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Sample records for humped tree snail

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

    Science.gov (United States)

    Lee, Taehwan; Burch, John B; Coote, Trevor; Pearce-Kelly, Paul; Hickman, Carole; Meyer, Jean-Yves; O Foighil, Diarmaid

    2009-08-18

    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. 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. 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. clara to differentially survive long-term direct

  2. 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

  3. 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...

  4. 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...

  5. The health hump

    OpenAIRE

    Strulik, Holger

    2015-01-01

    In this paper, I suggest a novel explanation for a hump-shaped ageconsumption profile, based on human aging. The model integrates health in the utility function and utilizes recent estimates on the effects of health on the marginal utility of consumption. The parsimonious model has a closed-form solution for the age of peak consumption and the consumption level at that age relative to initial consumption. A calibration of the model with data from gerontology produces an empirically plausible ...

  6. Evolutionary history of a vanishing radiation: isolation-dependent persistence and diversification in Pacific Island partulid tree snails.

    Science.gov (United States)

    Lee, Taehwan; Li, Jingchun; Churchill, Celia K C; Foighil, Diarmaid Ó

    2014-09-24

    Partulid tree snails are endemic to Pacific high islands and have experienced extraordinary rates of extinction in recent decades. Although they collectively range across a 10,000 km swath of Oceania, half of the family's total species diversity is endemic to a single Eastern Pacific hot spot archipelago (the Society Islands) and all three partulid genera display highly distinctive distributions. Our goal was to investigate broad scale (range wide) and fine scale (within-Society Islands) molecular phylogenetic relationships of the two widespread genera, Partula and Samoana. What can such data tell us regarding the genesis of such divergent generic distribution patterns, and nominal species diversity levels across Oceania? Museum, captive (zoo) and contemporary field specimens enabled us to genotype 54 of the ~120 recognized species, including many extinct or extirpated taxa, from 14 archipelagoes. The genera Partula and Samoana are products of very distinct diversification processes. Originating at the western edge of the familial range, the derived genus Samoana is a relatively recent arrival in the far eastern archipelagoes (Society, Austral, Marquesas) where it exhibits a stepping-stone phylogenetic pattern and has proven adept at both intra-and inter- archipelago colonization. The pronounced east-west geographic disjunction exhibited by the genus Partula stems from a much older long-distance dispersal event and its high taxonomic diversity in the Society Islands is a product of a long history of within-archipelago diversification. The central importance of isolation for partulid lineage persistence and diversification is evident in time-calibrated phylogenetic trees that show that remote archipelagoes least impacted by continental biotas bear the oldest clades and/or the most speciose radiations. In contemporary Oceania, that isolation is being progressively undermined and these tree snails are now directly exposed to introduced continental predators

  7. Demographic and genetic factors in the recovery or demise of ex situ populations following a severe bottleneck in fifteen species of Hawaiian tree snails

    Directory of Open Access Journals (Sweden)

    Melissa R. Price

    2015-11-01

    Full Text Available Wild populations of endangered Hawaiian tree snails have declined precipitously over the last century due to introduced predators and other human impacts. Life history traits, such as very low fecundity (<5 offspring per year across taxa and maturity at approximately four years of age have made recovery difficult. Conservation efforts such as in situ predator-free enclosures may increase survival to maturity by protecting offspring from predation, but no long-term data existed prior to this study demonstrating the demographic and genetic parameters necessary to maintain populations within those enclosures. We evaluated over 20 years of evidence for the dynamics of survival and extinction in captive ex situ populations of Hawaiian tree snails established from wild-collected individuals. From 1991 to 2006, small numbers of snails (<15 from fifteen species were collected from the wild to initiate captive-reared populations as a hedge against extinction. This small number of founders resulted in a severe bottleneck in each of the captive-reared populations. We identified key demographic parameters that predicted population recovery from this bottleneck. Species with captive populations that produced between two and four offspring per adult per year and had 20–50% of those offspring survive to maturity recovered to numbers above 100 individuals, and maintained viable populations following a decline that occurred between 2009 and 2014. Those populations that had less than two offspring per adult per year and less than 20% survival to maturity did not reach 100 individuals in captivity, and many of these populations died out during the recent decline. We suggest that small reductions in fitness may contribute to extirpation in taxa with inherently low fecundity, by keeping populations below a threshold number essential to long-term recovery. Future ex situ populations should be founded with no less than 15 adults, and maintained in conditions closely

  8. Tabanidae and other Diptera on Camel’s Hump Vermont: Ecological Observations

    Directory of Open Access Journals (Sweden)

    Jeffrey Freeman

    2011-11-01

    Full Text Available A canopy trap and aerial nets led to finding 8 species of Tabanidae. There was an abundance of calyptrate muscoid flies. Camel’s Hump is in the Green Mountains of western New England, USA. Discovering Diptera on Camel’s Hump involved sixteen visits over 40 years. Upwards of 23 other Diptera species are listed. Habitats on the east side and above 762 m (2500 ft elevation on Camel’s Hump differ from the west slope but the boreal forest on both sides is influenced by cloud and fog precipitation on trees. The cliffs just above the 900 m level along the east side are often overlooked, are not seen from the summit and provide access to morning sun for insects. Recent visits explored the role of polarized skylight in relation to the canopy trap, the boreal forest environment and flies found there.

  9. Effect of speed hump characteristics on pavement condition

    Directory of Open Access Journals (Sweden)

    Talaat Ali Abdel-Wahed

    2017-02-01

    Full Text Available Speed humps are the most common type of traffic calming devices due to their low cost and easy installation. However, in many Egyptian roads, considerable number of these humps is randomly placed without proper engineering studies and justifications. Deterioration of pavement condition is observed near these humps. This paper presents a case study applied to collect and analyze visual inspection data for the reason of evaluating the impact of speed humps on pavement condition on intercity rural roads. The paper used 52 speed humps located in an intercity two-lane, two-way road that connects two cities, Tahta and Gerga, in Upper Egypt. The total length of this road is about 34 km. Pavement condition index (PCI, in road sections, near speed humps in the two directions of travel were calculated from the visual inspection measurements. The characteristics of each speed hump (width, height, and distance from preceding hump were measured. Using statistical analyses, the correlations between the pavement conditions and hump characteristics were examined. Regression analysis models were developed to represent the relationships between pavement conditions and hump characteristics. Generally, the results proved that the pavement conditions are greatly influenced by the presence of speed humps and hump characteristics.

  10. 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.

  11. An improved JWKB approximation for multiple-humped fission barriers

    International Nuclear Information System (INIS)

    Martinelli, T.; Menapace, E.; Ventura, A.

    1977-01-01

    Penetrabilities of two- and three-humped fission barriers are calculated in semiclassical (JWKB) approximation, valid also in the case where classical turning points are close, or coincident (excitation energy near the top of some hump). Numerical results are shown for Th 234 . (author)

  12. An acceleration test for stress corrosion cracking using humped specimen

    International Nuclear Information System (INIS)

    Kamaya, Masayuki; Fukumura, Takuya; Totsuka, Nobuo

    2003-01-01

    By using the humped specimen, which is processed by the humped die, in the slow strain rate technique (SSRT) test, fracture facet due to stress corrosion cracking (SCC) can be observed in relatively short duration. Although the cold work and concentrated stress and strain caused by the characteristic shape of the specimen accelerate the SCC, to date these acceleration effects have not been examined quantitatively. In the present study, the acceleration effects of the humped specimen were examined through experiments and finite element analyses (FEA). The experiments investigated the SCC of alloy 600 in the primary water environment of a pressurized water reactor. SSRT tests were conducted using two kinds of humped specimen: one was annealed after hump processing in order to eliminate the cold work, and the other was hump processed after the annealing treatment. The work ratio caused by the hump processing and stress/strain conditions during SSRT test were evaluated by FEA. It was found that maximum work ratio of 30% is introduced by the hump processing and that the distribution of the work ratio is not uniform. Furthermore, the work ratio is influenced by the friction between the specimen and dies as well as by the shape of dies. It was revealed that not only the cold work but also the concentrated stress and strain during SSRT test accelerate the crack initiation and growth of the SCC. (author)

  13. Radioactive fuel cask railcar humping study

    International Nuclear Information System (INIS)

    Wilson, L.T.

    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 1 / 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

  14. 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)

  15. 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.

  16. Scaling of spiking and humping in keyhole welding

    Energy Technology Data Exchange (ETDEWEB)

    Wei, P S; Chuang, K C [Department of Mechanical and Electro-Mechanical Engineering, National Sun Yat-Sen University, Kaohsiung, Taiwan (China); DebRoy, T [Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA 16802 (United States); Ku, J S, E-mail: pswei@mail.nsysu.edu.tw, E-mail: cielo.zhuang@gmail.com, E-mail: rtd1@psu.edu, E-mail: jsku@mail.nsysu.edu.tw [Institute of Materials Science and Engineering, National Sun Yat-Sen University, Kaohsiung, Taiwan (China)

    2011-06-22

    Spiking, rippling and humping seriously reduce the strength of welds. The effects of beam focusing, volatile alloying element concentration and welding velocity on spiking, coarse rippling and humping in keyhole mode electron-beam welding are examined through scale analysis. Although these defects have been studied in the past, the mechanisms for their formation are not fully understood. This work relates the average amplitudes of spikes to fusion zone depth for the welding of Al 6061, SS 304 and carbon steel, and Al 5083. The scale analysis introduces welding and melting efficiencies and an appropriate power distribution to account for the focusing effects, and the energy which is reflected and escapes through the keyhole opening to the surroundings. The frequency of humping and spiking can also be predicted from the scale analysis. The analysis also reveals the interrelation between coarse rippling and humping. The data and the mechanistic findings reported in this study are useful for understanding and preventing spiking and humping during keyhole mode electron and laser beam welding.

  17. 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.

  18. 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.

  19. Lichen Endozoochory by Snails

    Science.gov (United States)

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

    2011-01-01

    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. PMID:21533256

  20. Changes in the selection differential exerted on a marine snail during the ontogeny of a predatory shore crab.

    Science.gov (United States)

    Pakes, D; Boulding, E G

    2010-08-01

    Empirical estimates of selection gradients caused by predators are common, yet no one has quantified how these estimates vary with predator ontogeny. We used logistic regression to investigate how selection on gastropod shell thickness changed with predator size. Only small and medium purple shore crabs (Hemigrapsus nudus) exerted a linear selection gradient for increased shell-thickness within a single population of the intertidal snail (Littorina subrotundata). The shape of the fitness function for shell thickness was confirmed to be linear for small and medium crabs but was humped for large male crabs, suggesting no directional selection. A second experiment using two prey species to amplify shell thickness differences established that the selection differential on adult snails decreased linearly as crab size increased. We observed differences in size distribution and sex ratios among three natural shore crab populations that may cause spatial and temporal variation in predator-mediated selection on local snail populations.

  1. Scoliosis associated with airflow obstruction due to endothoracic vertebral hump.

    Science.gov (United States)

    Ito, Kenyu; Kawakami, Noriaki; Miyasaka, Kazuyoshi; Tsuji, Taichi; Ohara, Tetsuya; Nohara, Ayato

    2012-12-01

    A retrospective clinical study of scoliosis-associated airflow obstruction due to endothoracic vertebral hump. The purpose of this study was to evaluate and present anatomical features of patients with scoliosis who showed airflow obstruction caused by endothoracic vertebral hump. It is well known that severe scoliosis causes airflow restriction due to thoracic cage deformity. There have been few reports of clinical data and anatomical features on scoliosis associated with airflow obstruction due to endothoracic vertebral hump. The subjects were 6 patients. The diagnoses were idiopathic scoliosis in 3 patients, symptomatic scoliosis in 2 patients, and thoracogenic scoliosis in 1 patient. The radiological outcome, comorbidities, pre- and postoperative respiratory function, and surgical complication were analyzed. Four patients had preoperative atelectasis on the convex side of the lower lobe and improved after the operations. All patients showed main thoracic curves and their apex was located at T7-T9. All patients had lordoscoliosis except 1, who demonstrated kyphosing scoliosis. The correction rate was 78% (62.8%-83.5%). Preoperative thoracic lordosis within the range of -5° to -47° was postoperatively corrected to a substantially normal kyphosis within the range of 9° to 24°. The average vital capacity, percent VC improved from 0.72 L (0.33-1.17 L) to 1.21 L (0.82-1.71 L) and 45.5% (37.3%- 50.8%) to 63.7% (41.0%-88.6%) relatively. Spine Penetration Index improved from 23% (18%-35%) to 16% (13%-19%). Endothoracic hump ratio improved from 1.34 (0.98-1.93) to 1.12 (0.86-1.28). Each patient with symptomatic scoliosis and thoracogenic scoliosis required relatively long periods of respiration management. Patients having lordoscoliosis with an apex located between T7 and T9 may develop airflow obstruction due to an endothoracic vertebral hump. Correction of lordoscoliosis through anterior and posterior approaches successfully improved endothoracic hump ratio and

  2. Hump-shape Uncertainty, Agency Costs and Aggregate Fluctuations

    OpenAIRE

    Lee, Gabriel; Kevin, Salyer; Strobel, Johannes

    2016-01-01

    Previously measured uncertainty shocks using the U.S. data show a hump-shape time path: Uncertainty rises for two years before its decline. Current literature on the effects uncertainty on macroeconomics, including housing, has not accounted for this observation. Consequently, the literature on uncertainty and macroeconomics is divided on the effcts and the propagation mechanism of uncertainty on aggregate uctuations. This paper shows that when uncertainty rises and falls over time, th...

  3. 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.

  4. SHORT COMMUNICATION Challenges to increased Snail ...

    African Journals Online (AJOL)

    The commercial production of snails has not kept pace with the demand for it in Ibarapa Local Government Areas (ILGA) of Oyo State, Nigeria. A study was carried out to characterize the snail farmers, identify challenges to an increased snail production and suggest measures for sustainable snail production. Structured ...

  5. Fundamentals of the double-humped fission barrier

    International Nuclear Information System (INIS)

    Brack, M.

    1980-01-01

    We review the development of the theory of the fission barrier over the past forty years. Special emphasis is put on the shell-correction method of Strutinsky and its foundation and numerical verification from microscopical Hartree-Fock calculations. The different practical realisations of the method and its applications to the calculation of deformation energy surfaces are reviewed. The influence of the different shape degrees of freedom of the nucleus on the form of the fission barrier is discussed. Finally, we summarize some more recent developments concerning both experimental and theoretical aspects of the double-humped fission barrier. (author)

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

    OpenAIRE

    E. Salimi Naghani* and L. Akradi1

    2012-01-01

    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 d...

  7. 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.

  8. 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 hump...

  9. Stability analysis of a boundary layer over a hump using parabolized stability equations

    Energy Technology Data Exchange (ETDEWEB)

    Gao, B; Park, D H; Park, S O, E-mail: sopark@kaist.ac.kr [Division of Aerospace Engineering, Korea Advanced Institute of Science and Technology, Gusong-dong, Yusong-gu, Daejeon 305-701 (Korea, Republic of)

    2011-10-15

    Parabolized stability equations (PSEs) were used to investigate the stability of boundary layer flows over a small hump. The applicability of PSEs to flows with a small separation bubble was examined by comparing the result with DNS data. It was found that PSEs can efficiently track the disturbance waves with an acceptable accuracy in spite of a small separation bubble. A typical evolution scenario of Tollmien-Schlichting (TS) wave is presented. The adverse pressure gradient and the flow separation due to the hump have a strong effect on the amplification of the disturbances. The effect of hump width and height is also examined. When the width of the hump is reduced, the amplification factor is increased. The height of the hump is found to obviously influence the stability only when it is greater than the critical layer thickness.

  10. Stability analysis of a boundary layer over a hump using parabolized stability equations

    International Nuclear Information System (INIS)

    Gao, B; Park, D H; Park, S O

    2011-01-01

    Parabolized stability equations (PSEs) were used to investigate the stability of boundary layer flows over a small hump. The applicability of PSEs to flows with a small separation bubble was examined by comparing the result with DNS data. It was found that PSEs can efficiently track the disturbance waves with an acceptable accuracy in spite of a small separation bubble. A typical evolution scenario of Tollmien-Schlichting (TS) wave is presented. The adverse pressure gradient and the flow separation due to the hump have a strong effect on the amplification of the disturbances. The effect of hump width and height is also examined. When the width of the hump is reduced, the amplification factor is increased. The height of the hump is found to obviously influence the stability only when it is greater than the critical layer thickness.

  11. STUDY OF TECHNICAL STATE IMPACT OF BRAKE RETARDERS AT THE PROCESSING ABILITY OF HUMPS

    Directory of Open Access Journals (Sweden)

    D. M. Kozachenko

    2016-08-01

    Full Text Available Purpose. The research aims development of methods for calculating the estimated capacity humps for the loss conditions of brake power retarders. Methodology. The operation of humps is connected with large number of random factors, such as the characteristics of cuts, environmental conditions, the value of braking power implemented by retardants and others. In this regard, to research the set tasks the methods of simulation modeling and mathematical statistics are used. Determination of speed and motion time of cuts on the routes is carried out on the basis of rolling down modeling of their rolling down from the humps. Findings. If the brake power of retarders of the rolling down part of humps is not enough to stop the cuts, it should be provided the intervals during break-up to release the rolling routes from the preliminary cuts. The dependencies allowing to set the duration of these intervals were determined using the methods of the probability theory If the brake power of retarders at the rolling down part of humps and at the classification tracks is not enough to meet the requirements of the aimed regulation of the cuts rolling speed, it is necessary the use the additional brake shoes. The work develops the methods that on the basis of simulation modeling of the humping process allow one to set the desired value of the break-up duration increase. They ensure the traffic safety at the given number of car motion speed regulators. Originality. Authors firstly proposed the improved methods for determining the estimated capacity of humps. Unlike the existing ones, allow taking into account the technological limitations caused by the requirements of the humping process safety and can be used to assess the performance of the humps in the conditions of parametric failures of the retarders. Practical value. The use of the proposed methods allows assessing the influence of the retarders’ disrepair on the performance degradation of humps for the

  12. 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.

  13. 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...

  14. Transient wave behaviour over an underwater sliding hump from experiments and analytical and numerical modelling

    Energy Technology Data Exchange (ETDEWEB)

    Callaghan, David P.; Nielsen, Peter [The University of Queensland, School of Civil Engineering, Brisbane (Australia); Ahmadi, Afshin [Kellogg Brown and Root Pty Ltd, Brisbane, QLD (Australia)

    2011-12-15

    Flume measurements of a one-dimensional sliding hump starting from rest in quiescence fresh water indicate that when the hump travels at speed less than the shallow-water wave celerity, three waves emerge, travelling in two directions. One wave travels in the opposite direction to the sliding hump at approximately the shallow-water wave celerity (backward free wave). Another wave travels approximately in step with the hump (forced wave), and the remaining wave travels in the direction of the hump at approximately the shallow-water wave celerity (forward free wave). These experiments were completed for a range of sliding hump speed relative to the shallow-water wave celerity, up to unity of this ratio, to investigate possible derivation from solutions of the Euler equation with non-linear and non-hydrostatic terms being included or excluded. For the experimental arrangements tested, the forced waves were negative (depression or reduced water surface elevation) waves while the free waves were positive (bulges or increased water surface elevation). For experiments where the sliding hump travelled at less than 80% of the shallow-water wave celerity did not include transient behaviour measurements (i.e. when the three waves still overlapped). The three wave framework was partially supported by these measurements in that the separated forward and forced waves were compared to measurements. For the laboratory scale experiments, the forward free wave height was predicted reasonably by the long-wave equation (ignoring non-linear and non-hydrostatic terms) when the sliding hump speed was less than 80% of the shallow-water wave celerity. The forced wave depression magnitude required the Euler equations for all hump speed tested. The long-wave solution, while being valid in a limited parameter range, does predict the existence of the three waves as found in these experiments (forward travelling waves measured quantitatively while the backward travelling waves visually by video

  15. Humps in the volatility structure of the crude oil futures market: New evidence

    International Nuclear Information System (INIS)

    Chiarella, Carl; Kang, Boda; Nikitopoulos, Christina Sklibosios; Tô, Thuy-Duong

    2013-01-01

    This paper analyses the volatility structure of commodity derivatives markets. The model encompasses hump-shaped, unspanned stochastic volatility, which entails a finite-dimensional affine model for the commodity futures curve and quasi-analytical prices for options on commodity futures. Using an extensive database of crude oil futures and futures options spanning 21 years, we find the presence of hump-shaped, partially spanned stochastic volatility in the crude oil market. The hump shaped feature is more pronounced when the market is more volatile, and delivers better pricing as well as hedging performance under various dynamic factor hedging schemes. - Highlights: • This paper analyses the volatility structure of commodity derivatives markets. • 21-years of data on crude oil futures and futures options is used. • The crude oil futures market has hump-shaped, unspanned stochastic volatility. • The hump shaped feature is more pronounced when the market is more volatile. • Hump shape delivers better pricing and hedging compared to exponential decay

  16. The effects of wetland habitat structure on Florida apple snail density

    Science.gov (United States)

    Karunaratne, L.B.; Darby, P.C.; Bennetts, R.E.

    2006-01-01

    Wetlands often support a variety of juxtaposed habitat patches (e.g., grass-, shrub- or tree-dominated) differentially suited to support the inhabiting fauna. The proportion of available habitat types has been affected by human activity and consequently has contributed to degrading habitat quality for some species. The Florida apple snail (Pomacea paludosa) has drawn attention as a critical prey item for wetlands wildlife and as an indicator of wetlands restoration success in peninsular Florida, USA. An apparent contradiction has evolved wherein this species appears intolerant of drying events, but these disturbances may be necessary to maintain suitable habitat structure for apple snails. We recently reported that assertions regarding intolerance to dry downs in this species were inaccurate. Here, we compared snail density in habitats with (wet prairie) and without (slough) emergent macrophytes, as well as evaluating the effects of structural attributes within the broad wet prairie habitat type. Snail densities were greater in prairies relative to sloughs (??2= 12.90, df=1, P=0.0003), often by a factor of two to three. Within wet prairie habitats, we found greater snail densities in Panicum hemitomon as compared to Eleocharis cellulosa (??2=31.45, df=1, P=0.0001). Significantly fewer snails were found in dense E. cellulosa as compared to habitats with lower stem density (??2= 10.73, df=1, P=0.011). Our results indicate that wet prairie habitat supports greater snail densities than nymphaea-dominatd slough. Our results have implications for wetlands water management in that continuous inundation has been shown to convert wet prairie to slough habitat, and we suggest this should be avoided in support of apple snails and their predators. ?? 2006, The Society of Wetland Scientists.

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

    African Journals Online (AJOL)

    G = the number or snails in grasses, % = percentage proportion of shruh snail s to the total number ot' snails in both habitats, ..... transmission pylons (P.F. Kasigwa personal observations). .... ation and k is any positive integer. References.

  18. 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.

  19. 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

  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. Numerical and Experimental Investigations of Humping Phenomena in Laser Micro Welding

    Science.gov (United States)

    Otto, Andreas; Patschger, Andreas; Seiler, Michael

    The Humping effect is a phenomenon which is observed approximately since 50 years in various welding procedures and is characterized by droplets due to a pile-up of the melt pool. It occurs within a broad range of process parameters. Particularly during micro welding, humping effect is critical due to typically high feed rates. In the past, essentially two approaches (fluid-dynamic approach of streaming melt within the molten pool and the Plateau-Rayleigh instability of a liquid jet) were discussed in order to explain the occurrence of the humping effect. But none of both can fully explain all observed effects. For this reason, experimental studies in micro welding of thin metal foils were performed in order to determine the influence of process parameters on the occurrence of humping effects. The experimental observations were compared with results from numerical multi-physical simulations (incorporating beam propagation, incoupling, heat transfer, fluid dynamics etc.) to provide a deeper understanding of the causes for hump formation.

  2. 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

  3. Current Situation of Edible Snails in Indonesia

    Directory of Open Access Journals (Sweden)

    Schneider, K.

    1999-01-01

    Full Text Available From March 7, 1995 to April 16, 1995 du ring the rainy season the utilisation of edible snails was investigated in Indonesia. To assess the current situation, the focus was put to answer the following questions : - Is it feasible under the present circumstances to domesticate these snails with the aim to conserve the natural resources ? - Could any individual or private initiative be enhanced or utilized ? - Would local disadvantaged groups (traditional animal farmers, women oryouths be benefitted through domestication of these snails ? - Is there any existing private organisation or NGO, which already gathers and trades the snails or would be interested to do this in the future ? Snails gatherers, -dealers and -farmers were visited and interviewed on the following topics using standardised questionnaires : Spreading and ecology ways of marketing, consumption habits, breeding and rearing. Diotopes were also visited and investigated. Results Spreading and ecology : Achatina fulica, Pomacea canaliculata, Pila ampullacea and Bellamia javanica are eaten. The snails can be found ail overJava. Ways of marketing : The snails gathered in the biotope are either marketed directly or through various marketing paths. A. fulica is exported in large quantifies. The population is therefore endangered. Consumption habits : Snails are not eaten regularly. Snail meat is known to be healthy. The consumption depends on the consumer's ethnie background. Breeding and rearing experience : with simple breeding systems for A. fulica and P. canaliculata are seldom found. The breeding of P. canaliculata is forbidden in Indonesia. There is no interest in breeding P. ampullacea or B. javanica. The breeding of A. fulica can ben-efit disadvantaged groups financially and help to conserving the natural snail population.

  4. Miracidial infectivity of snail host ( Bulinus truncatus ) in the laboratory

    African Journals Online (AJOL)

    Miracidial infectivity rate of snail Bulinus truncatus collected from Agulu Lake was studied in the laboratory. The snails were maintained in the laboratory and eggs deposited were allowed to hatch and dates noted until snails of different ages were produced. These snails were consequently exposed to miracidia hatched ...

  5. Seasonal dynamics of snail populations in coastal Kenya: Model calibration and snail control

    Science.gov (United States)

    Gurarie, D.; King, C. H.; Yoon, N.; Wang, X.; Alsallaq, R.

    2017-10-01

    A proper snail population model is important for accurately predicting Schistosoma transmission. Field data shows that the overall snail population and that of shedding snails have a strong pattern of seasonal variation. Because human hosts are infected by the cercariae released from shedding snails, the abundance of the snail population sets ultimate limits on human infection. For developing a predictive dynamic model of schistosome infection and control strategies we need realistic snail population dynamics. Here we propose two such models based on underlying environmental factors and snail population biology. The models consist of two-stage (young-adult) populations with resource-dependent reproduction, survival, maturation. The key input in the system is seasonal rainfall which creates snail habitats and resources (small vegetation). The models were tested, calibrated and validated using dataset collected in Msambweni (coastal Kenya). Seasonal rainfall in Msambweni is highly variable with intermittent wet - dry seasons. Typical snail patterns follow precipitation peaks with 2-4-month time-lag. Our models are able to reproduce such seasonal variability over extended period of time (3-year study). We applied them to explore the optimal seasonal timing for implementing snail control.

  6. Multi-hump bright solitons in a Schrödinger-mKdV system

    Science.gov (United States)

    Cisneros-Ake, Luis A.; Parra Prado, Hugo; López Villatoro, Diego Joselito; Carretero-González, R.

    2018-03-01

    We consider the problem of energy transport in a Davydov model along an anharmonic crystal medium obeying quartic longitudinal interactions corresponding to rigid interacting particles. The Zabusky and Kruskal unidirectional continuum limit of the original discrete equations reduces, in the long wave approximation, to a coupled system between the linear Schrödinger (LS) equation and the modified Korteweg-de Vries (mKdV) equation. Single- and two-hump bright soliton solutions for this LS-mKdV system are predicted to exist by variational means and numerically confirmed. The one-hump bright solitons are found to be the anharmonic supersonic analogue of the Davydov's solitons while the two-hump (in both components) bright solitons are found to be a novel type of soliton consisting of a two-soliton solution of mKdV trapped by the wave function associated to the LS equation. This two-hump soliton solution, as a two component solution, represents a new class of polaron solution to be contrasted with the two-soliton interaction phenomena from soliton theory, as revealed by a variational approach and direct numerical results for the two-soliton solution.

  7. Analysis of vorticity dynamics for hump characteristics of a pump turbine model

    Energy Technology Data Exchange (ETDEWEB)

    Li, Deyou; Gong, Ruzhi; Wang, Hongjie; Han, Lei; Wei, Xianzhu; Qin, Daqing [School of Energy Science and Engineering, Harbin Institute of Technology, Harbin (China)

    2016-08-15

    Conventional parameters based on CFD methodology for the investigation on hump characteristics of a pump turbine cannot reflect the dynamic interaction mechanism between the runner and the fluid. This research presents a dynamic interaction mechanism of a pump turbine operating in the hump region. First, vorticity dynamic parameters were obtained based on the theory of vorticity dynamics. Second, 3-D unsteady flow simulations were performed in a full pump turbine model using the SST k-ω turbulence model, and numerical results have a good agreement with the experiments. Then, analysis was carried out to determine the relation between the vorticity dynamic parameters and hump characteristics. The results indicate that the theory of vorticity dynamics has an advantage in evaluating the dynamic performance of a pump turbine. The energy transfer between the runner and the fluid is through vorticity dynamic parameters-pressure and friction terms, in which the pressure term accounts for the most. Furthermore, vortex generation mainly results from the skin friction. Combining vorticity dynamic analysis with the method of Q-criterion indicates that hump characteristics are related to the reduction of the surface normal pressure work and vortex motion on the suction surfaces close to the leading edges in the runner, and the increase of skin friction work in the stay-guide vanes.

  8. Degree of Acetylization Chitosan Gonggong Snail Shells

    Science.gov (United States)

    Horiza, H.; Iskandar, I.; Aldo, N.

    2018-04-01

    Chitosan is a polysaccharide obtained from the deacetylation of chitin, which is generally derived from crustacean animal waste and animal skins other sea. One marine animals that have compounds that can be processed chitin chitosan is derived from the snail Gonggong marine waters of Riau Islands province. The purpose of this study was to determine the degree of chitosan from the shells of snails asetilisasi Gonggong. This research is an experimental research laboratory. The results of this study indicate that the degree of chitosan shell snail deasetilisasi Gonggong is 70.27%.

  9. Double hump sign in indentation gonioscopy is correlated with presence of plateau iris configuration regardless of patent iridotomy.

    Science.gov (United States)

    Kiuchi, Yoshiaki; Kanamoto, Takashi; Nakamura, Takao

    2009-02-01

    A plateau iris is one of the clinical forms of angle closure glaucoma. In patients with a patent iridotomy, the double hump sign detected during indentation gonioscopy has been reported to indicate the existence of a plateau iris configuration. The purpose of this study was to determine whether the double hump sign is correlated with the presence of the plateau iris syndrome regardless of the patency of the iridotomy. Five women and 3 men without a patent iridotomy presented with narrow angles on gonioscopy and a double hump sign on indentation gonioscopy. Ultrasound biomicroscopy (UBM) imaging was performed to determine the etiology of the narrow angle and double hump sign, and to determine the appropriate treatment to prevent the progression of visual field damage. Ten patients with narrow angles and without a double hump sign were also examined by UBM to serve as a control group. All 8 patients who showed double hump sign had a short iris root, which was inserted anterior to the ciliary face, a typical anatomic appearance of a plateau iris. On the other hand, only 1 eye of 10 eyes in control group appeared to have a plateau iris. A double hump sign observed on indentation gonioscopy is strongly correlated with the presence of a plateau iris, and therefore a useful indicator of a plateau iris configuration regardless of the patency of a laser iridotomy. Thus, a plateau iris configuration can be detected without using a UBM in many cases.

  10. 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...

  11. 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

    -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......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...... 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...

  12. 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.

  13. Short term performance and effect of speed humps on pavement condition of Alexandria Governorate roads

    Directory of Open Access Journals (Sweden)

    Wael Bekheet

    2014-12-01

    Some performance trends were observed and found to be statistically significant, including superior short-term performance of projects with good or average construction QC records when compared to poor construction QC records. Raveling was the most widely observed distress, while load-related distresses were not common. The analysis also showed that the presence of improper speed humps significantly affected the pavement condition, reducing the PCI of the pavement sections by up to 19 PCI points.

  14. Analysis of the flow close to a hump at the wall of a circular pipe

    International Nuclear Information System (INIS)

    Von Linsingen, I.; Silva Ferreira, R.T. da

    1981-01-01

    To study the laminar fully developed flow close to a circunferencial square hump placed at the wall of a smooth circular pipe is studied. An experimental set up was used to determine the reattachment legth and the velocity and shear stress profiles of the flow for different Reynolds numbers. Simple relations were obtained from the analysis of the data for the reattachment length, maximum velocity and maximum shear stress in different positions along the flow and different Reynolds numbers. (Author) [pt

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

    OpenAIRE

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

    2011-01-01

    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 me...

  16. Statistical model calculations with a double-humped fission barrier GIVAB computer code

    International Nuclear Information System (INIS)

    Delagrange, H.; Gilat, J.

    1979-01-01

    Neutron and gamma emission probabilities and fission probabilities are computed, taking into account the special feature of the actinide fission barriers with two maxima. Spectra and cross sections are directly deduced from these probabilities. Populations of both wells are followed step by step. For each initial E and J, decay rates are computed and normalized in order to obtain the de-excitation probabilities imposed by the two-humped fission barrier

  17. 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....

  18. The First Record of Linguatula serrata Infection of Two-Humped Camel (Camelus bactrinus In Iran

    Directory of Open Access Journals (Sweden)

    B Hajimohammadi

    2009-02-01

    Full Text Available "nLinguatula serrata, is a cosmopolitan zoonotic parasite. Adult of L. serrrata parasitize the nasopharynx of canids. Con­suming raw glandular material of infected intermediate hosts (camel, sheep, cattle, goat, etc. can infect human. In Iran, two-humped camel is merely found in cold regions (Ardabil and East Azarbijan provinces and is in danger of extinc­tion. A seven-year-old two-humped male camel, due to car accident injury was sent to slaughterhouse of Tabriz, Iran. In meat inspection practice, the visceral organs were taken out. A small red nodule having a white center was observed at the surface of the left lobe of lung. To study more, the whole of the left lobe of lung was sent to the parasitology labora­tory. One nymph of L. serrata was separated from the specimen. This is the first report of infection with L. serrate of two-humped camel in Iran.

  19. 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.

  20. Detection of Candida species by nested PCR method in one-humped camels (Camelus dromedarius).

    Science.gov (United States)

    Parin, Ugur; Erbas, Goksel; Kirkan, Sukru; Savasan, Serap; Tugba Yuksel, H; Balat, Gamze

    2018-02-01

    Systemic fungal diseases are the infections caused by false treatment protocols and generally are not taken into consideration especially in the veterinary field. One-humped camels are found in the western side of the Aegean region of our country and bred for wrestling. The aim of this study is the application of diagnosing systemic fungi infection from camel blood samples by the PCR method. In this study, specific primers for DNA topoisomerase II gene sequences were used. As a result, a systemic fungal infection was detected by the nested PCR method from 10 (20%) out of 50 DNA samples taken from camels located on the western side of the Aegean region. In this study, 3 (30%) samples were identified as Candida albicans, 3 (30%) samples were identified as C. glabrata, and 4 (40%) samples were identified as C. parapsilosis. In conclusion, the 20% positive systemic fungal infection rate in one-humped camels observed in the present study showed that the systemic fungal infections are not taken into considerations in veterinary medicine. Further studies are suggested in order to obtain and to maintain extensive data for systemic fungal diseases in our country for one-humped camels.

  1. Biochemical evaluation of aestivation and starvation in two snail ...

    African Journals Online (AJOL)

    hope&shola

    2010-11-08

    Nov 8, 2010 ... food uptake ceases, water loss occurs and the snails are not able to rid .... Fasting glucose decreased in both aestivating and starved B. rohlfsi snails ... significant muscle wastage during aestivation and starvation. It has been ...

  2. Nutritional Assessment of Some Nigerian Land and Water Snail ...

    African Journals Online (AJOL)

    Choice-Academy

    lapillus) snail species for nutritional assessment using their muscular foot tissues. The mean of ... Kwashiorkor is a protein – energy malnutrition that occurs ... analyses from the same pool of snails. ... due to the fact that swimming in water is a.

  3. 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

  4. Profitability of Snail Production in Osun State,Nigeria | Baba ...

    African Journals Online (AJOL)

    The study determined the features and profitability of snail farming in Osun State. To achieve the study objectives, 20 snail farmers each were randomly selected from Osogbo, Iwo and Ife-Ijesa townships, where majority of snail farmers in the State were located. Data collected from the farmers were analysed using ...

  5. Occurrence of digenean larvae in freshwater snails in the Ruvu ...

    African Journals Online (AJOL)

    Occurrence of digenean larvae in freshwater snails in the Ruvu basin, Tanzania. G Nkwengulila, ESP Kigadye. Abstract. A survey was carried out on digenean larvae infecting freshwater snails in five habitats in Dar es Salaam, Ruvu and Morogoro. 9424 snails belonging to 12 species from five families were examined for ...

  6. The occurrence of digenean larvae in freshwater snails at Mbezi ...

    African Journals Online (AJOL)

    The occurrence of digenean larvae in freshwater snails at Mbezi-Temboni pond, Dar es Salaam. ESP Kigadye, G Nkwengulila. Abstract. The abundance of digenean larvae in snails at a pond in Mbezi-Temboni, Dar es Salaam, was investigated from July 1996 to June 1997. A total of 2,112 snails belonging to three species, ...

  7. CYTOGENETIC STUDY OF FOUR SPECIES OF LAND SNAILS OF ...

    African Journals Online (AJOL)

    The chromosomal study of the four species of achatinid snails was carried out with the aim of determining their chromosome numbers as part of a preliminary attempt to understand the cytogenetics of land snails of Nigeria. The haploid chromosomes of various species of snails studied were obtained from their ovotestis ...

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

    African Journals Online (AJOL)

    The study investigates the determinants of productivity level among commercial snail farmers in Oyo State. A systematic sampling technique was employed to select one-hundred and forty–two snail farmers from the membership list provided by the Snail Farmers Association of Nigeria (SFAN), Oyo State Chapter.

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

    Directory of Open Access Journals (Sweden)

    Jiun-Jye Wang

    2011-05-01

    Full Text Available 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.

  10. Modeling snail breeding in a bioregenerative life support system

    Science.gov (United States)

    Kovalev, V. S.; Manukovsky, N. S.; Tikhomirov, A. A.; Kolmakova, A. A.

    2015-07-01

    The discrete-time model of snail breeding consists of two sequentially linked submodels: "Stoichiometry" and "Population". In both submodels, a snail population is split up into twelve age groups within one year of age. The first submodel is used to simulate the metabolism of a single snail in each age group via the stoichiometric equation; the second submodel is used to optimize the age structure and the size of the snail population. Daily intake of snail meat by crewmen is a guideline which specifies the population productivity. The mass exchange of the snail unit inhabited by land snails of Achatina fulica is given as an outcome of step-by-step modeling. All simulations are performed using Solver Add-In of Excel 2007.

  11. First report on circulation of Echinococcus ortleppi in the one humped camel (Camelus dromedaries), Sudan.

    Science.gov (United States)

    Ahmed, Mohamed E; Eltom, Kamal H; Musa, Nasreen O; Ali, Ibtisam A; Elamin, Fatima M; Grobusch, Martin P; Aradaib, Imadeldin E

    2013-06-25

    Echinococcus granulosus (EG) complex, the cause of cystic echinococcosis (CE), infects humans and several other animal species worldwide and hence the disease is of public health importance. Ten genetic variants, or genotypes designated as (G1-G10), are distributed worldwide based on genetic diversity. The objective of this study was to provide some sequence data and phylogeny of EG isolates recovered from the Sudanese one-humped camel (Camelus dromedaries). Fifty samples of hydatid cysts were collected from the one- humped camels (Camelus dromedaries) at Taboul slaughter house, central Sudan. DNAs were extracted from protoscolices and/or associated germinal layers of hydatid cysts using a commercial kit. The mitochondrial NADH dehydrogenase subunit 1 (NADH1) gene and the cytochrome C oxidase subunit 1 (cox1) gene were used as targets for polymerase chain reaction (PCR) amplification. The PCR products were purified and partial sequences were generated. Sequences were further examined by sequence analysis and subsequent phylogeny to compare these sequences to those from known strains of EG circulating globally. The identity of the PCR products were confirmed as NADH1 and cox1 nucleotide sequences using the Basic Local Alignment Search Tool (BLAST) of NCBI (National Center for Biotechnology Information, Bethesda, MD). The phylogenetic analysis showed that 98% (n = 49) of the isolates clustered with Echinococcus canadensis genotype 6 (G6), whereas only one isolate (2%) clustered with Echinococcus ortleppi (G5). This investigation expands on the existing sequence data generated from EG isolates recovered from camel in the Sudan. The circulation of the cattle genotype (G5) in the one-humped camel is reported here for the first time.

  12. Optimal stocking densities of snails [ Archachatina marginata ...

    African Journals Online (AJOL)

    Optimal stocking densities of breeding and fattening snails [Archachatina marginata Saturalis A.m.s (Swainson)] were determined through two experiments (five treatments, four replicates and randomised complete block design each) between April and December 1998.Experiment 1 had 3,6, 12, 17 and 22 A.m.s. adult ...

  13. Biosorption of radionuclides by snail shell biomass

    International Nuclear Information System (INIS)

    Dhami, P.S.; Chaudhari, S.D.; Rathinam, M.; Gopalakrishnan, V.; Ramanujam, A.

    2001-01-01

    The sorption of various radionuclides from low acidic and alkaline medium was studied using biomass of snail shell origin. Quantitative removal of plutonium was achieved when an alkaline waste effluents of PUREX origin at pH 9.4 was treated using this biomass. The sorbed activity was recovered by dissolving it in 1.0 M nitric acid. (author)

  14. 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.

  15. 4 Prevalence of Snail.cdr

    African Journals Online (AJOL)

    Administrator

    Kpong head pond is a lake system that was created just below the Kpong dam. The high occurrence of B. trunctus found by this study, coupled with the intense human activity that occurs at the banks of the head pond, indicates that an active transmission of S. haematobiumparasite occurs in the area. The snails were ...

  16. 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...

  17. Reynolds-Averaged Navier-Stokes Analysis of Zero Efflux Flow Control over a Hump Model

    Science.gov (United States)

    Rumsey, Christopher L.

    2006-01-01

    The unsteady flow over a hump model with zero efflux oscillatory flow control is modeled computationally using the unsteady Reynolds-averaged Navier-Stokes equations. Three different turbulence models produce similar results, and do a reasonably good job predicting the general character of the unsteady surface pressure coefficients during the forced cycle. However, the turbulent shear stresses are underpredicted in magnitude inside the separation bubble, and the computed results predict too large a (mean) separation bubble compared with experiment. These missed predictions are consistent with earlier steady-state results using no-flow-control and steady suction, from a 2004 CFD validation workshop for synthetic jets.

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

    OpenAIRE

    A. Bello; B.I. Onyeanusi; M.L. Sonfada; J.B. Adeyanju; M.A. Umaru

    2012-01-01

    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...

  19. Optimal systematics of single-humped fission barriers for statistical calculations

    International Nuclear Information System (INIS)

    Mashnik, S.G.

    1993-01-01

    A systematic comparison of the existing phenomenological approaches and models for describing single-humped fast-computing fission barriers are given. The experimental data on excitation energy dependence of the fissility of compound nuclei are analyzed in the framework of the statistical approach by using different models for fission barriers, shell and pairing corrections and level-density parameter in order to identify their reliability and region of applicability for Monte Carlo calculations of evaporative cascades. The energy dependence of fission cross-sections for reactions induced by intermediate energy protons has been analyzed in the framework of the cascade-exiton model. 53 refs., 15 figs., 3 tabs

  20. 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.

  1. Parasites of edible land snails in Edo State, Nigeria

    Directory of Open Access Journals (Sweden)

    Igbinosa I. B.

    2016-12-01

    Full Text Available Land snails are sources of protein to man and are hosts to a number of parasites. It is imperative that the roles of the snail hosts and parasites are clearly defined. Before then however, the parasites of the different land snails collected in any locality should be identified. Land snails were collected in the wild in both dry and wet seasons. The internal organs and the faeces were examined for the presence of parasite. In the rainy season of 2015, a total of 272 snails were collected across four major towns (Benin, Uromi, Ekpoma and Auchi in Edo State, Nigeria, while in the dry season, fewer snails (n=91 were handpicked. The snail species seen are: Achatina achatina (Linnaeus, 1758, Achatina fulica (Férussac, 1821, Acharchatina marginata (Swainson, 1982, Limicolaria aurora (Jay, 1839, L. flammea (Müller, 1774 and Limicolariopsis spp. The larvae of Strongyloides stercoralis were isolated from the various snail species with overall prevalence of 54.04 %. Snails positive with Alaria mesocercariae were L. aurora, L. flammea and Limicolariopsis spp. Additionally, few L. flammea were positive of the cercariae of Drocoelium dedriticum. Meanwhile, some samples of A. fulica harboured larvae of Angiostrongylus cantonesis, sporocysts of Fasciola gigantica and Schistosoma mansoni. Therefore, these edible snails could pose serious health hazard to man and animals by serving as a possible alternative parasite transmission route.

  2. Microangiopathic Hemolytic Anemia Following Three Different Species of Hump-Nosed Pit Viper (Genus: Hypnale) Envenoming in Sri Lanka.

    Science.gov (United States)

    Namal Rathnayaka, Rathnayaka Mudiyanselage M K; Ranathunga, Anusha Nishanthi; Kularatne, Senanayake A M; Rajapakse, Jayanthe; Ranasinghe, Shirani; Jayathunga, Radha

    2018-03-01

    There are 3 species of hump-nosed pit vipers in Sri Lanka: Hypnale hypnale, Hypnale zara, and Hypnale nepa. The latter 2 are endemic to the country. Microangiopathic hemolytic anemia (MAHA) is a known complication of hump-nosed pit viper bites. It was previously documented as a complication of general viper bites and not species specific. We report a series of 3 patients who developed MAHA after being bitten by each species of hump-nosed pit viper. The first patient was bitten by H hypnale and developed a severe form of MAHA associated with acute kidney injury and thrombocytopenia falling into the category of thrombotic microangiopathy. The other 2 developed MAHA that resolved without any complications. Copyright © 2017 Wilderness Medical Society. Published by Elsevier Inc. All rights reserved.

  3. Performance of Reynolds Averaged Navier-Stokes Models in Predicting Separated Flows: Study of the Hump Flow Model Problem

    Science.gov (United States)

    Cappelli, Daniele; Mansour, Nagi N.

    2012-01-01

    Separation can be seen in most aerodynamic flows, but accurate prediction of separated flows is still a challenging problem for computational fluid dynamics (CFD) tools. The behavior of several Reynolds Averaged Navier-Stokes (RANS) models in predicting the separated ow over a wall-mounted hump is studied. The strengths and weaknesses of the most popular RANS models (Spalart-Allmaras, k-epsilon, k-omega, k-omega-SST) are evaluated using the open source software OpenFOAM. The hump ow modeled in this work has been documented in the 2004 CFD Validation Workshop on Synthetic Jets and Turbulent Separation Control. Only the baseline case is treated; the slot flow control cases are not considered in this paper. Particular attention is given to predicting the size of the recirculation bubble, the position of the reattachment point, and the velocity profiles downstream of the hump.

  4. 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.

  5. 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.

  6. 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.

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

    DEFF Research Database (Denmark)

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

    2016-01-01

    than the larger snails. We evaluated the effect of control measures on six populations having >1000 adult snails and used data from the two largest populations to investigate how environmental factors (temperature, humidity, and rainfall) interacted with population dynamics and control measures. More......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...

  8. 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.

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

    DEFF Research Database (Denmark)

    Haahr, Jørgen Thorlund; Lusby, Richard Martin

    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......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...

  10. 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.

  11. 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

  12. Nutritive potentials and utilization of garden snail (Limicolaria aurora ...

    African Journals Online (AJOL)

    AJB SERVER

    2006-10-16

    Oct 16, 2006 ... The possibility of using garden snail (Limicolaria aurora) meat meal as a protein source in fish feeds was tested in ... garden snail meat meal was used to replace fish meal at 0%, (control diet), 25, 50, 75 and 100% inclusion ..... Randall DJ, Brett JR (eds) Fish Physiology, Academic Press, NY 8: 279-352,.

  13. 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

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

    African Journals Online (AJOL)

    The socio-economic characteristic of snail farmers in Oyo State Agricultural Development Programme (ADP) was evaluated in two out of the four zones that were available. The two zones selected were Ibadan/Ibarapa and Oyo zones, to determine the factors related to snail production, consumption and marketing in the ...

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

    NARCIS (Netherlands)

    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, D.C.; 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

    2017-01-01

    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

  16. Nutritive potentials and utilization of garden snail (Limicolaria aurora ...

    African Journals Online (AJOL)

    The possibility of using garden snail (Limicolaria aurora) meat meal as a protein source in fish feeds was tested in Clarias gariepinus fingerlings. Five isonitrogenous (43% crude protein) diets in which garden snail meat meal was used to replace fish meal at 0%, (control diet), 25, 50, 75 and 100% inclusion levels were used ...

  17. Snail arboreality: the microdistribution of Sitala jenynsi (Gastropoda ...

    African Journals Online (AJOL)

    The habitats and patterns of vertical migration of the shell banding morphs of the snail Sitala jenynsi (Pfeiffer) were studied in Dar es Salaam and Wazo regions of central coastal Tanzania Both dimorphic and trimorphic populations were arboreal throughout the year. The snails occurred randomly within mid-heights 180 to ...

  18. 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...

  19. 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.

  20. Land Snail Extinctions at Kalaeloa, O`ahu

    Directory of Open Access Journals (Sweden)

    T.S. Dye

    2001-06-01

    Full Text Available In this article we show that the interpretation of Polynesian influence drawn from the stratigraphic record of sub-fossil land snails at Kalaeloa (O'ahu, Hawai'i is based on a unique stratigraphic sequence at a single sinkhole. The interpretation was then applied to other land snail sequences, despite their lack of evidence for Polynesian influence. We present a reanalysis of the stratigraphic record to conclude that Polynesians had little, if any, effect on land snail populations in sinkholes. We show that directional change in land snail populations was underway before Polynesians colonised the islands. Decreases in the diversity of snail populations, possibly indicative of environmental stress, do occur near the end of the stratigraphic sequence. Based on available dating evidence, however, these changes probably took place in the post-Contact period when the regional environment was radically altered by sugar cane cultivation.

  1. 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

    ponds. Previous risk assessment on FZT transmission in the Red River Delta of Vietnam identified carp nursery ponds as major sites of transmission. In this study, we analyzed the association between snail population density and heterophyid trematode infection in snails with the rate of FZT transmission...... to juvenile fish raised in carp nurseries....

  2. A survey of snail farms in Cross River State, Nigeria | Ogogo | Global ...

    African Journals Online (AJOL)

    The existence of snail in the wild has become threatened, and information on the efficiency and effectiveness of ex - situ management of snails in many areas is urgently needed for consistent supply of snails. This work, therefore surveyed the practice and adoption of snail farming technology in Cross River State, Nigeria.

  3. Loss of Snail2 favors skin tumor progression by promoting the recruitment of myeloid progenitors

    DEFF Research Database (Denmark)

    Villarejo, Ana; Molina-Ortiz, Patricia; Montenegro, Yenny

    2015-01-01

    showed that loss of Snail2 leads to a decrease in proliferation indicating a non-cell autonomous role for Snail2 in the skin carcinogenic response observed in vivo. Bone marrow (BM) cross-reconstitution assays between Snail2 wild-type and null mice showed that Snail2 absence in the hematopoietic system...

  4. Ecological and morphological patterns in communities of land snails of the genus Mandarina from the Bonin Islands.

    Science.gov (United States)

    Chiba, Satoshi

    2004-01-01

    The land snail genus Mandarina has undergone extensive radiation within the Bonin Islands in the west Pacific. The preferred above-ground vegetation heights of sympatric species were clearly different. They separated into arboreal, semi-arboreal, exposed ground and sheltered ground ecotypes. Shells of species with different ecotypes differ markedly, but shells of species with the same ecotype are very similar to each other. Shell morphologies of some phylogenetically distantly related species with the same ecotype were indistinguishable. Character evolution estimated parsimoniously using a phylogenetic tree suggests that the speciation among sympatric species is accompanied by ecological and morphological diversification. In addition, species coexistence of Mandarina is related to niche differentiation. The above findings suggest that ecological interactions among species contribute to the ecological and morphological diversification and radiation of these land snails in this depauperate environment.

  5. 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

  6. Interactions between freshwater snails and tadpoles: competition and facilitation.

    Science.gov (United States)

    Brönmark, Christer; Rundle, Simon D; Erlandsson, Ann

    1991-06-01

    Freshwater snails and anuran tadpoles have been suggested to have their highest population densities in ponds of intermediate size where abiotic disturbance (e.g. desiccation) is low and large predators absent. Both snails and tadpoles feed on periphytic algae and, thus, there should be a large potential for competitive interactions to occur between these two distantly related taxa. In a field experiment we examined the relative strength of competition between two closely related snail species, Lymnaea stagnalis and L. peregra, and between L. stagnalis and tadpoles of the common frog, Rana temporaria. Snail growth and egg production and tadpole size at and time to metamorphosis were determined. Effects on the common food source, periphyton, were monitored with the aid of artificial substrates. Periphyton dry weight was dramatically reduced in the presence of snails and/or tadpoles. There were no competitive effects on growth or egg production of the two snail species when they were coexisting. Mortality of L. peregra was high (95%) after reproduction, but independent of treatment. Growth of L. stagnalis was reduced only at the highest tadpole densities, whereas egg production was reduced both by intraspecific competition and by competition with tadpoles. Differences in egg production were retained after tadpole metamorphosis. Tadpole larval period increased, weight of metamorphosing frogs decreased and growth rate was reduced as a function of increasing tadpole density. However, contrary to expectation, snails had a positive effect on tadpole larval period, weight and growth rate. Further, in experimental containers without snails there was a dense growth of the filamentous green alga Cladophora sp. We suggest that the facilitative effects of snails on tadpoles are due to an "indirect mutualistic" mechanism, involving competition between food sources of different quality (microalgae and Cladophora sp.) and tadpoles being competitively dominant over snails for the

  7. Triple-humped fission barrier model for a new {sup 238}U neutron cross-section evaluation and first validations

    Energy Technology Data Exchange (ETDEWEB)

    Lopez Jimenez, M.J. [CEA/DIF/DPTA/Service de Physique Nucleaire, B.P. 12, F-91680 Bruyeres-le-Chatel (France); Morillon, B. [CEA/DIF/DPTA/Service de Physique Nucleaire, B.P. 12, F-91680 Bruyeres-le-Chatel (France); Romain, P. [CEA/DIF/DPTA/Service de Physique Nucleaire, B.P. 12, F-91680 Bruyeres-le-Chatel (France)]. E-mail: pascal.romain@cea.fr

    2005-01-15

    A new neutron-induced cross-section evaluation of {sup 238}U from 1 keV up to 200 MeV has been performed using only nuclear reactions models. A new fission penetrability model taking into account a triple humped barrier has been developed. A clear improvement has been observed for K-effective validation tests (up to 30 MeV) with this new evaluation. This improvement is mainly due to a better treatment of the inelastic exit channel.

  8. Generalized double-humped logistic map-based medical image encryption

    Directory of Open Access Journals (Sweden)

    Samar M. Ismail

    2018-03-01

    Full Text Available This paper presents the design of the generalized Double Humped (DH logistic map, used for pseudo-random number key generation (PRNG. The generalized parameter added to the map provides more control on the map chaotic range. A new special map with a zooming effect of the bifurcation diagram is obtained by manipulating the generalization parameter value. The dynamic behavior of the generalized map is analyzed, including the study of the fixed points and stability ranges, Lyapunov exponent, and the complete bifurcation diagram. The option of designing any specific map is made possible through changing the general parameter increasing the randomness and controllability of the map. An image encryption algorithm is introduced based on pseudo-random sequence generation using the proposed generalized DH map offering secure communication transfer of medical MRI and X-ray images. Security analyses are carried out to consolidate system efficiency including: key sensitivity and key-space analyses, histogram analysis, correlation coefficients, MAE, NPCR and UACI calculations. System robustness against noise attacks has been proved along with the NIST test ensuring the system efficiency. A comparison between the proposed system with respect to previous works is presented.

  9. 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.

  10. Special cutaneous vascular elements in one-humped camel (Camelus dromedarius

    Directory of Open Access Journals (Sweden)

    Mohammad Rashad Fath-Elbab

    2016-06-01

    Full Text Available Objective: The aim of this study was to investigate the histomorphological structure and functional significance of various special regulatory devices of the vascular terminal branches of the skin in one-humped camel (Camelus dromedarius. Materials and methods: Skin samples from different body parts (e.g., front, neck and shoulder, back, belly, chest, thigh, flank and tail of camel were used in this study. The samples were stained with Harris hematoxylin and trichrome stain. Semithin sections were also prepared from these samples. Results: The vascular elements demonstrated in the current study included- throttle arteries within the dermis on the level of the hair papillae, glomus bodies within the dermis on the level mid-length of the hair follicles, medium-sized arteries on the level of the secretory end-pieces of the epitrichial sweat glands, and tufts of spirally-oriented arterioles in the nearby of the hair follicles. Conclusions: These vascular elements are either designed to control blood pressure (Hemo-dynamic mechanism or patterned to control body temperature (Thermo-regulatory mechanism. [J Adv Vet Anim Res 2016; 3(2.000: 106-111

  11. 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.

  12. Flow Physics and Scaling for Discrete Jet Forcing on a Wall-Mounted Hump

    Science.gov (United States)

    Otto, Christopher; Tewes, Philipp; Little, Jesse

    2017-11-01

    An experimental study is conducted to explore flow physics and scaling parameters (e.g., aspect ratio, exit area, spacing) for steady jets and fluidic oscillators in support of the development of active flow control technology. Various actuation modules are designed, built and tested on an existing model of the NASA hump geometry. Experiments are carried out at a Reynolds numbers of 1.0 .106 (Ma = 0.09). Time-averaged pressure measurements are conducted along both the chord and span of the model. Stereo PIV is performed downstream of the actuation location to investigate the underlying control mechanisms in more detail. Separation control using spatially distributed steady round jet forcing was applied successfully for a spacing of Δz / c = 1.14 % for Cμ > 0.9 % . A larger spacing (Δz / c = 2.27 %) did not allow for full reattachment and led to 3D behavior in the separated region and also slightly upstream of the actuation. Fluidic oscillators showed control authority for Cμ >= 0.6 % for both presented spacings (Δz / c = 2.27 % and Δz / c = 4.54 %). In contrast to the 3D effects observed with steady jets, the fluidic oscillators provided a more uniform reduction in separation at a significantly lower Cμ even for larger spacing.

  13. 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...

  14. Potentiation of zinc stress caused by parastic infection of snails

    Energy Technology Data Exchange (ETDEWEB)

    Guth, D.J. (Univ. of Michigan, Flint); Blankespoor, H.D.; Cairns, J. Jr.

    1977-09-08

    The purpose of this experiment was to determine the effects of parasitism (Schistosomatium douthitti Price and Trichobilharzia sp.) on the tolerance of snails Lymnaea stagnalis (L.) to acutely lethal concentrations of zinc. Significant reduction in tolerance occurred for snails with patent infections at 24 and 75 ppM of Zn/sup + +/. At two selected prepatent levels of parasite development, significant differences occurred at the higher concentration only.

  15. Modulation of defensive reflex conditioning in snails by serotonin

    Science.gov (United States)

    Andrianov, Vyatcheslav V.; Bogodvid, Tatiana K.; Deryabina, Irina B.; Golovchenko, Aleksandra N.; Muranova, Lyudmila N.; Tagirova, Roza R.; Vinarskaya, Aliya K.; Gainutdinov, Khalil L.

    2015-01-01

    Highlights Daily injection of serotonin before a training session accelerated defensive reflex conditioning in snails.Daily injection of 5-hydroxytryptophan before a training session in snails with a deficiency of serotonin induced by the “neurotoxic” analog of serotonin 5,7-dihydroxytryptamine, restored the ability of snails to learn.After injection of the “neurotoxic” analogs of serotonin 5,6- and 5,7-dihydroxytryptamine as well as serotonin, depolarization of the membrane and decrease of the threshold potential of premotor interneurons was observed. We studied the role of serotonin in the mechanisms of learning in terrestrial snails. To produce a serotonin deficit, the “neurotoxic” analogs 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 2 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. PMID:26557063

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

    Directory of Open Access Journals (Sweden)

    Mandë Holford

    2009-11-01

    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.

  17. X-Rays from the Location of the Double-humped Transient ASASSN-15lh

    Science.gov (United States)

    Margutti, R.; Metzger, B. D.; Chornock, R.; Milisavljevic, D.; Berger, E.; Blanchard, P. K.; Guidorzi, C.; Migliori, G.; Kamble, A.; Lunnan, R.; Nicholl, M.; Coppejans, D. L.; Dall'Osso, S.; Drout, M. R.; Perna, R.; Sbarufatti, B.

    2017-02-01

    We present the detection of persistent soft X-ray radiation with {L}x˜ {10}41-1042 erg s-1 at the location of the extremely luminous, double-humped transient ASASSN-15lh as revealed by Chandra and Swift. We interpret this finding in the context of observations from our multiwavelength campaign, which revealed the presence of weak narrow nebular emission features from the host-galaxy nucleus and clear differences with respect to superluminous supernova optical spectra. Significant UV flux variability on short timescales detected at the time of the rebrightening disfavors the shock interaction scenario as the source of energy powering the long-lived UV emission, while deep radio limits exclude the presence of relativistic jets propagating into a low-density environment. We propose a model where the extreme luminosity and double-peaked temporal structure of ASASSN-15lh is powered by a central source of ionizing radiation that produces a sudden change in the ejecta opacity at later times. As a result, UV radiation can more easily escape, producing the second bump in the light curve. We discuss different interpretations for the intrinsic nature of the ionizing source. We conclude that, if the X-ray source is physically associated with the optical-UV transient, then ASASSN-15lh most likely represents the tidal disruption of a main-sequence star by the most massive spinning black hole detected to date. In this case, ASASSN-15lh and similar events discovered in the future would constitute the most direct probes of very massive, dormant, spinning, supermassive black holes in galaxies. Future monitoring of the X-rays may allow us to distinguish between the supernova hypothesis and the hypothesis of a tidal disruption event.

  18. 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.

  19. Crimean Congo hemorrhagic fever among the one-humped camel (Camelus dromedaries) in Central Sudan.

    Science.gov (United States)

    Suliman, Hajer M; Adam, Ibrahim A; Saeed, Shamseldin I; Abdelaziz, Sanaa A; Haroun, Eltahir M; Aradaib, Imadeldin E

    2017-08-03

    Crimean-Congo hemorrhagic fever (CCHF) is a tick-borne viral zoonotic disease caused by Crimean-Congo hemorrhagic fever virus (CCHFV), a member of the genus Nairovirus in the family Bunyaviridae. CCHF is typically asymptomatic in animals but can be highly fatal in humans approaching case fatality rate of approximately 30%. In the present investigation, a cross sectional study was conducted to determine the prevalence of CCHF and to identify the potential risk factors associated with CCHFV seropositivity among the one-humped camel (Camelus dromedaries) in Central Sudan. A total of 361 camels selected randomly from six localities were employed in the study. Sera sampled were tested for the presence of CCHFV-specific immunoglobulin G (IgG) antibodies using enzyme-linked immunosorbent assay (ELISA). CCHFV seropositivity was recorded in 77 out of 361 animals accounting for a prevalence rate of 21.3%. Age (OR = 3.6, CI = 1.72-7.79, p-value = 0.026); locality (OR = 5.85, CI = 1.81-18.83, p- value = 0.003), tick number (OR = 4.6, CI = 1.37-9.81, P-value 0.04); tick control (OR = 2.2, CI, 1.11-4.35, P-value = 0.023) and breed (OR = 6.60, CI = 2.38-18.36, P-value = 0.001) were recorded as potential risk factors for contracting CCHF. The prevalence of CCHF is significantly high among camels in Khartoum State, Sudan. Age, breed, locality and tick control are considered as potential risk factors for contracting CCHF. This study would be expected to reduce the impact on the livelihood of pastoral communities and ultimately avoid disease spread in human.

  20. [Phylogenetic analysis of CO I gene of Oncomelania snails from project of afforestation for schistosomiasis control in marshland endemic regions].

    Science.gov (United States)

    Xu, Yu-Mei; Zhang, Shi-Qing; Zhu, Chuan-Gang

    2012-04-01

    To investigate the genetic difference of cytochrome oxidase I (CO I ) of Oncomelania snails from the project of afforestation for schistosomiasis control in marshland regions, so as to explore the effects of different ecological environments. The snails were collected from 3 different areas, Anqing, Tongling, Wuwei, i.e. the upstream, midstream and downstream regions along the Yangtz River in Anhui Province. Genomic DNA was extracted from the snails, and CO I gene fragments were amplified by PCR, then purified and sequenced. The sequences were edited by using Blast. The CO I genes of O. h. minima and Biomphalaria glabrata were used as the reference of exogenous gene. The genetic distances of the various regions were calculated by the Kimura method and phylogenetic trees were constructed with UPGMA and the NJ method of MEGA (3.1) software. The amplified CO I gene of the snail was a fragment about 700 bp including 2 primers in length. There were little genetic diversity among the different areas, the identities were higher than or equal to 98%. The genetic distances indicated that the distance between the projects of afforestation and woodland in Anqing was 0.003, while Tongling was 0.019, Wuwei was 0.007. The distances among the three projects of afforestation were 0.003-0.012. The two phylogenetic trees were constructed by the methods of UPGMA and NJ respectively, which took on very similar topo-structure in which isolates of Biomphalaria glabrata located in one clade and all the others in the other one. In the other one clade, O. H. minima located in one clade. There was little genetic diversity among Anqing, Tongling, Wuwei clusters. The afforestations of Anqing and Wuwei clustered into one group, while the woodlands of Anqing and Wuwei appeared as another group. There is a little genetic diversity of the snail cytochrome oxidase I (CO I ) in different ecological environments among the upstream, midstream and downstream regions along the Yangtz River in Anhui

  1. [Analysis of trend of Oncomelania snail status in Yangtze River valley of Anhui Province, 1998-2009].

    Science.gov (United States)

    He, Jia-Chang; Wang, Jia-Sheng; Lu, Jin-You; Li, Ting-Ting; Gao, Feng-Hu; Zhou, Ping; Zhu, Chuan-Ming; He, Long-Zhu; Yu, Bei-Bei; Zhang, Shi-Qing

    2011-04-01

    To understand the trend of Oncomelania hupensis snail distribution in Yangtze River valley of Anhui Province so as to provide an evidence for making out schistosomiasis prevention and control strategies in the future. The snail data from 1998 to 2009 of the Yangtze River valley in Anhui Province were collected including the snail area, newly occurred and re-occurred snail areas, densities of snails and infected snails, etc., and the trend and influence factors were analyzed. With several fluctuations, the snail area showed a trend of declining in general after the devastating summer flooding in 1998. From 1998 to 2009, 3 peaks of newly occurred snail areas appeared in 1998, 2004 and 2006 and 2 peaks of reoccurred snail areas appeared in 1998 and 2004. The densities of living snails and infected snails were more severe in banks of the Yangtze River than in islets of the Yangtze River. During 12 years, 1 peak of living snail density appeared in 2003, and 3 peaks of infected snail density appeared in 1999, 2003-2004 and 2006 in the islets of the Yangtze River. The densities of living snails and infected snails in banks of the Yangtze both appeared 1 peak in 1998. The distribution of snails in the Yangtze River valley is related to nature, society and financial circumstances, and it is hard to completely perform the snail control in a short-term. Therefore, at the same time of strengthening snail control, we should also strengthen infectious source control.

  2. Reproductive Ecology of the Giant African Snail in South Florida: Implications for Eradication Programs.

    Directory of Open Access Journals (Sweden)

    Amy Roda

    Full Text Available 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 (1000 adult snails and used data from the two largest populations to investigate how environmental factors (temperature, humidity, and rainfall interacted with population dynamics and control measures. More snails were collected in weeks with high humidity and more gravid snails were collected when the temperature was higher. The addition of metaldehyde pesticides had the greatest impact on population dynamics by reducing snail numbers. In populations with fewer snails, their numbers were already declining before the use of metaldehyde, although the new treatment accelerated the process. As a consequence of the eradication program, egg-producing snails were no longer collected from most populations by the end of the study. The aggressive and persistent control efforts apparently lead to reduced populations of egg producing snails, eventually resulting in local extinctions of this important pest.

  3. Reproductive Ecology of the Giant African Snail in South Florida: Implications for Eradication Programs

    Science.gov (United States)

    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 (1000 adult snails and used data from the two largest populations to investigate how environmental factors (temperature, humidity, and rainfall) interacted with population dynamics and control measures. More snails were collected in weeks with high humidity and more gravid snails were collected when the temperature was higher. The addition of metaldehyde pesticides had the greatest impact on population dynamics by reducing snail numbers. In populations with fewer snails, their numbers were already declining before the use of metaldehyde, although the new treatment accelerated the process. As a consequence of the eradication program, egg-producing snails were no longer collected from most populations by the end of the study. The aggressive and persistent control efforts apparently lead to reduced populations of egg producing snails, eventually resulting in local extinctions of this important pest. PMID:27861504

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

    International Nuclear Information System (INIS)

    Cohen-Taguri, G.; Ruzin, A.; Goldfarb, I.

    2012-01-01

    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.

  5. Effect of Age on Fiber Characteristics of one-humped Female Camels of Semnan Province (Short article

    Directory of Open Access Journals (Sweden)

    H.R Ansari Renani

    2012-01-01

    Full Text Available The aim of this study was to determine the effect of age on fiber characteristics of one-humped female camels of Semnan province. 50 grams of wool samples from the left midside area were randomly collected from 28 camels of three different age groups: young, adult and old and fibre characteristics were measured. Statistical model used for this research was completely randomized design (CRD. Analysis of data and comparison of means were performed using Duncan's new multiple range test. The results showed that staple length and cashmere percent in young camels were significantly (P

  6. 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.

  7. Destructive role of hot ions in the formation of electrostatic density humps and dips in dusty plasmas

    International Nuclear Information System (INIS)

    Mahmood, S.; Saleem, H.

    2003-01-01

    It is shown that the ion thermal energy is destructive for the ion acoustic solitons in the presence of dust, and it decreases the value of Mach number for the formation of solitary structures. The regions of ion density humps and dips are produced simultaneously, corresponding to positive and negative values of the electrostatic potential. The nonlinear electron density also behaves in a similar fashion as that of ions. However, the dust density increases in the regions where the ion and electron densities are depleted and vice versa

  8. Venoms of South Asian hump-nosed pit vipers (Genus: Hypnale cause muscarinic effects in BALB/c mice

    Directory of Open Access Journals (Sweden)

    A Silva

    2014-03-01

    Full Text Available Although clinical, in-vivo and in-vitro studies suggest the necrotic, haemorrhagic, pro-coagulant and nephrotoxic effects of South Asian Hump nosed pit vipers, reports on neurotoxic properties are limited to a single in-vitro study. Using BALB/c mice, for the first time, here we demonstrate the signs of envenoming suggestive of possible muscarinic effects of the venoms of all three Hypnale species. Further, we demonstrate that the muscarinic effects are occurred at lower venom doses by H. hypnale venom, compared to H. nepa and H. zara.

  9. [Application of electronic fence technology based on GIS in Oncomelania hupensis snail monitoring].

    Science.gov (United States)

    Zhi-Hua, Chen; Yi-Sheng, Zhu; Zhi-Qiang, Xue; Xue-Bing, Li; Yi-Min, Ding; Li-Jun, Bi; Kai-Min, Gao; You, Zhang

    2017-07-27

    To study the application of Geographic Information System (GIS) electronic fence technique in Oncomelania hupensis snail monitoring. The electronic fence was set around the history and existing snail environments in the electronic map, the information about snail monitoring and controlling was linked to the electronic fence, and the snail monitoring information system was established on these bases. The monitoring information was input through the computer and smart phone. The electronic fence around the history and existing snail environments was set in the electronic map (Baidu map), and the snail monitoring information system and smart phone APP were established. The monitoring information was input and upload real-time, and the snail monitoring information was demonstrated in real time on Baidu map. By using the electronic fence technology based on GIS, the unique "environment electronic archives" for each snail monitoring environment can be established in the electronic map, and real-time, dynamic monitoring and visual management can be realized.

  10. Analysis of land snail marketing in Owerri agricultural zone of Imo ...

    African Journals Online (AJOL)

    Analysis of land snail marketing in Owerri agricultural zone of Imo state, ... The study was conducted in Owerri Agricultural Zone of Imo state, Nigeria to assess the profitability of snail marketing during ... EMAIL FULL TEXT EMAIL FULL TEXT

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

    Directory of Open Access Journals (Sweden)

    Cho Hee Kim

    2011-03-01

    Full Text Available 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.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.Taken together, our findings demonstrate that Snail is implicated in metabolic stress-induced necrosis, providing a new function for Snail in tumor progression.

  12. Venomics-Accelerated Cone Snail Venom Peptide Discovery

    Science.gov (United States)

    Himaya, S. W. A.

    2018-01-01

    Cone snail venoms are considered a treasure trove of bioactive peptides. Despite over 800 species of cone snails being known, each producing over 1000 venom peptides, only about 150 unique venom peptides are structurally and functionally characterized. To overcome the limitations of the traditional low-throughput bio-discovery approaches, multi-omics systems approaches have been introduced to accelerate venom peptide discovery and characterisation. This “venomic” approach is starting to unravel the full complexity of cone snail venoms and to provide new insights into their biology and evolution. The main challenge for venomics is the effective integration of transcriptomics, proteomics, and pharmacological data and the efficient analysis of big datasets. Novel database search tools and visualisation techniques are now being introduced that facilitate data exploration, with ongoing advances in related omics fields being expected to further enhance venomics studies. Despite these challenges and future opportunities, cone snail venomics has already exponentially expanded the number of novel venom peptide sequences identified from the species investigated, although most novel conotoxins remain to be pharmacologically characterised. Therefore, efficient high-throughput peptide production systems and/or banks of miniaturized discovery assays are required to overcome this bottleneck and thus enhance cone snail venom bioprospecting and accelerate the identification of novel drug leads. PMID:29522462

  13. ATM-mediated Snail Serine 100 phosphorylation regulates cellular radiosensitivity

    International Nuclear Information System (INIS)

    Boohaker, Rebecca J.; Cui, Xiaoli; Stackhouse, Murray; Xu, Bo

    2013-01-01

    Purpose: Activation of the DNA damage responsive protein kinase ATM is a critical step for cellular survival in response to ionizing irradiation (IR). Direct targets of ATM regulating radiosensitivity remain to be fully investigated. We have recently reported that ATM phosphorylates the transcriptional repressor Snail on Serine 100. We aimed to further study the functional significance of ATM-mediated Snail phosphorylation in response to IR. Material and methods: We transfected vector-only, wild-type, the Serine 100 to alanine (S100A) or to glutamic acid (S100E) substitution of Snail into various cell lines. We assessed colony formation, γ-H2AX focus formation and the invasion index in the cells treated with or without IR. Results: We found that over-expression of the S100A mutant Snail in HeLa cells significantly increased radiosensitivity. Meanwhile the expression of S100E, a phospho-mimicking mutation, resulted in enhanced radio-resistance. Interestingly, S100E could rescue the radiosensitive phenotype in ATM-deficient cells. We also found that expression of S100E increased γ-H2AX focus formation and compromised inhibition of invasion in response to IR independent of cell survival. Conclusion: ATM-mediated Snail Serine 100 phosphorylation in response to IR plays an important part in the regulation of radiosensitivity

  14. Venomics-Accelerated Cone Snail Venom Peptide Discovery

    Directory of Open Access Journals (Sweden)

    S. W. A. Himaya

    2018-03-01

    Full Text Available Cone snail venoms are considered a treasure trove of bioactive peptides. Despite over 800 species of cone snails being known, each producing over 1000 venom peptides, only about 150 unique venom peptides are structurally and functionally characterized. To overcome the limitations of the traditional low-throughput bio-discovery approaches, multi-omics systems approaches have been introduced to accelerate venom peptide discovery and characterisation. This “venomic” approach is starting to unravel the full complexity of cone snail venoms and to provide new insights into their biology and evolution. The main challenge for venomics is the effective integration of transcriptomics, proteomics, and pharmacological data and the efficient analysis of big datasets. Novel database search tools and visualisation techniques are now being introduced that facilitate data exploration, with ongoing advances in related omics fields being expected to further enhance venomics studies. Despite these challenges and future opportunities, cone snail venomics has already exponentially expanded the number of novel venom peptide sequences identified from the species investigated, although most novel conotoxins remain to be pharmacologically characterised. Therefore, efficient high-throughput peptide production systems and/or banks of miniaturized discovery assays are required to overcome this bottleneck and thus enhance cone snail venom bioprospecting and accelerate the identification of novel drug leads.

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

    Directory of Open Access Journals (Sweden)

    Bruno Bonnemain

    2005-01-01

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

  16. Parametric Study of Flow Control Over a Hump Model Using an Unsteady Reynolds- Averaged Navier-Stokes Code

    Science.gov (United States)

    Rumsey, Christopher L.; Greenblatt, David

    2007-01-01

    This is an expanded version of a limited-length paper that appeared at the 5th International Symposium on Turbulence and Shear Flow Phenomena by the same authors. A computational study was performed for steady and oscillatory flow control over a hump model with flow separation to assess how well the steady and unsteady Reynolds-averaged Navier-Stokes equations predict trends due to Reynolds number, control magnitude, and control frequency. As demonstrated in earlier studies, the hump model case is useful because it clearly demonstrates a failing in all known turbulence models: they under-predict the turbulent shear stress in the separated region and consequently reattachment occurs too far downstream. In spite of this known failing, three different turbulence models were employed to determine if trends can be captured even though absolute levels are not. Overall the three turbulence models showed very similar trends as experiment for steady suction, but only agreed qualitatively with some of the trends for oscillatory control.

  17. 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.

  18. 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

  19. MTA3 regulates CGB5 and Snail genes in trophoblast

    International Nuclear Information System (INIS)

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

    2013-01-01

    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

  20. Effect of radiation on Lymnnea auricularia rubiginosa snails

    International Nuclear Information System (INIS)

    Cruz, B. de la; Yumul, B.V.; Anden, A.; Perpuse, W.G.

    1976-03-01

    As a means of checking the spread of fascioliasis, the intermediate host of F. hepatica and F. gigantica which is the Lumnea auricularia rubiginosa is exposed to different doses of radioisotopes. Radioisotopes used were 32 P, 3 H-thymidine, and 137 Cs. Findings show that at different concentration and doses of radioisotopes, there is a reduced viability and increase mortality in the eggs laid by the parent snails exposed to radiation. The effects on the development of irradiated eggs are also being studied as well as the effects of irradiation on the reproductive apparatus of the snails

  1. 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.

  2. 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.

  3. Computational analysis of locally forced flow over a wall-mounted hump at high-Re number

    International Nuclear Information System (INIS)

    Saric, S.; Jakirlic, S.; Djugum, A.; Tropea, C.

    2006-01-01

    An incompressible, high-Reynolds number flow (slightly less then 1 Mio. per chord) over a smoothly contoured, asymmetric, wall-mounted hump was computationally studied using the LES (large eddy simulation) and DES (detached eddy simulation) methods. In addition, several second-moment and eddy-viscosity closures within the RANS (Reynolds-averaged Navier-Stokes) framework were tested. The focus of the investigation was on the effects of local perturbation of the hump boundary layer introduced by spatially uniform (in the spanwise direction) steady suction and oscillatory suction/blowing through a narrow opening (1.7 mm) situated at the hump crest immediately upstream of the natural separation point. Reference experiments have shown that both flow control mechanisms cause a shortening of the recirculation bubble relative to the baseline configuration with no flow control. All statistical turbulence models used in the RANS framework resulted in a substantially larger recirculation zone independent of the modelling level, being a consequence of a too low turbulence level in the separated shear layer. Accordingly, the effect of the steady suction, namely the reduction of the reattachment length, was underpredicted. The LES method, despite a relatively coarse mesh (with a total of 4 Mio. cells) for such a high-Reynolds number, wall-bounded flow, was capable of capturing important effects of the flow control qualitatively and quantitatively. DES failed to do so in the suction case, despite good results in the baseline and oscillatory blowing/suction cases, indicating that a shallow separation from curved surfaces poses a challenge to this hybrid RANS/LES strategy. A sensitivity study of the RANS/LES interface position within the DES approach shows that a RANS region chosen too thin (with the interface situated at the very beginning of the logarithmic layer) can lead to a strong reduction of the turbulent viscosity causing a low turbulence level within the shear layer

  4. 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 (P<0.05). Different habitats had different snail 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, P<0.05), underscoring the possible influence of species interaction on B.s. goniomphalos snail 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

  5. Flowering Trees

    Indian Academy of Sciences (India)

    Flowering Trees. Boswellia serrata Roxb. ex Colebr. (Indian Frankincense tree) of Burseraceae is a large-sized deciduous tree that is native to India. Bark is thin, greenish-ash-coloured that exfoliates into smooth papery flakes. Stem exudes pinkish resin ... Fruit is a three-valved capsule. A green gum-resin exudes from the ...

  6. Flowering Trees

    Indian Academy of Sciences (India)

    IAS Admin

    Flowering Trees. Ailanthus excelsa Roxb. (INDIAN TREE OF. HEAVEN) of Simaroubaceae is a lofty tree with large pinnately compound alternate leaves, which are ... inflorescences, unisexual and greenish-yellow. Fruits are winged, wings many-nerved. Wood is used in making match sticks. 1. Male flower; 2. Female flower.

  7. Flowering Trees

    Indian Academy of Sciences (India)

    Flowering Trees. Gyrocarpus americanus Jacq. (Helicopter Tree) of Hernandiaceae is a moderate size deciduous tree that grows to about 12 m in height with a smooth, shining, greenish-white bark. The leaves are ovate, rarely irregularly ... flowers which are unpleasant smelling. Fruit is a woody nut with two long thin wings.

  8. Flowering Trees

    Indian Academy of Sciences (India)

    More Details Fulltext PDF. Volume 8 Issue 8 August 2003 pp 112-112 Flowering Trees. Zizyphus jujuba Lam. of Rhamnaceae · More Details Fulltext PDF. Volume 8 Issue 9 September 2003 pp 97-97 Flowering Trees. Moringa oleifera · More Details Fulltext PDF. Volume 8 Issue 10 October 2003 pp 100-100 Flowering Trees.

  9. A snail-eating snake recognizes prey handedness.

    Science.gov (United States)

    Danaisawadi, Patchara; Asami, Takahiro; Ota, Hidetoshi; Sutcharit, Chirasak; Panha, Somsak

    2016-04-05

    Specialized predator-prey interactions can be a driving force for their coevolution. Southeast Asian snail-eating snakes (Pareas) have more teeth on the right mandible and specialize in predation on the clockwise-coiled (dextral) majority in shelled snails by soft-body extraction. Snails have countered the snakes' dextral-predation by recurrent coil reversal, which generates diverse counterclockwise-coiled (sinistral) prey where Pareas snakes live. However, whether the snake predator in turn evolves any response to prey reversal is unknown. We show that Pareas carinatus living with abundant sinistrals avoids approaching or striking at a sinistral that is more difficult and costly to handle than a dextral. Whenever it strikes, however, the snake succeeds in predation by handling dextral and sinistral prey in reverse. In contrast, P. iwasakii with little access to sinistrals on small peripheral islands attempts and frequently misses capturing a given sinistral. Prey-handedness recognition should be advantageous for right-handed snail-eating snakes where frequently encountering sinistrals. Under dextral-predation by Pareas snakes, adaptive fixation of a prey population for a reversal gene instantaneously generates a sinistral species because interchiral mating is rarely possible. The novel warning, instead of sheltering, effect of sinistrality benefitting both predators and prey could further accelerate single-gene ecological speciation by left-right reversal.

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

    African Journals Online (AJOL)

    SARAH

    2014-12-01

    Dec 1, 2014 ... Thus, to optimize the use of snail's shells in areas such as agricultural production ... The data collected focused on (1) stakeholders marketing system of the ... gathered was used to establish the general sales channel from the ...

  11. 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 ...

  12. Differences in predatory pressure on terrestrial snails by birds and ...

    Indian Academy of Sciences (India)

    Supplementary table 2. Number of collected individuals of particular morph categories of C. nemoralis and C. hortensis with specification of undamaged and damaged snails. Morph. Total number of individuals. Undamaged individuals. Shells damaged by. Mice. Birds. Mouse + bird. Cepaea nemoralis. 732. 172. 105. 436.

  13. The role of snail aestivation in transmission of schistosomiasis in ...

    African Journals Online (AJOL)

    Aestivation therefore plays an important role in maintaining the transmission of schistosomiasis. This review assesses the possible impacts of climate change on the temporal and spatial distribution of schistosomiasis-transmitting snails with special emphasis on aestivation, and discusses the effect of schistosome infection ...

  14. Ecology and distribution of gastropod snails of medical and ...

    African Journals Online (AJOL)

    A study on the ecology and distribution of snails of medical importance was conducted in water bodies from four different communities (Old Karmo, Gwagwa, ... The following floras were identified from the study-sites; Megathyrsus maximus, Guinea grass and Commelina nigritana (African dayflower) were identified from the ...

  15. 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.

  16. 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 of a...

  17. Response of Oncomelania snail distribution on land use in Sichuan ...

    African Journals Online (AJOL)

    Response of Oncomelania snail distribution on land use in Sichuan, China. Q Sun, Z Peng, J Zhang, J Jiang. Abstract. Schistosomiasis is one of the four major infectious diseases that require prevention and control in China. It is mainly distributed along the middle and downstream areas of the Yangtze River and some hilly ...

  18. Freshwater snail distribution related to environmental factors in ...

    African Journals Online (AJOL)

    This station which received domestic sewage from the neighbouring cities was characterized by the highest conductivity and pH and the lowest values of dissolved oxygen. Multiple stepwise regression analysis showed that snail densities were probably influenced by conductivity, dissolved oxygen, pH, and canopy cover.

  19. Growth, Age Determination and Longevity in the Giant African Snail ...

    African Journals Online (AJOL)

    Growth rates in terms of shell lengths were investigated in four subspecies of Archachatina marginata (Swainson) under culture conditions. Number of shell whorls, shell pigmentation and microsculpture were also studied to assess their usefulness in age determination. The snails displayed a sigmoid growth pattern, with ...

  20. Nonlinear permittivity spectra of supercooled ionic liquids: Observation of a "hump" in the third-order permittivity spectra and comparison to double-well potential models.

    Science.gov (United States)

    Patro, L N; Burghaus, O; Roling, B

    2017-04-21

    We have measured the third-order permittivity spectra ε 3 3 of a monocationic and of a dicationic liquid close to the glass transition temperature by applying ac electric fields with large amplitudes up to 180 kV/cm. A peak ("hump") in the modulus of ε 3 3 is observed for a mono-cationic liquid after subtraction of the dc contribution from the imaginary part of ε 3 3 . We show that the origin of this experimental "hump" is a peak in the imaginary part of ε 3 3 , with the peak height strongly increasing with decreasing temperature. Overall, the spectral shape of the third-order permittivity of both ionic liquids is similar to the predictions of a symmetric double well potential model, although this model does not predict a "hump" in the modulus. In contrast, an asymmetric double well potential model predicts a "hump," but the spectral shape of both the real and imaginary part of ε 3 3 deviates significantly from the experimental spectra. These results show that not only the modulus of ε 3 3 but also its phase is an important quantity when comparing experimental results with theoretical predictions.

  1. 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.

  2. 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...

  3. 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...

  4. 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. Copyright © 2011 Australian Society for Parasitology Inc. All rights reserved.

  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. Snail recruits Ring1B to mediate transcriptional repression and cell migration in pancreatic cancer cells.

    Science.gov (United States)

    Chen, Jiangzhi; Xu, Hong; Zou, Xiuqun; Wang, Jiamin; Zhu, Yi; Chen, Hao; Shen, Baiyong; Deng, Xiaxing; Zhou, Aiwu; Chin, Y Eugene; Rauscher, Frank J; Peng, Chenghong; Hou, Zhaoyuan

    2014-08-15

    Transcriptional repressor Snail is a master regulator of epithelial-mesenchymal transition (EMT), yet the epigenetic mechanism governing Snail to induce EMT is not well understood. Here, we report that in pancreatic ductal adenocarcinoma (PDAC), elevated levels of the ubiquitin E3 ligase Ring1B and Snail, along with elevated monoubiquitination of H2A at K119 (H2AK119Ub1), are highly correlated with poor survival. Mechanistic investigations identified Ring1B as a Snail-interacting protein and showed that the carboxyl zinc fingers of Snail recruit Ring1B and its paralog Ring1A to repress its target promoters. Simultaneous depletion of Ring1A and Ring1B in pancreatic cancer cells decreased Snail binding to the target chromatin, abolished H2AK119Ub1 modification, and thereby compromised Snail-mediated transcriptional repression and cell migration. We found that Ring1B and the SNAG-associated chromatin modifier EZH2 formed distinct protein complexes with Snail and that EZH2 was required for Snail-Ring1A/B recruitment to the target promoter. Collectively, our results unravel an epigenetic mechanism underlying transcriptional repression by Snail, suggest Ring1A/B as a candidate therapeutic target, and identify H2AK119Ub1 as a potential biomarker for PDAC diagnosis and prognosis. ©2014 American Association for Cancer Research.

  7. The suitability of several aquatic snails as intermediate hosts for Angiostrongylus cantonensis.

    Science.gov (United States)

    Yousif, F; Lämmler, G

    1975-10-16

    Sixteen species of aquatic snails of four families were tested by quantitative technique under standardized conditions for their suitability as intermediate hosts for Angiostrongylus cantonensis. These species were the planorbid snails Biomphalaria glabrata, Biomphalaria alexandrina, Planorbis planorbis, Planorbis intermixtus, Bulinus truncatus, Bulinus contortus, Bulinus africanus, Bulinus tropicus and Helisoma sp.; the lymnaeid snails Lymnaea natalensis, Lymnaea tomentosa, Lymnaea stagnalis, and Stagnicola elodes; the physid snail Physa acuta (an Egyptian and a German strain) and the ampullariid snails Marisa cornuarietis and Lanistes carinatus. All these snail species proved to be susceptible to infection with A. cantonensis, and first stage larvae reached the infective third stage in all of them. However, the rate and intensity of infection varied with different species. B. glabrata was the most susceptible snail species with a 100% infection rate and an average percentage recovery of third stage larvae of 26.1. This was followed by S. elodes and B. africanus, with a 100% infection rate and an average percentage recovery of third stage larvae of 15.6 and 14.6 respectively. The rest of snail species proved to be less susceptible. For comparative evaluation of the suitability of the various snail species as intermediate hosts of A. cantonensis a "Capacity Index" was determined. This index should provide a useful method for the evaluation of the suitability of various snails as intermediate hosts of nematode parasites under standardized conditions in the laboratory.

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

    International Nuclear Information System (INIS)

    Li, Hui; Li, Min; Xu, Ding; Zhao, Chun; Liu, Guodong; Wang, Fang

    2014-01-01

    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

  9. Why abundant tropical tree species are phylogenetically old.

    Science.gov (United States)

    Wang, Shaopeng; Chen, Anping; Fang, Jingyun; Pacala, Stephen W

    2013-10-01

    Neutral models of species diversity predict patterns of abundance for communities in which all individuals are ecologically equivalent. These models were originally developed for Panamanian trees and successfully reproduce observed distributions of abundance. Neutral models also make macroevolutionary predictions that have rarely been evaluated or tested. Here we show that neutral models predict a humped or flat relationship between species age and population size. In contrast, ages and abundances of tree species in the Panamanian Canal watershed are found to be positively correlated, which falsifies the models. Speciation rates vary among phylogenetic lineages and are partially heritable from mother to daughter species. Variable speciation rates in an otherwise neutral model lead to a demographic advantage for species with low speciation rate. This demographic advantage results in a positive correlation between species age and abundance, as found in the Panamanian tropical forest community.

  10. 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.

  11. Arsenic transfer and impacts on snails exposed to stabilized and untreated As-contaminated soils

    Energy Technology Data Exchange (ETDEWEB)

    Coeurdassier, M.; Scheifler, R.; Mench, M.; Crini, N.; Vangronsveld, J.; de Vaufleury, A. [Universite de Franche-Comte, Besancon (France)

    2010-06-15

    An As-contaminated soil (Unt) was amended with either iron grit (Z), a coal fly ash (beringite, B) or B + Z (BZ) and placed in lysimeters in 1997. An uncontaminated soil (R) was also studied. In summer and autumn 2003, lettuces were cultivated in the lysimeters and snails were caged for one month. Lettuce As concentrations were higher during the summer, while no differences occurred in snails between seasons. Snail As concentrations ({mu} g g{sup -1} DW) ranged from 2.5 to 7.0 in B, Z and BZ, and peaked at 17.5 in Unt. In summer, snail survival was affected in Unt and Z compared to R and B while no mortality was noticed in autumn. Snail growth decreased only in B, BZ and Unt in autumn. Snail As concentrations suggest a risk for their predators even on the remediated soils.

  12. Survival, growth and reproduction of the imported ampullarid snail Marisa cornuarietis in Central Sudan.

    Science.gov (United States)

    Haridi, A A; el Safi, S H; Jobin, W R

    1985-04-01

    The ampullarid snail Marisa cornuarietis was imported to the Sudan in 1981 for evaluation as a biological control agent against the planorbid snails which transmit human schistosomes. In initial field studies in small protected ponds the generation time of M. cornuarietis was 4 months, as in Puerto Rico. The snails reached 4 cm in diameter after 1 year, compared to 3 cm in Puerto Rico. Their population density varied from 60 to 175 snails per metre of shore-line, compared to a similar pond in Puerto Rico where the stable density was about 115 snails per metre. The proportion surviving after 1 year was 0.03, less than the annual proportion surviving of 0.10 in Puerto Rico. Thus the preliminary results indicated that the ampullarid snails could establish strong populations in permanent habitats in central Sudan where there was adequate food, although it might take longer than it does in Puerto Rico.

  13. Effects of Snail Density on Growth, Reproduction and Survival of Biomphalaria alexandrina Exposed to Schistosoma mansoni

    Directory of Open Access Journals (Sweden)

    T. D. Mangal

    2010-01-01

    Full Text Available The effects of snail density on Biomphalaria alexandrina parasitized with Schistosoma mansoni were investigated. Laboratory experiments were used to quantify the impact of high density on snail growth, fecundity, and survival. Density-dependent birth rates of snails were determined to inform mathematical models, which, until now, have assumed a linear relationship between density and fecundity. The experiments show that the rate of egg-laying followed a negative exponential distribution with increasing density and this was significantly affected by exposure to parasitic infection. High density also affected the weight of snails and survival to a greater degree than exposure to parasitic infection. Although snail growth rates were initially constrained by high density, they retained the potential for growth suggesting a reversible density-dependent mechanism. These experimental data can be used to parameterise models and confirm that snail populations are regulated by nonlinear density-dependent mechanisms.

  14. Tree Nut Allergies

    Science.gov (United States)

    ... Blog Vision Awards Common Allergens Tree Nut Allergy Tree Nut Allergy Learn about tree nut allergy, how ... a Tree Nut Label card . Allergic Reactions to Tree Nuts Tree nuts can cause a severe and ...

  15. 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.

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

    Science.gov (United States)

    Williams, Dana E; Miller, Margaret W; Bright, Allan J; Cameron, Caitlin M

    2014-01-01

    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 m(2) 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 m(2) 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.

  17. Impact and cost-effectiveness of snail control to achieve disease control targets for schistosomiasis

    OpenAIRE

    Lo, Nathan C.; Gurarie, David; Yoon, Nara; Coulibaly, Jean T.; Bendavid, Eran; Andrews, Jason R.; King, Charles H.

    2018-01-01

    Schistosomiasis is a parasitic disease that affects over 240 million people globally. To improve population-level disease control, there is growing interest in adding chemical-based snail control interventions to interrupt the lifecycle of Schistosoma in its snail host to reduce parasite transmission. However, this approach is not widely implemented, and given environmental concerns, the optimal conditions for when snail control is appropriate are unclear. We assessed the potential impact and...

  18. The transcription factor snail controls epithelial-mesenchymal transitions by repressing E-cadherin expression

    DEFF Research Database (Denmark)

    Cano, A; Pérez-Moreno, M A; Rodrigo, I

    2000-01-01

    The Snail family of transcription factors has previously been implicated in the differentiation of epithelial cells into mesenchymal cells (epithelial-mesenchymal transitions) during embryonic development. Epithelial-mesenchymal transitions are also determinants of the progression of carcinomas......, occurring concomitantly with the cellular acquisition of migratory properties following downregulation of expression of the adhesion protein E-cadherin. Here we show that mouse Snail is a strong repressor of transcription of the E-cadherin gene. Epithelial cells that ectopically express Snail adopt...

  19. Deposition of strontium and calcium in snail shell

    Energy Technology Data Exchange (ETDEWEB)

    Rosenthal, Jr, G M; Nelson, D J; Gardiner, D A

    1965-07-03

    The relative effects of strontium and calcium concentrations in the environment on their uptake and incorporation into snail shell were investigated. /sup 45/Ca and /sup 85/Sr were used as tracers and specific activities were used to determine deposition. Data are presented in tables and graphs. Deposition of both calcium and strontium in the snail shell depended primarily on the respective concentrations of these elements in the immediate environment. A slight effect of strontium on calcium deposition was observed. There was found to be a minimum strontium deposition for various combinations of strontium and calcium in the environment. It was concluded that strontium uptake is more closely associated with environmental strontium concentrations than with calcium concentrations.

  20. Biological control and invading freshwater snails. A case study.

    Science.gov (United States)

    Pointier, J P; Augustin, D

    1999-12-01

    Introductions of four species of freshwater snails occurred between 1972 and 1996 onto Guadeloupe Island. Two of them, Melanoides tuberculata and Marisa cornuarietis, were subsequently used as biological control agents against Biomphalaria glabrata, the snail intermediate host of intestinal schistosomiasis. In 1996, a general survey was carried out in 134 sites which had already been investigated in 1972. The total number of mollusc species had increased from 19 to 21. Site numbers housing B. glabrata and two other species had strongly declined. This decline may be mainly attributed to a competitive displacement by M. tuberculata and M. cornuarietis as illustrated by several biological control programmes. There were no changes in the remainder of the malacological fauna.

  1. 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. Copyright © 2014 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved.

  2. 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.

  3. Effects of an invasive ant on land snails in the Ogasawara Islands.

    Science.gov (United States)

    Uchida, Shota; Mori, Hideaki; Kojima, Tsubasa; Hayama, Kayo; Sakairi, Yuko; Chiba, Satoshi

    2016-12-01

    We investigated how Pheidole megacephala has affected endemic achatinellid snails because these snails are excellent indicators of the impact of ants and they have high conservation value in Ogasawara. In 2015 we surveyed the Minamizaki area of Hahajima Island of Ogasawara, designated a core zone of the World Heritage Site, for P. megacephala. In Minamizaki, we determined the distribution and density of achatinellid snails in 2015 and compared these data with their distribution and density in 2005. Land cover in the survey area was entirely forest. We also tested whether P. megacephala preyed on achatinellid snails in the laboratory. P. megacephala was present in the forested areas of Minamizaki. Achatinellid snails were absent in 19 of 39 sites where P. megacephala was present, whereas in other areas densities of the snails ranged from 2 to 228 individuals/site. In the laboratory, P. megacephala carried 6 of 7 achatinellid snails and a broken shell was found. Snail distribution and density comparisons and results of the feeding experiments suggest that the presence of P. megacephala has contributed to the decline of achatinellid snails in forests in the survey area. Yet, P. megacephala is not on the official list of invasive non-native species. Stakeholders using the list of invasive species to develop conservation programs should recognize that invasiveness of non-native species differs depending on the ecosystem and that official lists may not be complete. © 2016 Society for Conservation Biology.

  4. Trace metallic elements in Helix aspersa terrestrial snails of a semiarid ecosystem

    International Nuclear Information System (INIS)

    Gaso P, M.I.; Segovia, N.; Zarazua, G.; Montes, F.; Morton, O.; Armienta, M.A.; Hernandez, E.

    2001-01-01

    The concentration of some major elements and traces in soil samples and of Helix aspersa eatable terrestrial snails were analysed at the Radioactive Wastes Storage Center (CADER) and in other reference sites. The methodology includes the use of an atomic absorption spectrophotometer, an X-ray fluorescence equipment and an Icp-mass spectroscope. The concentrations of some toxic elements (Ba, Cd, Cr, Ni, Pb and V) in the soft tissue of the snails were greater than the toxic levels reported in the literature for such trace elements. The snails compared with another wild eatable foods present transfer coefficients soil-snail high relatively. (Author)

  5. [Effect of agroforestry model on inhibition of Oncomelania snails in plateau mountainous area of Yunnan Province].

    Science.gov (United States)

    Zhang, Chun-Hua; Tang, Guo-Yong; Liu, Fang-Yan; Li, Kun

    2012-10-01

    To evaluate the effect of agroforestry models on the inhibition of Oncomelania snails in the plateau mountainous area of Yunnan Province. The experimental field was established at Sanying Village of Eryuan County, Yunnan Province, where the "Flourishing Forest and Controlling Snails Project" was implemented. Different drought crops (alfalfa, vegetables, broad bean, garlic, lettuce, celery, green onions, and wheat) were intercropped under walnut forest in experimental groups, and the crops were not intercropped under walnut forest in a control group. The growth of forest, the change of snails and short-term income of residents were investigated. Agroforestry models promoted the forestry growth and effectively inhibited the growth of snails. There was a little snail in one of the experimental group that forest was intercropped with alfalfa (the occurrence rate of frames with living snails was 3.33%, the average density of living snails was 0.004/0.1 m2, and the declining rates were both 50.00%). The snails were not found in other intercropped models. The income of residents in the experimental groups increased (900-6 800 Yuan per year) compared with that in the control group. The model of walnut forest intercropped with crops not only has the obvious effect on inhibition of snails, but also has good economic and ecological benefits in the plateau mountainous area of Yunnan Province.

  6. Diet quality affects chemical tolerance in the freshwater snail Lymnaea stagnalis.

    Science.gov (United States)

    Fidder, Bridgette N; Reátegui-Zirena, Evelyn G; Salice, Christopher J

    2018-04-01

    Organisms generally select high-quality diets to obtain maximal energy while devoting the least amount of time and energy. Diets, however, can vary in natural systems. In ecotoxicological testing, the effect of diet type on organismal responses to toxicants has not been explored despite the potential for dietary effects to influence toxicological endpoints. We first evaluated diet quality using growth rate and sensitivity to the fungicide pyraclostrobin of Lymnaea stagnalis fed lettuce (common laboratory diet), turtle pellets (high nutrient composition), and a combination diet of both food items. We also measured the macronutrient content of snails raised on the multiple diets to determine how diet may have impacted energy allocation patterns. Finally, we evaluated whether snails discernibly preferred a particular diet. Snails fed high-nutrient and combination diets grew larger overall than snails fed a lettuce-only diet. Snails fed the high-nutrient and combination diets, both juvenile and adult, were significantly more tolerant to pyraclostrobin than snails fed lettuce. When measured for macronutrient content, snails raised on high-nutrient and combination diets had significantly higher carbohydrate content than snails fed lettuce. Despite the strong effects of diet type, snails did not exhibit a clear diet choice in preference trials. Dietary composition clearly influences growth rate, sensitivity, and macronutrient content of Lymnaea stagnalis. These results suggest that the nutritional environment has potentially strong impacts on toxicant sensitivity. Environ Toxicol Chem 2018;37:1158-1167. © 2017 SETAC. © 2017 SETAC.

  7. Flowering Trees

    Indian Academy of Sciences (India)

    medium-sized handsome tree with a straight bole that branches at the top. Leaves are once pinnate, with two to three pairs of leaflets. Young parts of the tree are velvety. Inflorescence is a branched raceme borne at the branch ends. Flowers are large, white, attractive, and fragrant. Corolla is funnel-shaped. Fruit is an ...

  8. Flowering Trees

    Indian Academy of Sciences (India)

    Cassia siamia Lamk. (Siamese tree senna) of Caesalpiniaceae is a small or medium size handsome tree. Leaves are alternate, pinnately compound and glandular, upto 18 cm long with 8–12 pairs of leaflets. Inflorescence is axillary or terminal and branched. Flowering lasts for a long period from March to February. Fruit is ...

  9. Flowering Trees

    Indian Academy of Sciences (India)

    Flowering Trees. Cerbera manghasL. (SEA MANGO) of Apocynaceae is a medium-sized evergreen coastal tree with milky latex. The bark is grey-brown, thick and ... Fruit is large. (5–10 cm long), oval containing two flattened seeds and resembles a mango, hence the name Mangas or. Manghas. Leaves and fruits contain ...

  10. Flowering Trees

    Indian Academy of Sciences (India)

    user

    Flowering Trees. Gliricidia sepium(Jacq.) Kunta ex Walp. (Quickstick) of Fabaceae is a small deciduous tree with. Pinnately compound leaves. Flower are prroduced in large number in early summer on terminal racemes. They are attractive, pinkish-white and typically like bean flowers. Fruit is a few-seeded flat pod.

  11. Flowering Trees

    Indian Academy of Sciences (India)

    Flowering Trees. Acrocarpus fraxinifolius Wight & Arn. (PINK CEDAR, AUSTRALIAN ASH) of. Caesalpiniaceae is a lofty unarmed deciduous native tree that attains a height of 30–60m with buttresses. Bark is thin and light grey. Leaves are compound and bright red when young. Flowers in dense, erect, axillary racemes.

  12. 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…

  13. Drawing Trees

    DEFF Research Database (Denmark)

    Halkjær From, Andreas; Schlichtkrull, Anders; Villadsen, Jørgen

    2018-01-01

    We formally prove in Isabelle/HOL two properties of an algorithm for laying out trees visually. The first property states that removing layout annotations recovers the original tree. The second property states that nodes are placed at least a unit of distance apart. We have yet to formalize three...

  14. Flowering Trees

    Indian Academy of Sciences (India)

    Srimath

    Grevillea robusta A. Cunn. ex R. Br. (Sil- ver Oak) of Proteaceae is a daintily lacy ornamental tree while young and growing into a mighty tree (45 m). Young shoots are silvery grey and the leaves are fern- like. Flowers are golden-yellow in one- sided racemes (10 cm). Fruit is a boat- shaped, woody follicle.

  15. Function of insulin in snail brain in associative learning.

    Science.gov (United States)

    Kojima, S; Sunada, H; Mita, K; Sakakibara, M; Lukowiak, K; Ito, E

    2015-10-01

    Insulin is well known as a hormone regulating glucose homeostasis across phyla. Although there are insulin-independent mechanisms for glucose uptake in the mammalian brain, which had contributed to a perception of the brain as an insulin-insensitive organ for decades, the finding of insulin and its receptors in the brain revolutionized the concept of insulin signaling in the brain. However, insulin's role in brain functions, such as cognition, attention, and memory, remains unknown. Studies using invertebrates with their open blood-vascular system have the promise of promoting a better understanding of the role played by insulin in mediating/modulating cognitive functions. In this review, the relationship between insulin and its impact on long-term memory (LTM) is discussed particularly in snails. The pond snail Lymnaea stagnalis has the ability to undergo conditioned taste aversion (CTA), that is, it associatively learns and forms LTM not to respond with a feeding response to a food that normally elicits a robust feeding response. We show that molluscan insulin-related peptides are up-regulated in snails exhibiting CTA-LTM and play a key role in the causal neural basis of CTA-LTM. We also survey the relevant literature of the roles played by insulin in learning and memory in other phyla.

  16. 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.

  17. Direct numerical simulation of a compressible boundary-layer flow past an isolated three-dimensional hump in a high-speed subsonic regime

    Science.gov (United States)

    De Grazia, D.; Moxey, D.; Sherwin, S. J.; Kravtsova, M. A.; Ruban, A. I.

    2018-02-01

    In this paper we study the boundary-layer separation produced in a high-speed subsonic boundary layer by a small wall roughness. Specifically, we present a direct numerical simulation (DNS) of a two-dimensional boundary-layer flow over a flat plate encountering a three-dimensional Gaussian-shaped hump. This work was motivated by the lack of DNS data of boundary-layer flows past roughness elements in a similar regime which is typical of civil aviation. The Mach and Reynolds numbers are chosen to be relevant for aeronautical applications when considering small imperfections at the leading edge of wings. We analyze different heights of the hump: The smaller heights result in a weakly nonlinear regime, while the larger result in a fully nonlinear regime with an increasing laminar separation bubble arising downstream of the roughness element and the formation of a pair of streamwise counterrotating vortices which appear to support themselves.

  18. 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

  19. 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...

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

    Directory of Open Access Journals (Sweden)

    Iman F. Abou-El-Naga

    2012-09-01

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

  1. Effect of dystocia on some hormonal and biochemical parameters in the one-humped camel (Camelus dromedarius).

    Science.gov (United States)

    Ghoneim, I M; Waheed, M M; Al-Eknah, M M; Al-Raja'a, A

    2016-08-01

    The present study compared some of the hormonal and biochemical constituents of serum from eutocic and dystocic one-humped camels (Camelus dromedarius). Sera were harvested from eutocic (n = 9) and dystocic (n = 20) camels within the first 15 minutes after delivery. Although there were no differences in the concentrations of estradiol-17β (E2) and prostaglandin F2α (PGF2α) between the eutocic and the dystocic animals, the level of progesterone (P4) and cortisol was significantly higher (P dystocia than those that had a normal birth. There were no differences between the concentrations of alkaline phosphatase, aspartate aminotransferase, calcium, cholesterol, creatine kinase, creatinine, or magnesium (Mg) in eutocic and dystocic animals. The nitric oxide concentration was significantly higher (P dystocia than those that had normal births. By contrast, the serum concentrations of glucose, phosphorus (P), and triglycerides were significantly lower (P dystocia. Moreover, stress and hormonal changes may affect the metabolic traits in dystocia camels. Copyright © 2016 Elsevier Inc. All rights reserved.

  2. Proteome Changes in biceps femoris Muscle of Iranian One-Humped Camel and Their Effect on Meat Quality Traits

    Directory of Open Access Journals (Sweden)

    Mohammad-Javad Varidi

    2016-01-01

    Full Text Available In this study physicochemical and quality traits of biceps femoris and longissimus thoracis muscles of male and female Iranian one-humped camel were determined during 14 days of refrigeration storage. Analysis of variance of the results showed that only shear force and temperature were affected by the gender (p<0.05. Anatomical location of the muscle influenced the meat properties except for drip loss (p<0.05. Also, except for cooking loss, ageing influenced the physicochemical and quality properties of meat; during 14 days of storage, proteolysis resulted in an increase of L* and b* values, drip loss and myofibrillar fragmentation index, and the decrease of a* value, expressed juice, shear force and sarcomere length. Proteome changes (myofi brillar proteins during storage were investigated. Gel analysis revealed that 19 protein spots were signifi cantly changed during 24, 72 and 168 h post-mortem. Fifteen spots were identified by MALDI-TOF/TOF mass spectrometer. Correlation analysis revealed significant correlations of actin, troponin T, capping protein, heat shock proteins (HSP and desmin with physicochemical and quality properties of meat (p<0.05. Actin might be a potential protein marker for colour, tenderness and water-holding capacity, and HSP27 and desmin are good candidate markers for colour and tenderness, respectively.

  3. 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.

  4. 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.

  5. 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.

  6. Molecular characterization of sympatrically distributed Neotricula aperta-like snails in the Mekong River, Kratie, Cambodia.

    Science.gov (United States)

    Wang, Chennan; Saijuntha, Weerachai; Kirinoki, Masashi; Hayashi, Naoko; Chigusa, Yuichi; Muth, Sinuon; Meng, Chuor Char; Ai, Yingchun; Agatsuma, Takeshi

    2016-01-01

    Fifty-six samples of Neotricula aperta-like snails were collected from six locations in Cambodia. Their mitochondrial cytochrome c oxidase subunit 1 (cox1) sequences were examined using haplotype network and neighbor-joining (NJ) tree analysis. Twenty-seven haplotypes (H1-H27) were observed and were divided into two different groups/lineages. Of 27, 17 haplotypes (H11-H27) were clustered with the reference samples of the γ-race N. aperta. The remaining 10 haplotypes (H1-H10) were clustered in a separate group/lineage, differing from the reference samples of the α-, β-, and γ-race N. aperta, suggesting a new lineage belonging the genus Neotricula. Our results show that both the γ-race and a new lineage were sympatrically present approximately 60 km upstream of the Mekong River near the Kratie port, Cambodia. Further morphological and molecular studies are required to confirm the taxonomic status of this new, unidentified lineage.

  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. Flowering Trees

    Indian Academy of Sciences (India)

    Srimath

    shaped corolla. Fruit is large, ellipsoidal, green with a hard and smooth shell containing numerous flattened seeds, which are embedded in fleshy pulp. Calabash tree is commonly grown in the tropical gardens of the world as a botanical oddity.

  9. 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.

  10. 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.

  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

  12. effect of different prevein level on the land snail (achatina chatina ...

    African Journals Online (AJOL)

    RAJAH

    The foot (edible portion), the shell and the visceral materials were weighed separately for each snail. .... Biometrics.11: 1-42. Ejidike, B. N., 2001. Comparative effect of supplemental and complete diets on the performance of. African giant land snail. Archachatina marginata). Proc. 26th Ann. Conf. Nig. Soc. for. Anim. Prod.

  13. 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.

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

    Science.gov (United States)

    Sidel'nikov, A P; Stepanov, I I

    2000-01-01

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

  15. 75 FR 35424 - Endangered and Threatened Wildlife and Plants; Proposed Reclassification of the Tulotoma Snail...

    Science.gov (United States)

    2010-06-22

    ... means that the snail has a rounded plate that seals the mouth of the shell while the snail is inside... Conservation measures provided to species listed as endangered or threatened under the Act include recognition.... Recognition through listing increases public awareness of threats to the tulotoma, and promotes conservation...

  16. Comparison of four species of snails as potential decoys to intercept schistosome miracidia.

    Science.gov (United States)

    Laracuente, A; Brown, R A; Jobin, W

    1979-01-01

    Preliminary studies have shown that various species of aquatic snails may be used as decoys or "sponges" to intercept schistosome miracidia, thereby preventing the miracidia from reaching the snails which normally serve as their intermediate host. In this study, four species of snails were evaluated as candidate decoys for field trials: Marisa cornuarietis, Pomacea australis, Helisoma caribaeum, and Tarebia granifera. In the laboratory all four species caused considerable reductions in the proportion of Biomphalaria glabrata infected by miracidia of Schistosoma mansoni. The most effective decoys were M. cornuarietis and H. caribaeum, both of which caused experimental infection levels of 90% to decrease to 25% when five decoy snails were present for each target snail. When ten decoy snails were present for each target snail, the proportion infected decreased to 1%. M. cornuarietis was chosen as the candidate for field trials because it was found more frequently in Puerto Rico than was H. caribaeum. Initial field trials in two ponds showed that M. cornuarietis blocked infections at a ratio of 6 decoys to 1 target snail, confirming the laboratory results. Further studies in flowing water are needed before the technique can be generally evaluated in an endemic area.

  17. The butterflies and land snails of Ndere Island National Park, Kenya ...

    African Journals Online (AJOL)

    After a survey of Ndere Island National Park between October and November 2004, we recorded 18 species of butterflies and 3 species of land snails. Eurema brigitta brigitta was the most abundant butterfly whereas Thapsia karamwegasensis was the most abundant land snail. Majority of the butterfly species are found in ...

  18. Removal of cadmium from aqueous solution using waste shells of golden apple snail

    Science.gov (United States)

    Benliang Zhao; Jia-en Zhang; Wenbin Yan; Xiaowu Kang; Chaogang Cheng; Ying Ouyang

    2016-01-01

    Golden apple snail (GAS) is one of the 100 worst invasive alien species. With the application of molluscicides to kill and control the spreading of these snails, a large amount of dead GAS shells are remained in many farms. This study ascertained the characteristics and removal of cadmium (Cd) by the GAS shell (GASS) powders and the associate mechanisms....

  19. 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

  20. To reduce the global burden of human schistosomiasis, use ‘old fashioned’ snail control

    Science.gov (United States)

    Sokolow, Susanne H.; Wood, Chelsea L.; Jones, Isabel J.; Lafferty, Kevin D.; Kuris, Armand; Hsieh, Michael H.; De Leo, Giulio A.

    2018-01-01

    Control strategies to reduce human schistosomiasis have evolved from ‘snail picking’ campaigns, a century ago, to modern wide-scale human treatment campaigns, or preventive chemotherapy. Unfortunately, despite the rise in preventive chemotherapy campaigns, just as many people suffer from schistosomiasis today as they did 50 years ago. Snail control can complement preventive chemotherapy by reducing the risk of transmission from snails to humans. Here, we present ideas for modernizing and scaling up snail control, including spatiotemporal targeting, environmental diagnostics, better molluscicides, new technologies (e.g., gene drive), and ‘outside the box’ strategies such as natural enemies, traps, and repellants. We conclude that, to achieve the World Health Assembly’s stated goal to eliminate schistosomiasis, it is time to give snail control another look.

  1. 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

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

    Science.gov (United States)

    Fruson, Lee; Dalesman, Sarah; Lukowiak, Ken

    2012-10-15

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

  3. 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.

  4. Effects of Deepwater Horizon Oil on the Movement and Survival of Marsh Periwinkle Snails (Littoraria irrorata).

    Science.gov (United States)

    Garner, T Ross; Hart, Michael A; Sweet, Lauren E; Bagheri, Hanna T J; Morris, Jeff; Stoeckel, James A; Roberts, Aaron P

    2017-08-01

    The Deepwater Horizon (DWH) oil spill resulted in the release of millions of barrels of oil into the Gulf of Mexico, and some marsh shorelines experienced heavy oiling including vegetation laid over under the weight of oil. Periwinkle snails (Littoraria irrorata) are a critical component of these impacted habitats, and population declines following oil spills, including DWH, have been documented. This study determined the effects of oil on marsh periwinkle movement and survivorship following exposure to oil. Snails were placed in chambers containing either unoiled or oiled laid over vegetation to represent a heavily impacted marsh habitat, with unoiled vertical structure at one end. In the first movement assay, snail movement to standing unoiled vegetation was significantly lower in oiled chambers (oil thickness ≈ 1 cm) compared to unoiled chambers, as the majority (∼75%) of snails in oiled habitats never reached standing unoiled vegetation after 72 h. In a second movement assay, there was no snail movement standing unoiled structure in chambers with oil thicknesses of 0.1 and 0.5 cm, while 73% of snails moved in unoiled chambers after 4h. A toxicity assay was then conducted by exposing snails to oil coated Spartina stems in chambers for periods up to 72 h, and mortality was monitored for 7 days post exposure. Snail survival decreased with increasing exposure time, and significant mortality (∼35%) was observed following an oil exposure of less than 24 h. Here, we have shown that oil impeded snail movement to clean habitat over a short distance and resulted in oil-exposure times that decreased survival. Taken together, along with declines documented by others in field surveys, these results suggest that marsh periwinkle snails may have been adversely affected following exposure to DWH oil.

  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. 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.

  7. 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

  8. 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

  9. An analysis of suppressing migratory effect on human urinary bladder cancer cell line by silencing of snail-1.

    Science.gov (United States)

    Salehi, Shima; Mansoori, Behzad; Mohammadi, Ali; Davoudian, Sadaf; Musavi Shenas, Seyed Mohammad Hossein; Shajari, Neda; Majidi, Jafar; Baradaran, Behzad

    2017-12-01

    Snail-1 actively participates in tumor progression, invasion, and migration. Targeting snail-1 expression can suppress the EMT process in cancer. The aim of this study was to investigate the effect of snail1 silencing on urinary bladder cancer. Quantitative RT-PCR was used to detect snail-1 and other related metastatic genes expression following siRNA knockdown in urinary bladder cancer EJ-138 cells. The protein level of snail1 was assessed by Western blot. MTT and TUNEL assays were assessed to understand if snail-1 had survival effects on EJ-138 cells. Scratch wound healing assay measured cell motility effects after snail1 suppression. The significant silencing of snail-1 reached 60pmol siRNA in a 48-h post-transfection. The result of scratch assay showed that snail-1 silencing significantly decreased Vimentin, MMPs, and CXCR4 expression; however, expression of E-cadherin was induced. The cell death assay indicated that snail-1 played the crucial role in bladder cancer survival rate. These results propose that snail-1 plays a major role in the progression and migration of urinary bladder cancer, and can be a potential therapeutic target for target therapy of invasive urinary bladder cancer. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  10. 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.

  11. Snail regulates p21WAF/CIP1 expression in cooperation with E2 A and Twist

    International Nuclear Information System (INIS)

    Takahashi, Eishi; Funato, Noriko; Higashihori, Norihisa; Hata, Yuiro; Gridley, Thomas; Nakamura, Masataka

    2004-01-01

    Snail, a zinc-finger transcriptional repressor, is essential for mesoderm and neural crest cell formation and epithelial-mesenchymal transition. The basic helix-loop-helix transcription factors E2A and Twist have been linked with Snail during embryonic development. In this study, we examined the role of Snail in cellular differentiation through regulation of p21 WAF/CIP1 expression. A reporter assay with the p21 promoter demonstrated that Snail inhibited expression of p21 induced by E2A. Co-expression of Snail with Twist showed additive inhibitory effects. Deletion mutants of the p21 promoter revealed that sequences between -270 and -264, which formed a complex with unidentified nuclear factor(s), were critical for E2A and Snail function. The E2A-dependent expression of the endogenous p21 gene was also inhibited by Snail

  12. 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.

  13. Chemosensitivity of the osphradium of the pond snail Lymnaea stagnalis

    Science.gov (United States)

    Wedemeyer; Schild

    1995-01-01

    The osphradium of the pond snail Lymnaea stagnalis was studied to determine the stimuli to which this organ responds. The following stimuli were tested: hypoxia, hypercapnia, a mixture of amino acids, a mixture of citralva and amyl acetate and a mixture of lyral, lilial and ethylvanillin. The mean nerve activity consistently increased with elevated PCO2, whereas hypoxia produced variable effects. The nerve activity became rhythmic upon application of citralva and amyl acetate, but it increased in a non-rhythmic way upon application of the other two odorant mixtures tested. Whole-cell patch-clamp recordings were made from a group of 15 neurones that lay next to the issuing osphradial nerve, to determine whether ganglion cells were involved in olfactory signal processing. All neurones tested responded to at least one of the three mixtures of odorants. Both excitatory and inhibitory responses occurred. Our results indicate that the osphradium of the pond snail Lymnaea stagnalis is sensitive to elevated PCO2 as well as to three different classes of odorants. In addition, at least some neurones within the osphradium are involved in the processing of olfactory information.

  14. 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

  15. Utilization Of Golden Snail As Alternative Liquid Organic Fertilizer LOF On Paddy Farmers In Dairi Indonesia

    Directory of Open Access Journals (Sweden)

    Ameilia Zuliyanti Siregar

    2017-11-01

    Full Text Available Golden snail Pomaceae canaliculata is a pest of rice plants and used as a food source to be processed into satay seasoning spices biscuits pastry candy crackers animal feed and fertilizer. In Lae Parira village the golden snail is very diverse. Because of this reason the preliminary study and utilization of golden snail used for of liquid organic fertilizer called LOF or and microorganisms local MOL. The golden snail is obtained from a livestock that is still alive and then washed boiled and removed from its shell. The golden snail meat is cut into small pieces separated from the intestine and other visceral organs. Flesh of golden snail give coconut water dilute brown sugar EM4 and fermentation until 10-14 days. The use of mashed LOF can be sprayed on the surface of the soil or all parts of the plant. For fertilization in rice plants the recommended dose of 250 ml15 liters of water is sprayed on the rice age 10 days after planting and repeated again at interval distance of 15 days. Fertilization on the plant recommended 200ml 15 liters of water sprayed on leaves and soil 7 days after planting and repeated every 7 days. The golden snail is potensial used for fertilizer in paddy plantation environmentally.

  16. Snail regulates cell survival and inhibits cellular senescence in human metastatic prostate cancer cell lines.

    Science.gov (United States)

    Emadi Baygi, Modjtaba; Soheili, Zahra Soheila; Schmitz, Ingo; Sameie, Shahram; Schulz, Wolfgang A

    2010-12-01

    The epithelial-mesenchymal transition (EMT) is regarded as an important step in cancer metastasis. Snail, a master regulator of EMT, has been recently proposed to act additionally as a cell survival factor and inducer of motility. We have investigated the function of Snail (SNAI1) in prostate cancer cells by downregulating its expression via short (21-mer) interfering RNA (siRNA) and measuring the consequences on EMT markers, cell viability, death, cell cycle, senescence, attachment, and invasivity. Of eight carcinoma cell lines, the prostate carcinoma cell lines LNCaP and PC-3 showed the highest and moderate expression of SNAI1 mRNA, respectively, as measured by quantitative RT-PCR. Long-term knockdown of Snail induced a severe decline in cell numbers in LNCaP and PC-3 and caspase activity was accordingly enhanced in both cell lines. In addition, suppression of Snail expression induced senescence in LNCaP cells. SNAI1-siRNA-treated cells did not tolerate detachment from the extracellular matrix, probably due to downregulation of integrin α6. Expression of E-cadherin, vimentin, and fibronectin was also affected. Invasiveness of PC-3 cells was not significantly diminished by Snail knockdown. Our data suggest that Snail acts primarily as a survival factor and inhibitor of cellular senescence in prostate cancer cell lines. We therefore propose that Snail can act as early driver of prostate cancer progression.

  17. 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.

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

    Science.gov (United States)

    Chontananarth, Thapana; Wongsawad, Chalobol

    2013-03-01

    To investigate the epidemiological situation of cercarial trematodes infection in freshwater snails from different water resources in Chiang Mai province, Thailand. 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. 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%). 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.

  19. Kinetic and dynamic aspects of soil-plant-snail transfer of cadmium in the field

    International Nuclear Information System (INIS)

    Gimbert, Frederic; Mench, Michel; Coeurdassier, Michael; Badot, Pierre-Marie; Vaufleury, Annette de

    2008-01-01

    The proper use of bioaccumulation in the assessment of environmental quality involves accounting for chemical fluxes in organisms. Cadmium (Cd) accumulation kinetics in a soil-plant-snail food chain were therefore investigated in the field under different soil contamination (from 0 to 40 mg kg -1 ), soil pH (6 and 7) and season. Allowing for an accurate and sensitive assessment of Cd transfer to snails, toxicokinetics appears an interesting tool in the improvement of risk assessment procedures and a way to quantify metal bioavailability for a defined target. On the basis of uptake fluxes, snails proved to be sensitive enough to distinguish moderate soil contaminations. The soil pH did not appear, in the range studied, as a modulating parameter of the Cd transfer from soil to snail whereas the season, by influencing the snail mass, may modify the internal concentrations. The present data specifying a time integrated assessment of environmental factors on metal bioavailability and transfer to terrestrial snails should ensure their rational use in environmental biomonitoring. - Toxicokinetics and uptake fluxes can be used to describe the environment contamination by Cd, its bioavailability and transfer to Helix aspersa snails in the field

  20. Arsenic transfer and impacts on snails exposed to stabilized and untreated As-contaminated soils

    International Nuclear Information System (INIS)

    Coeurdassier, M.; Scheifler, R.; Mench, M.; Crini, N.; Vangronsveld, J.; Vaufleury, A. de

    2010-01-01

    An As-contaminated soil (Unt) was amended with either iron grit (Z), a coal fly ash (beringite, B) or B + Z (BZ) and placed in lysimeters in 1997. An uncontaminated soil (R) was also studied. In summer and autumn 2003, lettuces were cultivated in the lysimeters and snails were caged for one month. Lettuce As concentrations were higher during the summer, while no differences occurred in snails between seasons. Snail As concentrations (μg g -1 DW) ranged from 2.5 to 7.0 in B, Z and BZ, and peaked at 17.5 in Unt. In summer, snail survival was affected in Unt and Z compared to R and B while no mortality was noticed in autumn. Snail growth decreased only in B, BZ and Unt in autumn. Snail As concentrations suggest a risk for their predators even on the remediated soils. - The addition of beringite along with iron grit into an As-contaminated soil decreases As transfer to and impacts on snails.

  1. Flowering Trees

    Indian Academy of Sciences (India)

    deciduous tree with irregularly-shaped trunk, greyish-white scaly bark and milky latex. Leaves in opposite pairs are simple, oblong and whitish beneath. Flowers that occur in branched inflorescence are white, 2–. 3cm across and fragrant. Calyx is glandular inside. Petals bear numerous linear white scales, the corollary.

  2. Flowering Trees

    Indian Academy of Sciences (India)

    Berrya cordifolia (Willd.) Burret (Syn. B. ammonilla Roxb.) – Trincomali Wood of Tiliaceae is a tall evergreen tree with straight trunk, smooth brownish-grey bark and simple broad leaves. Inflorescence is much branched with white flowers. Stamens are many with golden yellow anthers. Fruit is a capsule with six spreading ...

  3. Flowering Trees

    Indian Academy of Sciences (India)

    Canthium parviflorum Lam. of Rubiaceae is a large shrub that often grows into a small tree with conspicuous spines. Leaves are simple, in pairs at each node and are shiny. Inflorescence is an axillary few-flowered cymose fascicle. Flowers are small (less than 1 cm across), 4-merous and greenish-white. Fruit is ellipsoid ...

  4. Flowering Trees

    Indian Academy of Sciences (India)

    sriranga

    Hook.f. ex Brandis (Yellow. Cadamba) of Rubiaceae is a large and handsome deciduous tree. Leaves are simple, large, orbicular, and drawn abruptly at the apex. Flowers are small, yellowish and aggregate into small spherical heads. The corolla is funnel-shaped with five stamens inserted at its mouth. Fruit is a capsule.

  5. Flowering Trees

    Indian Academy of Sciences (India)

    Celtis tetrandra Roxb. of Ulmaceae is a moderately large handsome deciduous tree with green branchlets and grayish-brown bark. Leaves are simple with three to four secondary veins running parallel to the mid vein. Flowers are solitary, male, female and bisexual and inconspicuous. Fruit is berry-like, small and globose ...

  6. Flowering Trees

    Indian Academy of Sciences (India)

    IAS Admin

    Aglaia elaeagnoidea (A.Juss.) Benth. of Meliaceae is a small-sized evergreen tree of both moist and dry deciduous forests. The leaves are alternate and pinnately compound, terminating in a single leaflet. Leaflets are more or less elliptic with entire margin. Flowers are small on branched inflorescence. Fruit is a globose ...

  7. Flowering Trees

    Indian Academy of Sciences (India)

    user

    Flowers are borne on stiff bunches terminally on short shoots. They are 2-3 cm across, white, sweet-scented with light-brown hairy sepals and many stamens. Loquat fruits are round or pear-shaped, 3-5 cm long and are edible. A native of China, Loquat tree is grown in parks as an ornamental and also for its fruits.

  8. Flowering Trees

    Indian Academy of Sciences (India)

    mid-sized slow-growing evergreen tree with spreading branches that form a dense crown. The bark is smooth, thick, dark and flakes off in large shreds. Leaves are thick, oblong, leathery and bright red when young. The female flowers are drooping and are larger than male flowers. Fruit is large, red in color and velvety.

  9. Flowering Trees

    Indian Academy of Sciences (India)

    Andira inermis (wright) DC. , Dog Almond of Fabaceae is a handsome lofty evergreen tree. Leaves are alternate and pinnately compound with 4–7 pairs of leaflets. Flowers are fragrant and are borne on compact branched inflorescences. Fruit is ellipsoidal one-seeded drupe that is peculiar to members of this family.

  10. Flowering Trees

    Indian Academy of Sciences (India)

    narrow towards base. Flowers are large and attrac- tive, but emit unpleasant foetid smell. They appear in small numbers on erect terminal clusters and open at night. Stamens are numerous, pink or white. Style is slender and long, terminating in a small stigma. Fruit is green, ovoid and indistinctly lobed. Flowering Trees.

  11. Flowering Trees

    Indian Academy of Sciences (India)

    Muntingia calabura L. (Singapore cherry) of. Elaeocarpaceae is a medium size handsome ever- green tree. Leaves are simple and alternate with sticky hairs. Flowers are bisexual, bear numerous stamens, white in colour and arise in the leaf axils. Fruit is a berry, edible with several small seeds embedded in a fleshy pulp ...

  12. ~{owering 'Trees

    Indian Academy of Sciences (India)

    . Stamens are fused into a purple staminal tube that is toothed. Fruit is about 0.5 in. across, nearly globose, generally 5-seeded, green but yellow when ripe, quite smooth at first but wrinkled in drying, remaining long on the tree ajier ripening.

  13. Tree Mortality

    Science.gov (United States)

    Mark J. Ambrose

    2012-01-01

    Tree mortality is a natural process in all forest ecosystems. However, extremely high mortality also can be an indicator of forest health issues. On a regional scale, high mortality levels may indicate widespread insect or disease problems. High mortality may also occur if a large proportion of the forest in a particular region is made up of older, senescent stands....

  14. Flowering Trees

    Indian Academy of Sciences (India)

    Guaiacum officinale L. (LIGNUM-VITAE) of Zygophyllaceae is a dense-crowned, squat, knobbly, rough and twisted medium-sized ev- ergreen tree with mottled bark. The wood is very hard and resinous. Leaves are compound. The leaflets are smooth, leathery, ovate-ellipti- cal and appear in two pairs. Flowers (about 1.5.

  15. Herbivorous snails can increase water clarity by stimulating growth of benthic algae.

    Science.gov (United States)

    Zhang, Xiufeng; Taylor, William D; Rudstam, Lars G

    2017-11-01

    Eutrophication in shallow lakes is characterized by a switch from benthic to pelagic dominance of primary productivity that leads to turbid water, while benthification is characterized by a shift in primary production from the pelagic zone to the benthos associated with clear water. A 12-week mesocosm experiment tested the hypothesis that the herbivorous snail Bellamya aeruginosa stimulates the growth of pelagic algae through grazing on benthic algae and through accelerating nutrient release from sediment. A tube-microcosm experiment using 32 P-PO 4 as a tracer tested the effects of the snails on the release of sediment phosphorus (P). The mesocosm experiment recorded greater total nitrogen (TN) concentrations and a higher ratio of TN:TP in the overlying water, and a higher light intensity and biomass of benthic algae as measured by chlorophyll a (Chl a) in the snail treatment than in the control. Concentrations of total phosphorus (TP), total suspended solids (TSSs), and inorganic suspended solids (ISSs) in the overlying water were lower in the snail treatment than in the control, though no significant difference in Chl a of pelagic algae between the snail treatment and control was observed. In the microcosm experiment, 32 P activity in the overlying water was higher in the snail treatment than in the control, indicating that snails accelerated P release from the sediment. Our interpretation of these results is that snails enhanced growth of benthic algae and thereby improved water clarity despite grazing on the benthic algae and enhancing P release from the sediment. The rehabilitation of native snail populations may therefore enhance the recovery of eutrophic shallow lakes to a clear water state by stimulating growth of benthic algae.

  16. Impact and cost-effectiveness of snail control to achieve disease control targets for schistosomiasis.

    Science.gov (United States)

    Lo, Nathan C; Gurarie, David; Yoon, Nara; Coulibaly, Jean T; Bendavid, Eran; Andrews, Jason R; King, Charles H

    2018-01-23

    Schistosomiasis is a parasitic disease that affects over 240 million people globally. To improve population-level disease control, there is growing interest in adding chemical-based snail control interventions to interrupt the lifecycle of Schistosoma in its snail host to reduce parasite transmission. However, this approach is not widely implemented, and given environmental concerns, the optimal conditions for when snail control is appropriate are unclear. We assessed the potential impact and cost-effectiveness of various snail control strategies. We extended previously published dynamic, age-structured transmission and cost-effectiveness models to simulate mass drug administration (MDA) and focal snail control interventions against Schistosoma haematobium across a range of low-prevalence (5-20%) and high-prevalence (25-50%) rural Kenyan communities. We simulated strategies over a 10-year period of MDA targeting school children or entire communities, snail control, and combined strategies. We measured incremental cost-effectiveness in 2016 US dollars per disability-adjusted life year and defined a strategy as optimally cost-effective when maximizing health gains (averted disability-adjusted life years) with an incremental cost-effectiveness below a Kenya-specific economic threshold. In both low- and high-prevalence settings, community-wide MDA with additional snail control reduced total disability by an additional 40% compared with school-based MDA alone. The optimally cost-effective scenario included the addition of snail control to MDA in over 95% of simulations. These results support inclusion of snail control in global guidelines and national schistosomiasis control strategies for optimal disease control, especially in settings with high prevalence, "hot spots" of transmission, and noncompliance to MDA. Copyright © 2018 the Author(s). Published by PNAS.

  17. Effect of defect creation and migration on hump characteristics of a-InGaZnO thin film transistors under long-term drain bias stress with light illumination

    Science.gov (United States)

    Cho, Yong-Jung; Kim, Woo-Sic; Lee, Yeol-Hyeong; Park, Jeong Ki; Kim, Geon Tae; Kim, Ohyun

    2018-06-01

    We investigated the mechanism of formation of the hump that occurs in the current-voltage I-V characteristics of amorphous InGaZnO (a-IGZO) thin film transistors (TFTs) that are exposed to long-term drain bias stress under illumination. Transfer characteristics showed two-stage degradation under the stress. At the beginning of the stress, the I-V characteristics shifted in the negative direction with a degradation of subthreshold slope, but the hump phenomenon developed over time in the I-V characteristics. The development of the hump was related to creation of defects, especially ionized oxygen vacancies which act as shallow donor-like states near the conduction-band minimum in a-IGZO. To further investigate the hump phenomenon we measured a capacitance-voltage C-V curve and performed two-dimensional device simulation. Stretched-out C-V for the gate-to-drain capacitance and simulated electric field distribution which exhibited large electric field near the drain side of TFT indicated that VO2+ were generated near the drain side of TFT, but the hump was not induced when VO2+ only existed near the drain side. Therefore, the degradation behavior under DBITS occurred because VO2+ were created near the drain side, then were migrated to the source side of the TFT.

  18. Scientific Opinion on the assessment of the potential establishment of the apple snail in the EU

    OpenAIRE

    EFSA Panel on Plant Health (PLH)

    2013-01-01

    EFSA requested the PLH Panel to review the current state of the art of the biology and ecology of apple snails, reported in this opinion, and to perform an environmental risk assessment for validation of the Plant Health environment guidance document, which will be provided in a second opinion. The Panel presents in this opinion the current state of the art of the biology of apple snails, and develops and uses a population dynamics model to assess the potential establishment of apple snails i...

  19. 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

  20. Hump behind the shoulders

    Science.gov (United States)

    ... High level of the hormone cortisol (caused by Cushing syndrome ) Certain genetic disorders that cause unusual fat accumulation ... and the A.D.A.M. Editorial team. Cushing's Syndrome Read more Neck Injuries and Disorders Read more ...

  1. Over the Hump

    National Research Council Canada - National Science Library

    Tunner, William H

    1998-01-01

    This book is a classic in the annals of air power history. William Tunner was a master of airlift operations at a time when the airplane itself was transitioning from the pre-modern into the modern era...

  2. Nuclear expression of Snail1 in borderline and malignant epithelial ovarian tumours is associated with tumour progression

    International Nuclear Information System (INIS)

    Tuhkanen, Hanna; Soini, Ylermi; Kosma, Veli-Matti; Anttila, Maarit; Sironen, Reijo; Hämäläinen, Kirsi; Kukkonen, Laura; Virtanen, Ismo; Mannermaa, Arto

    2009-01-01

    Transcription factor Snail1 has a central role in induction of epithelial-mesenchymal transition (EMT). The aim of the present study was to elucidate the expression of Snail1 protein during epithelial ovarian tumourigenesis and to study the association of Snail1 expression with clinicopathological factors and prognosis. Epithelial and stromal fibroblast-like fusiform cells of 14 normal ovarian samples, 21 benign, 24 borderline and 74 malignant epithelial ovarian tumours were studied for Snail1 protein using immunohistochemistry. Nuclei of surface peritoneal cells of normal ovaries (n = 14) were regarded as negative for Snail1. Nuclear expression of Snail1 protein in epithelial ovarian tumours was increased during tumour progression from precursor lesions into carcinomas both in epithelial (p = 0.006) and stromal cells (p = 0.007). Nuclei of benign tumours (n = 21) were negative for Snail1. In borderline tumours (n = 24) occasional positive epithelial cells were found in 2 (8%) samples and in 3 (13%) samples stromal cells were focally positive for Snail1. In carcinomas (n = 74) focal Snail1 staining in epithelial cells was present in 17 (23%) tumours, and in stromal cells in 18 (24%) tumours. Nuclear expression of Snail1 in epithelial or stromal cells was not associated with clinicopathological factors or prognosis. Nuclear Snail1 expression seems to be related to tumour progression, and expression in borderline tumours indicates a role for Snail1 in early epithelial ovarian tumour development. Snail1 also appears to function more generally in tissue remodelling as positive staining was demonstrated in stromal cells

  3. 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.

  4. Optimal designs of mollusk shells from bivalves to snails.

    Science.gov (United States)

    Okabe, Takuya; Yoshimura, Jin

    2017-02-10

    Bivalve, ammonite and snail shells are described by a small number of geometrical parameters. Raup noted that the vast majority of theoretically possible shell forms do not occur in nature. The constraint factors that regulate the biased distribution of natural form have long since been an open problem in evolution. The problem of whether natural shell form is a result of optimization remains unsolved despite previous attempts. Here we solve this problem by considering the scaling exponent of shell thickness as a morphological parameter. The scaling exponent has a drastic effect on the optimal design of shell shapes. The observed characteristic shapes of natural shells are explained in a unified manner as a result of optimal utilization of shell material resources, while isometric growth in thickness leads to impossibly tight coiling.

  5. 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.

  6. 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...

  7. 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.

  8. High molecular weight lectin isolated from the mucus of the giant African snail Achatina fulica.

    Science.gov (United States)

    Ito, Shigeru; Shimizu, Masahiro; Nagatsuka, Maki; Kitajima, Seiji; Honda, Michiyo; Tsuchiya, Takahide; Kanzawa, Nobuyuki

    2011-01-01

    To understand better the host defense mechanisms of mollusks against pathogens, we examined the anti-microbial activity of mucus from the giant African snail Achatina fulica. Hemagglutination activity of the mucus secreted by the integument of snails inoculated with Escherichia coli was observed to increase and to cause hemagglutination of rabbit red blood cells. Purification of the snail mucus lectin by sequential column chromatography revealed that the relative molecular mass of the lectin was 350 kDa. The hemagglutination activity of the lectin was Ca(2+)-dependent and was inhibited by galactose. Growth arrest tests showed that the lectin did not inhibit bacterial growth, but did induce agglutination of gram-positive and gram-negative bacteria. Tissue distribution analyses using a polyclonal antibody revealed that the lectin was expressed in the tissues of the mantle collar. The lectin isolated from the mucus of the snail appeared to contribute to its innate immunity.

  9. 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. Whet...

  10. 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.

  11. Multi-hump potentials for efficient wave absorption in the numerical solution of the time-dependent Schrödinger equation

    Science.gov (United States)

    Silaev, A. A.; Romanov, A. A.; Vvedenskii, N. V.

    2018-03-01

    In the numerical solution of the time-dependent Schrödinger equation by grid methods, an important problem is the reflection and wrap-around of the wave packets at the grid boundaries. Non-optimal absorption of the wave function leads to possible large artifacts in the results of numerical simulations. We propose a new method for the construction of the complex absorbing potentials for wave suppression at the grid boundaries. The method is based on the use of the multi-hump imaginary potential which contains a sequence of smooth and symmetric humps whose widths and amplitudes are optimized for wave absorption in different spectral intervals. We show that this can ensure a high efficiency of absorption in a wide range of de Broglie wavelengths, which includes wavelengths comparable to the width of the absorbing layer. Therefore, this method can be used for high-precision simulations of various phenomena where strong spreading of the wave function takes place, including the phenomena accompanying the interaction of strong fields with atoms and molecules. The efficiency of the proposed method is demonstrated in the calculation of the spectrum of high-order harmonics generated during the interaction of hydrogen atoms with an intense infrared laser pulse.

  12. Interplay of superconductivity and bosonic coupling in the peak-dip-hump structure of Bi2Sr2CaCu2O8 +δ

    Science.gov (United States)

    Miller, Tristan L.; Zhang, Wentao; Ma, Jonathan; Eisaki, Hiroshi; Moore, Joel E.; Lanzara, Alessandra

    2018-04-01

    Because of the important role of electron-boson interactions in conventional superconductivity, it has long been asked whether any similar mechanism is at play in high-temperature cuprate superconductors. Evidence for strong electron-boson coupling is observed in cuprates with angle-resolved photoemission spectroscopy (ARPES), in the form of a dispersion kink and peak-dip-hump structure. What is missing is evidence of a causal relation to superconductivity. Here we revisit the problem using the technique of time-resolved ARPES on Bi2Sr2CaCu2O8 +δ . We focus on the peak-dip-hump structure, and show that laser pulses shift spectral weight into the dip as superconductivity is destroyed on picosecond time scales. We compare our results to simulations of Eliashberg theory in a superconductor with an Einstein boson, and find that the magnitude of the shift in spectral weight depends on the degree to which the bosonic mode contributes to superconductivity. Further study could address one of the longstanding mysteries of high-temperature superconductivity.

  13. 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

  14. 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.

  15. [Occurrence of Achatina fulica Bowdich, 1822 (Mollusca, Gastropoda) in Brazil: intermediate snail host of angiostrongyliasis].

    Science.gov (United States)

    Teles, H M; Vaz, J F; Fontes, L R; Domingos, M de F

    1997-06-01

    Achatina fulica, the intermediate snail host of angiostrongyliasis and also an agricultural pest, is being bred in Brazil for human consumption as "escargot". The snail has escaped from its artificial breeding sites and its dispersal in Itariri country, State of S. Paulo, is reported here for the first time. A. fulica is a transmitter of the rat lungworm Angiostrongylus cantonensis, nematode which causes meningoencephalic angiostrongyliasis; the risks of human contamination are commented on.

  16. 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.

  17. 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.

  18. Snail1 induces epithelial-to-mesenchymal transition and tumor initiating stem cell characteristics

    International Nuclear Information System (INIS)

    Dang, Hien; Ding, Wei; Emerson, Dow; Rountree, C Bart

    2011-01-01

    Tumor initiating stem-like cells (TISCs) are a subset of neoplastic cells that possess distinct survival mechanisms and self-renewal characteristics crucial for tumor maintenance and propagation. The induction of epithelial-mesenchymal-transition (EMT) by TGFβ has been recently linked to the acquisition of TISC characteristics in breast cancer. In HCC, a TISC and EMT phenotype correlates with a worse prognosis. In this work, our aim is to elucidate the underlying mechanism by which cells acquire tumor initiating characteristics after EMT. Gene and protein expression assays and Nanog-promoter luciferase reporter were utilized in epithelial and mesenchymal phenotype liver cancer cell lines. EMT was analyzed with migration/invasion assays. TISC characteristics were analyzed with tumor-sphere self-renewal and chemotherapy resistance assays. In vivo tumor assay was performed to investigate the role of Snail1 in tumor initiation. TGFβ induced EMT in epithelial cells through the up-regulation of Snail1 in Smad-dependent signaling. Mesenchymal liver cancer post-EMT demonstrates TISC characteristics such as tumor-sphere formation but are not resistant to cytotoxic therapy. The inhibition of Snail1 in mesenchymal cells results in decreased Nanog promoter luciferase activity and loss of self-renewal characteristics in vitro. These changes confirm the direct role of Snail1 in some TISC traits. In vivo, the down-regulation of Snail1 reduced tumor growth but was not sufficient to eliminate tumor initiation. In summary, TGFβ induces EMT and TISC characteristics through Snail1 and Nanog up-regulation. In mesenchymal cells post-EMT, Snail1 directly regulates Nanog expression, and loss of Snail1 regulates tumor growth without affecting tumor initiation

  19. Surface tree languages and parallel derivation trees

    NARCIS (Netherlands)

    Engelfriet, Joost

    1976-01-01

    The surface tree languages obtained by top-down finite state transformation of monadic trees are exactly the frontier-preserving homomorphic images of sets of derivation trees of ETOL systems. The corresponding class of tree transformation languages is therefore equal to the class of ETOL languages.

  20. Weak involvement of octopamine in aversive taste learning in a snail.

    Science.gov (United States)

    Aonuma, Hitoshi; Kaneda, Mugiho; Hatakeyama, Dai; Watanabe, Takayuki; Lukowiak, Ken; Ito, Etsuro

    2017-05-01

    The pond snail Lymnaea stagnalis is capable of learning taste aversion by pairing presentations of a sucrose solution and an electric shock and consolidating it into long-term memory (LTM), which is referred to as conditioned taste aversion (CTA). We asked here if the neurotransmitter octopamine is involved in CTA. We first determined the levels of octopamine and its catabolites in the central nervous system (CNS) of snails with varying degrees of food deprivation, because CTA grades are correlated with degrees of food deprivation. We next manipulated the octopamine signaling using both an agonist and an antagonist of octopamine receptors and correlated their respective effects with CTA grades. We found that snails with the least amount of food-deprivation obtained the best CTA grade and had low levels of octopamine; whereas the most severely food-deprived snails did not form CTA and had the highest CNS octopamine levels. In modestly food-deprived snails, octopamine application increased the basal level of feeding response to a sucrose solution, and it did not obstruct CTA formation. Application of phentolamine, an octopamine receptor antagonist, to the most severely food-deprived snails decreased the basal level of feeding elicited by sucrose, but it did not enhance CTA formation. We conclude that octopamine involvement in CTA formation in Lymnaea is at best weak, and that the changes in CNS octopamine content are an epiphenomenon. Copyright © 2017 Elsevier Inc. All rights reserved.

  1. Assessment the Molluscicidal Properties of Azadirachtin Against Golden Apple Snail, Pomacea Canaliculata

    International Nuclear Information System (INIS)

    Rosdiyani Massaguni; Siti Noor Hajjar Mohd Latip

    2015-01-01

    Concern with the negative impact of synthetic pesticide on environment and human health have led this study in order to evaluate the molluscicidal efficacies of azadirachtin in neem seed crude extract on golden apple snail. Azadirachtin was extracted by maceration technique using four different solvents and the quantity of azadirachtin in extracts was compared to select the best solvent. Then, bioassays were performed on adult of golden apple snail to compare the molluscicidal activity of azadirachtin. A comparison of the extractive yields of different solvents indicated that the polarity of the solvents tested not significantly influence in enhanced the azadirachtin yields. The result on mortality rate of golden apple snail subjected to various concentration and solvent extracts indicated that neem seed crude extracts significantly killed the golden apple snail. The LC 50 values of the methanol extract (21.008 mg/ ml) were the lowest, indicating the highest potency, followed in order by ethanol extract (43.726 mg/ ml), acetone extract (48.110 mg/ ml) and water extract (53.654 mg/ ml). The mortality rate was correlated positively with the extract concentrations as the mortality of snail increased with the increase of extract concentration. Therefore, this study indicated that neem seed crude extracts possessed molluscicidal effect for controlling the golden apple snail. (author)

  2. Bacterial diversity in different regions of gastrointestinal tract of Giant African snail (Achatina fulica).

    Science.gov (United States)

    Pawar, Kiran D; Banskar, Sunil; Rane, Shailendra D; Charan, Shakti S; Kulkarni, Girish J; Sawant, Shailesh S; Ghate, Hemant V; Patole, Milind S; Shouche, Yogesh S

    2012-12-01

    The gastrointestinal (GI) tract of invasive land snail Achatina fulica is known to harbor metabolically active bacterial communities. In this study, we assessed the bacterial diversity in the different regions of GI tract of Giant African snail, A. fulica by culture-independent and culture-dependent methods. Five 16S rRNA gene libraries from different regions of GI tract of active snails indicated that sequences affiliated to phylum γ-Proteobacteria dominated the esophagus, crop, intestine, and rectum libraries, whereas sequences affiliated to Tenericutes dominated the stomach library. On phylogenetic analysis, 30, 27, 9, 27, and 25 operational taxonomic units (OTUs) from esophagus, crop, stomach, intestine, and rectum libraries were identified, respectively. Estimations of the total bacterial diversity covered along with environmental cluster analysis showed highest bacterial diversity in the esophagus and lowest in the stomach. Thirty-three distinct bacterial isolates were obtained, which belonged to 12 genera of two major bacterial phyla namely γ-Proteobacteria and Firmicutes. Among these, Lactococcus lactis and Kurthia gibsonii were the dominant bacteria present in all GI tract regions. Quantitative real-time polymerase chain reaction (qPCR) analysis indicated significant differences in bacterial load in different GI tract regions of active and estivating snails. The difference in the bacterial load between the intestines of active and estivating snail was maximum. Principal component analysis (PCA) of terminal restriction fragment length polymorphism suggested that bacterial community structure changes only in intestine when snail enters estivation state. © 2012 The Authors. Published by Blackwell Publishing Ltd.

  3. Identification of characteristic aroma compounds in raw and thermally processed African giant snail (Achatina fulica).

    Science.gov (United States)

    Lasekan, Ola; Muniady, Megala; Lin, Mee; Dabaj, Fatma

    2018-04-24

    Food flavor appreciation is one of the first signals along with food appearance and texture encountered by consumers during eating of food. Also, it is well known that flavor can strongly influence consumer's acceptability judgment. The increase in the consumption of snail meat across the world calls for the need to research into the aroma compounds responsible for the distinctive aroma notes of processed snail meat. The odorants responsible for the unique aroma notes in thermally processed giant African snail meats were evaluated by means of aroma extract dilution analysis (AEDA), gas chromatography-olfactometry (GC-O) and odor activity values (OAVs) respectively. Results revealed significant differences in the aroma profiles of the raw and thermally processed snail meats. Whilst the aroma profile of the raw snail meat was dominated with the floral-like β-ionone and β-iso-methyl ionone, sweaty/cheesy-like butanoic acid, and the mushroom-like 1-octen-3-one, the boiled and fried samples were dominated with the thermally generated odorants like 2-methylpyrazine, 2,5-dimethylpyrazine, 2-acetylthiazole and 2-acetylpyridine. Finally, results have shown that sotolon, 2-acetyl-1-pyrroline, 2-furanmethanethiol, 2-methylbutanal, 1-octen-3-one, octanal, furanone, 2-methoxyphenol, 2-acetylpyridine, 2-acetylthiazole, and 2-methylpyrazine contributed to the overall aroma of the thermally processed snail meat.

  4. Sensory mediation of memory blocking stressors in the pond snail Lymnaea stagnalis.

    Science.gov (United States)

    Dalesman, Sarah; Karnik, Vikram; Lukowiak, Ken

    2011-08-01

    The great pond snail, Lymnaea stagnalis, is commonly used as a model species to study how stress affects the ability to form long-term memory (LTM); however, we still have little information about how the snail senses stressful stimuli. The osphradium is an external sensory organ that demonstrates electrophysiological responses to a variety of external chemical stimuli. We examined the role, if any, played by the osphradium in sensing two environmental stressors, crowding and low environmental calcium, both known to block LTM in intact animals. We severed the osphradial nerve, blocking external sensory input from this organ to the central nervous system, and then exposed the snails to low environmental calcium or crowding stress to assess whether these stressors continued to block LTM formation. When exposed to low environmental calcium, snails with their osphradial nerve severed responded as if they were maintained in our standard calcium environment. That is, they did not respond to low calcium as a stressor blocking LTM; therefore, the osphradium plays a crucial role in mediating how snails respond to this stressor. However, following crowding, LTM formation was blocked in both control groups and snails that had the osphradial nerve severed, indicating that sensory information from the osphradium is not required to sense crowded conditions. Together these data show that two stressors that result in the same behavioural phenotype, blocking LTM formation, do so via two distinct sensory pathways.

  5. Effects of 5-HT and insulin on learning and memory formation in food-deprived snails.

    Science.gov (United States)

    Aonuma, Hitoshi; Totani, Yuki; Kaneda, Mugiho; Nakamura, Ryota; Watanabe, Takayuki; Hatakeyama, Dai; Dyakonova, Varvara E; Lukowiak, Ken; Ito, Etsuro

    2018-02-01

    The pond snail Lymnaea stagnalis learns conditioned taste aversion (CTA) and consolidates it into long-term memory (LTM). How well they learn and form memory depends on the degree of food deprivation. Serotonin (5-HT) plays an important role in mediating feeding, and insulin enhances the memory consolidation process following CTA training. However, the relationship between these two signaling pathways has not been addressed. We measured the 5-HT content in the central nervous system (CNS) of snails subjected to different durations of food deprivation. One-day food-deprived snails, which exhibit the best learning and memory, had the lowest 5-HT content in the CNS, whereas 5-day food-deprived snails, which do not learn, had a high 5-HT content. Immersing 1-day food-deprived snails in 5-HT impaired learning and memory by causing an increase in 5-HT content, and that the injection of insulin into these snails reversed this impairment. We conclude that insulin rescues the CTA deficit and this may be due to a decrease in the 5-HT content in the CNS of Lymnaea. Copyright © 2018 Elsevier Inc. All rights reserved.

  6. 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.

  7. Trees are good, but…

    Science.gov (United States)

    E.G. McPherson; F. Ferrini

    2010-01-01

    We know that “trees are good,” and most people believe this to be true. But if this is so, why are so many trees neglected, and so many tree wells empty? An individual’s attitude toward trees may result from their firsthand encounters with specific trees. Understanding how attitudes about trees are shaped, particularly aversion to trees, is critical to the business of...

  8. Overexpression of Snail is associated with lymph node metastasis and poor prognosis in patients with gastric cancer

    International Nuclear Information System (INIS)

    Shin, Na Ri; Lee, Jae Hyuk; Park, Do Youn; Jeong, Eun Hui; Choi, Chang In; Moon, Hyun Jung; Kwon, Chae Hwa; Chu, In Sun; Kim, Gwang Ha; Jeon, Tae Yong; Kim, Dae Hwan

    2012-01-01

    Epithelial–mesenchymal transition (EMT) plays a significant role in tumor progression and invasion. Snail is a known regulator of EMT in various malignant tumors. This study investigated the role of Snail in gastric cancer. We examined the effects of silenced or overexpressed Snail using lenti-viral constructs in gastric cancer cells. Immunohistochemical analysis of tissue microarrays from 314 patients with gastric adenocarcinoma (GC) was used to determine Snail’s clinicopathological and prognostic significance. Differential gene expression in 45 GC specimens with Snail overexpression was investigated using cDNA microarray analysis. Silencing of Snail by shRNA decreased invasion and migration in GC cell lines. Conversely, Snail overexpression increased invasion and migration of gastric cancer cells, in line with increased VEGF and MMP11. Snail overexpression (≥75% positive nuclear staining) was also significantly associated with tumor progression (P < 0.001), lymph node metastases (P = 0.002), lymphovascular invasion (P = 0.002), and perineural invasion (P = 0.002) in the 314 GC patients, and with shorter survival (P = 0.023). cDNA microarray analysis revealed 213 differentially expressed genes in GC tissues with Snail overexpression, including genes related to metastasis and invasion. Snail significantly affects invasiveness/migratory ability of GCs, and may also be used as a predictive biomarker for prognosis or aggressiveness of GCs

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

    OpenAIRE

    Rosmilah Misnan; Norazlin Salahudin Abd Aziz; Zailatul Hani Mohamad Yadzir; Faizal Bakhtiar; Noormalin Abdullah; Shahnaz Murad

    2016-01-01

    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...

  10. 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

  11. Soil parameters are key factors to predict metal bioavailability to snails based on chemical extractant data

    International Nuclear Information System (INIS)

    Pauget, B.; Gimbert, F.; Scheifler, R.; Coeurdassier, M.; Vaufleury, A. de

    2012-01-01

    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 4 , EDTA, CaCl 2 , NH 4 NO 3 , NaNO 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 (r² 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 (r² 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: ► New approach to identify chemical methods able to predict metal bioavailability to snails. ► Bioavailability of cadmium, lead and zinc to snails was determined by

  12. 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

  13. 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.

  14. 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...

  15. 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...

  16. Lead reduces shell mass in juvenile garden snails (Helix aspersa)

    International Nuclear Information System (INIS)

    Beeby, Alan; Richmond, Larry; Herpe, Florian

    2002-01-01

    A high Pb diet causes differential depression of juvenile shell mass in populations of Helix. - In an earlier paper examining inherited tolerance to Pb, the shell growth of laboratory-bred offspring of Helix aspersa from contaminated sites was compared with that of juveniles from naieve populations on dosed and undosed diets. Eight-week-old snails were fed either 500 μg g -1 Pb or a control food in competitive trials between two populations. In the first series of trials, a parental history of exposure to Pb did not confer any advantage to either of two populations (BI and MI) competing with a naieve population (LE), whether Pb was present in the diet or not. However, in the analysis of their metal concentrations reported here, LE are found to retain higher levels of Pb in the soft tissues than either BI or MI. Compared to their siblings on the unleaded diet, dosed LE and BI juveniles had lower soft tissue concentrations of Ca and Mg. Although the growth in shell height is unaffected by diet, LE and BI juveniles build lighter shells on the Pb-dosed diet, achieving around 75% of the shell mass of their controls. In contrast, the shell weights of dosed MI juveniles are depressed by only 15% and show no change in the essential metal concentrations of their soft tissues. A second experiment using five populations fed only the dosed food show that the shell weight/soft tissue weight ratios are comparable to the dosed snails of the previous experiment. Building a lighter shell thus appears to be the common response of all Helix populations to a high Pb diet, at least amongst juveniles. The reduction in its mass means that less Ca and Mg is added to the shell and, along with the lowered soft tissue concentrations observed in some populations, may be a consequence of an increased effort to excrete Pb. The possibility that the MI population shows a genotypic adaptation, perhaps as some form of modification of its Ca metabolism, is briefly discussed

  17. City of Pittsburgh Trees

    Data.gov (United States)

    Allegheny County / City of Pittsburgh / Western PA Regional Data Center — Trees cared for and managed by the City of Pittsburgh Department of Public Works Forestry Division. Tree Benefits are calculated using the National Tree Benefit...

  18. Study of the Variability of the Reflection Component in Seyfert 1 Galaxies: Connecting the Fe K Variability with the Compton Hump

    Science.gov (United States)

    Ponti, G.; Miniutti, G.; Malaguti, G.; Gallo, L.; Goldwurm, A.

    2009-05-01

    We present preliminary results of an ongoing project devoted to the study of the continuum and Fe K band variability in a sample of bright AGNs. These kind of studies may break the spectral degeneracy between the different absorption/emission models, allowing ``safe'' measurements of the disc and black hole properties from the broad line shapes. In fact, the Fe K band, alone, allows a first separation between the different components. Here we show the case of NGC 3783 which shows both a constant and a variable reflection component as well as strong ionized absorption. We show that a fundamental contribution will be given by Simbol-X that will allow to simultaneously measure not only the Fe K variability, but also the connected reflection hump variations.

  19. Biological control of the snail hosts of schistosomiasis in areas of low transmission: the example of the Caribbean area.

    Science.gov (United States)

    Pointier, J P; Jourdane, J

    2000-10-23

    The biological control of schistosomiasis has already proven its efficiency in several habitats in the Caribbean area. Two main types of biological control agents, either trematode parasites or competitor snails have been studied and tested against the snail hosts of schistosomiasis in this region. The first one, Ribeiroia guadeloupensis, a trematode sterilizing Biomphalaria glabrata was successfully tested in a Guadeloupean pond housing a natural population of B. glabrata. The second agent involves several species of competitor snails belonging to the Ampullariidae (Pomacea glauca, Marisa cornuarietis) and Thiaridae (Tarebia granifera, Melanoides tuberculata) families. Ampullarid snails were tested with success in several West Indian islands such as Guadeloupe. Thiarid snails have also proven their efficiency but also their limits in several types of habitats in Guadeloupe, Martinique, St. Lucia and Venezuela. Competitor snails have also proven to be useful in preventing the recolonization by the snail hosts after molluscicide treatments. The case of the rivers of the littoral central part of Venezuela is particularly relevant to this issue. The island of Martinique also constitutes a good example of the importance of competitor snails in a post-transmission phase of schistosomiasis control. This island is a well-developed country where schistosomiasis transmission was interrupted in the 1970s. However, the reactivation of some transmission sites was observed in the 1980s. The introduction of M. tuberculata into these sites resulted in the interruption of transmission and the near total disappearance of the snail hosts. Presently, the thiarid snails have colonized the whole Martinican hydrographic system and maintain dense populations preventing an eventual recolonization by the planorbid snails and thus are maintaining a sustainable control.

  20. 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.

  1. 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

    ). For snails not previously exposed to Bt material, hatchability of eggs was similar in the soils tested. The outcome of the experiments indicates that, in growing snails, long-term exposure is needed to reveal an effect of Bt-maize. The hazard analysis of Bt-maize which we performed, based on a worst......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...

  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. 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.

  4. Reciprocal Regulation between DNA-PKcs and Snail1 Conferring Genomic Instability

    International Nuclear Information System (INIS)

    Seo, Haeng Ran; Lee, Hae June; Jin, Yeung Bae; Bae, Sang Woo; Lee, Yun Sil; Kim, Nam Hee; Kim, Hyun Sil; Nam, Hyung Wook; Yook, Jong In

    2010-01-01

    Although the roles of DNA-dependent protein kinase catalytic subunit (DNA-PKcs) involving non-homologous end joining (NHEJ) of DNA repair are well recognized, the biological mechanisms and regulators by which DNA-PKcs regulate genomic instability are not clearly defined. We show herein that DNA-PKcs activity resulting from DNA damage caused by ionizing radiation (IR) phosphorylates Snail1 at serine 100, which results in increased Snail1 expression and its function by inhibition of GSK-3-mediated phosphorylation. Furthermore, Snail1 phosphorylated at serine 100 can reciprocally inhibit kinase activity of DNA-PKcs, resulting in an inhibition to recruit DNA-PKcs or Ku70/80 to a DNA double-strand break site, and ultimately inhibition of DNA repair activity. The impairment of repair activity by a direct interaction between Snail1 and DNA-PKcs increases the resistance to DNA damaging agents, such as IR, and genomic instability. Our findings provide a novel cellular mechanism for induction of genomic instability by reciprocal regulation of DNA-PKcs and Snail1

  5. Susceptibility of the Giant African snail (Achatina fulica) exposed to the gastropod parasitic nematode Phasmarhabditis hermaphrodita.

    Science.gov (United States)

    Williams, A J; Rae, R

    2015-05-01

    The Giant African snail (Achatina fulica) is a major pest in tropical countries. Current control methods involve the use of slug pellets (metaldehyde) but they are ineffective, therefore new methods of control are needed. We investigated whether A. fulica is susceptible to the gastropod parasitic nematode Phasmarhabditis hermaphrodita, which has been developed as a biological control agent for slugs and snails in northern Europe. We exposed A. fulica to P. hermaphrodita applied at 30 and 150nematodes per cm(2) for 70days and also assessed feeding inhibition and changes in snail weight. We show that unlike the susceptible slug species Deroceras panormitanum, which is killed less than 30days of exposure to P. hermaphrodita, A. fulica is remarkably resistant to the nematode at both doses. Also P. hermaphrodita does not reduce feeding in A. fulica nor did it have any effect on weight gain over 70days. Upon dissection of infected A. fulica we found that hundreds of P. hermaphrodita had been encapsulated, trapped and killed in the snail's shell. We found that A. fulica is able to begin encapsulating P. hermaphrodita after just 3days of exposure and the numbers of nematodes encapsulated increased over time. Taken together, we have shown that A. fulica is highly resistant to P. hermaphrodita, which could be due to an immune response dependent on the snail shell to encapsulate and kill invading parasitic nematodes. Copyright © 2015 Elsevier Inc. All rights reserved.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. Tropomyosin or not tropomyosin, what is the relevant allergen in house dust mite and snail cross allergies?

    Science.gov (United States)

    Bessot, J C; Metz-Favre, C; Rame, J M; De Blay, F; Pauli, G

    2010-02-01

    Since tropomyosin is cross reactive in many arthropods, it was assumed that this highly conserved protein could be responsible for cross reactions in house dust mite (HDM) allergic patients who experienced adverse reactions after crustacean and mollusc ingestion. Here we report two clinical cases where the role of tropomyosin is a matter of debate. In the first case, the clinical history, as well as the results of in vivo and in vitro investigations, are in favour of a shrimp allergy without any snail allergy in a patient sensitized to HDM. In the second, the clinical history and the cutaneous tests are in favour of an allergy to snails without any allergy to shrimps in a patient suffering from HDM allergies. The clinical presentation is different in shrimp and snail allergies. In shrimp allergy, symptoms are mainly urticaria or angio-oedema. In snail allergies, adverse reactions are especially severe asthma. Shrimp tropomyosin is a dominant allergen in crustaceans whereas has a much less prominent role in HDM sensitization. Cross reactivities between HDM and snails have been confirmed by inhibition experiments. However, tropomyosin appears to be a minor allergen or even is not involved in snail allergy. It is necessary to clarify the allergens shared between HDMI and snails. The effects of HDM immunotherapy in snail allergy are questioned. Knowledge of taxonomy can contribute to more precise evaluation of cross reactivities between crustaceans and molluscs.

  14. 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.

  15. Domain analysis of the Nematostella vectensis SNAIL ortholog reveals unique nucleolar localization that depends on the zinc-finger domains

    NARCIS (Netherlands)

    Dattoli, A.A.; Hink, M.A.; DuBuc, T.Q.; Teunisse, B.J.; Goedhart, J.; Röttinger, E.; Postma, M.

    2015-01-01

    SNAIL transcriptional factors are key regulators during development and disease. They arose early during evolution, and in cnidarians such as Nematostella vectensis, NvSNAILA/B are detected in invaginating tissues during gastrulation. The function of SNAIL proteins is well established in bilaterians

  16. [Study on the relationship between Terra-MODIS image and the snail distribution in marshland of Jiangning county, Jiangsu province].

    Science.gov (United States)

    Zhang, Bo; Zhang, Zhi-ying; Xu, De-zhong; Sun, Zhi-dong; Zhou, Xiao-nong; Gong, Zi-li; Liu, Shi-jun; Liu, Cheng; Xu, Bin; Zhou, Yun

    2003-04-01

    To analyze the relationship between the normalized difference vegetation index (NDVI) and the snail distribution in marshland of Jiangning county in Jiangsu province, and to explore the utility of Terra-MODIS image map in the small scale snail habitats surveillance. NDVI were extracted from MODIS image by vector chart of the snail distribution using ArcView 8.1 and ERDAS 8.5 software. The relationship between NDVI and the snail distribution were Investigated using Bivariate correlations and stepwise linear regression. The snail density on marshland was positively correlated with the mean NDVI in the first ten-day of May and the maximum NDVI (N(20max)) in the last ten-day of May. Incidence of pixel with the live snail on marshland was positively correlated with the mean NDVI (N(2mean)) in the first ten-day of May. An equation Y(1) = 0.009 47 x N(20max) (R(2) = 0.73), Y(2) = 0.018 6 x N(2mean) (R(2) = 0.906) was established. This study showed that the Terra-MODIS satellite images reflecting the status of the vegetation on marshland in Jiangning county could be applied to the study to supervise the snail habitat. The results suggested that MODIS images could be used to survey the small scale snail habitats on marshland.

  17. Metagonimoides oregonensis (Heterophyidae:Digenea) Infection in pleurocerid snails and Desmognathus quadramaculatus salamander larvae in southern Appalachian streams

    Science.gov (United States)

    Lisa K. Belden; William E. Peterman; Stephen A. Smith; Lauren R. Brooks; E.F. Benfield; Wesley P. Black; Zhaomin Yang; Jeremy M. Wojdak

    2012-01-01

    Metagonimoides oregonensis (Heterophyidae) is a little-known digenetic trematode that uses raccoons and possibly mink as definitive hosts, and stream snails and amphibians as intermediate hosts. Some variation in the life cycle and adult morphology in western and eastern populations has been previously noted. In the southern Appalachians, Pleurocera snails and stream...

  18. The potential for using red claw crayfish and hybrid African catfish as biological control agents for Schistosoma host snails

    NARCIS (Netherlands)

    Monde, C.; Syampungani, S.; Rico, A.; Brink, van den P.J.

    2017-01-01

    The potential of red claw crayfish and hybrid African catfish (Clarias gariepinus and Clarias ngamensis) as predators for Schistosoma host snails was evaluated in 2014 by monitoring the consumption of snails by crayfish and catfish in experimental tanks over time under laboratory conditions. After

  19. Sympatric and allopatric experimental infections of the planorbid snail Gyraulus chinensis with miracidia of Euparyphium albuferensis (Trematoda: Echinostomatidae).

    Science.gov (United States)

    Muñoz-Antoli, C; Marín, A; Trelis, M; Toledo, R; Esteban, J-G

    2010-12-01

    An experimental infection with echinostomatid miracidia in sympatric or 'local' vs. allopatric or 'away' snail combinations, as a model to examine parasite compatibility, was carried out. We employed Euparyphium albuferensis miracidia to infect Gyraulus chinensis snails, from three different natural parks: Albufera (Valencia, Spain); the Ebro Delta (Tarragona, Spain) and Coto de Doñana (Huelva, Spain). Insignificant differences between the three snail strains were noted for the infection rate and the rhythm of daily cercarial production. However, a significantly higher total cercarial production per snail, patent period and life span were observed in local snails. The different infection characteristics in the three G. chinensis strains considered reveal that E. albuferensis miracidia demonstrate local adaptation.

  20. Growth Performance of Pekin Ducks Fed with Golden Snail and Fresh Banana Peelings

    Directory of Open Access Journals (Sweden)

    Ulep, LJL.

    1995-01-01

    Full Text Available The growth performance and economics of feeding confined Pekin ducks with three different levels of golden snail fresh meat and banana peelings in equal percentage for replacing 50 %, 70 % or 90 % of the commercial feed of the diet was studied. Body weight gains and feed consumption of ducks, cost of feed and profit above feed and stock cost different significantly among treatments. Feed conversion varied during the first month of feeding but became comparable after the second month. Ducks fed the diet with 45 % banana peel and 45 % golden snail meat gave the best performance, were the most economical and yielded the highest profit. Snail meat and banana peeling utilization as replacement to commercial diet for ducks is advantageaous in terms of growth performance and cost benefit.

  1. Bioaccumulation of /sup 95m/Tc in fish and snails

    Energy Technology Data Exchange (ETDEWEB)

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

    1982-03-01

    Concentration factors for technetium recommended in radiological assessment models for freshwater biota are default values based on the behavior of iodine in the environment. In this study a small experimental freshwater pond was spiked with /sup 95/mTc to obtain data for calculating concentration factors for fish and snails. A model using the pond data was developed to calculate steady-state body burdens for freshwater biota. The concentration factors based on the calculated body burden for carp (Caprinus carpio), mosquitofish (Gambusia affinis), and snails (Helisoma sp.) were 11, 75 and 121, respectively. The concentration factor for carp was less than the recommended value of 15 listed in the USNRC Regulatory Guide 1.109 for calculating radiation dose to man; however, the concentration factors for mosquitofish and snails exceeded the recommended values by 5 and 24 times, respectively.

  2. Bioaccumulation of sup(95m)Tc in fish and snails

    Energy Technology Data Exchange (ETDEWEB)

    Blaylock, B.G.; Frank, M.L.; DeAngelis, D.L. (Oak Ridge National Lab., TN (USA))

    1982-03-01

    Concentration factors for technetium recommended in radiological assessment models for freshwater biota are default values based on the behavior of iodine in the environment. A small experimental freshwater pond was spiked with sup(95m)Tc to obtain data for calculating concentration factors for fish and snails. A model using the pond data was developed to calculate steady-state body burdens for freshwater biota. The concentration factors based on the calculated body burden for carp (Caprinus carpio), mosquitofish (Gambusia affinis), and snails (Helisoma sp.) were 11,75 and 121, respectively. The concentration factor for carp was less than the recommended value of 15 listed in the USNRC Regulatory Guide 1.109 for calculating radiation dose to man; however, the concentration factors for mosquitofish and snails exceeded the recommended values by 5 and 25 times, respectively.

  3. 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...

  4. 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

    The geographical ranges of most species, including many infectious disease agents and their vectors and intermediate hosts, are assumed to be constrained by climatic tolerances, mainly temperature. It has been suggested that global warming will cause an expansion of the areas potentially suitable...... 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...... are more likely to contract and/or move into cooler areas in the south and east. Importantly, we also note that even though climate per se matters, the impact of humans on habitat play a crucial role in determining the distribution of the intermediate host snails in Africa. Thus, a future contraction...

  5. Prevalence of Haplorchis taichui in Field-Collected Snails: A Molecular Approach

    Science.gov (United States)

    Chontananarth, Thapana

    2010-01-01

    The prevalence of the cercarial stage of an intestinal trematode, Haplorchis taichui, in thiarid snails (Gastropoda: Thiaridae) was investigated using light microscope and species-specific PCR procedures. A total of 988 snails were collected from Mae Taeng district, Chiang Mai province, northern Thailand, which comprised of 3 species; Melanoides tuberculata, Tarebia granifera, and Thiara scabra. The overall prevalence of pleurolophocercous cercariae was 21.7% as determined by the morphology. For genetic detection of H. taichui infection in snails, 2 primers Hapt_F (5'-GGCCAACGCAATCGTCATCC-3') and Hapt_R (5'-GCGTCGGGTTTCAGACATGG-3'), were used. The genomic DNA of H. taichui, which was used as a positive control, gave an amplification of the 256 bp fragment. The overall prevalence of H. taichui from specific PCR was 9.7%. The proportion of H. taichui among the pleurolophocercous cercariae in this study was 44.9%. PMID:21234240

  6. The use of ionizing radiation in the control of Oncomelania quadrasi snails

    International Nuclear Information System (INIS)

    Cruz, B. de la; Asis, A.V.; Pagulayan, P.; Payongayong, A.; Pineda, R.

    1983-01-01

    Schistosomiasis is still an endemic disease affecting mostly farmers. One way of checking the spread of the disease is to eradicate the intermediate host of parasite. Previous reports indicate that application of nuclear techniques could be a viable tool in the control of parasites of medical importance. To determine whether ionizing radiation could be a useful tool in the control of Oncomelania quadrasi, which is the vector host of Schistosoma japonicum. Attempts have been made to determine whether genetic effects on irradiated male snails can be transmitted to their progenies. These deleterious effects could be either short life span or defective reproductive capacity of the progenies. Attemps were also made to determine whether introduction of irradiated male snails in a given population could reduce the snail density. (author)

  7. 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.

  8. Urban tree growth modeling

    Science.gov (United States)

    E. Gregory McPherson; Paula J. Peper

    2012-01-01

    This paper describes three long-term tree growth studies conducted to evaluate tree performance because repeated measurements of the same trees produce critical data for growth model calibration and validation. Several empirical and process-based approaches to modeling tree growth are reviewed. Modeling is more advanced in the fields of forestry and...

  9. Keeping trees as assets

    Science.gov (United States)

    Kevin T. Smith

    2009-01-01

    Landscape trees have real value and contribute to making livable communities. Making the most of that value requires providing trees with the proper care and attention. As potentially large and long-lived organisms, trees benefit from commitment to regular care that respects the natural tree system. This system captures, transforms, and uses energy to survive, grow,...

  10. Forest snail diversity and its environmental predictors along a sharp climatic gradient in southern Siberia

    Science.gov (United States)

    Horsák, Michal; Juřičková, Lucie; Horsáková, Veronika; Pokorná, Adéla; Pokorný, Petr; Šizling, Arnošt L.; Chytrý, Milan

    2018-04-01

    Diversity patterns of forest snail assemblages have been studied mainly in Europe. Siberian snail faunas have different evolutionary history and colonization dynamics than European faunas, but studies of forest snail diversity are almost missing from Siberia. Therefore, we collected snails at 173 forest sites in the Russian Altai and adjacent areas, encompassing broad variation in climate and forest types. We found 51 species, with a maximum of 15 and an average of seven species per site. The main gradient in species composition was related to soil pH, a variable that also positively correlates with snail abundances. The second gradient was associated with climate characteristics of winter. We observed significant differences in both species richness and composition among six forest types defined based on vegetation classification. Hemiboreal continental forests were the poorest of these types but hosted several species characteristic of European full-glacial stages of the Late Pleistocene. A high snow cover in Temperate coniferous and mixed forests, protecting the soil from freezing, allowed the frost-sensitive large-bodied (>10 mm) species to inhabit this forest type. In contrast to most of the European snail assemblages studied so far we found that the factors responsible for the variation in species richness differed from those driving species composition. This may be attributed to the sharp climatic gradient and the presence of the cold-adapted species typical of the Pleistocene cold stages. We suggest that southern Siberian forests hosting these species can serve as modern analogues of full-glacial forests in periglacial Central and Eastern Europe.

  11. Second intermediate host land snails and definitive host animals of Brachylaima cribbi in southern Australia

    Directory of Open Access Journals (Sweden)

    Butcher A.R.

    2005-03-01

    Full Text Available This study of infection of southern Australian land snails with Brachylaima cribbi metacercariae has shown that all commonly encountered native and introduced snails are susceptible second intermediate hosts. The range of infected snails is extensive with metacercariae-infected snails being present in all districts across southern Australia. C. virgata has the highest average natural metacercarial infection intensity of 6.1 metacercariae per infected snail. The susceptibility of birds, mammals and reptiles to B. cribbi infection was studied in South Australia by capturing, dissecting and examining the intestinal tract contents of animals which commonly eat land snails as a food source. Indigenous Australian little ravens (Corvus mellori, which are a common scavenger bird, and two other passeriform birds, the black bird (Turdus merula and the starling (Sturnus vulgaris, which are both introduced European birds, were found to have the highest infection rates of all animals examined. Other birds found infected with B. cribbi were an emu (Dromaius novaehollandiae, chickens (Gallus gallus and a pigeon (Columba livia. Natural infections were also detected in field mice (Mus domesticus and shingleback lizards (Tiliqua rugosa although the intensity of infection was lower than that observed in birds. Susceptibility studies of laboratory mice, rats and ducks showed that mice developed patent infections which persisted for several weeks, rats developed a short-lived infection of three weeks’ duration and ducks did not support infection. This study has shown for the first time that a brachylaimid can infect a wide host range of birds, mammals and reptiles in nature.

  12. Diversity and biogeography of land snails (Mollusca, Gastropoda) in the limestone hills of Perak, Peninsular Malaysia

    Science.gov (United States)

    Foon, Junn Kitt; Clements, Gopalasamy Reuben; Liew, Thor-Seng

    2017-01-01

    Abstract Limestone hills are now gaining global conservation attention as hotspots for short-range endemic species. Levels of land snail endemism can be high at limestone hills, especially at hill clusters that are geographically isolated. In the State of Perak, Peninsular Malaysia, limestone hills have been opportunistically surveyed for land snails in the past, but the majority have yet to be surveyed. To address this knowledge gap, we systematically surveyed the terrestrial malacofauna of 12 limestone hills that, based on our opinion, are a representation of the limestone land snail assemblages within the State. Our inventory yielded high sampling completeness (>85%). We found 122 species of land snails, of which 34 species were unique to one of the surveyed hills. We identified 30 species that are potentially new to science. The number of land snail species recorded at each hill ranged between 39 and 63 species. Four of the sampled limestone hills namely, Prk 01 G. Tempurung, Prk 55 G. Pondok, Prk 47 Kanthan, and Prk 64 Bt Kepala Gajah, have high levels of species richness and unique species, representing 91% of the total species recorded in this study. We identified two clusters of limestone hills in central Perak with distinct differences in land snail species composition – a northern hill cluster on elevated granite bedrock and southern hill cluster in a low-lying valley surrounded by alluvial soils. As limestone hills continue to be quarried to meet the cement demand, the four identified limestone hills, along with other hills from the two clusters, warrant urgent conservation attention in order to maintain high species diversity within Perak’s terrestrial malacofauna. PMID:28769723

  13. Predator-induced morphological plasticity across local populations of a freshwater snail.

    Directory of Open Access Journals (Sweden)

    Christer Brönmark

    Full Text Available The expression of anti-predator adaptations may vary on a spatial scale, favouring traits that are advantageous in a given predation regime. Besides, evolution of different developmental strategies depends to a large extent on the grain of the environment and may result in locally canalized adaptations or, alternatively, the evolution of phenotypic plasticity as different predation regimes may vary across habitats. We investigated the potential for predator-driven variability in shell morphology in a freshwater snail, Radix balthica, and whether found differences were a specialized ecotype adaptation or a result of phenotypic plasticity. Shell shape was quantified in snails from geographically separated pond populations with and without molluscivorous fish. Subsequently, in a common garden experiment we investigated reaction norms of snails from populations' with/without fish when exposed to chemical cues from tench (Tinca tinca, a molluscivorous fish. We found that snails from fish-free ponds had a narrow shell with a well developed spire, whereas snails that coexisted with fish had more rotund shells with a low spire, a shell morphology known to increase survival rate from shell-crushing predators. The common garden experiment mirrored the results from the field survey and showed that snails had similar reaction norms in response to chemical predator cues, i.e. the expression of shell shape was independent of population origin. Finally, we found significant differences for the trait means among populations, within each pond category (fish/fish free, suggesting a genetic component in the determination of shell morphology that has evolved independently across ponds.

  14. Mitogenomic phylogeny of cone snails endemic to Senegal.

    Science.gov (United States)

    Abalde, Samuel; Tenorio, Manuel J; Afonso, Carlos M L; Zardoya, Rafael

    2017-07-01

    Cone snails attain in Senegal one of their highest peaks of species diversity throughout the continental coast of Western Africa. A total of 15 endemic species have been described, all placed in the genus Lautoconus. While there is ample data regarding the morphology of the shell and the radular tooth of these species, virtually nothing is known regarding the genetic diversity and phylogenetic relationships of one of the most endangered groups of cones. In this work, we determined the complete or near-complete (only lacking the control region) mitochondrial (mt) genomes of 17 specimens representing 11 endemic species (Lautoconus belairensis, Lautoconus bruguieresi, Lautoconus cacao, Lautoconus cloveri, Lautoconus cf. echinophilus, Lautoconus guinaicus, Lautoconus hybridus, Lautoconus senegalensis, Lautoconus mercator, Lautoconus taslei, and Lautoconus unifasciatus). We also sequenced the complete mt genome of Lautoconus guanche from the Canary Islands, which has been related to the cones endemic to Senegal. All mt genomes share the same gene arrangement, which conforms to the consensus reported for Conidae, Neogastropoda and Caenogastropoda. Phylogenetic analyses using probabilistic methods recovered three major lineages, whose divergence coincided in time with sea level and ocean current changes as well as temperature fluctuations during the Messinian salinity crisis and the Plio-Pleistocene transition. Furthermore, the three lineages corresponded to distinct types of radular tooth (robust, small, and elongated), suggesting that dietary specialization could be an additional evolutionary driver in the diversification of the cones endemic to Senegal. The reconstructed phylogeny showed several cases of phenotypic convergence (cryptic species) and questions the validity of some species (ecotypes or phenotypic plasticity), both results having important taxonomic and conservation consequences. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. Utilisation of Giant African snail (Achatina fulica) meal as protein source by laying hens

    OpenAIRE

    Diarra, Siaka Seriba; Kant, Rashmi; Tanhimana, Jemarlyn; Lela, Patrick

    2015-01-01

    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 compa...

  16. [Neuroeffector connections of multimodal neurons in the African snail (Achatina fulica)].

    Science.gov (United States)

    Bugaĭ, V V; Zhuravlev, V L; Safonova, T A

    2004-02-01

    Using a new method of animal preparation, the efferent connections of giant paired neurons on the dorsal surface of visceral and right parietal ganglia of snail, Achatina fulica, were examined. It was found that spikes in giant neurons d-VLN and d-RPLN evoke postjunctional potentials in different points of the snail body and viscerae (in the heart, in pericardium, in lung cavity and kidney walls, in mantle and body wall muscles, in tentacle retractors and in cephalic artery). The preliminary analysis of synaptic latency and facilitation suggests a direct connections between giant neurons and investigated efferents.

  17. Fulicin regulates the female reproductive organs of the snail, Achatina fulica.

    Science.gov (United States)

    Fujisawa, Y; Masuda, K; Minakata, H

    2000-08-01

    Fulicin is a D-amino acid-containing neuropeptide that has been thought to control male copulatory behavior in the land snail, Achatina fulica. In the present study, we demonstrated that the vagina and the oviduct of Achatina were densely innervated by fulicin-like immunoreactive neuronal fibers. We confirmed that fulicin was actually present in the vagina by mass spectrometry. Furthermore, fulicin showed a profound excitatory effect on contractions of the vagina and the oviduct. These results suggest that fulicin controls female egg-laying behavior as an excitatory neuropeptide regulating the female reproductive organs of the snail.

  18. Determination of 3-O- and 4-O-methylated monosaccharide constituents in snail glycans.

    Science.gov (United States)

    Stepan, Herwig; Bleckmann, Christina; Geyer, Hildegard; Geyer, Rudolf; Staudacher, Erika

    2010-07-02

    The N- and O-glycans of Arianta arbustorum, Achatina fulica, Arion lusitanicus and Planorbarius corneus were analysed for their monosaccharide pattern by reversed-phase HPLC after labelling with 2-aminobenzoic acid or 3-methyl-1-phenyl-2-pyrazolin-5-one and by gas chromatography-mass spectrometry. Glucosamine, galactosamine, mannose, galactose, glucose, fucose and xylose were identified. Furthermore, three different methylated sugars were detected: 3-O-methyl-mannose and 3-O-methyl-galactose were confirmed to be a common snail feature; 4-O-methyl-galactose was detected for the first time in snails. Copyright 2010 Elsevier Ltd. All rights reserved.

  19. 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.

  20. Oxidation of glucose-U-/sup 14/C and synthesis of glycogen in different tissues of the garden snail, Cryptozona ligulata with reference to aestivation and starvation

    Energy Technology Data Exchange (ETDEWEB)

    Krupanidhi, S; Raghavaiah, K; Padmanabha Naidu, B; Ramamurthi, R [Sri Venkateswara Univ., Tirupati (India). Dept. of Zoology

    1978-03-01

    The percent decrease of glycogen content in all the tissues investigated is more in 20-days starved snails than the 4-months aestivated snails when compared to active snails. Recovery of administered glucose-U/sup 14/C in the respiratory CO/sub 2/ is 42.27 % in active snails, whereas it is 8.81 % and 26.09 % in aestivated and starved snails respectively. Maximum levels of incorporation labelled glucose were found at 18 hr in all the tissues and the rate of incorporation was greatly elevated in the tissues of aestivated and starved snails. The causes for the difference in the rates of incorporation and the utilization of glycogen in active, aestivated and starved snails are discussed.

  1. Medium rare or well done - how would you like your snail? Influence of cooking practices on the isotopic composition of land snails' shells

    Science.gov (United States)

    Kwiecien, O.; Breitenbach, S. F. M.

    2017-12-01

    Since the seminal work of Goodfriend (1992, EPSL 11), several studies confirmed a relation between the isotopic composition (δ18O, δ13C) of land snail shell carbonate, and environmental parameters like precipitation amount, moisture source, temperature and vegetation. This relation, however, is not straightforward and, importantly, site dependent. The choice of sampling strategy (discrete or bulk sampling), cleaning procedure, and/or pre-depositional history further complicate the shell analysis. The advantage of using snail shells as environmental archive lies in their limited mobility, and thus an intrinsic aptitude of recording local and site-specific conditions. However, snail shells found at archaeological sites, even if of local origin, often represent a dietary component and boiling/roasting could potentially alter the isotopic signature of aragonite material. While thermal processing affects the clumped isotope composition of carbonates, its influence on traditional isotopes is still debated (Ritter et al. 2017, Sedimentology; Müller et al. 2017, Scientific Reports). Consequently, a proper sampling strategy is of great importance and should be chosen according to scientific question. Horizontal high-resolution shell sampling (drill holes along growth axis, across growth lines) provides insights into the amplitude of seasonal variability, while vertical high-resolution sampling (multiple drill holes along the same growth line) produces reproducible results. We took advantage of this reproducibility and, on a yet unprecedented scale, experimentally and sequentially tested the influence of boiling on the δ18O and δ13C signature of shells of modern Helix pomatia. Our results challenge recent reports on alteration due to boiling (Müller et al., 2017, Scientific Reports) and support uncompromised application of snail shells from archeological sites for paleoenvironmental reconstructions.

  2. Fault tree handbook

    International Nuclear Information System (INIS)

    Haasl, D.F.; Roberts, N.H.; Vesely, W.E.; Goldberg, F.F.

    1981-01-01

    This handbook describes a methodology for reliability analysis of complex systems such as those which comprise the engineered safety features of nuclear power generating stations. After an initial overview of the available system analysis approaches, the handbook focuses on a description of the deductive method known as fault tree analysis. The following aspects of fault tree analysis are covered: basic concepts for fault tree analysis; basic elements of a fault tree; fault tree construction; probability, statistics, and Boolean algebra for the fault tree analyst; qualitative and quantitative fault tree evaluation techniques; and computer codes for fault tree evaluation. Also discussed are several example problems illustrating the basic concepts of fault tree construction and evaluation

  3. There's Life in Hazard Trees

    Science.gov (United States)

    Mary Torsello; Toni McLellan

    The goals of hazard tree management programs are to maximize public safety and maintain a healthy sustainable tree resource. Although hazard tree management frequently targets removal of trees or parts of trees that attract wildlife, it can take into account a diversity of tree values. With just a little extra planning, hazard tree management can be highly beneficial...

  4. Role of the lymnaeid snail Pseudosuccinea columella in the transmission of the liver fluke Fasciola hepatica in Egypt.

    Science.gov (United States)

    Dar, Y; Vignoles, P; Rondelaud, D; Dreyfuss, G

    2015-11-01

    Experimental infections of three Egyptian Pseudosuccinea columella populations with sympatric miracidia of Fasciola sp., coming from cattle- or sheep-collected eggs, were carried out to determine the capacity of this lymnaeid to support larval development of the parasite. Using microsatellite markers, the isolates of Egyptian miracidia were identified as Fasciola hepatica. Apart from being independent of snail origin, prevalences ranging from 60.4 to 75.5% in snails infected with five miracidia of F. hepatica were significantly higher than values of 30.4 to 42.2% in snails with bi-miracidial infections. The number of metacercariae ranged from 243 to 472 per cercarial-shedding snail and was independent of snail origin, parasite origin and miracidial dose used for infection. If P. columella was subjected to two successive bi-miracidial infections with F. hepatica, prevalence of infection was 63.3%, with a mean of 311 metacercariae per snail. These values were clearly greater than those already reported for Radix natalensis infected with the same parasite and the same protocol. Successful experimental infection of P. columella with F. hepatica suggests that this lymnaeid snail is an important intermediate host for the transmission of fascioliasis in Egypt.

  5. Copper desorption in flooded agricultural soils and toxicity to the Florida apple snail (Pomacea paludosa): Implications in Everglades restoration

    International Nuclear Information System (INIS)

    Hoang, Tham C.; Rogevich, Emily C.; Rand, Gary M.; Gardinali, Piero R.; Frakes, Robert A.; Bargar, Timothy A.

    2008-01-01

    Copper (Cu) desorption and toxicity to the Florida apple snail were investigated from soils obtained from agricultural sites acquired under the Comprehensive Everglades Restoration Plan. Copper concentrations in 11 flooded soils ranged from 5 to 234 mg/kg on day 0 and from 6.2 to 204 mg/kg on day 28 (steady-state). The steady-state Cu concentration in overlying water ranged from 9.1 to 308.2 μg/L. In a 28-d growth study, high mortality in snails occurred within 9 to 16 d in two of three soil treatments tested. Growth of apple snails over 28 d was affected by Cu in these two treatments. Tissue Cu concentrations by day 14 were 12-23-fold higher in snails exposed to the three soil treatments compared to controls. The endangered Florida snail kite and its main food source, the Florida apple snail, may be at risk from Cu exposure in these managed agricultural soil-water ecosystems. - Copper desorbs from agricultural soils and is toxic to the Florida apple snail

  6. Study on the relationship of abnormal transcription factors OCT4, HBP1 and Snail expression with progression of osteosarcoma

    Directory of Open Access Journals (Sweden)

    Li Li

    2016-09-01

    Full Text Available Objective: To study the relationship of abnormal transcription factors OCT4, HBP1 and Snail expression with progression of osteosarcoma. Methods: Surgical removed osteosarcoma tissue specimens were selected as pathology group, surgically removed osteoid osteoma specimens were selected as control group, and the expression levels of gene transcription factors OCT4, HBP1 and Snail, proliferation genes, epithelial-mesenchymal transition marker molecules in tissue specimens were determined. Results: Oct4 and Snail protein levels of pathology group were significantly higher than those of control group and HBP1 protein level was significantly lower than that of control group; C-myc and cyclinD1 protein levels of pathology group were significantly higher than those of control group, positively correlated with OCT4 and negatively correlated with HBP1; p16 and p53 protein levels were significantly lower than those of control group, negatively correlated with OCT4 and positively correlated with HBP1; N-cadherin and Vimentin protein levels of pathology group were significantly higher than those of control group and positively correlated with Snail while E-cadherin and Occludin protein levels were significantly lower than those of control group and negatively correlated with Snail. Conclusion: Oct4 and Snail are highly expressed and HBP1 is lowly expressed in osteosarcoma tissue, Oct4 and Snail can participate in the regulation of cell proliferation, and HBP1 can participate in the regulation of epithelial-mesenchymal transition of cells.

  7. Heavy metal concentrations in a soil-plant-snail food chain along a terrestrial soil pollution gradient

    Energy Technology Data Exchange (ETDEWEB)

    Notten, M.J.M. [Institute of Ecological Science, Department of Systems Ecology, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV, Amsterdam (Netherlands)]. E-mail: martje.notten@ecology.falw.vu.nl; Oosthoek, A.J.P. [Institute of Ecological Science, Department of Systems Ecology, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV, Amsterdam (Netherlands); Rozema, J. [Institute of Ecological Science, Department of Systems Ecology, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV, Amsterdam (Netherlands); Aerts, R. [Institute of Ecological Science, Department of Systems Ecology, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV, Amsterdam (Netherlands)

    2005-11-15

    We investigated concentrations of Zn, Cu, Cd and Pb in the compartments of a soil-plant (Urtica dioica)-snail (Cepaea nemoralis) food chain in four polluted locations in the Biesbosch floodplains, the Netherlands, and two reference locations. Total soil metal concentrations in the polluted locations were 4-20 times higher than those in the reference locations. Positive relationships between the generally low leaf concentrations and the soil concentrations were found for Zn only (r {sup 2} = 0.20). Bioaccumulation of Zn, Cu and Cd was observed in the snail tissues. We found positive relationships between the snail and leaf concentrations for all metals (range r {sup 2} = 0.19-0.46). The relationships between soil and snail concentrations were also positive, except for Cu (range r {sup 2} = 0.15-0.33). These results suggest transfer of metals to C. nemoralis snails from U. dioica leaves and from the soil. Metal transfer from polluted leaves to C. nemoralis is more important than transfer from the soil. - Bioaccumulation and positive snail-leaf relationships suggest metal transfer from Urtica dioica leaves to Cepaea nemoralis snails.

  8. Heavy metal concentrations in a soil-plant-snail food chain along a terrestrial soil pollution gradient

    International Nuclear Information System (INIS)

    Notten, M.J.M.; Oosthoek, A.J.P.; Rozema, J.; Aerts, R.

    2005-01-01

    We investigated concentrations of Zn, Cu, Cd and Pb in the compartments of a soil-plant (Urtica dioica)-snail (Cepaea nemoralis) food chain in four polluted locations in the Biesbosch floodplains, the Netherlands, and two reference locations. Total soil metal concentrations in the polluted locations were 4-20 times higher than those in the reference locations. Positive relationships between the generally low leaf concentrations and the soil concentrations were found for Zn only (r 2 = 0.20). Bioaccumulation of Zn, Cu and Cd was observed in the snail tissues. We found positive relationships between the snail and leaf concentrations for all metals (range r 2 = 0.19-0.46). The relationships between soil and snail concentrations were also positive, except for Cu (range r 2 = 0.15-0.33). These results suggest transfer of metals to C. nemoralis snails from U. dioica leaves and from the soil. Metal transfer from polluted leaves to C. nemoralis is more important than transfer from the soil. - Bioaccumulation and positive snail-leaf relationships suggest metal transfer from Urtica dioica leaves to Cepaea nemoralis snails

  9. 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...... tree is isomorphic to T? We prove that in the general setting, CST is NP-complete, which implies that the tree edit distance considered here is also NP-hard, even when both input trees having diameters bounded by 10. We also show that, when the number of distinct stars is bounded by a constant k, CTS...

  10. Investigation of the fatty acid composition of the snail Succinea putris L.

    NARCIS (Netherlands)

    Horst, D.J. van der; Voogt, P.A.

    1969-01-01

    1. 1. The incorporation of 1-14C-acetate into some classes of lipids by Succinea putris L. is investigated. 2. 2. This snail is able to synthesize fatty acids from injected acetate. 3. 3. The acetate is also used for the synthesis of non-saponifiable lipids. 4. 4. The fatty acid composition of

  11. Pseudoglessula Libera, a new Subulinid land snail from Guinea, West Africa (Mollusca, Gastropoda Pulmonata)

    NARCIS (Netherlands)

    Solem, A.; Bruggen, van A.C.

    1976-01-01

    Study of some land snails collected in Guinea, West Africa, by Ms. Diane deVry has led to the description of a new species, Pseudoglessula libera. It is currently known only from several localities near Conakry, but probably has a wide distribution. Detailed comparisons with previously described

  12. Fasciola hepatica: Infection Status of Freshwater Snails Collected from Gangwon-do (Province), Korea.

    Science.gov (United States)

    Lee, Jae-Hyung; Quan, Juan-Hua; Choi, In-Wook; Park, Gab-Man; Cha, Guang-Ho; Kim, Hyun-Ju; Yuk, Jae-Min; Lee, Young-Ha

    2017-02-01

    Fasciola hepatica is a trematode that causes zoonosis, mainly in cattle and sheep, and occasionally in humans. Few recent studies have determined the infection status of this fluke in Korea. In August 2015, we collected 402 samples of freshwater snails at Hoenggye-ri (upper stream) and Suha-ri (lower stream) of Song-cheon (stream) in Daegwalnyeong-myeon, Pyeongchang-gun in Gangwon-do (Province) near many large cattle or sheep farms. F. hepatica infection was determined using PCR on the nuclear ribosomal internal transcribed spacer 2 (ITS-2). Among the 402 samples, F. hepatica 1TS-2 marker was detected in 6 freshwater snails; thus, the overall prevalence in freshwater snails was 1.5%. The prevalence varied between collection areas, ranging from 0.0% at Hoenggye-ri to 2.9% at Suha-ri. However, F. gigantica ITS-2 was not detected in the 6 F. hepatica -positive samples by PCR. The nucleotide sequences of the 6 F. hepatica ITS-2 PCR-positive samples were 99.4% identical to the F. hepatica ITS-2 sequences in GenBank, whereas they were 98.4% similar to F. gigantica ITS-2 sequences. These results indicated that the prevalence of F. hepatica in snail intermediate hosts was 1.5% in Gangwon-do, Korea; however the prevalence varied between collection areas. These results may help us to understand F. hepatica infection status in natural environments.

  13. A “Love” Dart Allohormone Identified in the Mucous Glands of Hermaphroditic Land Snails

    NARCIS (Netherlands)

    Stewart, M.J.; Wang, Tianfang; Koene, J.M.; Storey, K.B.; cummns, S.F.

    2016-01-01

    Animals have evolved many ways to enhance their own reproductive success. One bizarre sexual ritual is the "love" dart shooting of helicid snails, which has courted many theories regarding its precise function. Acting as a hypodermic needle, the dart transfers an allohormone that increases paternity

  14. Effects of glyphosate-based herbicides on survival, development and growth of invasive snail (Pomacea canaliculata).

    Science.gov (United States)

    Xu, Yanggui; Li, Adela Jing; Li, Kaibin; Qin, Junhao; Li, Huashou

    2017-12-01

    This study tests the hypotheses that whether environmental relevance of glyphosate would help control spread of the invasive snail Pomacea canaliculata, or benefit its population growth worldwide. Our results showed that glyphosate induced acute toxicity to the snail only at high concentrations (96h LC50 at 175mg/L) unlikely to occur in the environment. Long-term exposures to glyphosate at sublethal levels (20 and 120mg/L) caused inhibition of food intake, limitation of growth performance and alterations in metabolic profiles of the snail. It is worth noting that glyphosate at 2mg/L benefited growth performance in P. canaliculata. Chronic exposures of glyphosate significantly enhanced overall metabolic rate and altered catabolism from protein to carbohydrate/lipid mode. Cellular responses in enzyme activities showed that the exposed snails could increase tolerance by their defense system against glyphosate-induced oxidative stress, and adjustment of metabolism to mitigate energy crisis. Our study displayed that sublethal concentrations of glyphosate might be helpful in control of the invasive species by food intake, growth performance and metabolic interruption; whether environmental relevance of glyphosate (≤2mg/L) benefits population growth of P. canaliculata is still inconclusive, which requires further field study. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Micro-distribution of freshwater snails before and after water flow ...

    African Journals Online (AJOL)

    Bulinus truncatus the intermediate host of Schistosoma haematobium, is widely distributed in modern irrigation schemes in Morocco. These schemes have intermittent irrigation and canals dry out in between irrigation periods. The snail species is therefore associated with the 'siphon boxes' connecting canal segments, ...

  16. Sexual selection on land snail shell ornamentation: a hypothesis that may explain shell diversity

    NARCIS (Netherlands)

    Schilthuizen, M.

    2003-01-01

    Background: Many groups of land snails show great interspecific diversity in shell ornamentation, which may include spines on the shell and flanges on the aperture. Such structures have been explained as camouflage or defence, but the possibility that they might be under sexual selection has not

  17. Tropical sea snail shells: Possible exotic sources for ceramic biomaterial synthesis

    Science.gov (United States)

    Oktar, F. N.; Kiyici, I. A.; Gökçe, H.; Aǧaogulları, D.; Kayali, E. S.

    2013-12-01

    In this study, chemical and structural properties of sea snail shell based bioceramic materials (i.e. hydroxyapatite, whitlockite and other phases) are produced by using mechano-chemical (ultrasonic) conversion method. For this purpose, differential thermal and gravimetric analysis (DTA/TG), X-ray diffraction, infra-red (IR) and scanning electron microscope (SEM) studies are performed.

  18. Tropical sea snail shells: Possible exotic sources for ceramic biomaterial synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Oktar, F. N. [Bioengineering Dept., Faculty of Engineering, Marmara Univ., Istanbul, Turkey, and Medical Imaging Technics Dept., School of Health Related Professions, Marmara Univ., Istanbul, Turkey, and Nanotechnology and Biomaterials Research and Application Cen (Turkey); Kiyici, I. A. [Graduate School of Natural and Applied Sciences, Biomedical Engineering, Kocaeli University, Kocaeli (Turkey); Gökçe, H. [Metallurgical and Materials Engineering Dept., Istanbul Technical Univ., Istanbul, Turkey, and Prof. Dr. Adnan Tekin Material Sciences and Production Technologies Applied Research Center, Istanbul Technical Univ., Istanbul (Turkey); Ağaogulları, D.; Kayali, E. S. [Metallurgical and Materials Engineering Dept., Istanbul Technical Univ., Istanbul (Turkey)

    2013-12-16

    In this study, chemical and structural properties of sea snail shell based bioceramic materials (i.e. hydroxyapatite, whitlockite and other phases) are produced by using mechano-chemical (ultrasonic) conversion method. For this purpose, differential thermal and gravimetric analysis (DTA/TG), X-ray diffraction, infra-red (IR) and scanning electron microscope (SEM) studies are performed.

  19. Hsp70 in the atrial neuroendocrine units of the snail, Achatina fulica.

    Science.gov (United States)

    Martynova, M G; Bystrova, O A; Shabelnikov, S V; Margulis, B A; Prokofjeva, D S

    2007-04-01

    Heat shock proteins (Hsps) are evolutionary conserved peptides well known as molecular chaperones and stress proteins. Elevated levels of extracellular Hsps in blood plasma have been observed during the stress responses and some diseases. Information on the cellular sources of extracellular Hsps and mechanisms regulating their release is still scanty. Here we showed the presence and localization of Hsp70 in the neuroendocrine system in the atrium of the snail, Achatina fulica. The occurrence of the peptide in snail atrium lysate was detected by Western blot analysis. Immunoperoxidase and immunogold staining demonstrated that Hsp70-immunoreactivity is mainly confined to the peculiar atrial neuroendocrine units which are formed by nerve fibers tightly contacted with large granular cells. Immunolabelling intensity differed in morphologically distinct types of secretory granules in the granular cells. The pictures of exocytosis of Hsp70-immunolabeled granules from the granular cells were observed. In nerve bundles, axon profiles with Hsp70-immunoreactive and those with non-immunoreactive neurosecretory granules were found. In addition, Hsp70-like material was also revealed in the granules of glia-interstitial cells that accompanied nerve fibers. Our findings provide an immuno-morphological basis for a role of Hsp70 in the functioning of the neuroendocrine system in the snail heart, and show that the atrial granular cells are a probable source of extracellular Hsp70 in the snail hemolymph.

  20. Natural infection of the feline lungworm Aelurostrongylus abstrusus in the invasive snail Achatina fulica from Argentina.

    Science.gov (United States)

    Valente, Romina; Diaz, Julia Ines; Salomón, Oscar Daniel; Navone, Graciela Teresa

    2017-02-15

    The giant African snail Achatina fulica is an invasive mollusk native to Africa, the first record in Argentina was in Puerto Iguazú, in northeastern Argentina in 2010. Recently it was reported in Corrientes Province. This snail can act as an intermediate host of Metastrongyloidea nematodes of importance in public health as: Angiostrongylus cantonensis, Angiostrongylus costaricensis and Angiostrongylus vasorum. Taking into account the presence of A. fulica in Argentina, the objectives of this study is to assess the presence of Metastrongyloidea nematodes in this mollusk species in Puerto Iguazú, Misiones, close to the international border with Brazil and Paraguay. A total of 451 samples were collected from February 2014 to November 2015. The snails were processed using a digestion technique to recover the parasites. A total of 206 nematodes larvae were founded in the digestion solution of 10 hosts (P=2%; MA=0.5; MI=21). Third larval stage (L3) nematodes identified as Aelurostrongylus abstrusus were founded parasitizing the snails. No other larval stage was observed. This species has veterinary importance because it causes 'aelurostrongilosis', also known as feline strongyloidosis. This study constitutes the first record of a Metastrongyloidea nematode in A. fulica in Argentina and also highlights the susceptibility of this mollusk as intermediate host of other helminthes of health importance. The present study suggests that there is a need to establish an epidemiological monitoring system in order to prevent the possible installation of an infected mollusks focus. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. [Dynamics of the dominance of identified cardioregulatory neurons in the snail Achatina fulica] .

    Science.gov (United States)

    Zhuravlev, V L; Bugaĭ, V V; Safronova, T A

    2000-08-01

    9 cardioregulating neurones belonging to 5 different functional groups were studied in visceral and right parietal ganglia of the Giant African snail Achatina fulica. The neuronal network included multimodal and multifunctional cells exerting short- or long-lasting chronoionotropic effects on the cardiac electro- and mechanograms. Mechanisms of the differences in the cardioregulating effectiveness of these groups were discussed.

  2. [Study of spatial stratified sampling strategy of Oncomelania hupensis snail survey based on plant abundance].

    Science.gov (United States)

    Xun-Ping, W; An, Z

    2017-07-27

    Objective To optimize and simplify the survey method of Oncomelania hupensis snails in marshland endemic regions of schistosomiasis, so as to improve the precision, efficiency and economy of the snail survey. Methods A snail sampling strategy (Spatial Sampling Scenario of Oncomelania based on Plant Abundance, SOPA) which took the plant abundance as auxiliary variable was explored and an experimental study in a 50 m×50 m plot in a marshland in the Poyang Lake region was performed. Firstly, the push broom surveyed data was stratified into 5 layers by the plant abundance data; then, the required numbers of optimal sampling points of each layer through Hammond McCullagh equation were calculated; thirdly, every sample point in the line with the Multiple Directional Interpolation (MDI) placement scheme was pinpointed; and finally, the comparison study among the outcomes of the spatial random sampling strategy, the traditional systematic sampling method, the spatial stratified sampling method, Sandwich spatial sampling and inference and SOPA was performed. Results The method (SOPA) proposed in this study had the minimal absolute error of 0.213 8; and the traditional systematic sampling method had the largest estimate, and the absolute error was 0.924 4. Conclusion The snail sampling strategy (SOPA) proposed in this study obtains the higher estimation accuracy than the other four methods.

  3. 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 -alumina, modified TiO2 (M-TiO2), and commercial TiO2 (C-TiO2) ENPs on the survival, behaviour, and early life stages of the freshwater snail Physa acuta (Draparnaud). The toxicity evaluation was carried out after spiking commercial sand with ENPs concentrations of 0...

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

    Science.gov (United States)

    Robinson, Samuel D.; Li, Qing; Bandyopadhyay, Pradip K.; Gajewiak, Joanna; Yandell, Mark; Papenfuss, Anthony T.; Purcell, Anthony W.; Norton, Raymond S.; Safavi-Hemami, Helena

    2015-01-01

    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, paralysis and sensory overload. Most conotoxins target the prey’s nervous system but evidence of venom peptides targeting neuroendocrine processes is emerging. Examples include vasopressin, RFamide neuropeptides and recently also insulin. To investigate the diversity of hormone/neuropeptide-like molecules 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, including peptides similar to the bee brain hormone prohormone-4, the mollusc ganglia neuropeptide elevenin, and thyrostimulin, a member of the glycoprotein hormone family, and confirmed the presence of insulin. We confirmed that at least two of these peptides are not only expressed in the venom gland but also form part of the injected venom cocktail, unambiguously demonstrating their role in envenomation. Our findings suggest that hormone/neuropeptide-like toxins are a diverse and integral part of the complex envenomation strategy of Conus. Exploration of this group of venom components offers an exciting new avenue for the discovery of novel pharmacological tools and drug candidates, complementary to conotoxins. PMID:26301480

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

    Science.gov (United States)

    Robinson, Samuel D; Li, Qing; Bandyopadhyay, Pradip K; Gajewiak, Joanna; Yandell, Mark; Papenfuss, Anthony T; Purcell, Anthony W; Norton, Raymond S; Safavi-Hemami, Helena

    2017-04-01

    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, paralysis and sensory overload. Most conotoxins target the prey's nervous system but evidence of venom peptides targeting neuroendocrine processes is emerging. Examples include vasopressin, RFamide neuropeptides and recently also insulin. To investigate the diversity of hormone/neuropeptide-like molecules 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, including peptides similar to the bee brain hormone prohormone-4, the mollusc ganglia neuropeptide elevenin, and thyrostimulin, a member of the glycoprotein hormone family, and confirmed the presence of insulin. We confirmed that at least two of these peptides are not only expressed in the venom gland but also form part of the injected venom cocktail, unambiguously demonstrating their role in envenomation. Our findings suggest that hormone/neuropeptide-like toxins are a diverse and integral part of the complex envenomation strategy of Conus. Exploration of this group of venom components offers an exciting new avenue for the discovery of novel pharmacological tools and drug candidates, complementary to conotoxins. Copyright © 2015 Elsevier Inc. All rights reserved.

  6. Reconsolidation of a Context Long-Term Memory in the Terrestrial Snail Requires Protein Synthesis

    Science.gov (United States)

    Gainutdinova, Tatiana H.; Tagirova, Rosa R.; Ismailova, Asja I.; Muranova, Lyudmila N.; Samarova, Elena I.; Gainutdinov, Khalil L.; Balaban, Pavel M.

    2005-01-01

    We investigated the influence of the protein synthesis blocker anisomycin on contextual memory in the terrestrial snail "Helix." Prior to the training session, the behavioral responses in two contexts were similar. Two days after a session of electric shocks (5 d) in one context only, the context conditioning was observed as the significant…

  7. Genetic variability and identification of the intermediate snail hosts of Schistosoma mansoni

    Directory of Open Access Journals (Sweden)

    Teofânia HDA Vidigal

    1998-01-01

    Full Text Available Studies based on shell or reproductive organ morphology and genetic considerations suggest extensive intraspecific variation in Biomphalaria snails. The high variability at the morphological and genetic levels, as well as the small size of some specimens and similarities between species complicate the correct identification of these snails. Here we review our work using methods based on polymerase chain reaction (PCR amplification for analysis of genetic variation and identification of Biomphalaria snails from Brazil, Argentina, Uruguay and Paraguay. Arbitrarily primed-PCR revealed that the genome of B. glabrata exihibits a remarkable degree of intraespecific polymorphism. Low stringency-PCR using primers for 18S rRNA permited the identification of B. glabrata, B. tenagophila and B. occidentalis. The study of individuals obtained from geographically distinct populations exhibits significant intraspecific DNA polymorphism, however specimens from the same species, exhibit some species specific LSPs. We also showed that PCR-restriction fragment of length polymorphism of the internal transcribed spacer region of Biomphalaria rDNA, using DdeI permits the differentiation of the three intermediate hosts of Schistosoma mansoni. The molecular biological techniques used in our studies are very useful for the generation of new knowledge concerning the systematics and population genetics of Biomphalaria snails.

  8. The susceptibility of Marisa cornuarietis, a predator of schistosome bearing snails, to N-tritylmorpholine.

    Science.gov (United States)

    Meier-Brook, C; Tjhen, K Y

    1977-03-01

    Introduction of the ampullariid snail, Marisa cornuarietis (L.), into water treated with molluscicides, in order to secure the success of chemical control of schistosome host snails, is promising. Adult Marisa can be introduced only two days after treating water of pH less than or equal to 7-9 with N-tritylmorpholine (= FresconR Shell) at a concentration of 0-03 ppm. There is considerable variation in the susceptibility of different strains: the LT50 in a concentration of 0-03 ppm Frescon at 25 degrees C was about 27-3 hours for a Puerto Rican and 44-6 hours for a Floridan strain, both 52 weeks old. At sexual maturity, i.e. approximately 18 weeks at 25 degrees C, the LT50 for the Floridan strain was approximately 31-8 hours; experiments with a hybrid stock of the two strains had an LT50 of 30-0 hours. Younger snails were significantly more susceptible to the molluscicide, and eggs were approximately four times more resistant than adults; this agrees with findings by previous authors for other snail species. In the case of the accidental uncontrolled spread of Marisa to cultivated areas it is suggested that a concentration of 0-03 Frescon is applied for at least four days.

  9. Turning snails into slugs: induced body plan changes and formation of an internal shell.

    Science.gov (United States)

    Osterauer, Raphaela; Marschner, Leonie; Betz, Oliver; Gerberding, Matthias; Sawasdee, Banthita; Cloetens, Peter; Haus, Nadine; Sures, Bernd; Triebskorn, Rita; Köhler, Heinz-R

    2010-01-01

    The archetypal body plan of conchiferan molluscs is characterized by an external calcareous shell, though internalization of shells has evolved independently in a number of molluscan clades, including gastropod families. In gastropods, the developmental process of torsion is regarded as a hallmark that is associated with a new anatomical configuration. This configuration is present in extant prosobranch gastropod species, which predominantly bear external shells. Here, we show that short-term exposure to platinum during development uncouples at least two of the processes associated with torsion of the freshwater snail Marisa cornuarietis. That is, the anus of the treated snails is located anteriorly, but the gill and the designated mantle tissue remains in a posterior location, thus preventing the formation of an external shell. In contrast to the prosobranchian archetype, platinum treatment results in the formation of a posterior gill and a cone-shaped internal shell, which persists across the lifetime. This first finding of artificially induced snail-slug conversion was also seen in the pulmonate snail Planorbarius corneus and demonstrates that selective alteration of embryonic key processes can result in fundamental changes of an existing body plan and-if altered regulation is inherited-may give rise to a new one. © 2010 Wiley Periodicals, Inc.

  10. A new alien snail species from the Eger stream, Hungary (Mollusca, Ampullariidae

    Directory of Open Access Journals (Sweden)

    Frisóczki, B.

    2016-11-01

    Full Text Available Our macrozoobenthon samplings carried out in the Eger stream during 2015–2016 resulted in recording an alien species Marisa cornuarietis (Linneaus, 1758 the giant ramshorn snail which has not been reported so far from outdoorwaters in Hungary. Here we report on collecting several specimens from the urban section of the stream close to the outflow of the Eger thermal spa.

  11. Echinostoma revolutum: freshwater snails as the second intermediate hosts in Chiang Mai, Thailand.

    Science.gov (United States)

    Chantima, Kittichai; Chai, Jong-Yil; Wongsawad, Chalobol

    2013-04-01

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

  12. Characterization of gelatin/chitosan scaffold blended with aloe vera and snail mucus for biomedical purpose.

    Science.gov (United States)

    López Angulo, Daniel Enrique; do Amaral Sobral, Paulo José

    2016-11-01

    Biologically active scaffolds used in tissue engineering and regenerative medicine have been generating promising results in skin replacement. The present study aims to test the hypothesis that the incorporation of Aloe vera and snail mucus into scaffolds based on gelatin and chitosan could improve their structure, composition and biodegradability, with a potential effect on bioactivity. Homogeneous pore diameter as well as pore walls in the composite scaffold could be seen in the SEM image. The pores in the scaffolds were interconnected and their sizes ranged from 93 to 296μm. The addition of Aloe vera and snail mucus enlarged the mean pore size with increased porosity and caused changes in the pore architecture. The FTIR analysis has shown good affinity and interaction between the matrix and the Aloe, which may decrease water-binding sites, so this fact hindered the water absorption capacity of the material. The mechanical properties could explain the highest swelling capacity of the snail scaffold, because the high percentage of elongation could facilitate the entry of liquid in it, generating a matrix with plenty of fluid retention. The real innovation in the present work could be the use of these substances (Aloe and snail mucus) for tissue engineering. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. A checklist of land snails from the west coast islands of Sabah, Borneo (Mollusca, Gastropoda

    Directory of Open Access Journals (Sweden)

    Chee-Chean Phung

    2017-05-01

    Full Text Available Sabah, situated in one of the world’s biodiversity hotspots, has the largest number of islands in Malaysia with more than 500 of various sizes and degrees of isolation. However, information on the islands’ biodiversity is limited. This study provides an up-to-date checklist of land snail species found on 24 west coast islands in Sabah. A total of 67 species (nearly 20% of the total number of land snail species in the state representing 37 genera and 19 families is enumerated based on systematic field surveys of 133 sampling plots, BORNEENSIS database records and species checklists published between 2000 and 2016. The number of species on the islands ranges from four to 29. Labuan Island has the highest number of species (29, followed by Tiga Island (25, Mantanani Besar Island (24 and Gaya Island (23. However, the populations of some land snail species may have declined as several previously recorded species on the islands were not found in a recent systematic field sampling. This checklist is provided as a baseline inventory for future island land snail studies and to better inform biodiversity conservation plans of marine parks and other islands on the Sabah west coast.

  14. Host ploidy, parasitism and immune defence in a coevolutionary snail-trematode system.

    Science.gov (United States)

    Osnas, E E; Lively, C M

    2006-01-01

    We studied the role of host ploidy and parasite exposure on immune defence allocation in a snail-trematode system (Potamopyrgus antipodarum-Microphallus sp.). In the field, haemocyte (the defence cell) concentration was lowest in deep-water habitats where infection is relatively low and highest in shallow-water habitats where infection is common. Because the frequency of asexual triploid snails is positively correlated with depth, we also experimentally studied the role of ploidy by exposing both diploid sexual and triploid asexual snails to Microphallus eggs. We found that triploid snails had lower haemocyte concentrations than did diploids in both parasite-addition and parasite-free treatments. We also found that both triploids and diploids increased their numbers of large granular haemocytes at similar rates after parasite exposure. Because triploid P. antipodarum have been shown to be more resistant to allopatric parasites than diploids, the current results suggest that the increased resistance of triploids is because of intrinsic genetic properties rather than to greater allocation to defence cells. This finding is consistent with recent theory on the advantages of increased ploidy for hosts combating coevolving parasites.

  15. Assessment of Toxic Metals and feed habits of the snail Pomacea specie from the Amatitlan Lake

    International Nuclear Information System (INIS)

    Roesch Palomo, R.R.

    1998-01-01

    In the present thesis an assesment of cadmium, cooper, cromium VI, and lead was made in samples of snail pomacea specie from the Amatitlan Lake. We conclude that the comsuption of this mollusk is toxic for human health. The concentration of heavy metals like cadmium, cooper shows that are not recomended for human comsuption according to Spanish and FAO/PAHO standards

  16. Effects of snails, submerged plants and their coexistence on eutrophication in aquatic ecosystems

    Directory of Open Access Journals (Sweden)

    Mo Shuqing

    2017-01-01

    Full Text Available Eutrophication resulting from nutrient loading to freshwater habitats is a severe problem, leading to degradation of ecosystems, including deterioration of water quality, water clarity and loss of biodiversity. Measures enacted to restore degraded freshwater ecosystems often involve the reintroduction of submerged plants and aquatic animals with beneficial ecological functions. In a mesocosm experiment, three treatments (planting with Vallisneria natans, introduction of the snail Bellamya aeruginosa and a combined treatment with both plants and snails were compared with controls to evaluate their effects on trophic state. The total nitrogen (TN, total phosphorus (TP and chlorophyll a (Chl a concentrations of planktonic and benthic algal samples were determined every two weeks, along with light intensity at the sediment surface. The plant-only treatment significantly reduced the TN levels and planktonic and benthic algal biomass and increased the light intensity at the sediment surface. The snail-only treatment reduced the concentrations of TN and reduced planktonic and benthic algal biomass. The combined treatment decreased the concentrations of TN and TP, reduced planktonic algal biomass and increased the light intensity on the sediment surface. The results indicate that while submerged plants and snails can both improve water quality, the most pronounced effect in aquatic ecosystems is achieved by their presence in combination. A combined reintroduction approach may provide enhanced benefits in restoring the eutrophic ecosystems, following the reduction of external nutrient loading.

  17. A Targeted Capture Linkage Map Anchors the Genome of the Schistosomiasis Vector Snail, Biomphalaria glabrata.

    Science.gov (United States)

    Tennessen, Jacob A; Bollmann, Stephanie R; Blouin, Michael S

    2017-07-05

    The aquatic planorbid snail Biomphalaria glabrata is one of the most intensively-studied mollusks due to its role in the transmission of schistosomiasis. Its 916 Mb genome has recently been sequenced and annotated, but it remains poorly assembled. Here, we used targeted capture markers to map over 10,000 B. glabrata scaffolds in a linkage cross of 94 F1 offspring, generating 24 linkage groups (LGs). We added additional scaffolds to these LGs based on linkage disequilibrium (LD) analysis of targeted capture and whole-genome sequences of 96 unrelated snails. Our final linkage map consists of 18,613 scaffolds comprising 515 Mb, representing 56% of the genome and 75% of genic and nonrepetitive regions. There are 18 large (> 10 Mb) LGs, likely representing the expected 18 haploid chromosomes, and > 50% of the genome has been assigned to LGs of at least 17 Mb. Comparisons with other gastropod genomes reveal patterns of synteny and chromosomal rearrangements. Linkage relationships of key immune-relevant genes may help clarify snail-schistosome interactions. By focusing on linkage among genic and nonrepetitive regions, we have generated a useful resource for associating snail phenotypes with causal genes, even in the absence of a complete genome assembly. A similar approach could potentially improve numerous poorly-assembled genomes in other taxa. This map will facilitate future work on this host of a serious human parasite. Copyright © 2017 Tennessen et al.

  18. Effects of Endosulfan on Predator–Prey Interactions Between Catfish and Schistosoma Host Snails

    NARCIS (Netherlands)

    Monde, Concillia; Syampungani, Stephen; Brink, van den Paul J.

    2016-01-01

    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

  19. Chemoreception niche of Bulinus globosus , as an aid to snail control

    African Journals Online (AJOL)

    Schistosomiasis has been a major public health problem especially in developing countries, where access to potable water is generally limited. Its control calls for a search for various interventions that would not only target the causative agent and human behavior, but also the snail intermediate host. This study explored the ...

  20. Invasive snails and an emerging infectious disease: results from the first national survey on Angiostrongylus cantonensis in China.

    Directory of Open Access Journals (Sweden)

    Shan Lv

    Full Text Available BACKGROUND: Eosinophilic meningitis (angiostrongyliasis caused by Angiostrongylus cantonensis is emerging in mainland China. However, the distribution of A. cantonensis and its intermediate host snails, and the role of two invasive snail species in the emergence of angiostrongyliasis, are not well understood. METHODOLOGY/PRINCIPAL FINDINGS: A national survey pertaining to A. cantonensis was carried out using a grid sampling approach (spatial resolution: 40x40 km. One village per grid cell was randomly selected from a 5% random sample of grid cells located in areas where the presence of the intermediate host snail Pomacea canaliculata had been predicted based on a degree-day model. Potential intermediate hosts of A. cantonensis were collected in the field, restaurants, markets and snail farms, and examined for infection. The infection prevalence among intermediate host snails was estimated, and the prevalence of A. cantonensis within P. canaliculata was displayed on a map, and predicted for non-sampled locations. It was confirmed that P. canaliculata and Achatina fulica were the predominant intermediate hosts of A. cantonensis in China, and these snails were found to be well established in 11 and six provinces, respectively. Infected snails of either species were found in seven provinces, closely matching the endemic area of A. cantonensis. Infected snails were also found in markets and restaurants. Two clusters of A. cantonensis-infected P. canaliculata were predicted in Fujian and Guangxi provinces. CONCLUSIONS/SIGNIFICANCE: The first national survey in China revealed a wide distribution of A. cantonensis and two invasive snail species, indicating that a considerable number of people are at risk of angiostrongyliasis. Health education, rigorous food inspection and surveillance are all needed to prevent recurrent angiostrongyliasis outbreaks.

  1. Invasive Snails and an Emerging Infectious Disease: Results from the First National Survey on Angiostrongylus cantonensis in China

    Science.gov (United States)

    Lv, Shan; Zhang, Yi; Liu, He-Xiang; Hu, Ling; Yang, Kun; Steinmann, Peter; Chen, Zhao; Wang, Li-Ying; Utzinger, Jürg; Zhou, Xiao-Nong

    2009-01-01

    Background Eosinophilic meningitis (angiostrongyliasis) caused by Angiostrongylus cantonensis is emerging in mainland China. However, the distribution of A. cantonensis and its intermediate host snails, and the role of two invasive snail species in the emergence of angiostrongyliasis, are not well understood. Methodology/Principal Findings A national survey pertaining to A. cantonensis was carried out using a grid sampling approach (spatial resolution: 40×40 km). One village per grid cell was randomly selected from a 5% random sample of grid cells located in areas where the presence of the intermediate host snail Pomacea canaliculata had been predicted based on a degree-day model. Potential intermediate hosts of A. cantonensis were collected in the field, restaurants, markets and snail farms, and examined for infection. The infection prevalence among intermediate host snails was estimated, and the prevalence of A. cantonensis within P. canaliculata was displayed on a map, and predicted for non-sampled locations. It was confirmed that P. canaliculata and Achatina fulica were the predominant intermediate hosts of A. cantonensis in China, and these snails were found to be well established in 11 and six provinces, respectively. Infected snails of either species were found in seven provinces, closely matching the endemic area of A. cantonensis. Infected snails were also found in markets and restaurants. Two clusters of A. cantonensis–infected P. canaliculata were predicted in Fujian and Guangxi provinces. Conclusions/Significance The first national survey in China revealed a wide distribution of A. cantonensis and two invasive snail species, indicating that a considerable number of people are at risk of angiostrongyliasis. Health education, rigorous food inspection and surveillance are all needed to prevent recurrent angiostrongyliasis outbreaks. PMID:19190771

  2. Polyethylene Glycol Mediated Colorectal Cancer Chemoprevention: Roles of Epidermal Growth Factor Receptor and Snail

    Science.gov (United States)

    Wali, Ramesh K.; Kunte, Dhananjay P.; Koetsier, Jennifer L.; Bissonnette, Marc; Roy, Hemant K.

    2008-01-01

    Polyethylene glycol (PEG) is a clinically widely used agent with profound chemopreventive properties in experimental colon carcinogenesis. We previously reported that Snail/β-catenin signaling may mediate the suppression of epithelial proliferation by PEG, although the upstream events remain unclear. We report herein the role of epidermal growth factor receptor (EGFR), a known mediator of Snail and overepressed in ~80% of human colorectal cancers (CRC), on PEG-mediated anti-proliferative and hence anti-neoplastic effects in azoxymethane (AOM)-rats and HT-29 colon cancer cells. AOM-rats were randomized to either standard diet or one with 10% PEG 3350 and euthanized 8 weeks later. The colonic samples were subjected to immunohistochemical or Western blot analyses. PEG decreased mucosal EGFR by 60% (pPEG effects were obtained in HT-29 cells. PEG suppressed EGFR protein via lysosmal degradation with no change in mRNA levels. To show that EGFR antagonism per se was responsible for the antiproliferative effect, we inhibited EGFR by either pre-treating cells with gefitinib or stably transfecting with EGFR-shRNA and measured the effect of PEG on proliferation. In either case PEG effect was blunted suggesting a vital role of EGFR. Flow cytometric analysis revealed that EGFR-shRNA cells, besides having reduced membrane EGFR also expressed low Snail levels (40%), corroborating a strong association. Furthermore, in EGFR silenced cells PEG effect on EGFR or Snail was muted, similar to that on proliferation. In conclusion, we show that EGFR is the proximate membrane signaling molecule through which PEG initiates antiproliferative activity with Snail/β-catenin pathway playing the central intermediary function. PMID:18790788

  3. Polyethylene glycol-mediated colorectal cancer chemoprevention: roles of epidermal growth factor receptor and Snail.

    Science.gov (United States)

    Wali, Ramesh K; Kunte, Dhananjay P; Koetsier, Jennifer L; Bissonnette, Marc; Roy, Hemant K

    2008-09-01

    Polyethylene glycol (PEG) is a clinically widely used agent with profound chemopreventive properties in experimental colon carcinogenesis. We reported previously that Snail/beta-catenin signaling may mediate the suppression of epithelial proliferation by PEG, although the upstream events remain unclear. We report herein the role of epidermal growth factor receptor (EGFR), a known mediator of Snail and overexpressed in approximately 80% of human colorectal cancers, on PEG-mediated antiproliferative and hence antineoplastic effects in azoxymethane (AOM) rats and HT-29 colon cancer cells. AOM rats were randomized to either standard diet or one with 10% PEG-3350 and euthanized 8 weeks later. The colonic samples were subjected to immunohistochemical or Western blot analyses. PEG decreased mucosal EGFR by 60% (P PEG effects were obtained in HT-29 cells. PEG suppressed EGFR protein via lysosmal degradation with no change in mRNA levels. To show that EGFR antagonism per se was responsible for the antiproliferative effect, we inhibited EGFR by either pretreating cells with gefitinib or stably transfecting with EGFR-short hairpin RNA and measured the effect of PEG on proliferation. In either case, PEG effect was blunted, suggesting a vital role of EGFR. Flow cytometric analysis revealed that EGFR-short hairpin RNA cells, besides having reduced membrane EGFR, also expressed low Snail levels (40%), corroborating a strong association. Furthermore, in EGFR silenced cells, PEG effect on EGFR or Snail was muted, similar to that on proliferation. In conclusion, we show that EGFR is the proximate membrane signaling molecule through which PEG initiates antiproliferative activity with Snail/beta-catenin pathway playing the central intermediary function.

  4. Physiology of the invasive apple snail Pomacea maculata: tolerance to low temperatures

    Science.gov (United States)

    Deaton, Lewis E.; Schmidt, William; Leblanc, Brody; Carter, Jacoby; Mueck, Kristy; Merino, Sergio

    2016-01-01

    Apple snails of the genus Pomacea native to South America have invaded and become established in Europe, Asia, and the United States. Both the channeled apple snail Pomacea canaliculata and the island apple snail Pomacea maculata have been reported in the United States. The two species are difficult to distinguish using morphological characters, leading to uncertainty about the identity of the animals from populations in the United States. Because the snails are subtropical, their tolerance of low temperatures is a critical factor in limiting the spread of the animals from present localities along the coast of the Gulf of Mexico to more northern areas. The tolerance of P. maculata collected in Louisiana to temperatures as low as 0°C was examined. There was no mortality among animals maintained in water at temperatures of 20°C or 15°C for 10 days. Survival of animals during a 10-day exposure to water at temperatures 10°C and 5°C was 50%. The LD50 for a 10-day exposure was 7°C. Snails did not survive more than 5 days in liquid water at 0°C. Ammonia excretion by animals in temperatures of 20°C and 15°C was comparable to values reported for freshwater gastropods; at very low temperatures, excretion of ammonia was decreased. There was no difference in the mean values of the osmolality of the hemolymph of animals exposed to 20°C, 15°C and 10°C for 10 days. Sequencing of mitochondrial cytochrome oxidase 1 identified the animals in the Louisiana population used in this study as P. maculata.

  5. Impairment of context memory by β-amyloid peptide in terrestrial snail

    Directory of Open Access Journals (Sweden)

    2008-09-01

    Full Text Available We examined influence of the β-amyloid peptide (25-35 neurotoxic fragment (βAP on Helix lucorum food-aversion learning. Testing with aversively conditioned carrot showed that 2, 5, and 14 days after training the βAP-injected group responded in a significantly larger number of cases and with a significantly smaller latency than the sham-injected control group. The results demonstrate that the amyloid peptide partially impairs the learning process. In an attempt to specify what component of memory is impaired we compared responses in a context in which the snails were aversively trained, and in a neutral context. It was found that the sham-injected learned snails significantly less frequently took the aversively conditioned food in the context in which the snails were shocked, while the βAP-injected snails remembered the aversive context 2 days after associative training, but were not able to distinguish two contexts 5, and 14 days after training. In a separate series of experiments a specific context was associated with electric shock, and changes in general responsiveness were tested in two contexts several days later. It was found that the βAP-injected snails significantly increased withdrawal responses in all tested contexts, while the sham-injected control animals selectively increased responsiveness only in the context in which they were reinforced with electric shocks. These results demonstrate that the β-amyloid peptide (25-35 interferes with the learning process, and may play a significant role in behavioral plasticity and memory by selectively impairing only one

  6. Soil calcium availability influences shell ecophenotype formation in the sub-antarctic land snail, Notodiscus hookeri.

    Directory of Open Access Journals (Sweden)

    Maryvonne Charrier

    Full Text Available Ecophenotypes reflect local matches between organisms and their environment, and show plasticity across generations in response to current living conditions. Plastic responses in shell morphology and shell growth have been widely studied in gastropods and are often related to environmental calcium availability, which influences shell biomineralisation. To date, all of these studies have overlooked micro-scale structure of the shell, in addition to how it is related to species responses in the context of environmental pressure. This study is the first to demonstrate that environmental factors induce a bi-modal variation in the shell micro-scale structure of a land gastropod. Notodiscus hookeri is the only native land snail present in the Crozet Archipelago (sub-Antarctic region. The adults have evolved into two ecophenotypes, which are referred to here as MS (mineral shell and OS (organic shell. The MS-ecophenotype is characterised by a thick mineralised shell. It is primarily distributed along the coastline, and could be associated to the presence of exchangeable calcium in the clay minerals of the soils. The Os-ecophenotype is characterised by a thin organic shell. It is primarily distributed at high altitudes in the mesic and xeric fell-fields in soils with large particles that lack clay and exchangeable calcium. Snails of the Os-ecophenotype are characterised by thinner and larger shell sizes compared to snails of the MS-ecophenotype, indicating a trade-off between mineral thickness and shell size. This pattern increased along a temporal scale; whereby, older adult snails were more clearly separated into two clusters compared to the younger adult snails. The prevalence of glycine-rich proteins in the organic shell layer of N. hookeri, along with the absence of chitin, differs to the organic scaffolds of molluscan biominerals. The present study provides new insights for testing the adaptive value of phenotypic plasticity in response to spatial

  7. Invading freshwater snails and biological control in Martinique Island, French West Indies

    Directory of Open Access Journals (Sweden)

    Jean-Pierre Pointier

    2001-09-01

    Full Text Available Eight alien freshwater snail species were introduced into Martinique Island during the last 50 years. The introduced snails include four planorbids (Biomphalaria straminea, Helisoma duryi, Amerianna carinata and Gyraulus sp., three thiarids (Melanoides tuberculata, M. amabilis and Tarebia granifera and one ampullarid (Marisa cornuarietis. Four of these species rapidly colonized the whole Martinican hydrographic system whereas the other four remained restricted to some particular sites. The invasion processes were documented during the last 20 years and showed (i a rapid invasion of the island by several morphs of M. tuberculata at the beginning of the 80's; (ii the introduction of T. granifera in 1991 and M. amabilis in 1997; and (iii the rapid spread of these last two species throughout the island. In the years following its introduction, M. tuberculata was used in biological control experiments against the snail hosts of schistosomiasis, B. glabrata and B. straminea. Experiments were conducted with success in several groups of water-cress beds which constituted the latest transmission sites for schistosomiasis at the beginning of the 80's. A malacological survey carried out in 2000 all over the island showed the absence of B. glabrata but the presence of some residual populations of B. straminea. Long-term studies carried out in Martinique have shown that the thiarids are able to maintain relatively stable populations over a long period of time, thus preventing recolonization by the snail hosts. Within this context the invasion of the hydrographic system of Martinique by thiarid snails has resulted in an efficient and sustainable control of the intermediate hosts of schistosomiasis.

  8. Invading freshwater snails and biological control in Martinique Island, French West Indies.

    Science.gov (United States)

    Pointier, J P

    2001-01-01

    Eight alien freshwater snail species were introduced into Martinique Island during the last 50 years. The introduced snails include four planorbids (Biomphalaria straminea, Helisoma duryi, Amerianna carinata and Gyraulus sp.), three thiarids (Melanoides tuberculata, M. amabilis and Tarebia granifera) and one ampullarid (Marisa cornuarietis). Four of these species rapidly colonized the whole Martinican hydrographic system whereas the other four remained restricted to some particular sites. The invasion processes were documented during the last 20 years and showed (i) a rapid invasion of the island by several morphs of M. tuberculata at the beginning of the 80's; (ii) the introduction of T. granifera in 1991 and M. amabilis in 1997; and (iii) the rapid spread of these last two species throughout the island. In the years following its introduction, M. tuberculata was used in biological control experiments against the snail hosts of schistosomiasis, B. glabrata and B. straminea. Experiments were conducted with success in several groups of water-cress beds which constituted the latest transmission sites for schistosomiasis at the beginning of the 80's. A malacological survey carried out in 2000 all over the island showed the absence of B. glabrata but the presence of some residual populations of B. straminea. Long-term studies carried out in Martinique have shown that the thiarids are able to maintain relatively stable populations over a long period of time, thus preventing recolonization by the snail hosts. Within this context the invasion of the hydrographic system of Martinique by thiarid snails has resulted in an efficient and sustainable control of the intermediate hosts of schistosomiasis.

  9. Apple snails and their endosymbionts bioconcentrate heavy metals and uranium from contaminated drinking water.

    Science.gov (United States)

    Vega, Israel A; Arribére, María A; Almonacid, Andrea V; Ribeiro Guevara, Sergio; Castro-Vazquez, Alfredo

    2012-09-01

    The differential ability of apple snail tissues, endosymbionts, and eggs to bioaccumulate several metals (Sb, As, Ba, Br, Zn, Cr, Fe, Hg, Se, and U) was investigated. Metal concentrations were determined by neutron activation analysis in several tissues, endosymbionts, and eggs from mature apple snails cultured in either drinking water or reconstituted water (prepared with American Society for Testing and Materials type I water). The highest bioconcentration factors (BCFs) in the midgut gland were found for Ba, Zn, Se, As, U, Br, and Hg (in decreasing order), while the highest in the kidney were for Ba, Br, and Hg. The foot showed the highest BCFs for Ba, Hg, Br, and Se (in decreasing order). Calcified tissues (uterus, shell) and eggs showed low BCFs, except for Ba. Both C corpuscles and gland tissue showed statistically higher BCFs than K corpuscles for Ba, Fe, U, Br, and Sb. The concentration of most of the studied elements was significantly lower in tissues and endosymbionts obtained from snails cultured in reconstituted water instead of drinking water. Snails cultured in reconstituted water and then exposed or not to Hg, As, and U (at the maximum contaminant level allowed by the US Environmental Protection Agency) also resulted in high levels accumulated in midgut gland, endosymbionts and kidney. Our findings suggest that the midgut gland (and the symbionts contained therein), the kidney, and the foot of Pomacea canaliculata may be useful bioindicators of Hg, As and U pollution in freshwater bodies and that the unrestricted use of ampullariid snails as human and animal food must be considered with caution.

  10. Prime waterfront real estate: Apple snails choose wild taro for oviposition sites

    Directory of Open Access Journals (Sweden)

    Colin H. KYLE, Alexis W. KROPF, Romi L. BURKS

    2011-10-01

    Full Text Available While difficult to prevent introductions, scientific research can help guide control efforts of exotic, invasive species. South American island apple snails Pomacea insularum have quickly spread across the United States Gulf Coast and few control measures exist to delay their spread. Usually occupying cryptic benthic habitats, female apple snails crawl out of the water to deposit large, bright pink egg clutches on emergent objects. To help identify the most likely place to find and remove clutches, we conducted four lab experiments to investigate what specific object qualities (i.e. material; shape and height; plant species; natural and artificial attracted P. insularum females to lay clutches. In our fourth experiment, we specifically examined the relationship between female size and reproductive output. To further understand reproductive output, we quantified experimental clutch chara- cteristics (height above water, dimensions, mass, approximate volume, number of eggs, hatching efficiency. Pomacea insularum females laid more clutches on plant material, chose round over flat surfaces and failed to differentiate between tall and short structures. In comparison to a common native plant in the eastern US, Pontederia cordata, snails clearly preferred to lay clutches on a widely distributed exotic, invasive plant (wild taro, Colocasia esculenta. Unexpectedly, smaller snails showed higher overall total fecundity as well as more eggs per clutch than larger snails. Therefore, hand removal efforts of large females may not be enough to slow down clutch production. Collectively, our results indicate that conservationists and managers should search emergent plants for P. insularum clutches carefully to guard against established populations [Current Zoology 57 (5: 630–641, 2011].

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

    DEFF Research Database (Denmark)

    Kara, E.; Zoghbi, A.; Marinucci, A.

    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...... 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...

  12. Turbulence growth and its dependency of wake vortices on excitation frequency by local body-force around two-dimensional hump

    Science.gov (United States)

    Yakeno, Aiko; Abe, Yoshiaki; Nonomura, Taku; Kawai, Soshi; Fujii, Kozo

    2017-11-01

    We investigated details of wake vortex dynamics to cause turbulence increase and early flow-reattachment under excitation forcing by a plasma actuator setting around a 2D hump numerically. The local body-force was homogeneous in the spanwise direction and bursting temporally. That actuation generates two-dimensional roll vortices and other turbulence motions such like three-dimensional rib structure in downstream. These dynamics depended on the excitation frequency. We tried to discuss multi-scaled vortices separately with considering the temporal phaseaveraged statistics of the excitation frequency and others, those are related to roll vortices and others with rib structure between rolls. It was found that the maximum value of non-periodic fluctuation in downstream correlated with flow-reattachment performance more than that of periodic fluctuation of roll vortices. The amplitude becomes large around separation position in early reattachment cases. The spacial growth rates of peak values in the wall-normal direction are same for high frequency cases, K-H instability modes, however not true for low frequency cases. In high frequency cases, amplitude in the early state of separation plays a significant rule to increase it in downstream. Strategic Programs for Innovative Research of the High Performance Computing Initiative (No. hp120296,hp130001,hp140207, hp150219) Grant-in-Aid for Scientific Research(B) (No. 15K21677) by the MEXT.

  13. Trees and highway safety.

    Science.gov (United States)

    2011-03-01

    To minimize the severity of run-off-road collisions of vehicles with trees, departments of transportation (DOTs) : commonly establish clear zones for trees and other fixed objects. Caltrans clear zone on freeways is 30 feet : minimum (40 feet pref...

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

    Directory of Open Access Journals (Sweden)

    Iman F. Abou-El-Naga

    2012-09-01

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

  15. Decision-Tree Program

    Science.gov (United States)

    Buntine, Wray

    1994-01-01

    IND computer program introduces Bayesian and Markov/maximum-likelihood (MML) methods and more-sophisticated methods of searching in growing trees. Produces more-accurate class-probability estimates important in applications like diagnosis. Provides range of features and styles with convenience for casual user, fine-tuning for advanced user or for those interested in research. Consists of four basic kinds of routines: data-manipulation, tree-generation, tree-testing, and tree-display. Written in C language.

  16. Minnesota's Forest Trees. Revised.

    Science.gov (United States)

    Miles, William R.; Fuller, Bruce L.

    This bulletin describes 46 of the more common trees found in Minnesota's forests and windbreaks. The bulletin contains two tree keys, a summer key and a winter key, to help the reader identify these trees. Besides the two keys, the bulletin includes an introduction, instructions for key use, illustrations of leaf characteristics and twig…

  17. 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...

  18. 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 ...

  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. TreePics: visualizing trees with pictures

    Directory of Open Access Journals (Sweden)

    Nicolas Puillandre

    2017-09-01

    Full Text Available While many programs are available to edit phylogenetic trees, associating pictures with branch tips in an efficient and automatic way is not an available option. Here, we present TreePics, a standalone software that uses a web browser to visualize phylogenetic trees in Newick format and that associates pictures (typically, pictures of the voucher specimens to the tip of each branch. Pictures are visualized as thumbnails and can be enlarged by a mouse rollover. Further, several pictures can be selected and displayed in a separate window for visual comparison. TreePics works either online or in a full standalone version, where it can display trees with several thousands of pictures (depending on the memory available. We argue that TreePics can be particularly useful in a preliminary stage of research, such as to quickly detect conflicts between a DNA-based phylogenetic tree and morphological variation, that may be due to contamination that needs to be removed prior to final analyses, or the presence of species complexes.

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

    Science.gov (United States)

    ABSTRACT Imposex, the development of male sex characteristics by female gonochoristic snails, has been causally associated with exposure to the ubiquitous environmental contaminant tributyltin (TBT). Documentation of imposex distribution indicates that this masculinizat...

  3. Adaptive Changes in the Vestibular System of Land Snail to a 30-Day Spaceflight and Readaptation on Return to Earth

    Directory of Open Access Journals (Sweden)

    Nikolay Aseyev

    2017-11-01

    Full Text Available The vestibular system receives a permanent influence from gravity and reflexively controls equilibrium. If we assume gravity has remained constant during the species' evolution, will its sensory system adapt to abrupt loss of that force? We address this question in the land snail Helix lucorum exposed to 30 days of near weightlessness aboard the Bion-M1 satellite, and studied geotactic behavior of postflight snails, differential gene expressions in statocyst transcriptome, and electrophysiological responses of mechanoreceptors to applied tilts. Each approach revealed plastic changes in the snail's vestibular system assumed in response to spaceflight. Absence of light during the mission also affected statocyst physiology, as revealed by comparison to dark-conditioned control groups. Readaptation to normal tilt responses occurred at ~20 h following return to Earth. Despite the permanence of gravity, the snail responded in a compensatory manner to its loss and readapted once gravity was restored.

  4. Trematodes in snails near raccoon latrines suggest a final host role for this mammal in California Salt Marshes

    Science.gov (United States)

    Lafferty, K.D.; Dunham, E.J.

    2005-01-01

    Of the 18 trematode species that use the horn snail, Cerithidea californica, as a first intermediate host, 6 have the potential to use raccoons as a final host. The presence of raccoon latrines in Carpinteria Salt Marsh, California, allowed us to investigate associations between raccoons and trematodes in snails. Two trematode species, Probolocoryphe uca and Stictodora hancocki, occurred at higher prevalences in snails near raccoon latrines than in snails away from latrines, suggesting that raccoons may serve as final hosts for these species. Fecal remains indicated that raccoons fed on shore crabs, the second intermediate host for P. uca, and fish, the second intermediate host for S. hancocki. The increase in raccoon populations in the suburban areas surrounding west coast salt marshes could increase their importance as final hosts for trematodes in this system. ?? American Society of Parasitologists 2005.

  5. Invasiveness does not predict impact: response of native land snail communities to plant invasions in riparian habitats

    Czech Academy of Sciences Publication Activity Database

    Horáčková, J.; Juřičková, L.; Šizling, A. L.; Jarošík, Vojtěch; Pyšek, Petr

    2014-01-01

    Roč. 9, č. 9 (2014), s. 1-10, e108296 E-ISSN 1932-6203 Institutional support: RVO:67985939 Keywords : plant invasions * land snails * impact Subject RIV: EF - Botanics Impact factor: 3.234, year: 2014

  6. Spectra of chemical trees

    International Nuclear Information System (INIS)

    Balasubramanian, K.

    1982-01-01

    A method is developed for obtaining the spectra of trees of NMR and chemical interests. The characteristic polynomials of branched trees can be obtained in terms of the characteristic polynomials of unbranched trees and branches by pruning the tree at the joints. The unbranched trees can also be broken down further until a tree containing just two vertices is obtained. The effectively reduces the order of the secular determinant of the tree used at the beginning to determinants of orders atmost equal to the number of vertices in the branch containing the largest number of vertices. An illustrative example of a NMR graph is given for which the 22 x 22 secular determinant is reduced to determinants of orders atmost 4 x 4 in just the second step of the algorithm. The tree pruning algorithm can be applied even to trees with no symmetry elements and such a factoring can be achieved. Methods developed here can be elegantly used to find if two trees are cospectral and to construct cospectral trees

  7. Refining discordant gene trees.

    Science.gov (United States)

    Górecki, Pawel; Eulenstein, Oliver

    2014-01-01

    Evolutionary studies are complicated by discordance between gene trees and the species tree in which they evolved. Dealing with discordant trees often relies on comparison costs between gene and species trees, including the well-established Robinson-Foulds, gene duplication, and deep coalescence costs. While these costs have provided credible results for binary rooted gene trees, corresponding cost definitions for non-binary unrooted gene trees, which are frequently occurring in practice, are challenged by biological realism. We propose a natural extension of the well-established costs for comparing unrooted and non-binary gene trees with rooted binary species trees using a binary refinement model. For the duplication cost we describe an efficient algorithm that is based on a linear time reduction and also computes an optimal rooted binary refinement of the given gene tree. Finally, we show that similar reductions lead to solutions for computing the deep coalescence and the Robinson-Foulds costs. Our binary refinement of Robinson-Foulds, gene duplication, and deep coalescence costs for unrooted and non-binary gene trees together with the linear time reductions provided here for computing these costs significantly extends the range of trees that can be incorporated into approaches dealing with discordance.

  8. Studies on Antigenic Communities between the Yamanashi and Chinese Strains of Schistosoma japonicum Eggs and Oncomelania Snails by Immunoelectrophoresis

    OpenAIRE

    Iwanaga, Yuzuru; Tsuji, Moriyasu; Tanaka, Noriyasu

    1988-01-01

    Antigenic communities were studied with sera from rabbits immunized with the Yamanashi and Chinese strains of Schistosoma japonicum eggs, and the antigens of five subspecies of Oncomelania snails, by immunoelectrophoresis. With regard to antigenic communities defined by the Yamanashi strain of S. japonicum eggs and Oncomelania snails, the schistosome egg produced 5 to 6 bands with Oncomelania hupensis nosophora, 3 to 4 bands with O.h.hupensis, 3 bands with O.h.chiui, 2 bands with O.h.quad...

  9. [Short-term effect of black film covering on Oncomelania hupensis snail control in marshland and lake regions].

    Science.gov (United States)

    Zheng, Sheng-bang; Zhou, Yi-biao; Li, Lin-han; Wu, Jin-yi; Yao, Bao-dong; Zhu, Shao-ping; Wei, Cheng-jian; Li, Fu-ping; Hu, Ben-jiao; Ren, Guang-hui; Yi, Ping; Jiang, Qing-wu

    2013-08-01

    To evaluate the short-term effect of the black film covering combined with niclosamide on Oncomelania hupensis snail control in marshland and lake regions. A ditch with snails in Anxiang County was selected as the experimental sites. The ditch was divided into 3 groups: a film group, a niclosamide group, and a niclosamide and film group. The snails were surveyed before the test and 1, 3, 5, 7 days after the experiment. After the film covering, the highest temperature of the surface of soil was 63.7 degrees C on the first day, and the temperature higher than 40 degrees C lasted 4.34 hours. On the second day, the highest temperature was 52.3 degrees C, and the temperature higher than 40 degrees C lasted 4.96 hours. On the fourth day and fifth day, the temperature was lower than 30 degrees C, while the temperature was lower than 34 degrees C on the sixth day. On the seventh day of the experiment, the snail death rates of the film group, the niclosamide group, and the niclosamide and film group on the soil surface were 16.36%, 58.40% and 53.57%, respectively. On the seventh day, the snail death rates of the film group, and the niclosamide and film group under the soil were 20.00% and 40.00%, respectively, while no snails were found under the soil in the niclosamide group 3 days after the experiment. In mesh bags, the snail death rates of the film group, the niclosamide group, and the niclosamide and film group were 84.00%, 95.33% and 95.33%, respectively. The short-term effect of the black film covering on snail control is not obvious, and the black film covering does no promote the molluscicidal effect of niclosamide.

  10. Endogenous growth factor stimulation of hemocyte proliferation induces resistance to Schistosoma mansoni challenge in the snail host.

    Science.gov (United States)

    Pila, Emmanuel A; Gordy, Michelle A; Phillips, Valerie K; Kabore, Alethe L; Rudko, Sydney P; Hanington, Patrick C

    2016-05-10

    Digenean trematodes are a large, complex group of parasitic flatworms that infect an incredible diversity of organisms, including humans. Larval development of most digeneans takes place within a snail (Gastropoda). Compatibility between snails and digeneans is often very specific, such that suitable snail hosts define the geographical ranges of diseases caused by these worms. The immune cells (hemocytes) of a snail are sentinels that act as a crucial barrier to infection by larval digeneans. Hemocytes coordinate a robust and specific immunological response, participating directly in parasite killing by encapsulating and clearing the infection. Hemocyte proliferation and differentiation are influenced by unknown digenean-specific exogenous factors. However, we know nothing about the endogenous control of hemocyte development in any gastropod model. Here, we identify and functionally characterize a progranulin [Biomphalaria glabrata granulin (BgGRN)] from the snail B. glabrata, a natural host for the human blood fluke Schistosoma mansoni Granulins are growth factors that drive proliferation of immune cells in organisms, spanning the animal kingdom. We demonstrate that BgGRN induces proliferation of B. glabrata hemocytes, and specifically drives the production of an adherent hemocyte subset that participates centrally in the anti-digenean defense response. Additionally, we demonstrate that susceptible B. glabrata snails can be made resistant to infection with S. mansoni by first inducing hemocyte proliferation with BgGRN. This marks the functional characterization of an endogenous growth factor of a gastropod mollusc, and provides direct evidence of gain of resistance in a snail-digenean infection model using a defined factor to induce snail resistance to infection.

  11. Epithelial-mesenchymal transition in breast epithelial cells treated with cadmium and the role of Snail.

    Science.gov (United States)

    Wei, Zhengxi; Shan, Zhongguo; Shaikh, Zahir A

    2018-04-01

    Epidemiological and experimental studies have implicated cadmium (Cd) with breast cancer. In breast epithelial MCF10A and MDA-MB-231 cells, Cd has been shown to promote cell growth. The present study examined whether Cd also promotes epithelial-mesenchymal transition (EMT), a hallmark of cancer progression. Human breast epithelial cells consisting of non-cancerous MCF10A, non-metastatic HCC 1937 and HCC 38, and metastatic MDA-MB-231 were treated with 1 or 3 μM Cd for 4 weeks. The MCF10A epithelial cells switched to a more mesenchymal-like morphology, which was accompanied by a decrease in the epithelial marker E-cadherin and an increase in the mesenchymal markers N-cadherin and vimentin. In both non-metastatic HCC 1937 and HCC 38 cells, treatment with Cd decreased the epithelial marker claudin-1. In addition, E-cadherin also decreased in the HCC 1937 cells. Even the mesenchymal-like MDA-MB-231 cells exhibited an increase in the mesenchymal marker vimentin. These changes indicated that prolonged treatment with Cd resulted in EMT in both normal and cancer-derived breast epithelial cells. Furthermore, both the MCF10A and MDA-MB-231 cells labeled with Zcad, a dual sensor for tracking EMT, demonstrated a decrease in the epithelial marker E-cadherin and an increase in the mesenchymal marker ZEB-1. Treatment of cells with Cd significantly increased the level of Snail, a transcription factor involved in the regulation of EMT. However, the Cd-induced Snail expression was completely abolished by actinomycin D. Luciferase reporter assay indicated that the expression of Snail was regulated by Cd at the promotor level. Snail was essential for Cd-induced promotion of EMT in the MDA-MB-231 cells, as knockdown of Snail expression blocked Cd-induced cell migration. Together, these results indicate that Cd promotes EMT in breast epithelial cells and does so by modulating the transcription of Snail. Copyright © 2018 Elsevier Inc. All rights reserved.

  12. Snails and their trails: the multiple functions of trail-following in gastropods.

    Science.gov (United States)

    Ng, Terence P T; Saltin, Sara H; Davies, Mark S; Johannesson, Kerstin; Stafford, Richard; Williams, Gray A

    2013-08-01

    Snails are highly unusual among multicellular animals in that they move on a layer of costly mucus, leaving behind a trail that can be followed and utilized for various purposes by themselves or by other animals. Here we review more than 40 years of experimental and theoretical research to try to understand the ecological and evolutionary rationales for trail-following in gastropods. Data from over 30 genera are currently available, representing a broad taxonomic range living in both aquatic and terrestrial environments. The emerging picture is that the production of mucus trails, which initially was an adaptation to facilitate locomotion and/or habitat extension, has evolved to facilitate a multitude of additional functions. Trail-following supports homing behaviours, and provides simple mechanisms for self-organisation in groups of snails, promoting aggregation and thus relieving desiccation and predation pressures. In gastropods that copulate, trail-following is an important component in mate-searching, either as an alternative, or in addition to the release of water- or air-borne pheromones. In some species, this includes a capacity of males not only to identify trails of conspecifics but also to discriminate between trails laid by females and males. Notably, trail discrimination seems important as a pre-zygotic barrier to mating in some snail species. As production of a mucus trail is the most costly component of snail locomotion, it is also tempting to speculate that evolution has given rise to various ways to compensate for energy losses. Some snails, for example, increase energy intake by eating particles attached to the mucus of trails that they follow, whereas others save energy through reducing the production of their own mucus by moving over previously laid mucus trails. Trail-following to locate a prey item or a mate is also a way to save energy. While the rationale for trail-following in many cases appears clear, the basic mechanisms of trail

  13. Studies on the Edible Terrestrial Snails Helix aspersa Muller Food Conversion Ratio in a Confined Microclimate System

    Directory of Open Access Journals (Sweden)

    Adrian Toader-Williams

    2010-05-01

    Full Text Available Terrestrial edible snail breeding is an agricultural activity that finds itself at pioneering stage in Romania. One of the species used in snail farming is Helix aspersa Muller. In order to accelerate their growth, farmers feed the snails with pumpkins as well as concentrated forage consisting of mix of flours to which calcium carbonate is added in order to supplement snails need for shell’s development. In a controlled microclimate environment we measured the average growth of six weeks old Helix aspersa Muller snails placed in four different plastic enclosures. The consumption of different type of foods within 24 hours period was measured. The wheat (60%, corn flour (20% and calcium carbonate (20% mix had a superior food conversion ratio (FCR of 4.80, whereas the second FCR registered 6.04 in the case of 53% pumpkin and 47% flour mix served in the same time followed by the pure fresh vegetable mix accounting for a FCR of 8.00 and by 19.02 when only the pumpkin has been administrated as meal. During the experiments the snails did not have access to soil, being known that soil is an integral part of their diet.

  14. Implications of Changing Temperatures on the Growth, Fecundity and Survival of Intermediate Host Snails of Schistosomiasis: A Systematic Review

    Directory of Open Access Journals (Sweden)

    Chester Kalinda

    2017-01-01

    Full Text Available Climate change has been predicted to increase the global mean temperature and to alter the ecological interactions among organisms. These changes may play critical roles in influencing the life history traits of the intermediate hosts (IHs. This review focused on studies and disease models that evaluate the potential effect of temperature rise on the ecology of IH snails and the development of parasites within them. The main focus was on IH snails of schistosome parasites that cause schistosomiasis in humans. A literature search was conducted on Google Scholar, EBSCOhost and PubMed databases using predefined medical subject heading terms, Boolean operators and truncation symbols in combinations with direct key words. The final synthesis included nineteen published articles. The studies reviewed indicated that temperature rise may alter the distribution, optimal conditions for breeding, growth and survival of IH snails which may eventually increase the spread and/or transmission of schistosomiasis. The literature also confirmed that the life history traits of IH snails and their interaction with the schistosome parasites are affected by temperature and hence a change in climate may have profound outcomes on the population size of snails, parasite density and disease epidemiology. We concluded that understanding the impact of temperature on the growth, fecundity and survival of IH snails may broaden the knowledge on the possible effects of climate change and hence inform schistosomiasis control programmes.

  15. Gut bacterial communities in the giant land snail Achatina fulica and their modification by sugarcane-based diet.

    Science.gov (United States)

    Cardoso, Alexander M; Cavalcante, Janaína J V; Vieira, Ricardo P; Lima, Joyce L; Grieco, Maria Angela B; Clementino, Maysa M; Vasconcelos, Ana Tereza R; Garcia, Eloi S; de Souza, Wanderley; Albano, Rodolpho M; Martins, Orlando B

    2012-01-01

    The invasive land snail Achatina fulica is one of the most damaging agricultural pests worldwide representing a potentially serious threat to natural ecosystems and human health. This species is known to carry parasites and harbors a dense and metabolically active microbial community; however, little is known about its diversity and composition. Here, we assessed for the first time the complexity of bacterial communities occurring in the digestive tracts of field-collected snails (FC) by using culture-independent molecular analysis. Crop and intestinal bacteria in FC were then compared to those from groups of snails that were reared in the laboratory (RL) on a sugarcane-based diet. Most of the sequences recovered were novel and related to those reported for herbivorous gut. Changes in the relative abundance of Bacteroidetes and Firmicutes were observed when the snails were fed a high-sugar diet, suggesting that the snail gut microbiota can influence the energy balance equation. Furthermore, this study represents a first step in gaining a better understanding of land snail gut microbiota and shows that this is a complex holobiont system containing diverse, abundant and active microbial communities.

  16. Gut bacterial communities in the giant land snail Achatina fulica and their modification by sugarcane-based diet.

    Directory of Open Access Journals (Sweden)

    Alexander M Cardoso

    Full Text Available The invasive land snail Achatina fulica is one of the most damaging agricultural pests worldwide representing a potentially serious threat to natural ecosystems and human health. This species is known to carry parasites and harbors a dense and metabolically active microbial community; however, little is known about its diversity and composition. Here, we assessed for the first time the complexity of bacterial communities occurring in the digestive tracts of field-collected snails (FC by using culture-independent molecular analysis. Crop and intestinal bacteria in FC were then compared to those from groups of snails that were reared in the laboratory (RL on a sugarcane-based diet. Most of the sequences recovered were novel and related to those reported for herbivorous gut. Changes in the relative abundance of Bacteroidetes and Firmicutes were observed when the snails were fed a high-sugar diet, suggesting that the snail gut microbiota can influence the energy balance equation. Furthermore, this study represents a first step in gaining a better understanding of land snail gut microbiota and shows that this is a complex holobiont system containing diverse, abundant and active microbial communities.

  17. Contribution of Golden Apple Snail Flour to Enhance Omega- 3 and Omega-6 Fatty Acids Contents in Weaning Food

    Science.gov (United States)

    Marsyha, D. D.; Wijayanti, H. S.; Nuryanto; Anjani, G.

    2018-02-01

    The case of undernourished children in Grobogan District (15.3%) is caused by children nutrients intake less than the Recommendation Dietary Allowance (RDA). To enhance children nutrients intake, be required formulation of weaning food using high-nutrient local food such as golden apple snail (Pomacea canaliculata). Golden apple snail flour contains high contents of zinc, iron, omega-3 and omega-6 fatty acids. This study aims to analyze the effect of golden apple snail flour substitution on nutrients content and organoleptic properties of weaning food (baby porridge). This is an experimental research by substitution of golden apple snail flour in the making of weaning food with four treatments of substitution (0%, 5%, 10%, 15%). Substitution of golden apple snails flour could affect the nutrient content levels of fat, zinc, iron (p=0.0001), carbohydrate (p=0.011), water (p=0.003), ash (p=0.001), omega-3 and omega-6 fatty acids. Whereas, it could not affect the content of energy (p=0.678), protein (p=0.129) and fiber (p=0.482). Furthermore, the substitution could affect the organoleptic properties include color, texture and taste (p=0.0001) while not for the aroma (p=0.798). Based on nutrient content analysis, substitution of golden apple snail flour could enhance the zinc, iron, omega-3 and omega-6 fatty acids contents of weaning food.

  18. First report of Angiostrongylus cantonensis in the giant African land snail Achatina fulica in French Polynesia detected using the SSU rRNA gene.

    Science.gov (United States)

    Fontanilla I, K C; Wade, C M

    2012-12-01

    The 5' end of the small subunit ribosomal RNA gene was used to determine whether 3rd larval stage Angiostrongylus cantonensis are present in populations of the giant African land snail Achatina fulica from French Polynesia. Two populations, one from Moaroa Valley, Tahiti (n=5) and the other from Haapiti Valley, Moorea (n=10), were examined. All snails from Tahiti were infected with nematodes, with parasite load ranging from 12 to 28. A total of 92 nematodes were found, of which 91 were positively identified as A. cantonensis. No nematodes were found in the snails from Moorea. We report for the first time the presence of A. cantonensis in A. fulica snails from French Polynesia, indicating a viable route of human infection of A. cantonensis in the region through the handling of A. fulica or consumption of the snail or contaminated food crops associated with the snail.

  19. Detection of early and single infections of Schistosoma japonicum in the intermediate host snail, Oncomelania hupensis, by PCR and loop-mediated isothermal amplification (LAMP) assay.

    Science.gov (United States)

    Kumagai, Takashi; Furushima-Shimogawara, Rieko; Ohmae, Hiroshi; Wang, Tian-Ping; Lu, Shaohong; Chen, Rui; Wen, Liyong; Ohta, Nobuo

    2010-09-01

    Polymerase chain reaction (PCR) with the specific primer set amplifying 28S ribosomal DNA (rDNA) of Schistosoma japonicum was able to detect genomic DNA of S. japonicum, but not S. mansoni, at 100 fg. This procedure enabled us to detect the DNA from a single miracidium and a snail infected with one miracidium at just 1 day after infection. We compared these results with those from loop-mediated isothermal amplification (LAMP) targeting 28S rDNA and found similar results. The LAMP could amplify the specific DNA from a group of 100 normal snails mixed with one infected snail A PCR screening of infected snails from endemic regions in Anhui Province revealed schistosomal DNA even in snails found negative by microscopy. PCR and LAMP show promise for monitoring the early infection rate in snails, and they may be useful for predicting the risk of infection in the endemic places.

  20. Distribution of intermediate host snails of schistosomiasis and fascioliasis in relation to environmental factors during the dry season in the Tchologo region, Côte d'Ivoire

    Science.gov (United States)

    Krauth, Stefanie J.; Wandel, Nathalie; Traoré, Seïdinan I.; Vounatsou, Penelope; Hattendorf, Jan; Achi, Louise Y.; McNeill, Kristopher; N'Goran, Eliézer K.; Utzinger, Jürg

    2017-10-01

    Snail-borne trematodiases, such as fascioliasis and schistosomiasis, belong to the neglected tropical diseases; yet, millions of people and livestock are affected. The spatial and temporal distribution of intermediate host snails plays an important role in the epidemiology and control of trematodiases. Snail distribution is influenced by numerous environmental and anthropomorphic factors. The aim of this study was to assess the distribution and constitution of the snail fauna during the dry season in constructed and natural water bodies in the Tchologo region, northern Côte d'Ivoire, and to relate these findings to environmental factors and human infections. Snails were collected using standard procedures and environmental parameters were assessed from a total of 50 water bodies in and around 30 randomly selected villages. A canonical correspondence analysis was performed to establish the relationship between snail occurrence and environmental factors. Furthermore, a total of 743 people from the same 30 villages and nearby settlements were invited for stool and urine examination for the diagnosis of Fasciola spp., Schistosoma haematobium and Schistosoma mansoni. Snails of medical importance of the genera Biomphalaria, Bulinus, Lymnaea and Physa were found. Differences in snail occurrence from sites sampled in December 2014 and snails sampled in February 2015, as well as between the northern and southern part of the study area, were revealed. Various environmental factors, such as temperature and human activities, were related to the occurrence of intermediate host snail species in the region. Only 2.3% of human participants tested positive for schistosomiasis, while no Fasciola eggs were found in stool samples. We conclude that intermediate host snails of Fasciola and Schistosoma co-occur in water bodies in the Tchologo region and that the distribution of these snails correlates not only with environmental factors, but also with the presence of humans and animals

  1. Evidence for non-assimilation of Chlorella by the African freshwater snail Bulinus (Physopsis) globosus

    International Nuclear Information System (INIS)

    Van Aardt, W.J.; Wolmarans, C.T.

    1981-01-01

    Little is known about the assimilation of its natural food by South African basommatophorans. It is generally assumed that the snails are microphagus herbivores which ingest mainly periphytic algae, detritus and the bacterial component of their food. Preliminary observations indicated that Chlorella spp. were by far the dominant algal species on stems and leaves of Juncus on which the snails were usually found in our study. This report describes experiments to see whether Chlorella is ingested and assimilated by Bulinus (Physopsis) globosus. A closely related species, B. (B.) tropicus, which occupies the same niche was also included in the study for purposes of comparison. It was found that, although Chlorella was continuously ingested by both species, it was assimilated by neither. Possible reasons for this are given

  2. Ocean acidification increases the vulnerability of native oysters to predation by invasive snails.

    Science.gov (United States)

    Sanford, Eric; Gaylord, Brian; Hettinger, Annaliese; Lenz, Elizabeth A; Meyer, Kirstin; Hill, Tessa M

    2014-03-07

    There is growing concern that global environmental change might exacerbate the ecological impacts of invasive species by increasing their per capita effects on native species. However, the mechanisms underlying such shifts in interaction strength are poorly understood. Here, we test whether ocean acidification, driven by elevated seawater pCO₂, increases the susceptibility of native Olympia oysters to predation by invasive snails. Oysters raised under elevated pCO₂ experienced a 20% increase in drilling predation. When presented alongside control oysters in a choice experiment, 48% more high-CO₂ oysters were consumed. The invasive snails were tolerant of elevated CO₂ with no change in feeding behaviour. Oysters raised under acidified conditions did not have thinner shells, but were 29-40% smaller than control oysters, and these smaller individuals were consumed at disproportionately greater rates. Reduction in prey size is a common response to environmental stress that may drive increasing per capita effects of stress-tolerant invasive predators.

  3. Chemical speciation and bioavailability of transuranics for a freshwater snail (Lymnaea stagnalis L.)

    International Nuclear Information System (INIS)

    Thiels, G.M.; Murray, C.N.; Rade, J.

    1981-01-01

    It is now becoming clear that the determination of the physico-chemical forms of transuranic elements is an important step in assessing their behaviour at very low environmental levels. Data from both simulated environmental systems as well as in-situ investigations have shown the necessity of understanding the source term of contamination, which probably plays a major role in the long-term distribution of these elements. In the present paper an experimental procedure is outlined, which allows a more extensive investigation into some aspects of the biogeochemical behaviour of two transuranics: 237 Pu and 241 Am. Two chemical methods were applied to a study of the freshwater snail Lymnaea stagnalis L.. Data were obtained on the uptake and retention patterns of different oxidation states of 237 Pu and 241 Am at the organ and cellular levels of the pond snail. An attempt was made to relate the environmental chemistry of both radionuclides to the fixation in L. stagnalis. (author)

  4. Prevalence of Fasciola in cattle and of its intermediate host Lymnaea snails in central Vietnam.

    Science.gov (United States)

    Nguyen, Sam Thi; Nguyen, Duc Tan; Van Nguyen, Thoai; Huynh, Vu Vy; Le, Duc Quyet; Fukuda, Yasuhiro; Nakai, Yutaka

    2012-12-01

    The aims of this study were to investigate the prevalence of natural Fasciola infections in both the definitive hosts (cattle) and the intermediate hosts (Lymnaea snails) in central Vietnam. A total of 1,075 fecal samples, randomly collected from cattle in Binh Dinh, Khanh Hoa, and Phu Yen provinces, were examined for Fasciola eggs by a sedimentation method. The overall prevalence of Fasciola was 45.3 %. A subset of the animals (235) was also screened for antibodies against Fasciola by an enzyme-linked immunosorbent assay. Overall, 46.3 % of these animals were shedding Fasciola eggs while 87.2 % were Fasciola seropositive. A lower prevalence of Fasciola was observed in calves ≤ 2 years of age (37.6 %) compared to that in cattle >2 years of age (53.7 %) (p Fasciola. This appears to be the first epidemiological survey of the prevalence of Fasciola in cattle and snails in these three provinces in central Vietnam.

  5. Enrichment and identification of cellulolytic bacteria from the gastrointestinal tract of Giant African snail, Achatina fulica.

    Science.gov (United States)

    Pawar, Kiran D; Dar, Mudasir A; Rajput, Bharati P; Kulkarni, Girish J

    2015-02-01

    The cellulolytic bacterial community structure in gastrointestinal (GI) tract of Achatina fulica was studied using culture-independent and -dependent methods by enrichment in carboxymethyl cellulose (CMC). Culture-dependent method indicated that GI tract of snail was dominated by Enterobacteriaceae members. When tested for cellulase activities, all isolates obtained by culture-dependent method showed both or either of CMCase or avicelase activity. Isolate identified as Citrobacter freundii showed highest CMCase and medium avicelase activity. Sequencing of clones from the 16S rRNA gene clone library identified ten operational taxonomic units (OTUs), which were affiliated to Enterobacteriaceae of phylum Gammaproteobacteria. Of these ten OTUs, eight OTUs closely matched with Enterobacter and Klebsiella genera. The most abundant OTU allied to Klebsiella oxytoca accounted for 70 % of the total sequences. The members of Klebsiella and Enterobacter were observed by both methods indicating their dominance among the cellulolytic bacterial community in the GI tract of the snail.

  6. Record of gut associated nemathelminth in the giant African snail Achatina fulica (Bowdich) from Bangalore, India.

    Science.gov (United States)

    Jayashankar, M; Murthy, G S S

    2015-06-01

    Prevalence of nematodes in Achatina fulica (Bowdich) sample collected from two different sites within Bangalore University Jnana Bharathi Campus viz., Dhanavanthari vana and Botany Department garden was 84 and 100 % respectively. However, the identity of the nemathelminth could not be established to the species level as it did not respond to the clearing agent and its genital organs were not located which is key character for taxonomic identification. Also, no Cercariae were recorded in the samples, perhaps the snail sample was non endemic for parasitic population. Helminthological prospection with regard to the giant African snail from the region has not been performed till date. The present work is a preliminary study in that direction intended to determine the nemathelminth fauna associated with A. fulica populations in Bangalore region laying emphasis on further studies to be undertaken in this regard.

  7. Complete mitochondrial genome of the giant ramshorn snail Marisa cornuarietis (Gastropoda: Ampullariidae).

    Science.gov (United States)

    Wang, Mingling; Qiu, Jian-Wen

    2016-05-01

    We report the complete mitochondrial genome (mitogenome) of the giant ramshorn snail Marisa cornuarietis, a biocontrol agent of freshwater weeds and snail vectors of schistosomes. The mitogenome is 15,923 bp in length, encoding 13 protein-coding genes, 22 transfer RNAs and 2 ribosomal RNAs. The mitogenome is A+T biased (70.0%), with 28.9% A, 41.1% T, 16.7% G, and 13.3% C. A comparison with Pomacea canaliculata, the other member in the same family (Ampullariidae) with a sequenced mitogenome, shows that the two species have an identical gene order, but their intergenic regions vary substantially in sequence length. The mitogenome data can be used to understand the population genetics of M. cornuarietis, and resolve the phylogenetic relationship of various genera in Ampullariidae.

  8. Factors controlling carbon isotopic composition of land snail shells estimated from lab culturing experiment

    Science.gov (United States)

    Zhang, Naizhong; Yamada, Keita; Yoshida, Naohiro

    2014-05-01

    Carbon isotopic composition (δ13C) of land snail shell carbonate is widely applied in reconstructing the C3/C4 vegetation distribution of paleo-environment, which is considered to reflect variations of some environmental parameters [1][2][3]. Land snail shell carbon has three potential sources: diet, atmospheric CO2 and ingested carbonate (limestone) [4]. However, their relative contributions to shell carbonate have not been understood well yet [4][5][6][7][8]. More researches are necessary before we could apply this tool in paleo-environment reconstruction, especially inter-lab culturing experiment. A kind of land snail species, Acusta despecta sieboldiana, was collected at Yokohama, Japan and cultured under suitable environment to lay eggs. The second generations were growing up from eggs to adults around 6-12 months at the temperature of 20°, 25° and 30°, respectively. All of the snails at 25° and 30° and most of those at 20° were fed by cabbage (C3 plant) during their life span while others were fed by corn (C4 plant). To investigate the effect of ingested carbonate, some of them were fed by Ca3(PO4)2 powder while others were fed by CaCO3 powder. δ13C of shells were analyzed by an Isotope Ratio Mass Spectrometry (Thermo Finnigan MAT 253); δ13C of food and snail tissue were measured by a Cavity Ring-Down Spectroscopy (Picarro G1121-i). At the same time, δ13C of eggshell and new born snails were analyzed by a Continuous Flow Isotope Ratio Mass Spectrometry (GasBench II). We confirmed that diet, atmospheric CO2 and ingested limestone could be important sources controlling shell δ13C values. And the temperature could affect shell carbonate δ13C values, too. A simple but credible frame was raised to discuss the mechanism of how each possible source and environmental parameter could affect shell carbonate δ13C values based on previous works [4][6][8] and this study. According to this frame and some reasonable assumptions, we have estimated the

  9. Marine snail venoms: use and trends in receptor and channel neuropharmacology.

    Science.gov (United States)

    Favreau, Philippe; Stöcklin, Reto

    2009-10-01

    Venoms are rich mixtures of mainly peptides and proteins evolved by nature to catch and digest preys or for protection against predators. They represent extensive sources of potent and selective bioactive compounds that can lead to original active ingredients, for use as drugs, as pharmacological tools in research and for the biotechnology industry. Among the most fascinating venomous animals, marine snails offer a unique set of pharmacologically active components, targeting a wide diversity of receptors and ion channels. Recent advances still continue to demonstrate their huge neuropharmacological potential. In the quest for interesting pharmacological profiles, researchers face a vast number of venom components to investigate within time and technological constraints. A brief perspective on marine snail venom's complexity and features is given followed by the different discovery strategies and pharmacological approaches, exemplified with some recent developments. These advances will hopefully help further uncovering new pharmacologically important venom molecules.

  10. A novel 13 residue acyclic peptide from the marine snail, Conus monile, targets potassium channels

    OpenAIRE

    Sudarslal, Sadasivannair; Singaravadivelan, Govindaswamy; Ramasamy, Palanisamy; Ananda, Kuppanna; Sarma, Siddhartha P; Sikdar, Sujit K; Krishnan, KS; Balaram, Padmanabhan

    2004-01-01

    A novel 13-residue peptide Mo1659 has been isolated from the venom of a vermivorous cone snail, Conus monile. HPLC fractions of the venom extract yielded an intense UV absorbing fraction with a mass of 1659 Da. De novo sequencing using both matrix assisted laser desorption and ionization and electrospray MS/MS methods together with analysis of proteolytic fragments successfully yielded the amino acid sequence, HGGSWYRFPWGY-NH2. This was further confirmed by comparison with the chemically synt...

  11. Scientometrics of zoonoses transmitted by the giant African snail Achatina fulica Bowdich, 1822

    Directory of Open Access Journals (Sweden)

    Gilberto Cezar Pavanelli

    Full Text Available ABSTRACT The dissemination of the giant African snail Achatina fulica in several countries has triggered a great number of studies on the mollusk, including those on zoonoses related to health in humans. The current research is a scientific survey on articles published in four databases, namely, PubMed, Bireme, Scielo and Lilacs. Results indicate that Brazil has a prominent position in international scientific production on this subject, with focus on Angiostrongylus cantonensis occurrences.

  12. Scientometrics of zoonoses transmitted by the giant African snail Achatina fulica Bowdich, 1822.

    Science.gov (United States)

    Pavanelli, Gilberto Cezar; Yamaguchi, Mirian Ueda; Calaça, Elaine Alves; Oda, Fabrício Hiroiuki

    2017-04-13

    The dissemination of the giant African snail Achatina fulica in several countries has triggered a great number of studies on the mollusk, including those on zoonoses related to health in humans. The current research is a scientific survey on articles published in four databases, namely, PubMed, Bireme, Scielo and Lilacs. Results indicate that Brazil has a prominent position in international scientific production on this subject, with focus on Angiostrongylus cantonensis occurrences.

  13. EMT transcription factors snail and slug directly contribute to cisplatin resistance in ovarian cancer

    International Nuclear Information System (INIS)

    Haslehurst, Alexandria M; Weberpals, Johanne; Davey, Scott; Squire, Jeremy; Park, Paul C; Feilotter, Harriet; Koti, Madhuri; Dharsee, Moyez; Nuin, Paulo; Evans, Ken; Geraci, Joseph; Childs, Timothy; Chen, Jian; Li, Jieran

    2012-01-01

    The epithelial to mesenchymal transition (EMT) is a molecular process through which an epithelial cell undergoes transdifferentiation into a mesenchymal phenotype. The role of EMT in embryogenesis is well-characterized and increasing evidence suggests that elements of the transition may be important in other processes, including metastasis and drug resistance in various different cancers. Agilent 4 × 44 K whole human genome arrays and selected reaction monitoring mass spectrometry were used to investigate mRNA and protein expression in A2780 cisplatin sensitive and resistant cell lines. Invasion and migration were assessed using Boyden chamber assays. Gene knockdown of snail and slug was done using targeted siRNA. Clinical relevance of the EMT pathway was assessed in a cohort of primary ovarian tumours using data from Affymetrix GeneChip Human Genome U133 plus 2.0 arrays. Morphological and phenotypic hallmarks of EMT were identified in the chemoresistant cells. Subsequent gene expression profiling revealed upregulation of EMT-related transcription factors including snail, slug, twist2 and zeb2. Proteomic analysis demonstrated up regulation of Snail and Slug as well as the mesenchymal marker Vimentin, and down regulation of E-cadherin, an epithelial marker. By reducing expression of snail and slug, the mesenchymal phenotype was largely reversed and cells were resensitized to cisplatin. Finally, gene expression data from primary tumours mirrored the finding that an EMT-like pathway is activated in resistant tumours relative to sensitive tumours, suggesting that the involvement of this transition may not be limited to in vitro drug effects. This work strongly suggests that genes associated with EMT may play a significant role in cisplatin resistance in ovarian cancer, therefore potentially leading to the development of predictive biomarkers of drug response or novel therapeutic strategies for overcoming drug resistance

  14. Scientometrics of zoonoses transmitted by the giant African snail Achatina fulica Bowdich, 1822

    Science.gov (United States)

    Pavanelli, Gilberto Cezar; Yamaguchi, Mirian Ueda; Calaça, Elaine Alves; Oda, Fabrício Hiroiuki

    2017-01-01

    ABSTRACT The dissemination of the giant African snail Achatina fulica in several countries has triggered a great number of studies on the mollusk, including those on zoonoses related to health in humans. The current research is a scientific survey on articles published in four databases, namely, PubMed, Bireme, Scielo and Lilacs. Results indicate that Brazil has a prominent position in international scientific production on this subject, with focus on Angiostrongylus cantonensis occurrences. PMID:28423090

  15. Biology and Control of Snail Intermediate Host of Schistosoma japonicum in The People's Republic of China

    DEFF Research Database (Denmark)

    Li, Z.J.; Ge, J; Dai, J.R.

    2016-01-01

    Schistosomiasis caused by Schistosoma japonicum is a severe parasitic disease in The People's Republic of China and imposed considerable burden on human and domestic animal health and socioeconomic development. The significant achievement in schistosomiasis control has been made in last 60years. ....... Oncomelania hupensis as the only intermediate host of S. japonicum plays a key role in disease transmission. The habitat complexity of the snails challenges to effective control. In this review we share the experiences in control and research of O. hupensis....

  16. Bisphenol A induces superfeminization in the Ramshorn snail Marisa cornuarietis (Gastropoda: Prosobranchia) at environmentally relevant concentrations

    OpenAIRE

    Oehlmann, Jörg; Schulte-Oehlmann, Ulrike; Bachmann, Jean; Oetken, Matthias; Lutz, Ilka; Kloas, Werner; Ternes, Thomas A.

    2007-01-01

    Previous investigations have shown that bisphenol A (BPA) induces a superfeminization syndrome in the freshwater snail Marisa cornuarietis at concentrations as low as 1 μg/L. Superfemales are characterized by the formation of additional female organs, enlarged accessory sex glands, gross malformations of the pallial oviduct, and a stimulation of egg and clutch production, resulting in increased female mortality. However, these studies were challenged on the basis of incomplete experiment...

  17. EMT transcription factors snail and slug directly contribute to cisplatin resistance in ovarian cancer

    Directory of Open Access Journals (Sweden)

    Haslehurst Alexandria M

    2012-03-01

    Full Text Available Abstract Background The epithelial to mesenchymal transition (EMT is a molecular process through which an epithelial cell undergoes transdifferentiation into a mesenchymal phenotype. The role of EMT in embryogenesis is well-characterized and increasing evidence suggests that elements of the transition may be important in other processes, including metastasis and drug resistance in various different cancers. Methods Agilent 4 × 44 K whole human genome arrays and selected reaction monitoring mass spectrometry were used to investigate mRNA and protein expression in A2780 cisplatin sensitive and resistant cell lines. Invasion and migration were assessed using Boyden chamber assays. Gene knockdown of snail and slug was done using targeted siRNA. Clinical relevance of the EMT pathway was assessed in a cohort of primary ovarian tumours using data from Affymetrix GeneChip Human Genome U133 plus 2.0 arrays. Results Morphological and phenotypic hallmarks of EMT were identified in the chemoresistant cells. Subsequent gene expression profiling revealed upregulation of EMT-related transcription factors including snail, slug, twist2 and zeb2. Proteomic analysis demonstrated up regulation of Snail and Slug as well as the mesenchymal marker Vimentin, and down regulation of E-cadherin, an epithelial marker. By reducing expression of snail and slug, the mesenchymal phenotype was largely reversed and cells were resensitized to cisplatin. Finally, gene expression data from primary tumours mirrored the finding that an EMT-like pathway is activated in resistant tumours relative to sensitive tumours, suggesting that the involvement of this transition may not be limited to in vitro drug effects. Conclusions This work strongly suggests that genes associated with EMT may play a significant role in cisplatin resistance in ovarian cancer, therefore potentially leading to the development of predictive biomarkers of drug response or novel therapeutic strategies for

  18. Effects of snails, submerged plants and their coexistence on eutrophication in aquatic ecosystems

    OpenAIRE

    Mo Shuqing; Zhang Xiufeng; Tang Yali; Liu Zhengwen; Kettridge Nicholas

    2017-01-01

    Eutrophication resulting from nutrient loading to freshwater habitats is a severe problem, leading to degradation of ecosystems, including deterioration of water quality, water clarity and loss of biodiversity. Measures enacted to restore degraded freshwater ecosystems often involve the reintroduction of submerged plants and aquatic animals with beneficial ecological functions. In a mesocosm experiment, three treatments (planting with Vallisneria natans, introduction of the snail Bellamya aer...

  19. Development of Helisoma trivolvis pond snails as biological samplers for biomonitoring of current-use pesticides.

    Science.gov (United States)

    Morrison, Shane A; Belden, Jason B

    2016-09-01

    Nontarget aquatic organisms residing in wetlands are commonly exposed to current-use pesticides through spray drift and runoff. However, it is frequently challenging to measure exposure because of rapid dissipation of pesticides from water and reduced bioavailability. The authors' hypothesis is that freshwater snails can serve as bioindicators of pesticide exposure based on their capacity to passively accumulate tissue residues. Helisoma trivolvis snails were evaluated as biomonitors of pesticide exposure using a fungicide formulation that contains pyraclostrobin and metconazole and is frequently applied to crops surrounding depressional wetlands. Exposure-response studies indicate that H. trivolvis are tolerant of pyraclostrobin and metconazole at concentrations >10 times those lethal to many aquatic species, with a median lethal concentration based on pyraclostrobin of 441 μg/L (95% confidence interval of 359-555 μg/L). Bioconcentration factors ranged from 137 mL/g to 211 mL/g and from 39 mL/g to 59 mL/g for pyraclostrobin and metconazole, respectively. Elimination studies suggested one-compartmental elimination and snail tissue half-lives (t50 ) of approximately 15 h and 5 h for pyraclostrobin and metconazole, respectively. Modeling derived toxicokinetic parameters in the context of an environmentally relevant pulsed exposure suggests that residues can be measured in snails long after water concentrations fall below detection limits. With high fungicide tolerance, rapid accumulation, and slow elimination, H. trivolvis may be viable for biomonitoring of pyraclostrobin and should be investigated for other pesticides. Environ Toxicol Chem 2016;35:2320-2329. © 2016 SETAC. © 2016 SETAC.

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

    Science.gov (United States)

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

    2013-01-01

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

  1. [Effect of water conservancy schistosomiasis control projects combined with molluscicide to control Oncomelania hupensis snails in rivers connecting with Yangtze River in Pukou District, Nanjing City].

    Science.gov (United States)

    Qiang, Zhou; Li-Xin, Wan; De-Rong, Hang; Qi-Hui, You; Jun, You; Yu-Lin, Zhang; Zhao-Feng, Zhu; Yi-Xin, Huang

    2017-12-07

    To evaluate the effect of the water conservancy schistosomiasis control projects combined with molluscicide to control Oncomelania hupensis snails in the rivers connecting with the Yangtze River. The water conservancy schistosomiasis control projects of Zhujiashan River, Qili River and Gaowang River were chosen as the study objects in Pukou District, Nanjing City. The data review method and field investigation were used to evaluate the effect of the water conservancy schistosomiasis control projects combined with molluscicide to control O. hupensis snails. After the projects of the water level control and concrete slope protection and mollusciciding were implemented, the snails in the project river sections were completely eliminated. The snail diffusion did not happen in the inland irrigation area too. In the outside of the river beach, though the snails still existed, the snail densities plunged below 1.0 snail per 1.0 m 2 . The comprehensive measures of the combination of water level control, concrete slope protection and mollusciciding can effectively control and eliminate the snails, and prevent the snails from spreading.

  2. [Oncomelania hupensis snail distribution in working areas of Yangtze River hydrologic agencies located in middle and lower reaches of Yangtze River in 2016].

    Science.gov (United States)

    Min, Xu; Suo-Xin, Huang; Zheng-Yuan, Zhao; Ben-Jiao, Hu; Jun, Fu; Si-Min, Dai; Li-Hong, Wen

    2016-10-13

    To understand the Oncomelania hupensis snail distribution in the working areas of Yangtze River hydrologic agencies located in the middle and lower reaches of the Yangtze River in 2016, so as to provide the evidence for assessing the risk of schistosome infection of hydrological workers and establishing the control strategies. The suspicious environments with O. hupensis snails in the above working areas were selected as study areas, and the snail situation was surveyed by the system sampling method combined with the environmental sampling method. The survey data were collected and analyzed statistically. Totally 19 working areas from 17 hydrological agencies were selected as the investigation sites, among which, 10 working areas from 9 agencies were found with O. hupensis snail distribution. The constituent ratio of the areas with snails reached to 38.81% of the investigation areas, the occurrence rate of frames with snails was 3.08%, and the average density of living snails was 0.07 /0.1 m 2 . By comparison, the average density of living snails and occurrence rate of frames with snails in hydrological agencies under the jurisdiction of the Middle Reaches Administrative Bureau were the most serious among three administrative bureaus of the Yangtze River Water Resources Commission. There are various degrees of O. hupensis breeding in the working areas of hydrological agencies located in the middle and lower reaches of the Yangtze River, and the hydrological workers are facing with the risk of schistosome infection.

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

    Science.gov (United States)

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

    2012-01-01

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

  4. Possible control of introduced giant African land snails (Achatina spp. by the reintroduced endemic skink Leiolopisma telfairii, Ile aux Aigrettes, Mauritius

    Directory of Open Access Journals (Sweden)

    Jamie A. COPSEY

    2011-01-01

    Full Text Available The giant African land snail (Achatina fulica is one of the world’s worst invasive species, out‐competing endemic snails, consuming native vegetation and potentially altering nutrient cycles. Attempts to eradicate the snail from islands have only been successful with incipient populations. We present correlative evidence that native island predators may act as an effective control agent for the snail. In 2000 a population of between 37,300 and 45,100 African land snails was estimated on the 26ha nature reserve island of Ile aux Aigrette, Mauritius. Between 2006 and 2007, 260 endemic Telfair’s skink Leiolopisma telfairii were reintroduced to the reserve. Snail population surveys in 2008 and 2009 showed that the introduced snail population had declined to 5,569 (± 3,630 and 6,871 (±5,379, respectively. Previous studies showed that the introduced snails were selective over other invertebrate prey items. We suggest that predation by the endemic skink has been an important causal factor behind the snail population decline.

  5. Trace metallic elements in Helix aspersa terrestrial snails of a semiarid ecosystem; Elementos metalicos traza en caracoles terrestres Helix aspersa de un ecosistema semiarido

    Energy Technology Data Exchange (ETDEWEB)

    Gaso P, M.I.; Segovia, N.; Zarazua, G.; Montes, F. [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico); Morton, O.; Armienta, M.A.; Hernandez, E. [IGF-UNAM, Ciudad Universitaria, 04510 Mexico D.F. (Mexico)

    2001-07-01

    The concentration of some major elements and traces in soil samples and of Helix aspersa eatable terrestrial snails were analysed at the Radioactive Wastes Storage Center (CADER) and in other reference sites. The methodology includes the use of an atomic absorption spectrophotometer, an X-ray fluorescence equipment and an Icp-mass spectroscope. The concentrations of some toxic elements (Ba, Cd, Cr, Ni, Pb and V) in the soft tissue of the snails were greater than the toxic levels reported in the literature for such trace elements. The snails compared with another wild eatable foods present transfer coefficients soil-snail high relatively. (Author)

  6. Concentration and retention of Toxoplasma gondii oocysts by marine snails demonstrate a novel mechanism for transmission of terrestrial zoonotic pathogens in coastal ecosystems

    Science.gov (United States)

    Krusor, Colin; Smith, Woutrina A.; Tinker, M. Tim; Silver, Mary; Conrad, Patricia A.; Shapiro, Karen

    2015-01-01

    The parasite Toxoplasma gondii is an environmentally persistent pathogen that can cause fatal disease in humans, terrestrial warm-blooded animals and aquatic mammals. Although an association between T. gondii exposure and prey specialization on marine snails was identified in threatened California sea otters, the ability of kelp-dwelling snails to transmit terrestrially derived pathogens has not been previously investigated. The objective of this study was to measure concentration and retention of T. gondii by marine snails in laboratory aquaria, and to test for natural T. gondii contamination in field-collected snails. Following exposure to T. gondii-containing seawater, oocysts were detected by microscopy in snail faeces and tissues for 10 and 3 days respectively. Nested polymerase chain reaction was also applied as a method for confirming putative T. gondii oocysts detected in snail faeces and tissues by microscopy. Toxoplasma gondiiwas not detected in field-collected snails. Results suggest that turban snails are competent transport hosts for T. gondii. By concentrating oocysts in faecal pellets, snails may facilitate entry of T. gondii into the nearshore marine food web. This novel mechanism also represents a general pathway by which marine transmission of terrestrially derived microorganisms can be mediated via pathogen concentration and retention by benthic invertebrates.

  7. Adaptation of Lymnaea fuscus and Radix balthica to Fasciola hepatica through the experimental infection of several successive snail generations

    Science.gov (United States)

    2014-01-01

    Background High prevalence of Fasciola hepatica infection (>70%) was noted during several outbreaks before the 2000s in several French farms where Galba truncatula is lacking. Other lymnaeids such as Lymnaea fuscus, L. glabra and/or Radix balthica are living in meadows around these farms but only juvenile snails can sustain complete larval development of F. hepatica while older snails were resistant. The low prevalence of infection (<20%) and limited cercarial production (<50 cercariae per infected snail) noted with these juveniles could not explain the high values noted in these cattle herds. As paramphistomosis due to Calicophoron daubneyi was not still noted in these farms, the existence of another mode of infection was hypothesized. Experimental infection of several successive generations of L. glabra, originating from eggs laid by their parents already infected with this parasite resulted in a progressive increase in prevalence of snail infection and the number of shed cercariae. The aim of this paper was to determine if this mode of snail infection was specific to L. glabra, or it might occur in other lymnaeid species such as L. fuscus and R. balthica. Methods Five successive generations of L. fuscus and R. balthica were subjected to individual bimiracidial infections in the laboratory. Resulting rediae and cercariae in the first four generations were counted after snail dissection at day 50 p.e. (20°C), while the dynamics of cercarial shedding was followed in the F5 generation. Results In the first experiment, prevalence and intensity of F. hepatica infection in snails progressively increased from the F1 (R. balthica) or F2 (L. fuscus) generation. In the second experiment, the prevalence of F. hepatica infection and the number of shed cercariae were significantly lower in L. fuscus and R. balthica (without significant differences between both lymnaeids) than in G. truncatula. Conclusion The F. hepatica infection of several successive snail generations

  8. Organic filler from golden apple snails shells to improve the silicone rubber insulator properties

    Science.gov (United States)

    Tepsila, Sujirat; Suksri, Amnart

    2018-02-01

    This paper investigates the effect of an addition of filler compound using golden apple snail shell as an organic filler to the silicone rubber insulator. The filler obtained from golden apple snail shell is found mostly contained calcium carbonate. The organic calcium carbonate (CaCO3) with particle size of 45, 75, 100 and 300 micron were prepared. Sample of silicone rubber that were filled with fillers were tested under ASTM D638-02a type standard for mechanical test. Also, electrical test such as I-V characteristics (ASTM D257-07) and dry arc test according to ASTM D495-14 have been performed. The results revealed that using larger particle size of organic filler obtained from the golden apple snail shell resulted to higher value of dielectric constant as well as higher dielectric strength. Also, the filler helps slow down the tracking activity at an insulator surface due to its crystals of calcium carbonate. However, when using excessive amount of filler, the sample will have a drawbacks in mechanical properties. By using agriculture waste as a filler compound, one can reduced the usage of commercial CaCO3 as an inorganic materials and to lower the investment cost to a final silicone rubber product.

  9. The effect of changes in habitat conditions on the movement of juvenile Snail Kites Rostrhamus sociabilis

    Science.gov (United States)

    Bowling, Andrea C.; Martin, Julien; Kitchens, Wiley M.

    2012-01-01

    The degradation of habitats due to human activities is a major topic of interest for the conservation and management of wild populations. There is growing evidence that the Florida Everglades ecosystem continues to suffer from habitat degradation. After a period of recovery in the 1990s, the Snail Kite Rostrhamus sociabilis population suffered a substantial decline in 2001 and has not recovered since. Habitat degradation has been suggested as one of the primary reasons for this lack of recovery. As a consequence of the continued degradation of the Everglades, we hypothesized that this would have led to increased movement of juvenile Kites over time, as a consequence of the need to find more favourable habitat. We used multistate mark-recapture models to compare between-site movement probabilities of juvenile Snail Kites in the 1990s (1992–95; which corresponds to the period before the decline) and 2000s (2003–06; after the decline). Our analyses were based on an extensive radiotelemetry study (266 birds tracked monthly over the entire state of Florida for a total period of 6 years) and considered factors such as sex and age of marked individuals. There was evidence of increased movement of juvenile Snail Kites during the post-decline period from most of the wetland regions used historically by Kites. Higher movement rates may contribute to an increase in the probability of mortality of young individuals and could contribute to the observed declines.

  10. The Compatibility Between Biomphalaria glabrata Snails and Schistosoma mansoni: An Increasingly Complex Puzzle.

    Science.gov (United States)

    Mitta, G; Gourbal, B; Grunau, C; Knight, M; Bridger, J M; Théron, A

    2017-01-01

    This review reexamines the results obtained in recent decades regarding the compatibility polymorphism between the snail, Biomphalaria glabrata, and the pathogen, Schistosoma mansoni, which is one of the agents responsible for human schistosomiasis. Some results point to the snail's resistance as explaining the incompatibility, while others support a "matching hypothesis" between the snail's immune receptors and the schistosome's antigens. We propose here that the two hypotheses are not exclusive, and that the compatible/incompatible status of a particular host/parasite couple probably reflects the balance of multiple molecular determinants that support one hypothesis or the other. Because these genes are involved in a coevolutionary arms race, we also propose that the underlying mechanisms can vary. Finally, some recent results show that environmental factors could influence compatibility. Together, these results make the compatibility between B. glabrata and S. mansoni an increasingly complex puzzle. We need to develop more integrative approaches in order to find targets that could potentially be manipulated to control the transmission of schistosomiasis. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

    Jeong, J; Toida, T; Muneta, Y; Kosiishi, I; Imanari, T; Linhardt, R J; Choi, H S; Wu, S J; Kim, Y S

    2001-12-01

    Acharan sulfate is a glycosaminoglycan (GAG), having the structure -->4)-2-acetamido-2-deoxy-alpha-D-glucopyranose(1-->4)-2-sulfo-alpha-L-idopyranosyluronic acid (1-->, isolated from the body of the giant African snail Achatina fulica. This GAG represents 3-5% of the dry weight of this snail's soft body tissues. Frozen sections and polyester wax sections of the snail's body were stained by Alcian blue-periodic acid-Schiff's reagent (PAS) to localize acharan sulfate. Alcian blue staining indicated that GAG was mainly secreted into the outer surface of the body from internal granules. A highly mucous material was collected and treated and the acharan sulfate was recovered by ethanol and cetyl pyridinium chloride precipitation. Crude acharan sulfate was purified by DEAE-Sephacel ion-exchange chromatography. Depolymerization of intact mucus and purified acharan sulfate fractions by heparin lyase II (heparitinase I) from Flavobacterium heparinum produced an unsaturated disaccharide as a major product, establishing the repeating unit of acharan sulfate. These results demonstrate that mucus in the granule and secreted to the outside of the body is composed entirely of acharan sulfate.

  12. Thevetia peruviana (Family: Apocynaceae in the control of slug and snail pests

    Directory of Open Access Journals (Sweden)

    A. Panigrahi

    1994-06-01

    Full Text Available An aqueous extract prepared from Kernels of the fruit of Thevetia peruviana (Pers. Schumann (Family : Apocynaceae was found under experimental conditions, to be toxic ti the slug Laevicaulis alte (Férussac and the snail Achatina fulica Bowdich, the important agrihorticultural pests of Indo-Pacific countries. Concentrations as low as 1% (w/v killed all the slugs exposed in less than 981.00 (± SD 22.76 min, and 2% of the extract killed 100% of the slugs L. alte and 50%, 50% and 30% of the snail A. fulica in between 92.34 (± SD 6.63 - 321.33 (± SD 4.14 and 271.20 (± SD 17.54 - 298.26 (± SD 16.69 min respectively. The most effective concentration of the extract was 20%; it killed 100% of exposed slugs and snails within a short time (40-50 and 90-1440 min respectively when the extract was exposed on the soil in experimental trays or when it was applied to potato slices offered as food to the gastropods.

  13. Chemoreception of hunger levels alters the following behaviour of a freshwater snail.

    Science.gov (United States)

    Larcher, Marie; Crane, Adam L

    2015-12-01

    Chemically-mediated orientation is essential for many animals that must locate sites containing resources such as mates or food. One way to find these areas is by using publically-available information from other individuals. We tested a freshwater snail, Physa gyrina, for chemoreception of conspecific cues and predicted they could discriminate between cues based on information regarding hunger levels. We placed 'tracker' snails into a 2-arm arena where they could either follow or avoid an area previously used by a 'marker' snail. The hunger levels of both trackers and markers was manipulated, being either starved or fed. Starved and fed trackers did not differ in their following response when markers were hungry, but starved trackers were significantly more likely to follow fed markers, compared to fed trackers that tended to avoid areas used by fed markers. This outcome suggests that P. gyrina uses conspecific chemical cues to find food and potentially in some situations to avoid intra-specific food competition. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Gender-based differences in Florida apple snail (Pomacea paludosa) movements

    Science.gov (United States)

    Valentine-Darby, P. L.; Darby, P.C.; Percival, H.F.

    2011-01-01

    Gastropod movements have been studied in the context of habitat selection, finding food and mates, and avoiding predation. Many of these studies were conducted in the laboratory, where constraints on spatial scale influence behavior. We conducted a field study of Florida apple snail (Pomacea paludosa) movements using telemetry. We hypothesized that Florida apple snail movements were driven by reproductive activity, and that gender differences would be evident. We documented male and female directions and distances traveled. We also conducted a trapping study that included conspecific bait to test if the presence of females attracted more males as measured by M:F ratios in traps. The greatest distances traveled were by males, and males were more likely to maintain a consistent bearing compared to females. Male distances peaked in what typically corresponds to peak breeding season. M:F ratios in traps were positively associated with reproductive activity in the study population as measured by egg cluster counts. Conspecific bait had no effect on the number of males or females captured. However, if a female crawled into the trap, we observed greater numbers of males compared to those with no trapped females. Males may have tracked females to increase mating encounters, following slime trails, as seen in other aquatic (including other Pomacea) snails. The capacity for mate finding has implications for reproductive success in the relatively low density populations often seen for Pomacea paludosa.

  15. Sexual selection on land snail shell ornamentation: a hypothesis that may explain shell diversity

    Directory of Open Access Journals (Sweden)

    Schilthuizen Menno

    2003-06-01

    Full Text Available Abstract Background Many groups of land snails show great interspecific diversity in shell ornamentation, which may include spines on the shell and flanges on the aperture. Such structures have been explained as camouflage or defence, but the possibility that they might be under sexual selection has not previously been explored. Presentation of the hypothesis The hypothesis that is presented consists of two parts. First, that shell ornamentation is the result of sexual selection. Second, that such sexual selection has caused the divergence in shell shape in different species. Testing the hypothesis The first part of the hypothesis may be tested by searching for sexual dimorphism in shell ornamentation in gonochoristic snails, by searching for increased variance in shell ornamentation relative to other shell traits, and by mate choice experiments using individuals with experimentally enhanced ornamentation. The second part of the hypothesis may be tested by comparing sister groups and correlating shell diversity with degree of polygamy. Implications of the hypothesis If the hypothesis were true, it would provide an explanation for the many cases of allopatric evolutionary radiation in snails, where shell diversity cannot be related to any niche differentiation or environmental differences.

  16. 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.

  17. Coded Splitting Tree Protocols

    DEFF Research Database (Denmark)

    Sørensen, Jesper Hemming; Stefanovic, Cedomir; Popovski, Petar

    2013-01-01

    This paper presents a novel approach to multiple access control called coded splitting tree protocol. The approach builds on the known tree splitting protocols, code structure and successive interference cancellation (SIC). Several instances of the tree splitting protocol are initiated, each...... instance is terminated prematurely and subsequently iterated. The combined set of leaves from all the tree instances can then be viewed as a graph code, which is decodable using belief propagation. The main design problem is determining the order of splitting, which enables successful decoding as early...

  18. Morocco - Fruit Tree Productivity

    Data.gov (United States)

    Millennium Challenge Corporation — Date Tree Irrigation Project: The specific objectives of this evaluation are threefold: - Performance evaluation of project activities, like the mid-term evaluation,...

  19. Responses of Withdrawal Interneurons to Serotonin Applications in Naïve and Learned Snails Are Different

    Directory of Open Access Journals (Sweden)

    Tatiana K. Bogodvid

    2017-12-01

    Full Text Available Long-term changes in membrane potential after associative training were described previously in identified premotor interneurons for withdrawal of the terrestrial snail Helix. Serotonin was shown to be a major transmitter involved in triggering the long-term changes in mollusks. In the present study we compared the changes in electrophysiological characteristics of identifiable premotor interneurons for withdrawal in response to bath applications of serotonin (5-HT or serotonin precursor 5-hydroxytryptophan (5-HTP in preparations from naïve, neurotoxin-injected or associatively trained snails. It was found that 5-HT or 5-HTP applications caused a significant decrease of membrane potential in premotor interneurons of naïve snails, associatively trained snails and snails with impaired serotonergic system by injection of a selective neurotoxin 5,7-dihydroxytryptamine (5,7-DHT 1 week before the experiments. Applications of 5-HT or 5-HTP did not cause significant changes in the action potential (AP threshold potential of these neurons in naïve snails. Conversely, applications of 5-HT or 5-HTP to the premotor interneurons of previously trained or 5,7-DHT-injected snails caused a significant increase in the firing threshold potential in spite of a depolarizing shift of the resting membrane potential. Results demonstrate that responsiveness of premotor interneurons to extracellularly applied 5-HT or 5-HTP changes for days after the associative training or serotonin depletion. Similarity of the effects in trained and 5,7-DHT-injected animals may be due to massive release of serotonin elicited by 5,7-DHT injection. Our results suggest that serotonin release due to aversive conditionining or elicited by the neurotoxin administration triggers similar changes in resting membrane potential and AP threshold in response to bath applications of 5-HT or its precursor 5-HTP.

  20. Impact of the Three Gorges project on ecological environment changes and snail distribution in Dongting Lake area.

    Directory of Open Access Journals (Sweden)

    Feiyue Li

    2017-07-01

    Full Text Available The Three Gorges Dam (TGD is a remarkable, far-reaching project in China. This study was conducted to assess the impact of TGD on changes in the ecological environment, snail distribution and schistosomiasis transmission in Dongting Lake area.Hydrological data were collected from 12 monitoring sites in Hunan section of Yangtze River before and after TGD was established. Data on snail distribution and human schistosomiasis infection were also collected. Correlation analyses were performed to detect the significance of snail distribution to changes in ecological environmental factors and human schistosomiasis infection.A series of ecological environmental factors have changed in Dongting Lake area following the operation of TGD. Volume of annual runoff discharged into Dongting Lake declined by 20.85%. Annual sediment volume discharged into the lake and the mean lake sedimentation rate decreased by 73.9% and 32.2%, respectively. From 2003 to 2015, occurrence rate of frames with living snails and mean density of living snails decreased overall by 82.43% and 94.35%, respectively, with annual decrements being 13.49% and 21.29%. Moreover, human infection rate of schistosomiasis had decreased from 3.38% in 2003 to 0.44% in 2015, with a reduction of 86.98%. Correlation analyses showed that mean density of living snails was significantly associated with water level (r = 0.588, p<0.001, as well as the mean elevation range of the bottomland (r = 0.374, p = 0.025 and infection rate of schistosomiasis (r = 0.865, p<0.001.Ecological environmental changes caused by the TGD were associated with distribution of snails, and might further affect the transmission and prevalence of schistosomiasis. Risk of schistosomiasis transmission still exists in Dongting Lake area and long-term monitoring is required.

  1. Are trees long-lived?

    Science.gov (United States)

    Kevin T. Smith

    2009-01-01

    Trees and tree care can capture the best of people's motivations and intentions. Trees are living memorials that help communities heal at sites of national tragedy, such as Oklahoma City and the World Trade Center. We mark the places of important historical events by the trees that grew nearby even if the original tree, such as the Charter Oak in Connecticut or...

  2. Fragmentation of random trees

    International Nuclear Information System (INIS)

    Kalay, Z; Ben-Naim, E

    2015-01-01

    We study fragmentation of a random recursive tree into a forest by repeated removal of nodes. The initial tree consists of N nodes and it is generated by sequential addition of nodes with each new node attaching to a randomly-selected existing node. As nodes are removed from the tree, one at a time, the tree dissolves into an ensemble of separate trees, namely, a forest. We study statistical properties of trees and nodes in this heterogeneous forest, and find that the fraction of remaining nodes m characterizes the system in the limit N→∞. We obtain analytically the size density ϕ s of trees of size s. The size density has power-law tail ϕ s ∼s −α with exponent α=1+(1/m). Therefore, the tail becomes steeper as further nodes are removed, and the fragmentation process is unusual in that exponent α increases continuously with time. We also extend our analysis to the case where nodes are added as well as removed, and obtain the asymptotic size density for growing trees. (paper)

  3. The tree BVOC index

    Science.gov (United States)

    J.R. Simpson; E.G. McPherson

    2011-01-01

    Urban trees can produce a number of benefits, among them improved air quality. Biogenic volatile organic compounds (BVOCs) emitted by some species are ozone precursors. Modifying future tree planting to favor lower-emitting species can reduce these emissions and aid air management districts in meeting federally mandated emissions reductions for these compounds. Changes...

  4. Tree growth visualization

    Science.gov (United States)

    L. Linsen; B.J. Karis; E.G. McPherson; B. Hamann

    2005-01-01

    In computer graphics, models describing the fractal branching structure of trees typically exploit the modularity of tree structures. The models are based on local production rules, which are applied iteratively and simultaneously to create a complex branching system. The objective is to generate three-dimensional scenes of often many realistic- looking and non-...

  5. Flowering T Flowering Trees

    Indian Academy of Sciences (India)

    Adansonia digitata L. ( The Baobab Tree) of Bombacaceae is a tree with swollen trunk that attains a dia. of 10m. Leaves are digitately compound with leaflets up to 18cm. long. Flowers are large, solitary, waxy white, and open at dusk. They open in 30 seconds and are bat pollinated. Stamens are many. Fruit is about 30 cm ...

  6. Fault tree graphics

    International Nuclear Information System (INIS)

    Bass, L.; Wynholds, H.W.; Porterfield, W.R.

    1975-01-01

    Described is an operational system that enables the user, through an intelligent graphics terminal, to construct, modify, analyze, and store fault trees. With this system, complex engineering designs can be analyzed. This paper discusses the system and its capabilities. Included is a brief discussion of fault tree analysis, which represents an aspect of reliability and safety modeling

  7. Tree biology and dendrochemistry

    Science.gov (United States)

    Kevin T. Smith; Walter C. Shortle

    1996-01-01

    Dendrochemistry, the interpretation of elemental analysis of dated tree rings, can provide a temporal record of environmental change. Using the dendrochemical record requires an understanding of tree biology. In this review, we pose four questions concerning assumptions that underlie recent dendrochemical research: 1) Does the chemical composition of the wood directly...

  8. Individual tree control

    Science.gov (United States)

    Harvey A. Holt

    1989-01-01

    Controlling individual unwanted trees in forest stands is a readily accepted method for improving the value of future harvests. The practice is especially important in mixed hardwood forests where species differ considerably in value and within species individual trees differ in quality. Individual stem control is a mechanical or chemical weeding operation that...

  9. Trees and Climate Change

    OpenAIRE

    Dettenmaier, Megan; Kuhns, Michael; Unger, Bethany; McAvoy, Darren

    2017-01-01

    This fact sheet describes the complex relationship between forests and climate change based on current research. It explains ways that trees can mitigate some of the risks associated with climate change. It details the impacts that forests are having on the changing climate and discuss specific ways that trees can be used to reduce or counter carbon emissions directly and indirectly.

  10. Structural Equation Model Trees

    Science.gov (United States)

    Brandmaier, Andreas M.; von Oertzen, Timo; McArdle, John J.; Lindenberger, Ulman

    2013-01-01

    In the behavioral and social sciences, structural equation models (SEMs) have become widely accepted as a modeling tool for the relation between latent and observed variables. SEMs can be seen as a unification of several multivariate analysis techniques. SEM Trees combine the strengths of SEMs and the decision tree paradigm by building tree…

  11. Matching Subsequences in Trees

    DEFF Research Database (Denmark)

    Bille, Philip; Gørtz, Inge Li

    2009-01-01

    Given two rooted, labeled trees P and T the tree path subsequence problem is to determine which paths in P are subsequences of which paths in T. Here a path begins at the root and ends at a leaf. In this paper we propose this problem as a useful query primitive for XML data, and provide new...

  12. Environmental tritium in trees

    International Nuclear Information System (INIS)

    Brown, R.M.

    1979-01-01

    The distribution of environmental tritium in the free water and organically bound hydrogen of trees growing in the vicinity of the Chalk River Nuclear Laboratories (CRNL) has been studied. The regional dispersal of HTO in the atmosphere has been observed by surveying the tritium content of leaf moisture. Measurement of the distribution of organically bound tritium in the wood of tree ring sequences has given information on past concentrations of HTO taken up by trees growing in the CRNL Liquid Waste Disposal Area. For samples at background environmental levels, cellulose separation and analysis was done. The pattern of bomb tritium in precipitation of 1955-68 was observed to be preserved in the organically bound tritium of a tree ring sequence. Reactor tritium was discernible in a tree growing at a distance of 10 km from CRNL. These techniques provide convenient means of monitoring dispersal of HTO from nuclear facilities. (author)

  13. aPKC-ι/P-Sp1/Snail signaling induces epithelial-mesenchymal transition and immunosuppression in cholangiocarcinoma.

    Science.gov (United States)

    Qian, Yawei; Yao, Wei; Yang, Tao; Yang, Yan; Liu, Yan; Shen, Qi; Zhang, Jian; Qi, Weipeng; Wang, Jianming

    2017-10-01

    Cholangiocarcinoma (CCA) is a highly malignant bile duct cancer that tends to invade and metastasize early. The epithelial-mesenchymal transition (EMT) has been implicated in cancer cell invasion and metastasis, as well as in cancer cell evasion of host immunity. In this study, we investigated the interaction between atypical protein kinase C-iota (aPKC-ι) and Snail in the regulation of EMT and its relationship to CCA immunosuppression. Our results demonstrated that aPKC-ι, Snail, and infiltrated immunosuppressive cells were significantly up-regulated in CCA tumor tissues and linked to poor prognosis. aPKC-ι induced EMT and immunosuppression by regulating Snail in vitro and in vivo, although aPKC-ι did not directly interact with Snail in coimmunoprecipitation experiments. To further clarify the molecular interaction between aPKC-ι and Snail in relation to EMT, quantitative iTRAQ-based phosphoproteomic analysis and liquid chromatography-tandem mass spectrometry were conducted to identify the substrates of aPKC-ι-dependent phosphorylation. Combined with coimmunoprecipitation, we showed that specificity protein 1 (Sp1) was directly phosphorylated by aPKC-ι on Ser59 (P-Sp1). Both Sp1 and P-Sp1 were up-regulated in CCA tumor tissues and associated with clinicopathological features and poor prognosis in CCA patients. Moreover, using chromatin immunoprecipitation assays, we found that P-Sp1 regulated Snail expression by increasing Sp1 binding to the Snail promoter. P-Sp1 also regulated aPKC-ι/Snail-induced EMT-like changes and immunosuppression in CCA cells. Our findings further indicated that CCA cells with EMT-like features appear to generate immunosuppressive natural T regulatory-like cluster of differentiation 4-positive (CD4 + )CD25 - cells rather than to increase CD4 + CD25 + natural T regulatory cells, in part by mediating T regulatory-inducible cytokines such as transforming growth factor β1 and interleukin 2. These results demonstrate that a

  14. Generalising tree traversals and tree transformations to DAGs

    DEFF Research Database (Denmark)

    Bahr, Patrick; Axelsson, Emil

    2017-01-01

    We present a recursion scheme based on attribute grammars that can be transparently applied to trees and acyclic graphs. Our recursion scheme allows the programmer to implement a tree traversal or a tree transformation and then apply it to compact graph representations of trees instead. The resul......We present a recursion scheme based on attribute grammars that can be transparently applied to trees and acyclic graphs. Our recursion scheme allows the programmer to implement a tree traversal or a tree transformation and then apply it to compact graph representations of trees instead...... as the complementing theory with a number of examples....

  15. Isolation and characterization of cultivable fermentative bacteria from the intestine of two edible snails, Helixpomatia and Cornu aspersum (Gastropoda: Pulmonata

    Directory of Open Access Journals (Sweden)

    MAR YVONNE CHARRIER

    2006-01-01

    Full Text Available The intestinal microbiota of the edible snails Cornu aspersum fSyn: H. aspersa, and Helix pomatia were investigated by culture-based methods, 16S rRNA sequence analyses and phenotypic characterisations. The study was carried out on aestivating snails and two populations of H. pomatia were considered. The cultivable bacteria dominated in the distal part of the intestine, with up to 5.10(9 CFU g -1, but the Swedish H. pomatia appeared significantly less colonised, suggesting a higher sensitivity of its microbiota to climatic change. All the strains, but one, shared ≥ 97% sequence identity with reference strains. They were arranged into two taxa: the Gamma Proteobacteria with Buttiauxella, Citrobacter, Enterobacter, Kluyvera, Obesumbacterium, Raoultella and the Firmicutes with Enterococcus, Lactococcus, and Clostridium. According to the literature, these genera are mostly assigned to enteric environments or to phyllosphere, data in favour of culturing snails in contact with soil and plants. None of the strains were able to digest filter paper, Avicel cellulose or carboxymethyl cellulose (CMC. Acetogens and methanogenic archaea were not cultivated, so the fate of hydrogen remains questionable. This microbiota could play important roles in the digestive process (fermentation and the energy supply of the snail (L-lactate, acetate. The choice of cereals and plants by snail farmers should take into account the fermentative abilities of the intestinal microbiota

  16. Utilization of the invasive plant Impatiens parviflora DC. by the snail Columella edentula Draparnaud in oak-hornbeam forests

    Directory of Open Access Journals (Sweden)

    Renata Piskorz

    2011-01-01

    Full Text Available This study investigated the extend to which the snail Columella edentula is more strongly associated with the small balsam Impatiens parviflora than with other plants in the herb layer of an oak-hornbeam forest, and to interpret the character of the interaction Impatiens parviflora - Columella edentula. Numbers of C. edentula and rates of colonization were compared on various plant species under natural and laboratory conditions. Seasonal variation in snail abundance on I. parviflora was observed on permanent plots. The leaf injuries caused by C. edentula were localized in respect of the morphological and anatomical structure of leaves. The results show that I. parviflora is one of the plant species of the herb layer that are most abundantly colonized by this snail in oak-hornbeam forest. Snail finds a plant particularly suitable as a place for resting. The most favoured attachment site is on the underside of the leaf, along the midrib, which provides the highest and relatively stable humidity, as well as protection from direct sunlight and predators. I. parviflora is also a food for the snails, but they do not eat these fragments of leaves where calcium carbonate is accumulated.

  17. Morphological and molecular characterization of lymnaeid snails and their potential role in transmission of Fasciola spp. in Vietnam.

    Science.gov (United States)

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

    2013-12-01

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

  18. Radiation decontamination of Peruvian marine ''lead snail'' (Thais chocolata) inoculated with Vibrio cholerae O1 El Tor

    International Nuclear Information System (INIS)

    Torres, Z.; Arias, F.

    2001-01-01

    In vivo studies were conducted using marine snails (Thais chocolata) artificially contaminated in a tank containing sea water inoculated with a pure culture of Vibrio cholerae, such that 10 5 colony forming units per gram (CFU/g) were uptaken by the mollusks in 1.5 h. A radiation D 10 value of 0.12 kGy was determined for V. cholerae upon subsequent irradiation of the live snails at doses in the range 0.0-4.0 kGy. A second series of tests were conducted using naturally contaminated, non-inoculated snails, shelled and packaged simulating commercial procedures, irradiated at 0.0-3.0 kGy, and stored at 2-4 deg. C. These tests indicated that a dose of 2.0 kGy was optimal to extend the microbiological shelf-life of the snails to 21 days without inducing significant adverse sensory or chemical effects. Non-irradiated snails similarly treated and stored spoiled after only seven days. (author)

  19. [Investigation on snails Achatina fulica and Pomacea canaliculata infected with Angiostrongylus cantonensis in Panyu region of Guangzhou City].

    Science.gov (United States)

    Chen, Chu-Xuan; He, Hui-Fang; Yin, Zhu; Zhou, Jin-Huan; Li, Shi-Qun; Li, Fang-Hui; Chen, Jiong-Min; Zhu, Wei-Jin; Zhong, Xiu-Ming; Yang, Kai-Ying; Liu, Gui-Ping; Jia, Xun; Chen, Wan-Tong; Li, Xiao-Mei; Chen, Yu-Chang; Luo, Xiao-Dong; Chen, Dai-Xiong; Shen, Hao-Xian

    2012-06-01

    To understand the natural infection status of Angiostrongylus cantonensis in snails Achatina fulica and Pomacea canaliculata from Panyu region of Guangzhou City. The snails Achatina fulica and Pomacea canaliculata captured from the field were digested with the artificial stomach fluid. The third-stage larvae of A. cantonensis were examined and counted under a microscope. The collected third-stage larvae were used to infect SD rats. A total of 367 Achatina fulica and 357 Pomacea canaliculata were examined. The infection rate of A. cantonensis in Achatina fulica was 22.62%, with a mean intensity of 57.00 larvae per positive snail. The infection rate of A. cantonensis in Pomacea canaliculata was 3.08%, with a mean intensity of 1.64 larvae per positive snail. The infection rates of A. cantonensis in Achatina fulica from Dagang, Shiqi, Hualong, and Lanhe towns and Nansha District, were 13.33%, 15.00%, 20.93%, 73.68% and 8.41%, respectively. Those in Pomacea canaliculata were 5.88%, 2.88%, 1.89%, 0% and 3.96%, respectively. A. cantonensis infection exists in Achatina fulica and Pomacea canaliculata from Panyu region of Guangzhou City, and the infection in Achatina fulica is more serious than that in Pomacea canaliculata. The infection rates of the snails among five sites are different.

  20. Predation as the primary selective force in recurrent evolution of gigantism in Poecilozonites land snails in Quaternary Bermuda

    Science.gov (United States)

    Olson, Storrs L.; Hearty, Paul J.

    2010-01-01

    During the last half million years, pulses of gigantism in the anagenetic lineage of land snails of the subgenus Poecilozonites on Bermuda were correlated with glacial periods when lower sea level resulted in an island nearly an order of magnitude larger than at present. During those periods, the island was colonized by large vertebrate predators that created selection pressure for large size and rapid growth in the snails. Extreme reduction in land area from rising seas, along with changes in ecological conditions at the onset of interglacial episodes, marked extinction events for large predators, after which snails reverted to much smaller size. The giant snails were identical in morphology during the last two glacials when the predators included a large flightless rail Rallus recessus (marine isotope stages (MIS) 4-2) and a crane Grus latipes and a duck Anas pachysceles (MIS 6). In a preceding glacial period (MIS 10), when the fauna also included the tortoise Hesperotestudo bermudae, the snails were not only large, but the shells were much thicker, presumably to prevent crushing by tortoises. Evolution of Poecilozonites provides an outstanding example of dramatic morphological change in response to environmental pressures in the absence of cladogenesis. PMID:20554560

  1. Elemental compositions of crab and snail shells from the Kueishantao hydrothermal field in the southwestern Okinawa Trough

    Science.gov (United States)

    Zeng, Zhigang; Ma, Yao; Wang, Xiaoyuan; Chen, Chen-Tung Arthur; Yin, Xuebo; Zhang, Suping; Zhang, Junlong; Jiang, Wei

    2018-04-01

    To reveal differences in the behavior of benthic vent animals, and the sources and sinks of biogeochemical and fluid circulations, it is necessary to constrain the chemical characteristics of benthic animals from seafloor hydrothermal fields. We measured the abundances of 27 elements in shells of the crab Xenograpsus testudinatus and the snail Anachis sp., collected from the Kueishantao hydrothermal field (KHF) in the southwestern Okinawa Trough, with the aim of improving our understanding of the compositional variations between individual vent organisms, and the sources of the rare earth elements (REEs) in their shells. The Mn, Hg, and K concentrations in the male X. testudinatus shells are found to be higher than those in female crab shells, whereas the reverse is true for the accumulation of B, implying that the accumulation of K, Mn, Hg, and B in the crab shells is influenced by sex. This is inferred to be a result of the asynchronous molting of the male and female crab shells. Snail shells are found to have higher Ca, Al, Fe, Ni, and Co concentrations than crab shells. This may be attributed to different metal accumulation times. The majority of the light rare earth element (LREE) distribution patterns in the crab and snail shells are similar to those of Kueishantao vent fluids, with the crab and snail shells also exhibiting LREE enrichment, implying that the LREEs contained in crab and snail shells in the KHF are derived from vent fluids.

  2. Parasites reduce food web robustness because they are sensitive to secondary extinction as illustrated by an invasive estuarine snail

    Science.gov (United States)

    Lafferty, Kevin D.; Kuris, Armand M.

    2009-01-01

    A robust food web is one in which few secondary extinctions occur after removing species. We investigated how parasites affected the robustness of the Carpinteria Salt Marsh food web by conducting random species removals and a hypothetical, but plausible, species invasion. Parasites were much more likely than free-living species to suffer secondary extinctions following the removal of a free-living species from the food web. For this reason, the food web was less robust with the inclusion of parasites. Removal of the horn snail, Cerithidea californica, resulted in a disproportionate number of secondary parasite extinctions. The exotic Japanese mud snail, Batillaria attramentaria, is the ecological analogue of the native California horn snail and can completely replace it following invasion. Owing to the similarities between the two snail species, the invasion had no effect on predator–prey interactions. However, because the native snail is host for 17 host-specific parasites, and the invader is host to only one, comparison of a food web that includes parasites showed significant effects of invasion on the native community. The hypothetical invasion also significantly reduced the connectance of the web because the loss of 17 native trematode species eliminated many links.

  3. Elevated native terrestrial snail abundance and diversity in association with an invasive understory shrub, Berberis thunbergii, in a North American deciduous forest

    Science.gov (United States)

    Utz, Ryan M.; Pearce, Timothy A.; Lewis, Danielle L.; Mannino, Joseph C.

    2018-01-01

    Invasive terrestrial plants often substantially reshape environments, yet how such invasions affect terrestrial snail assemblages remains understudied. We investigated how snail assemblages in deciduous forest soils with dense Berberis thunbergii (Japanese barberry), an invasive shrub in eastern North America, differ from forest areas lacking the shrub. Leaf litter and soil samples were collected from forest patches with dense B. thunbergii understories and adjacent control areas within two exurban forest tracts in western Pennsylvania, U.S.A. Snails were identified to species and quantified by standard diversity metrics. Contrary to our expectations, snails were significantly more abundant and diverse in B. thunbergii-invaded areas. Despite differences in abundance, the snail community composition did not differ between invaded and control habitats. The terrestrial snail assemblage we observed, which was composed entirely of native species, appears to respond favorably to B. thunbergii invasion and therefore may not be negatively impacted by physicochemical changes to soils typically observed in association with the plant. Such findings could reflect the fact that B. thunbergii likely creates more favorable habitat for snails by creating cooler, more humid, and more alkaline soil environments. However, the snail assemblages we retrieved may consist mostly of species with high tolerance to environmental degradation due to a legacy of land use change and acid deposition in the region.

  4. 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...

  5. A recursive algorithm for trees and forests

    OpenAIRE

    Guo, Song; Guo, Victor J. W.

    2017-01-01

    Trees or rooted trees have been generously studied in the literature. A forest is a set of trees or rooted trees. Here we give recurrence relations between the number of some kind of rooted forest with $k$ roots and that with $k+1$ roots on $\\{1,2,\\ldots,n\\}$. Classical formulas for counting various trees such as rooted trees, bipartite trees, tripartite trees, plane trees, $k$-ary plane trees, $k$-edge colored trees follow immediately from our recursive relations.

  6. Phylogenetic trees in bioinformatics

    Energy Technology Data Exchange (ETDEWEB)

    Burr, Tom L [Los Alamos National Laboratory

    2008-01-01

    Genetic data is often used to infer evolutionary relationships among a collection of viruses, bacteria, animal or plant species, or other operational taxonomic units (OTU). A phylogenetic tree depicts such relationships and provides a visual representation of the estimated branching order of the OTUs. Tree estimation is unique for several reasons, including: the types of data used to represent each OTU; the use ofprobabilistic nucleotide substitution models; the inference goals involving both tree topology and branch length, and the huge number of possible trees for a given sample of a very modest number of OTUs, which implies that fmding the best tree(s) to describe the genetic data for each OTU is computationally demanding. Bioinformatics is too large a field to review here. We focus on that aspect of bioinformatics that includes study of similarities in genetic data from multiple OTUs. Although research questions are diverse, a common underlying challenge is to estimate the evolutionary history of the OTUs. Therefore, this paper reviews the role of phylogenetic tree estimation in bioinformatics, available methods and software, and identifies areas for additional research and development.

  7. Skewed Binary Search Trees

    DEFF Research Database (Denmark)

    Brodal, Gerth Stølting; Moruz, Gabriel

    2006-01-01

    It is well-known that to minimize the number of comparisons a binary search tree should be perfectly balanced. Previous work has shown that a dominating factor over the running time for a search is the number of cache faults performed, and that an appropriate memory layout of a binary search tree...... can reduce the number of cache faults by several hundred percent. Motivated by the fact that during a search branching to the left or right at a node does not necessarily have the same cost, e.g. because of branch prediction schemes, we in this paper study the class of skewed binary search trees....... For all nodes in a skewed binary search tree the ratio between the size of the left subtree and the size of the tree is a fixed constant (a ratio of 1/2 gives perfect balanced trees). In this paper we present an experimental study of various memory layouts of static skewed binary search trees, where each...

  8. Three Gorges Dam: Impact of Water Level Changes on the Density of Schistosome-Transmitting Snail Oncomelania hupensis in Dongting Lake Area, China.

    Directory of Open Access Journals (Sweden)

    Jin-Yi Wu

    Full Text Available Schistosomiasis remains an important public health issue in China and worldwide. Oncomelania hupensis is the unique intermediate host of schistosoma japonicum, and its change influences the distribution of S. japonica. The Three Gorges Dam (TGD has substantially changed the ecology and environment in the Dongting Lake region. This study investigated the impact of water level and elevation on the survival and habitat of the snails.Data were collected for 16 bottomlands around 4 hydrological stations, which included water, density of living snails (form the Anxiang Station for Schistosomiasis Control and elevation (from Google Earth. Based on the elevation, sixteen bottomlands were divided into 3 groups. ARIMA models were built to predict the density of living snails in different elevation areas.Before closure of TGD, 7 out of 9 years had a water level beyond the warning level at least once at Anxiang hydrological station, compared with only 3 out of 10 years after closure of TGD. There were two severe droughts that happened in 2006 and 2011, with much fewer number of flooding per year compared with other study years. Overall, there was a correlation between water level changing and density of living snails variation in all the elevations areas. The density of living snails in all elevations areas was decreasing after the TGD was built. The relationship between number of flooding per year and the density of living snails was more pronounced in the medium and high elevation areas; the density of living snails kept decreasing from 2003 to 2014. In low elevation area however, the density of living snails decreased after 2003 first and turned to increase after 2011. Our ARIMA prediction models indicated that the snails would not disappear in the Dongting Lake region in the next 7 years. In the low elevation area, the density of living snails would increase slightly, and then stabilize after the year 2017. In the medium elevation region, the change of

  9. The gravity apple tree

    International Nuclear Information System (INIS)

    Aldama, Mariana Espinosa

    2015-01-01

    The gravity apple tree is a genealogical tree of the gravitation theories developed during the past century. The graphic representation is full of information such as guides in heuristic principles, names of main proponents, dates and references for original articles (See under Supplementary Data for the graphic representation). This visual presentation and its particular classification allows a quick synthetic view for a plurality of theories, many of them well validated in the Solar System domain. Its diachronic structure organizes information in a shape of a tree following similarities through a formal concept analysis. It can be used for educational purposes or as a tool for philosophical discussion. (paper)

  10. Visualizing phylogenetic tree landscapes.

    Science.gov (United States)

    Wilgenbusch, James C; Huang, Wen; Gallivan, Kyle A

    2017-02-02

    Genomic-scale sequence alignments are increasingly used to infer phylogenies in order to better understand the processes and patterns of evolution. Different partitions within these new alignments (e.g., genes, codon positions, and structural features) often favor hundreds if not thousands of competing phylogenies. Summarizing and comparing phylogenies obtained from multi-source data sets using current consensus tree methods discards valuable information and can disguise potential methodological problems. Discovery of efficient and accurate dimensionality reduction methods used to display at once in 2- or 3- dimensions the relationship among these competing phylogenies will help practitioners diagnose the limits of current evolutionary models and potential problems with phylogenetic reconstruction methods when analyzing large multi-source data sets. We introduce several dimensionality reduction methods to visualize in 2- and 3-dimensions the relationship among competing phylogenies obtained from gene partitions found in three mid- to large-size mitochondrial genome alignments. We test the performance of these dimensionality reduction methods by applying several goodness-of-fit measures. The intrinsic dimensionality of each data set is also estimated to determine whether projections in 2- and 3-dimensions can be expected to reveal meaningful relationships among trees from different data partitions. Several new approaches to aid in the comparison of different phylogenetic landscapes are presented. Curvilinear Components Analysis (CCA) and a stochastic gradient decent (SGD) optimization method give the best representation of the original tree-to-tree distance matrix for each of the three- mitochondrial genome alignments and greatly outperformed the method currently used to visualize tree landscapes. The CCA + SGD method converged at least as fast as previously applied methods for visualizing tree landscapes. We demonstrate for all three mtDNA alignments that 3D

  11. Drift algae, an invasive snail and elevated temperature reduce ecological performance of a warm-temperate seagrass, through additive effects

    DEFF Research Database (Denmark)

    Hoffle, H.; Wernberg, T.; Thomsen, M. S.

    2012-01-01

    Seagrasses are under pressure from multiple concurrent threats, including rising temperatures, invasive species and nutrient-driven algal accumulations. We quantified the abundance of drift algae and the invasive snail Batillaria australis in 3 Halophila ovalis seagrass beds in the Swan River....... The survey showed that drift algae varied considerably between sites and sampling times, and sites experienced average loads of 0.4 to 0.8 kg fresh wt m(-2) and extreme loads up to 2.5 kg fresh wt m(-2). In contrast, invasive snails were constantly abundant at all sites at all collection times (mean...... reduced the length of the 2nd inter node. We found relatively few significant higher-order interactions, suggesting a dominance of additive effects of stress. We conclude that temperature, drift algae and invasive snails are already affecting the ecological performance of H. ovalis in Swan River...

  12. Antimicrobial proteins of Snail mucus (Achatina fulica against Streptococcus mutans and Aggregatibacter actinomycetemcomitans

    Directory of Open Access Journals (Sweden)

    Herluinus Mafranenda DN

    2014-03-01

    Full Text Available Background: Achasin and mytimacin-AF are proteins of snail mucus (Achatina fulica which have antimicrobial activity. Snail mucus is suspected to have other proteins which have antimicrobial activity against Streptococcus mutans and Aggregatibacter actinomycetemcomitans the oral pathologic bacteria. Purpose: The study were aimed to characterize the proteins of snail mucus (Achatina fulica that have antimicrobial activities to Streptococcus mutans and Actinobacillus actinomycetemcomitans, and to compared the antimicrobial effect of achasin and mytimacin-AF. Methods: The sample of study was the mucus of snails which were taken from Yogyakarta Province. The isolation and characterization of protein were conducted by using SDS-PAGE method, electroelution, and dialysis. Nano drop test was conducted to determine protein concentration. The sensitivity test was conducted by using dilution test, and followed by spectrophotometry and paper disc diffusion tests. Results: The study showed that proteins successfully characterized from snail mucus (Achatina fulica were proteins with molecular weights of 83.67 kDa (achasin, 50.81 kDa, 15 kDa, 11.45 kDa (full amino acid sequence of mytimacin-AF and 9.7 kDa (mytimacin-AF. Based on the dilution test, Achasin had better antimicrobial activities against Streptococcus mutans, while mytimacin-AF had better antimicrobial activities against Aggregatibacter actinomycetemcomitans. But the paper disc diffusion test result showed that Achasin had antimicrobial activities against Streptococcus mutans and Aggregatibacter actinomycetemcomitans, while mytimacin-AF had no antimicrobial activities. Conclusion: The proteins with molecular weights of 50.81 kDa, 15 kDa, 11.45 kDa were considered as new antimicrobial proteins isolated from snail mucus. Achasin, had better antimicrobial activities against Streptococcus mutans, while mytimacin-AF had better antimicrobial activities against Aggregatibacter actinomycetemcomitans

  13. Large-scale determinants of intestinal schistosomiasis and intermediate host snail distribution across Africa: does climate matter?

    Science.gov (United States)

    Stensgaard, Anna-Sofie; Utzinger, Jürg; Vounatsou, Penelope; Hürlimann, Eveline; Schur, Nadine; Saarnak, Christopher F L; Simoonga, Christopher; Mubita, Patricia; Kabatereine, Narcis B; Tchuem Tchuenté, Louis-Albert; Rahbek, Carsten; Kristensen, Thomas K

    2013-11-01

    The geographical ranges of most species, including many infectious disease agents and their vectors and intermediate hosts, are assumed to be constrained by climatic tolerances, mainly temperature. It has been suggested that global warming will cause an expansion of the areas potentially suitable for infectious disease transmission. However, the transmission of infectious diseases is governed by a myriad of ecological, economic, evolutionary and social factors. Hence, a deeper understanding of the total disease system (pathogens, vectors and hosts) and its drivers is important for predicting responses 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 are more likely to contract and/or move into cooler areas in the south and east. Importantly, we also note that even though climate per se matters, the impact of humans on habitat play a crucial role in determining the distribution of the intermediate host snails in Africa. Thus, a future contraction in the geographical range size of the intermediate host snails caused by climatic changes does not necessarily translate into a decrease or zero-sum change in human

  14. Comparative Phylogenetic Studies on Schistosoma japonicum and Its Snail Intermediate Host Oncomelania hupensis: Origins, Dispersal and Coevolution.

    Directory of Open Access Journals (Sweden)

    Stephen W Attwood

    Full Text Available Schistosoma japonicum causes major public health problems in China and the Philippines; this parasite, which is transmitted by freshwater snails of the species Oncomelania hupensis, causes the disease intestinal schistosomiasis in humans and cattle. Researchers working on Schistosoma in Africa have described the relationship between the parasites and their snail intermediate hosts as coevolved or even as an evolutionary arms race. In the present study this hypothesis of coevolution is evaluated for S. japonicum and O. hupensis. The origins and radiation of the snails and the parasite across China, and the taxonomic validity of the sub-species of O. hupensis, are also assessed.The findings provide no evidence for coevolution between S. japonicum and O. hupensis, and the phylogeographical analysis suggests a heterochronous radiation of the parasites and snails in response to different palaeogeographical and climatic triggers. The results are consistent with a hypothesis of East to West colonisation of China by Oncomelania with a re-invasion of Japan by O. hupensis from China. The Taiwan population of S. japonicum appears to be recently established in comparison with mainland Chinese populations.The snail and parasite populations of the western mountain region of China (Yunnan and Sichuan appear to have been isolated from Southeast Asian populations since the Pleistocene; this has implications for road and rail links being constructed in the region, which will breach biogeographical barriers between China and Southeast Asia. The results also have implications for the spread of S. japonicum. In the absence of coevolution, the parasite may more readily colonise new snail populations to which it is not locally adapted, or even new intermediate host species; this can facilitate its dispersal into new areas. Additional work is required to assess further the risk of spread of S. japonicum.

  15. Assessment of anoxia tolerance and photoperiod dependence of GABAergic polarity in the pond snail Lymnaea stagnalis.

    Science.gov (United States)

    Buck, Leslie T; Bond, Hilary C; Malik, Aqsa

    2017-01-01

    The pond snail Lymnaea stagnalis is reported to be anoxia-tolerant and if the tolerance mechanism is similar to that of the anoxia-tolerant painted turtle, GABA should play an important role. A potentially confounding factor investigating the role of GABA in anoxia tolerance are reports that GABA has both inhibitory and excitatory effects within L. stagnalis central ganglion. We therefore set out to determine if seasonality or photoperiod has an impact on: 1) the anoxia-tolerance of the intact pond snail, and 2) the response of isolated neuroganglia cluster F neurons to exogenous GABA application. L. stagnalis maintained on a natural summer light cycle were unable to survive any period of anoxic exposure, while those maintained on a natural winter light cycle survived a maximum of 4h. Using intracellular sharp electrode recordings from pedal ganglia cluster F neurons we show that there is a photoperiod dependent shift in the response to GABA. Snails exposed to a 16h:8h light:dark cycle in an environmental chamber (induced summer phenotype) exhibited hyperpolarizing inhibitory responses and those exposed to a 8h:16h light:dark cycle (induced winter phenotype) exhibited depolarizing excitatory responses to GABA application. Using gramicidin-perforated patch recordings we also found a photoperiod dependent shift in the reversal potential for GABA. We conclude that the opposing responses of L. stagnalis central neurons to GABA results from a shift in intracellular chloride concentration that is photoperiod dependent and is likely mediated through the relative efficacy of cation chloride co-transporters. Although the physiological ramifications of the photoperiod dependent shift are unknown this work potentially has important implications for the impact of artificial light pollution on animal health. Copyright © 2016 Elsevier Inc. All rights reserved.

  16. Ecological modulation of environmental stress: interactions between ultraviolet radiation, epibiotic snail embryos, plants and herbivores.

    Science.gov (United States)

    Wahl, Martin

    2008-05-01

    1. The distribution of egg masses of the freshwater snails Lymnaea stagnalis and Planorbarius corneus on the undersides of water lily leaves (e.g. Nuphar lutea) is related to the prevalence of the leaf-mining beetle Galerucella nymphaeae. 2. When given the choice, Planorbarius significantly avoids leaves that were infested by the mining beetle. Conversely, Lymnaea did not discriminate against mined leaves. 3. Intact Nuphar leaves block over 95% of incident ultraviolet radiation. Yet, ultraviolet transmission reaches almost 100% under beetle mining scars. These are several times wider than snail embryos. 4. When exposed to natural sunlight, Lymnaea embryos proved to be resistant to ambient ultraviolet, while Planorbarius embryos were rapidly killed. Thus, one selective advantage of Planorbarius discrimination against mined leaves when depositing its eggs could be the avoidance of ultraviolet radiation passing through mining scars. 5. Other mining-related modifications of the leaves, reduced area, decreased longevity, altered aufwuchs (i.e. biofilm and epibionts) are discussed but seem less relevant for the oviposition preference of Planorbarius. 6. The discriminatory behaviour of this snail species was triggered by water-borne cues emitted by the damaged leaf, not by the eggs or larvae of the beetle. 7. This study illustrates how environmental stress on a given species, ultraviolet radiation in this case, can be ecologically buffered (shading by Nuphar) or enhanced (reduction of Nuphar shading through beetle mining) by associated species. It highlights how the impact of a given stress depends on the identity of the target species as well as on the identity and role of other species in the community.

  17. Previous motor activity affects the transition from uncertainty to decision making in snails.

    Science.gov (United States)

    Korshunova, Tatiana A; Vorontsov, Dmitry D; Dyakonova, Varvara E

    2016-11-15

    One of the most widely accepted benefits of enhanced physical activity is an improvement in the symptoms of depression, including the facilitation of decision making. Up until now, these effects have been shown in rodents and humans only. Little is known about their evolutionary origin or biological basis, and the underlying cellular mechanisms also remain relatively elusive. Here, we demonstrate for the first time that preceding motor activity accelerates decision making in an invertebrate, the pond snail Lymnaea stagnalis To investigate decision making in a novel environment, snails, which normally live in water, were placed on a flat dry surface to simulate the potentially threatening consequence of being in an arid environment. This stimulus initiated two distinct phases in snail behaviour: slow circular movements, followed by intense locomotion in a chosen direction. The first phase was prolonged when the test arena was symmetrically lit, compared with one with an apparent gradient of light. However, forced muscular locomotion for 2 h prior to the test promoted the transition from random circular motions to a directional crawl, accompanied by an increase in crawling speed but with no effect on the choice of direction. Intense locomotion for 2 h also produced a strong excitatory effect on the activity of serotonergic neurons in L. stagnalis Our results suggest that the beneficial effects of physical exercise on cognitive performance in mammals might have deep roots in evolution, granting the opportunity to unravel the origins of such effects at the single-neuron and network levels. © 2016. Published by The Company of Biologists Ltd.

  18. Bisphenol A Induces Superfeminization in the Ramshorn Snail (Gastropoda: Prosobranchia) at Environmentally Relevant Concentrations

    Science.gov (United States)

    Oehlmann, Jörg; Schulte-Oehlmann, Ulrike; Bachmann, Jean; Oetken, Matthias; Lutz, Ilka; Kloas, Werner; Ternes, Thomas A.

    2006-01-01

    Previous investigations have shown that bisphenol A (BPA) induces a superfeminization syndrome in the freshwater snail Marisa cornuarietis at concentrations as low as 1 μg/L. Superfemales are characterized by the formation of additional female organs, enlarged accessory sex glands, gross malformations of the pallial oviduct, and a stimulation of egg and clutch production, resulting in increased female mortality. However, these studies were challenged on the basis of incomplete experimentation. Therefore, the objective of the current approach was to bridge several gaps in knowledge by conducting additional experiments. In an initial series of experiments, study results from the reproductive phase of the snails were evaluated in the sub-micrograms per liter range. Before and after the spawning season, superfemale responses were observed [NOEC (no observed effect concentration) 7.9 ng/L, EC10 (effective concentration at 10%) 13.9 ng/L], which were absent during the spawning season. A further experiment investigated the temperature dependence of BPA responses by exposing snails at two temperatures in parallel. The adverse effect of BPA was at least partially masked at 27°C (EC10 998 ng/L) when compared with 20°C (EC10 14.8 ng/L). In M. cornuarietis, BPA acts as an estrogen receptor (ER) agonist, because effects were completely antagonized by a co-exposure to tamoxifen and Faslodex. Antiandrogenic effects of BPA, such as a significant decrease in penis length at 20°C, were also observed. Competitive receptor displacement experiments indicate the presence of androgen- and estrogen-specific binding sites. The affinity for BPA of the estrogen binding sites in M. cornuarietis is higher than that of the ER in aquatic vertebrates. The results emphasize that prosobranchs are affected by BPA at lower concentrations than are other wildlife groups, and the findings also highlight the importance of exposure conditions. PMID:16818258

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

    KAUST Repository

    Sun, Jin

    2013-11-01

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

  20. NUTRITIONAL EVALUATION OF BREAD WASTE AS A REPLACEMENT FOR MAIZE IN THE DIET OF GROWING SNAILS

    Directory of Open Access Journals (Sweden)

    A.J. OMOLE

    2011-11-01

    Full Text Available The effect of replacing maize fraction of the diet of growing snails partially or wholly with bread waste (BW on performance characteristics and cost benefits was studied for 12 weeks. A total of 120 growing snails (Archachatina marginata of mean weight 83.67 ± 3.5g of about 3 months of age were randomly allotted to 4 dietary treatments, BW1, BW2, BW3 and BW4 in which maize fraction of the diet was replaced at 0, 50, 75 and 100% with BW respectively, in a completely randomized design replicated 3 times. The parameters measured were feed intake, weight gain, shell length, width and thickness. Feed conversion ratio and cost/weight gain were calculated. The results showed that significant differences were not observed in the mean total feed intake, weight gain and shell increment (P>0.05. The results also revealed that dietary treatments had no significant influence on the dressing percentage (P>0.05 which varied between 41.25 and 41.28%. The total feed cost and cost per weight reduced as the level of BW in the diet increased from 0 to 100%. The highest cost/ weight gain (CW of N223.2 was recorded in diet containing 0% BW while the lowest CW was recorded in diet containing 100%BW. Based on the present results maize fraction of snail’s diet could be replaced with bread waste up to 100% at reduced cost without any adverse effect on performance of growing snails.