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.

<p>Environmental changes, such as climate change, can have differential effects on species, with important consequences for community structure and ultimately, for ecosystem functioning. In the Arctic, where ecosystems are experiencing warming at twice the rate as elsewhere, these effects are expected to be particularly strong. A proper characterization of the link between warming and biotic interactions in these particular communities is of global importance because the tundra's permafrost stores a vast amount of carbon that could be released through decomposition as greenhouse gases and alter the global rate of climate change. In this dissertation, I examine how arthropod communities are responding to warming in the Arctic and how these responses might be affecting ecosystem functioning. </p><p>I first address the question of whether and how long-term changes in climate are affecting individual groups and overall community structure in a high-arctic arthropod food web. I find that increasingly warm springs and summers between 1996-2011 differentially affected some arthropod groups and that this led to major changes in the relative abundances of different trophic groups within the arthropod community. Specifically, spring and summer warming are associated with relatively more herbivores and parasitoids and fewer detritivores within the community. These changes are particularly pronounced in heath sites, suggesting that arthropod communities in dry habitats are more responsive to climate change than those in wet habitats. I also show that herbivores and parasitoids are sensitive to conditions at subzero temperatures, even during periods of diapause, and that all trophic groups benefit from a longer transition period between summer and winter. These results suggest that the projected winter and springtime warming in Greenland may have unexpected consequences for northern arthropod communities. Moreover, the relative increase in herbivores and loss of detritivores may be changing the influence of the arthropod community over key ecosystem processes such as decomposition, nutrient cycling, and primary productivity in the tundra. </p><p>Predator-induced trophic cascades have been shown to impact both community structure and ecosystem processes, yet it is unclear how climate change may exacerbate or dampen predator effects on ecosystems. In the second chapter of my dissertation, I investigate the role of one of the dominant tundra predators within the arctic ecosystem, wolf spiders, and how their impact might be changing with warming. Using results from a two-year-long field experiment, I test the influence of wolf spider density over the structure of soil microarthropod communities and decomposition rates under both ambient and artificially warmed temperatures. I find that predator effects on soil microarthropods change in response to warming and that these changes translate into context-specific indirect effects of predators on decomposition. Specifically, while high densities of wolf spiders lead to faster decomposition rates at ambient temperatures, they are associated with slower decomposition rates in experimentally warmed plots. My results suggest that if warming causes an increase in arctic wolf spider densities, these spiders may buffer the rate at which the massive pool of stored carbon is lost from the tundra. </p><p>Wolf spiders in the Arctic are expected to become larger with warming, but it is unclear how this change in body size will affect spider populations or the role of wolf spiders within arctic food webs. In the third chapter of my dissertation, I explore wolf spider population structure and juvenile recruitment at three sites of the Alaskan Arctic that naturally differ in mean spider body size. I find that there are fewer juveniles in sites where female body sizes are larger and that this pattern is likely driven by a size-related increase in the rate of intraspecific cannibalism. These findings suggest that across the tundra landscape, there is substantial variation in the population structure and trophic position of wolf spiders, which is driven by differences in female spider body sizes. </p><p>Overall, this dissertation demonstrates that arctic arthropod communities are changing as a result of warming. In the long-term, warming is causing a shift in arthropod community structure that is likely altering the functional role of these animals within the ecosystem. However even in the short-term, warming can alter species interactions and community structure, with important consequences for ecosystem function. Arthropods are not typically considered to be major players in arctic ecosystems, but I provide evidence that this assumption should be questioned. Considering that they are the largest source of animal biomass across much of the tundra, it is likely that their activities have important consequences for regional and global carbon dynamics.</p> / Dissertation

This research was undertaken primarily to further elucidate the life history of this medically important spider. Special attention was given to rearing experimental spiders under as near-natural environmental conditions as possible.

A família Theraphosidae é a maior dentre as famílias da subordem Mygalomorphae, apresentando 112 gêneros e 908 espécies. É considerada um grupo monofilético, e está dividida em nove subfamílias. A subfamília Theraphosinae é restrita ao continente americano. É caracterizada por apresentar o bulbo com êmbolo distalmente largo e grosso, com presença de quilhas, e o subtegulum largo, que se estende até a metade do tegulum, e também pela presença de pêlos urticantes de tipo I, III e IV (Raven, 1985, Pérez-Miles et al. 1996). Homoeomma foi revisado em 1972, quando possuía um elenco de dez espécies. Atualmente, o gênero apresenta 14 espécies, com distribuição restrita à América do Sul (Argentina, Brasil, Colômbia, Peru e Uruguai). O holótipo de Homoeomma pictum possui bulbo copulador e apófise tibial da perna I semelhante a Thrixopelma, sendo transferido para esse gênero. O tipo da espécie Homoeomma peruvianum também foi examinado e este provavelmente não pertence ao gênero, porém, não foi possível estabelecer um novo gênero para essa espécie. O holótipo de H. nigrum, uma fêmea com espermateca danificada, não foi examinado. Essas duas espécies são consideradas species inquirenda. As espécies H. stradlingi e H. strabo passam a ser sinônimos-júnior de Homoeomma familiare. Homoeomma hirsutum é considerada sinônimo-júnior de H. montanum. Na análise cladística, foram incluídas oito espécies de Homoeomma, além das espécies Grammostola mollicoma, Magulla obesa, Maraca cabocla, Plesiopelma flavohirtum, P. longisternalis, Tmesiphantes nubilus, Gen. n. sp.1. Para o enraizamento, foi utilizada Oligoxytre caatinga (Theraphosidae, Ischnocolinae). A análise resultou em dois cladogramas igualmente parcimoniosos, com 73 passos. O consenso estrito (75 passos) possui a seguinte topologia: (Oligoxystre caatinga ((((Homoeomma stradlingi (H. montanum (H. brasilianum (H. uruguayensis (H. elegans H. villosum)))))(Maraca humile Maraca cabocla ))(Plesiopelma longisternalis Cyriocosmus ritae (Gen. n. simoni Gen. n. sp1 Gen. n. flavohirtum )))(Tmesiphantes nubilus (Grammostola mollicoma Magulla obesa )))). Apenas seis das oito espécies de Homoeomma formam um agrupamento monofilético. Homoeomma simoni e Plesiopelma flavohirtum foram transferidas para um gênero novo, junto a uma espécie nova. O Gen. n. é bem suportado por quatro sinapomorfias. Homoeomma humile é grupo-irmão de Maraca cabocla, sendo transferida para este gênero, compartilhando três características sinapomórficas não exclusivas. O gênero Maraca é grupo-irmão de Homoeomma. As seis espécies restantes de Homoeomma formam um grupo monofilético, com três sinapomorfias não exclusivas: apófise digitiforme do bulbo grande, ângulo de 90º-135º do êmbolo em relação ao bulbo e metatarso I dos machos curvo na base. São descritas pela primeira vez as fêmeas de H. brasilianum e subtegulum. A distribuição das espécies foi atualizada e ampliada com novos registros. / Theraphosidae is the larger family within suborder Mygalomorphae, with 112 genera and 908 species. It is considered a monophyletic group, divided into nine subfamilies. The subfamily Theraphosinae is restricted to America continent. It is characterized by the presence of a papal bulb with wide and thick embulus presenting keels, wide subtegulum, extending down the bulb to half of tegulum length and by the presence of urticating hairs type I, III and IV. The present work aims the increase of the taxonomic and phylogenetic subfamily knowledge, throughout the study of Homoeomma genera Ausserer, 1871. Homoeomma was revised in 1972, including ten species on it. Nowadays, the genera has 14 species, with distribution restricted to South America (Argentina, Brazil, Colombia, Peru e Uruguay). The Homoeomma pictum holotype presents copulatory bulb and tibial apophysis of leg I that resemble Thrixopelma, so the species is transfered to these genus. The type of Homoeomma peruvianum was also examined and probably do not belong to the genus. Unfortunately, it was not possible to establish a new genus to this species. H. nigrum´s holotype, a female presenting a severed spermathecae, wasn\'t examined. These two species are considered species inquireda. H. stradlingi e H. strabo are established as junior-synonyms of H. familiare. And Homoeomma hirsutum is considered junior-synonym of. 7 The eight remaining species of Homoeomma were included in cladistic analysis, enclosed with Grammostola mollicoma, Magulla obesa, Maraca cabocla, Plesiopelma flavohirtum, P. longisternalis, Tmesiphantes nubilus, Gen. n. sp.1. Oligoxytre caatinga (subfamily Ischnocolinae) was used to set the root. The analysis resulted in two equally parsimonic trees, with 73 steps. The strict consensus (75 steps) presents this topology: (Oligoxystre caatinga ((((Homoeomma stradlingi (H. montanum (H. brasilianum (H. uruguayensis (H. elegans H. villosum)))))(Maraca humile Maraca cabocla ))(Plesiopelma longisternalis Cyriocosmus ritae (Gen. n. simoni Gen. n. sp1 Gen. n. flavohirtum )))(Tmesiphantes nubilus (Grammostola mollicoma Magulla obesa )))). The eight species of Homoeomma do not form a monophyletic group. Three transferences are proposed: Homoeomma simoni and Plesiopelma flavohirtum are transfered to a new genus, with a new species. Gen. N. is well supported by four synapomorphies. H. humile is the sister group of Maraca cabocla, sharing three non exclusive synapomorphies. The genus Maraca is considered sister group of Homoeomma. The six remaining species of Homoeomma form a monophyletic group with three non exclusive synapomorphies: a big papal bulb digitform apophysis, a 90º-135ºangle between embulus and bulb and males metatarsus I presenting a basal curvature. The females of H. brasilianum e H. elegans are described for the first time. Species distribution is updated and enlarged with new records.

Os carboidratos são moléculas diversas e complexas que são empregadas por organismos vivos em funções biológicas, como eventos energéticos, estruturais e de sinalização. L-Fucose é um monossacarídeo presente em diversos grupos biológicos, como mamíferos, insetos e plantas. Umas das modificações póstraducionais mais conhecidas contendo L-Fucose são os antígenos do sistema sanguíneo ABO e o leite humano. Alterações no padrão de fucosilação estão relacionadas a patologias como câncer e fucosidose. Essas alterações estão relacionadas ao balanço entre as atividades de &alpha;-L-fucosidases e fucosiltransferases. As -L-fucosidases são glicosídeo hidrolases que catalisam a hidrólise de ligações entre resíduos de L-Fucose ligados a outras moléculas. Fucosiltransferases são glicosiltransferases que transferem L-Fucose de GDPfucose para um substrato receptor específico. Embora a importância do metabolismo da fucose, existem poucas informações sobre este assunto em Arthropoda. A literatura indica que fucose, &alpha;-L-fucosidases e fucosiltransferases estão envolvidas na interação parasita-hospedeiro em carrapatos, sugerindo que o metabolismo da fucose é essencial para Arachnida. Nosso objetivo foi estudar o metabolismo de fucose em duas espécies de Arachnida: a aranha Nephilingis cruentata e o carrapato Amblyomma sculptum. Ele foi realizado através da caracterização das fucosidases nativas e recombinantes, estrutura e análise in silico, mutagênese sitio-dirigida, padrão de expressão, especificidade e efeito nas células tumorais. Além disso, analisamos as sequências de fucosiltransferases e a expressão por qPCR. As enzimas envolvidas em caminhos metabólicos de fucose também foram investigadas. NcFuc e AsFuc têm um pH ótimo de 5, são inibidas por fucose e fuconojirimicina e apresentam processo de oligomerização dependente de pH. Nós produzimos com sucesso as formas recombinantes dessas enzimas, e elas apresentam as mesmas propriedades cinéticas das formas nativas. A hidrólise de substratos naturais por NcFucr e AsFucr sugerem especificidades diferentes, e ambas conseguiram remover resíduos de fucose de celulares tumorais, reduzindo a invasão celular. Além disso, elas catalisaram reações de transfucosilação. A produção recombinante permitiu a identificação dos resíduos D214 e E59 como díade catalítica em NcFuc. As análises filogenéticas, os dados cinéticos, a modelagem molecular e a especificidade sugerem que os sítios ativos das &alpha;-Lfucosidases são diferentes em cada espécie de Arachnida e indicaram que o significado fisiológico da remoção de fucose é diferente entre os organismos. Os ensaios de qPCR evidenciaram que, embora as &alpha;-L-fucosidases possam ser enzimas lisossômicas, elas são principalmente expressas no sistema digestório em Arachnida e estão envolvidas na digestão. Representantes de todas as famílias conhecidas de fucosiltransferases foram identificados nos dados do transcriptoma de aranha. No entanto, POFUT1 também foi identificado no nível proteômico e sua análise de expressão indicou uma maior expressão no MG. Isso pode estar relacionado à regeneração de células após a secreção de enzimas digestivas. A análise transcriptômica e proteômica indica que o Arachnida usa vias salvage e de novo para a síntese de fucose. Considerando todos os dados obtidos, concluímos 11 que o metabolismo da fucose está relacionado à digestão em Arachnida, uma vez que eles podem obter a fucose da dieta devido à presença de &alpha;-L-fucosidases muito ativas. / Carbohydrates are diverse and complex molecules being employed by living organisms in biological functions such as energetic, structural and signalling events. L-Fucose is a monosaccharide component of many glycans present in a variety of biological groups, such as mammals, insects, and plants. Some of the best-known examples of post-translational modified molecules containing L-Fucose are the ABO blood antigen system and human milk. Changes in the fucosylation pattern are related to pathologies like cancer and fucosidosis. These changes are related to the balance between the activities of &alpha;-L-fucosidases and fucosyltransferases. &alpha;-Lfucosidases are glycoside hydrolases that catalyse the hydrolysis of glycosidic bonds between residues of L-Fucose to other molecules. Fucosyltransferases are glycosyltransferases which transfer L-Fucose from a GDP-fucose to a specific acceptor. Although the importance of fucose metabolism, there is few information about this subject in Arthropoda. Literature indicates that fucose, &alpha;-L-fucosidases and fucosyltransferases are involved in host-pathogen interaction in ticks, suggesting that fucose metabolism is essential to Arachnida. Our aim was to study the metabolism of fucose in two Arachnida species: the spider Nephilingis cruentata and the tick Amblyomma sculptum. This was accomplished through the characterization of native and recombinant fucosidases, structure and in silico analyses, site-directed mutagenesis, expression pattern, specificity and, effect on tumour cells. Besides that, we analysed fucosyltransferases sequences and expression by qPCR. The enzymes involved in fucose metabolic pathways were also investigated. NcFuc and AsFuc have a pH optimum of 5.0, are competitively inhibited by fucose and fuconojirimycin and present an oligomerisation process pH dependent. We successfully produced the recombinant form of these enzymes, and they have the same kinetic properties of native forms. Natural substrate hydrolysis by NcFucr and AsFucr suggest different specificities and they were able to remove fucose residues from tumour cell lines, reducing cell invasion. Moreover, they catalysed transfucosylation reactions. The recombinant production allowed the identification of the residues D214 and E59 as the catalytic dyad in NcFuc. Phylogenetic analysis, kinetic data, molecular modelling, and specificity assays suggest that &alpha;-L-fucosidase active sites are different to each Arachnida species and indicated that the physiological significance of fucose removal is different among organisms qPCR assays evidenced that although fucosidases might be lysosomal enzymes, they are mainly expressed at the digestive system in Arachnida and are involved in digestion. Representatives of all known families of fucosyltransferases were identified in the spider MG transcriptome data. However, POFUT1 was also identified at the proteomic level and its expression analysis indicated a higher expression at MG. This might be related to the regeneration of cells after secretion of digestive enzymes. Transcriptomic and proteomic analysis indicate that Arachnida uses both salvage and de novo pathways to fucose synthesis. Considering all the obtained data we concluded that fucose metabolism is related to digestion in Arachnida since they are able to salvage fucose from diet due to the presence of very active &alpha;-L-fucosidases.

Barychelidae is a family of mygalomorph spiders that has been typically considered as consisting of three subfamilies (Barychelinae, Sasoninae and Trichopelmatinae). The subfamily Trichopelmatinae, however, has also been considered as potentially belonging to Theraphosidae. Lack of information about this subfamily has compounded many problems in the understanding of its systematic standing. Therefore, a taxonomic revision and cladistics analysis of the subfamily is presented, vying to resolve the relationships within this group. The study also aims to: redescribe the type material, provide pictures for the type material, analyze specimens from several collections, and possibly describing new species and/or unknown male or female individuals, and develop a taxonomic key of Trichopelmatinae. A cladistics analysis was performed, including all the species of Trichopelmatinae, in addition to some species of Barychelidae, Theraphosidae, Paratropididae and Nemesiidae. The data matrix with 60 taxa and 95 characters was analyzed with implied character weighting, in which six different values of concavities (k) were used. The chosen cladogram was the one obtained with the values of k for 4, 5 and 6, as they showed the shortest cladogram length and highest fit number. The results presented show that Trichopelmatinae is a monophyletic group, which is now comprised of three genera (Psalistops Simon, 1889, Reichlingia (Rudloff, 2001) and Trichopelma Simon, 1888). Additionally, Trichopelmatinae are herein transferred to Theraphosidae. Several species are synonymized: P. montigena Simon, 1889, P. tigrinus Simon, 1889 and P. zonatus Simon, 1889 with P. melanopygius Simon, 1889; T. corozalis (Petrunkevitch, 1929) with T. insulanum (Petrunkevitch, 1926); P. maculosus Bryant, 1948 with P. fulvus Bryant, 1948; P. opifex (Simon, 1889) and P. solitarius (Simon, 1889) with Schismatothele lineata Karsch, 1879. The following transfers are also done: P. fulvus, P. hispaniolensis Wunderlich, 1988, P. venadensis Valerio, 1986 andP. steini (Simon, 1889) to Trichopelma; P. gasci Maréchal, 1996 to Hapalopus Ausserer, 1875; T. astutum Simon, 1889 to Euthycaelus Simon, 1889; T. maddeni Esposito & Agnarsson, 2014 to Holothele Karsch, 1879; T. flavicomum Simon, 1891 and T. illetabile Simon, 1888 to the subfamily Sasoninae. The species T. illetabile, P. nigrifemuratus Mello-Leitão, 1939, T. spinosum (Franganillo, 1926), T. scopulatum (Fischel, 1927) and T. eucubanum Özdikmen & Demir, 2012 are considered as nomina dubia. Moreover, 1 new species of Psalistops (P. sp. nov. 1) and 11 new species of Trichopelma (T. sp. nov. 1, T. sp. nov. 2, T. sp. nov. 3, T. sp. nov. 4, T. sp. nov. 5, T. sp. nov. 6, T. sp. nov. 7, T. sp. nov. 8, T. sp. nov. 9, T. sp. nov. 10 and T. sp. nov. 11) are described. Both genera have their distribution mapped and new occurrences documented. The results of the analysis showed that the revision of Trichopelmatinae allowed for a better understanding of its systematic standing and also provided with some important information about the families Barychelidae and Theraphosidae. This highlights that a more comprehensive cladistics analysis, with even more representatives from all the included families would potentially help resolve and define better the systematic standing of both families. / Barychelidae é uma família de aranhas migalomorfas que contém tipicamente três subfamílias (Barychelinae, Sasoninae e Trichopelmatinae). A subfamília Trichopelmatinae, entretanto, também já foi considerada como pertencendo à Theraphosidae. Falta de informações sobre essa subfamília acarreta em vários problemas no entendimento de sua posição sistemática. Para tentar resolver essa questão, a revisão taxonômica e análise cladística da subfamília são aqui apresentadas, de froma a colaborar no entendimento dos relacionamentos dentro desse grupo. O estudo também pretende: redescrever o material tipo, fornecer imagens do material tipo, analisar espécimes de diversas coleções, e possivelmente descrever novas espécies e/ou indivíduos machos ou fêmeas desconhecidos, assim como desenvolver chave taxonômica de Trichopelmatinae. Foi realizada análise cladística incluindo todas as espécies de Trichopelmatinae, além de algumas espécies de Barychelidae, Theraphosidae, Paratropididae e Nemesiidae. A matriz de dados com 60 táxons e 95 caracteres foi analisada com pesagem de caráter implícita, em que 6 diferentes valores de concavidades (k) foram utilizados. O cladograma escolhido foi aquele obtido com as concavidades 4, 5 e 6, pois eles demonstraram os cladogramas mais curtos e maior valor de fit. Os resultados aqui apresentados mostram que Trichopelmatinae é um grupo monofilético, que agora é composto por três gêneros, (Psalistops Simon, 1889, Reichlingia (Rudloff, 2001) e Trichopelma Simon, 1888). Adicionalmente, as espécies de Trichopelmatinae são transferidos para Theraphosidae. Várias espécies são sinonimizadas: P. montigena Simon, 1889, P. tigrinus Simon, 1889 e P. zonatus Simon, 1889 com P. melanopygius Simon, 1889; T. corozalis (Petrunkevitch, 1929) com T. insulanum (Petrunkevitch, 1926); P. maculosus Bryant, 1948 com P. fulvus Bryant, 1948; P. opifex (Simon, 1889) e P. solitarius (Simon, 1889) com Schismatothele lineata Karsch, 1879. As seguintes transferências também são feitas: P. fulvus, P. hispaniolensis Wunderlich, 1988, P. venadensis Valerio, 1986 e P. steini (Simon, 1889) para Trichopelma; P. gasci Maréchal, 1996 para Hapalopus Ausserer, 1875; T. astutum Simon, 1889 para Euthycaelus Simon, 1889; T. maddeni Esposito & Agnarsson, 2014 para Holothele Karsch, 1879; T. flavicomum Simon, 1891 e T. illetabile Simon, 1888 para a subfamília Sasoninae. As espécies T. illetabile, P. nigrifemuratus Mello-Leitão, 1939, T. spinosum (Franganillo, 1926), T. scopulatum (Fischel, 1927) e T. eucubanum Özdikmen & Demir, 2012 são consideradas como nomina dubia. Além disso, 1 nova espécie de Psalistops (P. sp. nov. 1) e 11 novas espécies de Trichopelma (T. sp. nov. 1, T. sp. nov. 2, T. sp. nov. 3, T. sp. nov. 4, T. sp. nov. 5, T. sp. nov. 6, T. sp. nov. 7, T. sp. nov. 8, T. sp. nov. 9, T. sp. nov. 10 and T. sp. nov. 11) são descritas. Espécies de ambos os gêneros têm suas distribuições mapeadas e novas ocorrências documentadas. Os resultados da análise demonstraram que a revisão de Trichopelmatinae permitiu um melhor entendimento de seu posicionamento sistemático e também forneceu algumas informações importantes sobre as famílias Barychelidae e Theraphosidae. Isso demonstra que uma análise cladística mais abrangente, com mais representantes de todas as famílias incluídas, poderia ajudar a resolver e definir melhor a sistemática de ambas as famílias.

Spider silk is a biodegradable and biocompatible natural material that is stronger than steel and more elastic than nylon. These properties make spider silk a desirable material for many commercial products, ranging from textiles to biomedical materials. Due to spiders’ cannibalistic and territorial nature it is impossible to farm them to produce spider silk at a high enough yield to meet product demands. Therefore, a bioengineered synthetic process is necessary to produce spider silk. Synthetic spider silk has been produced in bacteria, goats, yeast, plants, mammalian cells and silkworms, but none of these processes provided a commercially viable yield or were able to express recombinant spider silk proteins (rSSps) that can mechanically imitate the natural spider silks. The overall goal of this research was to increase the yield and mechanical characteristics, e.g. strength and elasticity, to create a commercially viable spider silk. Three different hosts were used: E. coli, alfalfa and an insect cell line. Each host addresses issues with synthetic protein production in both the short-term and long-term scheme. Through this research yields were increased, while the mechanical properties of the synthetic silks were improved and groundwork for future research into the improvement of synthetic spider silk production were identified.

Spider silk has long been a subject of scientific research due to its remarkable mechanical properties. Until recently, there has been no way to effectively obtain spider silk except by harvesting it from individual spiders. With advances in technology, the genes that code for the individual spider silk proteins have been isolated and genetically engineered into other hosts to produce recombinant spider silk proteins (rSSp) of varying sizes, Larger rSSp have correspondingly greater mechanical properties in any resulting materials. Using current production methods, larger rSSp cannot be produced in commercially viable quantities while simultaneously being economically viable. The current production methods have shown that small rSSp are easier to produce and purify in genetically engineered systems while maintaining favorable yields. After the small molecular weight rSSp were expressed and purified, they were polymerized to form larger molecular weight rSSp, while having maintained mechanical properties of similarly sized rSSp from other expression systems. To accomplish this polymerization, two systems were designed that can catalyze this reaction: using a Spy System and an intein system. These two systems require no external cofactors or enzymes and occur spontaneously once initiated. The expression and purification of rSSp from both of these systems has been characterized. The Spy System did not produce high enough quantities of rSSp to be economically viable. Whereas the intein system produced yields of 5 g/L, which is higher than previously reported. The rSSp from the intein system have been made into biomaterials, such as films, hydrogels, and aerogels. The mechanical properties of these biomaterials were comparable to biomaterials from other spider silk protein production. Utilizing the intein system, projected cost estimates for the production of rSSp has been lowered from $350 to $40 per kilogram. This decreased cost of rSSp would allow a wider array of commercial applications.

Sub-Saharan Africa is home to nine described species of Dignomus Wollaston, 1862. Study and dissection of specimens has led me to the hypothesis that there are nine undocumented species in this region. Descriptions and images of the new species are presented and discussed, along with a compiled list of all described species from the Sub- Saharan region. The probable biology as geographic distributions for members of the genus are also given. Additionally, a phylogenetic analysis of 95 species of bostrichoids using CO1 molecular data was done with a focus on the origins of Dignomus and Pseudomezium. parsimony and bayesian analyses were run, the later providing evidence that Pseudomezium derived genus of Dignomus. Support was also found for a monophyletic Ptininae (i.e., the spider beetles) but not for the bostrichids, and anobiids. More data will be needed to clarify the relationships among the taxa of Bostrichoidea.

Spider-silk is known as one of the stronger natural materials, unfortunately it is impossible to farm spiders due to their territorial and cannibalistic nature. To address this issue, researchers have studied spider-silk to discover how it is produced in nature. From their results, spider-silk is composed of large sized proteins produced in two different cell types. Using this knowledge, researchers created transgenic organisms capable of producing spider-silk proteins in large quantities. Using these proteins, several groups have created fibers, films, hydrogels, and adhesives with robust and versatile properties. Wet-spinning is a technique commonly used to create fibers from spider-silk proteins. These fibers unfortunately do not compare to the mechanical properties of natural silk. To address this researchers have used a method known as electrospinning to create spider-silk fibers with substantially smaller diameters. In doing so, these electrospun fibers have increased surface area and enhanced mechanical properties. Using this method, our group has modified the electrospinner to be able to produce continuous fine diameter yarns composed of hundreds of nanofibers with mechanical properties surpassing that of natural silk. Fibers aside, spider-silk proteins can be used to create a variety of different biocompatible materials. To further enhance these materials, our group has utilized a technique traditionally used for observation. This technique employs a high intensity light source to initiate cross-links within the proteins. With this method, our spider-silk protein materials have increased their mechanical properties by a factor of seven. These materials can further be modified through post-treatments, resulting in tunable materials with diverse and robust mechanical properties.