Spider silk is one of the most versatile material.s in nature with great mechanical properties, exceeding some of the best man made materials. Native and synthetically produced silk has been used in a wide array of applications throughout the history of mankind including nets, bandages and cloths. It is recognized that spider silk can be a suitable replacement material for many existing materials such as ropes, body armor, parachutes and biodegradable bottles - all of which could show cost and environmental 4 benefits relative to other currently used man made materials. An added advantage to these types of applications is the potential for the products to have intrinsic antimicrobial activity. Studies have demonstrated a level of antimicrobial activity in native silk, a property that may have evolved in order to resist microbial decomposition, to protect developing eggs, and to resist decomposition or destruction by predators, parasites, or fluctuations in the environment. In this study, the novel aqueous glue coating peptides found on the silk fiber of the black widow spider, spider coating peptide 1 and 2, were investigated. Using circular dichroism, it was determined that SCP-1 and SCP-2 display predominantly alpha-helical secondary structures. In temperature gradient studies, SCP-1 is structurally stable at high temperatures while SCP-2 unfolded and lost its alpha-helical structure. The two peptides remained structurally stable both in an acidic and basic environment. This study was the first to characterize the secondary structure of the peptides found coating various silk fibers in Latrodectus hesperus, the black widow spider. The function of the SCPs is unknown but has-been hypothesized to potentially have antimicrobial properties. We investigated this role and found no significant antibacterial activity of the peptides against Escherichia coli and Bacillus subtitlis in growth studies. This study is the first to investigate the functional role of SCPs.

Spider silk from the female black widow spider, Latrodectus hesperus, is made of extraordinary biomolecules of nature. Efforts of the scientific community to commercially synthesize silks have become a collaborating, yet competitive race, to characterize the proteins that contribute to its intriguing biomechanics. Little has been reported on aqueous silk molecules in black widow spider silk, which are quite different from the large water insoluble core fibroins. In this study, a novel, aqueous aggregate gland derived silk factor (AgSF 1) was investigated using proteomics and immunological approaches. Western blot analyses of whole tissue lysates and solublized silk fibers revealed high levels of AgSFl in the aggregate gland, in the web scaffolding junctions, and in wrapping silk. MS/MS analyses of tryptic digest products from solubilized wrapping silk and aggregate gland whole cell lysate also confirmed the presence of AgSFl in these samples. Possible post-translational modifications were also analyzed by two-dimensional gel electrophoresis (2DE) and MS/MS analysis. AgSFl was localized in the web scaffolding junctions and our data supports a role as an adhesive silk protein that serves as a center for connecting scaffolding fibers that functions to reduce the tensile strength of scaffolding fibers, which facilitates capture of aerial insects.

Belonging to the diverse order Araneae, the black widow spider Latrodectus 4 hesperus produces high-performance silks with a broad range ofbiological functions and mechanical properties. The cob weaver spider spins different fibers by using seven specialized glands located in its abdomen. Egg case silk originates from the tubuliforrn gland and to date, no proteins that participate in the assembly process of egg case silk proteins have been identified. The goal of this project was the expression, purification, and characterization of such protein products. De novo sequencing of peptides from in-solution tryptic digestion of black widow spider dragline silk, the most studied type of silk, identified a novel cysteine-rich nonfibroin- like peptide that we named cysteine-rich component or CRC- 1. Further analysis of a large pool of nucleic acid sequences deposited in our custom eDNA database revealed 4 additional sequences with similarities to each other at the amino acid level called CRC-2, CRC-3, CRC-4, and CRC-5, suggesting a new family of proteins. Specifically, Q-PCR analysis revealed that the CRC-5 mRNAs were predominantly expressed in the tubuliform and aggregate glands. Since the aggregate gland manufactures a more complex aqueous solution compared to the tubuliforrn gland, we focused these studies on the tubuliform gland and resultant egg case fibers. Westem blot analysis using a cross-reactive polyclonal anti-CRC-1 antiserum conoborated the presence of CRC-5 in the tubulifmm gland and egg case silk, supporting the colocalization ofTuSpl, a tubuliform gland-specific protein, and CRC-5. Thus, we have demonstrated that these two proteins are present within tubuliform silks. In vitro studies suggested that recombinant CRC-5 displayed enzymatic activity similar to a sulfhydryl oxidase. Collectively, our findings provide new insights into novel proteins that have a potential role in the silk assembly and extrusion pathway of egg case silk fibers.

Spider silk is a natural high-performance biopolymer with superior mechanical propetiies. Although these fibers out perfmm several man-made and natural biomaterials, there are cha llenges to be circumvented before commercialization. One of the silkproducing glands warranting further study is the pyrifonn gland, which produces gluelike threads functioning to cement dragline silk to substrates. We focused on the molecular properties of PySp 1, the major component of pyrifonn silk from Latrodectus hersperus, and its putative Oiiholog, PySp2, from Nephi/a clavipes. To date, there are no reports describing the secondary structure of PySp internal block repeats. Moreover, because the PySp C-terminus amino acid residues are distinct from MaSp C-terminus and the morphology of these glands is different, we hypothesized that PySp C-terminal domains form distinct secondary structures. The MaSp C-terminus has been shown to regulate the silk assembly process and whether the PySp C-terminus performs a similar function is unknown. In order to test this supposition, we used the following experimental approaches: I) we developed a series of PySp prokaryotic expression constructs carrying various block repeat modules representative of the internal iterations found within the protein chain; 2) we constructed prokaryotic expression vectors coding for the PySp C-terminal domains; 3) we expressed and purified the PySp C-terminal domains from bacteria; 4) we performed structural analyses of the purified PySp C-terminal domains using cd spectroscopy and atomic force microscopy. After expression and purification of the PySp C-tennini proteins, our studies support that this domain displays a predominantly ~-sheet structure, distinctive from the NMR-determined ahelical nature of MaSp C-tennini. The difference in secondary structure implies the MA and pyriform glands use different biochemical mechanisms during fiber extrusion to control protein folding and assembly. By investigating protein folding and fiber formation for different spider silk types, its characteristics can be customized for spinning different materials for industrial applications.

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The transfer of prey resources between ecosystems can have dramatic consequences for both recipient and donor systems by altering food web stability and the likelihood of trophic effects cascading across the ecosystem boundary. Landscape-scale factors influence the importance, direction and magnitude of energy flows, but may also alter the ability of consumer organisms to respond to spatio-temporal changes in allochthonous prey availability. Here, I used flood and drying disturbance gradients to investigate interactions between these two processes on populations of a riparian fishing spider Dolomedes aquaticus (Pisauridae). The abundance of aquatic insects with a winged adult stage, a major component of the diet of D. aquaticus, was markedly higher at less flood-prone rivers and declined with increasing flood disturbance. It was expected that spider populations would be largest at these stable rivers where the aquatic prey abundance was highest. However, a habitat (loose, unembedded riverbank rocks) manipulation revealed that the lack of scouring floods at these sites led to habitat-limited populations, preventing response to the increased prey resource. In fact a peak shaped relationship of spider biomass and abundance was found, with the largest spider populations at intermediately disturbed rivers. In addition, patchy habitat availability was the most likely cause of the small scale (4 m2) aggregation of spiders seen at the most stable and disturbed rivers. These patterns were also associated with strong interactions between the spiders. Stable isotope analysis of field collected spiders and an experimental manipulation of spider densities and food availability indicated that cannibalism rates were likely to be significantly higher at stable and disturbed rivers than those intermediate on the disturbance gradient. Differences in D. aquaticus population size structure and life history traits across the flood disturbance gradient were driven by interactions between resource availability, environmental stability and cannibalism rates. To separate the effects of habitat availability and aquatic prey abundance I used drying rivers, as the amount of aquatic insect prey alters as the water recedes. Desiccation mortality and low aquatic prey biomass most likely caused the spiders' spatial distribution and size class structure to alter in drying river reaches, potentially also leading to differences in cannibalism rates. Overall, cross-ecosystem transfers of prey had large impacts on the distribution, cannibalism rates and life history traits of D. aquaticus but their effects were modified by the nature of the ecosystem boundary. Thus river flow regime controlled the magnitude of the subsidy and its use by a consumer. Hence, cross-ecosystem subsidies will not always lead to larger consumer populations and consumer responses will depend on interactions between large-scale processes.

The purpose of this study was to examine the masking preferences of the spider crab, Notomithrax ursus. The algal composition of the mask in the natural habitat at Kaikoura was examined to determine the general rules the crab follows when decorating itself. The effects of size and sex on the mask composition were examined, as well as determining how the composition of the mask varies by body part. The preference of the crabs was further examined through the use of choice and background change experiments in the laboratory. It was determined that the preference of certain types of algae for mask material is not entirely dependent on their relative abundance in the environment. Possible explanations for this behaviour are given.

The present study attempted to answer two general questions: (1) what is the relation between expected and actual reactions to a spider in individuals afraid of spiders? and (2) are inaccurate expectancies updated on the basis of experience? Behavioral and cognitive-behavioral learning models of fear, treatment protocols developed in relation to these, and recent findings from our laboratory necessitated answers to two additional questions: (3) does the expectation accuracy of individuals who meet DSM-IV criteria for diagnosis with a specific phobia differ from that of individuals who are fearful but do not meet criteria? and (4) does expectation accuracy vary as a function of context? Two final questions were obvious: (5) do the actual reactions of individuals who meet criteria for diagnosis differ predictably from those of fearful individuals? and (6) do reactions vary contextually? Student participants reported and tested a series of trial-specific expectancies about their reactions to a live, mechanical, or virtual tarantula over seven trials. Participants then completed three final trials in the presence of a live tarantula. Participants poorly anticipated the quality and intensity of their initial reactions, but expectation accuracy increased quickly. No clear tendencies for over- or under-prediction emerged. Participants updated expectancies in relation to prior trial expectation accuracy, either increasing or decreasing their predicted reactions relative to the original expectancy. Participants who met criteria for diagnosis with a specific phobia consistently anticipated and reported more intense reactions than did those who were fearful, but diagnostic status was not predictive of expectation accuracy. Participants in the live and virtual spider groups reported similar levels of fear that were greater than those in the mechanical spider group. Participants in the virtual spider group more readily reduced the distance maintained between themselves and the spider stimulus than did those in the live or mechanical spider groups. Expectation accuracy did not vary contextually. Results are discussed in light of the theoretical models presented, with findings lending greater support to behavioral models of fear learning relative to cognitive models that postulate a substantial role for conscious processing and appraisal in specific fear. Practical recommendations are made to researchers and clinicians based on present findings.