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PubMed1995

Severe intravascular hemolysis associated with brown recluse spider envenomation. A report of two cases and review of the literature.

Envenomation by the brown recluse spider (loxoscelism) is classically associated with a necrotic ulcer. Systemic manifestations occur in a minority of cases, but are generally mild and self-limited. The hematologic complications of brown recluse spider bite range from mild hemolysis to fulminant intravascular hemolysis with or without evidence of disseminated intravascular coagulation. Intravascular hemolysis is a rare but occasionally lethal complication of brown recluse spider envenomation. This article presents two cases of severe hemolysis associated with loxoscelism occurring in two young women in Memphis, Tennessee. The second documented death in an adult from severe hemolysis due to a brown recluse spider bite is reported. A review of the literature emphasizing the pathogenic mechanisms of spider bite hemolysis is also included.

Adolescent↗
PubMed2005

Design, expression and solid-state NMR characterization of silk-like materials constructed from sequences of spider silk, Samia cynthia ricini and Bombyx mori silk fibroins.

Silk has a long history of use in medicine as sutures. To address the requirements of a mechanically robust and biocompatible material, basic research to clarify the role of repeated sequences in silk fibroin in its structures and properties seems important as well as the development of a processing technique suitable for the preparation of fibers with excellent mechanical properties. In this study, three silk-like protein analogs were constructed from two regions selected from among the crystalline region of Bombyx mori silk fibroin, (GAGSGA)(2), the crystalline region of Samia cynthia ricini silk fibroin, (Ala)(12), the crystalline region of spider dragline silk fibroin, (Ala)(6), and the Gly-rich region of spider silk fibroin, (GGA)(4). The silk-like protein analog constructed from the crystalline regions of the spider dragline silk and B. mori silk fibroins, (A(6)SCS)(8), that constructed from the crystalline regions of the S. c.ricini and B. mori silk fibroins, (A(12)SGS)(4), that constructed from and the crystalline region of S. c.ricini silk fibroin and the glycine-rich region of spider dragline silk fibroin, (A(12)SGS)(4),were expressed their molecular weights being about 36.0 kDa, 17.0 kDa and 17.5 kDa, respectively in E. coli by means of genetic engineering technologies. (A(12)SCS)(4) and (A(12)SGS)(4 )undergo a structural transition from alpha-helix to beta-sheet on a change in the solvent treatment from trifluoroacetic acid (TFA) to formic acid (FA). However, (A(6)SCS)(8) takes on the beta-sheet structure predominantly on TFA treatment and FA treatment. Structural analysis was performed on model peptides selected from spider dragline and S. c.ricini silks by means of (13)C CP/MAS NMR.

Animals↗
PubMed2004

Predator-prey coevolution: Australian native bees avoid their spider predators.

Australian crab spiders Thomisus spectabilis manipulate visual flower signals to lure introduced Apis mellifera. We gave Australian native bees, Austroplebia australis, the choice between two white daisies, Chrysanthemum frutescens, one of them occupied by a crab spider. The colour contrast between flowers and spiders affected the behaviour of native bees. Native bees approached spider-occupied flowers more frequently. However, native bees avoided flowers occupied by spiders and landed on vacant flowers more frequently. In contrast to honeybees that did not coevolve with T. spectabilis, Australian native bees show an anti-predatory response to avoid flowers occupied by this predator.

Animals↗
PubMed2005

Spider webs designed for rare but life-saving catches.

The impact of rare but positive events on the design of organisms has been largely ignored, probably due to the paucity of recordings of such events and to the difficulty of estimating their impact on lifetime reproductive success. In this respect, we investigated the size of spider webs in relation to rare but large prey catches. First, we collected field data on a short time-scale using the common orb-weaving spider Zygiella x-notata to determine the distribution of the size of prey caught and to quantify the relationship between web size and daily capture success. Second, we explored, with an energetic model, the consequences of an increase in web size on spider fitness. Our results showed that (i) the great majority of prey caught are quite small (body length less than 2mm) while large prey (length greater than 10mm) are rare, (ii) spiders cannot survive or produce eggs without catching these large but rare prey and (iii) increasing web size increases the daily number of prey caught and thus long-term survival and fecundity. Spider webs seem, therefore, designed for making the best of the rare but crucial event of catching large prey.

Adaptation, Physiological↗
PubMed2004

Prey selection by linyphiid spiders: molecular tracking of the effects of alternative prey on rates of aphid consumption in the field.

A molecular approach, using aphid-specific monoclonal antibodies, was used to test the hypothesis that alternative prey can affect predation on aphids by linyphiid spiders. These spiders locate their webs in cereal crops within microsites where prey density is high. Previous work demonstrated that of two subfamilies of Linyphiidae, one, the Linyphiinae, is web-dependent and makes its webs at sites where they were more likely to intercept flying insects plus those (principally aphids) falling from the crop above. The other, the Erigoninae, is less web-dependent, making its webs at ground level at sites with higher densities of ground-living detritivores, especially Collembola. The guts of the spiders were analysed to detect aphid proteins using enzyme-linked immunosorbent assay (ELISA). Female spiders were consuming more aphid than males of both subfamilies and female Linyphiinae were, as predicted, eating more aphid than female Erigoninae. Rates of predation on aphids by Linyphiinae were related to aphid density and were not affected by the availability of alternative prey. However, predation by the Erigoninae on aphids was significantly affected by Collembola density. Itinerant Linyphiinae, caught away from their webs, contained the same concentration of aphid in their guts as web-owners. However, nonweb-owning Erigoninae, living away from Collembola aggregations at web-sites, contained significantly higher concentrations of aphid. For both subfamilies there was evidence of a disproportionate increase in predation on aphids once Collembola populations had declined. It was concluded that nonaphid prey, by helping to maintain spiders in the field, can significantly affect predation on aphids.

Animals↗
PubMed2006

Plant-fungus mutualism affects spider composition in successional fields.

Mutualistic symbionts are widespread in plants and may have strong, bottom-up influences on community structure. Here we show that a grass-endophyte mutualism shifts the composition of a generalist predator assemblage. In replicated, successional fields we manipulated endophyte infection by Neotyphodium coenophialum in a dominant, non-native plant (Lolium arundinaceum). We compared the magnitude of the endophyte effect with manipulations of thatch biomass, a habitat feature of known importance to spiders. The richness of both spider families and morphospecies was greater in the absence of the endophyte, although total spider abundance was not affected. Thatch removal reduced both spider abundance and richness, and endophyte and thatch effects were largely additive. Spider families differed in responses, with declines in Linyphiidae and Thomisidae due to the endophyte and declines in Lycosidae due to thatch removal. Results demonstrate that the community impacts of non-native plants can depend on plants' mutualistic associates, such as fungal endophytes.

Animals↗
PubMedDate not supplied

Pair rule gene orthologs in spider segmentation.

The activation of pair rule genes is the first indication of the metameric organization of the Drosophila embryo and thus forms a key step in the segmentation process. There are two classes of pair rule genes in Drosophila: the primary pair rule genes that are directly activated by the maternal and gap genes and the secondary pair rule genes that rely on input from the primary pair rule genes. Here we analyze orthologs of Drosophila primary and secondary pair rule orthologs in the spider Cupiennius salei. The expression patterns of the spider pair rule gene orthologs can be subdivided in three groups: even-skipped and runt-1 expression is in stripes that start at the posterior end of the growth zone and their expression ends before the stripes reach the anterior end of the growth zone, while hairy and pairberry-3 stripes also start at the posterior end, but do not cease in the anterior growth zone. Stripes of odd-paired, odd-skipped-related-1, and sloppy paired are only found in the anterior portion of the growth zone. The various genes thus seem to be active during different phases of segment specification. It is notable that the spider orthologs of the Drosophila primary pair rule genes are active more posterior in the growth zone and thus during earlier phases of segment specification than most orthologs of Drosophila secondary pair rule genes, indicating that parts of the hierarchy might be conserved between flies and spiders. The spider ortholog of the Drosophila pair rule gene fushi tarazu is not expressed in the growth zone, but is expressed in a Hox-like fashion. The segmentation function of fushi tarazu thus appears to be a newly acquired role of the gene in the lineage of the mandibulate arthropods.

Amino Acid Sequence↗
PubMed2002

Spider silk fibers spun from soluble recombinant silk produced in mammalian cells.

Spider silks are protein-based "biopolymer" filaments or threads secreted by specialized epithelial cells as concentrated soluble precursors of highly repetitive primary sequences. Spider dragline silk is a flexible, lightweight fiber of extraordinary strength and toughness comparable to that of synthetic high-performance fibers. We sought to "biomimic" the process of spider silk production by expressing in mammalian cells the dragline silk genes (ADF-3/MaSpII and MaSpI) of two spider species. We produced soluble recombinant (rc)-dragline silk proteins with molecular masses of 60 to 140 kilodaltons. We demonstrated the wet spinning of silk monofilaments spun from a concentrated aqueous solution of soluble rc-spider silk protein (ADF-3; 60 kilodaltons) under modest shear and coagulation conditions. The spun fibers were water insoluble with a fine diameter (10 to 40 micrometers) and exhibited toughness and modulus values comparable to those of native dragline silks but with lower tenacity. Dope solutions with rc-silk protein concentrations >20% and postspinning draw were necessary to achieve improved mechanical properties of the spun fibers. Fiber properties correlated with finer fiber diameter and increased birefringence.

Amino Acid Motifs↗
PubMed2005

Giant wood spider Nephila pilipes alters silk protein in response to prey variation.

Recent studies have demonstrated that orb-weaving spiders may alter web structures, foraging localities or silk output in response to prey variations. In this study we conducted field surveys and food manipulations to examine whether orb-weaving spiders may also adjust the protein of silk to prey variations. A comparison of dragline silks collected from nine giant wood spider Nephila pilipes populations in Taiwan showed a spatial variation. The percentage of all amino acids (except alanine and glycine) exhibited significant differences among populations. A survey of prey composition also revealed a significant spatial variation among N. pilipes populations. To determine whether prey variation was responsible for silk protein variation, we fed N. pilipes with different types of prey (dipteran vs orthopteran) then compared the percentage of five major dragline amino acids and secondary structures. The results showed that dragline of N. pilipes fed with orthopteran prey contained significantly higher proline and glutamine but lower alanine. Congruent with this result were those from FTIR spectroscopy, which showed that dragline of N. pilipes fed with crickets exhibited significantly higher percentage of proline- and glutamine-containing beta turns, and lower percentage of alanine-containing beta sheet structures. Since the results of feeding manipulations showed that diet significantly affected the compositions of dragline silks, the observed spatial variation seemed to reflect the different types of prey these spiders had consumed. Results of this study thus indicated that orb-weaving spiders can alter dragline protein in response to prey variations.

Amino Acids↗
PubMed2005

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

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.

Analysis of Variance↗
PubMed2001

Polarized light detection in spiders.

We describe here the detection of polarized light by the simple eyes of spiders. Using behavioural, morphological, electrophysiological and optical studies, we show that spiders have evolved two different mechanisms to resolve the e-vector of light. Wolf spiders (Lycosidae), are able to turn in response to rotation of a polarized pattern at the zenith of their visual fields, and we also describe a strip in the ventral retina of the principal (anterio-median) eyes that views this location and has receptors tiered into two layers. This provides each pair of receptors with a similar optical solution to that provided by the 'dorsal rim area' of the insect compound eye. In contrast, gnaphosid spiders have evolved a pair of lensless secondary eyes for the detection of polarized light. These two eyes, each sensitive to orthogonal directions of polarization, are perfectly designed to integrate signals from the larger part of the sky and cooperate to analyse the polarization of light. Built-in polarizers help to improve signal purity. Similar organisation in the eyes of several other spider families suggests that these two mechanisms are not restricted to only a few families.

Animals↗
PubMed2000

Self-reported automaticity and irrationality in spider phobia.

Spider phobic women (n = 39) and nonfearful controls (n = 41) completed a 20-item questionnaire measuring the extent to which they experience their fear reactions to spiders as automatic and irrational. For the phobic sample, therapy outcome data were also collected. Results suggest that spider phobics tend to view their attitude to spiders as irrational and in this respect, they do not differ from control subjects. Furthermore, compared to control subjects, phobics more often perceive their responses to spiders as automatic, i.e., not under intentional control. Contrary to expectation, no robust correlation was found between automaticity and irrationality. Interestingly, automaticity was not related to treatment outcome, while irrationality to some extent predicted therapy outcome (i.e., the more phobics experienced their fear as irrational, the more they profited from exposure treatment).

Adult↗
PubMed2001

High gene flow levels lead to gamete wastage in a desert spider system.

Field censuses, breeding experiments, and a quantitative model are used to obtain insight into the extent and consequences of genetic mixing between locally adapted populations of a desert spider. Typically, 9% of the matings of desert riparian spiders (non-aggressive phenotype) in native habitat involve an arid-land partner (aggressive phenotype). Mating was found to be random with respect to behavioral phenotype, but linearly related to both the rate of immigration and survival of immigrants from surrounding arid habitats in the riparian area. Genetic mixing between riparian and arid-land spiders produces offspring that exhibit lower rates of survival in riparian habitat. Two extreme behavioral phenotypes were also observed in the field studies: approximately 5% of the female spiders attacked all males they encountered while another 22% ran from all potential mates. Punnett square analyses of the potential genotypes produced by introgression between arid- and riparian-adapted spiders indicate that these extreme phenotypes appear in F2 generation hybrids and backcrosses. Because there is a costly wastage of gametes in the case of mixed phenotype mating, model results indicate that within three generations of the cessation of gene flow, the riparian population would be free of mixed genotypes and moving towards genetic differentiation.

Alleles↗
PubMed1975

[Role of the principal and accessory eyes in the photomenotactic orientation of the funnel spider Agelena labyrinthica (CL.)].

The photomenotactic orientation of funnel spiders (Agelena labyrinthica [Cl.]) returning to their retreat was studied by measuring the direction of their course on the horizontal webs. 1. If a lamp was shifted 90 degrees just before the spider caught its prey the mean return course deviated less than 90 degrees from the direction of the retreat. This deviation was not only a function of the azimuth of the light and of the amount it had been moved, but also varied with the course taken when approaching the prey, the duration of the interval without light stimulation while the lamps were changed, the light stimulation experienced while at the retreat, the extent to which vision was experimentally reduced, and the light intensity. 2. Elimination of the principal or of the accessory eyes had little or no significant effect on the photomenotactic orientation. Spiders able to use only the median eye or one principal eye could no longer use the lamp to orient by. 3. Animals with full vision showed an increased (decreased) deviation from the direction of the retreat if the light intensity was abruptly increased (decreased), as did animals without principal eyes or without accessory eyes. The mean return directions were, however, not dependent upon light intensity changes before reaching the prey or after an interruption of web contact. The threshold for photomenotactic orientation using the accessory eyes is 0.366-10(-4) sb; the corresponding value for the principal eyes is 100 times larger. 4. If the lamp was not visible on the outward run the spiders were unable to perform correct return runs by light orientation without optical information from previous runs. If they could see a lamp while at the retreat their return course was shifted in the direction away from the light. Animals without principal eyes did not show this effect. 5. Spiders that had not performed an outward run did not keep to a straight course. Animals with full vision spontaneously showed negative phototactic orientation, those without principal eyes were usually positively phototactic. 6. Animals, whose web contact had been interrupted or animals without principal eyes showed a similar deviation from the correct return direction as did unmanipulated animals.

Animals↗
PubMedDate not supplied

Local tolerance to spider silks and protein polymers in vivo.

Spider silks were implanted subcutaneously in pigs for a study of the tolerance against this material. Four types of spider silks of high purity and cleanliness were implanted: (i) major ampullate dragline silk reeled from the golden silk spider Nephila clavipes, (ii) native (unsterilised) silk reeled from a Brachypelma spider, (iii) native silk taken from this spider's web and (iv) its web silk thermally treated at 80 degrees C. For comparison we used fibrous silk analogue protein polymers and four already marketed wound dressings (polyurethane film, collagen dressings, gauze pads). All materials were applied epicutaneously to split skin wounds. The implants were examined macroscopically as well as by light microscopy. Superficially, all sites healed rapidly. There were marked inflammatory reactions in all sites with lympho-plasmacellular infiltrations, evidence of phagocytosis and granuloma formation as indicated by the appearance of giant cells. However there was a marked absence of epitheloid cells indicating that the observed reaction was a foreign body granuloma. Furthermore, the histopathological images recorded after 14 days revealed no marked differences between the dressings. Polyurethane films, however, seemed to be superior with respect to the duration of the wound healing process.

Animals↗
PubMed2005

The transition to social inbred mating systems in spiders: role of inbreeding tolerance in a subsocial predecessor.

The social spiders are unusual among cooperatively breeding animals in being highly inbred. In contrast, most other social organisms are outbred owing to inbreeding avoidance mechanisms. The social spiders appear to originate from solitary subsocial ancestors, implying a transition from outbreeding to inbreeding mating systems. Such a transition may be constrained by inbreeding avoidance tactics or fitness loss due to inbreeding depression. We examined whether the mating system of a subsocial spider, in a genus with three social congeners, is likely to facilitate or hinder the transition to inbreeding social systems. Populations of subsocial Stegodyphus lineatus are substructured and spiders occur in patches, which may consist of kin groups. We investigated whether male mating dispersal prevents matings within kin groups in natural populations. Approximately half of the marked males that were recovered made short moves (< 5m) and mated within their natal patch. This potential for inbreeding was counterbalanced by a relatively high proportion of immigrant males. In mating experiments, we tested whether inbreeding actually results in lower offspring fitness. Two levels of inbreeding were tested: full sibling versus non-sib matings and matings of individuals within and between naturally occurring patches of spiders. Neither full siblings nor patch mates were discriminated against as mates. Sibling matings had no effect on direct fitness traits such as fecundity, hatching success, time to hatching and survival of the offspring, but negatively affected offspring growth rates and adult body size of both males and females. Neither direct nor indirect fitness measures differed significantly between within patch and between-patch pairs. We tested the relatedness between patch mates and nonpatch mates using DNA fingerprinting (TE-AFLP). Kinship explained 30% of the genetic variation among patches, confirming that patches are often composed of kin. Overall, we found limited male dispersal, lack of kin discrimination, and tolerance to low levels of inbreeding. These results suggest a history of inbreeding which may reduce the frequency of deleterious recessive alleles in the population and promote the evolution of inbreeding tolerance. It is likely that the lack of inbreeding avoidance in subsocial predecessors has facilitated the transition to regular inbreeding social systems.

Animals↗
PubMed2006

The potential of a jumping spider, Phidippus clarus, as a biocontrol agent.

Spiders, particularly assemblages of species, have been shown to be effective in reducing pest insects and crop damage in field crops and orchards. We investigated the potential for a single jumping spider species to reduce pests in a greenhouse setting. We placed three treatments in large enclosures: 1) control treatment of only sweet basil, Ocimum basilicum L.; 2) sweet basil and a phytophagous pest, fourlined plant bug, Poecilocapsus lineatus (F.) (Heteroptera: Miridae); and 3) sweet basil, fourlined plant bug, and jumping spider Phidippus clarus (Keyserling 1884). After 1 wk, jumping spiders reduced the number of plant bugs. Plants exposed to plant bugs alone were significantly shorter than either control plants or plants exposed to plant bugs and spiders. Chlorophyll concentration did not significantly differ across treatments. We discuss the feasibility of using P. clarus and similar salticids in biocontrol.

Animals↗
PubMed1987

Wolf spider bites.

Because of their dark color and hunting habits, wolf spiders (Lycosidae) are often confused with the much more dangerous brown recluse spider (Loxosceles reclusa). Unlike the brown recluse spider, wolf spider envenomation seldom causes cutaneous necrosis or systemic symptoms. In this report, two documented cases of wolf spider bites are described and the pertinent literature reviewed.

Child, Preschool↗