail body water ?18O composition. This parameter is interpreted as a paleo-hydrological indicator that reflects the isotopic composition of local precipitation modified by local evaporation. Rusinga and Mfangano Islands in Lake Victoria provide a unique opportunity to compare extant species of modern and fossil freshwater mollusks and land snails from the same location to examine lake paleo-hydrology. This location is particularly interesting as Lake Victoria itself is the main source of rain-water in the region such that the isotopic composition of land snail body water can be related back to the source waters. We combine clumped isotope and oxygen isotope measurements of both freshwater mollusks and land snails to examine the water balance of the lake, testing hypotheses about the mechanism of a significant rise in lake level in Lake Victoria ~35 - 40 ka BP. Outcrops of paleo-beach deposits ~18 m above the modern day lake level indicate high water stands at ~35-40 ka BP. Based on water balance models for Lake Victoria, an increase in lake level of this magnitude could be driven by local mean annual precipitation that is significantly greater than modern. However, this is inconsistent with regional climate reconstructions. This suggests that either lake level was controlled by non-climatic factors, or that local climate in the Lake Victoria basin was different than regional patterns of climate across eastern Africa. We use oxygen and clumped isotopes of modern and fossil shells (Corbicula sp., Melanoides sp. and Bellamya unicolor) from this 18 m beach outcrop on Mfangano Island to (1) compare with modern lake water ?18O values and (2) calculate paleo-water compositions. We combine these results with calculated snail body water ?18O composition (using oxygen and clumped isotopes) of land snails (Limicoloria cf. martensiana) from Rusinga and Mfangano Islands, to study hydrological changes of Lake Victoria. We use these data to evaluate the relative importance of climate change and tectonics as mechanisms for the Late Pleistocene expansion of Lake Victoria.

Zaarur, S.; Affek, H. P.; Tryon, C.; Peppe, D. J.; Faith, J.



Taxonomy: A Precursor to Understanding Ecological Interactions among Schistosomes, Snail Hosts, and Snail-Eating Fishes  

Microsoft Academic Search

We have observed a dramatic decrease in the abundance of snail-eating fishes and an increase in the prevalence of schistosomiasis among village residents and expatriate tourists at Lake Malawi, Africa, over the past two decades. We hypothesized that these observations were linked by a cause-and-effect relationship and that the observed decrease in fish molluscivores permitted an increase in the abundance

Jay Richard Stauffer Jr; Henry Madsen; Adrianus Konings; Paul Bloch; Cecilia Paola Ferreri; Jeremy Likongwe; Kenneth R. McKaye; Kristin E. Black



No effect of mate novelty on sexual motivation in the freshwater snail Biomphalaria glabrata  

Microsoft Academic Search

BACKGROUND: When mating effort (e.g. via ejaculates) is high, males are expected to strategically allocate their resources depending on the expected fitness gains from a given mating opportunity. One mechanism to achieve strategic mating is the Coolidge effect, where male sexual motivation declines across repeated encounters with a familiar partner, but resuscitates when encountering a novel female. Experimental tests of

Ines K Häderer; Johanna Werminghausen; Nico K Michiels; Nadine Timmermeyer; Nils Anthes



Relative size influences gender role in the freshwater hermaphroditic snail, Helisoma trivolvis  

Microsoft Academic Search

Simultaneous hermaphrodites have the unique challenge of allocating their available resources to egg and sperm production and behaviorally to a male and\\/or female mating role. Models that address the influence of body size on sex allocation predict that larger individuals should allocate proportionally more resources to female than male function and that this should translate into corresponding behavioral preferences during

Cynthia G. Norton; Angela F. Johnson; Rebecca L. Mueller



Toxic effect of two common Euphorbiales latices on the freshwater snail Lymnaea acuminata  

Microsoft Academic Search

The aqueous and serially purified latex extracts of plants Euphorbia pulcherima and Euphorbia hirta (family Euphorbiaceae) have potent molluscicidal activity. Sub-lethal doses (40 and 80% of LC50) of aqueous and partially purified latex extracts of both the plants also significantly alter the levels of total protein, total free amino acid, nucleic acid (DNA and RNA) and the activity of enzyme

Sunil Kumar Singh; R. P Yadav; Digvijay Singh; Ajay Singh



Freshwater snails of East Caprivi and the lower Okavango River Basin in Namibia and Botswana  

Microsoft Academic Search

A systematic account is given of the aquatic gastropod fauna of the lower Okavango River in Namibia and Botswana, and of the East Caprivi area in Namibia, based on collections made mostly in 1983–86 from about 100 different sites. A total of 20 living species are reported, 9 of them for the first time from this area: Bellamya monardi, Lobogenes

D. S. Brown; B. A. Curtis; S. Bethune; C. C. Appleton



Energy saving through trail following in a marine snail  

PubMed Central

Most snails and slugs locomote over a layer of mucus and although the resultant mucus trail is expensive to produce, we show that this expense can be reduced by trail following. When tracking over fresh conspecific trails, the marine intertidal snail Littorina littorea (L.) produced only approximately 27% of the mucus laid by marker snails. When tracking over weathered trails, snails adjusted their mucus production to recreate a convex trail profile of similar shape and thickness to the trail as originally laid. Maximum energy saving occurs when following recently laid trails which are little weathered. Many and diverse ecological roles for trail following have been proposed. Energy saving is the only role that applies across the Gastropoda and so may help to explain why trail following is such a well-established behaviour.

Davies, Mark S; Blackwell, Janine



Astronomers Follow Distant Galaxy at a Snail's Pace  

NSF Publications Database

... Astronomers Follow Distant Galaxy at a Snail's Pace M33 tracked across the sky, rather than toward ... s press release. -NSF- Media Contacts Dave Finley, NRAO (505) 835-7302 M. Mitchell ...


Effects of pollution on freshwater organisms  

SciTech Connect

This review includes subjects in last year's reviews on effects of pollution on freshwater invertebrates and effects of pollution on freshwater fish and amphibians. This review also includes information on the effects of pollution on freshwater plants. 625 references.

Phipps, G.L.; Harden, M.J.; Leonard, E.N.; Roush, T.H; Spehar, D.L.; Stephan, C.E.; Pickering, Q.H.; Buikema, A.L. Jr.



Transfer RNA editing in land snail mitochondria.  


Some mitochondrial tRNA genes of land snails show mismatches in the acceptor stems predicted from their gene sequences. The majority of these mismatches fall in regions where the tRNA genes overlap with adjacent downstream genes. We have synthesized cDNA from four circularized tRNAs and determined the sequences of the 5' and 3' parts of their acceptor stems. Three of the four tRNAs differ from their corresponding genes at a total of 13 positions, which all fall in the 3' part of the acceptor stems as well as the discriminator bases. The editing events detected involve changes from cytidine, thymidine, and guanosine to adenosine residues, which generally restore base-pairing in the stems. However, in one case an A-A mismatch is created from an A-C mismatch. It is suggested that this form of RNA editing may involve polyadenylylation of the maturing tRNAs as an intermediate. PMID:7479799

Yokobori, S; Pääbo, S



Respiration rates and population metabolism of woodland snails  

Microsoft Academic Search

Experiments were done to measure the respiration rates of twenty species of terrestrial snail. Acclimatization phenomena were sought in two species, Discus rotundatus and Hygromia striolata, but not detected. The Q10s between 5 and 15° C for the twenty species varied between 1.20 and 4.27, with a mean Q10 of 2.21. Q10 was higher in larger snail species. There was

C. F. Mason; Botanic Gardens



Global ocean freshwater transport pathways  

NASA Astrophysics Data System (ADS)

Variations in the atmospheric hydrological cycle are most easily observed through ocean salinity changes, and therefore it is useful to understand the basic ocean circulations responsible for maintaining the mean ocean salinity distribution. Ocean freshwater transports are calculated here from geostrophic and Ekman velocities and salinities. The net transports are assigned quantitatively to upper ocean gyre circulations, intermediate and deep overturning, and Bering Strait/Indonesian Throughflow. Excess freshwater input into the ocean in high latitudes must be transported via ocean circulation to the evaporative lower latitudes. High latitude northern hemisphere freshwater input of about 0.6 Sv is removed southwards through deep and intermediate water formation (NADW and NPIW). In complete contrast, high latitude southern hemisphere freshwater, also about 0.6 Sv, is removed northwards via the Atlantic, Pacific and Indian gyres, rather than through deep water formation. This northern-southern hemisphere asymmetry is consistent with the known "Drake Passage" effect. Excess evaporation in the Atlantic and Indian Oceans is balanced by inflow of freshwater from other regions; each transfer is quantified here. The Pacific Ocean is nearly neutral with respect to freshwater. It is seen that the NADW freshwater balance is nearly closed within the Atlantic/Arctic Ocean and the freshwater transport associated with export of NADW to the Southern Ocean is only a small component of the Atlantic freshwater budget. Bering Strait's small freshwater transport of < 0.1 Sv helps to maintain the Atlantic-Pacific salinity difference. However, proportionally large variations in the small Bering Strait transport can only marginally impact NADW salinity, whose freshening relative to saline surface water is mainly due to air-sea/runoff fluxes in the subpolar North Atlantic and Arctic. In contrast, Bering Strait freshwater export has proportionally much greater impact on North Pacific salinity balances, including NPIW salinity, because the Pacific has a much smaller overturning rate than the Atlantic.

Talley, L.



Transboundary Freshwater Dispute Database  

NSDL National Science Digital Library

The database includes 150 water related treaties and 39 US compacts. The International Treaties and Compacts section is searchable by nation, basin, issues, conflict resolution mechanisms, non-water linkages, and date. US Compacts are searchable by state, basin, focus and date. For all treaties or compacts there is a summary of the agreement, the parties involved, allocations if applicable and other information pertinent to a specific agreement. There is also information available on indigenous approaches to water conflict resolution, a digitized inventory of the world's river basins with data about those basins, and a bibliography featuring publications about transboundary freshwater dispute resolution.


Rapid spread of an invasive snail in South America: the giant African snail, Achatina fulica , in Brasil  

Microsoft Academic Search

Beginning around 1800, but primarily since the early and mid-twentieth century, the giant African snail, Achatina (Lissachatina) fulica Bowdich, 1822, has been introduced throughout the tropics and subtropics and has been considered the most important snail\\u000a pest in these regions. In Brasil, specimens probably brought from Indonesia were introduced into the state of Paran? in the\\u000a 1980s for commercial purposes

Silvana C. Thiengo; Fábio André Faraco; Norma C. Salgado; Robert H. Cowie; Monica A. Fernandez



United Nations Environment Programme: Freshwater  

NSDL National Science Digital Library

This portal provides access to information on equitable and sustainable management of freshwater resources around the world. Topics include water scarcity, irrigated agriculture, water and sanitation, water quality, groundwater, transboundary water management, water and ecosystems, floods and droughts, and urban water. There are also case studies, global assessments of freshwater resources, policy documents, and information on conferences and other events.


A conserved role for Snail as a potentiator of active transcription  

PubMed Central

The transcription factors of the Snail family are key regulators of epithelial–mesenchymal transitions, cell morphogenesis, and tumor metastasis. Since its discovery in Drosophila ?25 years ago, Snail has been extensively studied for its role as a transcriptional repressor. Here we demonstrate that Drosophila Snail can positively modulate transcriptional activation. By combining information on in vivo occupancy with expression profiling of hand-selected, staged snail mutant embryos, we identified 106 genes that are potentially directly regulated by Snail during mesoderm development. In addition to the expected Snail-repressed genes, almost 50% of Snail targets showed an unanticipated activation. The majority of “Snail-activated” genes have enhancer elements cobound by Twist and are expressed in the mesoderm at the stages of Snail occupancy. Snail can potentiate Twist-mediated enhancer activation in vitro and is essential for enhancer activity in vivo. Using a machine learning approach, we show that differentially enriched motifs are sufficient to predict Snail's regulatory response. In silico mutagenesis revealed a likely causative motif, which we demonstrate is essential for enhancer activation. Taken together, these data indicate that Snail can potentiate enhancer activation by collaborating with different activators, providing a new mechanism by which Snail regulates development.

Rembold, Martina; Ciglar, Lucia; Yanez-Cuna, J. Omar; Zinzen, Robert P.; Girardot, Charles; Jain, Ankit; Welte, Michael A.; Stark, Alexander; Leptin, Maria; Furlong, Eileen E.M.



Effects of Dietary Exposure to Forest Pesticides on the Brown Garden Snail 'Helix aspersa' Mueller.  

National Technical Information Service (NTIS)

Brown garden snails, Helix aspersa, were fed prepared diets with 12 pesticides used in forest spraying practices where endangered arboreal and terrestrial snails may be at risk. Acephate, atrazine, glyphosate, hexazinone, and picloram were not lethal at c...

G. S. Schuytema A. V. Nebeker W. L. Griffis



MTA3 regulates CGB5 and Snail genes in trophoblast.  


Secreted by the placental trophoblast, human chorionic gonadotropin (hCG) is an important hormone during pregnancy and is required for the maintenance of pregnancy. Previous studies have shown that dys-regulation of hCG expression is associated with preeclampsia. However, the exact relationship between altered hCG levels and development of preeclampsia is unknown. Metastasis associated protein 3 (MTA3), a chromatin remodeling protein, is abundantly expressed in the placental trophoblasts, but its function is unknown. In breast cancer, MTA3 has been shown to repress the expression of Snail and cell migration. However, whether MTA3 acts similarly in the trophoblast has not been investigated. In the present study, we examined the role of MTA3 in regulating the hCG ?-subunit gene (gene name: CGB5) and Snail expression in the trophoblast cell line, BeWo, as well as its relevance to the high hCG expression levels seen in preeclampsia. First, we investigated MTA3 expression in preeclamptic placenta as compared to normal control placenta via gene expression microarray and qRT-PCR and found that MTA3 was significantly down-regulated, whereas both CGB5 and Snail were up-regulated in preeclamptic placenta. Secondly, we knocked down MTA3 gene in trophoblast cell line BeWo and found Snail and hCG were both up-regulated, suggesting that MTA3 represses Snail and hCG gene expression in trophoblasts. Next, we cloned the CGB5 and Snail promoters into the pGL3-basic vector individually and found that silencing of MTA3 by siRNA resulted in an increase of both CGB5 and Snail promoter activities. To confirm that this MTA3 inhibition is a direct effect, we performed a chromatin immune-precipitation (ChIP) assay and found that MTA3 occupied the proximal promoter regions of both Snail and hCG within BeWo cells. Furthermore, we examined MTA3 expression in placental trophoblast by immunohistochemistry and found that MTA3 expression was higher in villous cytotrophoblasts versus syncytiotrophoblasts, which supports an inverse association of MTA3 with hCG expression. Lastly, using the well-characterized trophoblast fusion model, we examined MTA3 and hCG levels in forskolin-treated BeWo cells and found that MTA3 down-regulation was accompanied by an up-regulation of hCG. These data further suggest that MTA3 is repressing placental hCG expression. In summary, MTA3 plays a critical role in repressing hCG and Snail in placenta trophoblast and its deregulation is associated with preeclampsia. PMID:23510993

Chen, Ying; Miyazaki, Jun; Nishizawa, Haruki; Kurahashi, Hiroki; Leach, Richard; Wang, Kai



Antioxidants and oxidative stress in Helix pomatia snails during estivation.  


Estivation enables land snails to survive a prolonged dryness but the return to active state imposes conditions of oxidative stress on internal organs due to a transient large increase in oxygen consumption, which augments mitochondrial production of reactive oxygen species. Therefore, activities of antioxidant enzymes, concentrations of reduced glutathione (GSH) and TBARS as an index of lipid peroxidation, were evaluated in Helix pomatia snails (i) during summer activity, (ii) during estivation, which was induced experimentally, (iii) at the start of arousal from estivation, and (iv) being aroused for 24 h. Estivation induced significant decreases in activity of catalase in the kidney and hepatopancreas and glutathione peroxidase in the kidney. Activity of glutathione reductase was unaffected by estivation/arousal cycle. Summer-active and estivating snails maintained high activity of glutathione transferase. Concentration of GSH was organ-dependent and was positively affected by estivation. Lack of increase in TBARS concentration during estivation/arousal cycle suggests that antioxidant defence system of H. pomatia snails is highly efficacious. In conclusion, permanent maintenance of relatively high activities of the antioxidant enzymes and the high concentration of GSH in H. pomatia snails indicate that they have well-developed strategy of defence against oxidative injury. PMID:19632354

Nowakowska, Anna; Swiderska-Ko?acz, Grazyna; Rogalska, Justyna; Caputa, Micha?



The Decline of Freshwater Ecosystems  

NSDL National Science Digital Library

This article discusses the risks that freshwater ecosystems face and how species nearby are affected by dams, dredging, and channelization of streams. It points out that even though freshwater ecosystems are limited in extent, covering about 1 percent of the Earth's surface, they are highly diverse and contain a disproportionally large number of the world's species. Statistics are given to illustrate the increase in waterways that have been altered for navigation. Some actions that are being taken to reduce threats to freshwater ecosystems are also mentioned.



Flux balance models for the oxygen and carbon isotope compositions of land snail shells  

Microsoft Academic Search

A simple flux balance model with a diffusive, evaporative boundary layer indicates that the time constant (characteristic time) for approach to oxygen isotope steady state in the body fluid of land snails is ?19 min or less. These comparatively short times support an assumption that the snail’s aragonitic shell is commonly precipitated from a body fluid that is at, or

Meena Balakrishnan; Crayton J. Yapp



Water vapour sorption by the pedal mucus trail of a land snail  

Microsoft Academic Search

The hydrophilicity of pedal mucus trails deposited by snails influences the settlement of marine organisms and can potentially influence the trailing and homing mechanisms of terrestrial snails. The composition of pedal mucus deposited as a trail on a solid substrate by the giant African land snail (Achatina marginata) has been probed non-invasively using infrared ellipsometry. The primary chemical groups in

B. J. Lincoln; T. R. E. Simpson; J. L. Keddie



New scope on the relationship between rotifers and Biomphalaria alexandrina snails  

PubMed Central

Objective To investigate the effect of rotifer internalization into snail tissue on the development of schistosomes. Methods Susceptible laboratory-bred Biomphalaria alexandrina (B. alexandrina) snails were exposed to lab-maintained rotifers; Philodina spp., two weeks before and after being infected with Schistosoma mansoni (S. mansoni) miracidia. The consequent histopathological impact on snail tissues and cercarial biology were investigated before and after emergence from snails. Results Contamination of B. alexandrina snails with philodina, two weeks before miracidial exposure, was found to hinder the preliminary development of S. mansoni cercariae inside the snail tissues. Furthermore, when snails were contaminated with rotifers two weeks post miracidial exposure; growth of already established cercariae was found to be retarded. The consequent influence of internalized rotifers within the snail tissue was clearly reflected on cercarial emergence, activity and infectivity along the four weeks duration of shedding. In the present study, comparison of snail histopathological findings and altered cercarial biology observed between the experimental and control groups indicated that the rotifers may have affected the levels of snail's energy reservoirs, which eventually was found to have had an adverse impact on reproduction, growth and survival of the parasite within the snail host, coupled with its performance outside the snail. Conclusions In future biological control strategies of schistosomiasis, ritifers should be considered as a parasitic scourge of humanity.

Mossallam, Shereen Farouk; Amer, Eglal Ibrahim; Abou-El-Naga, Iman Fathy



Helix and Drugs: Snails for Western Health Care From Antiquity to the Present  

PubMed Central

The land helix, or snail, has been used in medicine since antiquity and prepared according to several formulations. This historical report traces the understanding of their properties from the time of Hippocrates, who proposed the use of snail mucus against protoccle and Pliny who thought that the snail increased the speed of delivery and was “a sovereign remedy to treat pain related to burns, abscesses and other wounds”, Galien recommended snails against hydrops foetails. In the 18th century, various snail “preparations” were also recommended for external use with dermatological disorders and internally for symptoms associated with tuberculosis and nephritis. Surprisingly, the 19th century saw a renewed interest in the pharmaceutical and medical use of snails with numerous indications for snail preparations. This interest in snails did not stop at the end of the 19th century. The 1945 edition of Dorvault devotes an entire paragraph to snails, indicating that the therapeutic usage of snails was still alive at that time. Recently the FDA has also shown an interest in snails. Ziconotide (SNXIII), a synthetic peptide coming from snail venom, has been under FDA review since 1999. Pre-clinical and clinical studies of this new drug are promising.



Lats2 kinase potentiates Snail1 activity by promoting nuclear retention upon phosphorylation.  


Snail1 is a central regulator of epithelial cell adhesion and movement in epithelial-to-mesenchymal transitions (EMTs) during embryo development; a process reactivated during cancer metastasis. While induction of Snail1 transcription precedes EMT induction, post-translational regulation of Snail1 is also critical for determining Snail1's protein level, subcellular localization, and capacity to induce EMT. To identify novel post-translational regulators of Snail1, we developed a live cell, bioluminescence-based screen. From a human kinome RNAi screen, we have identified Lats2 kinase as a novel regulator of Snail1 protein level, subcellular localization, and thus, activity. We show that Lats2 interacts with Snail1 and directly phosphorylates Snail1 at residue T203. This occurs in the nucleus and serves to retain Snail1 in the nucleus thereby enhancing its stability. Lats2 was found to positively influence cellular EMT and tumour cell invasion, in a Snail1-dependent manner. Indeed during TGF?-induced EMT Lats2 is activated and Snail1 phosphorylated at T203. Analysis in mouse and zebrafish embryo development confirms that Lats2 acts as a positive modulator of Snail1 protein level and potentiates its in vivo EMT activity. PMID:21952048

Zhang, Kun; Rodriguez-Aznar, Eva; Yabuta, Norikazu; Owen, Robert J; Mingot, Jose M; Nojima, Hiroshi; Nieto, M Angela; Longmore, Gregory D



Bioaccumulation and distribution of /sup 95m/Tc in an experimental freshwater pond  

SciTech Connect

An acute release of /sup 95m/Tc was made to a small experimental freshwater pond to determine the behavior of technetium in a freshwater ecosystem. The objectives of the study were (1) to determine the distribution of /sup 95m/Tc in the components of the ecosystem and (2) to determine the concentration in freshwater biota. Prior to the release of /sup 95m/Tc, the pond was stocked with aquatic macrophytes, fish, and invertebrates. All components of the pond were sampled for a period of 37 d. Analyses of filtered and unfiltered water samples showed that /sup 95m/Tc did not sorb significantly to particulates suspended in the water but remained dissolved. Sediments accumulated /sup 95m/Tc slowly as the experiment progressed. In the biota, periphyton accumulated /sup 95m/Tc rapidly, reaching the highest concentration (3482 dpm/g dry wt) 4 h after the release and maintaining a relatively high concentration throughout the experiment. Fish and invertebrates accumulated /sup 95m/Tc gradually. Elimination studies and tissue analyses showed that a large percentage of the body burden was in the digestive system of all fish, suggesting that fish were accumulating /sup 95m/Tc through the food chain. Biological half-lives determined from elimination studies for carp (Cyprinus carpio), mosquitofish (Gambusia affinis), and snails (Helisoma sp.) were 2.5, 4.3, and 21.3 d, respectively. Calculated concentration factors for the same species were 11 for carp, 75 for mosquito fish, and 121 for snails. The estimated size of the biomass components in the ecosystem in descending order were: periphyton, macrophytes, invertebrates, fish, and algae. Based on biomass estimates and concentrations of the /sup 95m/Tc in the aquatic biota, approximately 1% of the /sup 95m/Tc accumulated in the biota.

Blaylock, B.G.; Frank, M.L.



Building a better snail: Lubrication and adhesive locomotion  

NASA Astrophysics Data System (ADS)

Many gastropods, such as slugs and snails, crawl via an unusual mechanism known as adhesive locomotion. We investigate this method of propulsion using two mathematical models: one for direct waves and one for retrograde waves. We then test the effectiveness of both proposed mechanisms by constructing two mechanical crawlers. Each crawler uses a different mechanical strategy to move on a thin layer of viscous fluid. The first uses a flexible flapping sheet to generate lubrication pressures in a Newtonian fluid, which in turn propel the mechanical snail. The second generates a wave of compression on a layer of Laponite, a non-Newtonian, finite-yield stress fluid with characteristics similar to those of snail mucus. This second design can climb smooth vertical walls and perform an inverted traverse.

Chan, Brian; Balmforth, N. J.; Hosoi, A. E.



MTA3 regulates CGB5 and Snail genes in trophoblast  

SciTech Connect

Highlights: •Impaired MTA3, raised CGB5 and Snail expression are associated with preeclampsia. •Knock-down of MTA3 causes up-regulation of CGB5 and Snail genes in BeWo cells. •MTA3 occupies CGB5 and Snail gene promoters in BeWo cells. -- Abstract: Secreted by the placental trophoblast, human chorionic gonadotropin (hCG) is an important hormone during pregnancy and is required for the maintenance of pregnancy. Previous studies have shown that dys-regulation of hCG expression is associated with preeclampsia. However, the exact relationship between altered hCG levels and development of preeclampsia is unknown. Metastasis associated protein 3 (MTA3), a chromatin remodeling protein, is abundantly expressed in the placental trophoblasts, but its function is unknown. In breast cancer, MTA3 has been shown to repress the expression of Snail and cell migration. However, whether MTA3 acts similarly in the trophoblast has not been investigated. In the present study, we examined the role of MTA3 in regulating the hCG ?-subunit gene (gene name: CGB5) and Snail expression in the trophoblast cell line, BeWo, as well as its relevance to the high hCG expression levels seen in preeclampsia. First, we investigated MTA3 expression in preeclamptic placenta as compared to normal control placenta via gene expression microarray and qRT-PCR and found that MTA3 was significantly down-regulated, whereas both CGB5 and Snail were up-regulated in preeclamptic placenta. Secondly, we knocked down MTA3 gene in trophoblast cell line BeWo and found Snail and hCG were both up-regulated, suggesting that MTA3 represses Snail and hCG gene expression in trophoblasts. Next, we cloned the CGB5 and Snail promoters into the pGL3-basic vector individually and found that silencing of MTA3 by siRNA resulted in an increase of both CGB5 and Snail promoter activities. To confirm that this MTA3 inhibition is a direct effect, we performed a chromatin immune-precipitation (ChIP) assay and found that MTA3 occupied the proximal promoter regions of both Snail and hCG within BeWo cells. Furthermore, we examined MTA3 expression in placental trophoblast by immunohistochemistry and found that MTA3 expression was higher in villous cytotrophoblasts versus syncytiotrophoblasts, which supports an inverse association of MTA3 with hCG expression. Lastly, using the well-characterized trophoblast fusion model, we examined MTA3 and hCG levels in forskolin-treated BeWo cells and found that MTA3 down-regulation was accompanied by an up-regulation of hCG. These data further suggest that MTA3 is repressing placental hCG expression. In summary, MTA3 plays a critical role in repressing hCG and Snail in placenta trophoblast and its deregulation is associated with preeclampsia.

Chen, Ying [Department of Obstetrics, Gynecology and Reproductive Biology, Michigan State University, Grand Rapids, MI 49503 (United States)] [Department of Obstetrics, Gynecology and Reproductive Biology, Michigan State University, Grand Rapids, MI 49503 (United States); Miyazaki, Jun [Department of Obstetrics and Gynecology, Fujita Health University School of Medicine, Fujita Health University, Toyoake (Japan) [Department of Obstetrics and Gynecology, Fujita Health University School of Medicine, Fujita Health University, Toyoake (Japan); Division of Molecular Genetics, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake (Japan); Nishizawa, Haruki [Department of Obstetrics and Gynecology, Fujita Health University School of Medicine, Fujita Health University, Toyoake (Japan)] [Department of Obstetrics and Gynecology, Fujita Health University School of Medicine, Fujita Health University, Toyoake (Japan); Kurahashi, Hiroki [Division of Molecular Genetics, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake (Japan)] [Division of Molecular Genetics, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake (Japan); Leach, Richard, E-mail: [Department of Obstetrics, Gynecology and Reproductive Biology, Michigan State University, Grand Rapids, MI 49503 (United States) [Department of Obstetrics, Gynecology and Reproductive Biology, Michigan State University, Grand Rapids, MI 49503 (United States); Department of Obstetrics, Gynecology and Women’s Health, Spectrum Health Medical Group, Grand Rapids, MI 49503 (United States); Wang, Kai, E-mail: [Department of Obstetrics, Gynecology and Reproductive Biology, Michigan State University, Grand Rapids, MI 49503 (United States)] [Department of Obstetrics, Gynecology and Reproductive Biology, Michigan State University, Grand Rapids, MI 49503 (United States)



The relationship between genetic variability and the susceptibility of Biomphalaria alexandrina snails to Schistosoma mansoni infection.  


In the present study, Biomphalaria snails collected from five Egyptian governorates (Giza, Fayoum, Kafr El-Sheikh, Ismailia and Damietta), as well as reference control Biomphalaria alexandrina snails from the Schistosome Biological Supply Center (SBSC) (Theodor Bilharz Research Institute, Egypt), were subjected to species-specific polymerase chain reaction (PCR) assays to identify the collected species. All of the collected snails were found to be B. alexandrina and there was no evidence of the presence of Biomphalaria glabrata. Randomly amplified polymorphic DNA (RAPD)-PCR assays showed different fingerprints with varying numbers of bands for the first generation (F?) of B. alexandrina snail populations (SBSC, Giza, Fayoum, Kafr El-Sheikh, Ismailia and Damietta). The primer OPA-1 produced the highest level of polymorphism and amplified the greatest number of specific bands. The estimated similarity coefficients among the B. alexandrina populations based on the RAPD-PCR profiles ranged from 0.56 (between SBSC and Ismailia snails) to 0.72 (between Ismailia and Kafr El-Sheikh snails). Experimental infection of the F? of progeny from the collected snails with Schistosoma mansoni (SBSC strain) showed variable susceptibility rates ranging from 15% in the Fayoum snail group to 50.3% in SBSC snails. A negative correlation was observed between the infection rates in the different snail groups and the distances separating their corresponding governorates from the parasite source. The infection rates of the snail groups and their similarity coefficients with SBSC B. alexandrina snails were positively correlated. The variations in the rates of infection of different B. alexandrina groups with S. mansoni, as well as the differences in the similarity coefficients among these snails, are dependent not only on the geographical distribution of the snails and the parasite, but also on the genetic variability of the snails. Introduction of this variability into endemic areas may reduce the ability of the parasite to infect local hosts and consequently reduce schistosomiasis epidemiology. PMID:22510827

Mohamed, Azza H; El-Din, Ahmed T Sharaf; Mohamed, Ahmed M; Habib, Mohamed R



Seasonal fluctuation of invasive flatworm predation pressure on land snails: Implications for the range expansion and impacts of invasive species  

Microsoft Academic Search

Introduction of the snail-eating flatworm Platydemus manokwari has caused extinction and decline of native land snails on tropical and subtropical islands. As the factors influencing flatworm predation pressure on land snails remain unclear, I examined the effects of seasonal variation in flatworm predation pressure on land snail survival in the wild on a subtropical island. I also examined the feeding

Shinji Sugiura



Euparyphium albuferensis and Echinostoma friedi (Trematoda: Echinostomatidae): experimental cercarial transmission success in sympatric snail communities.  


Euparyphium albuferensis and Echinostoma friedi cercarial infectivity to four species of sympatric snails was examined under single- or multiple-choice laboratory conditions to show the level of parasite-snail host compatibility. Radix peregra, Lymnaeafuscus, Physella acuta and Gyraulus chinensis act as second intermediate hosts of both parasite species although different cercarial transmission success (CTS) was observed. In single-host experiments, R. peregra and P. acuta showed a high degree of compatibility with E. albuferensis, while only P. acuta in the case of E. friedi. In two-choice snail communities, a snail with high CTS increased the values of another with low compatibility, in both parasite species. In multiple-choice snail communities, high CTS of some hosts decreased, while low CTS of other hosts increased. The degree of parasite-host compatibility of each snail species could be determined by the presence of other snails in the community. PMID:18666415

Muñoz-Antoli, Carla; Marin, Antoni; Vidal, Amparo; Toledo, Rafael; Esteban, José Guillermo



Snail as a potential target molecule in cardiac fibrosis: paracrine action of endothelial cells on fibroblasts through snail and CTGF axis.  


Ischemia/reperfusion (I/R) injury to myocardium induces death of cardiomyocytes and destroys the vasculature, leading to cardiac fibrosis that is mainly mediated by the transdifferentiation of fibroblasts to myofibroblasts and the collagen deposition. Snail involvement in fibrosis is well known; however, the contribution of Snail to cardiac fibrosis during I/R injury and its underlying mechanisms have not been defined. We showed that I/R injury to mouse hearts significantly increases the expression of Snail. An in vitro hypoxia/reoxygenation (Hy/Reoxy) experiment showed that the cell source of Snail induction is endothelial cells rather than cardiac fibroblasts (cFibroblasts) or cardiomyoblasts. When Snail was overexpressed in endothelial cells, they underwent endothelial-to-mesenchymal transition (EndMT) but showed very poor capacity for collagen synthesis. Instead, reoxygenation- or Snail overexpression-mediated EndMT-like cells noticeably stimulated transdifferentiation of fibroblasts to myofibroblasts via secretion of connective tissue growth factor (CTGF). The injection of a peroxisome proliferator-activated receptor-? (PPAR-?) agonist, a selective Snail inhibitor, remarkably suppressed collagen deposition and cardiac fibrosis in mouse I/R injury, and significantly improved cardiac function and reduced Snail and CTGF expression in vivo. Our findings suggested a new mechanism of cell-to-cell communication between EndMT-like cells and fibroblasts for fibrosis induction and implicated Snail as a potential target molecule in cardiac fibrosis after I/R injury. PMID:23760445

Lee, Sae-Won; Won, Joo-Yun; Kim, Woo Jean; Lee, Jaewon; Kim, Kyung-Hee; Youn, Seock-Won; Kim, Ju-Young; Lee, Eun Ju; Kim, Yong-Jin; Kim, Kyu-Won; Kim, Hyo-Soo



40 CFR 35.1605-3 - Publicly owned freshwater lake.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Publicly owned freshwater lake. 35.1605-3 Section 35.1605-3...Protecting and Restoring Publicly Owned Freshwater Lakes § 35.1605-3 Publicly owned freshwater lake. A freshwater lake that offers public...



Demography of the Snail Kite in Blue Cypress Marsh Complex.  

National Technical Information Service (NTIS)

This report presents data on the snail kites that use the Blue Cypress Marsh Complex (BCMC). This report will concentrate on demographic data collected in 2005, but will also synthesize data collected since 2001 in BCMC. The number of birds observed on ea...

A. Bowling C. Cattau D. Huser J. Martin M. Conners W. Kitchens



Peptide Neurotoxins from Fish-Hunting Cone Snails  

Microsoft Academic Search

To paralyze their more agile prey, the venomous fish-hunting cone snails (Conus) have developed a potent biochemical strategy. They produce several classes of toxic peptides (contoxins) that attack a series of successive physiological targets in the neuromuscular system of the fish. The peptides include presynaptic omega -conotoxins that prevent the voltage-activated entry of calcium into the nerve terminal and release

Baldomero M. Olivera; William R. Gray; Regina Zeikus; J. Michael McIntosh; Janos Varga; Jean Rivier; Victoria de Santos; Lourdes J. Cruz



Sperm allocation in the simultaneously hermaphroditic land snail Arianta arbustorum  

Microsoft Academic Search

To test the idea that individuals of the simultaneously hermaphroditic land snailArianta arbustorumcan control the number of spermatozoa in their spermatophores, we investigated whether they differentially release sperm to virgin or nonvirgin partners with respect to the potential risk of sperm competition in a given mating. The number of sperm transferred ranged from 802620 to 3968800 (X= 2185100;N=91), but was




Food induced esterase phenocopies in the snail Cepaea nemoralis  

Microsoft Academic Search

Hepatopancreatic extracts from the snail Cepaea nemoralis, assayed straight from the field, often contain three or four heavily staining esterase zones which migrate to the cathodal end of polyacrylamide disc gels during electrophoresis Previous breeding results showed that the heavily straining zones appeared allelic but to incorporate these multibanded phenotypes, a super gene of five closely linked loci was tentatively

G S Oxford



Systematic review of the land snails of the Pitcairn Islands  

Microsoft Academic Search

The land snails (and semi-terrestrial molluscs) of the four islands that comprise the Pitcairn group are reviewed and the indigenous species illustrated. The strictly terrestrial molluscan faunas from the two atolls (Oeno and Ducie) are poor, like many other atolls in the Pacific. Each supports less than six species with wide geographical ranges. In contrast, the terrestrial molluscan fauna from




Snail-Induced Sulfonation Pathway in Breast Cancer Metastasis.  

National Technical Information Service (NTIS)

This projects seeks to establish a key role for cellular sulfonation enzymes in the metastatic progression of breast cancer. To this end we have accomplished the following tasks in this first year of support: 1. Creation Tetracycline inducible WT Snail an...

I. F. Rauscher



Snail Shells in a Practical Application of Statistical Procedures  

ERIC Educational Resources Information Center

This paper is based upon a laboratory exercise designed for biology students in secondary schools or those taking introductory biology laboratory courses in colleges and universities. This exercise requires a set of calipers, a calculator and populations of snail shells collected either from the wild or obtained from a biological supply house. The…

Banks, Stephen W.; Shepherd, Deborah K.; Williams-Hart, Tara; Gossett, Dalton R.; Crnkovic, Amanda C.



Antioxidants and oxidative stress in Helix pomatia snails during estivation  

Microsoft Academic Search

Estivation enables land snails to survive a prolonged dryness but the return to active state imposes conditions of oxidative stress on internal organs due to a transient large increase in oxygen consumption, which augments mitochondrial production of reactive oxygen species. Therefore, activities of antioxidant enzymes, concentrations of reduced glutathione (GSH) and TBARS as an index of lipid peroxidation, were evaluated

Anna Nowakowska; Gra?yna ?widerska-Ko?acz; Justyna Rogalska; Micha? Caputa



Food Choice in the Common Snail (Helix Aspersa).  

ERIC Educational Resources Information Center

The easily obtained common snail shows interesting dietary preferences which can be the source of several simple experiments. Specific student instructions are given for quantitative and comparative studies using cabbage, lettuce, carrot, rutabaga, and onion. Suggestions for laboratory setup and further work are included. (DH)

Gill, John; Howell, Pauline



Flying shells: historical dispersal of marine snails across Central America.  


The geological rise of the Central American Isthmus separated the Pacific and the Atlantic oceans about 3 Ma, creating a formidable barrier to dispersal for marine species. However, similar to Simpson's proposal that terrestrial species can 'win sweepstakes routes'-whereby highly improbable dispersal events result in colonization across geographical barriers-marine species may also breach land barriers given enough time. To test this hypothesis, we asked whether intertidal marine snails have crossed Central America to successfully establish in new ocean basins. We used a mitochondrial DNA genetic comparison of sister snails (Cerithideopsis spp.) separated by the rise of the Isthmus. Genetic variation in these snails revealed evidence of at least two successful dispersal events between the Pacific and the Atlantic after the final closure of the Isthmus. A combination of ancestral area analyses and molecular dating techniques indicated that dispersal from the Pacific to the Atlantic occurred about 750 000 years ago and that dispersal in the opposite direction occurred about 72 000 years ago. The geographical distribution of haplotypes and published field evidence further suggest that migratory shorebirds transported the snails across Central America at the Isthmus of Tehuantepec in southern Mexico. Migratory birds could disperse other intertidal invertebrates this way, suggesting the Central American Isthmus may not be as impassable for marine species as previously assumed. PMID:21920976

Miura, Osamu; Torchin, Mark E; Bermingham, Eldredge; Jacobs, David K; Hechinger, Ryan F



Effects of 17?-ethynylestradiol, fluoxetine, and the mixture on life history traits and population growth rates in a freshwater gastropod.  


Pharmaceutical and personal care products (PPCPs), some of which have endocrine-disrupting effects at environmentally relevant concentrations, have been detected in many surface waters. The authors evaluated the effects of 2 common endocrine disrupting PPCPs on the life history traits of the snail, Physa pomilia, using a life table response experiment with snails raised in environmentally relevant concentrations of 17?-ethynylestradiol (EE2), fluoxetine, or their mixture. Exposure to fluoxetine or the mixture reduced snail reproduction, but EE2 did not. Generally, individual life history traits were affected minimally by the PPCPs, but when integrated using a demographic model, all 3 chemical exposure scenarios decreased population growth rates, with the EE2 and fluoxetine mixture causing the most adverse effects. Overall, the results provide additional insight into the effects of PPCPs on freshwater invertebrates and point to the importance of testing simultaneous exposures to multiple PPCPs. In addition, using a demographic model to integrate individual endpoints provided insights into effects that were not apparent from individual life history traits alone and suggest at least a potential for adverse ecological effects under realistic environmental exposures concentrations. PMID:23983099

Luna, Tamara O; Plautz, Stephanie C; Salice, Christopher J



Tissue responses exhibited by Biomphalaria alexandrina snails from different Egyptian localities following Schistosoma mansoni exposure.  


Snails' susceptibilities to infection with Schistosoma mansoni were determined through observation of infection rates, total cercarial production and tissue responses of the first generation (F1) of Biomphalaria alexandrina snails, originally collected from different Egyptian governorates (Giza, Fayoum, Kafr El-Sheikh, Ismailia and Damietta) and responses were compared between groups. The emergence of cercariae for a 3-month period and the calculation of survival and infection rates, in control (Schistosome Biological Supply Center; SBSC) and infected snails were evaluated. SBSC and Giza snails showed greater susceptibilities to infection and lower mortality rates. In addition, at 6 and 72 h post-exposure to miracidia all the snail groups showed no difference in the anatomical locations of sporocysts. The larvae were found in the head-foot, the mantle collar and the tentacles of the snails. Sporocysts showed normal development with low tissue reactions in SBSC and Giza snail groups infected with S. mansoni miracidia (SBSC). However, in Fayoum, Kafr El-Sheikh, Ismailia and Damietta snail groups, variable tissue responses were observed in which numerous hemocytes made direct contact with S. mansoni larvae forming capsules. The results suggested that, different responses of B. alexandrina snail's hemocytes towards S. mansoni are related to the degree of susceptibility of these snails. So this is important in planning the strategy of schistosomiasis control. PMID:21295031

Mohamed, Azza H; Sharaf El-Din, Ahmed T; Mohamed, Ahmed M; Habib, Mohamed R



Testosterone, gonadotropins and androgen receptor during spermatogenesis of Biomphalaria alexandrina snails (Pulmonata: Basommatophora).  


Endocrine regulation of reproductive processes of the snail Biomphalaria alexandrina is poorly recognized. Thus, the aims of the study were: (1) to acquire histological images of the ovotestis; (2) to determine the hemolymph concentrations of testosterone (T) and gonadotropic hormones (luteinizing hormone: LH and follicle stimulating hormone: FSH), (3) to demonstrate androgen receptor (AR) immunolocalization in the ovotestis, and (4) to show LH and FSH protein expression in cerebral ganglia of small (diameter shell: 4-6mm), medium (7-11mm) and large (12-16mm) B. alexandrina snails. These three groups represented different reproductive stages of the snail. The AR immunoexpression was found in the periphery and inside the acini of small (immature) snails as well as in spermatocytes, spermatids, Sertoli cells, the interstitial cells and the acinus lining epithelium of medium (mature) snails. Low AR immunoexpression was demonstrated in the interstitial cells of large (aged) snails. The neurons at the periphery of the cerebral ganglia and connective sheath of the ganglia showed a positive FSH and LH immunostaining. T concentration in the hemolymph was higher in medium snails than in small and large snails. In contrast, LH concentration was higher in medium snails than in small and large snails. These data suggests that gonadotropins and T play a role in the gonadal development in B. alexandrina. PMID:23153701

Omran, Nahla El-Sayed El-Shazly



Targeted Inactivation of Snail Family EMT Regulatory Factors by a Co(III)-Ebox Conjugate  

PubMed Central

Snail family proteins are core EMT (epithelial-mesenchymal transition) regulatory factors that play essential roles in both development and disease processes and have been associated with metastasis in carcinomas. Snail factors are required for the formation of neural crest stem cells in most vertebrate embryos, as well as for the migratory invasive behavior of these cells. Snail factors have recently been linked to the formation of cancer stem cells, and expression of Snail proteins may be associated with tumor recurrence and resistance to chemotherapy and radiotherapy. We report that Co(III)-Ebox is a potent inhibitor of Snail- mediated transcriptional repression in breast cancer cells and in the neural crest of Xenopus. We further show that the activity of Co(III)-Ebox can be modulated by temperature, increasing the utility of this conjugate as a Snail inhibitor in model organisms. We exploit this feature to further delineate the requirements for Snail function during neural crest development, showing that in addition to the roles that Snail factors play in neural crest precursor formation and neural crest EMT/migration, inhibition of Snail function after the onset of neural crest migration leads to a loss of neural crest derived melanocytes. Co(III)-Ebox-mediated inhibition therefore provides a powerful tool for analysing the function of these core EMT factors with unparalleled temporal resolution. Moreover, the potency of Co(III)-Ebox as a Snail inhibitor in breast cancer cells suggests its potential as a therapeutic inhibitor of tumor progression and metastasis.

Harney, Allison S.; Meade, Thomas J.; LaBonne, Carole



The human Lgl polarity gene, Hugl-2, induces MET and suppresses Snail tumorigenesis.  


Lethal giant larvae proteins have key roles in regulating polarity in a variety of cell types and function as tumour suppressors. A transcriptional programme initiated by aberrant Snail expression transforms epithelial cells to potentially aggressive cancer cells. Although progress in defining the molecular determinants of this programme has been made, we have little knowledge as to how the Snail-induced phenotype can be suppressed. In our studies we identified the human lethal giant larvae homologue 2, Hugl-2, (Llgl2/Lgl2) polarity gene as downregulated by Snail. Snail binds E-boxes in the Hugl-2 promoter and represses Hugl-2 expression, whereas removal of the E-boxes releases Hugl-2 from Snail repression. We demonstrate that inducing Hugl-2 in cells with constitutive Snail expression reverses the phenotype including changes in morphology, motility, tumour growth and dissemination in vivo, and expression of epithelial markers. Hugl-2 expression reduced the nuclear localization of Snail and thus binding of Snail to its target promoters. Our results placing Hugl-2 within the Snail network as well as its ability to suppress Snail carcinogenesis identifies Hugl-2 as a target molecule driving cascades, which may have preventative and therapeutic promise to minimize cancer progression. PMID:22580609

Kashyap, A; Zimmerman, T; Ergül, N; Bosserhoff, A; Hartman, U; Alla, V; Bataille, F; Galle, P R; Strand, S; Strand, D



Snail2 controls mesodermal BMP/Wnt induction of neural crest  

PubMed Central

The neural crest is an induced tissue that is unique to vertebrates. In the clawed frog Xenopus laevis, neural crest induction depends on signals secreted from the prospective dorsolateral mesodermal zone during gastrulation. The transcription factors Snail2 (Slug), Snail1 and Twist1 are expressed in this region. It is known that Snail2 and Twist1 are required for both mesoderm formation and neural crest induction. Using targeted blastomere injection, morpholino-based loss of function and explant studies, we show that: (1) Snail1 is also required for mesoderm and neural crest formation; (2) loss of snail1, snail2 or twist1 function in the C2/C3 lineage of 32-cell embryos blocks mesoderm formation, but neural crest is lost only in the case of snail2 loss of function; (3) snail2 mutant loss of neural crest involves mesoderm-derived secreted factors and can be rescued synergistically by bmp4 and wnt8 RNAs; and (4) loss of snail2 activity leads to changes in the RNA levels of a number of BMP and Wnt agonists and antagonists. Taken together, these results identify Snail2 as a key regulator of the signals involved in mesodermal induction of neural crest.

Shi, Jianli; Severson, Courtney; Yang, Jianxia; Wedlich, Doris; Klymkowsky, Michael W.



Effect of three dormant oils on schistosomiasis and fascioliasis vector snails and its relation with some non-target snails.  


Three oils were tested for their molluscicidal activity, Caple-2, Kemasol and Super-max. Super-max had the strongest toxic effect on B. alexandrina and other snail species. Its LC50 was 0.53 ppm, meanwhile LC50 of Kemasol 3.2 ppm and 4.21 ppm for Caple 2. The LC50 & LC90 of the oils were lower in Lymneae natalensis as compared to B. alexandrina. The LC50 & LC90 of the oils against non-target snails (Physa acuta, Helisoma duryi, Planorbis planorbis and Melanoides tuberculata) were higher as compared to B. alexandrina. Hatchability of snails' eggs exposed to Super-max (3.0 & 5.0 ppm) was stopped completely and l.0 ppm showed the lower percent of egg hatchability 22.7 %. Caple 2 and Kemasol did not affect eggs hatchability. Supermax had the strongest harmful effect on both miracidia and cercariae of S. mansoni. 100% mortality values were obtained for both larval stages after 8 & 9 minutes respectively when maintained at LC50. 100% mortality of miracidia occurred after 35 & 155 minutes when maintained at LC50 of Kemasol & Caple 2 respectively. The infection rate of B. alexandrina with S. mansoni miracidia was greatly reduced by the sublethal concentrations of the oils. The reduction of infection rate was higher in snails treated with Supermax (42.9%). A highly significant reduction of total cercarial production per snail was in the experimental groups as compared with controls. The prepatent period of treated snails was prolonged compared to control. Moreover, Total protein content and enzyme activities of snails treated with LC10 of oils showed a significant reduction as compared with control in haemolymyph. There was an increase of protein contents in the tissue. AlkP enzyme activity was slightly increased in haemolymph of experimental groups than controls and was significantly higher in the tissues as compared to control. ALT enzyme activity in haemolymph of experimental groups was higher than control, but lower in tissue. AST enzyme activity was higher in haemolymph and tissue of experimental groups than controls. The SDS-PAGE pattern of tissue soluble proteins extracted from treated B. alexandrina and controls showed different oils effects on the synthesis of protein within snails yielded a complex pattern of polypeptides ranging in molecular weight between 13.775 to 156.7 kDa. Many bands were present in treated snails. At least, one band was detected for snails treated with each of the oils and not in controls. The difference in the similarity indices between treatment and control; for Kemasol was 0.86 & 0.64, for Caple 2 was 0.61 & 0.55 and for Supermax was 0.64 & 0.86. LC25 of Supermax did not cause any mortality to Daphnia after 6 hr. But, LC50 & LC90 caused lower mortality after 6 hr. Kemasol caused 100% mortality after 4 hr at LC50 and 2 hr in LC90. Caple 2 caused 50% mortality of Daphnia after 5 hr at LC25 &100% mortality after 30 minutes in LC50 & LC90. PMID:17153697

Mostafa, Bayaumy B



Freshwater Ecology. LC Science Tracer Bullet.  

ERIC Educational Resources Information Center

Freshwater ecosystems include lakes, ponds, streams, rivers, and certain types of wetlands. This literature and resources guide is not intended to be a comprehensive bibliography on freshwater ecology; the guide is designed--as the name of the series implies--to put the reader or student "on target." Other literature guides related to freshwater

Niskern, Diana, Comp.


Inhabitants of the Fresh-Water Community.  

ERIC Educational Resources Information Center

This learner's guide is designed to assist middle school students in studying freshwater organisms. Following a brief introduction to freshwater ecology, simple line drawings facilitate the identification of plants and animals common to Florida's freshwater ecosystems. Emphasis of the short text which accompanies each illustration is upon the…

Jorgensen, Joseph; Schroeder, Marlene


Icebergs For Use as Freshwater.  

National Technical Information Service (NTIS)

Over three quarters of the Earth's supply of freshwater is locked up in polar ice. Recent estimates have indicated that this water can be made available for use at 20 to 50% of the cost of desalination of seawater. Using ice involves locating and transpor...

R. L. Civiak



Localization and characterization of acharan sulfate in the body of the giant African snail Achatina fulica  

Microsoft Academic Search

Acharan sulfate is a glycosaminoglycan (GAG), having the structure ?4)-2-acetamido-2-deoxy-?-d-glucopyranose(1?4)-2-sulfo-?-l-idopyranosyluronic acid (1?, isolated from the body of the giant African snail Achatina fulica. This GAG represents 3–5% of the dry weight of this snail's soft body tissues. Frozen sections and polyester wax sections of the snail's body were stained by Alcian blue-periodic acid-Schiff's reagent (PAS) to localize acharan sulfate. Alcian

Jia Jeong; Toshihiko Toidab; Yuki Munetab; Ichiro Kosiishi; Toshio Imanari; Robert J. Linhardt; Hyung Seok Choia; Song Ji Wua; Yeong Shik Kim



Creosote compounds in snails obtained from Pensacola Bay, Florida, near an onshore hazardous-waste site  

USGS Publications Warehouse

Snails, Thais haemostoma, were collected from two areas offshore in Pensacola Bay, Florida, near an onshore hazardous-waste site. Tissue from the snails was extracted to isolate the lipophilic compounds and analyzed by gas chromatography/mass spectrometry. Along with naturally occurring compounds, the snail tissue contained large concentrations of polycyclic aromatic compounds, such as phenanthrene, acridine, dibenzothiophene, dibenzofuran, and benzo[a]pyrene. Many of these compounds were characteristic of creosote contamination associated with the onshore hazardous-waste site.

Rostad, C. E.; Pereira, W. E.



Growth and development of the rare land snail Paryphanta busbyi watti (Eupulmonata : Rhytididae)  

Microsoft Academic Search

The rare carnivorous land snail Paryphanta busbyi watti was investigated by following marked snails over a study period of 6.3 years. Large snails were fitted with harmonic radar transponders to aid in locating them. This species is iteroparous and has determinate growth. Shells had maximum diameters of 49.6-61.2 mm. Two to eight large eggs, representing 5%-23% of the live weight

M. J. McLeanB; G. C. ArnoldC; R. MontefioreE


Studies on Lymnaea snails and their trematode parasites in Abis II village, Alexandria.  


Lymnaea snails in Abis II village were studied as regard their species, monthly distribution, density and infection rates in different water bodies. The trematode parasites in L. cailliaudi, the only species of Lymnaea in Abis II village were xiphidio in 40% of snails and Fasciola in 10%. Echinostome cercariae were detected from few snails outside Abis II village. The morphological characters of the different larval stages of the detected parasites were described. PMID:8376865

Salem, A I; Osman, M M; el-Daly, S; Farahat, A



Determination of wing cell fate by the escargot and snail genes in Drosophila.  


Inset appendages such as the wing and the leg are formed in response to inductive signals in the embryonic field. In Drosophila, cells receiving such signals initiate developmental programs which allow them to become imaginal discs. Subsequently, these discs autonomously organize patterns specific for each appendage. We here report that two related transcription factors, Escargot and Snail that are expressed in the embryonic wing disc, function as intrinsic determinants of the wing cell fate. In escargot or snail mutant embryos, wing-specific expression of Snail, Vestigial and beta-galactosidase regulated by escargot enhancer were found as well as in wild-type embryos. However, in escargot snail double mutant embryos, wing development proceeded until stage 13, but the marker expression was not maintained in later stages, and the invagination of the primordium was absent. From such analyses, it was concluded that Escargot and Snail expression in the wing disc are maintained by their auto- and crossactivation. Ubiquitous escargot or snail expression induced from the hsp70 promoter rescued the escargot snail double mutant phenotype with the effects confined to the prospective wing cells. Similar DNA binding specificities of Escargot and Snail suggest that they control the same set of genes required for wing development. We thus propose the following scenario for early wing disc development. Prospective wing cells respond to the induction by turning on escargot and snail transcription, and become competent for regulation by Escargot and Snail. Such cells initiate auto- and crossregulatory circuits of escargot and snail. The sustained Escargot and Snail expression then activates vestigial and other target genes that are essential for wing development. This maintains the commitment to the wing cell fate and induces wing-specific cell shape change. PMID:8620833

Fuse, N; Hirose, S; Hayashi, S



Seasonal modulation of free radical metabolism in estivating land snails Helix aspersa  

Microsoft Academic Search

We investigated the regulation of free radical metabolism in Helix aspersa snails during a cycle of 20-day estivation and 24-h arousal in summer in comparison with estivation\\/arousal in winter-snails. In winter-snails (J. Exp. Biol. 206, 675–685, 2003), we had already observed an increase in the selenium-dependent glutathione-peroxidase (Se-GPX) activity in foot muscle and hepatopancreas and in the contents of hepatopancreas

Gabriella R. Ramos-Vasconcelos; Luciano A. Cardoso; Marcelo Hermes-Lima



Remodeling of phospholipid fatty acids in mitochondrial membranes of estivating snails  

Microsoft Academic Search

The effects of estivation on the phospholipid-specific fatty acid composition of mitochondrial membranes in the hepatopancreas\\u000a of the terrestrial snail Cepaea nemoralis were investigated. The fatty acid composition of all phospholipids was significantly altered in snails estivating for 6 wk,\\u000a indicating that substantial remodeling occurs. The most profound changes occurred in cardiolipin (CL). CL of estivating snails\\u000a was 13-fold more

J. A. Stuart; T. E. Gillis; J. S. Ballantyne



A Population Growth Trend Analysis for Neotricula aperta, the Snail Intermediate Host of Schistosoma mekongi, after Construction of the Pak-Mun Dam  

PubMed Central

Background The Pak-Mun dam is a controversial hydro-power project on the Mun River in Northeast Thailand. The dam is sited in a habitat of the freshwater snail Neotricula aperta, which is the intermediate host for the parasitic blood-fluke Schistosoma mekongi causing Mekong schistosomiasis in humans in Cambodia and Laos. Few data are available which can be used to assess the effects of water resource development on N. aperta. The aim of this study was to obtain data and to analyze the possible impact of the dam on N. aperta population growth. Methodology/Principal Findings Estimated population densities were recorded for an N. aperta population in the Mun River 27 km upstream of Pak-Mun, from 1990 to 2011. The Pak-Mul dam began to operate in 1994. Population growth was modeled using a linear mixed model expression of a modified Gompertz stochastic state-space exponential growth model. The N. aperta population was found to be quite stable, with the estimated growth parameter not significantly different from zero. Nevertheless, some marked changes in snail population density were observed which were coincident with changes in dam operation policy. Conclusions/Significance The study found that there has been no marked increase in N. aperta population growth following operation of the Pak-Mun dam. The analysis did indicate a large and statistically significant increase in population density immediately after the dam came into operation; however, this increase was not persistent. The study has provided the first vital baseline data on N. aperta population behavior near to the Pak-Mun dam and suggests that the operation policy of the dam may have an impact on snail population density. Nevertheless, additional studies are required for other N. aperta populations in the Mun River and for an extended time series, to confirm or refine the findings of this work.

Attwood, Stephen W.; Upatham, E. Suchart



Experimental infections with Fasciola in snails, mice and rabbits.  


Experimental infection trails of Lymnaea (cailliaudi) natalensis snails with miracidia of Fasciola hepatica revealed neither cercariae nor larval stages shed. Infection of white mice with metacercariae from field-collected snails proved to be negative for Fasciola eggs and immature juveniles or adults after 84 days post infection. The infection of eight rabbits (Oryctolagus cuniculus) has succeeded; two rabbits were infected, with a very low infection rate. Faeces of rabbits were negative for eggs. The worm burden was one and three worms from 40 fed metacercariae. The obtained fluke measures 23 mm in length by 4 mm in width. The tegument is covered with sharp-ending spines. The uterus contains few eggs. The intrauterine eggs measured 158 microm x 80 microm. According to the morphological characters of these flukes, they belong to F. gigantica. PMID:18246370

Hussein, Abdel-Nasser A; Khalifa, R M A



Mercury residues in south Florida apple snails (Pomacea paludosa)  

SciTech Connect

Mercury concentrations in the sediments of south Florida wetlands have increased three fold in the last century. Because south Florida is home to many endemic and endangered species, it is important to understand the potential impacts of mercury in this ecosystem`s food web. Recent research by Malley et al. has shown mollusks to be sensitive indicators of methyl mercury which can reflect small differences in background methyl mercury concentrations. In this study, we attempted to determine if the apple snail (Pomacea paludosa) or its eggs are good indicators of bioavailable mercury. Then, using the apple snail as an indicator, we attempted to determine geographic differences in the concentrations of mercury in south Florida. 12 refs., 1 fig., 1 tab.

Eisemann, J.D.; Beyer, W.N.; Morton, A. [National Biological Services, Laurel, MD (United States)] [National Biological Services, Laurel, MD (United States); Bennetts, R.E. [Univ. of Florida, Gainesville, FL (United States)] [Univ. of Florida, Gainesville, FL (United States)



Intertidal snail-trematode communities on the southern Thailand before and after the South Asia tsunami.  


Intertidal snail-trematode communities in southern Thailand were examined before and after the South Asia tsunami. Infection rates and species diversity of cercaria in the host snail Cerithidea in tidal zones did not change significantly from one year before to one month after the tsunami. However, the host snails C. quadrata, C. alata and C. obtusa disappeared from greatly damaged sites. It is important to follow up on the intertidal snail-trematode community recovery process after destruction of the intertidal ecosystem. PMID:17883003

Harada, Masakazu; Sri-aroon, Pusadee; Lohachit, Chantima; Fujimoto, Chigusa; Arif-Ul- Hasan; Itaki, Rodney; Suguri, Setsuo; Chusongsang, Yupa; Chusongsang, Phiraphol



Poly(ADP-ribose)-dependent regulation of Snail1 protein stability.  


Snail1 is a master regulator of the epithelial-mesenchymal transition (EMT) and has been implicated in key tumor biological processes such as invasion and metastasis. It has been previously shown that poly(ADP-ribose) polymerase-1 (PARP-1) knockdown, but not PARP inhibition, downregulates the expression of Snail1. In this study we have characterized a novel regulatory mechanism controlling Snail1 protein expression through poly(ADP-ribosyl)ation. The effect is not only limited to repression of Snail1 transcription but also to downregulated Snail1 protein stability. PARP-1 (but not PARP-2) poly(ADP) ribosylates Snail1, both in vivo and in vitro, and interacts with Snail1, an association that is sensitive to PARP inhibitors. PARP inhibition has also clear effects on EMT phenotype of different tumor cells, including Snail1 downregulation, E-cadherin upregulation, decreased cell elongation and invasiveness. Therefore, this study reveals a new regulatory mechanism of Snail1 activation through poly(ADP-ribosyl)ation with consequences in malignant transformation through EMT. PMID:21577210

Rodríguez, M I; González-Flores, A; Dantzer, F; Collard, J; de Herreros, A G; Oliver, F J




Microsoft Academic Search

An 1 S-year study of reproduction and survival of the Florida Everglade (Snail) Kite (Rostrhamus sociabilis plumbeus) has revealed the following: extremely poor nesting success (only 13.6% of nests found at the nest-building stage successful); extremely long breeding seasons (some reproductive activity in almost all months in good years); frequent multiple brooding and frequent renesting after failure; low egg hatchability



Phenoloxidase activity of Helix aspersa maxima (garden snail, gastropod) hemocyanin.  


The oxygen-transporting protein, hemocyanin (Hc), of the garden snail Helix aspersa maxima (HaH) was isolated and kinetically characterized. Kinetic parameters of the reaction of catalytic oxidation of catechol to quinone, catalyzed by native HaH were determined: the V max value amounted to 22 nmol min(-1) mg(-1), k cat to 1.1 min(-1). Data were compared to those reported for other molluscan Hcs and phenoloxidases (POs). The o-diphenoloxidase activity of the native HaH is about five times higher than the activity determined for the Hcs of the terrestrial snail Helix pomatia and of the marine snail Rapana thomasiana (k cat values of 0.22 and 0.25 min(-1), respectively). The K m values obtained for molluscan Hcs from different species are comparable to those for true POs, but the low catalytic efficiency of Hcs is probably related to inaccessibility of the active sites to potential substrates. Upon treatment of HaH with subtilisin DY, the enzyme activity against substrate catechol was considerably increased. The relatively high proteolytically induced o-diPO activity of HaH allowed using it for preparation of a biosensor for detection of catechol. PMID:24243490

Raynova, Yuliana; Doumanova, Lyuba; Idakieva, Krassimira Nikolova



[Lipids composition and speed of energy metabolism in gastropods].  


Lipid composition of digestive gland and pedal muscle of two northern freshwater pulmonate snails Lymnaea stagnalis and Lymnaea ovata and three marine prosobranch gastropods Littorina obtusata, Littorina littorea, Buccinum undatum from the White Sea was studied. The species differ in ecology, particularly in trophic nabits and motor activity. The content of triacilglycerides both in digestive gland and pedal was higher in littoral dwellers Littorina the activity of which depends on the tide level. The phospholipids content in digestive gland does not differ in quantity in all cases and does not relate to type of feeding or resource quality. In a pedal muscle of marine species the quantity of common phospholipids is higher in comparison with the freshwater ones. The amount of total phospholipids in pedal muscle correlates with mass of metabolic inert formation which constitutes a part of whole mass of snails. The presence of massive shell enhances demands in energy needed for supporting movement and activity. Because the intensity of energy metabolism is related to quantity of total phospholipids, mitochondria and activity of their oxidizing ferments, the presence of thick shell in marine snails together with motor activity costs more in terms of energy than in freshwater snails with thin shell. This hypothesis is supported by the higher specific rate of oxygen consumption in marine snails than in freshwaters. PMID:19140337

Arakelova, E S



Effect of Echinostoma friedi (Trematoda: Echinostomatidae) experimental infection on longevity, growth and fecundity of juvenile Radix peregra (Gastropoda: Lymnaeidae) and Biomphalaria glabrata (Gastropoda: Planorbidae) snails.  


The effect of Echinostoma friedi experimental infection on longevity, growth and fecundity of two susceptible first intermediate host snails, Radix peregra and Biomphalaria glabrata, was studied to contrast the level of compatibility. 120 R. peregra and 150 B. glabrata snails were used exposed to one, three or five miracidia and divided in three categories: INF (snails exposed and infected); ENI (exposed but not infected) and C (control or not miracidial-exposed snails). R. peregra INF snails' death process starts sooner, but in a prolonged extension, while B. glabrata INF snails have a much shorter life span. The infection and the miracidial exposure are able to reduce R. peregra normal development (stunting). B. glabrata INF snails' growth exceeds that of C snails (gigantism). E. friedi produces a total parasitic castration of R. peregra and B. glabrata INF snails. R. peregra would be considered as the required snail host, while B. glabrata only as an adequate snail host. PMID:17805574

Muñoz-Antoli, Carla; Marín, Antoni; Toledo, Rafael; Esteban, José-Guillermo



Defense response of susceptible and resistant Biomphalaria alexandrina snails against Schistosoma mansoni infection.  


In Egypt, Biomphalaria alexandrina is the intermediate host for Schistosoma mansoni. The fates of Schistosoma miracidia in the snails varies between different species of Biomphalaria. The internal defense system is one of the factors that influence the susceptibility pattern of the snails. The interaction between Biomphalaria snails and S. mansoni needs to be identified for each species, and even between the members of the same species with different degrees of susceptibility. In the present study, the first generation of susceptible and resistant parents of B. alexandrina was examined histologically at the 30th day post exposure. The study includes the characterization of the immune response, as expressed by tissue reactions, of susceptible and resistant B. alexandrina snails against S. mansoni. It was also designed to determine the impact of the resistance increase in parent snails, on the mechanisms of interaction of their offspring against infection. The results showed that the infection rate of the offspring from the susceptible parents was 92%. No susceptible offspring was produced from the resistant parents. When the parents were of equal number of susceptible and resistant snails, they gave an offspring with an infection rate of 20%. Susceptible snails that had susceptible parents showed a higher degree of susceptibility than those that had both susceptible and resistant parents. A common feature of the resistant snails was the absence of any viable parasites. The tissue reactions of the resistant snails having only resistant parents occurred at the site of miracidial penetration. In resistant snails for which susceptible ones were included in their parents, the reactions occurred in the deep tissues. These results characterized the immune response of B. alexandrina snails against Schistosoma infection which was found to occur by two different mechanisms. One type of defense occurs in highly resistant snails, and employs direct miracidial destruction soon after parasite penetration. The other type occurs in less resistant snails where a delayed resistance development occurs after the dissemination of the sporocysts in the snail tissues. It seems that B. alexandrina snails respond more or less similar to B. glabrata. The results also proved that the immune response of the internal defense system increased with increasing the number of the inherited resistant genes. PMID:23025090

Abou-El-Naga, Iman F; Radwan, Eman H



Plagiorchis elegans (Trematoda) and incompatible snail hosts: implications for snail life history traits and biocontrol of human schistosomiasis.  


We examined the effect of Plagiorchis elegans on egg production and survival on Bulinus truncatus and Helisoma trivolvis trivolvis. Both species are incompatible hosts for P. elegans. Helisoma t. trivolvis occurs sympatrically with P. elegans; B. truncatus does not. Overall, P. elegans had no effect on survivorship or egg production in H. t. trivolvis or on the survivorship of B. truncatus. Its effect on egg production in B. truncatus was transitory; egg production was reduced by 50% for 5 wk following exposure but returned to normal thereafter. Neither egg production nor survivorship was affected in adult H. t. trivolvis. Egg production ceased at 14 wk post-exposure (PE), but resumed when the snails were paired. Young H. t. trivolvis also produced eggs after exposure, but later than the adults and only after they had been paired with another snail. This suggests that a need for periodic cross-fertilization in H. t. trivolvis rather than the effect of the parasite is responsible for the cessation of egg production in this species. Survivorship in young H. t. trivolvis was significantly higher in exposed snails between wk 7 to 10 PE than in controls. PMID:19566345

Daoust, Simon P; Mader, Brian J; McLaughlin, J Daniel; Rau, Manfred E



Characteristics of snail farming in Edo South Agricultural Zone of Edo State, Nigeria.  


The study was carried out to determine the characteristics of snail farming in Edo South Agricultural Zone of Edo State Nigeria. The interview schedule was used to collect data from 60 snail farmers randomly selected from six cells in the study area. Information on the socioeconomic status of the farmers, production system, management practices and production constraints in the snail farms were elicited. The constraints were determined using a four-point Likert-type scale; a mean score of ? 2.5 was considered as a production constraint. Majority (85.0 %) of the respondents were part-time snail farmers. The major species of snails reared were Achatina achatina and Archachatina marginata, reared by 43.3 and 26.7 % of the farmers, respectively. Semi-intensive system of production was practised by 40.0 % of the farmers. Majority (78.0 %) of the respondents used car tyres to house their snails. About 56 % of the respondents kept their snails for 1-2 years before sale. Up to 51.7 % of the respondents separated their snails into different pens according to their size/age. The most commonly used feeds were vegetables (71.2 %), plant leaves (67.8 %) and kitchen waste (59.3 %). Records of snail production activities were kept by 75.0 % of respondents. The major constraints identified were lack of capital (3.31), inability to get good laying stock (3.00), lack of formulated feed to buy (2.98) and slow growth rate of snails (2.52). The potentials of snail farming in the study area have not been fully exploited as farmers produced at subsistence level. PMID:23011673

Chah, Jane Mbolle; Inegbedion, Grace



Transcription factor snail1 expression and poor survival in pharyngeal squamous cell carcinoma.  


Snail1, a key regulator of epithelial-mesenchymal transition (EMT), plays an important role in tumour progression. Previous studies of snail1 have mainly focused on the epithelial tumour cells. The objective of this study was to evaluate the expression of snail1 protein in endothelial cells, stromal myofibroblasts and malignant epithelial cells of pharyngeal squamous cell carcinomas (PSCC), as well as its relation to clinicopathological features and survival. One hundred and ten tissue microarray samples were analyzed for snail1 expression using immunohistochemistry. In endothelial cells snail1 expression was observed in 51 (48%) of 107 cases and it predicted reduced disease specific survival (DSS) (p=0.009). In 49 (46%) tumour samples snail1 immunostaining was detected in stromal myofibroblasts and there was a tendency to poorer DSS in that group (p=0.067). Snail1 expression in endothelial cells and stromal myofibroblasts is also associated with hypopharyngeal tumours (p=0.01 and p=0.038 respectively), increasing T category (T3-4) (p=0.005, p=0.037 respectively) and poorer general condition of the patient (Karnofsky performance status score <70; p=0.029, p=0.039 respectively). Moreover endothelial expression correlated with advanced stage (III-IV) (p=0.005) and poorer differentiation (grade 2-3; p=0.012). In malignant epithelial cells snail1 immunostaining was detected in 75 of 110 cases (68%). Expression of the protein was more common in hypopharyngeal tumours (p=0.044). Snail1 positive tumours associated with a lower Karnofsky performance status score (p=0.039) and regional failure (p=0.042). Our findings indicate that snail1 protein expression in endothelial cells and to some extent also in tumour stromal myofibroblasts seems to be a predictor of poor survival in PSCC. The presence of snail1 protein in tumour microenvironment rather than in malignant epithelial tumour cells may induce tissue remodelling and tumour progression. PMID:21360437

Jouppila-Mättö, Anna; Tuhkanen, Hanna; Soini, Ylermi; Pukkila, Matti; Närkiö-Mäkelä, Mervi; Sironen, Reijo; Virtanen, Ismo; Mannermaa, Arto; Kosma, Veli-Matti



Characterisation of the human snail ( SNAI1 ) gene and exclusion as a major disease gene in craniosynostosis  

Microsoft Academic Search

The Snail family of proteins in vertebrates comprises two zinc-finger transcription factors, Snail and Slug, which are thought to be involved in the formation of the mesoderm and neural crest. Here, we describe the isolation and characterisation of the human Snail (SNAI1) gene and a related Snail-like pseudogene, SNAI1P. SNAI1 spans approximately 6.4 kb, contains three exons and has a

Stephen R. F. Twigg; Andrew O. M. Wilkie



Changing Arctic Ocean freshwater pathways.  


Freshening in the Canada basin of the Arctic Ocean began in the 1990s and continued to at least the end of 2008. By then, the Arctic Ocean might have gained four times as much fresh water as comprised the Great Salinity Anomaly of the 1970s, raising the spectre of slowing global ocean circulation. Freshening has been attributed to increased sea ice melting and contributions from runoff, but a leading explanation has been a strengthening of the Beaufort High--a characteristic peak in sea level atmospheric pressure--which tends to accelerate an anticyclonic (clockwise) wind pattern causing convergence of fresh surface water. Limited observations have made this explanation difficult to verify, and observations of increasing freshwater content under a weakened Beaufort High suggest that other factors must be affecting freshwater content. Here we use observations to show that during a time of record reductions in ice extent from 2005 to 2008, the dominant freshwater content changes were an increase in the Canada basin balanced by a decrease in the Eurasian basin. Observations are drawn from satellite data (sea surface height and ocean-bottom pressure) and in situ data. The freshwater changes were due to a cyclonic (anticlockwise) shift in the ocean pathway of Eurasian runoff forced by strengthening of the west-to-east Northern Hemisphere atmospheric circulation characterized by an increased Arctic Oscillation index. Our results confirm that runoff is an important influence on the Arctic Ocean and establish that the spatial and temporal manifestations of the runoff pathways are modulated by the Arctic Oscillation, rather than the strength of the wind-driven Beaufort Gyre circulation. PMID:22222749

Morison, James; Kwok, Ron; Peralta-Ferriz, Cecilia; Alkire, Matt; Rigor, Ignatius; Andersen, Roger; Steele, Mike



Inhibition of egg hatching with apple wax solvent as a novel method for controlling golden apple snail ( Pomacea canaliculata)  

Microsoft Academic Search

Golden apple snail (Pomacea canaliculata) is an important pest of rice in Asia. Among chemicals screened for ability to inhibit hatching of snail eggs, morpholine which is a solvent of apple wax was very effective in suppressing hatching of snail eggs. At a concentration of 60%, or higher, morpholine completely suppressed egg hatching in the laboratory and outdoor conditions. Scanning

Der-Chung Wu; Jih-Zu Yu; Bing-Huei Chen; Chien-Yih Lin; Wen-Hsiung Ko



The Application of Electric Shock as a Novel Pest Control Method for Apple Snail, Pomacea canaliculata (Gastropoda: Ampullariidae)  

Microsoft Academic Search

The apple snail, Pomacea canaliculata, brought to Japan from Taiwan for human consumption in the 1980s, has come to be considered as deleterious for rice cultivation. The snail is unable to injure young rice plants while receiving electric shock because the snail retracts its entire body into its shell and shuts its aperture with its operculum. Electric shock should be

Yoshihito Yagyu; Satoshi Tsuji; Saburoh Satoh; Chobei Yamabe



Increased response to cadmium and Bacillus thuringiensis maize toxicity in the snail Helix aspersa infected by the nematode Phasmarhabditis hermaphrodita.  


To determine the effect of nematode infection on the response of snails to selected toxins, we infected Helix aspersa with 0-, 0.25-, 1-, or 4-fold the recommended field dose of a commercial nematode application for agricultural use. In the first experiment, the snails also were exposed to cadmium via food and soil at concentrations of 0, 30, 60, 120, or 240 mg/kg in a full-factorial design. In the second experiment, snails were infected with nematodes and also fed either Bt (expressing Bacillus thuringiensis toxin) maize or non-Bt maize. The snails were weighed at the beginning and end (after four weeks) of the experiments, and mortality was checked daily. Neither exposure of snails to nematodes nor exposure of snails to cadmium or Bt toxin affected the survival rates of snails. The number of dead snails was highest for combinations of nematode treatments with cadmium concentrations of 120 and 240 mg/kg. In both experiments (Bt and cadmium), the growth rate decreased with increasing nematode dose. The Bt maize was not harmful to the snails in the absence of nematodes, but infected snails grew faster when fed non-Bt maize. The growth rate of snails exposed to cadmium decreased with exposure to increasing Cd concentrations and differed significantly between the no-nematode treatment and the treatments with nematode doses of one- and fourfold the recommended field dose. Snails treated with the highest dose of nematodes accumulated the highest cadmium concentrations. PMID:17269462

Kramarz, Paulina E; de Vaufleury, Annette; Zygmunt, Piotr M S; Verdun, Cyrille




Microsoft Academic Search

Some extracts of Euphorbia helioscopia (Euphorbiaceae), Calendula micrantha (Compositae) and Azadriachta indica (Meliaceae) were screened for the control of Culex pipiens larvae, the vector of Filariasis and Biomphalaria alexandrina snails the vector of Schistosomiasis in Egypt. These plants exhibit dual effect on both pests which share the same aquatic breeding habitat and are of medical importance. B. alexandrina snails were



Effect of Infection with Shistosoma mansoni on Some Biological Parameters in Biomphalaria alexandrina Snails  

Microsoft Academic Search

Histological alterations in digestive gland as well as hematological and biochemical changes in haemolymph of Shistosoma mansoni infected Biomphalaria alexandrina snails were studied. The results showed great histological damages in tissues of the digestive gland of infected snails with large numbers of sporocysts and cercariae at several stages of development encircled by cycts in tissue of digestive gland. A detailed

Fayez A. Bakry



Occurrence of a blood group Alike substance in eggs of the prosobranch snail Pomacea canaliculata  

Microsoft Academic Search

Summary In the eggs of the prosobranch snailsPomacea canaliculata andPomacea insularum a blood group A-like substance has been detected by anti-A from the snailsHelix pomatia, Helix aspersa andCepaea nemoralis.

G. Uhlenbruck; G. Steinhausen; D. F. Cheesman; B. Helm



Herbivory on aquatic vascular plants by the introduced golden apple snail ( Pomacea canaliculata ) in Lao PDR  

Microsoft Academic Search

The effect of naturally found densities of the exotic and herbivorous golden apple snail (Pomacea canaliculata) on three dominant aquatic plants – duckweed (Lemna minor), water hyacinth (Eichhornia crassipes) and morning glory (Ipomoea aquatica) – was assessed in a wetland survey and quantified in a field experiment in Laos in southeast Asia. Snail grazing reduced plant biomass, but plant species

Nils O. L. Carlsson; Jean O. Lacoursière



Notch1 increases Snail expression under high reactive oxygen species conditions in hepatocellular carcinoma cells.  


Abstract Notch1 and reactive oxygen species (ROS) modulate important pathways associated with tumor development and progression. Notably, Notch1 expression is upregulated in 41.8% of hepatocellular carcinoma (HCC) patients and ROS levels increases as HCC progresses from Grade I to Grade III. It has been established that Notch1 and ROS modulate Snail expression in malignant tumors; however, the mechanism regulating Snail protein expression is not yet known. In this study, we observed that Notch1 and ROS cooperatively increase the levels of Snail protein in Huh7 (hepatoma) cells. On its own, signaling through Notch1 increases transcription of Snail without changing protein levels. In contrast, the combined activation of the Notch1 and ROS-induced phosphoinositide 3-kinase/Akt (PI3K/Akt) signaling pathways resulted in the high expression of Snail protein. This increase in Snail expression was associated with increased Huh7 cells invasiveness. Furthermore, we observed that correlation between Snail and Notch1 expression was the strongest in advanced grade HCC tissue. In conclusion, Notch1 and ROS-induced PI3K/Akt signals cooperatively increase Snail expression and may induce malignancy in HCC. PMID:24684482

Kim, H S; Jung, G



Snail Contributes to the Maintenance of Stem Cell-Like Phenotype Cells in Human Pancreatic Cancer  

PubMed Central

Snail, a potent repressor of E-cadherin expression, plays a key role in epithelial-to-mesenchymal transition (EMT) in epithelial cancer. Recently, EMT and stemness programs are found linked together. In the current study, the expression of Snail and its contribution to cancer stem cell (CSC) marker expression, invasiveness, self-renewal, clonogenicity, and tumorigenicity of pancreatic cancer cells were studied. Our results showed that Snail was highly expressed in CSChigh cell line Panc-1. Stable, short hairpin RNA (shRNA)-mediated Snail knockdown decreased invasion in Panc-1 cells, in line with increased E-cadherin expression and its translocation from the nucleus to the membrane. Snail silencing in Panc-1 also inhibited CSC marker ALDH expression, together with decreased sphere and colony forming capacity, which was highly consistent with the expression of stem cell associated transcription factors like Sox2 and Oct4. In mouse xenograft models, knockdown of Snail led to a reduced number of tumor-bearing mice and a reduced average size of tumors, which had a stronger membrane staining of E-cadherin and lighter staining of Oct4. Collectively, these findings implicate Snail is required for the maintenance of stem cell-like phenotype in pancreatic cancer, and inhibition of Snail could be an efficient strategy to treat pancreatic cancer by targeting CSCs.

Zhou, Wei; Lv, Ran; Qi, Weilin; Wu, Di; Xu, Yunyun; Liu, Wei; Mou, Yiping; Wang, Liewei



Effects of desiccation on two life stages of an invasive snail and its native cohabitant  

Microsoft Academic Search

Invasive species are of critical concern as they have the potential to rapidly alter biotic systems around the globe. The\\u000a upper Mississippi River (UMR) system has been recently invaded by the aquatic snail, Bithynia tentaculata, which spread from the Great Lakes region. In addition to potentially impacting native aquatic snails, B. tentaculata also carries three parasites which kill thousands of

Allison M. Wood; Cody R. Haro; Roger J. Haro; Gregory J. Sandland


Influence of Snail on Integrin Beta l Expression/Activity in Breast Carcinoma.  

National Technical Information Service (NTIS)

We provide the first evidence that Snail-1, a tumor progression factor 1-3, influences breast tumor cell adhesion to matrix proteins. Specifically, we show that Snail-1 reduces alpha2 beta1 integrin expression levels in breast tumor cells. This novel Snai...

R. E. Bachelder



Influence of Snail on Integrin Beta 1 Expression/Activity in Breast Carcinoma.  

National Technical Information Service (NTIS)

We provide the first evidence that Snail-1, a tumor progression factor 1-3, influences breast tumor cell adhesion to matrix proteins. Specifically, we show that Snail-1 reduces alpha2 beta1 integrin expression levels in breast tumor cells. This novel Snai...

R. E. Bachelder



Snail contributes to the maintenance of stem cell-like phenotype cells in human pancreatic cancer.  


Snail, a potent repressor of E-cadherin expression, plays a key role in epithelial-to-mesenchymal transition (EMT) in epithelial cancer. Recently, EMT and stemness programs are found linked together. In the current study, the expression of Snail and its contribution to cancer stem cell (CSC) marker expression, invasiveness, self-renewal, clonogenicity, and tumorigenicity of pancreatic cancer cells were studied. Our results showed that Snail was highly expressed in CSC(high) cell line Panc-1. Stable, short hairpin RNA (shRNA)-mediated Snail knockdown decreased invasion in Panc-1 cells, in line with increased E-cadherin expression and its translocation from the nucleus to the membrane. Snail silencing in Panc-1 also inhibited CSC marker ALDH expression, together with decreased sphere and colony forming capacity, which was highly consistent with the expression of stem cell associated transcription factors like Sox2 and Oct4. In mouse xenograft models, knockdown of Snail led to a reduced number of tumor-bearing mice and a reduced average size of tumors, which had a stronger membrane staining of E-cadherin and lighter staining of Oct4. Collectively, these findings implicate Snail is required for the maintenance of stem cell-like phenotype in pancreatic cancer, and inhibition of Snail could be an efficient strategy to treat pancreatic cancer by targeting CSCs. PMID:24489910

Zhou, Wei; Lv, Ran; Qi, Weilin; Wu, Di; Xu, Yunyun; Liu, Wei; Mou, Yiping; Wang, Liewei



Accumulation and excretion of DDT by the terrestrial snail, Cepaea hortensis  

Microsoft Academic Search

Terrestrial gastropods (snails and slugs) have been shown to accumulate considerable quantities of the organochlorine insecticide DDT, with no noticeable toxic effect. These invertebrates serve as a source of this concentrated pesticide to vertebrate predators. Snails and slugs as non-target organisms accumulate DDT residues at concentrations equal to or considerably higher than the surrounding environment. Such information from the literature

Daniel L. Dindal; Karl-Hans Wurzinger



The golden apple snail Pomacea canaliculata in Asian rice farming systems: Present impact and future threat  

Microsoft Academic Search

The golden apple snail, Pomacea canaliculata (Lamarck, 1822) (Mesogastropoda: Pilidae), has recently been introduced to several Asian countries where it has unexpectedly developed into a pest of rice. Reasons for the introduction as well as the economic and ecological impact of the snail are described. Most farmers have resorted to chemical control, with implications for human health and the environment.

Matthias Halwart




EPA Science Inventory

Brown garden snails, Helix aspersa, were fed prepared diets with 12 pesticides used in forest spraying practices where endangered arboreal and terrestrial snails may be at risk. cephate, atrazine, glyphosate, hexazinone, and picloram were not lethal at concentrations of 5,000 mg/...


Dissociation of sexual arousal and sexual proclivity in the garden snail, Helix aspersa.  


Sexual arousal (intensity of courtship) and sexual proclivity (tendency to court) in Helix aspersa can be reliably measured using externally observable correlates. Snails with sexual proclivity are significantly more likely to turn toward an anesthetized conspecific after contacting it than are sexually unreceptive snails. Sexual arousal can be inferred from the stage of a snail's genital eversion, which appears only during courtship. The higher the stage of the eversion, the shorter the time required to complete introductory courtship behavior and the higher the rate of successful copulation, the fewer the number of breaks and pauses during courtship, and the longer the time a snail will spend in contact with an anesthetized conspecific. Sexual proclivity has no effect on feeding or locomotory behavior; however, sexual arousal inhibits feeding and increases locomotor activity. Snails that were allowed daily contact with conspecifics required less time to complete introductory courtship behavior relative to snails that were isolated from conspecifics for 1 week. This suggests that daily contact increases sexual arousal. A greater percentage of isolated snails exhibited courtship behavior than did snails which had experienced daily conspecific contact. This suggests that isolation increases sexual proclivity. These differences indicate that sexual arousal is not merely due to an increase in sexual proclivity. PMID:2241758

Adamo, S A; Chase, R



Tests of the Ability of Five Disinfectants to Kill New Zealand Mud Snails  

Microsoft Academic Search

We exposed New Zealand mud snails (NZMS), Potamopyrgus antipodarum, to various concentrations of four different quaternary ammonium-based disinfectants (Roccal D-Plus, Hyamine 1622, benzalkonium chloride, and Stepanquat 50 NF) and to liquid dish soap (Dawn) for 15 min. After 24 h of recovery in water, survival of the exposed snails was determined. Generally, mortality increased with increased chemical concentration. A concentration

Randall W. Oplinger; Eric Wagner



A Snail1/Notch1 signalling axis controls embryonic vascular development.  


Notch1-Delta-like 4 (Dll4) signalling controls vascular development by regulating endothelial cell (EC) targets that modulate vessel wall remodelling and arterial-venous specification. The molecular effectors that modulate Notch signalling during vascular development remain largely undefined. Here we demonstrate that the transcriptional repressor, Snail1, acts as a VEGF-induced regulator of Notch1 signalling and Dll4 expression. EC-specific Snail1 loss-of-function conditional knockout mice die in utero with defects in vessel wall remodelling in association with losses in mural cell investment and disruptions in arterial-venous specification. Snail1 loss-of-function conditional knockout embryos further display upregulated Notch1 signalling and Dll4 expression that is partially reversed by inhibiting ?-secretase activity in vivo with Dll4 identified as a direct target of Snail1-mediated transcriptional repression. These results document a Snail1-Dll4/Notch1 axis that controls embryonic vascular development. PMID:24894949

Wu, Zhao-Qiu; Rowe, R Grant; Lim, Kim-Chew; Lin, Yongshun; Willis, Amanda; Tang, Yi; Li, Xiao-Yan; Nor, Jacques E; Maillard, Ivan; Weiss, Stephen J



[Neurochemical mechanisms of food aversion conditioning consolidation in snail Helix lucorum].  


Effects of cycloheximide, protein synthesis inhibitors, as well as serotonin receptor antagonist and NMDA receptor antagonist on food aversion conditioning consolidation were studied in snail Helix lucorum. Food aversion conditioning was absent in snails after application of cycloheximide. Repeated produced no food aversion conditioning for the same type of food in these snails without cycloheximide application. Food aversion conditioning was absent in snails after applications of metiotepin, nonselective serotonin receptors antagonist, or after MK-801, NMDA glutamate receptors antagonist. At the same time, repeated training produced facilitated food aversion conditioning for the same type of food in these snails. Our experiments were the first which showed that effect on different molecular mechanisms evoked reversible or irreversible disruption of long-term memory consolidation during the same learning. It was suggested that suppression of retrieval produced reversible effect, whereas disruption of memory storage initiated irreversible effect on long-term memory consolidation. PMID:19140302

Solntseva, S V; Nikitin, v P



[Neurochemical mechanisms of food aversion conditioning consolidation in snail helix lucorum].  


Effects of cycloheximide, protein synthesis inhibitor as well as serotonin receptor antagonist and NMDA receptor antagonist, on food aversion conditioning consolidation were studied in snail Helix lucorum. Food aversion conditioning was absent in snails after application of cycloheximide. Repeated training produced no food aversion conditioning for the same type of food in these snails without cycloheximide application. Food aversion conditioning was absent in snails after metiotepin, nonselective serotonin receptors antagonist, or after MK-801, NMDA glutamate receptors antagonist, applications. At the same time, repeated training produced facilitated food aversion conditioning for the same type of food in these snails. Our experiments were the first which showed that effect on different molecular mechanisms evoked reversible or irreversible disruption of long-term memory consolidation during the same learning. It was suggested that suppression of retrieval produced reversible effect whereas disruption of memory storage initiated irreversible effect on long-term memory consolidation. PMID:18825927

Solntseva, S V; Nikitin, V P



40 CFR 35.1605-2 - Freshwater lake.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Freshwater lake. 35.1605-2 Section 35.1605-2 Protection...Protecting and Restoring Publicly Owned Freshwater Lakes § 35.1605-2 Freshwater lake. Any inland pond, reservoir,...



Nuclear sex-determining genes cause large sex-ratio variation in the apple snail Pomacea canaliculata.  


Evolutionary maintenance of genetic sex-ratio variation is enigmatic since genes for biased sex ratios are disadvantageous in finite populations (the "Verner effect"). However, such variation could be maintained if a small number of nuclear sex-determining genes were responsible, although this has not been fully demonstrated experimentally. Brood sex ratios of the freshwater snail Pomacea canaliculata are highly variable among parents, but population sex ratios are near unity. In this study, the effect of each parent on the brood sex ratio was investigated by exchanging partners among mating pairs. There were positive correlations between sex ratios of half-sib broods of the common mother (r = 0.42) or of the common father (r = 0.47). Moreover, the correlation between full-sib broods was very high (r = 0.92). Thus, both parents contributed equally to the sex-ratio variation, which indicates that nuclear genes are involved and their effects are additive. Since the half-sib correlations were much stronger than the parent-offspring regressions previously obtained, the variation was caused by zygotic sex-determining genes rather than by parental sex-ratio genes. The number of relevant genes appears to be small. PMID:17057241

Yusa, Yoichi



Use of a saponin based molluscicide to control Pomacea canaliculata snails in Southern Brazil.  


Pomacea canaliculata snails pose a severe problem to direct seeded rice cultivated in Southern Brazil. Control of this snail is nowadays performed with toxic chemicals such as copper sulfate and fungicides such as fentin. A novel natural molluscicide based on alkali modified quinoa (Chenopodium quinoa) saponins was tested under laboratory conditions. Snails were collected in rice fields close to Porto Alegre (State of Rio Grande do Sul) and in Brusque (State of Santa Catarina, 400 km north of Porto Alegre). In Santa Catarina the product was very effective, while in Porto Alegre it had no effect. This unexpected behavior was probably due to the respiratory habits of the snails under different contents of dissolved oxygen in the water. Near Porto Alegre the water used in rice fields is heavily polluted, with dissolved oxygen levels of 1-2 ppm, and the snails rely primarily on their siphon and lungs to breathe. Since saponin control is probably due to an interaction between saponins with the sterols present in the cell walls in the gills, no control was observed. By contrast, in Santa Catarina the dissolved oxygen level of the water is 5-6 ppm, and the snails remain mostly underwater, breathing with their gills. In this case the snails died within 24 h at a dose of 20 and 30 ppm of product. To test this observation, snails grown in polluted waters were forced to remain underwater in saponin solutions and water (control) preventing the use of their siphon to breathe. The snails exposed to saponin solutions died, while the control snails survived, indicating that they were still able to use their gills to breathe. These results indicate that the use of the saponin product is limited to rice fields not irrigated with heavily polluted waters. PMID:19911565

San Martíns, R; Gelmi, Claudio; de Oliveira, Jaime Vargas; Galo, José Luis; Pranto, Honorio



Snail1 expression in colorectal cancer and its correlation with clinical and pathological parameters  

PubMed Central

Background Snail1 is a transcription regulator of E-cadherin. The loss of E-cadherin seems to be a crucial step in the process of Epithelial-mesenchymal transition (EMT). EMT initiates invasion and proliferation in many tumours. Overexpression of Snail1 is known to be associated with poor outcome in several solid tumours. The aim of this study was to analyse its expression profile and prognostic significance in colorectal cancer. Methods Tissue microarrays (TMA) containing paraffin-embedded primary colorectal cancer (CRC) tissue samples from 251 patients were used in this study. The expression of Snail1 and E-cadherin was assessed by immunohistochemistry in different tumour compartments, corresponding lymph node metastases and normal colonic mucosa. Intensity of staining was classified according to the Remmele score (standardized scoring system) as well as the semiquantitative score established by Blechschmidt et al. Results Snail1 expression was observed in 76% of the CRC. Loss of E-cadherin was noted in 87% of the CRC. Snail1 positive tumours were significantly correlated with Snail1 positive lymph node metastases (p=0.03). There was no significant correlation between loss of E-cadherin and Snail1 expression, or between N-stage or grading and Snail1 expression. Kaplan-Meier survival analysis identified no prognostic impact of Snail1 expression on overall survival. Conclusion Snail1 expression was detectable in most of the CRC but showed no significant association with E-cadherin loss, clinical pathological characteristics or overall survival. The observed loss of E-cadherin could be explained by effects of other important EMT pathways, such as the Wnt-signalling cascade.



Snails and slugs damaging the cut foliage, Cordyline fruticosa and use of biorationals towards their management.  


Snails and slugs became a serious molluscan pests and damaging leaves of purple compacta, Cordyline fruticosa extensively grown for export at Green Farm Ltd, Sri Lanka. The export quality of leaves of C. fruticosa is lowered due to feeding of snails, Achantina fulica (Bowditch), Opeas pyrgula Schmacker and Boettgerx and Helix aspersa Muller and slugs incurring great loss to cut foliage industry. Paucity of information is available to understand snails and slugs damage and their host range that limits to develop suitable management practices. Therefore this study was aimed to determine damage, alternate hosts and to develop possible management practices. Snails and slugs damaged mainly fresh leaves of C. fruticosa. The severity of damage was 44.5% in infested field based on the visual rating method. Leaves of cassava, sting bean, okra, cucumber, passion fruit, papaya, Glyricidia and shoe flower were identified as alternate hosts and neem, Ixora and Dracaena spp were not served as alternate hosts. Among the plant materials tested for their repellence against snails and slugs revealed that neem seed powder was an irritant; neem leaves, mint leaves and Lantana leaves were acted as anti-feedant and Salt as chemical repellent. Among the barrier and bait experiments Bordeaux mixture exhibited a significant barrier effect against horizontal movement of snails. Baits made out of Metaldehyde bait, vegetables bait and jaggery had a strong effect in repelling the snails and slugs. Mulching with Madhuca longifolia punnac was the best to reduce the snails and slugs population compared to M. longifolia seed kernel powder. Oil from M. longifolia failed to reduce their population. Hence the results revealed that saponin containing M. longifolia punnac helped to eliminate snails and slugs when used as mulch. Metaldehyde, vegetable and jaggery baits are also useful to minimize their colonization further. Hence combination of these methods will help to prevent snails and slugs from damaging C. fruticosa and benefit to the cut foliage industry to sustain its export quality. PMID:23885439

Karthiga, S; Jegathambigai, V; Karunarathne, M D S D; Svinningen, A; Mikunthan, G



Protumorigenic effects of Snail-expression fibroblasts on colon cancer cells.  


Snail1 is a transcriptional factor that plays an important role in epithelial-mesenchymal transition and in the acquisition of invasive properties by epithelial cells. In colon tumors, Snail1 expression in the stroma correlates with lower specific survival of cancer patients. However, the role(s) of Snail1 expression in stroma and its association with patients' survival have not been determined. We used human primary carcinoma-associated fibroblasts (CAFs) or normal fibroblasts (NFs) and fibroblast cell lines to analyze the effects of Snail1 expression on the protumorigenic capabilities in colon cancer cells. Snail1 expression was higher in CAFs than in NFs and, as well as ?-SMA, a classic marker of activated CAFs. Moreover, in tumor samples from 50 colon cancer patients, SNAI1 expression was associated with expression of other CAF markers, such as ?-SMA and fibroblast activation protein. Interestingly, coculture of CAFs with colon cells induced a significant increase in epithelial cell migration and proliferation, which was associated with endogenous SNAI1 expression levels. Ectopic manipulation of Snail1 in fibroblasts demonstrated that Snail1 expression controlled migration as well as proliferation of cocultured colon cancer cells in a paracrine manner. Furthermore, expression of Snail1 in fibroblasts was required for the coadjuvant effect of these cells on colon cancer cell growth and invasion when coxenografted in nude mice. Finally, cytokine profile changes, particularly MCP-3 expression, in fibroblasts are put forward as mediators of Snail1-derived effects on colon tumor cell migration. In summary, these studies demonstrate that Snail1 is necessary for the protumorigenic effects of fibroblasts on colon cancer cells. PMID:24242829

Herrera, Alberto; Herrera, Mercedes; Alba-Castellón, Lorena; Silva, Javier; García, Vanesa; Loubat-Casanovas, Jordina; Alvarez-Cienfuegos, Ana; Miguel García, José; Rodriguez, Rufo; Gil, Beatriz; Ma Jesús Citores; Ma Jesús Larriba; Ignacio Casal, J; de Herreros, Antonio García; Bonilla, Félix; Peña, Cristina



Changes in Frequency of Spontaneous Oscillations in Procerebrum Correlate to Behavioural Choice in Terrestrial Snails  

PubMed Central

The aim of our study was to understand functional significance of spontaneous oscillations of local field potential in the olfactory brain lobe of terrestrial snail, the procerebrum (PC). We compared changes in frequency of oscillations in semi-intact preparations from snails trained to percept the same conditioned odor as positive (associated with food reinforcement) or negative (associated with noxious reinforcement). In vivo recordings in freely behaving naïve snails showed a significant decrease of spontaneous PC oscillations frequency during a stage of tentacle withdrawal to odor presentation. In in vitro preparations from naïve snails, a similar decrease in frequency of the PC oscillations to odor presentation was observed. Changes in frequency of the oscillations to cineole presentations in the “aversive” group of snails (demonstrating withdrawal) were much more pronounced than in naïve snails. No significant difference in responses to 5% and 20% cineole was noted. Changes in the spontaneous oscillations frequency in the snails trained to respond with positive reaction (approach) to cineole depended on the concentration of the applied odor, and these responses were qualitatively similar to responses of other groups during the first 10?s of responses to odor, but significantly different (increase in PC oscillations frequency) from the responses of the aversively trained and naïve snails in the interval 11–30?s, which corresponds to the end of the tentacle withdrawal and timing of decision making (approach or escape) in the free behaving snails. Obtained results suggest that frequency of the PC lobe spontaneous oscillations correlate to the choice of behavior in snails: withdrawal (decrease in frequency) or approach (increase in frequency) to the source of odor.

Samarova, Elena; Balaban, Pavel



Refuge function of marine algae complicates selection in an intertidal snail.  


Species with restricted gene flow often show trait-shifts from one type of environment to another. In those rock-dwelling marine gastropods that lack larval dispersal, size generally decreases in wave-exposed habitats reducing risk of dislodgement, while increases in less exposed habitats to resist crab-crushing. In Littorina fabalis, however, snails of moderately exposed shores are generally much larger (11-14 mm) than snails of sheltered shores (5-8 mm). Observations from the White Sea (where crabs are not present) indicate that in the absence of crabs snails are small (6-7 mm) in both habitats. We assumed that the optimal size for L. fabalis in the absence of crabs is less than 8 mm, and thus that increased size in moderately exposed habitats in areas with crabs might be a response to crab predation. In a crab-rich area (Sweden) we showed that crab predation is an important mortality factor for this snail species in both sheltered and moderately exposed habitats. In sheltered habitats, snails were relatively more protected from crab-predation when dwelling on their habitual substrate, fucoid algae, than if experimentally tethered to rocks below the algae. This showed that algae function as snail refuges. Snail dislodgement increased, however, with wave exposure but tethering snails in moderately exposed habitats showed that large snails survived equally well on rocks under the algae as in the canopy of the algae. Thus in sheltered habitats a small snail size is favored, probably due to life-history reasons, while increased risk of being dislodged from the algae refuges promotes a large size in moderately exposed habitats. This study shows an example of selection of a trait depends on complex interactions of different factors (life-history optimization, crab predation, wave induced dislodgement and algal refuges). PMID:15711994

Kemppainen, Petri; van Nes, Solveig; Ceder, Christofer; Johannesson, Kerstin



Population studies on Oncomelania quadrasi, the snail intermediate host of Schistosoma japonicum, in the Philippines. 5. Quantitative analysis on successful snail control by land reclamation.  


For the control of Oncomelania quadrasi, environmental modifications, i.e., clearing of vegetation, leveling of swampy depression and draining of stagnant water by channeling and excavation were carried out at 3 areas in Leyte, Philippines from 1974 to 1977. The change of snail population resulted in the land reclamation was evaluated by the methods previously developed by the population studies on this snail. As a result of statistical analysis based on y = log(x + 0.01) transformation and the antilogarithmic mean density A-y = (antilog -y) -0.01, the reduction of snail population was observed at 13 out of 18 sites studied at 3 project areas and the significant reduction was statistically confirmed at 9 sites of them. Particularly at Dagami area, which was a wide and heavily snail-infested land adjacent to Dagami Poblacion, the reduction rate of snail density reached 87.7% to 99.2% and some wet depressions have been converted into good rice fields with little snail infestation at the last survey. PMID:3090317

Makiya, K; Tanaka, H; Bañez, E; Blas, B L; Santos, A T



A flavonol present in cocoa [(-)epicatechin] enhances snail memory.  


Dietary consumption of flavonoids (plant phytochemicals) may improve memory and neuro-cognitive performance, though the mechanism is poorly understood. Previous work has assessed cognitive effects in vertebrates; here we assess the suitability of Lymnaea stagnalis as an invertebrate model to elucidate the effects of flavonoids on cognition. (-)Epicatechin (epi) is a flavonoid present in cocoa, green tea and red wine. We studied its effects on basic snail behaviours (aerial respiration and locomotion), long-term memory (LTM) formation and memory extinction of operantly conditioned aerial respiratory behaviour. We found no significant effect of epi exposure (15 mg l(-1)) on either locomotion or aerial respiration. However, when snails were operantly conditioned in epi for a single 0.5 h training session, which typically results in memory lasting ~3 h, they formed LTM lasting at least 24 h. Snails exposed to epi also showed significantly increased resistance to extinction, consistent with the hypothesis that epi induces a more persistent LTM. Thus training in epi facilitates LTM formation and results in a more persistent and stronger memory. Previous work has indicated that memory-enhancing stressors (predator kairomones and KCl) act via sensory input from the osphradium and are dependent on a serotonergic (5-HT) signalling pathway. Here we found that the effects of epi on LTM were independent of osphradial input and 5-HT, demonstrating that an alternative mechanism of memory enhancement exists in L. stagnalis. Our data are consistent with the notion that dietary sources of epi can improve cognitive abilities, and that L. stagnalis is a suitable model with which to elucidate neuronal mechanisms. PMID:23014569

Fruson, Lee; Dalesman, Sarah; Lukowiak, Ken



Speciation and Gene Flow between Snails of Opposite Chirality  

PubMed Central

Left-right asymmetry in snails is intriguing because individuals of opposite chirality are either unable to mate or can only mate with difficulty, so could be reproductively isolated from each other. We have therefore investigated chiral evolution in the Japanese land snail genus Euhadra to understand whether changes in chirality have promoted speciation. In particular, we aimed to understand the effect of the maternal inheritance of chirality on reproductive isolation and gene flow. We found that the mitochondrial DNA phylogeny of Euhadra is consistent with a single, relatively ancient evolution of sinistral species and suggests either recent “single-gene speciation” or gene flow between chiral morphs that are unable to mate. To clarify the conditions under which new chiral morphs might evolve and whether single-gene speciation can occur, we developed a mathematical model that is relevant to any maternal-effect gene. The model shows that reproductive character displacement can promote the evolution of new chiral morphs, tending to counteract the positive frequency-dependent selection that would otherwise drive the more common chiral morph to fixation. This therefore suggests a general mechanism as to how chiral variation arises in snails. In populations that contain both chiral morphs, two different situations are then possible. In the first, gene flow is substantial between morphs even without interchiral mating, because of the maternal inheritance of chirality. In the second, reproductive isolation is possible but unstable, and will also lead to gene flow if intrachiral matings occasionally produce offspring with the opposite chirality. Together, the results imply that speciation by chiral reversal is only meaningful in the context of a complex biogeographical process, and so must usually involve other factors. In order to understand the roles of reproductive character displacement and gene flow in the chiral evolution of Euhadra, it will be necessary to investigate populations in which both chiral morphs coexist.



Toxicity of botanical insecticides on golden apple snail (Pomacea canaliculata).  


The molluscicidal activity of crude extracts from five highly potential plants, Annona squamosa seed, Nerium indicum Leaves, Stemona tuberose root, Cyperus rotundus corm and Derris elliptica root was assessed to Pomacea canaliculata. D. elliptica root and C. rotundus corm extracts showed the highest toxicity against 3-month old snails which have LC50 as 23.68 +/- 2.96 mg/l and 133.20 +/- 7.94 mg/l, respectively. The C. rotundus corm extracts were chosen for detoxification enzyme in vivo assay which shows esterase and glutathione S-transferase activity in stomach, intestinal tracts and digestive glands of survival treated P. canaliculata were inhibited. PMID:21542482

Ruamthum, W; Visetson, S; Milne, J R; Bullangpoti, V



Metabolism of Carotenoids in the Apple Snail, Pomacea canaliculata  

Microsoft Academic Search

Feeding experiments with ?,?-carotene, canthaxanthin, (3R,3?R)-zeaxanthin, (3R,3?R,6?R)-lutein and racemic astaxanthin on the apple snail Pomacea canaliculata were investigated. Based on the experimental results, ?,?-carotene was oxidatively metabolized, and the resulting principal metabolic product (3S,3?S)-astaxanthin along with other keto carotenoids such as (3S)-3-hydroxy-?-echinenone, canthaxanthin, (3S,3?R)-4-ketozeaxanthin and (3S)-phoenicoxanthin was accumulated in the gonad. Similarly, (3R,3?R,6?R)-lutein was converted into fritschiellaxanthin [(3S,3?R,6?R)-3,3?-dihydroxy-?, ?-caroten-4-one]. It

Miyuki Tsushima; Masaaki Katsuyama; Takao Matsuno



[Equipment for biological experiments with snails aboard piloted orbital stations].  


To fly biological experiments aboard piloted orbital stations, research equipment was built up of an incubation container, filter system and automatic temperature controller. Investigations included analysis of the makeup and concentrations of gases produced by animals (snails) during biocycle, and emitted after death. Filters are chemisorption active fibrous materials (AFM) with high sorption rate and water receptivity (cation exchange fiber VION-KN-1 and anion exchange fiber VION-AS-1), and water-repellent carbon adsorbent SKLTS. AFM filters were effective in air cleaning and practically excluded ingress of chemical substances from the container into cabin atmosphere over more than 100 days. PMID:21033402

Gorgiladze, G I; Korotkova, E V; Kuznetsova, E E; Mukhamedieva, L N; Begrov, V V; Pepeliaev, Iu V



Davis Pond Freshwater Prediversion Biomonitoring Study: Freshwater Fisheries and Eagles  

USGS Publications Warehouse

In January 2001, the construction of the Davis Pond freshwater diversion structure was completed by the U.S. Army Corps of Engineers. The diversion of freshwater from the Mississippi River is intended to mitigate saltwater intrusion from the Gulf of Mexico and to lessen the concomitant loss of wetland areas. In addition to the freshwater inflow, Barataria Bay basin would receive nutrients, increased flows of sediments, and water-borne and sediment-bound compounds. The purpose of this biomonitoring study was, therefore, to serve as a baseline for prediversion concentrations of selected contaminants in bald eagle (Haliaeetus leucocephalus) nestlings (hereafter referred to as eaglets), representative freshwater fish, and bivalves. Samples were collected from January through June 2001. Two similarly designed postdiversion studies, as described in the biological monitoring program, are planned. Active bald eagle nests targeted for sampling eaglet blood (n = 6) were generally located southwest and south of the diversion structure. The designated sites for aquatic animal sampling were at Lake Salvador, at Lake Cataouatche, at Bayou Couba, and along the Mississippi River. Aquatic animals representative of eagle prey were collected. Fish were from three different trophic levels and have varying feeding strategies and life histories. These included herbivorous striped mullet (Mugil cephalus), omnivorous blue catfish (Ictalurus furcatus), and carnivorous largemouth bass (Micropterus salmoides). Three individuals per species were collected at each of the four sampling sites. Freshwater Atlantic rangia clams (Rangia cuneata) were collected at the downstream marsh sites, and zebra mussels (Dreissena spp.) were collected on the Mississippi River. The U.S. Geological Survey (USGS) Biomonitoring of Environmental Status and Trends (BEST) protocols served as guides for fish sampling and health assessments. Fish are useful for monitoring aquatic ecosystems because they accumulate pesticides and other contaminants. Biomarker data on individual fish, generated at the USGS National Wetlands Research Center (Lafayette, La.), included percent white blood cells in whole blood, spleen weight to body weight ratio, liver weight to body weight ratio, condition factor, splenic macrophage aggregates, and liver microsomal 7-ethoxyresorufin-o-deethylase (EROD) activity. Fish age was estimated by comparing total lengths with values from the same species in the Southeast United States as determined from the literature. Contaminant analyses were coordinated by the U.S. Fish and Wildlife Service (USFWS) Analytical Control Facility (Laurel, Md.), where residues of organochlorine (OC) pesticides, total polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), aliphatic hydrocarbons (AHs), and trace elements were determined. The organic contaminant data were generated at the Mississippi State University Chemical Lab (Mississippi State, Miss.), and the inorganic contaminant data were generated by the Texas A&M University Geochemical and Environmental Research Group (College Station, Tex.). Statistical tests were performed to assess relationships among contaminants, fish age, fish species, and collection sites.

Jenkins, Jill A.; Bourgeois, E. Beth; Jeske, Clint W.



The repressor function of snail is required for Drosophila gastrulation and is not replaceable by Escargot or Worniu.  


Mesoderm formation in the Drosophila embryo depends on the maternal Toll signaling pathway. The Toll pathway establishes the Dorsal nuclear gradient, which regulates many zygotic genes to establish the mesodermal fate and promote the invagination of ventral cells. An important target gene of Dorsal is snail, which is required for proper mesoderm invagination. The Snail protein contains five zinc fingers and is a transcriptional repressor. However, it is not clear whether repressing target genes is a requirement for Snail to control ventral invagination. To examine such requirement, we conducted a series of genetic rescue experiments in snail mutant embryos. Snail, Worniu, and Escargot are closely related zinc-finger proteins and have equal functions during neuroblast development. However, among these three proteins, only Snail can rescue the mesoderm invagination phenotype. Moreover, the ability of various Snail mutant constructs to repress gene expression correlates with their ability to control invagination. This unique property of Snail in mesoderm formation can be attributed mostly to the CtBP co-repressor interaction motifs in the N-terminus, not to the C-terminal DNA-binding zinc fingers. Ectopic expression of Snail outside the ventral domain is not sufficient to induce cell movement even though repression of target genes still occurs. Together, the results show that the repressor function of Snail is essential for gastrulation. The repression of target genes by Snail may permit other factors in the ventral cells to positively promote mesoderm invagination. PMID:15110709

Hemavathy, Kirugaval; Hu, Xiaodi; Ashraf, Shovon I; Small, Stephen J; Ip, Y Tony



Snail expression and outcome in T1 high-grade and T2 bladder cancer: a retrospective immunohistochemical analysis  

PubMed Central

Background Neoadjuvant chemotherapy has been shown to have benefit in T1 high-grade or T2 bladder cancer. However, neoadjuvant chemotherapy fails in some patients. Careful patient selection for neoadjuvant chemotherapy is therefore needed. Several reports show that Snail is associated with resistance to chemotherapy. We hypothesized that Snail expression could predict survival in T1 high-grade and T2 bladder cancer patients treated with neoadjuvant chemotherapy. Methods The participants were 44 patients with T1 high-grade and T2 bladder cancer receiving neoadjuvant chemotherapy. Immunohistochemical analysis was used to determine Snail expression in specimens of bladder cancer obtained by transurethral resection before neoadjuvant chemotherapy. The relationships between Snail expression and patients’ outcomes were analyzed. Results Snail expression was positive in 15 of the 44 patients (34.1%) and negative in 29 (65.9%). Disease-free survival was significantly shorter for the Snail-positive group than for the Snail-negative group (p?=?0.014). In addition, disease-specific survival was also significantly shorter for the Snail-positive group than for the Snail-negative group (p?=?0.039). In multivariate analysis, Snail expression level was identified as an independent prognostic factor for disease-specific survival (p?=?0.020). Conclusions The results indicate that Snail expression may predict poor outcome in T1 high-grade and T2 bladder cancer patients treated with neoadjuvant chemotherapy.



The Influence of Plagiorchis mutationis Larval Infection on the Cellular Immune Response of the Snail Host Lymnaea stagnalis.  


Abstract : The effects of trematode Plagiorchis mutationis parasitism on the cellular immune responses of the snail host Lymnaea stagnalis were investigated. The number of spreading blood cells (hemocytes) from infected snails was significantly less (69.5%) than in uninfected individuals (79.2%). The phagocytic activity of blood cells in infected snails was also significantly less (17.2%) compared to uninfected snails (27.8%). The hemocytes from the infected snails did not form a complete capsule around Sephadex beads in vitro. The protective reactions of the snail hosts were independent of the parasite load (daily cercariae production). In vitro, dead cercariae of P. mutationis were encapsulated by hemocytes from uninfected snails. The hemocytes of the infected snails formed a complete capsule around only 20% of dead cercariae in vitro, with remaining cercariae either unencapsulated (50% of cercariae) or incompletely encapsulated (30% of cercariae). The total number of hemocytes in the infected snails was twofold less than in uninfected individuals. The results of this study showed that the cellular response of snail host L. stagnalis to P. mutationis trematode infection is similar to the previously studied snail-trematode model systems. PMID:24428684

Kryukova, Natalia A; Yurlova, Natalia I; Rastyagenko, Natalia M; Antonova, Elena V; Glupov, Viktor V



The p65 subunit of NF-?B and PARP1 assist Snail1 in activating fibronectin transcription.  


Snail1 is a transcriptional repressor of E-cadherin that triggers epithelial-mesenchymal transition (EMT). Here, we report assisted Snail1 interaction with the promoter of a typical mesenchymal gene, fibronectin (FN1), both in epithelial cells undergoing EMT and in fibroblasts. Together with Snail1, the p65 subunit of NF-?B and PARP1 bound to the FN1 promoter. We detected nuclear interaction of these proteins and demonstrated the requirement of all three for FN1 transcription. Moreover, other genes involved in cell movement mimic FN1 expression induced by Snail1 or TGF-?1 treatment and recruit p65NF-?B and Snail1 to their promoters. The molecular cooperation between Snail1 and NF-?B in transcription activation provides a new insight into how Snail1 can modulate a variety of cell programs. PMID:22223884

Stanisavljevic, Jelena; Porta-de-la-Riva, Montserrat; Batlle, Raquel; de Herreros, Antonio García; Baulida, Josep



Freshwater Ecoregions of the World: A New Map of Biogeographic Units for Freshwater Biodiversity Conservation  

NSDL National Science Digital Library

We present a new map depicting the first global biogeographic regionalization of Earth's freshwater systems. This map of freshwater ecoregions is based on the distributions and compositions of freshwater fish species and incorporates major ecological and evolutionary patterns. Covering virtually all freshwater habitats on Earth, this ecoregion map, together with associated species data, is a useful tool for underpinning global and regional conservation planning efforts (particularly to identify outstanding and imperiled freshwater systems); for serving as a logical framework for large-scale conservation strategies; and for providing a global-scale knowledge base for increasing freshwater biogeographic literacy. Preliminary data for fish species compiled by ecoregion reveal some previously unrecognized areas of high biodiversity, highlighting the benefit of looking at the world's freshwaters through a new framework.

Robin Abell et al (WWF;)



Toxic effect of stem bark and leaf of Euphorbia hirta plant against freshwater vector snail Lymnaea acuminata  

Microsoft Academic Search

The aqueous stem bark and leaf extracts of plant Euphorbia hirta (family-Euphorbiaceae) have potent molluscicidal activity. Sub-lethal doses (40% and 80% of LC50) of aqueous stem bark and leaf extracts of this plant also significantly (P<0.05) alter the levels of total protein, total free amino acid, nucleic acids (DNA and RNA) and the activity of enzyme protease and acid and

Sunil Kumar Singh; Ram P. Yadav; Sudhanshu Tiwari; Ajay Singh



The role of spatial processes and environmental determinants in microgeographic shell variation of the freshwater snail Chilina dombeyana (Bruguière, 1789)  

NASA Astrophysics Data System (ADS)

Wildlife data often show spatial organization, demonstrating positive correlations either as a result of processes occurring over the landscape or due to the influence of spatially structured environmental variables. It is, thus, essential to consider non-random spatial structure when evaluating the underlying causes of biological variation. In this study, we analyzed the population structure of Chilina dombeyana shell morphology of 14 populations that are close geographically and belong to the same hydrographic basin. We utilized a variation partitioning approach to evaluate the importance of spatial processes, such as migration, acting over the landscape, and environmental characteristics, including habitat and hydrologic characteristics, and the occurrence of aquatic predators in promoting between population variation. Our results demonstrate spatially structured variation in C. dombeyana shell morphology, with populations living near each other having more similar shell sizes than populations living farther apart. The shell size variation partition indicated that both spatially structured environmental factors and genetic relationships resulting from migration or shared common ancestry may explain this pattern. Shell shape variation, in contrast, was found to be essentially under the influence of non-spatially structured environmental factors, with habitat and water characteristics accounting for about half of the total variation among populations. The large proportion of the variation in shell size that is spatially structured demonstrates that spatial structure on morphological traits might be strong and highlights the need to consider such phenomenon in intraspecific studies of phenotypic evolution.

Bertin, Angéline; Ruíz, Victor H.; Figueroa, Ricardo; Gouin, Nicolas



The effects of engineered nanoparticles on survival, reproduction, and behaviour of freshwater snail, Physa acuta (Draparnaud, 1805)  

Microsoft Academic Search

Increasing uses of engineered nanoparticles (ENPs) in commercial products and industrial applications has eventually resulted to their releases into atmospheric, terrestrial, and aquatic environments. However, knowledge gaps in ENPs toxicity, fate, and behaviour currently limit our ability to quantify risk assessment of materials with nanoscale dimensions, and therefore, the extent of the resultant environmental impacts remains unknown. In the present

N. Musee; P. J. Oberholster; L. Sikhwivhilu; A.-M. Botha


Davis Strait volume, freshwater and heat fluxes  

Microsoft Academic Search

Volume, freshwater and heat transport through Davis Strait, the northern boundary of the Labrador Basin, are computed using a mooring array deployed for three con- secutive years. The net volume, freshwater and heat transports are ?2.6 ± 1.0 Sv, ?92 ± 34 mSv ,1 8± 17 ? 1012W. Both southward and northward volume and fresh- water transports are maximum in

Jerome Cuny; Peter B. Rhines; Ron Kwok



Freshwater for resilience: a shift in thinking.  

PubMed Central

Humanity shapes freshwater flows and biosphere dynamics from a local to a global scale. Successful management of target resources in the short term tends to alienate the social and economic development process from its ultimate dependence on the life-supporting environment. Freshwater becomes transformed into a resource for optimal management in development, neglecting the multiple functions of freshwater in dynamic landscapes and its fundamental role as the bloodstream of the biosphere. The current tension of these differences in worldview is exemplified through the recent development of modern aquaculture contrasted with examples of catchment-based stewardship of freshwater flows in dynamic landscapes. In particular, the social and institutional dimension of catchment management is highlighted and features of social-ecological systems for resilience building are presented. It is concluded that this broader view of freshwater provides the foundation for hydrosolidarity.

Folke, Carl



Characterizations of Cholinesterases in Golden Apple Snail (Pomacea canaliculata).  


Cholinesterases (ChEs) have been identified in vertebrates and invertebrates. Inhibition of ChE activity in invertebrates, such as bivalve molluscs, has been used to evaluate the exposure of organophosphates, carbamate pesticides, and heavy metals in the marine system. The golden apple snail (Pomacea canaliculata) is considered as one of the worst invasive alien species harmful to rice and other crops. The ChE(s) in this animal, which has been found recently, but poorly characterized thus far, could serve as biomarker(s) for environmental surveillance as well as a potential target for the pest control. In this study, the tissue distribution, substrate preference, sensitivity to ChE inhibitors, and molecular species of ChEs in P. canaliculata were investigated. It was found that the activities of both AChE and BChE were present in all test tissues. The intestine had the most abundant ChE activities. Both enzymes had fair activities in the head, kidney, and gills. The BChE activity was more sensitive to tetra-isopropylpyrophosphoramide (iso-OMPA) than the AChE. Only one BChE molecular species, 5.8S, was found in the intestine and head, whereas two AChE species, 5.8S and 11.6S, were found there. We propose that intestine ChEs of this snail may be potential biomarkers for manipulating pollutions. PMID:24217797

Zou, Xiang-Hui; Xie, Heidi Qun-Hui; Zha, Guang-Cai; Chen, Vicky Ping; Sun, Yan-Jie; Zheng, Yu-Zhong; Tsim, Karl Wah-Keung; Dong, Tina Ting-Xia; Choi, Roy Chi-Yan; Luk, Wilson Kin-Wai



Imposex in the golden apple snail Pomacea canaliculata in Taiwan.  


The golden apple snail Pomacea canaliculata (Lamarck, 1822) was introduced into Taiwan intentionally in the early 1980s and has become a recurring pest that seriously threatens aquatic crops. In this study, a field description of imposex with a developed penis sheath and penis in female golden apple snails from crop/domestic wastewater drainage sites and a six-order river is presented for the first time. Based on the five field collections and the aquarium group, the vas deferens sequence (VDS) of P. canaliculata in imposex development was categorized into four stages, i.e., stage 0: without male genital system; stage 1: with rudimentary penis; stage 2: with rudimentary penis and penis sheath; and stage 3: the rudimentary penis developing into penis pouch and penis. The VDS indices varied between 1.07 and 2.82 and were lowest in the aquarium group and Yuanlin2. Regarding the severity of imposex, the aquarium group was less pronounced, as illustrated by the length of penis sheath and penis length, than the field collections (p<0.05). In respect of the penis length, males of the most imposex-affected site were up to 15% shorter than that of the aquarium group. Negative correlations between male penis length and female imposex characters (i.e., penis length and penis sheath length) were also observed. PMID:17023028

Liu, Wen-Hui; Chiu, Yuh-Wen; Huang, Da-Ji; Liu, Ming-Yie; Lee, Ching-Chang; Liu, Li-Lian



Reproduction and demography of the Florida Everglade (Snail) Kite  

USGS Publications Warehouse

An 18-year study of reproduction and survival of the Florida Everglade (Snail) Kite (Rostrhamus sociabilis plumbeus) has revealed the following: extremely poor nesting success (only 13.6% of nests found at the nest-building stage successful); extremely long breeding seasons (some reproductive activity in almost all months in good years); frequent multiple brooding and frequent multiple brooding and frequent renesting after failure; low egg hatchability (81%); high failure rates due to nest collapse, desertion, and predation; extremely high survival of juveniles and adults under good water conditions; and high vulnerability to drought due to near total dependency on a single species of drought-sensitive snail for food. Despite low nesting success, the species has increased rapidly under good conditions, mainly because of multiple nesting attempts within long breeding seasons and high survival rates of free-flying birds. Nesting success varied significantly between regions and nest substrates, but not as a function of seasons or solitary vs. colonial nesting. While nesting success was reduced in low water years, this effect was at least partly due to heavy use of poor nest substrates under such conditions. Clutch size and numbers of young per successful nest varied with regions, but not as a function of seasons or water levels. The effects of coloniality on clutch size and numbers of young were inconsistent. Significant effects of nest-substrate types on clutch size and numbers of young were apparently artifacts of substrate differences between regions.

Snyder, N.F.R.; Beissinger, S.R.; Chandler, R.E.



The slipper snail, Crepidula: an emerging lophotrochozoan model system.  


Recent developmental and genomic research focused on "slipper snails" in the genus Crepidula has positioned Crepidula fornicata as a de facto model system for lophotrochozoan development. Here we review recent developments, as well as earlier reports demonstrating the widespread use of this system in studies of development and life history. Recent studies have resulted in a well-resolved fate map of embryonic cell lineage, documented mechanisms for axis determination and D quadrant specification, preliminary gene expression patterns, and the successful application of loss- and gain-of-function assays. The recent development of expressed sequence tags and preliminary genomics work will promote the use of this system, particularly in the area of developmental biology. A wealth of comparative information on phylogenetic relationships, variation in mode of development within the family, and numerous studies on larval biology and metamorphosis, primarily in Crepidula fornicata, make these snails a powerful tool for studies of the evolution of the mechanisms of development in the Mollusca and Lophotrochozoa. By bringing a review of the current state of knowledge of Crepidula life histories and development together with some detailed experimental methods, we hope to encourage further use of this system in various fields of investigation. PMID:20570845

Henry, Jonathan J; Collin, Rachel; Perry, Kimberly J



Snail up-regulates pro-inflammatory mediators and inhibits differentiation in oral keratinocytes  

PubMed Central

The transcriptional repressor, Snail2, is over-expressed in head and neck squamous cell carcinomas (HNSCCs) relative to non-malignant head and neck mucosal epithelium, and in locally recurrent relative to non-recurrent HNSCCs. We investigated the mechanisms by which Snails might contribute to the pathogenesis of HNSCCs using cell biological and molecular analyses. Oral keratinocytes that expressed Snails acquired an enhanced ability to attract monocytes and to invade a dense interstitial collagen matrix. They were also found to up-regulate production of pro-inflammatory cytokines and cyclooxygenase-2 (COX2), which have previously been shown to correlate with malignancy. Induction of nuclear factor-kappa B transcriptional activity by Snails was weak and not sufficient to account for the elevated levels of COX2, interleukin-6, interleukin-8 or CXCL1. In addition, expression of Snails in oral keratinocytes impaired desquamation in vitro and strongly repressed expression of both ELF3 and matriptase-1, which play important roles in the terminal differentiation of keratinocytes. Re-expression of matriptase-1 in Snail-expressing cells partially rescued desquamation. This implicates Snails as contributing to malignancy both at the early stages, by impeding terminal differentiation, and at later stages, when invasion and inflammation are important.

Lyons, J. Guy; Patel, Vyomesh; Roue, Naomi C.; Fok, Sandra Y.; Soon, Lilian L.; Halliday, Gary M.; Gutkind, J. Silvio



A molecular role for lysyl oxidase-like 2 enzyme in Snail regulation and tumor progression  

PubMed Central

The transcription factor Snail controls epithelial–mesenchymal transitions (EMT) by repressing E-cadherin expression and other epithelial genes. However, the mechanisms involved in the regulation of Snail function are not fully understood. Here we show that lysyl-oxidase-like 2 and 3 (LOXL2 and LOXL3), two members of the lysyl-oxidase gene family, interact and cooperate with Snail to downregulate E-cadherin expression. Snail's lysine residues 98 and 137 are essential for Snail stability, functional cooperation with LOXL2/3 and induction of EMT. Overexpression of LOXL2 or LOXL3 in epithelial cells induces an EMT process, supporting their implication in tumor progression. The biological importance of LOXL2 is further supported by RNA interference of LOXL2 in Snail-expressing metastatic carcinoma cells, which led to a strong decrease of tumor growth associated to increased apoptosis and reduced expression of mesenchymal and invasive/angiogenic markers. Taken together, these results establish a direct link between LOXL2 and Snail in carcinoma progression.

Peinado, Hector; del Carmen Iglesias-de la Cruz, Maria; Olmeda, David; Csiszar, Katalin; Fong, Keith S K; Vega, Sonia; Nieto, Maria Angela; Cano, Amparo; Portillo, Francisco



The mesoderm determinant snail collaborates with related zinc-finger proteins to control Drosophila neurogenesis.  


The Snail protein functions as a transcriptional regulator to establish early mesodermal cell fate. Later, in germ band-extended embryos, Snail is also expressed in most neuroblasts. Here we present evidence that this expression of Snail is required for central nervous system (CNS) development. The neural function of snail is masked by two closely linked genes, escargot and worniu. Both Escargot and Worniu contain zinc-finger domains that are highly homologous to that of Snail. Although not affecting expression of early neuroblast markers, the deletion of the region containing all three genes correlates with loss of expression of CNS determinants including fushi tarazu, pdm-2 and even-skipped. Transgenic expression of each of the three Snail family proteins can rescue efficiently the fushi tarazu defects, and partially the pdm-2 and even-skipped CNS patterns. These results demonstrate that the Snail family proteins have essential functions during embryonic CNS development, around the time of ganglion mother cell formation. PMID:10562554

Ashraf, S I; Hu, X; Roote, J; Ip, Y T



Radix natalensis: the effect of Fasciola hepatica infection on the reproductive activity of the snail  

PubMed Central

Experimental infections of Egyptian Radix natalensis (shell height at miracidial exposure: 4 mm) with a French isolate of Fasciola hepatica were carried out under laboratory conditions at 22 °C to specify the characteristics and follow the dynamics of their egg-laying. Controls constituted unexposed R. natalensis of the same size. No significant difference between controls and the uninfected snails of the exposed group was noted, whatever the parameter considered. In controls and exposed snails, the dates of the first egg masses were close to each other (56.4–65.3 days). In contrast, the life span of snails and the length of the egg-laying period were significantly shorter and egg production was significantly lower in infected R. natalensis than in controls and uninfected snails. In infected R. natalensis, but without cercarial shedding (NCS snails), egg production was irregular throughout the egg-laying period. In cercarial-shedding (CS) snails, the first egg masses were laid before the first cercarial emergence (at a mean of 56 days and 67 days, respectively). Thereafter, egg mass production of CS snails was irregular up to day 72 of the experiment, stopped during the following two weeks and started again after day 88 for a single snail. In conclusion, the F. hepatica infection of R. natalensis reduced the reproductive activity in both NCS and CS snails. The pattern noted for egg production in infected R. natalensis seems to be species-specific because of the high shell size of this lymnaeid and its role as an atypical intermediate host in the life cycle of the parasite.

Dar, Yasser; Vignoles, Philippe; Rondelaud, Daniel; Dreyfuss, Gilles



Expression of Snail is associated with myofibroblast phenotype development in oral squamous cell carcinoma.  


Snail is a regulator of epithelial-mesenchymal transition (EMT) and considered crucial to carcinoma metastasis, myofibroblast transdifferentiation, and fibroblast activation. To investigate the role of Snail in oral squamous cell carcinoma (OSCC), its immunohistochemical expression was analysed in 129 OSCC samples and correlated to nodal metastasis, histological grade, E-cadherin, and alpha smooth-muscle-actin (alpha SMA). The results were compared to findings in 23 basal cell carcinomas (BCC). Additionally, the influence of TGF beta 1 and EGF on Snail, E-cadherin, vimentin, and alpha SMA expression was analysed in two OSCC cell lines. As a result, Snail-positive cells were mainly found in the stroma of the OSCC invasive front without statistically significant correlation to histological grade or nodal metastasis. Snail was co-localised to alpha SMA but not to E-cadherin or cytokeratin and showed a significant correlation to the loss of membranous E-cadherin. All BCCs were Snail negative. In OSCC culture, the growth-factor-mediated EMT-like phenomenon was accompanied by alpha SMA down-regulation. In summary, Snail expression in OSCC is a stromal phenomenon associated with the myofibroblast phenotype and not related to growth-factor-mediated transdifferentiation of the carcinoma cells themselves. Consequently, Snail immunohistochemistry cannot contribute to the prediction of the metastatic potential. Furthermore, stromal Snail expression is suggested to be the result of mutual paracrine interaction of fibro-/myofibroblasts and dedifferentiated carcinoma cells leading to the generation of a special type of carcinoma-associated fibroblasts. PMID:19198871

Franz, Marcus; Spiegel, Karin; Umbreit, Claudia; Richter, Petra; Codina-Canet, Carolina; Berndt, Angela; Altendorf-Hofmann, Annelore; Koscielny, Sven; Hyckel, Peter; Kosmehl, Hartwig; Virtanen, Ismo; Berndt, Alexander



Snail2 promotes osteosarcoma cell motility through remodelling of the actin cytoskeleton and regulates tumor development  

PubMed Central

The function of Snail2 in mesenchymal tumors is, to date unknown. Using knockdown and overexpression studies, we show that Snail2 regulates migration and invasion of osteosarcoma cells. Knockdown resulted in significantly decreased motility, remodelling of the actin cytoskeleton, and loss of cellular protrusions. Over-expression increased motility, formation of actin-rich cellular protrusions, and altered expression of some non-canonical Wnt pathway components whilst decreasing expression of the adhesion molecule OB-cadherin. Unexpectedly, knockdown also resulted in significantly smaller tumors in an in vivo CAM assay. Therefore Snail2 may be a potential therapeutic target for clinical intervention of osteosarcoma.

Sharili, Amir-Shaya; Allen, Steve; Smith, Ken; Price, Joanna; McGonnell, Imelda M.



Susceptibility of Saudi Bulinus truncatus to infection with Egyptian Schistosoma haematobium with observations on protein electrophoretic pattern of the snails.  


A laboratory-based susceptibility study was carried out on snails Bulinus truncatus collected from highland Abha, Asser, Saudi Arabia to Egyptian Schistosoma haematobium to investigate the potential role of Saudi B. truncatus in the transmission of Egyptian S. haematobium and to know the possibility that the parasite might be able to spread into Saudi Arabia. The results revealed that, compared to Egyptian snails, survival of snails at day 25 post-exposure was significantly higher in Saudi B. truncatus ones. The infection rate was higher in Saudi snails as compared to Egyptian ones. The incubation period was shorter in Saudi snails but the duration of cercarial shedding was longer in the Egyptian than in the Saudi snails. The production of S. haematobium cercariae per snail was higher in Egyptian snails than in Saudi ones. These results suggest that Saudi B. truncatus can play a role in the transmission of Egyptian S. haematobium in Saudi Arabia and therefore this parasite might be able to spread into the Kingdom. In addition, electrophoretic analysis of tissue soluble proteins was done to determine the effects of the parasite on both the Egyptian and Saudi snails. The electrophoretic analysis revealed the occasional presence or absence of certain bands in infected snails in comparison with non-infected one. PMID:19329256

Mostafa, Osama M S; Bin Dajem, Saad M; Abu El Einin, Hanaa M



Transforming growth factor beta-1 induces snail transcription factor in epithelial cell lines: mechanisms for epithelial mesenchymal transitions.  


The Snail transcription factor has been described recently as a strong repressor of E-cadherin in epithelial cell lines, where its stable expression leads to the loss of E-cadherin expression and induces epithelial-mesenchymal transitions and an invasive phenotype. The mechanisms regulating Snail expression in development and tumor progression are not yet known. We show here that transforming growth factor beta-1 (TGFbeta1) induces Snail expression in Madin-Darby canine kidney cells and triggers epithelial-mesenchymal transitions by a mechanism dependent on the MAPK signaling pathway. Furthermore, TGFbeta1 induces the activity of Snail promoter, whereas fibroblast growth factor-2 has a milder effect but cooperates with TGFbeta1 in the induction of Snail promoter. Interestingly, TGFbeta1-mediated induction of Snail promoter is blocked by a dominant negative form of H-Ras (N17Ras), whereas oncogenic H-Ras (V12Ras) induces Snail promoter activity and synergistically cooperates with TGFbeta1. The effects of TGFbeta1 on Snail promoter are dependent of MEK1/2 activity but are apparently independent of Smad4 activity. In addition, H-Ras-mediated induction of Snail promoter, alone or in the presence of TGFbeta1, depends on both MAPK and phosphatidylinositol 3-kinase activities. These data support that MAPK and phosphatidylinositol 3-kinase signaling pathways are implicated in TGFbeta1-mediated induction of Snail promoter, probably through Ras activation and its downstream effectors. PMID:12665527

Peinado, Hector; Quintanilla, Miguel; Cano, Amparo



Chemical properties of the extracellular matrix of the snail nervous system: a comprehensive study using a combination of histochemical techniques.  


The extracellular matrix (ECM) consists of various types of protein and carbohydrate polymers with red-ox and acid-base properties that have a crucial impact on tissue homeostasis. In the present study, a combination of both frequently applied and also specialized histochemical staining methods were used to reveal the chemical properties of the ECM of the snail central nervous system (CNS) which has a long been favored experimental model for comparative neurobiologists. Reactions such as silver ion reduction to label oxidative elements and different protein fibers, visible and fluorescent periodic-Schiff (PAS) reaction for the detection of unbranched chain of carbohydrates, and cationic dyes (acridine orange and alcian blue) for differentiating acidic carbohydrates were used. Illumination of sections stained with toluidine blue at pH 4.0 by a fluorescent light (lambda ex546/em580 nm), visualized components of the extraneural space (ECM molecules and glial cells) of the adult and also the developing CNS. Silver, toluidine blue and azure A were used to detect specific molecule bands in CNS extracts separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Some molecules showed both negative character and had carbohydrate side chains revealed by the Solanum tuberosum lectin probe. In a comparison of a freshwater aquatic (Lymnaea stagnalis) and a terrestrial (Helix pomatia) species, the ECM showed similarities in the composition of the periganglionic sheath and interperikaryonal space. The sheath was rich in alcian blue-positive sulfated proteoglycans infiltrated the space between collagen and reticular fibers, whereas in the interperikaryonal space PAS- and acridine orange-positive neutral and weakly acidic carbohydrates were detected. The ganglionic neuropil was mostly filled with PAS-positive material, but negatively charged sulfated and carboxylated molecules detected by acridine orange and alcian blue were present only in Helix. A low carbohydrate content was also found in the neuropil of both adult and developing Lymnaea, but most of the ECM components appeared only during the postembryonic juvenile stages. Comparing the SDS-PAGE of the periganglionic sheath and neural tissue extracts, toluidine blue (pH 4.0) and azure A (pH 2.0) revealed negatively charged molecules; some were found in both fractions. These results show, for the first time, the general chemical characteristics of the ECM of the snail CNS, indicating differences in the composition of the ganglion neuropil between aquatic and terrestrial species. Hence, a different strategy for retaining water by the neural tissue is suggested in species living in different environments. PMID:20219380

Serfozo, Zoltán; Elekes, Károly



Suppression of SCARA5 by Snail1 is essential for EMT-associated cell migration of A549 cells  

PubMed Central

Accumulating evidence indicates that epithelial-to-mesenchymal transition (EMT) might be a key event for cancer progression. The upregulation of Snail1, one of the most extensively studied EMT regulators, has been implicated in cancer metastasis, but the underlying mechanisms remain unclear. This study aims to identify that Snail1 targets regulating EMT-associated cancer cell migration. Human lung carcinoma A549 cells were treated with transforming growth factor beta 1 (TGF-?1), and EMT-associated phenotypic and functional alterations were monitored. TGF-?1 induced typical EMT-like morphological changes, ‘cadherin switching' and cell migration in A549 cells. TGF-?1 stimulation induced rapid and persistent upregulation of Snail1. Moreover, Snail1 upregulation was required for EMT-associated cell migration. Several metastasis suppressors with putative Snail1-binding sites in their promoters were dramatically repressed in A549 cells during TGF-?1-induced EMT. Gain- and loss-of Snail1 function experiments demonstrated that scavenger receptor class A member 5 (SCARA5) was negatively regulated by Snail1. Importantly, SCARA5 downregulation was essential for EMT-induced migration in A549 cells. The chromatin immunoprecipitation assay revealed that Snail1 could bind to the E-box elements in SCARA5 promoter, implying that SCARA5 is a direct Snail1 target modulating cancer cell mobility during EMT. In addition, we showed that DNA methyltransferase 1 was physically associated with Snail1 to silence SCARA5 expression with an unidentified DNA methylation-independent mechanism, suggesting the complexity of Snail1-mediated epigenetic regulation. Collectively, our data demonstrated that EMT-regulator Snail1 suppresses the expression of SCARA5 to promote cancer progression, highlighting the possibility to target Snail1 and SCARA5 for cancer treatment.

Liu, J; Hu, G; Chen, D; Gong, A-Y; Soori, G S; Dobleman, T J; Chen, X-M



Habitat structure effects on size selection of snail kites ( Rostrhamus sociabilis ) and limpkins ( Aramus guarauna ) when feeding on apple snails ( Pomacea spp.)  

NASA Astrophysics Data System (ADS)

Consumer density can influence foraging patterns such as prey-size selection, but few studies have evaluated its effects in field conditions. Here we evaluate the hypothesis that habitat structure influences forager density, and that this in turn influences the size of prey consumed by two avian predators. The sizes of two apple snail species available to, and consumed by, snail kites and limpkins were determined at sites with high and low densities of snail kite foraging perches. Sites with more perches had higher densities of snail kites, but not of limpkins. Both predators consumed prey larger than those available in the marshes, but habitat structure influenced the probability of consumption of different prey sizes. Limpkins consumed larger prey at low-density sites when compared with high-density sites, in contrast to other studies that found no size selection. Thus, limpkins can present prey-size selectivity but the presence of other predators can influence the range of prey sizes consumed. When a wider range of prey sizes is available, limpkins can select larger prey; alternatively, higher densities of other predators can result in higher foraging risk, favoring the capture of smaller, easier to handle prey. Snail kites incorporated smaller prey to their diet at low-density sites than at high-density ones, probably due to the higher costs of carrying large prey, differential age distribution, or lower foraging risks. Thus, habitat structure can influence consumer density and foraging patterns in complex ways, influencing predator-prey interactions in natural systems.

Tanaka, Marcel O.; Souza, Andréa L. T.; Módena, Érica S.



Influence of water hardness and sulfate on the acute toxicity of chloride to sensitive freshwater invertebrates.  


Total dissolved solids (TDS) represent the sum of all common ions (e.g., Na, K, Ca, Mg, chloride, sulfate, and bicarbonate) in freshwater. Currently, no federal water quality criteria exist for the protection of aquatic life for TDS, but because the constituents that constitute TDS are variable, the development of aquatic life criteria for specific ions is more practical than development of aquatic life criteria for TDS. Chloride is one such ion for which aquatic life criteria exist; however, the current aquatic life criteria dataset for chloride is more than 20 years old. Therefore, additional toxicity tests were conducted in the current study to confirm the acute toxicity of chloride to several potentially sensitive invertebrates: water flea (Ceriodaphnia dubia), fingernail clams (Sphaerium simile and Musculium transversum), snail (Gyraulus parvus), and worm (Tubifex tubifex), and determine the extent to which hardness and sulfate modify chloride toxicity. The results indicated a significant ameliorating effect of water hardness (calcium and magnesium) on chloride toxicity for all species tested except the snail; for example, the 48-h chloride median lethal concentration (LC50) for C. dubia at 50?mg/L hardness (977?mg Cl(-) /L) was half that at 800?mg/L hardness (1,836?mg Cl(-) /L). Conversely, sulfate over the range of 25 to 600?mg/L exerted a negligible effect on chloride toxicity to C. dubia. Rank order of LC50 values for chloride at a given water hardness was in the order (lowest to highest): S. simile?

Soucek, David J; Linton, Tyler K; Tarr, Christopher D; Dickinson, Amy; Wickramanayake, Nilesh; Delos, Charles G; Cruz, Luis A



Pathogenic agents in freshwater resources  

NASA Astrophysics Data System (ADS)

Numerous pathogenic agents have been found in freshwaters used as sources for water supplies, recreational bathing and irrigation. These agents include bacterial pathogens, enteric viruses, several protozoans and parasitic worms more common to tropical waters. Although infected humans are a major source of pathogens, farm animals (cattle, sheep, pigs), animal pets (dogs, cats) and wildlife serve as significant reservoirs and should not be ignored. The range of infected individuals within a given warm-blooded animal group (humans included) may range from 1 to 25%. Survival times for pathogens in the water environment may range from a few days to as much as a year (Ascaris, Taenia eggs), with infective dose levels varying from one viable cell for several primary pathogenic agents to many thousands of cells for a given opportunistic pathogen.As pathogen detection in water is complex and not readily incorporated into routine monitoring, a surrogate is necessary. In general, indicators of faecal contamination provide a positive correlation with intestinal pathogen occurrences only when appropriate sample volumes are examined by sensitive methodology.Pathways by which pathogens reach susceptible water users include ingestion of contaminated water, body contact with polluted recreational waters and consumption of salad crops irrigated by polluted freshwaters. Major contributors to the spread of various water-borne pathogens are sewage, polluted surface waters and stormwater runoff. All of these contributions are intensified during periods of major floods. Several water-borne case histories are cited as examples of breakdowns in public health protection related to water supply, recreational waters and the consumption of contaminated salad crops. In the long term, water resource management must focus on pollution prevention from point sources of waste discharges and the spread of pathogens in watershed stormwater runoff.

Geldreich, Edwin E.



Quantifying freshwater sustainability through multiscale mapping  

NASA Astrophysics Data System (ADS)

The issue of freshwater availability and sustainability within U.S. federal and state governments. For example, a recent report by the U.S. National Science and Technology Council (NSTC) urges the federal government to take new steps to understand freshwater sustainability in the United States [NSTC, 2004]. Although the report refers to ‘availability’—a concept that in the past has applied only to human needs and that implies that a resource may decline or be liquidated—the focus of the report is on ‘sustainability’ as commonly defined in the literature today. Sustainability requires that consumption will not cause a decline or liquidation of freshwater resources.

Kanivetsky, Roman; Shmagin, Boris


Helobdella nilae and Alboglossiphonia conjugata leeches as biological agents for snails control.  


The efficacy of leeches, as biological agents, in control of snail intermediate hosts of schistosomiasis (Bulinus truncatus, Biomphalaria alexandrina) and fascioliasis (Lymnaea natalensis) as well as their effect on the non-target snails Physa acuta, Melanioides tuberculata and Cleopatra bulimoides was evaluated. Two glossiphoniid snail leeches, Helobdella nilae and Alboglossiphonia conjugata were used. They destroyed egg masses and young snails more rapidly than adult ones. H. nilae showed a stronger destructive effect than A. conjugata. In a descending order, it preferred L. natalensis followed by B. truncatus, B. alexandrina, Ph. acuta, M. tuberculata and lastly C. bulimoides. But, A. conjugata preferred L. natalensis followed by B. truncatus, Ph. acuta, M. tuberculata, B. alexandrina and lastly C. bulimoides. The detailed diagnostic morphology and biology of the two leeches were given. PMID:19530628

Abd-Allah, Karim F; Saleh, Mohamed H; El-Hamshary, Azza M S; Negm-Eldin, Mohsen M; El-Fakahany, Amany F; Abdel-Tawab, Ahmed H; Abdel-Maboud, Amina I; Aly, Nagwa S M



Sciomyzid Flies: Another Approach to Biological Control of Snail-Borne Diseases.  

National Technical Information Service (NTIS)

Sciomyzid flies (Diptera) are predators and parasitoids of molluscs, most commonly of aquatic and terrestrial snail, and some species prey upon fingernail clams and slugs. The use of introduced species of sciomyzid flies to control populations of disease-...

L. Knutson



Pesticide Fact Sheet: Neu 1165M Slug and Snail Bait; Iron (Ferric) Phosphate.  

National Technical Information Service (NTIS)

Iron phosphate is to be used as the pesticidal active ingredient in a slug and snail bait formulation, on terrestrial, non-commercial food crops (vegetables, berries, fruit trees including citrus), domestic outdoor ornamental, domestic lawn and garden use...



A faunistic survey of cercariae isolated from lymnaeid snails in central areas of Mazandaran, Iran.  


The aim of this study was to elucidate the species diversity of larva trematodes in the Mazandaran Province, Northern Iran. In this cross-sectional study, a total of 3,266 lymnaeid snails from 3 species were collected from different parts of streams, swamps, rice fields and rivers in the central areas of Mazandaran Province (Sari, Neka, Qaemshahr and Savad-Koh cities), during April to September, 2008. The samples were tested by crushing and emerging methods. From the total of examined snails, 119 (3.6%) were found to be infected with the lymnaeid snails. Lymnaea gedrosiana were found to be infected with the Furcocercariae of Diplostomidae, Clinostomidae, Echinostomatidae and also cercariae of the Plagiorchiidae. The latest infection was found to be in L. palustris. The Mazandaran Province with its temperate climate is a suitable place for living of snails, particularly lymnaeidae, that could have a significant role as an intermediate host of diseases. PMID:20437681

Sharif, M; Daryani, A; Karimi, S A



Dynamic Chromatin Modification Sustains Epithelial-Mesenchymal Transition following Inducible Expression of Snail-1  

PubMed Central

SUMMARY Epithelial-mesenchymal transition (EMT) is thought to contribute to cancer metastasis, but its underlying mechanisms are not well understood. To define early steps in this cellular transformation, we analyzed human mammary epithelial cells with tightly regulated expression of Snail-1, a master regulator of EMT. After Snail-1 induction, epithelial markers were repressed within 6 hr, and mesenchymal genes were induced at 24 hr. Snail-1 binding to its target promoters was transient (6–48 hr) despite continued protein expression, and it was followed by both transient and long-lasting chromatin changes. Pharmacological inhibition of selected histone acetylation and demethylation pathways suppressed the induction as well as the maintenance of Snail-1-mediated EMT. Thus, EMT involves an epigenetic switch that may be prevented or reversed with the use of small-molecule inhibitors of chromatin modifiers.

Javaid, Sarah; Zhang, Jianmin; Anderssen, Endre; Black, Josh C.; Wittner, Ben S.; Tajima, Ken; Ting, David T.; Smolen, Gromoslaw A.; Zubrowski, Matthew; Desai, Rushil; Maheswaran, Shyamala; Ramaswamy, Sridhar; Whetstine, Johnathan R.; Haber, Daniel A.



Reciprocal Repression between Sox3 and Snail Transcription Factors Defines Embryonic Territories at Gastrulation  

PubMed Central

Summary In developing amniote embryos, the first epithelial-to-mesenchymal transition (EMT) occurs at gastrulation, when a subset of epiblast cells moves to the primitive streak and undergoes EMT to internalize and generate the mesoderm and the endoderm. We show that in the chick embryo this decision to internalize is mediated by reciprocal transcriptional repression of Snail2 and Sox3 factors. We also show that the relationship between Sox3 and Snail is conserved in the mouse embryo and in human cancer cells. In the embryo, Snail-expressing cells ingress at the primitive streak, whereas Sox3-positive cells, which are unable to ingress, ensure the formation of ectodermal derivatives. Thus, the subdivision of the early embryo into the two main territories, ectodermal and mesendodermal, is regulated by changes in cell behavior mediated by the antagonistic relationship between Sox3 and Snail transcription factors.

Acloque, Herve; Ocana, Oscar H.; Matheu, Ander; Rizzoti, Karine; Wise, Clare; Lovell-Badge, Robin; Nieto, M. Angela



Evolution of whole-body enantiomorphy in the tree snail genus Amphidromus  

PubMed Central

Diverse animals exhibit left–right asymmetry in development. However, no example of dimorphism for the left–right polarity of development (whole-body enantiomorphy) is known to persist within natural populations. In snails, whole-body enantiomorphs have repeatedly evolved as separate species. Within populations, however, snails are not expected to exhibit enantiomorphy, because of selection against the less common morph resulting from mating disadvantage. Here we present a unique example of evolutionarily stable whole-body enantiomorphy in snails. Our molecular phylogeny of South-east Asian tree snails in the genus Amphidromus indicates that enantiomorphy has likely persisted as the ancestral state over a million generations. Enantiomorphs have continuously coexisted in every population surveyed spanning a period of 10 years. Our results indicate that whole-body enantiomorphy is maintained within populations opposing the rule of directional asymmetry in animals. This study implicates the need for explicit approaches to disclosure of a maintenance mechanism and conservation of the genus.




Toxicity of imidazolium-based ionic liquids on Physa acuta and the snail antioxidant stress response.  


In the present study, the acute and developmental toxicities of imidazolium ionic liquids (ILs) with different alkyl chain lengths, as well as the antioxidant response and lipid peroxidation levels were evaluated in the snail, Physa acuta. Longer alkyl chains corresponded to increased IL toxicity in snails. Long-term IL exposure at lower concentrations inhibited snail growth and reproduction. We also found that IL inhibited the activities of superoxide dismutase (SOD) and glutathione S-transferase (GST), promoted the activity of catalase (CAT), and increased the glutathione content. However, SOD, GST, and CAT activities returned to control levels after 96 h of recovery. In addition, malondialdehyde levels were increased in treatment groups compared with the control and did not return to control levels even after a recovery period, indicating that ILs induced lipid peroxidation in snail viscera. These results suggest that oxidative stress and lipid peroxidation may be involved in the mechanism of toxicity for ILs. PMID:24497176

Ma, Junguo; Dong, Xiangyi; Fang, Qian; Li, Xiaoyu; Wang, Jianji



Results of White Garden Snail Environmental Monitoring Program. Spring and Fall 1987.  

National Technical Information Service (NTIS)

The white garden snail (Theba pisana Muller) is believed to have originated in the coastal areas of the Mediterranean and has invaded California on three separate occasions. Two infestations were successfully eradicated before 1970 and a third occurrence ...

B. Turner, M. Bisbiglia, N. Miller, K. Hefner, N. Carr



Biology and Control of White Snails (Mollusca: Helicidae), Introduced Pests in Australia.  

National Technical Information Service (NTIS)

Introduced white snails (Helicidae) such as Theba pisana, Cernuella virgata, Cochlicella acuta and C. barbara have long been regarded as significant agricultural pests in Australia. They feed upon foul crops and pastures. The native distributions of white...

G. H. Baker



Bioaccumulative and conchological assessment of heavy metal transfer in a soil-plant-snail food chain  

PubMed Central

Background Copper (Cu), zinc (Zn), cadmium (Cd), and lead (Pb) can pose serious threats to environmental health because they tend to bioaccumulate in terrestrial ecosystems. We investigated under field conditions the transfer of these heavy metals in a soil-plant-snail food chain in Banat area, Romania. The main goal of this paper was to assess the Roman snail (Helix pomatia) usefulness in environmental monitoring as bioindicator of heavy metal accumulation. Eight sampling sites, selected by different history of heavy metal (HM) exposure, were chosen to be sampled for soil, nettle leaves, and newly matured snails. This study also aimed to identify the putative effects of HM accumulation in the environment on phenotypic variability in selected shell features, which included shell height (SH), relative shell height (RSH), and whorl number (WN). Results Significantly higher amounts of HMs were accumulated in snail hepatopancreas and not in foot. Cu, Zn, and Cd have biomagnified in the snail body, particularly in the hepatopancreas. In contrast, Pb decreased when going up into the food chain. Zn, Cd, and Pb correlated highly with each other at all levels of the investigated food chain. Zn and Pb exhibited an effective soil–plant transfer, whereas in the snail body only foot Cu concentration was correlated with that in soil. There were significant differences among sampling sites for WN, SH, and RSH when compared with reference snails. WN was strongly correlated with Cd and Pb concentrations in nettle leaves but not with Cu and Zn. SH was independent of HM concentrations in soil, snail hepatopancreas, and foot. However, SH correlated negatively with nettle leaves concentrations for each HM except Cu. In contrast, RSH correlated significantly only with Pb concentration in hepatopancreas. Conclusions The snail hepatopancreas accumulates high amounts of HMs, and therefore, this organ can function as a reliable biomarker for tracking HM bioavailability in soil. Long-term exposure to HMs via contaminated food might influence the variability of shell traits in snail populations. Therefore, our results highlight the Roman snail (Helix pomatia) potential to be used in environmental monitoring studies as bioindicator of HM pollution.



Pesticide concentrations in snail kite eggs and nestlings in Florida  

USGS Publications Warehouse

From 1970-1977, unhatched snail kite eggs and young that were found dead at nests in Florida were analyzed by gas chromatography for residues of organochlorine pollutants. The 1970 and 1974 material showed measurable amounts of p,p'-DDE, p,p'-DDD, p,p'-DDT, and dieldrin. Dieldrin and polychlorinated biphenyl (PCB) residues were less than 0.1 ppm in the eggs and were detected in only one sample of muscle tissue at 0.11 ppm. Concentrations in ppm wet weight of p,p'-DDE, p,p' DDD, p,p'-DDT, dieldrin, and PCB for two samples of muscle and three of brain tissue (all 1977 material) were not detected at the limit of quantification (0.05 ppm).

Sykes, P.W., Jr.



Evening roosts of the snail kite in Florida  

USGS Publications Warehouse

A total of 36 roost sites of the Snail Kite (Rostrhamus sociabilis) were studied in southern Florida, of which four (11%) were used regularly for 6 or more years. Major roosts were also used as nesting sites. All roosts were in flooded marshes and 33 (91.6%) were in stands of coastal-plain willow. Population increase and the number of roosts were strongly correlated. The number of kites arriving at roosts before sunset was smaller than arriving after sunset (37.8:62.2%), and gray birds (adult and subadult males) generally went to roost earlier than brown birds (all females and immature males). Rites tended to go to roost earlier on cloudy days. Morning departure from roosts was over a much shorter time than arrivals in the afternoon. Ninety-two percent of the kite roosts were also used by other species of birds for roosting, 8 1% of which were eight species of herons.

Sykes, P.W., Jr.



Associative learning phenomena in the snail (Helix aspersa): conditioned inhibition.  


Two experiments using garden snails (Helix aspersa) showed conditioned inhibition using both retardation and summation tests. Conditioned inhibition is a procedure by which a stimulus becomes a predictor of the absence of a relevant event--the unconditioned stimulus (US). Typically, conditioned inhibition consists of pairings between an initially neutral conditioned stimulus, CS(2), and an effective excitatory conditioned stimulus, CS(1), in the absence of the US. Retardation and summation tests are required in order to confirm that CS(2) has acquired inhibitory properties. Conditioned inhibition has previously been found in invertebrates; however, these demonstrations did not use the retardation and summation tests required for an unambiguous demonstration of inhibition, allowing for alternative explanations. The implications of our results for the fields of comparative cognition and invertebrate physiological models of learning are discussed. PMID:21877176

Acebes, Félix; Solar, Patricia; Moris, Joaquín; Loy, Ignacio



Golden Apple Snail (Pomacea canaliculata Lamarck, 1819) in Sabah, Malaysia - Current Situation and Management Strategy  

Microsoft Academic Search

The paper reports the control operation of the golden apple snail in Sabah implemented by the Department of Agriculture following the outbreak of the pest in the 1990s. The snail was sighted in Keningau in 1992. Two years later it mushroomed to most of the rice-growing districts with a total infested area of about 5,000 ha. The control operation employed

Su Sin


Dysregulated expression of Snail and E-cadherin correlates with gastrointestinal stromal tumor metastasis.  


Snail, a zinc finger structure transcription inhibitory factor, has been reported to play an important role in the metastatic progression of several types of cancer. The aim of the study was to identify potential biomarkers for metastasis in gastrointestinal stromal tumors (GISTs) by examining the expression levels of Snail, E-cadherin, and Vimentin in GISTs and investigate their clinical significance. The protein expression of Snail, E-cadherin, and Vimentin in 74 GIST specimens was detected by immunohistochemical analysis, and the correlation between expression levels and clinicopathological data was analyzed. Snail, E-cadherin, and Vimentin were positively expressed in 51.4% (38/74), 32.4% (24/74), and 68.9% (51/74) of GIST tissue samples, respectively. Snail protein expression was significantly higher in GISTs with distant metastasis compared with GISTs without distant metastasis (P<0.05). E-cadherin expression level was significantly lower in cases of GIST with distant metastasis compared with those without distant metastasis (P<0.05), whereas the expression level of Vimentin did not significantly change according to clinical and pathological characteristics (all P>0.05). Snail expression was significantly negatively correlated with E-cadherin expression (r's=-0.276, P=0.017) but not with Vimentin expression (r's=0.041, P=0.728) in GISTs. High Snail expression and low E-cadherin expression were significantly correlated with metastasis in GISTs, and Snail, because of positive correlation, is potentially a biomarker of GIST with distant metastasis. PMID:24999604

Liu, Sheng; Liao, Guoqing; Ding, Jie; Ye, Ke; Zhang, Yi; Zeng, Liang; Chen, Senlin



Regulation of glycolysis in the land snail Oreohelix during estivation and artificial hypercapnia  

Microsoft Academic Search

Respiration rates, hemolymph acid-base variables, and metabolite levels were measured in the land snail Oreohelix during a brief period of estivation (4 days) and during exposure of non-estivating snails to elevated levels of ambient CO2 (34 and 58 mmHg). Respiration rate dropped during entry into estivation reflecting decreased glycolytic flux. Analyses of metabolite levels in foot muscle and digestive gland

Bernard B. Rees; Steven C. Hand



Polymorphism and Population Density in the African Land Snail, Limicolaria martensiana.  


In natural populations of the African land snail, Limicolaria martensiana, the degree of polymorphism in color and pattern may vary with the density of the population. This could occur because predators eat the snails selectively and use past experience as a guide in finding further prey. Hence contrasting color forms may be at an advantage in dense populations where predators would have ample opportunity to learn to recognize prey. PMID:17737105

Owen, D F



[Occurrence of Achatina fulica Bowdich, 1822 (Mollusca, Gastropoda) in Brazil: intermediate snail host of angiostrongyliasis].  


Achatina fulica, the intermediate snail host of angiostrongyliasis and also an agricultural pest, is being bred in Brazil for human consumption as "escargot". The snail has escaped from its artificial breeding sites and its dispersal in Itariri country, State of S. Paulo, is reported here for the first time. A. fulica is a transmitter of the rat lungworm Angiostrongylus cantonensis, nematode which causes meningoencephalic angiostrongyliasis; the risks of human contamination are commented on. PMID:9515269

Teles, H M; Vaz, J F; Fontes, L R; Domingos, M de F



Toxicity of Euphorbia milii Latex and Niclosamide to Snails and Nontarget Aquatic Species  

Microsoft Academic Search

The toxicity of Euphorbia milii molluscicidal latex and niclosamide (NCL) to target snails (Biomphalaria glabrata and Biomphalaria tenagophila) and nontarget aquatic organisms is evaluated. Planorbidae snails were killed by very low concentrations of lyophilized latex (48-h LC50, mg\\/L: B. glabrata, 0.12; B. tenagophila, 0.09; Helisoma duryi, 0.10). Latex was less toxic (48-h LC50 or EC50, mg\\/L) to oligochaeta (Tubifex tubifex,

Eduardo C. Oliveira-Filho; Francisco J. R. Paumgartten




Microsoft Academic Search

Our first objective was to find, which species of s piders overwinter in the land-snail shells in the x eric habitats of Southern Moravia (Czech Republic). During the winter 2008\\/2009 we collected 2448 empty land-snail shells from 31 xeric localities. Land-sn ail shells were represented by three species from t hree genera ( Cepea , Helix and Helicella ). Alltogether


The Giant Snail Achatina fulica as a Candidate Species for Advanced Bioregenerative Life Support Systems  

NASA Astrophysics Data System (ADS)

Maintenance of crew health is of paramount importance for long duration space missions. Weight loss, bone and calcium loss, increased exposure to radiation and oxidative stress are critical concerns that need to be alleviated. Rational nutrition is a resource for mitigating the influence of unfavorable conditions. The insufficiency of vegetarian diet has been examined by the Japanese, Chinese and U.S. developers of bioregenerative life support systems (BLSS). Hence, inclusion of animals such as silkworm in BLSS looks justified. The giant snail is currently under studying as a source of animal food and a species of reducing waste in BLSS. An experimental system to conduct cultivation of giant snail was developed. It was established that there are some reasons to use the giant snails in BLSS. It could be a source of delicious meat. A. fulica is capable of consuming a wide range of feedstuffs including plant residues. Cultivation of snail in the limited volume does not demand the big expenditures of labor. The production of crude edible biomass and protein of A. fulica was 60±15 g and 7±1.8 g respectively per 1 kg of consumed forage (fresh salad leaves, root and leafy tops of carrot). To satisfy daily animal protein needs (30-35 g) a crewman has to consume 260-300 g of snail meat. To produce such amount of snail protein it takes to use 4.3-5.0 kg of plant forage daily. The nutritional composition of A. fulica whole bodies (without shell) and a meal prepared in various ways was quantitatively determined. Protein, carbohydrate, fat acid and ash content percentages were different among samples prepared in various ways. The protein content was highest (68 %) in the dry sample washed with CH3 COOH solution. Taking into consideration the experimental results a conceptual configuration of BLSS with inclusion of giant snail was developed and mass flow rates between compartments were calculated. Keywords: animal food; protein; giant snail; BLSS; conceptual configuration.

Verbitskaya, Olga; Manukovsky, Nickolay; Kovalev, Vladimir


Comparative ORESTES-sampling of transcriptomes of immune-challenged Biomphalaria glabrata snails  

Microsoft Academic Search

The snail Biomphalaria glabrata (Gastropoda, Mollusca) is an important intermediate host for the human parasite Schistosoma mansoni (Digenea, Trematoda). Anti-pathogen responses of B. glabrata were studied towards a better understanding of snail immunity and host–parasite compatibility. Open reading frame ESTs (ORESTES) were sampled from different transcriptomes of M line strain B. glabrata, 12h post-challenge with Escherichia coli (Gram-negative), Micrococcus luteus

Ben Hanelt; Cheng Man Lun; Coen M Adema



Snail is a repressor of RKIP transcription in metastatic prostate cancer cells  

Microsoft Academic Search

Diminished expression of the metastasis suppressor protein RKIP was previously reported in a number of cancers. The underlying mechanism remains unknown. Here, we show that the expression of RKIP negatively correlates with that of Snail zinc-transcriptional repressor, a key modulator of normal and neoplastic epithelial–mesenchymal transition (EMT) program. With a combination of loss-of-function and gain-of-function approaches, we showed that Snail

S Beach; H Tang; A S Dhillon; E T Keller; W Kolch; K C Yeung



Enzootic Angiostrongylus cantonensis in Rats and Snails after an Outbreak of Human Eosinophilic Meningitis, Jamaica  

PubMed Central

After an outbreak in 2000 of eosinophilic meningitis in tourists to Jamaica, we looked for Angiostrongylus cantonensis in rats and snails on the island. Overall, 22% (24/109) of rats harbored adult worms, and 8% (4/48) of snails harbored A. cantonensis larvae. This report is the first of enzootic A. cantonensis infection in Jamaica, providing evidence that this parasite is likely to cause human cases of eosinophilic meningitis.

Lindo, John F.; Waugh, Cecilia; Hall, John; Cunningham-Myrie, Colette; Ashley, Deanna; Sullivan, James J.; Bishop, Henry S.; Robinson, David G.; Holtz, Timothy; Robinson, Ralph D.



Deterministic assembly of land snail communities according to species size and diet.  


1. We investigated whether coexisting snail species in 145 treeless fen communities in the Western Carpathian Mountains differed more in size and diet than would be expected by chance, as predicted for traits commonly associated with competition and differential resource acquisition under limiting similarity theory. 2. Contrary to expectations, coexisting snail species were no more different in body size than expected by chance under a null model. However, variation in body size played a significant role in structuring snail communities: coexisting snail species were significantly more similar with respect to body size. 3. We developed two new test statistics to expand our investigation of limiting similarity to include diet, a nominal trait. We tested whether communities of snails were characterized by a greater richness of diet, and whether different diets were represented more or less evenly within communities. Communities of snails were significantly less evenly distributed than expected by chance, with detritivores being over-represented relative to predatory strategies. 4. We also examined the effect of water pH and conductivity, herbaceous cover, and bryophyte and vascular plant richness, on these trends by examining how the effect size of our tests varied across these gradients. Convergence in species size increased with increasing habitat pH. Specifically, smaller snail species were over-represented in fen communities in general, and this effect was accentuated in increasingly calcareous fens. 5. Theory predicts that traits related strongly to environmental conditions are more likely to be convergent. Our findings support this suggestion, as small snail species have an advantage in tolerating freezing conditions over winter when refuges are limited. 6. These results add to the growing body of literature demonstrating that variation in body size and diet play a strong role in structuring communities, although frequently in ways not predicted by limiting similarity theory. Finally, our results increase our understanding of how species are assembled non-randomly into communities with respect to important traits. PMID:20345504

Schamp, Brandon; Horsák, Michal; Hájek, Michal



Acid phosphatase activity in the Indian apple snail, Pila globosa (Swainson), during aestivation and starvation stress  

Microsoft Academic Search

Acid phosphatase activity has been studied in hepatopancreas and foot tissues of the Indian apple snail,Pila globosa (Swainson), with reference to aestivation and starvation. The enzyme activity in the tissues of control snails is higher\\u000a in hepatopancreas, than in foot. The activity of acid phosphatase increased in hepatopancreas and decreased in foot during\\u000a starvation while it decreased in both the

P Aruna; C Sreeramulu Chetty; R Chandramohan Naidu; K S Swami



Effects of pollution on freshwater organisms  

SciTech Connect

A variety of sources were searched for data concerning the effects of pollution on freshwater plants, animals, and ecosystems. Pertinent data obtained since the last annual review are briefly summarized, tabulated by pollutant, and appropriately referenced.

Kline, E.R.; Mattson, V.R.; Pickering, Q.H.; Spehar, D.L.; Stephan, C.E.




EPA Science Inventory

An extensive literature review is presented which is concerned with the effects of pollutants (metals, pesticides, detergents, industrial wastes) on freshwater fish; chemical and biological methods for identifying and determining the effects of such pollutants; and the effects of...


Freshwater Biology and Pollution Ecology: Training Manual.  

National Technical Information Service (NTIS)

The manual includes specific teaching outlines on biology and identification of major plant and animal groups, effects of pollution, biological indices of pollution, and methods of collection and analysis of freshwater communities.

R. M. Sinclair



Endemic angiostrongyliasis in the Brazilian Amazon: natural parasitism of Angiostrongylus cantonensis in Rattus rattus and R. norvegicus, and sympatric giant African land snails, Achatina fulica.  


Angiostrongylus cantonensis, the rat lungworm, is one etiological agent of eosinophilic meningoencephalitis in humans. This zoonosis is frequently found in Asia and, more recently, in North America, Caribbean Island and northeastern of South America. Until now, research of A. cantonensis in southern, southeastern and northeastern regions of Brazil has been found natural infections only terrestrial and freshwater intermediate snail hosts (Achatina fulica, Sarasinula marginata, Subulina octona, Bradybaena similaris and Pomacea lineate). In this study, we examined the occurrence of helminthes in the synantropic rodents Rattus rattus and Rattus norvegicus in northern Brazil, focusing on the role of these species as vertebrate hosts of A. cantonensis and A. fulica as intermediate host have found natural. Thirty specimens of R. rattus and twelve of R. norvegicus were collected in the Guamá and Jurunas neighborhoods of the city of Belém, in the Brazilian state of Pará, of which almost 10% harbored adult worms in their pulmonary arteries. Sympatric A. fulica were found to be infected by L(3) larvae, which experimental infection confirmed to be A. cantonensis. Natural infection of snails and rodents with A. cantonensis was confirmed through morphological and morphometrical analyses of adults and larvae using light microscopy, scanning electron microscopy and molecular sequences of partial Cytochrome Oxidase subunit I. Phylogenetic analyses showed that A. cantonensis isolated from Pará, Brazil is similar to Japan isolate; once these specimens produced a single haplotype with high bootstrap support with Rio de Janeiro isolate. This study confirms that A. cantonensis is now endemic in northern Brazil, and that R. rattus and R. norvegicus act as natural definitive hosts, and A. fulica as the intermediate host of the parasite in this region. PMID:23072946

Moreira, V L C; Giese, E G; Melo, F T V; Simões, R O; Thiengo, S C; Maldonado, A; Santos, J N



Doxorubicin enhances Snail/LSD1-mediated PTEN suppression in a PARP1-dependent manner.  


The transcription factor Snail not only functions as a master regulator of epithelial-mesenchymal transition (EMT), but also mediates cell proliferation and survival. While previous studies have showed that Snail protects tumor cells from apoptosis through transcriptional repression of PTEN, the specific mechanism remains unclear. In this study, we demonstrated that Snail cooperates with LSD1 to repress PTEN in a PARP1-dependent manner. Upon doxorubicin treatment, Snail becomes tightly associated with PARP1 through its pADPr-binding motif and is subject to poly(ADP-ribosyl)ation. This modification can enhance Snail-LSD1 interaction and promote the recruitment of LSD1 to PTEN promoter, where LSD1 removes methylation on histone H3 lysine 4 for transcription repression. Furthermore, treatment of tumor cells with PARP1 inhibitor AZD2281 can compromise doxorubicin-induced PTEN suppression and enhance the inhibitory effect of doxorubicin. Together, we proposed a tentative drug-resistant mechanism through which tumor cells defend themselves against DNA damage-induced apoptosis. PARP1 inhibitors in combination with DNA damaging reagents might represent a promising treatment strategy targeting tumors with over-activated Snail and LSD1. PMID:24675890

Lin, Yiwei; Kang, Tiebang; Zhou, Binhua P



The collagen receptor discoidin domain receptor 2 stabilizes SNAIL1 to facilitate breast cancer metastasis.  


Increased stromal collagen deposition in human breast tumours correlates with metastases. We show that activation of the collagen I receptor DDR2 (discoidin domain receptor 2) regulates SNAIL1 stability by stimulating ERK2 activity, in a Src-dependent manner. Activated ERK2 directly phosphorylates SNAIL1, leading to SNAIL1 nuclear accumulation, reduced ubiquitylation and increased protein half-life. DDR2-mediated stabilization of SNAIL1 promotes breast cancer cell invasion and migration in vitro, and metastasis in vivo. DDR2 expression was observed in most human invasive ductal breast carcinomas studied, and was associated with nuclear SNAIL1 and absence of E-cadherin expression. We propose that DDR2 maintains SNAIL1 level and activity in tumour cells that have undergone epithelial-mesenchymal transition (EMT), thereby facilitating continued tumour cell invasion through collagen-I-rich extracellular matrices by sustaining the EMT phenotype. As such, DDR2 could be an RTK (receptor tyrosine kinase) target for the treatment of breast cancer metastasis. PMID:23644467

Zhang, Kun; Corsa, Callie A; Ponik, Suzanne M; Prior, Julie L; Piwnica-Worms, David; Eliceiri, Kevin W; Keely, Patricia J; Longmore, Gregory D



Effects of dietary exposure to forest pesticides on the brown garden snail Helix aspersa mueller  

SciTech Connect

Brown garden snails, Helix aspersa, were fed prepared diets with 12 pesticides used in forest spraying practices where endangered arboreal and terrestrial snails may be at risk. Acephate, atrazine, glyphosate, hexazinone, and picloram were not lethal at concentrations of 5,000 mg/kg in 14-day screening tests. The remaining seven pesticides, lethal to 13-100% of the tested snails at 5,000 mg/kg, were evaluated in 10-day definitive feeding tests. Azinphosmethyl (Guthion) and aminocarb were the most toxic, with 10-day LC50s of 188 and 313 mg/kg, respectively. Paraquat, trichlorfon and fenitrothion had 10-day LC50s of 659, 664, and 7,058 mg/kg respectively. Avoidance of pesticide-containing foods occurred, e.g., 10-day LC50s of >10,000 mg/kg for carbaryl and ethyl parathion. Significant descreases (p<0.05) in snail weight (total, shell-only, body-only) or shell diameter were accompanied by a significant decrease in the amount of food consumed/snail/day. Concentrations of pesticide in tissues were measured in snails exposed to atrazine and azinphosmethyl; there was no bioaccumulation. (Copyright (c) 1994 Springer-Verlag New York Inc.)

Schuytema, G.S.; Nebeker, A.V.; Griffis, W.L.



Snail plays an oncogenic role in glioblastoma by promoting epithelial mesenchymal transition  

PubMed Central

Background: The factors affecting glioblastoma progression are of great clinical importance since dismal outcomes have been observed for glioblastoma patients. The Snail gene is known to coordinate the regulation of tumor progression in diverse tumors through induction of epithelial mesenchymal transition (EMT); however, its role in glioblastoma is still uncertain. Therefore, we aimed to further define its role in vitro. Methods and results: The small interfering RNA (siRNA) technique was employed to knock down Snail expression in three glioblastoma cell lines (KNS42, U87, and U373). Specific inhibition of Snail expression increased E-cadherin expression but decreased vimentin expression in all cell lines. In addition, inhibition of the expression of Snail significantly reduced the proliferation, viability, invasion, and migration of glioblastoma cells as well as increased the number of cells in the G1 phase. Conclusions: Knockdown of Snail suppresses the proliferation, viability, migration, and invasion of cells as well as inhibits cell cycle progression by promoting EMT induction. The findings suggest that expression of this gene facilitates glioblastoma progression. Therefore, these results indicate the clinical significance of Snail for use as a potential therapeutic target for glioblastoma.

Myung, Jae Kyung; Choi, Seung Ah; Kim, Seung-Ki; Wang, Kyu-Chang; Park, Sung-Hye



Biological characteristics and control of intermediate snail host of Schistosoma japonicum.  


Except for imported cases, we have had no new Schistosoma japonicum infection in Japan since 1977. But there are still two habitats of the intermediate snail host: Oncomelania nosophora in the previous endemic areas of Kofu Basin and Obitsu. O. nosophora from Kofu Basin and Obitsu are susceptible to Chinese and Philippine strains of S. japonicum. The number of immigrants from current endemic areas in China or the Philippines is increasing. In order to prevent re-emerging of S. japonicum infections in Japan, we should continue monitoring on those existing snail hosts and investigate an adequate quarantine system. In Japan, elimination of schistosomiasis has been mainly accomplished by control of the snail host. As measures of snail control, cement-lining of ditches and chemical mollusciciding were most effective in Japan. But the cost of this joint program is too expensive compared with health budget in almost developing countries. In endemic areas of Japan, land reformation from paddy field to fruit farm was also effective. The intermediate snail host in the Philippines, Oncomelania quadrasi is much more aquatic than O. nosophora. For control of O. quadrasi, small drainage of the water and land reclamation from swampy field to rice-field were effective. Based on biological characteristics of Oncomelania spp., we can modify the past successful snail control program in Japan to be adapted ecologically and economically to each endemic area of developing countries. PMID:14665400

Ohmae, Hiroshi; Iwanaga, Yuzuru; Nara, Takeshi; Matsuda, Hajime; Yasuraoka, Kazuo



Correlation of Snail expression with histological grade and lymph node status in breast carcinomas.  


Snail is a zinc finger transcription factor that triggers the epithelial-mesenchymal transition (EMT) by directly repressing E-cadherin expression. Snail is required for mesoderm and neural crest formation during embryonic development and has recently been implicated in the EMT associated with tumour progression. In a series of human breast carcinomas, we have analysed the expression of Snail and that of molecules of the E-cadherin/catenin complexes. We have also correlated these data with the pathological features of the tumours. We show that Snail expression inversely correlates with the grade of differentiation of the tumours and that it is expressed in all the infiltrating ductal carcinomas (IDC) presenting lymph node metastases that were analysed. In addition, Snail is expressed in some dedifferentiated tumours with a negative nodal status. Considering that Snail is involved in the induction of the invasive and migratory phenotype in epithelial cells, these results indicate that it is also involved in the progression of breast ductal tumours, where it could additionally serve as a marker of the metastatic potential. PMID:12082640

Blanco, Maria J; Moreno-Bueno, Gema; Sarrio, David; Locascio, Annamaria; Cano, Amparo; Palacios, José; Nieto, M Angela



Bacterial diversity in different regions of gastrointestinal tract of Giant African snail (Achatina fulica).  


The gastrointestinal (GI) tract of invasive land snail Achatina fulica is known to harbor metabolically active bacterial communities. In this study, we assessed the bacterial diversity in the different regions of GI tract of Giant African snail, A. fulica by culture-independent and culture-dependent methods. Five 16S rRNA gene libraries from different regions of GI tract of active snails indicated that sequences affiliated to phylum ?-Proteobacteria dominated the esophagus, crop, intestine, and rectum libraries, whereas sequences affiliated to Tenericutes dominated the stomach library. On phylogenetic analysis, 30, 27, 9, 27, and 25 operational taxonomic units (OTUs) from esophagus, crop, stomach, intestine, and rectum libraries were identified, respectively. Estimations of the total bacterial diversity covered along with environmental cluster analysis showed highest bacterial diversity in the esophagus and lowest in the stomach. Thirty-three distinct bacterial isolates were obtained, which belonged to 12 genera of two major bacterial phyla namely ?-Proteobacteria and Firmicutes. Among these, Lactococcus lactis and Kurthia gibsonii were the dominant bacteria present in all GI tract regions. Quantitative real-time polymerase chain reaction (qPCR) analysis indicated significant differences in bacterial load in different GI tract regions of active and estivating snails. The difference in the bacterial load between the intestines of active and estivating snail was maximum. Principal component analysis (PCA) of terminal restriction fragment length polymorphism suggested that bacterial community structure changes only in intestine when snail enters estivation state. PMID:23233413

Pawar, Kiran D; Banskar, Sunil; Rane, Shailendra D; Charan, Shakti S; Kulkarni, Girish J; Sawant, Shailesh S; Ghate, Hemant V; Patole, Milind S; Shouche, Yogesh S



Intrinsic metabolic depression in cells isolated from the hepatopancreas of estivating snails.  


Many animals across the phylogenetic scale are routinely capable of depressing their metabolic rate to 5-15% of that at rest, remaining in this state sometimes for years. However, despite its widespread occurrence, the biochemical processes associated with metabolic depression remain obscure. We demonstrate here the development of an isolated cell model for the study of metabolic depression. The isolated cells from the hepatopancreas (digestive gland) of the land snail (Helix aspersa) are oxygen conformers; i.e., their rate of respiration depends on pO(2). Cells isolated from estivating snails show a stable metabolic depression to 30% of control (despite the long and invasive process of cell isolation) when metabolic rate at the physiological pH and pO(2) of the hemolymph of estivating snails is compared with metabolic rate at the physiological pH and pO(2) of the hemolymph of control snails. When the extrinsic effects of pH and pO(2) are excluded, the intrinsic metabolic depression of the cells from estivating snails is still to below 50% of control snails. The in vitro effect of pO(2) on metabolic rate is independent of pH and state (awake or estivating), but the effects of pH and state significantly interact. This suggests that pH and state change affect metabolic depression by similar mechanisms but that the metabolic depression by hypoxia involves a separate mechanism. PMID:10783155

Guppy, M; Reeves, D C; Bishop, T; Withers, P; Buckingham, J A; Brand, M D



Small mammals cause non-trophic effects on habitat and associated snails in a native system.  


Legacy effects occur when particular species or their interactions with others have long-lasting impacts, and they are increasingly recognized as important determinants of ecolog