WorldWideScience

Sample records for humped tree snail

  1. Survey of Endangered Tree Snails on Navy-Owned Land in Guam

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The objectives of this survey are to determine the location of Guam tree snails on Navy-owned lands in Guam and to identify the location of suitable habitat and...

  2. Population genetics and the effects of a severe bottleneck in an ex situ population of critically endangered Hawaiian tree snails.

    Science.gov (United States)

    Price, Melissa R; Hadfield, Michael G

    2014-01-01

    As wild populations decline, ex situ propagation provides a potential bank of genetic diversity and a hedge against extinction. These programs are unlikely to succeed if captive populations do not recover from the severe bottleneck imposed when they are founded with a limited number of individuals from remnant populations. In small captive populations allelic richness may be lost due to genetic drift, leading to a decline in fitness. Wild populations of the Hawaiian tree snail Achatinella lila, a hermaphroditic snail with a long life history, have declined precipitously due to introduced predators and other human impacts. A captive population initially thrived after its founding with seven snails, exceeding 600 captive individuals in 2009, but drastically declined in the last five years. Measures of fitness were examined from 2,018 captive snails that died between 1998 and 2012, and compared with genotypic data for six microsatellite loci from a subset of these deceased snails (N = 335), as well as live captive snails (N = 198) and wild snails (N = 92). Surprisingly, the inbreeding coefficient (Fis) declined over time in the captive population, and is now approaching values observed in the 2013 wild population, despite a significant decrease in allelic richness. However, adult annual survival and fecundity significantly declined in the second generation. These measures of fitness were positively correlated with heterozygosity. Snails with higher measures of heterozygosity had more offspring, and third generation offspring with higher measures of heterozygosity were more likely to reach maturity. These results highlight the importance of maintaining genetic diversity in captive populations, particularly those initiated with a small number of individuals from wild remnant populations. Genetic rescue may allow for an increase in genetic diversity in the captive population, as measures of heterozygosity and rarified allelic richness were higher in wild tree

  3. Origin and diversification of the endemic Hawaiian tree snails (Achatinellidae: Achatinellinae) based on molecular evidence.

    Science.gov (United States)

    Holland, Brenden S; Hadfield, Michael G

    2004-08-01

    Tree snails of the endemic subfamily Achatinellinae comprise a diverse and important component of the Hawaiian fauna. In recent decades anthropogenic impacts have resulted in devastating extinction rates in Hawaiian tree snails. To address long-standing biogeographic, systematic, and evolutionary questions we used cytochrome c oxidase subunit I (COI) gene sequences to reconstruct the phylogeny of 23 extant species spanning the range of the subfamily from five Hawaiian Islands. To investigate family-level relationships, data were analyzed from 11 terrestrial pulmonate families. Although nodal support for monophyly of the endemic Pacific family Achatinellidae and endemic Hawaiian subfamily Achatinellinae was strong, bifurcation order among deeper ingroup nodes was not well-supported by bootstrap resampling. We hypothesize that lineage extinction and rapidity of lineage formation may have rendered evolutionary reconstruction difficult using a standard phylogenetic approach. Use of an optimized evolutionary model, however, improved resolution and recovered three main clades. The diversification pattern inferred contradicts the traditional biogeographic hypothesis of a Maui origin of the achatinelline lineage. Taxa comprising the basal ingroup clade (Achatinella spp.) and seeding lineages for subsequent clades originated on O'ahu. Therefore it appears that the ancestral colonizing species of achatinellines arrived first on O'ahu from an unknown source, and that O'ahu is the Hawaiian origin of the subfamily. Species previously defined by morphological criteria were generally found to be phylogenetically distinct, and the overall colonization pattern follows the island-age progression rule with several instances of generic polyphyly and back-colonization.

  4. Moorean tree snail survival revisited: a multi-island genealogical perspective

    Directory of Open Access Journals (Sweden)

    Meyer Jean-Yves

    2009-08-01

    Full Text Available Abstract Background The mass extirpation of the island of Moorea's endemic partulid tree snail fauna, following the deliberate introduction of the alien predator Euglandina rosea, represents one of the highest profile conservation crises of the past thirty years. All of the island's partulids were thought to be extirpated by 1987, with five species persisting in zoos, but intensive field surveys have recently detected a number of surviving wild populations. We report here a mitochondrial (mt phylogenetic estimate of Moorean partulid wild and captive lineage survival calibrated with a reference museum collection that pre-dates the predator's introduction and that also includes a parallel dataset from the neighboring island of Tahiti. Results Although severe winnowing of Moorea's mt lineage diversity has occurred, seven of eight (six Partula; two Samoana partulid tip clades remain extant. The extinct mt clade occurred predominantly in the P. suturalis species complex and it represented a major component of Moorea's endemic partulid treespace. Extant Moorean mt clades exhibited a complex spectrum of persistence on Moorea, in captivity, and (in the form of five phylogenetically distinct sister lineages on Tahiti. Most notably, three Partula taxa, bearing two multi-island mt lineages, have survived decades of E. rosea predation on Moorea (P. taeniata and in the valleys of Tahiti (P. hyalina and P. clara. Their differential persistence was correlated with intrinsic attributes, such as taxonomy and mt lineages, rather than with their respective within-island distribution patterns. Conclusion Conservation efforts directed toward Moorean and Tahitian partulids have typically operated within a single island frame of reference, but our discovery of robust genealogical ties among survivors on both islands implies that a multi-island perspective is required. Understanding what genetic and/or ecological factors have enabled Partula taeniata, P. hyalina and P

  5. Consumption Habits and Humps

    DEFF Research Database (Denmark)

    Kraft, Holger; Munk, Claus; Seifried, Frank Thomas

    We show that the optimal consumption of an individual over the life cycle can have the hump shape (inverted U-shape) observed empirically if the preferences of the individual exhibit internal habit formation. In the absence of habit formation, an impatient individual would prefer a decreasing...... consumption path over life. However, because of habit formation, a high initial consumption would lead to high required consumption in the future. To cover the future required consumption, wealth is set aside, but the necessary amount decreases with age which allows consumption to increase in the early part...... of life. At some age, the impatience outweighs the habit concerns so that consumption starts to decrease. We derive the optimal consumption strategy in closed form, deduce sufficient conditions for the presence of a consumption hump, and characterize the age at which the hump occurs. Numerical examples...

  6. Consumption Habits and Humps

    DEFF Research Database (Denmark)

    Kraft, Holger; Munk, Claus; Seifried, Frank Thomas

    2017-01-01

    We show that the optimal consumption of an individual over the life cycle can have the hump shape (inverted U-shape) observed empirically if the preferences of the individual exhibit internal habit formation. In the absence of habit formation, an impatient individual would prefer a decreasing...... consumption path over life. However, because of habit formation, a high initial consumption would lead to high required consumption in the future. To cover the future required consumption, wealth is set aside, but the necessary amount decreases with age which allows consumption to increase in the early part...... of life. At some age, the impatience outweighs the habit concerns so that consumption starts to decrease. We derive the optimal consumption strategy in closed form, deduce sufficient conditions for the presence of a consumption hump, and characterize the age at which the hump occurs. Numerical examples...

  7. Snails home

    Science.gov (United States)

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

    2014-06-01

    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.

  8. Effectiveness of Motorcycle speed controlled by speed hump

    Directory of Open Access Journals (Sweden)

    Pornsiri Urapa

    2014-09-01

    Full Text Available Speed humps are one of the traffic calming measures widely accepted to control vehicle speed in the local road. Humps standards from the western countries are designed mainly for the passenger car. This study, therefore, aims to reveal the effectiveness of speed hump to control the motorcycle speed. This study observes the free-flow speed of the riders at the total of 20 speed bumps and humps. They are 0.3-14.8 meter in width and 5-18 centimeter in height. The results reveal that the 85th percentile speeds reduce 15-65 percent when crossing the speed bumps and speed humps. Besides, this study develops the speed model to predict the motorcycle mean speed and 85th percentile speed. It is found that speed humps follow the ITE standard can control motorcycle crossing speeds to be 25-30 Kph which are suitable to travel on the local road.

  9. Reversible algorithm of simulating multivariate densities with multi_hump

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    To simulate a multivariate density with multi_hump, Markov chainMonte Carlo method encounters the obstacle of escaping from one hump to another, since it usually takes extraordinately long time and then becomes practically impossible to perform. To overcome these difficulties, a reversible scheme to generate a Markov chain, in terms of which the simulated density may be successful in rather general cases of practically avoiding being trapped in local humps, was suggested.

  10. Double humps and radiation effects of SOI NMOSFET

    Institute of Scientific and Technical Information of China (English)

    Cui Jiangwei; Yu Xuefeng; Ren Diyuan; He Chengfa; Gao Bo; Li Ming; Lu Jian

    2011-01-01

    Radiation experiments have been carried out with a SOI NMOSFET. The behavior of double humps was studied under irradiation. The characterization of the hump was demonstrated. The results have shown that the shape of the hump changed along with the total dose and the reason for this was analyzed. In addition, the coupling effect of the back-gate transistor was more important for the main transistor than the parasitic transistor.

  11. Double humps and radiation effects of SOI NMOSFET

    Energy Technology Data Exchange (ETDEWEB)

    Cui Jiangwei; Yu Xuefeng; Ren Diyuan; He Chengfa; Gao Bo; Li Ming; Lu Jian, E-mail: cuijiangwei@sina.cn [Xinjiang Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Urumqi 830011 (China)

    2011-06-15

    Radiation experiments have been carried out with a SOI NMOSFET. The behavior of double humps was studied under irradiation. The characterization of the hump was demonstrated. The results have shown that the shape of the hump changed along with the total dose and the reason for this was analyzed. In addition, the coupling effect of the back-gate transistor was more important for the main transistor than the parasitic transistor. (semiconductor devices)

  12. Dorsal hump morphology in pink salmon (Oncorhynchus gorbuscha).

    Science.gov (United States)

    Susuki, Kenta; Ichimura, Masaki; Koshino, Yosuke; Kaeriyama, Masahide; Takagi, Yasuaki; Adachi, Shinji; Kudo, Hideaki

    2014-05-01

    Mature male Pacific salmon (Genus Oncorhynchus) develop a dorsal hump, as a secondary male sexual characteristic, during the spawning period. Previous gross anatomical studies have indicated that the dorsal humps of salmon are mainly composed of cartilaginous tissue (Davidson [1935] J Morphol 57:169-183.) However, the histological and biochemical characteristics of such humps are poorly understood. In this study, the detailed microstructures and components of the dorsal humps of pink salmon were analyzed using histochemical techniques and electrophoresis. In mature males, free interneural spines and neural spines were located in a line near to the median septum of the dorsal hump. No cartilaginous tissue was detected within the dorsal hump. Fibrous and mucous connective tissues were mainly found in three regions of the dorsal hump: i) the median septum, ii) the distal region, and iii) the crescent-shaped region. Both the median septum and distal region consisted of connective tissue with a high water content, which contained elastic fibers and hyaluronic acid. It was also demonstrated that the lipid content of the dorsal hump connective tissue was markedly decreased in the mature males compared with the immature and maturing males. Although, the crescent-shaped region of the hump consisted of connective tissue, it did not contain elastic fibers, hyaluronic acid, or lipids. In an ultrastructural examination, it was found that all of the connective tissues in the dorsal hump were composed of collagen fibers. Gel electrophoresis of collagen extracts from these tissues found that the collagen in the dorsal hump is composed of Type I collagen, as is the case in salmon skin. These results indicate that in male pink salmon the dorsal hump is formed as a result of an increase in the amount of connective tissue, rather than cartilage, and the growth of free interneural spines and neural spines.

  13. How the Camel Got His Hump

    Institute of Scientific and Technical Information of China (English)

    史习冬; Rudyard; Kipling

    2000-01-01

    Now this is the next tale,and it tellshow the Camel got his big hump~1.In the beginning of years,when theworld was so new and all,and the Animalswere just beginning to work for Man,therewas a Camel,and he lived in the middle of aHowling Desert because he did not want towork;and besides,he was a Howler himself.So he ate sticks and thorns~2 and tamarisks~3and milkweed and prickles~4,~*most scruciating idle~5;and when anybody spoke to

  14. DATA OF A HUMP YARDS AND FACTORS AFFECTING ON THEM

    Directory of Open Access Journals (Sweden)

    V. V. Zhuravel

    2010-04-01

    Full Text Available A kind of regression equations, which adequately describe the correlation between the error of braking of cuts, the slope of hump-yard tracks and the indices of hump yard work taking into account the influence of parameters of wagon stream processed, is determined.

  15. The ecology of shell shape difference in chirally dimorphic snails

    NARCIS (Netherlands)

    Schilthuizen, M.; Haase, M.; Koops, K.; Looijes, S.M.; Hendrikse, S.

    2012-01-01

    The Southeast-Asian tree snail subgenus Amphidromus s. str. (Gastropoda Pulmonata: Camaenidae) is unusual among all gastropods for its genetic antisymmetry: populations consist of stable mixtures of individuals with clockwise (dextral) and counterclockwise (sinistral) coiling directions. Although pr

  16. Radioactive fuel cask railcar humping study

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, L.T. (comp.)

    1978-01-01

    The response of two radioactive shipping casks due to railroad humping shocks was calculated using a spring-mass model. The two railcars for these casks had different coupling mechanisms and different tiedown arrangements. Humping tests had been performed on one of the railcars (ATMX-600) and the resulting shock spectra was used to adjust the spring-mass model to get matching results. One car (designed for cask shipment) was equipped with Freightmaster E-15 end of car coupler and had about /sup 1///sub 8/ in. free travel of the cask skid relative to the car. The other car (ATMX-600), equipped with Miner RF-333 draft gear, was designed for nuclear weapon shipment and adapted to nuclear waste shipment by fastening the casks to the floor. Both car frames were built by the same manufacturer and are very similar. The response of the casks was put in shock spectra format and a parametric study was performed with various cask weights. Additional studies were done on the effects of fastening the loose cask, and using the Freightmaster end of car coupler on the ATMX car. Half-sine response spectra were overlaid to include the natural frequency of the cask tiedown. The resulting shock amplitude was plotted against the cask weight for each car. The results show a constant acceleration level for all the weights on the car with hydraulic end-of-car coupler which results from constant force at that impact velocity. The cask acceleration can be reduced by fastening it to the car, rather than allowing it to move freely through some small space. This study also shows that the cask response can be optimized on railcars without hydraulic draft gear by adjusting the tiedown stiffness to keep the tiedown frequency different than car frequencies.

  17. Snail: More than EMT.

    Science.gov (United States)

    Wu, Yadi; Zhou, Binhua P

    2010-01-01

    Snail has moved into the fast lane of development and cancer biology with the epithelial-mesenchymal transition (EMT) emerging as one of the hottest topics in medical science within the past few years. Snail not only acts primarily as a key inducer of EMT but also plays an important role in cell survival, immune regulation and stem cell biology. This review focuses on the regulation of Snail and discusses the EMT-dependent and -independent functions of Snail in development and disease. Understanding the regulation and functional roles of Snail will shed new light on the mechanism of tumor progression and the development of novel cancer therapies.

  18. Trough and hump phenomenon in a kind of random system

    Energy Technology Data Exchange (ETDEWEB)

    Zhao Xiaopeng [Institute of Electrorheological Technology 141, Department of Applied Physics, Northwestern Polytechnical University, 710072 Xi' an (China)]. E-mail: xpzhao@nwpu.edu.cn; Huang Ming [Institute of Electrorheological Technology 141, Department of Applied Physics, Northwestern Polytechnical University, 710072 Xi' an (China); Tang Hong [Institute of Electrorheological Technology 141, Department of Applied Physics, Northwestern Polytechnical University, 710072 Xi' an (China); Yin Jianbo [Institute of Electrorheological Technology 141, Department of Applied Physics, Northwestern Polytechnical University, 710072 Xi' an (China); Guo Huilin [Institute of Electrorheological Technology 141, Department of Applied Physics, Northwestern Polytechnical University, 710072 Xi' an (China); Luo Chunrong [Institute of Electrorheological Technology 141, Department of Applied Physics, Northwestern Polytechnical University, 710072 Xi' an (China)

    2005-05-16

    A kind of random system applied simultaneously by the polarizing electric field and microwave field was investigated. The trough and hump phenomenon occurs simultaneously in the transmission spectra at frequency range of 8-12 GHz while microwave scanning the samples. The solid/fluid complex fluid samples are composed of BaTiO{sub 3}/silicon oil and microcapsule composite particle/silicon oil. It is seen that the troughs and humps are very similar with photonic band gaps and left-handed metamaterial transmission peaks, which respectively appear in the photonic crystal and left-handed metamaterial. Moreover, the high of troughs and humps also exhibit adjustable characteristics with respect to the external electric field. We think that the trough and hump phenomenon in random system may be originated from the interactions between local oscillation of systems and microwaves field.

  19. Snail: More than EMT

    OpenAIRE

    Wu, Yadi; Zhou, Binhua P.

    2010-01-01

    Snail has moved into the fast lane of development and cancer biology with the epithelial-mesenchymal transition (EMT) emerging as one of the hottest topics in medical science within the past few years. Snail not only acts primarily as a key inducer of EMT but also plays an important role in cell survival, immune regulation and stem cell biology. This review focuses on the regulation of Snail and discusses the EMT-dependent and -independent functions of Snail in development and disease. Unders...

  20. Trees

    Science.gov (United States)

    Al-Khaja, Nawal

    2007-01-01

    This is a thematic lesson plan for young learners about palm trees and the importance of taking care of them. The two part lesson teaches listening, reading and speaking skills. The lesson includes parts of a tree; the modal auxiliary, can; dialogues and a role play activity.

  1. A Matheuristic Approach to Integrate Humping and Pullout Sequencing Operations at Railroad Hump Yards

    DEFF Research Database (Denmark)

    Haahr, Jørgen Thorlund; Lusby, Richard Martin

    2016-01-01

    This article presents a novel matheuristic for solving the hump yard block-to-track assignment problem. This is an important problem arising in the railway freight industry and involves scheduling the transitions of a set of rail cars from a set of inbound trains to a set of outbound trains over...... a certain planning horizon. It was also the topic of the 2014 challenge organized by the Railway Applications Section of the Institute for Operations Research and the Management Sciences for which the proposed matheuristic was awarded first prize. Our approach decomposes the problem into three highly...... dependent subproblems. Optimization-based strategies are adopted for two of these, while the third is solved using a greedy heuristic. We demonstrate the efficiency of the complete framework on the official datasets, where solutions within 4–14% of a known lower bound (to a relaxed problem) are found. We...

  2. Effect of welding current and speed on occurrence of humping bead in high-speed GMAW

    Institute of Scientific and Technical Information of China (English)

    Chen Ji; Wu Chuansong

    2009-01-01

    The developed mathematical model of humping formation mechanism in high-speed gas metal arc welding (GMAW) is used to analyze the effects of welding current and welding speed on the occurrence of humping bead. It considers both the momentum and heat content of backward flowing molten jet inside weld pool. Three-dimensional geometry of weld pool, the spacing between two adjacent humps and hump height along humping weld bead are calculated under different levels of welding current and welding speed. It shows that wire feeding rate, power intensity and the moment of backward flowing molten jet are the major factors on humping bead formation.

  3. The Classroom Animal: Snails.

    Science.gov (United States)

    Kramer, David S.

    1985-01-01

    Points out that snails are interesting and easily-managed classroom animals. One advantage of this animal is that it requires no special attention over weekends or holidays. Background information, anatomy, reproduction, and feeding are discussed, along with suggestions for housing aquatic and/or land snails. (DH)

  4. Trees

    OpenAIRE

    Henri Epstein

    2016-01-01

    An algebraic formalism, developed with V. Glaser and R. Stora for the study of the generalized retarded functions of quantum field theory, is used to prove a factorization theorem which provides a complete description of the generalized retarded functions associated with any tree graph. Integrating over the variables associated to internal vertices to obtain the perturbative generalized retarded functions for interacting fields arising from such graphs is shown to be possible for a large cate...

  5. Trees

    OpenAIRE

    Epstein, Henri

    2016-01-01

    An algebraic formalism, developped with V. Glaser and R. Stora for the study of the generalized retarded functions of quantum field theory, is used to prove a factorization theorem which provides a complete description of the generalized retarded functions associated with any tree graph. Integrating over the variables associated to internal vertices to obtain the perturbative generalized retarded functions for interacting fields arising from such graphs is shown to be possible for a large cat...

  6. Trees

    CERN Document Server

    Epstein, Henri

    2016-01-01

    An algebraic formalism, developped with V.~Glaser and R.~Stora for the study of the generalized retarded functions of quantum field theory, is used to prove a factorization theorem which provides a complete description of the generalized retarded functions associated with any tree graph. Integrating over the variables associated to internal vertices to obtain the perturbative generalized retarded functions for interacting fields arising from such graphs is shown to be possible for a large category of space-times.

  7. Snail meat: Significance and consumption

    Directory of Open Access Journals (Sweden)

    Dragićević Olgica

    2005-01-01

    Full Text Available The consumption of snail meat goes back to prehistoric times. Different ancient nations had snails on their menu, but Helices culture as a productive activity was born as a Roman culture. Some of the most economically important edible species are: Helix aspersa (Mtiller Helixpomatia (Linne, Helix iucorum (Linne, Helix aperta (Born, Eobania vermiculata (Miiller. Together with its tasie, snail meat has several advantages over others: quite low lipid rate and calorie values versus rich mineral, essential amino acid and fatty acid content. The composition of snail meat is presented. In addition, the composition of different snail species and the part analyzed (pedal mass and visceral mass is presented. Also, the differences in composition according to the species (snail meat horse/chicken meat, beef, swine meat, fish meat are presented. The French are the world's leading consumers of snails. !n France snails come to market in a variety of ways. Estimated consumption of snails in France is around 40 000 tones/year. Total French imports account for 25% of world imports. France is also the leading exporter of prepared snails, mainly sold as preserved snails and prepared dishes. Snail imports have been much higher than exports (65 tones exported in 2002. vs. 2.700 tones imported. Despite the large consumption, only 3% of snails in France come from production (farming. Italy is in second place in the world consumption of snails, and Spain and Germany are in the third and fourth place. The development of snails consumption in Italy is followed with the same amount of production of snails in the whole biological circle. In 2001, from 24,700 tons, 9,350 tons (37.8% came from production, 6 00 tons (2.4% came from nature, and 14,750 tons (59.70% came from imports (frozen, fresh and prepared snails. In Serbia, at the beginning of 2005, we had over 400 registered farms for snail production.

  8. Modeling the Compton Hump Reverberation Observed in Active Galactic Nuclei

    Science.gov (United States)

    Hoormann, Janie; Beheshtipour, Banafsheh; Krawczynski, Henric

    2016-04-01

    In recent years, observations of the Iron K alpha reverberation in supermassive black holes have provided a new way to probe the inner accretion flow. Furthermore, a time lag between the direct coronal emission and the reprocessed emission forming the Compton Hump in AGN has been observed. In order to model this Compton Hump reverberation we performed general relativistic ray tracing studies of the accretion disk surrounding supermassive black holes, taking into account both the radial and angular dependence of the ionization parameter. We are able to model emission not only from a lamp-post corona but also implementing 3D corona geometries. Using these results we are able to model the observed data to gain additional insight into the geometry of the corona and the structure of the inner accretion disk.

  9. Distance between speed humps and pedestrian crossings: does it matter?

    Science.gov (United States)

    Johansson, Charlotta; Rosander, Peter; Leden, Lars

    2011-09-01

    Speed humps are a common physical measure installed at pedestrian crossings to reduce vehicle speeds therefore improve the safety and mobility of pedestrians at the crossing. The aim of this study was to determine whether variations in distance between speed humps and pedestrian crossings contribute differently to the safety and mobility of pedestrians and cyclists, especially children and the elderly, and if so, how. Three sites in Sweden were studied, where vehicle speed measurements and video filming at the site resulted in manually coded, road user behaviour of 1972 pedestrians and cyclists. Road user behaviour at three test sites and two comparison sites equipped with speed cushion at distances of about 5m and 10 m from the pedestrian crossing, i.e. about one or two car lengths, were studied. As vehicle speeds were somewhat lower at the pedestrian crossing when the distance between the speed cushion to the pedestrian crossing was greater, and there were positive aspects regarding the mobility of the pedestrians and cyclists, a greater distance of about 10 m or two car lengths between the hump and the pedestrian crossing is suggested. The present study only covers speed cushions, but the same distance is also regarded as important when installing other types of physical measures to reduce vehicle speed.

  10. Lichen endozoochory by snails.

    Science.gov (United States)

    Boch, Steffen; Prati, Daniel; Werth, Silke; Rüetschi, Jörg; Fischer, Markus

    2011-04-13

    Endozoochory plays a prominent role for the dispersal of seed plants. However, for most other plant taxa it is not known whether this mode of dispersal occurs at all. Among those other taxa, lichens as symbiotic associations of algae and fungi are peculiar as their successful dispersal requires movement of propagules that leaves the symbiosis functional. However, the potential for endozoochorous dispersal of lichen fragments has been completely overlooked. We fed sterile thalli of two foliose lichen species (Lobaria pulmonaria and Physcia adscendens) differing in habitat and air-quality requirements to nine snail species common in temperate Europe. We demonstrated morphologically that L. pulmonaria regenerated from 29.0% of all 379 fecal pellets, whereas P. adscendens regenerated from 40.9% of all 433 fecal pellets, showing that lichen fragments survived gut passage of all snail species. Moreover, molecular analysis of regenerated lichens confirmed the species identity for a subset of samples. Regeneration rates were higher for the generalist lichen species P. adscendens than for the specialist lichen species L. pulmonaria. Furthermore, lichen regeneration rates varied among snail species with higher rates after gut passage of heavier snail species. We suggest that gastropods generally grazing on lichen communities are important, but so far completely overlooked, as vectors for lichen dispersal. This opens new ecological perspectives and questions the traditional view of an entirely antagonistic relationship between gastropods and lichens.

  11. Improving the uniformity of RF-plasma density by a humped variable-gap spiral antenna

    Institute of Scientific and Technical Information of China (English)

    Xu Xu; Li Lin-Sen; Liu Feng; Zhou Qian-Hong; Liang Rong-Qing

    2008-01-01

    This paper develops a humped spiral antenna of top inductively coupled plasma with variable gap.Comparing with planar spiral antennas,it investigates the performance of humped spiral antennae in the calculated electromagnetic configurations and experimental results.It finds that the humped antenna has the improved uniformity of plasma density in the radial direction and the decreased electron temperature in the top inductively coupled plasma.By experimental and theoretical analyses,the plasma performance in the case of humped antennae is considered to be the combined results of the uniform electromagnetic configurations and the depressed capacitively coupling effect.

  12. Effect of habitat fragmentation on the schistosome-transmitting snail Oncomelania hupensis in a mountainous area of China.

    Science.gov (United States)

    Zhou, Yi-Biao; Yang, Mei-Xia; Yihuo, Wu-li; Liu, Gang-ming; Wang, Hai-yin; Wei, Jian-Guo; Jiang, Qing-Wu

    2011-04-01

    The effect of habitat fragmentation on schistosome-transmitting snails was assessed in an intervention village and a control village in Sichuan Province, China. Snail habitats were fragmented by environmental management. After 2 years, the proportions of quadrats with snails in the fragmented habitats decreased from 9.35% to 2.41% in one patch (c3) and from 12.20% to 6.57% in another patch (c12), whilst the proportions in habitats without fragmentation did not alter significantly. Mean snail density decreased from 0.246 to 0.063 snails/0.11 m2 in patch c3 and from 0.356 to 0.177 snails/0.11 m2 in patch c12, whilst the mean snail density of other patches did not alter significantly. Most snails from the same patch and/or its remaining patches after fragmentation clustered together in the phylogenetic tree, except for c1, c3 and its remaining patches (c5, c6 and c11). Snail habitats in the study zone exhibited visible fragmentation. Habitat fragmentation could decrease the snail population size and limit migration and dispersal of snails between patches. Copyright © 2010 Royal Society of Tropical Medicine and Hygiene. Published by Elsevier Ltd. All rights reserved.

  13. Snail Farming in Mature Rubber Plantation : 4. Studies on some Artificial Methods for Hatching of Snail Eggs and Protection of Young Snails during the Dry Season

    Directory of Open Access Journals (Sweden)

    Awah, AA.

    2001-01-01

    Full Text Available Three species of edible land snails of the moist forest belt of Nigeria, Archachatina marginata (Swainson, Archachatina papyracae (Pfeiffer and two phenotypes of Limicolaria species, sometimes named Limicolaria flammae (Muller and Limicolaria aurora (Jay, were used in the study of three methods of artificial hatching of snail eggs and their young ones for the study of two methods of reduction of mortality during the dry season. The results of egg laying performance by the three species of snails showed a significantly (p <0.01 higher population explosion in a given breeding season for L. flammae/aurora than for either A. papyracae or A. marginata. The results of artificial methods for hatching of snail eggs indicated that the use of plastic containers, plus either loose topsoil or cotton wool for the incubator mediums or the use of cellophane containers (bag plus loose topsoil for the incubator medium, were in each case suitable for adoption in successful hatching of snail eggs artificially. Leaking coagulation pans or wooden boxes, half filled with heat sterilized loose topsoil and placed on the ground under shade of rubber tree canopy as dry season protection methods for the snails, were again in each case effective in the reduction of field mortality of the young snails. The survival rates were 100 % ; 90.6 % and 71.2 % for youngs of A. marginata, A. papyracae and L. flammae/aurora respectively. The results further indicated that the dry season protection method deemed optimum for the youngs of A. marginata may not necessarily be optimum for the youngs of either A. papyracae orL. flammae/aurora.

  14. Hampton's hump in a patient with endocarditis and septic emboli.

    Science.gov (United States)

    Basso, Mark; Goldstein, Scott

    2016-05-01

    We discuss a case of a 20-year-old woman presenting with chest pain found to have a Hampton's hump on chest x-ray and corresponding wedge infarct on computed tomographic scan. Contrary to our suspicion that this febrile and tachycardic patient had a pulmonary embolism, she was later determined to have a septic embolus secondary to endocarditis. We highlight the difficulties in diagnosing certain cases of endocarditis in the emergency department, as well as the difficulties in distinguishing septic emboli from pulmonary emboli,especially with plain radiographs.

  15. Inquiry, Land Snails, and Environmental Factors.

    Science.gov (United States)

    Barrow, Lloyd H.; Krantz, Patrick D.

    2002-01-01

    Introduces land snails for use in inquiry-based science activities. Describes common characteristics and safety considerations while introducing students to land snails. Explains procedures for inquiry-based use of land snails in classrooms. (YDS)

  16. A DES Procedure Applied to a Wall-Mounted Hump

    Directory of Open Access Journals (Sweden)

    Radoslav Bozinoski

    2012-01-01

    Full Text Available This paper describes a detached-eddy simulation (DES for the flow over a wall-mounted hump. The Reynolds number based on the hump chord is Rec=9.36×105 with an in-let Mach number of 0.1. Solutions of the three-dimensional Reynolds-averaged Navier-Stokes (RANS procedure are obtained using the Wilcox k−ω equations. The DES results are obtained using the model presented by Bush and Mani and are compared with RANS solutions and experimental data from NASA's 2004 Computational Fluid Dynamics Validation on Synthetic Jets and Turbulent Separation Control Workshop. The DES procedure exhibited a three-dimensional flow structure in the wake, with a 13.65% shorter mean separation region compared to RANS and a mean reattachment length that is in good agreement with experimental measurements. DES predictions of the pressure coefficient in the separation region also exhibit good agreement with experiment and are more accurate than RANS predictions.

  17. Snail meat: Significance and consumption

    OpenAIRE

    Dragićević Olgica; Baltić Milan Ž.

    2005-01-01

    The consumption of snail meat goes back to prehistoric times. Different ancient nations had snails on their menu, but Helices culture as a productive activity was born as a Roman culture. Some of the most economically important edible species are: Helix aspersa (Mtiller) Helixpomatia (Linne), Helix iucorum (Linne), Helix aperta (Born), Eobania vermiculata (Miiller). Together with its tasie, snail meat has several advantages over others: quite low lipid rate and calorie values versus rich mine...

  18. Multi-hump solutions with small oscillations at infinity for stationary Swift-Hohenberg equation

    Science.gov (United States)

    Deng, Shengfu; Sun, Shu-Ming

    2017-02-01

    The paper considers the stationary Swift-Hohenberg equation cw-(∂x2+k02)2w-w3=0, where c  >  0 is a constant, k02=\\sqrt{c}-μ , and μ >0 is a small parameter. In this case, the linear operator has a pair of real eigenvalues and a pair of purely imaginary eigenvalues. It can be proved that the equation has homoclinic (or single hump) solutions approaching to periodic solutions as |x|\\to +∞ (called single-hump generalized homoclinic solutions). This paper provides the first rigorous proof of existence of homoclinic solutions with two humps which tend to periodic solutions at infinity (or two-hump generalized homoclinic solutions) by pasting two appropriate single-hump generalized homoclinic solutions together. The dynamical system approach is used to reformulate the problem into a classical dynamical system problem and then the solution is decomposed into a decaying part and an oscillatory part at positive infinity. By adjusting some free constants and modifying the single-hump generalized homoclinic solution near negative infinity, it is shown that the solution is reversible with respect to a point near negative infinity. Therefore, the translational invariant and reversibility properties of the system yield a two-hump generalized homoclinic solution. The method may be applied to prove the existence of 2 k -hump solutions for any positive integer k.

  19. Study of effect of a smooth hump on hypersonic boundary layer instability

    Science.gov (United States)

    Park, Donghun; Park, Seung O.

    2016-12-01

    Effect of a two-dimensional smooth hump on linear instability of hypersonic boundary layer is studied by using parabolized stability equations. Linear evolution of mode S over a hump is analyzed for Mach 4.5 and 5.92 flat plate and Mach 7.1 sharp cone boundary layers. Mean flow for stability analysis is obtained by solving the parabolized Navier-Stokes equations. Hump with height smaller than local boundary layer thickness is considered. The case of flat plate and sharp cone without the hump are also studied to provide comparable data. For flat plate boundary layers, destabilization and stabilization effect is confirmed for hump located at upstream and downstream of synchronization point, respectively. Results of parametric studies to examine the effect of hump height, location, etc., are also given. For sharp cone boundary layer, stabilization influence of hump is also identified for a specific range of frequency. Stabilization influence of hump on convective instability of mode S is found to be a possible cause of previous experimental observations of delaying transition in hypersonic boundary layers.

  20. The Lazy Snail

    Institute of Scientific and Technical Information of China (English)

    范丽萍

    2007-01-01

    @@ 一、故事内容 Once upon a time,there was a snail.He lived in a very poor place.There were some holes in the roof.In summer,it was very hot.If it rained outside,it rained inside,too.In winter,it was very cold.The winds came through the broken window.

  1. Characterization of mannanase-producing bacteria from sago hump

    Directory of Open Access Journals (Sweden)

    Sri Wahyuni

    2016-02-01

    Full Text Available Sago is a hardwood that can be used as source of fiber hemicellulose mannan. The abundance of mannanase waste is potential for the production of functional foods such as Manno oligosaccharides. Sago hump which is sago processing waste is very potential for growth of microorganisms because it contains lignin, cellulose, starch, minerals and vitamins that can be used as sources of carbon and energy for the growth. In this study, BLS.11-01 and BLS.11-02 isolates have been isolated and characterized from waste of sago hump. Locust bean gum was used as  substrate for measuring the activity of mannanase. Both isolates had optimum temperatures at 70°C and 60°C while they remain stable at temperature range of 30°C - 90°C. Mannanase from BLS.11-01 and BLS.11-02 had optimum pH at 6 and 7, respectively, and were also stable in wide pH range of 2-8. Co2+ was a mannanase activator for both isolates. Cu2+, Zn2+, Ni2+, Ca2+ and Fe2+ were  mannanase inhibitors for two isolates. Tween 20 (0.5% and 1.0% and NaCl (0.5% and 1.0% were chemical reagents that could enhance the activity of BLS.11-01 and BLS.11-02 mannanase isolates.  While tween 80 (0.5% and 1.0%, urea (0.5% and 1.0% and SDS (0.5% and 1.0% were chemical reagents that were not effective for both isolates mannanase activity

  2. An artificial perch to help Snail Kites handle an exotic Apple Snail

    Science.gov (United States)

    Pias, Kyle E.; Welch, Zach C.; Kitchens, Wiley M.

    2012-01-01

    In the United States, the Snail Kite (Rostrhamus sociabilis plumbeus) is a federally endangered species and restricted to the wetlands of south-central Florida where the current population numbers less than 1,500. The Snail Kite is an extreme dietary specialist, previously feeding almost exclusively on one species of snail, the Florida Apple Snail (Pomacea paludosa). Within the past decade, an exotic species of apple snail, the Island Apple Snail (Pomacea insularum), has become established on lakes in central Florida. Island Apple Snails are larger than the native Florida Apple Snails, and Snail Kites handle the exotic snails less efficiently. Juvenile Snail Kites, in particular, have lower daily energy balances while feeding on Island Apple Snails. An inexpensive, easy-to-construct platform was developed that would provide Snail Kites with a flat, stable surface on which to extract snails. The platform has the potential to reduce the difficulties Snail Kites experience when handling exotic snails, and may benefit the Snail Kite population as a whole. Initial observations indicate that Snail Kites use the platforms frequently, and snails extracted at the platforms are larger than snails extracted at other perches.

  3. Influence of backward flowing molten jet on humping bead formation during high-speed GMA welding

    Institute of Scientific and Technical Information of China (English)

    CHEN Ji; WU Chuansong

    2009-01-01

    Considering the inflttence of backward flowing molten jet observed by experiments, a new pool surface deformation formula and droplets heat content model are used to investigate the humping formation mechanism during high-speed gas metal arc (GMA) welding. Three-dimensional geometry of the humping bead is numerically simulated only if some extra force and heat acted at the rear part of weld pool are taken into account in the model. It has proved that both the momentum and heat content of backward flowing molten jet must be appropriately treated to quantitatively analyze the physical mechanism of the humping phenomenon.

  4. Hump-nosed viper bite: an important but under-recognized cause of systemic envenoming.

    Science.gov (United States)

    Shivanthan, Mitrakrishnan Chrishan; Yudhishdran, Jevon; Navinan, Rayno; Rajapakse, Senaka

    2014-01-01

    Hump-nosed viper bites are common in the Indian subcontinent. In the past, hump-nosed vipers (Hypnale species) were considered moderately venomous snakes whose bites result mainly in local envenoming. However, a variety of severe local effects, hemostatic dysfunction, microangiopathic hemolysis, kidney injury and death have been reported following envenoming by Hypnale species. We systematically reviewed the medical literature on the epidemiology, toxin profile, diagnosis, and clinical, laboratory and postmortem features of hump-nosed viper envenoming, and highlight the need for development of an effective antivenom.

  5. On the Hump-Shaped Output Effect of Monetary Policy in an Open Economy

    OpenAIRE

    Pierdzioch, Christian; Yener, Serkan

    2004-01-01

    Results of empirical research have revealed a characteristic hump-shaped effect of monetary policy shocks on output: the effect builds to a peak after several months and then gradually dies out. We analyze, in the context of a "new open economy macroeconomics" model, factors that imply a hump- shaped effect of a monetary policy shock on output. We find that a hump- shaped effect of output is likely to result if the model features a "catching up with the Joneses" effect, pricing-to-market beha...

  6. On the Hump-Shaped Output Effect of Monetary Policy in an Open Economy

    OpenAIRE

    Pierdzioch, Christian; Yener, Serkan

    2004-01-01

    Results of empirical research have revealed a characteristic hump-shaped effect of monetary policy shocks on output: the effect builds to a peak after several months and then gradually dies out. We analyze, in the context of a "new open economy macroeconomics" model, factors that imply a hump- shaped effect of a monetary policy shock on output. We find that a hump- shaped effect of output is likely to result if the model features a "catching up with the Joneses" effect, pricing-to-market beha...

  7. Design and implementation of speed humps: supplement to national guidelines for traffic calming

    CSIR Research Space (South Africa)

    Emslie, I

    1997-03-01

    Full Text Available This report presents guidelines to assist local authorities and traffic engineers with a uniform approach to the implementation of speed humps. It is recommended that these guidelines be read in conjunction with The National Guidelines for Traffic...

  8. A duplex kidney with dromedary hump showing altered hilar anatomy

    Directory of Open Access Journals (Sweden)

    Tallapaneni S

    2011-02-01

    Full Text Available A comprehensive knowledge of the wide range of variations of renal vasculature and renal pelvis is mandatory to the anatomists for a better understanding of the embryology. It remains as the key issue in determining the technical feasibility of various endourologic procedures and innumerable intervention techniques besides kidney retrievals for transplantation. In the present case the duplex kidney showed lobulations on the anterior surface just adjacent to the hilar region. The midlateral portion of the convex lateral border of the kidney showed a small focal bulge –dromedary hump. At the hilum reversed anterio-posterior disposition of renal vasculature with anteriorly placed renal artery which bifurcated into two upper and lower anterior segmental branches. The renal vein formed by large tributaries arising from the hilum running towards the inferior vena cava. The renal pelvis was most posteriorly placed which showed a double pelvis. The upper pelvis was seen arising behind the renal vein and the lower pelvis arising inferomedial to the lower anterior segmental artery.Both the pelvises were seen uniting medial to the lower part of hilum and continued as a single ureter which opened into the bladder. The thorough knowledge of these anatomical variations is necessary to avoid iatrogenic injuries and enable the surgeon and radiologists approach unusual situations with confidence rather than surprise.

  9. Tip Graft and Columellar Strut Using Dorsal Osseocartilaginous Hump

    Directory of Open Access Journals (Sweden)

    Mehdi Bakhshaee

    2010-09-01

    Full Text Available Background: Although, different grafts are used for nasal tipplasty in cases with under projected or ill defined tip, the selectionof a graft material, which provides sufficient amount oftissue with least donor site morbidity and low recipient sitecomplication is challenging. The objectives of the presentstudy were to examine the usefulness of cartilaginous dorsumas a proper material for tip graft, and to introduce the cartilaginousdorsum as an acceptable material for columellar strut.Methods: Fifty six (18 males and 38 females patients wereoperated for augmentation tip plasty and hump reduction from2004 to 2008. The tailored cartilaginous or ostecartilaginousdorsum was used as a tip graft or columellar strut in 35 and 21cases, respectively. The cartilaginous framework was exposedusing open or close rhinoplasty approach in 41 and 15 cases,respectively. The patients were followed for 12- 36 months.Cosmetic outcomes and patients' satisfaction were obtainedusing qualitative measures.Results: The percentage of patients with very improved, improved,unchanged or unacceptable aesthetic outcome were39.29%, 50%, 3.57% and 7.14%, respectively. Moreover, thepercentages of very satisfied, satisfied, indifferent and unsatisfiedpatients were 66%, 18%, 9%, and 7%, respectively.Conclusion: The procedure provides a well-defined nasal tipwith no evidence of bifidity, angularity, or cartilage graft visibilityand displacement. The use of dorsal osteocartilaginousgraft offers outstanding advantages including ease of harvest,mould, fix, and low resorption.

  10. Histogenesis of rumen in one-humped camel (Camelus dromedarius

    Directory of Open Access Journals (Sweden)

    E. Salimi Naghani* and L. Akradi1

    2012-05-01

    Full Text Available The aim of this study was to follow several sequence histological changes that occur during the histogenesis of the rumen in one-humped camel (Camelus dromedarius. Histogenesis study was carried out on 66 fetuses of camel from 50th day of gestation until birth (390 days, according to the most relevant histo-differentiation characteristics of the rumen in fetuses, these were divided into four groups: group I (5-24 cm crown-rump length (C-RL; 50-140 days; group II (24-30 cm C-RL; 140-160 days; group III (30-60 cm C-RL; 160-250 days; group IV (60-108 cm C-RL; 250-390 days. At 50 days, the rumen consisted of four layers: the epithelial layer, propria-submucosa, tunica muscularis and serosa. The epithelium glandular region was pseudostratified and in non-glandular region was stratified. The muscularis mucosa was observed incompletely from 140 days between lamina propria and submucosa in glandular region of the rumen to the birth day. The primary lymphatic nodules appeared in lamina propria of glandular region of the rumen at 160 days of gestation. The epithelium of the glandular region in rumen was formed by a simple columnar layer at 250 days. In all groups, the tunica muscularis layer of rumen was increased with ruminal development, gradually. The non-glandular region of rumen was formed by a stratified epithelium and number of these cells increased with ruminal development. The lymphatic nodules and muscularis mucosa in non-glandular region did not observe in all groups. The study observations revealed that non-glandular region of the rumen in the fetuses of camel are less precocious than the rumen of the domestic ruminants.

  11. Snail1 Expression Is Required for Sarcomagenesis

    Directory of Open Access Journals (Sweden)

    Lorena Alba-Castellón

    2014-05-01

    Full Text Available Snail1 transcriptional repressor is a major inducer of epithelial-to mesenchymal transition but is very limitedly expressed in adult animals. We have previously demonstrated that Snail1 is required for the maintenance of mesenchymal stem cells (MSCs, preventing their premature differentiation. Now, we show that Snail1 controls the tumorigenic properties of mesenchymal cells. Increased Snail1 expression provides tumorigenic capabilities to fibroblastic cells; on the contrary, Snail1 depletion decreases tumor growth. Genetic depletion of Snail1 in MSCs that are deficient in p53 tumor suppressor downregulates MSC markers and prevents the capability of these cells to originate sarcomas in immunodeficient SCID mice. Notably, an analysis of human sarcomas shows that, contrarily to epithelial tumors, these neoplasms display high Snail1 expression. This is particularly clear for undifferentiated tumors, which are associated with poor outcome. Together, our results indicate a role for Snail1 in the generation of sarcomas.

  12. Small Molecules in the Cone Snail Arsenal.

    Science.gov (United States)

    Neves, Jorge L B; Lin, Zhenjian; Imperial, Julita S; Antunes, Agostinho; Vasconcelos, Vitor; Olivera, Baldomero M; Schmidt, Eric W

    2015-10-16

    Cone snails are renowned for producing peptide-based venom, containing conopeptides and conotoxins, to capture their prey. A novel small-molecule guanine derivative with unprecedented features, genuanine, was isolated from the venom of two cone snail species. Genuanine causes paralysis in mice, indicating that small molecules and not just polypeptides may contribute to the activity of cone snail venom.

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

    Science.gov (United States)

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

    2012-05-01

    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.

  14. Consumption and Wage Humps in a Life-cycle Model with Education

    DEFF Research Database (Denmark)

    Kraft, Holger; Munk, Claus; Seifried, Frank Thomas

    The observed hump-shaped life-cycle pattern in individuals' consumption cannot be explained by the classical consumption-savings model. We explicitly solve a model with utility of both consumption and leisure and with educational decisions affecting future wages. We show optimal consumption is hu...

  15. Entropy production analysis for hump characteristics of a pump turbine model

    Science.gov (United States)

    Li, Deyou; Gong, Ruzhi; Wang, Hongjie; Xiang, Gaoming; Wei, Xianzhu; Qin, Daqing

    2016-07-01

    The hump characteristic is one of the main problems for the stable operation of pump turbines in pump mode. However, traditional methods cannot reflect directly the energy dissipation in the hump region. In this paper, 3D simulations are carried out using the SST k- ω turbulence model in pump mode under different guide vane openings. The numerical results agree with the experimental data. The entropy production theory is introduced to determine the flow losses in the whole passage, based on the numerical simulation. The variation of entropy production under different guide vane openings is presented. The results show that entropy production appears to be a wave, with peaks under different guide vane openings, which correspond to wave troughs in the external characteristic curves. Entropy production mainly happens in the runner, guide vanes and stay vanes for a pump turbine in pump mode. Finally, entropy production rate distribution in the runner, guide vanes and stay vanes is analyzed for four points under the 18 mm guide vane opening in the hump region. The analysis indicates that the losses of the runner and guide vanes lead to hump characteristics. In addition, the losses mainly occur in the runner inlet near the band and on the suction surface of the blades. In the guide vanes and stay vanes, the losses come from pressure surface of the guide vanes and the wake effects of the vanes. A new insight-entropy production analysis is carried out in this paper in order to find the causes of hump characteristics in a pump turbine, and it could provide some basic theoretical guidance for the loss analysis of hydraulic machinery.

  16. Snail1, Snail2, and E47 promote mammary epithelial branching morphogenesis

    OpenAIRE

    Lee, KangAe; Gjorevski, Nikolce; Boghaert, Eline; Radisky, Derek C.; Nelson, Celeste M.

    2011-01-01

    While the roles of Snail transcription factors in epithelial-mesenchymal transition (EMT) are well established, their functions in other morphogenetic processes are less understood. Here, Snail, Snail2, and E47 are shown to promote mammary gland branching morphogenesis, via activation of an EMT-like gene expression program.

  17. The Snail Takes a Walk with Me

    Institute of Scientific and Technical Information of China (English)

    王宜鸣; 乐伟国

    2008-01-01

    @@ 一、故事内容 I'm a snake. Today God gives me a job-I should take a walk with the snail. The snail moves too slowly. I have to scare him. He looks at me, full of shame. I am very angry. I pull him, and even kick.The snail cries, so he stops walking. I feel quite helpless.

  18. Snail modulates cell metabolism in MDCK cells

    Energy Technology Data Exchange (ETDEWEB)

    Haraguchi, Misako, E-mail: haraguci@m3.kufm.kagoshima-u.ac.jp [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); Iwasaki, Yasumasa [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); Fukushige, Tomoko [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); Izumo, Kimiko; Horiuchi, Masahisa [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); Furukawa, Tatsuhiko [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)

    2013-03-22

    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

  19. Edible Snails (Terrestrial) of Turkey

    OpenAIRE

    YILDIRIM, M. Zeki

    2004-01-01

    Edible species and their distribution in Turkey were studied. The absence of Helix pomatia, a species reported to occur in Turkey in resources in various disciplines, is mentioned, while 7 species of edible snails determined (Theba pisana, Eobania vermiculata, Cryptomphalus aspersus, Cantareus apertus, Helix asemnis, Helix cincta and Helix lucorum) are described in detail by means of morphology, distribution, systematical positions, and a key to the species is given. Additionally, problems ab...

  20. Celss nutrition system utilizing snails

    Science.gov (United States)

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

    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.

  1. Production of apple snail for space diet

    Science.gov (United States)

    Yamashita, Masamichi; Motoki, Shigeru; Space Agriculture Task Force, J.; Katayama, Naomi

    For food production in space at recycling bio-elements under closed environment, appropriate organisms should be chosen to drive the closed materials recycle loop. We propose a combination of green algae, photosynthetic protozoa, and aquatic plants such as Wolffia spp., for the primary producer fixing solar energy to chemical form in biomass, and apple snail, Pomacea bridgesii, which converts this biomass to animal meat. Because of high proliferation rate of green algae or protozoa compared to higher plants, and direct conversion of them to apple snail, the efficiency of food production in this combination is high, in terms of energy usage, space for rearing, and yield of edible biomass. Furthermore, green algae and apple snail can form a closed ecological system with exchanging bio-elements between two member, i.e. excreta of snail turn to fertilizer of algae, and grown algae become feed for snail. Since apple snail stays in water or on wet substrate, control of rearing is easy to make. Mass production technology of apple snail has been well established to utilize it as human food. Nutrients of apple snail are also listed in the standard tables of food composition in Japan. Nutrients for 100 g of apple snail canned in brine are energy 340 kJ, protein 16.5 g, lipid 1.0 g, cholesterol 240 mg, carbohydrate 0.8 g, Ca 400 mg, Fe 3.9 mg, Zn 1.5 mg. It is rich in minerals, especially Ca and Fe. Vitamin contents are quite low, but K 0.005 mg, B2 0.09 mg, B12 0.0006 mg, folate 0.001 mg, and E 0.6 mg. The amino acid score of apple snail could not be found in literature. Overall, apple snail provides rich protein and animal lipid such as cholesterol. It could be a good source of minerals. However, it does not give enough vitamin D and B12 , which are supposed to be supplemented by animal origin foods. In terms of acceptance in food culture, escargot is a gourmet menu in French dishes, and six to ten snail, roughly 50 g, are served for one person. Apple snail reaches to 30 g

  2. On some single-hump solutions of the short-pulse equation and their periodic generalizations

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Y.; Williams, F.; Whitaker, N. [Department of Mathematics and Statistics, University of Massachusetts, Amherst, MA 01003-4515 (United States); Kevrekidis, P.G., E-mail: kevrekid@gmail.co [Department of Mathematics and Statistics, University of Massachusetts, Amherst, MA 01003-4515 (United States); Saxena, A. [Center for Nonlinear Studies and Theoretical Division, MS B262, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Frantzeskakis, D.J. [Department of Physics, University of Athens, Panepistimiopolis, Zografos, Athens 15784 (Greece)

    2010-06-28

    In the present work, we consider both localized (e.g. peakon and breather) and extended waveforms (peakon-lattice and breather-lattice, as well as some periodic ones) that arise in the context of the short-pulse equation, as emanating from their sine-Gordon equation analogs. Through direct numerical simulations, we find that the most robust solution is the breather, although some of the single-hump variants of the periodic solutions may be preserved upon the time dynamics as well. Multi-peakon, as well as multi-breather and multi-hump profiles more generally are found to be subject to symmetry-breaking instabilities and are, thus, less robust.

  3. Nasal bone grafts from the removed hump used as overlay grafts to camouflage concave lateral crura.

    Science.gov (United States)

    Kubilay, Utku; Erdogdu, Suleyman; Sezen, Ozan Seymen

    2014-01-01

    Alar cartilage consists of a medial crus, middle crus and lateral crus. The lateral crus is an important aesthetic and functional structure of the nose. A 32-year-old male patient with concave lateral crura was operated by the authors. An open rhinoplasty with a dorsal approach to the septum is preferred. The nasal bones harvested from the hump, which is an autogenous graft trimmed and sutured on both concave lateral crura as an overlay camouflage grafts. Satisfactory result was achieved.

  4. Double-hump resonance structure of the cross sections for electron impact ionization of Ar5+

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Configuration-average distorted-wave calculations are carried out for electron-impact ionization of Ar5+. Both direct ionization and the indirect excitation autoionization processes are included in our calculations. Our theoretical values are in quite reasonable agreement with the experimental data. The indirect processes contribute up to 50% to the total ionization cross sections. The possible origin of double-hump resonance structure of the cross sections is demonstrated and the contributions of metastable states are also taken into account.

  5. Double-Humped Transverse Density Profile in Two-Dimensional Chute Flow with Rough Sidewalls

    Institute of Scientific and Technical Information of China (English)

    HU Guo-Qi; ZHANG Xun-Sheng; BAO De-Song; TANG Xiao-Wei

    2006-01-01

    @@ We study a two-dimensional granular rapid flow with rough sidewalls stuck with the same size discs by molecular dynamics simulation. A transient state of the double-humped density profile in the flowing process has been found, which appears and moves as travelling wave and is the same as the phenomena in the recent experiments [Acta Phys. Sin. 53 (2004) 3389 (in Chinese)].

  6. Production of a double-humped ion velocity distribution function in a single-ended Q-machine

    DEFF Research Database (Denmark)

    Andersen, S.A.; Jensen, Vagn Orla; Michelsen, Poul

    1970-01-01

    An experimental method of producing a double-humped velocity distribution function for the ions in a Q-machine is described. The method is based on charge exchange processes between neutral ceasium and the ions in a ceasium plasma.......An experimental method of producing a double-humped velocity distribution function for the ions in a Q-machine is described. The method is based on charge exchange processes between neutral ceasium and the ions in a ceasium plasma....

  7. Hump nosed viper bite inSri Lanka-descriptive observational study of 1543 cases

    Institute of Scientific and Technical Information of China (English)

    Wijewantha HS; Sellahewa KH

    2010-01-01

    Objective:To identify the clinical manifestations of hump nosed viper envenomation and to recognize the available treatment methods to prevent complications.Methods: Descriptive observational study involving a series of1 543 patients admitted with hump nosed viper bite to 5 major hospitals in Sri Lanka was conducted. Data collection was done consecutively during February1990 and February2008. ExceptHypnale, identification of the biting snake was made by the corresponding author after visual examination of the dead or live snakes, which were brought to hospital.Results: Sixty seven(4.34%) patients developed systemic effects and two (0.1%) patients died due to effects of envenomation or complications of treatment. Systemic effects varied from coagulopathy, nephropathy to some neurological manifestations. Fifty nine (3.8%) patients had only coagulopathy and they received either, intravenous isotonic saline to ensure adequate urine out put i.e.0.5 mL/kg /hour or15 mL/kg of fresh frozen plasma(FFP). None of the patients that had coagulopathy developed renal failure. Contamination of the sample by mildly venomous species ofHypnale may have contributed to the low incidence of systemic complications.Conclusions: It is likely that early hydration with normal saline orFFP can prevent acute renal failure. FFP showed a tendency for early correction of coagulopathy. Role of FFP in hump nosed viper envenomation is worth studying in randomized double blind controlled clinical trials.

  8. Sub-harmonic broadband humps and tip noise in low-speed ring fans.

    Science.gov (United States)

    Moreau, Stéphane; Sanjose, Marlène

    2016-01-01

    A joint experimental and numerical study has been achieved on a low-speed axial ring fan in clean inflow. Experimental evidence shows large periodic broadband humps at lower frequencies than the blade passing frequencies and harmonics even at design conditions. These sub-harmonic humps are also found to be sensitive to the fan process and consequently to its tip geometry. Softer fans yield more intense humps more shifted to lower frequencies with respect to the fan harmonics. Unsteady turbulent flow simulations of this ring fan mounted on a test plenum have been achieved by four different methods that have been validated by comparing with overall performances and detailed hot-wire velocity measurements in the wake. Noise predictions are either obtained directly or are obtained through Ffowcs Williams and Hawkings' analogy, and compared with narrowband and third-octave power spectra. All unsteady simulations correctly capture the low flow rates, the coherent vortex dynamics in the tip clearance and consequently the noise radiation dominated by the tip noise in the low- to mid-frequency range. Yet, only the scale-adaptive simulation and the lattice Boltzmann method simulations which can describe most of the turbulent structures accurately provide the proper spectral shape and levels, and consequently the overall sound power level.

  9. Reproductive ecology of the giant African snail in South Florida

    DEFF Research Database (Denmark)

    Roda, Amy; Nachman, Gøsta Støger; Weihman, Scott

    2016-01-01

    Giant African snail (Achatina fulica (Bowdich, 1822)), an important invasive snail, was recently found in South Florida, USA. An extensive eradication effort was initiated consisting of pesticide applications, debris removal and hand collections. We studied the reproduction capacity and population...... dynamics of snails collected from 22 populations for two years to help evaluate the likely success of the eradication program. A total of 23,890 snails, ranging from 25-131 mm, were measured, dissected and the number of eggs in each snail counted. Gravid snails ranged from 48-128 mm. Only 5% of snails had...... eggs, which were found year round. As the snails increased in size, they were more likely to include reproducing individuals. However, the percentage of gravid snails peaked when snails were approximately 90 mm. Although more prevalent, small (

  10. COMPLEX SIMULATION MODEL OF TRAIN BREAKING-UP PROCESS AT THE HUMPS

    Directory of Open Access Journals (Sweden)

    E. B. Demchenko

    2015-11-01

    Full Text Available Purpose. One of the priorities of station sorting complex functioning improvement is the breaking-up process energy consumptions reduction, namely: fuel consumption for train pushing and electric energy consumption for cut braking. In this regard, an effective solution of the problem of energy consumption reduction at breaking-up subsystem requires a comprehensive handling of train pushing and cut rolling down processes. At the same time, the analysis showed that the current task of pushing process improvement and cut rolling down effectiveness increase are solved separately. To solve this problem it is necessary to develop the complex simulation model of train breaking up process at humps. Methodology. Pushing process simulation was done based on adapted under the shunting conditions traction calculations. In addition, the features of shunting locomotives work at the humps were taken into account. In order to realize the current pushing mode the special algorithm of hump locomotive controlling, which along with the safety shunting operation requirements takes into account behavioral factors associated with engineer control actions was applied. This algorithm provides train smooth acceleration and further movement with speed, which is close to the set speed. Hump locomotive fuel consumptions were determined based on the amount of mechanical work performed by locomotive traction. Findings. The simulation model of train pushing process was developed and combined with existing cut rolling down model. Cut initial velocity is determined during simulation process. The obtained initial velocity is used for further cut rolling process modeling. In addition, the modeling resulted in sufficiently accurate determination of the fuel rates consumed for train breaking-up. Originality. The simulation model of train breaking-up process at the humps, which in contrast to the existing models allows reproducing complexly all the elements of this process in detail

  11. Rooks (Corvus frugilegus) dine on snails in Poland

    OpenAIRE

    MACIOROWSKI, Grzegorz; BURAL, Dobieslaw; GIERSZAL, Henryk; URBANSKA, Maria

    2014-01-01

    Evidence of breeding rooks feeding on Roman snails (Helix pomatia) and grove snails (Cepaea nemoralis) is presented. Shell dimensions of food remains and intact Roman snails collected in the study area were measured in order to estimate the size and shape of the snails collected by rooks in relation to the food available in the vicinity of the rookery. Smaller and rounder snail shells were collected by rooks than were available in the area around the colony, indicating that the rooks collecte...

  12. Modeling freshwater snail habitat suitability and areas of potential snail-borne disease transmission in Uganda

    Directory of Open Access Journals (Sweden)

    A.S. Stensgaard

    2006-11-01

    Full Text Available Geographic information system (GIS-based modeling of an intermediate host snail species’ environmental requirements using known occurrence records can provide estimates of its spatial distribution. When other data are lacking, this can be used as a rough spatial prediction of potential snail-borne disease transmission areas. Furthermore, knowledge of abiotic factors affecting intra-molluscan parasitic development can be used to make “masks” based on remotely sensed climatic data, and these can in turn be used to refine these predictions. We used data from a recent freshwater snail survey from Uganda, environmental data and the genetic algorithm for rule-set prediction (GARP to map the potential distribution of snail species known to act as intermediate hosts of several human and animal parasites. The results suggest that large areas of Uganda are suitable habitats for many of these snail species, indicating a large potential for disease transmission. The lack of parasitological data still makes it difficult to determine the magnitude of actual disease transmission, but the predicted snail distributions might be used as indicators of potential present and future risk areas. Some of the predicted snail distribution maps were furthermore combined with temperature masks delineating suitable temperature regimes of the parasites they host. This revealed the coinciding suitable areas for snail and parasite, but also areas suitable for host snails, but apparently not for the parasites. Assuming that the developed models correctly reflect areas suitable for transmission, the applied approach could prove useful for targeting control interventions.

  13. Status report on Fish Springs pond snail

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report provides a life history of the pond snail (Lymnaea Hinkleyia pilsbryi) at Fish Springs National Wildlife Refuge. The following information is included;...

  14. Freshwater snail consumption and angiostrongyliasis in Malaya.

    Science.gov (United States)

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

    1978-06-01

    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.

  15. CRCP-Prey choice of corallivorous snails

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The snail, Coralliophila abbreviata, is a common generalist corallivore and can be a major contributor to Caribbean acroporid tissue mortality. Considering the...

  16. Wall-Resolved Large-Eddy Simulation of Flow Separation Over NASA Wall-Mounted Hump

    Science.gov (United States)

    Uzun, Ali; Malik, Mujeeb R.

    2017-01-01

    This paper reports the findings from a study that applies wall-resolved large-eddy simulation to investigate flow separation over the NASA wall-mounted hump geometry. Despite its conceptually simple flow configuration, this benchmark problem has proven to be a challenging test case for various turbulence simulation methods that have attempted to predict flow separation arising from the adverse pressure gradient on the aft region of the hump. The momentum-thickness Reynolds number of the incoming boundary layer has a value that is near the upper limit achieved by recent direct numerical simulation and large-eddy simulation of incompressible turbulent boundary layers. The high Reynolds number of the problem necessitates a significant number of grid points for wall-resolved calculations. The present simulations show a significant improvement in the separation-bubble length prediction compared to Reynolds-Averaged Navier-Stokes calculations. The current simulations also provide good overall prediction of the skin-friction distribution, including the relaminarization observed over the front portion of the hump due to the strong favorable pressure gradient. We discuss a number of problems that were encountered during the course of this work and present possible solutions. A systematic study regarding the effect of domain span, subgrid-scale model, tunnel back pressure, upstream boundary layer conditions and grid refinement is performed. The predicted separation-bubble length is found to be sensitive to the span of the domain. Despite the large number of grid points used in the simulations, some differences between the predictions and experimental observations still exist (particularly for Reynolds stresses) in the case of the wide-span simulation, suggesting that additional grid resolution may be required.

  17. Haemolymph Components of Infected & None Infected Lymnaea Snails with Xiphidiocercariae

    Directory of Open Access Journals (Sweden)

    AA Saboor Yaraghi

    2011-03-01

    Full Text Available Background: In this study the haemolymph components of infected and none infected Lymnaea gedrosiana with xiphidiocercaria larvae was compared.Methods: Five hundred Fifty Lymnaea snails were collected from Ilam and Mazandaran prov­inces, Iran, during 2008-2009. The snails were transported to the lab at Tehran University of Medi­cal Sciences and their cercarial sheddings were studied. Haemolmyphs of snails were ex­tracted and cells were counted using haemocytometer and cell-surface carbohydrate were recog­nized by conjugated lectin (Lentil. Haemolymph protein concentrations were measured by Brad­ford protein assay method and soluble protein compositions were determined on sodium dodecyl sulphate polyacrilamide gel electrophoresis (SDS-PAGE.Result: From the 550 examined Lymnaea snails for cercariae, 27 snails were infected with xiphidiocer­cariae. Mean of haemolymph cells (haemocyte number were obtained 93480±2.43 (cells/ml for none infected snails (25 snail and 124560±2800 (cells/ml for infected snails (25 snail. Mannose carbohydrate was recognized on haemocyte of none infected and infected snails. Mean of protein concentration of haemolymph plasma was obtained as 1354 ± 160 μg/ml (1.4 mg/ml for none infected snails (25 snails and 1802±138 μg/ml (1.8 mg/ml for infected snail (25 snails. Comparing to none infected snails, the SDS-PAGE results of haemolymph plasma of infected snails, showed an extra protein band (70 kDa. The results showed a significant differ­ence between the amounts and the kinds of proteins in haemolymph of infected and none infected snails.Conclusion: This information might be useful to understand of parasite detection, adhesion, engulf­ment and antigen agglutination by snail.

  18. Design and implementation of an early warning system in vehicle for road speed control hump based on DSP and CCD

    Science.gov (United States)

    Yang, Shuyi; Zhu, Pingyu; He, Yanfang; Wang, Le

    2011-12-01

    Road speed control humps have the effect of strengthening transportation safety by preventing traffic accidents. However, vehicles will produce strong mechanical vibrations when crossing speed control humps at high speed. These vibrations affect the passenger's comfort and cause machine parts damage. Early warning systems in vehicles for road speed control humps were designed based on DSP and CCD sensors. The system uses a CCD camera to take the picture of the road speed control humps. The image information is processed and recognised by DSP. Then the related voice and image information is given quickly and accurately after the system processes. This information will remind the driver to prepare for slowing down in good time, it makes them safe and comfortable to pass over the road speed control hump.TMS320DM642DSP early warning system in vehicles was illustrated from three aspects of the image collection module, the image discernment module and the early warning export module. TMS320C6x soft develop flow was introduced in this paper. The system has strong practicality, rapid response and well directed-viewing.

  19. Exploring the source of the mid-level hump for intensity discrimination in quiet and the effects of noise.

    Science.gov (United States)

    Roverud, Elin; Strickland, Elizabeth A

    2015-03-01

    Intensity discrimination Weber fractions (WFs) measured for short, high-frequency tones in quiet are larger at mid levels than at lower or higher levels. The source of this "mid-level hump" is a matter of debate. One theory is that the mid-level hump reflects basilar-membrane compression, and that WFs decrease at higher levels due to spread-of-excitation cues. To test this theory, Experiment 1 measured the mid-level hump and growth-of-masking functions to estimate the basilar membrane input/output (I/O) function in the same listeners. Results showed the initial rise in WFs could be accounted for by the change in I/O function slope, but there was additional unexplained variability in WFs. Previously, Plack [(1998). J. Acoust. Soc. Am. 103(5), 2530-2538] showed that long-duration notched noise (NN) presented with the tone reduced the mid-level hump even with a temporal gap in the NN. Plack concluded the results were consistent with central profile analysis. However, simultaneous, forward, and backward NN were not examined separately, which may independently test peripheral and central mechanisms of the NN. Experiment 2 measured WFs at the mid-level hump in the presence of NN and narrowband noise of different durations and temporal positions relative to the tone. Results varied across subjects, but were consistent with more peripheral mechanisms.

  20. A Matheuristic Approach for Solving the Railroad Hump Yard Block-to-Track Assignment

    DEFF Research Database (Denmark)

    Haahr, Jørgen Thorlund; Lusby, Richard Martin

    This paper presents a novel matheuristic for solving the Hump Yard Block-to-Track Assignment Problem. This is an important problem rising in the railway freight industry and involves scheduling the transitions of a set of rail cars from a set of inbound trains to a set of outbound trains over...... a certain planning horizon. It was also the topic of the 2014 challenge organised by the Railway Applications Section of the Institute for Operations Research and the Management Sciences for which the proposed matheuristic was awarded first prize. Our approach decomposes the problem into three highly...

  1. The role of Snail in prostate cancer

    Science.gov (United States)

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

    2012-01-01

    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. PMID:23076049

  2. Epigenetic regulation of EMT: the Snail story.

    Science.gov (United States)

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

    2014-01-01

    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.

  3. Modeling freshwater snail habitat suitability and areas of potential snail-borne disease transmission in Uganda

    DEFF Research Database (Denmark)

    Stensgaard, Anna-Sofie; Jørgensen, Aslak; Kabatereine, N B

    2006-01-01

    Geographic information system (GIS-based modeling of an intermediate host snail species environmental requirements using known occurrence records can provide estimates of its spatial distribution. When other data are lacking, this can be used as a rough spatial prediction of potential snail......-borne disease transmission areas. Furthermore, knowledge of abiotic factors affecting intra-molluscan parasitic development can be used to make "masks" based on remotely sensed climatic data, and these can in turn be used to refine these predictions. We used data from a recent freshwater snail survey from...... Uganda, environmental data and the genetic algorithm for rule-set prediction (GARP) to map the potential distribution of snail species known to act as intermediate hosts of several human and animal parasites. The results suggest that large areas of Uganda are suitable habitats for many of these snail...

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

    Science.gov (United States)

    Tiwari, Farindra; Singh, D. K.

    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.

  5. Effect of droplet heat content distribution on humping formation in high speed GMAW

    Institute of Scientific and Technical Information of China (English)

    Ji CHEN; Chuansong WU

    2011-01-01

    The momentum of strong backward flowing melt jet and the thermal action from transferred droplets are two dominating factors affecting the formation of humping bead in high speed gas metal arc welding (GMAW).Appropriate describing the influence of the distribution mode of droplet heat content in the weld pool is essential to understand the physical mechanism of humping bead formation.Based on the experimental results,four kinds of droplet heat content distribution modes are proposed and employed to calculate the transient evolution of the temperature field and weld pool during high speed GMAW process.Through making comparison of predicted and measured weld bead dimensions,a suitable and adaptive distribution mode of droplet heat content is found,i.e.,droplet heat content is distributed in bottom layer of gouging region at the front of weld pool,and is averagely distributed in the whole layer at the rear of weld pool.The proposed mode is also validated by experimental observation of the weld pool images and measured by geometric dimensions of the weld bead.

  6. Biometric and Ultrasonographic Evaluation of the Testis of One-humped Camel (Camelus dromedarius

    Directory of Open Access Journals (Sweden)

    Riaz Hussain Pasha, Anas Sarwar Qureshi*, Laeeq Akbar Lodhi1 and Huma Jamil1

    2011-04-01

    Full Text Available Twenty four adult clinically healthy one-humped male camels (Camelus dromedarius were examined three times (beginning, mid and end in each season (winter, spring, summer and autumn for establishing the normal ultrasonic appearance and seasonal changes in the testicular parenchyma in the natural ecology of Punjab, Pakistan. The testes of each camel were scanned by using a B-mode real time ultrasound scanner fitted with a 7.5-MHz linear-array transducer. Scrotal biometry was done with the measuring tape during all the seasons of year. The tunics of the testes appeared as hyperechoic lines surrounding the homogenous, moderately echogenic parenchyma of the testis. The mediastinum testis was visualized as hyperechoic central line and a spot, in longitudinal and transverse sections, respectively. During winter season, the parenchyma was hyperechoic and mediastinum testis was seen as thin hyperechoic line. In spring, the echogenicity of parenchyma was moderate and mediastinum appeared relatively thick central hyperechoic line. In summer and autumn, less echoic parenchyma and thick band of mediastinum was recorded. Biometric studies showed significantly (P<0.01 higher scrotal length and width of the testis during winter and spring season as compared to summer and autumn. Present study revealed that the ultrasonic structure of camel testis resembles other mammals and season has an apparent effect on the testicular size and echogenicity of the testicular parenchyma in the one-humped camel.

  7. Molecular detection of Trypanosoma from one-humped camels slaughtered in Najafabad slaughterhouse

    Directory of Open Access Journals (Sweden)

    Samaneh Mehrabiyan

    2014-07-01

    Full Text Available   Introduction: Trypanosomes infect a variety of animals and cause fever, weakness, and lethargy, which lead to weight loss and anemia. In livestock the disease is fatal unless treated and causes serious economic losses. Present study was conducted to detection of Trypanosoma from one-humped camels slaughtered in Najafabad slaughterhouse .   Materials and methods: 278 blood samples were taken at three different time periods from one-humped camels slaughtered in Najafabad slaughterhouse and were tested by polymerase chain reaction (PCR to detection of Trypanosoma .   Results: The overall infection rate of Trypanosoma was 1.07%. Positive samples (3.8% only found in spring and summer, and no positive sample was found in fall and winter .   Discussion and conclusion : Fortunately, this may suggest that the prevalence of Trypanosoma is very low in the region. It is suggested to prevent the disease by preventing livestock suspected of carrying the disease from entering the country. If it is not possible to test imported healthy livestock by molecular assays, it is recommended that simple and rapid tests such as agglutination tests that do not need an expert be assessed .

  8. Epidemiological situation and molecular identification of cercarial stage in freshwater snails in Chao-Phraya Basin, Central Thailand

    Institute of Scientific and Technical Information of China (English)

    Sothorn Anucherngchai; Thanawan Tejangkura; Thapana Chontananarth

    2016-01-01

    Objective: To investigate the prevalence of cercarial trematode infection in snails and to examine the reconstruction of the phylogenetic relationship to explain the molecular system of cercarial stage trematodes to estimate the infection rate of in the definite host from the Chao-Phraya Basin.Methods: The snails were collected from 10 provinces of the Chao-Phraya Basin,Thailand by stratified sampling method. The snails were examined for cercarial infection by the crushing method. All DNA specimens were amplified with internal transcribed spacer 3(ITS3) and ITS4 primer based on PCR technique. The sequence data were aligned and used to reconstruct the phylogenetic tree by unweighted pair-group method with arithmetic means with 10 000 bootstraps.Results: The overall rate of cercarial infection was found to be 5.90%(122/2 067). Snails in the family Thiaridae were found to be in the highest prevalence followed by Lymnaeidae, Bithyniidae, Planorbidae, Viviparidae, and Ampullariidae, respectively, while the Buccinidae family(Clea helena) did not reveal any infections. The frequently found species of cercariae were parapleurolophocercous cercariae, cercariae and megarulous cercariae. The monophyletic tree separated the snails into five groups comprised of Heterophyidae, Strigeidae, Lecithodendriidae, Philophthalmidae and Echinostomatidae using the sequence of Angiostrongylus cantonensis as an out-group.Conclusions: This study was the first to report on cercarial infection in the Chao-Phraya Basin, Thailand. This revealed that a high variety of freshwater snails were infected by cercariae stage trematodes with a high prevalence. The sequence data of ITS2 can be used to investigate the phylogenetic relationships of trematodes at the family level and in each clade of different families separated by the definitive hosts.

  9. Socio-Economic Characteristics Of Snail Farmers, Consumers And ...

    African Journals Online (AJOL)

    A multi-stage sampling technique was employed to obtain a representative sample of ... between snail farmers' demographic characteristic and their production levels was ... only seven out of the twelve factors listed as limiting snail marketing.

  10. Evaluation of cis and trans fatty acid profiles in a Camel\\\\\\'s hump and meat consumed in Birjand and Nehbandan cities

    Directory of Open Access Journals (Sweden)

    Seyyed Javad Hosseini-Vashan

    2013-08-01

    Conclusion: Although there is no difference in the total amount of saturated and unsaturated fatty acids derived from the camel meat or hump in the two areas, the amount was less in the hump of the camel and also lower in Birjand. Therefore, it is probable that the camel's products in Birjand have a better quality regarding the incidence of atherosclerosis.

  11. Profound effects of population density on fitness-related traits in an invasive freshwater snail.

    Directory of Open Access Journals (Sweden)

    Nicholas Zachar

    Full Text Available Population density can profoundly influence fitness-related traits and population dynamics, and density dependence plays a key role in many prominent ecological and evolutionary hypotheses. Here, we evaluated how individual-level changes in population density affect growth rate and embryo production early in reproductive maturity in two different asexual lineages of Potamopyrgus antipodarum, a New Zealand freshwater snail that is an important model system for ecotoxicology and the evolution of sexual reproduction as well as a potentially destructive worldwide invader. We showed that population density had a major influence on individual growth rate and early-maturity embryo production, effects that were often apparent even when comparing treatments that differed in population density by only one individual. While individual growth rate generally decreased as population density increased, we detected a hump-shaped relationship between embryo production and density, with females from intermediate-density treatments producing the most embryos and females from low- and high-density treatments producing the fewest embryos. The two lineages responded similarly to the treatments, indicating that these effects of population density might apply more broadly across P. antipodarum. These results indicate that there are profound and complex relationships between population density, growth rate, and early-maturity embryo production in at least two lineages of this important model system, with potential implications for the study of invasive populations, research on the maintenance of sex, and approaches used in ecotoxicology.

  12. Eosinophilic meningitis risk associated with raw Ampullarium canaliculatus snails consumption.

    Science.gov (United States)

    Wang, Jiun-Jye; Chung, Li-Yu; Lin, Rong-Jyh; Lee, June-Der; Lin, Chaio-Wen; Yen, Chuan-Min

    2011-05-01

    In Taiwan, Angiostrongylus cantonensis infection has been reported in foreign laborers who had consumed raw Ampullarium canaliculatus snails. This study analyzed three foreign laborers who had contracted enzyme-linked immunosorbent assay-confirmed A cantonensis infection while working in Taiwan. All three workers had consumed either roasted snails or raw snails flavored with seasoning while drinking wine. This study investigated possible risk factors for A cantonensis, including naturally occurring A cantonensis in A canaliculatus snails, viability of third-stage A cantonensis larvae in raw seasoned snails and in roasted snails, infectivity of larvae, and effects of alcohol while consuming snails. Positive infection rates in snails from five different irrigation canals in south Taiwan ranged from 12.3% to 29.4% and the average number of motile larvae per infected snail ranged from 36 to 65. The number of motile and coiled larvae in snail meat after 120 minutes seasoning was 93 (27.7%) and 233 (69.3%), respectively. After 20 minutes of roasting, most larvae in the snail meat were dead. The infectivities of motile and coiled larvae from snail meat after 60 minutes seasoning were 53.2% and 33.2%, respectively, and those from snail meat after 5 minutes roasting were 33.2% and 7.0%, respectively. Eating Taiwan A canaliculatus snails raw is extremely risky given their high infection rates and infection intensities. Even after 120 minutes seasoning or after 20 minutes roasting, snail meat should be considered unsafe for human consumption. Finally, experimental rodent studies indicated that consuming alcohol while ingesting larvae does not significantly reduced infectivity.

  13. Exploring the source of the mid-level hump for intensity discrimination in quiet and the effects of noisea)

    Science.gov (United States)

    Roverud, Elin; Strickland, Elizabeth A.

    2015-01-01

    Intensity discrimination Weber fractions (WFs) measured for short, high-frequency tones in quiet are larger at mid levels than at lower or higher levels. The source of this “mid-level hump” is a matter of debate. One theory is that the mid-level hump reflects basilar-membrane compression, and that WFs decrease at higher levels due to spread-of-excitation cues. To test this theory, Experiment 1 measured the mid-level hump and growth-of-masking functions to estimate the basilar membrane input/output (I/O) function in the same listeners. Results showed the initial rise in WFs could be accounted for by the change in I/O function slope, but there was additional unexplained variability in WFs. Previously, Plack [(1998). J. Acoust. Soc. Am. 103(5), 2530–2538] showed that long-duration notched noise (NN) presented with the tone reduced the mid-level hump even with a temporal gap in the NN. Plack concluded the results were consistent with central profile analysis. However, simultaneous, forward, and backward NN were not examined separately, which may independently test peripheral and central mechanisms of the NN. Experiment 2 measured WFs at the mid-level hump in the presence of NN and narrowband noise of different durations and temporal positions relative to the tone. Results varied across subjects, but were consistent with more peripheral mechanisms. PMID:25786945

  14. The effects of ipsilateral, contralateral, and bilateral broadband noise on the mid-level hump in intensity discrimination.

    Science.gov (United States)

    Roverud, Elin; Strickland, Elizabeth A

    2015-11-01

    Previous psychoacoustical and physiological studies indicate that the medial olivocochlear reflex (MOCR), a bilateral, sound-evoked reflex, may lead to improved sound intensity discrimination in background noise. The MOCR can decrease the range of basilar-membrane compression and can counteract effects of neural adaptation from background noise. However, the contribution of these processes to intensity discrimination is not well understood. This study examined the effect of ipsilateral, contralateral, and bilateral noise on the "mid-level hump." The mid-level hump refers to intensity discrimination Weber fractions (WFs) measured for short-duration, high-frequency tones which are poorer at mid levels than at lower or higher levels. The mid-level hump WFs may reflect a limitation due to basilar-membrane compression, and thus may be decreased by the MOCR. The noise was either short (50 ms) or long (150 ms), with the long noise intended to elicit the sluggish MOCR. For a tone in quiet, mid-level hump WFs improved with ipsilateral noise for most listeners, but not with contralateral noise. For a tone in ipsilateral noise, WFs improved with contralateral noise for most listeners, but only when both noises were long. These results are consistent with MOCR-induced WF improvements, possibly via decreases in effects of compression and neural adaptation.

  15. Evaluation of the iPhone with an acrylic sleeve versus the Scoliometer for rib hump measurement in scoliosis

    Directory of Open Access Journals (Sweden)

    Izatt Maree T

    2012-07-01

    Full Text Available Abstract Background Vertebral rotation found in structural scoliosis contributes to trunkal asymmetry which is commonly measured with a simple Scoliometer device on a patient's thorax in the forward flexed position. The new generation of mobile 'smartphones' have an integrated accelerometer, making accurate angle measurement possible, which provides a potentially useful clinical tool for assessing rib hump deformity. This study aimed to compare rib hump angle measurements performed using a Smartphone and traditional Scoliometer on a set of plaster torsos representing the range of torsional deformities seen in clinical practice. Methods Nine observers measured the rib hump found on eight plaster torsos moulded from scoliosis patients with both a Scoliometer and an Apple iPhone on separate occasions. Each observer repeated the measurements at least a week after the original measurements, and were blinded to previous results. Intra-observer reliability and inter-observer reliability were analysed using the method of Bland and Altman and 95% confidence intervals were calculated. The Intra-Class Correlation Coefficients (ICC were calculated for repeated measurements of each of the eight plaster torso moulds by the nine observers. Results Mean absolute difference between pairs of iPhone/Scoliometer measurements was 2.1 degrees, with a small (1 degrees bias toward higher rib hump angles with the iPhone. 95% confidence intervals for intra-observer variability were +/- 1.8 degrees (Scoliometer and +/- 3.2 degrees (iPhone. 95% confidence intervals for inter-observer variability were +/- 4.9 degrees (iPhone and +/- 3.8 degrees (Scoliometer. The measurement errors and confidence intervals found were similar to or better than the range of previously published thoracic rib hump measurement studies. Conclusions The iPhone is a clinically equivalent rib hump measurement tool to the Scoliometer in spinal deformity patients. The novel use of plaster torsos as rib

  16. Agonist-induced hump current production in heterologously-expressed human α4β2-nicotinic acetylcholine receptors

    Institute of Scientific and Technical Information of China (English)

    Qiang LIE; Ke-wei YU; Yong-chang CHANG; Ronald J LUKAS; Jie WU

    2008-01-01

    Aim:To characterize the functional and pharmacological features of agonist-induced hump currents in human α4β2-nicotinic acetylcholine receptors (nAChR).Methods:Whole-cell and outside-out patch recordings were performed using human α4β2-nAChR heterologously expressed in stably-transfected,native nAChR-null subclonal human epithelial 1 (SH-EP1) cells.RT-PCR was used to test the mRNA expression of transfected nAChR.Homology modeling and ace-tylcholine (Ach) docking were applied to show the possible Ach-binding site in the channel pore.Results:The rapid exposure of 10 mmol/L Ach induced an inward current with a decline from peak to steady-state.However,after the re-moval of Ach,an additional inward current,called "hump" current,reoccurred.The ability of agonists to produce these hump currents cannot be easily explained based on drug size,charge,acute potency,or actions as full or partial agonists.Hump currents were associated with a rebound increase in whole-cell conductance,and they had voltage dependence-like peak currents induced by agonist action.Hump currents blocked by the α4β2-nAChR antagonist dihydro-β-erythroidine were reduced when α4β2-nAChR were desensitized,and were more pronounced in the absence of external Ca2+.Outside-out single-channel recordings demon-strated that compared to 1 μmol/L nicotine,100 μmol/L nicotine reduced channel current amplitude,shortened the channel mean open time,and prolonged the channel mean closed time,supporting an agonist-induced open-channel block before hump current production.A docking model also simulated the agonist-binding site in the channel pore.Conclusion:These results support the hypoth-esis that hump currents reflect a rapid release of agonists from the α4β2-nAChR channel pore and a rapid recovery from desensitized α4β2-nAChR.

  17. Reproduction in the one humped camel (Camelus dromedarius in semi arid Nigeria

    Directory of Open Access Journals (Sweden)

    M.A. Umaru

    2013-02-01

    Full Text Available This review examines the one humped camel (Camelus dromedarius a considerable number of the dromedary about 50,000 is found in the semi-arid part of Northern Nigeria. Apart from the wide use of the camel as a draught animal the camel now serve as a source of milk, meat and hide in this region, these notes examines the anatomical basis of reproduction, pregnancy, and its diagnosis, fertility, and the application of modern  techniques in camel reproduction. Different techniques and equipments are now being employed for explicit study of the reproductive processes in the camel. Transrectal ultrasaonographic scanning machine is now being used to study ovulation pattern and timing, video endoscopic hysteroscopy is another technique employed to study various aspects of the camel conceptus. Techniques like oestrous synchronization, super ovulation, semen collection artificial insemination, embryo recovery and transfer are all used in the study of camel.

  18. Application of Sweeping Jet Actuators on the NASA Hump Model and Comparison with CFDVAL2004 Experiments

    Science.gov (United States)

    Koklu, Mehti

    2017-01-01

    Flow separation control over a wall-mounted hump model was studied experimentally to assess the performance of sweeping jet actuators. Results were compared to that of the 2004 CFD validation experiment (CFDVAL2004), which examined flow separation control with steady suction and unsteady zero-net-mass-flow actuators. Comparisons were carried out at low and high amplitude excitations. In addition to the active flow control methods, a passive flow control method (i.e., vortex generator) was used to complement the dataset. Steady/unsteady surface pressure measurements and surface oilflow visualization were used in the performance assessment of the actuators. The results indicated that the sweeping jet actuators are more effective than the steady suction and unsteady zero-net-mass-flow actuators. For the same momentum coefficient, the sweeping jet actuators produced more flow acceleration upstream of separation, more pressure recovery downstream, and consistently a smaller separation bubble.

  19. Wet-Induced Fabrication of Heterogeneous Hump-on-String Fibers

    Directory of Open Access Journals (Sweden)

    Cheng Song

    2015-07-01

    Full Text Available Inspired by the high adhesiveness of the electrospun fiber, we propose a method to fabricate multi-scale heterogeneous hump-on-string fiber via the adsorption of nanoparticles, the NPCTi which is the hydrolysate of titanium tetrachloride (TiCl4 and the nanoparticles containing Al (NPCAl which is produced by the hydrolysis of Trimethylaluminium (TMA, Al(CH33. The water collection efficiency of the fibers can be easily controlled via changing not only the size of the beads but also the ratio of the Ti and Al. In addition, we introduce a computational fluid dynamics (CFD simulation to show the pressure distribution of on the surface of the fibers, which gives another explanation regarding the high water collection efficiency.

  20. Transient distal renal tubular acidosis following hump nosed viper bite: Two cases from Sri Lanka

    Directory of Open Access Journals (Sweden)

    Ranga M Weerakkody

    2016-01-01

    Full Text Available Hump-nosed viper (Hypnale hypnale; HNV is one of the six major snake species in Sri Lanka that cause envenomation. Nephrotoxicity, coagulopathy, and neurotoxicity are wellrecognized features of its envenomation. Type 4 renal tubular acidosis (RTA4 has only once been described previously in this condition, and we report two further cases. Two patients aged 53 and 51 presented following HNV bites with acute kidney injury and microangiopathic hemolytic anemia. Both underwent multiple cycles of hemodialysis until the polyuric phase was reached. Despite polyuria, both patients developed resistant hyperkalemia that needed further hemodialysis. The urinary pH, arterial pH, delta ratio, and transtubular potassium gradient confirmed RTA4. HNV venom has been shown to damage the proximal convoluted tubules in animal studies, but not the distal convoluted tubule, and hence the mechanism of our observation in these two patients is unclear. Unexplained hyperkalemia in recovery phase of HNV bite should raise suspicions of RTA4.

  1. Statement on the identity of apple snails

    DEFF Research Database (Denmark)

    Baker, R.; Candresse, T.; Dormannsné Simon, E.

    2012-01-01

    Following a request by the European Commission, EFSA’s Panel on Plant Health was asked to deliver a statement to clarify the current scientific knowledge regarding the identity of the apple snails in the context of the evaluation of the pest risk analysis prepared by the Spanish Ministry of Envir......Following a request by the European Commission, EFSA’s Panel on Plant Health was asked to deliver a statement to clarify the current scientific knowledge regarding the identity of the apple snails in the context of the evaluation of the pest risk analysis prepared by the Spanish Ministry...

  2. Statement on the identity of apple snails

    DEFF Research Database (Denmark)

    Baker, R.; Candresse, T.; Dormannsné Simon, E.

    2012-01-01

    Following a request by the European Commission, EFSA’s Panel on Plant Health was asked to deliver a statement to clarify the current scientific knowledge regarding the identity of the apple snails in the context of the evaluation of the pest risk analysis prepared by the Spanish Ministry of Envir......Following a request by the European Commission, EFSA’s Panel on Plant Health was asked to deliver a statement to clarify the current scientific knowledge regarding the identity of the apple snails in the context of the evaluation of the pest risk analysis prepared by the Spanish Ministry...

  3. Is there any support for the humped-back model in some steppe and semi steppe regions of Iran?

    Science.gov (United States)

    Ashouri, Parvaneh; Jalili, Adel; Danehkar, Afshin; Chahouki, Mohammad Ali Zare; Hamzeh'ee, Behnam

    2016-05-01

    One of the famous theories in ecology is the humped-back model (HBM) which explains that habitats with intermediate productivity and disturbance support the most species. Most studies on HBM patterns have been conducted for herbaceous species. Knowledge about this theory in arid and semi-arid communities is still weak, especially with severe environments and disturbances containing woody plants. In this study, an analysis is presented on species richness-productivity relationship along a gradient of disturbance and stress in some steppe and semi steppe rangelands in Iran. A nonlinear curve-fitting approach was used that fitted a three-parameter Gaussian curve between species richness and productivity across 180 plots (1 m2). Mitchell-Olds and Shaw 's test (MOS) was used to assess the significance of the humped-back curve. Data were collected from six rangelands, including all life forms of species (grasses, forbs and small shrubs) with litter. Fitted Gaussian curve showed a positive trend between productivity and species richness across a decreasing gradient of disturbance in which species richness was increased. Maximum values for species richness correspond to values of plant productivity in undisturbed sites with a moderate stress. The MOS test showed a significant positive trend in the curve which means that the observed shape in the species richness-productivity relationship covers the mechanisms located in low to medium productivity in the left-hand side of the humped-back model. In other words, this research did not detect a full unimodal curve. This is because of less productivity in the arid and semi-arid ecosystems with abiotic stress. However, there was a partial support for the humped-back model in this study. Hence, more studies to test the existence of a humped-back model in such areas, would be required to reveal all aspects of this relationship.

  4. Application of Failure Mode and Effect Analysis (FMEA) and cause and effect analysis in conjunction with ISO 22000 to a snails (Helix aspersa) processing plant; A case study.

    Science.gov (United States)

    Arvanitoyannis, Ioannis S; Varzakas, Theodoros H

    2009-08-01

    Failure Mode and Effect Analysis (FMEA) has been applied for the risk assessment of snails manufacturing. A tentative approach of FMEA application to the snails industry was attempted in conjunction with ISO 22000. Preliminary Hazard Analysis was used to analyze and predict the occurring failure modes in a food chain system (snails processing plant), based on the functions, characteristics, and/or interactions of the ingredients or the processes, upon which the system depends. Critical Control points have been identified and implemented in the cause and effect diagram (also known as Ishikawa, tree diagram, and fishbone diagram). In this work a comparison of ISO22000 analysis with HACCP is carried out over snails processing and packaging. However, the main emphasis was put on the quantification of risk assessment by determining the RPN per identified processing hazard. Sterilization of tins, bioaccumulation of heavy metals, packaging of shells and poisonous mushrooms, were the processes identified as the ones with the highest RPN (280, 240, 147, 144, respectively) and corrective actions were undertaken. Following the application of corrective actions, a second calculation of RPN values was carried out leading to considerably lower values (below the upper acceptable limit of 130). It is noteworthy that the application of Ishikawa (Cause and Effect or Tree diagram) led to converging results thus corroborating the validity of conclusions derived from risk assessment and FMEA. Therefore, the incorporation of FMEA analysis within the ISO22000 system of a snails processing industry is considered imperative.

  5. Snail promotes an invasive phenotype in lung carcinoma

    Directory of Open Access Journals (Sweden)

    Merikallio Heta

    2012-11-01

    Full Text Available Abstract Background Snail is a transcriptional factor which is known to influence the epitheliomesenchymal transition (EMT by regulating adhesion proteins such as E-cadherin and claudins as well as matrix metalloproteases (MMP. Methods To evaluate the functional importance of snail, a transciptional factor involved in EMT in lung tumors, we investigated its expression in a large set of lung carcinomas by immunohistochemistry. Expression of snail and effects of snail knockdown was studied in cell lines. Results Nuclear snail expression was seen in 21% of cases this being strongest in small cell lung carcinomas (SCLC. There was significantly greater snail expression in SCLC compared to squamous cell or adenocarcinoma. Positive snail expression was associated with poor survival in the whole material and separately in squamous cell and adenocarcinomas. In Cox regression analysis, snail expression showed an independent prognostic value in all of these groups. In several cell lines knockdown of snail reduced invasion in both matrigel assay and in the myoma tissue model for invasion. The influence of snail knockdown on claudin expression was cell type specific. Snail knockdown in these cell lines modified the expression of MMP2 and MMP9 but did not influence the activation of these MMPs to any significant degree. Conclusions The results show that snail plays an important role in the invasive characteristics of lung carcinoma influencing the survival of the patients. Snail knockdown might thus be one option for targeted molecular therapy in lung cancer. Snail knockdown influenced the expression of claudins individually in a cell-line dependent manner but did not influence MMP expressions or activations to any significant degree.

  6. Calcium, snails, and birds: a case study

    Directory of Open Access Journals (Sweden)

    R. Mänd

    2000-10-01

    Full Text Available Recent studies have shown that wild birds breeding in acidified areas have difficulties with obtaining sufficient calcium for their eggshells, and that the cause of it is the shortage of land snails. Many birds have to search for Ca-rich snail shells on a daily basis during egg production. Molluscs depend on litter calcium, which has decreased due to acidification of the environment. Calcium limitation may be a widespread phenomenon also in non-acidified, naturally Ca-poor areas. The problem is that while in the latter areas the time for development of specific adaptations may have been sufficient, then in acidified areas, on the contrary, calcium shortage is a recent phenomenon. Therefore, since the extent of calcium limitation in non-acidified areas is hard to derive from observational data, experimental approach is needed. We provide experimental evidence that specific calcium deficit does affect reproductive traits also in the birds breeding in naturally base-poor habitats. Our study was conducted in a heterogeneous woodland area in Estonia containing deciduous forest patches as well as base-poor pine forest with low snail abundance. Ca supplementation, using snail shell and chicken eggshell fragments, was carried out for pied flycatchers and great tits. Extra calcium affected positively several reproductive traits like egg volume and eggshell thickness, start of breeding, and fledglings’ parameters. The negative relationship between calcium availability and lay-date suggests that birds adjust their breeding tactics to conditions of Ca deficiency, for example, by postponing laying.

  7. Spatial analysis of snail distribution in Jiangning county

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhi-ying; ZHOU Yun; XU De-zhong; SUN Zhi-dong; ZHOU Xiao-nong; GONG Zi-li

    2002-01-01

    Objective: To explore the spatial distribution of oncomelenia snails in Jiangning County. Methods:Cluster analysis and the Spatial Scan Statistics were performed based on the density of alive-snails in habitats and its rate infected by the S. Japonicum. Results: Although areas of snail habitats and density of the alivesnails in marshland in 2000 are higher significantly than that in mountain areas in Jiangning County, the numbers of habitats in mountain are more than that in marshland and they distributed sporadically. The snail habitats were classified into 4 in marshlands and 3 classes in mountain areas respectively in cluster analysis.Although they are mainly the one with low density of alive and infected snails, we should alert that there are also some habitats with high snail density and infection rate, which is important for the transmission of schistosomia. The analysis of Spatial Scan Statistics detected 2 significant spatial aggregations for alive-snail in marshland and 4 in mountain areas respectively with p-values less than 0. 01. There are also 2 significant spatial aggregations for infected snails in marshland. Conclusion.. The significant spatial aggregations for alivesnails and infected snails indicated that there are some factors in the habitats suitable for the survival of snails and the transmission of schistosomia.

  8. Multidimensionally constrained relativistic mean-field study of triple-humped barriers in actinides

    Science.gov (United States)

    Zhao, Jie; Lu, Bing-Nan; Vretenar, Dario; Zhao, En-Guang; Zhou, Shan-Gui

    2015-01-01

    Background: Potential energy surfaces (PES's) of actinide nuclei are characterized by a two-humped barrier structure. At large deformations beyond the second barrier, the occurrence of a third barrier was predicted by macroscopic-microscopic model calculations in the 1970s, but contradictory results were later reported by a number of studies that used different methods. Purpose: Triple-humped barriers in actinide nuclei are investigated in the framework of covariant density functional theory (CDFT). Methods: Calculations are performed using the multidimensionally constrained relativistic mean field (MDC-RMF) model, with the nonlinear point-coupling functional PC-PK1 and the density-dependent meson exchange functional DD-ME2 in the particle-hole channel. Pairing correlations are treated in the BCS approximation with a separable pairing force of finite range. Results: Two-dimensional PES's of 226,228,230,232Th and 232,235,236,238U are mapped and the third minima on these surfaces are located. Then one-dimensional potential energy curves along the fission path are analyzed in detail and the energies of the second barrier, the third minimum, and the third barrier are determined. The functional DD-ME2 predicts the occurrence of a third barrier in all Th nuclei and 238U . The third minima in 230 ,232Th are very shallow, whereas those in 226 ,228Th and 238U are quite prominent. With the functional PC-PK1 a third barrier is found only in 226 ,228 ,230Th . Single-nucleon levels around the Fermi surface are analyzed in 226Th, and it is found that the formation of the third minimum is mainly due to the Z =90 proton energy gap at β20≈1.5 and β30≈0.7 . Conclusions: The possible occurrence of a third barrier on the PES's of actinide nuclei depends on the effective interaction used in multidimensional CDFT calculations. More pronounced minima are predicted by the DD-ME2 functional, as compared to the functional PC-PK1. The depth of the third well in Th isotopes decreases

  9. Prognostic significance of snail expression in hilar cholangiocarcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Kong, Dalu [Department of Hepatobiliary Surgery, Tianjin Medical University Cancer Institute and Hospital, Hexi District, Tianjin (China); Liang, Jun [Department of Oncology, Affiliated Hospital of Medical College, Qingdao University, Qingdao, Shandong Province (China); Li, Rong [Department of Hepatobiliary Surgery, Tianjin Medical University Cancer Institute and Hospital, Hexi District, Tianjin (China); Liu, Shihai [Department of Laboratory Center, Affiliated Hospital of Medical College, Qingdao University, Qingdao, Shandong Province (China); Wang, Jigang [Department of Oncology, Affiliated Hospital of Medical College, Qingdao University, Qingdao, Shandong Province (China); Zhang, Kejun; Chen, Dong [Department of General Surgery, Affiliated Hospital of Medical College, Qingdao University, Qingdao, Shandong Province (China)

    2012-05-11

    Many patients with hilar cholangiocarcinoma (HC) have a poor prognosis. Snail, a transcription factor and E-cadherin repressor, is a novel prognostic factor in many cancers. The aim of this study was to evaluate the relationship between snail and E-cadherin protein expression and the prognostic significance of snail expression in HC. We examined the protein expression of snail and E-cadherin in HC tissues from 47 patients (22 males and 25 females, mean age 61.2 years) using immunohistochemistry and RT-PCR. Proliferation rate was also evaluated in the same cases by the MIB1 index. High, low and negative snail protein expression was recorded in 18 (38%), 17 (36%), and 12 (26%) cases, respectively, and 40.4% (19/47) cases showed reduced E-cadherin protein expression in HC samples. No significant correlation was found between snail and E-cadherin protein expression levels (P = 0.056). No significant correlation was found between snail protein expression levels and gender, age, tumor grade, vascular or perineural invasion, nodal metastasis and invasion, or proliferative index. Cancer samples with positive snail protein expression were associated with poor survival compared with the negative expresser groups. Kaplan-Meier curves comparing different snail protein expression levels to survival showed highly significant separation (P < 0.0001, log-rank test). With multivariate analysis, only snail protein expression among all parameters was found to influence survival (P = 0.0003). We suggest that snail expression levels can predict poor survival regardless of pathological features and tumor proliferation. Immunohistochemical detection of snail protein expression levels in routine sections may provide the first biological prognostic marker.

  10. The Snail-Induced Sulfonation Pathway in Breast Cancer Metastasis

    Science.gov (United States)

    2014-09-01

    AD_________________ Award Number: W81XWH-11-1-0494   TITLE: The Snail -Induced Sulfonation... Snail -Induced Sulfonation Pathway in Breast Cancer Metastasis 5b. GRANT NUMBER W81XWH-11-1-0494 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Dr...provided funding for a 3-year project that has resulted in fundamental new insights into how the transcription factor Snail can control gene

  11. Haemolymph Components of Infected & None Infected Lymnaea Snails with Xiphidiocercariae

    OpenAIRE

    AA Saboor Yaraghi; A. Farahnak; MR Eshraghian

    2011-01-01

    Background: In this study the haemolymph components of infected and none infected Lymnaea gedrosiana with xiphidiocercaria larvae was compared.Methods: Five hundred Fifty Lymnaea snails were collected from Ilam and Mazandaran prov­inces, Iran, during 2008-2009. The snails were transported to the lab at Tehran University of Medi­cal Sciences and their cercarial sheddings were studied. Haemolmyphs of snails were ex­tracted and cells were counted using haemocytometer and cell-surface carbohydrat...

  12. Inheritance of Schistosoma mansoni infection incompatibility in Biomphalaria alexandrina snails

    OpenAIRE

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

    2010-01-01

    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,...

  13. The effects of the herbicide atrazine on freshwater snails.

    Science.gov (United States)

    Gustafson, Kyle D; Belden, Jason B; Bolek, Matthew G

    2015-07-01

    Atrazine has been shown to affect freshwater snails from the subcellular to community level. However, most studies have used different snail species, methods, endpoints, and atrazine exposure concentrations, resulting in some conflicting results and limiting our understanding. The goal of this study was to address these concerns by (1) investigating the acute and chronic effects of atrazine on four species of freshwater snails (Biomphalaria glabrata, Helisoma trivolvis, Physa acuta, and Stagnicola elodes) using the same methods, endpoints, and concentrations, and (2) summarizing the current literature pertaining to the effects of atrazine on freshwater snails. We conducted a 48 h acute toxicity test with an atrazine concentration higher than what typically occurs in aquatic environments (1000 µg/L). Additionally, we exposed snails to environmentally relevant atrazine concentrations (0, 0.3, 3, and 30 µg/L) for 28 days and assessed snail survival, growth, and reproduction. We also summarized all known literature pertaining to atrazine effects on freshwater snails. The literature summary suggests snails are often affected by environmentally relevant atrazine concentrations at the subcellular and cellular levels. These effects are typically not transitive to effects on survival, growth, or reproduction at the same concentrations. Our acute exposures corroborate the general trend of no direct effect on snail populations as atrazine did not directly affect the survival of any of the four snail species. Similarly, environmentally relevant concentrations did not significantly affect the survival, growth, or reproduction of any snail species. These results indicate that, in the absence of other possible stressors, the direct effects of environmentally relevant atrazine concentrations may not be realized at the snail population level.

  14. Snail acetylation by histone acetyltransferase p300 in lung cancer

    OpenAIRE

    Chang, Rui; Zhang, Yinjie; Zhang, Peng; Zhou, Qinghua

    2017-01-01

    Background Epithelial to mesenchymal transition (EMT) is a complex and dynamic molecular event in lung cancer metastasis that has not yet been thoroughly investigated. EMT transcriptional factors, such as Snail, play a central role in regulation of the EMT process. In this study, we sought to identify an association between p300 and Snail in lung cancer, as well as the engagement of p300 in Snail acetylation. Methods We transfected p300 small interfering RNA into lung cancer cells to detect S...

  15. Spatially Distributed Forcing for Boundary Layer Separation Control on a Wall Mounted Hump

    Science.gov (United States)

    Borgmann, David; Little, Jesse; Woszidlo, Rene

    2016-11-01

    Numerous successful efforts on controlling flow separation have been demonstrated using spatially distributed actuators. These include both steady and unsteady forcing from discrete locations in the vicinity of separation. Despite this, there are many open questions on the actual flow control mechanism. A canonical hump model is used to investigate these physics in a subsonic wind tunnel. Reynolds number independence is achieved above 0.72 ×106 and testing is performed up to 2.2 ×106. The efficacy of discrete steady jets is studied as a function of spacing, momentum coefficient, velocity ratio and mass flux. Highly-resolved surface pressure data for the controlled flow are compared to an inviscid solution establishing a figure of merit. Results indicate the inviscid limit is reached for a momentum coefficient of 1% with actuator spacing of 0.5% span. A comparison of steady discrete jets with sweeping jets actuators of equivalent cross-sectional area is undertaken. Surface flow visualization and PIV are employed to extract detailed information on the baseline and controlled flow field. This importance of establishing critical baseline features is also discussed with respect to establishing proper boundary conditions for accompanying numerical simulations. Supported by The Boeing Company.

  16. One-Humped Camel (Camelus dromedarius Infestation withLinguatula serrata in Tabriz, Iran

    Directory of Open Access Journals (Sweden)

    HR Haddadzadeh

    2010-06-01

    Full Text Available "n "nBackground: Linguatula serrata is one of well known members of Pentastomida which infects both human and animals. The aim of this study was to evaluate the prevalence of L. serrata in mesenteric lymph nodes, livers and lungs of camels slaughtered in Tabriz area, Iran. "n "nMethods: Mesenteric lymph nodes (MLNs, livers and lungs of 140 one-humped camels slaughtered in Tabriz, north-west of Iran were investigated for nymphs of L. serrata from July 2007 to June 2008. The organs were examined macroscopically and then a tissue digestion method was also done for investigation of liver and lung of the camels that had infected MLN. The liver and lung samples were mostly taken from condemned and rejected part of organs. "n "nResults: The infection rate of L. serrata nymphs in MLNs, livers and lungs was 13.5%, 1.4% and 1.4% respectively. The number of isolated nymph in infected lymph nodes varied from 2 to 18 with a mean of 4.78. Only one nymph was isolated from each infected livers and lungs. The infection rate increased with age (p<0.05. No significant difference in different sex groups and seasons was observed (p>0.05. "n "nConclusion: Considering this fact that consumption of undercooked camel liver was not common in the studied area, the zoonotic importance of this infection should be concluded.

  17. PROBABILISTIC APPROACH FOR THE DETERMINATION OF CUTS PERMISSIBLE BRAKING MODES ON THE GRAVITY HUMPS

    Directory of Open Access Journals (Sweden)

    Volodymyr BOBROVSKYI

    2016-03-01

    Full Text Available The paper presents the research results of cuts braking modes on the gravity humps. The objective of this paper is developing the methods for assessment of braking modes of cuts under conditions of fuzziness of their rolling properties, as well as selecting the permissible starting speed range of cuts from retardant positions. As a criterion for assessing the modes of target control of cut rolling speed, it was proposed to use an average gap size on a classification track at the established norms of probable exceeding of permissible speed of cars collision and their stop in retarders. As a criterion for evaluating the modes of interval control of cuts rolling speed, using the risk of their non-separation on the switches was proposed. Using the simulation modeling and mathematical statistics, the configuration of the range of permissible speed of cuts coming out from retardant positions has been set. The conducted researches allow simplifying the choice of cut braking modes in systems of automatic control of cut rolling speed.

  18. Simulation of a hump structure in the optical scattering rate within a generalized Allen formalism and its application to copper oxide systems.

    Science.gov (United States)

    Hwang, Jungseek

    2013-07-24

    We propose a possible way to simulate a hump structure in the optical scattering rate. The optical scattering rate of correlated charge carriers can be defined within an extended Drude model formalism. When some electron- and hole-doped copper oxide systems are in spin density or charge density wave phases they show hump structures in their optical scattering rates. The hump structures have not yet been simulated or clearly understood. We are able to simulate the hump structure by using a peak followed by a dip feature in the normalized density of states within a generalized Allen formalism. We observe that reversing the order of the dip and peak gives completely different features in the optical scattering rate; a peak-dip (dip-peak) results in a hump (a valley) in the scattering rate. We also obtain the real parts of the optical conductivity and reflectance spectra from the simulated optical scattering rate and compare them with published experimental spectra. From these comparisons we conclude that the peak-dip order can give the hump structure that is observed experimentally in copper oxide systems. Finally we fit two published optical spectra with our new model and discuss our results and the possible origin of the dip or peak features in the normalized density of states.

  19. Fecundity of the Chinese mystery snail in a Nebraska reservoir

    Science.gov (United States)

    Stephen, Bruce J.; Allen, Craig R.; Chaine, Noelle M.; Fricke, Kent A.; Haak, Danielle M.; Hellman, Michelle L.; Kill, Robert A.; Nemec, Kristine T.; Pope, Kevin L.; Smeenk, Nicholas A.; Uden, Daniel R.; Unstad, Kody M.; VanderHam, Ashley E.; Wong, Alec

    2013-01-01

    The Chinese mystery snail (Bellamya chinensis) is a non-indigenous, invasive species in freshwater ecosystems of North America. We provide fecundity estimates for a population of these snails in a Nebraska reservoir. We dissected 70 snails, of which 29 were females. Nearly all female snails contained developing young, with an average of 25 young per female. Annual fecundity was estimated at between 27.2 and 33.3 young per female per year. Based on an estimated adult population and the calculated fecundity, the annual production for this reservoir was between 2.2 and 3.7 million young.

  20. Inheritance of Schistosoma mansoni infection incompatibility in Biomphalaria alexandrina snails

    Directory of Open Access Journals (Sweden)

    Iman F Abou El Naga

    2010-03-01

    Full Text Available 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.

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

    Science.gov (United States)

    Bakry, Fayez A; Hamdi, Salwa A H

    2006-12-01

    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.

  2. How stress alters memory in 'smart' snails.

    Directory of Open Access Journals (Sweden)

    Sarah Dalesman

    Full Text Available Cognitive ability varies within species, but whether this variation alters the manner in which memory formation is affected by environmental stress is unclear. The great pond snail, Lymnaea stagnalis, is commonly used as model species in studies of learning and memory. The majority of those studies used a single laboratory strain (i.e. the Dutch strain originating from a wild population in the Netherlands. However, our recent work has identified natural populations that demonstrate significantly enhanced long-term memory (LTM formation relative to the Dutch strain following operant conditioning of aerial respiratory behaviour. Here we assess how two populations with enhanced memory formation (i.e. 'smart' snails, one from Canada (Trans Canada 1: TC1 and one from the U.K. (Chilton Moor: CM respond to ecologically relevant stressors. In control conditions the Dutch strain forms memory lasting 1-3 h following a single 0.5 h training session in our standard calcium pond water (80 mg/l [Ca(2+], whereas the TC1 and CM populations formed LTM lasting 5+ days following this training regime. Exposure to low environmental calcium pond water (20 mg/l [Ca(2+], which blocks LTM in the Dutch strain, reduced LTM retention to 24 h in the TC1 and CM populations. Crowding (20 snails in 100 ml immediately prior to training blocks LTM in the Dutch strain, and also did so in TC1 and CM populations. Therefore, snails with enhanced cognitive ability respond to these ecologically relevant stressors in a similar manner to the Dutch strain, but are more robust at forming LTM in a low calcium environment. Despite the two populations (CM and TC1 originating from different continents, LTM formation was indistinguishable in both control and stressed conditions. This indicates that the underlying mechanisms controlling cognitive differences among populations may be highly conserved in L. stagnalis.

  3. The convoluted evolution of snail chirality

    Science.gov (United States)

    Schilthuizen, M.; Davison, A.

    2005-11-01

    The direction that a snail (Mollusca: Gastropoda) coils, whether dextral (right-handed) or sinistral (left-handed), originates in early development but is most easily observed in the shell form of the adult. Here, we review recent progress in understanding snail chirality from genetic, developmental and ecological perspectives. In the few species that have been characterized, chirality is determined by a single genetic locus with delayed inheritance, which means that the genotype is expressed in the mother's offspring. Although research lags behind the studies of asymmetry in the mouse and nematode, attempts to isolate the loci involved in snail chirality have begun, with the final aim of understanding how the axis of left-right asymmetry is established. In nature, most snail taxa (>90%) are dextral, but sinistrality is known from mutant individuals, populations within dextral species, entirely sinistral species, genera and even families. Ordinarily, it is expected that strong frequency-dependent selection should act against the establishment of new chiral types because the chiral minority have difficulty finding a suitable mating partner (their genitalia are on the ‘wrong’ side). Mixed populations should therefore not persist. Intriguingly, however, a very few land snail species, notably the subgenus Amphidromus sensu stricto, not only appear to mate randomly between different chiral types, but also have a stable, within-population chiral dimorphism, which suggests the involvement of a balancing factor. At the other end of the spectrum, in many species, different chiral types are unable to mate and so could be reproductively isolated from one another. However, while empirical data, models and simulations have indicated that chiral reversal must sometimes occur, it is rarely likely to lead to so-called ‘single-gene’ speciation. Nevertheless, chiral reversal could still be a contributing factor to speciation (or to divergence after speciation) when

  4. The One-humped Camel in the Canary Islands: History and Present Status

    Directory of Open Access Journals (Sweden)

    Wilson, RT.

    2015-01-01

    Full Text Available The one-humped camel (Camelus dromedarius L. is not indigenous to the Canary Islands but based on historical references was introduced at the very beginning of the fifteenth century. The camel thrived in the subtropical dry environment. A long period of isolation from other animals of the same species meant that the animals were virtually disease free. This made the Islands an ideal base for exporting camels to new areas such that camels from the Canaries went to Peru in the sixteenth century, to Brazil in the eighteenth century, Venezuela and Bolivia in the early part of the nineteenth century and Australia in 1840. Camels went to several Caribbean islands in the middle of the nineteenth century. More recently (late twentieth and early twenty-first centuries some animals were exported from the islands to mainland Europe, notably France, Spain and the Netherlands, and to South America. Camels have been used in military operations, as transport and draught animals in support of agriculture and have found a role in the tourist industry. In early 2013 there were some 1,300 camels distributed over four of the larger islands of the archipelago in herds varying in size from a single animal to herds of as many as 150 head: a large group of about 400 heads kept in a Safari Park on the island of Fuerteventura is considered as the national conservation herd. The "Canary" camel has recently been shown to be genetically distinct from most other populations and it has been proposed that it should be designated as a distinct breed.

  5. A biometric study of the digestive tract of one-humped camel (camelus dromedarius fetuses

    Directory of Open Access Journals (Sweden)

    A. Bello

    2012-09-01

    Full Text Available A Biometrical study was conducted on the digestive tract of 35 foetuses of the one-humped camel collected from the Sokoto metropolitan abattoir, over a period of five months at different gestational ages. The approximate age of the foetuses was estimated from the crown vertebral rump length (CVRL and samples were categorised into first, second and third trimester. The mean body weight of the foetus at first, second third trimester ranged from 1.40 ± 0.06 kg, 6.10 ± 0.05 kg and 17.87 ± 0.6 kg respectively. The mean weights of the entire digestive system at first, second and third trimester were 0.80 ± 0.07 kg, 2.13 ± 0.04 kg and 4.86 ± 0.08 kg respectively. The mean weights of the digestive tract at first, second and third trimester were 0.53 ± 0.07 kg, 1.03 ± 0.05 and 2.43 ± 0.07 kg respectively. The small intestine at first trimester were found not to have any clear demarcation to show duodenum, jejunum and ileum; the entire small intestine was found to be 76.00 ± 3.00 cm at first trimester and showed clear demarcation at second and third trimesters.. The mean volumes of the entire stomach (rumen, reticular and abomasum ranged from 136.67 ± 8.30 cm3 at first trimester to 353.33 ± 6.50 cm3 at third trimester. It was observed that there was increase in body weight, organ weight and individual segment of the digestive tract of the fetuses with advancement in gestation period. A geometrical increase in length and diameter of the various segments of the digestive tract showed a significant difference (P≤ 0.05 with advancement in gestational period.

  6. Supercharged Snails for Stream Ecology & Water-Quality Studies

    Science.gov (United States)

    Stewart, Arthur J.; Ryon, Michael G.

    2003-01-01

    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…

  7. The role of DDX3 in regulating Snail.

    Science.gov (United States)

    Sun, Mianen; Song, Ling; Zhou, Tong; Gillespie, G Yancey; Jope, Richard S

    2011-03-01

    DDX3, a DEAD box protein family member, appears to promote the progression of some cancers, which may partly result from its impedance of death receptor-mediated apoptosis. We found that another mechanism by which DDX3 may aid cancer progression is by promoting increased levels of the transcription factor Snail. Snail represses expression of cellular adhesion proteins, leading to increased cell migration and metastasis of many types of cancer. Knockdown of DDX3 levels by shRNA reduced basal levels of Snail in HeLa and MCF-7 cells, and this was associated with reduced cell proliferation and migration. Snail protein and mRNA levels were increased by treatment with the HDAC inhibitors sodium butyrate or trichostatin A, and these increases were attenuated in cells with DDX3 knocked down. Treatment of cells with camptothecin was discovered to increase Snail protein levels, and this increase was diminished in cells with DDX3 knocked down. Analysis of 31 patient glioblastoma multiforme (GBM) samples revealed a significant correlation between the levels of DDX3 and Snail. Thus, DDX3 is required for basal Snail expression and increases in Snail induced by HDAC inhibitors or camptothecin, indicating that this action of DDX3 may contribute to its promotion of the progression of some cancers.

  8. Management of shells of giant African snails (Achatinidae) from the ...

    African Journals Online (AJOL)

    SARAH

    2014-12-01

    Dec 1, 2014 ... The trading of the snail in Abidjan is exclusively done by women of all ages, educated and ... The markets of Abidjan produced a large amount of empty snail shells, ..... Thus, for profit, retailers focus on A. ventricosa for.

  9. The Role of Snail in EMT and Tumorigenesis.

    Science.gov (United States)

    Wang, Yifan; Shi, Jian; Chai, Kequn; Ying, Xuhua; Zhou, Binhua P

    2013-11-01

    Epithelial-mesenchymal transition (EMT) is a highly conserved process in which polarized, immobile epithelial cells lose tight junctions, associated adherence, and become migratory mesenchymal cells. Several transcription factors, including the Snail/Slug family, Twist, δEF1/ZEB1, SIP1/ZEB2 and E12/E47 respond to microenvironmental stimuli and function as molecular switches for the EMT program. Snail is a zinc-finger transcriptional repressor controlling EMT during embryogenesis and tumor progression. Through its N-terminal SNAG domain, Snail interacts with several corepressors and epigenetic remodeling complexes to repress specific target genes, such as the E-cadherin gene (CDH1). An integrated and complex signaling network, including the RTKs, TGF-β, Notch, Wnt, TNF-α, and BMPs pathways, activates Snail, thereby inducing EMT. Snail expression correlates with the tumor grade, nodal metastasis of many types of tumor and predicts a poor outcome in patients with metastatic cancer. Emerging evidences indicate that Snail causes a metabolic reprogramming, bestows tumor cells with cancer stem cell-like traits, and additionally, promotes drug resistance, tumor recurrence and metastasis. Despite many new and exciting developments, several challenges remain to be addressed in order to understand more thoroughly the role of Snail in metastasis. Additional investigations are required to disclose the contribution of microenvironmental factors on tumor progression. This information will lead to a comprehensive understanding of Snail in cancer and will provide us with novel approaches for preventing and treating metastatic cancers.

  10. Whole genome analysis of a schistosomiasis-transmitting freshwater snail

    DEFF Research Database (Denmark)

    Adema, Coen M; Hillier, Ladeana W; Jones, Catherine S

    2017-01-01

    Biomphalaria snails are instrumental in transmission of the human blood fluke Schistosoma mansoni. With the World Health Organization's goal to eliminate schistosomiasis as a global health problem by 2025, there is now renewed emphasis on snail control. Here, we characterize the genome of Biompha...

  11. Community ecology of tropical forest snails: 30 years after Solem

    NARCIS (Netherlands)

    Schilthuizen, M.

    2011-01-01

    Since Solem’s provocative claim in the early 1980s that land snails in tropical forests are neither abundant nor diverse, at least 30 quantitative-ecological papers on tropical land snail communities have appeared. Jointly, these papers have shown that site diversity is, in fact, high in tropical fo

  12. Phenotypic plasticity of the introduced New Zealand mud snail, Potamopyrgus antipodarum, compared to sympatric native snails.

    Science.gov (United States)

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

    2014-01-01

    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.

  13. Phenotypic plasticity of the introduced New Zealand mud snail, Potamopyrgus antipodarum, compared to sympatric native snails.

    Directory of Open Access Journals (Sweden)

    Edward P Levri

    Full Text Available 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.

  14. Microhabitats within Venomous Cone Snails Contain Diverse Actinobacteria▿ †

    Science.gov (United States)

    Peraud, Olivier; Biggs, Jason S.; Hughen, Ronald W.; Light, Alan R.; Concepcion, Gisela P.; Olivera, Baldomero M.; Schmidt, Eric W.

    2009-01-01

    Actinomycetes can be symbionts in diverse organisms, including both plants and animals. Some actinomycetes benefit their host by producing small molecule secondary metabolites; the resulting symbioses are often developmentally complex. Actinomycetes associated with three cone snails were studied. Cone snails are venomous tropical marine gastropods which have been extensively examined because of their production of peptide-based neurological toxins, but no microbiological studies have been reported on these organisms. A microhabitat approach was used in which dissected tissue from each snail was treated as an individual sample in order to explore bacteria in the tissues separately. Our results revealed a diverse, novel, and highly culturable cone snail-associated actinomycete community, with some isolates showing promising bioactivity in a neurological assay. This suggests that cone snails may represent an underexplored reservoir of novel actinomycetes of potential interest for drug discovery. PMID:19749071

  15. Whole genome analysis of a schistosomiasis-transmitting freshwater snail.

    Science.gov (United States)

    Adema, Coen M; Hillier, LaDeana W; Jones, Catherine S; Loker, Eric S; Knight, Matty; Minx, Patrick; Oliveira, Guilherme; Raghavan, Nithya; Shedlock, Andrew; do Amaral, Laurence Rodrigues; Arican-Goktas, Halime D; Assis, Juliana G; Baba, Elio Hideo; Baron, Olga L; Bayne, Christopher J; Bickham-Wright, Utibe; Biggar, Kyle K; Blouin, Michael; Bonning, Bryony C; Botka, Chris; Bridger, Joanna M; Buckley, Katherine M; Buddenborg, Sarah K; Lima Caldeira, Roberta; Carleton, Julia; Carvalho, Omar S; Castillo, Maria G; Chalmers, Iain W; Christensens, Mikkel; Clifton, Sandra; Cosseau, Celine; Coustau, Christine; Cripps, Richard M; Cuesta-Astroz, Yesid; Cummins, Scott F; di Stephano, Leon; Dinguirard, Nathalie; Duval, David; Emrich, Scott; Feschotte, Cédric; Feyereisen, Rene; FitzGerald, Peter; Fronick, Catrina; Fulton, Lucinda; Galinier, Richard; Gava, Sandra G; Geusz, Michael; Geyer, Kathrin K; Giraldo-Calderón, Gloria I; de Souza Gomes, Matheus; Gordy, Michelle A; Gourbal, Benjamin; Grunau, Christoph; Hanington, Patrick C; Hoffmann, Karl F; Hughes, Daniel; Humphries, Judith; Jackson, Daniel J; Jannotti-Passos, Liana K; de Jesus Jeremias, Wander; Jobling, Susan; Kamel, Bishoy; Kapusta, Aurélie; Kaur, Satwant; Koene, Joris M; Kohn, Andrea B; Lawson, Dan; Lawton, Scott P; Liang, Di; Limpanont, Yanin; Liu, Sijun; Lockyer, Anne E; Lovato, TyAnna L; Ludolf, Fernanda; Magrini, Vince; McManus, Donald P; Medina, Monica; Misra, Milind; Mitta, Guillaume; Mkoji, Gerald M; Montague, Michael J; Montelongo, Cesar; Moroz, Leonid L; Munoz-Torres, Monica C; Niazi, Umar; Noble, Leslie R; Oliveira, Francislon S; Pais, Fabiano S; Papenfuss, Anthony T; Peace, Rob; Pena, Janeth J; Pila, Emmanuel A; Quelais, Titouan; Raney, Brian J; Rast, Jonathan P; Rollinson, David; Rosse, Izinara C; Rotgans, Bronwyn; Routledge, Edwin J; Ryan, Kathryn M; Scholte, Larissa L S; Storey, Kenneth B; Swain, Martin; Tennessen, Jacob A; Tomlinson, Chad; Trujillo, Damian L; Volpi, Emanuela V; Walker, Anthony J; Wang, Tianfang; Wannaporn, Ittiprasert; Warren, Wesley C; Wu, Xiao-Jun; Yoshino, Timothy P; Yusuf, Mohammed; Zhang, Si-Ming; Zhao, Min; Wilson, Richard K

    2017-05-16

    Biomphalaria snails are instrumental in transmission of the human blood fluke Schistosoma mansoni. With the World Health Organization's goal to eliminate schistosomiasis as a global health problem by 2025, there is now renewed emphasis on snail control. Here, we characterize the genome of Biomphalaria glabrata, a lophotrochozoan protostome, and provide timely and important information on snail biology. We describe aspects of phero-perception, stress responses, immune function and regulation of gene expression that support the persistence of B. glabrata in the field and may define this species as a suitable snail host for S. mansoni. We identify several potential targets for developing novel control measures aimed at reducing snail-mediated transmission of schistosomiasis.

  16. The mitochondrial genome of the venomous cone snail Conus consors.

    Directory of Open Access Journals (Sweden)

    Age Brauer

    Full Text Available Cone snails are venomous predatory marine neogastropods that belong to the species-rich superfamily of the Conoidea. So far, the mitochondrial genomes of two cone snail species (Conus textile and Conus borgesi have been described, and these feed on snails and worms, respectively. Here, we report the mitochondrial genome sequence of the fish-hunting cone snail Conus consors and describe a novel putative control region (CR which seems to be absent in the mitochondrial DNA (mtDNA of other cone snail species. This possible CR spans about 700 base pairs (bp and is located between the genes encoding the transfer RNA for phenylalanine (tRNA-Phe, trnF and cytochrome c oxidase subunit III (cox3. The novel putative CR contains several sequence motifs that suggest a role in mitochondrial replication and transcription.

  17. 光纤激光焊接工艺参量对底部驼峰的影响%Effect of fiber laser welding parameters on root humps

    Institute of Scientific and Technical Information of China (English)

    周聪; 夏海龙; 陈根余; 李时春; 黎长邹

    2015-01-01

    In order to study influence of welding parameters on root humps in high power fiber laser welding , effect of laser power, welding speed, defocus, flow rate of bottom shielding gas and welding position on root humps was studied based on a single variable method .The results show that , with the increase of laser power , root humps tend to increase at first and then decrease .When welding speed increases , root hump height increases at first and then decreases , root hump spacing decreases significantly.When defocus is near 0mm, root hump tendency is obvious .Under the appropriate flow rate of bottom shielding gas, root hump tendency is reduced .The optimal rate is 15L/min.When welding orientation is 60°, root hump tendency decreases to a certain extent .The results show that reasonable welding parameters can eliminate root hump efficiently .%为了研究高功率光纤激光焊接工艺参量对底部驼峰倾向的影响,采用单一变量方法研究了激光功率、焊接速度、离焦量、下表面保护气体流量及焊接方位的变化对底部驼峰的影响。结果表明,随激光功率的增加,底部驼峰倾向先加大后减小;焊接速率提高时,底部驼峰高度先增加后减小,驼峰间距明显减小;离焦量在0 mm附近时,底部驼峰倾向较大;适当的下表面保护气体流量有助于减小底部驼峰倾向,最佳流量为15L/min;焊接方位为60°时,一定程度上可减小底部驼峰倾向。优化后的工艺参量合理,可有效地消除底部驼峰。

  18. Research on Influence of Wind Resistance on Cars Humping%车辆溜放运动中风阻力影响研究

    Institute of Scientific and Technical Information of China (English)

    丁昆

    2012-01-01

    The movement equation of cars humping is the theoretical base of modelling of hump automation. For a long time, uniform variable motion has been turned to in engineering application, which obviously is not accurate. Starting from research on the influence of wind resistances on cars humping, the quadratic equation of nonuniform variable motion between the wind resistance and rolling speed was established. The equation of nonuniform variable motion of cars humping was set up by mathematical derivation , which revealed the moving law of cars humping more accurately. The mathematical model has been successfully applied in control of car rolling speeds of the automatic hump yard system. Reference can also be provided for modelling in the fields of improvement of hump design methods , accurate measurement of cars humping resistances and cars humping emulation.%车辆溜放运动方程是驼峰自动化建模的基础理论,长期以来工程应用中一直按匀变速运动简化处理,不够精确.本文从研究车辆溜放风阻力着手,建立风阻力与溜放速度间的二次方程,通过数学推导获得溜放车辆的非匀变速运动方程,较匀变速运动方程能够更加精确地反映驼峰车辆溜放的运动规律.该方程已作为数学模型成功应用于驼峰自动化系统车辆溜放速度的精确控制与分析,收效甚好.该方程可供驼峰设计方法改进、车辆溜放阻力精确测量和驼峰溜放仿真时借鉴.

  19. Modeling snail breeding in Bioregenerative Life Support System

    Science.gov (United States)

    Kovalev, Vladimir; Tikhomirov, Alexander A.; Nickolay Manukovsky, D..

    It is known that snail meat is a high quality food that is rich in protein. Hence, heliciculture or land snail farming spreads worldwide because it is a profitable business. The possibility to use the snails of Helix pomatia in Biological Life Support System (BLSS) was studied by Japanese Researches. In that study land snails were considered to be producers of animal protein. Also, snail breeding was an important part of waste processing, because snails were capable to eat the inedible plant biomass. As opposed to the agricultural snail farming, heliciculture in BLSS should be more carefully planned. The purpose of our work was to develop a model for snail breeding in BLSS that can predict mass flow rates in and out of snail facility. There are three linked parts in the model called “Stoichiometry”, “Population” and “Mass balance”, which are used in turn. Snail population is divided into 12 age groups from oviposition to one year. In the submodel “Stoichiometry” the individual snail growth and metabolism in each of 12 age groups are described with stoichiometry equations. Reactants are written on the left side of the equations, while products are written on the right side. Stoichiometry formulas of reactants and products consist of four chemical elements: C, H, O, N. The reactants are feed and oxygen, products are carbon dioxide, metabolic water, snail meat, shell, feces, slime and eggs. If formulas of substances in the stoichiometry equations are substituted with their molar masses, then stoichiometry equations are transformed to the equations of molar mass balance. To get the real mass balance of individual snail growth and metabolism one should multiply the value of each molar mass in the equations on the scale parameter, which is the ratio between mass of monthly consumed feed and molar mass of feed. Mass of monthly consumed feed and stoichiometry coefficients of formulas of meat, shell, feces, slime and eggs should be determined experimentally

  20. Power efficiency of the active boundary layer control around the hump by a slotted synthetic jet generator

    Directory of Open Access Journals (Sweden)

    Pick Petr

    2015-01-01

    Full Text Available The present contribution summarizes the power efficiency of the active flow control of the boundary layer of air around a hump. The synthetic jet generator with a rectangular output part, i.e. a slot, is actuated using a modulated signal. The actuation of the synthetic jet is carried out by modulating the input voltage of acoustic transducers of the generator. This causes the decrease of the loss coefficient and the change of the mixing size area (e.g. wake. A comparison of three types of modulating signals and their influence on the loss coefficient is performed. The main advantages of modulated signal are then described.

  1. Self-assembled formation and transformation of In/CdZnTe(110) nano-rings into camel-humps

    Energy Technology Data Exchange (ETDEWEB)

    Cohen-Taguri, G. [School of Mechanical Engineering and Materials and Nanotechnologies Program, Faculty of Engineering, Tel Aviv University, Tel Aviv 69978 (Israel); Ruzin, A. [School of Electrical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv 69978 (Israel); Goldfarb, I. [School of Mechanical Engineering and Materials and Nanotechnologies Program, Faculty of Engineering, Tel Aviv University, Tel Aviv 69978 (Israel); Research Center for Nanoscience and Nanotechnology, Tel Aviv University, Tel Aviv 69978 (Israel)

    2012-05-21

    We used in situ scanning tunneling microscopy to monitor in real time the formation of nano-rings at the molecular beam epitaxially grown In/CdZnTe(110) surface, and Auger electron spectroscopy to explore the corresponding compositional changes. In-diffusion of In and segregation of Cd to the surface in course of annealing lead to a formation of elliptically distorted nano-rings, elongated along the fast [110] diffusion direction. Exacerbated diffusion anisotropy in the liquid state, at temperatures above the melting point of In, further distorts the nano-rings into a camel-hump shape.

  2. Spatial mosaic evolution of snail defensive traits

    Directory of Open Access Journals (Sweden)

    de León Francisco

    2007-03-01

    Full Text Available Abstract 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.

  3. Enumerating Trees

    CERN Document Server

    Kucharczyk, Robert A

    2012-01-01

    In this note we discuss trees similar to the Calkin-Wilf tree, a binary tree that enumerates all positive rational numbers in a simple way. The original construction of Calkin and Wilf is reformulated in a more algebraic language, and an elementary application of methods from analytic number theory gives restrictions on possible analogues.

  4. Crawling beneath the free surface: Water snail locomotion

    Science.gov (United States)

    Lee, Sungyon; Bush, John W. M.; Hosoi, A. E.; Lauga, Eric

    2008-08-01

    Land snails move via adhesive locomotion. Through muscular contraction and expansion of their foot, they transmit waves of shear stress through a thin layer of mucus onto a solid substrate. Since a free surface cannot support shear stress, adhesive locomotion is not a viable propulsion mechanism for water snails that travel inverted beneath the free surface. Nevertheless, the motion of the freshwater snail, Sorbeoconcha physidae, is reminiscent of that of its terrestrial counterparts, being generated by the undulation of the snail foot that is separated from the free surface by a thin layer of mucus. Here, a lubrication model is used to describe the mucus flow in the limit of small-amplitude interfacial deformations. By assuming the shape of the snail foot to be a traveling sine wave and the mucus to be Newtonian, an evolution equation for the interface shape is obtained and the resulting propulsive force on the snail is calculated. This propulsive force is found to be nonzero for moderate values of the capillary number but vanishes in the limits of high and low capillary number. Physically, this force arises because the snail's foot deforms the free surface, thereby generating curvature pressures and lubrication flows inside the mucus layer that couple to the topography of the foot.

  5. Anti-ulcer potentials of phylum mollusca (tropical snail) slime

    Institute of Scientific and Technical Information of China (English)

    Nwodo NJ; Okonta J M; Ezugwu CO; Attama AA

    2009-01-01

    Objective:The effectiveness of the slimy substance in snail to regenerate and repair damaged areas on its body/shell lead to this investigation.Methods:The anti-ulcer'property of snail slime extracted from phylum mollusca (tropical snail)from the giant African snail Archachatina marginata (Fam.Arionidae)was investi-gated using histamine,stress and indomethacin-induced ulcers.The solubility profile of extract was investiga-ted in different solvents and at different temperatures.Chemical analysis was carried out to determine the types of constituents present in the slim,while acute toxicity test was carried out to evaluate its profile of toxicity. The effect of the snail slim on gastrointestinal motility was investigated in mice,while the guinea pig ileum was used to study the effect of the extract on contraction produced by acetylcholine and histamine.The snail slime contained copious quantity of protein,with varying amounts of simple sugars,carbohydrates and fats.The slime was not soluble in most common solvents and increases in temperature,did not appear to increase its sol-ubility.Results:The result further indicated that although the snail slime exhibited significant (P <0.05)an-ti-ulcer induced by stress and histamine,it was most potent against ulcer induced by indomethacin.The snail slime potently inhibited gastrointestinal movement in mice in a dose-dependent manner;however,it was not a-ble to inhibit contraction induced by acetylcholine and histamine in guinea pig ileum.Conclusion:The snail mucin possesses potent antiulcer properties without any toxic effect.The mechanism responsible for the anti-ul-cer property may not be postulated with certainty but cytoprotective and anti-spasmodic activities are most likely to be involved.

  6. Painful rib hump: a new clinical sign for detecting intraspinal rib displacement in scoliosis due to neurofibromatosis

    Directory of Open Access Journals (Sweden)

    Katsalouli Marina

    2006-06-01

    Full Text Available Abstract Background Spinal cord compression and associate neurological impairment is rare in patients with scoliosis and neurofibromatosis. Common reasons are vertebral subluxation, dislocation, angulation and tumorous lesions around the spinal canal. Only twelve cases of intraspinal rib dislocation have been reported in the literature. The aim of this report is to present a case of rib penetration through neural foramen at the apex of a scoliotic curve in neurofibromatosis and to introduce a new clinical sign for its detection. Methods A 13-year-old girl was evaluated for progressive left thoracic kyphoscoliotic curve due to a type I neurofibromatosis. Clinical examination revealed multiple large thoracic and abdominal "cafe-au-lait" spots, neurological impairment of the lower limbs and the presence of a thoracic gibbous that was painful to pressure at the level of the left eighth rib (Painful Rib Hump. CT-scan showed detachment and translocation of the cephalic end of the left eighth rib into the adjacent enlarged neural foramen. The M.R.I. examination of the spine showed neither cord abnormality nor neurogenic tumor. Results The patient underwent resection of the intraspinal mobile eighth rib head and posterior spinal instrumentation and was neurologically fully recovered six months postoperatively. Conclusion Spine surgeons should be aware of intraspinal rib displacement in scoliotic curves in neurofibromatosis. Painful rib hump is a valuable diagnostic tool for this rare clinical entity.

  7. Development of Buffalo Hump in the course of antiretroviral therapy including raltegravir and unboosted atazanavir: a case report and review of the literature

    Directory of Open Access Journals (Sweden)

    Mastroianni Claudio M

    2011-02-01

    Full Text Available Abstract Introduction The availability of raltegravir plus atazanavir provides an alternative antiretroviral strategy that may be equally efficacious and less toxic than those currently recommended in HIV treatment guidelines. In fact, this new combination antiretroviral therapy attracts the attention of the scientific community because both drugs have a good safety profile coupled with potent antiviral activity, and their combined use would avert nucleoside- and ritonavir-related toxicities. Case presentation We describe the case of a 47-year-old, Caucasian woman treated for HIV-1 infection who developed Buffalo Hump during antiretroviral therapy, including raltegravir and unboosted atazanavir. Clinical evaluation and an ultrasonography scan of the cervical region showed a new progressive increase of lipohypertrophy and the results of DEXA confirmed these data. In our patient the worsening of the Buffalo Hump cannot be attributed to hypercortisolism; insulin-resistance, diabetes, dyslipidemia, hyperlactatemia and metabolic syndrome were not present. Moreover, she was not in therapy with antiretroviral drugs that are described as the cause of Buffalo Hump; on the other hand she developed this side effect three months after the switch of the antiretroviral therapy to raltegravir plus unboosted atazanavir. Conclusion Current data indicate that the etiology of HIV-associated Buffalo Hump remains elusive but is likely multifactorial; a possible contributing cause, but not the main cause, could be exposure to antiretroviral drugs. To the best of our knowledge, this is the first report on development of Buffalo Hump in the course of antiretroviral therapy, including the use of these drugs. On the basis of our data we can formulate the hypothesis of a pharmacological pathogenesis that underlies the development of this case of Buffalo Hump in the absence of other risk factors.

  8. Tree compression with top trees

    DEFF Research Database (Denmark)

    Bille, Philip; Gørtz, Inge Li; Landau, Gad M.;

    2015-01-01

    We introduce a new compression scheme for labeled trees based on top trees. Our compression scheme is the first to simultaneously take advantage of internal repeats in the tree (as opposed to the classical DAG compression that only exploits rooted subtree repeats) while also supporting fast...

  9. Tree compression with top trees

    DEFF Research Database (Denmark)

    Bille, Philip; Gørtz, Inge Li; Landau, Gad M.

    2013-01-01

    We introduce a new compression scheme for labeled trees based on top trees [3]. Our compression scheme is the first to simultaneously take advantage of internal repeats in the tree (as opposed to the classical DAG compression that only exploits rooted subtree repeats) while also supporting fast...

  10. Tree compression with top trees

    DEFF Research Database (Denmark)

    Bille, Philip; Gørtz, Inge Li; Landau, Gad M.

    2015-01-01

    We introduce a new compression scheme for labeled trees based on top trees. Our compression scheme is the first to simultaneously take advantage of internal repeats in the tree (as opposed to the classical DAG compression that only exploits rooted subtree repeats) while also supporting fast...

  11. Relationship between snail population density and infection status of snails and fish with zoonotic trematodes in Vietnamese carp nurseries

    DEFF Research Database (Denmark)

    Clausen, Jesper Hedegaard; Madsen, Henry; Murrell, Kenneth Darwin

    2012-01-01

    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...

  12. Correlating molecular phylogeny with venom apparatus occurrence in Panamic auger snails (Terebridae.

    Directory of Open Access Journals (Sweden)

    Mandë Holford

    Full Text Available Central to the discovery of neuroactive compounds produced by predatory marine snails of the superfamily Conoidea (cone snails, terebrids, and turrids is identifying those species with a venom apparatus. Previous analyses of western Pacific terebrid specimens has shown that some Terebridae groups have secondarily lost their venom apparatus. In order to efficiently characterize terebrid toxins, it is essential to devise a key for identifying which species have a venom apparatus. The findings presented here integrate molecular phylogeny and the evolution of character traits to infer the presence or absence of the venom apparatus in the Terebridae. Using a combined dataset of 156 western and 33 eastern Pacific terebrid samples, a phylogenetic tree was constructed based on analyses of 16S, COI and 12S mitochondrial genes. The 33 eastern Pacific specimens analyzed represent four different species: Acus strigatus, Terebra argyosia, T. ornata, and T. cf. formosa. Anatomical analysis was congruent with molecular characters, confirming that species included in the clade Acus do not have a venom apparatus, while those in the clade Terebra do. Discovery of the association between terebrid molecular phylogeny and the occurrence of a venom apparatus provides a useful tool for effectively identifying the terebrid lineages that may be investigated for novel pharmacological active neurotoxins, enhancing conservation of this important resource, while providing supplementary information towards understanding terebrid evolutionary diversification.

  13. Correlating molecular phylogeny with venom apparatus occurrence in Panamic auger snails (Terebridae).

    Science.gov (United States)

    Holford, Mandë; Puillandre, Nicolas; Modica, Maria Vittoria; Watkins, Maren; Collin, Rachel; Bermingham, Eldredge; Olivera, Baldomero M

    2009-11-05

    Central to the discovery of neuroactive compounds produced by predatory marine snails of the superfamily Conoidea (cone snails, terebrids, and turrids) is identifying those species with a venom apparatus. Previous analyses of western Pacific terebrid specimens has shown that some Terebridae groups have secondarily lost their venom apparatus. In order to efficiently characterize terebrid toxins, it is essential to devise a key for identifying which species have a venom apparatus. The findings presented here integrate molecular phylogeny and the evolution of character traits to infer the presence or absence of the venom apparatus in the Terebridae. Using a combined dataset of 156 western and 33 eastern Pacific terebrid samples, a phylogenetic tree was constructed based on analyses of 16S, COI and 12S mitochondrial genes. The 33 eastern Pacific specimens analyzed represent four different species: Acus strigatus, Terebra argyosia, T. ornata, and T. cf. formosa. Anatomical analysis was congruent with molecular characters, confirming that species included in the clade Acus do not have a venom apparatus, while those in the clade Terebra do. Discovery of the association between terebrid molecular phylogeny and the occurrence of a venom apparatus provides a useful tool for effectively identifying the terebrid lineages that may be investigated for novel pharmacological active neurotoxins, enhancing conservation of this important resource, while providing supplementary information towards understanding terebrid evolutionary diversification.

  14. Phylogenetic relationships of the operculate land snail genus Cyclophorus Montfort, 1810 in Thailand.

    Science.gov (United States)

    Nantarat, Nattawadee; Tongkerd, Piyoros; Sutcharit, Chirasak; Wade, Christopher M; Naggs, Fred; Panha, Somsak

    2014-01-01

    Operculate land snails of the genus Cyclophorus are distributed widely in sub-tropical and tropical Asia. Shell morphology is traditionally used for species identification in Cyclophorus but their shells exhibit considerable variation both within and between populations; species limits have been extremely difficult to determine and are poorly understood. Many currently recognized species have discontinuous distributions over large ranges but geographical barriers and low mobility of snails are likely to have led to long periods of isolation resulting in cryptic speciation of allopatric populations. As a contribution towards solving these problems, we reconstructed the molecular phylogeny of 87 Cyclophorus specimens, representing 29 nominal species (of which one was represented by four subspecies), plus three related out-group species. Molecular phylogenetic analyses were used to investigate geographic limits and speciation scenarios. The analyses of COI, 16S rRNA and 28S rRNA gene fragments were performed using neighbour-joining (NJ), maximum likelihood (ML), and Bayesian inference (BI) methods. All the obtained phylogenetic trees were congruent with each other and in most cases confirmed the species level classification. However, at least three nominate species were polyphyletic. Both C. fulguratus and C. volvulus appear to be species complexes, suggesting that populations of these species from different geographical areas of Thailand are cryptic species. C. aurantiacus pernobilis is distinct and likely to be a different species from the other members of the C. aurantiacus species complex.

  15. Habitat preferences of coral-associated wentletrap snails (Gastropoda: Epitoniidae)

    NARCIS (Netherlands)

    Gittenberger, A.; Hoeksema, B.W.

    2013-01-01

    Examination of about 60,000 scleractinian corals of the families Dendrophylliidae, Euphylliidae and Fungiidae for the presence of associated wentletrap snails (Gastropoda: Epitoniidae) revealed various ectoparasitic life history strategies. Twenty Indo-Pacific wentletrap species were found, which we

  16. Molecular diversity of avian schistosomes in Danish freshwater snails

    DEFF Research Database (Denmark)

    Christiansen, Anne Ø.; Olsen, Annette; Buchmann, Kurt

    2016-01-01

    Avian schistosomes are widespread parasites of snails and waterfowl and may cause cercarial dermatitis (swimmer's itch) in humans, a disease that is frequently reported in European countries. These parasites are known to occur in Denmark, but here, we applied a new approach using molecular tools...... to identify the parasites at species level. In order to do that, 499 pulmonate freshwater snails (Radix sp., Lymnaea stagnalis, Stagnicola sp. and Planorbarius corneus) were sampled from 12 lakes, ponds, and marshes in the greater Copenhagen area. Avian schistosome cercariae were identified by microscopy...... and subjected to molecular investigation by sequencing and phylogenetic analysis of the 5.8S and ITS2 ribosomal DNA for species identification. Additionally, snail hosts belonging to the genus Radix were identified by sequencing and phylogenetic analysis of partial ITS2 ribosomal DNA. Three out of 499 snails...

  17. CRCP-Acropora palmata snail corallivore removal evaluation

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Corallivorous snail feeding scars are a common source of tissue loss for the threatened coral Acropora palmata, accounting for roughly one quarter of tissue loss in...

  18. Determinants of production level of commercial snail farmers in Oyo ...

    African Journals Online (AJOL)

    Analytical tools employed include frequency counts, Chi-Square and five (5) point Likert ... characteristics of respondents and their herd size, hence snail productivity. ... The study identifies housing, management and pest control as areas of ...

  19. Snails, stable iostopes, and southwestern desert paleoclimates

    Energy Technology Data Exchange (ETDEWEB)

    Sharpe, S.E. [Univ. and Community College System of Nevada, Reno, NV (United States); Whelan, J.F.; Forester, R.M.; Burdett, J.

    1995-09-01

    Modern and fossil molluscs (snails) occur in many localities in and semi-arid regions throughout the desert southwest. Live terrestrial snails are found under rocks and in forest litter and aquatic taxa inhabit springs, seeps, and/or wetlands. Molluscs uptake local water during their growing season (spring and summer) and incorporate its delta 180 signature into their shells. Preliminary 180 analysis of modem shells from the southern Great Basin indicates that the shells probably reflect meteoric water 180 values during the growing season. This provides a way to estimate the delta 180 value of precipitation and, thereby, the source of the moisture-bearing air masses. Significant 180 variability in shells analyzed include geographic location, elevation, taxonomy, and habitat (terrestrial, spring, or wetland). We found a rough inverse correlation with elevation in modem shells from the Spring Range in southern Nevada. The delta 180 values of modem and fossil shells are also very different; modem values in this location are much higher than those from nearby late Pleistocene-age molluscs suggesting that the Pleistocene summers were variously colder and wetter than today or less evaporative (more humid). Assuming shell material directly reflects the 180 of the growing-season environment, comparison of modem and fossil shell delta 180 values can potentially identify changes in air-mass moisture sources and can help to define seasonal precipitation change through time. Comprehension and quantification of community and isotopic variability in modem gastropods is required to create probabilistic valid transfer functions with fossil materials. Valid inferences about past environmental conditions can then be established with known confidence limits.

  20. The Secrets Behind Vegetation Control on Snail Fever

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Oncomelania (Oncomelania hupensis), a dioecian, ovoviviparous, and amphibious snail, is the sole intermediate host of Schistosoma japonicum, the most wide-spread snail fever in the world. Chemical eliminating the host proved unacceptable for there was severe contamination to water and soil. The river beaches and the delta areas of five provinces in the middle and lower reaches of Yangtze River in China provide the most favorable habitats for Oncomelania. Our studies have revealed that the occurrence of ...

  1. Snail levels control the migration mechanism of mesenchymal tumor cells.

    Science.gov (United States)

    Belgiovine, Cristina; Chiesa, Giulio; Chiodi, Ilaria; Frapolli, Roberta; Bonezzi, Katiuscia; Taraboletti, Giulia; D'Incalci, Maurizio; Mondello, Chiara

    2016-07-01

    Cancer cells use two major types of movement: Mesenchymal, which is typical of cells of mesenchymal origin and depends on matrix metalloproteinase (MMP) activity, and amoeboid, which is characteristic of cells with a rounded shape and relies on the activity of Rho-associated kinase (ROCK). The present authors previously demonstrated that, during neoplastic transformation, telomerase-immortalized human fibroblasts (cen3tel cells) acquired a ROCK-dependent/MMP independent mechanism of invasion, mediated by the downregulation of the ROCK cellular inhibitor Round (Rnd)3/RhoE. In the present study, cen3tel transformation was also demonstrated to be paralleled by downregulation of Snail, a major determinant of the mesenchymal movement. To test whether Snail levels could determine the type of movement adopted by mesenchymal tumor cells, Snail was ectopically expressed in tumorigenic cells. It was observed that ectopic Snail did not increase the levels of typical mesenchymal markers, but induced cells to adopt an MMP-dependent mechanism of invasion. In cells expressing ectopic Snail, invasion became sensitive to the MMP inhibitor Ro 28-2653 and insensitive to the ROCK inhibitor Y27632, suggesting that, once induced by Snail, the mesenchymal movement prevails over the amoeboid one. Snail-expressing cells had a more aggressive behavior in vivo, and exhibited increased tumor growth rate and metastatic ability. These results confirm the high plasticity of cancer cells, which can adopt different types of movement in response to changes in the expression of specific genes. Furthermore, the present findings indicate that Rnd3 and Snail are possible regulators of the type of invasion mechanism adopted by mesenchymal tumor cells.

  2. Molluscicidal activity of chlorophyll extraction against the freshwater snails

    Institute of Scientific and Technical Information of China (English)

    Mona Said Mahmoud; Peter Richter; Hatem Abdel Mawgoud Shalaby; Omnia Mohamed Kandil; Donat-Peter Hder

    2013-01-01

    Objective: To evaluate the molluscicidal activity of chlorophyll extract as a photodynamic substance against the snails Lymnaea stagnalis, Biomphalaria spp. and Physa marmorata.Methods:Chlorophyllin was extracted from deep-frozen spinach. Snails were incubated in chlorophyllin containing water with 2.5, 5.0, 10.0 and 15.0 µg/mL. All samples were kept in darkness overnight for incubation. After incubation, three samples were irradiated with simulated solar radiation for 3 h. After irradiation, the vitality of the organisms was determined. Results: The photodynamically active chlorophyllin, at low concentrations, was able to kill snails within a few hours under exposure of solar radiation. Besides, it had a killing effect by about 70%and 100% on the snails’ eggs and the newly hatched snails, respectively, after 3 h exposure to solar radiation.Conclusion:The derivates of chlorophyll was a very interesting substance for photodynamic freshwater snail control. Hence, it might be a promising and cheap new strategy which probably had the potential to replace the synthetic molluscicides for snail control.

  3. Molluscicidal activity of chlorophyll extraction against the freshwater snails

    Directory of Open Access Journals (Sweden)

    Mona Said Mahmoud

    2013-09-01

    Full Text Available Objective: To evaluate the molluscicidal activity of chlorophyll extract as a photodynamic substance against the snails Lymnaea stagnalis, Biomphalaria spp. and Physa marmorata. Methods: Chlorophyllin was extracted from deep-frozen spinach. Snails were incubated in chlorophyllin containing water with 2.5, 5.0, 10.0 and 15.0 µg/mL. All samples were kept in darkness overnight for incubation. After incubation, three samples were irradiated with simulated solar radiation for 3 h. After irradiation, the vitality of the organisms was determined. Results: The photodynamically active chlorophyllin, at low concentrations, was able to kill snails within a few hours under exposure of solar radiation. Besides, it had a killing effect by about 70% and 100% on the snails’ eggs and the newly hatched snails, respectively, after 3 h exposure to solar radiation. Conclusion: The derivates of chlorophyll was a very interesting substance for photodynamic freshwater snail control. Hence, it might be a promising and cheap new strategy which probably had the potential to replace the synthetic molluscicides for snail control.

  4. Crawling beneath the free surface: Water snail locomotion

    CERN Document Server

    Lee, Sungyon; Hosoi, A E; Lauga, Eric

    2008-01-01

    Land snails move via adhesive locomotion. Through muscular contraction and expansion of their foot, they transmit waves of shear stress through a thin layer of mucus onto a solid substrate. Since a free surface cannot support shear stress, adhesive locomotion is not a viable propulsion mechanism for water snails that travel inverted beneath the free surface. Nevertheless, the motion of the freshwater snail, Sorbeoconcha physidae, is reminiscent of that of its terrestrial counterparts, being generated by the undulation of the snail foot that is separated from the free surface by a thin layer of mucus. Here, a lubrication model is used to describe the mucus flow in the limit of small amplitude interfacial deformations. By assuming the shape of the snail foot to be a traveling sine wave and the mucus to be Newtonian, an evolution equation for the interface shape is obtained and the resulting propulsive force on the snail is calculated. This propulsive force is found to be non-zero for moderate values of Capillar...

  5. The competitive interaction of snails Thiara scabra and Physa doopi on the snail Lymnaea rubiginosa under laboratory conditions

    Directory of Open Access Journals (Sweden)

    Sarwitri Endah Estuningsih

    1998-03-01

    Full Text Available The competitive interaction of the snails Thiara scabra and Physa doopi against the snail Lymnaea rubiginosa, the intermediate host ofFasciola gigantica has been studied. Aquaria, 60 x 40 x 20 cm and 30 x 20 x 10 cm in size were used, and the two snail species were introduced in different proportion . The results over a one year period showed that the competition between snail L. rubiginosa and T. scabra or P. doopi has started after 8 months as demonstrated by the reduction of the population ofL. rubiginosa and increasing the population of T. scabra or P. doopi. The competitive interaction does not seem to be due to competition for food but to a chemical factors, possibly water-soluble pheromones. The other explanation is discussed .

  6. Context trees

    OpenAIRE

    Ganzinger, Harald; Nieuwenhuis, Robert; Nivela, Pilar

    2001-01-01

    Indexing data structures are well-known to be crucial for the efficiency of the current state-of-the-art theorem provers. Examples are \\emph{discrimination trees}, which are like tries where terms are seen as strings and common prefixes are shared, and \\emph{substitution trees}, where terms keep their tree structure and all common \\emph{contexts} can be shared. Here we describe a new indexing data structure, \\emph{context trees}, where, by means of a limited kind of conte...

  7. Two Trees

    OpenAIRE

    Cochrane, John. H.; Longstaff, Francis A.; Santa-Clara, Pedro

    2004-01-01

    We solve a model with two “Lucas trees.†Each tree has i.i.d. dividend growth. The investor has log utility and consumes the sum of the two trees’ dividends. This model produces interesting asset-pricing dynamics, despite its simple ingredients. Investors want to rebalance their portfolios after any change in value. Since the size of the trees is fixed, however, prices must adjust to offset this desire. As a result, expected returns, excess returns, and return volatility all vary throug...

  8. Effects of defect creation on bidirectional behavior with hump characteristics of InGaZnO TFTs under bias and thermal stress

    Science.gov (United States)

    Im, Hwarim; Song, Hyunsoo; Jeong, Jaewook; Hong, Yewon; Hong, Yongtaek

    2015-03-01

    We investigated the hump characteristics of amorphous indium-gallium-zinc oxide thin-film transistors. The device showed a field effect mobility of 24.3 cm2 V-1 s-1, a threshold voltage (Vth) of 4.8 V, and a subthreshold swing of 120 mV/dec. Under positive gate bias stress, Vth showed bidirectional shift with a hump. Vth was positively and negatively shifted in the above-threshold and subthreshold regions, respectively. At high temperatures, Vth was more positively shifted without bidirectional shift. Under simultaneous drain bias stress (VDS,stress), the hump was maintained. However, the bidirectional shift was not observed with an increasing VDS,stress. The hump and positive shift are related to the defect creation of the shallow donor-like and deep-level acceptor-like states, respectively. We performed a two-dimensional device simulation to further investigate this phenomenon. By varying the peak values of the Gaussian shallow donor-like and deep acceptor-like states, we qualitatively confirmed the relationship between the two states and transfer curve changes.

  9. Effect of wall cooling on the stability of compressible subsonic flows over smooth humps and backward-facing steps

    Science.gov (United States)

    Al-Maaitah, Ayman A.; Nayfeh, Ali H.; Ragab, Saad A.

    1990-01-01

    The effect of wall cooling on the two-dimensional linear stability of subsonic flows over two-dimensional surface imperfections is investigated. Results are presented for flows over smooth humps and backward-facing steps with Mach numbers up to 0.8. The results show that, whereas cooling decreases the viscous instability, it increases the shear-layer instability and hence it increases the growth rates in the separation region. The coexistence of more than one instability mechanism makes a certain degree of wall cooling most effective. For the Mach numbers 0.5 and 0.8, the optimum wall temperatures are about 80 pct and 60 pct of the adiabatic wall temperature, respectively. Increasing the Mach number decreases the effectiveness of cooling slightly and reduces the optimum wall temperature.

  10. Relation between the "Double-Hump" Behavior in the Radio Band and the Broad-Line Luminosity for Blazars

    Institute of Scientific and Technical Information of China (English)

    Zhao-Hua Xie; Hong Dai; Jian-Ming Hao; Lei-Ming Du; Xiong Zhang

    2007-01-01

    The physics behind the spectral energy distribution (SED) of blazars remains open.We assembled 36 blazars to tackle the factors that control their SED. Now, many blazar spectra have the "double hump" feature in the radio and far-IR frequencies. For these a parameter,△, is created to characterize the behavior of the SED. We found a significant correlation between the broad-line luminosity (LBLR) and △. Because LBLR is an indicator of the accreting power of the source in blazars, we derived a linear correlation,△∝ (M)1/3. 18, which suggests that the SED of blazars may depend on the accretion rate, like that of BL Lac objects. We also found a significant correlation between (m) and△ for a sample of 11 blazars (out of one of 36)with available black hole masses. This implies the Eddington accretion ratio may influence the shape of the SED of blazars.

  11. The evolution of reproductive isolation in a simultaneous hermaphrodite, the freshwater snail Physa

    Directory of Open Access Journals (Sweden)

    Lydeard Charles

    2011-05-01

    Full Text Available Abstract Background The cosmopolitan freshwater snail Physa acuta has recently found widespread use as a model organism for the study of mating systems and reproductive allocation. Mitochondrial DNA phylogenies suggest that Physa carolinae, recently described from the American southeast, is a sister species of P. acuta. The divergence of the acuta/carolinae ancestor from the more widespread P. pomilia appears to be somewhat older, and the split between a hypothetical acuta/carolinae/pomilia ancestor and P. gyrina appears older still. Results Here we report the results of no-choice mating experiments yielding no evidence of hybridization between gyrina and any of four other populations (pomilia, carolinae, Philadelphia acuta, or Charleston acuta, nor between pomilia and carolinae. Crosses between pomilia and both acuta populations yielded sterile F1 progeny with reduced viability, while crosses between carolinae and both acuta populations yielded sterile F1 hybrids of normal viability. A set of mate-choice tests also revealed significant sexual isolation between gyrina and all four of our other Physa populations, between pomilia and carolinae, and between pomilia and Charleston acuta, but not between pomilia and the acuta population from Philadelphia, nor between carolinae and either acuta population. These observations are consistent with the origin of hybrid sterility prior to hybrid inviability, and a hypothesis that speciation between pomilia and acuta may have been reinforced by selection for prezygotic reproductive isolation in sympatry. Conclusions We propose a two-factor model for the evolution of postzygotic reproductive incompatibility in this set of five Physa populations consistent with the Dobzhansky-Muller model of speciation, and a second two-factor model for the evolution of sexual incompatibility. Under these models, species trees may be said to correspond with gene trees in American populations of the freshwater snail, Physa.

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

    Science.gov (United States)

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

    2010-01-01

    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.

  13. Talking Trees

    Science.gov (United States)

    Tolman, Marvin

    2005-01-01

    Students love outdoor activities and will love them even more when they build confidence in their tree identification and measurement skills. Through these activities, students will learn to identify the major characteristics of trees and discover how the pace--a nonstandard measuring unit--can be used to estimate not only distances but also the…

  14. Functional changes in the snail statocyst system elicited by microgravity.

    Directory of Open Access Journals (Sweden)

    Pavel M Balaban

    Full Text Available BACKGROUND: The mollusk statocyst is a mechanosensing organ detecting the animal's orientation with respect to gravity. This system has clear similarities to its vertebrate counterparts: a weight-lending mass, an epithelial layer containing small supporting cells and the large sensory hair cells, and an output eliciting compensatory body reflexes to perturbations. METHODOLOGY/PRINCIPAL FINDINGS: In terrestrial gastropod snail we studied the impact of 16- (Foton M-2 and 12-day (Foton M-3 exposure to microgravity in unmanned orbital missions on: (i the whole animal behavior (Helix lucorum L., (ii the statoreceptor responses to tilt in an isolated neural preparation (Helix lucorum L., and (iii the differential expression of the Helix pedal peptide (HPep and the tetrapeptide FMRFamide genes in neural structures (Helix aspersa L.. Experiments were performed 13-42 hours after return to Earth. Latency of body re-orientation to sudden 90° head-down pitch was significantly reduced in postflight snails indicating an enhanced negative gravitaxis response. Statoreceptor responses to tilt in postflight snails were independent of motion direction, in contrast to a directional preference observed in control animals. Positive relation between tilt velocity and firing rate was observed in both control and postflight snails, but the response magnitude was significantly larger in postflight snails indicating an enhanced sensitivity to acceleration. A significant increase in mRNA expression of the gene encoding HPep, a peptide linked to ciliary beating, in statoreceptors was observed in postflight snails; no differential expression of the gene encoding FMRFamide, a possible neurotransmission modulator, was observed. CONCLUSIONS/SIGNIFICANCE: Upregulation of statocyst function in snails following microgravity exposure parallels that observed in vertebrates suggesting fundamental principles underlie gravi-sensing and the organism's ability to adapt to gravity

  15. Functional changes in the snail statocyst system elicited by microgravity.

    Science.gov (United States)

    Balaban, Pavel M; Malyshev, Aleksey Y; Ierusalimsky, Victor N; Aseyev, Nikolay; Korshunova, Tania A; Bravarenko, Natasha I; Lemak, M S; Roshchin, Matvey; Zakharov, Igor S; Popova, Yekaterina; Boyle, Richard

    2011-03-29

    The mollusk statocyst is a mechanosensing organ detecting the animal's orientation with respect to gravity. This system has clear similarities to its vertebrate counterparts: a weight-lending mass, an epithelial layer containing small supporting cells and the large sensory hair cells, and an output eliciting compensatory body reflexes to perturbations. In terrestrial gastropod snail we studied the impact of 16- (Foton M-2) and 12-day (Foton M-3) exposure to microgravity in unmanned orbital missions on: (i) the whole animal behavior (Helix lucorum L.), (ii) the statoreceptor responses to tilt in an isolated neural preparation (Helix lucorum L.), and (iii) the differential expression of the Helix pedal peptide (HPep) and the tetrapeptide FMRFamide genes in neural structures (Helix aspersa L.). Experiments were performed 13-42 hours after return to Earth. Latency of body re-orientation to sudden 90° head-down pitch was significantly reduced in postflight snails indicating an enhanced negative gravitaxis response. Statoreceptor responses to tilt in postflight snails were independent of motion direction, in contrast to a directional preference observed in control animals. Positive relation between tilt velocity and firing rate was observed in both control and postflight snails, but the response magnitude was significantly larger in postflight snails indicating an enhanced sensitivity to acceleration. A significant increase in mRNA expression of the gene encoding HPep, a peptide linked to ciliary beating, in statoreceptors was observed in postflight snails; no differential expression of the gene encoding FMRFamide, a possible neurotransmission modulator, was observed. Upregulation of statocyst function in snails following microgravity exposure parallels that observed in vertebrates suggesting fundamental principles underlie gravi-sensing and the organism's ability to adapt to gravity changes. This simple animal model offers the possibility to describe general

  16. Mass migration of juvenile Biomphalaria glabrata snails bred under semi-natural conditions

    OpenAIRE

    Frederico Simões Barbosa

    1989-01-01

    For the development of studies on snail interspecific competition special in-door laboratory channels were built. In the all five channels seeded with adult specimens of Biomphalaria glabrata mass migration of juvenile snails outside the water was observed. Most of the migrant snails presented apertural lamellae. Data collected during the period of two years, showed the regression of the migration phenomenon and the disappearance of the lamellate snails.

  17. The freshwater snail lymnaea rubiginosa as an experimental host of Angiostrongylus malaysiensis: a preliminary report.

    Science.gov (United States)

    Dondero, T J; Lim, B L

    1976-03-01

    Preliminary studies have shown that Lymnaea rubiginosa, a common fresh-water snail in Peninsular Malaysia, which is easily colonized and reared in the laboratory, is a capable experimental intermediate host for Angiostrongylus malaysiensis. Overall 73% of the snails tested became infected following 6 hours exposure to infective rat faeces. Higher infection rates, up to 100%, and heavier worm loads, occurred among the larger sized snails. Snail attrition was low except when very heavy worm loads were acquired.

  18. Phylogenetic trees

    OpenAIRE

    Baños, Hector; Bushek, Nathaniel; Davidson, Ruth; Gross, Elizabeth; Harris, Pamela E.; Krone, Robert; Long, Colby; Stewart, Allen; WALKER, Robert

    2016-01-01

    We introduce the package PhylogeneticTrees for Macaulay2 which allows users to compute phylogenetic invariants for group-based tree models. We provide some background information on phylogenetic algebraic geometry and show how the package PhylogeneticTrees can be used to calculate a generating set for a phylogenetic ideal as well as a lower bound for its dimension. Finally, we show how methods within the package can be used to compute a generating set for the join of any two ideals.

  19. Implication of snail in metabolic stress-induced necrosis.

    Directory of Open Access Journals (Sweden)

    Cho Hee Kim

    Full Text Available BACKGROUND: Necrosis, a type of cell death accompanied by the rupture of the plasma membrane, promotes tumor progression and aggressiveness by releasing the pro-inflammatory and angiogenic cytokine high mobility group box 1. It is commonly found in the core region of solid tumors due to hypoxia and glucose depletion (GD resulting from insufficient vascularization. Thus, metabolic stress-induced necrosis has important clinical implications for tumor development; however, its regulatory mechanisms have been poorly investigated. METHODOLOGY/PRINCIPAL FINDINGS: Here, we show that the transcription factor Snail, a key regulator of epithelial-mesenchymal transition, is induced in a reactive oxygen species (ROS-dependent manner in both two-dimensional culture of cancer cells, including A549, HepG2, and MDA-MB-231, in response to GD and the inner regions of a multicellular tumor spheroid system, an in vitro model of solid tumors and of human tumors. Snail short hairpin (sh RNA inhibited metabolic stress-induced necrosis in two-dimensional cell culture and in multicellular tumor spheroid system. Snail shRNA-mediated necrosis inhibition appeared to be linked to its ability to suppress metabolic stress-induced mitochondrial ROS production, loss of mitochondrial membrane potential, and mitochondrial permeability transition, which are the primary events that trigger necrosis. CONCLUSIONS/SIGNIFICANCE: Taken together, our findings demonstrate that Snail is implicated in metabolic stress-induced necrosis, providing a new function for Snail in tumor progression.

  20. Effect of steamed sago and golden snail flour as substitution of yellow corn on performance of male duck of Alabio, Mojosari and MA

    Directory of Open Access Journals (Sweden)

    Ahmad Subhan

    2010-06-01

    Full Text Available This study was aimed at finding out the effects of combining steaming sago (Metroxylon Spp and golden snail flour (Pomacea Spp as the source of energy in duck ration, substituting yellow corn, on the performance of male Alabio, Mojosari, and their cross (MA. One hundred and ninety two young male ducks from the three breeds of 7 days old were assigned in 48 units of cage (4 ducks/cage. Research method applied was Completely Randomized Design with factorial pattern (3x4. The first factor was duck breeds (a consisted of tree duck breeds: Alabio duck, Mojosari duck and Raja duck and the second factor was types of ration: R0 (control/100% basal ration, R1 (basal ration + 13% steaming sago and 2% golden snail flour, R2 (basal ration + 26% steaming sago and 4% golden snail flour and R3 (basal ration + 39% steaming sago and 6% golden snail flour. All treatments were repeated four times. The observed variables were performance of ducks: body weight, body weight gain, ration consumption and ration conversion. Results indicated that breed had significant effect (P < 0.05 on body weight, body weight gain and ration conversion. Meanwhile, ration had significant effect (P < 0.05 on ration consumption, body weight gain, and final body weight. It is concluded that the combination of steaming sago and golden snail flour up to 45% of the ration could replace the need for yellow corn as the source of energy in the ration without affecting the performance of male ducks of 1 – 8 weeks old. Cross male ducks were better than that male Alabio ducks and Mojosari because they were more efficient in converting ration into meat which resulted in higher body weight gain.

  1. 76 FR 31866 - Endangered and Threatened Wildlife and Plants; Reclassification of the Tulotoma Snail From...

    Science.gov (United States)

    2011-06-02

    ...; Reclassification of the Tulotoma Snail From Endangered to Threatened AGENCY: Fish and Wildlife Service, Interior... snail (Tulotoma magnifica) from endangered to threatened, under the authority of the Endangered Species... this snail. DATES: This final rule is effective on July 5, 2011. ADDRESSES: This final rule...

  2. New scope on the relationship between rotifers and Biomphalaria alexandrina snails

    Institute of Scientific and Technical Information of China (English)

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

    2013-01-01

    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.

  3. 75 FR 35424 - Endangered and Threatened Wildlife and Plants; Proposed Reclassification of the Tulotoma Snail...

    Science.gov (United States)

    2010-06-22

    ...; Proposed Reclassification of the Tulotoma Snail From Endangered to Threatened AGENCY: Fish and Wildlife...), propose to reclassify the tulotoma snail (Tulotoma magnifica) from endangered to threatened, under the... no longer correctly reflects the status of this snail. We have documented a substantial...

  4. The faucet snail (Bithynia tentaculata) invades the St. Louis River Estuary

    Science.gov (United States)

    The European-origin faucet snail (Bithynia tentaculata) now numbers among the aquatic invasive species present in the St. Louis River Estuary. This snail has been in the lower Great Lakes since the early 20th century but is new to the Lake Superior basin. We found faucet snails...

  5. Game tree algorithms and solution trees

    NARCIS (Netherlands)

    W.H.L.M. Pijls (Wim); A. de Bruin (Arie)

    1998-01-01

    textabstractIn this paper, a theory of game tree algorithms is presented, entirely based upon the concept of solution tree. Two types of solution trees are distinguished: max and min trees. Every game tree algorithm tries to prune nodes as many as possible from the game tree. A cut-off criterion in

  6. Electron Tree

    DEFF Research Database (Denmark)

    Appelt, Ane L; Rønde, Heidi S

    2013-01-01

    The photo shows a close-up of a Lichtenberg figure – popularly called an “electron tree” – produced in a cylinder of polymethyl methacrylate (PMMA). Electron trees are created by irradiating a suitable insulating material, in this case PMMA, with an intense high energy electron beam. Upon discharge......, during dielectric breakdown in the material, the electrons generate branching chains of fractures on leaving the PMMA, producing the tree pattern seen. To be able to create electron trees with a clinical linear accelerator, one needs to access the primary electron beam used for photon treatments. We...... appropriated a linac that was being decommissioned in our department and dismantled the head to circumvent the target and ion chambers. This is one of 24 electron trees produced before we had to stop the fun and allow the rest of the accelerator to be disassembled....

  7. Electron Tree

    DEFF Research Database (Denmark)

    Appelt, Ane L; Rønde, Heidi S

    2013-01-01

    The photo shows a close-up of a Lichtenberg figure – popularly called an “electron tree” – produced in a cylinder of polymethyl methacrylate (PMMA). Electron trees are created by irradiating a suitable insulating material, in this case PMMA, with an intense high energy electron beam. Upon discharge......, during dielectric breakdown in the material, the electrons generate branching chains of fractures on leaving the PMMA, producing the tree pattern seen. To be able to create electron trees with a clinical linear accelerator, one needs to access the primary electron beam used for photon treatments. We...... appropriated a linac that was being decommissioned in our department and dismantled the head to circumvent the target and ion chambers. This is one of 24 electron trees produced before we had to stop the fun and allow the rest of the accelerator to be disassembled....

  8. MTA3 regulates CGB5 and Snail genes in trophoblast

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Ying [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); 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); Kurahashi, Hiroki [Division of Molecular Genetics, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake (Japan); Leach, Richard, E-mail: Richard.Leach@hc.msu.edu [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: Kai.Wang@hc.msu.edu [Department of Obstetrics, Gynecology and Reproductive Biology, Michigan State University, Grand Rapids, MI 49503 (United States)

    2013-04-19

    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 β-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

  9. Compatibility and sex in a snail-schistosome system.

    Science.gov (United States)

    Webster, J P

    2001-04-01

    Knowledge of the genetics underlying resistance to parasitic infection has important repercussions for our understanding of infection dynamics and the mechanisms of host-parasite co-evolution. The aim here was to determine for a Biomphalaria glabrato-Schistosoma mansoni system whether (1) resistance is dominant over susceptibility, (2) it is possible to crossbreed snails to be simultaneously resistant and/or susceptible to more than one parasite strain and (3) compatibility genotype affects reproductive strategy. Using replicate snail strains artificially selected for either resistance or susceptibility to single replicate parasite strains, individual snails from each line were paired with a selected partner of matched or non-matched compatibility status and cross-breeding was identified by RAPD-PCR. The resulting compatibility phenotype of all offspring was determined. Support for all 3 hypotheses were obtained. The results are discussed in terms of their applied and theoretical implications.

  10. Effects of trematode parasitism on the shell morphology of snails from flow and nonflow environments.

    Science.gov (United States)

    Gustafson, Kyle D; Bolek, Matthew G

    2016-03-01

    The primary function of the gastropod shell is protection. However, shells that function well in one environment may be maladaptive in another. Upon infection, the snail shell protects internal parasites and it is to the parasite's advantage to optimize, or not interfere with, shell functionality. However, parasites, particularly trematodes, are often pathogenic and it is not clear if parasitism will induce environment-dependent or -independent changes to gastropod shells. We conducted a field study and a complementary laboratory experiment to examine the effects of trematode parasitism on shell characteristics (shape, size, and crush resistance) of Physa acuta snails in flow and nonflow environments using geometric morphometrics and crush assays. Field results indicate wetland (nonflow) snails had large, crush resistant shells with narrow apertures and tall spires. In contrast, stream (flow) snails had small, weak shells with wide apertures and short spires. Parasitism had no apparent effect on the crush resistance of wetland snails but significantly reduced the crush resistance of stream snails. Parasitism had no significant effect on overall shell shape in stream or wetland snails. Similar to the results of our field study, nonflow tank snails had significantly more crush resistant shells than flow tank snails. Additionally, the shapes of flow and nonflow tank snails significantly differed where nonflow tank snails resembled wetland snails and flow tank snails resembled stream snails. For laboratory snails, parasitism reduced crush resistance regardless of flow/nonflow treatment. Our results demonstrate that habitat and/or flow treatment was the primary factor affecting P. acuta shell morphology and that trematode parasitism played a secondary role.

  11. Negative Regulatory Role of TWIST1 on SNAIL Gene Expression.

    Science.gov (United States)

    Forghanifard, Mohammad Mahdi; Ardalan Khales, Sima; Farshchian, Moein; Rad, Abolfazl; Homayouni-Tabrizi, Masoud; Abbaszadegan, Mohammad Reza

    2017-01-01

    Epithelial-mesenchymal transition (EMT) is crucial for specific morphogenetic movements during embryonic development as well as pathological processes of tumor cell invasion and metastasis. TWIST and SNAIL play vital roles in both developmental and pathological EMT. Our aim in this study was to investigate the functional correlation between TWIST1 and SNAIL in human ESCC cell line (KYSE-30). The packaging cell line GP293T was cotransfected with either control retroviral pruf-IRES-GFP plasmid or pruf-IRES-GFP-hTWIST1 and pGP plasmid. The KYSE-30 ESCC cells were transduced with produced viral particles and examined with inverted fluorescence microscope. DNA was extracted from transduced KYSE-30 cells and analyzed for copy number of integrated retroviral sequences in the target cell genome. The concentration of retroviral particles was determined by Real-time PCR. After RNA extraction and cDNA synthesis, the mRNA expression of TWIST1 and SNAIL was assessed by comparative real-time PCR amplification. Ectopic expression of TWIST1 in KYSE-30, dramatically reduces SNAIL expression. Retroviral transduction enforced TWIST1 overexpression in GFP-hTWIST1 nearly 9 folds in comparison with GFP control cells, and interestingly, this TWIST1 enforced expression caused a - 7 fold decrease of SNAIL mRNA expression in GFP-hTWIST1 compared to GFP control cells. Inverse correlation of TWIST1 and SNAIL mRNA levels may introduce novel molecular gene expression pathway controlling EMT process during ESCC aggressiveness and tumorigenesis. Consequently, these data extend the spectrum of biological activities of TWIST1 and propose that therapeutic repression of TWIST1 may be an effective strategy to inhibit cancer cell invasion and metastasis.

  12. Some quality parameters of land snail meat - Helix pomatia

    Directory of Open Access Journals (Sweden)

    Tojagić Slobodan N.

    2004-01-01

    Full Text Available Considering the tradition in our regions to collect land snails (Helix pomatia for export, which is "disrupted" by social control resulting in limited possibilities to develop this attractive activity, there is a great interest lately for land snail breeding and fattening at farms. For this reason it is necessary to investigate systematically the possibilities to develop this activity in a longer period and in larger areas. The first investigations, although covering only nutritive and health safety aspects of the edible parts yielded the results presented in this work. Chemical composition, the content of some elements and organochlorine insecticides were followed as unavoidable in human living and environment.

  13. Ivermectin efficacy against Biomphalaria, intermediate host snail vectors of Schistosomiasis.

    Science.gov (United States)

    Katz, Naftale; Araújo, Neusa; Coelho, Paulo Marcos Zech; Morel, Carlos Medicis; Linde-Arias, Ana Rosa; Yamada, Takeshi; Horimatsu, Yuki; Suzuki, Koh; Sunazuka, Toshiaki; Ōmura, Satoshi

    2017-03-15

    The impact of ivermectin on adult snails of the genus Biomphalaria (B. glabrata, B. tenagophila and B. straminea), B. glabrata infected with Schistosoma mansoni, snail egg-masses cercariae and miracidia, as well as on guppy fish (Poecilia reticulata) was examined and evaluated. Biomphalaria snails, egg-masses, parasite stages and guppies were all exposed to different concentrations of ivermectin for 24 h, followed by regular observations of mortality. The calculated lethal doses of ivermectin were around an LD50 of 0.03 μg ml(-1), and an LD90 of 0.3 μg ml(-1) for the three species of snails. Specimens of B. glabrata actually shedding parasite cercariae all died when exposed to ivermectin at a concentration of a mere 0.01 μg ml(-1). Ivermectin B1a, the major (80%) component of commercially available ivermectin, proved to be inactive, and it was the minor (20%) component, ivermectin B1b, which caused snail death. Snail egg-masses were not affected, even at the highest concentration of 100 μg ml(-1). With respect to S. mansoni parasite stages, 0.2 μg ml(-1) ivermectin killed 50% of cercariae and miracidia within five minutes, rising to 90% after 30 min. Mortality of guppy fish within 24 h of exposure to ivermectin at concentrations of 0.5 μg ml(-1) and 0.01 μg ml(-1), were 100% and 30%, respectively. The concentration of 0.01 μg ml(-1) that killed Schistosoma mansoni-infected snails only caused 30% mortality in guppy fish. Ivermectin can be considered a promising molluscicide, especially as it is more potent against infected snails than uninfected ones, although it has no impact on egg-masses. Ivermectin and its derivatives could be explored in the search for a new agent to help control schistosomiasis transmission.The Journal of Antibiotics advance online publication, 15 March 2017; doi:10.1038/ja.2017.31.

  14. One-trial reward learning in the snail Lymnea stagnalis.

    Science.gov (United States)

    Alexander, J; Audesirk, T E; Audesirk, G J

    1984-01-01

    We present evidence that the pond snail Lymnaea stagnalis is capable of aquisition and extensive retention of an appetitively reinforced feeding response after only a single training trial. Food-deprived snails presented with a single pairing of a phagostimulant (a mixture of sucrose and casein digest) and a novel, non-food chemostimulus (amyl acetate) subsequently made feeding responses to the amyl acetate and retained the association for at least 19 days. This demonstration of one-trial, non-aversive classical conditioning enhances the utility of Lymnaea stagnalis as a model system for the detailed analysis of neural mechanisms underlying plasticity.

  15. Dip-Hump Temperature Dependence of Specific Heat and Effects of Pairing Fluctuations in the Weak-Coupling Side of a P-Wave Interacting Fermi Gas

    Science.gov (United States)

    Inotani, Daisuke; van Wyk, Pieter; Ohashi, Yoji

    2016-12-01

    We investigate the specific heat CV at constant volume in the normal state of a p-wave interacting Fermi gas. Including p-wave pairing fluctuations within the strong-coupling theory developed by Nozières and Schmitt-Rink, we show that, in the weak-coupling side, CV exhibits a dip-hump behavior as a function of the temperature. While the dip is associated with the pseudogap phenomenon near Tc, the hump structure is found to come from the suppression of Fermi quasiparticle scattering into a p-wave molecular state in the Fermi degenerate regime. Since the latter phenomenon does not occur in the ordinary s-wave interacting Fermi gas, it may be viewed as a characteristic phenomenon associated with a p-wave pairing interaction.

  16. Interpreting Tree Ensembles with inTrees

    OpenAIRE

    Deng, Houtao

    2014-01-01

    Tree ensembles such as random forests and boosted trees are accurate but difficult to understand, debug and deploy. In this work, we provide the inTrees (interpretable trees) framework that extracts, measures, prunes and selects rules from a tree ensemble, and calculates frequent variable interactions. An rule-based learner, referred to as the simplified tree ensemble learner (STEL), can also be formed and used for future prediction. The inTrees framework can applied to both classification an...

  17. Intraguild predation by shore crabs affects mortality, behavior, growth, and densities of California horn snails

    Science.gov (United States)

    Lorda, J.; Hechinger, R.F.; Cooper, S. D.; Kuris, A. M.; Lafferty, Kevin D.

    2016-01-01

    The California horn snail, Cerithideopsis californica, and the shore crabs, Pachygrapsus crassipesand Hemigrapsus oregonensis, compete for epibenthic microalgae, but the crabs also eat snails. Such intraguild predation is common in nature, despite models predicting instability. Using a series of manipulations and field surveys, we examined intraguild predation from several angles, including the effects of stage-dependent predation along with direct consumptive and nonconsumptive predator effects on intraguild prey. In the laboratory, we found that crabs fed on macroalgae, snail eggs, and snails, and the size of consumed snails increased with predator crab size. In field experiments, snails grew less in the presence of crabs partially because snails behaved differently and were buried in the sediment (nonconsumptive effects). Consistent with these results, crab and snail abundances were negatively correlated in three field surveys conducted at three different spatial scales in estuaries of California, Baja California, and Baja California Sur: (1) among 61 sites spanning multiple habitat types in three estuaries, (2) among the habitats of 13 estuaries, and (3) among 34 tidal creek sites in one estuary. These results indicate that shore crabs are intraguild predators on California horn snails that affect snail populations via predation and by influencing snail behavior and performance.

  18. Microbiological quality of raw and processed wild and cultured edible snails.

    Science.gov (United States)

    Parlapani, Foteini F; Neofitou, Christos; Boziaris, Ioannis S

    2014-03-15

    An increasing interest in snail farming in Greece and other European countries has been observed. Despite the fact that edible snails have been involved with problems of Salmonella spp. contamination, there are to our knowledge only limited studies regarding microbiological safety and hygiene of such products. Enumeration of microbial populations and presence/absence of Salmonella spp. in snail meat and intestines of wild Cornu aspersum, Helix lucorum and cultured Cornu aspersum snails from indoor/outdoor type farms was conducted. Furthermore, snail-processing steps were simulated in the laboratory and the population reduction in snail meat was determined. Microbial populations were higher in intestines than snail meat in almost all cases. Escherichia coli/coliforms and Enterococcus spp. populations were lower in the intestines and snail meat of cultured C. aspersum. Salmonella spp. were detected in the intestines and snail meat of wild snails only. The high levels of bacterial populations were considerably reduced after the appropriate processing. The lower populations of E. coli/coliforms, Enterococcus spp. and especially the absence of Salmonella spp. in cultured snails show that the controlled conditions decrease the possibility of pathogen presence and contribute to food safety and public health. © 2013 Society of Chemical Industry.

  19. Expression and activity of SNAIL transcription factor during Epithelial to Mesenchymal Transition (EMT) in cancer progression.

    Science.gov (United States)

    Papiewska-Pająk, Izabela; Kowalska, Maria A; Boncela, Joanna

    2016-09-19

    Inhibition of E-cadherin gene expression by transcription factor SNAIL is known to be a crucial element of Epithelial to Mesenchymal Transition; EMT. Epigenetic regulation of E-cadherin expression is regulated by SNAIL binding to E-box sequences in the CDH1 gene promoter and recruiting enzymes belonging to repressor complexes that are directly engaged in histone modifications and DNA methylation leading to the modification of chromatin structure. SNAIL involvement in cell acquisition of invasive phenotype is based on direct suppression of tight-junction and gap junction proteins. The nuclear localization of SNAIL is required for SNAIL activity and protects this factor from proteasomal degradation in the cytoplasm. The main factor engaged in that process is GSK- 3β kinase. Expression and stability of SNAIL is regulated on the transctriptional and posttranscriptional levels by a number of signaling molecules and biological factors, for example: TGF-β, TNF-α, ILK and NFκB. The expression of SNAIL in cancer cells is also regulated by micro-RNA, mainly by miR-34. Increased expression of SNAIL, observed in many human cancers, has been correlated with increased resistance to chemio-, radio - or immunotherapy, gain of cancer stem cells features and migrative and invasive characteristics, which leads to tumor metastases. Understanding of the SNAIL's mechanism of action may lead to new treatment strategies in cancer directed to interfere with signaling pathways that either activate SNAIL or are activated by SNAIL.

  20. Auditory intensity discrimination as a function of level-rove and tone duration in normal-hearing and impaired subjects: the "mid-level hump" revisited.

    Science.gov (United States)

    Pienkowski, Martin; Hagerman, Bjorn

    2009-07-01

    The just-noticeable difference (DeltaI) in the intensity (I) of sound is typically reported to be a constant or a slightly decreasing ratio of the baseline intensity (known as Weber's law, and the "near-miss to Weber's law", respectively). However, in the relatively few studies on the intensity discrimination of very brief sounds, DeltaI/I is usually found to be non-monotonic, with poorest discrimination in the middle of the auditory dynamic range. Here, it is demonstrated that this "severe departure from Weber's law" or "mid-level hump" is not merely a phenomenon of short-duration sounds. In normal-hearing subjects (n=8), the near-miss to Weber's law that is observed with the discrimination of 300 ms-long, 4 kHz tones, gives way to a significant mid-level hump if tone intensities are not fixed over a great many trials (as is standard practice) but are instead randomly roved, trial-to-trial, over a wide intensity range. This was not the case in subjects with mild to moderate hearing impairment (n=4). Furthermore, in the discrimination of widely-roved, 4 ms-long, 4 kHz tone bursts, the performance of normal-hearing subjects did not significantly worsen at mid-levels compared to the unroved condition, unlike what was found with the 300 ms-long tones. It is suggested that mid-level humps could simply be the product of the well-known mid-level compressive nonlinearity in cochlear mechanics. We further suggest that the hump is eliminated, and the near-miss to Weber's law is produced, by a more central mechanism such as the recently reported "adaptation to sound-level statistics", which is bypassed during wide-range roving and possibly when sound durations are brief.

  1. A preliminary knowledge-driven prediction model of snail distribution in the Poyang Lake region

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Present monitoring and prediction of schistosomiasis's intermediate parasite,snail,are based on remote sensing image's spectral signatures,and the calculation result iS in fact an incomplete-constraints solution.TM image of the Poyang Lake region on October 31,2005 was combined with GIS thematic data(DEM,boundary of the Poyang Lake,vegetation,soil and land use)to make a prediction on snail spatial distribution in the region by remote sensing,geo-informatics and knowledge-driven modeling according to mechanism of snail occurrence.Result shows that with change of overall fuzzy membership of snail occurrence from high to low,snail occurrence of the snail samples of validation group goes up to 81% within 10% high fuzzy membership range,denoting high efficiency of the model in predicting snail occurrence.

  2. Multiple genes elucidate the evolution of venomous snail-hunting Conus species.

    Science.gov (United States)

    Nam, Hannah H; Corneli, Patrice Showers; Watkins, Maren; Olivera, Baldomero; Bandyopadhyay, Pradip

    2009-12-01

    The species-rich Cone snails (Conus sp.) are predatory, marine gastropods known for small venom peptides that are valuable for pharmacological research applications. Phylogenetic analyses with mitochondrial rRNA sequences have facilitated peptide discovery. However, these relatively conserved genes leave unresolved the closer relationships among many species. We sequenced 26 internal transcribed spacer 2 (ITS2) sequences from genomic ribosomal DNA to elucidate the evolutionary relationships among molluscivorous species and to piscivorous and vermivorous species. We show that ITS2 sequences are well conserved within species but are sufficiently variable among species to resolve recent divergences. Using Bayesian, maximum likelihood and log-determinant methods, we use the ITS sequences to resolve portions of the tree that could not be resolved using the more conventional mt rRNA sequences. When the ITS2 sequences are added to existing COI and to the more conserved rRNA sequences and then properly modeled, support throughout the tree is increased. This enables us to show finer relationships among the molluscivorous species that reveal three well-supported clades (Conus, Cylinder, and Darioconus) and renders the ITS2 sequences an essential component in advancing the discovery and pharmacological characterization of novel peptides from the venoms of these molluscs.

  3. On the nature of the in-ecliptic interplanetary magnetic field's two-humped distribution at 1AU

    CERN Document Server

    Khabarova, Olga

    2011-01-01

    According to classical models of the solar wind and the interplanetary magnetic field (IMF) expansion, distributions in the ecliptic plane of both the IMF at 1 AU and the radial magnetic field on the Sun are expected to be identical . We found that photospheric (as well as the solar wind source surface) magnetic field distribution is purely Gaussian, but the distribution of the in-ecliptic and radial IMF at the Earth orbit demonstrates two-humped shape. It was previously supposed that interplanetary sector structure is responsible for the latter phenomenon. Our results indicate that picture of the IMF expansion into space is more complicated than usually considered. The heliospheric current sheet and sector structure are not the only source of the effect. IMF histograms were analysed on the basis of data from different spacecraft obtained at the distances from 0.29 AU to 4 AU from the Sun. The shape of the radial IMF component distribution strongly depends on a heliocentric distance and a heliolatitude. We su...

  4. iPTF13ehe in the context of Quark-Novae in massive binaries: double-humped, hydrogen-poor, superluminous Supernovae as standard candles

    CERN Document Server

    Ouyed, Rachid; Koning, Nico

    2015-01-01

    A Quark-Nova (QN; the explosive transition of a Neutron star to a Quark star) occurring in the second common envelope (CE) phase of a massive binary, as described in Ouyed et al. (2015a&b), gives excellent fits to super-luminous, hydrogen-poor, Supernovae (SLSNe) with double-humped light curves including DES13S2cmm, SN 2006oz and LSQ14bdq (see {\\it http://www.quarknova.ca/LCGallery.html}). In our model, the hydrogen envelope of the less massive companion is ejected during the first CE phase while the QN explosion occurs deep inside the He-rich second CE phase after it has expanded to its equilibrium configuration at ~1200Rsun; this yields the first hump in our model. The subsequent merging of the quark star with the CO core leads to black hole formation and accretion explaining the second long-lasting hump in our model, while the collision of the QN-ejected He-rich CE with the H-rich (i.e. first) CE accounts for late emission. Here we show that our model provides an excellent fit to the recently discovere...

  5. Charge density waves as the origin of dip-hump structures in the differential tunneling conductance of cuprates: The case of d-wave superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Gabovich, Alexander M., E-mail: gabovich@iop.kiev.ua; Voitenko, Alexander I., E-mail: voitenko@iop.kiev.ua

    2014-08-15

    Highlights: • d-Wave superconductivity and charge-density waves compete for the Fermi surface. • Charge-density waves induce pseudogaps and peak-dip-hump structures in cuprates. • Tunnel spectra are non-symmetric due to the dielectric order-parameter phase fixation. • Scatter of the dielectric order parameter smears the tunnel spectra peculiarities. - Abstract: Quasiparticle differential current–voltage characteristics (CVCs) G(V) of non-symmetric tunnel junctions between d-wave superconductors with charge-density waves (CDWs) and normal metals were calculated. The dependences G(V) were shown to have a V-like form at small voltages V and low temperatures, and to be asymmetric at larger V owing to the presence of CDW peak in either of the V-branches. The spatial scatter of the dielectric (CDW) order parameter smears the CDW peak into a hump and induces a peak-dip-hump structure (PDHS) typical of CVCs observed for such junctions. At temperatures larger than the superconducting critical one, the PDHS evolves into a pseudogap depression. The results agree well with the scanning tunneling microscopy data for Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+δ} and YBa{sub 2}Cu{sub 3}O{sub 7−δ}. The results differ substantially from those obtained earlier for CDW s-wave superconductors.

  6. Distribution, habitats and role as intermediate host of the freshwater snail, Bulinus forskalii, in South Africa

    Directory of Open Access Journals (Sweden)

    K.N. De Kock

    2005-09-01

    Full Text Available This paper focuses on the geographical distribution and habitats of Bulinus forskalii, the snail intermediate host of the conical fluke of equids, Gastrodiscus aegyptiacus as reflected by the 1 209 samples in the database of the National Freshwater Snail Collection of South Africa. The 362 different loci on record represent an extensive distribution in KwaZulu-Natal Province, the Limpopo Province, the coastal areas of the Eastern Cape Province and the south-eastern part of the North West Province. Although it was recorded from all types of water-body represented in the database, the highest percentages of samples were recovered from dams (30.4 % and brooks (28.2 %. The majority of samples came from perennial habitats (59.1%, 60.7% from habitats with standing water, 54.0 % from habitats with clear water and 71.8 % from habitats of which the water was described as fresh. The majority of samples (39.5 % were collected in habitats of which the substratum was recorded as muddy. The highest percentage of samples, by far (81.5 %, was collected in habitats that fell within the mean yearly temperature interval ranging from 15-20 °C. An integrated decision tree constructed from the data in the database indicated that temperature and type of water-body played a decisive role in determining the presence of B. forskalii in a given area. The results of experimental exposure to miracidia of a local strain of both Schistosoma haematobium and Schistosoma mattheei in the laboratory indicated that a local strain of B. forskalii was incompatible with both these strains of parasite. Research to clarify the role of B. forskalii in the transmission of both Calicophoron microbothrium and G. aegyptiacus in South Africa, is recommended.

  7. Audubon Tree Study Program.

    Science.gov (United States)

    National Audubon Society, New York, NY.

    Included are an illustrated student reader, "The Story of Trees," a leaders' guide, and a large tree chart with 37 colored pictures. The student reader reviews several aspects of trees: a definition of a tree; where and how trees grow; flowers, pollination and seed production; how trees make their food; how to recognize trees; seasonal changes;…

  8. Molecular diversity of avian schistosomes in Danish freshwater snails.

    Science.gov (United States)

    Christiansen, Anne Ø; Olsen, Annette; Buchmann, Kurt; Kania, Per W; Nejsum, Peter; Vennervald, Birgitte J

    2016-03-01

    Avian schistosomes are widespread parasites of snails and waterfowl and may cause cercarial dermatitis (swimmer's itch) in humans, a disease that is frequently reported in European countries. These parasites are known to occur in Denmark, but here, we applied a new approach using molecular tools to identify the parasites at species level. In order to do that, 499 pulmonate freshwater snails (Radix sp., Lymnaea stagnalis, Stagnicola sp. and Planorbarius corneus) were sampled from 12 lakes, ponds, and marshes in the greater Copenhagen area. Avian schistosome cercariae were identified by microscopy and subjected to molecular investigation by sequencing and phylogenetic analysis of the 5.8S and ITS2 ribosomal DNA for species identification. Additionally, snail hosts belonging to the genus Radix were identified by sequencing and phylogenetic analysis of partial ITS2 ribosomal DNA. Three out of 499 snails shed different species of Trichobilharzia cercariae: Trichobilharzia szidati was isolated from L. stagnalis, Trichobilharzia franki from Radix auricularia and Trichobilharzia regenti from Radix peregra. In the light of the public health risk represented by bird schistosomes, these findings are of concern and, particularly, the presence of the potentially neuro-pathogenic species, T. regenti, in Danish freshwaters calls for attention.

  9. Spatially-resolved thermoluminescence from snail opercula using an EMCCD

    DEFF Research Database (Denmark)

    Duller, G.A.T.; Kook, Myung Ho; Stirling, R.J.

    2015-01-01

    In recent years opercula of the snail species Bithynia tentaculata have been shown to emit thermoluminescence (TL) signals that can be used to determine equivalent dose, and may be capable of dating events throughout the entire Quaternary period. Concentric growth lines are a notable feature...

  10. Arsenic Trioxide Modulates the Central Snail Neuron Action Potential

    Directory of Open Access Journals (Sweden)

    Guan-Ling Lu

    2009-09-01

    Conclusion: As2O3 at 10 mM elicits BoPs in central snail neurons and this effect may relate to the PLC activity of the neuron, rather than protein kinase A activity, or calcium influxes of the neuron. As2O3 at higher concentration irreversibly abolishes the spontaneous action potentials of the neuron.

  11. SNAILs promote G1 phase in selected cancer cells.

    Science.gov (United States)

    Wu, Ya-Lan; Xue, Jian-Xin; Zhou, Lin; Deng, Lei; Shang, Yan-Na; Liu, Fang; Mo, Xian-Ming; Lu, You

    2015-11-01

    Cells can acquire a stem-like cell phenotype through epithelial-mesenchymal transition (EMT). However, it is not known which of the stem-like cancer cells are generated by these phenotype transitions. We studied the EMT-inducing roles of SNAILs (the key inducers for the onset of EMT) in selected cancer cells (lung cancer cell line with relatively stable genome), in order to provide more implications for the investigation of EMT-related phenotype transitions in cancer. However, SNAILs fail to induce completed EMT. In addition, we proved that Snail accelerates the early G1 phase whereas Slug accelerates the late G1 phase. Blocking G1 phase is one of the basic conditions for the onset of EMT-related phenotype transitions (e.g., metastasis, acquiring stemness). The discovery of this unexpected phenomenon (promoting G1 phase) typically reveals the heterogeneity of cancer cells. The onset of EMT-related phenotype transitions in cancer needs not only the induction and activation of SNAILs, but also some particular heredity alterations (genetic or epigenetic alterations, which cause heterogeneity). The new connection between heredity alteration (heterogeneity) and phenotype transition suggests a novel treatment strategy, the heredity alteration-directed specific target therapy. Further investigations need to be conducted to study the relevant heredity alterations.

  12. The maintenance of hybrids by parasitism in a freshwater snail.

    Science.gov (United States)

    Guttel, Yonathan; Ben-Ami, Frida

    2014-11-01

    Hybrids have often been labelled evolutionary dead-ends due to their lower fertility and viability. However, there is growing awareness that hybridisation between different species may play a constructive role in animal evolution as a means to create variability. Thus, hybridisation and introgression may contribute to adaptive evolution, for example with regards to natural antagonists (parasites, predators, competitors) and adaptation to local environmental conditions. Here we investigated whether parasite intensity contributes to the continuous recreation of hybrids in 74 natural populations of Melanopsis, a complex of freshwater snails with three species. We also examined, under laboratory conditions, whether hybrids and their parental taxa differ in their tolerance of low and high temperatures and salinity levels. Infections were consistently less prevalent in males than in females, and lower in snails from deeper habitats. Infection prevalence in hybrids was significantly lower than in the parental taxa. Low hybrid infection rates could not be explained by sediment type, snail density or geographic distribution of the sampling sites. Interestingly, infected hybrid snails did not show signs of parasite-induced gigantism, whereas all parental taxa did. We found that hybrids mostly coped with extreme temperatures and salinity levels as well as their parental taxa did. Taken together, our results suggest that Melanopsis hybrids perform better in the presence of parasites and environmental stress. This may explain the widespread and long-term occurrence of Melanopsis hybrids as evidenced by paleontological and biogeographic data. Hybridisation may be an adaptive host strategy, reducing infection rates and resisting gigantism.

  13. Snail arboreality: the microdistribution of Sitalajenyn.si (Gastropoda ...

    African Journals Online (AJOL)

    The vertical shifts of each snail from a horizontal plane passing through the ... carried out during daytime in an air-conditioned room at. 18°C, 24°C, 30°C ..... Tail wagging was circular at lower temperatures but described horizontal strokes at ...

  14. Hydrocarbons in the land snail Cepaea nemoralis (L.) (gastropoda, pulmonata)

    NARCIS (Netherlands)

    Horst, D.J. van der; Oudejans, R.C.H.M.

    1972-01-01

    1. 1. The biosynthesis of hydrocarbons in the snail Cepaea nemoralis was studied after injection of the 14C-labelled precursors acetate, valine, isoleucine and palmitic acid. 2. 2. The highest incorporation was achieved with palmitic acid, although with the other precursors the hydrocarbons were al

  15. Long-term habitat selection and chronic root herbivory: explaining the relationship between periodical cicada density and tree growth.

    Science.gov (United States)

    Yang, Louie H; Karban, Richard

    2009-01-01

    Periodical cicadas (Magicicada spp.) are insect herbivores that feed on host tree roots, but their distribution among hosts is determined largely by the oviposition of female cicadas in the previous generation. A pattern of decreasing tree growth rates with increasing cicada densities is predicted when considering the costs of chronic root herbivory, but the opposite pattern is expected when considering adaptive habitat selection. Here, we report observations indicating that the relationship between periodical cicada densities and host tree growth rates is hump shaped. We suggest that both herbivory and habitat selection are likely to be key processes explaining this pattern, resulting in regions of positive and negative correlation. These results suggest that the effects of cicada herbivory are most apparent at relatively high cicada densities, while habitat selection tends to distribute cicada herbivory on host trees that are able to compensate for cicada root herbivory up to threshold cicada densities.

  16. Aspen Trees.

    Science.gov (United States)

    Canfield, Elaine

    2002-01-01

    Describes a fifth-grade art activity that offers a new approach to creating pictures of Aspen trees. Explains that the students learned about art concepts, such as line and balance, in this lesson. Discusses the process in detail for creating the pictures. (CMK)

  17. Molecular phylogeny and evolution of the cone snails (Gastropoda, Conoidea).

    Science.gov (United States)

    Puillandre, N; Bouchet, P; Duda, T F; Kauferstein, S; Kohn, A J; Olivera, B M; Watkins, M; Meyer, C

    2014-09-01

    We present a large-scale molecular phylogeny that includes 320 of the 761 recognized valid species of the cone snails (Conus), one of the most diverse groups of marine molluscs, based on three mitochondrial genes (COI, 16S rDNA and 12S rDNA). This is the first phylogeny of the taxon to employ concatenated sequences of several genes, and it includes more than twice as many species as the last published molecular phylogeny of the entire group nearly a decade ago. Most of the numerous molecular phylogenies published during the last 15years are limited to rather small fractions of its species diversity. Bayesian and maximum likelihood analyses are mostly congruent and confirm the presence of three previously reported highly divergent lineages among cone snails, and one identified here using molecular data. About 85% of the species cluster in the single Large Major Clade; the others are divided between the Small Major Clade (∼12%), the Conus californicus lineage (one species), and a newly defined clade (∼3%). We also define several subclades within the Large and Small major clades, but most of their relationships remain poorly supported. To illustrate the usefulness of molecular phylogenies in addressing specific evolutionary questions, we analyse the evolution of the diet, the biogeography and the toxins of cone snails. All cone snails whose feeding biology is known inject venom into large prey animals and swallow them whole. Predation on polychaete worms is inferred as the ancestral state, and diet shifts to molluscs and fishes occurred rarely. The ancestor of cone snails probably originated from the Indo-Pacific; rather few colonisations of other biogeographic provinces have probably occurred. A new classification of the Conidae, based on the molecular phylogeny, is published in an accompanying paper. Copyright © 2014 Elsevier Inc. All rights reserved.

  18. Trematode communities in snails can indicate impact and recovery from hurricanes in a tropical coastal lagoon.

    Science.gov (United States)

    Aguirre-Macedo, María Leopoldina; Vidal-Martínez, Victor M; Lafferty, Kevin D

    2011-11-01

    In September 2002, Hurricane Isidore devastated the Yucatán Peninsula, Mexico. To understand its effects on the parasites of aquatic organisms, we analyzed long-term monthly population data of the horn snail Cerithidea pliculosa and its trematode communities in Celestún, Yucatán, Mexico before and after the hurricane (February 2001 to December 2009). Five trematode species occurred in the snail population: Mesostephanus appendiculatoides, Euhaplorchis californiensis, two species of the genus Renicola and one Heterophyidae gen. sp. Because these parasites use snails as first intermediate hosts, fishes as second intermediate hosts and birds as final hosts, their presence in snails depends on food webs. No snails were present at the sampled sites for 6 months after the hurricane. After snails recolonised the site, no trematodes were found in snails until 14 months after the hurricane. It took several years for snail and trematode populations to recover. Our results suggest that the increase in the occurrence of hurricanes predicted due to climate change can impact upon parasites with complex life cycles. However, both the snail populations and their parasite communities eventually reached numbers of individuals and species similar to those before the hurricane. Thus, the trematode parasites of snails can be useful indicators of coastal lagoon ecosystem degradation and recovery.

  19. Trematode communities in snails can indicate impact and recovery from hurricanes in a tropical coastal lagoon

    Science.gov (United States)

    Aguirre-Macedo, Maria Leopoldina; Vidal-Martinez, Victor M.; Lafferty, Kevin D.

    2011-01-01

    In September 2002, Hurricane Isidore devastated the Yucatán Peninsula, Mexico. To understand its effects on the parasites of aquatic organisms, we analyzed long-term monthly population data of the horn snail Cerithidea pliculosa and its trematode communities in Celestún, Yucatán, Mexico before and after the hurricane (February 2001 to December 2009). Five trematode species occurred in the snail population: Mesostephanus appendiculatoides, Euhaplorchis californiensis, two species of the genus Renicola and one Heterophyidae gen. sp. Because these parasites use snails as first intermediate hosts, fishes as second intermediate hosts and birds as final hosts, their presence in snails depends on food webs. No snails were present at the sampled sites for 6 months after the hurricane. After snails recolonised the site, no trematodes were found in snails until 14 months after the hurricane. It took several years for snail and trematode populations to recover. Our results suggest that the increase in the occurrence of hurricanes predicted due to climate change can impact upon parasites with complex life cycles. However, both the snail populations and their parasite communities eventually reached numbers of individuals and species similar to those before the hurricane. Thus, the trematode parasites of snails can be useful indicators of coastal lagoon ecosystem degradation and recovery.

  20. Lymnaea glabra: progressive increase in susceptibility to Fasciola hepatica through successive generations of experimentally infected snails.

    Science.gov (United States)

    Rondelaud, D; Teukeng, F F Djuikwo; Vignoles, P; Dreyfuss, G

    2015-07-01

    Experimental infections of Lymnaea glabra (two populations) with Fasciola hepatica were carried out during seven successive snail generations, to determine if prevalence and intensity of snail infection increased over time through descendants of snails already infected with F. hepatica. Controls were descendants coming from uninfected parents and infected according to the same protocol. No larval forms were found in the bodies of control snails coming from uninfected parents. In contrast, prevalence and intensity of F. hepatica infection in snails originating from infected parents progressively increased from the F2 or F3 to the F6 generation of L. glabra. In another experiment carried out with the F7 generations of L. glabra and a single generation of Galba truncatula (as controls), the prevalence of F. hepatica infection and the total number of cercariae were lower in L. glabra (without significant differences between both populations). If the number of cercariae shed by infected snails was compared to overall cercarial production noted in snails containing cercariae but dying without emission, the percentage was greater in G. truncatula (69% instead of 52-54% in L. glabra). Even if most characteristics of F. hepatica infection were lower in L. glabra, prevalence and intensity of parasite infection increased with snail generation when tested snails came from infected parents. This mode of snail infection with F. hepatica suggests an explanation for cases of fasciolosis occurring in cattle-breeding farms where paramphistomosis is lacking and G. truncatula is absent.

  1. Snail as a key regulator of PRL-3 gene in colorectal cancer.

    Science.gov (United States)

    Zheng, Ping; Meng, Hui-Min; Gao, Wei-Zhe; Chen, Lin; Liu, Xun-Hua; Xiao, Zheng-Quan; Liu, Yong-Xia; Sui, Hong-Mei; Zhou, Jun; Liu, Yu-Hong; Li, Jian-Ming

    2011-10-15

    The regulators of a key metastasis gene PRL-3 in colorectal cancer (CRC) are still largely unknown. We found three potential binding sites of Snail, a key transcriptional factor involved in the epithelial-mesenchymal transition (EMT), in the region of PRL-3 promoter (located at -642 to -383). Moreover, our results showed that one of the Snail binding sites (located at -624 to -619) was the key element to maintain promoter activity of human PRL-3 gene. The transcriptional activity of PRL-3 promoter was abolished after the Snail binding site (located at -624 to -619) was mutated. Both promoter activity and protein expression of PRL-3 in CRC cell lines could be regulated by Snail. In clinical samples of CRC and metastatic lymph node of CRC, expression of PRL-3 protein was correlated with expression of Snail protein. Functional studies using gene over-expression and knockdown methods indicated that Snail promoted proliferation, cell adhesion and migration of human CRC cells. In SW480 cells with PRL-3 stable knockdown, cell proliferation increased after Snail was up-regulated. Our data first reveal transcriptional factor Snail as a key regulator of PRL-3 in CRC. The link between Snail and PRL-3 suggests a new potential mechanism of Snail contributing to progression and metastasis of CRC.

  2. Cten promotes epithelial-mesenchymal transition through the post-transcriptional stabilization of Snail.

    Science.gov (United States)

    Thorpe, Hannah; Asiri, Abdulaziz; Akhlaq, Maham; Ilyas, Mohammad

    2017-07-10

    Cten promotes cell migration however the knowledge of underlying signalling pathways is sparse. We have shown that Cten downregulates E-cadherin, a feature of epithelial to mesenchymal transition (EMT). This prompted us to investigate whether Cten further contributed to EMT processes to regulate cell motility. The regulation of Snail by Cten was investigated following overexpression, knockdown (by RNA-interference) or knockout of Cten in HCT116, Caco-2 and SW620 colorectal cancer (CRC) cell lines. Subsequently, the cycloheximide (CHX) pulse chase assay was used to investigate changes in Snail protein stability and the functional relevance of Cten-Snail signalling was investigated. Snail was identified as a downstream target of Cten signalling using multiple approaches of Cten expression manipulation. Furthermore, this activity was mediated through the SH2 domain of Cten. The CHX assay confirmed that Cten was regulating Snail at a post transcriptional level and this was through the prevention of Snail degradation. Cell migration, invasion and colony formation efficiency were increased following forced expression of GFP-Cten but subsequently lost when Snail was knocked down, demonstrating a functional Cten-Snail signalling axis. In conclusion, we have described a novel Cten-Snail signaling pathway that contributes to cell motility in CRC, mediated by the stabilization of Snail protein. This finding potentially furthers the understanding of EMT regulatory networks in cancer metastasis. © 2017 Wiley Periodicals, Inc.

  3. FBXL5 Inhibits Metastasis of Gastric Cancer Through Suppressing Snail1

    Directory of Open Access Journals (Sweden)

    Weidong Wu

    2015-03-01

    Full Text Available Background/Aims: The Snail family of transcription factors controls epithelial to mesenchymal transition (EMT, a process associated with tumorigenesis originated from epithelial cells. Snail1 is a member from Snail family and upregulation of Snail1 has been detected in gastric cancer (GC, suggesting a potential role of Snail1 in GC metastasis. We have recently reported that FBXL5 regulates cortactin by inducing its ubiquitylation and subsequent proteasomal degradation, resulting in inhibition of metastasis of GC. However, a role of FBXL4 in regulation of other EMT-associated proteins is not unknown. Methods: The levels of FBXL5 and Snail1 as well as their relationship were determined in GC specimen. Co-immunoprecipitation (IP was performed to detect the interaction between Snail1 and FBXL5 in GC cells. The effects on Snail1 by FBXL5 were examined by overexpression of depletion of FBXL5 in GC cells. The invasiveness of the FBXL5-modified GC cells was examined in both scratch wound healing assay and transwell matrix penetration assay. Results: FBXL5 also physiologically interacted with Snail1. FBXL5 inhibited Snail1 to suppress GC cell invasiveness. Conclusion: FBXL5 negatively regulates several EMT-enhancing factors. FBXL5 is an attractive novel target for inhibiting invasion and metastasis of GC cells.

  4. Targeted inactivation of Snail family EMT regulatory factors by a Co(III)-Ebox conjugate.

    Science.gov (United States)

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

    2012-01-01

    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.

  5. The Use of Golden Snail (Pomacea sp. as Animal Feed in the Philippines

    Directory of Open Access Journals (Sweden)

    Serra, AB.

    1997-01-01

    Full Text Available The golden snail is introduced to the Philippines in early 80's for culture as food source. This herbivorous snail, a voracious feeder of live and fresh plant materials become a serious rice pest. Its elimination in the ecosystems is impossible. To use them as animal feed is much better alternative for their control and more environmentally friendly than the use of chemicals. Thus, this mini review paper aimed to collate any existing information on the use of golden snail as animal feed. The different meal forms that can be extracted are golden snail meal (30 % calcium and 15 % crude protein, golden snail meat meal (62 % crude protein and 3336 kcal/kg and golden shell meal (35 % calcium. Feeding trials indicate that golden snail meal can be a part of swine and chicken layer diets up to 15 %. Golden snail meat meal can be a part of broiler chicken diet up to 12 %. Feeding fresh and ground golden snail to ducks can replace 50 % of their diet under total confinement system. Whereas, golden snail meat meal (75 % of the diet plus rice bran can be beneficially fed to tilapia. With the information collated, golden snail can be a promising animal feed in the Philippines.

  6. Overexpression of Snail in retinal pigment epithelial triggered epithelial–mesenchymal transition

    Energy Technology Data Exchange (ETDEWEB)

    Li, Hui; Li, Min; Xu, Ding; Zhao, Chun; Liu, Guodong; Wang, Fang, E-mail: milwang_122@msn.com

    2014-03-28

    Highlights: • First reported overexpression of Snail in RPE cells could directly trigger EMT. • Further confirmed the regulator role of Snail in RPE cells EMT in vitro. • Snail may be a potential therapeutic target to prevent the fibrosis of PVR. - Abstract: Snail transcription factor has been implicated as an important regulator in epithelial–mesenchymal transition (EMT) during tumourigenesis and fibrogenesis. Our previous work showed that Snail transcription factor was activated in transforming growth factor β1 (TGF-β1) induced EMT in retinal pigment epithelial (RPE) cells and may contribute to the development of retinal fibrotic disease such as proliferative vitreoretinopathy (PVR). However, whether Snail alone has a direct role on retinal pigment epithelial–mesenchymal transition has not been investigated. Here, we analyzed the capacity of Snail to drive EMT in human RPE cells. A vector encoding Snail gene or an empty vector were transfected into human RPE cell lines ARPE-19 respectively. Snail overexpression in ARPE-19 cells resulted in EMT, which was characterized by the expected phenotypic transition from a typical epithelial morphology to mesenchymal spindle-shaped. The expression of epithelial markers E-cadherin and Zona occludin-1 (ZO-1) were down-regulated, whereas mesenchymal markers a-smooth muscle actin (a-SMA) and fibronectin were up-regulated in Snail expression vector transfected cells. In addition, ectopic expression of Snail significantly enhanced ARPE-19 cell motility and migration. The present data suggest that overexpression of Snail in ARPE-19 cells could directly trigger EMT. These results may provide novel insight into understanding the regulator role of Snail in the development of retinal pigment epithelial–mesenchymal transition.

  7. Unimodular trees versus Einstein trees

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez, Enrique; Gonzalez-Martin, Sergio [Universidad Autonoma, Instituto de Fisica Teorica, IFT-UAM/CSIC, Madrid (Spain); Universidad Autonoma de Madrid, Departamento de Fisica Teorica, Madrid (Spain); Martin, Carmelo P. [Universidad Complutense de Madrid (UCM), Departamento de Fisica Teorica I Facultad de Ciencias Fisicas, Madrid (Spain)

    2016-10-15

    The maximally helicity violating tree-level scattering amplitudes involving three, four or five gravitons are worked out in Unimodular Gravity. They are found to coincide with the corresponding amplitudes in General Relativity. This a remarkable result, insofar as both the propagators and the vertices are quite different in the two theories. (orig.)

  8. Unimodular Trees versus Einstein Trees

    CERN Document Server

    Alvarez, Enrique; Martin, Carmelo P

    2016-01-01

    The maximally helicity violating (MHV) tree level scattering amplitudes involving three, four or five gravitons are worked out in Unimodular Gravity. They are found to coincide with the corresponding amplitudes in General Relativity. This a remarkable result, insofar as both the propagators and the vertices are quite different in both theories.

  9. Unimodular trees versus Einstein trees

    Science.gov (United States)

    Álvarez, Enrique; González-Martín, Sergio; Martín, Carmelo P.

    2016-10-01

    The maximally helicity violating tree-level scattering amplitudes involving three, four or five gravitons are worked out in Unimodular Gravity. They are found to coincide with the corresponding amplitudes in General Relativity. This a remarkable result, insofar as both the propagators and the vertices are quite different in the two theories.

  10. Distribution and habitats of the snail Lymnaea truncatula, intermediate host of the liver fluke Fasciola hepatica, in South Africa.

    Science.gov (United States)

    de Kock, K N; Wolmarans, C T; Bornman, M

    2003-12-01

    This paper focuses on the geographical distribution and habitats of Lymnaea truncatula, the intermediate, snail host of the liver fluke, Fasciola hepatica, as reflected by the 723 samples in the database of the National Freshwater Snail Collection, Potchefstroom, South Africa. The 221 different loci (1/16-degree squares) on record reflect an extensive but discontinuous distribution, except in Lesotho and in parts of the Mpumalanga, Gauteng and North West provinces of South Africa. Although recorded from 12 different types of waterbody, it was mostly (42.0%) recovered from swamps. Most samples (45.8%) were collected in habitats with slow-flowing water. A muddy substratum was recorded for 62.5% of the samples. Most samples (86.3%) were collected in habitats with a mean annual air temperature of 10-20 degrees C, and more than 69% came from localities with a mean annual rainfall of 600-900 mm. An integrated decision tree constructed from the data indicated that temperature and types of waterbody play a decisive role in determining the presence of L. truncatula in a given area. A temperature index calculated for all mollusc species ranked L. truncatula second in a total of 53 species according to its association with low temperatures. It remains to be established whether its distribution is indeed discontinuous, and whether its preference for a particular habitat, amphibious habits and ability to aestivate could have resulted in some populations having been overlooked during surveys.

  11. Distribution and habitats of the snail Lymnaea truncatula, intermediate host of the liver fluke Fasciola hepatica, in South Africa

    Directory of Open Access Journals (Sweden)

    K.N. de Kock

    2003-07-01

    Full Text Available This paper focuses on the geographical distribution and habitats of Lymnaea truncatula, the intermediate, snail host of the liver fluke, Fasciola hepatica, as reflected by the 723 samples in the database of the National Freshwater Snail Collection, Potchefstroom, South Africa. The 221 different loci (1/16-degree squares on record reflect an extensive but discontinuous distribution, except in Lesotho and in parts of the Mpumalanga, Gauteng and North West provinces of South Africa. Although recorded from 12 different types of waterbody, it was mostly (42.0 % recovered from swamps. Most samples (45.8 % were collected in habitats with slow-flowing water. A muddy substratum was recorded for 62.5 % of the samples. Most samples (86.3 % were collected in habitats with a mean annual air temperature of 10-20 o C, and more than 69 % came from localities with a mean annual rainfall of 600-900mm. An integrated decision tree constructed from the data indicated that temperature and types of waterbody play a decisive role in determining the presence of L. truncatula in a given area. A temperature index calculated for all mollusc species ranked L. truncatula second in a total of 53 species according to its association with low temperatures. It remains to be established whether its distribution is indeed discontinuous, and whether its preference for a particular habitat, amphibious habits and ability to aestivate could have resulted in some populations having been overlooked during surveys.

  12. Skin to cervical epidural space distances as read from magnetic resonance imaging films: consideration of the "hump pad.".

    Science.gov (United States)

    Aldrete, J A; Mushin, A U; Zapata, J C; Ghaly, R

    1998-06-01

    To measure the distances from the skin to the epidural space (DSES) of the lower cervical and upper thoracic intervertebral spaces. Retrospective review of films of the cervical spine as obtained by magnetic resonance imaging (MRI). Health care facility that provides diagnosis and treatment of patients with chronic pain. MRI sagittal films of 100 patients, who had diagnostic studies for chronic headaches and cervicobrachial radiculopathy, were reviewed. Measurements were made of DSES, the dural sac, and the spinal cord by centimeter ruler. Estimates were also made of the width of the epidural space by measuring the distance from the ligamentum flavum to the dural sac. The longest DSES were noted at C6-7 and C7-T1 levels, with a mean of 5.7 cm, but they decreased to a mean of 5.4 cm at the T1-2, and to 4. 7 cm at the T2-3 intervertebral spaces. One of the major factors in this variability was the presence of an accumulation of fatty tissue along the lower cervical and upper thoracic area, which the authors named the "hump pad." This accumulation appears to be thicker in obese patients, with a slight correlation coefficient with the patient's weight. The distances from ligamentum flavum to dural sac, representing the depth of the epidural space, averaged 0.3 cm, 0.4 cm, 0.5 cm, and 0.4 cm, respectively. In the cervical spine, DSES varies from space to space. In obese individuals, the fat pad may increase DSES at the lower cervical intervertebral spaces. The longest mean distances from the ligamentum flavum to the dural sac and to the spinal cord were found at the T1-2 and T2-3 levels, precisely where DSES is shorter. All things being equal, the upper thoracic intervertebral spaces appeared to provide a greater margin of safety for insertion of epidural catheters to treat cervicobrachial radiculopathies.

  13. Comparative in-vivo toxicity of venoms from South Asian hump-nosed pit vipers (Viperidae: Crotalinae: Hypnale

    Directory of Open Access Journals (Sweden)

    Silva Anjana

    2012-08-01

    Full Text Available Abstract Background Envenoming by south Asian hump-nosed pit vipers (Genus: Hypnale is a significant health issue in Sri Lanka and in peninsular India. Bites by these snakes frequently lead to local envenoming, coagulopathy and acute renal failure even resulting in death. Recently the genus was revised and the existence of three species viz H. hypnale, H. nepa and H. zara were recognized. There is, however, a paucity of information on the toxicity of the venoms of these species. Hence, we compared the toxic effects of the three Hypnale venoms using BALB/c mice. Findings Intraperitoneal median lethal doses (LD50 for H. hypnale, H. zara and H. nepa venoms were 1.6, 6.0 and 9.5 μg protein/g respectively. Minimum haemorrhagic doses for venoms of H. hypnale, H. zara and H. nepa were 3.4, 11.0 and 16.6 μg protein/mouse respectively. The minimum necrotic doses for the same venoms were 15.0, 55.1 and 68.2 μg protein/mouse respectively. Severe congestion and petecheal haemorrhages were observed in lungs, kidneys, liver and the alimentary tract. Histopathogical examination of kidneys revealed proximal tubular cell injury and acute tubular necrosis with intact basement membrane indicating possible direct nephrotoxicity. Hypnale venoms caused pulmonary oedema, hepatocellular degeneration and necrosis, focal neuronal degeneration in brain and extramedullary haemopoiesis in spleen. H. hypnale venom caused all above histopathological alterations at lower doses compared to the other two. Conclusion Hypnale venoms cause similar pathological changes with marked differences in the severity of the toxic effects in vivo. Therefore, differences in the severity of the clinical manifestations could possibly be seen among bite victims of the three Hypnale species.

  14. Snail Hosts of Paragonimus in Asia and the Americas

    Institute of Scientific and Technical Information of China (English)

    G.M.DAVIS; CHENCui-E; 等

    1994-01-01

    We have undertaken a comprehensive review of snail hosts of Paragonimus world-wide exclusive of Africa based on modern malacological data,where available,and with consideration of the phylogeny of the snail groups involved.This is the first comprehensive review since those made by Chen(1979)and Chen et al.(1983),and there have been considerable taxonomic changes over the past decade. A number of names and concepts found in the medical malacological and parasitological literature up to the present time require revision or correction.There ae vast radiations of snails of the superfamilies Cerithiacea and Rissoacea involved in the transmission of Paragonimus in CHina.We list 54 species world-wide of which 35(65%)occur in China.Revisions and corrections pertaining to China include:(i)the family Hydrobiidae does not occur in China or S.E.Asia and thd Pomatiopsidae should be used,(ii)The genus Bythinella is entirely European(Hydrobiidae:Amnicolinae).The so-called Bythinella of China belongs to the genus Erhaia(Pomatiopsidae).(iii)The generic name Pseudobythinella described from China is preoccupied,a junior synonym of Pseudobythinella Melville 1956,a fossil from england,ll chinese Pseudobythinella are now classified as Erhaia.(iv)Akiyoshia has been used as a generic name for some snails in Hunan transmitting Paragonimus,Akiyoshia is from Japan and biological/ecological data indicate tat the Chinese taxon is not Akiyoshia.(v)The genus Tricula in recent Chinese literature is comprised of four genera determined by detailed comparative anatomical data:Tricula,Neotricula,Gammatricula,and Jinhongia Shells cannot be used to discriminate among them.(vi)tricula cristella has been consistently misidentified in collections in China and literature.However,genuine T.cristella does transmit Paragonimus skrjabini.(vii)Tricula minutoides in the Chinese literature has been misidentified,and specimens,are T.cristella.(viii)The genus Melania and the family Melaniidae are used in the

  15. Metabolic acceleration in the pond snail Lymnaea stagnalis?

    Science.gov (United States)

    Zimmer, Elke I.; Ducrot, V.; Jager, T.; Koene, J.; Lagadic, L.; Kooijman, S. A. L. M.

    2014-11-01

    Under constant environmental conditions, most animals tend to grow following the von Bertalanffy growth curve. Deviations from this curve can point to changes in the environment that the animals experience, such as food limitation when the available food is not sufficient or suitable. However, such deviations can also point to a phenomenon called metabolic acceleration, which is receiving increasing attention in the field of Dynamic Energy Budget (DEB) modeling. Reasons for such an acceleration are usually changes in shape during ontogeny, which cause changes in the surface area to volume ratio of the organism. Those changes, in turn, lead to changes in some of the model parameters that have length in their dimension. The life-history consequences of metabolic acceleration as implemented in the DEB theory are an s-shaped growth curve (when body size is expressed as a length measure) and a prolongation of the hatching time. The great pond snail Lymnaea stagnalis was earlier found to be food limited during the juvenile phase in laboratory experiments conducted under classical ecotoxicity test protocols. The pond snail has isomorphic shell growth but yet does not exhibit the expected von Bertalanffy growth curve under food limitation. When applying the standard DEB model to data from such life-cycle experiments, we also found that the hatching time is consistently underestimated, which could be a sign of metabolic acceleration. We here present an application of the DEB model including metabolic acceleration to the great pond snail. We account for the simultaneous hermaphroditism of the snail by including a model extension that describes the relative investment into the male and female function. This model allowed us to adequately predict the life history of the snail over the entire life cycle. However, the pond snail does not change in shape substantially after birth, so the original explanation for the metabolic acceleration does not hold. Since the change in shape

  16. Cancer metastasis is accelerated through immunosuppression during Snail-induced EMT of cancer cells.

    Science.gov (United States)

    Kudo-Saito, Chie; Shirako, Hiromi; Takeuchi, Tadashi; Kawakami, Yutaka

    2009-03-03

    Epithelial-mesenchymal transition (EMT) is a key step toward cancer metastasis, and Snail is a major transcription factor governing EMT. Here, we demonstrate that Snail-induced EMT accelerates cancer metastasis through not only enhanced invasion but also induction of immunosuppression. Murine and human melanoma cells with typical EMT features after snail transduction induced regulatory T cells and impaired dendritic cells in vitro and in vivo partly through TSP1 production. Although Snail(+) melanoma did not respond to immunotherapy, intratumoral injection with snail-specific siRNA or anti-TSP1 monoclonal antibody significantly inhibited tumor growth and metastasis following increase of tumor-specific tumor-infiltrating lymphocytes and systemic immune responses. These results suggest that inhibition of Snail-induced EMT could simultaneously suppress both tumor metastasis and immunosuppression in cancer patients.

  17. Central role of Snail1 in the regulation of EMT and resistance in cancer: a target for therapeutic intervention

    OpenAIRE

    Kaufhold, Samantha; Bonavida, Benjamin

    2014-01-01

    Snail1 is the founding member of the Snail superfamily of zinc-finger transcription factors, which also includes Snail2 (Slug) and Snail3 (Smuc). The superfamily is involved in cell differentiation and survival, two processes central in cancer research. Encoded by the SNAI1 gene located on human chromosome 20q13.2, Snail1 is composed of 264 amino acids and usually acts as a transcriptional repressor. Phosphorylation and nuclear localization of Snail1, governed by PI3K and Wnt signaling pathwa...

  18. An ecological study of Bithynia snails, the first intermediate host of Opisthorchis viverrini in northeast Thailand.

    Science.gov (United States)

    Wang, Yi-Chen; Ho, Richard Cheng Yong; Feng, Chen-Chieh; Namsanor, Jutamas; Sithithaworn, Paiboon

    2015-01-01

    Infection with the food-borne trematodiasis, liver fluke Opisthorchis viverrini, is a major public health concern in Southeast Asia. While epidemiology and parasitic incidence in humans are well studied, ecological information on the O. viverrini intermediate hosts remains limited. This study aimed to investigate the factors affecting the distribution and abundance of the first intermediate host, Bithynia siamensis goniomphalos snails. Water quality and snails were sampled in 31 sites in Muang District, Khon Kaen Province, Thailand from June 2012 to January 2013 to characterize the B.s. goniomphalos snail habitats. Species relative abundance and Shannon's diversity and evenness indices were employed to describe snail compositions and diversities across different habitat types. Statistical analyses were conducted to examine the extent to which the water quality variables and species interactions account for the relative abundance of B.s. goniomphalos snails. The results showed that the freshwater habitats of ponds, streams and rice paddies possessed significantly different abiotic water qualities, with water temperature and pH showing distinct statistical differences (Psnail diversity and species evenness, with high B.s. goniomphalos snail abundance at rice paddy habitats. The differences in snail abundance might be due to the distinct sets of abiotic water qualities associated with each habitat types. The relative abundance of B.s. goniomphalos snails was found to be negatively correlated with that of Filopaludina martensi martensi snails (r=-0.46, Psnail population. Field work observations revealed that rice planting seasons and irrigation could regulate snail population dynamics at rice paddy habitats. This study provides new ecological insights into the factors affecting Bithynia snail distribution and abundance. It bridges the knowledge gap in O. viverrini disease ecology and highlights the potential effect of anthropogenic irrigation practices on B

  19. Snail2 is an essential mediator of Twist1-induced epithelial-mesenchymal transition and metastasis

    OpenAIRE

    Casas, Esmeralda; Kim, Jihoon; Bendesky, Andrés; Ohno-Machado, Lucila; Wolfe, Cecily J.; Yang, Jing

    2011-01-01

    To metastasize, carcinoma cells must attenuate cell-cell adhesion to disseminate into distant organs. A group of transcription factors, including Twist1, Snail1, Snail2, ZEB1, and ZEB2, have been shown to induce Epithelial-Mesenchymal Transition (EMT), thus promoting tumor dissemination. However, it is unknown whether these transcription factors function independently or coordinately to activate the EMT program. Here we report that direct induction of Snail2 is essential for Twist1 to induce ...

  20. Removal of corallivorous snails as a proactive tool for the conservation of acroporid corals

    Directory of Open Access Journals (Sweden)

    Dana E. Williams

    2014-11-01

    Full Text Available Corallivorous snail feeding is a common source of tissue loss for the threatened coral, Acropora palmata, accounting for roughly one-quarter of tissue loss in monitored study plots over seven years. In contrast with larger threats such as bleaching, disease, or storms, corallivory by Coralliophila abbreviata is one of the few direct sources of partial mortality that may be locally managed. We conducted a field experiment to explore the effectiveness and feasibility of snail removal. Long-term monitoring plots on six reefs in the upper Florida Keys were assigned to one of three removal treatments: (1 removal from A. palmata only, (2 removal from all host coral species, or (3 no-removal controls. During the initial removal in June 2011, 436 snails were removed from twelve 150 m2 plots. Snails were removed three additional times during a seven month “removal phase”, then counted at five surveys over the next 19 months to track recolonization. At the conclusion, snails were collected, measured and sexed. Before-After-Control-Impact analysis revealed that both snail abundance and feeding scar prevalence were reduced in removal treatments compared to the control, but there was no difference between removal treatments. Recolonization by snails to baseline abundance is estimated to be 3.7 years and did not differ between removal treatments. Recolonization rate was significantly correlated with baseline snail abundance. Maximum snail size decreased from 47.0 mm to 34.6 mm in the removal treatments. The effort required to remove snails from A. palmata was 30 diver minutes per 150 m2 plot, compared with 51 min to remove snails from all host corals. Since there was no additional benefit observed with removing snails from all host species, removals can be more efficiently focused on only A. palmata colonies and in areas where C. abbreviata abundance is high, to effectively conserve A. palmata in targeted areas.

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

    CSIR Research Space (South Africa)

    Musee, N

    2010-01-01

    Full Text Available of test specimens P. acuta is a common pulmonate snail mostly found in streams, ponds, and lakes throughout South Africa. The P. acuta snails used in this bioassay were obtained from batch cultures of offspring col- lected from the Rietvlei nature..., and themselves are prey to fish, and other invertebrate predators (Osenberg and Mittelbach, 1989; Underwood, 1991; Bernot and Turner, 2001). In addition, the pulmonate snails are important detritivores in standing and running water. Cummins (1974) devised...

  2. Experimental infections with Fasciola in snails, mice and rabbits.

    Science.gov (United States)

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

    2008-05-01

    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.

  3. Structure of mega-hemocyanin reveals protein origami in snails.

    Science.gov (United States)

    Gatsogiannis, Christos; Hofnagel, Oliver; Markl, Jürgen; Raunser, Stefan

    2015-01-06

    Mega-hemocyanin is a 13.5 MDa oxygen transporter found in the hemolymph of some snails. Similar to typical gastropod hemocyanins, it is composed of 400 kDa building blocks but has additional 550 kDa subunits. Together, they form a large, completely filled cylinder. The structural basis for this highly complex protein packing is not known so far. Here, we report the electron cryomicroscopy (cryo-EM) structure of mega-hemocyanin complexes from two different snail species. The structures reveal that mega-hemocyanin is composed of flexible building blocks that differ in their conformation, but not in their primary structure. Like a protein origami, these flexible blocks are optimally packed, implementing different local symmetries and pseudosymmetries. A comparison between the two structures suggests a surprisingly simple evolutionary mechanism leading to these large oxygen transporters.

  4. MODULATION OF DEFENSIVE REFLEX CONDITIONING IN SNAILS BY SEROTONIN

    Directory of Open Access Journals (Sweden)

    Vyatcheslav V Andrianov

    2015-10-01

    Full Text Available We studied the role of serotonin in the mechanisms of learning in terrestrial snails. To produce a serotonin deficit, the neurotoxic analogues of serotonin, 5,6- or 5,7-dihydroxytryptamine (5,6/5,7-DHT were used. Injection of 5,6/5,7-DHT was found to disrupt defensive reflex conditioning. Within two weeks of neurotoxin application, the ability to learn had recovered. Daily injection of serotonin before a training session accelerated defensive reflex conditioning and daily injections of 5-HTP in snails with a deficiency of serotonin induced by 5,7-DHT restored the snail’s ability to learn. We discovered that injections of the neurotoxins 5,6/5,7-DHT as well as serotonin, caused a decrease in the resting and threshold potentials of the premotor interneurons LPa3 and RPa3.

  5. Activity of the mangrove snail Cerithidea decollata (Gastropoda: Potamididae) in a warm temperate South African estuary

    Science.gov (United States)

    Hodgson, Alan N.; Dickens, John

    2012-08-01

    A population of Cerithidea decollata, an intertidal marine gastropod usually found within mangroves, was studied within an area of Juncus kraussii in the upper reaches of the warm temperate Knysna estuary, which is at the southern-most limit of the recorded distribution of this snail. Activity (migratory and homing behaviour, distances travelled during foraging) of the snails was monitored over spring and neap tides in four seasons. Migratory patterns of the snails were affected by season, time of low tide (day vs night), tidal magnitude (spring vs neap) and zonation. In the summer and spring, a greater proportion of snails migrated from J. kraussii leaves onto the mud during the day at spring low tide. During neap tides in these two seasons, most snails did not climb J. kraussii leaves and remained on the mud, which was nearly always exposed. In autumn a few snails only were active and in winter snails were almost completely inactive, probably due to low air temperatures. Snails travelled greater distances on the mud on spring tides, during the diurnal low tides, and in the summer. No snails were found to home to individual J. kraussii leaves; however, homing behaviour was recorded to wooden poles within the Juncus wetland.

  6. Hormone-like peptides in the venoms of marine cone snails

    DEFF Research Database (Denmark)

    Robinson, Samuel D.; Li, Qing; Bandyopadhyay, Pradip K.

    2017-01-01

    The venoms of cone snails (genus Conus) are remarkably complex, consisting of hundreds of typically short, disulfide-rich peptides termed conotoxins. These peptides have diverse pharmacological targets, with injection of venom eliciting a range of physiological responses, including sedation...... in the venoms of cone snails we systematically mined the venom gland transcriptomes of several cone snail species and examined secreted venom peptides in dissected and injected venom of the Australian cone snail Conus victoriae. Using this approach we identified several novel hormone/neuropeptide-like toxins...

  7. Fasciola hepatica in snails collected from water-dropwort fields using PCR.

    Science.gov (United States)

    Kim, Hwang-Yong; Choi, In-Wook; Kim, Yeon-Rok; Quan, Juan-Hua; Ismail, Hassan Ahmed Hassan Ahmed; Cha, Guang-Ho; Hong, Sung-Jong; Lee, Young-Ha

    2014-12-01

    Fasciola hepatica is a trematode that causes zoonosis mainly in cattle and sheep and occasionally in humans. Fascioliasis has been reported in Korea; however, determining F. hepatica infection in snails has not been done recently. Thus, using PCR, we evaluated the prevalence of F. hepatica infection in snails at 4 large water-dropwort fields. Among 349 examined snails, F. hepatica-specific internal transcribed space 1 (ITS-1) and/or ITS-2 markers were detected in 12 snails and confirmed using sequence analysis. Morphologically, 213 of 349 collected snails were dextral shelled, which is the same aperture as the lymnaeid snail, the vectorial host for F. hepatica. Among the 12 F. hepatica-infected snails, 6 were known first intermediate hosts in Korea (Lymnaea viridis and L. ollula) and the remaining 6 (Lymnaea sp.) were potentially a new first intermediate host in Korea. It has been shown that the overall prevalence of the snails contaminated with F. hepatica in water-dropwort fields was 3.4%; however, the prevalence varied among the fields. This is the first study to estimate the prevalence of F. hepatica infection using the vectorial capacity of the snails in Korea.

  8. Action of SNAIL1 in Cardiac Myofibroblasts Is Important for Cardiac Fibrosis following Hypoxic Injury

    Science.gov (United States)

    Biswas, Hirak; Longmore, Gregory D.

    2016-01-01

    Hypoxic injury to the heart results in cardiac fibrosis that leads to cardiac dysfunction and heart failure. SNAIL1 is a zinc finger transcription factor implicated in fibrosis following organ injury and cancer. To determine if the action of SNAIL1 contributed to cardiac fibrosis following hypoxic injury, we used an endogenous SNAIL1 bioluminescence reporter mice, and SNAIL1 knockout mouse models. Here we report that SNAIL1 expression is upregulated in the infarcted heart, especially in the myofibroblasts. Utilizing primary cardiac fibroblasts in ex vivo cultures we find that pro-fibrotic factors and collagen I increase SNAIL1 protein level. SNAIL1 is required in cardiac fibroblasts for the adoption of myofibroblast fate, collagen I expression and expression of fibrosis-related genes. Taken together this data suggests that SNAIL1 expression is induced in the cardiac fibroblasts after hypoxic injury and contributes to myofibroblast phenotype and a fibrotic scar formation. Resultant collagen deposition in the scar can maintain elevated SNAIL1 expression in the myofibroblasts and help propagate fibrosis. PMID:27706205

  9. Finite Sholander Trees, Trees, and their Betweenness

    CERN Document Server

    Chvátal, Vašek; Schäfer, Philipp Matthias

    2011-01-01

    We provide a proof of Sholander's claim (Trees, lattices, order, and betweenness, Proc. Amer. Math. Soc. 3, 369-381 (1952)) concerning the representability of collections of so-called segments by trees, which yields a characterization of the interval function of a tree. Furthermore, we streamline Burigana's characterization (Tree representations of betweenness relations defined by intersection and inclusion, Mathematics and Social Sciences 185, 5-36 (2009)) of tree betweenness and provide a relatively short proof.

  10. Crab scars reveal survival advantage of left-handed snails

    OpenAIRE

    Dietl, Gregory P.; Hendricks, Jonathan R.

    2006-01-01

    Biological asymmetries are important elements of the structure and function of many living organisms. Using the Plio–Pleistocene fossil record of crab predation on morphologically similar pairs of right- and left-handed snail species, we show here for the first time, contrary to traditional wisdom, that rare left-handed coiling promotes survival from attacks by right-handed crabs. This frequency-dependent result influences the balance of selection processes that maintain left-handedness at th...

  11. Bioconcentration ratio of diazinon by freshwater fish and snail.

    Science.gov (United States)

    Kanazawa, J

    1978-11-01

    The bioconcentration ratios of diazinon from water by freshwater fishes were generally larger than that of crayfish and snails. Among fishes, the bioconcentration ratio of diazinon by topmouth gudgeon was the highest value, 152 being average. However, elimination of diazinon from fish body was linearly rapid. The influence of test concentration centration ratio of diazinon in whole body of topmouth gudgeon was increased proportional to the body weight.

  12. MICROBIOLOGICAL AND CHEMICAL TESTING OF FOOD SNAILS MARKETEDS IN SARDINIA

    Directory of Open Access Journals (Sweden)

    T. Tedde

    2009-09-01

    Full Text Available A total of 29 samples of snails belonging to the species Helix aspersa, Helix aperta and Helix vermiculata were analysed for the presence of Salmonella spp. and Clostridium perfringens; Cadmium and Lead concentrations were determined by ICP-MS. One sample contained Salmonella sp.; Clostridium perfringens were not detected. The means of toxic metals (expressed as mg/Kg wet weight were the following: Cd 0,995, Pb 0,274. Key words

  13. Characterization of microsatellite loci for the littorine snail Bembicium vittatum.

    Science.gov (United States)

    Kennington, W J; Lukehurst, S S; Johnson, M S

    2008-11-01

    We describe the isolation and development of 17 polymorphic microsatellite loci for the intertidal snail Bembicium vittatum (Gastropoda: Littorinidae). The loci were tested in 46 individuals from a single population situated near the centre of the species distribution. No evidence of linkage disequilibrium was detected between any pair of loci. However, two loci showed significant departures from Hardy-Weinberg expectations. The number of alleles per locus ranged from two to 15. © 2008 The Authors. Journal compilation © 2008 Blackwell Publishing Ltd.

  14. Iron K and Compton hump reverberation in SWIFT J2127.4+5654 and NGC 1365 revealed by NuSTAR and XMM-Newton

    Science.gov (United States)

    Kara, E.; Zoghbi, A.; Marinucci, A.; Walton, D. J.; Fabian, A. C.; Risaliti, G.; Boggs, S. E.; Christensen, F. E.; Fuerst, F.; Hailey, C. J.; Harrison, F. A.; Matt, G.; Parker, M. L.; Reynolds, C. S.; Stern, D.; Zhang, W. W.

    2015-01-01

    In the past five years, a flurry of X-ray reverberation lag measurements of accreting supermassive black holes have been made using the XMM-Newton telescope in the 0.3-10 keV energy range. In this work, we use the NuSTAR (Nuclear Spectroscopic Telescope Array) telescope to extend the lag analysis up to higher energies for two Seyfert galaxies, SWIFT J2127.4+5654 and NGC 1365. X-ray reverberation lags are due to the light travel time delays between the direct continuum emission and the reprocessed emission from the inner radii of an ionized accretion disc. XMM-Newton has been particularly adept at measuring the lag associated with the broad Fe K emission line, where the gravitationally redshifted wing of the line is observed to respond before the line centroid at 6.4 keV, produced at larger radii. Now, we use NuSTAR to probe the lag at higher energies, where the spectrum shows clear evidence for Compton reflection, known as the Compton `hump'. The XMM-Newton data show Fe K lags in both SWIFT J2127.4+5654 and NGC 1365. The NuSTAR data provide independent confirmation of these Fe K lags, and also show evidence for the corresponding Compton hump lags, especially in SWIFT J2127.4+5654. These broad-band lag measurements confirm that the Compton hump and Fe K lag are produced at small radii. At low frequencies in NGC 1365, where the spectrum shows evidence for eclipsing clouds in the line of sight, we find a clear negative (not positive) lag from 2 to 10 keV, which can be understood as the decrease in column density from a neutral eclipsing cloud moving out of our line of sight during the observation.

  15. Impact of cigarette butt leachate on tidepool snails.

    Science.gov (United States)

    Booth, David J; Gribben, Paul; Parkinson, Kerryn

    2015-06-15

    In urban areas, cigarette butts are the most common discarded refuse articles. In marine intertidal zones, they often fall into tidepools. We tested how common intertidal molluscs were affected by butt leachate in a laboratory experiment, where snails were exposed to various leachate concentrations. Mortality was very high, with all species showing 100% mortality at the full leachate concentration (5 butts per litre and 2h soak time) after 8days. However, Austrocochlea porcata showed higher mortality than the other 2 species at lower concentrations (10%, 25%) which may affect the relative abundance of the 3 snails under different concentrations of leachate pollution. Also, sublethal effects of leachate on snail activity were observed, with greater activity of Nerita atramentosa than the other 2 species at higher concentrations, suggesting it is more resilient than the other 2 species. While human health concerns predominate with respect to smoking, we show strong lethal and sublethal (via behavioural modifications) impacts of discarded butts on intertidal organisms, with even closely-related taxa responding differently.

  16. The Compton hump and variable blue wing in the extreme low-flux NuSTAR observations of 1H0707-495

    DEFF Research Database (Denmark)

    Kara, E.; Fabian, A. C.; Lohfink, A. M.;

    2015-01-01

    of a deep 250-ks NuSTAR (Nuclear Spectroscopic Telescope Array) observation of 1H0707-495, which includes the first sensitive observations above 10 keV. Even though the NuSTAR observations caught the source in an extreme low-flux state, the Compton hump is still significantly detected. NuSTAR, with its high...... is that the drop in flux is the blue wing of the relativistically broadened iron K alpha emission line. When the flux is low, the coronal source height is low, thus enhancing the most gravitationally redshifted emission....

  17. A complete mitochondrial genome sequence of the wild two-humped camel (Camelus bactrianus ferus: an evolutionary history of camelidae

    Directory of Open Access Journals (Sweden)

    Meng He

    2007-07-01

    Full Text Available Abstract Background The family Camelidae that evolved in North America during the Eocene survived with two distinct tribes, Camelini and Lamini. To investigate the evolutionary relationship between them and to further understand the evolutionary history of this family, we determined the complete mitochondrial genome sequence of the wild two-humped camel (Camelus bactrianus ferus, the only wild survivor of the Old World camel. Results The mitochondrial genome sequence (16,680 bp from C. bactrianus ferus contains 13 protein-coding, two rRNA, and 22 tRNA genes as well as a typical control region; this basic structure is shared by all metazoan mitochondrial genomes. Its protein-coding region exhibits codon usage common to all mammals and possesses the three cryptic stop codons shared by all vertebrates. C. bactrianus ferus together with the rest of mammalian species do not share a triplet nucleotide insertion (GCC that encodes a proline residue found only in the nd1 gene of the New World camelid Lama pacos. This lineage-specific insertion in the L. pacos mtDNA occurred after the split between the Old and New World camelids suggests that it may have functional implication since a proline insertion in a protein backbone usually alters protein conformation significantly, and nd1 gene has not been seen as polymorphic as the rest of ND family genes among camelids. Our phylogenetic study based on complete mitochondrial genomes excluding the control region suggested that the divergence of the two tribes may occur in the early Miocene; it is much earlier than what was deduced from the fossil record (11 million years. An evolutionary history reconstructed for the family Camelidae based on cytb sequences suggested that the split of bactrian camel and dromedary may have occurred in North America before the tribe Camelini migrated from North America to Asia. Conclusion Molecular clock analysis of complete mitochondrial genomes from C. bactrianus ferus and L

  18. Impact of the age of Biomphalaria alexandrina snails on Schistosoma mansoni transmission: modulation of the genetic outcome and the internal defence system of the snail

    Directory of Open Access Journals (Sweden)

    Iman Fathy Abou-El-Naga

    2015-08-01

    Full Text Available Of the approximately 34 identified Biomphalariaspecies,Biomphalaria alexandrinarepresents the intermediate host of Schistosoma mansoniin Egypt. Using parasitological and SOD1 enzyme assay, this study aimed to elucidate the impact of the age of B. alexandrinasnails on their genetic variability and internal defence against S. mansoniinfection. Susceptible and resistant snails were reared individually for self-reproduction; four subgroups of their progeny were used in experiment. The young susceptible subgroup showed the highest infection rate, the shortest pre-patent period, the highest total cercarial production, the highest mortality rate and the lowest SOD1 activity. Among the young and adult susceptible subgroups, 8% and 26% were found to be resistant, indicating the inheritance of resistance alleles from parents. The adult resistant subgroup, however, contained only resistant snails and showed the highest enzyme activity. The complex interaction between snail age, genetic background and internal defence resulted in great variability in compatibility patterns, with the highest significant difference between young susceptible and adult resistant snails. The results demonstrate that resistance alleles function to a greater degree in adults, with higher SOD1 activity and provide potential implications for Biomphalariacontrol. The identification of the most susceptible snail age enables determination of the best timing for applying molluscicides. Moreover, adult resistant snails could be beneficial in biological snail control.

  19. Biological studies on the snail intermediate hosts of schistosomiasis with a special emphasis on using larval echinostomes as biocontrol agent against larval schistosomes and snails.

    Science.gov (United States)

    Rashed, A A

    2002-12-01

    The present investigation deals with the infectivity of the two snail intermediate hosts of schistosomiasis, Biomphalaria alexandrina and Bulinus truncatus collected from nine drains in Sharkia Governorate, Egypt. The rate of infection among the snails was general low being 0% in many drains. Regarding B. alexandrina, the rate of infection ranged from 4-16%, and in B. truncatus ranged from 4-8%. Infection with larval echinostomes was dominant over larval schistosomes in the two snail vectors. The distribution of larval schistosomes was restricted to the hepatopancreas of the two snail vectors, while larval echinostomes were distributed in head, foot, kidney, haemocoelic cavity, hepatopancreas...etc. The predation of larval schistosomes by larval echinostomes and the severe histopathological effects induced by larval ecbinostomes strongly enhances using them as biocontrol agent. The physico-chemical parameters and pollution condition in the drains seem to have no effect on the process of snails infectivity. It is concluded that larval echinostomes can resist the polluting conditions in the drain. The two snail vectors exhibit very minimal or rare host response against larval echinostomes. Probably, the toxicants and pollutants in the drain may act as stressor that makes the snails much more susceptible to infection by larval trematodes.

  20. Prey-Capture Strategies of Fish-Hunting Cone Snails: Behavior, Neurobiology and Evolution.

    Science.gov (United States)

    Olivera, Baldomero M; Seger, Jon; Horvath, Martin P; Fedosov, Alexander E

    2015-09-01

    The venomous fish-hunting cone snails (Conus) comprise eight distinct lineages evolved from ancestors that preyed on worms. In this article, we attempt to reconstruct events resulting in this shift in food resource by closely examining patterns of behavior, biochemical agents (toxins) that facilitate prey capture and the combinations of toxins present in extant species. The first sections introduce three different hunting behaviors associated with piscivory: 'taser-and-tether', 'net-engulfment' and 'strike-and-stalk'. The first two fish-hunting behaviors are clearly associated with distinct groups of venom components, called cabals, which act in concert to modify the behavior of prey in a specific manner. Derived fish-hunting behavior clearly also correlates with physical features of the radular tooth, the device that injects these biochemical components. Mapping behavior, biochemical components and radular tooth features onto phylogenetic trees shows that fish-hunting behavior emerged at least twice during evolution. The system presented here may be one of the best examples where diversity in structure, physiology and molecular features were initially driven by particular pathways selected through behavior.

  1. Perspectives on land snails - sampling strategies for isotopic analyses

    Science.gov (United States)

    Kwiecien, Ola; Kalinowski, Annika; Kamp, Jessica; Pellmann, Anna

    2017-04-01

    Since the seminal works of Goodfriend (1992), several substantial studies confirmed a relation between the isotopic composition of land snail shells (d18O, d13C) and environmental parameters like precipitation amount, moisture source, temperature and vegetation type. This relation, however, is not straightforward and site dependent. The choice of sampling strategy (discrete or bulk sampling) and cleaning procedure (several methods can be used, but comparison of their effects in an individual shell has yet not been achieved) further complicate the shell analysis. The advantage of using snail shells as environmental archive lies in the snails' limited mobility, and therefore an intrinsic aptitude of recording local and site-specific conditions. Also, snail shells are often found at dated archaeological sites. An obvious drawback is that shell assemblages rarely make up a continuous record, and a single shell is only a snapshot of the environmental setting at a given time. Shells from archaeological sites might represent a dietary component and cooking would presumably alter the isotopic signature of aragonite material. Consequently, a proper sampling strategy is of great importance and should be adjusted to the scientific question. Here, we compare and contrast different sampling approaches using modern shells collected in Morocco, Spain and Germany. The bulk shell approach (fine-ground material) yields information on mean environmental parameters within the life span of analyzed individuals. However, despite homogenization, replicate measurements of bulk shell material returned results with a variability greater than analytical precision (up to 2‰ for d18O, and up to 1‰ for d13C), calling for caution analyzing only single individuals. Horizontal high-resolution sampling (single drill holes along growth lines) provides insights into the amplitude of seasonal variability, while vertical high-resolution sampling (multiple drill holes along the same growth line

  2. Effects of silver nanoparticles on the freshwater snail Physa acuta: The role of test media and snails' life cycle stage.

    Science.gov (United States)

    F Gonçalves, Sandra; D Pavlaki, Maria; Lopes, Rafael; Hammes, Julia; Gallego-Urrea, Julián Alberto; Hassellöv, Martin; Jurkschat, Kerstin; Crossley, Alison; Loureiro, Susana

    2017-01-01

    Silver nanoparticles (AgNPs) are widely used worldwide, most likely leading to their release into the environment and a subsequent increase of environmental concentrations. Studies of their deleterious effects on organisms is crucial to understand their environmental impacts. The freshwater snail Physa acuta was chosen to evaluate the potential deleterious effects of AgNPs and their counterpart AgNO3 , through water-only exposures. The toxicity of AgNPs is greatly influenced by medium composition. Thus, 2 media were tested: artificial pond water (APW) and modified APW (adapted by removing calcium chloride). Acute tests (96 h) were performed with juvenile and adult snails in both media to assess lethality, and egg mass chronic tests were conducted with APW medium only to assess embryo viability and mortality, carried out until 90% hatching success was reached in the control. Acute toxicity increased with decreasing shell length for both silver forms (ion and nanoparticle); that is, juveniles were more sensitive than adults. Different test media led to dissimilar median lethal concentrations, with chloride playing an important role in toxicity, most likely by complexation with silver ions, which would reduce the bioavailability, uptake, and toxicity of silver. Chronic tests showed that hatching success was more sensitive to silver in the ionic form than in the particulate form. Different forms of silver, exposure media, and life cycle stages led to different patterns of toxicity, highlighting an impairment in the snails' life cycle. Environ Toxicol Chem 2017;36:243-253. © 2016 SETAC.

  3. THE BIOCIDE TRIBUTYLTIN REDUCES THE ACCUMULATION OF TESTOSTERONE AS FATTY ACID ESTERS IN THE MUD SNAIL (ILYANASSA OBSOLETA)

    Science.gov (United States)

    Imposex, the development of male sex characteristics by female gonochoristic snails, has been documented globally and is causally associated with exposure to the ubiquitous environmental contaminant tributyltin (TBT). Elevated testosterone levels in snails also are associated wit...

  4. THE BIOCIDE TRIBUTYLTIN REDUCES THE ACCUMULATION OF TESTOSTERONE AS FATTY ACID ESTERS IN THE MUD SNAIL (ILYANASSA OBSOLETA)

    Science.gov (United States)

    Imposex, the development of male sex characteristics by female gonochoristic snails, has been documented globally and is causally associated with exposure to the ubiquitous environmental contaminant tributyltin (TBT). Elevated testosterone levels in snails also are associated wit...

  5. Aquatic snails from mining sites have evolved to detect and avoid heavy metals.

    Science.gov (United States)

    Lefcort, H; Abbott, D P; Cleary, D A; Howell, E; Keller, N C; Smith, M M

    2004-05-01

    Toxicants in polluted environments are often patchily distributed. Hence, rather than being passive absorbers of pollution, some organisms have evolved the ability to detect and avoid toxicants. We studied the avoidance behavior of Physella columbiana, an aquatic pulmonate snail, in a pond that has been polluted with heavy metals for more than 120 years. Populations of this snail are rare at reference sites and are only robust at heavy-metal-polluted sites. We hypothesized that the snails are able to persist because they have evolved the ability to minimize their exposure to metals by actively avoiding metals in their environment. Using a Y-maze flow tank, we tested the avoidance behavior of snails to heavy-metal-polluted sediments and single-metal solutions of cadmium, zinc, or lead. We also tested the avoidance behaviors of the snails' laboratory-reared offspring raised in nonpolluted conditions. In addition, we tested the avoidance behavior of a small population of snails from a reference pond. Although all the snails we tested were able to detect low concentrations of heavy metals, we found that snails from the polluted site were the most sensitive, that their offspring were somewhat less sensitive, and that snails from the reference site were the least sensitive. This suggests that the ability of polluted-site snails to avoid heavy metals is both genetic and environmental. The concentrations of metals avoided by the snails from the polluted site were below the levels found at hot spots within their natal pond. The snails may be able to persist at this site because they decrease their exposure by moving to less-polluted sections of the pond. One application of our findings is the use of aquatic snails and our Y-maze design as an inexpensive pollution detector. Environmental pollutants such as lead, zinc, and arsenic are a problem throughout the world. People in underdeveloped countries often lack sophisticated pollution detection devices. We have developed a

  6. MiR-22 inhibits lung cancer cell EMT and invasion through targeting Snail.

    Science.gov (United States)

    Zhang, K; Li, X-Y; Wang, Z-M; Han, Z-F; Zhao, Y-H

    2017-08-01

    Snail is an important factor in regulating epithelial mesenchymal transition (EMT). Its elevation is related to the enhancement of lung cancer invasion. MicroRNA-22 (MiR-22) plays a role in regulating lung cancer cell invasion. Bioinformatics analysis showed the complementary binding site between miR-22 and Snail. This study aimed to investigate the role of miR-22 in regulating Snail and affecting lung cancer cell invasion and metastasis. Dual luciferase assay confirmed the targeted relationship between miR-22 and Snail. MiR-22 and Snail expressions were compared in MRC-5, Anip973, and AGZY83-a cells. Cell colony formation and invasion were tested in Anip973 and AGYZ83-a cells. Anip973 and AGYZ83-a cells were treated by 5 ng/ml transforming growth factor β1 (TGF-β1) to detect miR-22, Snail, E-cadherin, and N-cadherin expressions. Anip973 cells were cultured in vitro and divided into five groups, including miR-Normal control (miR-NC), miR-22 mimic, small interfering RNA-Normal control (si-NC), si-Snail, and miR-22 mimic + si-Snail groups. MiR-22 targeted inhibited Snail expression. MiR-22 significantly down-regulated, while Snail obviously elevated in Anip973 and AGYZ83-a cells compared with that in MRC-5 cells. Anip973 exhibited markedly stronger invasive and colony formation abilities than AGYZ83-a. TGFβ1 apparently reduced miR-22 and E-cadherin, whereas increased Snail and N-cadherin stronger in Anip973 than that in AGYZ83-a. MiR-22 mimic and/or si-Snail transfection significantly reduced Snail and N-cadherin levels, up-regulated E-cadherin expression, and attenuated cell colony formation and invasion. Down-regulation of miR-22 plays a role in facilitating lung cancer cell EMT and invasion by elevating Snail. MiR-22 over-expression attenuated lung cancer cell EMT and invasion via targeted inhibiting Snail.

  7. Modular Tree Automata

    DEFF Research Database (Denmark)

    Bahr, Patrick

    2012-01-01

    Tree automata are traditionally used to study properties of tree languages and tree transformations. In this paper, we consider tree automata as the basis for modular and extensible recursion schemes. We show, using well-known techniques, how to derive from standard tree automata highly modular r...

  8. Simple street tree sampling

    Science.gov (United States)

    David J. Nowak; Jeffrey T. Walton; James Baldwin; Jerry. Bond

    2015-01-01

    Information on street trees is critical for management of this important resource. Sampling of street tree populations provides an efficient means to obtain street tree population information. Long-term repeat measures of street tree samples supply additional information on street tree changes and can be used to report damages from catastrophic events. Analyses of...

  9. Modular tree automata

    DEFF Research Database (Denmark)

    Bahr, Patrick

    2012-01-01

    Tree automata are traditionally used to study properties of tree languages and tree transformations. In this paper, we consider tree automata as the basis for modular and extensible recursion schemes. We show, using well-known techniques, how to derive from standard tree automata highly modular...

  10. Field prevalence and laboratory susceptibility of southern Australian land snails to Brachylaima cribbi sporocyst infection

    Directory of Open Access Journals (Sweden)

    Butcher A.R.

    2003-06-01

    Full Text Available Brachylaima cribbi is a terrestrial trematode of birds and mammals with helic id and hygromild land snails reported as first and second Intermediate hosts. However, reports describing the first Intermediate host range of B. cribbi have been limited to those snail species present In a small number of geographical locations In South Australia. The natural first Intermediate host range, distribution and prevalence of B. cribbi In land snails In southern Australia were determined. A total of 6,432 introduced and native land snails were collected from eight geographical districts across 3,000 km of southern Australia and examined microscopically for B. cribbi sporocysts. Four Introduced European snails, Theba pisana, Cernuella virgata, Cochlicella acuta and Cochlicella barbara were natural first Intermediate hosts. Sporocyst-infected snails were detected In all districts from Victoria to the west coast of South Australia, a distance of over 1,300 km. Natural sporocyst infection was not observed in introduced European snails Microxeromagna armillata and Helix aspersa or In native Australian land snails Succinea australis and Strangesta gawleri. Egg feeding experiments in the laboratory with B. cribbi confirmed the susceptibility of those species of snails found to be natural first intermediate hosts. Of those species not found to be Infected In nature, only M. armillata could be Infected In the laboratory. Although this study has shown that five different species of European land snails are suitable first Intermediate hosts for B. cribbi there are as yet no reports of B. cribbi from these snails In Europe or from other countries where they have been introduced. Further Investigations are needed in Europe to clarify the origins of this parasite.

  11. Snail transcription factor negatively regulates maspin tumor suppressor in human prostate cancer cells

    Directory of Open Access Journals (Sweden)

    Neal Corey L

    2012-08-01

    Full Text Available Abstract Background Maspin, a putative tumor suppressor that is down-regulated in breast and prostate cancer, has been associated with decreased cell motility. Snail transcription factor is a zinc finger protein that is increased in breast cancer and is associated with increased tumor motility and invasion by induction of epithelial-mesenchymal transition (EMT. We investigated the molecular mechanisms by which Snail increases tumor motility and invasion utilizing prostate cancer cells. Methods Expression levels were analyzed by RT-PCR and western blot analyses. Cell motility and invasion assays were performed, while Snail regulation and binding to maspin promoter was analyzed by luciferase reporter and chromatin immunoprecipitation (ChIP assays. Results Snail protein expression was higher in different prostate cancer cells lines as compared to normal prostate epithelial cells, which correlated inversely with maspin expression. Snail overexpression in 22Rv1 prostate cancer cells inhibited maspin expression and led to increased migration and invasion. Knockdown of Snail in DU145 and C4-2 cancer cells resulted in up-regulation of maspin expression, concomitant with decreased migration. Transfection of Snail into 22Rv1 or LNCaP cells inhibited maspin promoter activity, while stable knockdown of Snail in C4-2 cells increased promoter activity. ChIP analysis showed that Snail is recruited to the maspin promoter in 22Rv1 cells. Conclusions Overall, this is the first report showing that Snail can negatively regulate maspin expression by directly repressing maspin promoter activity, leading to increased cell migration and invasion. Therefore, therapeutic targeting of Snail may be useful to re-induce expression of maspin tumor suppressor and prevent prostate cancer tumor progression.

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

    Science.gov (United States)

    Chah, Jane Mbolle; Inegbedion, Grace

    2013-02-01

    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.

  13. The mitochondrial 16 s rRNA reveals high anthropogenic influence on land snail diversity in a preliminary island survey.

    Science.gov (United States)

    Abu-Bakar, Siti-Balkhis; Razali, Norhanis M; Naggs, Fred; Wade, Christopher; Mohd-Nor, Siti-Azizah; Aileen-Tan, Shau-Hwai

    2014-03-01

    A total of 30 specimens belonging to five species, namely; Cryptozona siamensis, Sarika resplendens and Sarika sp. from the family Ariophantidae as well as Quantula striata and Quantula sp. from the family Dyakiidae were collected from the Langkawi Island in Northern Peninsular Malaysia. All specimens were identified through comparisons of shell morphology and amplification of a 500 bp segment of the 16S rRNA mtDNA gene. To assess phylogenetic insights, the sequences were aligned using ClustalW and phylogenetic trees were constructed. The analyses showed two major lineages in both Maximum Parsimony and Neighbour Joining phylogenetic trees. Each putative taxonomic group formed a monophyletic cluster. Our study revealed low species and intraspecies genetic diversities based on the 16S rRNA gene sequences. Thus, this study has provided an insight of land snail diversity in populations of an island highly influenced by anthropogenic activities through complementary use of shell morphological and molecular data.

  14. The effect of isolation on reproduction and growth of Pseudosuccinea columella (Pulmonata: Lymnaeidae: a snail-conditioned water experiment

    Directory of Open Access Journals (Sweden)

    Gutiérrez Alfredo

    2002-01-01

    Full Text Available A snail-conditioned water experiment was conducted in Pseudosuccinea columella to test the possible role of a chemical interaction between snails on the diminished growth and fecundity rates found for snails raised in pairs compared to those raised in complete isolation. The results permit to discard the hypothesis of an inhibition of growth and reproduction between snails due to factors released into the water.

  15. 76 FR 41811 - Kellaway Proposed Low-Effect Habitat Conservation Plan for the Morro Shoulderband Snail, San Luis...

    Science.gov (United States)

    2011-07-15

    ... Shoulderband Snail, San Luis Obispo County, CA AGENCY: Fish and Wildlife Service, Interior. ACTION: Notice of... ``take'' of the Federally endangered Morro shoulderband snail (Helminthoglypta walkeriana) incidental to..., which includes the Kellaway Low-Effect Habitat Conservation Plan for the Morro Shoulderband Snail...

  16. 78 FR 14587 - Kelley-McDonough Low-Effect Habitat Conservation Plan for the Morro Shoulderband Snail, Community...

    Science.gov (United States)

    2013-03-06

    ... Shoulderband Snail, Community of Los Osos, San Luis Obispo County, California AGENCY: Fish and Wildlife Service... potential for ``take'' of the federally endangered Morro shoulderband snail that is likely to occur... that are likely to result in take of the Morro shoulderband snail as described in their plan. We...

  17. A pilot study testing a natural and a synthetic molluscicide for controlling invasive apple snails (Pomacea maculata)

    Science.gov (United States)

    Pomacea maculata (formerly P. insularum), an apple snail native to South America, was discovered in Louisiana in 2008. These snails strip vegetation, reproduce at tremendous rates, and have reduced rice production and caused ecosystem changes in Asia. In this study snails were exposed to two mollusc...

  18. Measuring Animal Movements in a Natural Ecosystem: A Mark-Recapture Investigation Using Stream-Dwelling Snails

    Science.gov (United States)

    Stewart, Timothy W.

    2007-01-01

    In this investigation, students measure and describe movements of animals in a natural ecosystem. Students mark stream-dwelling snails with nail polish, then search for these snails 1-7 days later. Distances and directions moved by recaptured snails are recorded. Simple statistical techniques are used to answer specific research questions and…

  19. 76 FR 41810 - Francis Proposed Low-Effect Habitat Conservation Plan for the Morro Shoulderband Snail, Los Osos...

    Science.gov (United States)

    2011-07-15

    ... Shoulderband Snail, Los Osos, San Luis Obispo County, CA AGENCY: Fish and Wildlife Service, Interior. ACTION... the potential for ``take'' of the Federally endangered Morro shoulderband snail (Helminthoglypta... includes the Francis Low-Effect Habitat Conservation Plan for the Morro Shoulderband Snail (HCP) that...

  20. Effects of pollution on land snail abundance, size and diversity as resources for pied flycatcher, Ficedula hypoleuca.

    Science.gov (United States)

    Eeva, Tapio; Rainio, Kalle; Suominen, Otso

    2010-09-01

    Passerine birds need extra calcium during their breeding for developing egg shells and proper growth of nestling skeleton. Land snails are an important calcium source for many passerines and human-induced changes in snail populations may pose a severe problem for breeding birds. We studied from the bird's viewpoint how air pollution affects the shell mass, abundance and diversity of land snail communities along a pollution gradient of a copper smelter. We sampled remnant snail shells from the nests of an insectivorous passerine, the pied flycatcher, Ficedula hypoleuca, to find out how the availability of land snails varies along the pollution gradient. The total snail shell mass increased towards the pollution source but declined abruptly in the vicinity of the smelter. This spatial variation in shell mass was evident also within a single snail species and could not be wholly explained by spatially varying snail numbers or species composition. Instead, the total shell mass was related to their shell size, individuals being largest at the moderately polluted areas. Smaller shell size suggests inferior growth of snails in the most heavily polluted area. Our study shows that pollution affects the diversity, abundance (available shell mass) and individual quality of land snails, posing reproductive problems for birds that rely on snails as calcium sources during breeding. There are probably both direct pollution-related (heavy metal and calcium levels) and indirect (habitat change) effects behind the observed changes in snail populations. Copyright 2010 Elsevier B.V. All rights reserved.

  1. Elevated Snail expression in human gingival fibroblasts by cyclosporine A as the possible pathogenesis for gingival overgrowth

    Directory of Open Access Journals (Sweden)

    Yi-Hung Lin

    2015-12-01

    Conclusion: CsA stimulated Snail expression and cell proliferation in HGFs, while silencing Snail could effectively reverse these phenomena. These results may provide new avenues for the design of novel antifibrotic therapies for CsA-induced gingival overgrowth through targeting Snail.

  2. Snail Enhances Glycolysis in the Epithelial-Mesenchymal Transition Process by Targeting FBP1 in Gastric Cancer.

    Science.gov (United States)

    Yu, Jie; Li, Jing; Chen, Yong; Cao, Wenmiao; Lu, Yuanyuan; Yang, Jianqi; Xing, Enmin

    2017-08-24

    Snail is a key regulator of epithelial-mesenchymal transition (EMT) in cancer. However, the regulatory role and underlying mechanisms of Snail in gastric cancer metabolism are unknown. In this study, we characterized the regulation of aerobic glycolysis by Snail in gastric cancer. The impact of Snail on glucose metabolism was studied in vitro. Combining maximum standardized uptake value (SUVmax), which was obtained preoperatively via a PET/CT scan, with immunohistochemistry staining, we further analyzed the correlation between SUVmax and Snail expression in gastric cancer tissues. Increased expression of Snail promoted lactate production, glucose utilization, and decreased FBP1 expression at both mRNA and protein level. The expression level of Snail was positively associated with SUVmax in gastric cancer patients (P=0.022). Snail and FBP1 expression were inversely correlated at both mRNA and protein level (P=0.002 and P=0.015 respectively) in gastric cancer tissues. Further studies demonstrated that Snail inhibited the FBP1 gene expression at the transcriptional level. Restoring FBP1 expression reversed the effects of glycolysis and EMT induced by Snail in gastric cancer cells. Our results thus reveal that Snail serves as a positive regulator of glucose metabolism through regulation of the FBP1 in gastric cancer. Disrupting the Snail-FBP1 signaling axis may be effective to prevent primary tumor EMT and glycolysis process. © 2017 The Author(s). Published by S. Karger AG, Basel.

  3. Population estimate of Chinese mystery snail (Bellamya chinensis) in a Nebraska reservoir

    Science.gov (United States)

    Chaine, Noelle M.; Allen, Craig R.; Fricke, Kent A.; Haak, Danielle M.; Hellman, Michelle L.; Kill, Robert A.; Nemec, Kristine T.; Pope, Kevin L.; Smeenk, Nicholas A.; Stephen, Bruce J.; Uden, Daniel R.; Unstad, Kody M.; VanderHam, Ashley E.

    2012-01-01

    The Chinese mystery snail (Bellamya chinensis) is an aquatic invasive species in North America. Little is known regarding this species' impacts on freshwater ecosystems. It is be lieved that population densities can be high, yet no population estimates have been reported. We utilized a mark-recapture approach to generate a population estimate for Chinese mystery snail in Wild Plum Lake, a 6.47-ha reservoir in southeast Nebraska. We calculated, using bias-adjusted Lincoln-Petersen estimation, that there were approximately 664 adult snails within a 127 m2 transect (5.2 snails/m2). If this density was consistent throughout the littoral zone (Chinese mystery snail wet biomass is estimated to be 3,119 kg (643 kg/ha). If this density is confined to the depth sampled in this study (1.46 m), then the adult population is estimated to be 169,400 snails, and wet biomass is estimated to be 2,084 kg (643 kg/ha). Additional research is warranted to further test the utility of mark-recapture methods for aquatic snails and to better understand Chinese mystery snail distributions within reservoirs.

  4. Activation of the ATM-Snail pathway promotes breast cancer metastasis

    Institute of Scientific and Technical Information of China (English)

    Mianen Sun; David A. Engler; Ming Zhan; Stephen T.C. Wong; Li Fu; Bo Xu; Xiaojing Guo; Xiaolong Qian; Haibo Wang; Chunying Yang; Kathryn L. Brinkman; Monica Serrano-Gonzalez; Richard S. Jope; Binhua Zhou

    2012-01-01

    The DNA damage response (DDR) is critical for the maintenance of genetic stability and serves as an anti-cancer barrier during early tumorigenesis.However,the role of the DDR in tumor progression and metastasis is less known.Here,we demonstrate that the ATM kinase,one of the critical DDR elements,is hyperactive in late stage breast tumor tissues with lymph-node metastasis and this hyperactivity correlates with elevated expression of the epitheliai-mesenchymal transition marker,Snail.At the molecular level,we demonstrate that ATM regulates Snail stabilization by phosphorylation on Serine-100.Using mass spectrometry,we identified HSP90 as a critical binding protein of Snail in response to DNA damage.HsP9o binds to and stabilizes phosphorylated Snail.We further provide in vitro and in vivo evidence that activation of ATM-mediated Snail phosphorylation promotes tumor invasion and metastasis.Finally,we demonstrate that Snail Serine-100 phosphorylation is elevated in breast cancer tissues with lymph-node metastasis,indicating clinical significance of the ATM-Snail pathway.Together,our findings provide strong evidence that the ATM-Snail pathway promotes tumor metastasis,highlighting a previously undescribed role of the DDR in tumor invasion and metastasis.

  5. The non-native faucet snail (Bithynia tentaculata) makes the leap to Lake Superior

    Science.gov (United States)

    The European-origin faucet snail (Bithynia tentaculata) has been present in the lower Great Lakes since the late 1800s but only very recently reached Lake Superior. Surveys from 2011 through 2013 found faucet snail to be abundant and wide-spread in the St. Louis River Estuary wi...

  6. Dry down impacts on apple snail (Pomacea paludosa) demography: Implications for wetland water management

    Science.gov (United States)

    Darby, P.C.; Bennetts, R.E.; Percival, H.F.

    2008-01-01

    Florida apple snails (Pomacea paludosa Say) are prey for several wetland-dependent predators, most notably for the endangered Florida snail kite (Rostrhamus sociabilis Vieillot). Management concerns for kites have been raised regarding the impacts of wetland dry downs on snails, but little data exists to validate these concerns. We simulated drying events in experimental tanks, where we observed that snail survival patterns, regardless of hydrology, were driven by a post-reproductive die off. In contrast to earlier reports of little to no dry down tolerance, we found that 70% of pre-reproductive adult-sized snails survived a 12-week dry down. Smaller size classes of snails exhibited significantly lower survival rates (snail breeding season, and 70% of dry downs were ??? 12 weeks in duration. Dry down timing can affect recruitment by truncating annual egg production and stranding juveniles. Dry down survival rates and seasonal patterns of egg cluster production helped define a range of hydrologic conditions that support robust apple snail populations, and illustrate why multiple characteristics of dry down events should be considered in developing target hydrologic regimes for wetland fauna. ?? 2008, The Society of Wetland Scientists.

  7. Local adaptation of the trematode Fasciola hepatica to the snail Galba truncatula

    Directory of Open Access Journals (Sweden)

    Dreyfuss G.

    2012-08-01

    Full Text Available Experimental infections of six riverbank populations of Galba truncatula with Fasciola hepatica were carried out to determine if the poor susceptibility of these populations to this digenean might be due to the scarcity or the absence of natural encounters between these snails and the parasite. The first three populations originated from banks frequented by cattle in the past (riverbank group whereas the three others were living on islet banks without any known contact with local ruminants (islet group. After their exposure, all snails were placed in their natural habitats from the end of October up to their collection at the beginning of April. Compared to the riverbank group, snails, which died without cercarial shedding clearly predominated in the islet group, while the other infected snails were few in number. Most of these last snails released their cercariae during a single shedding wave. In islet snails dissected after their death, the redial and cercarial burdens were significantly lower than those noted in riverbank G. truncatula. Snails living on these islet banks are thus able to sustain larval development of F. hepatica. The modifications noted in the characteristics of snail infection suggest the existence of an incomplete adaptation between these G. truncatula and the parasite, probably due to the absence of natural contact between host and parasite.

  8. Larval stages of digenetic trematodes in Melanopsis praemorsa snails from freshwater bodies in Palestine

    Institute of Scientific and Technical Information of China (English)

    Sami Bdir; Ghaleb Adwan

    2011-01-01

    Objective: To detect the species of larval trematodes (cercariae) in Melanopsis praemorsa snails from 5 different fresh water bodies in Palestine. Methods: A total of 1 880 Melanopsis praemorsa snails were collected from different fresh water bodies in Palestine from October, 2008 to November, 2010. Cercariae in Melanopsis praemorsa snails were obtained by lighting and crushing methods. The behavior of cercariae was observed using a dissecting microscope. Results: Three different species of larval trematodes were identified from Melanopsis praemorsa snails collected only from Al-Bathan fresh water body, while snails from other water bodies were not infected. These species were microcercous cercaria, xiphidiocercaria and brevifurcate lophocercous cercaria. These cercariae called Cercaria melanopsi palestinia I, Cercaria melanopsi palestinia II and Cercaria melanopsi palestinia III have not been described before from this snail in Palestine. The infection rate of Melanopsis praemorsa collected from Al-Bathan fresh water body was 5.7%, while the overall infection rate of snails collected from all fresh water bodies was 4.3%. Details are presented on the morphology and behavior of the cercariae as well as their development within the snail. Conclusions: These results have been recorded for the first time and these cercariae may be of medical and veterinary importance.

  9. 50 CFR 17.45 - Special rules-snails and clams. [Reserved

    Science.gov (United States)

    2010-10-01

    ... 50 Wildlife and Fisheries 2 2010-10-01 2010-10-01 false Special rules-snails and clams. 17.45 Section 17.45 Wildlife and Fisheries UNITED STATES FISH AND WILDLIFE SERVICE, DEPARTMENT OF THE INTERIOR... Special rules—snails and clams....

  10. Studies on the molluscicidal activity of Agave angustifolia and Pittosporum tobira on schistosomiasis transmitting snails.

    Science.gov (United States)

    Ibrahim, Abdalla M; Abdel-Gawad, Mahfouz M; El-Nahas, Hanan A; Osman, Nadia S

    2015-04-01

    In the search for new molluscicidal plants for controlling the snail vectors of schistosomiasis, laboratory evaluation was made to assess the molluscicidal activity of Agave angustifolia and Pittosporum tobira plants against Biomphalaria alexandrina snails. Results indicated that both plants have promising molluscicidal activity as the LC90 of the dry powder of both plants was 120 ppm. Both plants showed marked cercaricidal and miracidicidal potencies against S. mansoni larvae. The LC90 of both plants (120 ppm) killed most B. alexandrina eggs within 24 h of exposure. The sub-lethal concentrations of both plants markedly suppressed the survival rate of B. alexandrina snails and the mortality increased with increasing the concentrations and the exposure period up to 10 successive weeks. The accumulative toxic effect of these concentrations was continuous during the recovery period. Also, the reproductive rates of exposed snails were greatly affected even through the recovery period. This depression in reproductive ability of snails was accompanied by histological damage in the hermaphrodite glands of exposed snails. Meanwhile, the growth of snails was estimated weekly and it showed great inhibition in exposed snails comparing with the control ones.

  11. Unpredictable responses of garden snail (Helix aspersa) populations to climate change

    NARCIS (Netherlands)

    Bezemer, T.M.; Knight, K.J.

    2001-01-01

    We studied the impact of climate change on the population dynamics of the garden snail (Helix aspersa) in the Ecotron controlled environment facility. The experimental series ran for three plant generations, allowing the snails to reproduce. We investigated the isolated and combined effects of eleva

  12. Exploring the temporal effects of seasonal water availability on the snail kite of Florida: Part III

    Science.gov (United States)

    Mooij, Wolf M.; Martin, Julien; Kitchens, Wiley M.; DeAngelis, Donald L.; Bissonette, John A.; Storch, Ilse

    2007-01-01

    The Florida snail kite (Rostrhamus sociabilis) is an endangered raptor that occurs as an isolated population, currently of about 2,000 birds, in the wetlands of southern and central Florida, USA. Its exclusive prey species, the apple snail (Pomacea paludosa) is strongly influenced by seasonal changes in water abundance. Droughts during the snail kite breeding season have a direct negative effect on snail kite survival and reproduction, but droughts are also needed to maintain aquatic vegetation types favorable to snail kite foraging for snails. We used a spatially explicit matrix model to explore the effects of temporal variation in water levels on the viability of the snail kite population under different temporal drought regimes in its wetland breeding habitat. We focused on three aspects of variations in water levels that were likely to affect kites: (1) drought frequency; (2) drought duration; and (3) drought timing within the year. We modeled a 31-year historical scenario using four different scenarios in which the average water level was maintained constant, but the amplitude of water level fluctuations was modified. Our results reveal the complexity of the effects of temporal variation in water levels on snail kite population dynamics. Management implications of these results are discussed. In particular, management decisions should not be based on annual mean water levels alone, but must consider the intra-annual variability.

  13. Identification of Medically Important Snails of Miangran Lake in Izeh, Khuzestan Province of Iran

    Directory of Open Access Journals (Sweden)

    Valipour Nouroozi

    2015-11-01

    Full Text Available Background Some freshwater snails are acting as intermediate hosts for digenetic trematodes. Studies on distribution of freshwater snails are important to determine the transmission patterns of the trematoda. Objectives The current study aimed to identify medically important snails of Miangran Lake in Izeh, Khuzestan province, Iran. Materials and Methods Sampling was conducted in fourteen sites around Miangran Lake in 2014. The collected samples were placed in plastic containers containing 70% ethyl alcohol, prior to consideration. The identification was carried out according to shell characteristics. Data were analyzed descriptively. Results All sampling sites were positive for medically important snails. Overall, nine genera and thirteen species were identified. The most diversity in genus was found in Melanopsis. Five genera of snails detected in the study with known medical importance include: Bithynia spp., Bulinus spp., Lymnaea spp., Melanoides spp. and Melanopsis spp. Melanoides spp. was observed in thirteen and Bellamya spp. was identified in two sites. Also, in this study Melanoides spp., Bulinus spp., and Lymnaea spp. were widespread snails around Miangran Lake. Conclusions The reason for difference in the detected snail genera in sampling sites may be due to various physicochemical factors. According to the current study, medically important snails exist in Miangran Lake and they could be a source of trematode infections for the local people. Controlling measures after comprehensive studies should be applied.

  14. Delimitation and phylogenetics of the diverse land snail family Urocoptidae (Gastropoda: Pulmonata): A reunion with Cerion

    NARCIS (Netherlands)

    Uit de Weerd, Dennis R.

    2010-01-01

    The extreme morphological diversity in the land-snail family Urocoptidae has complicated its delimitation from other land-snail families, and has obscured its intra- and interfamilial phylogenetic relationships. Using an independent dataset of 28S rRNA DNA-sequence data, I tested morphologybased hyp

  15. Snail/beta-catenin signaling protects breast cancer cells from hypoxia attack

    Energy Technology Data Exchange (ETDEWEB)

    Scherbakov, Alexander M., E-mail: alex.scherbakov@gmail.com [Laboratory of Clinical Biochemistry, Institute of Clinical Oncology, N.N. Blokhin Cancer Research Centre, Kashirskoye sh. 24, Moscow 115478 (Russian Federation); Stefanova, Lidia B.; Sorokin, Danila V.; Semina, Svetlana E. [Laboratory of Molecular Endocrinology, Institute of Carcinogenesis, N.N. Blokhin Cancer Research Centre, Kashirskoye sh. 24, Moscow 115478 (Russian Federation); Berstein, Lev M. [Laboratory of Oncoendocrinology, N.N. Petrov Research Institute of Oncology, St. Petersburg 197758 (Russian Federation); Krasil’nikov, Mikhail A. [Laboratory of Molecular Endocrinology, Institute of Carcinogenesis, N.N. Blokhin Cancer Research Centre, Kashirskoye sh. 24, Moscow 115478 (Russian Federation)

    2013-12-10

    The tolerance of cancer cells to hypoxia depends on the combination of different factors – from increase of glycolysis (Warburg Effect) to activation of intracellular growth/apoptotic pathways. Less is known about the influence of epithelial–mesenchymal transition (EMT) and EMT-associated pathways on the cell sensitivity to hypoxia. The aim of this study was to explore the role of Snail signaling, one of the key EMT pathways, in the mediating of hypoxia response and regulation of cell sensitivity to hypoxia, using as a model in vitro cultured breast cancer cells. Earlier we have shown that estrogen-independent HBL-100 breast cancer cells differ from estrogen-dependent MCF-7 cells with increased expression of Snail1, and demonstrated Snail1 involvement into formation of hormone-resistant phenotype. Because Snail1 belongs to hypoxia-activated proteins, here we studied the influence of Snail1 signaling on the cell tolerance to hypoxia. We found that Snail1-enriched HBL-100 cells were less sensitive to hypoxia-induced growth suppression if compared with MCF-7 line (31% MCF-7 vs. 71% HBL-100 cell viability after 1% O{sub 2} atmosphere for 3 days). Snail1 knock-down enhanced the hypoxia-induced inhibition of cell proliferation giving the direct evidence of Snail1 involvement into cell protection from hypoxia attack. The protective effect of Snail1 was shown to be mediated, at least in a part, via beta-catenin which positively regulated expression of HIF-1-dependent genes. Finally, we found that cell tolerance to hypoxia was accompanied with the failure in the phosphorylation of AMPK – the key energy sensor, and demonstrated an inverse relationship between AMPK and Snail/beta-catenin signaling. Totally, our data show that Snail1 and beta-catenin, besides association with loss of hormone dependence, protect cancer cells from hypoxia and may serve as an important target in the treatment of breast cancer. Moreover, we suggest that the level of these proteins as well

  16. Prostaglandin E₂ receptor EP2 mediates Snail expression in hepatocellular carcinoma cells.

    Science.gov (United States)

    Cheng, Shan-Yu; Zhang, Hai; Zhang, Min; Xia, Shu-Kai; Bai, Xiao-Ming; Zhang, Li; Ma, Juan; Rong, Rong; Wang, Yi-Pin; Du, Ming-Zhan; Wang, Jie; Chen, Meng; Shi, Feng; Yang, Qin-Yi; Leng, Jing

    2014-05-01

    Prostaglandin E2 (PGE2) has been shown to influence cell invasion and metastasis in several types of cancer, including hepatocellular carcinoma (HCC). however, the molecular mechanisms underlying it remain to be further elucidated. Snail, as one of key inducers of epithelial-mesenchymal transition (EMT), plays pivotal roles in HCC invasion and metastasis. The present study was designed to evaluate the possible signaling pathways through which PGE2 regulates Snail protein expression in HCC cell lines. PGE2 markedly enhanced Huh-7 cell invasion and migration ability by upregulating the expression level of Snail protein, and EP2 receptor played an important role in this process. Src, EGFR, Akt and mTOR were all activated and involved in the regulation of snail protein expression. Our findings suggest that PGE2 could upregulate the expression level of Snail protein through the EP2/Src/EGFR/Akt/mTOR pathway in Huh-7 cells, which promotes HCC cell invasion and migration.

  17. Mesenchymal cells reactivate Snail1 expression to drive three-dimensional invasion programs

    DEFF Research Database (Denmark)

    Rowe, R.G.; Li, X.Y.; Hu, Y.

    2009-01-01

    Epithelial-mesenchymal transition (EMT) is required for mesodermal differentiation during development. The zinc-finger transcription factor, Snail1, can trigger EMT and is sufficient to transcriptionally reprogram epithelial cells toward a mesenchymal phenotype during neoplasia and fibrosis....... Whether Snail1 also regulates the behavior of terminally differentiated mesenchymal cells remains unexplored. Using a Snai1 conditional knockout model, we now identify Snail1 as a regulator of normal mesenchymal cell function. Snail1 expression in normal fibroblasts can be induced by agonists known...... to promote proliferation and invasion in vivo. When challenged within a tissue-like, three-dimensional extracellular matrix, Snail1-deficient fibroblasts exhibit global alterations in gene expression, which include defects in membrane type-1 matrix metalloproteinase (MT1-MMP)-dependent invasive activity...

  18. Juveniles of Lymnaea 'smart' snails do not perseverate and have the capacity to form LTM.

    Science.gov (United States)

    Shymansky, Tamila; Protheroe, Amy; Hughes, Emily; Swinton, Cayley; Swinton, Erin; Lukowiak, Kai S; Phillips, Iain; Lukowiak, Ken

    2017-02-01

    Previously, it was concluded that the nervous systems of juvenile snails were not capable of mediating long-term memory (LTM). However, exposure and training of those juvenile snails in the presence of a predator cue significantly altered their ability to learn and form LTM. In addition, there are some strains of Lymnaea which have been identified as 'smart'. These snails form LTM significantly better than the lab-bred strain. Here, we show that juveniles of two smart snail strains not only are capable of associative learning but also have the capacity to form LTM following a single 0.5 h training session. We also show that freshly collected 'wild' 'average' juveniles are also not able to form LTM. Thus, the smart snail phenotype in these strains is expressed in juveniles.

  19. Land snails (Mollusca: Gastropoda of India: status, threats and conservation strategies

    Directory of Open Access Journals (Sweden)

    S. Sen

    2012-09-01

    Full Text Available Land snails form an important component in the forest ecosystem. In terms of number of species, the phylum Mollusca, to which land snails belong, is the largest phylum after Arthropoda. Mollusca provide unique ecosystem services including recycling of nutrients and they provide a prey base for small mammals, birds, snakes and other reptiles. However, land snails have the largest number of documented extinctions, compared to any other taxa. Till date 1,129 species of land snails are recorded from Indian territory. But only basic information is known about their taxonomy and little is known of their population biology, ecology and their conservation status. In this paper, we briefly review status, threats and conservation strategies of land snails of India.

  20. Lymnaea stagnalis Snails Infection in Trematoda Larval of Shahrekord City Springs

    Directory of Open Access Journals (Sweden)

    Shahla Rivaz

    2014-03-01

    Full Text Available Abstract Background and objective: This study was established to determine the lymnaea stagnalis snails’ infection with trematodes larval stage in one of the springs of the Shahrekord city in Chahar Mahal and Bakhtiari. Materials and methods: To determine the snail infection to trematodes larval stages, the snails were caught from the field, and transferred to the Parasitology department of Razi Vaccine and Serum research Institute. Then stimulating of snails by light, tubing and squashing of them were used to detection and identification of the isolated cercariae. Results: Of 400 collected Snails from the referred springs, 320 of them identified as lymnaea stagnalis. Observed cercariae were identified and classificated as order Plagiorchis, family plagiorchiidae and genus opisthioglyphe and plagiorchis. In Chahar Mahal and Bakhtiari province due to having more than 10% of water content of country, ecological conditions can play important role to developing sensitive snail especially Lymnaeidae and be considered as a critical and suitable habitat for them.

  1. Phenotypic plasticity in the common garden snail: big guts and heavier mucus glands compete in snails faced with the dual challenge of poor diet and coarse substrate.

    Science.gov (United States)

    Munn, Adam J; Treloar, Marguerite

    2016-12-26

    Phenotypic plasticity allows animals to manage environmental challenges. Studies aimed at quantifying plasticity often focus on one challenge, such as diet, and one organ system, such the gastrointestinal tract, but this approach may not adequately reflect how plasticity could buffer multiple challenges. Thus, we investigated the outcomes of a dual challenge experiment that fed land snails either a high-fibre (low quality) or a low-fibre (high quality) diet, and simultaneously exercised them daily over 1.2 m on either a smooth surface of polyvinyl chloride (PVC) or a rough sandpaper. By the end of 20 days, snails fed the poor quality diet had a longer crop and oesophagus and a heavier intestine and rectum than those offered a low-fibre diet. Additionally, high-fibre fed snails had a smaller spermoviduct and oviduct. When also exercised on sandpaper, high-fibre fed snails had a smaller digestive gland, a main energy store, than those exercised on PVC. All snails exercised on sandpaper had a heavier pedal mucus gland, used a loping gait and used less mucus than those on PVC plastic, but there was no difference in the average speed of snails on either surface, supporting the conclusion that loping is a mucus conserving gait. Notably, snails faced with both a diet and substrate challenge had a smaller kidney, which could directly effect fecundity. This demonstrates that our dual challenge approach has potential for evaluating the costs and limits of the plasticity necessary to fully appreciate the evolutionary significance of plasticity in snails and other species.

  2. Effects of an exotic prey species on a native specialist: example of the snail kite

    Science.gov (United States)

    Cattau, Christopher E.; Martin, J.; Kitchens, Wiley M.

    2010-01-01

    Despite acknowledging that exotic species can exhibit tremendous influence over native populations, few case studies have clearly demonstrated the effects of exotic prey species on native predators. We examined the effects of the recently introduced island apple snail (Pomacea insularum) on the foraging behavior and energetics of the endangered snail kite (Rostrhamus sociabilis plumbeus) in Florida. We conducted time-activity budgets: (i) on kites foraging for native Florida apple snails (Pomacea paludosa) in major wetland units within the kites' range that had not been invaded by the exotic island apple snail and (ii) on kites foraging for exotic apple snails in Lake Tohopekaliga, the only major wetland utilized by the snail kite that had suffered a serious invasion of P. insularum. When foraging for P. insularum, snail kites dropped a greater proportion of snails, and they experienced increased handling times and decreased consumption rates; however, kites foraging for P. insularum also spent a smaller proportion of the day in flight. Estimates of net daily energy balances between kites feeding on P. insularum versus P. paludosa were comparable for adults, but juveniles experienced energetic deficiencies when feeding on the exotic snail. Due to this discrepancy, we hypothesize that wetlands invaded by P. insularum, such as Lake Tohopekaliga, may function as ecological traps for the snail kite in Florida by attracting breeding adults but simultaneously depressing juvenile survival. This study highlights the conservation implications and importance of elucidating the effects that exotic species have on native specialists, especially those that are endangered, because subtle influences on behavior may have significant population consequences.

  3. Effects of an exotic prey species on a native specialist: Eexample of the snail kite

    Science.gov (United States)

    Cattau, Christopher E.; Martin, J.; Kitchens, W.M.

    2010-01-01

    Despite acknowledging that exotic species can exhibit tremendous influence over native populations, few case studies have clearly demonstrated the effects of exotic prey species on native predators. We examined the effects of the recently introduced island apple snail (Pomacea insularum) on the foraging behavior and energetics of the endangered snail kite (Rostrhamus sociabilis plumbeus) in Florida. We conducted time-activity budgets: (i) on kites foraging for native Florida apple snails (Pomacea paludosa) in major wetland units within the kites' range that had not been invaded by the exotic island apple snail and (ii) on kites foraging for exotic apple snails in Lake Tohopekaliga, the only major wetland utilized by the snail kite that had suffered a serious invasion of P. insularum. When foraging for P. insularum, snail kites dropped a greater proportion of snails, and they experienced increased handling times and decreased consumption rates; however, kites foraging for P. insularum also spent a smaller proportion of the day in flight. Estimates of net daily energy balances between kites feeding on P. insularum versus P. paludosa were comparable for adults, but juveniles experienced energetic deficiencies when feeding on the exotic snail. Due to this discrepancy, we hypothesize that wetlands invaded by P. insularum, such as Lake Tohopekaliga, may function as ecological traps for the snail kite in Florida by attracting breeding adults but simultaneously depressing juvenile survival. This study highlights the conservation implications and importance of elucidating the effects that exotic species have on native specialists, especially those that are endangered, because subtle influences on behavior may have significant population consequences. ?? 2009 Elsevier Ltd.

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

    Science.gov (United States)

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

    2012-01-01

    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

  5. Changes in frequency of spontaneous oscillations in procerebrum correlate to behavioural choice in terrestrial snails

    Directory of Open Access Journals (Sweden)

    Elena Samarova

    2009-08-01

    Full Text Available 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.

  6. Targeted inactivation of Snail family EMT regulatory factors by a Co(III-Ebox conjugate.

    Directory of Open Access Journals (Sweden)

    Allison S Harney

    Full Text Available 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.

  7. Impact of Snail and E-cadherin expression in pancreatic neuroendocrine tumors.

    Science.gov (United States)

    Yonemori, Keiichi; Kurahara, Hiroshi; Maemura, Kosei; Mataki, Yuko; Sakoda, Masahiko; Iino, Satoshi; Ueno, Shinichi; Shinchi, Hiroyuki; Natsugoe, Shoji

    2017-08-01

    Pancreatic neuroendocrine tumors (PNETs) are a rare type of malignancy with a prognosis that is relatively good, compared with that of pancreatic adenocarcinoma. However, a number of patients with PNETs have distant metastasis and a less favorable prognosis. Epithelial-mesenchymal transition (EMT) is essential for tumor progression and metastasis. Snail and E-cadherin serve key roles in the process of EMT in numerous tumor types, including gastric and pancreatic adenocarcinoma. However, the role of EMT in PNETs remains unclear. The aim of the present study was to investigate the significance of Snail and E-cadherin expression in PNETs. Tissue samples were obtained from 40 resected PNETs. The expression of Snail and E-cadherin was evaluated in the primary tumors using immunohistochemical staining. The association between protein expression and patient clinicopathological features was then analyzed. High and low Snail expression levels were observed in 11 (27.5%) and 29 (72.5%) patients, respectively. Preserved and reduced E-cadherin expression was observed in 19 (47.5%) and 21 (52.5%) patients, respectively. Patients with low Snail expression and preserved E-cadherin expression had a significantly lower risk of vascular invasion, lymphatic invasion, lymph node metastasis and liver metastasis and a lower WHO classification, as compared with the group that included patients with high Snail and reduced E-cadherin, high Snail and preserved E-cadherin, and low Snail and reduced E-cadherin expression. In addition, the patients with low Snail expression levels and preserved E-cadherin expression had more a favorable prognosis compared with the other group. The present study indicates that EMT serves an important role in tumor progression in PNETs. Immunohistochemical evaluation of Snail and E-cadherin is useful for predicting the risk of vessel invasion and metastasis in PNETs.

  8. Speciation and gene flow between snails of opposite chirality.

    Directory of Open Access Journals (Sweden)

    Angus Davison

    2005-09-01

    Full Text Available 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

  9. Cisplatin promotes mesenchymal-like characteristics in osteosarcoma through Snail.

    Science.gov (United States)

    Fang, Shuo; Yu, Ling; Mei, Hongjun; Yang, Jian; Gao, Tian; Cheng, Anyuan; Guo, Weichun; Xia, Kezhou; Liu, Gaiwei

    2016-12-01

    More than 30% of patients with osteosarcoma succumb to pulmonary metastases. Epithelial-mesenchymal transition (EMT) is a biological process by which tumor cells gain an increased capacity for invasiveness and metastasis. A previous study confirmed the phenomenon of EMT in osteosarcoma, a mesenchymal-derived tumor. However, whether chemotherapy affects EMT remains to be elucidated. In the present study, the osteosarcoma cells were exposed to a sublethal dose of cisplatin, and any surviving cells were assumed to be more resistant to cisplatin. In addition, these cells exhibited a more mesenchymal phenotype. Immunofluorescence analysis revealed that the cisplatin treated cells had an increased long/short axis ratio and increased expression of N-cadherin compared with control cells. A panel of EMT-associated genes was subsequently assessed by quantitative PCR and western blot analysis, and they were observed to be significantly upregulated in the cisplatin treated cells. The in vitro wound healing and Transwell assay indicated that the cisplatin treated cells were more prone to migrate and invade. An in vivo assay showed that the cisplatin-treated xenograft had increased expression of EMT-associated genes, and exhibited increased pulmonary lesions compared with the control, which indicated an elevated capacity to metastasize. The expression of Snail was knocked down by specific small interfering RNA, and it was observed that Snail inhibition promoted cisplatin sensitivity, and cisplatin-induced EMT was significantly blocked. Taken together, the results of the present study supported that idea that Snail participates in cisplatin-induced EMT in osteosarcoma cells, and targeting EMT-transcription factors may offer promise for the therapeutics of osteosarcoma.

  10. Crab scars reveal survival advantage of left-handed snails.

    Science.gov (United States)

    Dietl, Gregory P; Hendricks, Jonathan R

    2006-09-22

    Biological asymmetries are important elements of the structure and function of many living organisms. Using the Plio-Pleistocene fossil record of crab predation on morphologically similar pairs of right- and left-handed snail species, we show here for the first time, contrary to traditional wisdom, that rare left-handed coiling promotes survival from attacks by right-handed crabs. This frequency-dependent result influences the balance of selection processes that maintain left-handedness at the species level and parallels some social interactions in human cultures, such as sports that involve dual contests between opponents of opposite handedness.

  11. Ecological Speciation and the Intertidal Snail Littorina saxatilis

    Directory of Open Access Journals (Sweden)

    Juan Galindo

    2014-01-01

    Full Text Available In recent decades biologists studying speciation have come to consider that the process does not necessarily require the presence of a geographical barrier. Rather, it now seems to be possible for reproductive barriers to evolve within what was hitherto a single ‘‘species.’’ The intertidal snail Littorina saxatilis has been the focus of a considerable amount of work in this context, and it is now thought of as a good case study of ‘‘ecological speciation.’’ We review some of this work and briefly consider prospects for future developments.

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

    Science.gov (United States)

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

    2010-01-01

    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.

  13. Polymorphisms in the Human SNAIL (SNAI1) gene.

    Science.gov (United States)

    Okajima, K; Paznekas, W A; Burstyn, T; Jabs, E W

    2001-02-01

    The human SNAIL is an important developmental protein involved in the formation of mesoderm and neural crest. The protein contains three classic and one atypical zinc-finger motif. The SNAI1 gene is composed of three exons. We have identified three SNPs in non-coding regions, two in the 5'UTR and one in intron 1, which can be detected by PCR followed by restriction enzyme digestion. We also identified a GGG/GGGG polymorphism in intron 1. We screened CEPH DNAs for these polymorphisms. Copyright 2001 Academic Press.

  14. Global climate change will increase the abundance of symbiotic nitrogen-fixing trees in much of North America.

    Science.gov (United States)

    Liao, Wenying; Menge, Duncan N L; Lichstein, Jeremy W; Ángeles-Pérez, Gregorio

    2017-11-01

    Symbiotic nitrogen (N)-fixing trees can drive N and carbon cycling and thus are critical components of future climate projections. Despite detailed understanding of how climate influences N-fixation enzyme activity and physiology, comparatively little is known about how climate influences N-fixing tree abundance. Here, we used forest inventory data from the USA and Mexico (>125,000 plots) along with climate data to address two questions: (1) How does the abundance distribution of N-fixing trees (rhizobial, actinorhizal, and both types together) vary with mean annual temperature (MAT) and precipitation (MAP)? (2) How will changing climate shift the abundance distribution of N-fixing trees? We found that rhizobial N-fixing trees were nearly absent below 15°C MAT, but above 15°C MAT, they increased in abundance as temperature rose. We found no evidence for a hump-shaped response to temperature throughout the range of our data. Rhizobial trees were more abundant in dry than in wet ecosystems. By contrast, actinorhizal trees peaked in abundance at 5-10°C MAT and were least abundant in areas with intermediate precipitation. Next, we used a climate-envelope approach to project how N-fixing tree relative abundance might change in the future. The climate-envelope projection showed that rhizobial N-fixing trees will likely become more abundant in many areas by 2080, particularly in the southern USA and western Mexico, due primarily to rising temperatures. Projections for actinorhizal N-fixing trees were more nuanced due to their nonmonotonic dependence on temperature and precipitation. Overall, the dominant trend is that warming will increase N-fixing tree abundance in much of the USA and Mexico, with large increases up to 40° North latitude. The quantitative link we provide between climate and N-fixing tree abundance can help improve the representation of symbiotic N fixation in Earth System Models. © 2017 John Wiley & Sons Ltd.

  15. Host density increases parasite recruitment but decreases host risk in a snail-trematode system.

    Science.gov (United States)

    Buck, J C; Hechinger, R F; Wood, A C; Stewart, T E; Kuris, A M; Lafferty, K D

    2017-08-01

    Most species aggregate in local patches. High host density in patches increases contact rate between hosts and parasites, increasing parasite transmission success. At the same time, for environmentally transmitted parasites, high host density can decrease infection risk to individual hosts, because infective stages are divided among all hosts in a patch, leading to safety in numbers. We tested these predictions using the California horn snail, Cerithideopsis californica (=Cerithidea californica), which is the first intermediate host for at least 19 digenean trematode species in California estuaries. Snails become infected by ingesting trematode eggs or through penetration by free-swimming miracidia that hatch from trematode eggs deposited with final-host (bird or mammal) feces. This complex life cycle decouples infective-stage production from transmission, raising the possibility of an inverse relationship between host density and infection risk at local scales. In a field survey, higher snail density was associated with increased trematode (infected snail) density, but decreased trematode prevalence, consistent with either safety in numbers, parasitic castration, or both. To determine the extent to which safety in numbers drove the negative snail-density-trematode-prevalence association, we manipulated uninfected snail density in 83 cages at eight sites within Carpinteria Salt Marsh (California, USA). At each site, we quantified snail density and used data on final-host (bird and raccoon) distributions to control for between-site variation in infective-stage supply. After three months, overall trematode infections per cage increased with snail biomass density. For egg-transmitted trematodes, per-snail infection risk decreased with snail biomass density in the cage and surrounding area, whereas per-snail infection risk did not decrease for miracidium-transmitted trematodes. Furthermore, both trematode recruitment and infection risk increased with infective

  16. Host density increases parasite recruitment but decreases host risk in a snail-trematode system

    Science.gov (United States)

    Buck, Julia C; Hechinger, R.F.; Wood, A.C.; Stewart, T.E.; Kuris, A.M.; Lafferty, Kevin D.

    2017-01-01

    Most species aggregate in local patches. High host density in patches increases contact rate between hosts and parasites, increasing parasite transmission success. At the same time, for environmentally-transmitted parasites, high host density can decrease infection risk to individual hosts, because infective stages are divided among all hosts in a patch, leading to safety in numbers. We tested these predictions using the California horn snail, Cerithideopsis californica (=Cerithidea californica), which is the first intermediate host for at least 19 digenean trematode species in California estuaries. Snails become infected by ingesting trematode eggs or through penetration by free-swimming miracidia that hatch from trematode eggs deposited with final-host (bird or mammal) feces. This complex life cycle decouples infective-stage production from transmission, raising the possibility of an inverse relationship between host density and infection risk. In a field survey, higher snail density was associated with increased trematode (infected snail) density, but decreased trematode prevalence, consistent with either safety in numbers, parasitic castration, or both. To determine the extent to which safety in numbers drove the negative snail density-trematode prevalence association, we manipulated uninfected snail density in 83 cages at eight sites within Carpinteria Salt Marsh (CA, USA). At each site, we quantified snail density and used data on final-host (bird and raccoon) distributions to control for between-site variation in infective-stage supply. After three months, overall trematode infections per cage increased with snail-biomass density. For egg-transmitted trematodes, per-snail infection risk decreased with snail-biomass density in the cage and surrounding area, whereas per-snail infection risk did not decrease for miracidium-transmitted trematodes. Furthermore, both trematode recruitment and infection risk increased with infective-stage input, but this was

  17. Modelling climate change impact on the spatial distribution of fresh water snails hosting trematodes in Zimbabwe.

    Science.gov (United States)

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

    2014-12-12

    Freshwater snails are intermediate hosts for a number of trematodes of which some are of medical and veterinary importance. The trematodes rely on specific species of snails to complete their life cycle; hence the ecology of the snails is a key element in transmission of the parasites. More than 200 million people are infected with schistosomes of which 95% live in sub-Saharan Africa and many more are living in areas where transmission is on-going. Human infection with the Fasciola parasite, usually considered more of veterinary concern, has recently been recognised as a human health problem. Many countries have implemented health programmes to reduce morbidity and prevalence of schistosomiasis, and control programmes to mitigate food-borne fascioliasis. As these programmes are resource demanding, baseline information on disease prevalence and distribution becomes of great importance. Such information can be made available and put into practice through maps depicting spatial distribution of the intermediate snail hosts. A biology driven model for the freshwater snails Bulinus globosus, Biomphalaria pfeifferi and Lymnaea natalensis was used to make predictions of snail habitat suitability by including potential underlying environmental and climatic drivers. The snail observation data originated from a nationwide survey in Zimbabwe and the prediction model was parameterised with a high resolution Regional Climate Model. Georeferenced prevalence data on urinary and intestinal schistosomiasis and fascioliasis was used to calibrate the snail habitat suitability predictions to produce binary maps of snail presence and absence. Predicted snail habitat suitability across Zimbabwe, as well as the spatial distribution of snails, is reported for three time slices representative for present (1980-1999) and future climate (2046-2065 and 2080-2099). It is shown from the current study that snail habitat suitability is highly variable in Zimbabwe, with distinct high- and low

  18. CCR7 pathway induces epithelial-mesenchymal transition through up-regulation of Snail signaling in gastric cancer.

    Science.gov (United States)

    Zhang, Jianping; Zhou, Yunzhe; Yang, Yonggang

    2015-02-01

    The chemokine receptor 7 (CCR7) and Snail signaling have been linked to various types of cancers. The associations between these signalings and the epithelial-mesenchymal transition (EMT) are not clear in gastric cancer. Here, the expression of CCR7 and Snail was detected in gastric cancer by immunohistochemistry and Western blot. Meanwhile, gastric cancer cells were subjected to CCL19, si-control, and si-Snail treatment. Cell cycle, migration, and invasion were also analyzed. The expression patterns of CCR7 and Snail were similar in either gastric cancer tissues or cells. The increased expression of CCR7 was closely associated with the increased Snail expression, which both were closely correlated with metastasis, stage and differentiation, and poor prognosis. The increased p-ERK, p-AKT, Snail, and MMP9 expression and the decreased E-cadherin were confirmed in MGC803 cells in a dose-dependent manner in response to CCL19 treatment. However, the blockade of Snail abrogated the up-regulation of MMP9 and down-regulation of E-cadherin. CCR7-induced ERK and PI3K pathway regulated Snail signaling. Besides si-Snail treatment led to MGC803 cell cycle arrest and affected the migration and invasion. In conclusion, our study suggested that CCR7 promotes Snail expression to induce the EMT, resulting in cell cycle progression, migration, and invasion in gastric cancer. CCR7-Snail pathway provided more potential regimens for cancer therapy.

  19. THE USE OF Pomacea canaliculata SNAILS IN FEED TO IMPROVE QUALITY OF ALABIO DUCK (Anas plathyrinchos Borneo MEAT

    Directory of Open Access Journals (Sweden)

    A. Subhan

    2016-03-01

    Full Text Available This research was aimed to improve the physical and chemical quality of Alabio ducks which was fed with Pomacea canaliculata snails. Those ducks were raised intensively. There were nine treatments  included R0 (control feed, R1 (control feed + 2.5% Pomacea canaliculata snails from swampy area, R2 (control feed + 5% Pomacea canaliculata snails from swampy area, R3 (control feed + 7.5% Pomacea canaliculata snails from swampy area R4 (control feed + 10% Pomacea canaliculata snails from swampy area R5 (control feed + 2.5% Pomacea canaliculata snails from tidal swampy area, R6 (control feed + 5% Pomacea canaliculata snails from tidal swampy area, R7 (control feed + 7.5% Pomacea canaliculata snails from tidal swampy area, and R8 (control feed + 10% Pomacea canaliculata snails from tidal swampy area. The variables observed included meat chemical and physical quality. A Completely Randomized Design was used in this study. Analysis of variance and Duncan’s multiple range test were used to analyze data. The research results revealed that using Pomacea canaliculata snails in duck feed had a significant effect (P<0.05 towards the physical characteristics (water holding capacity, cooking loss, and tenderness, and chemical characteristics of Alabio duck meat (water, protein, collagen, fat, and cholesterol content. However, there was no significant effect towards meat pH. It can be concluded that using 5% Pomacea canaliculata snails in a mixture of Alabio duck feed decreased cooking loss and meat cholesterol content.

  20. Healthy,Happy trees

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Healthy trees are important to us all. Trees provide shade, beauty, and homes for wildlife. Trees give us products like paper and wood. Trees can give us all this only if they are healthy.They must be well cared for to remain healthy.

  1. PKD1 phosphorylation-dependent degradation of SNAIL by SCF-FBXO11 regulates epithelial-mesenchymal transition and metastasis

    Science.gov (United States)

    Zheng, Hanqiu; Shen, Minhong; Cha, Yin-Lian; Li, Wenyang; Wei, Yong; Blanco, Mario Andres; Ren, Guangwen; Zhou, Tianhua; Storz, Peter; Wang, Hui-Yun; Kang, Yibin

    2014-01-01

    SUMMARY Metastatic dissemination is often initiated by the reactivation of an embryonic development program referred to as epithelial-mesenchymal transition (EMT). The transcription factor SNAIL promotes EMT and elicits associated pathological characteristics, such as invasion, metastasis and stemness. To better understand the post-translational regulation of SNAIL, we performed a luciferase-based genome-wide E3 ligase siRNA library screen and identified SCF-FBXO11 as an important E3 which targets SNAIL for ubiquitylation and degradation. Furthermore, we discovered that SNAIL degradation by FBXO11 is dependent on Serine-11 phosphorylation of SNAIL by protein kinase D1 (PKD1). FBXO11 blocks SNAIL-induced EMT, tumor initiation and metastasis in multiple breast cancer models. These findings establish the PKD1-FBXO11-SNAIL axis as a mechanism of post-translational regulation of EMT and cancer metastasis. PMID:25203322

  2. Patterns in hydraulic architecture from roots to branches in six tropical tree species from cacao agroforestry and their relation to wood density and stem growth

    Directory of Open Access Journals (Sweden)

    Martyna Malgorzata Kotowska

    2015-03-01

    Full Text Available For decades it has been assumed that the largest vessels are generally found in roots and that vessel size and corresponding sapwood area-specific hydraulic conductivity are acropetally decreasing towards the distal twigs. However, recent studies from the perhumid tropics revealed a hump-shaped vessel size distribution. Worldwide tropical perhumid forests are extensively replaced by agroforestry systems often using introduced species of various biogeographical and climatic origins. Nonetheless, it is unknown so far what kind of hydraulic architectural patterns are developed in those agroforestry tree species and which impact this exerts regarding important tree functional traits, such as stem growth, hydraulic efficiency and wood density. We investigated wood anatomical and hydraulic properties of the root, stem and branch wood in Theobroma cacao and five common shade tree species in agroforestry systems on Sulawesi (Indonesia; three of these were strictly perhumid tree species, and the other three tree species are tolerating seasonal drought. The overall goal of our study was to relate these properties to stem growth and other tree functional traits such as foliar nitrogen content and sapwood to leaf area ratio. Our results confirmed a hump-shaped vessel size distribution in nearly all species. Drought-adapted species showed divergent patterns of hydraulic conductivity, vessel density and relative vessel lumen area between root, stem and branch wood compared to wet forest species. Confirming findings from natural old-growth forests in the same region, wood density showed no relationship to specific conductivity. Overall, aboveground growth performance was better predicted by specific hydraulic conductivity than by foliar traits and wood density. Our study results suggest that future research on conceptual trade-offs of tree hydraulic architecture should consider biogeographical patterns underlining the importance of anatomical adaptation

  3. Patterns in hydraulic architecture from roots to branches in six tropical tree species from cacao agroforestry and their relation to wood density and stem growth.

    Science.gov (United States)

    Kotowska, Martyna M; Hertel, Dietrich; Rajab, Yasmin Abou; Barus, Henry; Schuldt, Bernhard

    2015-01-01

    For decades it has been assumed that the largest vessels are generally found in roots and that vessel size and corresponding sapwood area-specific hydraulic conductivity are acropetally decreasing toward the distal twigs. However, recent studies from the perhumid tropics revealed a hump-shaped vessel size distribution. Worldwide tropical perhumid forests are extensively replaced by agroforestry systems often using introduced species of various biogeographical and climatic origins. Nonetheless, it is unknown so far what kind of hydraulic architectural patterns are developed in those agroforestry tree species and which impact this exerts regarding important tree functional traits, such as stem growth, hydraulic efficiency and wood density (WD). We investigated wood anatomical and hydraulic properties of the root, stem and branch wood in Theobroma cacao and five common shade tree species in agroforestry systems on Sulawesi (Indonesia); three of these were strictly perhumid tree species, and the other three tree species are tolerating seasonal drought. The overall goal of our study was to relate these properties to stem growth and other tree functional traits such as foliar nitrogen content and sapwood to leaf area ratio. Our results confirmed a hump-shaped vessel size distribution in nearly all species. Drought-adapted species showed divergent patterns of hydraulic conductivity, vessel density, and relative vessel lumen area between root, stem and branch wood compared to wet forest species. Confirming findings from natural old-growth forests in the same region, WD showed no relationship to specific conductivity. Overall, aboveground growth performance was better predicted by specific hydraulic conductivity than by foliar traits and WD. Our study results suggest that future research on conceptual trade-offs of tree hydraulic architecture should consider biogeographical patterns underlining the importance of anatomical adaptation mechanisms to environment.

  4. Reproduction and demography of the Florida Everglade (Snail) Kite

    Science.gov (United States)

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

    1989-01-01

    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.

  5. Characterizations of cholinesterases in golden apple snail (Pomacea canaliculata).

    Science.gov (United States)

    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

    2014-07-01

    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.

  6. Diaphanous gene mutation affects spiral cleavage and chirality in snails

    Science.gov (United States)

    Kuroda, Reiko; Fujikura, Kohei; Abe, Masanori; Hosoiri, Yuji; Asakawa, Shuichi; Shimizu, Miho; Umeda, Shin; Ichikawa, Futaba; Takahashi, Hiromi

    2016-01-01

    L-R (left and right) symmetry breaking during embryogenesis and the establishment of asymmetric body plan are key issues in developmental biology, but the onset including the handedness-determining gene locus still remains unknown. Using pure dextral (DD) and sinistral (dd) strains of the pond snail Lymnaea stagnalis as well as its F2 through to F10 backcrossed lines, the single handedness-determining-gene locus was mapped by genetic linkage analysis, BAC cloning and chromosome walking. We have identified the actin-related diaphanous gene Lsdia1 as the strongest candidate. Although the cDNA and derived amino acid sequences of the tandemly duplicated Lsdia1 and Lsdia2 genes are very similar, we could discriminate the two genes/proteins in our molecular biology experiments. The Lsdia1 gene of the sinistral strain carries a frameshift mutation that abrogates full-length LsDia1 protein expression. In the dextral strain, it is already translated prior to oviposition. Expression of Lsdia1 (only in the dextral strain) and Lsdia2 (in both chirality) decreases after the 1-cell stage, with no asymmetric localization throughout. The evolutionary relationships among body handedness, SD/SI (spiral deformation/spindle inclination) at the third cleavage, and expression of diaphanous proteins are discussed in comparison with three other pond snails (L. peregra, Physa acuta and Indoplanorbis exustus). PMID:27708420

  7. MYCOTOXINS CONTAMINATION IN EDIBLE LAND SNAIL AT GRAZING PADDOCK ENVIRONMENT

    Directory of Open Access Journals (Sweden)

    Ime Ebenso

    2013-02-01

    Full Text Available Mycotoxins contamination of animal products is under reported. Juvenile edible land snails (Archachatina marginata were exposed as sentinels in bottomless metal drums for 1 week at abandoned, new and reference sites respectively at grazing paddock environment, to assess the presence of foodborne microbiological mycotoxins contamination during the dry season. Mycological analysis of A. marginata samples revealed high (p<0.05 contamination at all paddocks ranged from 1.2-1.3 x 105 cfu-g. Results revealed values that were found to be unacceptable by FAO/WHO standards. The presence of Aspergillus niger, A. fumigatus and Penicillum expansum were noted as potential toxicogenic mycoflora. Snails were tolerant to all levels of contamination with no clinical signs of infection or mortality. This finding could serve as basis for assessing pre-slaughter microbial contamination of livestock farm/field environment in order to establish data with comparative epidemiological value, which could highlight early warning signals of food safety risk and cross-contamination of mycotoxins in the food chain.

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

    Institute of Scientific and Technical Information of China (English)

    Thapana Chontananarth; Chalobol Wongsawad

    2013-01-01

    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.

  9. Taken to the limit--Is desiccation stress causing precocious encystment of trematode parasites in snails?

    Science.gov (United States)

    O'Dwyer, Katie; Poulin, Robert

    2015-12-01

    When hosts experience environmental stress, the quantity and quality of resources they provide for parasites may be diminished, and host longevity may be decreased. Under stress, parasites may adopt alternative strategies to avoid fitness reductions. Trematode parasites typically have complex life cycles, involving asexual reproduction in a gastropod first intermediate host. A rare phenomenon, briefly mentioned in the literature, and termed 'precocious encystment' involves the next stage in the parasites' life cycle (metacercarial cyst) forming within the preceding stage (redia), while still inside the snail. In the trematode Parorchis sp. NZ using rocky shore snails exposed to long periods outside water, we hypothesised that this might be an adaptive strategy against desiccation, preventing parasite emergence from the snail. To test this, we first investigated the effect of prolonged desiccation on the survival of two species of high intertidal snails. Secondly, we measured the reproductive output (cercarial production) of the parasite under wet and dry conditions. Finally, we quantified the influence of desiccation stress on the occurrence of precocious encystment. Snail mortality was higher under dry conditions, indicating stress, and it was somewhat exacerbated for infected snails. Parasite reproductive output differed between wet and dry conditions, with parasites of snails kept in dry conditions producing more cercariae when placed in water. Little variation was observed in the occurrence of precocious encystment, although some subtle patterns emerged. Given the stresses associated with living in high intertidal environments, we discuss precocious encystment as a possible stress response in this trematode parasite.

  10. Comparative toxicity of Paraquat herbicide and some plant extracts in Lymnaea natalensis snails.

    Science.gov (United States)

    Bakry, Fayez A; Eleiwa, Mona E; Taha, Samir A; Ismil, Somya M

    2016-01-01

    Paraquat has been shown to be a highly toxic compound for humans and animals, and many cases of acute poisoning and death have been reported over the past few decades. The present study was undertaken to evaluate comprehensively herbicides (Paraquat) and some plant extracts to biochemical aspects of Lymnaea natalensis snails. It was found that the exposure of L. natalensis to Paraquat and plant extracts led to a significant reduction in the infectivity of Fasciola gigantica miracidia to the snail. The glucose level in hemolymph of exposed snails was elevated, while the glycogen showed a decrease in soft tissues when compared with the control group. In addition, the activity level of some enzymes representing glycolytic enzymes as hexokinase (HK), pyruvate kinase (PK), phosphofructokinase (PFK), lactate dehydrogenase (LDH), and glucose phosphate isomerase (GPI) in snail's tissues were reduced in response to the treatment. It was concluded that the pollution of the aquatic environment by herbicide would adversely affect the metabolism of the L. natalensis snails. Snails treated with Agave attenuate, Ammi visnaga, and Canna iridiflora plant had less toxic effect compared to snails treated with Paraquat.

  11. Temperature dependence of Opisthorchis viverrini infection in first intermediate host snail, Bithynia siamensis goniomphalos.

    Science.gov (United States)

    Prasopdee, Sattrachai; Kulsantiwong, Jutharat; Piratae, Supawadee; Khampoosa, Panita; Thammasiri, Chalida; Suwannatrai, Apiporn; Laha, Thewarach; Grams, Rudi; Loukas, Alex; Tesana, Smarn

    2015-01-01

    Determining of the success of a parasite's infectiveness in its snail host clearly depends on environmental conditions. Temperature, one of the most influential factors impinging on metabolism of cold-blooded animals, is believed to be an important factor in parasitic infection in snails. In order to elucidate the influence of temperature, sex and size of snails on infectivity of Opisthorchis viverrini to its first intermediate host, Bithynia siamensis goniomphalos, 960 snails were divided into 2 groups by sex. Each group was subdivided by their size into small and medium sub-groups. Each snail was fed with embryonated uterine-eggs of O. viverrini at different temperatures (16-37°C, 3°C intervals). Dissections were carried out 1, 7, 14, 28 and 56 days thereafter and detection of O. viverrini infection was undertaken by PCR using specific primers. Infection was strongly temperature-dependent, as temperature increases of 1°C resulted in increased odds of infection 5.4% (P<0.01). A temperature of 34°C gave the highest rate of infection of 44.14%. We also found that the odds of infection in small sized snails was 39.8% higher relative to medium sized snails (P<0.05). Relative to day 1, the decrease in the odds of infection was detected when the day post infection was longer (P<0.01). Proportion of infection in female was not different to male significantly.

  12. Effects of Fasciola gigantica experimental infection on some inorganic elements in the snail host Lymnaea natalensis.

    Science.gov (United States)

    Mostafa, Osama Mohammad Sayed

    2008-04-01

    Flame atomic absorption spectrometry was performed to determine the alteration in the concentrations of metallic ion Pb, Zn, K, Na, Fe, Cu and Co in the soft parts of the Lymnaea natalensis snails shedding Fasciola gigantica cercariae and to determine the alteration in the concentration of Ca in the soft parts and shells of the same snails. The Co was found to be present at concentration level below the detection limits of the analytical method used. Regarding detected elements, three elements Zn, K and Cu were found to be present at significantly higher concentrations in cercariae-shedding snails compared with uninfected snails. Two elements, Pb and Na, showed significant decrease in cercariae-shedding snails compared to uninfected ones. The concentration of Fe showed non-significant increase. The results showed significant lowering in the calcium content of the shells and soft parts of cercariae-shedding snails relative to the calcium content in the uninfected ones. The obtained results and the hypothesis of hypercalcification in shells of infected snails were discussed.

  13. Nrf2 inhibits epithelial-mesenchymal transition by suppressing snail expression during pulmonary fibrosis.

    Science.gov (United States)

    Zhou, Wencheng; Mo, Xiaoting; Cui, Wenhui; Zhang, Zhihui; Li, Delin; Li, Liucheng; Xu, Liang; Yao, Hongwei; Gao, Jian

    2016-12-16

    Epithelial-mesenchymal transition (EMT) is a phenotype conversion that plays a critical role in the development of pulmonary fibrosis (PF). It is known that snail could regulate the progression of EMT. Nuclear factor erythroid 2 related factor 2 (Nrf2), a key regulator of antioxidant defense system, protects cells against oxidative stress. However, it is not known whether Nrf2 regulates snail thereby modulating the development of PF. Here, bleomycin (BLM) was intratracheally injected into both Nrf2-knockout (Nrf2(-/-)) and wild-type mice to compare the development of PF. Rat type II alveolar epithelial cells (RLE-6TN) were treated with a specific Nrf2 activator sulforaphane, or transfected with Nrf2 and snail siRNAs to determine their effects on transforming growth factor β1 (TGF-β1)-induced EMT. We found that BLM-induced EMT and lung fibrosis were more severe in Nrf2(-/-) mice compared to wild-type mice. In vitro, sulforaphane treatment attenuated TGF-β1-induced EMT, accompanied by the down-regulation of snail. Inversely, silencing Nrf2 by siRNA enhanced TGF-β1-induced EMT along with increased expression of snail. Interestingly, when snail was silenced by siRNA, sulforaphane treatment was unable to reduce the progression of EMT in RLE-6TN cells. These findings suggest that Nrf2 attenuates EMT and fibrosis process by regulating the expression of snail in PF.

  14. Utilisation of Giant African snail (Achatina fulica meal as protein source for laying hens

    Directory of Open Access Journals (Sweden)

    Siaka Seriba Diarra

    2015-05-01

    Full Text Available A 12-week experiment was carried out to investigate the effects of substituting Giant African snail meal for fish meal in laying hens diet. Four diets were formulated to contain snail meal as replacement for fish meal at 0 (control, 33, 67 and 100 %. A total of 120 Shaver Brown pullets aged 18 weeks were allocated to the dietary treatments in a randomised design. Each treatment consisted of three replicates and ten birds per replicate. Feed intake increased only for the 33% treatment as compared to the 67% replacement diet but did not differ from the other treatments. There were no significant treatment effects on egg performance parameters observed (egg production, egg weight, total egg mass, feed conversion ratio and percent shell. The overall feed cost of egg production reduced on the snail mealbased diets. The organoleptic evaluation of boiled eggs revealed no difference between the treatments. Based on these results it was concluded that total replacement of fish meal with cooked snail meat meal does not compromise laying performance or egg quality. The substitution is beneficial in terms of production cost reduction and the reduction of snails will have a beneficial impact especially where these snails are a serious agricultural pest. The manual collection and processing of snails can also become a source of rural income.

  15. Bacterial induction of Snail1 contributes to blood-brain barrier disruption

    Science.gov (United States)

    Kim, Brandon J.; Hancock, Bryan M.; Bermudez, Andres; Cid, Natasha Del; Reyes, Efren; van Sorge, Nina M.; Lauth, Xavier; Smurthwaite, Cameron A.; Hilton, Brett J.; Stotland, Aleksandr; Banerjee, Anirban; Buchanan, John; Wolkowicz, Roland; Traver, David; Doran, Kelly S.

    2015-01-01

    Bacterial meningitis is a serious infection of the CNS that results when blood-borne bacteria are able to cross the blood-brain barrier (BBB). Group B Streptococcus (GBS) is the leading cause of neonatal meningitis; however, the molecular mechanisms that regulate bacterial BBB disruption and penetration are not well understood. Here, we found that infection of human brain microvascular endothelial cells (hBMECs) with GBS and other meningeal pathogens results in the induction of host transcriptional repressor Snail1, which impedes expression of tight junction genes. Moreover, GBS infection also induced Snail1 expression in murine and zebrafish models. Tight junction components ZO-1, claudin 5, and occludin were decreased at both the transcript and protein levels in hBMECs following GBS infection, and this repression was dependent on Snail1 induction. Bacteria-independent Snail1 expression was sufficient to facilitate tight junction disruption, promoting BBB permeability to allow bacterial passage. GBS induction of Snail1 expression was dependent on the ERK1/2/MAPK signaling cascade and bacterial cell wall components. Finally, overexpression of a dominant-negative Snail1 homolog in zebrafish elevated transcription of tight junction protein–encoding genes and increased zebrafish survival in response to GBS challenge. Taken together, our data support a Snail1-dependent mechanism of BBB disruption and penetration by meningeal pathogens. PMID:25961453

  16. Classification and regression trees

    CERN Document Server

    Breiman, Leo; Olshen, Richard A; Stone, Charles J

    1984-01-01

    The methodology used to construct tree structured rules is the focus of this monograph. Unlike many other statistical procedures, which moved from pencil and paper to calculators, this text's use of trees was unthinkable before computers. Both the practical and theoretical sides have been developed in the authors' study of tree methods. Classification and Regression Trees reflects these two sides, covering the use of trees as a data analysis method, and in a more mathematical framework, proving some of their fundamental properties.

  17. Reconstruction and Implementation of 3D Virtual Road Speed Control Humps for Vehicle%车辆三维虚拟道路减速带重构与实现

    Institute of Scientific and Technical Information of China (English)

    蒋荣超; 陈焕明; 刘大维; 王松

    2012-01-01

    为实现三维虚拟道路减速带与三维随机路面的同构,对道路减速带断面轮廓和路面不平度模拟方法进行研究.基于三角网格法的基本理论,利用Delaunay算法规则重构 了3种道路减速带,并采用谐波叠加法建立了三维随机路面数学模型.在三维路面的基础上,确定了道路减速带的安装位置.根据减速带的宽度,将三维随机路面中相应的路面节点和单元数据去除,并把减速带的节点和单元数据添加到相应的位置,实现了三维虚拟道路减速带与随机路面的同构.该结果为采用相关应用软件研究车辆-道路减速带耦合作用提供了参考依据.%In order to implement the isomorphism of 3D virtual road speed control hump and 3D random road surface, the cross-section profile of road speed control hump and the simulation method of road roughness were researched and analyzed. Three types of speed control humps were reconstructed using Delaunay based on the basic theory of triangular mesh method. Simultaneously, a mathematical model of 3D random road surface was established based on the basic principles of harmonic superposition. On the basis of 3D road surface, the installation site of road speed control hump was determined. According to the width of speed control hump, the nodes and elements were removed from the appropriate location and the speed control hump's nodes and elements were added to the appropriate location. Then the isomorphism of 3D virtual road speed control hump and 3D random road surface was implemented. This study provided a reference for the research of vehicle-road coupling effect using relevant application software.

  18. Observations of MCG-5-23-16 with Suzaku, XMM-Newton and NuSTAR: Disk Tomography and Compton Hump Reverberation

    Science.gov (United States)

    Zoghbi, A.; Cackett, E. M.; Reynolds, C.; Kara, E.; Harrison, F. A.; Fabian, A. C.; Lohfink, A.; Matt, G.; Stern, D.; Zhang, W. W.

    2014-01-01

    MCG-5-23-16 is one of the first active galactic nuclei (AGNs) where relativistic reverberation in the iron K line originating in the vicinity of the supermassive black hole was found, based on a short XMM-Newton observation. In this work, we present the results from long X-ray observations using Suzaku, XMM-Newton, and NuSTAR designed to map the emission region using X-ray reverberation. A relativistic iron line is detected in the lag spectra on three different timescales, allowing the emission from different regions around the black hole to be separated. Using NuSTAR coverage of energies above 10 keV reveals a lag between these energies and the primary continuum, which is detected for the first time in an AGN. This lag is a result of the Compton reflection hump responding to changes in the primary source in a manner similar to the response of the relativistic iron K line.

  19. Perceptions and problems of disease in the one-humped camel in southern Africa in the late 19th and early 20th centuries : historical review

    Directory of Open Access Journals (Sweden)

    R.T. Wilson

    2008-05-01

    Full Text Available The one-humped camel (Camelus dromedarius was first introduced to German South West Africa (Namibia for military purposes in 1889. Introductions to the Cape of Good Hope (South Africa in 1897 and Rhodesia (Zimbabwe in 1903 were initially with a view to replacing oxen that died of rinderpest. Disease risks attendant on these introductions were recognised and to some extent guarded against. There were, however, relatively few problems. One camel was diagnosed as having foot-and-mouth disease. Mange in camels from India caused some concern as did trypanosomosis from Sudan. Trypanosomosis was introduced into both the Cape of Good Hope and Transvaal. Antibodies to some common livestock disease were found in later years.

  20. Power Configuration for Hump Switch Machine Locking Valve%驼峰ZK4转辙机锁闭阀电源设置

    Institute of Scientific and Technical Information of China (English)

    银雪华

    2012-01-01

    在旧驼峰站场上安装新型ZK4转辙机,要增设一组直流24V电源供锁闭阀使用,根据站场特点,采用了分散供电方式,既能保证道岔的正常运用,又大大地节约了成本。%When installing a new ZK4 switch machine at an old hump yard,a group of 24V DC power supply locking valve was added.According to the features of the yard,separate power supply mode was adopted to ensure the normal operation of the turnout,greatly saving the cost.

  1. Occurrence of a Snail Borne Disease, Cercarial Dermatitis (Swimmer Itch in Doon Valley (Uttarakhand, India.

    Directory of Open Access Journals (Sweden)

    Rakesh Kumar Jauhari

    2014-02-01

    Full Text Available 'Cercarial dermatitis' also known as swimmers itch (Skin allergies is caused by a trematode parasite, Schistosoma which has two hosts - an invertebrate (snail and a vertebrate (livestock, human being. Although the availability of both vector snails and pathogens at the selected site the Doon Valley in northern India has already been confirmed but there was a hazy picture of the disease, whether it is due to entrance of cercariae or due to wild variety of grass (Parthenium hysterophorus. The present study is an attempt to provide a way forward towards the vector snails and snail borne diseases in the study area.Snail sampling and identification was done by applying standard methods / using Keys & Catalogues. Associated parasites and cercariometry in snails has been worked out by cercarial shedding. Human involvement at zo-onotic level has been performed in collaboration with Health centers and socio- economic aspect of inhabitants of study area.The snail diversity encountered 19 species including the vector species such as Indoplanorbis exustus, Gyraulus convexiusculus, Melanoides tuberculata and Lymnaea acuminata. The cercarial diversity comprised Furcocercous, Monostome, Amphistome and liver fluke / Xiphidiocercaria. During the study (2009-2010, 0.173% was found with cercarial dermatitis among human population in the selected area. The symptoms of disease recorded were red spots and swellings on effected parts of skin. Frequent visits of livestock to the water body and presence of vector snails provides a clue in completing the life cycle of the parasite of the family Schistosomatidae.Cercarial dermatitis has been considered a potential risk at those places where warm blooded and snail's hosts share a link with aquatic bodies with particular emphasis to temperature and time of year.

  2. Novel snail1 target proteins in human colon cancer identified by proteomic analysis.

    Directory of Open Access Journals (Sweden)

    María Jesús Larriba

    Full Text Available BACKGROUND: The transcription factor Snail1 induces epithelial-to-mesenchymal transition (EMT, a process responsible for the acquisition of invasiveness during tumorigenesis. Several transcriptomic studies have reported Snail1-regulated genes in different cell types, many of them involved in cell adhesion. However, only a few studies have used proteomics as a tool for the characterization of proteins mediating EMT. METHODOLOGY/PRINCIPAL FINDINGS: We identified by proteomic analysis using 2D-DIGE electrophoresis combined with MALDI-TOF-TOF and ESI-linear ion trap mass spectrometry a number of proteins with variable functions whose expression is modulated by Snail1 in SW480-ADH human colon cancer cells. Validation was performed by Western blot and immunofluorescence analyses. Snail1 repressed several members of the 14-3-3 family of phosphoserine/phosphothreonine binding proteins and also the expression of the Proliferation-associated protein 2G4 (PA2G4 that was mainly localized at the nuclear Cajal bodies. In contrast, the expression of two proteins involved in RNA processing, the Cleavage and polyadenylation specificity factor subunit 6 (CPSF6 and the Splicing factor proline/glutamine-rich (SFPQ, was higher in Snail1-expressing cells than in controls. The regulation of 14-3-3epsilon, 14-3-3tau, 14-3-3zeta and PA2G4 by Snail1 was reproduced in HT29 colon cancer cells. In addition, we found an inverse correlation between 14-3-3sigma and Snail1 expression in human colorectal tumors. CONCLUSIONS/SIGNIFICANCE: We have identified a set of novel Snail1 target proteins in colon cancer that expand the cellular processes affected by Snail1 and thus its relevance for cell function and phenotype.

  3. Discussion on Hump Rolling Vehicle Speed Control Problem%关于驼峰溜放车辆调整问题的探讨

    Institute of Scientific and Technical Information of China (English)

    何宁; 李兴汉

    2011-01-01

    我国铁路驼峰编组场对溜放车辆的调速制式,从采用铁鞋、手闸和减速器等点式调速,到减速顶连续式调速,随着调速设备和技术的不断创新,使我国驼峰编组站的能力和效率显著提高,驼峰调车作业的安全情况大为改观,为编组站的现代化发挥了重要作用。通过对溜放车辆调速问题的分析,看到某些调速设备和调速制式的一些不足,通过不断地改进和创新,为适应新形势下铁路实现高速和重载做好准备。%China's railway hump of marshalling yard control the rolling speed of vehicles, from the iron shoes, hand brake and skate and so on point type speed control, to continuous type speed control such as retarders, with incessant technology innovation of speed control, the capacity and efficiency of our hump marshalling yard have significantly improved and the security situation greatly improved, for realize modernization of marshalling yard play an important role. Through analysis the rolling speed problem of vehicles, we also know some equipments and systems of the speed control existed insufficiency, so we must continuous improvement and innovation, to adapt the new situation and make greater contribution for high-speed and heavy haul rail.

  4. The Research on Hump Phenomenon after Improving Electrical Safe Operating Area of SOI-LDMOS%SOI-LDMOS器件改善电安全工作区后驼峰现象的研究

    Institute of Scientific and Technical Information of China (English)

    霍昌隆; 刘斯扬; 钱钦松; 孙伟锋

    2012-01-01

    研究了高压SOI-LDMOS器件在引入P-sink结构改善电安全工作区(E-SOA)后Ⅰ-Ⅴ特性曲线呈现的驼峰现象(hump).首先将驼峰现象出现后器件的源端总电流分成电子电流与空穴电流单独分析,确定高栅压下电子电流阶梯上升是驼峰现象产生的表面原因,进而通过仿真分析出Kirk效应导致的空穴电流在表面漂移区中电导调制是驼峰现象产生的根本原因.最后,根据对驼峰现象的分析,设计出新器件结构成功消除了驼峰现象,为今后不同类型LDMOS器件改善Ⅰ-Ⅴ曲线驼峰现象提供了理论指导.%The hump phenomenon of I-V characteristic after introducing P-sink structure to improve electrical safe operating area (E-SOA) on the high voltage SOI-LDMOS has been investigated in this paper. Firstly, the electron current and hole current are extracted and analyzed from total current at source side separately to make sure that the electron current step increase is the appearance reason for hump phenomenon, and then hole conductivity modulation in surface N-drift region induced by Kirk effect at drain side is confirmed as the deep reason. Moreover, according to the analysis in this paper, a new SOI-LDMOS structure has been designed to eliminating hump phenomenon, which gives the theoretic instructions for eliminating hump phenomenon of high voltage LDMOS more accurately.

  5. Large-scale facilitation of a sessile community by an invasive habitat-forming snail

    DEFF Research Database (Denmark)

    Thyrring, Jakob; Thomsen, Mads Solgaard; Wernberg, Thomas

    2013-01-01

    Abstract We provide an example of extensive facilitation of a sessile community throughout an invaded estuary by the invasive snail Batillaria australis. We show that B. australis greatly increases a limiting resource (attachment space) to a community of sessile organisms and estimate that a large...... part of the invaded estuary now contain ca. 50 times more sessile individuals associated with the invader than all native snails combined. We argue that native snails are unlikely to have been dramatically reduced by the invader, and we therefore suggest that the shell-attached sessile community...

  6. Does social facilitation affect responses to natural and anthropogenic stressors in the freshwater snail Planorbella trivolvis?

    Science.gov (United States)

    Plautz, Stephanie C; Salice, Christopher J

    2011-12-01

    Social facilitation is the initiation or increase of a trait, such as stressor tolerance, when in the presence of conspecifics, members of the same species. It has been shown to alter the outcome of toxicity experiments in colonial organisms. We evaluated whether social facilitation would impact responses to stressors in the noncolonial New Mexico ramshorn snail (Planorbella trivolvis) by exposing snails to stressors either singly or in groups of three. Social facilitation did not impact snail responses to malathion but did affect responses to predator cues and temperature stress. Copyright © 2011 SETAC.

  7. The Use of Golden Snail (Pomacea sp.) as Animal Feed in the Philippines

    OpenAIRE

    Serra, AB

    1997-01-01

    The golden snail is introduced to the Philippines in early 80's for culture as food source. This herbivorous snail, a voracious feeder of live and fresh plant materials become a serious rice pest. Its elimination in the ecosystems is impossible. To use them as animal feed is much better alternative for their control and more environmentally friendly than the use of chemicals. Thus, this mini review paper aimed to collate any existing information on the use of golden snail as animal feed. The ...

  8. AKT primes snail-induced EMT concomitantly with the collective migration of squamous cell carcinoma cells.

    Science.gov (United States)

    Okui, Gaku; Tobiume, Kei; Rizqiawan, Andra; Yamamoto, Kazuhiro; Shigeishi, Hideo; Ono, Shigehiro; Higashikawa, Koichiro; Kamata, Nobuyuki

    2013-09-01

    In this study, we found that wounding of a confluent monolayer of squamous cell carcinoma (SCC) cells induced epithelial-mesenchymal transition (EMT) specifically at the edge of the wound. This process required the combined stimulation of TGFβ, TNFα, and PDGF-D. Such a combined cytokine treatment of confluent monolayers of the cells upregulated the expression levels of Snail and Slug via PI3K. The PI3K downstream effector, AKT, was dispensable for the upregulation of Snail and Slug, but essential for enabling EMT in response to upregulation of Snail and Slug. Copyright © 2013 Wiley Periodicals, Inc.

  9. Multiple infection of amber Succinea putris snails with sporocysts of Leucochloridium spp. (Trematoda).

    Science.gov (United States)

    Ataev, G L; Zhukova, A A; Tokmakova, А S; Prokhorova, Е E

    2016-08-01

    Amber Succinea putris snails were collected in the Leningrad Region (Russia). Some of them were infected with trematodes Leucochloridium paradoxum, Leucochloridium perturbatum and Leucochloridium vogtianum. One snail had triple infection with all these species. Genotyping of sporocysts by ITS1-5.8S-ITS2 nucleotide sequences of ribosomal DNA (rDNA) and phylogenetic analysis were performed. The results confirmed the species identification of sporocysts of Leucochloridium based on the shape and colour of mature broodsacs. Sporocyst broodsacs could leave the host snail on their own, remaining viable in the environment for up to an hour. This ability of sporocysts may prevent the excessive infection of the molluscan host.

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

    Institute of Scientific and Technical Information of China (English)

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

    2005-01-01

    @@ 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 ℃ 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.

  11. Fossil land snails of East Africa and their palaeoecological significance

    Science.gov (United States)

    Pickford, Martin

    1995-04-01

    This study deals with the Neogene and extant land snails of tropical East Africa and their implications for interpreting the paleoenvironments of the numerous localities at which they have been found. Of major significance to the study is the intimate association between the terrestrial molluscs and the rich mammalian faunas, hominoids included, of East Africa. Thus, palaeoecological reconstructions based on land snails are directly applicable to the mammalian faunas. Palaeoecological reconstructions are proposed for most of the Lower and Middle Miocene hominoids, including Proconsul, Rangwapithecus, Limnopithecus, Micropithecus, Nyanzapithecus, Kenyapithecus and others, and for the mid-Pliocene Australopithecus from Laetoli, Tanzania. The departure point for the palaeoecological reconstructions is a comprehensive study of extant terrestrial molluscs of East Africa, the habitat preferences of which are well documented. All the fossil gastropods studied comprise extant genera and even species, so the usual problems regarding the application of actualism to fossil assemblages is avoided. Furthermore, the fossil gastropod assemblages resemble extant ones, confirming their utility for such reconstructions. Among the parameters examined are rainfall, altitude, vegetation cover and type and zoogeography. A further point of interest is that the samples are more than adequate for the purposes of the study, many of the fossil localities having yielded several thousand specimens. Finally, more than 40% of the extant genera of East Africa have now been recognized in the fossil state. The molluscs are thus, by far, the best represented biological group known in the fossil record of Africa and as such hold great potential for understanding the past. This study ends with reconstructions of the palaeoecology of numerous fossiliferous localities in East Africa which have yielded molluscs and mammals. Changes through the geological column are documented and the habitat preferences

  12. Single- or mixed-sex Schistosoma japonicum infections of intermediate host snails in hilly areas of Anhui, China.

    Science.gov (United States)

    Shi, Hui-Ping; Lu, Da-Bing; Shen, Lei; Shi, Tan; Gu, Jian

    2014-02-01

    Schistosomiasis japonicum is one of the most serious communicable diseases, and the transmission of the parasite is dependent of its complex life cycle on which many factors can have an impact. Multiple infections comprising both male and female schistosome within snail intermediate hosts, for example, would facilitate parasite transmission. However, no research on Schistosoma japonicum communities in field-collected Oncomelania hupensis hupensis in relation to schistosome sex has been reported. Therefore, snail survey was performed in a hilly region of Anhui, China, and single- or mixed-sex schistosome infections of snails were detected with final host mouse infection. A total of 8,563 snails were sampled in the field, and 67 were identified with schistosome infections. Of these infected snails, 46 were selected for final host infection. From this, 21 snails were infected with female schistosome, 23 with males and 2 with both males and females. More worms were recovered for snails with mixed-sex infections than with single-sex infection and for snails with male schistosome infection than with female infection (Psnails was significantly higher than would be expected if randomly distributed (Psnails was nearly equal and up to 95.65 % (44/46) of infected snails were single-sex infection. Schistosome infections in snails collected from the hilly area of Anhui Province were not randomly distributed but over-dispersed.

  13. The population density effects on the reproductive biology of the snail Bradybaena similaris (Férussac, 1821) (Mollusca, Gastropoda).

    Science.gov (United States)

    Oliveira, C S de; Vasconcellos, M C; Pinheiro, J

    2008-05-01

    The influence of population density on some aspects of the reproductive biology of the snail Bradybaena similaris was studied. Molluscs were maintained under 0.2 (isolated), 0.3, 0.6, 1.0, 1.3 and 1.7 snail/m(2) densities. The animals maintained under 0.3 and 0.6 snail/m(2) showed the lowest numbers of eggs laid/snail, being the highest value observed to the 1.7 snail/m(2). The hatching of the snails maintained under 0.3 snail/m(2) density, begun at the 21st day after laying, and the maximum time required to the hatching was 36 days was observed to the eggs came from snails maintained under the densities 0.6, 1.0, 1.3 snail/m(2), respectively. The highest percentage hatchability (55.56%) was observed to isolated snails. The galactogen content in the albumen gland did not seem to accompany the alterations occurred in the reproduction of B. similaris in response to the different population densities.

  14. The population density effects on the reproductive biology of the snail Bradybaena similaris (Férussac, 1821 (Mollusca, Gastropoda

    Directory of Open Access Journals (Sweden)

    CS. de Oliveira

    Full Text Available The influence of population density on some aspects of the reproductive biology of the snail Bradybaena similaris was studied. Molluscs were maintained under 0.2 (isolated, 0.3, 0.6, 1.0, 1.3 and 1.7 snail/m² densities. The animals maintained under 0.3 and 0.6 snail/m² showed the lowest numbers of eggs laid/snail, being the highest value observed to the 1.7 snail/m². The hatching of the snails maintained under 0.3 snail/m² density, begun at the 21st day after laying, and the maximum time required to the hatching was 36 days was observed to the eggs came from snails maintained under the densities 0.6, 1.0, 1.3 snail/m², respectively. The highest percentage hatchability (55.56% was observed to isolated snails. The galactogen content in the albumen gland did not seem to accompany the alterations occurred in the reproduction of B. similaris in response to the different population densities.

  15. Fault-Tree Compiler

    Science.gov (United States)

    Butler, Ricky W.; Boerschlein, David P.

    1993-01-01

    Fault-Tree Compiler (FTC) program, is software tool used to calculate probability of top event in fault tree. Gates of five different types allowed in fault tree: AND, OR, EXCLUSIVE OR, INVERT, and M OF N. High-level input language easy to understand and use. In addition, program supports hierarchical fault-tree definition feature, which simplifies tree-description process and reduces execution time. Set of programs created forming basis for reliability-analysis workstation: SURE, ASSIST, PAWS/STEM, and FTC fault-tree tool (LAR-14586). Written in PASCAL, ANSI-compliant C language, and FORTRAN 77. Other versions available upon request.

  16. Impacts of Thermal Treatments on Major and Minor Allergens of Sea Snail, Cerithidea obtusa (Obtuse Horn Shell

    Directory of Open Access Journals (Sweden)

    Rosmilah Misnan

    2016-08-01

    Full Text Available Snail is one of the worst causes of food allergy. Thus, the aim of this study was to identify the major and minor allergens of the local marine snail (Cerithidea obtusa and subsequently to investigate the impacts of heat treatment on the IgE-binding activity of snail allergens. Proteins from raw and heat-treated snails (boiled, roasted and fried were extracted and then resolved by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE. Immunoblotting of all extracts were then performed using sera from patients with snail allergy. The results showed that the raw extract contains numerous protein bands between 12 to>250 kDa. Some thermostable proteins, predominantly the 33 and 42 kDa bands, remained detected in all cooked extracts with decreasing intensities from boiled to roasted to fried extracts, while the majority of thermolabile bands denatured after heating. Boiled snail had more protein bands compared to roasted and fried snails. Immunoblotting of raw extract demostrated 19 IgE-binding bands ranging from 15 to 240 kDa. The thermostable bands of 33 and 42 kDa and a thermolabile of 30 kDa band were identified as the major allergens of this snail. The cooked extracts yielded less allergenic bands. The boiled extract yielded approximately 14 IgE-binding bands with some smeared bands at high molecular weight regions. The roasted extract had lesser IgE-binding bands and the majority appeared as smears, while the IgE-reactivity in the fried extract was less visible and appeared as weak smears. This study indicated that both raw and cooked snails played a crucial role in snail allergenicity, as this species of snail contains both thermostable and thermolabile major allergens. The degree of snail allergenicity was revealed in the order: raw> boiled > roasted> fried. Thus, the results would facilitate in the development of effective diagnosis and management strategies of snail allergy in this country

  17. Categorizing Ideas about Trees: A Tree of Trees

    Science.gov (United States)

    Fisler, Marie; Lecointre, Guillaume

    2013-01-01

    The aim of this study is to explore whether matrices and MP trees used to produce systematic categories of organisms could be useful to produce categories of ideas in history of science. We study the history of the use of trees in systematics to represent the diversity of life from 1766 to 1991. We apply to those ideas a method inspired from coding homologous parts of organisms. We discretize conceptual parts of ideas, writings and drawings about trees contained in 41 main writings; we detect shared parts among authors and code them into a 91-characters matrix and use a tree representation to show who shares what with whom. In other words, we propose a hierarchical representation of the shared ideas about trees among authors: this produces a “tree of trees.” Then, we categorize schools of tree-representations. Classical schools like “cladists” and “pheneticists” are recovered but others are not: “gradists” are separated into two blocks, one of them being called here “grade theoreticians.” We propose new interesting categories like the “buffonian school,” the “metaphoricians,” and those using “strictly genealogical classifications.” We consider that networks are not useful to represent shared ideas at the present step of the study. A cladogram is made for showing who is sharing what with whom, but also heterobathmy and homoplasy of characters. The present cladogram is not modelling processes of transmission of ideas about trees, and here it is mostly used to test for proximity of ideas of the same age and for categorization. PMID:23950877

  18. THE BIOCIDE TRIBUTYLTIN ALTERS TESTOSTERONE ESTERIFICATION IN MUD SNAILS (ILYANASSA OBSOLETA)

    Science.gov (United States)

    The Biocide Tributyltin Alters Testosterone Esterification in Mud Snails (Ilyanassa obsoleta)Meredith P. Gooding and Gerald A. LeBlanc Department of Environmental and Molecular Toxicology, North Carolina State University, Raleigh, NC 27695-7633Tributyltin (TBT...

  19. Effects of Endosulfan on Predator-Prey Interactions Between Catfish and Schistosoma Host Snails.

    Science.gov (United States)

    Monde, Concillia; Syampungani, Stephen; Van den Brink, Paul J

    2016-08-01

    The effect of the pesticide endosulfan on predator-prey interactions between catfish and Schistosoma host snails was assessed in static tank experiments. Hybrid catfish (Clarias gariepinus × C. ngamensis) and Bulinus globosus were subjected to various endosulfan concentrations including an untreated control. The 48- and 96-h LC50 values for catfish were 1.0 and snails were 1137 and 810 µg/L. To assess sublethal effects on the feeding of the catfish on B. globosus, endosulfan concentrations between 0.03 and 1.0 µg/L were used. Predation was significantly greater (p snails using fish may be affected in endosulfan-polluted aquatic systems of Southern Africa because it has been found present at concentrations that are indicated to cause lethal effects on the evaluated hybrid catfish and to inhibit the predation of snails by this hybrid catfish.

  20. Large-scale determinants of intestinal schistosomiasis and intermediate host snail distribution across Africa

    DEFF Research Database (Denmark)

    Stensgaard, Anna-Sofie; Utzinger, Jürg; Vounatsou, Penelope

    2013-01-01

    to climate change. Here, we combine a growing degree day model for Schistosoma mansoni with species distribution models for the intermediate host snail (Biomphalaria spp.) to investigate large-scale environmental determinants of the distribution of the African S. mansoni-Biomphalaria system and potential...... impacts of climatic changes. Snail species distribution models included several combinations of climatic and habitat-related predictors; the latter divided into "natural" and "human-impacted" habitat variables to measure anthropogenic influence. The predictive performance of the combined snail......-parasite model was evaluated against a comprehensive compilation of historical S. mansoni parasitological survey records, and then examined for two climate change scenarios of increasing severity for 2080. Future projections indicate that while the potential S. mansoni transmission area expands, the snail ranges...

  1. Compatibility of Ugandan Schistosoma mansoni isolates with Biomphalaria snail species from Lake Albert and Lake Victoria

    DEFF Research Database (Denmark)

    Adriko, Moses; Standley, Claire J.; Tinkitina, Benjamin

    2013-01-01

    In order to investigate the capacity of being intermediate host for Schistosoma mansoni, the Ugandan F1 generation of Biomphalaria snail species that were laboratory-bred from parent populations originally collected from either Lake Victoria or Lake Albert was challenged with sympatric and non......-sympatric S. mansoni isolates. After a prepatent period of 20 days, a daily 10-hourly snail shedding for cercariae was done to determine the infection rate, cercarial production per hour and survival period of infected snails. The study suggests that when parasite strains from a different geographical origin...... is used for infection, survival of infected snails increase, leading to an increased transmission potential. Although earlier literature had indicated that the Lake Victoria Biomphalaria sudanica is refractory to S. mansoni, we showed that all Ugandan Biomphalaria spp., including B. sudanica from all...

  2. Life history studies and habitat requirements of the apple snail at Lake Woodruff National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This study discusses habitat requirements and life history of the apple snail at Lake Woodruff National Wildlife Refuge. A study was initiated during 1971 to gather...

  3. Susceptibility of Iraqi fresh water snails to infection with Schistosoma haematobium and Schistosoma mansoni Egyptian strains.

    Science.gov (United States)

    Wajdi, N A; Hussain, W I; El-Hawary, M F

    1979-01-01

    A great number of Egyptian workers and farmers are seeking settlement in Iraq and some of them proved to have either Schistosoma Haematobium (S.h.) or Schistosoma mansoni (S.m) or even mixed infection. Besides, there is the possibility that some of the Iraqi fresh water snails may prove to be susceptible to infection by one or both of the Schistosoma Egyptian strains. The present study deals with investigations on the susceptibility of Iraqi B. truncatus, Gyranaulus ehrenbergi, Physa c.f. fontinalis, Lymnea lagetis, Melanoides tuberculata and Melanopsis nodes by these parasites. Egyptian S. haematobium but not Egyptian S. mansoni infect Iraqi B. truncatus and both proved to be unable to infect any of the other snails included in the study. Yet, the number of cercariae shedded by B. truncatus snails infected with the Egyptian S. haematobium strain, was much less that the number of cercariae shedded by these snails when infected with the Iraqi S. Haematobium strain.

  4. Specificity of Mechanisms of Memory Reconsolidation in Snails Trained for Rejection of Two Types of Food.

    Science.gov (United States)

    Nikitin, V P; Kozyrev, S A; Solntseva, S V

    2017-01-01

    Specificity of behavioral and neuronal mechanisms of impairment of long-term memory reconsolidation was studied in edible snails trained for associative skill of rejection of two types of food: raw carrots (conditioned stimulus 1) and apple (conditioned stimulus 2). In 2 days after training, the snails received protein synthesis inhibitor cycloheximide and a reminder (conditioned stimulus 1 or 2). In 3 and 14 days after cycloheximide/reminder, we observed the absence of aversive responses to the conditioned stimulus used as the reminder and preserved responses to the conditioned stimulus not used as the reminder. Moreover, we observed specific suppression of synaptic responses of command neurons of snail defensive behavior induced by the conditioned stimulus used as the reminder after cycloheximide injection and preserved synaptic responses of neurons to the other conditioned stimulus. It was hypothesized that protein synthesis-dependent synapse-specific plasticity of command neurons can be a mechanism of selective preservation of conditioned food aversion memory in snails.

  5. Palatability and chemical defense of Phragmites australis to the marsh periwinkle snail Littoraria irrorata.

    Science.gov (United States)

    Hendricks, Lindsey G; Mossop, Hannah E; Kicklighter, Cynthia E

    2011-08-01

    Coastal marsh habitats are impacted by many disturbances, including habitat destruction, pollution, and the introduction of invasive species. The common reed, Phragmites australis, has been particularly invasive in the mesohaline regions of the Chesapeake Bay, but few studies have investigated its role in trophic interactions with North American marsh consumers. The marsh periwinkle snail Littoraria irrorata is a common grazer in marshes and grazes on the native grass Spartina alterniflora. Whether this snail grazes on Phragmites has not been addressed. We found Spartina leaves to be tougher than those of Phragmites, but despite this, snails consumed significantly more Spartina than Phragmites. Subsequent experiments demonstrated that Phragmites is chemically deterrent to snails by an unknown, moderately polar, compound. Further studies are required to more fully understand the interactions between Phragmites, herbivores, and Spartina, and how they may impact marsh ecosystems.

  6. Behavioural responses of the snail Lymnaea acuminata to carbohydrates and amino acids in bait pellets.

    Science.gov (United States)

    Agrahari, P; Singh, D K

    2010-12-01

    Snail control could play an important role in programmes against fascioliasis, especially if the methods used for molluscicide delivery could be improved, such as by the development of bait formulations containing both an effective attractant and a molluscicide, to ensure good levels of contact between the molluscicide and the target snail populations. In a recent study, the attractiveness to Lymnaea acuminata (an intermediate host of the digenean trematode Fasciola gigantica) of potential components of snail-attractant pellets was investigated. Carbohydrates (glucose, maltose, sucrose or starch, each at 10 mM) and amino acids (citrulline, tryptophan, proline or serine, each at 20 mM), were tested in aquaria, with the snails initially placed 22.5, 30 or 45 cm from an agar pellet containing the component under test. Under these conditions, starch and proline emerged as the strongest attractants for L. acuminata, followed by maltose and serine.

  7. Detection of Fasciola gigantica infection in snails by polymerase chain reaction.

    Science.gov (United States)

    Velusamy, R; Singh, B P; Raina, O K

    2004-02-26

    Polymerase chain reaction (PCR) was used to detect Fasciola gigantica infection in the snail intermediate host. Fasciola specific primers amplified a 124 bp fragment in PCR when the genomic DNA isolated from F. gigantica infected Lymnaea auricularia snails was used as template. In addition to the 124 bp amplicon, a ladder of DNA fragments representing amplification of the 124 bp repetitive sequences was observed. Genomic DNA of the parasite was used as a positive control, which also gave an amplification of the 124 bp fragment. DNA isolated from non-infected snails was used as a negative control and no amplification of this sequence was observed. This technique is highly specific and sensitive and possesses fairly good prospects of its utility as an epidemiological tool for ascertaining the infectivity status in ubiquitous snail populations.

  8. Palatability of Thlaspi caerulescens for snails: influence of zinc and glucosinolates.

    Science.gov (United States)

    Noret, N; Meerts, P; Tolrà, R; Poschenrieder, C; Barceló, J; Escarre, J

    2005-03-01

    * The hypothesis that zinc (Zn) hyperaccumulation defends Thlaspi caerulescens against herbivores is tested with the snail Helix aspersa. We investigated the effects of leaf zinc, cadmium, glucosinolate, nitrogen and dry matter concentrations on the feeding preferences of snails. * Four T. caerulescens populations from southern France (two from metalliferous and two from normal soils) were grown on low- and high-Zn soils to obtain contrasting leaf Zn concentrations. Plants were also collected in the field, and binary feeding choices involving low- and high-Zn leaves were conducted. * Foliar Zn, Cd, N and dry matter concentrations did not affect the feeding choices of snails, whereas glucosinolate had a significant negative effect on herbivore preferences. Compared with metallicolous plants, nonmetallicolous ones appeared to be better protected against snails, whatever their Zn concentration. * These results do not support the defence hypothesis, as glucosinolates appear to decrease the degree of herbivory when Zn does not.

  9. Targeted inactivation of Snail family EMT regulatory factors by a Co(III)-Ebox conjugate

    National Research Council Canada - National Science Library

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

    2012-01-01

    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...

  10. Dynamic Chromatin Modification Sustains Epithelial-Mesenchymal Transition following Inducible Expression of Snail-1

    Directory of Open Access Journals (Sweden)

    Sarah Javaid

    2013-12-01

    Full Text Available 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.

  11. Dynamic Chromatin Modification Sustains Epithelial-Mesenchymal Transition following Inducible Expression of Snail-1

    Science.gov (United States)

    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.

    2014-01-01

    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. PMID:24360956

  12. Effect of Diet on Growth and Reproduction of the African Giant Snail ...

    African Journals Online (AJOL)

    ... range of feed materials grew fastest, matured sexually earliest, and laid eggs ... The implications of the study for snail culture in cages and pasture systems were discussed. Key Words: Archachatina marginata, nutrition, growth, reproduction.

  13. Ants as shell collectors: notes on land snail shells found around ant nests

    Directory of Open Access Journals (Sweden)

    Barna Páll-Gergely

    2009-03-01

    Full Text Available We investigated the shell collecting activities of harvester ants (Messor spp. in semi-arid grasslands and shrubs in Turkey. We found eleven species of snails in the area, two of them were not collected by ants. Eight – mainly small sized – snail species were found on ant nests in a habitat characterized by shrubs, three in rocky grassland and four in a grassland habitat. Some shells (e.g. Chondrus zebrula tantalus, Multidentula ovularis might be taken into the nests, and we hypothesise that some of these snail species are consumed by ants (Monacha spp.. From a fauna inventory perspective, shell collecting activities of harvester ant may help malacologists to find snail species which are normally hidden for a specialist (e.g. Oxychilus hydatinus, Cecilioides spp. due to their special habits.

  14. Studies on the survival and development of field-caught snail Lymnaea rubiginosa in the laboratory

    Directory of Open Access Journals (Sweden)

    S Widjajanti

    1998-10-01

    Full Text Available Lymnaea rubiginosa was collected from two habitats in order to observe their survival and growth rate including their egg production, hatching time and the time they needed to reach maturity. One of the habitat is rice fields in Bogor (subdistricts of Ciomas and Ciampea and the other is a pond in Bogor Botanical Garden. In the laboratory those snails were kept in separate aquarium and grouped according to their shell length. The result showed that the longer the snail length the shorter their survival rate and less egg production. Moreover, the snails collected from rice fields were infected with Echinostoma sp. And Chaetogaster sp., while the snails from the pond were only infected with Chaetogaster sp. The hatching time is between 10-14 days, and to reach maturity, with shell length about 1 cm, they need about 6 weeks.

  15. Microbiological and chemical analysis of land snails commercialised in Sicily

    Directory of Open Access Journals (Sweden)

    Antonello Cicero

    2015-05-01

    Full Text Available In this study 160 samples of snails belonging to the species Helix aspersa maxima and Helix aspersa muller were examined for chemical and microbiological analysis. Samples came from Greece and Poland. Results showed mean concentration of cadmium (0.35±0.036 mg/kg and lead (0.05±0.013 mg/kg much higher than the limit of detection. Mercury levels in both species were not detected. Microbiological analysis revealed the absence of Salmonella spp. and Clostridium spp. in both examined species. E. coli and K. oxytoca were observed in Helix aspersa maxima and Helix aspersa muller. Furthermore, one case of fungi positivity in samples of Helix aspersa muller was found. The reported investigations highlight the need to create and adopt a reference legislation to protect the health of consumers.

  16. Diversity increases biomass production for trematode parasites in snails

    Science.gov (United States)

    Hechinger, Ryan F.; Lafferty, Kevin D.; Kuris, Armand M.

    2008-01-01

    Increasing species diversity typically increases biomass in experimental assemblages. But there is uncertainty concerning the mechanisms of diversity effects and whether experimental findings are relevant to ecological process in nature. Hosts for parasites provide natural, discrete replicates of parasite assemblages. We considered how diversity affects standing-stock biomass for a highly interactive parasite guild: trematode parasitic castrators in snails. In 185 naturally occurring habitat replicates (individual hosts), diverse parasite assemblages had greater biomass than single-species assemblages, including those of their most productive species. Additionally, positive diversity effects strengthened as species segregated along a secondary niche axis (space). The most subordinate species—also the most productive when alone—altered the general positive effect, and was associated with negative diversity effects on biomass. These findings, on a previously unstudied consumer class, extend previous research to illustrate that functional diversity and species identity may generally both explain how diversity influences biomass production in natural assemblages of competing species.

  17. The Epithelial-Mesenchymal Transition Factor SNAIL Paradoxically Enhances Reprogramming

    Directory of Open Access Journals (Sweden)

    Juli J. Unternaehrer

    2014-11-01

    Full Text Available Reprogramming of fibroblasts to induced pluripotent stem cells (iPSCs entails a mesenchymal to epithelial transition (MET. While attempting to dissect the mechanism of MET during reprogramming, we observed that knockdown (KD of the epithelial-to-mesenchymal transition (EMT factor SNAI1 (SNAIL paradoxically reduced, while overexpression enhanced, reprogramming efficiency in human cells and in mouse cells, depending on strain. We observed nuclear localization of SNAI1 at an early stage of fibroblast reprogramming and using mouse fibroblasts expressing a knockin SNAI1-YFP reporter found cells expressing SNAI1 reprogrammed at higher efficiency. We further demonstrated that SNAI1 binds the let-7 promoter, which may play a role in reduced expression of let-7 microRNAs, enforced expression of which, early in the reprogramming process, compromises efficiency. Our data reveal an unexpected role for the EMT factor SNAI1 in reprogramming somatic cells to pluripotency.

  18. Solar radio-transmitters on snail kites in Florida

    Science.gov (United States)

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

    1989-01-01

    The effectiveness and safety of one- and two-stage solar radio-transmitters in tracking the movements and survival of adult and fledgling Snail Kites (Rostrhamus sociabilis) were evaluated between 1979 and 1983 in southern Florida. Transmitters were attached to birds with back-pack arrangements using teflon ribbon straps. Accessory plastic shields minimized feather coverage of the solar cells. Intact transmitters were seen on birds up to 47 mo after installation. Operating lives ranged from 8 to 21 mo for one-stage, and 10 to 14 mo for two-stage transmitters. Because survival of adult and nestling radio-marked kites was high, we conclude that our transmitter-attachment method had little effect on the birds.

  19. Bioaccumulative and conchological assessment of heavy metal transfer in a soil-plant-snail food chain

    Directory of Open Access Journals (Sweden)

    Nica Dragos V

    2012-06-01

    Full Text Available Abstract 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

  20. Preparation and evaluation of appertized from snail Helix aspersa M

    Directory of Open Access Journals (Sweden)

    Nelson Loyola López

    2015-01-01

    Full Text Available This study includes the development and evaluation of snails (Helix aspersa M. appertized, collected at a heliciculture breeding center, located in Los Niches sector, Curico, Maule region, South-central of Chile. The test was conducted at the Laboratory of Sciences of the Catholic University of Maule, Nuestra Señora del Carmen Campus, Curico. The main objective of this work was to study the influence of appertized on sensory attributes and commercial durability of snail Helix aspersa M. Additionally, some specific objectives were proposed as follow: to provide this mollusc with a commercial alternative for it consume, to evaluate its organoleptic characteristics and guarantee the product from both the microbiological and nutritional points of view. Three media cover were used (T0: water + NaCl 2%; T1: Water + NaCl 2% + citric acid 0.5% + kilol and T2: extra virgin olive oil + spices + tocopherol. The product was assessed at two different times, after 30 and 90 days of storage. Two sensory evaluations were conducted to measure various organoleptic attributes and acceptability of the appertized by 14 trained panelists. Amino acid, vitamins, cholesterol, acidity, heavy metals, phosphorus and organochlorines analysis were performed. The presence of both total and fecal contaminant microorganisms was determined. Attributes such as color, flavor, aroma, texture and overall acceptability were also measured. Preserves made by T0 and T1 treatments were equally accepted by the panelists. However, preserve from treatment T2 was rejected because of the detection in them of a very dark color, odor and mealy texture. Positive results regarding the content of amino acids, vitamin C and low cholesterol, as well as the absence of pathogenic microorganisms were obtained for the three treatments.

  1. A proposal of space foods for long-term stay in space: Use of snail

    OpenAIRE

    Katayama, Naomi; Yamashita, Masamichi; 片山, 直美; 山下, 雅道

    2009-01-01

    Development of regenerative life-support system is necessary for long term manned space mission. In particular, food is the most important subject to study on. We aim to provide delicious space foods to space crew. Use of snail is proposed for this purpose. Snail can convert biomass of algae, which is in lower grade as human food, to a gourmet food with high quality protein.

  2. Cytokines and mother sporocysts in susceptible and resistant Bulinus truncatus snails infected with Schistosoma haematobium.

    Science.gov (United States)

    El-Din, Abdel Hakim Saad; Gawish, Fathiya Ali; Abu El Einin, Hanaa Mohamed; Mansour, Shereen Mahfouz

    2014-08-01

    The presence of immunoreactive interleukin (IL-2), interferon gamma (IFN-γ) and tumor necrosis factor alpha (TNF-α) in addition to the citation of mother sporscytes in cephalopodal musculature in the susceptible and resistance Bulinus truncatus the specific intermediate host for the trematode Schistosoma haematobium were investigated,. Using ELISA tests, Results indicated that the concentration of IL-2-like activity in the susceptible and resistant snails decreased significantly after infection then persisted at low levels until the 4th week post exposure (WPE) in susceptible snails, while in resistant snails elevated during the second WPE, and returned to initial level at 3 and 4 WPE. Susceptible snails had low detectable levels of TNF-α and INF-γ like-activity after infection. However, the resistant snails had significant low levels of TNF-α and INF-γ like-activity from 3 WPE until the 4th WPE without any sign of normalization. Histological sections in the head- foot region of susceptible and resistance B. truncatus infected with S. haematobium, mother sporocysts exists from 1 to 7(day post exposure) DPE, in the susceptible snail the mother sporocysts were found as single, multiple and mature types. No mother sporocysts were appear in the lip and mantle of the snail on 2, 5, 7 DPE and on 1-3, 6 DPE respectively. In the resistant snails few mother sporocysts were found in the lip, mantle and tentacles. The results showed that schistosome-resistant Bulinus can be an alternative strategy for the control of schistosomiasis.

  3. The potential utility of nested PCR for investigation of Coxiella burnetii in Iranian snails

    OpenAIRE

    2016-01-01

    Objective: To detect the prevalence of Coxiella burnetii (C. burnetii) in two species of snails consisted of Lymnaea palustris (L. palustris) and Pomacea canaliculata (P. canaliculata) by using nested PCR method in Chaharmahel Va Bakhtiari Province which is located in the southwest of Iran. Methods: A total of 160 snail samples consisted of 100 L. palustris and 60 P. canaliculata were collected from 4 rice paddy fields in the southwest of Iran between June and August 2014. S...

  4. Shading decreases the abundance of the herbivorous California horn snail, Cerithidea californica

    Science.gov (United States)

    Lorda, Julio; Lafferty, Kevin D.

    2012-01-01

    Most of the intertidal zone in estuaries of California, USA and Baja California, Mexico is covered with vascular vegetation. Shading by these vascular plants influences abiotic and biotic processes that shape benthic community assemblages. We present data on the effects of shading on the California horn snail, Cerithidea californica. This species is important because it is the most common benthic macrofaunal species in these systems and acts as an obligate intermediate host of several species of rematode parasites that infect several other species. Using observational and experimental studies, we found a negative effect of shade on the distribution and abundance of the California horn snail. We hypothesized that shading reduces the abundance of the epipelic diatoms that the snails feeds on, causing snails to leave haded areas. We observed a negative relationship between vascular plant cover, sub-canopy light levels, and snail density in Mugu Lagoon. Then we experimentally manipulated light regimes, by clipping vegetation and adding shade structures, and found higher snail densities at higher light levels. In Goleta Slough, we isolated the effect of shade from vegetation by documenting a negative relationship between the shade created by two bridges and diatom and snail densities. We also found that snails moved the greatest distances over shaded channel banks compared to unshaded channel banks. Further, we documented the effect of water depth and channel bank orientation on shading in this system. An additional effect of shading is the reduction of temperature, providing an alternative explanation for some of our results. These results broaden our knowledge of how variation in the light environment influences the ecology of estuarine ecosystems.

  5. Calcareous forest seepages acting as biodiversity hotspots and refugia for woodland snail faunas

    Science.gov (United States)

    Horsák, Michal; Tajovská, Eva; Horsáková, Veronika

    2017-07-01

    Land-snail species richness has repeatedly been found to increase with the increasing site calcium content and humidity. These two factors, reported as the main drivers of land-snail assemblage diversity, are also among the main habitat characteristics of calcareous seepages. Here we explore local species richness and compositional variation of forest spring-fed patches (i.e. seepages), to test the hypothesis that these habitats might act as biodiversity hotspots and refugia of regional snail faunas. In contrast to treeless spring fens, only little is known about land snail faunas inhabiting forest seepages. Studying 25 isolated calcareous forest seepages, evenly distributed across the White Carpathians Protected Landscape Area (SE Czech Republic), we found that these sites, albeit spatially very limited, can harbour up to 66% of the shelled land-snail species known to occur in this well-explored protected area (in total 83 species). By comparing land snail assemblages of the studied seepages with those occurring in the woodland surroundings of each site as well as those previously sampled in 28 preserved forest sites within the study area, we found the seepages to be among the most species rich sites. Although the numbers of species did not statistically differ among these three systems, we found highly significant differences in species composition. Seepage faunas were composed of many species significantly associated with spring sites, in contrast to the assemblages of both surrounding and preserved forest sites. Our results highly support the hypothesis that calcareous forest seepages might serve as refugia and biodiversity hotspots of regional land snail faunas. Protection of these unique habitats challenges both conservation plans and forest management guidelines as they might act as sources for the recolonization and restoration of forest snail assemblages particularly in areas impoverished by harvesting and clearcutting.

  6. Deterministic assembly of land snail communities according to species size and diet.

    Science.gov (United States)

    Schamp, Brandon; Horsák, Michal; Hájek, Michal

    2010-07-01

    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

  7. The ectopic expression of Snail in MDBK cells does not induce epithelial-mesenchymal transition

    OpenAIRE

    IZAWA, GENYA; Kobayashi, Wakako; Haraguchi, Misako; Sudo, Akiharu; Ozawa, Masayuki

    2015-01-01

    Epithelial-mesenchymal transition (EMT), a key process in the tumor metastatic cascade, is characterized by the loss of cell-cell junctions and cell polarity, as well as by the acquisition of migratory and invasive properties. However, the precise molecular events that initiate this complex EMT process are poorly understood. Snail expression induces EMT in Madin-Darby canine kidney (MDCK) cells and the human epidermoid carcinoma cell line, A431. Snail is a zinc finger transcription factor and...

  8. The ectopic expression of Snail in MDBK cells does not induce epithelial-mesenchymal transition.

    Science.gov (United States)

    Izawa, Genya; Kobayashi, Wakako; Haraguchi, Misako; Sudo, Akiharu; Ozawa, Masayuki

    2015-07-01

    Epithelial-mesenchymal transition (EMT), a key process in the tumor metastatic cascade, is characterized by the loss of cell-cell junctions and cell polarity, as well as by the acquisition of migratory and invasive properties. However, the precise molecular events that initiate this complex EMT process are poorly understood. Snail expression induces EMT in Madin-Darby canine kidney (MDCK) cells and the human epidermoid carcinoma cell line, A431. Snail is a zinc finger transcription factor and triggers EMT by suppressing E-cadherin expression. In the present study, to broaden our knowledge of Snail‑induced EMT, we generated stable Snail transfectants using Madin-Darby bovine kidney (MDBK) cells. Contrary to the MDCK or A431 cells examined in our previous studies, the MDBK cells transfected with the Snail construct maintained an epithelial morphology and showed no sign of reduced cell-cell adhesiveness compared to the control cells. Consistent with these observations, the downregulation of epithelial marker proteins, e.g. E-cadherin and desmoglein, and the upregulation of mesenchymal marker proteins, e.g., N-cadherin and fibronectin, were not detected. Furthermore, the E-cadherin promoter was not methylated. Therefore, in the MDBK cells, the ectopic expression of Snail failed to induce EMT. As previously demonstrated, in MDCK cells, Snail expression is accompanied by the increased expression of other EMT-inducing transcription factors, e.g., Slug and zinc finger E-box-binding homeobox 1 (ZEB1). However, the MDBK cells transfected with the Snail construct did not exhibit an increased expression of these factors. Thus, it is possible that the failure to upregulate other EMT-related transcription factors may explain the lack of Snail-mediated induction of EMT in MDBK cells.

  9. BHC80 is Critical in Suppression of Snail-LSD1 Interaction and Breast Cancer Metastasis

    Science.gov (United States)

    2014-04-01

    Flores A, Dantzer F, Collard J, de Herreros AG, Oliver FJ. Poly(ADP-ribose) dependent regulation of Snail1 protein stability. Oncogene 2011; 30:4365-72...Mediated Transcription. Molecular Cell 2010; 40:521-32. 25 40. Rodriguez MI, Gonzalez-Flores A, Dantzer F, Collard J, de Herreros AG, Oliver FJ...transcription factors, such as Snail, Twist and ZEB1, have been recognized as E-cadherin suppressors and EMT inducers [6, 7]. Not surprisingly, these

  10. IMPOSEX IN THE MARINE SNAIL XANTHOCHORUS BUXEA (BRODERIP, 1833) (MURICIDAE) FROM THE SOUTH AMERICAN PACIFIC

    OpenAIRE

    Guabloche, Angélica; Alvarez, Javier; Rivas, Rolf; Hurtado, Soledad; Pradel, Renzo; Iannacone,Jose

    2013-01-01

    The imposex phenomenon is the emergence of male sexual characteristics on the reproductive system of female prosobranch gastropod snails. This alteration was historically associated with contamination with organotin compounds, such as tributyltin (TBT). In this study we evaluated the incidence of imposex in the marine snail Xanthochorus buxea (Broderip, 1833) (Muricidae) from Hermosa Beach, Ancon, Lima, Peru. Imposex percentage was 97.6%. The rate of the relative length of the ...

  11. The effect of aquatic plant abundance on shell crushing resistance in a freshwater snail.

    Directory of Open Access Journals (Sweden)

    Johel Chaves-Campos

    Full Text Available 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.

  12. The Giant Snail Achatina fulica as a Candidate Species for Advanced Bioregenerative Life Support Systems

    Science.gov (United States)

    Verbitskaya, Olga; Manukovsky, Nickolay; Kovalev, Vladimir

    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.

  13. Spanning Tree Problem

    Directory of Open Access Journals (Sweden)

    Yen Hung Chen

    2012-01-01

    minimum cost spanning tree T in G such that the total weight in T is at most a given bound B. In this paper, we present two polynomial time approximation schemes (PTASs for the constrained minimum spanning tree problem.

  14. Making Tree Ensembles Interpretable

    OpenAIRE

    Hara, Satoshi; Hayashi, Kohei

    2016-01-01

    Tree ensembles, such as random forest and boosted trees, are renowned for their high prediction performance, whereas their interpretability is critically limited. In this paper, we propose a post processing method that improves the model interpretability of tree ensembles. After learning a complex tree ensembles in a standard way, we approximate it by a simpler model that is interpretable for human. To obtain the simpler model, we derive the EM algorithm minimizing the KL divergence from the ...

  15. Embeddings of Iteration Trees

    OpenAIRE

    Mitchell, William

    1992-01-01

    This paper, dating from May 1991, contains preliminary (and unpublishable) notes on investigations about iteration trees. They will be of interest only to the specialist. In the first two sections I define notions of support and embeddings for tree iterations, proving for example that every tree iteration is a direct limit of finite tree iterations. This is a generalization to models with extenders of basic ideas of iterated ultrapowers using only ultrapowers. In the final section (which is m...

  16. How terrestrial snails can be used in risk assessment of soils.

    Science.gov (United States)

    de Vaufleury, Annette; Coeurdassier, Michaël; Pandard, Pascal; Scheifler, Renaud; Lovy, Christiane; Crini, Nadia; Badot, Pierre-Marie

    2006-03-01

    Among soil invertebrates, terrestrial snails are herbivorous and detritivorous organisms exposed to polluted soils by both digestive and cutaneous routes. Using laboratory-reared snails (Helix aspersa aspersa), we describe how the effects of contaminants on survival and growth of snails can be evaluated in laboratory bioassays. A national ring test was performed to assess the effect of Cd added to the soil or to the food. The ecotoxicity of sewage sludge also was evaluated. The present results demonstrate that toxicity depends on both the pollutants and the exposure route. Cadmium was sixfold more toxic for snails exposed via food contamination (median effective concentration [EC50], 68-139 microg/g) than via soil contamination (EC50, 534-877 microg/g), whereas the opposite occurred with the sewage sludge (EC50, 55% of sludge in the food and 10% of waste in the soil). A logistic relationship linked growth inhibition and internal Cd concentrations, which can reach 2,000 microg/g in the viscera of snails exposed to 626 microg/g in the food. No clear trend was found between Cu, Zn, Pb, Cr, and Ni concentrations in the sludge and in snail tissues. These data enabled the development of an international standard, which should enhance the use of terrestrial gastropods for both fundamental research and routine risk assessment in the terrestrial environment.

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

    Science.gov (United States)

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

    2014-03-01

    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 27.4μgL(-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.

  18. Toxicity of copper sulfate and rotenone to Chinese mystery snail (Bellamya chinensis)

    Science.gov (United States)

    Haak, Danielle M.; Stephen, Bruce J.; Kill, Robert A.; Smeenk, Nicholas A.; Allen, Craig R.; Pope, Kevin L.

    2014-01-01

    The Chinese mystery snail (Bellamya chinensis) is a freshwater snail native to Southeast Asia, Japan, and Russia and is currently classified as an invasive species in at least 27 states in the USA. The species tolerates a wide range of environmental conditions, making management of established populations difficult. We tested the efficacy of two traditional chemical treatments, rotenone and copper sulfate, on the elimination of adult Chinese mystery snails in laboratory experiments. All snails (N=50) survived 72-hour exposure to rotenone-treated lake water, and 96% (N=25) survived 72-hour exposure to pre-determined rotenone concentrations of 0.25, 2.5, and 25.0 mg/L. All snails (N=10) survived exposure to 1.25 mg/L copper sulfate solution, 90% (N=10) survived exposure to 2.50 mg/L copper sulfate solution, and 80% (N=5) survived exposure to 5.0 mg/L copper sulfate solution. Neither rotenone nor copper sulfate effectively killed adult Chinese mystery snails in laboratory experiments, most likely due to their relatively large size, thick shell, and operculum. Therefore, it appears that populations will be very difficult to control once established, and management should focus on preventing additional spread or introductions of this species.

  19. Impact of invasive apple snails on the functioning and services of natural and managed wetlands

    Science.gov (United States)

    Horgan, Finbarr G.; Stuart, Alexander M.; Kudavidanage, Enoka P.

    2014-01-01

    At least 14 species of apple snail (Ampullariidae) have been released to water bodies outside their native ranges; however, less than half of these species have become widespread or caused appreciable impacts. We review evidence for the impact of apple snails on natural and managed wetlands focusing on those studies that have elucidated impact mechanisms. Significant changes in wetland ecosystems have been noted in regions where the snails are established: Two species in particular (Pomacea canaliculata and Pomacea maculata) have become major pests of aquatic crops, including rice, and caused enormous increases in molluscicide use. Invasive apple snails have also altered macrophyte community structure in natural and managed wetlands through selective herbivory and certain apple snail species can potentially shift the balance of freshwater ecosystems from clear water (macrophyte dominated) to turbid (plankton dominated) states by depleting densities of native aquatic plants. Furthermore, the introductions of some apple snail species have altered benthic community structure either directly, through predation, or indirectly, through exploitation competition or as a result of management actions. To date much of the evidence for these impacts has been based on correlations, with few manipulative field or mesocosm experiments. Greater attention to impact monitoring is required, and, for Asia in particular, a landscape approach to impact management that includes both natural and managed-rice wetlands is recommended.

  20. Aragonite-calcite transformation in fossil snail shells of loess sequences in Loess Plateau, Central China

    Institute of Scientific and Technical Information of China (English)

    SHENG Xuefen; CHEN Jun; CAI Yuanfeng; CHEN Yang; JI Junfeng

    2005-01-01

    The methods of X-ray diffraction (XRD) and ICP-AES are applied to analyzing the mineral composition of modern and fossil snail shells in Luochuan section and Xifeng section. The results show that the mineral phase of calcium carbonate in modern snail shells is aragonite, but for some fossil snail shells in certain layers of loess sequences, a part of aragonite is transformed into calcite. In Luochuan and Xifeng sections, the stratigraphic borderline of aragonite-calcite transformation appearing obviously is between L5 and L6. Under the earth surface condition, the aragonite-calcite transformation is influenced by the factor of temperature only in a long time scale. It seems that the pressure is not the factor influencing the aragonite-calcite transformation. The results also show that existing age of snail shells is possibly the dominant and principal factor for the aragonite-calcite transformation. To a certain extent, the degree of aragonite-calcite transformation in snail shell is controlled by the content of trace element, such as Mg2+. The trace element can improve the stability of snail shell aragonite and impede the process of aragonite transforming into calcite.

  1. Polycomb complex 2 is required for E-cadherin repression by the Snail1 transcription factor

    DEFF Research Database (Denmark)

    Herranz, Nicolás; Pasini, Diego; Díaz, Víctor M

    2008-01-01

    The transcriptional factor Snail1 is a repressor of E-cadherin gene (CDH1) expression essential for triggering epithelial-mesenchymal transition (EMT). Snail1 represses CDH1 directly binding its promoter and inducing the synthesis of Zeb1 repressor. In this article we show that repression of CDH1...... by Snail1, but not by Zeb1, is dependent on the activity of the Polycomb repressive complex 2 (PRC2). ES cells null for Suz12, one of the components of PRC2, show higher levels of Cdh1 mRNA than control ES cells. In tumour cells, interference of PRC2 activity prevents the ability of Snail1 to down......-regulate CDH1 and partially de-represses CDH1. Chromatin immunoprecipitation assays demonstrated that Snail1 increases the binding of Suz12 to CDH1 promoter and the tri-methylation of lysine 27 in the histone 3. Moreover, Snail1 interacts with Suz12 and Ezh2 as shown by coimmunoprecipitation experiments...

  2. Spatial distribution of Biomphalaria spp., the intermediate host snails of Schistosoma mansoni, in Brazil.

    Science.gov (United States)

    Scholte, Ronaldo G C; Carvalho, Omar S; Malone, John B; Utzinger, Jürg; Vounatsou, Penelope

    2012-09-01

    Schistosomiasis mansoni remains an important parasitic disease of man, endemic in large parts of sub-Saharan Africa, the Middle East, South America and the Caribbean. The aetiological agent is the trematode Schistosoma mansoni, whereas aquatic snails of the genus Biomphalaria act as intermediate hosts in the parasite life cycle. In Brazil, the distribution of Biomphalaria spp. is closely associated with the occurrence of schistosomiasis. The purpose of this study was to map and predict the spatial distribution of the intermediate host snails of S. mansoni across Brazil. We assembled snail "presenceonly" data and used a maximum entropy approach, along with climatic and environmental variables to produce predictive risk maps. We identified a series of risk factors that govern the distribution of Biomphalaria snails. We find that high-risk areas for B. glabrata are concentrated in the regions of Northeast and Southeast and the northern part of the South region. B. straminea are found in the Northeast and Southeast regions, and B. tenagophila are concentrated in the Southeast and South regions. Our findings confirm that the presence of the intermediate host snails is correlated with the occurrence of schistosomiasis mansoni. The generated risk maps of intermediate host snails might assist the national control programme for spatial targeting of control interventions and to ultimately move towards schistosomiasis elimination in Brazil.

  3. The potential utility of nested PCR for investigation ofCoxiella burnetii in Iranian snails

    Institute of Scientific and Technical Information of China (English)

    Mina Dehghani-Samani; Abbas Doosti; Asghar Arshi

    2016-01-01

    Objective: To detect the prevalence ofCoxiella burnetii (C. burnetii) in two species of snails consisted ofLymnaea palustris (L. palustris) andPomacea canaliculata (P. canaliculata) by using nestedPCR method in Chaharmahel Va Bakhtiari Province which is located in the southwest of Iran. Methods:A total of160 snail samples consisted of 100L. palustris and 60P. canaliculata were collected from 4 rice paddy fields in the southwest of Iran between June and August 2014. Snails'DNA was extracted by a genomicDNA purification kit according to the manufacturer's instructions. Detection of the presence ofC. burnetii'sDNA was carried out by using a nested PCR assay with [specific primers outer membrane protein 1 (OMP1)-OMP2 and OMP3-OMP4] targeting the com1 gene. Results: In this study, a total of 160 snail samples were tested and 15 (9.37%) samples were found positive forC. burnetii, 15 samples were positive from theL. palustris and there were no positive samples fromP. canaliculata. Conclusions: Snails are kind of gastropods which seem to be harmless in life, but these small gastropods can be very dangerous for farmers, especially in humid climates. Also,C. burnetii in snails showed that this bacterium can be a factor of transmission of contamination to human beings and animals.

  4. Are sick individuals weak competitors? Competitive ability of snails parasitized by a gigantism-inducing trematode.

    Science.gov (United States)

    Seppälä, Otto; Karvonen, Anssi; Kuosa, Marja; Haataja, Maarit; Jokela, Jukka

    2013-01-01

    Parasitized individuals are often expected to be poor competitors because they are weakened by infections. Many trematode species, however, although extensively exploiting their mollusc hosts, also induce gigantism (increased host size) by diverting host resources towards growth instead of reproduction. In such systems, alternatively to reduced competitive ability due to negative effects of parasitism on host performance, larger size could allow more efficient resource acquisition and thus increase the relative competitive ability of host individuals. We addressed this hypothesis by testing the effect of a trematode parasite Diplostomum pseudospathaceum on the competitive ability of its snail host Lymnaea stagnalis. We experimentally examined the growth of snails kept in pairs in relation to their infection status and intensity of resource competition (i.e. food availability). We found that parasitized snails grew faster and their reproduction was reduced compared to unparasitized individuals indicating parasite-induced gigantism. However, growth of the snails was faster when competing with parasitized individuals compared to unparasitized snails indicating reduced competitive ability due to parasitism. The latter effect, however, was relatively weak suggesting that the effects of the parasite on snail physiology may partly override each other in determining competitive ability.

  5. Differences in predatory pressure on terrestrial snails by birds and mammals

    Indian Academy of Sciences (India)

    Zuzanna M Rosin; Paulina Olborska; Adrian Surmacki; Piotr Tryjanowski

    2011-09-01

    The evolution of shell polymorphism in terrestrial snails is a classic textbook example of the effect of natural selection in which avian and mammalian predation represents an important selective force on gene frequency. However, many questions about predation remain unclear, especially in the case of mammals. We collected 2000 specimens from eight terrestrial gastropod species to investigate the predation pressure exerted by birds and mice on snails. We found evidence of avian and mammalian predation in 26.5% and 36.8% of the shells. Both birds and mammals were selective with respect to snail species, size and morphs. Birds preferred the brown-lipped banded snail Cepaea nemoralis (L.) and mice preferred the burgundy snail Helix pomatia L. Mice avoided pink mid-banded C. nemoralis and preferred brown mid-banded morphs, which were neglected by birds. In contrast to mice, birds chose larger individuals. Significant differences in their predatory pressure can influence the evolution and maintenance of shell size and polymorphism of shell colouration in snails.

  6. The potential utility of nested PCR for investigation of Coxiella burnetii in Iranian snails

    Directory of Open Access Journals (Sweden)

    Mina Dehghani-Samani

    2016-03-01

    Full Text Available Objective: To detect the prevalence of Coxiella burnetii (C. burnetii in two species of snails consisted of Lymnaea palustris (L. palustris and Pomacea canaliculata (P. canaliculata by using nested PCR method in Chaharmahel Va Bakhtiari Province which is located in the southwest of Iran. Methods: A total of 160 snail samples consisted of 100 L. palustris and 60 P. canaliculata were collected from 4 rice paddy fields in the southwest of Iran between June and August 2014. Snails' DNA was extracted by a genomic DNA purification kit according to the manufacturer's instructions. Detection of the presence of C. burnetii's DNA was carried out by using a nested PCR assay with [specific primers outer membrane protein 1 (OMP1-OMP2 and OMP3-OMP4] targeting the com1 gene. Results: In this study, a total of 160 snail samples were tested and 15 (9.37% samples were found positive for C. burnetii, 15 samples were positive from the L. palustris and there were no positive samples from P. canaliculata. Conclusions: Snails are kind of gastropods which seem to be harmless in life, but these small gastropods can be very dangerous for farmers, especially in humid climates. Also, C. burnetii in snails showed that this bacterium can be a factor of transmission of contamination to human beings and animals.

  7. Are sick individuals weak competitors? Competitive ability of snails parasitized by a gigantism-inducing trematode.

    Directory of Open Access Journals (Sweden)

    Otto Seppälä

    Full Text Available Parasitized individuals are often expected to be poor competitors because they are weakened by infections. Many trematode species, however, although extensively exploiting their mollusc hosts, also induce gigantism (increased host size by diverting host resources towards growth instead of reproduction. In such systems, alternatively to reduced competitive ability due to negative effects of parasitism on host performance, larger size could allow more efficient resource acquisition and thus increase the relative competitive ability of host individuals. We addressed this hypothesis by testing the effect of a trematode parasite Diplostomum pseudospathaceum on the competitive ability of its snail host Lymnaea stagnalis. We experimentally examined the growth of snails kept in pairs in relation to their infection status and intensity of resource competition (i.e. food availability. We found that parasitized snails grew faster and their reproduction was reduced compared to unparasitized individuals indicating parasite-induced gigantism. However, growth of the snails was faster when competing with parasitized individuals compared to unparasitized snails indicating reduced competitive ability due to parasitism. The latter effect, however, was relatively weak suggesting that the effects of the parasite on snail physiology may partly override each other in determining competitive ability.

  8. Hepatitis C virus NS4B protein induces epithelial-mesenchymal transition by upregulation of Snail.

    Science.gov (United States)

    Hu, Bicheng; Xie, Shenggao; Hu, Yuqian; Chen, Wen; Chen, Xiaofan; Zheng, Yi; Wu, Xinxing

    2017-04-21

    Chronic hepatitis C virus (HCV) infection is an important cause of hepatocellular carcinoma (HCC). Epithelial to mesenchymal transition (EMT) is a key process associated with tumor metastasis and poor prognosis. HCV infection, HCV core and NS5A protein could induce EMT process, but the role of NS4B on EMT remains poorly understood. We overexpressed HCV NS4B protein in HepG2 cells or Huh7.5.1 cells infected by HCVcc, the E-cadherin expression, N-cadherin expression and the EMT-associated transcriptional factor Snail were determined. The migration and invasion capabilities of the transfected cells were evaluated using wound-healing assay. Additionally, we used Snail siRNA interference to confirm the relation of HCV NS4B and Snail on EMT promotion. HCV NS4B increased the expression of EMT related markers and promoted cell migration and invasion. Snail knock-down almost completely eliminated the function of NS4B protein in EMT changes and reversed cell migration capacity to lower level. HCV NS4B protein could reduce the expression of Scribble and Hippo signal pathway were subsequently inactivated, resulting in the activation of PI3K/AKT pathway, which may be the reason for the up-regulation of Snail. This study demonstrates that HCV NS4B protein induces EMT progression via the upregulation of Snail in HCC, which may be a novel underlying mechanism for HCV-associated HCC development, invasion and metastasis.

  9. Snail nuclear transport: the gateways regulating epithelial-to-mesenchymal transition?

    Science.gov (United States)

    Muqbil, Irfana; Wu, Jack; Aboukameel, Amro; Mohammad, Ramzi M; Azmi, Asfar S

    2014-08-01

    Epithelial-to-mesenchymal transition (EMT) and the reverse process (MET) play central role in organ developmental biology. It is a fine tuned process that when disturbed leads to pathological conditions especially cancers with aggressive and metastatic behavior. Snail is an oncogene that has been well established to be a promoter of EMT through direct repression of epithelial morphology promoter E-cadherin. It can function in the nucleus, in the cytosol and as discovered recently, extracellularly through secretory vesicular structures. The intracellular transport of snail has for long been shown to be regulated by the nuclear pore complex. One of the Karyopherins, importin alpha, mediates snail import, while exportin 1 (Xpo1) also known as chromosome maintenance region 1 (CRM1) is its major nuclear exporter. A number of additional biological regulators are emerging that directly modulate Snail stability by altering its subcellular localization. These observations indicate that targeting the nuclear transport machinery could be an important and as of yet, unexplored avenue for therapeutic intervention against the EMT processes in cancer. In parallel, a number of novel agents that disrupt nuclear transport have recently been discovered and are being explored for their anti-cancer effects in the early clinical settings. Through this review we provide insights on the mechanisms regulating snail subcellular localization and how this impacts EMT. We discuss strategies on how the nuclear transport function can be harnessed to rein in EMT through modulation of snail signaling. Copyright © 2014 Elsevier Ltd. All rights reserved.

  10. Foraging and refuge use by a pond snail: Effects of physiological state, predators, and resources

    Science.gov (United States)

    Wojdak, Jeremy M.

    2009-09-01

    The costs and benefits of anti-predator behavioral responses should be functions of the actual risk of predation, the availability of the prey's resources, and the physiological state of the prey. For example, a food-stressed individual risks starvation when hiding from predators, while a well-fed organism can better afford to hide (and pay the cost of not foraging). Similarly, the benefits of resource acquisition are probably highest for the prey in the poorest state, while there may be diminishing returns for prey nearing satiation. Empirical studies of state-dependent behavior are only beginning, however, and few studies have investigated interactions between all three potentially important factors. Here I present the results of a laboratory experiment where I manipulated the physiological state of pond snails ( Physa gyrina), the abundance of algal resources, and predation cues ( Belostoma flumineum waterbugs consuming snails) in a full factorial design to assess their direct effects on snail behavior and indirect effects on algal biomass. On average, snails foraged more when resources were abundant, and when predators were absent. Snails also foraged more when previously exposed to physiological stress. Snails spent more time at the water's surface (a refuging behavior) in the presence of predation cues on average, but predation, resource levels, and prey state had interactive effects on refuge use. There was a consistent positive trait-mediated indirect effect of predators on algal biomass, across all resource levels and prey states.

  11. Molecular identification of symbionts from the pulmonate snail Biomphalaria glabrata in Brazil.

    Science.gov (United States)

    Hertel, Lynn A; Barbosa, Contança S; Santos, Ricardo A A L; Loker, Eric S

    2004-08-01

    The icthyosporean, Capsaspora owczarzaki, a known predator of Schistosoma mansoni sporocysts in vitro, is more prevalent in laboratory-reared strains of the intermediate snail host, Biomphalaria glabrata resistant to S. mansoni, than from the susceptible M line strain. We examined whether B. glabrata resistant to the NIH-PR-1 strain of S. mansoni from 2 regions in Brazil were also host to C. owczarzaki. Symbiont presence was examined using hemolymph culturing and nested polymerase chain reaction of snail genomic DNA with primers designed to specifically amplify sequences from relatives of the Icthyosporea. All B. glabrata of the resistant Salvador strain from the laboratory of Dr. Lobato Paraense in Rio de Janeiro, Brazil (n = 46) tested negative for symbionts. Three of 18 semiresistant 10-R2 B. glabrata from the laboratory of Dr. Barbosa in Recife, Brazil tested positive for C. owczarzaki. Another icthyosporean, Anurofeca sp., was identified from 1, 10-R2 snail and from 2 of 12 field-collected B. glabrata from Praia do Forte Orange, Ilha de Itamaracá. Snails from 2 other sites, Hotel Colibri, Pontezinha and Praia do Sossego, Ilha de Itamaracá, were negative for Anurofeca. Two genera of ciliates were also identified. Paruroleptus sp. was found in 4, 10-R2 snails and Trichodina sp. was identified in 2 field-collected snails from Praia do Forte Orange and Praia do Sossego.

  12. Seasonal variation in abiotic factors and ferulic acid toxicity in snail-attractant pellets against the intermediate host snail Lymnaea acuminata.

    Science.gov (United States)

    Agrahari, P; Singh, D K

    2013-11-01

    Laboratory evaluation was made to access the seasonal variations in abiotic environmental factors temperature, pH, dissolved oxygen, carbon dioxide, electrical conductivity and ferulic acid toxicity in snail-attractant pellets (SAP) against the intermediate host snail Lymnaea acuminata in each month of the years 2010 and 2011. On the basis of a 24-h toxicity assay, it was noted that lethal concentration values of 4.03, 3.73% and 4.45% in SAP containing starch and 4.16, 4.23% and 4.29% in SAP containing proline during the months of May, June and September, respectively, were most effective in killing the snails, while SAP containing starch/proline + ferulic acid was least effective in the month of January/February (24-h lethal concentration value was 7.67%/7.63% in SAP). There was a significant positive correlation between lethal concentration value of ferulic acid containing SAP and levels of dissolved O2 /pH of water in corresponding months. On the contrary, a negative correlation was observed between lethal concentration value and dissolved CO2 /temperature of test water in the same months. To ascertain that such a relationship between toxicity and abiotic factors is not co-incidental, the nervous tissue of treated (40% and 80% of 24-h lethal concentration value) and control group of snails was assayed for the activity of acetylcholinesterase (AChE) in each of the 12 months of the same year. There was a maximum inhibition of 58.43% of AChE, in snails exposed to 80% of the 24-h lethal concentration value of ferulic acid + starch in the month of May. This work shows conclusively that the best time to control snail population with SAP containing ferulic acid is during the months of May, June and September.

  13. Feeding behavior of black carp Mylopharyngodon piceus (Pisces: Cyprinidae) on fry of other fish species and trematode transmitting snail species

    DEFF Research Database (Denmark)

    Hung, Nguyen Manh; The, Dang Tat; Stauffer, Jay R.

    2014-01-01

    Fish raised in aquaculture ponds may get infected with fishborne zoonotic trematodes (FZT) during the nursing stage. Freshwater snails serve as intermediate hosts for FZT and we wanted to explore the possibility of controlling snails by stocking nursery ponds with a few juvenile specimens...... offered snails as food; the odds of survival of fry from tanks with medium sized and large black carp was 5.6% and 39.9%, respectively of that of fry in tanks with small sized black carp. Since the large black carp also consumed fewer snails than medium sized fish, we believe that large specimens were...... stressed in the experimental aquaria. Under semi-field conditions, presence of the black carp had no effect on survival of fry of Oreochromis niloticus and C. carpio both in the absence and presence of snails as alternative food. The black carp consumed most snails offered with the exception of some...

  14. Age-dependent susceptibilities of Bulinus truncatus snails to an aqueous extract of Pulicaria crispa (Forssk.) Oliv. (Asteraceae) leaves.

    Science.gov (United States)

    Ali, Elnour A; Bushara, Hamid O; Ali, Faisal S; Hussein, Mansour F

    2009-05-01

    This study was carried out to investigate the potential use of the herb Pulicaria crispa in the biological control of different developmental stages of Bulinus truncatus, a major snail intermediate host of urinary schistosomiasis. Age-dependent susceptibilities of mature adult snails, immature snails, juveniles, and one-day old egg masses to aqueous extracts of Pulicaria crispa leaves collected from Khartoum (Sudan) and Riyadh (Saudi Arabia) was determined and compared. The results show the juvenile snails are the most susceptible, followed in descending order by one-day old egg masses, immature snails, and mature adult snails. The P. crispa sample collected from Riyadh was significantly more potent against B. truncatus than that collected from Khartoum, as indicated by the least (LC50) and (LC90) values for all B. truncatus ages.

  15. Characteristics of Feeding Preference and Nutrients Utilization of Golden Apple Snail (Pomacea canaliculata on Macrophytes in Paddy Fields

    Directory of Open Access Journals (Sweden)

    Benliang Zhao

    2012-10-01

    Full Text Available Golden apple snail was a harmful invasive gastropod in Asian wetlands. In order to clarify the effect of Pomacea canaliculata on macrophytes in paddy fields, feeding preference and nutrients utilization of snail were studied. Feeding preference of snail was Alternanthera philoxenoides>Monochoria vaginalis>Oryza sativa L. Snail showed a higher approximate digestion coefficient on Oryza sativa L. than that on Monochoria vaginalis. Nitrogen utilization coefficient of snail on Alternanthera philoxenoides was significantly higher than that on Oryza sativa L. Snail exhibited a higher calcium utilization coefficient on Alternanthera philoxenoides and Monochoria vaginalis than that on Oryza sativa L. Oryza sativa L. was not preferred among three plants under the same available and exposure condition.

  16. Covering tree with stars

    DEFF Research Database (Denmark)

    Baumbach, Jan; Guo, Jian-Ying; Ibragimov, Rashid

    2013-01-01

    We study the tree edit distance problem with edge deletions and edge insertions as edit operations. We reformulate a special case of this problem as Covering Tree with Stars (CTS): given a tree T and a set of stars, can we connect the stars in by adding edges between them such that the resulting ...

  17. Covering tree with stars

    DEFF Research Database (Denmark)

    Baumbach, Jan; Guo, Jiong; Ibragimov, Rashid

    2015-01-01

    We study the tree edit distance problem with edge deletions and edge insertions as edit operations. We reformulate a special case of this problem as Covering Tree with Stars (CTS): given a tree T and a set of stars, can we connect the stars in by adding edges between them such that the resulting ...

  18. Macro tree transducers

    NARCIS (Netherlands)

    Engelfriet, Joost; Vogler, Heiko

    1985-01-01

    Macro tree transducers are a combination of top-down tree transducers and macro grammars. They serve as a model for syntax-directed semantics in which context information can be handled. In this paper the formal model of macro tree transducers is studied by investigating typical automata theoretical

  19. Winter Birch Trees

    Science.gov (United States)

    Sweeney, Debra; Rounds, Judy

    2011-01-01

    Trees are great inspiration for artists. Many art teachers find themselves inspired and maybe somewhat obsessed with the natural beauty and elegance of the lofty tree, and how it changes through the seasons. One such tree that grows in several regions and always looks magnificent, regardless of the time of year, is the birch. In this article, the…

  20. Total well dominated trees

    DEFF Research Database (Denmark)

    Finbow, Arthur; Frendrup, Allan; Vestergaard, Preben D.

    cardinality then G is a total well dominated graph. In this paper we study composition and decomposition of total well dominated trees. By a reversible process we prove that any total well dominated tree can both be reduced to and constructed from a family of three small trees....

  1. The Wish Tree Project

    Science.gov (United States)

    Brooks, Sarah DeWitt

    2010-01-01

    This article describes the author's experience in implementing a Wish Tree project in her school in an effort to bring the school community together with a positive art-making experience during a potentially stressful time. The concept of a wish tree is simple: plant a tree; provide tags and pencils for writing wishes; and encourage everyone to…

  2. The Wish Tree Project

    Science.gov (United States)

    Brooks, Sarah DeWitt

    2010-01-01

    This article describes the author's experience in implementing a Wish Tree project in her school in an effort to bring the school community together with a positive art-making experience during a potentially stressful time. The concept of a wish tree is simple: plant a tree; provide tags and pencils for writing wishes; and encourage everyone to…

  3. Macro tree transducers

    NARCIS (Netherlands)

    Engelfriet, Joost; Vogler, Heiko

    1985-01-01

    Macro tree transducers are a combination of top-down tree transducers and macro grammars. They serve as a model for syntax-directed semantics in which context information can be handled. In this paper the formal model of macro tree transducers is studied by investigating typical automata theoretical

  4. [Effects of heavy metals on snail development. Use of snails as bio-indicators of heavy metal pollution for the preservation of human health].

    Science.gov (United States)

    Gomot, A

    1997-01-01

    The use of snails as biological indicators is particularly appropriate for metals, which they accumulate in their organs. The aim of the present experiment was to carry out a rigorous experimentation in the laboratory and in the wild in order to develop a methodology for the use of snails at a known stage of growth that would give precise information on the toxicity of heavy metals for different concentrations and durations of exposure. We have developed a test of toxicity based on the effects of a noxious and carcinogenic element, cadmium, on the land-snail Helix aspersa aspersa (H.a.a) of one month of age. Five concentrations (50 to 800 micrograms/g), were selected to estimate the concentrations causing 50% inhibition of growth (EC 50) at 14 days: 190 micrograms/g and at 28 days: 180 micrograms/g. A soil matrix contaminated with metals (soil including 800 micrograms/g Cr, 20 micrograms/g Cd, 800 micrograms/g Pb and 2000 micrograms/g Zn) was incorporated into the food at 50 and 75%, it too inhibited the growth of juvenile snails compared to incorporation of control soil. An accurate and rapid (2 to 4 weeks) method is therefore available for the evaluation of the toxicity of pollutants by ingestion. The first trials of this method in the wild consisted of placing batches of 2-month-old snails, identical to those used in the first lab tests, in locations that were either polluted or not. Differences in growth were observed depending on the locations; analysis of the levels of metal in the organs of the snails should enable us to check if there is a correlation between these levels and the growth rates. The results obtained with cadmium compared to those of other authors working with earthworms and soil arthropods show that snails give responses to concentrations comparable to those of earthworms and much more rapidly and with more sensitivity than those of collembolla for example. The ease of handling snails and the perfect control of their breeding are essential

  5. Distribution and abundance of schistosomiasis and fascioliasis host snails along the Mara River in Kenya and Tanzania

    Directory of Open Access Journals (Sweden)

    Gabriel O. Dida

    2014-10-01

    Full Text Available We purposively selected 39 sampling sites along the Mara River and its two perennial tributaries of Amala and Nyangores and sampled snails. In addition, water physicochemical parameters (temperature, turbidity, dissolved oxygen, conductivity, alkalinity, salinity and pH were taken to establish their influence on the snail abundance and habitat preference. Out of the 39 sites sampled, 10 (25.6% had snails. The snail species encountered included Biomphalaria pfeifferi Krauss – the intermediate host of Schistosoma mansoni Sambon, Bulinus africanus – the intermediate host of Schistosoma haematobium, and Lymnaea natalensis Krauss – the intermediate host of both Fasciola gigantica and F. hepatica Cobbold. Ceratophallus spp., a non-vector snail was also encountered. Most (61.0% of the snails were encountered in streamside pools. Schistosomiasis-transmitting host snails, B. pfeifferi and B. africanus, were fewer than fascioliasis-transmitting Lymnaea species. All the four different snail species were found to be attached to different aquatic weeds, with B. pfeifferi accounting for over half (61.1% of the snails attached to the sedge, followed by B. africanus and Lymnaea spp., accounting for 22.2 and 16.7%, respectively. Ceratophallus spp. were non-existent in sedge. The results from this preliminary study show that snails intermediate hosts of schistosomiasis and fascioliasis exists in different habitats, in few areas along the Mara River, though their densities are still low to have any noticeable impacts on disease transmission in case they are infected. The mere presence of the vector snails in these focal regions calls for their immediate control and institution of proper regulations, management, and education among the locals that can help curtail the spread of the snails and also schistosomiasis and fascioliasis within the Mara River basin.

  6. Antigens of Euparipha pisana (snail). I. Identification of allergens by means of in vivo and in vitro analysis.

    Science.gov (United States)

    Amoroso, S; Cocchiara, R; Locorotondo, G; Parlato, A; Lampiasi, N; Albeggiani, G; Falagiani, P; Geraci, D

    1988-01-01

    The data obtained in this study suggest that eating Euparipha pisana (snail), a common food in Mediterranean countries, could give serious allergic reaction such as asthma. We describe here the identification and partial characterization of allergenic molecules form this new source. An aqueous extract of snail was obtained by homogenization in distilled water, centrifugation, dialysis and defatting with ethyl ether. Skin prick test (SPT) performed with the snail extract on 70 subjects allergic to the more common allergens of the Mediterranean area gave a SPT positivity in 61% of the subjects tested, with a mean value of histamine-equivalent prick (HEP) equal to 0.81 +/- 0.25 (n = 43), while no SPT-snail-positive reactions were obtained by using the same extract on 30 not allergic subjects. To ascertain if such a sensitivity was IgE-mediated, sera from SPT-snail-positive subjects were analyzed by RAST, coupling the snail extract to polystyrene balls and to paper discs. 19% of the sera tested were RAST-positive, mean value of binding 4.8 +/- 2.8% (n = 13), while when using sera from SPT-snail-negative subjects, the RAST mean value was 0.49 +/- 0.18% (n = 27). Histamine release (HR) was also performed. Basophils prepared from SPT-snail-positive subjects were incubated with a snail extract. All of the SPT-snail-positive subjects gave a significant value of HR, mean value 21.8 +/- 7% using 1 micrograms of snail extract (n = 16), while 1.41 +/- 1.1% (n = 10) was the mean value obtained when SPT-snail-negative subjects were analyzed.(ABSTRACT TRUNCATED AT 250 WORDS)

  7. Distribution and abundance of schistosomiasis and fascioliasis host snails along the Mara River in Kenya and Tanzania.

    Science.gov (United States)

    Dida, Gabriel O; Gelder, Frank B; Anyona, Douglas N; Matano, Ally-Said; Abuom, Paul O; Adoka, Samson O; Ouma, Collins; Kanangire, Canisius K; Owuor, Phillip O; Ofulla, Ayub V O

    2014-01-01

    We purposively selected 39 sampling sites along the Mara River and its two perennial tributaries of Amala and Nyangores and sampled snails. In addition, water physicochemical parameters (temperature, turbidity, dissolved oxygen, conductivity, alkalinity, salinity and pH) were taken to establish their influence on the snail abundance and habitat preference. Out of the 39 sites sampled, 10 (25.6%) had snails. The snail species encountered included Biomphalaria pfeifferi Krauss - the intermediate host of Schistosoma mansoni Sambon, Bulinus africanus - the intermediate host of Schistosoma haematobium, and Lymnaea natalensis Krauss - the intermediate host of both Fasciola gigantica and F. hepatica Cobbold. Ceratophallus spp., a non-vector snail was also encountered. Most (61.0%) of the snails were encountered in streamside pools. Schistosomiasis-transmitting host snails, B. pfeifferi and B. africanus, were fewer than fascioliasis-transmitting Lymnaea species. All the four different snail species were found to be attached to different aquatic weeds, with B. pfeifferi accounting for over half (61.1%) of the snails attached to the sedge, followed by B. africanus and Lymnaea spp., accounting for 22.2 and 16.7%, respectively. Ceratophallus spp. were non-existent in sedge. The results from this preliminary study show that snails intermediate hosts of schistosomiasis and fascioliasis exists in different habitats, in few areas along the Mara River, though their densities are still low to have any noticeable impacts on disease transmission in case they are infected. The mere presence of the vector snails in these focal regions calls for their immediate control and institution of proper regulations, management, and education among the locals that can help curtail the spread of the snails and also schistosomiasis and fascioliasis within the Mara River basin.

  8. Trees in Lhasa

    Institute of Scientific and Technical Information of China (English)

    Degyi

    2008-01-01

    Trees are flourishing in Lhasa wherever the history exists. There is such a man. He has already been through cus-toms after his annual trek to Lhasa, which he has been doing for over twenty years in succession to visit his tree.Although he has been making this journey for so long,it is neither to visit friends or family,nor is it his hometown.It is a tree that is tied so profoundly to his heart.When the wind blows fiercely on the bare tree and winter snow falls,he stands be-fore the tree with tears of jo...

  9. Distributed Contour Trees

    Energy Technology Data Exchange (ETDEWEB)

    Morozov, Dmitriy; Weber, Gunther H.

    2014-03-31

    Topological techniques provide robust tools for data analysis. They are used, for example, for feature extraction, for data de-noising, and for comparison of data sets. This chapter concerns contour trees, a topological descriptor that records the connectivity of the isosurfaces of scalar functions. These trees are fundamental to analysis and visualization of physical phenomena modeled by real-valued measurements. We study the parallel analysis of contour trees. After describing a particular representation of a contour tree, called local{global representation, we illustrate how di erent problems that rely on contour trees can be solved in parallel with minimal communication.

  10. FBXO11 promotes ubiquitination of the Snail family of transcription factors in cancer progression and epidermal development

    Science.gov (United States)

    Jin, Yue; Shenoy, Anitha K.; Doernberg, Samuel; Chen, Hao; Luo, Huacheng; Shen, Huangxuan; Lin, Tong; Tarrash, Miriam; Cai, Qingsong; Hu, Xin; Fiske, Ryan; Chen, Ting; Wu, Lizi; Mohammed, Kamal A.; Rottiers, Veerle; Lee, Siu Sylvia; Lu, Jianrong

    2015-01-01

    The Snail family of transcription factors are core inducers of epithelial-to-mesenchymal transition (EMT). Here we show that the F-box protein FBXO11 recognizes and promotes ubiquitin-mediated degradation of multiple Snail family members including Scratch. The association between FBXO11 and Snai1 in vitro is independent of Snai1 phosphorylation. Overexpression of FBXO11 in mesenchymal cells reduces Snail protein abundance and cellular invasiveness. Conversely, depletion of endogenous FBXO11 in epithelial cancer cells causes Snail protein accumulation, EMT, and tumor invasion, as well as loss of estrogen receptor expression in breast cancer cells. Expression of FBXO11 is downregulated by EMT-inducing signals TGFβ and nickel. In human cancer, high FBXO11 levels correlate with expression of epithelial markers and favorable prognosis. The results suggest that FBXO11 sustains the epithelial state and inhibits cancer progression. Inactivation of FBXO11 in mice leads to neonatal lethality, epidermal thickening, and increased Snail protein levels in epidermis, validating that FBXO11 is a physiological ubiquitin ligase of Snail. Moreover, in C. elegans, the FBXO11 mutant phenotype is attributed to the Snail factors as it is suppressed by inactivation/depletion of Snail homologs. Collectively, these findings suggest that the FBXO11-Snail regulatory axis is evolutionarily conserved and critically governs carcinoma progression and mammalian epidermal development. PMID:25827072

  11. Malacological survey and geographical distribution of vector snails for schistosomiasis within informal settlements of Kisumu City, western Kenya

    Directory of Open Access Journals (Sweden)

    Opisa Selpha

    2011-12-01

    Full Text Available Abstract Background Although schistosomiasis is generally considered a rural phenomenon, infections have been reported within urban settings. Based on observations of high prevalence of Schistosoma mansoni infection in schools within the informal settlements of Kisumu City, a follow-up malacological survey incorporating 81 sites within 6 informal settlements of the City was conducted to determine the presence of intermediate host snails and ascertain whether active transmission was occurring within these areas. Methods Surveyed sites were mapped using a geographical information system. Cercaria shedding was determined from snails and species of snails identified based on shell morphology. Vegetation cover and presence of algal mass at the sites was recorded, and the physico-chemical characteristics of the water including pH and temperature were determined using a pH meter with a glass electrode and a temperature probe. Results Out of 1,059 snails collected, 407 (38.4% were putatively identified as Biomphalaria sudanica, 425 (40.1% as Biomphalaria pfeifferi and 227 (21.5% as Bulinus globosus. The spatial distribution of snails was clustered, with few sites accounting for most of the snails. The highest snail abundance was recorded in Nyamasaria (543 snails followed by Nyalenda B (313 snails. As expected, the mean snail abundance was higher along the lakeshore (18 ± 12 snails compared to inland sites (dams, rivers and springs (11 ± 32 snails (F1, 79 = 38.8, P Biomphalaria snails was higher in the inland (2.7% compared to the lakeshore sites (0.3% (P = 0.0109. B. sudanica was more abundant in sites along the lakeshore whereas B. pfeifferi and B. globosus were more abundant in the inland sites. Biomphalaria and Bulinus snails were found at 16 and 11 out of the 56 inland sites, respectively. Conclusions The high abundance of Biomphalaria and Bulinus spp. as well as observation of field-caught snails shedding cercariae confirmed that besides Lake

  12. Growth of a Pine Tree

    Science.gov (United States)

    Rollinson, Susan Wells

    2012-01-01

    The growth of a pine tree is examined by preparing "tree cookies" (cross-sectional disks) between whorls of branches. The use of Christmas trees allows the tree cookies to be obtained with inexpensive, commonly available tools. Students use the tree cookies to investigate the annual growth of the tree and how it corresponds to the number of whorls…

  13. Growth of a Pine Tree

    Science.gov (United States)

    Rollinson, Susan Wells

    2012-01-01

    The growth of a pine tree is examined by preparing "tree cookies" (cross-sectional disks) between whorls of branches. The use of Christmas trees allows the tree cookies to be obtained with inexpensive, commonly available tools. Students use the tree cookies to investigate the annual growth of the tree and how it corresponds to the number of whorls…

  14. Distribution of trematodes in snails in ponds at integrated small-scale aquaculture farms.

    Science.gov (United States)

    Boerlage, Annette S; Graat, Elisabeth A M; Verreth, Johan A; de Jong, Mart C M

    2013-03-01

    In integrated small-scale aquaculture farming, animal and human excreta maybe used as fish feed and pond fertilizer, thereby enhancing transmission of fish-borne zoonotic trematodes (FZTs) from final hosts, like humans, pigs and chickens, to snails. Areas within a pond could vary in trematode egg-load due to the immediate bordering land, and this might provide implications for control of these trematodes or sampling in field studies measuring FZT prevalence in snails. We therefore estimated the effect of bordering land use on prevalence and FZT burden in snails in different areas within small-scale aquaculture ponds. Nine sampling areas within a pond were assigned in six ponds. For each sampling area, about 120 Melanoides tuberculata snails were collected. Based on land use bordering a sampling area, these were categorized in 5 risk-categories: low-risk (road, rice planted in pond, agriculture, or middle of pond), human access point to pond, livestock sty (pigs or poultry), both human access point and livestock sty, and water connection to canal. In total, 5392 snails were collected. Percentages of snails with parapleurolophocercous cercariae varied between 6% in areas categorized as low-risk and areas with livestock sty only to 15% in areas with both human access point and livestock sty; only this 15% was significantly different from the prevalence in the low-risk category. Percentages of snails with xiphidio cercariae did not differ between risk-categories and varied between 5% and 10%. Mean snail size was 15.2mm, and was significantly associated with both the probability of infection as well as parasite burden. Very small differences in parasite burden were found at different land use areas; the maximum difference was about 11 cercariae. This study demonstrated only small differences between areas surrounding a pond on risk of snails to be infected with fish-borne trematodes within different pond areas. In field studies on FZTs in M. tuberculata snails in ponds

  15. Soil parameters are key factors to predict metal bioavailability to snails based on chemical extractant data

    Energy Technology Data Exchange (ETDEWEB)

    Pauget, B.; Gimbert, F., E-mail: frederic.gimbert@univ-fcomte.fr; Scheifler, R.; Coeurdassier, M.; Vaufleury, A. de

    2012-08-01

    Although soil characteristics modulate metal mobility and bioavailability to organisms, they are often ignored in the risk assessment of metal transfer. This paper aims to determine the ability of chemical methods to assess and predict cadmium (Cd), lead (Pb) and zinc (Zn) environmental bioavailability to the land snail Cantareus aspersus. Snails were exposed in the laboratory for 28 days to 17 soils from around a former smelter. The soils were selected for their range of pH, organic matter, clay content, and Cd, Pb and Zn concentrations. The influence of soil properties on environmental availability (estimated using HF-HClO{sub 4}, EDTA, CaCl{sub 2}, NH{sub 4}NO{sub 3}, NaNO{sub 3}, free ion activity and total dissolved metal concentration in soil solution) and on environmental bioavailability (modelled using accumulation kinetics) was identified. Among the seven chemical methods, only the EDTA and the total soil concentration can be used to assess Cd and Pb environmental bioavailability to snails (r Superscript-Two {sub adj} = 0.67 and 0.77, respectively). For Zn, none of the chemical methods were suitable. Taking into account the influence of the soil characteristics (pH and CEC) allows a better prediction of Cd and Pb environmental bioavailability (r Superscript-Two {sub adj} = 0.82 and 0.83, respectively). Even though alone none of the chemical methods tested could assess Zn environmental bioavailability to snails, the addition of pH, iron and aluminium oxides allowed the variation of assimilation fluxes to be predicted. A conceptual and practical method to use soil characteristics for risk assessment is proposed based on these results. We conclude that as yet there is no universal chemical method to predict metal environmental bioavailability to snails, and that the soil factors having the greatest impact depend on the metal considered. - Highlights: Black-Right-Pointing-Pointer New approach to identify chemical methods able to predict metal bioavailability

  16. Investigations into the mechanism of lead toxicity to the freshwater pulmonate snail, Lymnaea stagnalis.

    Science.gov (United States)

    Brix, Kevin V; Esbaugh, Andrew J; Munley, Kathleen M; Grosell, Martin

    2012-01-15

    The freshwater pulmonate snail, Lymnaea stagnalis, is the most sensitive aquatic organism tested to date for Pb with an estimated EC20 for juvenile snail growth of 3 μg l⁻¹. A previous study supported the hypothesis that this hypersensitivity to Pb was due to an extremely high Ca²⁺ uptake rate needed to support shell formation. The current study sought to build upon this working hypothesis and develop a mechanistic predictive model for inhibition of snail growth as a function of Pb exposure. Initial experiments confirmed previous predictions that juvenile snails have net Ca²⁺ uptake rates of 7000-8000 nmol g⁻¹ h⁻¹, approximately 100-fold higher than observed in a typical freshwater fish. However, an initial time course study revealed that the onset of growth inhibition occurs at least 4d prior to inhibition of net Ca²⁺ flux in Pb-exposed snails indicating the latter is not the primary mechanism of action. Qualitative observations during this experiment indicated snail feeding was inhibited in a dose-dependent manner. A subsequent experiment demonstrated that when food is withheld from snails for even 24 h, net Ca²⁺ uptake is significantly (∼50%) reduced. A second time course study demonstrated quantitatively that snail feeding is inhibited by Pb exposure by up to 98% at relatively high Pb concentrations (57 μg l⁻¹) but no inhibition was observed at ≤ 10 μg l⁻¹ Pb indicating feeding inhibition is not causing observed growth effects at concentrations approximating the EC20 of 3 μg l⁻¹ Pb. A final experiment testing whether Pb-induced growth effects are related to inhibition of carbonic anhydrase activity in the snail mantle also failed to demonstrate an effect. We conclude that while both feeding and net Ca²⁺ uptake in snails are affected by Pb exposure, they appear to be secondary effects. The primary mechanism of action explaining L. stagnalis hypersensitivity to Pb remains to be identified. Copyright © 2011 Elsevier B

  17. Release of lungworm larvae from snails in the environment: potential for alternative transmission pathways.

    Directory of Open Access Journals (Sweden)

    Alessio Giannelli

    2015-04-01

    Full Text Available Gastropod-borne parasites may cause debilitating clinical conditions in animals and humans following the consumption of infected intermediate or paratenic hosts. However, the ingestion of fresh vegetables contaminated by snail mucus and/or water has also been proposed as a source of the infection for some zoonotic metastrongyloids (e.g., Angiostrongylus cantonensis. In the meantime, the feline lungworms Aelurostrongylus abstrusus and Troglostrongylus brevior are increasingly spreading among cat populations, along with their gastropod intermediate hosts. The aim of this study was to assess the potential of alternative transmission pathways for A. abstrusus and T. brevior L3 via the mucus of infected Helix aspersa snails and the water where gastropods died. In addition, the histological examination of snail specimens provided information on the larval localization and inflammatory reactions in the intermediate host.Twenty-four specimens of H. aspersa received ~500 L1 of A. abstrusus and T. brevior, and were assigned to six study groups. Snails were subjected to different mechanical and chemical stimuli throughout 20 days in order to elicit the production of mucus. At the end of the study, gastropods were submerged in tap water and the sediment was observed for lungworm larvae for three consecutive days. Finally, snails were artificially digested and recovered larvae were counted and morphologically and molecularly identified. The anatomical localization of A. abstrusus and T. brevior larvae within snail tissues was investigated by histology. L3 were detected in the snail mucus (i.e., 37 A. abstrusus and 19 T. brevior and in the sediment of submerged specimens (172 A. abstrusus and 39 T. brevior. Following the artificial digestion of H. aspersa snails, a mean number of 127.8 A. abstrusus and 60.3 T. brevior larvae were recovered. The number of snail sections positive for A. abstrusus was higher than those for T. brevior.Results of this study

  18. Programming macro tree transducers

    DEFF Research Database (Denmark)

    Bahr, Patrick; Day, Laurence E.

    2013-01-01

    A tree transducer is a set of mutually recursive functions transforming an input tree into an output tree. Macro tree transducers extend this recursion scheme by allowing each function to be defined in terms of an arbitrary number of accumulation parameters. In this paper, we show how macro tree...... transducers can be concisely represented in Haskell, and demonstrate the benefits of utilising such an approach with a number of examples. In particular, tree transducers afford a modular programming style as they can be easily composed and manipulated. Our Haskell representation generalises the original...... definition of (macro) tree transducers, abolishing a restriction on finite state spaces. However, as we demonstrate, this generalisation does not affect compositionality....

  19. Programming macro tree transducers

    DEFF Research Database (Denmark)

    Bahr, Patrick; Day, Laurence E.

    2013-01-01

    A tree transducer is a set of mutually recursive functions transforming an input tree into an output tree. Macro tree transducers extend this recursion scheme by allowing each function to be defined in terms of an arbitrary number of accumulation parameters. In this paper, we show how macro tree...... transducers can be concisely represented in Haskell, and demonstrate the benefits of utilising such an approach with a number of examples. In particular, tree transducers afford a modular programming style as they can be easily composed and manipulated. Our Haskell representation generalises the original...... definition of (macro) tree transducers, abolishing a restriction on finite state spaces. However, as we demonstrate, this generalisation does not affect compositionality....

  20. Chlorophyllin Bait Formulation and Exposure to Different Spectrum of Visible Light on the Reproduction of Infected/Uninfected Snail Lymnaea acuminata

    Directory of Open Access Journals (Sweden)

    Navneet Kumar

    2016-01-01

    Full Text Available Fasciolosis is a waterborne disease, caused by Fasciola species. Snail Lymnaea acuminata is an intermediate host of these flukes. Control of snail population is major tool in reducing the incidences. Variation in light intensity and wavelength caused significant changes in reproduction pattern of snails. Maximum fecundity was noted with bait containing carbohydrate (starch, 468 ± 0.10/20 snails or amino acid (serine, 319 ± 0.29/20 snails as attractant. Sublethal feeding of chlorophyllin bait with starch or serine attractant to infected and uninfected snails caused significant reduction in fecundity, hatchability, and survivability. These significant changes are observed in snails exposed to different spectral band of visible light and sunlight. Maximum fecundity of 536 ± 2.0 and minimum of 89.3 ± 0.4 were noted in snails not fed with bait and exposed to sunlight and red spectral band, respectively. There was complete arrest in the fecundity of infected and uninfected snails and no survivability of uninfected snails after 48 h feeding with bait containing chlorophyllin + attractant. Minimum hatchability (9.25 ± 0.5 was noted in red light exposed, chlorophyllin + starch fed infected snails and hatching period of bait fed snails was prolonged. Conclusively, chlorophyllin bait and red light reduce reproduction capacity in snails.

  1. Chlorophyllin Bait Formulation and Exposure to Different Spectrum of Visible Light on the Reproduction of Infected/Uninfected Snail Lymnaea acuminata.

    Science.gov (United States)

    Kumar, Navneet; Singh, D K; Singh, Vinay Kumar

    2016-01-01

    Fasciolosis is a waterborne disease, caused by Fasciola species. Snail Lymnaea acuminata is an intermediate host of these flukes. Control of snail population is major tool in reducing the incidences. Variation in light intensity and wavelength caused significant changes in reproduction pattern of snails. Maximum fecundity was noted with bait containing carbohydrate (starch, 468 ± 0.10/20 snails) or amino acid (serine, 319 ± 0.29/20 snails) as attractant. Sublethal feeding of chlorophyllin bait with starch or serine attractant to infected and uninfected snails caused significant reduction in fecundity, hatchability, and survivability. These significant changes are observed in snails exposed to different spectral band of visible light and sunlight. Maximum fecundity of 536 ± 2.0 and minimum of 89.3 ± 0.4 were noted in snails not fed with bait and exposed to sunlight and red spectral band, respectively. There was complete arrest in the fecundity of infected and uninfected snails and no survivability of uninfected snails after 48 h feeding with bait containing chlorophyllin + attractant. Minimum hatchability (9.25 ± 0.5) was noted in red light exposed, chlorophyllin + starch fed infected snails and hatching period of bait fed snails was prolonged. Conclusively, chlorophyllin bait and red light reduce reproduction capacity in snails.

  2. Chlorophyllin Bait Formulation and Exposure to Different Spectrum of Visible Light on the Reproduction of Infected/Uninfected Snail Lymnaea acuminata

    Science.gov (United States)

    Kumar, Navneet; Singh, D. K.; Singh, Vinay Kumar

    2016-01-01

    Fasciolosis is a waterborne disease, caused by Fasciola species. Snail Lymnaea acuminata is an intermediate host of these flukes. Control of snail population is major tool in reducing the incidences. Variation in light intensity and wavelength caused significant changes in reproduction pattern of snails. Maximum fecundity was noted with bait containing carbohydrate (starch, 468 ± 0.10/20 snails) or amino acid (serine, 319 ± 0.29/20 snails) as attractant. Sublethal feeding of chlorophyllin bait with starch or serine attractant to infected and uninfected snails caused significant reduction in fecundity, hatchability, and survivability. These significant changes are observed in snails exposed to different spectral band of visible light and sunlight. Maximum fecundity of 536 ± 2.0 and minimum of 89.3 ± 0.4 were noted in snails not fed with bait and exposed to sunlight and red spectral band, respectively. There was complete arrest in the fecundity of infected and uninfected snails and no survivability of uninfected snails after 48 h feeding with bait containing chlorophyllin + attractant. Minimum hatchability (9.25 ± 0.5) was noted in red light exposed, chlorophyllin + starch fed infected snails and hatching period of bait fed snails was prolonged. Conclusively, chlorophyllin bait and red light reduce reproduction capacity in snails. PMID:26925296

  3. Habitat characteristics for different freshwater snail species as determined biologically through macroinvertebrate information.

    Science.gov (United States)

    El-Khayat, Hanaa M M; Mahmoud, Kadria M A; Mostafa, Bayomy B; Tantawy, Ahmad A; El-Deeb, Fatma A; Ragb, Fawzy M; Ismail, Nahed M; El-Said, Kalil M; Taleb, Hoda M Abu

    2011-12-01

    Macro-invertebrates including freshwater snails collected from 643 sites over 8 successive seasons among the River Nile, branches, main canals and certain drains in eight Egyptian Governorates. Thirteen snail species and one bivalve species were identified. The most distributed were Lanistus carinatus and Physa acuta while the most abundant were Cleopatra bulimoides and Physa acuta during the whole study. The sites that harbored each snail species in all the examined water-courses were grouped seasonally and their biological assessment was determined by their minimum and maximum total point similarity percentage to that of the corresponded reference site and mean of the total points. Habitats for most snail species attained minimum total point's similarity percentage less than 21% (very poor habitat) during autumn and winter then spring while during summer very poor habitat was harbored by only few snail species. P. acuta was the only survived snails in habitat which attained 0 as a minimum total point's similarity percentage during two seasons and L. carinatus and Succinea cleopatra during one season. With respect to medically important snails very poor sites constituted 23% of Biomphalaria alexandrina sites, 14% of Lymnaea natalensis and 9.4% of Bulinus truncatus sites. The studied macroinvertebrate matrices, total number of organisms, taxa richness, the Ephemeroptera, Plecoptera, and Trichoptera (EPT) index, ratio of EPT index to chironomidae, ratio of scraper to filtering collector, contribution of dominant macroinvertebrate major group, comparison revealed descending tolerances from B. alexanrina followed by L. natalensis then B. truncates, but Hilsenhoff Biotic Index (HBI) showed the same tolerance to organic pollution.

  4. Thermal tolerance and climate warming sensitivity in tropical snails.

    Science.gov (United States)

    Marshall, David J; Rezende, Enrico L; Baharuddin, Nursalwa; Choi, Francis; Helmuth, Brian

    2015-12-01

    Tropical ectotherms are predicted to be especially vulnerable to climate change because their thermal tolerance limits generally lie close to current maximum air temperatures. This prediction derives primarily from studies on insects and lizards and remains untested for other taxa with contrasting ecologies. We studied the HCT (heat coma temperatures) and ULT (upper lethal temperatures) of 40 species of tropical eulittoral snails (Littorinidae and Neritidae) inhabiting exposed rocky shores and shaded mangrove forests in Oceania, Africa, Asia and North America. We also estimated extremes in animal body temperature at each site using a simple heat budget model and historical (20 years) air temperature and solar radiation data. Phylogenetic analyses suggest that HCT and ULT exhibit limited adaptive variation across habitats (mangroves vs. rocky shores) or geographic locations despite their contrasting thermal regimes. Instead, the elevated heat tolerance of these species (HCT = 44.5 ± 1.8°C and ULT = 52.1 ± 2.2°C) seems to reflect the extreme temperature variability of intertidal systems. Sensitivity to climate warming, which was quantified as the difference between HCT or ULT and maximum body temperature, differed greatly between snails from sunny (rocky shore; Thermal Safety Margin, TSM = -14.8 ± 3.3°C and -6.2 ± 4.4°C for HCT and ULT, respectively) and shaded (mangrove) habitats (TSM = 5.1 ± 3.6°C and 12.5 ± 3.6°C). Negative TSMs in rocky shore animals suggest that mortality is likely ameliorated during extreme climatic events by behavioral thermoregulation. Given the low variability in heat tolerance across species, habitat and geographic location account for most of the variation in TSM and may adequately predict the vulnerability to climate change. These findings caution against generalizations on the impact of global warming across ectothermic taxa and highlight how the consideration of nonmodel animals, ecological transitions

  5. Pattern Avoidance in Ternary Trees

    CERN Document Server

    Gabriel, Nathan; Pudwell, Lara; Tay, Samuel

    2011-01-01

    This paper considers the enumeration of ternary trees (i.e. rooted ordered trees in which each vertex has 0 or 3 children) avoiding a contiguous ternary tree pattern. We begin by finding recurrence relations for several simple tree patterns; then, for more complex trees, we compute generating functions by extending a known algorithm for pattern-avoiding binary trees. Next, we present an alternate one-dimensional notation for trees which we use to find bijections that explain why certain pairs of tree patterns yield the same avoidance generating function. Finally, we compare our bijections to known "replacement rules" for binary trees and generalize these bijections to a larger class of trees.

  6. Influence of water quality on zinc toxicity to the Florida apple snail (Pomacea paludosa) and sensitivity of freshwater snails to zinc.

    Science.gov (United States)

    Hoang, Tham C; Tong, Xin

    2015-03-01

    The present study characterized the influence of water-quality characteristics on zinc (Zn) toxicity to the Florida apple snail (Pomacea paludosa) and the sensitivity of freshwater snails to Zn. Standard 96-h renewal acute toxicity tests were conducted with Zn and juvenile P. paludosa under 3 conditions of pH and alkalinity, water hardness, and dissolved organic carbon (DOC). Median lethal effect concentrations (96-h LC50s), no-observed- effect concentrations, lowest-observed-effect concentrations, LC10s, and LC20s were determined for each test. The results showed that Zn toxicity to P. paludosa decreased linearly with increasing hardness, pH, and DOC. A multiple linear regression model based on pH, hardness, and DOC was able to explain 99% of the observed variability in LC50s. These results are useful for the development of a biotic ligand model (BLM) for P. paludosa and Zn. Zinc acute toxicity data were collected from the literature for 12 freshwater snail species in a wide range of water-quality characteristics for species sensitivity distribution analysis. The results showed that P. paludosa is the second most sensitive to Zn. The present study also suggested that aqueous ZnCO3 and ZnHCO3 (-) can be bioavailable to P. paludosa. Therefore, bioavailability models (e.g., BLM) should take these Zn species into consideration for bioavailability when applied to snails.

  7. The Compton hump and variable blue wing in the extreme low-flux NuSTAR observations of 1H0707-495

    Science.gov (United States)

    Kara, E.; Fabian, A. C.; Lohfink, A. M.; Parker, M. L.; Walton, D. J.; Boggs, S. E.; Christensen, F. E.; Hailey, C. J.; Harrison, F. A.; Matt, G.; Reynolds, C. S.; Stern, D.; Zhang, W. W.

    2015-05-01

    The narrow-line Seyfert I galaxy, 1H0707-495, has been well observed in the 0.3-10 keV band, revealing a dramatic drop in flux in the iron Kα band, a strong soft excess, and short time-scale reverberation lags associated with these spectral features. In this paper, we present the first results of a deep 250-ks NuSTAR (Nuclear Spectroscopic Telescope Array) observation of 1H0707-495, which includes the first sensitive observations above 10 keV. Even though the NuSTAR observations caught the source in an extreme low-flux state, the Compton hump is still significantly detected. NuSTAR, with its high effective area above 7 keV, clearly detects the drop in flux in the iron Kα band, and by comparing these observations with archival XMM-Newton observations, we find that the energy of this drop increases with increasing flux. We discuss possible explanations for this, the most likely of which is that the drop in flux is the blue wing of the relativistically broadened iron Kα emission line. When the flux is low, the coronal source height is low, thus enhancing the most gravitationally redshifted emission.

  8. Iron K and Compton hump reverberation in SWIFT J2127.4+5654 and NGC 1365 revealed by NuSTAR and XMM-Newton

    CERN Document Server

    Kara, E; Marinucci, A; Walton, D J; Fabian, A C; Risaliti, G; Boggs, S E; Christensen, F E; Fuerst, F; Hailey, C J; Harrison, F A; Matt, G; Parker, M L; Reynolds, C S; Stern, D; Zhang, W W

    2014-01-01

    In the past five years, a flurry of X-ray reverberation lag measurements of accreting supermassive black holes have been made using the XMM-Newton telescope in the 0.3-10 keV energy range. In this work, we use the NuSTAR telescope to extend the lag analysis up to higher energies for two Seyfert galaxies, SWIFT J2127.4+5654 and NGC 1365. X-ray reverberation lags are due to the light travel time delays between the direct continuum emission and the reprocessed emission from the inner radii of an ionised accretion disc. XMM-Newton has been particularly adept at measuring the lag associated with the broad Fe K emission line, where the gravitationally redshifted wing of the line is observed to respond before the line centroid at 6.4 keV, produced at larger radii. Now we use NuSTAR to probe the lag at higher energies, where the spectrum shows clear evidence for Compton reflection, known as the Compton 'hump'. The XMM-Newton data show Fe K lags in both SWIFT J2127.4+5654 and NGC 1365. The NuSTAR data provide independ...

  9. Snail Promotes Epithelial Mesenchymal Transition in Breast Cancer Cells in Part via Activation of Nuclear ERK2

    Science.gov (United States)

    Smith, Bethany N.; Burton, Liza J.; Henderson, Veronica; Randle, Diandra D.; Morton, Derrick J.; Smith, Basil A.; Taliaferro-Smith, Latonia; Nagappan, Peri; Yates, Clayton; Zayzafoon, Majd; Chung, Leland W. K.; Odero-Marah, Valerie A.

    2014-01-01

    Snail transcription factor is up-regulated in several cancers and associated with increased tumor migration and invasion via induction of epithelial-to-mesenchymal transition (EMT). MAPK (ERK1/2) signaling regulates cellular processes including cell motility, adhesion, and invasion. We investigated the regulation of ERK1/2 by Snail in breast cancer cells. ERK1/2 activity (p-ERK) was higher in breast cancer patient tissue as compared to normal tissue. Snail and p-ERK were increased in several breast cancer cell lines as compared to normal mammary epithelial cells. Snail knockdown in MDA-MB-231 and T47-D breast cancer cells decreased or re-localized p-ERK from the nuclear compartment to the cytoplasm. Snail overexpression in MCF-7 breast cancer cells induced EMT, increased cell migration, decreased cell adhesion and also increased tumorigenicity. Snail induced nuclear translocation of p-ERK, and the activation of its subcellular downstream effector, Elk-1. Inhibiting MAPK activity with UO126 or knockdown of ERK2 isoform with siRNA in MCF-7 Snail cells reverted EMT induced by Snail as shown by decreased Snail and vimentin expression, decreased cell migration and increased cell adhesion. Overall, our data suggest that ERK2 isoform activation by Snail in aggressive breast cancer cells leads to EMT associated with increased cell migration and decreased cell adhesion. This regulation is enhanced by positive feedback regulation of Snail by ERK2. Therefore, therapeutic targeting of ERK2 isoform may be beneficial for breast cancer. PMID:25122124

  10. Snail promotes epithelial mesenchymal transition in breast cancer cells in part via activation of nuclear ERK2.

    Directory of Open Access Journals (Sweden)

    Bethany N Smith

    Full Text Available Snail transcription factor is up-regulated in several cancers and associated with increased tumor migration and invasion via induction of epithelial-to-mesenchymal transition (EMT. MAPK (ERK1/2 signaling regulates cellular processes including cell motility, adhesion, and invasion. We investigated the regulation of ERK1/2 by Snail in breast cancer cells. ERK1/2 activity (p-ERK was higher in breast cancer patient tissue as compared to normal tissue. Snail and p-ERK were increased in several breast cancer cell lines as compared to normal mammary epithelial cells. Snail knockdown in MDA-MB-231 and T47-D breast cancer cells decreased or re-localized p-ERK from the nuclear compartment to the cytoplasm. Snail overexpression in MCF-7 breast cancer cells induced EMT, increased cell migration, decreased cell adhesion and also increased tumorigenicity. Snail induced nuclear translocation of p-ERK, and the activation of its subcellular downstream effector, Elk-1. Inhibiting MAPK activity with UO126 or knockdown of ERK2 isoform with siRNA in MCF-7 Snail cells reverted EMT induced by Snail as shown by decreased Snail and vimentin expression, decreased cell migration and increased cell adhesion. Overall, our data suggest that ERK2 isoform activation by Snail in aggressive breast cancer cells leads to EMT associated with increased cell migration and decreased cell adhesion. This regulation is enhanced by positive feedback regulation of Snail by ERK2. Therefore, therapeutic targeting of ERK2 isoform may be beneficial for breast cancer.

  11. Snail,E-cadherin 在胃癌中的表达及意义%Expression and Significance of Snail and E-cadherin in Gastric Cancer

    Institute of Scientific and Technical Information of China (English)

    曹晓丽; 杜圣英; 李登欣; 张晴

    2013-01-01

    Objective To investigate the expression of Snail and E-cadherin protein in gastric cancer and explore their significance.Methods The expression of Snail and E-cadherin protein was detected by immunohistochemi-cal SP method in 45 cases of gastric carcinoma tissue and 20 cases of para-cancerous normal gastric tissue.Results The positive rate of Snail immunostaining in gastric carcinoma was higher than that in adjacent normal gastric tissue (P<0. 05),the positive rate of E-cadherin immunostaining in gastric cancer was lower than that in adjacent normal gastric tissue (P<0.05).The expression of Snail and E-cadherin in gastric carcinoma tissue was closely related with the depth of tumor invasion,differentiatial degree,clinical stage,lymph node metastases and distant metastases (P<0.05).There was negative correlation between the expression of Snail and E-cadherin protein in gastric carcinoma(P<0.05).Conclusion The abnormal expression of Snail and E-cadherin might be important biological markers for malignant transformation , invasion and metastasis of gastric carcinoma .Co-detection of Snail and E-cadherin has significant effect on predicting the degree of malignancy and prognosis of gastric cancer .%  目的观察锌指结合蛋白(Snail)和上皮性钙粘附蛋白E-cadherin在胃癌组织中的表达,并探讨其意义.方法采用免疫组化SP法检测45例胃癌患者肿瘤组织和20例癌旁正常胃组织中Snail,E-cadherin蛋白的表达.结果胃癌组织中Snail阳性表达率明显高于癌旁正常胃组织(P<0.05),胃癌组织中E-cadherin阳性表达率显著低于癌旁正常胃组织(P<0.05);Snail和E-cad表达均与胃癌的分化程度、浸润深度、临床分期、淋巴结转移、是否有远处器官转移密切相关(P<0.05);Snail与E-cadherin在胃癌组织中的表达呈显著负相关(P<0.05).结论 Snail,E-cadherin的异常表达可能是胃黏膜发生恶性转变及胃癌发生侵袭转移的重要生物学标志,联合检测两

  12. Bayesian Rose Trees

    CERN Document Server

    Blundell, Charles; Heller, Katherine A

    2012-01-01

    Hierarchical structure is ubiquitous in data across many domains. There are many hier- archical clustering methods, frequently used by domain experts, which strive to discover this structure. However, most of these meth- ods limit discoverable hierarchies to those with binary branching structure. This lim- itation, while computationally convenient, is often undesirable. In this paper we ex- plore a Bayesian hierarchical clustering algo- rithm that can produce trees with arbitrary branching structure at each node, known as rose trees. We interpret these trees as mixtures over partitions of a data set, and use a computationally efficient, greedy ag- glomerative algorithm to find the rose trees which have high marginal likelihood given the data. Lastly, we perform experiments which demonstrate that rose trees are better models of data than the typical binary trees returned by other hierarchical clustering algorithms.

  13. Local adaptation along a continuous coastline: prey recruitment drives differentiation in a predatory snail.

    Science.gov (United States)

    Sanford, Eric; Worth, David J

    2010-03-01

    Recent work demonstrates that nearshore oceanography can generate strong variation in the delivery of resources (nutrients and larvae) to benthic marine communities over spatial scales of tens to hundreds of kilometers. Moreover, variation in the strength of these bottom-up inputs is often spatially consistent, linked to regional centers of upwelling, coastal topography, and other stable features of the coastline. Whereas the ecological effects of these oceanographic links are increasingly clear, the possibility that these same bottom-up forces might impose spatially varying selection on consumers has not been addressed. Here, we test the hypothesis that a carnivorous snail (Nucella canaliculata) with direct development is locally adapted to persistent differences in prey recruitment within two adjacent oceanographic regions (northern California and Oregon, USA). Previous laboratory studies demonstrated that snails from Oregon rarely drilled the thick-shelled mussel Mytilus californianus, whereas snails from California readily drilled this prey. To test whether these differences reflect local adaptation, snails from two populations in each region were raised through two laboratory generations to minimize the potential influence of nongenetic effects. We then reciprocally outplanted these F2 generation snails to field enclosures at each of the four sites and monitored their growth for 11 months. Recruitment and availability of preferred prey (the acorn barnacle Balanus glandula and blue mussel Mytilus trossulus) at the experimental sites were 1-3 orders of magnitude lower in California than in Oregon. At the California sites, snails that originated from Oregon sources failed to drill larger M. californianus, encountered few alternative prey, and showed almost no growth. In contrast, snails from California drilled M. californianus and showed substantial growth. These results strongly suggest that the capacity of California snails to drill M. californianus allows

  14. Calcium-activated potassium conductance noise in snail neurons.

    Science.gov (United States)

    Westerfield, M; Lux, H D

    1982-11-01

    Current fluctuations were measured in small, 3-6 micrometers-diameter patches of soma membrane in bursting neurons of the snail, Helix pomatia. The fluctuations dramatically increased in magnitude with depolarization of the membrane potential under voltage clamp conditions. Two components of conductance noise were identified in the power spectra calculated from the membrane currents. One component had a corner frequency which increased with depolarization. This component was blocked by intracellular injection of TEA and was relatively insensitive to extracellular calcium levels (as long as the total number of effective divalent cations remained constant). It was identified as fluctuations of the voltage-dependent component of delayed outward current. The second component of conductance noise had a corner frequency which decreased with depolarization. It was relatively unaffected by TEA injection and was reversibly blocked by substitution of extracellular calcium with magnesium, cobalt, or nickel. This second component of noise was identified as fluctuations of the calcium-dependent potassium current. The results suggest that the two components of delayed outward current are conducted through physically distinct channels.

  15. Angiostrongylus infections in rats and snails in northeast Thailand.

    Science.gov (United States)

    Pipitgool, V; Sithithaworn, P; Pongmuttasaya, P; Hinz, E

    1997-01-01

    A survey of Angiostrongylus infections in rats and snails was carried out in the provinces of Ubon Ratchathani, Udon Thani. Kalasin, Chaiyaphum and Khon Kaen in northeast Thailand. Only two Rattus norvegicus (3.8%) and one Bandicota indica (1.4%) out of 151 R. rattus, 52 R. norvegicus and 69 B. indica examined were infected with adult lung worms. All worms recovered were A. cantonensis. Prevalence of infection in 423 Pila polita was 0.9% while all of 77 P. ampullacea were negative for larvae. In contrast to this 36.4% of 500 Achatina fulica harbored L3 of Angiostrongylus (with variations of between 29% and 46% in the five provinces). The average infection intensity in A. fulica was 13.6 L3 (1 to 441). Experimental infection of Wistar rats with L3 (isolated from A. fulica resulted in a recovery rate of 48.3% of adult worms of which 91.7% and 8.3% were identified as A. cantonensis and A. malaysiensis, respectively. This is the first proven finding of A. malaysiensis in northeast Thailand.

  16. Toxicity of Metals to a Freshwater Snail, Melanoides tuberculata

    Directory of Open Access Journals (Sweden)

    M. Shuhaimi-Othman

    2012-01-01

    Full Text Available Adult freshwater snails Melanoides tuberculata (Gastropod, Thiaridae were exposed for a four-day period in laboratory conditions to a range of copper (Cu, cadmium (Cd, zinc (Zn, lead (Pb, nickel (Ni, iron (Fe, aluminium (Al, and manganese (Mn concentrations. Mortality was assessed and median lethal times (LT50 and concentrations (LC50 were calculated. LT50 and LC50 increased with the decrease in mean exposure concentrations and times, respectively, for all metals. The LC50 values for the 96-hour exposures to Cu, Cd, Zn, Pb, Ni, Fe, Al, and Mn were 0.14, 1.49, 3.90, 6.82, 8.46, 8.49, 68.23, and 45.59 mg L−1, respectively. Cu was the most toxic metal to M. tuberculata, followed by Cd, Zn, Pb, Ni, Fe, Mn, and Al (Cu > Cd > Zn > Pb > Ni > Fe > Mn > Al. Metals bioconcentration in M. tuberculata increases with exposure to increasing concentrations and Cu has the highest accumulation (concentration factor in the soft tissues. A comparison of LC50 values for metals for this species with those for other freshwater gastropods reveals that M. tuberculata is equally sensitive to metals.

  17. The valuative tree

    CERN Document Server

    Favre, Charles

    2004-01-01

    This volume is devoted to a beautiful object, called the valuative tree and designed as a powerful tool for the study of singularities in two complex dimensions. Its intricate yet manageable structure can be analyzed by both algebraic and geometric means. Many types of singularities, including those of curves, ideals, and plurisubharmonic functions, can be encoded in terms of positive measures on the valuative tree. The construction of these measures uses a natural tree Laplace operator of independent interest.

  18. Comparison of galled trees.

    Science.gov (United States)

    Cardona, Gabriel; Llabrés, Mercè; Rosselló, Francesc; Valiente, Gabriel

    2011-01-01

    Galled trees, directed acyclic graphs that model evolutionary histories with isolated hybridization events, have become very popular due to both their biological significance and the existence of polynomial-time algorithms for their reconstruction. In this paper, we establish to which extent several distance measures for the comparison of evolutionary networks are metrics for galled trees, and hence, when they can be safely used to evaluate galled tree reconstruction methods.

  19. Dynamic of population-dynamics in a medically important snail species Lymnaea (Radix Luteola (Lamarck

    Directory of Open Access Journals (Sweden)

    T. K. Misra

    1993-09-01

    Full Text Available The life-cycle parameters of the snail Lymnaea (Radix luteola and the factors influencing the same have been studied under laboratory conditions. Ins each month, from July 1990 to June 1991, a batch of 100 zero-day old individual were considered for studies. The snails of April batch survived for 19.42 days while those in December batch survived for 87.45 days. The May batch individual though survived for 65.67 days gained maximum shell size (15.84 mm in length and body weight (419.87 mg. All individuals of April batch died prior to attainment of sexual maturity. In the remaining 11 batches the snails became sexually mature between 32 and 53 days. At this stage, they were with varying shell lengths, 9.3 mm to 13,11 mm in respect to batches. The reproduction period varied from 1-67 days. An individual laid, on an average, 0,25 (March batch to 443.67 (May batch eggs in its life-span. A batch of such snails would leave 24312, 22520, 720268, 80408, 76067, 418165, 214, 9202, 0, 0, 2459386 and 127894 individuals at the end of 352nd day. Since the environmental conditions were almost similar the 'dynamic' of population dynamics seems to be involved with the 'strain' of the snail individuals of the batches concerned.

  20. Genetic variation between Biomphalaria alexandrina snails susceptible and resistant to Schistosoma mansoni infection.

    Science.gov (United States)

    El-Nassery, Suzanne M F; Abou-El-Naga, Iman F; Allam, Sonia R; Shaat, Eman A; Mady, Rasha F M

    2013-01-01

    Much effort has been made to control schistosomiasis infection in Egypt. However, enduring effects from such strategies have not yet been achieved. In this study, we sought to determine the genetic variability related to the interaction between Biomphalaria alexandrina snails and Schistosoma mansoni. Using RAPD-PCR with eight (10 mers) random primers, we were able to determine the polymorphic markers that differed between snails susceptible and resistant to Schistosoma mansoni infection using five primers out of the eight. Our results suggest that the RAPD-PCR technique is an efficient means by which to compare genomes and to detect genetic variations between schistosomiasis intermediate hosts. The RAPD technique with the above-noted primers can identify genomic markers that are specifically related to the Biomphalaria alexandrina/Schistosoma mansoni relationship in the absence of specific nucleotide sequence information. This approach could be used in epidemiologic surveys to investigate genetic diversity among Biomphalaria alexandrina snails. The ability to determine resistant markers in Biomphalaria alexandrina snails could potentially lead to further studies that use refractory snails as agents to control the spread of schistosomiasis.

  1. Heat shock proteins and survival strategies in congeneric land snails (Sphincterochila) from different habitats.

    Science.gov (United States)

    Mizrahi, Tal; Heller, Joseph; Goldenberg, Shoshana; Arad, Zeev

    2012-09-01

    Polmunate land snails are subject to stress conditions in their terrestrial habitat, and depend on a range of behavioural, physiological and biochemical adaptations for coping with problems of maintaining water, ionic and thermal balance. The involvement of the heat shock protein (HSP) machinery in land snails was demonstrated following short-term experimental aestivation and heat stress, suggesting that land snails use HSPs as part of their survival strategy. As climatic variation was found to be associated with HSP expression, we tested whether adaptation of land snails to different habitats affects HSP expression in two closely related Sphincterochila snail species, a desert species Sphincterochila zonata and a Mediterranean-type species Sphincterochila cariosa. Our study suggests that Sphincterochila species use HSPs as part of their survival strategy following desiccation and heat stress, and as part of the natural annual cycle of activity and aestivation. Our studies also indicate that adaptation to different habitats results in the development of distinct strategies of HSP expression in response to stress, namely the reduced expression of HSPs in the desert-inhabiting species. We suggest that these different strategies reflect the difference in heat and aridity encountered in the natural habitats, and that the desert species S. zonata relies on mechanisms and adaptations other than HSP induction thus avoiding the fitness consequences of continuous HSP upregulation.

  2. NUTRITIONAL VALUE OF CHICKEN OFFAL AS REPLACEMENT FOR LOCAL FISH MEAL IN GROWING SNAILS

    Directory of Open Access Journals (Sweden)

    A OMOLE

    2009-03-01

    Full Text Available A total of ninety six growing snails of mean weight 91.23±2.4g were used to determine the effects of partial or total replacement of local fish meal, a source of protein but expensive to a less expensive, alternative source, chicken offal in the diet of growing snails. Completely randomized design was used for the study. The feeding trial had four treatments, C1, C2, C3 and C4 in which fish meal fraction of the diets was replaced at 0, 50, 75 and 100% with chicken offal respectively. The parameters taken were weight gain, feed intake. Feed conversion ratio, total feed cost, and cost per weight gain were calculated. The trial lasted for twelve weeks. Significant differences were not observed in the mean weekly feed intake of the snails in all the treatments. The mean weight gain in all the treatments were not significantly influenced by the inclusion of chicken offal in the diet (P>0.005. Total feed cost and cost/weight gain reduced as the level of the chicken offal increased while the lowest cost/weight gain was observed in C4. The inclusion of Chicken offal in all the diets had no detrimental effect on the snails in all the treatments. Based on the present results chicken offal could replace local fish meal in the diet of growing snail up to 100% and hereby reduce feed cost

  3. Asymmetry of mandibular dentition is associated with dietary specialization in snail-eating snakes

    Science.gov (United States)

    2017-01-01

    Background In vertebrates, the left-and-right pairs of homologous organs are generally present in equal numbers. A remarkable exception is snail-eating snakes in the family Pareidae: almost all the pareid snakes have much more teeth on the right mandible than on the left for functional specialization in feeding on the dextral majority of land snails. Because the only exceptional species with symmetric dentition has been regarded as a slug-eater, the extent of dietary specialization on slugs could shape the degree of the lateral asymmetry of mandibular dentition (dentition asymmetry) even among snail eaters. Methods To test this, I compared the morphology and behavior of two sympatric species of Taiwanese snail-eating snakes, Pareas atayal and P. formosensis. Results Specimens collected in the same locality showed that the dentition asymmetry of P. formosensis was significantly smaller than that of P. atayal. Congruent to its weak asymmetry, P. formosensis showed a strong preference of slugs to snails in the feeding experiment. Discussion The dietary specialization of P. formosensis on slugs would contribute to niche partitioning from the sympatric congener P. atayal. This study suggests that the diverse variation in the dentition asymmetry of pareid snakes is the result of their dietary specialization and divergence. PMID:28265502

  4. An overview of freshwater snails in Asia with main focus on Vietnam.

    Science.gov (United States)

    Madsen, H; Hung, N M

    2014-12-01

    Freshwater snails have received much attention for their role as intermediate hosts for trematodes causing disease in people and animals such as schistosomiasis and various food-borne trematodes. While effective medical treatment exists for some of these diseases there is need for preventive measures to reduce transmission, e.g. control of intermediate hosts because transmission patterns are often complicated due to presence of reservoir final hosts. In order to implement control measures against the intermediate host snails with minimal impact on the freshwater ecosystems and their biodiversity, a profound knowledge on transmission patterns of the trematodes is required and this is partly related to distribution, habitat preferences, and seasonal variation in density of the intermediate host species. Identification of snail species can be problematic on the basis of morphological and anatomical characters alone as some species show morphological plasticity and similarly morphological differentiation of cercariae found in snails may be difficult and this could lead to biased perceptions of intermediate host spectra and transmission patterns. In this paper, we give an overview of the snail families and their medical and veterinary importance in Asia but with main focus on Vietnam.

  5. Diet control on carbon isotopic composition of land snail shell carbonate

    Institute of Scientific and Technical Information of China (English)

    LIU ZongXiu; GU ZhaoYan; WU NaiQin; XU Bing

    2007-01-01

    Carbon isotope compositions for both the carbonate shells and soft bodies (organic tissue) of living land snails collected mostly from the Loess Plateau, China have been measured. The result shows that δ13C values range from -13.1‰ to -4.3‰ for the aragonite shell samples and from -26.8‰ to -18.0‰ for the soft body samples. Although the shells are enriched in 13C relative to the bodies averagely by 14.2(±0.8)‰, the shell δ13Ca values are closely correlated to the body δ13Corg values, expressed as δ13Ca = 1.021 δ13Corg + 14.38 (R = 0.965; N = 31). This relationship indicates that δ13Ca is primarily a function of the isotopic composition of the snail diets since previous studies have proved that the snail body is the same as their food in carbon isotope composition. In other words, carbon isotope compo-sition of the carbonate shell can be used as a proxy to estimate the dietary 13C abundance of the land snails. The data also support that the 13C enrichment of the carbonate shells results mainly from the equilibrium fractionations between the metabolic CO2, HCO3- in the hemolymph and shell aragonite, and partially from kinetic fractionations when snail shells form during their activity.

  6. Effects of Bt-maize material on the life cycle of the land snail Cantareus aspersus

    DEFF Research Database (Denmark)

    Kramarz, Paulina; de Vaufleury, Annette; Gimbert, Frédéric

    2009-01-01

    Insect resistant Bt-maize (MON 810) expresses active Cry1Ab endotoxin derived from Bacillus thuringiensis (Bt). Snails constitute non-target soil species potentially exposed to Bt-toxin through consumption of plant material and soil in fields where transgenic plants have been grown. We studied...... the effect of the Cry1Ab toxin on survival, growth and egg hatchability of the snail Cantareus aspersus. From the age of 4 to 88 weeks, snails were fed either powdered Bt-maize or non-Bt-maize and exposed to soil samples collected after harvesting either the Bt-maize or non-Bt-maize. We applied four...... treatments: non-Bt soil + non-Bt-maize (MM); Bt soil + Bt-maize (BB), non-Bt soil + Bt-maize (MB), Bt soil + non-Bt-maize (BM). Eggs laid by snails not exposed to Bt-toxin were also exposed to the two types of soils (Bt and non-Bt soil). At the end of growth (47 weeks of exposure), snails exposed to Bt...

  7. Molecular Diversity and Gene Evolution of the Venom Arsenal of Terebridae Predatory Marine Snails.

    Science.gov (United States)

    Gorson, Juliette; Ramrattan, Girish; Verdes, Aida; Wright, Elizabeth M; Kantor, Yuri; Rajaram Srinivasan, Ramakrishnan; Musunuri, Raj; Packer, Daniel; Albano, Gabriel; Qiu, Wei-Gang; Holford, Mandë

    2015-05-28

    Venom peptides from predatory organisms are a resource for investigating evolutionary processes such as adaptive radiation or diversification, and exemplify promising targets for biomedical drug development. Terebridae are an understudied lineage of conoidean snails, which also includes cone snails and turrids. Characterization of cone snail venom peptides, conotoxins, has revealed a cocktail of bioactive compounds used to investigate physiological cellular function, predator-prey interactions, and to develop novel therapeutics. However, venom diversity of other conoidean snails remains poorly understood. The present research applies a venomics approach to characterize novel terebrid venom peptides, teretoxins, from the venom gland transcriptomes of Triplostephanus anilis and Terebra subulata. Next-generation sequencing and de novo assembly identified 139 putative teretoxins that were analyzed for the presence of canonical peptide features as identified in conotoxins. To meet the challenges of de novo assembly, multiple approaches for cross validation of findings were performed to achieve reliable assemblies of venom duct transcriptomes and to obtain a robust portrait of Terebridae venom. Phylogenetic methodology was used to identify 14 teretoxin gene superfamilies for the first time, 13 of which are unique to the Terebridae. Additionally, basic local algorithm search tool homology-based searches to venom-related genes and posttranslational modification enzymes identified a convergence of certain venom proteins, such as actinoporin, commonly found in venoms. This research provides novel insights into venom evolution and recruitment in Conoidean predatory marine snails and identifies a plethora of terebrid venom peptides that can be used to investigate fundamental questions pertaining to gene evolution.

  8. Development of the feline lungworms Aelurostrongylus abstrusus and Troglostrongylus brevior in Helix aspersa snails.

    Science.gov (United States)

    Giannelli, Alessio; Ramos, Rafael Antonio Nascimento; Annoscia, Giada; Di Cesare, Angela; Colella, Vito; Brianti, Emanuele; Dantas-Torres, Filipe; Mutafchiev, Yasen; Otranto, Domenico

    2014-04-01

    Aelurostrongylus abstrusus (Strongylida, Angiostrongylidae) and Troglostrongylus brevior (Strongylida, Crenosomatidae) are regarded as important lungworm species of domestic felids, with the latter considered an emerging threat in the Mediterranean region. The present study aimed to assess their concurrent development in the mollusc Helix aspersa (Pulmonata, Helicidae). Thirty snails were infested with 100 first-stage larvae (L1) of A. abstrusus and T. brevior, isolated from a naturally infested kitten. Larval development was checked by digesting five specimens at 2, 6 and 11 days post infestation. Larvae retrieved were morphologically described and their identification was confirmed by specific PCR and sequencing. All H. aspersa snails were positive for A. abstrusus and T. brevior, whose larval stages were simultaneously detected at each time point. In addition, snails were exposed to outdoor conditions and examined after overwintering, testing positive up to 120 days post infestation. Data herein presented suggest that A. abstrusus and T. brevior develop in H. aspersa snails and may eventually co-infest cats. Data on the morphology of both parasitic species in H. aspersa provide additional information on their development and identification, to better understand the population dynamics of these lungworms in receptive snails and paratenic hosts.

  9. Differential expression of transcription factors Snail, Slug, SIP1, and Twist in ameloblastoma.

    Science.gov (United States)

    Siar, Chong Huat; Ng, Kok Han

    2014-01-01

    Epithelial-to-mesenchymal transition (EMT) via the mechanism of transcription repression is a crucial process for the induction of invasiveness in many human tumors. Ameloblastoma is a benign odontogenic epithelial neoplasm with a locally infiltrative behavior. Twist, an EMT promoter, has been implicated in its invasiveness. The roles of the other transcription factors remain unclarified. Four transcription factors, namely Snail, Slug, SIP1, and Twist, were examined immunohistochemically in 64 ameloblastoma [18 unicystic (UA), 20 solid/multicystic (SA), 4 desmoplastic (DA), and 22 recurrent (RA)]. All four transcription factors were differentially expressed in ameloblastoma [Snail: n = 60/64 (94%); Slug: n = 21/64 (33%); SIP: n = 18/64 (28%); Twist: n = 26/64 (41%)] (P 0.05). Intracellular protein localization was predominantly nuclear for Snail, cytoplasmic>nuclear for Slug and SIP1, and cytoplasmic/nuclear for Twist. Overexpression of Snail in most subsets (UA = 18/18; SMA = 19/20; DA = 4/4; RA = 19/22) compared with the other transcription factors (P ameloblastoma. Overexpression of Snail in most subsets suggests that this molecule is most likely the prototype transcription factor involved in inducing EMT in the ameloblastoma. © 2013 John Wiley & Sons A/S. Published by Blackwell Publishing Ltd.

  10. Genetic Variation between Biomphalaria alexandrina Snails Susceptible and Resistant to Schistosoma mansoni Infection

    Directory of Open Access Journals (Sweden)

    Suzanne M. F. El-Nassery

    2013-01-01

    Full Text Available Much effort has been made to control schistosomiasis infection in Egypt. However, enduring effects from such strategies have not yet been achieved. In this study, we sought to determine the genetic variability related to the interaction between Biomphalaria alexandrina snails and Schistosoma mansoni. Using RAPD-PCR with eight (10 mers random primers, we were able to determine the polymorphic markers that differed between snails susceptible and resistant to Schistosoma mansoni infection using five primers out of the eight. Our results suggest that the RAPD-PCR technique is an efficient means by which to compare genomes and to detect genetic variations between schistosomiasis intermediate hosts. The RAPD technique with the above-noted primers can identify genomic markers that are specifically related to the Biomphalaria alexandrina/Schistosoma mansoni relationship in the absence of specific nucleotide sequence information. This approach could be used in epidemiologic surveys to investigate genetic diversity among Biomphalaria alexandrina snails. The ability to determine resistant markers in Biomphalaria alexandrina snails could potentially lead to further studies that use refractory snails as agents to control the spread of schistosomiasis.

  11. Imidacloprid induced alterations in enzyme activities and energy reserves of the land snail, Helix aspersa.

    Science.gov (United States)

    Radwan, M A; Mohamed, M S

    2013-09-01

    The in vivo sublethal toxic effects (0.2 and 0.6 LD50) of topically applied imidacloprid on biochemical biomarkers in the land snail, Helix aspersa was examined. Biochemical perturbations were assessed by measuring the three enzymatic (Acetylcholinesterase, AChE; catalase, CAT and glutathione-S-transferase, GST) activities and three energy reserves (protein, glycogen and lipids) in the snails. Snail samples were taken from each sublethal dose and control groups at 1, 3 and 7 days after treatment. The results revealed that there were overall decrease in AChE activity as well as depletion of lipids and glycogen contents in the imidacloprid-treated snails compared to control groups. The CAT and GST activities of treated snails with the sublethal doses of imidacloprid were significantly higher than those of untreated controls along the three times of exposure. Moreover, an increase in the level of total proteins was observed in animals treated with 0.6 LD50 imidacloprid compared to control groups. The alterations in all tested biochemical perturbations were most pronounced with the 0.6 LD50 than 0.2 LD50. This study suggests that alterations of the enzyme activities and energy reserves in this species that could be useful as biomarkers of imidacloprid exposure in the evaluation of terrestrial impacts of this insecticide.

  12. Specialized insulin is used for chemical warfare by fish-hunting cone snails.

    Science.gov (United States)

    Safavi-Hemami, Helena; Gajewiak, Joanna; Karanth, Santhosh; Robinson, Samuel D; Ueberheide, Beatrix; Douglass, Adam D; Schlegel, Amnon; Imperial, Julita S; Watkins, Maren; Bandyopadhyay, Pradip K; Yandell, Mark; Li, Qing; Purcell, Anthony W; Norton, Raymond S; Ellgaard, Lars; Olivera, Baldomero M

    2015-02-10

    More than 100 species of venomous cone snails (genus Conus) are highly effective predators of fish. The vast majority of venom components identified and functionally characterized to date are neurotoxins specifically targeted to receptors, ion channels, and transporters in the nervous system of prey, predators, or competitors. Here we describe a venom component targeting energy metabolism, a radically different mechanism. Two fish-hunting cone snails, Conus geographus and Conus tulipa, have evolved specialized insulins that are expressed as major components of their venoms. These insulins are distinctive in having much greater similarity to fish insulins than to the molluscan hormone and are unique in that posttranslational modifications characteristic of conotoxins (hydroxyproline, γ-carboxyglutamate) are present. When injected into fish, the venom insulin elicits hypoglycemic shock, a condition characterized by dangerously low blood glucose. Our evidence suggests that insulin is specifically used as a weapon for prey capture by a subset of fish-hunting cone snails that use a net strategy to capture prey. Insulin appears to be a component of the nirvana cabal, a toxin combination in these venoms that is released into the water to disorient schools of small fish, making them easier to engulf with the snail's distended false mouth, which functions as a net. If an entire school of fish simultaneously experiences hypoglycemic shock, this should directly facilitate capture by the predatory snail.

  13. Influence of photon beam irradiation on Lymnaea natalensis snails infected with Fasciola gigantica.

    Science.gov (United States)

    Said, Doaa E; Rostom, Yousry A

    2006-04-01

    Lymnaea natalensis is the intermediate host of Fasciola gigantica in Egypt. The effect of photon beam irradiation on the ability of the laboratory reared L. natalensis to support the larval development of F. gigantica has been studied. 120 snails were divided into two groups: The control infected non irradiated group (GI) and the experimental infected irradiated group (GII). The later group was subdivided into two subgroups: GIIa: snails irradiated before infection and GIIb: snails irradiated after infection. Photon beam irradiation had non significant effect on the survival rate between the all groups at the 30th day post infection. The life span, the number of infected snails and the length of the shedding period were significantly decreased in the two irradiated subgroups than the control group. The effect was more obvious on GIIb without significant difference. The number of metacercariae significantly decreased in the 2 irradiated subgroups than the control one. Also, it was significantly decreased in GIIb when compared with GIIa. So, photon beam irradiation has a great role on retarding larval development of F. gigantica inside the snail. This opens the way to a new strategy for fascioliasis control of in Egypt.

  14. Attraction to amino acids by Lymnaea acuminata, the snail host of Fasciola species.

    Science.gov (United States)

    Tiwari, F; Singh, D K

    2004-04-01

    Adult Lymnaea acuminata (average length 20-22 mm) were collected locally from lakes and low-lying submerged fields from Gorakhpur. The chemoattraction studies were made in round glass aquaria measuring 30 cm in diameter and filled to a depth of 10 mm with 500 ml dechlorinated tap water. Each aquarium was divided into four concentric zones. At the starting time of the assay 10 snails were placed on the circumference of outermost zone 0. Snail attractant pellets (SAP) were added simultaneously in the center of central zone 3. SAP of different amino acids were prepared at concentrations of 10, 20, 50, 80 and 100 mM/2% agar solution and, subsequently, spread to a uniform thickness of 5 mm. After cooling, SAP were cut in small pieces of 5 mm in diameter. Lymnaea acuminata's attraction to amino acids was studied using different amino acid concentrations in SAP. Pellets containing amino acids with non-polar R groups (proline and tryptophan), a charged polar group (arginine) and uncharged polar R groups (serine, citrulline and asparagine) were tested. The snails were more attracted to the uncharged polar R group amino acid serine than to other groups of amino acids. The preferred amino acid concentration was 80 mM. The attraction of snails to different amino acids was concentration dependent. Snails could discriminate amongst the different amino acids at > or = 50 mM.

  15. Fascioliasis Control: In Vivo and In Vitro Phytotherapy of Vector Snail to Kill Fasciola Larva

    Science.gov (United States)

    Sunita, Kumari; Singh, D. K.

    2011-01-01

    Snail is one of the important components of an aquatic ecosystem, it acts as intermediate host of Fasciola species. Control of snail population below a certain threshold level is one of the important methods in the campaign to reduce the incidence of fascioliasis. Life cycle of the parasite can be interrupted by killing the snail or Fasciola larva redia and cercaria in the snail body. In vivo and in vitro toxicity of the plant products and their active component such as citral, ferulic acid, umbelliferone, azadirachtin, and allicin against larva of Fasciola in infected snail Lymnaea acuminata were tested. Mortality of larvae were observed at 2 h, 4 h, 6 h, and 8 h, of treatment. In in vivo treatment, azadirachtin caused highest mortality in redia and cercaria larva (8 h, LC50 0.11, and 0.05 mg/L) whereas in in vitro condition allicin was highly toxic against redia and cercaria (8 h, LC50 0.01, and 0.009 mg/L). Toxicity of citral was lowest against redia and cercaria larva. PMID:22132306

  16. Fascioliasis Control: In Vivo and In Vitro Phytotherapy of Vector Snail to Kill Fasciola Larva

    Directory of Open Access Journals (Sweden)

    Kumari Sunita

    2011-01-01

    Full Text Available Snail is one of the important components of an aquatic ecosystem, it acts as intermediate host of Fasciola species. Control of snail population below a certain threshold level is one of the important methods in the campaign to reduce the incidence of fascioliasis. Life cycle of the parasite can be interrupted by killing the snail or Fasciola larva redia and cercaria in the snail body. In vivo and in vitro toxicity of the plant products and their active component such as citral, ferulic acid, umbelliferone, azadirachtin, and allicin against larva of Fasciola in infected snail Lymnaea acuminata were tested. Mortality of larvae were observed at 2 h, 4 h, 6 h, and 8 h, of treatment. In in vivo treatment, azadirachtin caused highest mortality in redia and cercaria larva (8 h, LC50 0.11, and 0.05 mg/L whereas in in vitro condition allicin was highly toxic against redia and cercaria (8 h, LC50 0.01, and 0.009 mg/L. Toxicity of citral was lowest against redia and cercaria larva.

  17. Attraction to amino acids by Lymnaea acuminata, the snail host of Fasciola species

    Directory of Open Access Journals (Sweden)

    Tiwari F.

    2004-01-01

    Full Text Available Adult Lymnaea acuminata (average length 20-22 mm were collected locally from lakes and low-lying submerged fields from Gorakhpur. The chemoattraction studies were made in round glass aquaria measuring 30 cm in diameter and filled to a depth of 10 mm with 500 ml dechlorinated tap water. Each aquarium was divided into four concentric zones. At the starting time of the assay 10 snails were placed on the circumference of outermost zone 0. Snail attractant pellets (SAP were added simultaneously in the center of central zone 3. SAP of different amino acids were prepared at concentrations of 10, 20, 50, 80 and 100 mM/2% agar solution and, subsequently, spread to a uniform thickness of 5 mm. After cooling, SAP were cut in small pieces of 5 mm in diameter. Lymnaea acuminata's attraction to amino acids was studied using different amino acid concentrations in SAP. Pellets containing amino acids with non-polar R groups (proline and tryptophan, a charged polar group (arginine and uncharged polar R groups (serine, citrulline and asparagine were tested. The snails were more attracted to the uncharged polar R group amino acid serine than to other groups of amino acids. The preferred amino acid concentration was 80 mM. The attraction of snails to different amino acids was concentration dependent. Snails could discriminate amongst the different amino acids at > or = 50 mM.

  18. Snail/Slug-YAP/TAZ complexes cooperatively regulate mesenchymal stem cell function and bone formation.

    Science.gov (United States)

    Tang, Yi; Weiss, Stephen J

    2017-03-04

    Snail and Slug are zinc-finger transcription factors that play key roles in directing the epithelial-mesenchymal transition (EMT) programs associated with normal development as well as disease progression. More recent work suggests that these EMT-associated transcription factors also modulate the function of both embryonic and adult stem cells. Interestingly, YAP and TAZ, the co-transcriptional effectors of the Hippo pathway, likewise play an important role in stem cell self-renewal and lineage commitment. While direct intersections between the Snail/Slug and Hippo pathways have not been described previously, we recently described an unexpected cooperative interaction between Snail/Slug and YAP/TAZ that controls the self-renewal and differentiation properties of bone marrow-derived mesenchymal stem cells (MSCs), a cell population critical to bone development. Additional studies revealed that both Snail and Slug are able to form binary complexes with either YAP or TAZ that, together, control YAP/TAZ transcriptional activity and function throughout mouse development. Given the more recent observations that MSC-like cell populations are found in association throughout the vasculature where they participate in tissue regeneration, fibrosis and cancer, the Snail/Slug-YAP/TAZ axis is well-positioned to regulate global stem cell function in health and disease.

  19. Bisphenol A regulates Snail-mediated epithelial-mesenchymal transition in hemangioma cells.

    Science.gov (United States)

    Zhai, Denggao; He, Jiantai; Li, Xiaoli; Gong, Liansheng; Ouyang, Yang

    2016-08-01

    Hemangioma (HA) can be exposed to bisphenol A (BPA) through direct skin absorption. Although numerous studies indicated that BPA can trigger the progression of cancers, there is no study concerning the effects of BPA on development of HA. Our present study revealed that nanomolar BPA can significantly increase the in vitro migration and invasion of HA cells via induction of epithelial-mesenchymal transition (EMT), which was evidenced by the upregulation of vimentin and downregulation of E-cadherin. The BPA treatment also significantly increased the expression and nuclear localization of Snail and the key transcription factor of EMT, while it had no effect on the expression of other transcription factors such as Slug, Twist, or ZEB1. Silencing of Snail by small interfering RNAs attenuated BPA-induced downregulation of cadherin and upregulation of vimentin, suggesting that Snail is essential for BPA-induced EMT. Both estrogen receptor α (ERα) and G protein-coupled estrogen receptor (GPER) were expressed in HA cells; furthermore, BPA treatment can increase the expression of both ERα and GPER. However, only the inhibitor of ERα (ICI 182, 780), and not GPER (G15), can abolish BPA-induced upregulation of Snail. It suggested that ERα is involved in BPA-induced EMT of HA cells. Collectively, our data suggested that BPA can trigger the EMT of HA cells via ERα/Snail signals. It indicated that more attention should be paid to the skin exposure to BPA for HA patients. Copyright © 2016 John Wiley & Sons, Ltd.

  20. Polyethyleneimine (PEI mediated siRNA gene silencing in the Schistosoma mansoni snail host, Biomphalaria glabrata.

    Directory of Open Access Journals (Sweden)

    Matty Knight

    2011-07-01

    Full Text Available An in vivo, non-invasive technique for gene silencing by RNA interference (RNAi in the snail, Biomphalaria glabrata, has been developed using cationic polymer polyethyleneimine (PEI mediated delivery of long double-stranded (ds and small interfering (si RNA. Cellular delivery was evaluated and optimized by using a 'mock' fluorescent siRNA. Subsequently, we used the method to suppress expression of Cathepsin B (CathB with either the corresponding siRNA or dsRNA of this transcript. In addition, the knockdown of peroxiredoxin (Prx at both RNA and protein levels was achieved with the PEI-mediated soaking method. B. glabrata is an important snail host for the transmission of the parasitic digenean platyhelminth, Schistosoma mansoni that causes schistosomiasis in the neotropics. Progress is being made to realize the genome sequence of the snail and to uncover gene expression profiles and cellular pathways that enable the snail to either prevent or sustain an infection. Using PEI complexes, a convenient soaking method has been developed, enabling functional gene knockdown studies with either dsRNA or siRNA. The protocol developed offers a first whole organism method for host-parasite gene function studies needed to identify key mechanisms required for parasite development in the snail host, which ultimately are needed as points for disrupting this parasite mediated disease.

  1. A theory of game trees, based on solution trees

    NARCIS (Netherlands)

    W.H.L.M. Pijls (Wim); A. de Bruin (Arie); A. Plaat (Aske)

    1996-01-01

    textabstractIn this paper a complete theory of game tree algorithms is presented, entirely based upon the notion of a solution tree. Two types of solution trees are distinguished: max and min solution trees respectively. We show that most game tree algorithms construct a superposition of a max and a

  2. A theory of game trees, based on solution trees

    NARCIS (Netherlands)

    W.H.L.M. Pijls (Wim); A. de Bruin (Arie); A. Plaat (Aske)

    1996-01-01

    textabstractIn this paper a complete theory of game tree algorithms is presented, entirely based upon the notion of a solution tree. Two types of solution trees are distinguished: max and min solution trees respectively. We show that most game tree algorithms construct a superposition of a max and a

  3. Influences of forest structure, climate and species composition on tree mortality across the eastern US.

    Science.gov (United States)

    Lines, Emily R; Coomes, David A; Purves, Drew W

    2010-10-13

    Few studies have quantified regional variation in tree mortality, or explored whether species compositional changes or within-species variation are responsible for regional patterns, despite the fact that mortality has direct effects on the dynamics of woody biomass, species composition, stand structure, wood production and forest response to climate change. Using bayesian analysis of over 430,000 tree records from a large eastern US forest database we characterised tree mortality as a function of climate, soils, species and size (stem diameter). We found (1) mortality is U-shaped vs. stem diameter for all 21 species examined; (2) mortality is hump-shaped vs. plot basal area for most species; (3) geographical variation in mortality is substantial, and correlated with several environmental factors; and (4) individual species vary substantially from the combined average in the nature and magnitude of their mortality responses to environmental variation. Regional variation in mortality is therefore the product of variation in species composition combined with highly varied mortality-environment correlations within species. The results imply that variation in mortality is a crucial part of variation in the forest carbon cycle, such that including this variation in models of the global carbon cycle could significantly narrow uncertainty in climate change predictions.

  4. Influences of forest structure, climate and species composition on tree mortality across the eastern US.

    Directory of Open Access Journals (Sweden)

    Emily R Lines

    Full Text Available Few studies have quantified regional variation in tree mortality, or explored whether species compositional changes or within-species variation are responsible for regional patterns, despite the fact that mortality has direct effects on the dynamics of woody biomass, species composition, stand structure, wood production and forest response to climate change. Using bayesian analysis of over 430,000 tree records from a large eastern US forest database we characterised tree mortality as a function of climate, soils, species and size (stem diameter. We found (1 mortality is U-shaped vs. stem diameter for all 21 species examined; (2 mortality is hump-shaped vs. plot basal area for most species; (3 geographical variation in mortality is substantial, and correlated with several environmental factors; and (4 individual species vary substantially from the combined average in the nature and magnitude of their mortality responses to environmental variation. Regional variation in mortality is therefore the product of variation in species composition combined with highly varied mortality-environment correlations within species. The results imply that variation in mortality is a crucial part of variation in the forest carbon cycle, such that including this variation in models of the global carbon cycle could significantly narrow uncertainty in climate change predictions.

  5. D2-tree

    DEFF Research Database (Denmark)

    Brodal, Gerth Stølting; Sioutas, Spyros; Pantazos, Kostas;

    2015-01-01

    We present a new overlay, called the Deterministic Decentralized tree (D2-tree). The D2-tree compares favorably to other overlays for the following reasons: (a) it provides matching and better complexities, which are deterministic for the supported operations; (b) the management of nodes (peers......-balancing scheme of elements into nodes is deterministic and general enough to be applied to other hierarchical tree-based overlays. This load-balancing mechanism is based on an innovative lazy weight-balancing mechanism, which is interesting in its own right....

  6. Symmetric M-tree

    CERN Document Server

    Sexton, Alan P

    2010-01-01

    The M-tree is a paged, dynamically balanced metric access method that responds gracefully to the insertion of new objects. To date, no algorithm has been published for the corresponding Delete operation. We believe this to be non-trivial because of the design of the M-tree's Insert algorithm. We propose a modification to Insert that overcomes this problem and give the corresponding Delete algorithm. The performance of the tree is comparable to the M-tree and offers additional benefits in terms of supported operations, which we briefly discuss.

  7. A parallel buffer tree

    DEFF Research Database (Denmark)

    Sitchinava, Nodar; Zeh, Norbert

    2012-01-01

    We present the parallel buffer tree, a parallel external memory (PEM) data structure for batched search problems. This data structure is a non-trivial extension of Arge's sequential buffer tree to a private-cache multiprocessor environment and reduces the number of I/O operations by the number...... of available processor cores compared to its sequential counterpart, thereby taking full advantage of multicore parallelism. The parallel buffer tree is a search tree data structure that supports the batched parallel processing of a sequence of N insertions, deletions, membership queries, and range queries...

  8. Survival and growth of freshwater pulmonate and nonpulmonate snails in 28-day exposures to copper, ammonia, and pentachlorophenol

    Science.gov (United States)

    Besser, John M.; Dorman, Rebecca A.; Hardesty, Douglas K.; Ingersoll, Christopher G.

    2016-01-01

    We performed toxicity tests with two species of pulmonate snails (Lymnaea stagnalis and Physa gyrina) and four taxa of nonpulmonate snails in the family Hydrobiidae (Pyrgulopsis robusta,Taylorconcha serpenticola, Fluminicola sp., and Fontigens aldrichi). Snails were maintained in static-renewal or recirculating culture systems with adults removed periodically to isolate cohorts of offspring for toxicity testing. This method successfully produced offspring for both species of pulmonate snails and for two hydrobiid species, P. robusta and Fluminicola sp. Toxicity tests were performed for 28 days with copper, ammonia, and pentachlorophenol in hard reconstituted water with endpoints of survival and growth. Tests were started with 1-week-old L. stagnalis, 2-week-old P. gyrina, 5- to 13-week-old P. robusta and Fluminicola sp., and older juveniles and adults of several hydrobiid species. For all three chemicals, chronic toxicity values for pulmonate snails were consistently greater than those for hydrobiid snails, and hydrobiids were among the most sensitive taxa in species sensitivity distributions for all three chemicals. These results suggest that the toxicant sensitivity of nonpulmonate snails in the family Hydrobiidae would not be adequately represented by results of toxicity testing with pulmonate snails.

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

    Science.gov (United States)

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

    2013-10-01

    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.

  10. Survival and Growth of Freshwater Pulmonate and Nonpulmonate Snails in 28-Day Exposures to Copper, Ammonia, and Pentachlorophenol.

    Science.gov (United States)

    Besser, John M; Dorman, Rebecca A; Hardesty, Douglas L; Ingersoll, Christopher G

    2016-02-01

    We performed toxicity tests with two species of pulmonate snails (Lymnaea stagnalis and Physa gyrina) and four taxa of nonpulmonate snails in the family Hydrobiidae (Pyrgulopsis robusta, Taylorconcha serpenticola, Fluminicola sp., and Fontigens aldrichi). Snails were maintained in static-renewal or recirculating culture systems with adults removed periodically to isolate cohorts of offspring for toxicity testing. This method successfully produced offspring for both species of pulmonate snails and for two hydrobiid species, P. robusta and Fluminicola sp. Toxicity tests were performed for 28 days with copper, ammonia, and pentachlorophenol in hard reconstituted water with endpoints of survival and growth. Tests were started with 1-week-old L. stagnalis, 2-week-old P. gyrina, 5- to 13-week-old P. robusta and Fluminicola sp., and older juveniles and adults of several hydrobiid species. For all three chemicals, chronic toxicity values for pulmonate snails were consistently greater than those for hydrobiid snails, and hydrobiids were among the most sensitive taxa in species sensitivity distributions for all three chemicals. These results suggest that the toxicant sensitivity of nonpulmonate snails in the family Hydrobiidae would not be adequately represented by results of toxicity testing with pulmonate snails.

  11. Food intake, growth, and reproduction as affected by day length and food availability in the pond snail Lymnaea stagnalis

    NARCIS (Netherlands)

    Maat, ter A.; Zonneveld, C.; Visser, de J.A.G.M.; Jansen, R.F.; Montagne-Wajer, K.; Koene, J.M.

    2007-01-01

    With the aim of integrating the physiology and evolutionary ecology of Lymnaea stagnalis (Linnaeus, 1758), we studied the effects of day length and food availability on the energy budget. Snails were assigned to two different photoperiods and three levels of food availability. The snails were kept i

  12. Mutations in snail family genes enhance craniosynostosis of Twist1 haplo-insufficient mice: implications for Saethre-Chotzen Syndrome.

    Science.gov (United States)

    Oram, Kathleen F; Gridley, Thomas

    2005-06-01

    In Drosophila, mutations in the Twist gene interact with mutations in the Snail gene. We show that the mouse Twist1 mutation interacts with Snai1 and Snai2 mutations to enhance aberrant cranial suture fusion, demonstrating that genetic interactions between genes of the Twist and Snail families have been conserved during evolution.

  13. Food intake, growth, and reproduction as affected by day length and food availability in the pond snail Lymnaea stagnalis

    NARCIS (Netherlands)

    Maat, ter A.; Zonneveld, C.; Visser, de J.A.G.M.; Jansen, R.F.; Montagne-Wajer, K.; Koene, J.M.

    2007-01-01

    With the aim of integrating the physiology and evolutionary ecology of Lymnaea stagnalis (Linnaeus, 1758), we studied the effects of day length and food availability on the energy budget. Snails were assigned to two different photoperiods and three levels of food availability. The snails were kept

  14. Neuromedin U is upregulated by Snail at early stages of EMT in HT29 colon cancer cells.

    Science.gov (United States)

    Przygodzka, Patrycja; Papiewska-Pajak, Izabela; Bogusz, Helena; Kryczka, Jakub; Sobierajska, Katarzyna; Kowalska, M Anna; Boncela, Joanna

    2016-11-01

    The epithelial-mesenchymal transition (EMT) is considered a core process that facilitates the escape of cancer cells from the primary tumor site. The transcription factor Snail was identified as a key regulator of EMT; however, the cascade of regulatory events leading to metastasis remains unknown and new predictive markers of the process are awaited. Gene expressions were analysed using real-time PCR, protein level by Western immunoblotting and confocal imaging. The motility of the cells was examined using time-lapse microscopy. Affymetrix GeneChip Human Genome U133 Plus 2.0 analysis was performed to identify transcriptomic changes upon Snail. Snail silencing was performed using siRNA nucleofection. NMU detection was performed by ELISA. HT29 cells overexpressing Snail showed changed morphology, functions and transcriptomic profile indicating EMT induction. Changes in expression of 324 genes previously correlated with cell motility were observed. Neuromedin U was the second highest upregulated gene in HT29-Snail cells. This increase was validated by real-time PCR. Additionally elevated NMU protein was detected by ELISA in cell media. These results show that Snail in HT29 cells regulates early phenotype conversion towards an intermediate epithelial state. We provided the first evidence that neuromedin U is associated with Snail regulatory function of metastatic induction in colon cancer cells. We described the global, early transcriptomic changes induced through Snail in HT29 colon cancer cells and suggested NMU involvement in this process. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Mutations in Snail Family Genes Enhance Craniosynostosis of Twist1 Haplo-insufficient Mice: Implications for Saethre-Chotzen Syndrome

    OpenAIRE

    2005-01-01

    In Drosophila, mutations in the Twist gene interact with mutations in the Snail gene. We show that the mouse Twist1 mutation interacts with Snai1 and Snai2 mutations to enhance aberrant cranial suture fusion, demonstrating that genetic interactions between genes of the Twist and Snail families have been conserved during evolution.

  16. Performance of broilers fed with snail (Pomacea caniculata meal as substitute to fish meal or meat and bone meal

    Directory of Open Access Journals (Sweden)

    Ulep, LJL.

    1991-01-01

    Full Text Available Snail meal was used as a substitution to fish meat and bone meal in broiler rations. Final weightand feed conversion efficiency of the birds, profit and return on investment differed significantly among treatments. Feed consumption and production costs were comparable. Results show that snail meal can replace fish or meat and bone meal in broiler diets.

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

    DEFF Research Database (Denmark)

    Madsen, Henry; Coulibaly, Godefroy; Furu, Peter

    1987-01-01

    Snail surveys were carried out in various parts of Mali. All areas surveyed are part of the Niger basin being either affluents or irrigation schemes fed by this river. The snail species present varied greatly between areas. The following potential hosts of schistosomes were recorded: Biomphalaria...... pfeifferi, Bulinus truncatus, B. globosus, B. umbilicatus, B. forskalii and B. senegalensis. In the large irrigation schemes, i.e. 'Office du Niger' and Baguinéda, only B. pfeifferi and B. truncatus appear to be intermediate hosts. Snail distribution appeared to some extent to be focal and high snail...... densities appeared to be associated with human water contact activities, which apparently create favourable biotopes for the snails. This is probably due to an alteration of the vegetation and an increase of the trophic status of the site by contamination with food remnants and other debris. The larger...

  18. An overview of freshwater snails in Asia with main focus on Vietnam

    DEFF Research Database (Denmark)

    Madsen, Henry; Hung, N. M.

    2014-01-01

    Freshwater snails have received much attention for their role as intermediate hosts for trematodes causing disease in people and animals such as schistosomiasis and various food-borne trematodes. While effective medical treatment exists for some of these diseases there is need for preventive...... measures to reduce transmission, e.g. control of intermediate hosts because transmission patterns are often complicated due to presence of reservoir final hosts. In order to implement control measures against the intermediate host snails with minimal impact on the freshwater ecosystems...... and their biodiversity, a profound knowledge on transmission patterns of the trematodes is required and this is partly related to distribution, habitat preferences, and seasonal variation in density of the intermediate host species. Identification of snail species can be problematic on the basis of morphological...

  19. Large-scale facilitation of a sessile community by an invasive habitat-forming snail

    Science.gov (United States)

    Thyrring, Jakob; Thomsen, Mads Solgaard; Wernberg, Thomas

    2013-12-01

    We provide an example of extensive facilitation of a sessile community throughout an invaded estuary by the invasive snail Batillaria australis. We show that B. australis greatly increases a limiting resource (attachment space) to a community of sessile organisms and estimate that a large part of the invaded estuary now contain ca. 50 times more sessile individuals associated with the invader than all native snails combined. We argue that native snails are unlikely to have been dramatically reduced by the invader, and we therefore suggest that the shell-attached sessile community, as a functional group, has benefitted significantly from this invasion. These results expand the current understanding of how invaded marine systems respond to habitat-forming invaders.

  20. EFFECTS OF CARBOFURAN ON THE REPRODUCTIVE CAPACITY OF A FRESHWATER SNAIL, RADIX QUADRASI, UNDER LABORATORY CONDITIONS

    Directory of Open Access Journals (Sweden)

    VIRGINIA S. CARING

    1992-01-01

    Full Text Available The effects of 4 sublethal concentrations of carbofuran (250, 500, 1000 and 2000 ppm on the reproductive capacity of R. quadrasi was determined. Results showed that incubation period is delayed and inhibited by 1000 and 2000 ppm carbofuran but not by lower concentrations. The hatching period is longer in treated snails and not all eggs hatch in the 1000 and 2000 ppm treatment. The percentage of hatching is inversely proportional to the carbofuran concentration. Oviposition was delayed in all the treated stages and at all dosages. The higher the carbofuran concentration, the later the onset of oviposition. The reproductive period is shortened. Fecundity was decreased in snails treated at EMB and SM. However, only the 2000 ppm carbofuran concentration showed an adverse effect on the snails exposure at PSM.