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Sample records for spin webs spider

  1. Stable isotope analyses of web-spinning spider assemblages along a headwater stream in Puerto Rico

    Directory of Open Access Journals (Sweden)

    Sean P. Kelly

    2015-10-01

    Full Text Available Web-spinning spiders that inhabit stream channels are considered specialists of aquatic ecosystems and are major consumers of emerging aquatic insects, while other spider taxa are more commonly found in riparian forests and as a result may consume more terrestrial insects. To determine if there was a difference in spider taxa abundance between riverine web-spinning spider assemblages within the stream channel and the assemblages 10 m into the riparian forest, we compared abundances for all web-spinning spiders along a headwater stream in El Yunque National Forest in northeast Puerto Rico. By using a nonmetric dimensional scaling (NMDS abundance analysis we were able to see a clear separation of the two spider assemblages. The second objective of the study was to determine if aquatic insects contributed more to the diet of the spider assemblages closest to the stream channel and therefore stable isotope analyses of δ15N and δ13C for web-spinning spiders along with their possible prey were utilized. The results of the Bayesian mixing model (SIAR however showed little difference in the diets of riverine (0 m, riparian (10 m and upland (25 m spiders. We found that aquatic insects made up ∼50% of the diet for web-spinning spiders collected at 0 m, 10 m, and 25 m from the stream. This study highlights the importance of aquatic insects as a food source for web-spinning spiders despite the taxonomic differences in assemblages at different distances from the stream.

  2. Spider Web DNA: A New Spin on Noninvasive Genetics of Predator and Prey.

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    Charles C Y Xu

    Full Text Available Noninvasive genetic sampling enables biomonitoring without the need to directly observe or disturb target organisms. This paper describes a novel and promising source of noninvasive spider and insect DNA from spider webs. Using black widow spiders (Latrodectus spp. fed with house crickets (Acheta domesticus, we successfully extracted, amplified, and sequenced mitochondrial DNA from spider web samples that identified both spider and prey to species. Detectability of spider DNA did not differ between assays with amplicon sizes from 135 to 497 base pairs. Spider and prey DNA remained detectable at least 88 days after living organisms were no longer present on the web. Spider web DNA as a proof-of-concept may open doors to other practical applications in conservation research, pest management, biogeography studies, and biodiversity assessments.

  3. Spider Web DNA: A New Spin on Noninvasive Genetics of Predator and Prey.

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    Xu, Charles C Y; Yen, Ivy J; Bowman, Dean; Turner, Cameron R

    2015-01-01

    Noninvasive genetic sampling enables biomonitoring without the need to directly observe or disturb target organisms. This paper describes a novel and promising source of noninvasive spider and insect DNA from spider webs. Using black widow spiders (Latrodectus spp.) fed with house crickets (Acheta domesticus), we successfully extracted, amplified, and sequenced mitochondrial DNA from spider web samples that identified both spider and prey to species. Detectability of spider DNA did not differ between assays with amplicon sizes from 135 to 497 base pairs. Spider and prey DNA remained detectable at least 88 days after living organisms were no longer present on the web. Spider web DNA as a proof-of-concept may open doors to other practical applications in conservation research, pest management, biogeography studies, and biodiversity assessments.

  4. Spider Web DNA: A New Spin on Noninvasive Genetics of Predator and Prey

    Science.gov (United States)

    Xu, Charles C. Y.; Yen, Ivy J.; Bowman, Dean; Turner, Cameron R.

    2015-01-01

    Noninvasive genetic sampling enables biomonitoring without the need to directly observe or disturb target organisms. This paper describes a novel and promising source of noninvasive spider and insect DNA from spider webs. Using black widow spiders (Latrodectus spp.) fed with house crickets (Acheta domesticus), we successfully extracted, amplified, and sequenced mitochondrial DNA from spider web samples that identified both spider and prey to species. Detectability of spider DNA did not differ between assays with amplicon sizes from 135 to 497 base pairs. Spider and prey DNA remained detectable at least 88 days after living organisms were no longer present on the web. Spider web DNA as a proof-of-concept may open doors to other practical applications in conservation research, pest management, biogeography studies, and biodiversity assessments. PMID:26606730

  5. Funnel-web spider bite

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    ... page: //medlineplus.gov/ency/article/002844.htm Funnel-web spider bite To use the sharing features on ... the effects of a bite from the funnel-web spider. Male funnel-web spiders are more poisonous ...

  6. Spider Spinning for Dummies

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    Bird, Richard S.

    Spider spinning is a snappy name for the problem of listing the ideals of a totally acyclic poset in such a way that each ideal is computed from its predecessor in constant time. Such an algorithm is said to be loopless. Our aim in these lectures is to show how to calculate a loopless algorithm for spider spinning. The calculation makes use of the fundamental laws of functional programming and the real purpose of the exercise is to show these laws in action.

  7. Mechanical behavior of silk during the evolution of orb-web spinning spiders.

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    Elices, Manuel; Plaza, Gustavo R; Arnedo, Miquel A; Pérez-Rigueiro, José; Torres, Fernando G; Guinea, Gustavo V

    2009-07-13

    The development of an accurate and reproducible approach to measuring the tensile behavior of spider silk has allowed characterizing and comparing the range of mechanical properties exhibited by different spider species with unprecedented detail. The comparison of silks spun by spiders belonging to different phylogenetic groups has revealed that evolution locked in many of the important properties of spider silks very early in the history of orb-web weaving spiders, despite the fact that the silk gland system is relatively isolated in physiological terms from the rest of the organism and should thus mutate quickly. The variations observed between species may be grouped in at least two patterns that are shown not to be related to phylogeny. Beyond the relevance of these results for the evolutionary biology of spiders and silks, the conservation of the basic traits observed in the mechanical behavior of spider silks is likely to set a limit to the range of properties that can be expected from artificial fibers bioinspired in natural silks.

  8. Spider's web inspires fibres for industry

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    Dacey, James

    2010-03-01

    Spiders may not be everybody's idea of natural beauty, but nobody can deny the artistry in the webs that they spin, especially when decorated with water baubles in the morning dew. Inspired by this spectacle, a group of researchers in China has mimicked the structural properties of the spider's web to create a fibre for industry that can manipulate water with the same skill and efficiency, writes James Dacey.

  9. Using Spider-Web Patterns To Determine Toxicity

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    Noever, David A.; Cronise, Raymond J.; Relwani, Rachna A.

    1995-01-01

    Method of determining toxicities of chemicals involves recording and analysis of spider-web patterns. Based on observation spiders exposed to various chemicals spin webs that differ, in various ways, from normal webs. Potential alternative to toxicity testing on higher animals.

  10. Reconstructing web evolution and spider diversification in the molecular era.

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    Blackledge, Todd A; Scharff, Nikolaj; Coddington, Jonathan A; Szüts, Tamas; Wenzel, John W; Hayashi, Cheryl Y; Agnarsson, Ingi

    2009-03-31

    The evolutionary diversification of spiders is attributed to spectacular innovations in silk. Spiders are unique in synthesizing many different kinds of silk, and using silk for a variety of ecological functions throughout their lives, particularly to make prey-catching webs. Here, we construct a broad higher-level phylogeny of spiders combining molecular data with traditional morphological and behavioral characters. We use this phylogeny to test the hypothesis that the spider orb web evolved only once. We then examine spider diversification in relation to different web architectures and silk use. We find strong support for a single origin of orb webs, implying a major shift in the spinning of capture silk and repeated loss or transformation of orb webs. We show that abandonment of costly cribellate capture silk correlates with the 2 major diversification events in spiders (1). Replacement of cribellate silk by aqueous silk glue may explain the greater diversity of modern orb-weaving spiders (Araneoidea) compared with cribellate orb-weaving spiders (Deinopoidea) (2). Within the "RTA clade," which is the sister group to orb-weaving spiders and contains half of all spider diversity, >90% of species richness is associated with repeated loss of cribellate silk and abandonment of prey capture webs. Accompanying cribellum loss in both groups is a release from substrate-constrained webs, whether by aerially suspended webs, or by abandoning webs altogether. These behavioral shifts in silk and web production by spiders thus likely played a key role in the dramatic evolutionary success and ecological dominance of spiders as predators of insects.

  11. Tangled in a sparse spider web

    DEFF Research Database (Denmark)

    Dimitrov, Dimitar Stefanov; Lopardo, Lara; Giribet, Gonzalo

    2012-01-01

    In order to study the tempo and the mode of spider orb web evolution and diversification, we conducted a phylogenetic analysis using six genetic markers along with a comprehensive taxon sample. The present analyses are the first to recover the monophyly of orb-weaving spiders based solely on DNA ...

  12. Application of 3 kinds of practical electromagnetic spiders in electromagnetic spider web

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    Jiang Min

    2016-01-01

    Full Text Available Electromagnetic spider web the launch circuit has introduced a lot, but in the center position of the utility of the spider generally have 3 kinds of circuits respectively, the use of single-chip microcomputer circuit of the low energy consumption spider by multi-channel transmission, single circuit receiver circuit. Direct use of the 3 channels of the spider and the use of PLC circuit spider, depending on the actual situation were placed.

  13. Prey interception drives web invasion and spider size determines successful web takeover in nocturnal orb-web spiders

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    Wenjin Gan

    2015-10-01

    Full Text Available A striking feature of web-building spiders is the use of silk to make webs, mainly for prey capture. However, building a web is energetically expensive and increases the risk of predation. To reduce such costs and still have access to abundant prey, some web-building spiders have evolved web invasion behaviour. In general, no consistent patterns of web invasion have emerged and the factors determining web invasion remain largely unexplored. Here we report web invasion among conspecifics in seven nocturnal species of orb-web spiders, and examined the factors determining the probability of webs that could be invaded and taken over by conspecifics. About 36% of webs were invaded by conspecifics, and 25% of invaded webs were taken over by the invaders. A web that was built higher and intercepted more prey was more likely to be invaded. Once a web was invaded, the smaller the size of the resident spider, the more likely its web would be taken over by the invader. This study suggests that web invasion, as a possible way of reducing costs, may be widespread in nocturnal orb-web spiders.

  14. Structural optimization of 3D-printed synthetic spider webs for high strength.

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    Qin, Zhao; Compton, Brett G; Lewis, Jennifer A; Buehler, Markus J

    2015-05-15

    Spiders spin intricate webs that serve as sophisticated prey-trapping architectures that simultaneously exhibit high strength, elasticity and graceful failure. To determine how web mechanics are controlled by their topological design and material distribution, here we create spider-web mimics composed of elastomeric filaments. Specifically, computational modelling and microscale 3D printing are combined to investigate the mechanical response of elastomeric webs under multiple loading conditions. We find the existence of an asymptotic prey size that leads to a saturated web strength. We identify pathways to design elastomeric material structures with maximum strength, low density and adaptability. We show that the loading type dictates the optimal material distribution, that is, a homogeneous distribution is better for localized loading, while stronger radial threads with weaker spiral threads is better for distributed loading. Our observations reveal that the material distribution within spider webs is dictated by the loading condition, shedding light on their observed architectural variations.

  15. Spinning gland transcriptomics from two main clades of spiders (order: Araneae--insights on their molecular, anatomical and behavioral evolution.

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    Francisco Prosdocimi

    Full Text Available Characterized by distinctive evolutionary adaptations, spiders provide a comprehensive system for evolutionary and developmental studies of anatomical organs, including silk and venom production. Here we performed cDNA sequencing using massively parallel sequencers (454 GS-FLX Titanium to generate ∼80,000 reads from the spinning gland of Actinopus spp. (infraorder: Mygalomorphae and Gasteracantha cancriformis (infraorder: Araneomorphae, Orbiculariae clade. Actinopus spp. retains primitive characteristics on web usage and presents a single undifferentiated spinning gland while the orbiculariae spiders have seven differentiated spinning glands and complex patterns of web usage. MIRA, Celera Assembler and CAP3 software were used to cluster NGS reads for each spider. CAP3 unigenes passed through a pipeline for automatic annotation, classification by biological function, and comparative transcriptomics. Genes related to spider silks were manually curated and analyzed. Although a single spidroin gene family was found in Actinopus spp., a vast repertoire of specialized spider silk proteins was encountered in orbiculariae. Astacin-like metalloproteases (meprin subfamily were shown to be some of the most sampled unigenes and duplicated gene families in G. cancriformis since its evolutionary split from mygalomorphs. Our results confirm that the evolution of the molecular repertoire of silk proteins was accompanied by the (i anatomical differentiation of spinning glands and (ii behavioral complexification in the web usage. Finally, a phylogenetic tree was constructed to cluster most of the known spidroins in gene clades. This is the first large-scale, multi-organism transcriptome for spider spinning glands and a first step into a broad understanding of spider web systems biology and evolution.

  16. Biomaterial evolution parallels behavioral innovation in the origin of orb-like spider webs.

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    Blackledge, Todd A; Kuntner, Matjaž; Marhabaie, Mohammad; Leeper, Thomas C; Agnarsson, Ingi

    2012-01-01

    Correlated evolution of traits can act synergistically to facilitate organism function. But, what happens when constraints exist on the evolvability of some traits, but not others? The orb web was a key innovation in the origin of >12,000 species of spiders. Orb evolution hinged upon the origin of novel spinning behaviors and innovations in silk material properties. In particular, a new major ampullate spidroin protein (MaSp2) increased silk extensibility and toughness, playing a critical role in how orb webs stop flying insects. Here, we show convergence between pseudo-orb-weaving Fecenia and true orb spiders. As in the origin of true orbs, Fecenia dragline silk improved significantly compared to relatives. But, Fecenia silk lacks the high compliance and extensibility found in true orb spiders, likely due in part to the absence of MaSp2. Our results suggest how constraints limit convergent evolution and provide insight into the evolution of nature's toughest fibers.

  17. Vibration transmission through sheet webs of hobo spiders (Eratigena agrestis) and tangle webs of western black widow spiders (Latrodectus hesperus).

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    Vibert, Samantha; Scott, Catherine; Gries, Gerhard

    2016-11-01

    Web-building spiders construct their own vibratory signaling environments. Web architecture should affect signal design, and vice versa, such that vibratory signals are transmitted with a minimum of attenuation and degradation. However, the web is the medium through which a spider senses both vibratory signals from courting males and cues produced by captured prey. Moreover, webs function not only in vibration transmission, but also in defense from predators and the elements. These multiple functions may impose conflicting selection pressures on web design. We investigated vibration transmission efficiency and accuracy through two web types with contrasting architectures: sheet webs of Eratigena agrestis (Agelenidae) and tangle webs of Latrodectus hesperus (Theridiidae). We measured vibration transmission efficiencies by playing frequency sweeps through webs with a piezoelectric vibrator and a loudspeaker, recording the resulting web vibrations at several locations on each web using a laser Doppler vibrometer. Transmission efficiencies through both web types were highly variable, with within-web variation greater than among-web variation. There was little difference in transmission efficiencies of longitudinal and transverse vibrations. The inconsistent transmission of specific frequencies through webs suggests that parameters other than frequency are most important in allowing these spiders to distinguish between vibrations of prey and courting males.

  18. Web orientation and prey resources for web-building spiders in eastern hemlock.

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    Mallis, Rachael E; Rieske, Lynne K

    2010-10-01

    We examined the arthropod community on eastern hemlock, Tsuga canadensis (L.) Carr, in the context of its role in providing potential prey items for hemlock-associated web-weaving spiders. Using sticky traps simulating spider webs, we evaluated what prey items are available to web-weaving spiders in eastern hemlock based on web orientation (horizontal versus vertical) and cardinal direction. We found that the overwhelming majority (>70%) of prey items available to spiders in hemlock canopies were Diptera. Psocoptera, Hymenoptera, and Hemiptera comprised most of the remaining potential prey. A significant direction × orientation interaction, and greater trap capture in some direction-orientation combinations, suggests that spiders might locate their webs in eastern hemlock canopies for thermoregulatory purposes, ultimately optimizing prey capture. We also evaluated these findings in the context of hemlock infestation by the invasive hemlock woolly adelgid, Adelges tsugae Annand. The adelgid is a sedentary insect with a mobile crawler stage that provides a readily available, easily obtained food source for predators in hemlock canopies. However, an abundance of alternative prey will affect within canopy spider distribution and the potential intensity with which spiders consume these prey. Understanding the response of spiders to potential prey availability is essential to understanding the trophic interactions involving these predators and their potential for influencing herbivore populations.

  19. Determination of PCDDs in spider webs: preliminary studies

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    Rybak Justyna

    2018-01-01

    Full Text Available The application of spider webs for determination of polichlorinated dibenzo-para-dioxins (PCDDs has been studied for the first time. The aim of the studies was to find out if spider webs are suitable for such examinations as it was proved in the previous research they are excellent indicators of air pollutants. Spiders are ubiquitous, thus collection of samples is easy and non-invasive. Studies were conducted within the city of Wrocław and surroundings, one of the biggest and at the same time heaviest polluted city in Poland. Five research sites have been chosen, where spider webs were collected after 60 days of continuous exposure time. Webs belonging to two genera Tegenaria sylvestris and Tegenaria ferruginea (family Agelenidae have been chosen as they are large and very dense, thus they are very suitable for such examinations. Webs were found to retain dioxins probably mainly by external exposure. These promising results should be continued and expanded in the future research.

  20. Optimal foraging, not biogenetic law, predicts spider orb web allometry.

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    Gregorič, Matjaž; Kiesbüy, Heine C; Lebrón, Shakira G Quiñones; Rozman, Alenka; Agnarsson, Ingi; Kuntner, Matjaž

    2013-03-01

    The biogenetic law posits that the ontogeny of an organism recapitulates the pattern of evolutionary changes. Morphological evidence has offered some support for, but also considerable evidence against, the hypothesis. However, biogenetic law in behavior remains underexplored. As physical manifestation of behavior, spider webs offer an interesting model for the study of ontogenetic behavioral changes. In orb-weaving spiders, web symmetry often gets distorted through ontogeny, and these changes have been interpreted to reflect the biogenetic law. Here, we test the biogenetic law hypothesis against the alternative, the optimal foraging hypothesis, by studying the allometry in Leucauge venusta orb webs. These webs range in inclination from vertical through tilted to horizontal; biogenetic law predicts that allometry relates to ontogenetic stage, whereas optimal foraging predicts that allometry relates to gravity. Specifically, pronounced asymmetry should only be seen in vertical webs under optimal foraging theory. We show that, through ontogeny, vertical webs in L. venusta become more asymmetrical in contrast to tilted and horizontal webs. Biogenetic law thus cannot explain L. venusta web allometry, but our results instead support optimization of foraging area in response to spider size.

  1. Comparing the rheology of native spider and silkworm spinning dope

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    Holland, C.; Terry, A. E.; Porter, D.; Vollrath, F.

    2006-11-01

    Silk production has evolved to be energetically efficient and functionally optimized, yielding a material that can outperform most industrial fibres, particularly in toughness. Spider silk has hitherto defied all attempts at reproduction, despite advances in our understanding of the molecular mechanisms behind its superb mechanical properties. Spun fibres, natural and man-made, rely on the extrusion process to facilitate molecular orientation and bonding. Hence a full understanding of the flow characteristics of native spinning feedstock (dope) will be essential to translate natural spinning to artificial silk production. Here we show remarkable similarity between the rheologies for native spider-dragline and silkworm-cocoon silk, despite their independent evolution and substantial differences in protein structure. Surprisingly, both dopes behave like typical polymer melts. This observation opens the door to using polymer theory to clarify our general understanding of natural silks, despite the many specializations found in different animal species.

  2. The Spider's Web: Creativity and Survival in Dynamic Balance.

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    Cohen, Bill

    2001-01-01

    The spider's web is presented as a model for Indigenous education and community transformation, grounded in Okanagan philosophy. Children are at the center and benefit from the influence of extended family and community. The model's relevance for language revitalization, cultural maintenance, and educational planning and assessment is discussed.…

  3. 46 SPIDER WEBS AS INDICATORS OF COBALT AND LEAD ...

    African Journals Online (AJOL)

    Spider webs were collected from the indoor and outdoor of 120 sampling sites of 10 zones of Kano. Municipality. The samples were analysed for .... from 120 sampling sites in 10 sampling zones of. Kano municipality. Each sampling zone ... London (Fergusson and Ryan, 1984); New Zealand. (Fergusson et al., 1986); Kano ...

  4. Research on Artificial Spider Web Model for Farmland Wireless Sensor Network

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    Jun Wang

    2018-01-01

    Full Text Available Through systematic analysis of the structural characteristics and invulnerability of spider web, this paper explores the possibility of combining the advantages of spider web such as network robustness and invulnerability with farmland wireless sensor network. A universally applicable definition and mathematical model of artificial spider web structure are established. The comparison between artificial spider web and traditional networks is discussed in detail. The simulation result shows that the networking structure of artificial spider web is better than that of traditional networks in terms of improving the overall reliability and invulnerability of communication system. A comprehensive study on the advantage characteristics of spider web has important theoretical and practical significance for promoting the invulnerability research of farmland wireless sensor network.

  5. Phylogenomics resolves a spider backbone phylogeny and rejects a prevailing paradigm for orb web evolution.

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    Bond, Jason E; Garrison, Nicole L; Hamilton, Chris A; Godwin, Rebecca L; Hedin, Marshal; Agnarsson, Ingi

    2014-08-04

    Spiders represent an ancient predatory lineage known for their extraordinary biomaterials, including venoms and silks. These adaptations make spiders key arthropod predators in most terrestrial ecosystems. Despite ecological, biomedical, and biomaterial importance, relationships among major spider lineages remain unresolved or poorly supported. Current working hypotheses for a spider "backbone" phylogeny are largely based on morphological evidence, as most molecular markers currently employed are generally inadequate for resolving deeper-level relationships. We present here a phylogenomic analysis of spiders including taxa representing all major spider lineages. Our robust phylogenetic hypothesis recovers some fundamental and uncontroversial spider clades, but rejects the prevailing paradigm of a monophyletic Orbiculariae, the most diverse lineage, containing orb-weaving spiders. Based on our results, the orb web either evolved much earlier than previously hypothesized and is ancestral for a majority of spiders or else it has multiple independent origins, as hypothesized by precladistic authors. Cribellate deinopoid orb weavers that use mechanically adhesive silk are more closely related to a diverse clade of mostly webless spiders than to the araneoid orb-weaving spiders that use adhesive droplet silks. The fundamental shift in our understanding of spider phylogeny proposed here has broad implications for interpreting the evolution of spiders, their remarkable biomaterials, and a key extended phenotype--the spider web. Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. Spider Silk Processing for Spidroin Recovery from Crossopriza Lyoni Web

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    Mohtar, J. A.; Ooi, W. L.; Yusuf, F.

    2018-03-01

    Spider silk is a potential biomaterial that can be used in various applications for its outstanding physicomechanical properties attributed by the spidroin composition. Efforts for commercializing spider silks have been mainly focused on the characterization of spidroins from the Entelegyne spiders for exceptional fibre construction. Hence, studies on silk proteins from the Haplogyne species remain neglected. The aim of this study is to isolate spidroin from Crossopriza lyoni web. Silk processing involved the pretreatment of fibres for the shell layer removal from the surface. A screening study was conducted to analyze the effect of temperature, incubation time and agitation speed on spidroin extraction using Ajisawa’s reagent by OFAT analysis followed by statistical optimization of the extraction process via RSM for maximal protein recovery. All parameters exerted significant effect on spidroin recovery (p<0.05) in which the maximum protein concentration (451.78 ± 0.110 µg/ml) was obtained at optimal condition of 70°C, 350 rpm and 1.25 hours. The discovery of spidroin from this study provides a basic platform for engineering spider silk to meet the demand for a variety of silk-based products in the near future.

  7.  “Spiders and Webs in American Literature”

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    Vincent Dussol

    2012-05-01

    Full Text Available From Jonathan Edwards to Jorie Graham, spiders are strikingly present in American literature. The purpose of this article is first to show how that theme may have become something of a national tradition as very different writers, all of them careful observers of aranae, answered one another through the years. It is very likely that the attention paid to spiders by American authors was increased by those Native American myths in which spiders are a central figure. More than occasionally, on the female side of the American counter-culture, especially among its feminist and lesbian exponents, simple activists and creative writers have harnessed the symbolic power invested in the spider by Native Americans.There may be deeper reasons accounting for American authors’ fascination with spiders. The country’s phobia of disunion is one; a nation of settlers’ acute consciousness of the precariousness of its occupation of the territory is another. In demonstrating outstanding skills for adjustment to unknown places, spiders epitomize a form of identity permanence. The predominantly positive character of spider symbols in American literature will occasionally be inverted. Following the national logic of checks and balances, any web covering the whole of the United States will tend to come under suspicion.This study ends with an inventory of cultural productions linked with spiders and webs and whose Americanness is yet to be clearly determined.De Jonathan Edwards à Jorie Graham, l’araignée apparaît dans un nombre frappant de textes littéraires américains. On a d’abord voulu tenter de montrer comment a pu se construire cette tradition thématique et faire la preuve que différents écrivains, réunis par un souci de l’observation, se sont répondus à travers elle. L’attention prêtée à l’araignée s’est certainement trouvée renforcée par les récits mythologiques des peuples premiers américains qui font de l’araignée une

  8. Web building and silk properties functionally covary among species of wolf spider.

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    Lacava, M; Camargo, A; Garcia, L F; Benamu, M; Santana, M; Fang, J; Wang, X; Blamires, S J

    2018-04-15

    While phylogenetic studies have shown covariation between the properties of spider major ampullate (MA) silk and web building, both spider webs and silks are highly plastic so we cannot be sure whether these traits functionally co-vary or just vary across environments that the spiders occupy. Since MaSp2-like proteins provide MA silk with greater extensibility, their presence is considered necessary for spider webs to effectively capture prey. Wolf spiders (Lycosidae) are predominantly non-web building, but a select few species build webs. We accordingly collected MA silk from two web building and six non-web building species found in semi-rural ecosystems in Uruguay to test whether the presence of MaSp2-like proteins (indicated by amino acid composition), silk mechanical properties, and silk nanostructures, were associated with web building across the group. The web building and non-web building species were from disparate subfamilies so we estimated a genetic phylogeny to perform appropriate comparisons. For all of the properties measured we found differences between web building and non-web building species. A phylogenetic regression model confirmed that web building and not phylogenetic inertia influences silk properties. Our study definitively showed an ecological influence over spider silk properties. We expect that the presence of the MaSp2-like proteins and the subsequent nanostructures improves the mechanical performance of silks within the webs. Our study furthers our understanding of spider web and silk co-evolution and the ecological implications of spider silk properties. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  9. Deer herbivory reduces web-building spider abundance by simplifying forest vegetation structure

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    Elizabeth J. Roberson

    2016-09-01

    Full Text Available Indirect ecological effects are a common feature of ecological systems, arising when one species affects interactions among two or more other species. We examined how browsing by white-tailed deer (Odocoileus virginianus indirectly affected the abundance and composition of a web-building spider guild through their effects on the structure of the ground and shrub layers of northern hardwood forests. We examined paired plots consisting of deer-free and control plots in the Allegheny Plateau region Pennsylvania and Northern Highlands region of Wisconsin. We recorded the abundance of seven types of webs, each corresponding to a family of web-building spiders. We quantified vegetation structure and habitat suitability for the spiders by computing a web scaffold availability index (WSAI at 0.5 m and 1.0 m above the ground. At Northern Highlands sites, we recorded prey availability. Spider webs were twice as abundant in deer-free plots compared to control plots, while WSAI was 7–12 times greater in deerfree plots. Prey availability was lower in deer-free plots. With the exception of funnel web-builders, all spider web types were significantly more abundant in deer-free plots. Both deer exclusion and the geographic region of plots were significant predictors of spider community structure. In closed canopy forests with high browsing pressure, the low density of tree saplings and shrubs provides few locations for web-building spiders to anchor webs. Recruitment of these spiders may become coupled with forest disturbance events that increase tree and shrub recruitment. By modifying habitat structure, deer appear to indirectly modify arthropod food web interactions. As deer populations have increased in eastern North America over the past several decades, the effects of deer on web-building spiders may be widespread.

  10. Is web oscillation in the orb-web spider Argiope lobata (Pallas, 1772)(Araneidae) an anti-predatory behaviour?

    DEFF Research Database (Denmark)

    Cedhagen, Tomas; Björklund, S.

    2007-01-01

    of the spider allow it to move the centre of gravity quickly, and thereby to oscillate. (2) The great elasticity and strength of its web allow the spider to control the oscillations so that slow movements are reduced to a minimum. (3) When it is oscillating. the eyes of a predator cannot accommodate to keep...

  11. Punctuated evolution of viscid silk in spider orb webs supported by mechanical behavior of wet cribellate silk

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    Piorkowski, Dakota; Blackledge, Todd A.

    2017-08-01

    The origin of viscid capture silk in orb webs, from cribellate silk-spinning ancestors, is a key innovation correlated with significant diversification of web-building spiders. Ancestral cribellate silk consists of dry nanofibrils surrounding a stiff, axial fiber that adheres to prey through van der Waals interactions, capillary forces, and physical entanglement. In contrast, viscid silk uses chemically adhesive aqueous glue coated onto a highly compliant and extensible flagelliform core silk. The extensibility of the flagelliform fiber accounts for half of the total work of adhesion for viscid silk and is enabled by water in the aqueous coating. Recent cDNA libraries revealed the expression of flagelliform silk proteins in cribellate orb-weaving spiders. We hypothesized that the presence of flagelliform proteins in cribellate silk could have allowed for a gradual shift in mechanical performance of cribellate axial silk, whose effect was masked by the dry nature of its adhesive. We measured supercontraction and mechanical performance of cribellate axial silk, in wet and dry states, for two species of cribellate orb web-weaving spiders to see if water enabled flagelliform silk-like performance. We found that compliance and extensibility of wet cribellate silk increased compared to dry state as expected. However, when compared to other silk types, the response to water was more similar to other web silks, like major and minor ampullate silk, than to viscid silk. These findings support the punctuated evolution of viscid silk mechanical performance.

  12. Magnetic susceptibility of spider webs as a proxy of airborne metal pollution.

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    Rachwał, Marzena; Rybak, Justyna; Rogula-Kozłowska, Wioletta

    2018-03-01

    The purpose of this pilot study was to test spider webs as a fast tool for magnetic biomonitoring of air pollution. The study involved the investigation of webs made by four types of spiders: Pholcus phalangioides (Pholcidae), Eratigena atrica and Agelena labirynthica (Agelenidae) and Linyphia triangularis (Linyphiidae). These webs were obtained from outdoor and indoor study sites. Compared to the clean reference webs, an increase was observed in the values of magnetic susceptibility in the webs sampled from both indoor and outdoor sites, which indicates contamination by anthropogenically produced pollution particles that contain ferrimagnetic iron minerals. This pilot study has demonstrated that spider webs are able to capture particulate matter in a manner that is equivalent to flora-based bioindicators applied to date (such as mosses, lichens, leaves). They also have additional advantages; for example, they can be generated in isolated clean habitats, and exposure can be monitored in indoor and outdoor locations, at any height and for any period of time. Moreover, webs are ubiquitous in an anthropogenic, heavily polluted environment, and they can be exposed throughout the year. As spider webs accumulate pollutants to which humans are exposed, they become a reliable source of information about the quality of the environment. Therefore, spider webs are recommended for magnetic biomonitoring of airborne pollution and for the assessment of the environment because they are non-destructive, low-cost, sensitive and efficient. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. The Lethal Toxin from Australian Funnel-Web Spiders Is Encoded by an Intronless Gene

    Science.gov (United States)

    Pineda, Sandy Steffany; Wilson, David; Mattick, John S.; King, Glenn F.

    2012-01-01

    Australian funnel-web spiders are generally considered the most dangerous spiders in the world, with envenomations from the Sydney funnel-web spider Atrax robustus resulting in at least 14 human fatalities prior to the introduction of an effective anti-venom in 1980. The clinical envenomation syndrome resulting from bites by Australian funnel-web spiders is due to a single 42-residue peptide known as δ-hexatoxin. This peptide delays the inactivation of voltage-gated sodium channels, which results in spontaneous repetitive firing and prolongation of action potentials, thereby causing massive neurotransmitter release from both somatic and autonomic nerve endings. Here we show that δ-hexatoxin from the Australian funnel-web spider Hadronyche versuta is produced from an intronless gene that encodes a prepropeptide that is post-translationally processed to yield the mature toxin. A limited sampling of genes encoding unrelated venom peptides from this spider indicated that they are all intronless. Thus, in distinct contrast to cone snails and scorpions, whose toxin genes contain introns, spiders may have developed a quite different genetic strategy for evolving their venom peptidome. PMID:22928020

  14. The lethal toxin from Australian funnel-web spiders is encoded by an intronless gene.

    Directory of Open Access Journals (Sweden)

    Sandy Steffany Pineda

    Full Text Available Australian funnel-web spiders are generally considered the most dangerous spiders in the world, with envenomations from the Sydney funnel-web spider Atrax robustus resulting in at least 14 human fatalities prior to the introduction of an effective anti-venom in 1980. The clinical envenomation syndrome resulting from bites by Australian funnel-web spiders is due to a single 42-residue peptide known as δ-hexatoxin. This peptide delays the inactivation of voltage-gated sodium channels, which results in spontaneous repetitive firing and prolongation of action potentials, thereby causing massive neurotransmitter release from both somatic and autonomic nerve endings. Here we show that δ-hexatoxin from the Australian funnel-web spider Hadronyche versuta is produced from an intronless gene that encodes a prepropeptide that is post-translationally processed to yield the mature toxin. A limited sampling of genes encoding unrelated venom peptides from this spider indicated that they are all intronless. Thus, in distinct contrast to cone snails and scorpions, whose toxin genes contain introns, spiders may have developed a quite different genetic strategy for evolving their venom peptidome.

  15. Web architecture alteration of the orb web weaving spider Metellina merianae (Araneae, Tetragnathidae induced by the parasitoid Megaetaira madida (Ichneumonidae, Polysphincta group

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    Korenko, Stanislav

    2016-09-01

    Full Text Available The polysphinctine wasp Megaetaira madida (Haliday, 1838 is a koinobiont ecto-parasitoid of spiders of the genus Metellina. Under the influence of the parasitoid’s final instar larva, the spider host M. merianae (Scopoli, 1763 built a three-dimensional web architecture, which differed considerably from the capturing orb web. The alteration of spider web behaviour induced by a parasitoid larva in this host-parasitoid pair is described for the first time.

  16. Spider webs as indicators of cobalt and lead pollution in Kano ...

    African Journals Online (AJOL)

    Spider webs were collected from the indoor and outdoor of 120 sampling sites of 10 zones of Kano Municipality. The samples were analysed for cobalt and lead by the use of ALPHA-4 model of Atomic Absorption Spectrophotometer (AAS). The analysis of the webs showed different levels of the metals in the indoor and ...

  17. Web-sharing Sociality and Cooperative Prey Capture in a Malagasy Spitting Spider (Araneae: Scytodidae)

    NARCIS (Netherlands)

    Miller, J.A.

    2006-01-01

    Web-sharing sociality and cooperative prey capture are reported for Scytodes socialis, sp. nov., a spitting spider discovered in a dry deciduous forest in Eastern Madagascar. Transect-based sampling was used to investigate colony demographics, estimate web volume and stratigraphic position, and

  18. Convergent evolution of behavior in an adaptive radiation of Hawaiian web-building spiders.

    Science.gov (United States)

    Blackledge, Todd A; Gillespie, Rosemary G

    2004-11-16

    Species in ecologically similar habitats often display patterns of divergence that are strikingly comparable, suggesting that natural selection can lead to predictable evolutionary change in communities. However, the relative importance of selection as an agent mediating in situ diversification, versus dispersal between habitats, cannot be addressed without knowledge of phylogenetic history. We used an adaptive radiation of spiders within the Hawaiian Islands to test the prediction that species of spiders on different islands would independently evolve webs with similar architectures. Tetragnatha spiders are the only nocturnal orb-weaving spiders endemic to the Hawaiian archipelago, and multiple species of orb-weaving Tetragnatha co-occur within mesic and wet forest habitats on each of the main islands. Therefore, comparison of web architectures spun by spiders on different islands allowed study of replicated evolutionary events of past behavioral diversification. We found that species within each island construct webs with architectures that differ from one another. However, pairs of species on different islands, "ethotypes," share remarkable similarities in web architectures. Phylogenetic analysis demonstrated that the species comprising these ethotypes evolved independent of one another. Our study illustrates the high degree of predictability that can be exhibited by the evolutionary diversification of complex behaviors. However, not all web architectures were shared between islands, demonstrating that unique effects also have played an important role in the historical diversification of behavior.

  19. How did the spider cross the river? Behavioral adaptations for river-bridging webs in Caerostris darwini (Araneae: Araneidae.

    Directory of Open Access Journals (Sweden)

    Matjaž Gregorič

    Full Text Available Interspecific coevolution is well described, but we know significantly less about how multiple traits coevolve within a species, particularly between behavioral traits and biomechanical properties of animals' "extended phenotypes". In orb weaving spiders, coevolution of spider behavior with ecological and physical traits of their webs is expected. Darwin's bark spider (Caerostris darwini bridges large water bodies, building the largest known orb webs utilizing the toughest known silk. Here, we examine C. darwini web building behaviors to establish how bridge lines are formed over water. We also test the prediction that this spider's unique web ecology and architecture coevolved with new web building behaviors.We observed C. darwini in its natural habitat and filmed web building. We observed 90 web building events, and compared web building behaviors to other species of orb web spiders.Caerostris darwini uses a unique set of behaviors, some unknown in other spiders, to construct its enormous webs. First, the spiders release unusually large amounts of bridging silk into the air, which is then carried downwind, across the water body, establishing bridge lines. Second, the spiders perform almost no web site exploration. Third, they construct the orb capture area below the initial bridge line. In contrast to all known orb-weavers, the web hub is therefore not part of the initial bridge line but is instead built de novo. Fourth, the orb contains two types of radial threads, with those in the upper half of the web doubled. These unique behaviors result in a giant, yet rather simplified web. Our results continue to build evidence for the coevolution of behavioral (web building, ecological (web microhabitat and biomaterial (silk biomechanics traits that combined allow C. darwini to occupy a unique niche among spiders.

  20. Degree of Biomimicry of Artificial Spider Silk Spinning Assessed by NMR Spectroscopy.

    Science.gov (United States)

    Otikovs, Martins; Andersson, Marlene; Jia, Qiupin; Nordling, Kerstin; Meng, Qing; Andreas, Loren B; Pintacuda, Guido; Johansson, Jan; Rising, Anna; Jaudzems, Kristaps

    2017-10-02

    Biomimetic spinning of artificial spider silk requires that the terminal domains of designed minispidroins undergo specific structural changes in concert with the β-sheet conversion of the repetitive region. Herein, we combine solution and solid-state NMR methods to probe domain-specific structural changes in the NT2RepCT minispidroin, which allows us to assess the degree of biomimicry of artificial silk spinning. In addition, we show that the structural effects of post-spinning procedures can be examined. By studying the impact of NT2RepCT fiber drying, we observed a reversible beta-to-alpha conversion. We think that this approach will be useful for guiding the optimization of artificial spider silk fibers. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Predator perception of detritus and eggsac decorations spun by orb-web spiders Cyclosa octotuberculata: Do they function to camouflage the spiders?

    Directory of Open Access Journals (Sweden)

    Wenjin GAN, Fengxiang LIU, Zengtao ZHANG, Daiqin LI

    2010-06-01

    Full Text Available Camouflage is one of the most widespread and powerful strategies that animals use to make detection/recognition more difficult. Many orb-web spiders of the genus Cyclosa add prey remains, plant debris, moults, and/or eggsacs to their webs called web decorations. Web decorations resembling spider body colour pattern have been considered to camouflage the spider from predators. While this camouflage is obvious from a human’s perspective, it has rarely been investigated from a predator’s perspective. In this study, we tested the visibility of web decorations by calculating chromatic and achromatic contrasts of detritus and eggsac decorations built by Cyclosa octotuberculata, against four different backgrounds viewed by both bird (e.g., blue tits and hymenopteran (e.g. wasps predators. We showed that both juvenile and adult spiders on webs with detritus or egg-sac decorations were undetectable by both hymenopteran and bird predators over short and long distances. Our results thus suggest that decorating webs with detritus or eggsacs by C. octotuberculata may camouflage the spider from both hymenopteran and bird predators in their common habitats [Current Zoology 56 (3: 379–387, 2010].

  2. Spiders and Worms and Crawlers, Oh My: Searching on the World Wide Web.

    Science.gov (United States)

    Eagan, Ann; Bender, Laura

    Searching on the world wide web can be confusing. A myriad of search engines exist, often with little or no documentation, and many of these search engines work differently from the standard search engines people are accustomed to using. Intended for librarians, this paper defines search engines, directories, spiders, and robots, and covers basics…

  3. Uncovering changes in spider orb-web topology owing to aerodynamic effects.

    Science.gov (United States)

    Zaera, Ramón; Soler, Alejandro; Teus, Jaime

    2014-09-06

    An orb-weaving spider's likelihood of survival is influenced by its ability to retain prey with minimum damage to its web and at the lowest manufacturing cost. This set of requirements has forced the spider silk to evolve towards extreme strength and ductility to a degree that is rare among materials. Previous studies reveal that the performance of the web upon impact may not be based on the mechanical properties of silk alone, aerodynamic drag could play a role in the dissipation of the prey's energy. Here, we present a thorough analysis of the effect of the aerodynamic drag on wind load and prey impact. The hypothesis considered by previous authors for the evaluation of the drag force per unit length of thread has been revisited according to well-established principles of fluid mechanics, highlighting the functional dependence on thread diameter that was formerly ignored. Theoretical analysis and finite-element simulations permitted us to identify air drag as a relevant factor in reducing deterioration of the orb web, and to reveal how the spider can take greater-and not negligible-advantage of drag dissipation. The study shows the beneficial air drag effects of building smaller and less dense webs under wind load, and larger and denser webs under prey impact loads. In essence, it points out why the aerodynamics need to be considered as an additional driving force in the evolution of silk threads and orb webs. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  4. Molecular studies of a novel dragline silk from a nursery web spider, Euprosthenops sp. (Pisauridae).

    Science.gov (United States)

    Pouchkina-Stantcheva, Natalia N; McQueen-Mason, Simon J

    2004-08-01

    Various spider species produce dragline silks with different mechanical properties. The primary structure of silk proteins is thought to contribute to the elasticity and strength of the fibres. Previously published work has demonstrated that the dragline silk of Euprosthenops sp. is stiffer then comparable silk of Nephila edulis, Araneus diadematus and Latrodectus mactans. Our studies of Euprosthenops dragline silk at the molecular level have revealed that nursery web spider fibroin has the highest polyalanine content among previously characterised silks and this is likely to contribute to the superior qualities of pisaurid dragline.

  5. Towards rationalisation of antivenom use in funnel-web spider envenoming: enzyme immunoassays for venom concentrations.

    Science.gov (United States)

    Miller, Mark; O'Leary, Margaret A; Isbister, Geoffrey K

    2016-03-01

    Funnel-web spider (Atrax and Hadronyche spp.) envenoming is rare but causes severe neuromuscular, autonomic, and cardiac effects. A rabbit-derived IgG antivenom is available, but venom detection in patients has not been reported. To use serial venom and antivenom concentrations to better define envenoming and antivenom effectiveness. Serum was collected from nine patients with suspected funnel-web spider bites and clinical effects were recorded. Venom-specific enzyme immunoassays were developed to measure funnel-web spider venom and antivenom concentrations. Goat anti-rabbit whole serum was coupled to UltraLink resin and added to samples to remove bound venom and measure free venom. Antivenom efficacy was defined as antivenom binding all free venom and antivenom effectiveness as resolution of clinical features. Venom was detectable in samples from six of nine patients. In three patients without venom detected, there were only moderate effects, which did not completely respond to antivenom in all cases and no spider was identified. In five of six cases, a male Atrax spp. (Sydney funnel-web) spider was identified. Three patients had moderate envenoming which responded to antivenom. Three patients had severe envenoming and developed catecholamine-induced myocarditis and acute pulmonary oedema. Although cholinergic and non-specific clinical features appeared to respond to antivenom, myocarditis and pulmonary oedema lasted 2-4 days. Median venom concentration pre-antivenom in five patients with samples was 5.6 ng/ml (3-35 ng/ml), and immediately post-antivenom decreased to a median of 0 ng/ml (0-1.8 ng/ml). Post-antivenom venom concentrations decreased when bound venom was removed; median, 0 ng/ml (0-0.9 ng/ml), indicating that most venom detected post-antivenom was bound. There was recurrence of venom and clinical features in one patient when a pressure bandage was removed. Detection of venom in suspected funnel-web spider bites identified definite cases with

  6. Cerebrospinal fluid indices in cryptococcal and tuberculous meningitis: the spider web coagulum and its diagnostic significance.

    Science.gov (United States)

    Staib, F; Seibold, M; Antweiler, E; Zimmer, C; Heitz, J; Stoltenburg-Didinger, G

    1990-01-01

    The differentiation between a chronic cryptococcal meningitis and a chronic tuberculous meningitis may cause problems for the clinician only if standard microbiological methods are not applied to the diagnosis of both infections. In a male non-AIDS patient (50 y), 11 years after a suggested diagnosis of "tuberculous meningitis", meningoencephalitis with hydrocephalus was diagnosed and treated accordingly without success. Mycobacterium tuberculosis was never found. Because fibrin fibres of a spider web coagulum in the CSF resembled Aspergillus mycelium, the patient was then treated with amphotericin B + flucytosine. Finally, a mycological examination led to the true diagnosis: (1) In the CSF, resembling Aspergillus hyphae were found to be spider web coagulum fibres. (2) Cryptococcal meningoencephalitis based on the detection of Cryptococcus neoformans in CSF and its antigen in serum and CSF. - At post-mortem, cryptococcal meningoencephalitis was established as cause of death. Residual signs of tuberculosis could not be detected in the brain and the meninges. Common clinical similarities of cryptococcal and tuberculous meningitis and the possibility of a double infection are discussed. A comparison of the presence of Cr. neoformans in the meninges of non-AIDS and AIDS patients is made. The formation of spider web coagulum in the CSF is discussed. Proposals for the diagnosis, therapy and prophylaxis of cryptococcal meningitis are made.

  7. The effect of colour polymorphism on thermoregulation in an orb web spider

    Science.gov (United States)

    Rao, Dinesh; Mendoza-Cuenca, Luis

    2016-08-01

    Spiders that build aerial webs in open areas face the risk of overheating due to incident solar radiation. These spiders can counteract overheating by either moving the web to another site or by adopting behavioural thermoregulation within the web. Since moving can be costly, studies have suggested that a passive but effective method of reducing heat load is by light reflectance through body colouration. We explored the interaction between colour and thermoregulation in a colour polymorphic species, under both field and laboratory conditions. We show that in natural conditions, the spiders maintain their body temperature below that of the ambient, but with no difference in surface temperature between colour morphs. In laboratory experiments with internal temperature measurements, white morphs bore the risk of overheating better than the yellow morphs since they heated up slower and cooled faster. We suggest that the thermoregulatory properties of colour polymorphism in Verrucosa arenata have physiological consequences and may play an important role in the maintenance of colour polymorphism in this species.

  8. Multiple model mimicry and feeding behavior of the spider web-inhabiting damsel bug, Arachnocoris berytoides Uhler (Hemiptera: Nabidae), from Puerto Rico

    Science.gov (United States)

    Javier E. Mercado; Jorge A. Santiago-Blay

    2015-01-01

    The Neotropical genus, Arachnocoris Scott groups thirteen species of specialized spider web-inhabiting damsel bugs (Nabidae) distributed from Panama to Brazil and the West Indies. We present new information on the web behavior of A. berytoides Uhler from Puerto Rico. Three different life stages were observed on the spider webs, suggesting this species likely depends on...

  9. The great silk alternative: multiple co-evolution of web loss and sticky hairs in spiders.

    Science.gov (United States)

    Wolff, Jonas O; Nentwig, Wolfgang; Gorb, Stanislav N

    2013-01-01

    Spiders are the most important terrestrial predators among arthropods. Their ecological success is reflected by a high biodiversity and the conquest of nearly every terrestrial habitat. Spiders are closely associated with silk, a material, often seen to be responsible for their great ecological success and gaining high attention in life sciences. However, it is often overlooked that more than half of all Recent spider species have abandoned web building or never developed such an adaptation. These species must have found other, more economic solutions for prey capture and retention, compensating the higher energy costs of increased locomotion activity. Here we show that hairy adhesive pads (scopulae) are closely associated with the convergent evolution of a vagrant life style, resulting in highly diversified lineages of at least, equal importance as the derived web building taxa. Previous studies often highlighted the idea that scopulae have the primary function of assisting locomotion, neglecting the fact that only the distal most pads (claw tufts) are suitable for those purposes. The former observations, that scopulae are used in prey capture, are largely overlooked. Our results suggest the scopulae evolved as a substitute for silk in controlling prey and that the claw tufts are, in most cases, a secondary development. Evolutionary trends towards specialized claw tufts and their composition from a low number of enlarged setae to a dense array of slender ones, as well as the secondary loss of those pads are discussed further. Hypotheses about the origin of the adhesive setae and their diversification throughout evolution are provided.

  10. Host specificity and temporal and seasonal shifts in host preference of a web-spider parasitoid Zatypota percontatoria.

    Science.gov (United States)

    Korenko, Stanislav; Michalková, Veronika; Zwakhals, Kees; Pekár, Stano

    2011-01-01

    Current knowledge about polysphinctine parasite wasps' interactions with their spider hosts is very fragmented and incomplete. This study presents the host specificity of Zatypota percontatoria (Müller) (Hymenoptera: Ichneumonidae) and its adaptation to varying host availability. Two years of field observations show that Z. percontatoria is a stenophagous parasitoid that parasitizes only five closely related web-building spiders of the family Theridiidae (Araneae). Within the Theridiidae it attacks only species belonging to a small group of species, here called the "Theridion" group. These hosts have a similar biology, but are available at different levels of abundance and at different sizes over the season. Laboratory experiments showed that this wasp species ignores linyphiid, araneid or dictynid spiders and accepts only theridiid spiders of the "Theridion" group. In the field study, wasp females preferred older juvenile and sub-adult female spider instars with intermediate body size. Only 5% of the parasitized spiders were males. Parasitism in the natural population of theridiid spiders was on average 1.3%. Parasitism was most frequent on two species, Theridion varians Hahn in 2007 and Neottiura bimaculata Linnaeus in 2008. The parasitization rate was positively correlated with spider abundance. The wasp responded adaptively to seasonal changes in host abundance and host body size and shifted host preference according to the availability of suitable hosts during, as well as between, seasons. In spring and summer the highest percentage of parasitism was on T. varians and in autumn it was on N. bimaculata.

  11. Quantifying Human Visible Color Variation from High Definition Digital Images of Orb Web Spiders.

    Directory of Open Access Journals (Sweden)

    Horacio Tapia-McClung

    Full Text Available Digital processing and analysis of high resolution images of 30 individuals of the orb web spider Verrucosa arenata were performed to extract and quantify human visible colors present on the dorsal abdomen of this species. Color extraction was performed with minimal user intervention using an unsupervised algorithm to determine groups of colors on each individual spider, which was then analyzed in order to quantify and classify the colors obtained, both spatially and using energy and entropy measures of the digital images. Analysis shows that the colors cover a small region of the visible spectrum, are not spatially homogeneously distributed over the patterns and from an entropic point of view, colors that cover a smaller region on the whole pattern carry more information than colors covering a larger region. This study demonstrates the use of processing tools to create automatic systems to extract valuable information from digital images that are precise, efficient and helpful for the understanding of the underlying biology.

  12. Female genital mutilation and monandry in an orb-web spider.

    Science.gov (United States)

    Nakata, Kensuke

    2016-02-01

    Monandry, in which a female has only one mating partner during the reproductive period, is established when a female spontaneously refrains from re-mating, or when a partner male interferes with the attempts of a female to mate again. In the latter case, however, females often have countermeasures against males, which may explain why polyandry is ubiquitous. Here, I demonstrate that the genital appendage, or scape, of the female orb-web spider (Cyclosa argenteoalba) is injured after her first mating, possibly by her first male partner. This female genital mutilation (FGM) permanently precludes copulation, and females appear to have no countermeasures. FGM is considered to confer a strong advantage to males in sexual conflicts over the number of female matings, and it may widely occur in spiders. © 2016 The Author(s).

  13. Host Specificity and Temporal and Seasonal Shifts in Host Preference of a Web-Spider Parasitoid Zatypota percontatoria

    OpenAIRE

    Korenko, Stanislav; Michalková, Veronika; Zwakhals, Kees; Pekár, Stano

    2011-01-01

    Current knowledge about polysphinctine parasite wasps' interactions with their spider hosts is very fragmented and incomplete. This study presents the host specificity of Zatypota percontatoria (Müller) (Hymenoptera: Ichneumonidae) and its adaptation to varying host availability. Two years of field observations show that Z. percontatoria is a stenophagous parasitoid that parasitizes only five closely related web-building spiders of the family Theridiidae (Araneae). Within the Theridiidae it a...

  14. The Use of Spider Webs as Passive Bioaerosol Collectors

    Science.gov (United States)

    2009-03-01

    water, released to water effluents , and sludge used in agriculture as fertilizer. Due to political and economic constraints, Waste Water Treatment...particulates, caused by shifts in environmental conditions, may cause coagulation and increase deposition rates of bioaerosols [29]. Dry weather...environments and geographical settings, their collection is highly inexpensive, and their constant regeneration allows the webs to become, in

  15. Mercury bioaccumulation, speciation, and influence on web structure in orb-weaving spiders from a forested watershed.

    Science.gov (United States)

    Wyman, Katherine E; Rodenhouse, Nicholas L; Bank, Michael S

    2011-08-01

    Atmospheric deposition is an important source of Hg in remote terrestrial ecosystems of northeastern North America. As high-level invertebrate consumers, orb-weaving spiders (family Araneidae) are excellent subjects for studying the impact of sublethal levels of Hg on forest animals because their webs provide snapshots of behavior and neurological function. Spiders of the diadematus group of the genus Araneus were collected from the Jeffers Brook watershed in the White Mountain National Forest, New Hampshire (USA), and analyzed for Hg content. Webs were photographed and measured to test for correlations between Hg body burden and web structure. Collected spiders contained concentrations of total Hg averaging 44.7 ± 10.0 ng/g Hg (wet mass; mean ± standard deviation), with 37 ± 6% of the total Hg present in the methylmercury form. Mercury loads were likely accumulated through diet (potential prey items contained an average of 43% of the Hg load in collected spiders) and possibly web ingestion. The present study found no direct evidence that the web structure-and thus the prey-capture ability-of spiders in the study area was affected by their Hg body burden. Copyright © 2011 SETAC.

  16. Characterization of insecticidal peptides from venom Australian funnel-web spiders

    Directory of Open Access Journals (Sweden)

    E. J. Vonorax

    2006-04-01

    Full Text Available Australian funnel-web spiders are relatively large primitive hunting spiders. Male Atrax robustus spiders have been responsible for a number of human deaths. Venom was collected from the species Hadronyche infensa (Hickman [female], H. formidabilis [male and female], H. versuta [female], and A. robustus (Cambridge [male] and was fractionated by high performance liquid chromatography. This resulted in the isolation and purification of a homologous series of 7 insecticidal peptides of relatively low molecular mass (approximately 4kDa. The amino acid sequences of these toxins consisted of 36 or 37 amino acids and were named atracotoxins. For the major bioassay of these toxins, we used the cotton bollworm, Helicoverpa armigera (Hubner, due to the great damage it causes to crops worldwide. These toxins, when injected subcutaneously into fifth or sixth instar larvae of Helicoverpa armigera,were lethal or caused an apparently irreversible writhing. The toxin from H. versuta venom showed no significant toxicity when subcutaneously injected into newborn mice. One of the toxins was found to have a free acid carboxyl terminus. These toxins have great potential as lead compounds for insecticide design or for incorporation in recombinant baculovirus insecticides.

  17. Effect of phenology on agonistic competitive interactions between invasive and native sheet-web spiders

    Science.gov (United States)

    Houser, Jeremy D.; Porter, Adam H.; Ginsberg, Howard; Jakob, Elizabeth M.

    2016-01-01

    The phenologies of introduced relative to native species can greatly influence the degree and symmetry of competition between them. The European spider Linyphia triangularis (Clerck, 1757) (Linyphiidae) reaches very high densities in coastal Maine (USA). Previous studies suggest thatL. triangularis negatively affects native linyphiid species, with competition for webs as one mechanism. We documented phenological differences between L. triangularis and three native species that illustrate the potential for the reversal of size-based competitive advantage over the course of the year. To test whether relative size influences interaction outcome, we allowed a resident spider to build a web and then introduced an intruder. We examined whether the outcomes of agonistic interactions over the webs were influenced by the species of the resident (invasive or native), the relative size of the contestants, and the species × size interaction. We found that the importance of relative size differed among species. In interactions between L. triangularis and each of two native species, size played a greater role than resident species on the outcome of interactions, suggesting that competitive advantage reverses over the season based on phenology-related size differences. Linyphia triangularis had a negative impact on the third species regardless of relative size.

  18. Metacommunity composition of web-spiders in a fragmented neotropical forest: relative importance of environmental and spatial effects.

    Directory of Open Access Journals (Sweden)

    Ronei Baldissera

    Full Text Available The distribution of beta diversity is shaped by factors linked to environmental and spatial control. The relative importance of both processes in structuring spider metacommunities has not yet been investigated in the Atlantic Forest. The variance explained by purely environmental, spatially structured environmental, and purely spatial components was compared for a metacommunity of web spiders. The study was carried out in 16 patches of Atlantic Forest in southern Brazil. Field work was done in one landscape mosaic representing a slight gradient of urbanization. Environmental variables encompassed plot- and patch-level measurements and a climatic matrix, while principal coordinates of neighbor matrices (PCNMs acted as spatial variables. A forward selection procedure was carried out to select environmental and spatial variables influencing web-spider beta diversity. Variation partitioning was used to estimate the contribution of pure environmental and pure spatial effects and their shared influence on beta-diversity patterns, and to estimate the relative importance of selected environmental variables. Three environmental variables (bush density, land use in the surroundings of patches, and shape of patches and two spatial variables were selected by forward selection procedures. Variation partitioning revealed that 15% of the variation of beta diversity was explained by a combination of environmental and PCNM variables. Most of this variation (12% corresponded to pure environmental and spatially environmental structure. The data indicated that (1 spatial legacy was not important in explaining the web-spider beta diversity; (2 environmental predictors explained a significant portion of the variation in web-spider composition; (3 one-third of environmental variation was due to a spatial structure that jointly explains variation in species distributions. We were able to detect important factors related to matrix management influencing the web-spider

  19. Spider phylogenomics: untangling the Spider Tree of Life

    Directory of Open Access Journals (Sweden)

    Nicole L. Garrison

    2016-02-01

    Full Text Available Spiders (Order Araneae are massively abundant generalist arthropod predators that are found in nearly every ecosystem on the planet and have persisted for over 380 million years. Spiders have long served as evolutionary models for studying complex mating and web spinning behaviors, key innovation and adaptive radiation hypotheses, and have been inspiration for important theories like sexual selection by female choice. Unfortunately, past major attempts to reconstruct spider phylogeny typically employing the “usual suspect” genes have been unable to produce a well-supported phylogenetic framework for the entire order. To further resolve spider evolutionary relationships we have assembled a transcriptome-based data set comprising 70 ingroup spider taxa. Using maximum likelihood and shortcut coalescence-based approaches, we analyze eight data sets, the largest of which contains 3,398 gene regions and 696,652 amino acid sites forming the largest phylogenomic analysis of spider relationships produced to date. Contrary to long held beliefs that the orb web is the crowning achievement of spider evolution, ancestral state reconstructions of web type support a phylogenetically ancient origin of the orb web, and diversification analyses show that the mostly ground-dwelling, web-less RTA clade diversified faster than orb weavers. Consistent with molecular dating estimates we report herein, this may reflect a major increase in biomass of non-flying insects during the Cretaceous Terrestrial Revolution 125–90 million years ago favoring diversification of spiders that feed on cursorial rather than flying prey. Our results also have major implications for our understanding of spider systematics. Phylogenomic analyses corroborate several well-accepted high level groupings: Opisthothele, Mygalomorphae, Atypoidina, Avicularoidea, Theraphosoidina, Araneomorphae, Entelegynae, Araneoidea, the RTA clade, Dionycha and the Lycosoidea. Alternatively, our results

  20. Behavioural analysis of web building anomalies in the orb-weaving spider Zygiella x-notata (Araneae, Araneidae

    Directory of Open Access Journals (Sweden)

    Toscani, Camille

    2012-07-01

    Full Text Available Among animal constructions, spider’s orb webs represent regular geometrical architecture models. Their construction is the result of successive, simple and reproducible behavioural patterns, often considered as stereotyped. It has recently been shown that spider’s building behaviours vary, which can alter web regularity. The final capture spiral results from the laying of successive threads between two radii, here termed ‘spiral units’. We defined a theoretical normal web, as a web in which each turn of the final spiral should be parallel to the preceding one. Weaving of the spiral units sometimes leads to anomalies in the orb web. Anomalies were identified and analysed in the orb-weaving spider Zygiella x-notata (Clerck, 1757. From video recordings of web construction, we noted the displacements of the legs and of the abdomen of the spider. We compared the frequency of displacements, and their duration, between the construction of spiral units that produce a normal turn and ones that produce an anomalous turn. The position of the legs on the web’s threads was also analysed. Results showed that anomalies were not the consequences of a modification in activity but more likely the result of the position on the radii of the fourth leg. These results suggest that spiders use local information to build the final capture spiral.

  1. Relationship between the ability to penetrate complex webs of Tetranychus spider mites and the ability of thread-cutting behavior in phytoseiid predatory mites

    NARCIS (Netherlands)

    Shimoda, T.; Kishimoto, H.; Takabayashi, J.; Amano, H.; Dicke, M.

    2010-01-01

    Predatory mites, that are important natural enemies of Tetranychus spider mites, are less hindered by complex webs of the spider mites than are other predatory mites that are natural enemies of other pest herbivores. This can be partly explained by their chaetotaxy, a morphological protection

  2. Urban Poor community Access to reproductive Health care in Surabaya. An Equity Analysis Using Spider Web

    Directory of Open Access Journals (Sweden)

    Ernawaty Ernawaty

    2015-01-01

    Full Text Available background:Poverty in urban area triggered new problem related with their access to health care services. Heavy burden of life in urban makes health, especially reproductive health, never become first priority for urban poor community. This study is aimed to analyzed equity of urban poor community when accessing the reproductive health care. Methods:This is descriptive study with cross sectional design applied. There were 78 women residents of Penjaringansari II Flats in Surabaya selected by simple random sampling (α=10% as respondents. Penjaringansari II Flats was choosen because it is a slum area that residence by unskilled labours and odd employees. The need fulfillment of respondents in reproductive health care was analyzed by spider web analysis. result: Most of respondents (55.1% were first married before 20 years old. There were 60.5% of them gave birth before 20 years old also, so it belongs to high risk pregnant women. Spider web area for health care of under age married was less than ideal age married which means that under age married urban poor experienced inequity for ANC health services. Approximately 10.3% of respondents had never use contraceptives because they fear of side effects and inhibiton of their husband. conclutions:Better equity shown in the prevention of cervical cancer. Being perceived as the poor who need assistance, free pap smear was often held by Penjaringansari II residents. Poor conditions experienced by a group not only can promote health care inequity, but also promote health care equity. recomendation:Health care equity for urban poor can be pursued through both aid schemes provided by the community or the government.

  3. Effects of prey macronutrient content on body composition and nutrient intake in a web-building spider.

    Directory of Open Access Journals (Sweden)

    Jesse Hawley

    Full Text Available The nutritional composition of diets can vary widely in nature and have large effects on the growth, reproduction and survival of animals. Many animals, especially herbivores, will tightly regulate the nutritional composition of their body, which has been referred to as nutritional homeostasis. We tested how experimental manipulation of the lipid and protein content of live prey affected the nutrient reserves and subsequent diet regulation of web-building spiders, Argiope keyserlingi. Live locusts were injected with experimental solutions containing specific amounts of lipid and protein and then fed to spiders. The nutrient composition of the spiders' bodies was directly related to the nutrient composition of the prey on which they fed. We then conducted an experiment where spiders were fed either high lipid or high protein prey and subsequently provided with two large unmanipulated locusts. Prior diet did not affect the amount or ratio of lipid and protein ingested by spiders when feeding on unmanipulated prey. Argiope keyserlingi were flexible in the storage of lipid and protein in their bodies and did not bias their extraction of nutrients from prey to compensate for previously biased diets. Some carnivores, especially those that experience frequent food limitation, may be less likely to strictly regulate their body composition than herbivores because food limitation may encourage opportunistic ingestion and assimilation of nutrients.

  4. Effects of prey macronutrient content on body composition and nutrient intake in a web-building spider.

    Science.gov (United States)

    Hawley, Jesse; Simpson, Stephen J; Wilder, Shawn M

    2014-01-01

    The nutritional composition of diets can vary widely in nature and have large effects on the growth, reproduction and survival of animals. Many animals, especially herbivores, will tightly regulate the nutritional composition of their body, which has been referred to as nutritional homeostasis. We tested how experimental manipulation of the lipid and protein content of live prey affected the nutrient reserves and subsequent diet regulation of web-building spiders, Argiope keyserlingi. Live locusts were injected with experimental solutions containing specific amounts of lipid and protein and then fed to spiders. The nutrient composition of the spiders' bodies was directly related to the nutrient composition of the prey on which they fed. We then conducted an experiment where spiders were fed either high lipid or high protein prey and subsequently provided with two large unmanipulated locusts. Prior diet did not affect the amount or ratio of lipid and protein ingested by spiders when feeding on unmanipulated prey. Argiope keyserlingi were flexible in the storage of lipid and protein in their bodies and did not bias their extraction of nutrients from prey to compensate for previously biased diets. Some carnivores, especially those that experience frequent food limitation, may be less likely to strictly regulate their body composition than herbivores because food limitation may encourage opportunistic ingestion and assimilation of nutrients.

  5. Dispatch from the field: ecology of ground-web-building spiders with description of a new species (Araneae, Symphytognathidae

    Directory of Open Access Journals (Sweden)

    Jeremy Miller

    2014-03-01

    Full Text Available Crassignatha danaugirangensis sp. n. (Araneae: Symphytognathidae was discovered during a tropical ecology field course held at the Danau Girang Field Centre in Sabah, Malaysia. A taxonomic description and accompanying ecological study were completed as course activities. To assess the ecology of this species, which belongs to the ground-web-building spider community, three habitat types were surveyed: riparian forest, recently inundated riverine forest, and oil palm plantation. Crassignatha danaugirangensis sp. n. is the most abundant ground-web-building spider species in riparian forest; it is rare or absent from the recently inundated forest and was not found in a nearby oil palm plantation. The availability of this taxonomic description may help facilitate the accumulation of data about this species and the role of inundated riverine forest in shaping invertebrate communities.

  6. Old maids have more appeal: effects of age and pheromone source on mate attraction in an orb-web spider

    Directory of Open Access Journals (Sweden)

    Anna-Lena Cory

    2016-04-01

    Full Text Available Background. In many insects and spider species, females attract males with volatile sex pheromones, but we know surprisingly little about the costs and benefits of female pheromone emission. Here, we test the hypothesis that mate attraction by females is dynamic and strategic in the sense that investment in mate attraction is matched to the needs of the female. We use the orb-web spider Argiope bruennichi in which females risk the production of unfertilised egg clutches if they do not receive a copulation within a certain time-frame. Methods. We designed field experiments to compare mate attraction by recently matured (young females with females close to oviposition (old. In addition, we experimentally separated the potential sources of pheromone transmission, namely the female body and the web silk. Results. In accordance with the hypothesis of strategic pheromone production, the probability of mate attraction and the number of males attracted differed between age classes. While the bodies and webs of young females were hardly found by males, the majority of old females attracted up to two males within two hours. Old females not only increased pheromone emission from their bodies but also from their webs. Capture webs alone spun by old females were significantly more efficient in attracting males than webs of younger females. Discussion. Our results suggest that females modulate their investment in signalling according to the risk of remaining unmated and that they thereby economize on the costs associated with pheromone production and emission.

  7. Female feeding regime and polyandry in the nuptially feeding nursery web spider, Pisaura mirabilis

    Science.gov (United States)

    Prokop, Pavol; Maxwell, Michael R.

    2009-02-01

    We examined the influence of female feeding regime on polyandry in the nuptially feeding nursery web spider (Pisaura mirabilis). In this species, the nuptial gift, a dead prey item wrapped in the male’s silk, is physically separate from the ejaculate. We manipulated female feeding regime (starved or fed) and the presence or absence of a gift with three successive males to test direct-benefits hypotheses (nuptial gift or sperm supply) for the expression of polyandry. The presence of a gift was necessary for copulation, as no male without a gift successfully copulated. Female mating behavior most strongly supports polyandry due to the accumulation of gifted food items (“nuptial gift” direct-benefits hypothesis). Starved females that were presented with a gift accepted significantly more gifts and inseminations than fed females. Most starved females (74%) copulated two or more times, as opposed to only 3% of the fed females. Nearly all of the females that accepted a gift subsequently copulated. The nuptial gift item seems to function as male mating effort and females appear to receive multiple matings as part of a feeding strategy.

  8. Adjustment of web-building initiation to high humidity: a constraint by humidity-dependent thread stickiness in the spider Cyrtarachne.

    Science.gov (United States)

    Baba, Yuki G; Kusahara, Miki; Maezono, Yasunori; Miyashita, Tadashi

    2014-07-01

    Cyrtarachne is an orb-weaving spider belonging to the subfamily Cyrtarachninae (Araneidae) which includes triangular-web-building Pasilobus and bolas spiders. The Cyrtarachninae is a group of spiders specialized in catching moths, which is thought to have evolved from ordinary orb-weaving araneids. Although the web-building time of nocturnal spiders is in general related to the time of sunset, anecdotal evidence has suggested variability of web-building time in Cyrtarachne and its closely related genera. This study has examined the effects of temperature, humidity, moonlight intensity, and prey (moths) availability on web-building time of Cyrtarachne bufo, Cyrtarachne akirai, and Cyrtarachne nagasakiensis. Generalized linear mixed model (GLMM) have revealed that humidity, and not prey availability, was the essential variable that explained the daily variability of web-building time. Experiments measuring thread stickiness under different humidities showed that, although the thread of Cyrtarachne was found to have strong stickiness under high humidity, low humidity caused a marked decrease of thread stickiness. By contrast, no obvious change in stickiness was seen in an ordinary orb-weaving spider, Larinia argiopiformis. These findings suggest that Cyrtarachne adjusts its web-building time to favorable conditions of high humidity maintaining strong stickiness, which enables the threads to work efficiently for capturing prey.

  9. Adjustment of web-building initiation to high humidity: a constraint by humidity-dependent thread stickiness in the spider Cyrtarachne

    Science.gov (United States)

    Baba, Yuki G.; Kusahara, Miki; Maezono, Yasunori; Miyashita, Tadashi

    2014-07-01

    Cyrtarachne is an orb-weaving spider belonging to the subfamily Cyrtarachninae (Araneidae) which includes triangular-web-building Pasilobus and bolas spiders. The Cyrtarachninae is a group of spiders specialized in catching moths, which is thought to have evolved from ordinary orb-weaving araneids. Although the web-building time of nocturnal spiders is in general related to the time of sunset, anecdotal evidence has suggested variability of web-building time in Cyrtarachne and its closely related genera. This study has examined the effects of temperature, humidity, moonlight intensity, and prey (moths) availability on web-building time of Cyrtarachne bufo, Cyrtarachne akirai, and Cyrtarachne nagasakiensis. Generalized linear mixed model (GLMM) have revealed that humidity, and not prey availability, was the essential variable that explained the daily variability of web-building time. Experiments measuring thread stickiness under different humidities showed that, although the thread of Cyrtarachne was found to have strong stickiness under high humidity, low humidity caused a marked decrease of thread stickiness. By contrast, no obvious change in stickiness was seen in an ordinary orb-weaving spider, Larinia argiopiformis. These findings suggest that Cyrtarachne adjusts its web-building time to favorable conditions of high humidity maintaining strong stickiness, which enables the threads to work efficiently for capturing prey.

  10. Short and fast vs long and slow: age changes courtship in male orb-web spiders ( Argiope keyserlingi)

    Science.gov (United States)

    O'Hanlon, James C.; Wignall, Anne E.; Herberstein, Marie E.

    2018-02-01

    Male reproductive performance can vary with condition, age and future reproductive opportunities. Web-building spiders are ideal models to examine the effects of senescence on fitness-related behaviours due to strong selection on male courtship to reduce pre-copulatory sexual cannibalism. Argiope keyserlingi spiders generate courtship vibrations, or `shudders', that reduce female aggression. We found that male A. keyserlingi courtship slowed with chronological age. Older males took longer to travel across the courtship thread, and overall number of shudders increased. Males retained some ability to modulate courtship quality (shudder duration and number of rocks within each shudder) in response to female quality. A change in courtship performance over time, despite strong selection for repeatability, indicates that ageing in male A. keyserlingi may have direct impacts on reproductive performance.

  11. One-step fabrication of multifunctional composite polyurethane spider-web-like nanofibrous membrane for water purification

    Energy Technology Data Exchange (ETDEWEB)

    Pant, Hem Raj, E-mail: hempant@jbnu.ac.kr [Department of Bio-nano System Engineering, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Department of Engineering Science and Humanities, Institute of Engineering, Pulchowk Campus, Tribhuvan University, Kathmandu (Nepal); Kim, Han Joo [Division of Mechanical Design Engineering, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Joshi, Mahesh Kumar; Pant, Bishweshwar; Park, Chan Hee; Kim, Jeong In [Department of Bio-nano System Engineering, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Hui, K.S., E-mail: kshui@hanyang.ac.kr [Department of Mechanical Engineering, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of); Kim, Cheol Sang, E-mail: chskim@jbnu.ac.kr [Department of Bio-nano System Engineering, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Division of Mechanical Design Engineering, Chonbuk National University, Jeonju 561-756 (Korea, Republic of)

    2014-01-15

    Highlights: • A single mat having varieties of performance for water treatment is simply introduced. • Cost effective Ag-doped fly ash/PU nanofibers are fabricated in one-step. • Solvent reduction of AgNO{sub 3} could produce Ag-loaded spider-web nets. • Size of Ag NPs on fiber surface can be controlled by controlling stirring time. • Fabrication of nanocomposite using pollutant material to control other pollutents. -- Abstract: A stable silver-doped fly ash/polyurathene (Ag-FA/PU) nanocomposite multifunctional membrane is prepared by a facile one-step electrospinning process using fly ash particles (FAPs). Colloidal solution of PU with FAPs and Ag metal precursor was subjected to fabricate nanocomposite spider-web-like membrane using electrospinning process. Presence of N,N-dimethylformamide (solvent of PU) led to reduce silver nitrate into Ag NPs. Incorporation of Ag NPs and FAPs through electrospun PU fibers is proven through electron microscopy and spectroscopic techniques. Presence of these NPs on PU nanofibers introduces several potential physicochemical properties such as spider-web-like nano-neeting for NPs separation, enhanced absorption capacity to remove carcinogenic arsenic (As) and toxic organic dyes, and antibacterial properties with reduce bio-fouling for membrane filter application. Preliminary observations used for above-mentioned applications for water treatment showed that it will be an economically and environmentally friendly nonwoven matrix for water purification. This simple approach highlights new avenues about the utilization of one pollutant material to control other pollutants in scalable and inexpensive ways.

  12. One-step fabrication of multifunctional composite polyurethane spider-web-like nanofibrous membrane for water purification

    International Nuclear Information System (INIS)

    Pant, Hem Raj; Kim, Han Joo; Joshi, Mahesh Kumar; Pant, Bishweshwar; Park, Chan Hee; Kim, Jeong In; Hui, K.S.; Kim, Cheol Sang

    2014-01-01

    Highlights: • A single mat having varieties of performance for water treatment is simply introduced. • Cost effective Ag-doped fly ash/PU nanofibers are fabricated in one-step. • Solvent reduction of AgNO 3 could produce Ag-loaded spider-web nets. • Size of Ag NPs on fiber surface can be controlled by controlling stirring time. • Fabrication of nanocomposite using pollutant material to control other pollutents. -- Abstract: A stable silver-doped fly ash/polyurathene (Ag-FA/PU) nanocomposite multifunctional membrane is prepared by a facile one-step electrospinning process using fly ash particles (FAPs). Colloidal solution of PU with FAPs and Ag metal precursor was subjected to fabricate nanocomposite spider-web-like membrane using electrospinning process. Presence of N,N-dimethylformamide (solvent of PU) led to reduce silver nitrate into Ag NPs. Incorporation of Ag NPs and FAPs through electrospun PU fibers is proven through electron microscopy and spectroscopic techniques. Presence of these NPs on PU nanofibers introduces several potential physicochemical properties such as spider-web-like nano-neeting for NPs separation, enhanced absorption capacity to remove carcinogenic arsenic (As) and toxic organic dyes, and antibacterial properties with reduce bio-fouling for membrane filter application. Preliminary observations used for above-mentioned applications for water treatment showed that it will be an economically and environmentally friendly nonwoven matrix for water purification. This simple approach highlights new avenues about the utilization of one pollutant material to control other pollutants in scalable and inexpensive ways

  13. Short-range phenotypic divergence among genetically distinct parapatric populations of an Australian funnel-web spider.

    Science.gov (United States)

    Wong, Mark K L; Woodman, James D; Rowell, David M

    2017-07-01

    Speciation involves divergence at genetic and phenotypic levels. Where substantial genetic differentiation exists among populations, examining variation in multiple phenotypic characters may elucidate the mechanisms by which divergence and speciation unfold. Previous work on the Australian funnel-web spider Atrax sutherlandi Gray (2010; Records of the Australian Museum 62 , 285-392; Mygalomorphae: Hexathelidae: Atracinae) has revealed a marked genetic structure along a 110-kilometer transect, with six genetically distinct, parapatric populations attributable to past glacial cycles. In the present study, we explore variation in three classes of phenotypic characters (metabolic rate, water loss, and morphological traits) within the context of this phylogeographic structuring. Variation in metabolic and water loss rates shows no detectable association with genetic structure; the little variation observed in these rates may be due to the spiders' behavioral adaptations (i.e., burrowing), which buffer the effects of climatic gradients across the landscape. However, of 17 morphological traits measured, 10 show significant variation among genetic populations, in a disjunct manner that is clearly not latitudinal. Moreover, patterns of variation observed for morphological traits serving different organismic functions (e.g., prey capture, burrowing, and locomotion) are dissimilar. In contrast, a previous study of an ecologically similar sympatric spider with little genetic structure indicated a strong latitudinal response in 10 traits over the same range. The congruence of morphological variation with deep phylogeographic structure in Tallaganda's A. sutherlandi populations, as well as the inconsistent patterns of variation across separate functional traits, suggest that the spiders are likely in early stages of speciation, with parapatric populations independently responding to local selective forces.

  14. The Spider and the Sea : Effects of marine subsidies on the role of spiders in terrestrial food webs

    OpenAIRE

    Mellbrand, Kajsa

    2009-01-01

    The purpose of this study was to identify if terrestrial arthropod predators on Baltic Sea shores vary in their use of marine versus terrestrial food items, and to construct a bottom-up food web for Baltic Sea shores. The inflow of marine nutrients in the area consists mainly of marine algal detritus and emerging aquatic insects (e.g. phantom midges, Chironomidae). Diets of coastal arthropods were examined using carbon and nitrogen stable isotope analysis, and a two source mixing model was us...

  15. A Coin-Flipping Analogy and Web App for Teaching Spin-Spin Splitting in [superscript 1]H NMR Spectroscopy

    Science.gov (United States)

    Azman, Adam M.; Esteb, John J.

    2016-01-01

    A coin-flipping analogy and free corresponding web app have been developed to facilitate student understanding of the origins of spin-spin splitting. First-order splitting patterns can easily be derived and understood. "Complex" splitting patterns (e.g., doublet of quartets), are easily incorporated into the analogy. A study of the…

  16. A revision of the purse-web spider genus Calommata Lucas, 1837 (Araneae, Atypidae in the Afrotropical Region

    Directory of Open Access Journals (Sweden)

    Rene Fourie

    2011-05-01

    Full Text Available The purse-web spider genus Calommata Lucas, 1837 is revised in the Afrotropical Region. Following examination of the female type material, C. transvaalica Hewitt, 1916 is removed from synonymy with C. simoni Pocock, 1903 and revalidated. The females of both species are redescribed and their males described for the first time. While C. simoni is very widespread across tropical Africa, C. transvaalica is endemic to northern South Africa. Four new species are described, all known only from males: C. megae sp. n. (Zimbabwe, C. meridionalis sp. n. (South Africa, C. namibica sp. n. (Namibia and C. tibialis sp. n. (Ivory Coast and Togo. Notes are presented on the biology of each species.

  17. Discrimination and identification of Q-markers based on 'Spider-web' mode for quality control of traditional Chinese medicine.

    Science.gov (United States)

    Jiang, Zhenzuo; Yang, Jing; Wang, Yuefei

    2017-12-28

    The safety and effectiveness of traditional Chinese medicine (TCM) in clinical practice is directly related to the quality of TCM. And, the quality control of TCM is a pivotal issue to the quality of TCM, but also an obstacle impeding the modernization of TCM. The purpose of this work is to compile and develop a strategy based on discrimination and identification of quality markers (Q-markers) for quality control of TCM. Mainly established by seven variables derived from four dimensions including content, stability, pharmacokinetics and pharmacology, the 'Spider-web' mode was undertaken to assess the Q-marker property of candidate compounds originated from TCM by taking regression area (A) and coefficient variation (CV) of the tested compounds into account. The importance index (ImI), ImI = A × 1/CV, was suggested to focus Q-markers. The compounds with larger regression area (A) and less coefficient variation (CV) are preferentially adopted as Q-markers, which should possess the satisfactory properties of content, stability, pharmacokinetics and pharmacological activity. To the contrary, the compounds are excluded on the grounds of the unsatisfactory Q-markers' property, less regression area (A) and larger coefficient variation (CV), which cannot represent the quality of TCM. The 'Spider-web' mode can filter out the redundant constituents and focus on the key indexes of quality control - Q-markers. The screened Q-markers possess the optimal integrated properties of content, stability, pharmacokinetics and pharmacology among the numerous and complicated ingredients of TCM, which can comprehensively characterize inherent quality of TCM. In summary, the novel strategy established in this work provides a valuable perspective for the quality control of TCM. Copyright © 2017 Elsevier GmbH. All rights reserved.

  18. Non-pest prey do not disrupt aphid predation by a web-building spider.

    Science.gov (United States)

    Welch, K D; Whitney, T D; Harwood, J D

    2016-02-01

    A generalist predator's ability to contribute to biological control is influenced by the decisions it makes during foraging. Predators often use flexible foraging tactics, which allows them to pursue specific types of prey at the cost of reducing the likelihood of capturing other types of prey. When a pest insect has low nutritional quality or palatability for a predator, the predator is likely to reject that prey in favour of pursuing alternative, non-pest prey. This is often thought to limit the effectiveness of generalist predators in consuming aphids, which are of low nutritional quality for many generalist predators. Here, we report behavioural assays that test the hypothesis that the generalist predator, Grammonota inornata (Araneae: Linyphiidae), preferentially forages for a non-pest prey with high nutritional quality (springtails), and rejects a pest prey with low nutritional quality (aphids). In no-choice assays, molecular gut-content analysis revealed that spiders continued to feed on the low-quality aphids at high rates, even when high-quality springtails were readily available. When provided a choice between aphids and springtails in two-way choice tests, spiders did not show the expected preference for springtails. Decision-making by spiders during foraging therefore appears to be sub-optimal, possibly because of attraction to the less frequently encountered of two preys as part of a dietary diversification strategy. These results indicate that behavioural preferences alone do not necessarily compromise the pest-suppression capacity of natural enemies: even nutritionally sub-optimal pest prey can potentially be subject to predation and suppression by natural enemies.

  19. Unravelling the complex venom landscapes of lethal Australian funnel-web spiders (Hexathelidae: Atracinae) using LC-MALDI-TOF mass spectrometry.

    Science.gov (United States)

    Palagi, Alexandre; Koh, Jennifer M S; Leblanc, Mathieu; Wilson, David; Dutertre, Sébastien; King, Glenn F; Nicholson, Graham M; Escoubas, Pierre

    2013-03-27

    Spider venoms represent vast sources of bioactive molecules whose diversity remains largely unknown. Indeed, only a small subset of species have been studied out of the ~43,000 extant spider species. The present study investigated inter- and intra-species venom complexity in 18 samples collected from a variety of lethal Australian funnel-web spiders (Mygalomorphae: Hexathelidae: Atracinae) using C4 reversed-phase separation coupled to offline MALDI-TOF mass spectrometry (LC-MALDI-TOF MS). An in-depth investigation focusing on four atracine venoms (male Illawarra wisharti, male and female Hadronyche cerberea, and female Hadronyche infensa Toowoomba) revealed, on average, ~800 peptides in female venoms while male venoms contained ~400 peptides, distributed across most HPLC fractions. This is significantly higher than previous estimates of peptide expression in mygalomorph venoms. These venoms also showed distinct intersexual as well as intra- and inter-species variation in peptide masses. Construction of both 3D and 2D contour plots revealed that peptide mass distributions in all 18 venoms were centered around the 3200-5400m/z range and to a lesser extent the 6600-8200m/z range, consistent with previously described hexatoxins. These findings highlight the extensive diversity of peptide toxins in Australian funnel-web spider venoms that that can be exploited as novel therapeutic and biopesticide lead molecules. In the present study we describe the complexity of 18 venoms from lethal Australian funnel-web spiders using LC-MALDI-TOF MS. The study includes an in-depth investigation, focusing on four venoms, that revealed the presence of ~800 peptides in female venoms and ~400 peptides in male venoms. This is significantly higher than previous estimates of peptide expression in spider venoms. By constructing both 3D and 2D contour plots we were also able to reveal the distinct intersexual as well as intra- and inter-species variation in venom peptide masses. We show that

  20. Dew drops on spider web appearance: a newly named pattern of IgG4 deposition in pemphigus with direct immunofluorescence.

    Science.gov (United States)

    Dmochowski, Marian; Gornowicz-Porowska, Justyna; Bowszyc-Dmochowska, Monika

    2017-08-01

    Novel appearances in cutaneous pathology as well as mucocutaneous clinical signs are being described which indicate that this is still an attractive area for exploration. The H + E histology terms of "decorated tomb stoning" and "undecorated tomb stoning", advocated by some pathologists, are misleading and as such should be avoided. Here, an appearance of IgG4 pemphigus deposits examined cost-effectively with direct immunofluorescence and suggested to be called "dew drops on spider web" is depicted in depth.

  1. A Parasitoid Wasp Induces Overwintering Behaviour in Its Spider Host

    OpenAIRE

    Korenko, Stanislav; Pekár, Stano

    2011-01-01

    Parasites and parasitoids control behaviors of their hosts. However, the origin of the behavior evoked by the parasitic organism has been rarely identified. It is also not known whether the manipulation is universal or host-specific. Polysphinctine wasps, koinobiont ectoparasitoids of several spider species that manipulate host web-spinning activity for their own protection during pupation, provide an ideal system to reveal the origin of the evoked behavior. Larva of Zatypota percontatoria pe...

  2. Bat Predation by Spiders

    Science.gov (United States)

    Nyffeler, Martin; Knörnschild, Mirjam

    2013-01-01

    In this paper more than 50 incidences of bats being captured by spiders are reviewed. Bat-catching spiders have been reported from virtually every continent with the exception of Antarctica (∼90% of the incidences occurring in the warmer areas of the globe between latitude 30° N and 30° S). Most reports refer to the Neotropics (42% of observed incidences), Asia (28.8%), and Australia-Papua New Guinea (13.5%). Bat-catching spiders belong to the mygalomorph family Theraphosidae and the araneomorph families Nephilidae, Araneidae, and Sparassidae. In addition to this, an attack attempt by a large araneomorph hunting spider of the family Pisauridae on an immature bat was witnessed. Eighty-eight percent of the reported incidences of bat catches were attributable to web-building spiders and 12% to hunting spiders. Large tropical orb-weavers of the genera Nephila and Eriophora in particular have been observed catching bats in their huge, strong orb-webs (of up to 1.5 m diameter). The majority of identifiable captured bats were small aerial insectivorous bats, belonging to the families Vespertilionidae (64%) and Emballonuridae (22%) and usually being among the most common bat species in their respective geographic area. While in some instances bats entangled in spider webs may have died of exhaustion, starvation, dehydration, and/or hyperthermia (i.e., non-predation death), there were numerous other instances where spiders were seen actively attacking, killing, and eating the captured bats (i.e., predation). This evidence suggests that spider predation on flying vertebrates is more widespread than previously assumed. PMID:23516436

  3. Spinning the Web: The Design of Yale's Front Door.

    Science.gov (United States)

    Callum, Robert

    1996-01-01

    The process of designing the Yale University (Connecticut) World Wide Web page "front door" is described, including its conceptualization, evolution through technological advances and attitudinal change, achievement of consensus through an interdepartmental advisory team, constituency response, and expectations about future change. (MSE)

  4. Collections of spiders, scientific networks, and politics: the web of life of Cândido de Mello Leitão (1886-1948

    Directory of Open Access Journals (Sweden)

    Regina Horta Duarte

    2010-01-01

    Full Text Available Cândido de Mello Leitão (1886-1948 started his career as a pediatrician. Being extremely dedicated to the study of spiders, he became one of the greatest arachnologists of his time, and earned wide recognition from his peers. The present article deals with some aspects of his career, while trying to address the question of how one could become a biologist in Brazil in the first half of the 20th century, when there were no graduation courses in Biology and the profession held no official recognition. Research conducted on books, newspapers and Mello Leitão's personal documents has shown how this specialization came to being in the crossroads of practical experiences in various scientific institutions, national and international collaboration and the changing social-historic conditions. A spider expert, Mello Leitão had great knowledge on webs that allowed him to become a biologist. Amid these personal and institutional relationships, he built and spread knowledge, and carved a role for himself, his colleagues, the institutions he worked in and the biology he practiced.

  5. Simplifying understory complexity in oil palm plantations is associated with a reduction in the density of a cleptoparasitic spider,Argyrodes miniaceus(Araneae: Theridiidae), in host (Araneae: Nephilinae) webs.

    Science.gov (United States)

    Spear, Dakota M; Foster, William A; Advento, Andreas Dwi; Naim, Mohammad; Caliman, Jean-Pierre; Luke, Sarah H; Snaddon, Jake L; Ps, Sudharto; Turner, Edgar C

    2018-02-01

    Expansion of oil palm agriculture is currently one of the main drivers of habitat modification in Southeast Asia. Habitat modification can have significant effects on biodiversity, ecosystem function, and interactions between species by altering species abundances or the available resources in an ecosystem. Increasing complexity within modified habitats has the potential to maintain biodiversity and preserve species interactions. We investigated trophic interactions between Argyrodes miniaceus, a cleptoparasitic spider, and its Nephila spp . spider hosts in mature oil palm plantations in Sumatra, Indonesia. A. miniaceus co-occupy the webs of Nephila spp . females and survive by stealing prey items caught in the web. We examined the effects of experimentally manipulated understory vegetation complexity on the density and abundance of A. miniaceus in Nephila spp . webs. Experimental understory treatments included enhanced complexity, standard complexity, and reduced complexity understory vegetation, which had been established as part of the ongoing Biodiversity and Ecosystem Function in Tropical Agriculture (BEFTA) Project. A. miniaceus density ranged from 14.4 to 31.4 spiders per square meter of web, with significantly lower densities found in reduced vegetation complexity treatments compared with both enhanced and standard treatment plots. A. miniaceus abundance per plot was also significantly lower in reduced complexity than in standard and enhanced complexity plots. Synthesis and applications : Maintenance of understory vegetation complexity contributes to the preservation of spider host-cleptoparasite relationships in oil palm plantations. Understory structural complexity in these simplified agroecosystems therefore helps to support abundant spider populations, a functionally important taxon in agricultural landscapes. In addition, management for more structurally complex agricultural habitats can support more complex trophic interactions in tropical

  6. Bioprospecting finds the toughest biological material: extraordinary silk from a giant riverine orb spider.

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    Ingi Agnarsson

    Full Text Available BACKGROUND: Combining high strength and elasticity, spider silks are exceptionally tough, i.e., able to absorb massive kinetic energy before breaking. Spider silk is therefore a model polymer for development of high performance biomimetic fibers. There are over 41,000 described species of spiders, most spinning multiple types of silk. Thus we have available some 200,000+ unique silks that may cover an amazing breadth of material properties. To date, however, silks from only a few tens of species have been characterized, most chosen haphazardly as model organisms (Nephila or simply from researchers' backyards. Are we limited to 'blindly fishing' in efforts to discover extraordinary silks? Or, could scientists use ecology to predict which species are likely to spin silks exhibiting exceptional performance properties? METHODOLOGY: We examined the biomechanical properties of silk produced by the remarkable Malagasy 'Darwin's bark spider' (Caerostris darwini, which we predicted would produce exceptional silk based upon its amazing web. The spider constructs its giant orb web (up to 2.8 m(2 suspended above streams, rivers, and lakes. It attaches the web to substrates on each riverbank by anchor threads as long as 25 meters. Dragline silk from both Caerostris webs and forcibly pulled silk, exhibits an extraordinary combination of high tensile strength and elasticity previously unknown for spider silk. The toughness of forcibly silked fibers averages 350 MJ/m(3, with some samples reaching 520 MJ/m(3. Thus, C. darwini silk is more than twice tougher than any previously described silk, and over 10 times better than Kevlar®. Caerostris capture spiral silk is similarly exceptionally tough. CONCLUSIONS: Caerostris darwini produces the toughest known biomaterial. We hypothesize that this extraordinary toughness coevolved with the unusual ecology and web architecture of these spiders, decreasing the likelihood of bridgelines breaking and collapsing the web

  7. The presence of webbing affects the oviposition rate of two-spotted spider mites, Tetranychus urticae (Acari: Tetranychidae)

    NARCIS (Netherlands)

    Oku, K.; Magalhães, S.; Dicke, M.

    2009-01-01

    Several species of tetranychid mites including Tetranychus urticae Koch (Acari: Tetranychidae) construct complicated three-dimensional webs on plant leaves. These webs provide protection against biotic and abiotic stress. As producing web is likely to entail a cost, mites that arrive on a leaf with

  8. Electrohydrodynamic spinning of random-textured silver webs for electrodes embedded in flexible organic solar cells

    Science.gov (United States)

    Yoon, Dai Geon; Chin, Byung Doo; Bail, Robert

    2017-03-01

    A convenient process for fabricating a transparent conducting electrode on a flexible substrate is essential for numerous low-cost optoelectronic devices, including organic solar cells (OSCs), touch sensors, and free-form lighting applications. Solution-processed metal-nanowire arrays are attractive due to their low sheet resistance and optical clarity. However, the limited conductance at wire junctions and the rough surface topology still need improvement. Here, we present a facile process of electrohydrodynamic spinning using a silver (Ag) - polymer composite paste with high viscosity. Unlike the metal-nanofiber web formed by conventional electrospinning, a relatively thick, but still invisible-to-naked eye, Ag-web random pattern was formed on a glass substrate. The process parameters such as the nozzle diameter, voltage, flow rate, standoff height, and nozzle-scanning speed, were systematically engineered. The formed random texture Ag webs were embedded in a flexible substrate by in-situ photo-polymerization, release from the glass substrate, and post-annealing. OSCs with a donor-acceptor polymeric heterojunction photoactive layer were prepared on the Ag-web-embedded flexible films with various Ag-web densities. The short-circuit current and the power conversion efficiency of an OSC with a Ag-web-embedded electrode were not as high as those of the control sample with an indium-tin-oxide electrode. However, the Ag-web textures embedded in the OSC served well as electrodes when bent (6-mm radius), showing a power conversion efficiency of 2.06% (2.72% for the flat OSC), and the electrical stability of the Ag-web-textured patterns was maintained for up to 1,000 cycles of bending.

  9. Effects of social information on life history and mating tactics of males in the orb-web spider Argiope bruennichi.

    Science.gov (United States)

    Cory, Anna-Lena; Schneider, Jutta M

    2018-01-01

    Informed mating decisions are often based on social cues providing information about prospective mating opportunities. Social information early in life can trigger developmental modifications and influence later mating decisions. A high adaptive value of such adjustments is particularly obvious in systems where potential mating rates are extremely limited and have to be carried out in a short time window. Males of the sexually cannibalistic spider Argiope bruennichi can achieve maximally two copulations which they can use for one (monogyny) or two females (bigyny). The choice between these male mating tactics should rely on female availability that males might assess through volatile sex pheromones emitted by virgin females. We predict that in response to those female cues, males of A. bruennichi should mature earlier and at a smaller body size and favor a bigynous mating tactic in comparison with controls. We sampled spiders from two areas close to the Southern and Northern species range to account for differences in mate quality and seasonality. In a fully factorial design, half of the subadult males from both areas obtained silk cues of females, while the other half remained without female exposure. Adult males were subjected to no-choice mating tests and could either monopolize the female or leave her (bigyny). We found that Southern males matured later and at a larger size than Northern males. Regardless of their origin, males also shortened the subadult stage in response to female cues, which, however, had no effects on male body mass. Contrary to our prediction, the frequencies of mating tactics were unaffected by the treatment. We conclude that while social cues during late development elicit adaptive life history adjustments, they are less important for the adjustment of mating decisions. We suggest that male tactics mostly rely on local information at the time of mate search.

  10. A parasitoid wasp induces overwintering behaviour in its spider host.

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    Stanislav Korenko

    Full Text Available Parasites and parasitoids control behaviors of their hosts. However, the origin of the behavior evoked by the parasitic organism has been rarely identified. It is also not known whether the manipulation is universal or host-specific. Polysphinctine wasps, koinobiont ectoparasitoids of several spider species that manipulate host web-spinning activity for their own protection during pupation, provide an ideal system to reveal the origin of the evoked behavior. Larva of Zatypota percontatoria performed species-specific manipulation of theridiid spiders, Neottiura bimaculata and Theridion varians, shortly before pupation. Parasitized N. bimaculata produced a dense web, whereas parasitized T. varians built a cupola-like structure. The larva pupated inside of either the dense web or the cupola-like structure. We discovered that unparasitized N. bimaculata produce an analogous dense web around their eggsacs and for themselves during winter, while T. varians construct an analogous 'cupola' only for overwintering. We induced analogous manipulation in unparasitized hosts by altering ambient conditions. We discovered that the behavior evoked by larvae in two hosts was functionally similar. The larva evoked protective behaviors that occur in unparasitized hosts only during specific life-history periods.

  11. A parasitoid wasp induces overwintering behaviour in its spider host.

    Science.gov (United States)

    Korenko, Stanislav; Pekár, Stano

    2011-01-01

    Parasites and parasitoids control behaviors of their hosts. However, the origin of the behavior evoked by the parasitic organism has been rarely identified. It is also not known whether the manipulation is universal or host-specific. Polysphinctine wasps, koinobiont ectoparasitoids of several spider species that manipulate host web-spinning activity for their own protection during pupation, provide an ideal system to reveal the origin of the evoked behavior. Larva of Zatypota percontatoria performed species-specific manipulation of theridiid spiders, Neottiura bimaculata and Theridion varians, shortly before pupation. Parasitized N. bimaculata produced a dense web, whereas parasitized T. varians built a cupola-like structure. The larva pupated inside of either the dense web or the cupola-like structure. We discovered that unparasitized N. bimaculata produce an analogous dense web around their eggsacs and for themselves during winter, while T. varians construct an analogous 'cupola' only for overwintering. We induced analogous manipulation in unparasitized hosts by altering ambient conditions. We discovered that the behavior evoked by larvae in two hosts was functionally similar. The larva evoked protective behaviors that occur in unparasitized hosts only during specific life-history periods.

  12. Changes in species diversity of arboreal spiders in Mexican coffee agroecosystems: untangling the web of local and landscape influences driving diversity

    Directory of Open Access Journals (Sweden)

    Zachary Hajian-Forooshani

    2014-11-01

    Full Text Available Agricultural intensification is implicated as a major driver of global biodiversity loss. Local management and landscape scale factors both influence biodiversity in agricultural systems, but there are relatively few studies to date looking at how local and landscape scales influence biodiversity in tropical agroecosystems. Understanding what drives the diversity of groups of organisms such as spiders is important from a pragmatic point of view because of the important biocontrol services they offer to agriculture. Spiders in coffee are somewhat enigmatic because of their positive or lack of response to agricultural intensification. In this study, we provide the first analysis, to our knowledge, of the arboreal spiders in the shade trees of coffee plantations. In the Soconusco region of Chiapas, Mexico we sampled across 38 sites on 9 coffee plantations. Tree and canopy connectedness were found to positively influence overall arboreal spider richness and abundance. We found that different functional groups of spiders are responding to different local and landscape factors, but overall elevation was most important variable influencing arboreal spider diversity. Our study has practical management applications that suggest having shade grown coffee offers more suitable habitat for arboreal spiders due to a variety of the characteristics of the shade trees. Our results which show consistently more diverse arboreal spider communities in lower elevations are important in light of looming global climate change. As the range of suitable elevations for coffee cultivation shrinks promoting arboreal spider diversity will be important in sustaining the viability of coffee.

  13. SPIDER SILK

    Directory of Open Access Journals (Sweden)

    PORAV Viorica

    2014-05-01

    Full Text Available The strengthness and toughness of spider fiber and its multifunctional nature is only surpassed in some cases by synthetic high performance fibers. In the world of natural fibers, spider silk has been long time recognized as a wonder fiber for its unique combination of high strength and rupture elongation. Scientists in civil military engineering reveal that the power of biological material (spider silk lies in the geometric configuration of structural protein, and the small cluster of week hydrogen bonds that works together to resist force and dissipate energy. Each spider and each type of silk has a set of mechanical properties optimized for their biological function. Most silks, in particular deagline silk, have exceptional mechanical properties. They exhibit a unique combination of high tensile strength and extensibility (ductility. This enables a silk fiber to absorb a lot of energy before breaking (toughness, the area under a stress- strain curve. A frequent mistake made in the mainstream media is to confuse strength and toughness when comparing silk to other materials. As shown below in detail, weight for weight, silk is stronger than steel, but not as strong as Kevlar. Silk is,however, tougher than both.This paper inform about overview on the today trend in the world of spider silk.

  14. Comparison of thread-cutting behaviour in three specialist predatory mites to cope with complex webs of Tetranychus spider mites

    NARCIS (Netherlands)

    Shimoda, T.; Kishimoto, H.; Takabayashi, J.; Amano, H.; Dicke, M.

    2009-01-01

    Anti-predator defenses provided by complex webs of Tetranychus mites can severely impede the performance of generalist predatory mites, whereas this may not be true for specialist predatory mites. Although some specialist predatory mites have developed morphological protection to reduce the adverse

  15. delta-Atracotoxins from australian funnel-web spiders compete with scorpion alpha-toxin binding but differentially modulate alkaloid toxin activation of voltage-gated sodium channels.

    Science.gov (United States)

    Little, M J; Zappia, C; Gilles, N; Connor, M; Tyler, M I; Martin-Eauclaire, M F; Gordon, D; Nicholson, G M

    1998-10-16

    delta-Atracotoxins from the venom of Australian funnel-web spiders are a unique group of peptide toxins that slow sodium current inactivation in a manner similar to scorpion alpha-toxins. To analyze their interaction with known sodium channel neurotoxin receptor sites, we studied their effect on [3H]batrachotoxin and 125I-Lqh II (where Lqh is alpha-toxin II from the venom of the scorpion Leiurus quinquestriatus hebraeus) binding and on alkaloid toxin-stimulated 22Na+ uptake in rat brain synaptosomes. delta-Atracotoxins significantly increased [3H]batrachotoxin binding yet decreased maximal batrachotoxin-activated 22Na+ uptake by 70-80%, the latter in marked contrast to the effect of scorpion alpha-toxins. Unlike the inhibition of batrachotoxin-activated 22Na+ uptake, delta-atracotoxins increased veratridine-stimulated 22Na+ uptake by converting veratridine from a partial to a full agonist, analogous to scorpion alpha-toxins. Hence, delta-atracotoxins are able to differentiate between the open state of the sodium channel stabilized by batrachotoxin and veratridine and suggest a distinct sub-conductance state stabilized by delta-atracotoxins. Despite these actions, low concentrations of delta-atracotoxins completely inhibited the binding of the scorpion alpha-toxin, 125I-Lqh II, indicating that they bind to similar, or partially overlapping, receptor sites. The apparent uncoupling between the increase in binding but inhibition of the effect of batrachotoxin induced by delta-atracotoxins suggests that the binding and action of certain alkaloid toxins may represent at least two distinguishable steps. These results further contribute to the understanding of the complex dynamic interactions between neurotoxin receptor site areas related to sodium channel gating.

  16. Poisonous Spiders: Bites, Symptoms, and Treatment; an Educational Review.

    Science.gov (United States)

    Rahmani, Farzad; Banan Khojasteh, Seyed Mahdi; Ebrahimi Bakhtavar, Hanieh; Rahmani, Farnaz; Shahsavari Nia, Kavous; Faridaalaee, Gholamreza

    2014-01-01

    More than 40,000 species of spiders have been identified in the world. Spider bites is a common problem among people, however few of them are harmful but delay in treatment can cause death. Since the spider bites are risk full to human, they should be taken seriously, especially in endemic areas. Our objective in this review was to study about poisonous spiders and find out treatments of them. Therefore, we collected related articles from PubMed database and Google Scholar. Three important syndromes caused by spider bites are loxoscelism, latrodectism and funnel web spider syndrome. Many treatments are used but much more studies should have done to decrease the mortality. In this review, we describes different venomous spiders according to their appearance, symptoms after their bites and available treatments.

  17. Poisonous Spiders: Bites, Symptoms, and Treatment; an Educational Review

    Directory of Open Access Journals (Sweden)

    Farzad Rahmani

    2014-03-01

    Full Text Available More than 40,000 species of spiders have been identified in the world. Spider bites is a common problem among people, however few of them are harmful but delay in treatment can cause death. Since the spider bites are risk full to human, they should be taken seriously, especially in endemic areas. Our objective in this review was to study about poisonous spiders and find out treatments of them. Therefore we collected related articles from PubMed database and Google Scholar. Three important syndromes caused by spider bites are loxoscelism, latrodectism and funnel web spider syndrome. Many treatments are used but much more studies should have done to decrease the mortality. In this review, we describes different venomous spiders according to their appearance, symptoms after their bites and available treatments. 

  18. Stress/Strain Characteristics and Biochemical Correlates of Spider Silks

    Science.gov (United States)

    1999-10-18

    do aminoacid analysis on silk samples measured and collected from the same spiders. Background to reports 1 and 2: Dr Kaplan left Natick during the...properties (shown by us) as well as measurable effects on silk aminoacid compositions (C Craig pers. comm). Thus after initial samples of silks from a...variability could be the state of nutrition of the spider. Starvation has been shown to have an effect on the web- geometry in orb-weaving spiders 2; and

  19. The Effect of Organic Fertilizers and Flowering Plants on Sheet-Web and Wolf Spider Populations (Araneae: Lycosidae and Linyphiidae) and Its Importance for Pest Control.

    Science.gov (United States)

    El-Nabawy, El-Said M; Tsuda, Katsuo; Sakamaki, Yositaka; Oda, Asahi; Ushijima, Yurie

    2016-01-01

    The main goal of this study was to identify the treatment that increases the populations of spiders, which are effective predators in agroecosystems. In 2013 and 2014 the experimental eggplant (Solanum melongena L.) field was two different treatments, organic fertilizers and chemical fertilizer treatment, and in 2014 we surrounded organic fertilizer plots with the flowering plants mealy cup sage (Salvia farinacea Benth.), spearmint (Mentha spicata L.), and basil (Ocimum basilicum L.). Analysis using repeated measures ANOVA revealed significant influences of fertilizer type on the numbers of linyphiid spiders and Collembola in 2013. In 2014, the numbers of Collembola, thrips, and lycosid and linyphiid spider were higher in organic fertilizer with flowering plants treatment comparing with the chemical fertilizer treatment. Moreover, the numbers of Henosepilachna vigintioctopunctata (F.) were significantly lower in the organic fertilizer with flowering plants treatment than in chemical fertilizers treatment. Finally, we expect that Thysanoptera and Collembola were important alternative prey for linyphiid and lycosid spiders and the use of organic fertilizer and flowering plants enhanced the density of these spiders, and may increase their effectiveness in suppressing the populations of H. vigintioctopunctata (F.). © The Author 2016. Published by Oxford University Press on behalf of the Entomological Society of America.

  20. Almost a spider: a 305-million-year-old fossil arachnid and spider origins.

    Science.gov (United States)

    Garwood, Russell J; Dunlop, Jason A; Selden, Paul A; Spencer, Alan R T; Atwood, Robert C; Vo, Nghia T; Drakopoulos, Michael

    2016-03-30

    Spiders are an important animal group, with a long history. Details of their origins remain limited, with little knowledge of their stem group, and no insights into the sequence of character acquisition during spider evolution. We describe a new fossil arachnid, Idmonarachne brasierigen. et sp. nov. from the Late Carboniferous (Stephanian,ca 305-299 Ma) of Montceau-les-Mines, France. It is three-dimensionally preserved within a siderite concretion, allowing both laboratory- and synchrotron-based phase-contrast computed tomography reconstruction. The latter is a first for siderite-hosted fossils and has allowed us to investigate fine anatomical details. Although distinctly spider-like in habitus, this remarkable fossil lacks a key diagnostic character of Araneae: spinnerets on the underside of the opisthosoma. It also lacks a flagelliform telson found in the recently recognized, spider-related, Devonian-Permian Uraraneida. Cladistic analysis resolves our new fossil as sister group to the spiders: the spider stem-group comprises the uraraneids and I. brasieri While we are unable to demonstrate the presence of spigots in this fossil, the recovered phylogeny suggests the earliest character to evolve on the spider stem-group is the secretion of silk. This would have been followed by the loss of a flagelliform telson, and then the ability to spin silk using spinnerets. This last innovation defines the true spiders, significantly post-dates the origins of silk, and may be a key to the group's success. The Montceau-les-Mines locality has previously yielded a mesothele spider (with spinnerets). Evidently, Late Palaeozoic spiders lived alongside Palaeozoic arachnid grades which approached the spider condition, but did not express the full suite of crown-group autapomorphies. © 2016 The Authors.

  1. Discovery of the largest orbweaving spider species: the evolution of gigantism in Nephila.

    Directory of Open Access Journals (Sweden)

    Matjaz Kuntner

    2009-10-01

    Full Text Available More than 41,000 spider species are known with about 400-500 added each year, but for some well-known groups, such as the giant golden orbweavers, Nephila, the last valid described species dates from the 19(th century. Nephila are renowned for being the largest web-spinning spiders, making the largest orb webs, and are model organisms for the study of extreme sexual size dimorphism (SSD and sexual biology. Here, we report on the discovery of a new, giant Nephila species from Africa and Madagascar, and review size evolution and SSD in Nephilidae.We formally describe N. komaci sp. nov., the largest web spinning species known, and place the species in phylogenetic context to reconstruct the evolution of mean size (via squared change parsimony. We then test female and male mean size correlation using phylogenetically independent contrasts, and simulate nephilid body size evolution using Monte Carlo statistics.Nephila females increased in size almost monotonically to establish a mostly African clade of true giants. In contrast, Nephila male size is effectively decoupled and hovers around values roughly one fifth of female size. Although N. komaci females are the largest Nephila yet discovered, the males are also large and thus their SSD is not exceptional.

  2. Spider Glue Proteins Have Distinct Architectures Compared with Traditional Spidroin Family Members*

    Science.gov (United States)

    Vasanthavada, Keshav; Hu, Xiaoyi; Tuton-Blasingame, Tiffany; Hsia, Yang; Sampath, Sujatha; Pacheco, Ryan; Freeark, Jordan; Falick, Arnold M.; Tang, Simon; Fong, Justine; Kohler, Kristin; La Mattina-Hawkins, Coby; Vierra, Craig

    2012-01-01

    Adhesive spider glues are required to perform a variety of tasks, including web construction, prey capture, and locomotion. To date, little is known regarding the molecular and structural features of spider glue proteins, in particular bioadhesives that interconnect dragline or scaffolding silks during three-dimensional web construction. Here we use biochemical and structural approaches to identify and characterize two aggregate gland specific gene products, AgSF1 and AgSF2, and demonstrate that these proteins co-localize to the connection joints of both webs and wrapping silks spun from the black widow spider, Latrodectus hesperus. Protein architectures are markedly divergent between AgSF1 and AgSF2, as well as traditional spider silk fibroin family members, suggesting connection joints consist of a complex proteinaceous network. AgSF2 represents a nonglycosylated 40-kDa protein that has novel internal amino acid block repeats with the consensus sequence NVNVN embedded in a glycine-rich matrix. Analysis of the amino acid sequence of AgSF1 reveals pentameric QPGSG iterations that are similar to conserved modular elements within mammalian elastin, a rubber-like elastomeric protein that interfaces with collagen. Wet-spinning methodology using purified recombinant proteins show AgSF1 has the potential to self-assemble into fibers. X-ray fiber diffraction studies performed on these synthetic fibers reveal the presence of noncrystalline domains that resemble classical rubber networks. Collectively, these data support that the aggregate gland serves to extrude a protein mixture that contains substances that allow for the self-assembly of fiber-like structures that interface with dragline silks to mediate prey capture. PMID:22927444

  3. Spiders of Kerala Agricultural University Campus, Thrissur, Kerala, India

    Directory of Open Access Journals (Sweden)

    C. K. Adarsh

    2015-12-01

    Full Text Available A total of 86 species of spiders belonging to 56 genera of 20 families have been recorded from the Kerala Agricultural University (KAU campus, Thrissur, Kerala, southern India.  This represents 5.1% of the total spiders’ species and 33.33% of the total families of spiders recorded in India.  The dominant spider family at KAU campus is Araneidae with 18 species of nine genera. Salticidae is represented by 14 species of 13 genera.  Out of 252 endemic spiders of India, 16 have been reported from KAU campus.  Guild structure analysis shows spiders belonging to seven types of feeding guilds present in KAU campus.  Orb-web builders are the dominant feeding guild accounting for 34%, followed by stalkers (22%, ground runners (20%, ambushers (8%, scattered line weavers (8%, foliage runners (7% and sheet-web builders (1%. 

  4. Brown Recluse Spider

    Science.gov (United States)

    ... to a group of spiders commonly known as violin spiders or fiddlebacks. The characteristic fiddle-shaped pattern ... 4-19.1mm) • Color: Golden brown • A dark violin/fiddle shape (see top photo) is located on ...

  5. Spider Bites (For Parents)

    Science.gov (United States)

    ... body rash fever and chills fatigue Of a black widow spider bite: rigid, painful muscles within 8 hours no ... child was bitten by a brown recluse or black widow spider Think Prevention! Make sure garages, attics, and woodpiles ...

  6. On the new record of the sheet-web spider Erigonoplus foveatus comb. nov. from Slovakia, with comments on Erigonoplus simplex (Araneae: Linyphiidae

    Directory of Open Access Journals (Sweden)

    Hollá, Katarína

    2016-04-01

    Full Text Available Mecynargus foveatus (Dahl, 1912 was recorded in the territory of Slovakia for the first time. Within two years of spider research, a single adult male was collected by beating branches of Scots pine (Pinus sylvestris in the Borská nížina lowland. We also discovered that specimens of Erigonoplus simplex Millidge, 1979 from Bulgaria were misidentified as M. foveatus. Therefore, we suggest to consider E. simplex as a new record for Bulgaria and to exclude M. foveatus from the spider fauna of Bulgaria. A revised distribution of both species is presented and discussed. Based on the high similarity to Erigonoplus, M. foveatus is transferred to this genus as Erigonoplus foveatus (Dahl, 1912 comb. nov.

  7. The results of bone deformity correction using a spider frame with web-based software for lower extremity long bone deformities

    Directory of Open Access Journals (Sweden)

    Tekin Ali Çağrı

    2016-01-01

    Full Text Available Aim: To present the functional and radiological results and evaluate the effectiveness of a computer-assisted external fixator (spider frame in patients with lower extremity shortness and deformity. Materials and methods: The study comprised 17 patients (14 male, 3 female who were treated for lower extremity long bone deformity and shortness between 2012 and 2015 using a spider frame. The procedure’s level of difficulty was determined preoperatively using the Paley Scale. Postoperatively, the results for the patients who underwent tibial operations were evaluated using the Paley criteria modified by ASAMI, and the results for the patients who underwent femoral operations were evaluated according to the Paley scoring system. The evaluations were made by calculating the External Fixator and Distraction indexes. Results: The mean age of the patients was 24.58 years (range, 5–51 years. The spider frame was applied to the femur in 10 patients and to the tibia in seven. The mean follow-up period was 15 months (range, 6–31 months from the operation day, and the mean amount of lengthening was 3.0 cm (range, 1–6 cm. The mean duration of fixator application was 202.7 days (range, 104–300 days. The mean External Fixator Index was 98 days/cm (range, 42–265 days/cm. The mean Distraction Index was 10.49 days/cm (range, 10–14 days/cm. Conclusion: The computer-assisted external fixator system (spider frame achieves single-stage correction in cases of both deformity and shortness. The system can be applied easily, and because of its high-tech software, it offers the possibility of postoperative treatment of the deformity.

  8. The results of bone deformity correction using a spider frame with web-based software for lower extremity long bone deformities.

    Science.gov (United States)

    Tekin, Ali Çağrı; Çabuk, Haluk; Dedeoğlu, Süleyman Semih; Saygılı, Mehmet Selçuk; Adaş, Müjdat; Esenyel, Cem Zeki; Büyükkurt, Cem Dinçay; Tonbul, Murat

    2016-03-22

    To present the functional and radiological results and evaluate the effectiveness of a computer-assisted external fixator (spider frame) in patients with lower extremity shortness and deformity. The study comprised 17 patients (14 male, 3 female) who were treated for lower extremity long bone deformity and shortness between 2012 and 2015 using a spider frame. The procedure's level of difficulty was determined preoperatively using the Paley Scale. Postoperatively, the results for the patients who underwent tibial operations were evaluated using the Paley criteria modified by ASAMI, and the results for the patients who underwent femoral operations were evaluated according to the Paley scoring system. The evaluations were made by calculating the External Fixator and Distraction indexes. The mean age of the patients was 24.58 years (range, 5-51 years). The spider frame was applied to the femur in 10 patients and to the tibia in seven. The mean follow-up period was 15 months (range, 6-31 months) from the operation day, and the mean amount of lengthening was 3.0 cm (range, 1-6 cm). The mean duration of fixator application was 202.7 days (range, 104-300 days). The mean External Fixator Index was 98 days/cm (range, 42-265 days/cm). The mean Distraction Index was 10.49 days/cm (range, 10-14 days/cm). The computer-assisted external fixator system (spider frame) achieves single-stage correction in cases of both deformity and shortness. The system can be applied easily, and because of its high-tech software, it offers the possibility of postoperative treatment of the deformity.

  9. Spider Bites: First Aid

    Science.gov (United States)

    ... t had one in the last five years. Black widow spider You can usually identify a black widow spider by the hourglass marking on its belly. In ... in the South. Signs and symptoms of a black widow spider bite may include: At first, slight swelling and ...

  10. Variation in protein intake induces variation in spider silk expression.

    Directory of Open Access Journals (Sweden)

    Sean J Blamires

    Full Text Available BACKGROUND: It is energetically expensive to synthesize certain amino acids. The proteins (spidroins of spider major ampullate (MA silk, MaSp1 and MaSp2, differ in amino acid composition. Glutamine and proline are prevalent in MaSp2 and are expensive to synthesize. Since most orb web spiders express high proline silk they might preferentially attain the amino acids needed for silk from food and shift toward expressing more MaSp1 in their MA silk when starved. METHODOLOGY/PRINCIPAL FINDINGS: We fed three spiders; Argiope aetherea, Cyrtophora moluccensis and Leucauge blanda, high protein, low protein or no protein solutions. A. aetherea and L. blanda MA silks are high in proline, while C. moluccesnsis MA silks are low in proline. After 10 days of feeding we determined the amino acid compositions and mechanical properties of each species' MA silk and compared them between species and treatments with pre-treatment samples, accounting for ancestry. We found that the proline and glutamine of A. aetherea and L. blanda silks were affected by protein intake; significantly decreasing under the low and no protein intake treatments. Glutmaine composition in C. moluccensis silk was likewise affected by protein intake. However, the composition of proline in their MA silk was not significantly affected by protein intake. CONCLUSIONS: Our results suggest that protein limitation induces a shift toward different silk proteins with lower glutamine and/or proline content. Contradictions to the MaSp model lie in the findings that C. moluccensis MA silks did not experience a significant reduction in proline and A. aetherea did not experience a significant reduction in serine on low/no protein. The mechanical properties of the silks could not be explained by a MaSp1 expressional shift. Factors other than MaSp expression, such as the expression of spidroin-like orthologues, may impact on silk amino acid composition and spinning and glandular processes may impact

  11. A preliminary checklist of spiders (Araneae: Arachnida in Chinnar Wildlife Sanctuary, Western Ghats, India

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    C. K. Adarsh

    2016-04-01

    Full Text Available A preliminary study was conducted to document spider diversity in Chinnar Wildlife Sanctuary, Idukki District, Kerala State in southern India.  The study was conducted from October to November 2012.  A total of 101 species of spiders belonging to 65 genera from 29 families were identified from the sanctuary.  This accounted for 6.98% of Indian spider species, 17.81% of Indian spider genera and 48.33% of the spider families of India.  The dominant families were Lycosidae (11 species and Araneidae (10.  Two endemic genera of Indian spiders such as Annandaliella and Neoheterophrictus were found at Chinnar, each representing one species each, and belonging to the family Theraphosidae.  A guild structure analysis of the spiders revealed seven feeding guilds such as orb weavers, stalkers, ground runners, foliage runners, sheet web builders, space web builders and ambushers. 

  12. Heritability of defence and life-history traits in the two-spotted spider mite

    NARCIS (Netherlands)

    Tien, N.S.H.; Sabelis, M.W.; Egas, M.

    2009-01-01

    Background: Two-spotted spider mites hide against predatory mites in a web of self-produced sticky silk. The proteins invested in this shelter may reduce investment in reproduction. Questions: Do spider mite populations harbor genetic variation for web production, thereby enabling a response to

  13. Evidence for competition between carnivorous plants and spiders.

    Science.gov (United States)

    Jennings, David E; Krupa, James J; Raffel, Thomas R; Rohr, Jason R

    2010-10-07

    Several studies have demonstrated that competition between disparate taxa can be important in determining community structure, yet surprisingly, to our knowledge, no quantitative studies have been conducted on competition between carnivorous plants and animals. To examine potential competition between these taxa, we studied dietary and microhabitat overlap between pink sundews (Drosera capillaris) and wolf spiders (Lycosidae) in the field, and conducted a laboratory experiment examining the effects of wolf spiders on sundew fitness. In the field, we found that sundews and spiders had a high dietary overlap with each other and with the available arthropod prey. Associations between sundews and spiders depended on spatial scale: both sundews and spiders were found more frequently in quadrats with more abundant prey, but within quadrats, spiders constructed larger webs and located them further away from sundews as the total sundew trapping area increased, presumably to reduce competition. Spiders also constructed larger webs when fewer prey were available. In the laboratory, our experiment revealed that spiders can significantly reduce sundew fitness. Our findings suggest that members of the plant and animal kingdoms can and do compete.

  14. The canopy spiders (Araneae of the floodplain forest in Leipzig

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    Otto, Stefan

    2010-10-01

    Full Text Available The canopy spiders of the floodplain forest in Leipzig have become a focus of ecological studies in recent years. In 2006 we sampled 30 tree canopies in the ‘Burgaue’ nature reserve with pyrethrum knock-down fogging, recording 502 adult spiders belonging to 48 species and 11 families. Based on these data and the results of a previous fogging study, the studied spider community was dominated by forest and forest-edge species with a preference for the shrub and canopy strata as well as by spiders of the web spider feeding guild. The community structure was typical for arboreal spider communities from northern temperate forests but very different from communities in the tropics. Species richness and evenness were similar to the old growth near-primary Białowieża Forest in Poland. The checklist of 96 canopy spider species of the floodplain forest of Leipzig includes 54 additions to the spider fauna of Leipzig and vicinity by recent canopy studies and eight first canopy records for Leipzig from our field work. The theridiid Dipoena torva (Thorell, 1875 was recorded for the first time in Saxony. The floodplain forest of Leipzig sustains a large and species-rich arboreal spider community and is thus a valuable habitat for a large proportion of endangered species (12%.

  15. Dew drops on spider web appearance: a newly named pattern of IgG4 deposition in pemphigus with direct immunofluorescence

    Directory of Open Access Journals (Sweden)

    Marian Dmochowski

    2017-08-01

    Full Text Available Novel appearances in cutaneous pathology as well as mucocutaneous clinical signs are being described which indicate that this is still an attractive area for exploration. The H + E histology terms of “decorated tomb stoning” and “undecorated tomb stoning”, advocated by some pathologists, are misleading and as such should be avoided. Here, an appearance of IgG4 pemphigus deposits examined cost-effectively with direct immunofluorescence and suggested to be called “dew drops on spider web” is depicted in depth.

  16. Synthetic spider silk fibers spun from Pyriform Spidroin 2, a glue silk protein discovered in orb-weaving spider attachment discs.

    Science.gov (United States)

    Geurts, Paul; Zhao, Liang; Hsia, Yang; Gnesa, Eric; Tang, Simon; Jeffery, Felicia; La Mattina, Coby; Franz, Andreas; Larkin, Leah; Vierra, Craig

    2010-12-13

    Spider attachment disc silk fibers are spun into a viscous liquid that rapidly solidifies, gluing dragline silk fibers to substrates for locomotion or web construction. Here we report the identification and artificial spinning of a novel attachment disc glue silk fibroin, Pyriform Spidroin 2 (PySp2), from the golden orb weaver Nephila clavipes . MS studies support PySp2 is a constituent of the pyriform gland that is spun into attachment discs. Analysis of the PySp2 protein architecture reveals sequence divergence relative to the other silk family members, including the cob weaver glue silk fibroin PySp1. PySp2 contains internal block repeats that consist of two subrepeat units: one dominated by Ser, Gln, and Ala and the other Pro-rich. Artificial spinning of recombinant PySp2 truncations shows that the Ser-Gln-Ala-rich subrepeat is sufficient for the assembly of polymeric subunits and subsequent fiber formation. These studies support that both orb- and cob-weaving spiders have evolved highly polar block-repeat sequences with the ability to self-assemble into fibers, suggesting a strategy to allow fiber fabrication in the liquid environment of the attachment discs.

  17. Probing the Impact of Acidification on Spider Silk Assembly Kinetics.

    Science.gov (United States)

    Xu, Dian; Guo, Chengchen; Holland, Gregory P

    2015-07-13

    Spiders utilize fine adjustment of the physicochemical conditions within its silk spinning system to regulate spidroin assembly into solid silk fibers with outstanding mechanical properties. However, the exact mechanism about which this occurs remains elusive and is still hotly debated. In this study, the effect of acidification on spider silk assembly was investigated on native spidroins from the major ampullate (MA) gland fluid excised from Latrodectus hesperus (Black Widow) spiders. Incubating the protein-rich MA silk gland fluid at acidic pH conditions results in the formation of silk fibers that are 10-100 μm in length and ∼2 μm in diameter as judged by optical and electron microscope methods. The in vitro spider silk assembly kinetics were monitored as a function of pH with a (13)C solid-state MAS NMR approach. The results confirm the importance of acidic pH in the spider silk self-assembly process with observation of a sigmoidal nucleation-elongation kinetic profile. The rates of nucleation and elongation as well as the percentage of β-sheet structure in the grown fibers depend on the pH. These results confirm the importance of an acidic pH gradient along the spinning duct for spider silk formation and provide a powerful spectroscopic approach to probe the kinetics of spider silk formation under various biochemical conditions.

  18. Spider silk reinforced by graphene or carbon nanotubes

    Science.gov (United States)

    Lepore, Emiliano; Bosia, Federico; Bonaccorso, Francesco; Bruna, Matteo; Taioli, Simone; Garberoglio, Giovanni; Ferrari, Andrea C.; Pugno, Nicola Maria

    2017-09-01

    Spider silk has promising mechanical properties, since it conjugates high strength (~1.5 GPa) and toughness (~150 J g-1). Here, we report the production of silk incorporating graphene and carbon nanotubes by spider spinning, after feeding spiders with the corresponding aqueous dispersions. We observe an increment of the mechanical properties with respect to pristine silk, up to a fracture strength ~5.4 GPa and a toughness modulus ~1570 J g-1. This approach could be extended to other biological systems and lead to a new class of artificially modified biological, or ‘bionic’, materials.

  19. Programming spiders, bots, and aggregators in Java

    CERN Document Server

    Heaton, Jeff

    2006-01-01

    The content and services available on the web continue to be accessed mostly through direct human control. But this is changing. Increasingly, users rely on automated agents that save them time and effort by programmatically retrieving content, performing complex interactions, and aggregating data from diverse sources. Programming Spiders, Bots, and Aggregators in Java teaches you how to build and deploy a wide variety of these agents-from single-purpose bots to exploratory spiders to aggregators that present a unified view of information from multiple user accounts. You will quickly build on

  20. Phylogenetic reconstruction of the wolf spiders (Araneae: Lycosidae) using sequences from the 12S rRNA, 28S rRNA, and NADH1 genes: implications for classification, biogeography, and the evolution of web building behavior.

    Science.gov (United States)

    Murphy, Nicholas P; Framenau, Volker W; Donnellan, Stephen C; Harvey, Mark S; Park, Yung-Chul; Austin, Andrew D

    2006-03-01

    Current knowledge of the evolutionary relationships amongst the wolf spiders (Araneae: Lycosidae) is based on assessment of morphological similarity or phylogenetic analysis of a small number of taxa. In order to enhance the current understanding of lycosid relationships, phylogenies of 70 lycosid species were reconstructed by parsimony and Bayesian methods using three molecular markers; the mitochondrial genes 12S rRNA, NADH1, and the nuclear gene 28S rRNA. The resultant trees from the mitochondrial markers were used to assess the current taxonomic status of the Lycosidae and to assess the evolutionary history of sheet-web construction in the group. The results suggest that a number of genera are not monophyletic, including Lycosa, Arctosa, Alopecosa, and Artoria. At the subfamilial level, the status of Pardosinae needs to be re-assessed, and the position of a number of genera within their respective subfamilies is in doubt (e.g., Hippasa and Arctosa in Lycosinae and Xerolycosa, Aulonia and Hygrolycosa in Venoniinae). In addition, a major clade of strictly Australasian taxa may require the creation of a new subfamily. The analysis of sheet-web building in Lycosidae revealed that the interpretation of this trait as an ancestral state relies on two factors: (1) an asymmetrical model favoring the loss of sheet-webs and (2) that the suspended silken tube of Pirata is directly descended from sheet-web building. Paralogous copies of the nuclear 28S rRNA gene were sequenced, confounding the interpretation of the phylogenetic analysis and suggesting that a cautionary approach should be taken to the further use of this gene for lycosid phylogenetic analysis.

  1. An insect-feeding guild of carnivorous plants and spiders: does optimal foraging lead to competition or facilitation?

    Science.gov (United States)

    Crowley, Philip H; Hopper, Kevin R; Krupa, James J

    2013-12-01

    Carnivorous plants and spiders, along with their prey, are main players in an insect-feeding guild found on acidic, poorly drained soils in disturbed habitat. Darwin's notion that these plants must actively attract the insects they capture raises the possibility that spiders could benefit from proximity to prey hotspots created by the plants. Alternatively, carnivorous plants and spiders may deplete prey locally or (through insect redistribution) more widely, reducing each other's gain rates from predation. Here, we formulate and analyze a model of this guild, parameterized for carnivorous sundews and lycosid spiders, under assumptions of random movement by insects and optimal foraging by predators. Optimal foraging here involves gain maximization via trap investment (optimal web sizes and sundew trichome densities) and an ideal free distribution of spiders between areas with and without sundews. We find no facilitation: spiders and sundews engage in intense exploitation competition. Insect attraction by plants modestly increases sundew gain rates but slightly decreases spider gain rates. In the absence of population size structure, optimal spider redistribution between areas with and without sundews yields web sizes that are identical for all spiders, regardless of proximity to sundews. Web-building spiders have higher gain rates than wandering spiders in this system at high insect densities, but wandering spiders have the advantage at low insect densities. Results are complex, indicating that predictions to be tested empirically must be based on careful quantitative assessment.

  2. Spiders in caves.

    Science.gov (United States)

    Mammola, Stefano; Isaia, Marco

    2017-04-26

    World experts of different disciplines, from molecular biology to macro-ecology, recognize the value of cave ecosystems as ideal ecological and evolutionary laboratories. Among other subterranean taxa, spiders stand out as intriguing model organisms for their ecological role of top predators, their unique adaptations to the hypogean medium and their sensitivity to anthropogenic disturbance. As the description of the first eyeless spider ( Stalita taenaria ), an array of papers on subterranean spider biology, ecology and evolution has been published, but a comprehensive review on these topics is still lacking. We provide a general overview of the spider families recorded in hypogean habitats worldwide, we review the different adaptations of hypogean spiders to subterranean life, and we summarize the information gathered so far about their origin, population structure, ecology and conservation status. Finally, we point out the limits of the knowledge we currently have regarding hypogean spiders, aiming to stimulate future research. © 2017 The Author(s).

  3. Loss of legs: is it or not a handicap for an orb-weaving spider?

    Science.gov (United States)

    Pasquet, Alain; Anotaux, Mylène; Leborgne, Raymond

    2011-07-01

    Leg loss is a common phenomenon in spiders, and according to the species 5% to 40% of the adults can present at least one missing leg. There is no possibility of regeneration after adult moult and the animal must manage with its missing appendages until its death. With the loss of one or more legs, female orb-weaving spiders can be penalized twice: firstly, because the legs are necessary for web construction and secondly, the legs are essential for the control of the prey after its interception by the web. During development, spiders may be also penalized because regeneration has energetic costs that take away resources for survival, growth and reproduction. All these consequences should influence negatively the development of the spider and thus its fitness. We investigated the impact of leg loss in the orb-weaving spider, Zygiella x-notata by studying its frequency in a natural population and web building and prey capture behaviours in laboratory. In field populations, 9.5% to 13%, of the adult females presented the loss of one or more legs; the majority of individuals had lost only one leg (in 48% of cases, a first one). Leg loss seems to affect all the adult spiders, as there is no difference of mass between intact spiders and those with missing leg. Data obtained with laboratory-reared spiders, showed that the loss of legs due to the moult is rare (less than 1%). Considering changes in web design, spiders with missing legs decreased their silk investment, increased the distance between spiral turns but did not change the capture surface of the web. Under our laboratory experimental conditions, spiders with one or two lost legs did not present any difference in prey capture efficiency. In laboratory conditions, spiders with lost leg(s) did not show any difference in egg sac production or in longevity (adult lifespan) compared to intact spiders.

  4. Proximate mechanism of behavioral manipulation of an orb-weaver spider host by a parasitoid wasp.

    Directory of Open Access Journals (Sweden)

    Thiago Gechel Kloss

    Full Text Available Some ichneumonid wasps induce modifications in the web building behavior of their spider hosts to produce resistant "cocoon" webs. These structures hold and protect the wasp's cocoon during pupa development. The mechanism responsible for host manipulation probably involves the inoculation of psychotropic chemicals by the parasitoid larva during a specific developmental period. Recent studies indicate that some spiders build cocoon webs similar to those normally built immediately before ecdysis, suggesting that this substance might be a molting hormone or a precursor chemical of this hormone. Here, we report that Cyclosa spider species exhibiting modified behavior presented higher 20-OH-ecdysone levels than parasitized spiders acting normally or unparasitized individuals. We suggest that the lack of control that spiders have when constructing modified webs can be triggered by anachronic activation of ecdysis.

  5. Synthetic Spider Silk Production on a Laboratory Scale

    Science.gov (United States)

    Hsia, Yang; Gnesa, Eric; Pacheco, Ryan; Kohler, Kristin; Jeffery, Felicia; Vierra, Craig

    2012-01-01

    As society progresses and resources become scarcer, it is becoming increasingly important to cultivate new technologies that engineer next generation biomaterials with high performance properties. The development of these new structural materials must be rapid, cost-efficient and involve processing methodologies and products that are environmentally friendly and sustainable. Spiders spin a multitude of different fiber types with diverse mechanical properties, offering a rich source of next generation engineering materials for biomimicry that rival the best manmade and natural materials. Since the collection of large quantities of natural spider silk is impractical, synthetic silk production has the ability to provide scientists with access to an unlimited supply of threads. Therefore, if the spinning process can be streamlined and perfected, artificial spider fibers have the potential use for a broad range of applications ranging from body armor, surgical sutures, ropes and cables, tires, strings for musical instruments, and composites for aviation and aerospace technology. In order to advance the synthetic silk production process and to yield fibers that display low variance in their material properties from spin to spin, we developed a wet-spinning protocol that integrates expression of recombinant spider silk proteins in bacteria, purification and concentration of the proteins, followed by fiber extrusion and a mechanical post-spin treatment. This is the first visual representation that reveals a step-by-step process to spin and analyze artificial silk fibers on a laboratory scale. It also provides details to minimize the introduction of variability among fibers spun from the same spinning dope. Collectively, these methods will propel the process of artificial silk production, leading to higher quality fibers that surpass natural spider silks. PMID:22847722

  6. Host selection by a kleptobiotic spider

    Science.gov (United States)

    Hénaut, Yann; Delme, Juliette; Legal, Luc; Williams, Trevor

    2005-02-01

    Why do kleptobiotic spiders of the genus Argyrodes seem to be associated with spiders of the genus Nephila worldwide? Observations following introduction of experimental insect prey of different sizes and weights on to host webs revealed that: (1) small prey are more effectively retained on the web of Nephila clavipes than on the web of another common host, Leucauge venusta. (2) N. clavipes did not consume small prey that accumulated on the web whereas larger, heavier prey were enveloped and stored. (3) We observed clear partitioning of prey items between N. clavipes and Argyrodes spp.; diet selection by Argyrodes did not overlap with that of N. clavipes but closely overlapped with that of L. venusta. (4) L. venusta responds very quickly to prey impact whereas N. clavipes is slower, offering a temporal window of opportunity for Argyrodes foraging. (5) The ability of L. venusta to detect and respond to small items also means that it acts aggressively to Argyrodes spp., whereas N. clavipes does not. Consequently, food-acquisition behaviours of Argyrodes were clearly less risky with N. clavipes compared with L. venusta. We conclude that when a kleptobiotic organism has a choice of various host species, it will opt for the least risky host that presents the highest rate of availability of food items. The fact that Nephila species present such characteristics explains the worldwide association with Argyrodes kleptobiotic spiders.

  7. Spider Silk-CBD-Cellulose Nanocrystal Composites: Mechanism of Assembly.

    Science.gov (United States)

    Meirovitch, Sigal; Shtein, Zvi; Ben-Shalom, Tal; Lapidot, Shaul; Tamburu, Carmen; Hu, Xiao; Kluge, Jonathan A; Raviv, Uri; Kaplan, David L; Shoseyov, Oded

    2016-09-18

    The fabrication of cellulose-spider silk bio-nanocomposites comprised of cellulose nanocrystals (CNCs) and recombinant spider silk protein fused to a cellulose binding domain (CBD) is described. Silk-CBD successfully binds cellulose, and unlike recombinant silk alone, silk-CBD self-assembles into microfibrils even in the absence of CNCs. Silk-CBD-CNC composite sponges and films show changes in internal structure and CNC alignment related to the addition of silk-CBD. The silk-CBD sponges exhibit improved thermal and structural characteristics in comparison to control recombinant spider silk sponges. The glass transition temperature (Tg) of the silk-CBD sponge was higher than the control silk sponge and similar to native dragline spider silk fibers. Gel filtration analysis, dynamic light scattering (DLS), small angle X-ray scattering (SAXS) and cryo-transmission electron microscopy (TEM) indicated that silk-CBD, but not the recombinant silk control, formed a nematic liquid crystalline phase similar to that observed in native spider silk during the silk spinning process. Silk-CBD microfibrils spontaneously formed in solution upon ultrasonication. We suggest a model for silk-CBD assembly that implicates CBD in the central role of driving the dimerization of spider silk monomers, a process essential to the molecular assembly of spider-silk nanofibers and silk-CNC composites.

  8. Morphological evolution of spiders predicted by pendulum mechanics.

    Directory of Open Access Journals (Sweden)

    Jordi Moya-Laraño

    Full Text Available BACKGROUND: Animals have been hypothesized to benefit from pendulum mechanics during suspensory locomotion, in which the potential energy of gravity is converted into kinetic energy according to the energy-conservation principle. However, no convincing evidence has been found so far. Demonstrating that morphological evolution follows pendulum mechanics is important from a biomechanical point of view because during suspensory locomotion some morphological traits could be decoupled from gravity, thus allowing independent adaptive morphological evolution of these two traits when compared to animals that move standing on their legs; i.e., as inverted pendulums. If the evolution of body shape matches simple pendulum mechanics, animals that move suspending their bodies should evolve relatively longer legs which must confer high moving capabilities. METHODOLOGY/PRINCIPAL FINDINGS: We tested this hypothesis in spiders, a group of diverse terrestrial generalist predators in which suspensory locomotion has been lost and gained a few times independently during their evolutionary history. In spiders that hang upside-down from their webs, their legs have evolved disproportionately longer relative to their body sizes when compared to spiders that move standing on their legs. In addition, we show how disproportionately longer legs allow spiders to run faster during suspensory locomotion and how these same spiders run at a slower speed on the ground (i.e., as inverted pendulums. Finally, when suspensory spiders are induced to run on the ground, there is a clear trend in which larger suspensory spiders tend to run much more slowly than similar-size spiders that normally move as inverted pendulums (i.e., wandering spiders. CONCLUSIONS/SIGNIFICANCE: Several lines of evidence support the hypothesis that spiders have evolved according to the predictions of pendulum mechanics. These findings have potentially important ecological and evolutionary implications since

  9. Microdissection of black widow spider silk-producing glands.

    Science.gov (United States)

    Jeffery, Felicia; La Mattina, Coby; Tuton-Blasingame, Tiffany; Hsia, Yang; Gnesa, Eric; Zhao, Liang; Franz, Andreas; Vierra, Craig

    2011-01-11

    Modern spiders spin high-performance silk fibers with a broad range of biological functions, including locomotion, prey capture and protection of developing offspring. Spiders accomplish these tasks by spinning several distinct fiber types that have diverse mechanical properties. Such specialization of fiber types has occurred through the evolution of different silk-producing glands, which function as small biofactories. These biofactories manufacture and store large quantities of silk proteins for fiber production. Through a complex series of biochemical events, these silk proteins are converted from a liquid into a solid material upon extrusion. Mechanical studies have demonstrated that spider silks are stronger than high-tensile steel. Analyses to understand the relationship between the structure and function of spider silk threads have revealed that spider silk consists largely of proteins, or fibroins, that have block repeats within their protein sequences. Common molecular signatures that contribute to the incredible tensile strength and extensibility of spider silks are being unraveled through the analyses of translated silk cDNAs. Given the extraordinary material properties of spider silks, research labs across the globe are racing to understand and mimic the spinning process to produce synthetic silk fibers for commercial, military and industrial applications. One of the main challenges to spinning artificial spider silk in the research lab involves a complete understanding of the biochemical processes that occur during extrusion of the fibers from the silk-producing glands. Here we present a method for the isolation of the seven different silk-producing glands from the cobweaving black widow spider, which includes the major and minor ampullate glands [manufactures dragline and scaffolding silk], tubuliform [synthesizes egg case silk], flagelliform [unknown function in cob-weavers], aggregate [makes glue silk], aciniform [synthesizes prey wrapping and egg

  10. Linking Native and Invader Traits Explains Native Spider Population Responses to Plant Invasion.

    Directory of Open Access Journals (Sweden)

    Jennifer N Smith

    Full Text Available Theoretically, the functional traits of native species should determine how natives respond to invader-driven changes. To explore this idea, we simulated a large-scale plant invasion using dead spotted knapweed (Centaurea stoebe stems to determine if native spiders' web-building behaviors could explain differences in spider population responses to structural changes arising from C. stoebe invasion. After two years, irregular web-spiders were >30 times more abundant and orb weavers were >23 times more abundant on simulated invasion plots compared to controls. Additionally, irregular web-spiders on simulated invasion plots built webs that were 4.4 times larger and 5.0 times more likely to capture prey, leading to >2-fold increases in recruitment. Orb-weavers showed no differences in web size or prey captures between treatments. Web-spider responses to simulated invasion mimicked patterns following natural invasions, confirming that C. stoebe's architecture is likely the primary attribute driving native spider responses to these invasions. Differences in spider responses were attributable to differences in web construction behaviors relative to historic web substrate constraints. Orb-weavers in this system constructed webs between multiple plants, so they were limited by the overall quantity of native substrates but not by the architecture of individual native plant species. Irregular web-spiders built their webs within individual plants and were greatly constrained by the diminutive architecture of native plant substrates, so they were limited both by quantity and quality of native substrates. Evaluating native species traits in the context of invader-driven change can explain invasion outcomes and help to identify factors limiting native populations.

  11. Spider Communities and Biological Control in Native Habitats Surrounding Greenhouses

    Directory of Open Access Journals (Sweden)

    Belén Cotes

    2018-03-01

    Full Text Available The promotion of native vegetation as a habitat for natural enemies, which could increase their abundance and fitness, is especially useful in highly simplified settings such as Mediterranean greenhouse landscapes. Spiders as generalist predators may also be involved in intra-guild predation. However, the niche complementarity provided by spiders as a group means that increased spider diversity may facilitate complementary control actions. In this study, the interactions between spiders, the two major horticultural pests, Bemisia tabaci and Frankliniella occidentalis, and their naturally occurring predators and parasitoids were evaluated in a mix of 21 newly planted shrubs selected for habitat management in a highly disturbed horticultural system. The effects of all factors were evaluated using redundancy analysis (RDA and the generalized additive model (GAM to assess the statistical significance of abundance of spiders and pests. The GAM showed that the abundance of both pests had a significant effect on hunter spider’s abundance, whereas the abundance of B. tabaci, but not F. occidentalis, affected web-weavers’ abundance. Ordination analysis showed that spider abundance closely correlated with that of B. tabaci but not with that of F. occidentalis, suggesting that complementarity occurs, and thereby probability of biocontrol, with respect to the targeted pest B. tabaci, although the temporal patterns of the spiders differed from those of F. occidentalis. Conservation strategies involving the establishment of these native plants around greenhouses could be an effective way to reduce pest populations outdoors.

  12. Detritus decorations of an orb-weaving spider, Cyclosa mulmeinensis (Thorell): for food or camouflage?

    Science.gov (United States)

    Tan, Eunice J; Li, Daiqin

    2009-06-01

    Many species of the orb-web spider genus Cyclosa often adorn their webs with decorations of prey remains, egg sacs and/or plant detritus, termed ;detritus decorations'. These detritus decorations have been hypothesised to camouflage the spider from predators or prey and thus reduce predation risk or increase foraging success. In the present study, we tested these two alternative hypotheses simultaneously using two types of detritus decorations (prey remain and egg sac) built by Cyclosa mulmeinensis (Thorell). By monitoring the possible responses of predators to spiders on their webs with and without decorations in the field, we tested whether web decorations would reduce the mortality of spiders. Wasp predators were observed to fly in the vicinity of webs with decorations slightly more often than in the vicinity of webs without decorations but there were very few attacks on spiders by wasps. By comparing the insect interception rates of webs with and without decorations in the field, we tested whether web decorations would increase the foraging success. Webs decorated with prey remains or egg sacs intercepted more insects than those without in the field. By calculating colour contrasts of both prey-remain and egg-sac decorations against spiders viewed by bird (blue tits) and hymenopteran (e.g. wasps) predators as well as hymenopteran (bees) prey, we showed that C. mulmeinensis spiders on webs with egg-sac decorations were invisible to both hymenopteran prey and predators and bird predators over short and long distances. While spiders on webs with prey-remain decorations were invisible to both hymenopterans and birds over short distances, spiders on webs with prey-remain decorations were visible to both predators and prey over long distances. Our results thus suggest that decorating webs with prey remains and egg sacs in C. mulmeinensis may primarily function as camouflage to conceal the spider from insects rather than as prey attractants, possibly contributing to

  13. Tarantula spider bite

    Science.gov (United States)

    ... spider belongs, contains the largest number of venomous species known. This article is for information only. DO ... Wash the area with soap and water. Place ice (wrapped in a clean cloth or other covering) ...

  14. Black widow spider

    Science.gov (United States)

    ... spider belongs, contains the largest number of venomous species known. This article is for information only. DO ... Clean the area with soap and water. Wrap ice in a clean cloth and place it on ...

  15. Space spider crane

    Science.gov (United States)

    Macconochie, Ian O. (Inventor); Mikulas, Martin M., Jr. (Inventor); Pennington, Jack E. (Inventor); Kinkead, Rebecca L. (Inventor); Bryan, Charles F., Jr. (Inventor)

    1988-01-01

    A space spider crane for the movement, placement, and or assembly of various components on or in the vicinity of a space structure is described. As permanent space structures are utilized by the space program, a means will be required to transport cargo and perform various repair tasks. A space spider crane comprising a small central body with attached manipulators and legs fulfills this requirement. The manipulators may be equipped with constant pressure gripping end effectors or tools to accomplish various repair tasks. The legs are also equipped with constant pressure gripping end effectors to grip the space structure. Control of the space spider crane may be achieved either by computer software or a remotely situated human operator, who maintains visual contact via television cameras mounted on the space spider crane. One possible walking program consists of a parallel motion walking program whereby the small central body alternatively leans forward and backward relative to end effectors.

  16. Plasticity in major ampullate silk production in relation to spider phylogeny and ecology.

    Directory of Open Access Journals (Sweden)

    Cecilia Boutry

    Full Text Available Spider major ampullate silk is a high-performance biomaterial that has received much attention. However, most studies ignore plasticity in silk properties. A better understanding of silk plasticity could clarify the relative importance of chemical composition versus processing of silk dope for silk properties. It could also provide insight into how control of silk properties relates to spider ecology and silk uses. We compared silk plasticity (defined as variation in the properties of silk spun by a spider under different conditions between three spider clades in relation to their anatomy and silk biochemistry. We found that silk plasticity exists in RTA clade and orbicularian spiders, two clades that differ in their silk biochemistry. Orbiculariae seem less dependent on external spinning conditions. They probably use a valve in their spinning duct to control friction forces and speed during spinning. Our results suggest that plasticity results from different processing of the silk dope in the spinning duct. Orbicularian spiders seem to display better control of silk properties, perhaps in relation to their more complex spinning duct valve.

  17. Early events in the evolution of spider silk genes.

    Directory of Open Access Journals (Sweden)

    James Starrett

    Full Text Available Silk spinning is essential to spider ecology and has had a key role in the expansive diversification of spiders. Silk is composed primarily of proteins called spidroins, which are encoded by a multi-gene family. Spidroins have been studied extensively in the derived clade, Orbiculariae (orb-weavers, from the suborder Araneomorphae ('true spiders'. Orbicularians produce a suite of different silks, and underlying this repertoire is a history of duplication and spidroin gene divergence. A second class of silk proteins, Egg Case Proteins (ECPs, is known only from the orbicularian species, Lactrodectus hesperus (Western black widow. In L. hesperus, ECPs bond with tubuliform spidroins to form egg case silk fibers. Because most of the phylogenetic diversity of spiders has not been sampled for their silk genes, there is limited understanding of spidroin gene family history and the prevalence of ECPs. Silk genes have not been reported from the suborder Mesothelae (segmented spiders, which diverged from all other spiders >380 million years ago, and sampling from Mygalomorphae (tarantulas, trapdoor spiders and basal araneomorph lineages is sparse. In comparison to orbicularians, mesotheles and mygalomorphs have a simpler silk biology and thus are hypothesized to have less diversity of silk genes. Here, we present cDNAs synthesized from the silk glands of six mygalomorph species, a mesothele, and a non-orbicularian araneomorph, and uncover a surprisingly rich silk gene diversity. In particular, we find ECP homologs in the mesothele, suggesting that ECPs were present in the common ancestor of extant spiders, and originally were not specialized to complex with tubuliform spidroins. Furthermore, gene-tree/species-tree reconciliation analysis reveals that numerous spidroin gene duplications occurred after the split between Mesothelae and Opisthothelae (Mygalomorphae plus Araneomorphae. We use the spidroin gene tree to reconstruct the evolution of amino acid

  18. Early events in the evolution of spider silk genes.

    Science.gov (United States)

    Starrett, James; Garb, Jessica E; Kuelbs, Amanda; Azubuike, Ugochi O; Hayashi, Cheryl Y

    2012-01-01

    Silk spinning is essential to spider ecology and has had a key role in the expansive diversification of spiders. Silk is composed primarily of proteins called spidroins, which are encoded by a multi-gene family. Spidroins have been studied extensively in the derived clade, Orbiculariae (orb-weavers), from the suborder Araneomorphae ('true spiders'). Orbicularians produce a suite of different silks, and underlying this repertoire is a history of duplication and spidroin gene divergence. A second class of silk proteins, Egg Case Proteins (ECPs), is known only from the orbicularian species, Lactrodectus hesperus (Western black widow). In L. hesperus, ECPs bond with tubuliform spidroins to form egg case silk fibers. Because most of the phylogenetic diversity of spiders has not been sampled for their silk genes, there is limited understanding of spidroin gene family history and the prevalence of ECPs. Silk genes have not been reported from the suborder Mesothelae (segmented spiders), which diverged from all other spiders >380 million years ago, and sampling from Mygalomorphae (tarantulas, trapdoor spiders) and basal araneomorph lineages is sparse. In comparison to orbicularians, mesotheles and mygalomorphs have a simpler silk biology and thus are hypothesized to have less diversity of silk genes. Here, we present cDNAs synthesized from the silk glands of six mygalomorph species, a mesothele, and a non-orbicularian araneomorph, and uncover a surprisingly rich silk gene diversity. In particular, we find ECP homologs in the mesothele, suggesting that ECPs were present in the common ancestor of extant spiders, and originally were not specialized to complex with tubuliform spidroins. Furthermore, gene-tree/species-tree reconciliation analysis reveals that numerous spidroin gene duplications occurred after the split between Mesothelae and Opisthothelae (Mygalomorphae plus Araneomorphae). We use the spidroin gene tree to reconstruct the evolution of amino acid compositions of

  19. Adhesion modulation using glue droplet spreading in spider capture silk.

    Science.gov (United States)

    Amarpuri, Gaurav; Zhang, Ci; Blackledge, Todd A; Dhinojwala, Ali

    2017-05-01

    Orb web spiders use sticky capture spiral silk to retain prey in webs. Capture spiral silk is composed of an axial fibre of flagelliform silk covered with glue droplets that are arranged in a beads-on-a-string morphology that allows multiple droplets to simultaneously extend and resist pull off. Previous studies showed that the adhesion of capture silk is responsive to environmental humidity, increasing up to an optimum humidity that varied among different spider species. The maximum adhesion was hypothesized to occur when the viscoelasticity of the glue optimized contributions from glue spreading and bulk cohesion. In this study, we show how glue droplet shape during peeling contributes significantly to capture silk adhesion. Both overspreading and underspreading of glue droplets reduces adhesion through changes in crack propagation and failure regime. Understanding the mechanism of stimuli-responsive adhesion of spider capture silk will lead to new designs for smarter adhesives. © 2017 The Author(s).

  20. Aplikasi Web Crawler Untuk Web Content Pada Mobile Phone

    OpenAIRE

    Sarwosri, Sarwosri; Basori, Ahmad Hoirul; Surastyo, Wahyu Budi

    2009-01-01

    Crawling is the process behind a search engine, which served through the World Wide Web in a structured and with certain ethics. Applications that run the crawling process is called Web Crawler, also called web spider or web robot. The growth of mobile search services provider, followed by growth of a web crawler that can browse web pages in mobile content type. Crawler Web applications can be accessed by mobile devices and only web pages that type Mobile Content to be explored is the Web Cra...

  1. Structural, optical, electrochemical and photovoltaic studies of spider web like Silver Indium Diselenide Quantum dots synthesized by ligand mediated colloidal sol-gel approach

    Science.gov (United States)

    Adhikari, Tham; Pathak, Dinesh; Wagner, Tomas; Jambor, Roman; Jabeen, Uzma; Aamir, Muhammad; Nunzi, Jean-Michel

    2017-11-01

    Silver indium diselenide quantum dots were successively synthesized by colloidal sol-gel method by chelating with organic ligand oleylamine (OLA). The particle size was studied by transmission electron microscopy (TEM) and the size was found about 10 nm. X-ray diffraction (XRD) was used to study crystalline structure of the nanocrystals. The grain size and morphology were further studied by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The elemental composition was studied by X-ray photon electron spectroscopy (XPS) and energy dispersive x-ray spectroscopy (EDAX). The capping property of OLA in nanocrystal was also demonstrated by Fourier Transform Infrared spectroscopy (FTIR). The band gap was calculated from both cyclic voltammetry and optical absorption and suggest quantum confinement. The solution processed bilayer thin film solar cells were fabricated with n-type Zinc oxide using doctor blading/spin coating method and their photovoltaic performance was studied. The best device sintered at 450 °C showed an efficiency 0.75% with current density of 4.54 mAcm-2, open-circuit voltage 0.44 V and fill factor 39.4%.

  2. Company profile: Spider stories.

    Science.gov (United States)

    Giuliani, Andrea

    2008-06-01

    SpiderBiotech is a biotech company that has carried out extensive research and development on peptide-based anti-infectives, with five people involved in R&D activities and a strong network of industrial and academic partners experienced in the field of anti-infectives. SpiderBiotech has also created a proprietary library of bioactive peptides and lipopeptides (both linear and dendrimeric) active against bacterial and viral infections. At the moment they have two ongoing projects: the most advanced is focused on the development of a panel of peptide based antibiotics. The second project is related to novel antiviral drugs to treat acyclovir resistant Herpes virus infections.

  3. Composition and Function of Spider Glues Maintained During the Evolution of Cobwebs.

    Science.gov (United States)

    Jain, Dharamdeep; Zhang, Ci; Cool, Lydia Rose; Blackledge, Todd A; Wesdemiotis, Chrys; Miyoshi, Toshikazu; Dhinojwala, Ali

    2015-10-12

    Capture silks are an interesting class of biological glues that help spiders subdue their prey. Viscid capture silk produced by the orb web spiders is a combination of hygroscopic salts that aid in water uptake and interact with adhesive glycoproteins to make them soft and sticky. The orb was a stepping stone to the evolution of new web types, but little is known about the adhesives in these webs. For instance, cobweb spiders evolved from orb-weaving ancestors and utilize glue in specialized sticky gumfoot threads rather than an elastic spiral. Early investigation suggests that gumfoot adhesives are quite different viscid glues because they lack a visible glycoprotein core, act as viscoelastic fluids rather than solids, and are largely invariant to humidity. Here, we use spectroscopic and staining methods to show that the gumfoot silk produced by Latrodectus hesperus (western black widow) is composed of hygroscopic organic salts and water insoluble glycoproteins, similar to viscid silk, in addition to a low concentration of spider coating peptides reported before. Our adhesion studies reveal that the organic salts play an important role in adhesion, similar to that seen in orb web spiders, but modulating function at much lower humidity. Our work shows more similarities in the viscid silk produced by orb web and cobweb spiders than previously anticipated and provide guidelines for developing synthetic adhesives that can work in dry to humid environments.

  4. Black widow spider envenomation.

    Science.gov (United States)

    Peterson, Michael E

    2006-11-01

    Black widow spiders are found throughout the continental United States and north into the southern Canadian provinces. Male black widow spiders are of little medical importance. Female black widow spiders can be 20 times larger than males. The female can be identified by the hourglass pattern, red or orange in color, on the ventral aspect of her shiny, globose black abdomen. Black widow spiders control the amount of venom they inject; an estimated 15% of bites to humans are non-envenomating. Cats are very sensitive to the venom and deaths are common. Dogs have severe clinical signs but are considered more resistant than cats. A single bite is capable of delivering a lethal dose of venom to companion animals. There are several toxic components consisting of five or six biologically active proteins. These include a potent mammalian neurotoxin called alpha-latrotoxin, which induces neurotransmitter release from nerve terminals. Acetylcholine, noradrenalin, dopamine, glutamate, and enkephalin systems are all susceptible to the toxin. Onset of clinical signs usually occurs during the first 8 hours post envenomation. The condition is extremely painful in moderate to severe envenomations. Abdominal rigidity without tenderness is a hallmark sign of Latrodectus envenomation. In cats, paralytic signs may occur early and are particularly marked. Hypertension is a significant threat. First aid is of no value in the treatment. The primary treatment for black widow spider envenomation is the administration of specific antivenin, which provides the most permanent and quickest relief of the envenomation syndrome, usually within 30 minutes of infusion. The prognosis of Latrodectus envenomation is uncertain of several days, and complete recovery may take weeks.

  5. A Spider That Lays Its Eggs in Rows

    Directory of Open Access Journals (Sweden)

    Robert L. Edwards

    2000-01-01

    Full Text Available The small (2.5-3.0 mm, colorful metine spider, Homalometa nigritarsis Simon 1897, Family Tetragnathidae, has previously been reported from northern Mexico, Panama and the southern islands of the Lesser Antilles (Levi 1986. In the rain forest of northeastern Puerto Rico it is most frequently found with webbing on the larger outer concave surfaces of pendulous leaves. H. nigritarsis typically makes a circular, relatively flat retreat within which the female deposits two parallel rows of naked eggs. The rows are produced at intervals; as one row hatches another replaces it shortly thereafter. Evidence of up to four generations of rows has been observed. Above the retreat, and closely aligned with it, the spider builds a nearly invisible, delicate orb web, typically from edge to edge of the leaf (Fig. 1a and b. While retaining the traditional orb-web, H. nigritarsis has adopted a unique habitat and set of life history features.

  6. Pyriform spidroin 1, a novel member of the silk gene family that anchors dragline silk fibers in attachment discs of the black widow spider, Latrodectus hesperus.

    Science.gov (United States)

    Blasingame, Eric; Tuton-Blasingame, Tiffany; Larkin, Leah; Falick, Arnold M; Zhao, Liang; Fong, Justine; Vaidyanathan, Veena; Visperas, Anabelle; Geurts, Paul; Hu, Xiaoyi; La Mattina, Coby; Vierra, Craig

    2009-10-16

    Spiders spin high performance threads that have diverse mechanical properties for specific biological applications. To better understand the molecular mechanism by which spiders anchor their threads to a solid support, we solubilized the attachment discs from black widow spiders and performed in-solution tryptic digests followed by MS/MS analysis to identify novel peptides derived from glue silks. Combining matrix-assisted laser desorption ionization tandem time-of-flight mass spectrometry and cDNA library screening, we isolated a novel member of the silk gene family called pysp1 and demonstrate that its protein product is assembled into the attachment disc silks. Alignment of the PySp1 amino acid sequence to other fibroins revealed conservation in the non-repetitive C-terminal region of the silk family. MS/MS analysis also confirmed the presence of MaSp1 and MaSp2, two important components of dragline silks, anchored within the attachment disc materials. Characterization of the ultrastructure of attachment discs using scanning electron microscopy studies support the localization of PySp1 to small diameter fibers embedded in a glue-like cement, which network with large diameter dragline silk threads, producing a strong, adhesive material. Consistent with elevated PySp1 mRNA levels detected in the pyriform gland, MS analysis of the luminal contents extracted from the pyriform gland after tryptic digestion support the assertion that PySp1 represents one of the major constituents manufactured in the pyriform gland. Taken together, our data demonstrate that PySp1 is spun into attachment disc silks to help affix dragline fibers to substrates, a critical function during spider web construction for prey capture and locomotion.

  7. Pyriform Spidroin 1, a Novel Member of the Silk Gene Family That Anchors Dragline Silk Fibers in Attachment Discs of the Black Widow Spider, Latrodectus hesperus*

    Science.gov (United States)

    Blasingame, Eric; Tuton-Blasingame, Tiffany; Larkin, Leah; Falick, Arnold M.; Zhao, Liang; Fong, Justine; Vaidyanathan, Veena; Visperas, Anabelle; Geurts, Paul; Hu, Xiaoyi; La Mattina, Coby; Vierra, Craig

    2009-01-01

    Spiders spin high performance threads that have diverse mechanical properties for specific biological applications. To better understand the molecular mechanism by which spiders anchor their threads to a solid support, we solubilized the attachment discs from black widow spiders and performed in-solution tryptic digests followed by MS/MS analysis to identify novel peptides derived from glue silks. Combining matrix-assisted laser desorption ionization tandem time-of-flight mass spectrometry and cDNA library screening, we isolated a novel member of the silk gene family called pysp1 and demonstrate that its protein product is assembled into the attachment disc silks. Alignment of the PySp1 amino acid sequence to other fibroins revealed conservation in the non-repetitive C-terminal region of the silk family. MS/MS analysis also confirmed the presence of MaSp1 and MaSp2, two important components of dragline silks, anchored within the attachment disc materials. Characterization of the ultrastructure of attachment discs using scanning electron microscopy studies support the localization of PySp1 to small diameter fibers embedded in a glue-like cement, which network with large diameter dragline silk threads, producing a strong, adhesive material. Consistent with elevated PySp1 mRNA levels detected in the pyriform gland, MS analysis of the luminal contents extracted from the pyriform gland after tryptic digestion support the assertion that PySp1 represents one of the major constituents manufactured in the pyriform gland. Taken together, our data demonstrate that PySp1 is spun into attachment disc silks to help affix dragline fibers to substrates, a critical function during spider web construction for prey capture and locomotion. PMID:19666476

  8. Biological control of two-spotted spider mites using phytoseiid predators

    OpenAIRE

    Sabelis, M.W.

    1982-01-01

    The searching behaviour of individual predators of four phytoseiid species ( Phytoseiulus persimilis , Amblyseius p o tentillae , Amblyseius bibens , Metaseiulus occidentalis ) is investigated in relation to the two-spotted spider mite ( Tetranychus urticae ), which infests greenhouse roses. Especially the role of spider- mite webbing in the predator-prey relation is s...

  9. Lyriform slit sense organs on the pedipalps and spinnerets of spiders

    Indian Academy of Sciences (India)

    One LSSO is found only on anterior spinnerets and it is a common feature observed among spiders, irrespective of the variations in web building behaviour. The orb-weaving araneid Argiope pulchella, however, has two LSSOs on the anterior spinneret. As non-web builders and orb weavers do not differ markedly in terms ...

  10. Reversible myocarditis after spider bite.

    Science.gov (United States)

    Kara, Hasan; Ak, Ahmet; Bayir, Aysegul; Avci, Ahmet

    2013-04-08

    Black widow spiders (Latrodectus tredecimguttatus) are poisonous spiders endemic in Turkey. Latrodectus bites may cause myocarditis with increased cardiac enzymes. We treated two men (aged 20 and 33 years) who had myocarditis after black spider bites with leucocytosis and elevated levels of troponin I, creatine kinase and creatine kinase-MB fraction. Both patients had normal results on an ECG, and one patient had abnormal echocardiography with minimal left ventricular wall movement disorder. Both patients were hospitalised in the intensive care unit and treated with intravenous fluids, analgesics, spasmolytic drugs, tetanus prophylaxis and cardiac monitoring. The levels of troponin I, creatine kinase and creatine kinase-MB fraction improved, and the patients were discharged home on the third and fifth hospital day without complications. Myocarditis after a Latrodectus bite is rare, but may be associated with serious complications. Therefore, in regions endemic with Latrodectus spiders, prudent treatment of spider bites may include cardiac evaluation and monitoring.

  11. Functional relations between locomotor performance traits in spiders and implications for evolutionary hypotheses

    Directory of Open Access Journals (Sweden)

    Taylor Phillip W

    2010-11-01

    Full Text Available Abstract Background Locomotor performance in ecologically relevant activities is often linked to individual fitness. Recent controversy over evolution of extreme sexual size dimorphism (SSD in spiders centres on the relationship between size and locomotor capacity in males. Advantages for large males running over horizontal surfaces and small males climbing vertically have been proposed. Models have implicitly treated running and climbing as functionally distinct activities and failed to consider the possibility that they reflect common underlying capacities. Findings We examine the relationship between maximum climbing and running performance in males of three spider species. Maximum running and climbing speeds were positively related in two orb-web spiders with high SSD (Argiope keyserlingi and Nephila plumipes, indicating that for these species assays of running and climbing largely reveal the same underlying capacities. Running and climbing speeds were not related in a jumping spider with low SSD (Jacksonoides queenslandica. We found no evidence of a performance trade-off between these activities. Conclusions In the web-spiders A. keyserlingi and N. plumipes good runners were also good climbers. This indicates that climbing and running largely represent a single locomotor performance characteristic in these spiders, but this was not the case for the jumping spider J. queenslandica. There was no evidence of a trade-off between maximum running and climbing speeds in these spiders. We highlight the need to establish the relationship between apparently disparate locomotor activities when testing alternative hypotheses that yield predictions about different locomotor activities. Analysis of slopes suggests greater potential for an evolutionary response on performance in the horizontal compared to vertical context in these spiders.

  12. Evolution of stenophagy in spiders (Araneae): evidence based on the comparative analysis of spider diets.

    Science.gov (United States)

    Pekár, Stano; Coddington, Jonathan A; Blackledge, Todd A

    2012-03-01

    Stenophagy (narrow diet breadth) represents an extreme of trophic specialization in carnivores, but little is known about the forces driving its evolution. We used spiders, the most diversified group of terrestrial predators, to investigate whether stenophagy (1) promoted diversification; (2) was phylogenetically conserved and evolutionarily derived state; and (3) was determined either by geographical distribution and foraging guild. We used published data on the prey of almost 600 species. Six categories of stenophagy were found: myrmecophagy, araneophagy, lepidopterophagy, termitophagy, dipterophagy, and crustaceophagy. We found that the species diversity of euryphagous genera and families was similar to stenophagous genera and families. At the family level, stenophagy evolved repeatedly and independently. Within families, the basal condition was oligophagy or euryphagy. Most types of stenophagy were clearly derived: myrmecophagy in Zodariidae; lepidopterophagy in Araneidae; dipterophagy in Theridiidae. In contrast, araneophagy was confined to basal and intermediate lineages, suggesting its ancestral condition. The diet breadth of species from the tropics and subtropics was less diverse than species from the temperate zone. Diet breadth was lower in cursorial spiders compared to web-building species. Thus, the evolution of stenophagy in spiders appears to be complex and governed by phylogeny as well as by ecological determinants. © 2011 The Author(s). Evolution© 2011 The Society for the Study of Evolution.

  13. Black widow spider and brown recluse spider bites in Texas from 1998 through 2002.

    Science.gov (United States)

    Forrester, Mathias B; Stanley, Sharilyn K

    2003-10-01

    Black widow spiders and brown recluse spiders are of medical importance to humans in the US. However, these spiders differ in their habits, habitat, and the clinical effects and treatment of their bite. This study used data from human exposure calls to poison centers in Texas to compare the epidemioloy of bites from these 2 spiders. During 1998-2002, 760 black widow spider bites and 1,369 brown recluse spider bites were reported. Black widow spider bite penetrance demonstrated no secular trend during this time period while the penetrance of brown recluse spider bites increased. A higher percentage of black widow spider bites occurred among males, while a higher proportion of brown recluse spider bites were reported for females. Black widow spider bites most frequently had mild outcomes while brown recluse spider bites most often had moderate outcomes. The majority of reported bites for both types of spider occurred at the patient's own residence, although the percentage was lower for black widow spiders. Seasonal trends were noted for both black widow and brown recluse spiders. The highest penetrance of black widow spider bites was observed in western Texas while the highest penetrance of brown recluse spider bites was observed in central Texas. This information is useful for identifying those populations at greatest risk for the respective spider bites.

  14. Black widow spider bite.

    Science.gov (United States)

    Kobernick, M

    1984-05-01

    Latrodectus mactans has now invaded towns and cities. The spider's venom is a neurotoxin that causes little local reaction but produces pain and spasm in large skeletal muscle groups within 30 minutes to three hours after the bite. Severe envenomation may result in respiratory failure and coma. First aid is of no value. Muscle relaxants are useful in treatment, as is calcium gluconate. Antivenin is indicated for high-risk victims, such as those with hypertension and persons younger than 16 or older than 60 years of age.

  15. A Tank Bromeliad Favors Spider Presence in a Neotropical Inundated Forest.

    Directory of Open Access Journals (Sweden)

    Yann Hénaut

    Full Text Available Tank bromeliads are good models for understanding how climate change may affect biotic associations. We studied the relationships between spiders, the epiphytic tank bromeliad, Aechmea bracteata, and its associated ants in an inundated forest in Quintana Roo, Mexico, during a drought period while, exceptionally, this forest was dry and then during the flooding that followed. We compared spider abundance and diversity between 'Aechmea-areas' and 'control-areas' of the same surface area. We recorded six spider families: the Dipluridae, Ctenidae, Salticidae, Araneidae, Tetragnathidae and Linyphiidae among which the funnel-web tarantula, Ischnothele caudata, the only Dipluridae noted, was the most abundant. During the drought period, the spiders were more numerous in the Aechmea-areas than in the control-areas, but they were not obligatorily associated with the Aechmea. During the subsequent flooding, the spiders were concentrated in the A. bracteata patches, particularly those sheltering an ant colony. Also, a kind of specificity existed between certain spider taxa and ant species, but varied between the drought period and subsequent flooding. We conclude that climatic events modulate the relationship between A. bracteata patches and their associated fauna. Tank bromeliads, previously considered only for their ecological importance in supplying food and water during drought, may also be considered refuges for spiders during flooding. More generally, tank bromeliads have an important role in preserving non-specialized fauna in inundated forests.

  16. 'Natural experiment' demonstrates top-down control of spiders by birds on a landscape level.

    Directory of Open Access Journals (Sweden)

    Haldre Rogers

    Full Text Available The combination of small-scale manipulative experiments and large-scale natural experiments provides a powerful approach for demonstrating the importance of top-down trophic control on the ecosystem scale. The most compelling natural experiments have come from studies examining the landscape-scale loss of apex predators like sea otters, wolves, fish and land crabs. Birds are dominant apex predators in terrestrial systems around the world, yet all studies on their role as predators have come from small-scale experiments; the top-down impact of bird loss on their arthropod prey has yet to be examined at a landscape scale. Here, we use a unique natural experiment, the extirpation of insectivorous birds from nearly all forests on the island of Guam by the invasive brown tree snake, to produce the first assessment of the impacts of bird loss on their prey. We focused on spiders because experimental studies showed a consistent top-down effect of birds on spiders. We conducted spider web surveys in native forest on Guam and three nearby islands with healthy bird populations. Spider web densities on the island of Guam were 40 times greater than densities on islands with birds during the wet season, and 2.3 times greater during the dry season. These results confirm the general trend from manipulative experiments conducted in other systems however, the effect size was much greater in this natural experiment than in most manipulative experiments. In addition, bird loss appears to have removed the seasonality of spider webs and led to larger webs in at least one spider species in the forests of Guam than on nearby islands with birds. We discuss several possible mechanisms for the observed changes. Overall, our results suggest that effect sizes from smaller-scale experimental studies may significantly underestimate the impact of bird loss on spider density as demonstrated by this large-scale natural experiment.

  17. Composition and Humidity Response of the Black Widow Spider's Gumfoot Silk and its Implications on Adhesion

    Science.gov (United States)

    Jain, Dharamdeep; Zhang, Ci; Cool, Lydia Rose; Blackledge, Todd. A.; Wesdemiotis, Chrys; Miyoshi, Toshikazu; Dhinojwala, Ali

    Humidity plays an important part in the performance of biomaterials such as pollen, gecko toe, wheat awns, bird feathers and dragline silk. Capture silk produced by web building spiders form an interesting class of humidity responsive biological glues. The adhesive properties of the widely studied `viscid silk' produced by orbweb-weaving spiders is highly humidity sensitive. On the other hand, relatively less is known about the dependence of composition and humidity response towards adhesion for `gumfoot' silk produced by cobweb-weaving spiders. In the present study, we investigate the gumfoot silk produced by Black Widow using adhesion mechanics, microscopy and spectroscopic methods. The results show the presence of hygroscopic salts, glycoproteins and previously known spider coating peptides in silk and their importance in the humidity response and adhesion. The current study elucidates the role of constituents of capture silk in its adhesion mechanism and offers insights to novel ways for fabricating bio-inspired adhesives.

  18. A check list of the spider fauna of the Karoo National Park, South Africa (Arachnida: Araneae

    Directory of Open Access Journals (Sweden)

    Anna S. Dippenaar-Schoeman

    1999-07-01

    Full Text Available A check list of the spider species of the Karoo National Park collected over a period of 10 years is presented. Thirty-eight families, represented by 102 genera and 116 species have been collected. Of these species, 76 (66.4 were wanderers and 39 (33.6 web builders. The Araneidae have the highest number of species (14 followed by the Thomisidae (10 and the Gnaphosidae (8, while 14 families are represented by a single species. Information on spider guilds, their habitat preference and web types is provided. This study forms part of the South African National Survey of Arachnida (SANSA.

  19. Riparian spiders as sentinels of polychlorinated biphenyl contamination across heterogeneous aquatic ecosystems.

    Science.gov (United States)

    Kraus, Johanna M; Gibson, Polly P; Walters, David M; Mills, Marc A

    2017-05-01

    Riparian spiders are being used increasingly to track spatial patterns of contaminants in and fluxing from aquatic ecosystems. However, our understanding of the circumstances under which spiders are effective sentinels of aquatic pollution is limited. The present study tests the hypothesis that riparian spiders may be effectively used to track spatial patterns of sediment pollution by polychlorinated biphenyls (PCBs) in aquatic ecosystems with high habitat heterogeneity. The spatial pattern of ΣPCB concentrations in 2 common families of riparian spiders sampled in 2011 to 2013 generally tracked spatial variation in sediment ΣPCBs across all sites within the Manistique River Great Lakes Area of Concern (AOC), a rivermouth ecosystem located on the south shore of the Upper Peninsula, Manistique (MI, USA) that includes harbor, river, backwater, and lake habitats. Sediment ΣPCB concentrations normalized for total organic carbon explained 41% of the variation in lipid-normalized spider ΣPCB concentrations across 11 sites. Furthermore, 2 common riparian spider taxa (Araneidae and Tetragnathidae) were highly correlated (r 2  > 0.78) and had similar mean ΣPCB concentrations when averaged across all years. The results indicate that riparian spiders may be useful sentinels of relative PCB availability to aquatic and riparian food webs in heterogeneous aquatic ecosystems like rivermouths where habitat and contaminant variability may make the use of aquatic taxa less effective. Furthermore, the present approach appears robust to heterogeneity in shoreline development and riparian vegetation that support different families of large web-building spiders. Environ Toxicol Chem 2017;36:1278-1286. Published 2016 Wiley Periodicals, Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America. Published 2016 Wiley Periodicals, Inc. on behalf of SETAC. This article is a US government work and, as such, is in

  20. Stable isotopes of Hawaiian spiders reflect substrate properties along a chronosequence

    Directory of Open Access Journals (Sweden)

    Susan R. Kennedy

    2018-03-01

    Full Text Available The Hawaiian Islands offer a unique opportunity to test how changes in the properties of an isolated ecosystem are propagated through the organisms that occur within that ecosystem. The age-structured arrangement of volcanic-derived substrates follows a regular progression over space and, by inference, time. We test how well documented successional changes in soil chemistry and associated vegetation are reflected in organisms at higher trophic levels—specifically, predatory arthropods (spiders—across a range of functional groups. We focus on three separate spider lineages: one that builds capture webs, one that hunts actively, and one that specializes on eating other spiders. We analyze spiders from three sites across the Hawaiian chronosequence with substrate ages ranging from 200 to 20,000 years. To measure the extent to which chemical signatures of terrestrial substrates are propagated through higher trophic levels, we use standard stable isotope analyses of nitrogen and carbon, with plant leaves included as a baseline. The target taxa show the expected shift in isotope ratios of δ15N with trophic level, from plants to cursorial spiders to web-builders to spider eaters. Remarkably, organisms at all trophic levels also precisely reflect the successional changes in the soil stoichiometry of the island chronosequence, demonstrating how the biogeochemistry of the entire food web is determined by ecosystem succession of the substrates on which the organisms have evolved.

  1. A comparative analysis of the morphology and evolution of permanent sperm depletion in spiders.

    Directory of Open Access Journals (Sweden)

    Peter Michalik

    2011-01-01

    Full Text Available Once thought to be energetically cheap and easy to produce, empirical work has shown that sperm is a costly and limited resource for males. In some spider species, there is behavioral evidence that sperm are permanently depleted after a single mating. This extreme degree of mating investment appears to co-occur with other reproductive strategies common to spiders, e.g. genital mutilation and sexual cannibalism. Here we corroborate that sperm depletion in the golden orb-web spider Nephila clavipes is permanent by uncovering its mechanistic basis using light and electron microscopy. In addition, we use a phylogeny-based statistical analysis to test the evolutionary relationships between permanent sperm depletion (PSD and other reproductive strategies in spiders. Male testes do not produce sperm during adulthood, which is unusual in spiders. Instead, spermatogenesis is nearly synchronous and ends before the maturation molt. Testis size decreases as males approach their maturation molt and reaches its lowest point after sperm is transferred into the male copulatory organs (pedipalps. As a consequence, the amount of sperm available to males for mating is limited to the sperm contained in the pedipalps, and once it is used, males lose their ability to fertilize eggs. Our data suggest that PSD has evolved independently at least three times within web-building spiders and is significantly correlated with the evolution of other mating strategies that limit males to monogamy, including genital mutilation and sexual cannibalism. We conclude that PSD may be an energy-saving adaptation in species where males are limited to monogamy. This could be particularly important in web-building spiders where extreme sexual size dimorphism results in large, sedentary females and small, searching males who rarely feed as adults and are vulnerable to starvation. Future work will explore possible energetic benefits and the evolutionary lability of PSD relative to other

  2. Summary statistics for fossil spider species taxonomy

    OpenAIRE

    Penney, David; Dunlop, Jason; Marusik, Yuri

    2012-01-01

    Abstract Spiders (Araneae) are one of the most species-rich orders on Earth today, and also have one of the longest geological records of any terrestrial animal groups, as demonstrated by their extensive fossil record. There are currently around 1150 described fossil spider species, representing 2.6% of all described spiders (i.e. extinct and extant). Data for numbers of fossil and living spider taxa described annually (and various other metrics for the fossil taxa) were compiled from current...

  3. Global patterns of guild composition and functional diversity of spiders.

    Directory of Open Access Journals (Sweden)

    Pedro Cardoso

    Full Text Available The objectives of this work are: (1 to define spider guilds for all extant families worldwide; (2 test if guilds defined at family level are good surrogates of species guilds; (3 compare the taxonomic and guild composition of spider assemblages from different parts of the world; (4 compare the taxonomic and functional diversity of spider assemblages and; (5 relate functional diversity with habitat structure. Data on foraging strategy, prey range, vertical stratification and circadian activity was collected for 108 families. Spider guilds were defined by hierarchical clustering. We searched for inconsistencies between family guild placement and the known guild of each species. Richness and abundance per guild before and after correcting guild placement were compared, as were the proportions of each guild and family between all possible pairs of sites. Functional diversity per site was calculated based on hierarchical clustering. Eight guilds were discriminated: (1 sensing, (2 sheet, (3 space, and (4 orb web weavers; (5 specialists; (6 ambush, (7 ground, and (8 other hunters. Sixteen percent of the species richness corresponding to 11% of all captured individuals was incorrectly attributed to a guild by family surrogacy; however, the correlation of uncorrected vs. corrected guilds was invariably high. The correlation of guild richness or abundances was generally higher than the correlation of family richness or abundances. Functional diversity was not always higher in the tropics than in temperate regions. Families may potentially serve as ecological surrogates for species. Different families may present similar roles in the ecosystems, with replacement of some taxa by other within the same guild. Spiders in tropical regions seem to have higher redundancy of functional roles and/or finer resource partitioning than in temperate regions. Although species and family diversity were higher in the tropics, functional diversity seems to be also

  4. Global Patterns of Guild Composition and Functional Diversity of Spiders

    Science.gov (United States)

    Cardoso, Pedro; Pekár, Stano; Jocqué, Rudy; Coddington, Jonathan A.

    2011-01-01

    The objectives of this work are: (1) to define spider guilds for all extant families worldwide; (2) test if guilds defined at family level are good surrogates of species guilds; (3) compare the taxonomic and guild composition of spider assemblages from different parts of the world; (4) compare the taxonomic and functional diversity of spider assemblages and; (5) relate functional diversity with habitat structure. Data on foraging strategy, prey range, vertical stratification and circadian activity was collected for 108 families. Spider guilds were defined by hierarchical clustering. We searched for inconsistencies between family guild placement and the known guild of each species. Richness and abundance per guild before and after correcting guild placement were compared, as were the proportions of each guild and family between all possible pairs of sites. Functional diversity per site was calculated based on hierarchical clustering. Eight guilds were discriminated: (1) sensing, (2) sheet, (3) space, and (4) orb web weavers; (5) specialists; (6) ambush, (7) ground, and (8) other hunters. Sixteen percent of the species richness corresponding to 11% of all captured individuals was incorrectly attributed to a guild by family surrogacy; however, the correlation of uncorrected vs. corrected guilds was invariably high. The correlation of guild richness or abundances was generally higher than the correlation of family richness or abundances. Functional diversity was not always higher in the tropics than in temperate regions. Families may potentially serve as ecological surrogates for species. Different families may present similar roles in the ecosystems, with replacement of some taxa by other within the same guild. Spiders in tropical regions seem to have higher redundancy of functional roles and/or finer resource partitioning than in temperate regions. Although species and family diversity were higher in the tropics, functional diversity seems to be also influenced by

  5. New records of two spider-parasitoids of the genus Polysphincta (Hymenoptera, Ichneumonidae, Ephialtini from Central Europe, with notes on their host interactions

    Directory of Open Access Journals (Sweden)

    Korenko, Stanislav

    2017-09-01

    Full Text Available A polysphinctine wasp Polysphincta longa, associated with the orb web building spider Araneus angulatus, was recorded for the first time in Slovakia. Further, the congener Polysphincta tuberosa was recorded in association with a new spider host Araneus sturmi. New distribution records of Polysphincta species from the Czech and Slovak Republics are presented. The final stage larva of both, P. longa and P. tuberosa, induced a specific alteration in web architecture: the spider constructed a unique 3D tangle of silk – so called “cocoon web” – to protect the parasitoid during the pupal stage. The host range of wasps belonging to the genus Polysphincta in Europe is discussed.

  6. Spider and burnable poison rod combinations

    International Nuclear Information System (INIS)

    Edwards, G.T.; Schluderberg, D.C.

    1980-01-01

    An improved design of burnable poison rods and associated spiders used in fuel assemblies of pressurized water power reactor cores, is described. The rods are joined to the spider arms in a manner which is proof against the reactor core environment and yet allows the removal of the rods from the spider simply, swiftly and delicately. (U.K.)

  7. Approach and avoidance in fear of spiders

    NARCIS (Netherlands)

    Rinck, M.; Becker, E.S.

    2007-01-01

    We examined attitudes towards spiders by employing an Approach-Avoidance Task, in which participants respond to pictures by pulling a joystick towards themselves or by pushing it away from themselves. For spider fearfuls, this stimulus–response assignment is either compatible (push spiders away) or

  8. Evaluation of the efficacy of vacuum cleaners for the integrated control of brown spider Loxosceles intermedia

    Directory of Open Access Journals (Sweden)

    E. N. Ramires

    2007-01-01

    Full Text Available Some venomous spiders of the genus Loxosceles can reach high population densities inside and around houses. In Brazil, most spider accidents are related to Loxosceles intermedia. Control of loxoscelism should utilize integrated pest management tools, such as vacuum cleaners, to eliminate egg sacs, webs and spiders. The present study tested the efficacy of one type of vacuum cleaner (for professional and domestic use in the control of L. intermedia populations. Cockroaches (Pycnoscelus surinamensis were used in some tests for comparison. Vacuuming using standard accessories or a paper tube resulted in the death of all female (n=60, male (n=60, young (n=60 and just-hatched (n=60 L. intermedia, and all egg sacs (n=5 were destroyed. The removal of the plastic plate present at the bottom of the vacuuming tube inside the machine allowed some spiders to survive the vacuuming process. When kept inside a vacuum bag full of dust and debris, adult females (n=10 survived for 10 days; however, significant mortality was observed among male (n=10 and young individuals (n=10. Addition of cornstarch to the vacuum bag did not affect the spiders (n=20. Vacuum cleaners, such as the one used in the present investigation, are promising tools for integrated management of L. intermedia and other spiders in domestic environments.

  9. First report of brown widow spider sightings in Peninsular Malaysia and notes on its global distribution.

    Science.gov (United States)

    Muslimin, Mustakiza; Wilson, John-James; Ghazali, Amir-Ridhwan M; Braima, Kamil A; Jeffery, John; Wan-Nor, Fitri; Alaa-Eldin, Mohamed E; Mohd-Zin, Siti-Waheeda; Wan-Yusoff, Wan S; Norma-Rashid, Yusoff; Lau, Yee L; Rohela, Mahmud; Abdul-Aziz, Noraishah M

    2015-01-01

    The brown widow spider (Latrodectus geometricus Koch, 1841) has colonised many parts of the world from its continent of origin, Africa. By at least 1841, the species had successfully established populations in South America and has more recently expanded its range to the southern states of North America. This highly adaptable spider has been far more successful in finding its niche around the world than its famous cousins, the black widow, Latrodectus mactans, found in the south-eastern states of North America, and the red-back, Latrodectus hasselti, found mostly in Australia, New Zealand and Japan. We performed an extensive web search of brown widow sightings and mapped the location of each sighting using ArcGIS. Specimens reputedly of the species L. geometricus were collected at three localities in Peninsular Malaysia. The spiders were identified and documented based on an examination of morphological characteristics and DNA barcoding. The spiders found in Peninsular Malaysia were confirmed to be Latrodectus geometricus based on their morphological characteristics and DNA barcodes. We recorded 354 sightings of the brown widow in 58 countries, including Peninsular Malaysia. Reports from the Americas and the Far East suggest a global-wide invasion of the brown widow spider. Herein we report the arrival of the brown widow spider in Peninsular Malaysia and provide notes on the identification of the species and its recently expanded range.

  10. Spider Silk: From Protein-Rich Gland Fluids to Diverse Biopolymer Fibers

    Science.gov (United States)

    2016-01-06

    process of dragline silk and move into studying the dopes spiders use to spin egg cases (tubuliform and aciniform) and wrap prey (aciniform). We... drops dramatically at a pH = 4 leading to rapid fiber formation. When the dope is close to the spinneret, decreasing the pH below 4 can accelerate the...Weber, W.S., Mou, Q., Yarger, J.L., Lewis, R.V., “Mechanical and Physical Properties of Recombinant Spider Silk Films Using Organic and Aqueous

  11. SVM-based prediction of propeptide cleavage sites in spider toxins identifies toxin innovation in an Australian tarantula.

    Directory of Open Access Journals (Sweden)

    Emily S W Wong

    Full Text Available Spider neurotoxins are commonly used as pharmacological tools and are a popular source of novel compounds with therapeutic and agrochemical potential. Since venom peptides are inherently toxic, the host spider must employ strategies to avoid adverse effects prior to venom use. It is partly for this reason that most spider toxins encode a protective proregion that upon enzymatic cleavage is excised from the mature peptide. In order to identify the mature toxin sequence directly from toxin transcripts, without resorting to protein sequencing, the propeptide cleavage site in the toxin precursor must be predicted bioinformatically. We evaluated different machine learning strategies (support vector machines, hidden Markov model and decision tree and developed an algorithm (SpiderP for prediction of propeptide cleavage sites in spider toxins. Our strategy uses a support vector machine (SVM framework that combines both local and global sequence information. Our method is superior or comparable to current tools for prediction of propeptide sequences in spider toxins. Evaluation of the SVM method on an independent test set of known toxin sequences yielded 96% sensitivity and 100% specificity. Furthermore, we sequenced five novel peptides (not used to train the final predictor from the venom of the Australian tarantula Selenotypus plumipes to test the accuracy of the predictor and found 80% sensitivity and 99.6% 8-mer specificity. Finally, we used the predictor together with homology information to predict and characterize seven groups of novel toxins from the deeply sequenced venom gland transcriptome of S. plumipes, which revealed structural complexity and innovations in the evolution of the toxins. The precursor prediction tool (SpiderP is freely available on ArachnoServer (http://www.arachnoserver.org/spiderP.html, a web portal to a comprehensive relational database of spider toxins. All training data, test data, and scripts used are available from

  12. Nuptial gifts of male spiders: sensory exploitation of the female's maternal care instinct or foraging motivation?

    DEFF Research Database (Denmark)

    Bilde, T.; Tuni, Cristina; Elsayed, Rehab

    2007-01-01

    Nuptial feeding can evolve as sensory traps where the male exploits the female's foraging motivation in a sexual context. The nuptial prey gift of the nursery-web spider Pisaura mirabilis is wrapped in white silk, and it has been suggested that males initially exploit the maternal care instinct...

  13. [Diversity of insects captured by weaver spiders (Arachnida: Araneae) in the cocoa agroecosystem in Tabasco, Mexico].

    Science.gov (United States)

    Pérez-de La Cruz, Manuel; Sánchez-Soto, Saúl; Ortíz-García, Carlos F; Zapata-Mata, Raúl; Cruz-Pérez, Aracely de la

    2007-01-01

    The aim of this work was to know the diversity of insects captured by weaver spiders in a plantation of cocoa (Theobroma cacao L.) of 6 ha in the State of Tabasco, Mexico. The study was carried out from July 2004 to June 2005 by means biweekly samples of the insects captured on the spiders webs. The total of 3,041 webs of 54 species of spiders belonging to seven families (Araneidae, Theridiidae, Tetragnathidae, Uloboridae, Pholcidae, Dyctinidae and Linyphiidae) were revised. We found 1,749 specimens belonging to 10 orders of insects, represented by 93 families, the majority of Coleoptera, Diptera and Hemiptera that constituted 74% of the identified families. The biggest number of specimens of all orders was captured by Araneidae, except of Isoptera, whose specimens were captured mainly by the family Theridiidae. The index of diversity (H'), evenness (J') and similarity (Is), applied to know the diversity of families of insects captured among families of spiders, varied from 0.00 to 3.24, 0.00 to 0.81, and 0.04 to 0.522, respectively. We conclude that there is a wide diversity of insects predated by the weaver spiders in the cocoa agroecosystem, and that there are species that can be promising for the biological control of pests.

  14. Biphasic activity of a jumping spider

    Science.gov (United States)

    Okuyama, Toshinori

    2011-01-01

    Individual variation is a ubiquitous and important factor that affects ecological dynamics. This study examined individual variation in the nest-use pattern of the jumping spider Phidippus audax. Although the jumping spider is a diurnal species, field observations in this study revealed that the majority of individuals remained in their nests during the day. An accompanying examination of the hunger level of the spiders revealed that spiders that remained in nests were more starved than those observed outside nests. If spiders actively forage when they are starved, as has been suggested by previous studies, one would expect to see the opposite trend (i.e., spiders that remained in nests are more satiated). Thus, the pattern observed in the field contradicts the known behavioral pattern of the spiders. An individual-based model was used to investigate the behavioral mechanism of the spider and the discrepancy found in the observations. A basic assumption of the model is that spiders possess distinct inactive and active phases (biphasic activity pattern), and transitions between the two phases are regulated by the hunger level of the spider. Data from a laboratory experiment were used to examine the assumptions of the model partially. The model was able to capture patterns observed in the data, suggesting that the pattern of transitions in biphasic activity is an important trait of the foraging behavior of the jumping spider.

  15. Spiders (Arachnida: Araneae of Gujarat University Campus, Ahmedabad, India with additional description of Eilica tikaderi (Platnick, 1976

    Directory of Open Access Journals (Sweden)

    Dhruv A. Prajapati

    2016-09-01

    Full Text Available We report a checklist of spiders based on a survey made from August 2013 to July 2014 in Gujarat University Campus, an urban area located in the middle of Ahmadabad City, Gujarat State. A total of 77 species of spiders belonging to 53 genera and 20 families of spiders were recorded from the study area represented by 31.74% of the total 63 families reported from India. Salticidae was found to be the most dominant family with 18 species from 14 genera. Guild structure analysis revealed six feeding guilds, namely stalkers, orb-web builders, space-web builders, ambushers, foliage hunters and ground runners. Stalkers and orb-web builders were the most dominant feeding guilds representing 28.58% and 20.78% respectively among all studied guilds. Species Eilica tikaderi (Platnick, 1976 is reported for the first time from Gujarat with additional description and detailed genitalic illustrations.

  16. The toxicology of Latrodectus tredecimguttatus: the Mediterranean Black Widow spider.

    Science.gov (United States)

    Bonnet, M S

    2004-01-01

    The symptomatology of envenomation by the Mediterranean Black Widow Spider, Latrodectus tredecimguttatus, is reviewed. The results confirm the hypothesis that the homeopathic remedy, Tarentula hispanica, is derived from this spider, not from the Wolf spider, Lycosa tarentula.

  17. Evidence for antimicrobial activity associated with common house spider silk

    Directory of Open Access Journals (Sweden)

    Wright Simon

    2012-06-01

    Full Text Available Abstract Background Spider silk is one of the most versatile materials in nature with great strength and flexibility. Native and synthetically produced silk has been used in a wide range of applications including the construction of artificial tendons and as substrates for human cell growth. In the literature there are anecdotal reports that suggest that native spider silk may also have antimicrobial properties. Findings In this study we compared the growth of a Gram positive and a Gram negative bacterium in the presence and absence of silk produced by the common house spider Tegenaria domestica. We demonstrate that native web silk of Tegenaria domestica can inhibit the growth of the Gram positive bacterium, Bacillus subtilis. No significant inhibition of growth was detected against the Gram negative bacterium, Escherichia coli. The antimicrobial effect against B. subtilis appears to be short lived thus the active agent potentially acts in a bacteriostatic rather than bactericidal manner. Treatment of the silk with Proteinase K appears to reduce the ability to inhibit bacterial growth. This is consistent with the active agent including a protein element that is denatured or cleaved by treatment. Tegenaria silk does not appear to inhibit the growth of mammalian cells in vitro thus there is the potential for therapeutic applications.

  18. Evidence from Multiple Species that Spider Silk Glue Component ASG2 is a Spidroin.

    Science.gov (United States)

    Collin, Matthew A; Clarke, Thomas H; Ayoub, Nadia A; Hayashi, Cheryl Y

    2016-02-15

    Spiders in the superfamily Araneoidea produce viscous glue from aggregate silk glands. Aggregate glue coats prey-capture threads and hampers the escape of prey from webs, thereby increasing the foraging success of spiders. cDNAs for Aggregate Spider Glue 1 (ASG1) and 2 (ASG2) have been previously described from the golden orb-weaver, Nephila clavipes, and Western black widow, Latrodectus hesperus. To further investigate aggregate glues, we assembled ASG1 and ASG2 from genomic target capture libraries constructed from three species of cob-web weavers and three species of orb-web weavers, all araneoids. We show that ASG1 is unlikely to be a glue, but rather is part of a widespread arthropod gene family, the peritrophic matrix proteins. For ASG2, we demonstrate its remarkable architectural and sequence similarities to spider silk fibroins, indicating that ASG2 is a member of the spidroin gene family. Thus, spidroins have diversified into glues in addition to task-specific, high performance fibers.

  19. The Legs That Rock the Cradle: Spider Mothers

    Indian Academy of Sciences (India)

    Abstract. Spiders are excellent models to study behavioural diversityand evolutionary adaptations in the animal world. This articleexplores the strategies used by spiders to maximise thesurvival of their offspring.

  20. The evolution of sociality in spiders

    DEFF Research Database (Denmark)

    Lubin, Yael; Bilde, T.

    2007-01-01

    . Anelosimus (Theridiidae) C. Sociality in Spiders: An Evolutionary Dead End? V. Evolution and Maintenance of Sociality in Spiders: Relevant Models A. Kin Selection 1. Kin Recognition 2. Inbreeding and Kin Selection B. Multilevel Selection (Group Selection) C. Ecological Benefits D. Ecological Constraints E......I. Introducing Social Spiders II. Social and Subsocial Species: A Survey of Behavioral Traits III. Inbred Sociality in Spiders A. Cooperation Versus Competition: A Balancing Act B. Do Social Spiders Have Division of Labor? C. Colony Foundation: Propagule Dispersal Versus Fission D. Female......-Biased Colony Sex Ratios: Primary and Operational Sex Ratios E. Mating System: Inbreeding and Its Population-Genetic Consequences F. "Boom and Bust" Colony Dynamics IV. Phylogenetic Relationships Among Social Spider Species A. Common Features of Social Evolution B. Case Studies 1. Stegodyphus (Eresidae) 2...

  1. The Aromatic Head Group of Spider Toxin Polyamines Influences Toxicity to Cancer Cells

    Directory of Open Access Journals (Sweden)

    David Wilson

    2017-10-01

    Full Text Available Spider venoms constitute incredibly diverse libraries of compounds, many of which are involved in prey capture and defence. Polyamines are often prevalent in the venom and target ionotropic glutamate receptors. Here we show that a novel spider polyamine, PA366, containing a hydroxyphenyl-based structure is present in the venom of several species of tarantula, and has selective toxicity against MCF-7 breast cancer cells. By contrast, a polyamine from an Australian funnel-web spider venom, which contains an identical polyamine tail to PA366 but an indole-based head-group, is only cytotoxic at high concentrations. Our results suggest that the ring structure plays a role in the cytotoxicity and that modification to the polyamine head group might lead to more potent and selective compounds with potential as novel cancer treatments.

  2. Bats in cobwebs of the giant-spider Nephilingis cruentata (Fabricius, 1775 (Araneae: Nephilidae in Brazil

    Directory of Open Access Journals (Sweden)

    Fábio André Facco Jacomassa

    2015-12-01

    Full Text Available Bats throughout the world are preyed upon primarily by vertebrates, but some are also attacked by invertebrates. We report two cases of bats entangled in webs of the giant-spider Nephilingis cruentata in southeastern Brazil. The first incidence occurred in December 2012, on which a female Eptesicus diminutus was found dead. The second occurred in March 2013, in which a male Tadarida brasiliensis was removed from the web alive, and later released. The animals showed no predation marks on the body, and both events were recorded after heavy rains. We suspect that the bats may have become entangled in the webs while seeking shelter from rain, or while foraging for insects. Even though the bats were not preyed upon, this spider cannot be ruled out as an opportunistic predator of small bats, as has been observed outside of Brazil.

  3. Ecology of spiders inhabiting abandoned mammal burrows in South African savanna.

    Science.gov (United States)

    Heidger, Christa

    1988-07-01

    In the Nylsvley Nature Reserve, in the South African savanna, the spider community in 320 abandoned mammal burrows was investigated. Three species, Agelena ocellata (Agelenidae), Euprosthenops proximus (Pisauridae) and Smeringopus pallidus (Pholcidae), coexisted in the burrows. The number of individuals and the number of species inhabiting the burrows increased with burrow size. Gerbil burrows were apparently too small to provide space for more than one individual of any of the three species. Only the burrows of springhares, warthogs, and antbears contained more than one spider. When artificial burrows were provided a rapid increase in settlement resulted. Competition for space therefore seems to be the determining factor influencing the population size. A relatively low number of prey items (136, in 119 webs) were found in agelenid webs only. Kleptoparasitic ants were observed stealing prey items from the webs.

  4. APLIKASI WEB CRAWLER UNTUK WEB CONTENT PADA MOBILE PHONE

    Directory of Open Access Journals (Sweden)

    Sarwosri Sarwosri

    2009-01-01

    Full Text Available Crawling is the process behind a search engine, which served through the World Wide Web in a structured and with certain ethics. Applications that run the crawling process is called Web Crawler, also called web spider or web robot. The growth of mobile search services provider, followed by growth of a web crawler that can browse web pages in mobile content type. Crawler Web applications can be accessed by mobile devices and only web pages that type Mobile Content to be explored is the Web Crawler. Web Crawler duty is to collect a number of Mobile Content. A mobile application functions as a search application that will use the results from the Web Crawler. Crawler Web server consists of the Servlet, Mobile Content Filter and datastore. Servlet is a gateway connection between the client with the server. Datastore is the storage media crawling results. Mobile Content Filter selects a web page, only the appropriate web pages for mobile devices or with mobile content that will be forwarded.

  5. De spin in het web

    NARCIS (Netherlands)

    Ir. Joop de Jong

    2003-01-01

    Businesses today are facing ever greater competition. Products and services need to be delivered faster, more efficiently and at lower price. Companies are forced to supply customised products: demand-oriented production. In order to meet this changing demand, companies have to subcontract and

  6. A 4-year study of invasive and native spider populations in Maine

    Science.gov (United States)

    Jakob, Elizabeth M.; Porter, Adam H.; Ginsberg, Howard; Bednarski, Julie V.; Houser, Jeremy

    2011-01-01

    Invasive spiders pose potential threats to native spiders. In 2002, the European spider Linyphia triangularis (Clerck, 1757) (Araneae: Linyphiidae) was discovered in all but one county in Maine. At Acadia National Park, we conducted a 4-year study of L. triangularis and three native linyphiid species of a similar size (Frontinella communis (Hentz, 1850), Pityohyphantes subarcticus Chamberlin and Ivie, 1943, and Neriene radiata (Walckenaer, 1842)). Using line-transect surveys, we measured population densities in coastal and forest habitat. The density of L. triangularis varied across years but was always significantly higher on the coast than in the forest. In contrast, only one native species was present on the coast and at very low numbers. Coastal L. triangularis were larger and in better condition than those in the forest, and numbers and biomass of insect prey were also higher on the coast. In 2 years, we also conducted transects at a second coastal location in Maine where the invader was at low density. At that site, native densities were substantially higher than at either Acadia site. Our data are consistent with the hypothesis that L. triangularis is reducing populations of native spiders. Companion studies suggest that L. triangularis negatively impacts natives by usurping both web sites and webs.

  7. The spiders of the Swartberg Nature Reserve in South Africa (Arachnida: Araneae

    Directory of Open Access Journals (Sweden)

    A.S. Dippenaar-Schoeman

    2005-06-01

    Full Text Available The Swartberg Nature Reserve is situated in the Large Swartberg mountain range, in the Oudtshoorn district of the Western Cape Province. Spiders were collected from the reserve over a 10-year period. This is one of the inventory projects of the South African National Survey (SANSA for spiders of the Succulent Karoo Biome. A total of 45 families comprising 136 genera and 186 species were collected, all which are new records for the area. This represents about 9.4 of the total known South African spider fauna. Of the spiders collected 142 species (76.5 were wanderers and 44 (23.5 web dwellers. The plant dwellers comprised 43.3 of the total number of species and the ground dwellers 56.7 . The Gnaphosidae was the most diverse family represented by 33 species, followed by the Salticidae with 23 and Thomisidae with 15. Ten species are possibly new to science and the Filistatidae is a first record for South Africa. An annotated checklist with information on the guilds, habitat preference and web types are provided.

  8. Spider trait assembly patterns and resilience under fire-induced vegetation change in South Brazilian grasslands.

    Directory of Open Access Journals (Sweden)

    Luciana R Podgaiski

    Full Text Available Disturbances induce changes on habitat proprieties that may filter organism's functional traits thereby shaping the structure and interactions of many trophic levels. We tested if communities of predators with foraging traits dependent on habitat structure respond to environmental change through cascades affecting the functional traits of plants. We monitored the response of spider and plant communities to fire in South Brazilian Grasslands using pairs of burned and unburned plots. Spiders were determined to the family level and described in feeding behavioral and morphological traits measured on each individual. Life form and morphological traits were recorded for plant species. One month after fire the abundance of vegetation hunters and the mean size of the chelicera increased due to the presence of suitable feeding sites in the regrowing vegetation, but irregular web builders decreased due to the absence of microhabitats and dense foliage into which they build their webs. Six months after fire rosette-form plants with broader leaves increased, creating a favourable habitat for orb web builders which became more abundant, while graminoids and tall plants were reduced, resulting in a decrease of proper shelters and microclimate in soil surface to ground hunters which became less abundant. Hence, fire triggered changes in vegetation structure that lead both to trait-convergence and trait-divergence assembly patterns of spiders along gradients of plant biomass and functional diversity. Spider individuals occurring in more functionally diverse plant communities were more diverse in their traits probably because increased possibility of resource exploitation, following the habitat heterogeneity hypothesis. Finally, as an indication of resilience, after twelve months spider communities did not differ from those of unburned plots. Our findings show that functional traits provide a mechanistic understanding of the response of communities to

  9. Spider trait assembly patterns and resilience under fire-induced vegetation change in South Brazilian grasslands.

    Science.gov (United States)

    Podgaiski, Luciana R; Joner, Fernando; Lavorel, Sandra; Moretti, Marco; Ibanez, Sebastien; Mendonça, Milton de S; Pillar, Valério D

    2013-01-01

    Disturbances induce changes on habitat proprieties that may filter organism's functional traits thereby shaping the structure and interactions of many trophic levels. We tested if communities of predators with foraging traits dependent on habitat structure respond to environmental change through cascades affecting the functional traits of plants. We monitored the response of spider and plant communities to fire in South Brazilian Grasslands using pairs of burned and unburned plots. Spiders were determined to the family level and described in feeding behavioral and morphological traits measured on each individual. Life form and morphological traits were recorded for plant species. One month after fire the abundance of vegetation hunters and the mean size of the chelicera increased due to the presence of suitable feeding sites in the regrowing vegetation, but irregular web builders decreased due to the absence of microhabitats and dense foliage into which they build their webs. Six months after fire rosette-form plants with broader leaves increased, creating a favourable habitat for orb web builders which became more abundant, while graminoids and tall plants were reduced, resulting in a decrease of proper shelters and microclimate in soil surface to ground hunters which became less abundant. Hence, fire triggered changes in vegetation structure that lead both to trait-convergence and trait-divergence assembly patterns of spiders along gradients of plant biomass and functional diversity. Spider individuals occurring in more functionally diverse plant communities were more diverse in their traits probably because increased possibility of resource exploitation, following the habitat heterogeneity hypothesis. Finally, as an indication of resilience, after twelve months spider communities did not differ from those of unburned plots. Our findings show that functional traits provide a mechanistic understanding of the response of communities to environmental change

  10. Compliant threads maximize spider silk connection strength and toughness

    Science.gov (United States)

    Meyer, Avery; Pugno, Nicola M.; Cranford, Steven W.

    2014-01-01

    Millions of years of evolution have adapted spider webs to achieve a range of functionalities, including the well-known capture of prey, with efficient use of material. One feature that has escaped extensive investigation is the silk-on-silk connection joints within spider webs, particularly from a structural mechanics perspective. We report a joint theoretical and computational analysis of an idealized silk-on-silk fibre junction. By modifying the theory of multiple peeling, we quantitatively compare the performance of the system while systematically increasing the rigidity of the anchor thread, by both scaling the stress–strain response and the introduction of an applied pre-strain. The results of our study indicate that compliance is a virtue—the more extensible the anchorage, the tougher and stronger the connection becomes. In consideration of the theoretical model, in comparison with rigid substrates, a compliant anchorage enormously increases the effective adhesion strength (work required to detach), independent of the adhered thread itself, attributed to a nonlinear alignment between thread and anchor (contact peeling angle). The results can direct novel engineering design principles to achieve possible load transfer from compliant fibre-to-fibre anchorages, be they silk-on-silk or another, as-yet undeveloped, system. PMID:25008083

  11. How spiders practice aggressive and Batesian mimicry

    Directory of Open Access Journals (Sweden)

    Ximena J. NELSON, Robert R. JACKSON

    2012-08-01

    Full Text Available To understand communication, the interests of the sender and the receiver/s of signals should be considered separately. When our goal is to understand the adaptive significance of specific responses to specific signals by the receiver, questions about signal information are useful. However, when our goal is to understand the adaptive significance to the sender of generating a signal, it may be better to envisage the receiver’s response to signals as part of the sender’s extended phenotype. By making signals, a sender interfaces with the receiver’s model of the world and indirectly manipulates its behaviour. This is especially clear in cases of mimicry, where animals use deceptive signals that indirectly manipulate the behaviour of receivers. Many animals adopt Batesian mimicry to deceive their predators, or aggressive mimicry to deceive their prey. We review examples from the lite­rature on spiders to illustrate how these phenomena, traditionally thought of as distinct, can become entangled in a web of lies [Current Zoology 58 (4: 620–629, 2012].

  12. Development of locomotion in a subsocial spider.

    Science.gov (United States)

    Ahn, Soon Kil; Kim, Kil Won

    2015-04-01

    Following consumption of their mother, the subsocial spider Amaurobius ferox remain together, exhibiting distinctive behaviours in response to intruders into the natal nest. We examined the ontogeny and characteristics of locomotory behaviours in A. ferox during this post-maternal social period. Locomotion of the spiderlings, elicited by the introduction of a cricket larva into the natal web, fell into two categories: 'abrupt locomotion' (AL) and 'ordinary locomotion' (OL). AL involved rapid and linear movement, whereas OL involved slower motion, not necessarily in a straight line. Both types of locomotion varied with spiderling age. AL appeared for only a limited period of time whereas the frequency of OL increased linearly over time. AL occurred more collectively than OL: the percentage of participants in a bout of locomotion was 18.67±17.71% vs. 10.22±9.33%. The collective tendency of AL increased up until the seventh day and then decreased, whereas that of OL progressively decreased. The direction of AL responses to the intruder did not vary over time; however, for OL, movements towards increased in frequency over time. Locomotory responses also varied with the intensity of intruder movement. Including transient behaviours, the chronology of different behaviours suggests that behavioural development in A. ferox involves maternal influences and weakens group cohesion and collective tendency. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. The diet of the black widow spider Latrodectus mirabilis (Theridiidae in two cereal crops of central Argentina

    Directory of Open Access Journals (Sweden)

    Gabriel Pompozzi

    2013-12-01

    Full Text Available The spider Latrodectus mirabilis (Holmberg, 1876 is commonly found in cereals crops of central Argentina. We studied its diet composition at the field and capture rate on leaf-cutting ants based on laboratory experiments. This study comprises the first approach that documents the diet of L. mirabilis in wheat and oat fields of central Argentina. We identified 1,004 prey items collected from its webs during the last phenological stages of both cereal crops. The prey composition was variable but the spiders prey mainly on ants (Formicidae, Hymenoptera, who represented more than 86% of the total. Meanwhile, in the capture rate experiences we registered a high proportion of ants captured by spiders at the beginning of experiences, capturing the half of the ants from total in the first four hours. Summarizing, we reported a polyphagous diet of this spider species in wheat and oat fields. Ants were the most important prey item of this spider, as found in other Latrodectus spiders around the world.

  14. Spider phobics more easily see a spider in morphed schematic pictures

    Directory of Open Access Journals (Sweden)

    Partchev Ivailo

    2007-11-01

    Full Text Available Abstract Background Individuals with social phobia are more likely to misinterpret ambiguous social situations as more threatening, i.e. they show an interpretive bias. This study investigated whether such a bias also exists in specific phobia. Methods Individuals with spider phobia or social phobia, spider aficionados and non-phobic controls saw morphed stimuli that gradually transformed from a schematic picture of a flower into a schematic picture of a spider by shifting the outlines of the petals until they turned into spider legs. Participants' task was to decide whether each stimulus was more similar to a spider, a flower or to neither object while EEG was recorded. Results An interpretive bias was found in spider phobia on a behavioral level: with the first opening of the petals of the flower anchor, spider phobics rated the stimuli as more unpleasant and arousing than the control groups and showed an elevated latent trait to classify a stimulus as a spider and a response-time advantage for spider-like stimuli. No cortical correlates on the level of ERPs of this interpretive bias could be identified. However, consistent with previous studies, social and spider phobic persons exhibited generally enhanced visual P1 amplitudes indicative of hypervigilance in phobia. Conclusion Results suggest an interpretive bias and generalization of phobia-specific responses in specific phobia. Similar effects have been observed in other anxiety disorders, such as social phobia and posttraumatic stress disorder.

  15. Bioaccumulation of Cry1Ab protein from an herbivore reduces anti-oxidant enzyme activities in two spider species.

    Directory of Open Access Journals (Sweden)

    Ji Zhou

    Full Text Available Cry proteins are expressed in rice lines for lepidopteran pest control. These proteins can be transferred from transgenic rice plants to non-target arthropods, including planthoppers and then to a predatory spider. Movement of Cry proteins through food webs may reduce fitness of non-target arthropods, although recent publications indicated no serious changes in non-target populations. Nonetheless, Cry protein intoxication influences gene expression in Cry-sensitive insects. We posed the hypothesis that Cry protein intoxication influences enzyme activities in spiders acting in tri-trophic food webs. Here we report on the outcomes of experiments designed to test our hypothesis with two spider species. We demonstrated that the movement of CryAb protein from Drosophila culture medium into fruit flies maintained on the CryAb containing medium and from the flies to the spiders Ummeliata insecticeps and Pardosa pseudoannulata. We also show that the activities of three key metabolic enzymes, acetylcholine esterase (AchE, glutathione peroxidase (GSH-Px, and superoxide dismutase (SOD were significantly influenced in the spiders after feeding on Cry1Ab-containing fruit flies. We infer from these data that Cry proteins originating in transgenic crops impacts non-target arthropods at the physiological and biochemical levels, which may be one mechanism of Cry protein-related reductions in fitness of non-target beneficial predators.

  16. Foraging modality and plasticity in foraging traits determine the strength of competitive interactions among carnivorous plants, spiders and toads.

    Science.gov (United States)

    Jennings, David E; Krupa, James J; Rohr, Jason R

    2016-07-01

    Foraging modalities (e.g. passive, sit-and-wait, active) and traits are plastic in some species, but the extent to which this plasticity affects interspecific competition remains unclear. Using a long-term laboratory mesocosm experiment, we quantified competition strength and the plasticity of foraging traits in a guild of generalist predators of arthropods with a range of foraging modalities. Each mesocosm contained eight passively foraging pink sundews, and we employed an experimental design where treatments were the presence or absence of a sit-and-wait foraging spider and actively foraging toad crossed with five levels of prey abundance. We hypothesized that actively foraging toads would outcompete the other species at low prey abundance, but that spiders and sundews would exhibit plasticity in foraging traits to compensate for strong competition when prey were limited. Results generally supported our hypotheses. Toads had a greater effect on sundews at low prey abundances, and toad presence caused spiders to locate webs higher above the ground. Additionally, the closer large spider webs were to the ground, the greater the trichome densities produced by sundews. Also, spider webs were larger with than without toads and as sundew numbers increased, and these effects were more prominent as resources became limited. Finally, spiders negatively affected toad growth only at low prey abundance. These findings highlight the long-term importance of foraging modality and plasticity of foraging traits in determining the strength of competition within and across taxonomic kingdoms. Future research should assess whether plasticity in foraging traits helps to maintain coexistence within this guild and whether foraging modality can be used as a trait to reliably predict the strength of competitive interactions. © 2016 The Authors. Journal of Animal Ecology © 2016 British Ecological Society.

  17. Learned predation risk management by spider mites

    Directory of Open Access Journals (Sweden)

    Thomas eHackl

    2014-09-01

    Full Text Available Predation is a prime selective force shaping prey behavior. Investment in anti-predator behavior is traded-off against time and energy for other fitness-enhancing activities such as foraging or reproduction. To optimize this benefit/cost trade-off, prey should be able to innately and/or by experience modulate their behavior to the level of predation risk. Here, we assessed learned predation risk management in the herbivorous two-spotted spider mite Tetranychus urticae. We exposed spider mites coming from benign (naïve or high immediate predation risk (experienced environments to latent and/or no risk and assessed their site choice, activity and oviposition. Benign environments were characterized by the absence of any predator cues, high immediate risk environments by killed spider mites, physical presence of the predatory mite Phytoseiulus persimilis and associated chemosensory traces left on the surface, and latent risk environments by only predator traces. In the no-choice experiment both naïve and experienced spider mites laid their first egg later on leaves with than without predator traces. Irrespective of predator traces presence/absence, experienced mites laid their first egg earlier than naïve ones did. Naïve spider mites were more active, indicating higher restlessness, and laid fewer eggs on leaves with predator traces, whereas experienced mites were less active and laid similar numbers of eggs on leaves with and without predator traces. In the choice experiment both naïve and experienced spider mites preferentially resided and oviposited on leaves without predator traces but experienced mites were less active than naïve ones. Overall, our study suggests that spider mites experienced with high predation risk behave bolder under latent risk than naïve spider mites. Since predator traces alone do not indicate immediate risk, we argue that the attenuated anti-predator response of experienced spider mites represents adaptive learned

  18. Understanding Spider-Man: Your Everyday Superhero

    OpenAIRE

    Falk, Nicklas; Blomsterberg, Sofie Amalie; Suciu, Alice Sabrina; Pedersen, Mads Peter; Lucas, Vilhelm

    2014-01-01

    This project focuses on the understanding of Spider-Man, and the morals and ethics that lie behind the choices he makes. Through the Dimensions Philosophy & Science/Text & Sign, this understanding is concluded by looking at ethical theories and comic book analysis. Based on the Ultimate Spider-Man comic book series, the aim is to clarify who Spider-Man is and what causes him to act in certain ways; before and after his realization of power. Some theories used to investigate these area...

  19. Modelling Crop Biocontrol by Wanderer Spiders

    Science.gov (United States)

    Venturino, Ezio; Ghersi, Andrea

    2008-09-01

    We study mathematically the effects some spiders populations have on insects living in and near agroecosystems, where woods and vineyards alternate in the landscape as in the Alta Langa, Piemonte, NW Italy.

  20. Reversible Myocarditis after Black Widow Spider Envenomation

    OpenAIRE

    Tarek Dendane; Khalid Abidi; Naoufel Madani; Asmae Benthami; Fatima-Zohra Gueddari; Redoune Abouqal; Amine-Ali Zeggwagh

    2012-01-01

    Black widow spiders can cause variable clinical scenarios from local damage to very serious conditions including death. Acute myocardial damage is rarely observed and its prognostic significance is not known. We report a rare case of a 35-year-old man who developed an acute myocarditis with cardiogenic pulmonary edema requiring mechanical ventilation caused by black widow spider's envenomation. The patient was previously healthy. The clinical course was associated with systemic and cardiovasc...

  1. Edge effect on weevils and spiders

    OpenAIRE

    R. Horváth; T. Magura; G. Péter; B. Tóthmérész

    2002-01-01

    The edge effect on weevils and spiders was tested along oak forest – meadow transects using sweep-net samples at the Síkfökút Project in Hungary. For spiders the species richness was significantly higher in the forest edge than either in the meadow or the forest interior. For weevils the species richness of the forest edge was higher than that of the meadow, but the difference was not statistically significant whereas the species richness of the forest...

  2. Anaphylaxis to black widow spider antivenom.

    Science.gov (United States)

    Hoyte, Christopher O; Cushing, Tracy A; Heard, Kennon J

    2012-06-01

    Black widow spider envenomation is commonly reported to poison centers. Black widow spider envenomation produces a clinical syndrome, known as latrodectism, characterized by headache, nausea, vomiting, several muscle cramping and pain, joint stiffness, hypertension, and regional diaphoresis. Black widow spider antivenom (Merck & Co, Inc, West Point, PA USA) is an effective and relatively safe treatment option. There is 1 clear case of anaphylaxis secondary to black widow spider antivenom reported in the medical literature. Here, we report a case of anaphylaxis to antivenom. A 12-year-old boy presented to the emergency department (ED) with diffuse, severe pain 2 1/2 hours after being bitten by a black widow spider on the right lower extremity. In the ED, the patient failed analgesic therapy with fentanyl and was given black widow spider antivenom. Within 45 minutes, he exhibited signs and symptoms consistent with anaphylaxis, including wheezing, chest tightness, pruritus, and urticarial rash. The patient was given standard therapy for anaphylaxis, and all of his signs and symptoms (including the pain secondary to the black widow envenomation) resolved over 6 hours of observation. Leading experts agree that the use of antivenom is indicated in cases of severe envenomation not responsive to standard therapy. Despite concern that the antivenom is an equine-derived whole IgG and can precipitate early hypersensitivity reactions, there is only 1 other reported case of anaphylaxis to the antivenom in the medical literature.

  3. Synthetic spider silk sustainability verification by techno-economic and life cycle analysis

    Science.gov (United States)

    Edlund, Alan

    Major ampullate spider silk represents a promising biomaterial with diverse commercial potential ranging from textiles to medical devices due to the excellent physical and thermal properties from the protein structure. Recent advancements in synthetic biology have facilitated the development of recombinant spider silk proteins from Escherichia coli (E. coli), alfalfa, and goats. This study specifically investigates the economic feasibility and environmental impact of synthetic spider silk manufacturing. Pilot scale data was used to validate an engineering process model that includes all of the required sub-processing steps for synthetic fiber manufacture: production, harvesting, purification, drying, and spinning. Modeling was constructed modularly to support assessment of alternative protein production methods (alfalfa and goats) as well as alternative down-stream processing technologies. The techno-economic analysis indicates a minimum sale price from pioneer and optimized E. coli plants at 761 kg-1 and 23 kg-1 with greenhouse gas emissions of 572 kg CO2-eq. kg-1 and 55 kg CO2-eq. kg-1, respectively. Spider silk sale price estimates from goat pioneer and optimized results are 730 kg-1 and 54 kg-1, respectively, with pioneer and optimized alfalfa plants are 207 kg-1 and 9.22 kg-1 respectively. Elevated costs and emissions from the pioneer plant can be directly tied to the high material consumption and low protein yield. Decreased production costs associated with the optimized plants include improved protein yield, process optimization, and an Nth plant assumption. Discussion focuses on the commercial potential of spider silk, the production performance requirements for commercialization, and impact of alternative technologies on the sustainability of the system.

  4. Spider assemblage (Arachnida: Araneae associated with canopies of Vochysia divergens (Vochysiaceae in the northern region of the Brazilian Pantanal

    Directory of Open Access Journals (Sweden)

    Leandro D. Battirola

    Full Text Available ABSTRACT This study describes the composition and temporal variation of the spider assemblage (Arachnida: Araneae associated with canopies of Vochysia divergens Pohl. (Vochysiaceae in the northern region of the Brazilian Pantanal. Three V. divergens plants were sampled in 2004, at each seasonal period of the northern Pantanal (high water, receding water, dry season and rising water, using thermonebulization of the canopies with insecticide, totaling 396 m2 of sampled canopies. Analysis of abundance and richness of spider families were based on Non-Metric Multidimensional Scaling (NMDS and Variance Analysis (ANOVA and MANOVA. A total of 7,193 spiders were collected (6,330 immatures; 88.0%; 863 adults, 12.0% distributed in 30 families. Araneidae (1,676 individuals, Anyphaenidae (1,631 individuals, Salticidae (1,542 individuals and Pisauridae (906 individuals, were predominant, representing 80.0% of the sample. Ten different guilds were registered: aerial hunters, orb-weavers, nocturnal aerial runners and diurnal space web weavers dominated, sharing most ecological niches. The spider assemblage is affected by changes in the habitat structure, especially by the seasonal hydrological regime and variations in the phenology of V. divergens . The assemblage is composed of different groups of spiders. The dominant taxa and behavioral guilds differ in the different seasonal periods. Spiders were more abundant during the dry and rising water seasons, most likely reflecting a greater supply of potential prey, associated with new foliage and flowering at the canopy. The displacement of soil dwelling spiders to the trunks and canopies before and during the seasonal floods can change the structure and composition of the canopy assemblages. Oonopidae, Gnaphosidae and Caponiidae, were more frequent during the rising and high water seasons, which indicates that these taxa use the canopies of V. divergens as a refuge during the seasonal flooding in the Pantanal.

  5. Cognitive bias in spider-phobic children: Comparison of a pictorial and a linguistic spider Stroop.

    NARCIS (Netherlands)

    Kindt, M.; Brosschot, J.F.

    1999-01-01

    Examined the relation between spider fear in children and cognitive processing bias toward threatening information. It was investigated whether spider fear in children is related to a cognitive bias for threatening pictures and words. Pictorial and linguistic Stroop stimuli were administered to 28

  6. Spin current

    CERN Document Server

    Valenzuela, Sergio O; Saitoh, Eiji; Kimura, Takashi

    2012-01-01

    In a new branch of physics and technology called spin-electronics or spintronics, the flow of electrical charge (usual current) as well as the flow of electron spin, the so-called 'spin current', are manipulated and controlled together. This book provides an introduction and guide to the new physics and application of spin current.

  7. Plasticity in extended phenotypes: orb web architectural responses to variations in prey parameters.

    Science.gov (United States)

    Blamires, Sean J

    2010-09-15

    A spider orb web is an extended phenotype; it modifies and interacts with the environment, influencing spider physiology. Orb webs are plastic, responding to variations in prey parameters. Studies attempting to understand how nutrients influence spider orb-web plasticity have been hampered by the inability to decouple prey nutrients from other, highly correlated, prey factors and the intrinsic link between prey protein and prey energy concentration. I analyzed the nutrient concentrations of cockroaches, and adult and juvenile crickets to devise experiments that controlled prey protein concentration while varying prey size, ingested mass, energy concentration and feeding frequency of the orb web spider Argiope keyserlingi. I found that A. keyserlingi alters overall architecture according to feeding frequency. Decoration length was inversely related to ingested prey mass and/or energy density in one experiment but directly related to ingested prey mass in another. These contradictory results suggest that factors not examined in this study have a confounding influence on decoration plasticity. As decorations attract prey as well as predators decreasing decoration investment may, in some instances, be attributable to benefits no longer outweighing the risks. Web area was altered according to feeding frequency, and mesh size altered according to feeding frequency and prey length. The number of radii in orb webs was unaffected by prey parameters. A finite amount of silk can be invested in the orb web, so spiders trade-off smaller mesh size with larger web capture area, explaining why feeding frequency influenced both web area and mesh size. Mesh size is additionally responsive to prey size via sensory cues, with spiders constructing webs suitable for catching the most common or most profitable prey.

  8. Discovery of fossil spider remains in Tertiary soft brown coal

    Energy Technology Data Exchange (ETDEWEB)

    Manewald, U.; Heimer, S.; Volkman, N.

    1986-11-01

    A fossil spring spider (Salticidae) is described, discovered in a 1 cm/sup 3/ void of a lower Miocene brown coal seam in Bitterfeld (GDR). The spider's hair, chelicerae and legs are well preserved. A photograph of the cephalothorax is provided. In the same coal seam egg cocoons of other spiders were also found and are shown in two further microscopic photographs. Conclusions are drawn on spider fossilization, sedimentation and paleoenvironment of the Miocene coal seam 8 references.

  9. Ultra-high Thermal Conductivity of Spider Silk: Protein Function Study with Controlled Structure Change and Comparison

    Science.gov (United States)

    2016-01-23

    ns ity ( 10 4 a .u .) Raman shift (cm-1) Fiber type scaffold gravity bridge healthy 6 (5). Thermal transport in Loxosceles laeta silk and...effect of spinning speed on  The thermal diffusivity of another type of spider ( Loxosceles laeta , Ll) silk was studied in this section. This was the...spectra of Nephila clavipes (a) and Loxosceles laeta (b) major ampullate silks spun at different rates. Their thermal diffusivity ranged from 3.44

  10. SPIDER OR NO SPIDER? NEURAL CORRELATES OF SUSTAINED AND PHASIC FEAR IN SPIDER PHOBIA.

    Science.gov (United States)

    Münsterkötter, Anna Luisa; Notzon, Swantje; Redlich, Ronny; Grotegerd, Dominik; Dohm, Katharina; Arolt, Volker; Kugel, Harald; Zwanzger, Peter; Dannlowski, Udo

    2015-09-01

    Processes of phasic fear responses to threatening stimuli are thought to be distinct from sustained, anticipatory anxiety toward an unpredicted, potential threat. There is evidence for dissociable neural correlates of phasic fear and sustained anxiety. Whereas increased amygdala activity has been associated with phasic fear, sustained anxiety has been linked with activation of the bed nucleus of stria terminalis (BNST), anterior cingulate cortex (ACC), and the insula. So far, only a few studies have focused on the dissociation of neural processes related to both phasic and sustained fear in specific phobia. We suggested that first, conditions of phasic and sustained fear would involve different neural networks and, second, that overall neural activity would be enhanced in a sample of phobic compared to nonphobic participants. Pictures of spiders and neutral stimuli under conditions of either predicted (phasic) or unpredicted (sustained) fear were presented to 28 subjects with spider phobia and 28 nonphobic control subjects during functional magnetic resonance imaging (fMRI) scanning. Phobic patients revealed significantly higher amygdala activation than controls under conditions of phasic fear. Sustained fear processing was significantly related to activation in the insula and ACC, and phobic patients showed a stronger activation than controls of the BNST and the right ACC under conditions of sustained fear. Functional connectivity analysis revealed enhanced connectivity of the BNST and the amygdala in phobic subjects. Our findings support the idea of distinct neural correlates of phasic and sustained fear processes. Increased neural activity and functional connectivity in these networks might be crucial for the development and maintenance of anxiety disorders. © 2015 Wiley Periodicals, Inc.

  11. Sex-specific kleptoparasitic foraging in ant-eating spiders

    DEFF Research Database (Denmark)

    Martisová, Martina; Bilde, T.; Pekar, Stano

    2009-01-01

    . To investigate this hypothesis, we studied the effect of sex and life history stage on the frequency of kleptoparasitism in ant-eating spiders of the genus Zodarion in the field. These spiders use a special capture technique involving a quick attack on an ant that is left unguarded by spiders for several minutes...

  12. Acute Generalized Exanthematous Pustulosis (AGEP Triggered by a Spider Bite

    Directory of Open Access Journals (Sweden)

    Michael Makris

    2009-01-01

    Discussion: A spider bite may represent a possible causative factor of AGEP. A spider's venom contains sphingomyelinase that stimulates the release of IL8 and GM-CSF, which are involved in AGEP pathogenesis. Whether or not the con-current use of antibiotics has an effect in AGEP appearance when combined with a spider's venom, cannot be excluded.

  13. A checklist of the spiders (Arachnida, Araneae of the Polokwane Nature Reserve, Limpopo Province, South Africa

    Directory of Open Access Journals (Sweden)

    Susan M. Dippenaar

    2008-05-01

    Full Text Available As part of the South African National Survey of Arachnida (SANSA, spiders were collected from all the field layers in the Polokwane Nature Reserve (Limpopo Province, South Africa over a period of a year (2005–2006 using four collecting methods. Six habitat types were sampled: Acacia tortillis open savanna; A. rehmanniana woodland, false grassland, riverine and sweet thorn thicket, granite outcrop; and Aloe marlothii thicket. A total of 13 821 spiders were collected (using sweep netting, tree beating, active searching and pitfall trapping represented by 39 families, 156 determined genera and 275 species. The most diverse families are the Thomisidae (42 spp., Araneidae (39 spp. and Salticidae (29 spp.. A total of 84 spp. (30.5% were web builders and 191 spp. (69.5% wanderers. In the Polokwane Nature Reserve, 13.75% of South African species are presently protected.

  14. The particle in the spider's web: transport through biological hydrogels.

    Science.gov (United States)

    Witten, Jacob; Ribbeck, Katharina

    2017-06-22

    Biological hydrogels such as mucus, extracellular matrix, biofilms, and the nuclear pore have diverse functions and compositions, but all act as selectively permeable barriers to the diffusion of particles. Each barrier has a crosslinked polymeric mesh that blocks penetration of large particles such as pathogens, nanotherapeutics, or macromolecules. These polymeric meshes also employ interactive filtering, in which affinity between solutes and the gel matrix controls permeability. Interactive filtering affects the transport of particles of all sizes including peptides, antibiotics, and nanoparticles and in many cases this filtering can be described in terms of the effects of charge and hydrophobicity. The concepts described in this review can guide strategies to exploit or overcome gel barriers, particularly for applications in diagnostics, pharmacology, biomaterials, and drug delivery.

  15. Spider mite web mediates anti-predator behaviour

    NARCIS (Netherlands)

    Lemos, F.; de Almeida Sarmento, R.; Pallini, A.; Rosa Dias, C.; Sabelis, M.W.; Janssen, A.

    2010-01-01

    Herbivores suffer significant mortality from predation and are therefore subject to natural selection on traits promoting predator avoidance and resistance. They can employ an array of strategies to reduce predation, for example through changes in behaviour, morphology and life history. So far, the

  16. The response of spider (Araneae assemblages to structural heterogeneity and prey abundance in sub-montane vegetation modified by conservation grazing

    Directory of Open Access Journals (Sweden)

    Peter Dennis

    2015-01-01

    Full Text Available The effect of experimental livestock grazing regimens (4 treatments×6 replicates on spiders via habitat structure and prey abundance was investigated on sub-montane habitats in the Southern Highlands of Scotland. The study, 2002–2004 included a baseline survey under the prior, commercial sheep grazing regimen and two assessments of spider assemblages post-treatment: commercial stocking density of sheep; 1/3 stocking density with sheep; 1/3 stocking density cattle with sheep; and no grazing. Spiders were sampled with a suction sampler, five sucks at each of 25 sample units by 24 plots (600 samples in 2003 and 2004, ca. 320 in 2002. Spider abundance and species richness increased under reduced stocking density, mixed herbivore and ungrazed treatments indirectly via changes in vegetation structure and prey abundance. The results refuted a meta-analysis that concluded species richness of spiders is unaffected by grazing. Grazing regimens caused turnover in species composition more than the net difference in species richness suggested, implying that no single, optimal grazing regimen will support as many species as a patchwork under varied grazing management. Conservation grazing benefits spiders and will have significant benefits for food webs in sub-montane ecosystems but the period to equilibrium after changes to grazing requires further investigation.

  17. Physical characterization of functionalized spider silk: electronic and sensing properties

    Directory of Open Access Journals (Sweden)

    Eden Steven, Jin Gyu Park, Anant Paravastu, Elsa Branco Lopes, James S Brooks, Ongi Englander, Theo Siegrist, Papatya Kaner and Rufina G Alamo

    2011-01-01

    Full Text Available This work explores functional, fundamental and applied aspects of naturally harvested spider silk fibers. Natural silk is a protein polymer where different amino acids control the physical properties of fibroin bundles, producing, for example, combinations of β-sheet (crystalline and amorphous (helical structural regions. This complexity presents opportunities for functional modification to obtain new types of material properties. Electrical conductivity is the starting point of this investigation, where the insulating nature of neat silk under ambient conditions is described first. Modification of the conductivity by humidity, exposure to polar solvents, iodine doping, pyrolization and deposition of a thin metallic film are explored next. The conductivity increases exponentially with relative humidity and/or solvent, whereas only an incremental increase occurs after iodine doping. In contrast, iodine doping, optimal at 70 °C, has a strong effect on the morphology of silk bundles (increasing their size, on the process of pyrolization (suppressing mass loss rates and on the resulting carbonized fiber structure (that becomes more robust against bending and strain. The effects of iodine doping and other functional parameters (vacuum and thin film coating motivated an investigation with magic angle spinning nuclear magnetic resonance (MAS-NMR to monitor doping-induced changes in the amino acid-protein backbone signature. MAS-NMR revealed a moderate effect of iodine on the helical and β-sheet structures, and a lesser effect of gold sputtering. The effects of iodine doping were further probed by Fourier transform infrared (FTIR spectroscopy, revealing a partial transformation of β-sheet-to-amorphous constituency. A model is proposed, based on the findings from the MAS-NMR and FTIR, which involves iodine-induced changes in the silk fibroin bundle environment that can account for the altered physical properties. Finally, proof

  18. Spider Invasion Across the Galaxy

    Directory of Open Access Journals (Sweden)

    Chung-Yue Hui

    2014-06-01

    Full Text Available The nature of the exotic stellar corpses which reincarnate by consuming their companion is reviewed. Apart from sucking life from their partners, they are actually eating the doomed companions away by their deadly and powerful particle/radiation beams. Such situation resembles that a female “black widow” spider that eats its mate after mating. These celestial zombies are called - Millisecond pulsars (MSPs. In this review article, I will focus on the effort of Fermi Asian Network (FAN in exploring these intricating objects over the last five years. Two special classes of MSPs are particularly striking. Since Fermi Gamma-ray Space Telescope has started surveying the gamma−ray sky, the population of “black widows” has been boosted. Another dramatic class is so-called “redbacks” (Australian cousin of “black widows” which has just emerged in the last few years. These MSPs provide us with a long-sought missing link in understanding the transition between accretion-powered and rotation-powered systems. The strategy of hunting MSPs through mulitwavelength observations of the unidentified Fermi objects is also reviewed.

  19. Spider Invasion Across the Galaxy

    Science.gov (United States)

    Hui, Chung-Yue

    2014-06-01

    The nature of the exotic stellar corpses which reincarnate by consuming their companion is reviewed. Apart from sucking life from their partners, they are actually eating the doomed companions away by their deadly and powerful particle/radiation beams. Such situation resembles that a female ¡°black widow¡± spider that eats its mate after mating. These celestial zombies are called - Millisecond pulsars (MSPs). In this review article, I will focus on the effort of Fermi Asian Network (FAN) in exploring these intricating objects over the last five years. Two special classes of MSPs are particularly striking. Since Fermi Gamma-ray Space Telescope has started surveying the gamma?ray sky, the population of ¡°black widows¡± has been boosted. Another dramatic class is so-called ¡°redbacks¡± (Australian cousin of ¡°black widows¡±) which has just emerged in the last few years. These MSPs provide us with a long-sought missing link in understanding the transition between accretion-powered and rotation-powered systems. The strategy of hunting MSPs through mulitwavelength observations of the unidentified Fermi objects is also reviewed.

  20. Edge effect on weevils and spiders

    Directory of Open Access Journals (Sweden)

    R. Horváth

    2002-05-01

    Full Text Available The edge effect on weevils and spiders was tested along oak forest – meadow transects using sweep-net samples at the Síkfökút Project in Hungary. For spiders the species richness was significantly higher in the forest edge than either in the meadow or the forest interior. For weevils the species richness of the forest edge was higher than that of the meadow, but the difference was not statistically significant whereas the species richness of the forest interior was significantly lower than that of the forest edge and the meadow. The composition of the spider assemblage of the edge was more similar to the forest, while the composition of weevils in the edge was more similar to the meadow. Our results based on two invertebrate groups operating on different trophic levels suggest that there is a significant edge effect for the studied taxa resulting in higher species richness in the edge.

  1. Relations between metals (Zn, Pb, Cd and Cu) and glutathione-dependent detoxifying enzymes in spiders from a heavy metal pollution gradient

    International Nuclear Information System (INIS)

    Wilczek, Grazyna; Babczynska, Agnieszka; Augustyniak, Maria; Migula, Pawel

    2004-01-01

    We studied the relations between glutathione-dependent detoxifying enzymes and heavy metal burdens in the web-building spider Agelena labyrinthica (Agelenidae) and the wolf spider Pardosa lugubris (Lycosidae) from five meadow sites along a heavy metal pollution gradient. We assayed the activity of glutathione-S-transferase (GST) and glutathione peroxidases (GPOX, GSTPx), and glutathione (GSH) levels in both sexes. Except for GSH vs Pb content, we found significant correlations between GPOX and GSTPx activity and metal concentrations in females of A. labyrinthica. The highest activity of these enzymes measured in the web-building spiders was found in the individuals from the most polluted sites. In P. lugubris males significant correlations were found between GST and Pb and Zn concentrations, and between GPOX and GSTPx and the concentration of Cu. GST activity was higher in males collected from less polluted areas. Thus, detoxifying strategies against pollutants seemed to be sex-dependent. Actively hunting spiders had higher metal concentrations, maintaining lower activity of detoxifying enzymes and a lower glutathione level. - Capsule: Glutathione-linked enzyme activity in spiders from polluted areas depends on hunting strategy and sex

  2. Quasistatic and continuous dynamic characterization of the mechanical properties of silk from the cobweb of the black widow spider Latrodectus hesperus.

    Science.gov (United States)

    Blackledge, Todd A; Swindeman, John E; Hayashi, Cheryl Y

    2005-05-01

    Spider silks are among the strongest and toughest known materials, but investigation of these remarkable properties has been confined largely to orb-weaving spiders. We investigated the mechanical performance of silk from the cobweb-weaving spider Latrodectus hesperus. Both silk from the scaffolding region of the web and sticky gumfooted capture lines had material properties similar to the major ampullate silk that orb weavers use as the framework for their orb webs. Major ampullate fibers obtained from anaesthetized Latrodectus spiders were similar, but exhibited increased stiffness and reduced extensibility. Novel continuous dynamic analysis of the silks revealed that the loss tangent (tandelta) increased rapidly during the first 2-3% of extension and reached a maximum near the yield point of fibers. The loss tangent then rapidly declined at an ever-decreasing rate until failure. We suggest that these data support molecular models for the mechanics of spider silk. We also demonstrate that the addition of sticky aggregate glue to the ends of the gumfooted lines modulates their mechanical performance--reducing stiffness and increasing extensibility. The storage modulus of viscid regions of the gumfooted lines was much lower than dry regions. This may be explained by disruption of hydrogen bonding within the amorphous regions of the fibers due to hydration from the glue.

  3. Disentangling the phylogenetic and ecological components of spider phenotypic variation.

    Science.gov (United States)

    Gonçalves-Souza, Thiago; Diniz-Filho, José Alexandre Felizola; Romero, Gustavo Quevedo

    2014-01-01

    An understanding of how the degree of phylogenetic relatedness influences the ecological similarity among species is crucial to inferring the mechanisms governing the assembly of communities. We evaluated the relative importance of spider phylogenetic relationships and ecological niche (plant morphological variables) to the variation in spider body size and shape by comparing spiders at different scales: (i) between bromeliads and dicot plants (i.e., habitat scale) and (ii) among bromeliads with distinct architectural features (i.e., microhabitat scale). We partitioned the interspecific variation in body size and shape into phylogenetic (that express trait values as expected by phylogenetic relationships among species) and ecological components (that express trait values independent of phylogenetic relationships). At the habitat scale, bromeliad spiders were larger and flatter than spiders associated with the surrounding dicots. At this scale, plant morphology sorted out close related spiders. Our results showed that spider flatness is phylogenetically clustered at the habitat scale, whereas it is phylogenetically overdispersed at the microhabitat scale, although phylogenic signal is present in both scales. Taken together, these results suggest that whereas at the habitat scale selective colonization affect spider body size and shape, at fine scales both selective colonization and adaptive evolution determine spider body shape. By partitioning the phylogenetic and ecological components of phenotypic variation, we were able to disentangle the evolutionary history of distinct spider traits and show that plant architecture plays a role in the evolution of spider body size and shape. We also discussed the relevance in considering multiple scales when studying phylogenetic community structure.

  4. Checklist of spider fauna of FR Peshawar, FATA, Pakistan

    Directory of Open Access Journals (Sweden)

    F. Perveen

    2012-03-01

    Full Text Available The spiders are known as poisonous arthropods, but they also act as the predator or biological pests control agent. Their 23 species belonging to 15 genera and 09 families were reported during 2009-2010 from FR Peshawar, FATA, Pakistan. The reported families Clubionidae, Scytodidae and Sprassidae covered each 4%, Araneidae, Gnaphosidae, Pholicidae and Salticidae each 9%, Thomisidae 13% and Lycosidae 43% biodiversity of spiders of FATA. However, the largest spider collected was huntsman, Isopoda tuhodnigra (Barrion with total body length 15.80+-0.83 mm. Moreover, the smallest spider was wolf spider, Pardosa birmanica (Simon with total body length 4.20+-1.30 mm. Further, the crab spiders, Thomisus pugilis (Stoliczka, T. spectabilis (Doleschall and Diaea evanida (Thorell were the most colorful species belonging to family Thomisidae. A detail study is required for further exploration of spider fauna of FATA.

  5. Uncovering the structure-function relationship in spider silk

    Science.gov (United States)

    Yarger, Jeffery L.; Cherry, Brian R.; van der Vaart, Arjan

    2018-03-01

    All spiders produce protein-based biopolymer fibres that we call silk. The most studied of these silks is spider dragline silk, which is very tough and relatively abundant compared with other types of spider silks. Considerable research has been devoted to understanding the relationship between the molecular structure and mechanical properties of spider dragline silks. In this Review, we overview experimental and computational studies that have provided a wealth of detail at the molecular level on the highly conserved repetitive core and terminal regions of spider dragline silk. We also discuss the role of the nanocrystalline β-sheets and amorphous regions in determining the properties of spider silk fibres, endowing them with strength and elasticity. Additionally, we outline imaging techniques and modelling studies that elucidate the importance of the hierarchical structure of silk fibres at the molecular level. These insights into structure-function relationships can guide the reverse engineering of spider silk to enable the production of superior synthetic fibres.

  6. Black widow spider bite: a case study.

    Science.gov (United States)

    Gaisford, Kristine; Kautz, Donald D

    2011-01-01

    This article is a case study of a patient cared for in the hours before her death. After the patient's death, we learned the patient died of a black widow spider bite. This article sheds light on the potential seriousness of this venom and allows for more rapid detection and treatment of those who are unfortunate enough to be bitten. The authors have documented the sequence of events for the patient, outlined the care the patient received, examined the pathophysiology of the body to a spider bite, and then made a passionate appeal for other nurses who work in critical care to do the same with patients in similar situations.

  7. Fish Predation by Semi-Aquatic Spiders: A Global Pattern

    Science.gov (United States)

    Nyffeler, Martin; Pusey, Bradley J.

    2014-01-01

    More than 80 incidences of fish predation by semi-aquatic spiders – observed at the fringes of shallow freshwater streams, rivers, lakes, ponds, swamps, and fens – are reviewed. We provide evidence that fish predation by semi-aquatic spiders is geographically widespread, occurring on all continents except Antarctica. Fish predation by spiders appears to be more common in warmer areas between 40° S and 40° N. The fish captured by spiders, usually ranging from 2–6 cm in length, are among the most common fish taxa occurring in their respective geographic area (e.g., mosquitofish [Gambusia spp.] in the southeastern USA, fish of the order Characiformes in the Neotropics, killifish [Aphyosemion spp.] in Central and West Africa, as well as Australian native fish of the genera Galaxias, Melanotaenia, and Pseudomugil). Naturally occurring fish predation has been witnessed in more than a dozen spider species from the superfamily Lycosoidea (families Pisauridae, Trechaleidae, and Lycosidae), in two species of the superfamily Ctenoidea (family Ctenidae), and in one species of the superfamily Corinnoidea (family Liocranidae). The majority of reports on fish predation by spiders referred to pisaurid spiders of the genera Dolomedes and Nilus (>75% of observed incidences). There is laboratory evidence that spiders from several more families (e.g., the water spider Argyroneta aquatica [Cybaeidae], the intertidal spider Desis marina [Desidae], and the ‘swimming’ huntsman spider Heteropoda natans [Sparassidae]) predate fish as well. Our finding of such a large diversity of spider families being engaged in fish predation is novel. Semi-aquatic spiders captured fish whose body length exceeded the spiders’ body length (the captured fish being, on average, 2.2 times as long as the spiders). Evidence suggests that fish prey might be an occasional prey item of substantial nutritional importance. PMID:24940885

  8. ­Comparative spigot ontogeny across the spider tree of life

    Directory of Open Access Journals (Sweden)

    Rachael E. Alfaro

    2018-01-01

    Full Text Available Spiders are well known for their silk and its varying use across taxa. Very few studies have examined the silk spigot ontogeny of the entire spinning field of a spider. Historically the spider phylogeny was based on morphological data and behavioral data associated with silk. Recent phylogenomics studies have shifted major paradigms in our understanding of silk use evolution, reordering phylogenetic relationships that were once thought to be monophyletic. Considering this, we explored spigot ontogeny in 22 species, including Dolomedes tenebrosus and Hogna carolinensis, reported here for the first time. This is the first study of its kind and the first to incorporate the Araneae Tree of Life. After rigorous testing for phylogenetic signal and model fit, we performed 60 phylogenetic generalized least squares analyses on adult female and second instar spigot morphology. Six analyses had significant correlation coefficients, suggesting that instar, strategy, and spigot variety are good predictors of spigot number in spiders, after correcting for bias of shared evolutionary history. We performed ancestral character estimation of singular, fiber producing spigots on the posterior lateral spinneret whose potential homology has long been debated. We found that the ancestral root of our phylogram of 22 species, with the addition of five additional cribellate and ecribellate lineages, was more likely to have either none or a modified spigot rather than a pseudoflagelliform gland spigot or a flagelliform spigot. This spigot ontogeny approach is novel and we can build on our efforts from this study by growing the dataset to include deeper taxon sampling and working towards the capability to incorporate full ontogeny in the analysis.

  9. Reversible Myocarditis after Black Widow Spider Envenomation

    Directory of Open Access Journals (Sweden)

    Tarek Dendane

    2012-01-01

    Full Text Available Black widow spiders can cause variable clinical scenarios from local damage to very serious conditions including death. Acute myocardial damage is rarely observed and its prognostic significance is not known. We report a rare case of a 35-year-old man who developed an acute myocarditis with cardiogenic pulmonary edema requiring mechanical ventilation caused by black widow spider's envenomation. The patient was previously healthy. The clinical course was associated with systemic and cardiovascular complaints. His electrocardiogram revealed ST-segment elevation with T-wave amplitude. The plasma concentrations of cardiac enzymes were elevated. His first echocardiography showed hypokinesis of the left ventricle (left ventricle ejection fraction 48%. Magnetic resonance imaging showed also focal myocardial injury of the LV. There was progressive improvement in cardiac traces, biochemical and echocardiographical values (second left ventricle ejection fraction increased to 50%. Myocardial involvement after a spider bite is rare and can cause death. The exact mechanism of this myocarditis is unknown. We report a rare case of acute myocarditis with cardiogenic pulmonary edema requiring mechanical ventilation caused by black widow spider's envenomation. We objectively documented progressive clinical and electrical improvement.

  10. Reversible myocarditis after black widow spider envenomation.

    Science.gov (United States)

    Dendane, Tarek; Abidi, Khalid; Madani, Naoufel; Benthami, Asmae; Gueddari, Fatima-Zohra; Abouqal, Redoune; Zeggwagh, Amine-Ali

    2012-01-01

    Black widow spiders can cause variable clinical scenarios from local damage to very serious conditions including death. Acute myocardial damage is rarely observed and its prognostic significance is not known. We report a rare case of a 35-year-old man who developed an acute myocarditis with cardiogenic pulmonary edema requiring mechanical ventilation caused by black widow spider's envenomation. The patient was previously healthy. The clinical course was associated with systemic and cardiovascular complaints. His electrocardiogram revealed ST-segment elevation with T-wave amplitude. The plasma concentrations of cardiac enzymes were elevated. His first echocardiography showed hypokinesis of the left ventricle (left ventricle ejection fraction 48%). Magnetic resonance imaging showed also focal myocardial injury of the LV. There was progressive improvement in cardiac traces, biochemical and echocardiographical values (second left ventricle ejection fraction increased to 50%). Myocardial involvement after a spider bite is rare and can cause death. The exact mechanism of this myocarditis is unknown. We report a rare case of acute myocarditis with cardiogenic pulmonary edema requiring mechanical ventilation caused by black widow spider's envenomation. We objectively documented progressive clinical and electrical improvement.

  11. Spiders Tune Glue Viscosity to Maximize Adhesion.

    Science.gov (United States)

    Amarpuri, Gaurav; Zhang, Ci; Diaz, Candido; Opell, Brent D; Blackledge, Todd A; Dhinojwala, Ali

    2015-11-24

    Adhesion in humid conditions is a fundamental challenge to both natural and synthetic adhesives. Yet, glue from most spider species becomes stickier as humidity increases. We find the adhesion of spider glue, from five diverse spider species, maximizes at very different humidities that matches their foraging habitats. By using high-speed imaging and spreading power law, we find that the glue viscosity varies over 5 orders of magnitude with humidity for each species, yet the viscosity at maximal adhesion for each species is nearly identical, 10(5)-10(6) cP. Many natural systems take advantage of viscosity to improve functional response, but spider glue's humidity responsiveness is a novel adaptation that makes the glue stickiest in each species' preferred habitat. This tuning is achieved by a combination of proteins and hygroscopic organic salts that determines water uptake in the glue. We therefore anticipate that manipulation of polymer-salts interaction to control viscosity can provide a simple mechanism to design humidity responsive smart adhesives.

  12. Hey! A Black Widow Spider Bit Me!

    Science.gov (United States)

    ... as soon as you can because they can make you very sick. With an adult's help, wash the bite well with soap and water. Then apply an ice pack to the bite, and try to elevate the area and keep it still to help prevent the ... black widows, you'll want to make sure that's the kind of spider that bit ...

  13. The aerodynamic signature of running spiders.

    Directory of Open Access Journals (Sweden)

    Jérôme Casas

    Full Text Available Many predators display two foraging modes, an ambush strategy and a cruising mode. These foraging strategies have been classically studied in energetic, biomechanical and ecological terms, without considering the role of signals produced by predators and perceived by prey. Wolf spiders are a typical example; they hunt in leaf litter either using an ambush strategy or by moving at high speed, taking over unwary prey. Air flow upstream of running spiders is a source of information for escaping prey, such as crickets and cockroaches. However, air displacement by running arthropods has not been previously examined. Here we show, using digital particle image velocimetry, that running spiders are highly conspicuous aerodynamically, due to substantial air displacement detectable up to several centimetres in front of them. This study explains the bimodal distribution of spider's foraging modes in terms of sensory ecology and is consistent with the escape distances and speeds of cricket prey. These findings may be relevant to the large and diverse array of arthropod prey-predator interactions in leaf litter.

  14. Spider silk MASP1 and MASP2 proteins as carbon fiber precursors

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, Randolph V [Utah State Univ., Logan, UT (United States)

    2017-06-14

    The objective of this project is to develop an unconventional non-petroleum based carbon fiber precursor which has the potential to be produced in high yield and quantities. Methods will be developed to produce pilot-scale quantities of fibers from spider silk proteins with mechanical properties at least 75% that of the natural dragline silk fibers in tensile strength and elongations of less than 5%. The precursor fibers will be converted to carbon fibers, with a goal of >250Ksi strength and 1-2% elongation. Cost analysis will be performed and the process optimized. Task 1: Subtask 1. Protein production: We exceeded the go/ no go milestone of 1.0g/L of one of the spider silk protein (MSp2) purified last FY and have now increased from 5L to 500L fermentations. We have made a series of changes to the purification protocol from the initial report last FY. These led to a reduction in the time needed for the purification and reduced the purification costs by nearly 90%. Subtask 2. Fiber spinning: The major focus has been to produce more material to send 24 fiber thread to ONRL. We are still developing the methodology to successfully spin 24 fiber yarns. This involves both the spinning dope solutions as well as the methods to keep the fibers from fusing during the post spin stretch. The second area of focus has been to standardize the spin dopes for making the fibers. We now know that the conductivity (indicative of salt remaining with the protein after purification) is an important factor in successful spinning as is the pH. We now know that we need to be below 600 uS conductivity and that the most effective pH is protein dependent. Subtask 3. Silkworm silk: We have found the transgenic silkworms made using gene replacement at the fibroin light chain instead of heavy chain as we did previously have a higher tensile strength. See figures below showing the curve for the top end of the cocoon fibers. This tensile strength is the same as the average for spider dragline silk

  15. Gumfooted lines in black widow cobwebs and the mechanical properties of spider capture silk.

    Science.gov (United States)

    Blackledge, Todd A; Summers, Adam P; Hayashi, Cheryl Y

    2005-01-01

    Orb-weaving spiders produce webs using two types of silk that have radically different mechanical properties. The dragline silk used to construct the supporting frame and radii of the web is stiff and as strong as steel, while the capture spiral is much weaker but more than ten times as extensible. This remarkable divergence in mechanical properties has been attributed to the aqueous glue that coats the capture spiral, which is thought to decrease capture spiral stiffness and increase its extensibility. However, discerning the effect of the aqueous glue on fiber performance is complicated because dragline silk and the capture spiral are assembled from different proteins, which may also affect mechanical performance. Here, we use the sticky gumfooted lines of black widow cobwebs to test the effect of the addition of aqueous glue on the mechanical properties of dragline silk. We also surveyed orb-webs spun by a broad range of species for bundles of looped silk. Such bundles, termed windlasses, have been thought to increase capture spiral extensibility by "paying out" additional lengths of silk. Our results suggest that neither plasticization of silk by aqueous glue nor excess silk in windlasses can by themselves account for the remarkable extensibility of orb-weaver capture silk compared to other spider silks. This argues that the unique amino acid motifs of the flagelliform fibroins that constitute the core of the capture spiral play an essential role in capture silk's extreme extensibility.

  16. Task specialization in two social spiders, Stegodyphus sarasinorum (Eresidae) and Anelosimus eximius (Theridiidae)

    DEFF Research Database (Denmark)

    Settepani, Virginia; Grinsted, Lena; Pedersen, Jørgen Granfeldt

    2013-01-01

    specialization, but in distinctly different ways: Stegodyphus sarasinorum showed behavioural asymmetries at the individual level, that is, individual spiders that had attacked prey once were more likely to attack prey again, independent of their body size or hunger level. In contrast, Anelosimus eximius showed...... no individual specialization, but showed differentiation according to instar, where adult and subadult females were more likely to engage in prey attack than were juveniles. We found no evidence for division of labour between prey attack and web maintenance. Different solutions to achieve task differentiation...

  17. A checklist of spiders from Sovenga Hill, an inselberg in the Savanna Biome, Limpopo Province, South Africa (Arachnida: Araneae

    Directory of Open Access Journals (Sweden)

    M.A. Modiba

    2005-12-01

    Full Text Available The South African National Survey of Arachnida (SANSA was initiated to make an inventory of the arachnid fauna of South Africa. Various projects are underway to prepare inventories of the spider fauna of the different floral biomes and provinces of South Africa. During April and May 2004 five different collecting methods were sed to sample spiders from four slopes on Sovenga Hill, an inselberg situated in the Savanna Biome, near Polokwane, in the Limpopo Province of South Africa. A total of 793 specimens represented by 29 families, 62 genera and 76 species were recorded over the twomonth period. The Thomisidae was the most abundant (n = 167 representing 21.1 % of all spiders sampled, followed by the Gnaphosidae (n = 101 with 12.7 % and the Lycosidae (n = 77 with 9.7 %. The most abundant species was a thomisid Tmarus comellini Garcia-Neto (n = 82, representing 10.3 % of the total, followed by a clubionid Clubiona godfreyi Lessert (n = 66 with 8.3 %. The Thomisidae was the most species-rich family with 12 species, followed by the Gnaphosidae with 11 species and the Araneidae with 10 species. Of the species collected 83.9 % were wandering spiders and 16.1 % web builders. This is the first quantitative survey of the Savanna Biome in the Polokwane area.

  18. Tubuliform silk protein: A protein with unique molecular characteristics and mechanical properties in the spider silk fibroin family

    Science.gov (United States)

    Tian, M.; Lewis, R. V.

    2006-02-01

    Orb-web weavers can produce up to six different types of silk and a glue for various functions. Tubuliform silk is unique among them due to its distinct amino acid composition, specific time of production, and atypical mechanical properties. To study the protein composing this silk, tubuliform gland cDNA libraries were constructed from three orb-weaving spiders Argiope aurantia, Araneus gemmoides, and Nephila clavipes. Amino acid composition comparison between the predicted tubuliform silk protein sequence (TuSp1) and the corresponding gland protein confirms that TuSp1 is the major component in tubuliform gland in three spiders. Sequence analysis suggests that TuSp1 shares no significant similarity with its paralogues, while it has conserved sequence motifs with the most primitive spider, Euagrus chisoseus silk protein. The presence of large side-chain amino acids in TuSp1 sequence is consistent with the frustrated β-sheet crystalline structure of tubuliform silk observed in transmission electron microscopy. Repeat unit comparison within species as well as among three spiders exhibits high sequence conservation. Parsimony analysis based on carboxy terminal sequence shows that Argiope and Araneus are more closely related than either is to Nephila which is consistent with phylogenetic analysis based on morphological evidence.

  19. Acidic Residues Control the Dimerization of the N-terminal Domain of Black Widow Spiders' Major Ampullate Spidroin 1.

    Science.gov (United States)

    Bauer, Joschka; Schaal, Daniel; Eisoldt, Lukas; Schweimer, Kristian; Schwarzinger, Stephan; Scheibel, Thomas

    2016-09-29

    Dragline silk is the most prominent amongst spider silks and comprises two types of major ampullate spidroins (MaSp) differing in their proline content. In the natural spinning process, the conversion of soluble MaSp into a tough fiber is, amongst other factors, triggered by dimerization and conformational switching of their helical amino-terminal domains (NRN). Both processes are induced by protonation of acidic residues upon acidification along the spinning duct. Here, the structure and monomer-dimer-equilibrium of the domain NRN1 of Latrodectus hesperus MaSp1 and variants thereof have been investigated, and the key residues for both could be identified. Changes in ionic composition and strength within the spinning duct enable electrostatic interactions between the acidic and basic pole of two monomers which prearrange into an antiparallel dimer. Upon naturally occurring acidification this dimer is stabilized by protonation of residue E114. A conformational change is independently triggered by protonation of clustered acidic residues (D39, E76, E81). Such step-by-step mechanism allows a controlled spidroin assembly in a pH- and salt sensitive manner, preventing premature aggregation of spider silk proteins in the gland and at the same time ensuring fast and efficient dimer formation and stabilization on demand in the spinning duct.

  20. Ground Spider Guilds and Functional Diversity in Native Pine Woodlands and Eucalyptus Plantations.

    Science.gov (United States)

    Corcuera, Pablo; Valverde, Pedro Luis; Jiménez, María Luisa; Ponce-Mendoza, Alejandro; De la Rosa, Gabriela; Nieto, Gisela

    2016-04-01

    Vegetation structure and floristics have a strong influence on the relative abundance of spider guilds and functional diversity of terrestrial arthropods. Human activities have transformed much of the temperate woodlands. The aim of this study was to test five predictions related to the guild distribution and functional diversity of the ground spider communities of Eucalyptus plantations and native pine woodlands in western Mexico. Spiders were collected every fortnight from September to November from 15 pitfalls positioned in each of the eight sites. We also assessed the cover of grasses, herbs, shrubs, and leaf litter in each site. We found that the abundances of ground hunters and sheet weavers between plantations and pine woodlands were different. Nevertheless, there was not a consistent difference between sites of each of the vegetation types. Most species of ground hunters, sheet web weavers, and many other hunters were associated with litter and the grass cover. Nonetheless, in some cases, species of different families belonging to the same guild responded to different variables. Wolf spiders were related to the grass Aristida stricta Micheaux, 1803, while the species of the other families of ground hunters were associated with leaf litter. One Eucalyptus plantation and one pine woodland had the highest functional diversity of all sites. These sites have a well developed litter and grass cover. Our study suggests that the abundance of litter and a high cover of grasses explain the occurrence of species with different traits, and these habitat components results in a high functional diversity. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  1. A novel neurotoxin from venom of the spider, Brachypelma albopilosum.

    Science.gov (United States)

    Zhong, Yunhua; Song, Bo; Mo, Guoxiang; Yuan, Mingwei; Li, Hongli; Wang, Ping; Yuan, Minglong; Lu, Qiumin

    2014-01-01

    Spiders have evolved highly selective toxins for insects. There are many insecticidal neurotoxins in spider venoms. Although a large amount of work has been done to focus on neurotoxicity of spider components, little information, which is related with effects of spider toxins on tumor cell proliferation and cytotoxicity, is available for Brachypelma albopilosum venom. In this work, a novel spider neurotoxin (brachyin) was identified and characterized from venoms of the spider, Brachypelma albopilosum. Brachyin is composed of 41 amino acid residues with the sequence of CLGENVPCDKDRPNCCSRYECLEPTGYGWWYASYYCYKKRS. There are six cysteines in this sequence, which form three disulfided bridges. The serine residue at the C-terminus is amidated. Brachyin showed strong lethal effects on American cockroaches (Periplaneta americana) and Tenebrio molitor (common mealbeetle). This neurotoxin also showed significant analgesic effects in mice models including abdominal writhing induced by acetic acid and formalin-induced paw licking tests. It was interesting that brachyin exerted marked inhibition on tumor cell proliferation.

  2. A novel neurotoxin from venom of the spider, Brachypelma albopilosum.

    Directory of Open Access Journals (Sweden)

    Yunhua Zhong

    Full Text Available Spiders have evolved highly selective toxins for insects. There are many insecticidal neurotoxins in spider venoms. Although a large amount of work has been done to focus on neurotoxicity of spider components, little information, which is related with effects of spider toxins on tumor cell proliferation and cytotoxicity, is available for Brachypelma albopilosum venom. In this work, a novel spider neurotoxin (brachyin was identified and characterized from venoms of the spider, Brachypelma albopilosum. Brachyin is composed of 41 amino acid residues with the sequence of CLGENVPCDKDRPNCCSRYECLEPTGYGWWYASYYCYKKRS. There are six cysteines in this sequence, which form three disulfided bridges. The serine residue at the C-terminus is amidated. Brachyin showed strong lethal effects on American cockroaches (Periplaneta americana and Tenebrio molitor (common mealbeetle. This neurotoxin also showed significant analgesic effects in mice models including abdominal writhing induced by acetic acid and formalin-induced paw licking tests. It was interesting that brachyin exerted marked inhibition on tumor cell proliferation.

  3. Spin current

    CERN Document Server

    Valenzuela, Sergio O; Saitoh, Eiji; Kimura, Takashi

    2017-01-01

    Since the discovery of the giant magnetoresistance effect in magnetic multilayers in 1988, a new branch of physics and technology, called spin-electronics or spintronics, has emerged, where the flow of electrical charge as well as the flow of electron spin, the so-called “spin current,” are manipulated and controlled together. The physics of magnetism and the application of spin current have progressed in tandem with the nanofabrication technology of magnets and the engineering of interfaces and thin films. This book aims to provide an introduction and guide to the new physics and applications of spin current, with an emphasis on the interaction between spin and charge currents in magnetic nanostructures.

  4. Spider silk: a novel optical fibre for biochemical sensing

    OpenAIRE

    Hey Tow, Kenny; Chow, Desmond; Vollrath, Fritz; Dicaire, Isabelle; Gheysens, Tom; Thévenaz, Luc

    2015-01-01

    Whilst being thoroughly used in the textile industry and biomedical sector, silk has not yet been exploited for fibre optics-based sensing although silk fibres directly obtained from spiders can guide light and have shown early promises to being sensitive to some solvents. In this communication, a pioneering optical fibre sensor based on spider silk is reported, demonstrating for the first time the use of spider silk as an optical fibre sensor to detect polar solvents such as water, ammonia a...

  5. Spin Electronics

    Science.gov (United States)

    2003-08-01

    applications, a ferromagnetic metal may be used as a source of spin-polarized electronics to be injected into a semiconductor, a superconductor or a...physical phenomena in II-VI and III-V semiconductors. In II-VI systems, the Mn2+ ions act to boost the electron spin precession up to terahertz ...conductors, proximity effect between ferromagnets and superconductors , and the effects of spin injection on the physical properties of the

  6. Spin doctoring

    OpenAIRE

    Vozková, Markéta

    2011-01-01

    1 ABSTRACT The aim of this text is to provide an analysis of the phenomenon of spin doctoring in the Euro-Atlantic area. Spin doctors are educated people in the fields of semiotics, cultural studies, public relations, political communication and especially familiar with the infrastructure and the functioning of the media industry. Critical reflection of manipulative communication techniques puts spin phenomenon in historical perspective and traces its practical use in today's social communica...

  7. Araneae Sloveniae: a national spider species checklist

    Science.gov (United States)

    Kostanjšek, Rok; Kuntner, Matjaž

    2015-01-01

    Abstract The research of the spider fauna of Slovenia dates back to the very beginning of binomial nomenclature, and has gone through more and less prolific phases with authors concentrating on taxonomy, faunistics, ecology and zoogeographic reviews. Although the body of published works is remarkable for a small nation, the faunistic data has remained too scattered for a thorough understanding of regional biotic diversity, for comparative and ecological research, and for informed conservation purposes. A national checklist is long overdue. Here, a critical review of all published records in any language is provided. The species list currently comprises 738 species, is published online at http://www.bioportal.si/katalog/araneae.php under the title Araneae Sloveniae, and will be updated in due course. This tool will fill the void in cataloguing regional spider faunas and will facilitate further araneological research in central and southern Europe. PMID:25632258

  8. Araneae Sloveniae: a national spider species checklist

    Directory of Open Access Journals (Sweden)

    Rok Kostanjšek

    2015-01-01

    Full Text Available The research of the spider fauna of Slovenia dates back to the very beginning of binomial nomenclature, and has gone through more and less prolific phases with authors concentrating on taxonomy, faunistics, ecology and zoogeographic reviews. Although the body of published works is remarkable for a small nation, the faunistic data has remained too scattered for a thorough understanding of regional biotic diversity, for comparative and ecological research, and for informed conservation purposes. A national checklist is long overdue. Here, a critical review of all published records in any language is provided. The species list currently comprises 738 species, is published online at http://www.bioportal.si/katalog/araneae.php under the title Araneae Sloveniae, and will be updated in due course. This tool will fill the void in cataloguing regional spider faunas and will facilitate further araneological research in central and southern Europe.

  9. Frame-web-choice experiments with stingless bees support the prey-attraction hypothesis for silk decorations in Argiope savignyi

    NARCIS (Netherlands)

    Galvez, Dumas

    2009-01-01

    There is controversy about the function of silk stabilimenta, also called silk decorations, oil spiders' webs. Most of the proposed hypotheses have been tested using indirect methods. Protection against predators, advertisement for vertebrates to avoid web damage, and increasing prey attraction are

  10. Spin glasses

    CERN Document Server

    Bovier, Anton

    2007-01-01

    Spin glass theory is going through a stunning period of progress while finding exciting new applications in areas beyond theoretical physics, in particular in combinatorics and computer science. This collection of state-of-the-art review papers written by leading experts in the field covers the topic from a wide variety of angles. The topics covered are mean field spin glasses, including a pedagogical account of Talagrand's proof of the Parisi solution, short range spin glasses, emphasizing the open problem of the relevance of the mean-field theory for lattice models, and the dynamics of spin glasses, in particular the problem of ageing in mean field models. The book will serve as a concise introduction to the state of the art of spin glass theory, usefull to both graduate students and young researchers, as well as to anyone curious to know what is going on in this exciting area of mathematical physics.

  11. Automating Information Discovery Within the Invisible Web

    Science.gov (United States)

    Sweeney, Edwina; Curran, Kevin; Xie, Ermai

    A Web crawler or spider crawls through the Web looking for pages to index, and when it locates a new page it passes the page on to an indexer. The indexer identifies links, keywords, and other content and stores these within its database. This database is searched by entering keywords through an interface and suitable Web pages are returned in a results page in the form of hyperlinks accompanied by short descriptions. The Web, however, is increasingly moving away from being a collection of documents to a multidimensional repository for sounds, images, audio, and other formats. This is leading to a situation where certain parts of the Web are invisible or hidden. The term known as the "Deep Web" has emerged to refer to the mass of information that can be accessed via the Web but cannot be indexed by conventional search engines. The concept of the Deep Web makes searches quite complex for search engines. Google states that the claim that conventional search engines cannot find such documents as PDFs, Word, PowerPoint, Excel, or any non-HTML page is not fully accurate and steps have been taken to address this problem by implementing procedures to search items such as academic publications, news, blogs, videos, books, and real-time information. However, Google still only provides access to a fraction of the Deep Web. This chapter explores the Deep Web and the current tools available in accessing it.

  12. Red-back spider (Latrodectus hasselti) antivenom prevents the toxicity of widow spider venoms.

    Science.gov (United States)

    Graudins, A; Padula, M; Broady, K; Nicholson, G M

    2001-02-01

    Widow spiders of the genus Latrodectus are found worldwide and produce similar clinical envenomation syndromes. In Australia, red-back spider antivenom (RBS-AV) is effective therapy for Latrodectus hasselti envenomation and it has been reported to reverse envenomation by other widow spiders. This study assessed the efficacy of RBS-AV in preventing in vitro and in vivo toxicity of widow spider venoms of North America and Europe. The binding of RBS-AV to alpha-latrotoxin and Latrodectus venoms (Latrodectus spp mactans, hesperus, lugubris, tredecimguttatus, hasselti) was assayed using Western blotting. Prevention of in vitro toxicity to alpha-latrotoxin and the same venoms was tested by pretreating an isolated chick biventer cervicis nerve-muscle preparation with RBS-AV. Prevention of in vivo toxicity was determined by a lethality study in male Balb/c mice (2.5 to 5x median lethal dose [LD50]) or alpha-latrotoxin (10x LD50) preincubated with antivenom or without RBS-AV (control). In Western blots, RBS-AV bound to alpha-latrotoxin and similar widow spider proteins in all venoms tested, indicating antigenic similarity with proteins found in RBS venom. Antivenom prevented the typical in vitro muscle contracture and loss of twitch tension seen with alpha-latrotoxin and the venoms tested. Control mice rapidly developed signs of envenomation, but mice treated with RBS-AV remained free of signs of envenomation. RBS-AV prevented both in vitro and in vivo toxicity from Latrodectus venoms and alpha-latrotoxin in mice. These data suggest that RBS-AV may be clinically effective in the treatment of envenomation resulting from the bite of other widow spiders.

  13. Disentangling the phylogenetic and ecological components of spider phenotypic variation.

    Directory of Open Access Journals (Sweden)

    Thiago Gonçalves-Souza

    Full Text Available An understanding of how the degree of phylogenetic relatedness influences the ecological similarity among species is crucial to inferring the mechanisms governing the assembly of communities. We evaluated the relative importance of spider phylogenetic relationships and ecological niche (plant morphological variables to the variation in spider body size and shape by comparing spiders at different scales: (i between bromeliads and dicot plants (i.e., habitat scale and (ii among bromeliads with distinct architectural features (i.e., microhabitat scale. We partitioned the interspecific variation in body size and shape into phylogenetic (that express trait values as expected by phylogenetic relationships among species and ecological components (that express trait values independent of phylogenetic relationships. At the habitat scale, bromeliad spiders were larger and flatter than spiders associated with the surrounding dicots. At this scale, plant morphology sorted out close related spiders. Our results showed that spider flatness is phylogenetically clustered at the habitat scale, whereas it is phylogenetically overdispersed at the microhabitat scale, although phylogenic signal is present in both scales. Taken together, these results suggest that whereas at the habitat scale selective colonization affect spider body size and shape, at fine scales both selective colonization and adaptive evolution determine spider body shape. By partitioning the phylogenetic and ecological components of phenotypic variation, we were able to disentangle the evolutionary history of distinct spider traits and show that plant architecture plays a role in the evolution of spider body size and shape. We also discussed the relevance in considering multiple scales when studying phylogenetic community structure.

  14. Black widow spider envenomation in pregnancy.

    Science.gov (United States)

    Wolfe, Michael D; Myers, Orrin; Caravati, E Martin; Rayburn, William F; Seifert, Steven A

    2011-01-01

    Little data exist regarding the optimal treatment and outcomes of pregnancies complicated by black widow spider envenomation. Our objective is to evaluate the clinical effects, medical outcomes, and treatment differences between pregnant and nonpregnant women. This observational study is based on a review of the database maintained by the American Association of Poison Control Centers from 2003 to 2007. Of the 12,640 human black widow spider envenomations reported at 61 poison centers in the United States, 3194 (25.3%) involved women of reproductive age, defined as age 15-45 years of age, with 97 (3.0% of reproductive-age women) being pregnant. Comparing pregnant and nonpregnant women, there were no significant differences in recommended or administered treatments. Pregnant women were more likely than nonpregnant women (OR: 1.84, 95% CI: 1.20-2.83) to have outcomes coded as minor, moderate, or major rather than no effect. Significantly higher percentages of pregnant patients were treated at a healthcare facility where they were either released (36.1% vs. 19.9%, p  Black widow spider envenomation is a rare occurrence in pregnant women and the short-term outcomes appear to be favorable.

  15. Troponin elevation after black widow spider envenomation.

    Science.gov (United States)

    Bush, Sean P; Davy, J Veeran

    2015-09-01

    Black widow spider envenomation generally results in self-limiting pain that can be treated in the emergency department (ED) with analgesics and benzodiazepines, usually with no further intervention. Occasionally, a patient has to be admitted or treated with antivenom for refractory pain or a venom-induced complication. We present the case of an 84-year-old man who presented to our ED with chest pain and dyspnea after being bitten on the foot by a western black widow spider (Lactrodectus hesperus). His initial cardiac troponin I (cTnI) was elevated at 0.07 ng/ml and continued to rise to a peak of 0.17 ng/ml. He also had rhabdomyolysis, another uncommon complication of black widow envenomation. An elevated cTnI generally signifies myocardial injury and is rarely seen after black widow envenomation. We discuss the possible etiologies for an elevated cardiac biomarker, in this context, and review potentially serious complications of widow spider envenomation presenting with chest symptoms and an elevated cardiac biomarker.

  16. Nanofibre production in spiders without electric charge.

    Science.gov (United States)

    Joel, Anna-Christin; Baumgartner, Werner

    2017-06-15

    Technical nanofibre production is linked to high voltage, because nanofibres are typically produced by electrospinning. In contrast, spiders have evolved a way to produce nanofibres without high voltage. These spiders are called cribellate spiders and produce nanofibres within their capture thread production. It is suggested that their nanofibres become frictionally charged when brushed over a continuous area on the calamistrum, a comb-like structure at the metatarsus of the fourth leg. Although there are indications that electrostatic charges are involved in the formation of the thread structure, final proof is missing. We proposed three requirements to validate this hypothesis: (1) the removal of any charge during or after thread production has an influence on the structure of the thread; (2) the characteristic structure of the thread can be regenerated by charging; and (3) the thread is attracted to or repelled from differently charged objects. None of these three requirements were proven true. Furthermore, mathematical calculations reveal that even at low charges, the calculated structural assembly of the thread does not match the observed reality. Electrostatic forces are therefore not involved in the production of cribellate capture threads. © 2017. Published by The Company of Biologists Ltd.

  17. Modelling of Tethered Space-Web Structures

    Science.gov (United States)

    McKenzie, D. J.; Cartnell, M. P.

    Large structures in space are an essential milestone in the path of many projects, from solar power collectors to space stations. In space, as on Earth, these large projects may be split up into more manageable sections, dividing the task into multiple replicable parts. Specially constructed spider robots could assemble these structures piece by piece over a membrane or space- web, giving a method for building a structure while on orbit. The modelling and applications of these space-webs are discussed, along with the derivation of the equations of motion of the structure. The presentation of some preliminary results from the solution of these equations will show that space-webs can take a variety of different forms, and give some guidelines for configuring the space-web system.

  18. Structure–Activity Relationship Study of Spider Polyamine Toxins as Inhibitors of Ionotropic Glutamate Receptors

    DEFF Research Database (Denmark)

    Xiong, Xiaofeng; Poulsen, Mette H; Hussein, Rama A

    2014-01-01

    The spider polyamine toxins Joro spider toxin-3 (JSTX-3) and Nephila polyamine toxins-1 and -8 (NPTX-1 and NPTX-8) are isolated from the venom of the orb-weaver spider Nephila clavata (Joro spider). They share a high degree of structural resemblance, their aromatic head groups being the only...

  19. Fear of spiders: The effect of real threat on the interference caused by symbolic threat

    NARCIS (Netherlands)

    Kwakkenbos, C.M.C.; Becker, E.S.; Rinck, M.

    2010-01-01

    The effect of the presence of a real spider on attentional biases for symbolic spider stimuli was examined in 42 low-fearful and 26 high-spider-fearful participants. They completed a word colour-naming task as well as a picture orientation-judgement task, both with versus without a spider present in

  20. Three newly recorded Linyphiid spiders (Araneae: Linyphiidae from Korea

    Directory of Open Access Journals (Sweden)

    Sue Yeon Lee

    2018-03-01

    Full Text Available Three Linyphiid spiders, Caviphantes pseudosaxetorum Wunderlich, 1979, Erigone edentata Saito and Ono, 2001, and Savignia kawachiensis Oi, 1960, are reported for the first time from Korea with taxonomic illustrations and redescription. In this study, the genus Caviphantes Oi, 1960 is also newly recorded to Korean spider fauna.

  1. Spider diversity in relation to habitat heterogeneity and an altitudinal ...

    African Journals Online (AJOL)

    Using pitfall traps, wandering spiders (Arachnida: Araneae) were sampled in a nested design from three different localities in the mountainous arid ecosystem of South Sinai at low, middle, and high altitudes. Habitat type and altitude were clearly different among the three localities. Spider diversity per trap varied spatially ...

  2. Forest floor spiders of woodlots in an agricultural landscape

    NARCIS (Netherlands)

    Mabelis, A.

    1996-01-01

    An inventory of spiders was made in woodlots, which are situated in an agricultural landscape in the eastern part of the Netherlands. Aim of the study was to test the hypotheses that good dispersers, like spiders, will be distributed randomly over habitat patches and consequently, that there will be

  3. Alleviation of oxidative stress induced by spider mite invasion ...

    African Journals Online (AJOL)

    Spider mite invasion induces oxidative stress on bean plants and increased soluble sugars, phenole, proline and peroxidase activity, but decreased catalase activity and ascorbic acid and carotenoid concentration. Application of elicitors significantly enhanced spider mite tolerance by decreasing hydrogen peroxide, ...

  4. Who is afraid of a black Spider(-Man)?

    OpenAIRE

    Ora C. McWilliams

    2013-01-01

    An Internet post asking about Spider-Man's race in a film turned into an Internet campaign about an actor that led fans to interact with each other as well as with the actor, which in turn led to the attention of media producers, which resulted in a change in Spider-Man's race in a print comic book.

  5. Who is afraid of a black Spider(-Man?

    Directory of Open Access Journals (Sweden)

    Ora C. McWilliams

    2013-06-01

    Full Text Available An Internet post asking about Spider-Man's race in a film turned into an Internet campaign about an actor that led fans to interact with each other as well as with the actor, which in turn led to the attention of media producers, which resulted in a change in Spider-Man's race in a print comic book.

  6. Brain systems underlying encounter expectancy bias in spider phobia.

    Science.gov (United States)

    Aue, Tatjana; Hoeppli, Marie-Eve; Piguet, Camille; Hofstetter, Christoph; Rieger, Sebastian W; Vuilleumier, Patrik

    2015-06-01

    Spider-phobic individuals are characterized by exaggerated expectancies to be faced with spiders (so-called encounter expectancy bias). Whereas phobic responses have been linked to brain systems mediating fear, little is known about how the recruitment of these systems relates to exaggerated expectancies of threat. We used fMRI to examine spider-phobic and control participants while they imagined visiting different locations in a forest after having received background information about the likelihood of encountering different animals (spiders, snakes, and birds) at these locations. Critically, imagined encounter expectancies modulated brain responses differently in phobics as compared with controls. Phobics displayed stronger negative modulation of activity in the lateral prefrontal cortex, precuneus, and visual cortex by encounter expectancies for spiders, relative to snakes or birds (within-participants analysis); these effects were not seen in controls. Between-participants correlation analyses within the phobic group further corroborated the hypothesis that these phobia-specific modulations may underlie irrationality in encounter expectancies (deviations of encounter expectancies from objective background information) in spider phobia; the greater the negative modulation a phobic participant displayed in the lateral prefrontal cortex, precuneus, and visual cortex, the stronger was her bias in encounter expectancies for spiders. Interestingly, irrationality in expectancies reflected in frontal areas relied on right rather than left hemispheric deactivations. Our data accord with the idea that expectancy biases in spider phobia may reflect deficiencies in cognitive control and contextual integration that are mediated by right frontal and parietal areas.

  7. Time-dependent motor properties of multipedal molecular spiders.

    Science.gov (United States)

    Samii, Laleh; Blab, Gerhard A; Bromley, Elizabeth H C; Linke, Heiner; Curmi, Paul M G; Zuckermann, Martin J; Forde, Nancy R

    2011-09-01

    Molecular spiders are synthetic biomolecular walkers that use the asymmetry resulting from cleavage of their tracks to bias the direction of their stepping motion. Using Monte Carlo simulations that implement the Gillespie algorithm, we investigate the dependence of the biased motion of molecular spiders, along with binding time and processivity, on tunable experimental parameters, such as number of legs, span between the legs, and unbinding rate of a leg from a substrate site. We find that an increase in the number of legs increases the spiders' processivity and binding time but not their mean velocity. However, we can increase the mean velocity of spiders with simultaneous tuning of the span and the unbinding rate of a spider leg from a substrate site. To study the efficiency of molecular spiders, we introduce a time-dependent expression for the thermodynamic efficiency of a molecular motor, allowing us to account for the behavior of spider populations as a function of time. Based on this definition, we find that spiders exhibit transient motor function over time scales of many hours and have a maximum efficiency on the order of 1%, weak compared to other types of molecular motors.

  8. Nutrient regulation in a predator, the wolf spider Pardosa prativaga

    DEFF Research Database (Denmark)

    Jensen, Kim; Mayntz, David; Toft, Søren

    2011-01-01

    Nutrient balancing is well known in herbivores and omnivores, but has only recently been demonstrated in predators. To test how a predator might regulate nutrients when the prey varies in nutrient composition, we restricted juvenile Pardosa prativaga wolf spiders to diets of one of six fruit fly......, Drosophila melanogaster, prey types varying in lipid:protein composition during their second instar. We collected all fly remnants to estimate food and nutrient intake over each meal. The spiders adjusted their capture rate and nutrient extraction in response to prey mass and nutrient composition...... irrespective of energy intake. Intake was initially regulated to a constant lipid plus protein mass, but later spiders fed on prey with high proportions of protein increased consumption relative to spiders fed on other prey types. This pattern indicates that the spiders were prepared to overconsume vast...

  9. SPIDER: CMB Polarimetry from the Edge of Space

    Energy Technology Data Exchange (ETDEWEB)

    Gualtieri, R.; et al.

    2017-11-28

    SPIDER is a balloon-borne instrument designed to map the polarization of the millimeter-wave sky at large angular scales. SPIDER targets the B-mode signature of primordial gravitational waves in the cosmic microwave background (CMB), with a focus on mapping a large sky area with high fidelity at multiple frequencies. SPIDER's first longduration balloon (LDB) flight in January 2015 deployed a total of 2400 antenna-coupled Transition Edge Sensors (TESs) at 90 GHz and 150 GHz. In this work we review the design and in-flight performance of the SPIDER instrument, with a particular focus on the measured performance of the detectors and instrument in a space-like loading and radiation environment. SPIDER's second flight in December 2018 will incorporate payload upgrades and new receivers to map the sky at 285 GHz, providing valuable information for cleaning polarized dust emission from CMB maps.

  10. TOPICAL REVIEW: Spin current, spin accumulation and spin Hall effect

    Directory of Open Access Journals (Sweden)

    Saburo Takahashi and Sadamichi Maekawa

    2008-01-01

    Full Text Available Nonlocal spin transport in nanostructured devices with ferromagnetic injector (F1 and detector (F2 electrodes connected to a normal conductor (N is studied. We reveal how the spin transport depends on interface resistance, electrode resistance, spin polarization and spin diffusion length, and obtain the conditions for efficient spin injection, spin accumulation and spin current in the device. It is demonstrated that the spin Hall effect is caused by spin–orbit scattering in nonmagnetic conductors and gives rise to the conversion between spin and charge currents in a nonlocal device. A method of evaluating spin–orbit coupling in nonmagnetic metals is proposed.

  11. Spin electronics

    CERN Document Server

    Buhrman, Robert; Daughton, James; Molnár, Stephan; Roukes, Michael

    2004-01-01

    This report is a comparative review of spin electronics ("spintronics") research and development activities in the United States, Japan, and Western Europe conducted by a panel of leading U.S. experts in the field. It covers materials, fabrication and characterization of magnetic nanostructures, magnetism and spin control in magnetic nanostructures, magneto-optical properties of semiconductors, and magnetoelectronics and devices. The panel's conclusions are based on a literature review and a series of site visits to leading spin electronics research centers in Japan and Western Europe. The panel found that Japan is clearly the world leader in new material synthesis and characterization; it is also a leader in magneto-optical properties of semiconductor devices. Europe is strong in theory pertaining to spin electronics, including injection device structures such as tunneling devices, and band structure predictions of materials properties, and in development of magnetic semiconductors and semiconductor heterost...

  12. Spin glasses

    International Nuclear Information System (INIS)

    Fischer, K.H.; Hertz, J.A.

    1993-01-01

    Spin glasses, simply defined by the authors as a collection of spins (i.e., magnetic moments) whose low-temperature state is a frozen disordered one, represent one of the fascinating new fields of study in condensed matter physics, and this book is the first to offer a comprehensive account of the subject. Included are discussions of the most important developments in theory, experimental work, and computer modeling of spin glasses, all of which have taken place essentially within the last two decades. The first part of the book gives a general introduction to the basic concepts and a discussion of mean field theory, while the second half concentrates on experimental results, scaling theory, and computer simulation of the structure of spin glasses

  13. Molecular investigation on Iranian widow spider Latrodectus tredecimguttatus based on DNA barcode analysis

    Directory of Open Access Journals (Sweden)

    Maryam Mollaiizadeh

    2017-09-01

    Full Text Available Objective: To identify the caught samples of Latrodectus tredecimguttatus (L. tredecimguttatus to the species level and to compare the obtained sequences with those of them that have been submitted in GenBank in Bojnurd district, located in north-east part of Iran. Methods: Samples were collected from different places of Bojnurd district using direct search method and were transferred to insectary. After then, by using valid morphological keys, samples were identified to the species level. Moreover, the DNA related to some samples was extracted by the use of different methods such as Collins, phenol-chloroform, salting-out and G-Spin kit. Finally, COI gene was studied by PCR amplification. Results: Totally, two egg sacs were collected as well as two mature female spiders. According to the lab results, by the use of molecular methods, 50 spiderlings belonging to an egg sac was evaluated. The results of PCR assay revealed that the best way for DNA extraction was salting- out method. Finally, the sequence of the partial mtDNA-COI of Latrodectus tredecimguttatus (L. tredecimguttatus sample was submitted to GenBank. The results showed an identity of 99% of the studied samples with those of GenBank. Conclusions: Widow spiders are widely spread in different parts of the world and their bites cause death. It is important to study these samples by the use of molecular methods and then to produce them in a mass volume in order to fight and extract their venom for provision of anti-serum. To the best of our knowledge, this is the first molecular survey on spiders in Iran. Finally, the assessment of the human protection against the specific Iranian L. tredecimguttatus anti-venom is suggested.

  14. Brown spider dermonecrotic toxin directly induces nephrotoxicity

    International Nuclear Information System (INIS)

    Chaim, Olga Meiri; Sade, Youssef Bacila; Bertoni da Silveira, Rafael; Toma, Leny; Kalapothakis, Evanguedes; Chavez-Olortegui, Carlos; Mangili, Oldemir Carlos; Gremski, Waldemiro; Dietrich, Carl Peter von; Nader, Helena B.; Sanches Veiga, Silvio

    2006-01-01

    Brown spider (Loxosceles genus) venom can induce dermonecrotic lesions at the bite site and systemic manifestations including fever, vomiting, convulsions, disseminated intravascular coagulation, hemolytic anemia and acute renal failure. The venom is composed of a mixture of proteins with several molecules biochemically and biologically well characterized. The mechanism by which the venom induces renal damage is unknown. By using mice exposed to Loxosceles intermedia recombinant dermonecrotic toxin (LiRecDT), we showed direct induction of renal injuries. Microscopic analysis of renal biopsies from dermonecrotic toxin-treated mice showed histological alterations including glomerular edema and tubular necrosis. Hyalinization of tubules with deposition of proteinaceous material in the tubule lumen, tubule epithelial cell vacuoles, tubular edema and epithelial cell lysis was also observed. Leukocytic infiltration was neither observed in the glomerulus nor the tubules. Renal vessels showed no sign of inflammatory response. Additionally, biochemical analyses showed such toxin-induced changes in renal function as urine alkalinization, hematuria and azotemia with elevation of blood urea nitrogen levels. Immunofluorescence with dermonecrotic toxin antibodies and confocal microscopy analysis showed deposition and direct binding of this toxin to renal intrinsic structures. By immunoblotting with a hyperimmune dermonecrotic toxin antiserum on renal lysates from toxin-treated mice, we detected a positive signal at the region of 33-35 kDa, which strengthens the idea that renal failure is directly induced by dermonecrotic toxin. Immunofluorescence reaction with dermonecrotic toxin antibodies revealed deposition and binding of this toxin directly in MDCK epithelial cells in culture. Similarly, dermonecrotic toxin treatment caused morphological alterations of MDCK cells including cytoplasmic vacuoles, blebs, evoked impaired spreading and detached cells from each other and from

  15. Checklist of the spiders (Araneae) of Israel.

    Science.gov (United States)

    Zonstein, Sergei; Marusik, Yuri M

    2013-01-01

    This checklist records 631 spider species and subspecies belonging to 49 families in Israel. Species distributions are given in both generalised (by main geographic areas of the country) and detailed (by localities) form. Twenty-seven records are considered as doubtful and another ten are based on misidentifications. A historical survey is provided. Each record is presented in its original combination. The list is dominated by members of the families Gnaphosidae and Salticidae (20.0% and 17.1% of total species, respectively). The level of regional endemism exceeds 37.0%.

  16. Transgenic Silk Moths to Produce Spider Silk

    National Research Council Canada - National Science Library

    Herrera, Rene J

    2008-01-01

    .... Other alternatives like production of the protein that yields same or similar mechanical properties of dragline silk in microorganisms or mammalian cells, in spinning fibers from concentrated protein...

  17. Web-spinning caterpillar stalks snails.

    Science.gov (United States)

    Rubinoff, Daniel; Haines, William P

    2005-07-22

    Moths and butterflies compose one of the most diverse insect orders, but they are overwhelmingly herbivorous. Less than 0.2% are specialized predators, indicating that lepidopteran feeding habits are highly constrained. We report a Hawaiian caterpillar that specializes on snails, a unique food source requiring an unusual feeding strategy. The caterpillar uses silk to restrain live prey. All caterpillars have silk glands, but none are known to use silk in this spiderlike fashion. Considering the canalization of caterpillar diets, evolution to attack and feed on snails is an anomaly. Hawaii s isolation and consequently disharmonic biota likely promote evolutionary experiments that occur nowhere else.

  18. Spinning a stem cell ethics web.

    Science.gov (United States)

    McDonald, Michael; Longstaff, Holly

    2013-01-01

    The goal of this study was to provide an ethics education resource for trainees and researchers in the Canadian Stem Cell Network that would address the multiple ethical challenges in stem cell research including accountability in and for research across its multiple dimensions. The website was built using a bottom-up type approach based on an ethics needs assessment in combination with a top-down expert-driven component. There have been 3,615 visitors to the website since it was launched in July, 2011. The ongoing rate of returning visitors (20%) indicates that the website is becoming a valuable tool used multiple times.

  19. Web Caching

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 7; Issue 7. Web Caching - A Technique to Speedup Access to Web Contents. Harsha Srinath Shiva Shankar Ramanna. General Article Volume 7 Issue 7 July 2002 pp 54-62 ... Keywords. World wide web; data caching; internet traffic; web page access.

  20. Cuticular antifungals in spiders: density- and condition dependence.

    Directory of Open Access Journals (Sweden)

    Daniel González-Tokman

    Full Text Available Animals living in groups face a high risk of disease contagion. In many arthropod species, cuticular antimicrobials constitute the first protective barrier that prevents infections. Here we report that group-living spiders produce cuticular chemicals which inhibit fungal growth. Given that cuticular antifungals may be costly to produce, we explored whether they can be modulated according to the risk of contagion (i.e. under high densities. For this purpose, we quantified cuticular antifungal activity in the subsocial crab spider Diaea ergandros in both natural nests and experimentally manipulated nests of varying density. We quantified the body-condition of spiders to test whether antifungal activity is condition dependent, as well as the effect of spider density on body-condition. We predicted cuticular antifungal activity to increase and body-condition to decrease with high spider densities, and that antifungal activity would be inversely related to body-condition. Contrary to our predictions, antifungal activity was neither density- nor condition-dependent. However, body-condition decreased with density in natural nests, but increased in experimental nests. We suggest that pathogen pressure is so important in nature that it maintains high levels of cuticular antifungal activity in spiders, impacting negatively on individual energetic condition. Future studies should identify the chemical structure of the isolated antifungal compounds in order to understand the physiological basis of a trade-off between disease prevention and energetic condition caused by group living, and its consequences in the evolution of sociality in spiders.

  1. Mermithid parasitism of Hawaiian Tetragnatha spiders in a fragmented landscape

    Science.gov (United States)

    Vandergast, Amy; Roderick, George K.

    2003-01-01

    Hawaiian Tetragnatha spiders inhabiting small forest fragments on the Big Island of Hawaii are parasitized by mermithid nematodes. This is the first report of mermithid nematodes infecting spiders in Hawaii, and an initial attempt to characterize this host–parasite interaction. Because immature mermithids were not morphologically identifiable, a molecular identification was performed. A phylogenetic analysis based on 18S small ribosomal subunit nuclear gene sequences suggested that Hawaiian spider mermithids are more closely related to a mainland presumptive Aranimemis species that infects spiders, than to an insect-infecting mermithid collected on Oahu, HI, or to Mermis nigrescens, also a parasite of insects. Measured infection prevalence was low (ranging from 0 to 4%) but differed significantly among forest fragments. Infection prevalence was associated significantly with fragment area, but not with spider density nor spider species richness. Results suggest that mermithid populations are sensitive to habitat fragmentation, but that changes in infection prevalence do not appear to affect spider community structure.

  2. Web Mining

    Science.gov (United States)

    Fürnkranz, Johannes

    The World-Wide Web provides every internet citizen with access to an abundance of information, but it becomes increasingly difficult to identify the relevant pieces of information. Research in web mining tries to address this problem by applying techniques from data mining and machine learning to Web data and documents. This chapter provides a brief overview of web mining techniques and research areas, most notably hypertext classification, wrapper induction, recommender systems and web usage mining.

  3. A revised and dated phylogeny of cobweb spiders (Araneae, Araneoidea, Theridiidae): A predatory Cretaceous lineage diversifying in the era of the ants (Hymenoptera, Formicidae).

    Science.gov (United States)

    Liu, Jie; May-Collado, Laura J; Pekár, Stano; Agnarsson, Ingi

    2016-01-01

    Cobweb spiders (Theridiidae) are highly diverse from the perspective of species richness, morphological diversity, variety of web architecture, and behavioral repertoires. The family includes over 50% of social spiders, a behavioral rarity among the order, and members of the family are furthermore the subject of research on venom, silk biomechanics, kleptoparasitism and web building, among other traits. Theridiidae is one of the most abundant groups of spiders, and thus key insect predators in many different ecosystems and is among relatively few spider families that show high degree of myrmecophagy. Modern comparative studies on all these fronts are best buttressed on a phylogenetic foundation. Our goal here is to offer a revised, dated, phylogenetic hypothesis for the family by summarizing previously published data from multiple molecular and morphological studies through data-mining, and adding novel data from several genera. We also test the hypothesis that the origin and diversification of cobweb spiders coincides with that of ants on which many species specialize as prey. The new phylogeny is largely congruent with prior studies and current taxonomy and should provide a useful tool for theridiid classification and for comparative analyses. Nevertheless, we also highlight the limitations of currently available data-the state of the art in Theridiidae phylogenetics-offering weak support for most of the deeper nodes in the phylogeny. Thus the need is clear for modern phylogenomic approaches to obtain a more solid understanding, especially of relationships among subfamilies. We recover the monophyly of currently recognized theridiid subfamilies with the exception of some enigmatic 'pholcommatines' (Styposis, Phoroncidia) and putative 'hadrotarsines' (Audifia, Tekellina) whose placement is uncertain in our analyses. Theridiidae dates back some 100 mya to the Cretaceous, a period of diversification in flowering plants and many groups of insects, including ants. The

  4. Spider silk as a novel high performance biomimetic muscle driven by humidity.

    Science.gov (United States)

    Agnarsson, Ingi; Dhinojwala, Ali; Sahni, Vasav; Blackledge, Todd A

    2009-07-01

    The abrupt halt of a bumble bee's flight when it impacts the almost invisible threads of an orb web provides an elegant example of the amazing strength and toughness of spider silk. Spiders depend upon these properties for survival, yet the impressive performance of silk is not limited solely to tensile mechanics. Here, we show that silk also exhibits powerful cyclic contractions, allowing it to act as a high performance mimic of biological muscles. These contractions are actuated by changes in humidity alone and repeatedly generate work 50 times greater than the equivalent mass of human muscle. Although we demonstrate that this response is general and occurs weakly in diverse hydrophilic materials, the high modulus of spider silk is such that it generates exceptional force. Furthermore, because this effect already operates at the level of single silk fibers, only 5 microm in diameter, it can easily be scaled across the entire size range at which biological muscles operate. By contrast, the most successful synthetic muscles developed so far are driven by electric voltage, such that they cannot scale easily across large ranges in cross-sectional areas. The potential applicability of silk muscles is further enhanced by our finding that silkworm fibers also exhibit cyclic contraction because they are already available in commercial quantities. The simplicity of using wet or dry air to drive the biomimetic silk muscle fibers and the incredible power generated by silk offer unique possibilities in designing lightweight and compact actuators for robots and micro-machines, new sensors, and green energy production.

  5. Repeated evolution of male sacrifice behavior in spiders correlated with genital mutilation.

    Science.gov (United States)

    Miller, Jeremy A

    2007-06-01

    According to sexual cannibalism theory, male complicity in terminal mating can be adaptive when the male's future reproductive value is low relative to the benefits of self sacrifice. Spiders and insects that exhibit male sacrifice behavior (either complicity in cannibalism or spontaneous death associated with copulation) often also have male genitalia that stereotypically become broken or disfigured the first time they are used for copulation, potentially lowering his future reproductive value. Theoretical work on monogamy has identified male bias in the effective sex ratio as a precursor to the evolution of monogamy (including male sacrifice) as an adaptive form of paternity protection. Using phylogeny-based statistics and drawing on several phylogenetic studies of araneoid spiders, I investigate relationships between male sacrifice behavior, genital mutilation, extreme sexual size dimorphism, and the accumulation of multiple males in the female web (as an indicator of a male-based effective sex ratio). This investigation focuses on araneoid spiders because several independent origins of sacrifice behavior are known for this group and the phylogenetic structure of the lineage is relatively well studied. I report that male genital mutilation is significantly correlated with sacrifice behavior and argue that this finding is consistent with sexual cannibalism theory. Male sacrifice behavior is also correlated with male accumulation, a result that is consistent with theoretical work on the evolution of monogamy. Male accumulation and extreme sexual size dimorphism are correlated suggesting that sex-based differences in maturation time can lead to a male biased effective sex ratio. Similar patterns of correlated characters may hold for some insect taxa. Studying traits that have appeared independently in multiple lineages is a powerful method for developing general theories about the evolution of biological phenomena.

  6. Inhibition of the spider heartbeat by gravity and vibration

    Science.gov (United States)

    Finck, A.

    1984-01-01

    The rate and vigor of the spider heartbeat is controlled by an external pacemaker. A mechanical feature of the spider cardio-vascular system is the production of high serum pressure in the prosoma and the legs. This appears to be the source for leg extension. The lyriform organ on the patella of the leg is sensitive to vibratory and kinesthetic stimuli. This sensitivity depends upon the degree of leg extension. Thus the activity of the heart and the response characteristics of the sense receptor are related. The effect of a supra-threshold vibratory or gravitational stimulus is to produce an inhibition and a tachycardia of the spider heartbeat.

  7. Biotechnological Trends in Spider and Scorpion Antivenom Development

    DEFF Research Database (Denmark)

    Laustsen, Andreas Hougaard; Solà, Mireia; Jappe, Emma Christine

    2016-01-01

    Spiders and scorpions are notorious for their fearful dispositions and their ability to inject venom into prey and predators, causing symptoms such as necrosis, paralysis, and excruciating pain. Information on venom composition and the toxins present in these species is growing due to an interest...... at an increasingly faster pace. In this review, the current knowledge of spider and scorpion venoms is presented, followed by a discussion of all published biotechnological efforts within development of spider and scorpion antitoxins based on small molecules, antibodies and fragments thereof, and next generation...

  8. Myocarditis after black widow spider envenomation.

    Science.gov (United States)

    Sari, Ibrahim; Zengin, Suat; Davutoglu, Vedat; Yildirim, Cuma; Gunay, Nurullah

    2008-06-01

    The black widow spider (BWS), which is a member of the arthropod family, is widely distributed on earth. Black widow spider bites can cause a wide variety of signs or symptoms in humans, but the cardiovascular manifestations are relatively rare except hypertension/hypotension and bradycardia/tachycardia. We report on a 65-year-old man who experienced myocarditis after BWS envenomation, which is extremely rare. He complained of chest pain after the BWS bite, and electrocardiography (ECG) was consistent with a 0.5-mm ST-segment elevation in leads II, aVF, and V3 through V6 and accompanying augmentation in T-wave amplitude in leads V3 through V6 without reciprocal changes. Creatine kinase-MB, troponin-I, and aspartate aminotransferase levels peaked at 98 IU/L, 6.1 ng/mL, and 62 U/L, respectively. His ECG readings and cardiac enzymes returned to normal with supportive treatment, and he was discharged with complete recovery. To the best of our knowledge, the present case is the third in the literature reporting myocarditis and the first reporting ST-segment elevation and accompanying augmentation in T-wave amplitude after BWS envenomation. In addition to usual measures, we recommend ECG and cardiac-specific enzyme followup for every patient envenomated by BWS for potentially fatal cardiac involvement.

  9. Intracellular recording from a spider vibration receptor.

    Science.gov (United States)

    Gingl, Ewald; Burger, Anna-M; Barth, Friedrich G

    2006-05-01

    The present study introduces a new preparation of a spider vibration receptor that allows intracellular recording of responses to natural mechanical or electrical stimulation of the associated mechanoreceptor cells. The spider vibration receptor is a lyriform slit sense organ made up of 21 cuticular slits located on the distal end of the metatarsus of each walking leg. The organ is stimulated when the tarsus receives substrate vibrations, which it transmits to the organ's cuticular structures, reducing the displacement to about one tenth due to geometrical reasons. Current clamp recording was used to record action potentials generated by electrical or mechanical stimuli. Square pulse stimulation identified two groups of sensory cells, the first being single-spike cells which generated only one or two action potentials and the second being multi-spike cells which produced bursts of action potentials. When the more natural mechanical sinusoidal stimulation was applied, differences in adaptation rate between the two cell types remained. In agreement with prior extracellular recordings, both cell types showed a decrease in the threshold tarsus deflection with increasing stimulus frequency. Off-responses to mechanical stimuli have also been seen in the metatarsal organ for the first time.

  10. Microcirculation abnormalities provoked by Loxosceles spiders' envenomation.

    Science.gov (United States)

    Cristina de Oliveira-Lima, Kátia; Farsky, Sandra Helena P; Lopes, Priscila Hess; de Andrade, Rute Maria Gonçalves; van den Berg, Carmen W; Tambourgi, Denise V

    2016-06-15

    Loxoscelism is caused by envenomation by spiders from Loxosceles genus. Clinical symptoms only appear a few hours after envenomation and can evolve in local reactions, such as dermonecrosis, and systemic reactions, including intravascular haemolysis, intravascular coagulation and renal failure. Considering that alterations in the microcirculatory network are involved in the pathogenesis of different diseases, including the inflammatory process, the aim of this study was to investigate the action of venoms of males and females of Loxosceles intermedia and Loxosceles laeta on the microcirculatory network and examine the systemic production of inflammatory mediators in a murine model of loxoscelism. We observed that during systemic envenomation, the alterations in the microcirculation include increase in the number of rolling cells, which was more intense in animals injected with female Loxosceles spider venoms. This positively correlated with increase in TNF-α and NO serum levels, induction of which was higher by female venoms when compared with male venoms. The increase of leukocytes rolling was not accompanied by increase of cell adhesion. The absence of leukocyte extravasation may explain why in mice, in contrast to humans, no cutaneous loxoscelism occurs. Thus, targeting the neutrophil adhesion and extravasation in Loxosceles envenomed patients may prevent cutaneous pathology. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. Do parasitoids explain differential abundance of two syntopic orb-weaver spiders (Araneae: Araneidae)?

    Science.gov (United States)

    Gonzaga, Marcelo O.; Cardoso, João C. F.; Vasconcellos-Neto, João

    2015-11-01

    In this study, we examined the relative abundance of two congeneric species of orb-weaver spiders, Cyclosa fililineata and Cyclosa morretes, in an area of Atlantic forest in southeastern Brazil, and the relationship of this variable with fecundity and attacks by parasitoids. We also investigated responses to vibrational stimuli that simulated the approach of a wasp and described architectural changes in webs of parasitized individuals of C. fililineata. C.fililineata was more abundant throughout the year, although this species produced a lower number of egg sacs and a lower number of eggs per egg sac when compared with C. morretes. Both species showed similar types of behavioral responses to vibrational stimuli, but C. fililineata remained motionless more often. The frequency of parasitism by the wasp Polysphincta janzeni on adults and juveniles was low and similar for C. fililineata and C. morretes in both dry and wet seasons. The parasitoid caused alterations in the web design of C. fililineata similar of those observed in other orb-weavers attacked by ichneumonid wasps. Webs constructed by spiders parasitized by larvae in their last instar had a lower number of radii and sticky spirals were completely absent. An egg parasitoid, Baeus cyclosae, attacked C. morretes more often than C. fililineata, possibly as a consequence of its greater clutch size and/or larger eggs. These results indicate that egg mortality caused by B. cyclosae, but not subadult and adult mortality promoted by P. janzeni, may be an important factor determining the relative abundance of these two Cyclosa species.

  12. Symmetric webs, Jones-Wenzl recursions and q-Howe duality

    DEFF Research Database (Denmark)

    Rose, David; Tubbenhauer, Daniel

    We define and study the category of symmetric sl2-webs. This category is a combinatorial description of the category of all finite dimensional quantum sl2-modules. Explicitly, we show that (the additive closure of) the symmetric sl2-spider is (braided monoidally) equivalent to the latter. Our main...

  13. Species replacement by a nonnative salmonid alters ecosystem function by reducing prey subsidies that support riparian spiders

    Science.gov (United States)

    Benjamin, J.R.; Fausch, K.D.; Baxter, C.V.

    2011-01-01

    Replacement of a native species by a nonnative can have strong effects on ecosystem function, such as altering nutrient cycling or disturbance frequency. Replacements may cause shifts in ecosystem function because nonnatives establish at different biomass, or because they differ from native species in traits like foraging behavior. However, no studies have compared effects of wholesale replacement of a native by a nonnative species on subsidies that support consumers in adjacent habitats, nor quantified the magnitude of these effects. We examined whether streams invaded by nonnative brook trout (Salvelinus fontinalis) in two regions of the Rocky Mountains, USA, produced fewer emerging adult aquatic insects compared to paired streams with native cutthroat trout (Oncorhynchus clarkii), and whether riparian spiders that depend on these prey were less abundant along streams with lower total insect emergence. As predicted, emergence density was 36% lower from streams with the nonnative fish. Biomass of brook trout was higher than the cutthroat trout they replaced, but even after accounting for this difference, emergence was 24% lower from brook trout streams. More riparian spiders were counted along streams with greater total emergence across the water surface. Based on these results, we predicted that brook trout replacement would result in 6-20% fewer spiders in the two regions. When brook trout replace cutthroat trout, they reduce cross-habitat resource subsidies and alter ecosystem function in stream-riparian food webs, not only owing to increased biomass but also because traits apparently differ from native cutthroat trout. ?? 2011 Springer-Verlag.

  14. At the Mercy of Gaia: Deep Ecologial Unrest and America's fall as Nature's Nation in Kingdom of the Spiders

    Directory of Open Access Journals (Sweden)

    Jacob Lillemose

    2015-10-01

    Full Text Available This paper looks as the animal horror genre as a way to discuss current notions of ecology in relation to a specific American idea of being "Nature's Nation". The central work for the discussion is the movie Kingdom of the Spiders (1977 by John Cardos, which depicts how a small Arizona town is taken over by a "swarm" of tarantulas. Without any obvious explanation the spiders slowly but steadily invade the town and start killing both other animals and humans until they have completely covered the town in their web. The paper connects the movie to a long tradition of fiction describing how nature turns on humans and reverses the power relation be-tween man and nature that is fundamental to modernity. Moreover, the paper connects the movie to Maurice Maeterlincks ideas of swarm communities as mani-fested by ants and termites to argue that these communities are ecologically superior to the the communities of man-made civilisation. Finally, the paper discusses Kingdom of the Spiders and animal horror in general in relation to recent ideas of non-human ecologies and critiques of anthropocentrism and makes the point that these works of fiction serve as both dramatic and philosophical visions of a world without humans.

  15. Interference Spins

    DEFF Research Database (Denmark)

    Popovski, Petar; Simeone, Osvaldo; Nielsen, Jimmy Jessen

    2015-01-01

    on traffic load and interference condition leads to performance gains. In this letter, a general network of multiple interfering two-way links is studied under the assumption of a balanced load in the two directions for each link. Using the notion of interference spin, we introduce an algebraic framework...

  16. Spinning worlds

    NARCIS (Netherlands)

    Schwarz, H.

    2017-01-01

    The thesis "Spinning Worlds" is about the characterisation of two types of gas-giant exoplanets: Hot Jupiters, with orbital periods of fewer than five days, and young, wide-orbit gas giants, with orbital periods as long as thousands of years. The thesis is based on near-infrared observations of 1

  17. A check list of the spider fauna of the Western Soutpansberg, South Africa (Arachnida: Araneae

    Directory of Open Access Journals (Sweden)

    S.H. Foord

    2002-12-01

    Full Text Available By virtue of its geological history and geographical location the Soutpansberg constitutes a refuge for a high diversity of organisms. The Western Soutpansberg forms part of the Savanna Biome and is presently the area with the highest concentration of Natural Heritage Sites in South Africa. A unique private initiative is under way to improve its national and international conservation status in a bid to conserve the mountain. A checklist of the spider species of the Western Soutpansberg collected over a five-year period is presented. Forty-six families, represented by 109 genera and 127 species have been collected. Of the species collected, 81 (64 % were wandering spiders and 46 (36 % web builders. The Thomisidae have the highest number of species (15 followed by the Araneidae and the Salticidae with 10 species each. Ninety-six genera are represented by a single species. Ninety six percent of the species collected are new records for the area. This survey is the first for the area and forms part of the South African National Survey of Arachnida (SANSA.

  18. Biomimetic calcium phosphate coatings on recombinant spider silk fibres

    NARCIS (Netherlands)

    Yang, Liang; Hedhammar, My; Blom, Tobias; Leifer, Klaus; Johansson, Jan; Habibovic, Pamela; van Blitterswijk, Clemens

    2010-01-01

    Calcium phosphate ceramic coatings, applied on surfaces of metallic and polymeric biomaterials, can improve their performance in bone repair and regeneration. Spider silk is biocompatible, strong and elastic, and hence an attractive biomaterial for applications in connective tissue repair. Recently,

  19. Peculiar torsion dynamical response of spider dragline silk

    Science.gov (United States)

    Liu, Dabiao; Yu, Longteng; He, Yuming; Peng, Kai; Liu, Jie; Guan, Juan; Dunstan, D. J.

    2017-07-01

    The torsional properties of spider dragline silks from Nephila edulis and Nephila pilipes spiders are investigated by using a torsion pendulum technique. A permanent torsional deformation is observed after even small torsional strain. This behaviour is quite different from that of the other materials tested here, i.e., carbon fiber, thin metallic wires, Kevlar fiber, and human hair. The spider dragline thus displays a strong energy dissipation upon the initial excitation (around 75% for small strains and more for a larger strain), which correspondingly reduces the amplitude of subsequent oscillations around the new equilibrium position. The variation of torsional stiffness in relaxation dynamics of spider draglines for different excitations is also determined. The experimental result is interpreted in the light of the hierarchical structure of dragline silk.

  20. [Effectiveness of a repellent paint against the spider Loxosceles laeta].

    Science.gov (United States)

    Catalán, Alejandro; Araya, Jorge E; Varela, Héctor; Cortés, William; Sagua, Hernán; González Cortés, Jorge

    2009-02-01

    Loxoscelism is a severe reaction to the bite of the spider Loxosceles laeta. In recent years, a paint with repellent properties has been promoted in the commerce. However, there are no reports of experiments evaluating its effectiveness. To evaluate experimentally the repellent properties of a paint against Loxosceles laeta. Males, females and nymphs of L laeta were deposited in cockpits that allow the free displacement of the spider. Half of the cockpit was covered with repellent paint. Daily observations during one week, determined how frequently the spiders occupied the space covered with repellent paint. The experiments were run in triplicate. No statistical differences in the occupancy of spaces covered with repellent paint or not covered with it were observed for nymphs (87% and 67%, respectively), males (72% and 77%, respectively) or females (91% and 84%, respectively). The tested paint does not have a repellent action against the spider Loxosceles laeta.

  1. A reconsideration of the classification of the spider infraorder Mygalomorphae (Arachnida: Araneae based on three nuclear genes and morphology.

    Directory of Open Access Journals (Sweden)

    Jason E Bond

    Full Text Available BACKGROUND: The infraorder Mygalomorphae (i.e., trapdoor spiders, tarantulas, funnel web spiders, etc. is one of three main lineages of spiders. Comprising 15 families, 325 genera, and over 2,600 species, the group is a diverse assemblage that has retained a number of features considered primitive for spiders. Despite an evolutionary history dating back to the lower Triassic, the group has received comparatively little attention with respect to its phylogeny and higher classification. The few phylogenies published all share the common thread that a stable classification scheme for the group remains unresolved. METHODS AND FINDINGS: We report here a reevaluation of mygalomorph phylogeny using the rRNA genes 18S and 28S, the nuclear protein-coding gene EF-1γ, and a morphological character matrix. Taxon sampling includes members of all 15 families representing 58 genera. The following results are supported in our phylogenetic analyses of the data: (1 the Atypoidea (i.e., antrodiaetids, atypids, and mecicobothriids is a monophyletic group sister to all other mygalomorphs; and (2 the families Mecicobothriidae, Hexathelidae, Cyrtaucheniidae, Nemesiidae, Ctenizidae, and Dipluridae are not monophyletic. The Microstigmatidae is likely to be subsumed into Nemesiidae. Nearly half of all mygalomorph families require reevaluation of generic composition and placement. The polyphyletic family Cyrtaucheniidae is most problematic, representing no fewer than four unrelated lineages. CONCLUSIONS: Based on these analyses we propose the following nomenclatural changes: (1 the establishment of the family Euctenizidae (NEW RANK; (2 establishment of the subfamily Apomastinae within the Euctenizidae; and (3 the transfer of the cyrtaucheniid genus Kiama to Nemesiidae. Additional changes include relimitation of Domiothelina and Theraphosoidea, and the establishment of the Euctenizoidina clade (Idiopidae + Euctenizidae. In addition to these changes, we propose a "road map

  2. SPIDERS (ARANEI) OF VOLGOGRAD SITY AND ITS ENVIRONS

    OpenAIRE

    A. V. Ponomarev; A. S. Khnykin

    2013-01-01

    Abstract. Aim. Fauna of spiders of Volgograd Region is researched uncompletely. Only 149 species of 19 families were listed in previous references. Complete listing of spiders of this large region was the aim of our investigation.Location. Volgograd Region, Russia.Methods. Material was collected in Volgograd City with environs and Volga-Don area in 2009–2013. Areas with minimum of anthropogenic influence within the city, artificial ecosystem of park type, plots of native vegetation along the ...

  3. Benefits of cooperation with genetic kin in a subsocial spider

    DEFF Research Database (Denmark)

    Schneider, J.M.; Bilde, T.

    2008-01-01

    used a cross-fostering design to control for genetic relatedness and group membership. Our study animal was the periodic social spider Stegodyphus lineatus, a transitional species that belongs to a genus containing both permanent social and periodic social species. In S. lineatus, the young cooperate....... Hence, in communally feeding spiders, nepotism favors group retention and reduces the conflict between selfish interests and the interests of the group....

  4. Spiders of the Vine Plants in Southern Moravia

    OpenAIRE

    Lucie Havlová; Vladimír Hula; Jana Niedobová

    2015-01-01

    Araneofauna of vineyards is relatively known in Central Europe but we have a lack of knowledge about araneofauna which occur directly on the vine plants. Our investigation was focused on spiders which live on vine plants, especially on the vine plants trunks. We investigated spiders in six vineyards in southern Moravia (Šatov, Mikulov, Popice, Morkůvky, Nosislav and Blučina). Vineyards were under different soil management, traps were placed on different parts of particular locality (terraced ...

  5. Rapid Characterization of Spider Silk Genes via Exon Capture

    Science.gov (United States)

    2015-03-28

    argentata (silver garden spider ), Latrodectus hesperus (Western black widow ), and Nephila clavipes (golden silk orb- weaver). A. diadematus and N...in light of sequence divergence, we also studied Parasteatoda tepidariorum (common house spider ) and Steatoda grossa (false black widow ). P...could determine the minimum number of spidroin gene copies in a black widow genome. In less well-characterized species, such as A. diadematus, our data

  6. Latrodectism—Effects of the Black Widow Spider Bite

    OpenAIRE

    Timms, Patrick K.; Gibbons, Robert B.

    1986-01-01

    Latrodectism—envenomation by the black widow spider, Latrodectus mactans—has been reported in virtually every state. The spider is particularly prevalent in the Southwest, Southeast and California, and symptoms from its bite are painful and may be confusing to clinicians. Prompt improvement can be expected in most cases with administration of calcium and muscle relaxant, but some patients may require treatment with antivenin. No deaths occurred in our series of 11 patients, although one case ...

  7. Spider silk as a blueprint for greener materials : a review

    OpenAIRE

    Lefèvre, Thierry; Auger, Michèle

    2016-01-01

    Spider silk exhibits remarkable properties, especially its well-known tensile performances. They rely on a complex nanostructured hierarchical organisation that studies progressively elucidate. Spider silk encompasses a vast range of fibres that exhibit diverse and captivating physical and biological characteristics. The full understanding of the relation between structure and properties may lead in the future to the design of a variety of high-performance, tailored materials and ...

  8. Small Molecules from Spiders Used as Chemical Probes

    DEFF Research Database (Denmark)

    Olsen, Christian Adam; Kristensen, Anders S.; Strømgaard, Kristian

    2011-01-01

    Spiders are important species in ecological systems and as major predators of insects they are endowed with a plethora of low‐molecular‐weight natural products having intriguing biological activities. The isolation and biological characterization of these entities are well established, however, o...... the area of pheromones and allomones from spiders. Herein, we recapitulate these recent results, put them into perspective with previous findings, and provide an outlook for future studies of these chemotypes....

  9. Visual Discrimination Learning in the Jumping Spider Phidippus regius

    Directory of Open Access Journals (Sweden)

    Massimo De Agrò

    2017-11-01

    Full Text Available Over the past decade, research in comparative psychology has increasingly focused on non-vertebrate models of cognition. Jumping spiders provide excellent models for the study of visually mediated behaviors, such as associative learning or the navigation of complex environments. Here, we tested visual and memory abilities of Phidippus regius to discriminate between artificial geometrical stimuli and to generalize the learned discrimination to illusory stimuli, using the amodal completion mechanism. Spiders were first trained to associate one shape (‘X’ or ‘O’ with a reward (sugar water, whilst the other shape was associated with an aversive taste (acidic water. Spiders were then asked to choose between the two shapes in the absence of any reward or punishment. They were then presented with an occluded version of the previously rewarded shape to test for the presence of amodal completion. Spiders were able to learn the discrimination task, although the association was not transferred to the illusory stimulus. This study provides the first demonstration of shape discrimination learning in a jumping spider. The results of the test on the illusory shape are discussed considering that either the spiders' visual system may not require amodal completion or they could have the tendency to learn the shape associated with the aversive taste rather than that associated with the reward.

  10. The phylogeny of fossil whip spiders.

    Science.gov (United States)

    Garwood, Russell J; Dunlop, Jason A; Knecht, Brian J; Hegna, Thomas A

    2017-04-21

    Arachnids are a highly successful group of land-dwelling arthropods. They are major contributors to modern terrestrial ecosystems, and have a deep evolutionary history. Whip spiders (Arachnida, Amblypygi), are one of the smaller arachnid orders with ca. 190 living species. Here we restudy one of the oldest fossil representatives of the group, Graeophonus anglicus Pocock, 1911 from the Late Carboniferous (Duckmantian, ca. 315 Ma) British Middle Coal Measures of the West Midlands, UK. Using X-ray microtomography, our principal aim was to resolve details of the limbs and mouthparts which would allow us to test whether this fossil belongs in the extant, relict family Paracharontidae; represented today by a single, blind species Paracharon caecus Hansen, 1921. Tomography reveals several novel and significant character states for G. anglicus; most notably in the chelicerae, pedipalps and walking legs. These allowed it to be scored into a phylogenetic analysis together with the recently described Paracharonopsis cambayensis Engel & Grimaldi, 2014 from the Eocene (ca. 52 Ma) Cambay amber, and Kronocharon prendinii Engel & Grimaldi, 2014 from Cretaceous (ca. 99 Ma) Burmese amber. We recovered relationships of the form ((Graeophonus (Paracharonopsis + Paracharon)) + (Charinus (Stygophrynus (Kronocharon (Charon (Musicodamon + Paraphrynus)))))). This tree largely reflects Peter Weygoldt's 1996 classification with its basic split into Paleoamblypygi and Euamblypygi lineages; we were able to score several of his characters for the first time in fossils. Our analysis draws into question the monophyly of the family Charontidae. Our data suggest that Graeophonus is a crown group amblypygid, and falls within a monophyletic Paleoamblypgi clade, but outside the family Paracharontidae (= Paracharonopsis + Paracharon). Our results also suggest a new placement for the Burmese amber genus Kronocharon, a node further down from its original position. Overall, we offer a

  11. Competing dwarf males: sexual selection in an orb-weaving spider.

    Science.gov (United States)

    Foellmer, M W; Fairbairn, D J

    2005-05-01

    Hypotheses for the adaptive significance of extreme female-biased sexual size dimorphism (SSD) generally assume that in dimorphic species males rarely interfere with each other. Here we provide the first multivariate examination of sexual selection because of male-male competition over access to females in a species with 'dwarf' males, the orb-weaving spider Argiope aurantia. Male A. aurantia typically try to mate opportunistically during the female's final moult when she is defenceless. We show that, contrary to previous hypotheses, the local operational sex ratio (males per female on the web) is male-biased most of the season. Both interference and scramble competition occur during opportunistic mating, the former leading to significant selection for large male body size. Male condition and leg length had no effect on mating success independent of size. We discuss these findings in the context of the evolution of extreme female-biased SSD in this clade.

  12. In a spin at Brookhaven spin physics

    CERN Document Server

    Makdisi, Y I

    2003-01-01

    The mysterious quantity that is spin took centre stage at Brookhaven for the SPIN2002 meeting last September. The 15th biennial International Spin Physics Symposium (SPIN2002) was held at Brookhaven National Laboratory on 9-14 September 2002. Some 250 spin enthusiasts attended, including experimenters and theorists in both nuclear and high-energy physics, as well as accelerator physicists and polarized target and polarized source experts. The six-day symposium included 23 plenary talks and 150 parallel talks. SPIN2002 was preceded by a one-day spin physics tutorial for students, postdocs, and anyone else who felt the need for a refresher course. (2 refs).

  13. Web evolution and Web Science

    OpenAIRE

    Hall, Wendy; Tiropanis, Thanassis

    2012-01-01

    This paper examines the evolution of the World Wide Web as a network of networks and discusses the emergence of Web Science as an interdisciplinary area that can provide us with insights on how the Web developed, and how it has affected and is affected by society. Through its different stages of evolution, the Web has gradually changed from a technological network of documents to a network where documents, data, people and organisations are interlinked in various and often unexpected ways. It...

  14. Spin-Circuit Representation of Spin Pumping

    Science.gov (United States)

    Roy, Kuntal

    2017-07-01

    Circuit theory has been tremendously successful in translating physical equations into circuit elements in an organized form for further analysis and proposing creative designs for applications. With the advent of new materials and phenomena in the field of spintronics and nanomagnetics, it is imperative to construct the spin-circuit representations for different materials and phenomena. Spin pumping is a phenomenon by which a pure spin current can be injected into the adjacent layers. If the adjacent layer is a material with a high spin-orbit coupling, a considerable amount of charge voltage can be generated via the inverse spin Hall effect allowing spin detection. Here we develop the spin-circuit representation of spin pumping. We then combine it with the spin-circuit representation for the materials having spin Hall effect to show that it reproduces the standard results as in the literature. We further show how complex multilayers can be analyzed by simply writing a netlist.

  15. Web archives

    DEFF Research Database (Denmark)

    Finnemann, Niels Ole

    2018-01-01

    This article deals with general web archives and the principles for selection of materials to be preserved. It opens with a brief overview of reasons why general web archives are needed. Section two and three present major, long termed web archive initiatives and discuss the purposes and possible...... values of web archives and asks how to meet unknown future needs, demands and concerns. Section four analyses three main principles in contemporary web archiving strategies, topic centric, domain centric and time-centric archiving strategies and section five discuss how to combine these to provide...... a broad and rich archive. Section six is concerned with inherent limitations and why web archives are always flawed. The last sections deal with the question how web archives may fit into the rapidly expanding, but fragmented landscape of digital repositories taking care of various parts...

  16. Spin Coherence in Semiconductor Nanostructures

    National Research Council Canada - National Science Library

    Flatte, Michael E

    2006-01-01

    ... dots, tuning of spin coherence times for electron spin, tuning of dipolar magnetic fields for nuclear spin, spontaneous spin polarization generation and new designs for spin-based teleportation and spin transistors...

  17. Molecular cloning and expression of the C-terminus of spider ...

    Indian Academy of Sciences (India)

    PRAKASH KUMAR

    . Among the types of spider silks, draglines from Nephila clavipes and Araneus diadematus have been the most intensely studied. However, the entirety of a spider silk gene has not been cloned yet, and sequence data from. Molecular cloning ...

  18. Riparian spiders as sentinels of PCB contamination across heterogeneous aquatic ecosystems

    Science.gov (United States)

    Riparian spiders are being used increasingly to track spatial patterns of contaminants in and fluxing from aquatic ecosystems. However, our understanding of the circumstances under which spiders are effective sentinels of aquatic pollution is limited. The present study tests the ...

  19. MR imaging of carotid webs

    International Nuclear Information System (INIS)

    Boesen, Mari E.; Eswaradass, Prasanna Venkatesan; Singh, Dilip; Mitha, Alim P.; Menon, Bijoy K.; Goyal, Mayank; Frayne, Richard

    2017-01-01

    We propose a magnetic resonance (MR) imaging protocol for the characterization of carotid web morphology, composition, and vessel wall dynamics. The purpose of this case series was to determine the feasibility of imaging carotid webs with MR imaging. Five patients diagnosed with carotid web on CT angiography were recruited to undergo a 30-min MR imaging session. MR angiography (MRA) images of the carotid artery bifurcation were acquired. Multi-contrast fast spin echo (FSE) images were acquired axially about the level of the carotid web. Two types of cardiac phase resolved sequences (cineFSE and cine phase contrast) were acquired to visualize the elasticity of the vessel wall affected by the web. Carotid webs were identified on MRA in 5/5 (100%) patients. Multi-contrast FSE revealed vessel wall thickening and cineFSE demonstrated regional changes in distensibility surrounding the webs in these patients. Our MR imaging protocol enables an in-depth evaluation of patients with carotid webs: morphology (by MRA), composition (by multi-contrast FSE), and wall dynamics (by cineFSE). (orig.)

  20. MR imaging of carotid webs

    Energy Technology Data Exchange (ETDEWEB)

    Boesen, Mari E. [University of Calgary, Department of Biomedical Engineering, Calgary (Canada); Foothills Medical Centre, Seaman Family MR Research Centre, Calgary (Canada); Eswaradass, Prasanna Venkatesan; Singh, Dilip; Mitha, Alim P.; Menon, Bijoy K. [University of Calgary, Department of Clinical Neurosciences, Calgary (Canada); Foothills Medical Centre, Calgary Stroke Program, Calgary (Canada); Goyal, Mayank [Foothills Medical Centre, Calgary Stroke Program, Calgary (Canada); University of Calgary, Department of Radiology, Calgary (Canada); Frayne, Richard [Foothills Medical Centre, Seaman Family MR Research Centre, Calgary (Canada); University of Calgary, Hotchkiss Brain Institute, Calgary (Canada)

    2017-04-15

    We propose a magnetic resonance (MR) imaging protocol for the characterization of carotid web morphology, composition, and vessel wall dynamics. The purpose of this case series was to determine the feasibility of imaging carotid webs with MR imaging. Five patients diagnosed with carotid web on CT angiography were recruited to undergo a 30-min MR imaging session. MR angiography (MRA) images of the carotid artery bifurcation were acquired. Multi-contrast fast spin echo (FSE) images were acquired axially about the level of the carotid web. Two types of cardiac phase resolved sequences (cineFSE and cine phase contrast) were acquired to visualize the elasticity of the vessel wall affected by the web. Carotid webs were identified on MRA in 5/5 (100%) patients. Multi-contrast FSE revealed vessel wall thickening and cineFSE demonstrated regional changes in distensibility surrounding the webs in these patients. Our MR imaging protocol enables an in-depth evaluation of patients with carotid webs: morphology (by MRA), composition (by multi-contrast FSE), and wall dynamics (by cineFSE). (orig.)

  1. First report of clinical presentation of a bite by a running spider ...

    African Journals Online (AJOL)

    This article describes the clinical progression of symptoms over a period of 5 days of a bite inflicted by a Philodromus sp. spider. Commonly known as 'running spiders', these are not considered to be harmful to humans. This report, however, is the first description of an actual bite by a member of this group of spiders ...

  2. Revision, phylogeny, and microhabitat shifts in the Southeast Asian spider genus Aetana (Araneae, Pholcidae

    Directory of Open Access Journals (Sweden)

    Bernhard A. Huber

    2015-12-01

    Full Text Available The previously poorly known Southeast Asian spider genus Aetana Huber, 2005 is revised. Fifteen species are newly described, and the first SEM data and a first phylogenetic analysis of the genus are presented. Four species groups are well supported, one restricted to Borneo, two restricted to the Philippines, and one ranging from the Philippines to Fiji. The cladistic analysis and field observations suggest that the ancestor of Aetana built its web close to the ground, in confined spaces among and under rocks and logs. In at least two cases, evolutionary shifts of microhabitat resulted in species being adapted to life in higher forest strata, with correlated morphological and behavioral changes (lighter coloration; longer abdomen; additional sheet in web or more strongly domed web. The following species are newly described: A. abadae Huber, sp. nov., A. baganihan Huber, sp. nov., A. banahaw Huber, sp. nov., A. kiukoki Huber, sp. nov., A. libjo Huber, sp. nov., A. loboc Huber, sp. nov., A. lozadae Huber, sp. nov., A. manansalai Huber, sp. nov., A. ocampoi Huber, sp. nov., A. paragua Huber, sp. nov. and A. pasambai Huber, sp. nov. from the Philippines; A. gaya Huber, sp. nov., A. indah Huber, sp. nov., A. lambir Huber, sp. nov. and A. poring Huber, sp. nov. from northern Borneo. The female of A. kinabalu Huber, 2005 is newly described. A potential case of female genital dimorphism is documented in A. ocampoi Huber, sp. nov.

  3. SPIDERGL: A GRAPHICS LIBRARY FOR 3D WEB APPLICATIONS

    Directory of Open Access Journals (Sweden)

    M. Di Benedetto

    2012-09-01

    Full Text Available The recent introduction of the WebGL API for leveraging the power of 3D graphics accelerators within Web browsers opens the possibility to develop advanced graphics applications without the need for an ad-hoc plug-in. There are several contexts in which this new technology can be exploited to enhance user experience and data fruition, like e-commerce applications, games and, in particular, Cultural Heritage. In fact, it is now possible to use the Web platform to present a virtual reconstruction hypothesis of ancient pasts, to show detailed 3D models of artefacts of interests to a wide public, and to create virtual museums. We introduce SpiderGL, a JavaScript library for developing 3D graphics Web applications. SpiderGL provides data structures and algorithms to ease the use of WebGL, to define and manipulate shapes, to import 3D models in various formats, and to handle asynchronous data loading. We show the potential of this novel library with a number of demo applications and give details about its future uses in the context of Cultural Heritage applications.

  4. Web 25

    DEFF Research Database (Denmark)

    Web 25: Histories from the First 25 Years of the World Wide Web celebrates the 25th anniversary of the Web. Since the beginning of the 1990s, the Web has played an important role in the development of the Internet as well as in the development of most societies at large, from its early grey...... and blue webpages introducing the hyperlink for a wider public, to today’s multifacted uses of the Web as an integrated part of our daily lives. This is the rst book to look back at 25 years of Web evolution, and it tells some of the histories about how the Web was born and has developed. It takes...... the reader on an exciting time travel journey to learn more about the prehistory of the hyperlink, the birth of the Web, the spread of the early Web, and the Web’s introduction to the general public in mainstream media. Fur- thermore, case studies of blogs, literature, and traditional media going online...

  5. Web Engineering

    Energy Technology Data Exchange (ETDEWEB)

    White, Bebo

    2003-06-23

    Web Engineering is the application of systematic, disciplined and quantifiable approaches to development, operation, and maintenance of Web-based applications. It is both a pro-active approach and a growing collection of theoretical and empirical research in Web application development. This paper gives an overview of Web Engineering by addressing the questions: (a) why is it needed? (b) what is its domain of operation? (c) how does it help and what should it do to improve Web application development? and (d) how should it be incorporated in education and training? The paper discusses the significant differences that exist between Web applications and conventional software, the taxonomy of Web applications, the progress made so far and the research issues and experience of creating a specialization at the master's level. The paper reaches a conclusion that Web Engineering at this stage is a moving target since Web technologies are constantly evolving, making new types of applications possible, which in turn may require innovations in how they are built, deployed and maintained.

  6. Radiation Safety System for SPIDER Neutral Beam Accelerator

    Science.gov (United States)

    Sandri, S.; Coniglio, A.; D'Arienzo, M.; Poggi, C.

    2011-12-01

    SPIDER (Source for Production of Ion of Deuterium Extracted from RF Plasma only) and MITICA (Megavolt ITER Injector Concept Advanced) are the ITER neutral beam injector (NBI) testing facilities of the PRIMA (Padova Research Injector Megavolt Accelerated) Center. Both injectors accelerate negative deuterium ions with a maximum energy of 1 MeV for MITICA and 100 keV for SPIDER with a maximum beam current of 40 A for both experiments. The SPIDER facility is classified in Italy as a particle accelerator. At present, the design of the radiation safety system for the facility has been completed and the relevant reports have been presented to the Italian regulatory authorities. Before SPIDER can operate, approval must be obtained from the Italian Regulatory Authority Board (IRAB) following a detailed licensing process. In the present work, the main project information and criteria for the SPIDER injector source are reported together with the analysis of hypothetical accidental situations and safety issues considerations. Neutron and photon nuclear analysis is presented, along with special shielding solutions designed to meet Italian regulatory dose limits. The contribution of activated corrosion products (ACP) to external exposure of workers has also been assessed. Nuclear analysis indicates that the photon contribution to worker external exposure is negligible, and the neutron dose can be considered by far the main radiation protection issue. Our results confirm that the injector has no important radiological impact on the population living around the facility.

  7. SPIDER: Probing the Early Universe with a Suborbital Polarimeter

    Science.gov (United States)

    Fraisse, Aurélien A.; SPIDER Collaboration

    2012-01-01

    SPIDER is a balloon-borne polarimeter designed to detect a divergence-free polarization pattern ("B-modes") in the Cosmic Microwave Background (CMB). In the inflationary scenario, the spectrum of the tensor perturbations that generate this signal is proportional to that of the primordial scalar perturbations through the tensor-to-scalar ratio r. The expected level of systematic error in the SPIDER instrument is significantly below the amplitude of an interesting cosmological B-mode signal with r=0.03. An optimized scanning strategy enables us to minimize uncertainty in the reconstruction of the Stokes parameters used to characterize the CMB, while providing access to a relatively wide range of angular scales. In the SPIDER field, the polarized emission from interstellar dust is as bright or brighter than the cosmological r=0.03 B-mode signal at all SPIDER frequencies (90, 150, and 280 GHz), a situation similar to that found in the "Southern Hole." Despite this foreground contamination, two 20-day flights of the SPIDER instrument will constrain the amplitude of the B-mode signal to rAPRA-NNX07AL64G), the National Science Foundation (ANT-1043515), the Gordon and Betty Moore Foundation, and the David and Lucile Packard Foundation. Support in Canada is provided by NSERC, the Canadian Space Agency, the Canada Foundation for Innovation, and CIFAR.

  8. Recent Advances in Research on Widow Spider Venoms and Toxins

    Directory of Open Access Journals (Sweden)

    Shuai Yan

    2015-11-01

    Full Text Available Widow spiders have received much attention due to the frequently reported human and animal injures caused by them. Elucidation of the molecular composition and action mechanism of the venoms and toxins has vast implications in the treatment of latrodectism and in the neurobiology and pharmaceutical research. In recent years, the studies of the widow spider venoms and the venom toxins, particularly the α-latrotoxin, have achieved many new advances; however, the mechanism of action of the venom toxins has not been completely clear. The widow spider is different from many other venomous animals in that it has toxic components not only in the venom glands but also in other parts of the adult spider body, newborn spiderlings, and even the eggs. More recently, the molecular basis for the toxicity outside the venom glands has been systematically investigated, with four proteinaceous toxic components being purified and preliminarily characterized, which has expanded our understanding of the widow spider toxins. This review presents a glance at the recent advances in the study on the venoms and toxins from the Latrodectus species.

  9. Endemic harvestmen and spiders of Austria (Arachnida: Opiliones, Araneae

    Directory of Open Access Journals (Sweden)

    Komposch, Christian

    2011-01-01

    Full Text Available A comprehensive overview of plant, fungus and animal species of Austria revealed a total of 748 endemic and subendemic species, including, 11 harvestman and 46 spider species. Altogether two endemic harvestmen (Nemastoma bidentatum relictum, Nemastoma schuelleri and 8 endemic spiders (Abacoproeces molestus, Collinsia (caliginosa nemenziana, Mughiphantes severus, Mughiphantes styriacus, Pelecopsis alpica, Scotophaeus nanus, Troglohyphantes novicordis, Troglohyphantes tauriscus, beside 9 subendemic harvestman and 38 subendemic spider species have been recorded from Austria. Hot-spots of endemism in the Eastern Alps are the north-eastern (Ennstaler Alps and southern Calcareous Alps (Karawanken, Karnische Alps and the Central Alps (Hohe Tauern, Gurktaler Alps, Ötztaler and Stubaier Alps. Most of the endemic arachnid species occur from the nival down to the montane zone. Important habitats are rocky areas, caves and woodlands. High absolute numbers and percentages of endemics can be found within the harvestman families Cladonychiidae, Ischyropsalididae and Nemastomatidae and in the spider genera Lepthyphantes s. l. and Troglohyphantes. The conservation status of these highly endangered taxa – 85 % of the spider species and 100 % of the harvestman taxa are endangered in Austria – is poor.

  10. Treatment effect on biases in size estimation in spider phobia.

    Science.gov (United States)

    Shiban, Youssef; Fruth, Martina B; Pauli, Paul; Kinateder, Max; Reichenberger, Jonas; Mühlberger, Andreas

    2016-12-01

    The current study investigates biases in size estimations made by spider-phobic and healthy participants before and after treatment. Forty-one spider-phobic and 20 healthy participants received virtual reality (VR) exposure treatment and were then asked to rate the size of a real spider immediately before and, on average, 15days after the treatment. During the VR exposure treatment skin conductance response was assessed. Prior to the treatment, both groups tended to overestimate the size of the spider, but this size estimation bias was significantly larger in the phobic group than in the control group. The VR exposure treatment reduced this bias, which was reflected in a significantly smaller size rating post treatment. However, the size estimation bias was unrelated to the skin conductance response. Our results confirm the hypothesis that size estimation by spider-phobic patients is biased. This bias is not stable over time and can be decreased with adequate treatment. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Heat and spin interconversion

    International Nuclear Information System (INIS)

    Ohnuma, Yuichi; Matsuo, Mamoru; Maekawa, Sadamichi; Saitoh, Eeiji

    2017-01-01

    Spin Seebeck and spin Peltier effects, which are mutual conversion phenomena of heat and spin, are discussed on the basis of the microscopic theory. First, the spin Seebeck effect, which is the spin-current generation due to heat current, is discussed. The recent progress in research on the spin Seebeck effect are introduced. We explain the origin of the observed sign changes of the spin Seebeck effect in compensated ferromagnets. Next, the spin Peltier effect, which is the heat-current generation due to spin current, is discussed. Finally, we show that the spin Seebeck and spin Peltier effects are summarized by Onsager's reciprocal relation and derive Kelvin's relation for the spin and heat transports. (author)

  12. Interactions Between the Chilean Recluse Spider (Araneae: Sicariidae) and an Araneophagic Spitting Spider (Araneae: Scytodidae).

    Science.gov (United States)

    Canals, Mauricio; Arriagada, Nicolás; Solís, Rigoberto

    2015-03-01

    In Chile, all necrotic arachnidism is attributed to the Chilean recluse spider, Loxosceles laeta Nicolet, a species that shares the microenvironmental habitats with the spitting spider Scytodes globula Nicolet. The latter species has been proposed as a potential predator of L. laeta. For this research, we studied the interaction between both species during individual encounters to assess the possibility of population regulation of L. laeta cohorts exposed to this potential predator. We found that in most encounters S. globula prevailed. Also, S. globula preys on spiderlings of L. laeta, with a population effect on cohorts of this species. These findings suggest that S. globula may be influencing L. laeta populations in central Chile. The population regulation of L. laeta by predation would be important because this species, in the absence of predators, has a high reproductive rate, and it can maintain populations of large size. However according to our results, although S. globula may aid in the reduction of both spiderling and adult L. laeta populations, and perhaps other Loxosceles species, it is insufficient for biological control of Loxosceles species. Its presence together with other control measures such as hygiene of the rooms can help to decrease loxoscelism incidence. © The Author 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  13. Influence of spider silk on refugia preferences of the recluse spiders Loxosceles reclusa and Loxosceles laeta (Araneae: Sicariidae).

    Science.gov (United States)

    Vetter, Richard S; Rust, Michael K

    2010-06-01

    In a previous experimental study, recluse spiders Loxosceles reclusa Gertsch and Mulaik and Loxosceles laeta (Nicolet) (Araneae: Sicariidae) preferred small cardboard refugia covered with conspecific silk compared with never-occupied refugia. Herein, we investigated some factors that might be responsible for this preference using similar cardboard refugia. When the two Loxosceles species were given choices between refugia previously occupied by their own and by the congeneric species, neither showed a species-specific preference; however, each chose refugia coated with conspecific silk rather than those previously inhabited by a distantly related cribellate spider, Metaltella simoni (Keyserling). When L. laeta spiders were offered refugia that were freshly removed from silk donors compared with heated, aged refugia from the same silk donor, older refugia were preferred. Solvent extracts of L. laeta silk were chosen approximately as often as control refugia when a range of solvents (methylene chloride:methanol, water, and hexane) were used. However, when acetone was used on similar silk, there was a statistical preference for the control, indicating that there might be a mildly repellent aspect to acetone-washed silk. Considering the inability to show attraction to chemical aspects of fresh silk, it seems that physical attributes may be more important for selection and that there might be repellency to silk of a recently vacated spider. These findings are discussed in regard to pest management strategies to control recluse spiders.

  14. Multivariable control of a rolling spider drone

    Science.gov (United States)

    Lyu, Haifeng

    The research and application of Unmanned Aerial Vehicles (UAVs) has been a hot topic recently. A UAV is dened as an aircraft which is designed not to carry a human pilot or operated with remote electronic input by the flight controller. In this thesis, the design of a control system for a quadcopter named Rolling Spider Drone is conducted. The thesis work presents the design of two kinds of controllers that can control the Drone to keep it balanced and track different kinds of input trajectories. The nonlinear mathematical model for the Drone is derived by the Newton-Euler method. The rotational subsystem and translational system are derived to describe the attitude and position motion of Drone. Techniques from linear control theory are employed to linearize the highly coupled and nonlinear quadcopter plant around equilibrium points and apply the linear feedback controller to stabilize the system. The controller is a digital tracking system that deploys LQR for system stability design. Fixed gain and adaptive gain scheduled controllers are developed and compared with different LQR weights. Step references and reference trajectories involving signicant variation for the yaw angle in the xy-plane and three-dimensional spaces are tracked in the simulation. The physical implementation and an output feedback controller are considered for future work.

  15. Efficient Journaling for the Spider Storage System

    Energy Technology Data Exchange (ETDEWEB)

    Oral, H Sarp [ORNL; Wang, Feiyi [ORNL; Shipman, Galen M [ORNL; Dillow, David A [ORNL; Miller, Ross G [ORNL; Drokin, Oleg [ORNL

    2003-01-01

    Journaling is a widely used technique to increase file system robustness against meta data and/or data corruptions. While the overhead of journaling can be negligible for small-scale file systems, we found that two aspects of local back-end file system journaling significantly lower the overall performance of a large-scale parallel file system such as Lustre: extra head seeks and serialization of incoming client requests. Journal transactions reside on a separate area of the disk that the file data, and each commit of the journal requires a head seek. Incoming client requests become serialized and take a latency hit by waiting for a commit to occur before the reply is sent. In this paper we present two different approaches to increase the local back-end file system journaling efficiency, thus increasing the overall aggregate parallel file system efficiency. First, we present a hardware-based solution where a solid-state device is used as an external journaling device to minimize the disk head seek. Second, we introduce a software-based optimization to allow asynchronously commit multiple journal transactions on the local back-end file system to minimize the penalty of serialization. Both our solutions are experimentally tested on Oak Ridge National Laboratory's large-scale Spider storage system and our tests show that both methods nearly double the overall parallel write performance.

  16. Web Caching

    Indian Academy of Sciences (India)

    operating systems, computer networks, distributed systems,. E-commerce and security. The World Wide Web has been growing in leaps and bounds. Studies have indicated that this massive distributed system can benefit greatly by making use of appropriate caching methods. Intelligent Web caching can lessen the burden ...

  17. Final design of thermal diagnostic system in SPIDER ion source

    Energy Technology Data Exchange (ETDEWEB)

    Brombin, M., E-mail: matteo.brombin@igi.cnr.it; Dalla Palma, M.; Pasqualotto, R.; Pomaro, N. [Consorzio RFX, Corso Stati Uniti 4, I-35127 Padova (Italy)

    2016-11-15

    The prototype radio frequency source of the ITER heating neutral beams will be first tested in SPIDER test facility to optimize H{sup −} production, cesium dynamics, and overall plasma characteristics. Several diagnostics will allow to fully characterise the beam in terms of uniformity and divergence and the source, besides supporting a safe and controlled operation. In particular, thermal measurements will be used for beam monitoring and system protection. SPIDER will be instrumented with mineral insulated cable thermocouples, both on the grids, on other components of the beam source, and on the rear side of the beam dump water cooled elements. This paper deals with the final design and the technical specification of the thermal sensor diagnostic for SPIDER. In particular the layout of the diagnostic, together with the sensors distribution in the different components, the cables routing and the conditioning and acquisition cubicles are described.

  18. Tool use in wild spider monkeys (Ateles geoffroyi).

    Science.gov (United States)

    Lindshield, Stacy M; Rodrigues, Michelle A

    2009-07-01

    Tool use has been observed in a variety of primate species, including both New and Old World monkeys. However, such reports mainly address the most prodigious tool users and frequently limit discussions of tool-using behavior to a foraging framework. Here, we present observations of novel and spontaneous tool use in wild black-handed spider monkeys (Ateles geoffroyi), where female spider monkeys used detached sticks in a self-directed manner. We introduce factors to explain Ateles tool-using abilities and limitations, and encourage the synthesis of relevant research in order to gain insight into the cognitive abilities of spider monkeys and the evolution of tool-using behaviors in primates.

  19. Vision in the nocturnal wandering spider Leucorchestris arenicola (Araneae: Sparassidae)

    DEFF Research Database (Denmark)

    Nørgaard, Thomas; Nilsson, Dan-Eric; Henschel, Joh R

    2008-01-01

    At night the Namib Desert spider Leucorchestris arenicola performs long-distance homing across its sand dune habitat. By disabling all or pairs of the spiders' eight eyes we found that homing ability was severely reduced when vision was fully abolished. Vision, therefore, seems to play a key role...... in the nocturnal navigational performances of L. arenicola. After excluding two or three pairs of eyes, the spiders were found to be able to navigate successfully using only their lateral eyes or only their anterior median eyes. Measurement of the eyes' visual fields showed that the secondary eyes combined have...... a near full (panoramic) view of the surroundings. The visual fields of the principal eyes overlap almost completely with those of the anterior lateral eyes. Electroretinogram recordings indicate that each eye type contains a single photopigment with sensitivity peaking at approximately 525 nm...

  20. [The black widow spider--its appearance and control].

    Science.gov (United States)

    Landeka, Nediljko; Plenković, Jasminka

    2003-03-01

    Between 1995 and 2002, a massive appearance of black widow (Latrodectus mactans tredecimguttatus, Rossi 1790) was recorded along the Croatia coast. This paper gives a historical review of latrodectism and observations from Istria and Dalmatia, paying particular attention to the spider's habitat. There are several reasons for the black widow to appear in a new habitat such as the introduction of leguminous plants, watermelons and melons where crops were grown earlier. Black widow can also be found near buildings and gardens. Human contacts with the spider are usually without consequences for humans, thanks to education and a relatively good visibility of the spider. The authors describe their experience in fighting black widow and emphasise the importance of education in preventing lactrodectism.

  1. Nuclear spin pumping and electron spin susceptibilities

    NARCIS (Netherlands)

    Danon, J.; Nazarov, Y.V.

    2011-01-01

    In this work we present a new formalism to evaluate the nuclear spin dynamics driven by hyperfine interaction with nonequilibrium electron spins. To describe the dynamics up to second order in the hyperfine coupling it suffices to evaluate the susceptibility and fluctuations of the electron spin.

  2. Latrodectism—Effects of the Black Widow Spider Bite

    Science.gov (United States)

    Timms, Patrick K.; Gibbons, Robert B.

    1986-01-01

    Latrodectism—envenomation by the black widow spider, Latrodectus mactans—has been reported in virtually every state. The spider is particularly prevalent in the Southwest, Southeast and California, and symptoms from its bite are painful and may be confusing to clinicians. Prompt improvement can be expected in most cases with administration of calcium and muscle relaxant, but some patients may require treatment with antivenin. No deaths occurred in our series of 11 patients, although one case was complicated by serum sickness. PMID:3962294

  3. Learning from animal sensors: the clever "design" of spider mechanoreceptors

    Science.gov (United States)

    Barth, Friedrich G.

    2012-04-01

    Three types of spider sensors responding to different forms of mechanical energy are chosen to illustrate the power of evolutionary constraints to fine-tune the functional "design" of animal sensors to the particular roles they play in particular behavioral contexts. As demonstrated by the application of computational biomechanics and a fruitful cooperation between biologists and engineers there are remarkable "technical" tricks to be found by which spider tactile sensors, airflow sensors, and strain sensors are adjusted to their biologically relevant stimulus patterns. The application of such "tricks" to technical solutions of measuring problems similar to those animals have to cope with, seems both realistic and very promising.

  4. Volatile compounds from leaves of the African spider plant (Gynandropsis gynandra) with bioactivity against spider mite (Tetranychus urticae)

    DEFF Research Database (Denmark)

    Nyalala, Samuel Odeyo; Petersen, Mikael Agerlin; Grout, Brian William Wilson

    2013-01-01

    Previous studies have demonstrated that Gynandropsis gynandra emits acetonitrile as a foliar volatile from intact plants and isolated leaves, and that this compound is an effective spider mite repellent. This study has used gas chromatography–mass spectrometry to investigate volatile compounds...... emitted from homogenised G. gynandra leaves to evaluate their tissue acetonitrile content and to look for other compounds that might be exploited for the management of spider mites. Acetonitrile was absent from the homogenised tissues of five lines of G. gynandra, studied over two seasons. Thirteen...... volatile compounds were emitted by G. gynandra at significantly higher levels than mite-susceptible pot roses, including isothiocyanates, aldehydes, esters, alcohols and terpenes. Six representative compounds were selected to assess bioactivity. Spider mite populations were completely inactive after a 2¿h...

  5. Magnetic Nanostructures Spin Dynamics and Spin Transport

    CERN Document Server

    Farle, Michael

    2013-01-01

    Nanomagnetism and spintronics is a rapidly expanding and increasingly important field of research with many applications already on the market and many more to be expected in the near future. This field started in the mid-1980s with the discovery of the GMR effect, recently awarded with the Nobel prize to Albert Fert and Peter Grünberg. The present volume covers the most important and most timely aspects of magnetic heterostructures, including spin torque effects, spin injection, spin transport, spin fluctuations, proximity effects, and electrical control of spin valves. The chapters are written by internationally recognized experts in their respective fields and provide an overview of the latest status.

  6. Mechanism of diffusive transport in molecular spider models

    Science.gov (United States)

    Semenov, Oleg; Olah, Mark J.; Stefanovic, Darko

    2011-02-01

    Recent advances in single-molecule chemistry have led to designs for artificial multipedal walkers that follow tracks of chemicals. We investigate the motion of a class of walkers, called molecular spiders, which consist of a rigid chemically inert body and several flexible enzymatic legs. The legs can reversibly bind to chemical substrates on a surface and through their enzymatic action convert them to products. The legs can also reversibly bind to products, but at a different rate. Antal and Krapivsky have proposed a model for molecular spider motion over regular one-dimensional lattices [T. Antal and P. L. Krapivsky, Phys. Rev. ENATUAS1539-375510.1103/PhysRevE.76.021121 76, 021121 (2007).]. In the model the legs hop from site to site under constraints imposed by connection to a common body. The first time a leg visits a site, the site is an uncleaved substrate, and the leg hops from this site only once it has cleaved it into a product. This cleavage happens at a rate rr=1. The effect of cleavage is to slow down the hopping rate for legs that visit a site for the first time. Along with the constraints imposed on the legs, this leads to an effective bias in the direction of unvisited sites that decreases the average time needed to visit n sites. The overall motion, however, remains diffusive in the long time limit. We have reformulated the Antal-Krapivsky model as a continuous-time Markov process and simulated many traces of this process using kinetic Monte Carlo techniques. Our simulations show a previously unpredicted transient behavior wherein spiders with small r values move superdiffusively over significant distances and times. We explain this transient period of superdiffusive behavior by describing the spider process as switching between two metastates: a diffusive state D wherein the spider moves in an unbiased manner over previously visited sites, and a boundary state B wherein the spider is on the boundary between regions of visited and unvisited sites

  7. Sensor web

    Science.gov (United States)

    Delin, Kevin A. (Inventor); Jackson, Shannon P. (Inventor)

    2011-01-01

    A Sensor Web formed of a number of different sensor pods. Each of the sensor pods include a clock which is synchronized with a master clock so that all of the sensor pods in the Web have a synchronized clock. The synchronization is carried out by first using a coarse synchronization which takes less power, and subsequently carrying out a fine synchronization to make a fine sync of all the pods on the Web. After the synchronization, the pods ping their neighbors to determine which pods are listening and responded, and then only listen during time slots corresponding to those pods which respond.

  8. Insecticidal toxins from black widow spider venom.

    Science.gov (United States)

    Rohou, A; Nield, J; Ushkaryov, Y A

    2007-03-15

    The biological effects of Latrodectus spider venom are similar in animals from different phyla, but these symptoms are caused by distinct phylum-specific neurotoxins (collectively called latrotoxins) with molecular masses ranging from 110 to 140 kDa. To date, the venom has been found to contain five insecticidal toxins, termed alpha, beta, gamma, delta and epsilon-latroinsectotoxins (LITs). There is also a vertebrate-specific neurotoxin, alpha-latrotoxin (alpha-LTX), and one toxin affecting crustaceans, alpha-latrocrustatoxin (alpha-LCT). These toxins stimulate massive release of neurotransmitters from nerve terminals and act (1) by binding to specific receptors, some of which mediate an exocytotic signal, and (2) by inserting themselves into the membrane and forming ion-permeable pores. Specific receptors for LITs have yet to be identified, but all three classes of vertebrate receptors known to bind alpha-LTX are also present in insects. All LTXs whose structures have been elucidated (alpha-LIT, delta-LIT, alpha-LTX and alpha-LCT) are highly homologous and have a similar domain architecture, which consists of a unique N-terminal sequence and a large domain composed of 13-22 ankyrin repeats. Three-dimensional (3D) structure analysis, so far done for alpha-LTX only, has revealed its dimeric nature and an ability to form symmetrical tetramers, a feature probably common to all LTXs. Only tetramers have been observed to insert into membranes and form pores. A preliminary 3D reconstruction of a delta-LIT monomer demonstrates the spatial similarity of this toxin to the monomer of alpha-LTX.

  9. Repeated Evolution of Power-Amplified Predatory Strikes in Trap-Jaw Spiders.

    Science.gov (United States)

    Wood, Hannah M; Parkinson, Dilworth Y; Griswold, Charles E; Gillespie, Rosemary G; Elias, Damian O

    2016-04-25

    Small animals possess intriguing morphological and behavioral traits that allow them to capture prey, including innovative structural mechanisms that produce ballistic movements by amplifying power [1-6]. Power amplification occurs when an organism produces a relatively high power output by releasing slowly stored energy almost instantaneously, resulting in movements that surpass the maximal power output of muscles [7]. For example, trap-jaw, power-amplified mechanisms have been described for several ant genera [5, 8], which have evolved some of the fastest known movements in the animal kingdom [6]. However, power-amplified predatory strikes were not previously known in one of the largest animal classes, the arachnids. Mecysmaucheniidae spiders, which occur only in New Zealand and southern South America, are tiny, cryptic, ground-dwelling spiders that rely on hunting rather than web-building to capture prey [9]. Analysis of high-speed video revealed that power-amplified mechanisms occur in some mecysmaucheniid species, with the fastest species being two orders of magnitude faster than the slowest species. Molecular phylogenetic analysis revealed that power-amplified cheliceral strikes have evolved four times independently within the family. Furthermore, we identified morphological innovations that directly relate to cheliceral function: a highly modified carapace in which the cheliceral muscles are oriented horizontally; modification of a cheliceral sclerite to have muscle attachments; and, in the power-amplified species, a thicker clypeus and clypeal apodemes. These structural innovations may have set the stage for the parallel evolution of ballistic predatory strikes. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Web Analytics

    Science.gov (United States)

    EPA’s Web Analytics Program collects, analyzes, and provides reports on traffic, quality assurance, and customer satisfaction metrics for EPA’s website. The program uses a variety of analytics tools, including Google Analytics and CrazyEgg.

  11. The changing use of the ovipositor in host shifts by ichneumonid ectoparasitoids of spiders (Hymenoptera, Ichneumonidae, Pimplinae

    Directory of Open Access Journals (Sweden)

    Takasuka Keizo

    2018-01-01

    Full Text Available Accurate egg placement into or onto a living host is an essential ability for many parasitoids, and changes in associated phenotypes, such as ovipositor morphology and behaviour, correlate with significant host shifts. Here, we report that in the ichneumonid group of koinobiont spider-ectoparasitoids (“polysphinctines”, several putatively ancestral taxa (clade I here, parasitic on ground-dwelling RTA-spiders (a group characterised by retrolateral tibial apophysis on male palpal tibiae, lay their eggs in a specific way. They tightly bend their metasoma above the spider’s cephalothorax, touching the carapace with the dorsal side of the ovipositor apically (“dorsal-press”. The egg slips out from the middle part of the ventral side of the ovipositor and moves towards its apex with the parted lower valves acting as rails. Deposition occurs as the parasitoid draws the ovipositor backwards from under the egg. Oviposition upon the tough carapace of the cephalothorax, presumably less palatable than the abdomen, is conserved in these taxa, and presumed adaptive through avoiding physical damage to the developing parasitoid. This specific way of oviposition is reversed in the putatively derived clade of polysphinctines (clade II here parasitic on Araneoidea spiders with aerial webs, which is already known. They bend their metasoma along the spider’s abdomen, grasping the abdomen with their fore/mid legs, pressing the ventral tip of the metasoma and the lower valves of the ovipositor against the abdomen (“ventral-press”. The egg is expelled through an expansion of the lower valves, which is developed only in this clade and evident in most species, onto the softer and presumably more nutritious abdomen.

  12. Decoherence dynamics of a single spin versus spin ensemble

    NARCIS (Netherlands)

    Dobrovitski, V.V.; Feiguin, A.E.; Awschalom, D.D.; Hanson, R.

    2008-01-01

    We study decoherence of central spins by a spin bath, focusing on the difference between measurement of a single central spin and measurement of a large number of central spins (as found in typical spin-resonance experiments). For a dilute spin bath, the single spin demonstrates Gaussian

  13. variability in condensed tannins and bitterness in spider plant ...

    African Journals Online (AJOL)

    ACSS

    Spider plant (Cleome gynandra L.) contributes considerably to the nutrition and medicines of communities in southern Africa. However, its utilisation is limited by its bitterness caused by condensed tannins. Unfortunately, processing options that reduce the bitterness also remove nutritionally and medicinally useful ...

  14. Spider bite in southern Africa: diagnosis and management

    African Journals Online (AJOL)

    older specimens the red stripes and spots may have disappeared completely. The legs are evenly black. .... Africa. (Map: Ansie Dippenaar.) Fig. 6. Brown widow spider depicting consistent orange to red hourglass .... Both cholinesterase inhibitors and α-latrotoxin give rise to an increase in acetylcholine concentration in the ...

  15. Biotechnological Trends in Spider and Scorpion Antivenom Development

    DEFF Research Database (Denmark)

    Laustsen, Andreas Hougaard; Solà, Mireia; Jappe, Emma Christine

    2016-01-01

    Spiders and scorpions are notorious for their fearful dispositions and their ability to inject venom into prey and predators, causing symptoms such as necrosis, paralysis, and excruciating pain. Information on venom composition and the toxins present in these species is growing due to an interest...

  16. Preservice Teachers' Conceptions about Animals and Particularly about Spiders

    Science.gov (United States)

    Jambrina, Carmen Urones; Vacas, Jose Manuel; Sanchez-Barbudo, Miguel

    2010-01-01

    Introduction: This article explores the scientific ideas and alternative conceptions that pre-service teachers have regarding animal classification and spiders in particular. Method: The study involved 40 pre-service teachers of elementary education in Spain and the data was collected by means of questionnaires, descriptions and drawings. The…

  17. Ant-Mimicking Spiders: Strategies for Living with Social Insects

    Directory of Open Access Journals (Sweden)

    Fadia Sara Ceccarelli

    2013-01-01

    Full Text Available Mimicry is a fascinating topic, in particular when viewed in terms of selective forces and evolutionary strategies. Mimicry is a system involving a signaller, a signal receiver, and a model and has evolved independently many times in plants and animals. There are several ways of classifying mimicry based on the interactions and cost-benefit scenarios of the parties involved. In this review, I briefly outline the dynamics of the most common types of mimicry to then apply it to some of the spider-ant associative systems known to date. In addition, this review expands on the strategies that ant-associating (in particular ant-mimicking spiders have developed to minimise the costs of living close to colonies of potentially dangerous models. The main strategy that has been noted to date is either chemical mimicry or actively avoiding contact with ants. If these strategies warrant protection for the spider (living close to potentially dangerous models, then the benefits of ant associations would outweigh the costs, and the association will prevail.

  18. Trial by fire: Social spider colony demographics in periodically ...

    African Journals Online (AJOL)

    Nests of social spiders of the genus Stegodyphus (Eresidae) are a prominent feature of African savannas and their size and visibility make them potentially good indicators of ecological consequences of fire. The colonies are sedentary and their nests may persist for several years, although individuals have an annual life ...

  19. Central European habitats inhabited by spiders with disjunctive distributions

    Czech Academy of Sciences Publication Activity Database

    Růžička, Vlastimil

    2011-01-01

    Roč. 59, č. 2 (2011), s. 367-380 ISSN 1505-2249 Institutional research plan: CEZ:AV0Z50070508 Keywords : spider s * glacial relicts * boreomontane species Subject RIV: EH - Ecology , Behaviour Impact factor: 0.506, year: 2011

  20. Ballooning behavior in the golden orbweb spider Nephilapilipes (Araneae: Nephilidae

    Directory of Open Access Journals (Sweden)

    Vanessa M.J. Lee

    2015-01-01

    Full Text Available Ballooning, a mode of aerial dispersal in spiders, is an innate behavior that requires appropriate physiological and meteorological conditions. Although only rarely reported in the golden orbweb spiders, family Nephilidae, the large geographic distributions of most nephilids—in particular of Nephila species—would imply that these spiders likely routinely disperse by ballooning in spite of giant female sizes. Here we study ballooning behavior in the golden orbweb spider Nephila pilipes (Fabricius, 1793. Specifically, we test for the propensity of spiderlings to deploy ballooning as a dispersal mechanism. We subjected a total of 59 first-instar spiderlings to a wind experiment at two wind speeds (2.17 ± 0.02 m s-1 and 3.17 ± 0.02 m s-1 under laboratory conditions. Under an average wind speed of 3.17 m s-1, none of the spiderlings exhibited pre-ballooning or ballooning behavior. However, at an average wind speed of 2.17 m s-1, 53 (89.8% spiderlings showed pre-ballooning behavior, and 17 (32.1% of the pre-ballooners ultimately ballooned. Our results concur with prior reports on spiderlings of other families that pre-ballooning behavior is a requirement for ballooning to occur. Furthermore, although we cannot rule out other dispersal mechanisms such as synanthropic spread, our findings suggest that the widespread N. pilipes uses ballooning to colonize remote oceanic islands.

  1. Spiders of the Vine Plants in Southern Moravia

    Directory of Open Access Journals (Sweden)

    Lucie Havlová

    2015-01-01

    Full Text Available Araneofauna of vineyards is relatively known in Central Europe but we have a lack of knowledge about araneofauna which occur directly on the vine plants. Our investigation was focused on spiders which live on vine plants, especially on the vine plants trunks. We investigated spiders in six vineyards in southern Moravia (Šatov, Mikulov, Popice, Morkůvky, Nosislav and Blučina. Vineyards were under different soil management, traps were placed on different parts of particular locality (terraced and plain and all localities were under integrated pest management. We employed two types of cardboard traps for spider collecting during whole vegetation season. Altogether, we collected 21 spider species which belong to seven families. The most important species was Marpissa nivoyi (Lucas, 1836, which is mentioned in the Red List as vulnerable (VU and Sibianor tantulus (Simon, 1868 which had unknown distribution in the Czech Republic. The other very interesting result is that the most common species is myrmecomorph Synageles venator (Lucas, 1836, which is scarcely recorded in such huge numbers as we documented in our study.

  2. Spiders (Araneae) as polyphagous natural enemies in orchards

    NARCIS (Netherlands)

    Bogya, S.

    1999-01-01

    Spiders (Araneae) occur in high abundance in all terrestrial ecosystems including agro-ecosystems. They are a very heterogeneous group of animals with different hunting tactics and therefore they play very different ecological roles. At family level these tactics are rather similar thus

  3. Effects of Packaging and Storage Conditions on Quality of Spider ...

    African Journals Online (AJOL)

    The purpose of this research was to increase insight into how the seed quality of spider plant is affected by different packaging containers, seed moisture content and storage temperatures, with a view to finding out the optimal method of packaging and storing of these seeds. This study was carried out using seeds dried ...

  4. Female mating strategy during precopulatory mate guarding in spider mites

    NARCIS (Netherlands)

    Oku, K.

    2009-01-01

    In some taxa, females choose their mates indirectly by using male combat. In the Kanzawa spider mite, Tetranychus kanzawai, adult males guard prereproductive quiescent females. In a dual choice experiment, more males first approached females already guarded by a conspecific male than approached

  5. The sejugal furrow in camel spiders and acariform mites

    Directory of Open Access Journals (Sweden)

    Dunlop, Jason A.

    2012-07-01

    Full Text Available Camel spiders (Arachnida: Solifugae are one of the arachnid groups characterised by a prosomal dorsal shield composed of three distinct elements: the pro-, meso- and metapeltidium. These are associated respectively with prosomal appendages one to four, five, and six. What is less well known, although noted in the historical literature, is that the coxae of the 4th and 5th prosomal segments (i.e. walking legs 2 and 3 of camel spiders are also separated ventrally by a distinct membranous region, which is absent between the coxae of the other legs. We suggest that this essentially ventral division of the prosoma specifically between coxae 2 and 3 is homologous with the so-called sejugal furrow (the sejugal interval sensu van der Hammen. This division constitutes a fundamental part of the body plan in acariform mites (Arachnida: Acariformes. If homologous, this sejugal furrow could represent a further potential synapomorphy for (Solifugae + Acariformes; a relationship with increasing morphological and molecular support. Alternatively, outgroup comparison with sea spiders (Pycnogonida and certain early Palaeozoic fossils could imply that the sejugal furrow defines an older tagma, derived from a more basal grade of organisation. In this scenario the (still divided prosoma of acariform mites and camel spiders would be plesiomorphic. This interpretation challenges the textbook arachnid character of a peltidium (or ‘carapace’ covering an undivided prosoma.

  6. Czech Republic – the type material of spiders (Araneae)

    Czech Academy of Sciences Publication Activity Database

    Růžička, Vlastimil; Kůrka, A.; Buchar, J.; Řezáč, M.

    2005-01-01

    Roč. 174, 1-4 (2005), s. 13-64 ISSN 0139-9543 R&D Projects: GA AV ČR(CZ) IAA6007401 Institutional research plan: CEZ:AV0Z50070508 Keywords : spiders * type material * Czech Republic Subject RIV: EG - Zoology

  7. Shedding light on the optical properties of spider silk fiber

    OpenAIRE

    Chow, Desmond M.; Tow, Kenny Hey; Vollrath, Fritz; Dicaire, Isabelle; Gheysens, Tom; Thevenaz, Luc

    2015-01-01

    Optical characterisation of a Nephila edulis spider dragline silk is performed. The silk fiber transmits light up to 1400 nm with a propagation loss of ∼9 dB/cm and birefringence of 8×10−3 measured at 1302 nm.

  8. Infrared and Raman Study of the Recluse Spider Silk

    Science.gov (United States)

    Wang, S. L.; Wang, Qijue; Xing, Zhen; Schniepp, H. C.; Qazilbash, M. M.

    Spider silk exhibits remarkable mechanical properties, such as high tensile strength and toughness. We want to gain insight into the composition and structure of spider silk to discover the origin of these properties. We are especially interested in the organization of the crystalline beta sheets that are expected to contribute to the high strength of the silk from the recluse spider, Loxosceles laeta. The recluse spider produces a silk that has a unique geometry amongst arachnids. We measure the silk's optical properties, particularly the infrared-active and Raman-active vibrations. Broadband infrared transmission spectra were collected in the spectral range between 600 cm-1 and 4000 cm-1, with light polarized parallel and perpendicular to the long axis of the silk. Raman micro-spectroscopy was performed in the spectral range 500 cm-1 and 4000 cm- 1 with a 514 nm laser. The infrared and Raman vibrational modes are fit with Lorentzian and pseudo-Voigt functions. The vibrational modes are assigned to specific structures and electronic bonds in the silk. This work was supported by NASA/ Virginia Space Grant Consortium.

  9. Characteristics of the first recorded spider (Arthropoda: Arachnida fauna from Sheringal, Khyber Pakhtunkhwa, Pakistan

    Directory of Open Access Journals (Sweden)

    Farzana Khan Perveen

    2015-12-01

    Full Text Available The spiders (order: Aranae are an important environmental indicator and play a significant role as predators in biological control of the most of the key insect pests. The present study was conducted to establish the characteristics of the first recorded spider fauna from Sheringal, Dir Upper (DU, Khyber Pakhtunkhwa (KP, Pakistan during June 2013-July 2014. Their 10 species belong to 7 families, and 10 genera (nt=123: total; ni=77: identified; nui=46: unidentified were recorded in the 6 quadrates, i.e., Daramdala, Doki, Guryaal, Samang, Shahoor and Sia-Sheringal of Sheringal. The largest family was Lycosidae (wolf spiders with respect to size and numbers of specimens collected (n=20, which contained Arctosa littorali Simon, 1897; Hippasa partita Takidar, 1970; Pardosa distincta Backwall, 1867, while the smallest family was Gnphosidae (ground spiders (n=3 with Gnaphosa eucalyptus Ghafoor and Beg, 2002; while other families Sparassidae (huntsman spiders (n=19 Halconia insignis Thorell, 1836, and Isopeda tuhogniga Barrion and Litsinger, 1995, Opilionidae (harvestmen spiders (n=12 Hadrobunus grandis Sundevall, 1833; Pholcidae (cellar spider (n=10 have Crossopriza lyoni Blackwall, 1867; Hersiliidae (two-tailed spiders (n=6 is having Harsilia savignyi Lucas, 1836; (n=5 with Araneus diadematus Clerck, 1757 were recorded. It was concluded that 50% of the spiders collected from the study area were venomous. A detail study is required for further exploration of spider fauna of Sheringal, KP, Pakistan with special reference to their taxonomical, physiological and ecological characteristics.

  10. Evaluating Stem Cell Response to a Spider Silk Scaffold

    Science.gov (United States)

    Hafner, Katherine Lee

    Micropatterning on a surface using fibers, channels, and troughs, can act as an effective means of inducing cell attachment and alignment. These morphological and pattern changes as a response to physical cues can impact the potential that a cell has to differentiate into a different cell line. This thesis evaluated the response of human dental pulp stem cells (DPSCs), and other cell types, to spider dragline silk fibers, a potential scaffold material for tissue regeneration, and further observed the effects of morphology, orientation, and composition of silk on the adherence of cells. Several cell lines were studied in this thesis, including adipose derived stem cells (ADSCs), osteoblasts (7F2s), and fibroblasts (3T3s), but DPSCs were the main cell type of interest. This is due to the fact that DPSCs are a proposed source of stem cells for nerve regeneration based on their close embryonic origin to neurons and the ease with which DPSCs can be obtained from a donor. The cells' morphologies and spread patterns were characterized after they were plated onto Nephila clavipes dragline fibers in media. The inclusion of 3T3s and 7F2s in this study allowed for both direct comparisons to prior published work and a qualitative comparison to the morphology of the DPSCs. After twelve days, the DPSCs exhibited greater relative alignment and adherence to the spider dragline fibers than the 3T3s and 7F2s when silk was wrapped in an aligned orientation rather than a random orientation. The impact of a common sterilization method (ultraviolet light) on the spider dragline fiber surface and subsequent cell response to this modified surface was also characterized. Exposure of the silk to ultraviolet light did not have a measureable effect on cell alignment, but it did eliminate bacterial growth and changed fiber surface roughness. Spiders' exposure to stressful environments did not have an effect on silk to impair cell alignment or adhesion, and synthetic recombinant protein silk

  11. Spin-polarized spin excitation spectroscopy

    International Nuclear Information System (INIS)

    Loth, Sebastian; Lutz, Christopher P; Heinrich, Andreas J

    2010-01-01

    We report on the spin dependence of elastic and inelastic electron tunneling through transition metal atoms. Mn, Fe and Cu atoms were deposited onto a monolayer of Cu 2 N on Cu(100) and individually addressed with the probe tip of a scanning tunneling microscope. Electrons tunneling between the tip and the substrate exchange energy and spin angular momentum with the surface-bound magnetic atoms. The conservation of energy during the tunneling process results in a distinct onset threshold voltage above which the tunneling electrons create spin excitations in the Mn and Fe atoms. Here we show that the additional conservation of spin angular momentum leads to different cross-sections for spin excitations depending on the relative alignment of the surface spin and the spin of the tunneling electron. For this purpose, we developed a technique for measuring the same local spin with a spin-polarized and a non-spin-polarized tip by exchanging the last apex atom of the probe tip between different transition metal atoms. We derive a quantitative model describing the observed excitation cross-sections on the basis of an exchange scattering process.

  12. Magnons, Spin Current and Spin Seebeck Effect

    Science.gov (United States)

    Maekawa, Sadamichi

    2012-02-01

    When metals and semiconductors are placed in a temperature gradient, the electric voltage is generated. This mechanism to convert heat into electricity, the so-called Seebeck effect, has attracted much attention recently as the mechanism for utilizing wasted heat energy. [1]. Ferromagnetic insulators are good conductors of spin current, i.e., the flow of electron spins [2]. When they are placed in a temperature gradient, generated are magnons, spin current and the spin voltage [3], i.e., spin accumulation. Once the spin voltage is converted into the electric voltage by inverse spin Hall effect in attached metal films such as Pt, the electric voltage is obtained from heat energy [4-5]. This is called the spin Seebeck effect. Here, we present the linear-response theory of spin Seebeck effect based on the fluctuation-dissipation theorem [6-8] and discuss a variety of the devices. [4pt] [1] S. Maekawa et al, Physics of Transition Metal Oxides (Springer, 2004). [0pt] [2] S. Maekawa: Nature Materials 8, 777 (2009). [0pt] [3] Concept in Spin Electronics, eds. S. Maekawa (Oxford University Press, 2006). [0pt] [4] K. Uchida et al., Nature 455, 778 (2008). [0pt] [5] K. Uchida et al., Nature Materials 9, 894 (2010) [0pt] [6] H. Adachi et al., APL 97, 252506 (2010) and Phys. Rev. B 83, 094410 (2011). [0pt] [7] J. Ohe et al., Phys. Rev. B (2011) [0pt] [8] K. Uchida et al., Appl. Phys. Lett. 97, 104419 (2010).

  13. PREFACE: SPIN2010 - Preface for Conference Proceedings

    Science.gov (United States)

    Ströher, Hans; Rathmann, Frank

    2011-03-01

    facilities at FZJ, and many made the most of the opportunity. We gratefully acknowledge the financial support from Brookhaven National Laboratory (BNL, USA), Forschungszentrum Jülich (FZJ), the International Union of Pure And Applied Physics (IUPAP), Thomas Jefferson Laboratory (JLab, USA), Helmholtz Institute Mainz (HIM, Germany) and the Virtual Institute on Spin and Strong QCD (VI-QCD) of the Helmholtz Association (HGF). We would also like to thank the local people from IKP and other institutions of FZJ for their contributions and help - without them we would not have been able to organize this great meeting. The current proceedings comprise written contributions of many of the presentations during SPIN2010; however, due to the recent incident in Japan, a number of our colleagues from there were unfortunately not able to deliver their write-ups in due time. This volume was edited by Ralf Gebel, Christoph Hanhart, Andro Kacharava, Andreas Lehrach, Bernd Lorentz, Nikolai N Nikolaev, Andreas Nogga, Frank Rathmann, and Hans Ströher. The next symposium - SPIN2012 - will be held at the Joint Institute for Nuclear Research (JINR) in Dubna (Russia) in 2012. We are looking forward to meeting you there. Important conference-related links: SPIN2010 Web-site: https://www.congressa.de/SPIN2010/ Article in CERN Courier: http://cerncourier.com/cws/article/cern/45451 Spin Physics Committee: http://www.spin-community.org Jülich, April 2011 - Hans Ströher, Frank Rathmann (Chairs SPIN2010) Conference photograph

  14. SPIDERS (ARANEI OF THE REPUBLIC OF SOUTH OSSETIA

    Directory of Open Access Journals (Sweden)

    Alexander V. Ponomarev

    2015-01-01

    Full Text Available Aim. Until recently, spider fauna of the Republic of South Ossetia has been the least studied among the regional araneofaunas of the Caucasus. According to the literature data, as little as 30 spider species have been known from the republic’s territory (Mkheidze, 1997, Mikhailov, 1990; Ponomarev, Dvadnenko, 2013; Trilicauscas, Komarov, 2014. Therefore, the aim of the present article is to summarize available data on the spider fauna of South Ossetia.Location. Republic of South Ossetia.Methods. The material was collected in various districts of South Ossetia in 2011-2014 by Yu.E. Komarov. Mainly, the collecting was performed in the city of Tskhinvali and its environs, and in the South Ossetian State Reserve. Spiders were sampled with pitfall traps and sweep netting. The time of traps’ exposure is April–December.Results and main conclusions. To date, the spider fauna of the Republic of South Ossetia includes 230 species from 29 families. 222 species were registered by the authors, eight species (Clubiona pseudosimilis, Gnaphosa lugubris, Linyphia hortensis, Neriene peltata, Geolycosa vultuosa, Pardosa azerifalcata, Ero aphana, and Philodromus rufus are known from the literature only. Seven species are new to the Caucasus (Clubiona pseudosimilis, Gnaphosa lugubris, Linyphia hortensis, Neriene peltata, Geolycosa vultuosa, Pardosa azerifalcata, Ero aphana, and Philodromus rufus. Of these, two species were known earlier only from Turkey (Pardosa consimilis, Ozyptila spirembolus, and one species (Tegenaria pseudolyncea only from Azerbaijan. Against the background of the widespread species predominance, the Caucasian element is small and presented by twelve species (Tegenaria pseudolyncea, Dysdera tkibuliensis, Haplodrassus caucasius, Zelotes khostensis, Mansuphantes ovalis, Sintula oseticus, Tenuiphantes teberdaensis, Pardosa azerifalcata, P. caucasica, Piratula hurkai, Trochosa cachetiensis, and Xysticus ukrainicus.

  15. Brown Spider (Loxosceles genus Venom Toxins: Tools for Biological Purposes

    Directory of Open Access Journals (Sweden)

    Andrea Senff-Ribeiro

    2011-03-01

    Full Text Available Venomous animals use their venoms as tools for defense or predation. These venoms are complex mixtures, mainly enriched of proteic toxins or peptides with several, and different, biological activities. In general, spider venom is rich in biologically active molecules that are useful in experimental protocols for pharmacology, biochemistry, cell biology and immunology, as well as putative tools for biotechnology and industries. Spider venoms have recently garnered much attention from several research groups worldwide. Brown spider (Loxosceles genus venom is enriched in low molecular mass proteins (5–40 kDa. Although their venom is produced in minute volumes (a few microliters, and contain only tens of micrograms of protein, the use of techniques based on molecular biology and proteomic analysis has afforded rational projects in the area and permitted the discovery and identification of a great number of novel toxins. The brown spider phospholipase-D family is undoubtedly the most investigated and characterized, although other important toxins, such as low molecular mass insecticidal peptides, metalloproteases and hyaluronidases have also been identified and featured in literature. The molecular pathways of the action of these toxins have been reported and brought new insights in the field of biotechnology. Herein, we shall see how recent reports describing discoveries in the area of brown spider venom have expanded biotechnological uses of molecules identified in these venoms, with special emphasis on the construction of a cDNA library for venom glands, transcriptome analysis, proteomic projects, recombinant expression of different proteic toxins, and finally structural descriptions based on crystallography of toxins.

  16. RHIC spin physics: Proceedings. Volume 7

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-12-01

    This proceedings compiles one-page summaries and five transparencies for each talk, with the intention that the speaker should include a web location for additional information in the summary. Also, email addresses are given with the participant list. The order follows the agenda: gluon, polarimetry, accelerator, W production and quark/antiquark polarization, parity violation searches, transversity, single transverse spin, small angle elastic scattering, and the final talk on ep collisions at RHIC. The authors begin the Proceedings with the full set of transparencies from Bob Jaffe`s colloquium on spin, by popular request.

  17. RHIC spin physics: Proceedings. Volume 7

    International Nuclear Information System (INIS)

    1998-01-01

    This proceedings compiles one-page summaries and five transparencies for each talk, with the intention that the speaker should include a web location for additional information in the summary. Also, email addresses are given with the participant list. The order follows the agenda: gluon, polarimetry, accelerator, W production and quark/antiquark polarization, parity violation searches, transversity, single transverse spin, small angle elastic scattering, and the final talk on ep collisions at RHIC. The authors begin the Proceedings with the full set of transparencies from Bob Jaffe's colloquium on spin, by popular request

  18. RCrawler: An R package for parallel web crawling and scraping

    Science.gov (United States)

    Khalil, Salim; Fakir, Mohamed

    RCrawler is a contributed R package for domain-based web crawling and content scraping. As the first implementation of a parallel web crawler in the R environment, RCrawler can crawl, parse, store pages, extract contents, and produce data that can be directly employed for web content mining applications. However, it is also flexible, and could be adapted to other applications. The main features of RCrawler are multi-threaded crawling, content extraction, and duplicate content detection. In addition, it includes functionalities such as URL and content-type filtering, depth level controlling, and a robot.txt parser. Our crawler has a highly optimized system, and can download a large number of pages per second while being robust against certain crashes and spider traps. In this paper, we describe the design and functionality of RCrawler, and report on our experience of implementing it in an R environment, including different optimizations that handle the limitations of R. Finally, we discuss our experimental results.

  19. Spin-Mechatronics

    Science.gov (United States)

    Matsuo, Mamoru; Saitoh, Eiji; Maekawa, Sadamichi

    2017-01-01

    We investigate the interconversion phenomena between spin and mechanical angular momentum in moving objects. In particular, the recent results on spin manipulation and spin-current generation by mechanical motion are examined. In accelerating systems, spin-dependent gauge fields emerge, which enable the conversion from mechanical angular momentum into spins. Such a spin-mechanical effect is predicted by quantum theory in a non-inertial frame. Experiments which confirm the effect, i.e., the resonance frequency shift in nuclear magnetic resonance, the stray field measurement of rotating metals, and electric voltage generation in liquid metals, are discussed.

  20. Evaluation of fixative solutions for ultrastructural analysis of brown spider Loxosceles intermedia (araneae: sicariidae) tissues

    OpenAIRE

    Costa-Ayub,C. L. S.; Faraco,C. D.; Freire,C. A.

    2006-01-01

    In view of the widely varying compositions of fixative solutions used for studying spiders, five different fixative formulas were tested for fixing male brown-spider (Loxosceles intermedia) gonad tissues. The brown spider represents a public health problem in Curitiba (Paraná State, Brazil). Morphological study of its gonads may aid in understanding the reproductive strategies of this species, and possibly in developing a reproduction control program. The fixatives tested contained glutaralde...

  1. On the predation of fly, Chrysomya rufifacies (Macquart) by a spider, Oxyopes sp. Latreille (Oxyopidae).

    Science.gov (United States)

    Heo, C C; Mohamad, A M; John, J; Baharudin, O

    2008-04-01

    During a forensic entomological study conducted in a palm oil plantation in Tg.Sepat, Selangor in September 2007, a spider (Arachnida), Oxyopes sp. (Oxyopidae) was found to predate on a calliphorid fly (Chrysomya rufifacies). The female spider laid a silk thread, or "drag line", behind it as it moved. This spider bites its prey by using a pairs of chelicerae, and injecting venom into the fly. The fly was moving its wing trying to escape, however, it succumbed to the deadly bite.

  2. Exploring of the first recorded spider (Arachenida: Aranae) species of Sheringal, Khyber Pakhtunkhwa, Pakistan

    OpenAIRE

    Farzana Perveen; Numan Khan

    2015-01-01

    The spiders (Arthropoada: Arachenida) are one of the groups of grasping animals. Their carapaces are found on the dorsal side of the cephalothorax, which is an important characteristic of spiders. The present study was conducted to explore the first recorded spider species (nti=75) of Sheringal, Dir Upper (DU), Khyber Pakhtunkhwa (KP), Dir Upper, Khyber Pakhtunkhwa, Pakistan. The 10 genera with 10 species under 7 families were recorded from June 2013-July 2014. According to length of legs, th...

  3. Exploring of the first recorded spider (Arachenida: Aranae species of Sheringal, Khyber Pakhtunkhwa, Pakistan

    Directory of Open Access Journals (Sweden)

    Farzana Perveen

    2015-09-01

    Full Text Available The spiders (Arthropoada: Arachenida are one of the groups of grasping animals. Their carapaces are found on the dorsal side of the cephalothorax, which is an important characteristic of spiders. The present study was conducted to explore the first recorded spider species (nti=75 of Sheringal, Dir Upper (DU, Khyber Pakhtunkhwa (KP, Dir Upper, Khyber Pakhtunkhwa, Pakistan. The 10 genera with 10 species under 7 families were recorded from June 2013-July 2014. According to length of legs, the largest spider was the huntsman spider, Halconia insignis Thorell having length of the first leg was 1.9±0.20, however, the same of the last leg was 1.44±0.25 (n=9. In the same contest, the smallest spider was the ground spider, Gnaphosa eucalyptus Ghafoor and Beg having length of the first leg was 0.4±0.08, while the same of the last leg was 0.4±0.08 (n=3. According to length of cephalothorax and abdomen, the largest spider was the wolf spider, Hippasa partita Takidar having length of the cephalothorax was 1.1±0.01, however, the same of the abdomen was 0.7±0.1 (n=6. In the same contest, the smallest spider was the harvestmen, Hadrobunus grandis Sundevall having length of the cephalothorax was 0.1±0.04, while the same of the abdomen was 0.3±0.04 (n=12. During present research, 10 spider species of Sheringal with different sizes were explored. The present research will be useful to educate and create awareness about spiders in the people of Sheringal.

  4. Case report: compartment syndrome after a suspected black widow spider bite.

    Science.gov (United States)

    Cohen, Jennifer; Bush, Sean

    2005-04-01

    Widow spider envenomations generally produce systemic neurologic syndromes without significant local injury. We report a patient who sustained a black widow spider bite to the left forearm and presented to the emergency department with rhabdomyolysis and compartment syndrome. We documented a decrease in symptoms and compartment pressure after administration of antivenom. No surgical intervention was performed. We believe this report to be the first documenting compartment syndrome associated with black widow spider bite.

  5. Ontogenesis, gender, and molting influence the venom yield in the spider Coremiocnemis tropix (Araneae, Theraphosidae)

    OpenAIRE

    Herzig, Volker

    2010-01-01

    The demand for spider venom increases along with the growing popularity of venoms-based research. A deeper understanding of factors that influence the venom yield in spiders would therefore be of interest to both commercial venom suppliers and research facilities. The present study addresses the influence of several factors on the venom yield by systematically analyzing the data obtained from 1773 electrical milkings of the Australian theraphosid spider Coremiocnemis tropix. Gender and ontoge...

  6. Two-dimensional spin diffusion in multiterminal lateral spin valves

    Science.gov (United States)

    Saha, D.; Basu, D.; Holub, M.; Bhattacharya, P.

    2008-01-01

    The effects of two-dimensional spin diffusion on spin extraction in lateral semiconductor spin valves have been investigated experimentally and theoretically. A ferromagnetic collector terminal of variable size is placed between the ferromagnetic electron spin injector and detector of a conventional lateral spin valve for spin extraction. It is observed that transverse spin diffusion beneath the collector terminal plays an important role along with the conventional longitudinal spin diffusion in describing the overall transport of spin carriers. Two-dimensional spin diffusion reduces the perturbation of the channel electrochemical potentials and improves spin extraction.

  7. Polymorphic regenerated silk fibers assembled through bioinspired spinning.

    Science.gov (United States)

    Ling, Shengjie; Qin, Zhao; Li, Chunmei; Huang, Wenwen; Kaplan, David L; Buehler, Markus J

    2017-11-09

    A variety of artificial spinning methods have been applied to produce regenerated silk fibers; however, how to spin regenerated silk fibers that retain the advantages of natural silks in terms of structural hierarchy and mechanical properties remains challenging. Here, we show a bioinspired approach to spin regenerated silk fibers. First, we develop a nematic silk microfibril solution, highly viscous and stable, by partially dissolving silk fibers into microfibrils. This solution maintains the hierarchical structures in natural silks and serves as spinning dope. It is then spun into regenerated silk fibers by direct extrusion in the air, offering a useful route to generate polymorphic and hierarchical regenerated silk fibers with physical properties beyond natural fiber construction. The materials maintain the structural hierarchy and mechanical properties of natural silks, including a modulus of 11 ± 4 GPa, even higher than natural spider silk. It can further be functionalized with a conductive silk/carbon nanotube coating, responsive to changes in humidity and temperature.

  8. Diet-dependent fecundity of the spiders Atypena formosana and Pardosa pseudoannulata, predators in irrigated rice

    DEFF Research Database (Denmark)

    Sigsgaard, Lene; Toft, Søren; Villareal, Sylvia

    2001-01-01

    of Collembola and D. melanogaster had the highest quality for both spiders, the BPH-GLH-Collembola and the full mixed diets were intermediate in quality, the quality of the BPH diet was intermediate to low and quality of the GLH and BPH-GLH diets was low. There need not be a contradiction between low dietary...... value of hoppers and successful natural biological control provided that the nutritional needs of the spiders are met by sufficient alternative prey. The hopper-spider relationship is comparable to that of aphids and spiders in temperate cereals, suggesting that low dietary quality of Homopterans...

  9. Methods of assembling and disassembling spider and burnable poison rod structures for nuclear reactors

    International Nuclear Information System (INIS)

    Edwards, G.T.; Schluderberg, D.C.

    1981-01-01

    A technique is provided for engaging and disengaging burnable poison rods from a spider in a nuclear reactor fuel assembly. A cap on the end of each of the burnable poison rods is provided with a shank or stem that is received in a respective bore formed in the spider. A frangible flange secures the shank and rod to the spider. Pressing the shank in the direction of the bore axis by means, e.g., of a plate ruptures the frangible flange to release the rod from the spider. (author)

  10. Functional Group of Spiders in Cultivated Landscape Dominated by Paddy Fields in West Java, Indonesia

    Directory of Open Access Journals (Sweden)

    I WAYAN SUANA

    2009-03-01

    Full Text Available Distribution of spiders in all colonized environments is limited by biotic and abiotic factors requiring adaptations with respect to, for example microhabitat choice and hunting behavior. These two factors were frequently used to group spiders into functional groups. In this study our objectives were to (i group of genera of spiders into functional group based on their microhabitat specificity, hunting behavior, and daily activity; and (ii compare the number and composition of functional group of spider at each habitat type and period of paddy growth. The study was conducted at a landscape dominated by paddy fields in Cianjur Watershed for a period of 9 months. Four different habitat types (paddy, vegetable, non-crop, and mixed garden, were sampled using five trapping techniques (pitfall traps, farmcop suction, sweep netting, yellow-pan traps, and sticky traps. The Unweighted Pair-Group Average and the Euclidean Distances were used to generate dendrogram of functional group of spider. We found 14 functional groups of spider at genus level. The number of functional group of spider at four habitat types was differing, but the composition was similar, because all habitats were closed to each other. Habitat structure diversity and disturbance level influenced the number of functional group of spider. Different architecture of vegetation and availability of differ prey during paddy growth, causing the composition of functional group of spider in each period of paddy growth was changed, although its number was unchanged.

  11. Spider Transcriptomes Identify Ancient Large-Scale Gene Duplication Event Potentially Important in Silk Gland Evolution.

    Science.gov (United States)

    Clarke, Thomas H; Garb, Jessica E; Hayashi, Cheryl Y; Arensburger, Peter; Ayoub, Nadia A

    2015-06-08

    The evolution of specialized tissues with novel functions, such as the silk synthesizing glands in spiders, is likely an influential driver of adaptive success. Large-scale gene duplication events and subsequent paralog divergence are thought to be required for generating evolutionary novelty. Such an event has been proposed for spiders, but not tested. We de novo assembled transcriptomes from three cobweb weaving spider species. Based on phylogenetic analyses of gene families with representatives from each of the three species, we found numerous duplication events indicative of a whole genome or segmental duplication. We estimated the age of the gene duplications relative to several speciation events within spiders and arachnids and found that the duplications likely occurred after the divergence of scorpions (order Scorpionida) and spiders (order Araneae), but before the divergence of the spider suborders Mygalomorphae and Araneomorphae, near the evolutionary origin of spider silk glands. Transcripts that are expressed exclusively or primarily within black widow silk glands are more likely to have a paralog descended from the ancient duplication event and have elevated amino acid replacement rates compared with other transcripts. Thus, an ancient large-scale gene duplication event within the spider lineage was likely an important source of molecular novelty during the evolution of silk gland-specific expression. This duplication event may have provided genetic material for subsequent silk gland diversification in the true spiders (Araneomorphae). © The Author(s) 2015. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

  12. Latrodectism: case report of a katipo spider (Latrodectus katipo) bite and review of the literature.

    Science.gov (United States)

    Thatcher, Lucinda; Janes, Ron

    2012-03-09

    We describe the case of a 29-year-old man who was bitten on the leg by a katipo spider, a relative of the Australian redback and American black widow spiders, while camping in sand dunes at Mahanga Beach, Mahia (North Island of New Zealand). Symptoms of latrodectism developed within hours, and were not diminished until two doses of the antivenom had been administered. This is only the second case report of a katipo spider bite in the recent literature. The katipo spider bite produces significant symptoms, however an antivenom is available in some hospital pharmacies.

  13. Spiders do not evoke greater early posterior negativity in the event-related potential as snakes.

    Science.gov (United States)

    He, Hongshen; Kubo, Kenta; Kawai, Nobuyuki

    2014-09-10

    It has been long believed that both snakes and spiders are archetypal fear stimuli for humans. Furthermore, snakes have been assumed as stronger threat cues for nonhuman primates. However, it is still unclear whether spiders hold a special status in human perception. The current study explored to what extent spider pictures draw early visual attention [as assessed with early posterior negativity (EPN)] when compared with insects similar to spiders. To measure the EPN, participants watched a random rapid serial presentation of pictures, which consisted of two conditions: spider condition (spider, wasp, bumblebee, beetle) and snake condition (snake, bird). EPN amplitudes revealed no significant difference between spider, wasp, bumblebee, and beetle pictures, whereas EPN amplitudes were significantly larger for snake pictures relative to bird pictures. In addition, EPN amplitudes were significantly larger for snake pictures relative to spider pictures. These results suggest that the early visual attentional capture of animate objects is stronger for snakes, whereas spiders do not appear to hold special early attentional value.

  14. Web Caching

    Indian Academy of Sciences (India)

    The user may never realize that the cache is between the client and server except in special circumstances. It is important to distinguish between Web cache and a proxy server as their functions are often misunderstood. Proxy servers serve as an intermediary to place a firewall between network users and the outside world.

  15. Fiber webs

    Science.gov (United States)

    Roger M. Rowell; James S. Han; Von L. Byrd

    2005-01-01

    Wood fibers can be used to produce a wide variety of low-density three-dimensional webs, mats, and fiber-molded products. Short wood fibers blended with long fibers can be formed into flexible fiber mats, which can be made by physical entanglement, nonwoven needling, or thermoplastic fiber melt matrix technologies. The most common types of flexible mats are carded, air...

  16. Dynamic nuclear spin polarization

    Energy Technology Data Exchange (ETDEWEB)

    Stuhrmann, H.B. [GKSS-Forschungszentrum Geesthacht GmbH (Germany)

    1996-11-01

    Polarized neutron scattering from dynamic polarized targets has been applied to various hydrogenous materials at different laboratories. In situ structures of macromolecular components have been determined by nuclear spin contrast variation with an unprecedented precision. The experiments of selective nuclear spin depolarisation not only opened a new dimension to structural studies but also revealed phenomena related to propagation of nuclear spin polarization and the interplay of nuclear polarisation with the electronic spin system. The observation of electron spin label dependent nuclear spin polarisation domains by NMR and polarized neutron scattering opens a way to generalize the method of nuclear spin contrast variation and most importantly it avoids precontrasting by specific deuteration. It also likely might tell us more about the mechanism of dynamic nuclear spin polarisation. (author) 4 figs., refs.

  17. Spin at Lausanne

    International Nuclear Information System (INIS)

    Anon.

    1980-01-01

    From 25 September to 1 October, some 150 spin enthusiasts gathered in Lausanne for the 1980 International Symposium on High Energy Physics with Polarized Beams and Polarized Targets. The programme was densely packed, covering physics interests with spin as well as the accelerator and target techniques which make spin physics possible

  18. Spin-torque transistor

    NARCIS (Netherlands)

    Bauer, G.E.W.; Brataas, A.; Tserkovnyak, Y.; Van Wees, B.J.

    2003-01-01

    A magnetoelectronic thin-film transistor is proposed that can display negative differential resistance and gain. The working principle is the modulation of the soure–drain current in a spin valve by the magnetization of a third electrode, which is rotated by the spin-torque created by a control spin

  19. Lethal intragroup aggression by adult male spider monkeys (Ateles geoffroyi).

    Science.gov (United States)

    Campbell, Christina J

    2006-12-01

    I report three cases of coalitionary aggression by adult male black-handed spider monkeys (Ateles geoffroyi) against subadult males within their community on Barro Colorado Island (BCI), Panama. Two of these cases were followed by the disappearance and presumed death of the victim. Similar behavior was recently reported by Valero et al. [in press], who suggested that this behavior may be the result of intense male reproductive competition. Like the single instance they reported, the cases I report all occurred when the operational sex ratio was approximately 1:1, which suggests that intense competition among males for access to reproductively viable females may be a contributing factor. Additionally the very low density of spider monkeys on BCI may play a significant role in the occurrence of this lethal aggression. Large numbers of adult males are not necessary to protect a territorial boundary against neighboring groups, and additional males may act merely as mating competition. (c) 2006 Wiley-Liss, Inc.

  20. Optics of the ultraviolet reflecting scales of a jumping spider

    Science.gov (United States)

    Land, Michael F; Horwood, Julia; Lim, Matthew L.M; Li, Daiqin

    2007-01-01

    The jumping spider Cosmophasis umbratica from Singapore is strongly sexually dimorphic. The males, but not the females, reflect ultraviolet as well as green–orange light. The scales responsible for this are composed of a chitin–air–chitin sandwich in which the chitin layers are three-quarters of a wavelength thick and the air gap a quarter wavelength (where λ=600 nm, the peak wavelength of the principal reflection maximum). It is shown that this configuration produces a second reflectance peak at approximately 385 nm, accounting for the observed reflection in the ultraviolet. Other scales have a similar thickness of chitin but lack the air gap and thus produce a dull purple reflection. This novel mechanism provides the spiders with two colour signals, both of which are important in mating displays. PMID:17456453

  1. Battre sa (super) coulpe : Spider-Man (1962)

    OpenAIRE

    Tomasovic, Dick

    2016-01-01

    L’édification est l'une des grandes fonctions traditionnelles de la littérature de jeunesse. Spider-Man, héros populaire s'il en est, s'est révélé bien sûr l'ambassadeur de nombreuses valeurs sociétales américaines (le do it yourself, l'esprit d'entreprise et d'indépendance, la tolérance, la fidélité , la célébration du système éducationnel, la transmission et la solidarité intergénérationnelle, le sens des responsabilités, évidemment, etc.). Spider-Man se bat moins qu'il ne se débat. Il est ...

  2. Black widow spider envenomation, a rare cause of Horner's syndrome.

    Science.gov (United States)

    Strowd, Roy E; Scott, Blake; Walker, Francis O

    2012-06-01

    Horner's syndrome involves a triad of eyelid ptosis, miosis, and facial anhidrosis that results from disruption of the oculosympathetic pathway. Acquired Horner's syndrome is associated with a variety of medical conditions including Pancoast tumor and carotid dissection. We report the unique case of a 47-year-old man presenting with Horner's syndrome 4 weeks after black widow spider envenomation. Workup did not reveal any alternative explanatory etiology. We hypothesize that late sequelae of black widow spider envenomation secondary to autonomic nerve injury or retrograde axonal transport after mechanical inoculation may have led to an acquired defect in the oculosympathetic pathway resulting in a Horner's syndrome. This case introduces a rare cause of Horner's syndrome and highlights the importance of environmental exposures in the evaluation of these patients. Copyright © 2012 Wilderness Medical Society. Published by Elsevier Inc. All rights reserved.

  3. Gravity Reception and Cardiac Function in the Spider

    Science.gov (United States)

    Finck, A.

    1985-01-01

    The following features of the arachnid gravity system were studied. (1) the absolute threshold to hyper-gz is quite low indicating fine proprioreceptive properties of the lyriform organ, the Gz/vibration detector; (2) the neurogenic heart of the spider is a good dependent variable for assessing its behavior to Gz and other stimuli which produce mechanical effects on the exoskeleton; (3) Not only is the cardiac response useful but it is now understood to be an integral part of the system which compensates for the consequences of gravity in the spider (an hydraulic leg extension); and (4) a theoretical model was proposed in which a mechanical amplifier, the leg lever, converts a weak force (at the tarsus) to a strong force (at the patella), capable of compressing the exoskeleton and consequently the lyriform receptor.

  4. Structure to function: Spider silk and human collagen

    Science.gov (United States)

    Rabotyagova, Olena S.

    Nature has the ability to assemble a variety of simple molecules into complex functional structures with diverse properties. Collagens, silks and muscles fibers are some examples of fibrous proteins with self-assembling properties. One of the great challenges facing Science is to mimic these designs in Nature to find a way to construct molecules that are capable of organizing into functional supra-structures by self-assembly. In order to do so, a construction kit consisting of molecular building blocks along with a complete understanding on how to form functional materials is required. In this current research, the focus is on spider silk and collagen as fibrous protein-based biopolymers that can shed light on how to generate nanostructures through the complex process of self-assembly. Spider silk in fiber form offers a unique combination of high elasticity, toughness, and mechanical strength, along with biological compatibility and biodegrability. Spider silk is an example of a natural block copolymer, in which hydrophobic and hydrophilic blocks are linked together generating polymers that organize into functional materials with extraordinary properties. Since silks resemble synthetic block copolymer systems, we adopted the principles of block copolymer design from the synthetic polymer literature to build block copolymers based on spider silk sequences. Moreover, we consider spider silk to be an important model with which to study the relationships between structure and properties in our system. Thus, the first part of this work was dedicated to a novel family of spider silk block copolymers, where we generated a new family of functional spider silk-like block copolymers through recombinant DNA technology. To provide fundamental insight into relationships between peptide primary sequence, block composition, and block length and observed morphological and structural features, we used these bioengineered spider silk block copolymers to study secondary structure

  5. Black widow spider (Latrodectus mactans) envenomation in a term pregnancy.

    Science.gov (United States)

    Sherman; Groll; Gonzalez; Aerts

    2000-07-01

    Description of a black widow spider (Latrodectus mactans) envenomation in a term pregnancy.Case report conducted at an Air Force tertiary care hospital of a 27-year-old primigravida at 38 1/7 weeks pregnancy.Latrodectus mactans antivenin can be given to treat symptoms of black widow envenomation.Black widow envenomations can cause symptoms associated with acute intra-abdominal processes. In pregnancy, envenomations can result in symptoms and signs similar to those seen in preeclampsia (abdominal pain, headache, hypertension, and proteinuria). Latrodectism should be considered in patients complaining of these symptoms in association with a spider bite. If latrodectism is considered to be the underlying origin for these symptoms, appropriate treatment should be administered. In cases of pregnancy, treatment should include L. mactans antivenin if believed to be clinically indicated. There is no current evidence that this antivenin is contraindicated in pregnancy. (Curr Surg 57:346-348)

  6. Environmental Engineering Approaches toward Sustainable Management of Spider Mites.

    Science.gov (United States)

    Suzuki, Takeshi

    2012-10-26

    Integrated pest management (IPM), which combines physical, biological, and chemical control measures to complementary effect, is one of the most important approaches to environmentally friendly sustainable agriculture. To expand IPM, we need to develop new pest control measures, reinforce existing measures, and investigate interactions between measures. Continued progress in the development of environmental control technologies and consequent price drops have facilitated their integration into plant production and pest control. Here I describe environmental control technologies for the IPM of spider mites through: (1) the disturbance of photoperiod-dependent diapause by artificial light, which may lead to death in seasonal environments; (2) the use of ultraviolet radiation to kill or repel mites; and (3) the use of water vapor control for the long-term cold storage of commercially available natural enemies. Such environmental control technologies have great potential for the efficient control of spider mites through direct physical effects and indirect effects via natural enemies.

  7. A troglomorphic spider from Java (Araneae, Ctenidae, Amauropelma)

    Science.gov (United States)

    Miller, Jeremy; Rahmadi, Cahyo

    2012-01-01

    Abstract A new troglomorphic spider from caves in Central Java, Indonesia, is described and placed in the ctenid genus Amauropelma Raven, Stumkat & Gray, until now containing only species from Queensland, Australia. Only juveniles and mature females of the new species are known. We give our reasons for placing the new species in Amauropelma, discuss conflicting characters, and make predictions about the morphology of the as yet undiscovered male that will test our taxonomic hypothesis. The description includes DNA barcode sequence data. PMID:22303127

  8. Traditions in Spider Monkeys Are Biased towards the Social Domain

    OpenAIRE

    Santorelli, Claire J.; Schaffner, Colleen M.; Campbell, Christina J.; Notman, Hugh; Pavelka, Mary S.; Weghorst, Jennifer A.; Aureli, Filippo

    2011-01-01

    Cross-site comparison studies of behavioral variation can provide evidence for traditions in wild species once ecological and genetic factors are excluded as causes for cross-site differences. These studies ensure behavior variants are considered within the context of a species' ecology and evolutionary adaptations. We examined wide-scale geographic variation in the behavior of spider monkeys (Ateles geoffroyi) across five long-term field sites in Central America using a well established ethn...

  9. Innate pattern recognition and categorization in a jumping spider.

    Directory of Open Access Journals (Sweden)

    Yinnon Dolev

    Full Text Available The East African jumping spider Evarcha culicivora feeds indirectly on vertebrate blood by preferentially preying upon blood-fed Anopheles mosquitoes, the vectors of human malaria1, using the distinct resting posture and engorged abdomen characteristic of these specific prey as key elements for their recognition. To understand perceptual categorization of objects by these spiders, we investigated their predatory behavior toward different digital stimuli--abstract 'stick figure' representations of Anopheles constructed solely by known key identification elements, disarranged versions of these, as well as non-prey items and detailed images of alternative prey. We hypothesized that the abstract images representing Anopheles would be perceived as potential prey, and would be preferred to those of non-preferred prey. Spiders perceived the abstract stick figures of Anopheles specifically as their preferred prey, attacking them significantly more often than non-preferred prey, even when the comprising elements of the Anopheles stick figures were disarranged and disconnected from each other. However, if the relative angles between the elements of the disconnected stick figures of Anopheles were altered, the otherwise identical set of elements was no longer perceived as prey. These data show that E. culicivora is capable of making discriminations based on abstract concepts, such as the hypothetical angle formed by discontinuous elements. It is this inter-element angle rather than resting posture that is important for correct identification of Anopheles. Our results provide a glimpse of the underlying processes of object recognition in animals with minute brains, and suggest that these spiders use a local processing approach for object recognition, rather than a holistic or global approach. This study provides an excellent basis for a comparative analysis on feature extraction and detection by animals as diverse as bees and mammals.

  10. Spiders in mountain habitats of the Giant Mountains

    Czech Academy of Sciences Publication Activity Database

    Růžička, Vlastimil; Vaněk, J.; Šmilauer, P.

    2012-01-01

    Roč. 43, č. 4 (2012), s. 341-347 ISSN 1067-4136 Institutional research plan: CEZ:AV0Z50070508 Keywords : Giant Mountains (Krkonoše, Karkonosze) * spider s * anemo-orographic systems Subject RIV: EH - Ecology , Behaviour Impact factor: 0.236, year: 2012 http://www.springerlink.com/content/0k5g721q1155r146/fulltext.pdf

  11. Colonization of subterranean habitats by spiders in Central Europe

    Czech Academy of Sciences Publication Activity Database

    Růžička, Vlastimil; Šmilauer, P.; Mlejnek, R.

    2013-01-01

    Roč. 42, č. 2 (2013), s. 133-140 ISSN 0392-6672 Grant - others:GA JU(CZ) GAJU 04-142/2010/P Institutional support: RVO:60077344 Keywords : superficial and deep subterranean habitats * caves * spider s Subject RIV: EH - Ecology , Behaviour Impact factor: 1.275, year: 2013 http://scholarcommons.usf.edu/cgi/viewcontent.cgi?article=1288&context=ijs

  12. Early environmental conditions shape personality types in a jumping spider

    Directory of Open Access Journals (Sweden)

    Jannis eLiedtke

    2015-12-01

    Full Text Available Individuals of many species across the animal kingdom are found to be less plastic than expected, even in behavioral traits. The existence of consistent behavioral differences between individuals, termed personality differences, is puzzling, since plastic behavior is considered ideal to enable animals to adaptively respond to changes in environmental conditions. In order to elucidate which mechanisms are important for the evolution of personality differences, it is crucial to understand which aspects of the environment are important for the development of personality differences. Here, we tested whether physical or social aspects of the environment during development influence individual differentiation (mean level of behavior using the jumping spider Marpissa muscosa. Furthermore, we assessed whether those behaviors were repeatable, i.e. whether personalities existed. We applied a split-brood design and raised spider siblings in three different environments: a deprived environment with no enrichment, a socially and a physically enriched environment. We focused on exploratory behavior and repeatedly assessed individual behavior in a novel environment and a novel object test. Results show that the environment during development influenced spiders’ exploratory tendencies: spiders raised in enriched environments tended to be more exploratory. Most investigated behaviors were repeatable (i.e. personalities existed across all individuals tested, whereas only few behaviors were also repeatable across individuals that had experienced the same environmental condition. Taken together, our results indicate that external stimuli can influence the development of one aspect of personality, the inter-individual variation (mean level of behavior, in a jumping spider. We also found family by environment interactions on behavioral traits potentially suggesting genetic variation in developmental plasticity.

  13. Damage, Self-Healing, and Hysteresis in Spider Silks

    OpenAIRE

    De Tommasi, D.; Puglisi, G.; Saccomandi, G.

    2010-01-01

    In this article, we propose a microstructure-based continuum model to describe the material behavior of spider silks. We suppose that the material is composed of a soft fraction with entropic elasticity and a hard, damageable fraction. The hard fraction models the presence of stiffer, crystal-rich, oriented regions and accounts for the effect of softening induced by the breaking of hydrogen bonds. To describe the observed presence of crystals with different size, composition, and orientation,...

  14. [Neurotoxic manifestations of black widow spider envenomation in paediatric patients].

    Science.gov (United States)

    Sotelo-Cruz, N; Gómez-Rivera, N

    2016-05-01

    Envenomation by black widow spiders manifests clinically with signs of neurotoxicity in paediatric patients. Identify typical neurological signs and symptoms in paediatric patients of different ages, and describe treatment and outcomes in a paediatric hospital in northwest Mexico. We reviewed 70 clinical records of patients hospitalised due to black widow spider bite between 1978 and 2014. We divided the total into 2 groups: Group 1, infants and preschool children; and Group 2, school-age children and adolescents. The demographic variables were age, sex, birthplace, place where envenomation occurred, body part(s) affected, degree of envenomation according to signs and symptoms, treatment, clinical outcome, and statistical differences. Boys accounted for 61.4% of all cases, and infants younger than one year old made up 14.2%. Most patients (70%) were bitten by the spider at home; the anatomical areas most frequently affected were the legs, neck, thorax, and abdomen. The neurological signs and symptoms displayed by Group 1 were irritability, constant crying, sialorrhoea, nausea, tachycardia, arrhythmias, fatigue when walking, agitation, muscle spasms paraesthesia, tetany, seizures, and nystagmus. Signs in Group 2 included localized pain, headache, sialorrhoea, paraesthesia, profuse sweating, anxiety, muscle weakness, muscle spasms, and fine tremor. The predominant autonomic sign in Group 1 was sialorrhoea (P<.0001) and in Group 2, paraesthesia (P<.0001). Patients who received Fab antivenom treatment displayed better outcomes and shorter hospital stays than those who did not. No deaths were reported. The neurological signs and symptoms caused by black widow spider bite are predominantly autonomic, and identifying them permits early diagnosis and more effective treatment. Copyright © 2015 Sociedad Española de Neurología. Published by Elsevier España, S.L.U. All rights reserved.

  15. Visual Discrimination Learning in the Jumping Spider Phidippus regius

    OpenAIRE

    Massimo De Agrò; Lucia Regolin; Enzo Moretto

    2017-01-01

    Over the past decade, research in comparative psychology has increasingly focused on non-vertebrate models of cognition. Jumping spiders provide excellent models for the study of visually mediated behaviors, such as associative learning or the navigation of complex environments. Here, we tested visual and memory abilities of Phidippus regius to discriminate between artificial geometrical stimuli and to generalize the learned discrimination to illusory stimuli, using the amodal completion mech...

  16. Artificial insemination in black-handed spider monkey (Ateles geoffroyi).

    Science.gov (United States)

    Hernández-López, L; Cerda-Molina, A L; Páez-Ponce, D L; Rojas-Maya, S; Mondragón-Ceballos, R

    2007-01-15

    Artificial insemination (AI) was performed in spider monkeys; these primates are vulnerable to extinction and usually do not reproduce spontaneously in captivity. Uterine cycles were followed by daily assessment of vaginal cytology, and corroborated a posteriori by concentrations of 17-beta estradiol and progesterone, measured by radioimmunoassay (RIA), in fecal samples collected once daily. Five females between 13 to 27 years old were inseminated intravaginally (with fresh semen) twice each during the periovulatory phase (Days 9-12 of the menstrual cycle; Day 0, first day of menstrual bleeding), from September to the first 3 weeks of November (most fertile months). Transcervical AI was not useful in this primate because the liquid portion of the semen completely solidified instead of liquefying as in other primates. Pregnancies were apparently achieved in 5 of 14 attempts. One female became pregnant after the first round of inseminations, delivered a healthy infant, was inseminated and got pregnant again (subsequently aborted). One female aborted, apparently due to an intramural uterine leiomyoma. Another two females stopped menstruating for a few months, then restarted menstruating (these females may have been pregnant and aborted). In conclusion, in spider monkeys: (1) captivity-induced stress did not inhibit reproduction; (2) fecal steroid hormones were useful to assess cyclicity; (3) the semen coagulum, which apparently is a tightly packed and large reservoir of spermatozoa, must not be discarded but used in AI; (4) old female spider monkeys did not have cessation of reproductive function.

  17. Epigeic spiders of the pastures of northern Wielkopolska

    Directory of Open Access Journals (Sweden)

    Woźny, Marek

    2000-10-01

    Full Text Available The fauna of epigeic spiders (Araneae occurring on three different types of pastures in northern Wielkopolska was analysed. Studies were conducted from May 1992 to October 1993. The 18,995 specimens collected were classified as belonging to 137 species and 17 families. The family Linyphiidae proved the richest in species while Lycosidae was the most abundantly in terms of number of specimens. Zoocenological analysis of spider communities showed their differentiation testifying to differences in the sites studied. The dominants were: 1 Osowo Stare (Site 1: Pardosa palustris, 2 Sycyn Dolny (Site 2: Xerolycosa miniata, P. palustris, Xysticus kochi, 3 Braczewo (Site 3: Erigone dentipalpis, P. palustris. Seasonal changes of dominance of the species at each site were established. A comparison of changes of the species’ dominances in the years 1992 and 1993 disclosed similar values of the individual dominance coefficient at the sites in Osowo Stare and Braczewo. This result indicates the occurrence of the process of stabilization of these biocenoses and a tendency to equilibrium in the environment. The least stable proved to be the site at Sycyn Dolny. Analysis of the seasonal dynamics of epigeic spider communities was also made by determining the mean number of species at each site in the two years of study. The highest number of species was noted in spring. It is interesting to note the appearance of species which are rare or very rare in Poland such as: Lepthyphantes insignis, Ostearius melanopygius, Enoplognatha mordax and Enoplognatha oelandica.

  18. Seasonal variation of ground spiders in a Brazilian Savanna

    Directory of Open Access Journals (Sweden)

    Marina Farcic Mineo

    2010-06-01

    Full Text Available The Brazilian Savanna Ecoregion (Cerrado is one of the richest biomes in the world, with a characteristic highly seasonal climate a dry season between May and September and a rainy season from October through April. Ground-dwelling spiders from three Cerrado phytophysiognomies, "campo cerrado", "cerrado" and "cerrad��o", were sampled using pitfall traps during two years, totaling 111 species and 3,529 individuals. The abundance of individuals and species richness was higher during the wet season. Fifty-eight species were captured exclusively during that period, whereas only nineteen were restricted to the dry season. Only two species were found in all samples. The number of juveniles was higher than the number of adults in all phytophysiognomies and in all species during both seasons. The highest abundance was registered in October and the lowest in April. Overall sex ratio was male-biased in all vegetation types sampled. Distinct climate variables affected the abundance of spiders depending on sex, age and vegetal physiognomy where they were sampled. This study involved the longest sampling of spider abundance and diversity on the ground of a Brazilian Savanna.

  19. A New Limit on CMB Circular Polarization from SPIDER

    Energy Technology Data Exchange (ETDEWEB)

    Nagy, J. M.; Ade, P. A. R.; Amiri, M.; Benton, S. J.; Bergman, A. S.; Bihary, R.; Bock, J. J.; Bond, J. R.; Bryan, S. A.; Chiang, H. C.; Contaldi, C. R.; Doré, O.; Duivenvoorden, A. J.; Eriksen, H. K.; Farhang, M.; Filippini, J. P.; Fissel, L. M.; Fraisse, A. A.; Freese, K.; Galloway, M.; Gambrel, A. E.; Gandilo, N. N.; Ganga, K.; Gudmundsson, J. E.; Halpern, M.; Hartley, J.; Hasselfield, M.; Hilton, G.; Holmes, W.; Hristov, V. V.; Huang, Z.; Irwin, K. D.; Jones, W. C.; Kuo, C. L.; Kermish, Z. D.; Li, S.; Mason, P. V.; Megerian, K.; Moncelsi, L.; Morford, T. A.; Netterfield, C. B.; Nolta, M.; Padilla, I. L.; Racine, B.; Rahlin, A. S.; Reintsema, C.; Ruhl, J. E.; Runyan, M. C.; Ruud, T. M.; Shariff, J. A.; Soler, J. D.; Song, X.; Trangsrud, A.; Tucker, C.; Tucker, R. S.; Turner, A. D.; List, J. F. Van Der; Weber, A. C.; Wehus, I. K.; Wiebe, D. V.; Young, E. Y.

    2017-08-01

    We present a new upper limit on CMB circular polarization from the 2015 flight of SPIDER, a balloon-borne telescope designed to search for $B$-mode linear polarization from cosmic inflation. Although the level of circular polarization in the CMB is predicted to be very small, experimental limits provide a valuable test of the underlying models. By exploiting the non-zero circular-to-linear polarization coupling of the HWP polarization modulators, data from SPIDER's 2015 Antarctic flight provides a constraint on Stokes $V$ at 95 and 150 GHz from $33<\\ell<307$. No other limits exist over this full range of angular scales, and SPIDER improves upon the previous limit by several orders of magnitude, providing 95% C.L. constraints on $\\ell (\\ell+1)C_{\\ell}^{VV}/(2\\pi)$ ranging from 141 $\\mu K ^2$ to 203 $\\mu K ^2$ at 150 GHz for a thermal CMB spectrum. As linear CMB polarization experiments become increasingly sensitive, the techniques described in this paper can be applied to obtain stronger constraints on circular polarization.

  20. Review of the Australian wolf spider genus Venator (Araneae, Lycosidae).

    Science.gov (United States)

    Framenau, Volker W

    2015-09-11

    Species of the Australian wolf spider genus Venator are reviewed including the type species, V. spenceri Hogg, 1900, from south-eastern Australia and V. immansuetus (Simon, 1909) comb. nov., a common species in south-west Western Australia. Venator marginatus Hogg, 1900 is only known from two female specimens and the genital morphology of this species does not conform to the diagnosis of genus as presented here. Therefore V. marginatus is considered incerta sedis. Venator includes medium-sized (9.0-22 mm body length) wolf spiders of overall brownish colouration, and with a black patch covering the anterior three quarters of the venter. They differ from all other wolf spiders in particular by genitalic characters, namely an elevated atrium of the female epigyne that forms a raised edged against the inverted T-shaped median septum. This edge often corresponds to a retrolateral incision on the tegular apophysis of the male pedipalp. The genus is mainly a representative of the Bassian fauna of the Australian continent where it occurs predominantly in dry sclerophyll forests.

  1. Spin physics in semiconductors

    CERN Document Server

    2017-01-01

    This book offers an extensive introduction to the extremely rich and intriguing field of spin-related phenomena in semiconductors. In this second edition, all chapters have been updated to include the latest experimental and theoretical research. Furthermore, it covers the entire field: bulk semiconductors, two-dimensional semiconductor structures, quantum dots, optical and electric effects, spin-related effects, electron-nuclei spin interactions, Spin Hall effect, spin torques, etc. Thanks to its self-contained style, the book is ideally suited for graduate students and researchers new to the field.

  2. Differential predictive power of self report and implicit measures on behavioural and physiological fear responses to spiders

    NARCIS (Netherlands)

    van Bockstaele, B.; Verschuere, B.; Koster, E.H.W.; Tibboel, H.; de Houwer, J.; Crombez, G.

    2011-01-01

    In this study, we investigated to what extent indirect measures predict behavioural and physiological fear responses towards spiders. Implicit attitudes towards spiders were assessed using an implicit association test and attentional bias towards spiders was assessed using a dot probe task and a

  3. Spider-mediated flux of PCBs from contaminated sediments to terrestrial ecosystems and potential risks to arachnivorous birds

    Science.gov (United States)

    Walters, D.M.; Mills, M.A.; Fritz, K.M.; Raikow, D.F.

    2010-01-01

    We investigated aquatic insect utilization and PCB exposure in riparian spiders at the Lake Hartwell Superfund site (Clemson, SC). We sampled sediments, adult chironomids, terrestrial insects, riparian spiders (Tetragnathidae, Araneidae, and Mecynogea lemniscata), and upland spiders (Araneidae) along a sediment contamination gradient. Stable isotopes (?13C, ? 15N) indicated that riparian spiders primarily consumed aquatic insects whereas upland spiders consumed terrestrial insects. PCBs in chironomids (mean 1240 ng/g among sites) were 2 orders of magnitude higher than terrestrial insects (15.2 ng/g), similar to differences between riparian (820?2012 ng/g) and upland spiders (30 ng/g). Riparian spider PCBs were positively correlated with sediment concentrations for all taxa (r2 = 0.44?0.87). We calculated spider-based wildlife values (WVs, the minimum spider PCB concentrations causing physiologically significant doses in consumers) to assess exposure risks for arachnivorous birds. Spider concentrations exceeded WVs for most birds at heavily contaminated sites and were ?14-fold higher for the most sensitive species (chickadee nestlings, Poecile spp.). Spiders are abundant and ubiquitous in riparian habitats, where they depend on aquatic insect prey. These traits, along with the high degree of spatial correlation between spider and sediment concentrations we observed, suggest that they are model indicator species for monitoring contaminated sediment sites and assessing risks associated with contaminant flux into terrestrial ecosystems. ?? This article not subject to U.S. Copyright. Published 2009 by the American Chemical Society.

  4. Untangling spider silk evolution with spidroin terminal domains

    Directory of Open Access Journals (Sweden)

    Garb Jessica E

    2010-08-01

    Full Text Available Abstract Background Spidroins are a unique family of large, structural proteins that make up the bulk of spider silk fibers. Due to the highly variable nature of their repetitive sequences, spidroin evolutionary relationships have principally been determined from their non-repetitive carboxy (C-terminal domains, though they offer limited character data. The few known spidroin amino (N-terminal domains have been difficult to obtain, but potentially contain critical phylogenetic information for reconstructing the diversification of spider silks. Here we used silk gland expression data (ESTs from highly divergent species to evaluate the functional significance and phylogenetic utility of spidroin N-terminal domains. Results We report 11 additional spidroin N-termini found by sequencing ~1,900 silk gland cDNAs from nine spider species that shared a common ancestor > 240 million years ago. In contrast to their hyper-variable repetitive regions, spidroin N-terminal domains have retained striking similarities in sequence identity, predicted secondary structure, and hydrophobicity. Through separate and combined phylogenetic analyses of N-terminal domains and their corresponding C-termini, we find that combined analysis produces the most resolved trees and that N-termini contribute more support and less conflict than the C-termini. These analyses show that paralogs largely group by silk gland type, except for the major ampullate spidroins. Moreover, spidroin structural motifs associated with superior tensile strength arose early in the history of this gene family, whereas a motif conferring greater extensibility convergently evolved in two distantly related paralogs. Conclusions A non-repetitive N-terminal domain appears to be a universal attribute of spidroin proteins, likely retained from the origin of spider silk production. Since this time, spidroin N-termini have maintained several features, consistent with this domain playing a key role in silk

  5. The spider Harpactea sadistica: co-evolution of traumatic insemination and complex female genital morphology in spiders

    Science.gov (United States)

    Řezáč, Milan

    2009-01-01

    The males of invertebrates from a few phyla, including arthropods, have been reported to practise traumatic insemination (TI; i.e. injecting sperm by using the copulatory organ to penetrate the female's body wall). As all previously reported arthropod examples have been insects, there is considerable interest in whether TI might have evolved independently in other arthropods. The research reported here demonstrates the first case of TI in the arthropod subphylum Chelicerata, in particular how the genital morphology and mating behaviour of Harpactea sadistica (Řezáč 2008), a spider from Israel, has become adapted specifically for reproduction based on TI. Males have needle-like intromittent organs and females have atrophied spermathecae. In other spiders, eggs are fertilized simultaneously with oviposition, but the eggs of H. sadistica are fertilized in the ovaries (internal fertilization) and develop as embryos before being laid. Sperm-storage organs of phylogenetically basal groups to H. sadistica provide males with last male sperm priority and allow removal of sperm by males that mate later, suggesting that TI might have evolved as an adaptive strategy to circumvent an unfavourable structure of the sperm-storage organs, allowing the first male to mate with paternity advantage. Understanding the functional significance of TI gives us insight into factors underlying the evolution of the genital and sperm-storage morphology in spiders. PMID:19403531

  6. A web in the patriarchal clan system: tactics of intimate partners in the Japanese sociocultural context.

    Science.gov (United States)

    Yoshihama, Mieko

    2005-10-01

    Only recently has Japanese society come to realize the magnitude of domestic violence as a serious social problem. Using focus group methodology, this study investigated the function and the sociocultural reinforcements of male partner violence. The analysis of the participants' accounts of various types of violence their partners perpetrated, which were accompanied by an elaborate collection of tactics to reinforce the effects of the violence, has led to the conceptualization of partners' violence as a spider web. The Japanese patriarchal clan system and underlying ideology of male superiority fosters the maintenance of this web.

  7. High-toughness silk produced by a transgenic silkworm expressing spider (Araneus ventricosus dragline silk protein.

    Directory of Open Access Journals (Sweden)

    Yoshihiko Kuwana

    Full Text Available Spider dragline silk is a natural fiber that has excellent tensile properties; however, it is difficult to produce artificially as a long, strong fiber. Here, the spider (Araneus ventricosus dragline protein gene was cloned and a transgenic silkworm was generated, that expressed the fusion protein of the fibroin heavy chain and spider dragline protein in cocoon silk. The spider silk protein content ranged from 0.37 to 0.61% w/w (1.4-2.4 mol% native silkworm fibroin. Using a good silk-producing strain, C515, as the transgenic silkworm can make the raw silk from its cocoons for the first time. The tensile characteristics (toughness of the raw silk improved by 53% after the introduction of spider dragline silk protein; the improvement depended on the quantity of the expressed spider dragline protein. To demonstrate the commercial feasibility for machine reeling, weaving, and sewing, we used the transgenic spider silk to weave a vest and scarf; this was the first application of spider silk fibers from transgenic silkworms.

  8. Biased interpretation and memory in children with varying levels of spider fear

    NARCIS (Netherlands)

    Klein, A.M.; Titulaer, G.; Simons, C.; Allart, E.; de Gier, E.; Bögels, S.M.; Becker, E.S.; Rinck, M.

    2014-01-01

    This study investigated multiple cognitive biases in children simultaneously, to investigate whether spider-fearful children display an interpretation bias, a recall bias, and source monitoring errors, and whether these biases are specific for spider-related materials. Furthermore, the independent

  9. In Vitro Evaluation of Spider Silk Meshes as a Potential Biomaterial for Bladder Reconstruction

    NARCIS (Netherlands)

    Steins, A.; Dik, P.; Müller, W.H.; Vervoort, S.J.; Reimers, K.; Kubhier, J.W.; Vogt, P.M.; van Apeldoorn, Aart A.; Coffer, P.J.; Schepers, K.

    2015-01-01

    Reconstruction of the bladder by means of both natural and synthetic materials remains a challenge due to severe adverse effects such as mechanical failure. Here we investigate the application of spider major ampullate gland-derived dragline silk from the Nephila edulis spider, a natural biomaterial

  10. Photoluminescent properties of spider silk coated with Eu-doped nanoceria

    Energy Technology Data Exchange (ETDEWEB)

    Dmitrović, Svetlana, E-mail: svetlana8@vin.bg.ac.rs [University of Belgrade, Vinča Institute of Nuclear Sciences (Serbia); Nikolić, Marko G.; Jelenković, Branislav [University of Belgrade, Institute of Physics (Serbia); Prekajski, Marija [University of Belgrade, Vinča Institute of Nuclear Sciences (Serbia); Rabasović, Mihailo [University of Belgrade, Institute of Physics (Serbia); Zarubica, Aleksandra [University of Niš, Department of Chemistry, Faculty of Science and Mathematics (Serbia); Branković, Goran [University of Belgrade, Institute for Multidisciplinary Research, Department of Material Science (Serbia); Matović, Branko [University of Belgrade, Vinča Institute of Nuclear Sciences (Serbia)

    2017-02-15

    Spider dragline silk was coated with pure as well as Eu-doped ceria nanopowders at the room temperature. The treatment was done by immersion of the spider silk mesh into aqueous solutions of cerium nitrate (Ce(NO{sub 3}){sub 3}) and ammonium hydroxide (NH{sub 4}OH). Depending on the relationship between Ce{sup 3+} ion and ammonium hydroxide concentration, coated fibers exhibited a different thickness. Obtained materials were studied by means of FESEM. It was found that ceria nanoparticles of average size of 3 nm were coated along spider thread. X-ray diffraction (XRD) and selected-area electron diffraction (SAED) confirmed crystal nature of nanoparticle coating of spider silk. By using Williamson-Hall plots, crystallite size and strain were estimated. EDS measurement confirmed the presence of Eu in spider-Eu-doped ceria composite, and according to FTIR analysis, the interaction between CeO2 and spider silk was proposed. The morphology of obtained composite was observed by TEM. The photoluminescence emission spectra of spider silk coated with Eu-doped ceria were measured with two different excitations of 385 and 466 nm. The two-photon excited auto-fluorescence of spider silk coated with Eu-doped ceria was detected using a nonlinear laser scanning microscope. Obtained composite has a potential as a fluorescent labeling material in diverse applications.

  11. High School Students' Attitudes Towards Spiders: A cross-cultural comparison

    Science.gov (United States)

    Prokop, Pavol; Tolarovičová, Andrea; Camerik, Anne M.; Peterková, Viera

    2010-08-01

    Spiders are traditionally considered to be among the least popular of animals. Current evidence suggests that a negative attitude towards spiders could be influenced by both cultural and evolutionary pressures. Some researchers suggest that science education activities could positively influence students' perceptions of spiders. Their evidence is, however, ambivalent. Using a five-point score Likert-type questionnaire in which the items were developed in a similar way to four of Kellert's categories of attitude (scientistic, negativistic, naturalistic, and ecologistic) towards invertebrates, we compared the level of knowledge of and attitudes towards spiders of high school students from two countries, Slovakia (n = 354) and South Africa (n = 382). The students represented different cultures and followed dissimilar science education curricula. Only among the Slovakian students there was a statistically significant but low correlation between knowledge and attitude (r = 0.30). The South African students scored higher in the categories of scientistic, naturalistic, and ecologistic attitudes. Comparison of attitude towards spiders of indigenous Africans from coeducational Catholic schools revealed that South African students have greater fear of spiders than Slovakian students, supporting the biological preparedness hypothesis. This hypothesis predicts a greater fear of spiders in South Africa than in Europe since several South African spiders possess venoms that are dangerous to humans. The results of this study are discussed from science education, cultural, and evolutionary perspectives.

  12. Methods of assembling and disassembling spider and burnable poison rod structures for nuclear reactors

    International Nuclear Information System (INIS)

    Walton, L.A.

    1981-01-01

    A method is described of joining burnable poison rods to the spider arms of a pressurised water power reactor fuel assembly which is proof against the reactor core environment but permits these rods to be removed from the spider simply, swiftly and delicately. (U.K.)

  13. Parasitization of a huntsman spider (Arachnida: Araneae: Sparassidae: Heteropoda venatoria by a mermithid nematode (Nematoda: Mermithidae

    Directory of Open Access Journals (Sweden)

    Sachin P. Ranade

    2016-11-01

    Full Text Available The emergence of a mermithid worm from a huntsman spider Heteropoda venatoria was witnessed at Buxa Tiger Reserve, West Bengal.  It appears to be a first record of the spider family Sparassidae serving as a host for a member of the family Mermithidae. 

  14. Contamination vs. harm-relevant outcome expectancies and covariation bias in spider phobia

    NARCIS (Netherlands)

    de Jong, Peter J.; Peters, Madelon L.

    There is increasing evidence that spiders are not feared because of harmful outcome expectancies but because of disgust and contamination-relevant outcome expectancies. This study investigated the relative strength of contamination- and harm-relevant UCS expectancies and covariation bias in spider

  15. Differences among plant species in acceptance by the spider mite Tetranychus urticae Koch

    NARCIS (Netherlands)

    Boom, van den C.E.M.; Beek, van T.A.; Dicke, M.

    2003-01-01

    The spider mite Tetranychus urticae Koch has a broad range of host plants. However, the spider mite does not accept all plants to the same degree because of differences in nutritive and toxic constituents. Other factors, such as the induction of secondary metabolites, the morphology of a leaf

  16. fMRI neurofeedback facilitates anxiety regulation in females with spider phobia

    NARCIS (Netherlands)

    Zilverstand, Anna; Sorger, Bettina; Sarkheil, Pegah; Goebel, R.

    2015-01-01

    BACKGROUND: Spider phobics show an exaggerated fear response when encountering spiders. This fear response is aggravated by negative and irrational beliefs about the feared object. Cognitive reappraisal can target these beliefs, and therefore has a fear regulating effect. The presented study

  17. The spider anxiety and disgust screening for children: Reliability and validity of a screening for children

    NARCIS (Netherlands)

    Klein, A.M.; Niekerk, R.E. van; Baartmans, J.M.D.; Rinck, M.; Becker, E.S.

    2017-01-01

    Objectives: Specific fears, such as fear of spiders, are often used as a model for studying the development of other fears because several studies suggest that the underlying processes of fear are similar. For the screening of spider fear in children, a good, fast, and reliable screening instrument

  18. Utility Assessment Report for SPIDERS Phase 2: Ft. Carson (Rev 1.0)

    Energy Technology Data Exchange (ETDEWEB)

    Barr, Jonathan L. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Tuffner, Francis K. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Hadley, Mark D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Schneider, Kevin P. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2014-01-01

    This document contains the Utility Assessment Report (UAR) for the Phase 2 operational Demonstration (OD) of the Smart Power Infrastructure Demonstration for Energy Reliability and Security (SPIDERS) Joint Capability Technology Demonstration (JCTD). The UAR for Phase 2 shows that the SPIDERS system was able to meet the requirements of the Implementation Directive at Ft. Carson.

  19. Postharvest fumigation of California table grapes with ozone to control Western black widow spider (Araneae: Theridiidae)

    Science.gov (United States)

    Ozone fumigations were evaluated for postharvest control of Western black widow spider (BWS), Latrodectus hesperus (Chamberlin and Ivie), in fresh table grapes destined for export from California USA. Mature adult female black widow spiders were contained in separate gas-permeable cages within a flo...

  20. Species status and conservation issues of New Zealand's endemic Latrodectus spider species (Araneae: Theridiidae)

    DEFF Research Database (Denmark)

    Vink, Cor J; Sirvid, Phillip J; Malumbres-Olarte, Jagoba

    2008-01-01

    New Zealand has two endemic widow spiders, Latrodectus katipo Powell, 1871 and L. atritus Urquhart, 1890. Both species face many conservation threats and are actively managed. The species status of the Latrodectus spiders of New Zealand was assessed using molecular (COI, ITS1, ITS2) and morpholog...

  1. Neural correlation of successful cognitive behaviour therapy for spider phobia: a magnetoencephalography study.

    Science.gov (United States)

    Wright, Barry; Alderson-Day, Ben; Prendergast, Garreth; Kennedy, Juliette; Bennett, Sophie; Docherty, Mary; Whitton, Clare; Manea, Laura; Gouws, Andre; Tomlinson, Heather; Green, Gary

    2013-12-30

    Cognitive behavioural therapy (CBT) can be an effective treatment for spider phobia, but the underlying neural correlates of therapeutic change are yet to be specified. The present study used magnetoencephalography (MEG) to study responses within the first half second, to phobogenic stimuli in a group of individuals with spider phobia prior to treatment (n=12) and then in nine of them following successful CBT (where they could touch and manage live large common house spiders) at least 9 months later. We also compared responses to a group of age-matched healthy control participants (n=11). Participants viewed static photographs of real spiders, other fear-inducing images (e.g. snakes, sharks) and neutral stimuli (e.g. kittens). Beamforming methods were used to localise sources of significant power changes in response to stimuli. Prior to treatment, participants with spider phobia showed a significant maximum response in the right frontal pole when viewing images of real spiders specifically. No significant frontal response was observed for either control participants or participants with spider phobia post-treatment. In addition, participants' subjective ratings of spider stimuli significantly predicted peak responses in right frontal regions. The implications for understanding brain-based effects of cognitive therapies are discussed. © 2013 Published by Elsevier Ireland Ltd.

  2. Species richness and composition assessment of spiders in a Mediterranean scrubland

    DEFF Research Database (Denmark)

    Bondoso Cardoso, Pedro Miguel; Henriques, Sérgio S.; Gaspar, Clara

    2009-01-01

    Intensive fieldwork has been undertaken in Portugal in order to develop a standardized and optimized sampling protocol for Mediterranean spiders. The present study had the objectives of testing the use of semi-quantitative sampling for obtaining an exhaustive species richness assessment of spider...

  3. Red-back spider (Latrodectus mactans hasselti) envenomation in a neonate.

    Science.gov (United States)

    Byrne, G C; Pemberton, P J

    A case of red-back spider (Latrodectus mactans hasselti) envenomation in a neonate is presented. The signs of envenomation in a neonate are discussed, together with the dose of antivenom necessary for the successful treatment of envenomation. In episodes of untractable crying in neonates, the possibility that the baby has been bitten by a red-back spider should be considered.

  4. Salivary proteins of spider mites suppress defenses in Nicotiana benthamiana and promote mite reproduction

    NARCIS (Netherlands)

    Villarroel, C.A.; Jonckheere, W.; Alba Cano, J.M.; Glas, J.J.; Dermauw, W.; Haring, M.A.; Van Leeuwen, T.; Schuurink, R.C.; Kant, M.R.

    2016-01-01

    Spider mites (Tetranychidae sp.) are widely occurring arthropod pests on cultivated plants. Feeding by the two-spotted spider mite T. urticae, a generalist herbivore, induces a defense response in plants that mainly depends on the phytohormones jasmonic acid and salicylic acid (SA). On tomato

  5. The path to the nest of spiders The path to the nest of spiders

    Directory of Open Access Journals (Sweden)

    Eliane Luz Bayer

    2008-04-01

    Full Text Available Italo Calvino writes in his preface to The Path to the Nest of Spiders that the novel answers to the "ripeness of the time" since ht wrote it after wartime, a period when everyone had a tale to tell. He tells us that this is a story in which iobody is a hero and nobody has the class consciousness necessary to unify them in the struggle. Calvino acknowledges that it was difficult to conciliate his experiences with the postwar literary movement which he calls Neo-expresSionism, a term which, he thinks, describes better Italian Neo-realism. This is a book with a full realistic depictior of the incongruousness of the whole situation, showing rumen beings driven by loneliness, aggressiveness, unfulfilment and failure to meet, their nerves frayed by the War. It reveals human beings in their weaknesses, subjected to deterministic fates changing roles according to circumstance. Partisans shift to the Nazi side and inform on their f rmer allies and vice-versa, being later chased in revenge. The novel has as its setting Italy under Fascism and unde German occupation, the Italian people being divided betw en the fascists of the "Black Brigade" and the "Partisa4s" who belonged to the Resistance. Although this is a pOlitical book, it has universal appeal. At the same time that it livens up historical facts about the period, it moves our feelings. Calvino's book is about World War II as it is viewed and felt by a small outcast, Pin, who makes considerable efforts to be accepted and understood by adults. In his daily life Pinsuffers the consequences Of the war. His aggressive disposition reflects the environment which he has been brought up in: since he was born, his country has been at war. Besides that, his only sister is a whore, whom he hates and despises. Italo Calvino writes in his preface to The Path to the Nest of Spiders that the novel answers to the "ripeness of the time" since ht wrote it after wartime, a period when everyone had a tale to tell

  6. Muon spin relaxation in random spin systems

    International Nuclear Information System (INIS)

    Toshimitsu Yamazaki

    1981-01-01

    The longitudinal relaxation function Gsub(z)(t) of the positive muon can reflect dynamical characters of local field in a unique way even when the correlation time is longer than the Larmor period of local field. This method has been applied to studies of spin dynamics in spin glass systems, revealing sharp but continuous temperature dependence of the correlation time. Its principle and applications are reviewed. (author)

  7. The time course of location-avoidance learning in fear of spiders.

    Science.gov (United States)

    Rinck, Mike; Koene, Marieke; Telli, Sibel; Moerman-van den Brink, Wiltine; Verhoeven, Barbara; Becker, Eni S

    2016-01-01

    Two experiments were designed to study the time course of avoidance learning in spider fearfuls (SFs) under controlled experimental conditions. To achieve this, we employed an immersive virtual environment (IVE): While walking freely through a virtual art museum to search for specific paintings, the participants were exposed to virtual spiders. Unbeknown to the participants, only two of four museum rooms contained spiders, allowing for avoidance learning. Indeed, the more SF the participants were, the faster they learned to avoid the rooms that contained spiders (Experiment. 1), and within the first six trials, high fearfuls already developed a preference for starting their search task in rooms without spiders (Experiment 2). These results illustrate the time course of avoidance learning in SFs, and they speak to the usefulness of IVEs in fundamental anxiety research.

  8. Community structure of spiders in coastal habitats of a Mediterranean delta region (Nestos Delta, NE Greece

    Directory of Open Access Journals (Sweden)

    S. Buchholz

    2009-01-01

    Full Text Available (pp 101-115Habitat zonation and ecology of spider assemblages have been poorly studied in Mediterranean ecosystems. A first analysis of spider assemblages in coastal habitats in the east Mediterranean area is presented. The study area is the 250 km² Nestos Delta, located in East Macedonia in the North-East of Greece. Spiders were caught in pitfall traps at 17 sites from the beginning of April to the end of June 2004. Nonparametric estimators were used to determine species richness and alpha diversity. Ordination analysis (redundancy analysis indicated four clearly separable spider species groups (salt meadows, dunes, mea-dows and floodplain forests, along a soil salinity and moisture gradient. Based on these results we discuss the habitat preferences of these spiders and include the first ecological data on several species.

  9. Association of spiders and lichen on Robben Island, South Africa: a case report

    Directory of Open Access Journals (Sweden)

    A. Mukherjee

    2010-04-01

    Full Text Available The present study is a firstrecord of spider occurrence on Robben Island, South Africa. Some habitats were rich in lichens. As we know, lichens enhance wildlife habitat in less direct ways. The objective of the study was to examine the potential importance of lichens in enriching spider diversity and abundance. A total of 260 spiders (170 from lichens and 90 from bush were collected following the visual search method over one year. Seasonal trends in overall species richness and abundance indicated that the relative density of spiders was greater in lichens than in bushes. The result suggests that habitat structure, such as branch size and epiphytic lichen abundance, can be an explanation for the greater number of spiders in lichen-rich patches of the island.

  10. Semantic Web

    Directory of Open Access Journals (Sweden)

    Anna Lamandini

    2011-06-01

    Full Text Available The semantic Web is a technology at the service of knowledge which is aimed at accessibility and the sharing of content; facilitating interoperability between different systems and as such is one of the nine key technological pillars of TIC (technologies for information and communication within the third theme, programme specific cooperation of the seventh programme framework for research and development (7°PQRS, 2007-2013. As a system it seeks to overcome overload or excess of irrelevant information in Internet, in order to facilitate specific or pertinent research. It is an extension of the existing Web in which the aim is for cooperation between and the computer and people (the dream of Sir Tim Berners –Lee where machines can give more support to people when integrating and elaborating data in order to obtain inferences and a global sharing of data. It is a technology that is able to favour the development of a “data web” in other words the creation of a space in both sets of interconnected and shared data (Linked Data which allows users to link different types of data coming from different sources. It is a technology that will have great effect on everyday life since it will permit the planning of “intelligent applications” in various sectors such as education and training, research, the business world, public information, tourism, health, and e-government. It is an innovative technology that activates a social transformation (socio-semantic Web on a world level since it redefines the cognitive universe of users and enables the sharing not only of information but of significance (collective and connected intelligence.

  11. Usare WebDewey

    OpenAIRE

    Baldi, Paolo

    2016-01-01

    This presentation shows how to use the WebDewey tool. Features of WebDewey. Italian WebDewey compared with American WebDewey. Querying Italian WebDewey. Italian WebDewey and MARC21. Italian WebDewey and UNIMARC. Numbers, captions, "equivalente verbale": Dewey decimal classification in Italian catalogues. Italian WebDewey and Nuovo soggettario. Italian WebDewey and LCSH. Italian WebDewey compared with printed version of Italian Dewey Classification (22. edition): advantages and disadvantages o...

  12. Adaptation of the spiders to the environment: the case of some Chilean species

    Directory of Open Access Journals (Sweden)

    Mauricio eCanals

    2015-08-01

    Full Text Available Spiders are small arthropods that have colonized terrestrial environments. These impose three main problems: i terrestrial habitats have large fluctuations in temperature and humidity; ii the internal concentration of water is higher than the external environment in spiders, which exposes them continually to water loss; and iii their small body size determines a large surface / volume ratio, affecting energy exchange and influencing the life strategy. In this review we focus on body design, energetic, thermal selection, and water balance characteristics of some spider species present in Chile and correlate our results with ecological and behavioral information. Preferred temperatures and critical temperatures of Chilean spiders vary among species and individuals and may be adjusted by phenotypic plasticity. For example in the mygalomorph high-altitude spider Paraphysa parvula the preferred temperature is similar to that of the lowland spider Grammostola rosea; but while P. parvula shows phenotypic plasticity, G. rosea does not. The araneomorph spiders Loxosceles laeta and Scytodes globula have greater daily variations in preferred temperatures at twilight and during the night, which are set to the nocturnal activity rhythms of these species. They also present acclimation of the minimum critical temperatures. Dysdera crocata has a low preferred temperature adjusted to its favorite prey, the woodlouse. Spider metabolic rate is low compared to other arthropods, which may be associated with its sit and wait predatory strategy particularly in primitive hunter and weavers. In mygalomorph spiders the respiratory system is highly optimized with high oxygen conductance, for example G. rosea needs only a difference of 0.12 to 0.16 kPa in the oxygen partial pressure across the air-hemolymph barrier to satisfy its resting oxygen consumption demands. Water loss is a significant stress for spiders. Paraphysa parvula shows an evaporative water loss ten times

  13. The susceptibilities in the spin-S Ising model

    International Nuclear Information System (INIS)

    Ainane, A.; Saber, M.

    1995-08-01

    The susceptibilities of the spin-S Ising model are evaluated using the effective field theory introduced by Tucker et al. for studying general spin-S Ising model. The susceptibilities are studied for all spin values from S = 1/2 to S = 5/2. (author). 12 refs, 4 figs

  14. Higher spin gauge theories

    CERN Document Server

    Henneaux, Marc; Vasiliev, Mikhail A

    2017-01-01

    Symmetries play a fundamental role in physics. Non-Abelian gauge symmetries are the symmetries behind theories for massless spin-1 particles, while the reparametrization symmetry is behind Einstein's gravity theory for massless spin-2 particles. In supersymmetric theories these particles can be connected also to massless fermionic particles. Does Nature stop at spin-2 or can there also be massless higher spin theories. In the past strong indications have been given that such theories do not exist. However, in recent times ways to evade those constraints have been found and higher spin gauge theories have been constructed. With the advent of the AdS/CFT duality correspondence even stronger indications have been given that higher spin gauge theories play an important role in fundamental physics. All these issues were discussed at an international workshop in Singapore in November 2015 where the leading scientists in the field participated. This volume presents an up-to-date, detailed overview of the theories i...

  15. Spin caloritronics in graphene

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Angsula; Frota, H. O. [Department of Physics, Federal University of Amazonas, Av. Rodrigo Octavio 3000-Japiim, 69077-000 Manaus, AM (Brazil)

    2015-06-14

    Spin caloritronics, the combination of spintronics with thermoelectrics, exploiting both the intrinsic spin of the electron and its associated magnetic moment in addition to its fundamental electronic charge and temperature, is an emerging technology mainly in the development of low-power-consumption technology. In this work, we study the thermoelectric properties of a Rashba dot attached to two single layer/bilayer graphene sheets as leads. The temperature difference on the two graphene leads induces a spin current, which depends on the temperature and chemical potential. We demonstrate that the Rashba dot behaves as a spin filter for selected values of the chemical potential and is able to filter electrons by their spin orientation. The spin thermopower has also been studied where the effects of the chemical potential, temperature, and also the Rashba term have been observed.

  16. Spin caloritronics in graphene

    Science.gov (United States)

    Frota, H. O.; Ghosh, Angsula

    2014-08-01

    Spin caloritronics, the combination of spintronics with thermoelectrics, based on spin and heat transport has attracted a great attention mainly in the development of low-power-consumption technology. In this work we study the thermoelectric properties of a quantum dot attached to two single layer graphene sheets as leads. The temperature difference on the two graphene leads induces a spin current which depends on the temperature and chemical potential. We demonstrate that the quantum dot behaves as a spin filter for selected values of the chemical potential and is able to filter electrons by their spin orientation. The spin thermopower has also been studied where the effects of the chemical potential, temperature and also the Coulomb repulsion due to the double occupancy of an energy level have been observed.

  17. Responsive web design workflow

    OpenAIRE

    LAAK, TIMO

    2013-01-01

    Responsive Web Design Workflow is a literature review about Responsive Web Design, a web standards based modern web design paradigm. The goals of this research were to define what responsive web design is, determine its importance in building modern websites and describe a workflow for responsive web design projects. Responsive web design is a paradigm to create adaptive websites, which respond to the properties of the media that is used to render them. The three key elements of responsi...

  18. Whaling into a spider web? The multiple international restraints to states` sovereignty / Enzo Cannizzaro

    Index Scriptorium Estoniae

    Cannizzaro, Enzo

    2016-01-01

    Vaalapüügist Antarktika vetes ja vastavast keerulisest seadusandlusest ning piirangutest rahvusvahelise õiguse kontekstis; Euroopa Kohtu lahendist (31.03.2014). Samal teemal ka artiklid lk. 1027-1069

  19. Revision of the funnel-web spider genus Novalena (Araneae: Agelenidae).

    Science.gov (United States)

    Maya-Morales, Julieta; Jiménez, María Luisa

    2017-05-05

    The Western Hemisphere genus Novalena Chamberlin & Ivie 1942 (Araneae: Agelenidae) is revised. The genus now includes a total of 53 species, of which 40 are new species from USA, Mexico, Guatemala, and Costa Rica: N. ajusco sp. nov. (♀), N. alamo sp. nov. (♂), N. alvarezi sp. nov. (♀), N. atzimbo sp. nov. (♀), N. bosencheve sp. nov. (♂), N. chamberlini sp. nov. (♂ ♀), N. cieneguilla sp. nov. (♀), N. cintalapa sp. nov. (♂ ♀), N. clara sp. nov. (♂ ♀), N. comaltepec sp. nov. (♀), N. creel sp. nov. (♂ ♀), N. dentata sp. nov. (♂ ♀), N. divisadero sp. nov. (♀), N. durango sp. nov. (♀), N. franckei sp. nov. (♂ ♀), N. garnica sp. nov. (♂ ♀), N. gibarrai sp. nov. (♂ ♀), N. irazu sp. nov. (♀), N. iviei sp. nov. (♂), N. ixtlan sp. nov. (♂), N. jiquilpan sp. nov. (♀), N. leonensis sp. nov. (♂ ♀), N. mexiquensis sp. nov. (♂ ♀), N. oaxaca sp. nov. (♂ ♀), N. paricutin sp. nov. (♀), N. perote sp. nov. (♂ ♀), N. plata sp. nov. (♀), N. poncei sp. nov. (♂ ♀), N. popoca sp. nov. (♀), N. prieta sp. nov. (♀), N. puebla sp. nov. (♂ ♀), N. punta sp. nov. (♂ ♀), N. rothi sp. nov. (♂ ♀), N. saltoensis sp. nov. (♀), N. sinaloa sp. nov. (♀), N. tacana sp. nov. (♂ ♀), N. triunfo sp. nov. (♀), N. valdezi sp. nov. (♂ ♀), N. victoria sp. nov. (♀), and N. volcanes sp. nov. (♀). Nine are previously described species: N. annamae (Gertsch & Davis 1940), N. attenuata (F.O. Pickard-Cambridge 1902), N. bipartita (Kraus 1955), N. calavera Chamberlin & Ivie 1942, N. costata (F.O. Pickard-Cambridge 1902), N. laticava (Kraus 1955), N. orizaba (Banks 1898), N. shlomitae (García-Villafuerte 2009), and N. simplex (F.O. Pickard-Cambridge 1902). Four new synonyms are proposed: N. pina Chamberlin & Ivie 1942 = N. intermedia (Chamberlin & Gertsch 1930); N. idahoana (Gertsch 1934) and N. wawona Chamberlin & Ivie 1942 = N. lutzi (Gertsch 1933); N. tolucana (Gertsch & Davis 1940) = N. approximata (Gertsch & Ivie 1936). One species is transferred from Melpomene back to Novalena: N. bipunctata Roth 1967 stat. rev. One species is transferred to Hoffmannilena Maya-Morales & Jiménez 2016: H. nova (O. Pickard-Cambridge 1896) comb. nov.

  20. Antibacterial activity of venom from funnel web spider Agelena labyrinthica (Araneae: Agelenidae

    Directory of Open Access Journals (Sweden)

    M Benli

    2008-01-01

    Full Text Available Since the number of microorganisms that are resistant to antibiotics has been increasing steadily, the need for combating these pathogens requires new pharmaceutical agents. To produce these substances, new models have been developed in recent decades. In our study, the venom of Agelena labyrinthica (Clerck, 1757 (Araneae: Agelenidae was tested against ten bacterial strains, specifically, testing 1/100, 1/10 and 1/1 fractions of diluted venom against these bacteria. While the 1/100 dilution was successful in only one of ten bacterial strains, the 1/10 and the 1/1 were effective on six of ten bacterial strains. The most effective results, among these three different concentrations, were observed on Bacillus subtilis. The other five strains that were also sensitive to the dilutions showed similar inhibition zones. Morphological alterations on bacterial cells and comparison with normal cells were accomplished by scanning electron microscopy (SEM. The venom-treated cells, due to their loss of cytoplasm, shrank and presented cell wall depression.

  1. The spider-web of company competencies: The role of product development

    DEFF Research Database (Denmark)

    Harmsen, Hanne; Bove, Karsten; Grunert, Klaus G.

    This paper examines the role of product development in relation to other key competencies like, eg, production management, sale scompetencies and company image. Based on a representative study of Danish production companies we examine how product development influences overall company success...

  2. NPR1: the spider in the web of induced resistance signaling pathways

    NARCIS (Netherlands)

    Pieterse, C.M.J.; Loon, L.C. van

    2004-01-01

    The plant hormones salicylic acid (SA), jasmonic acid (JA), and ethylene (ET) are major players in the regulation of signaling networks that are involved in induced defense responses against pathogens and insects. During the past two years, significant progress has been made in understanding the

  3. Constructing a multidimensional free energy surface like a spider weaving a web.

    Science.gov (United States)

    Chen, Changjun

    2017-10-15

    Complete free energy surface in the collective variable space provides important information of the reaction mechanisms of the molecules. But, sufficient sampling in the collective variable space is not easy. The space expands quickly with the number of the collective variables. To solve the problem, many methods utilize artificial biasing potentials to flatten out the original free energy surface of the molecule in the simulation. Their performances are sensitive to the definitions of the biasing potentials. Fast-growing biasing potential accelerates the sampling speed but decreases the accuracy of the free energy result. Slow-growing biasing potential gives an optimized result but needs more simulation time. In this article, we propose an alternative method. It adds the biasing potential to a representative point of the molecule in the collective variable space to improve the conformational sampling. And the free energy surface is calculated from the free energy gradient in the constrained simulation, not given by the negative of the biasing potential as previous methods. So the presented method does not require the biasing potential to remove all the barriers and basins on the free energy surface exactly. Practical applications show that the method in this work is able to produce the accurate free energy surfaces for different molecules in a short time period. The free energy errors are small in the cases of various biasing potentials. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  4. The energy sector abroad. Part 12. The Czech Republic. Spider in the European natural gas web

    International Nuclear Information System (INIS)

    Holwerda, B.

    1998-01-01

    The natural gas industry in the Czech Republic is one of the oldest in Europe. In the past, natural gas has played a modest role in the Czech energy supply: coal and town gas from coal and lignite were the major energy sources. However, more and more use is made of natural gas, imported from Russia (Gazprom) and Norway. Besides, the Czech natural gas distribution, transportation and storage system occupies a key position in the Central-European natural gas network

  5. Spin and Maximal Acceleration

    Directory of Open Access Journals (Sweden)

    Giorgio Papini

    2017-12-01

    Full Text Available We study the spin current tensor of a Dirac particle at accelerations close to the upper limit introduced by Caianiello. Continual interchange between particle spin and angular momentum is possible only when the acceleration is time-dependent. This represents a stringent limit on the effect that maximal acceleration may have on spin physics in astrophysical applications. We also investigate some dynamical consequences of maximal acceleration.

  6. Spin Hall effect devices

    Czech Academy of Sciences Publication Activity Database

    Jungwirth, Tomáš; Wunderlich, Joerg; Olejník, Kamil

    2012-01-01

    Roč. 11, č. 5 (2012), s. 382-390 ISSN 1476-1122 EU Projects: European Commission(XE) 268066 - 0MSPIN; European Commission(XE) 215368 - SemiSpinNet Grant - others:AV ČR(CZ) AP0801 Program:Akademická prémie - Praemium Academiae Institutional research plan: CEZ:AV0Z10100521 Keywords : spin Hall effect * spintronics * spin transistor Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 35.749, year: 2012

  7. Spin coating apparatus

    Science.gov (United States)

    Torczynski, John R.

    2000-01-01

    A spin coating apparatus requires less cleanroom air flow than prior spin coating apparatus to minimize cleanroom contamination. A shaped exhaust duct from the spin coater maintains process quality while requiring reduced cleanroom air flow. The exhaust duct can decrease in cross section as it extends from the wafer, minimizing eddy formation. The exhaust duct can conform to entrainment streamlines to minimize eddy formation and reduce interprocess contamination at minimal cleanroom air flow rates.

  8. A controllable spin prism

    International Nuclear Information System (INIS)

    Hakioglu, T

    2009-01-01

    Based on Khodas et al (2004 Phys. Rev. Lett. 92 086602), we propose a device acting like a controllable prism for an incident spin. The device is a large quantum well where Rashba and Dresselhaus spin-orbit interactions are present and controlled by the plunger gate potential, the electric field and the barrier height. A totally destructive interference can be manipulated externally between the Rashba and Dresselhaus couplings. The spin-dependent transmission/reflection amplitudes are calculated as the control parameters are changed. The device operates as a spin prism/converter/filter in different regimes and may stimulate research in promising directions in spintronics in analogy with linear optics.

  9. Quantum spin Hall phases

    International Nuclear Information System (INIS)

    Murakami, Shuichi

    2009-01-01

    We review our recent theoretical works on the quantum spin Hall effect. First we compare edge states in various 2D systems, and see whether they are robust or fragile against perturbations. Through the comparisons we see the robust nature of edge states in 2D quantum spin Hall phases. We see how it is protected by the Z 2 topological number, and reveal the nature of the Z 2 topological number by studying the phase transition between the quantum spin Hall and insulator phases. We also review our theoretical proposal of the ultrathin bismuth film as a candidate to the 2D quantum spin Hall system. (author)

  10. PREFACE: Spin Electronics

    Science.gov (United States)

    Dieny, B.; Sousa, R.; Prejbeanu, L.

    2007-04-01

    Conventional electronics has in the past ignored the spin on the electron, however things began to change in 1988 with the discovery of giant magnetoresistance in metallic thin film stacks which led to the development of a new research area, so called spin-electronics. In the last 10 years, spin-electronics has achieved a number of breakthroughs from the point of view of both basic science and application. Materials research has led to several major discoveries: very large tunnel magnetoresistance effects in tunnel junctions with crystalline barriers due to a new spin-filtering mechanism associated with the spin-dependent symmetry of the electron wave functions new magnetic tunnelling barriers leading to spin-dependent tunnelling barrier heights and acting as spin-filters magnetic semiconductors with increasingly high ordering temperature. New phenomena have been predicted and observed: the possibility of acting on the magnetization of a magnetic nanostructure with a spin-polarized current. This effect, due to a transfer of angular momentum between the spin polarized conduction electrons and the local magnetization, can be viewed as the reciprocal of giant or tunnel magnetoresistance. It can be used to switch the magnetization of a magnetic nanostructure or to generate steady magnetic excitations in the system. the possibility of generating and manipulating spin current without charge current by creating non-equilibrium local accumulation of spin up or spin down electrons. The range of applications of spin electronics materials and phenomena is expanding: the first devices based on giant magnetoresistance were the magnetoresistive read-heads for computer disk drives. These heads, introduced in 1998 with current-in plane spin-valves, have evolved towards low resistance tunnel magnetoresistice heads in 2005. Besides magnetic recording technology, these very sensitive magnetoresistive sensors are finding applications in other areas, in particular in biology. magnetic

  11. Local Noncollinear Spin Analysis.

    Science.gov (United States)

    Abate, Bayileyegn A; Joshi, Rajendra P; Peralta, Juan E

    2017-12-12

    In this work, we generalize the local spin analysis of Clark and Davidson [J. Chem. Phys. 2001 115 (16), 7382] for the partitioning of the expectation value of the molecular spin square operator, ⟨Ŝ 2 ⟩, into atomic contributions, ⟨Ŝ A ·Ŝ B ⟩, to the noncollinear spin case in the framework of density functional theory (DFT). We derive the working equations, and we show applications to the analysis of the noncollinear spin solutions of typical spin-frustrated systems and to the calculation of magnetic exchange couplings. In the former case, we employ the triangular H 3 He 3 test molecule and a Mn 3 complex to show that the local spin analysis provides additional information that complements the standard one-particle spin population analysis. For the calculation of magnetic exchange couplings, J AB , we employ the local spin partitioning to extract ⟨Ŝ A ·Ŝ B ⟩ as a function of the interatomic spin orientation given by the angle θ. This, combined with the dependence of the electronic energy with θ, provides a methodology to extract J AB from DFT calculations that, in contrast to conventional energy differences based methods, does not require the use of ad hoc S A and S B values.

  12. Spin glasses (II)

    International Nuclear Information System (INIS)

    Fischer, K.H.

    1985-01-01

    Experimental results of spin glass studies are reviewed and related to existing theories. Investigations of spin glasses are concentrated on atomic structure, metallurgical treatment, and high-temperature susceptibility of alloys, on magnetic properties at low temperature and near the freezing temperature, on anisotropy behaviour measured by ESR, NMR and torque, on specific heat, Moessbauer effect, neutron scattering and muon-spin depolarization experiments, ultrasound and transport properties. Some new theories of spin glasses are discussed which have been developed since Part I appeared

  13. Fossil evidence for spin alignment of SDSS galaxies in filaments

    NARCIS (Netherlands)

    Jones, Bernard J.T.; Weygaert, Rien van de; Arag´on-Calvo, Miguel A.

    2010-01-01

    We search for and find fossil evidence that the distribution of the spin axes of galaxies in cosmic web filaments relative to their host filaments are not randomly distributed. This would indicate that the action of large scale tidal torques effected the alignments of galaxies located in cosmic

  14. Spin alignment of dark matter haloes in filaments and walls

    NARCIS (Netherlands)

    Aragón-Calvo, M. A.; Weygaert, R. van de; Jones, B. J. T.; Hulst, T. van der

    2006-01-01

    Abstract: The MMF technique is used to segment the cosmic web as seen in a cosmological N-body simulation into wall-like and filament-like structures. We find that the spins and shapes of dark matter haloes are significantly correlated with each other and with the orientation of their host

  15. Spin alignment of dark matter halos in filaments and walls

    NARCIS (Netherlands)

    Aragon-Calvo, Miguel A.; van de Weygaert, Rien; Jones, Bernard J. T.; van der Hulst, J. M.

    2007-01-01

    The MMF technique is used to segment the cosmic web as seen in a cosmological N-body simulation into wall-like and filament-like structures. We find that the spins and shapes of dark matter halos are significantly correlated with each other and with the orientation of their host structures. The

  16. SPIDERS (ARANEI IN HEPRETOBIONT MESOFAUNA OF THE NORTHWEST CAUCASUS

    Directory of Open Access Journals (Sweden)

    A. V. Ponomarev

    2014-01-01

    Full Text Available Abstract. Aim. We discussed in previous work a herpetobiont fauna of arachnids (Arachnida from the isolated yewboxwood wood, located in the Caucasian State Biosphere Reserve, 20 km near Sochi (Ponomarev, Chumachenko, 2007. The aim of the paper is to summarize available data about herpetobiont araneofauna of the Northwest Caucasus. Location. Republic of Adygea, Russia.Methods. Material was collected in 2009 on north macroslope of Main Caucasian Ridge within the territory of the Caucasian State Biosphere Reserve between 1000–1820 m. The following plant communities are studied: beech-silver fir (assotiation Abieti-Fagetion orientalis Korotkov et Belonovskaya 1987, maple forest (assotiation Petasito albae-Abietetum nordmannianae subassotiation Aceretosum trautvetteri Francuzov 2006, subalpine meadow (assotiation Poa longifolii – Calamagrostietum arundinaceae Semagina, 1992. Soil traps were used for collection of spiders.Results and main conclusions. During the period of study 100 species of spiders from 19 families are registered. Most diverse araneofauna of subalpine meadows includs 54 species belonging to 14 families. The least diverse araneofauna is in maple forest (24 species of 7 families. In beech-silver fir includes 45 species of 16 families of spiders. Only 3 species (Pireneitega ovtchinnikovi, Cybaeus abchasicus, Tenuiphantes mengei were found in all surveyed habitats. These 3 species clearly tend to forest habitats. Herpetobiont araneofauna of the Northwest Caucasus characterized by high taxonomic diversity with clear predominance of representatives of the family Linyphiidae. Specificity of araneofauna in different types of plant communities is high.

  17. Spider monkey, Muriqui and Woolly monkey relationships revisited.

    Science.gov (United States)

    de Lima, Margarida Maria Celeira; Sampaio, Iracilda; Vieira, Ricardo dos Santos; Schneider, Horacio

    2007-01-01

    The taxonomic relationships among the four genera of the Atelidae family, Alouatta (Howler), Ateles (Spider), Lagothrix (Woolly) and Brachyteles (Muriqui), have been the subject of great debate. In general, almost all authors agree with the assignment of Howler monkeys as the basal genus, either in its own tribe Alouattini or in the subfamily Alouattinae, but they disagree on the associations among the other members of the family. Muriquis have been grouped with Spider monkeys based on the fact that they share various behavioral and morphological characteristics. Cladistic analyses using morphological, biochemical, karyotype and behavioral characteristics depicted a phylogenetic tree that places Howler as the basal genus and the remaining genera in an unresolved politomy. More recent studies using molecular data have suggested that Muriqui and Woolly monkeys are sister groups. However, a recent study based on nuclear and mtDNA argued that politomy is what best represents the relationships among Spider, Woolly and Muriqui. To contribute to this debate we have added new data from two nuclear genes, Transferrin and von Willebrand Factor, and using an alignment of 17,997 bp we demonstrate that a total analysis strongly supports the Muriqui-Woolly clade. A gene-to-gene approach showed that four of the eight nuclear genes provide support for the Muriqui-Woolly clade, two strongly and two moderately, while none of the eight genes provide support for any alternative arrangement. The mitochondrial genes were not able to resolve the politomy. A possible reason for the difficulty in resolving atelid relationships may be the short period of time separating each cladogenetic event in the evolutionary process that shaped this family.

  18. Male mating tactics in spider monkeys: sneaking to compete.

    Science.gov (United States)

    Gibson, K Nicole

    2010-09-01

    I investigated the mating system and male mating tactics for a population of wild spider monkeys (Ateles belzebuth chamek), to identify the behaviors males used to achieve and maintain access to sexually receptive females, and to examine if some males used more tactics than other males and/or had differential access to females. Results show that the mating system mostly involved scramble competition polygyny and that males used a range of mating tactics and behaviors, previously unreported for spider monkeys. The most unusual feature of spider monkey mating behavior was the secretive nature of copulations-nearly all copulations were clandestine, but a few were in the presence of other group members. Fifteen sexually mature males were observed to copulate 43 times. These data provide the first opportunity to evaluate how female availability influences male-male competition. First, the operational sex ratio was highly skewed toward males because usually only one female was receptive in each community per month. Second, females only mated with a few males in their community in any one mating period, but some females mated over the course of multiple consecutive mating periods, eventually mating with most or all of the males in their community. Across all communities, 9 (21%) of the 43 copulations involved a single male-female partner, 20 (47%) involved four males mating with the same female, and males mated with from one to four different females. Fourteen of the 16 total adult males and 1 subadult male (10 total) copulated. One or two males in each community were successful in monopolizing access to receptive females, and these males did not usually have the highest rates of copulation. In this system, clandestine copulations are one behavioral solution to the complex problem of gaining mating exclusivity and, probably, exercising mate choice. (c) 2010 Wiley-Liss, Inc.

  19. Peptidomic and transcriptomic profiling of four distinct spider venoms.

    Science.gov (United States)

    Oldrati, Vera; Koua, Dominique; Allard, Pierre-Marie; Hulo, Nicolas; Arrell, Miriam; Nentwig, Wolfgang; Lisacek, Frédérique; Wolfender, Jean-Luc; Kuhn-Nentwig, Lucia; Stöcklin, Reto

    2017-01-01

    Venom based research is exploited to find novel candidates for the development of innovative pharmacological tools, drug candidates and new ingredients for cosmetic and agrochemical industries. Moreover, venomics, as a well-established approach in systems biology, helps to elucidate the genetic mechanisms of the production of such a great molecular biodiversity. Today the advances made in the proteomics, transcriptomics and bioinformatics fields, favor venomics, allowing the in depth study of complex matrices and the elucidation even of minor compounds present in minute biological samples. The present study illustrates a rapid and efficient method developed for the elucidation of venom composition based on NextGen mRNA sequencing of venom glands and LC-MS/MS venom proteome profiling. The analysis of the comprehensive data obtained was focused on cysteine rich peptide toxins from four spider species originating from phylogenetically distant families for comparison purposes. The studied species were Heteropoda davidbowie (Sparassidae), Poecilotheria formosa (Theraphosidae), Viridasius fasciatus (Viridasiidae) and Latrodectus mactans (Theridiidae). This led to a high resolution profiling of 284 characterized cysteine rich peptides, 111 of which belong to the Inhibitor Cysteine Knot (ICK) structural motif. The analysis of H. davidbowie venom revealed a high richness in term of venom diversity: 95 peptide sequences were identified; out of these, 32 peptides presented the ICK structural motif and could be classified in six distinct families. The profiling of P. formosa venom highlighted the presence of 126 peptide sequences, with 52 ICK toxins belonging to three structural distinct families. V. fasciatus venom was shown to contain 49 peptide sequences, out of which 22 presented the ICK structural motif and were attributed to five families. The venom of L. mactans, until now studied for its large neurotoxins (Latrotoxins), revealed the presence of 14 cysteine rich

  20. Comprehensive Proteomic Analysis of Spider Dragline Silk from Black Widows: A Recipe to Build Synthetic Silk Fibers.

    Science.gov (United States)

    Larracas, Camille; Hekman, Ryan; Dyrness, Simmone; Arata, Alisa; Williams, Caroline; Crawford, Taylor; Vierra, Craig A

    2016-09-13

    The outstanding material properties of spider dragline silk fibers have been attributed to two spidroins, major ampullate spidroins 1 and 2 (MaSp1 and MaSp2). Although dragline silk fibers have been treated with different chemical solvents to elucidate the relationship between protein structure and fiber mechanics, there has not been a comprehensive proteomic analysis of the major ampullate (MA) gland, its spinning dope, and dragline silk using a wide range of chaotropic agents, inorganic salts, and fluorinated alcohols to elucidate their complete molecular constituents. In these studies, we perform in-solution tryptic digestions of solubilized MA glands, spinning dope and dragline silk fibers using five different solvents, followed by nano liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) analysis with an Orbitrap Fusion™ Tribrid™. To improve protein identification, we employed three different tryptic peptide fragmentation modes, which included collision-induced dissociation (CID), electron transfer dissociation (ETD), and high energy collision dissociation (HCD) to discover proteins involved in the silk assembly pathway and silk fiber. In addition to MaSp1 and MaSp2, we confirmed the presence of a third spidroin, aciniform spidroin 1 (AcSp1), widely recognized as the major constituent of wrapping silk, as a product of dragline silk. Our findings also reveal that MA glands, spinning dope, and dragline silk contain at least seven common proteins: three members of the Cysteine-Rich Protein Family (CRP1, CRP2 and CRP4), cysteine-rich secretory protein 3 (CRISP3), fasciclin and two uncharacterized proteins. In summary, this study provides a proteomic blueprint to construct synthetic silk fibers that most closely mimic natural fibers.

  1. Comprehensive Proteomic Analysis of Spider Dragline Silk from Black Widows: A Recipe to Build Synthetic Silk Fibers

    Directory of Open Access Journals (Sweden)

    Camille Larracas

    2016-09-01

    Full Text Available The outstanding material properties of spider dragline silk fibers have been attributed to two spidroins, major ampullate spidroins 1 and 2 (MaSp1 and MaSp2. Although dragline silk fibers have been treated with different chemical solvents to elucidate the relationship between protein structure and fiber mechanics, there has not been a comprehensive proteomic analysis of the major ampullate (MA gland, its spinning dope, and dragline silk using a wide range of chaotropic agents, inorganic salts, and fluorinated alcohols to elucidate their complete molecular constituents. In these studies, we perform in-solution tryptic digestions of solubilized MA glands, spinning dope and dragline silk fibers using five different solvents, followed by nano liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS analysis with an Orbitrap Fusion™ Tribrid™. To improve protein identification, we employed three different tryptic peptide fragmentation modes, which included collision-induced dissociation (CID, electron transfer dissociation (ETD, and high energy collision dissociation (HCD to discover proteins involved in the silk assembly pathway and silk fiber. In addition to MaSp1 and MaSp2, we confirmed the presence of a third spidroin, aciniform spidroin 1 (AcSp1, widely recognized as the major constituent of wrapping silk, as a product of dragline silk. Our findings also reveal that MA glands, spinning dope, and dragline silk contain at least seven common proteins: three members of the Cysteine-Rich Protein Family (CRP1, CRP2 and CRP4, cysteine-rich secretory protein 3 (CRISP3, fasciclin and two uncharacterized proteins. In summary, this study provides a proteomic blueprint to construct synthetic silk fibers that most closely mimic natural fibers.

  2. Noise in tunneling spin current across coupled quantum spin chains

    OpenAIRE

    Aftergood, Joshua; Takei, So

    2017-01-01

    We theoretically study the spin current and its dc noise generated between two spin-1/2 spin chains weakly coupled at a single site in the presence of an over-population of spin excitations and a temperature elevation in one subsystem relative to the other, and compare the corresponding transport quantities across two weakly coupled magnetic insulators hosting magnons. In the spin chain scenario, we find that applying a temperature bias exclusively leads to a vanishing spin current and a conc...

  3. SPIDERS Bi-Directional Charging Station Interconnection Testing

    Energy Technology Data Exchange (ETDEWEB)

    Simpson, M.

    2013-09-01

    The Smart Power Infrastructure Demonstration for Energy Reliability and Security (SPIDERS) program is a multi-year Department of Defense-Department of Energy (DOE) collaborative effort that will demonstrate integration of renewables into island-able microgrids using on-site generation control, demand response, and energy storage with robust security features at multiple installations. Fort Carson, Colorado, will be the initial development and demonstration site for use of plug-in electric vehicles as energy storage (also known as vehicle-to-grid or V2G).

  4. Native spider silk as a biological optical fiber

    Science.gov (United States)

    Huby, N.; Vié, V.; Renault, A.; Beaufils, S.; Lefèvre, T.; Paquet-Mercier, F.; Pézolet, M.; Bêche, B.

    2013-03-01

    In this study, we demonstrate the use of eco-friendly native spider silk as an efficient optical fiber in air, highly bent fibers, and physiological liquid. We also integrated the silk filament in a photonic chip made of polymer microstructures fabricated by UV lithography. The molding process is non-destructive for silk and leads to an efficient micro-optical coupling between silk and synthetic optical structures. These optical performances combined with the unique biocompatibility, bioresorbability, flexibility, and tensile strength of silk filaments pave the way for new applications in biological media and for original biophotonic purposes.

  5. TFC - Accesibilidad web

    OpenAIRE

    Aguilar Garzón, Daniel

    2011-01-01

    Estudio de 10 webs del portal uoc.edu, basado en las pautas de accesibilidad web W3C Estudi de 10 webs del portal uoc.edu, basat en les pautes d'accessibilitat web W3C Study of 10 portal websites uoc.edu based on the W3C web accessibility guidelines

  6. Effect of spin rotation coupling on spin transport

    International Nuclear Information System (INIS)

    Chowdhury, Debashree; Basu, B.

    2013-01-01

    We have studied the spin rotation coupling (SRC) as an ingredient to explain different spin-related issues. This special kind of coupling can play the role of a Dresselhaus like coupling in certain conditions. Consequently, one can control the spin splitting, induced by the Dresselhaus like term, which is unusual in a semiconductor heterostructure. Within this framework, we also study the renormalization of the spin-dependent electric field and spin current due to the k → ⋅p → perturbation, by taking into account the interband mixing in the rotating system. In this paper we predict the enhancement of the spin-dependent electric field resulting from the renormalized spin rotation coupling. The renormalization factor of the spin electric field is different from that of the SRC or Zeeman coupling. The effect of renormalized SRC on spin current and Berry curvature is also studied. Interestingly, in the presence of this SRC-induced SOC it is possible to describe spin splitting as well as spin galvanic effect in semiconductors. -- Highlights: •Studied effect of spin rotation coupling on the spin electric field, spin current and Berry curvature. •In the k → ⋅p → framework we study the renormalization of spin electric field and spin current. •For an inertial system we have discussed the spin splitting. •Expression for the Berry phase in the inertial system is discussed. •The inertial spin galvanic effect is studied

  7. Climatic Variables Do Not Directly Predict Spider Richness and Abundance in Semiarid Caatinga Vegetation, Brazil.

    Science.gov (United States)

    Carvalho, Leonardo S; Sebastian, Nicholas; Araújo, Helder F P; Dias, Sidclay C; Venticinque, Eduardo; Brescovit, Antonio D; Vasconcellos, Alexandre

    2015-02-01

    Spiders are abundant in tropical ecosystems and exert predatory pressure on a wide variety of invertebrate populations and also serve as prey for many others organisms, being part of complex interrelationships influenced directly and indirectly by a myriad of factors. We examined the influence of biotic (i.e., prey availability) and abiotic (i.e., temperature, precipitation, relative humidity, real evapotranspiration) factors on species richness and abundance during a two-year period in the semiarid Caatinga vegetation in northeastern Brazil. Data were analyzed through partial autocorrelation functions, cross correlations, and a path analysis. A total of 2522 spiders were collected with beating tray, pit-fall traps, and malaise traps, comprising 91 species and 34 families. Spider abundance peaked in the rainy season. Our results suggest that total invertebrate abundance has a direct influence on spider richness and abundance, whereas the effects of precipitation were mainly indirectly related to most spider assemblage parameters. The increase in vegetation cover with the rainy season in the Caatinga provides more breeding and foraging sites for spiders and stimulates their activities. Additionally, rainfall in arid and semiarid ecosystems stimulated the activity and reproduction of many herbivore and detritivore invertebrates dependent on plant biomass and necromass consumption, leading to an increase in spider prey availability. © The Author 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  8. Psychophysiology of spider phobia in 8- to 12-year-old girls.

    Science.gov (United States)

    Leutgeb, Verena; Schäfer, Axel; Köchel, Angelika; Scharmüller, Wilfried; Schienle, Anne

    2010-12-01

    The present investigation focused on late event-related potentials (ERPs) and facial electromyographic (EMG) activity in response to symptom provocation in 8- to 12-year-old spider phobic girls and compared results to those in non-fearful controls. Fourteen patients and 14 controls were presented with phobia-relevant, generally fear-inducing, disgust-inducing and affectively neutral pictures in an EEG/EMG session. ERPs were extracted in the time-windows 340-500ms (P300) and 550-770ms (late positive potential, LPP). Relative to controls, phobics showed enhanced amplitudes of P300 and LPP in response to spider pictures. This result is interpreted to reflect motivated attention to emotionally salient stimuli. Moreover, phobics showed enhanced average facial EMG activity of the levator labii and the corrugator supercilii in response to spider pictures, reflecting the negative valence and disgust relevance of spiders. Additionally, spider phobic girls relative to controls showed higher overall disgust proneness and heightened average facial EMG activity in both muscle regions in response to disgust stimuli, possibly revealing a disgust-based origin of spider phobia in children. These aspects should be considered in psychotherapeutic treatment of childhood spider phobia. Copyright © 2010 Elsevier B.V. All rights reserved.

  9. Heat Tolerance of the Brown Recluse Spider (Araneae: Sicariidae): Potential for Pest Control.

    Science.gov (United States)

    Cramer, Kenneth L; Zagar, Lindsey M

    2016-02-01

    The brown recluse spider, Loxosceles reclusa Gertsch & Mulaik, is a well-known venomous spider common in the south-central United States where infestations can reach thousands of individuals in a single structure. Bites from this spider pose a risk of dermonecrotic lesions (loxoscelism) or, rarely, more serious systemic effects. The heat tolerance of this spider is understudied but may offer an alternative pest control solution to pesticides or fumigation, both of which have their disadvantages. We subjected brown recluse spiders to increasing temperatures to establish the upper lethal temperature (LT). Using probit analysis to generate probability of mortality at increasing temperatures, we then exposed adult spiders to the observed LT50 to simulate whole-room heat treatment. Laboratory results predict exposure to 48°C for 130 min will achieve 100% mortality of adult spiders. Field tests need to be conducted to determine the efficacy of heat treatment in a variety of real-world situations. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  10. Brain dynamics in spider-phobic individuals exposed to phobia-relevant and other emotional stimuli.

    Science.gov (United States)

    Michalowski, Jaroslaw M; Melzig, Christiane A; Weike, Almut I; Stockburger, Jessica; Schupp, Harald T; Hamm, Alfons O

    2009-06-01

    Dense sensor event-related brain potentials were measured in participants with spider phobia and nonfearful controls during viewing of phobia-relevant spider and standard emotional (pleasant, unpleasant, neutral) pictures. Irrespective of the picture content, spider phobia participants responded with larger P1 amplitudes than controls, suggesting increased vigilance in this group. Furthermore, spider phobia participants showed a significantly enlarged early posterior negativity (EPN) and late positive potential (LPP) during the encoding of phobia-relevant pictures compared to nonfearful controls. No group differences were observed for standard emotional materials indicating that these effects were specific to phobia-relevant material. Within group comparisons of the spider phobia group, though, revealed comparable EPN and LPP evoked by spider pictures and emotional (unpleasant and pleasant) picture contents. These results demonstrate a temporal unfolding in perceptual processing from unspecific vigilance (P1) to preferential responding (EPN and LPP) to phobia-relevant materials in the spider phobia group. However, at the level of early stimulus processing, these effects of increased attention seem to be related to emotional relevance of the stimulus cues rather than reflecting a fear-specific response.

  11. Phantom spiders 2: More notes on dubious spider species from Europe

    Directory of Open Access Journals (Sweden)

    Breitling, Rainer

    2016-09-01

    Full Text Available A surprisingly large number of European spider species have never been reliably rediscovered since their first description many decades ago. Most of these are probably synonymous with other species or unidentifiable, due to insufficient descriptions or missing type material. In this second part of a series on this topic, we discuss about 100 of these cases, focusing mainly on species described in the early 20th century by Pelegrín Franganillo Balboa and Gabor von Kolosváry, as well as a number of jumping spiders and various miscellaneous species. In most cases, the species turned out to be unidentifiable nomina dubia, but for some of them new synonymies could be established as follows: Alopecosa accentuata auct., nec (Latreille, 1817 = Alopecosa farinosa (Herman, 1879 syn. nov., comb. nov.; Alopecosa barbipes oreophila Simon, 1937 = Alopecosa farinosa (Herman, 1879 syn. nov., comb. nov.; Alopecosa mariae orientalis (Kolosváry, 1934 = Alopecosa mariae (Dahl, 1908 syn. nov.; Araneus angulatus afolius (Franganillo, 1909 and Araneus angulatus atricolor Simon, 1929 = Araneus angulatus Clerck, 1757 syn. nov.; Araneus angulatus castaneus (Franganillo, 1909 = Araneus pallidus (Olivier, 1789 syn. nov.; Araneus angulatus levifolius (Franganillo, 1909, Araneus angulatus niger (Franganillo, 1918 and Araneus angulatus nitidifolius (Franganillo, 1909 = Araneus angulatus Clerck 1757 syn. nov.; Araneus angulatus pallidus (Franganillo, 1909, Araneus angulatus crucinceptus (Franganillo, 1909, Araneus angulatus fuscus (Franganillo, 1909 and Araneus angulatus iberoi (Franganillo, 1909 = Araneus pallidus (Olivier, 1789 syn. nov.; Araneus circe strandi (Kolosváry, 1935 = Araneus circe (Audouin, 1826 syn. nov.; Araneus diadematus nemorosus Simon, 1929 and Araneus diadematus soror (Simon, 1874 = Araneus diadematus Clerck, 1757 syn. nov.; Araneus pyrenaeus (Simon, 1874 = Araneus pallidus (Olivier, 1789 syn. nov.; Araneus sericinus (Roewer, 1942 = Aculepeira armida

  12. Spin labels. Applications in biology

    International Nuclear Information System (INIS)

    Frangopol, T.P.; Frangopol, M.; Ionescu, S.M.; Pop, I.V.; Benga, G.

    1980-11-01

    The main applications of spin labels in the study of biomembranes, enzymes, nucleic acids, in pharmacology, spin immunoassay are reviewed along with the fundamentals of the spin label method. 137 references. (author)

  13. Proceedings of RIKEN BNL Research Center workwhop on RHIC spin

    Energy Technology Data Exchange (ETDEWEB)

    SOFFER,J.

    1999-10-06

    This RHIC Spin Workshop is the 1999 annual meeting of the RHIC Spin Collaboration, and the second to be hosted at Brookhaven and sponsored by the RIKEN BNL Research Center. The previous meetings were at Brookhaven (1998), Marseille (1996), MIT in 1995, Argonne 1994, Tucson in 1991, and the Polarized Collider Workshop at Penn State in 1990. As noted last year, the Center provides a home for combined work on spin by theorists, experimenters, and accelerator physicists. This proceedings, as last year, is a compilation of 1 page summaries and 5 selected transparencies for each speaker. It is designed to be available soon after the workshop is completed. Speakers are welcome to include web or other references for additional material. The RHIC spin program and RHIC are rapidly becoming reality. RHIC has completed its first commissioning run, as described here by Steve Peggs. The first Siberian Snake for spin has been completed and is being installed in RHIC. A new polarized source from KEK and Triumf with over 1 milliampere of polarized H{sup minus} is being installed, described by Anatoli Zelenski. They have had a successful test of a new polarimeter for RHIC, described by Kazu Kurita and Haixin Huang. Spin commissioning is expected next spring (2000), and the first physics run for spin is anticipated for spring 2001. The purpose of the workshop is to get everyone together about once per year and discuss goals of the spin program, progress, problems, and new ideas. They also have many separate regular forums on spin. There are spin discussion sessions every Tuesday, now organized by Naohito Saito and Werner Vogelsang. The spin discussion schedule and copies of presentations are posted on http://riksg01.rhic.bnl.gov/rsc. Speakers and other spinners are encouraged to come to BNL and to lead a discussion on your favorite idea. They also have regular polarimeter and snake meetings on alternate Thursdays, led by Bill McGahern, the lead engineer for the accelerator spin

  14. Spin Switching via Quantum Dot Spin Valves

    Science.gov (United States)

    Gergs, N. M.; Bender, S. A.; Duine, R. A.; Schuricht, D.

    2018-01-01

    We develop a theory for spin transport and magnetization dynamics in a quantum dot spin valve, i.e., two magnetic reservoirs coupled to a quantum dot. Our theory is able to take into account effects of strong correlations. We demonstrate that, as a result of these strong correlations, the dot gate voltage enables control over the current-induced torques on the magnets and, in particular, enables voltage-controlled magnetic switching. The electrical resistance of the structure can be used to read out the magnetic state. Our model may be realized by a number of experimental systems, including magnetic scanning-tunneling microscope tips and artificial quantum dot systems.

  15. Spin, mass, and symmetry

    Energy Technology Data Exchange (ETDEWEB)

    Peskin, M.E. [Stanford Univ., CA (United States)

    1994-12-01

    When the strong interactions were a mystery, spin seemed to be just a complication on top of an already puzzling set of phenomena. But now that particle physicists have understood the strong, weak, and electromagnetic interactions, to be gauge theories, with matter built of quarks and leptons, it is recognized that the special properties of spin 1/2 and spin 1 particles have taken central role in the understanding of Nature. The lectures in this summer school will be devoted to the use of spin in unravelling detailed questions about the fundamental interactions. Thus, why not begin by posing a deeper question: Why is there spin? More precisely, why do the basic pointlike constituents of Nature carry intrinsic nonzero quanta of angular momentum? Though the authos has found no definite answer to this question, the pursuit of an answer has led through a wonderful tangle of speculations on the deep structure of Nature. Is spin constructed or is it fundamental? Is it the requirement of symmetry? In the furthest flights taken, it seems that space-time itself is too restrictive a notion, and that this must be generalized in order to gain a full appreciation of spin. In any case, there is no doubt that spin must play a central role in unlocking the mysteries of fundamental physics.

  16. Physics lab in spin

    CERN Multimedia

    Hawkes, N

    1999-01-01

    RAL is fostering commerical exploitation of its research and facilities in two main ways : spin-out companies exploit work done at the lab, spin-in companies work on site taking advantage of the facilities and the expertise available (1/2 page).

  17. More spinoff from spin

    International Nuclear Information System (INIS)

    Masaike, Akira

    1993-01-01

    Despite playing a major role in today's Standard Model, spin - the intrinsic angular momentum carried by particles - is sometimes dismissed as an inessential complication. However several major spin questions with important implications for the Standard Model remain unanswered, and recent results and new technological developments made the 10th International Symposium on High Energy Spin Physics, held in Nagoya, Japan, in November, highly topical. The symposium covered a wide range of physics, reflecting the diversity of spin effects, however four main themes were - the spin content of the nucleon, tests of symmetries and physics beyond standard models, intermediate energy physics, and spin technologies. Opening the meeting, T. Kinoshita reviewed the status of measurements of the anomalous magnetic moment (g-2) of the electron and the muon. The forthcoming experiment at Brookhaven (September 1991, page 23) will probe beyond the energy ranges open to existing electronpositron colliders. For example muon substructure will be opened up to 5 TeV and Ws to 2 TeV. R.L. Jaffe classified quark-parton distributions in terms of their spin dependence, pointing out their leftright attributes, and emphasized the importance of measuring transverse spin distributions through lepton pair production

  18. Spin Hall noise

    NARCIS (Netherlands)

    Kamra, A.; Witek, F.P.; Meyer, S.; Huebl, H.; Geprägs, S.; Gross, R.; Bauer, G.E.W.; Goennenwein, S.T.B.

    2014-01-01

    We measure the low-frequency thermal fluctuations of pure spin current in a platinum film deposited on yttrium iron garnet via the inverse spin Hall effect (ISHE)-mediated voltage noise as a function of the angle ? between the magnetization and the transport direction. The results are consistent

  19. Antiferromagnetic spin Seebeck effect.

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Stephen M.; Zhang, Wei; KC, Amit; Borisov, Pavel; Pearson, John E.; Jiang, J. Samuel; Lederman, David; Hoffmann, Axel; Bhattacharya, Anand

    2016-03-03

    We report on the observation of the spin Seebeck effect in antiferromagnetic MnF2. A device scale on-chip heater is deposited on a bilayer of MnF2 (110) (30nm)/Pt (4 nm) grown by molecular beam epitaxy on a MgF2(110) substrate. Using Pt as a spin detector layer, it is possible to measure the thermally generated spin current from MnF2 through the inverse spin Hall effect. The low temperature (2–80 K) and high magnetic field (up to 140 kOe) regime is explored. A clear spin-flop transition corresponding to the sudden rotation of antiferromagnetic spins out of the easy axis is observed in the spin Seebeck signal when large magnetic fields (>9T) are applied parallel to the easy axis of the MnF2 thin film. When the magnetic field is applied perpendicular to the easy axis, the spin-flop transition is absent, as expected.

  20. Spin, mass, and symmetry

    International Nuclear Information System (INIS)

    Peskin, M.E.

    1994-01-01

    When the strong interactions were a mystery, spin seemed to be just a complication on top of an already puzzling set of phenomena. But now that particle physicists have understood the strong, weak, and electromagnetic interactions, to be gauge theories, with matter built of quarks and leptons, it is recognized that the special properties of spin 1/2 and spin 1 particles have taken central role in the understanding of Nature. The lectures in this summer school will be devoted to the use of spin in unravelling detailed questions about the fundamental interactions. Thus, why not begin by posing a deeper question: Why is there spin? More precisely, why do the basic pointlike constituents of Nature carry intrinsic nonzero quanta of angular momentum? Though the authos has found no definite answer to this question, the pursuit of an answer has led through a wonderful tangle of speculations on the deep structure of Nature. Is spin constructed or is it fundamental? Is it the requirement of symmetry? In the furthest flights taken, it seems that space-time itself is too restrictive a notion, and that this must be generalized in order to gain a full appreciation of spin. In any case, there is no doubt that spin must play a central role in unlocking the mysteries of fundamental physics