Thesis (Ph.D.)--York University, 2008. Graduate Programme in Biology. / Typescript. Includes bibliographical references (leaves 203-228). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:NR39026

Thesis (Ph. D.)--University of Texas at Austin, 2003. / Vita. Includes bibliographical references. Available also from UMI company.

Not available / text

Thesis (M.S.)--University of Texas at El Paso, 2009. / Title from title screen. Vita. CD-ROM. Includes bibliographical references. Also available online.

Thesis--University of Michigan. / Without thesis statement. Bibliography: p. 250-266.

Thesis (M.F.A.)--University of North Texas, August, 2008. / Title from title page display. Includes bibliographical references.

Thesis (Ph.D.)--University of Texas at Arlington, 2009.

Thesis (M.S.)--California Polytechnic State University, 2009. / Title from PDF title page; viewed on September 22, 2009. Major professor: Emily Taylor, Ph.D. "Presented to the faculty of California Polytechnic State University, San Luis Obispo." "In partial fulfillment of the requirements for the degree [of] Master of Science in Biological Sciences." "June, 2009." Includes bibliographical references (p. 48-57). Also available on microfiche.

The crotoxin complex protein is the major neurotoxic component in the venom of the Brazilian rattlesnake, Crotalus durissus terrificus. The purified protein can be crystallized in the form of thin platelets (less than 500 Å thick) suitable for electron crystallography and image processing techniques. The unit cell dimensions of the crystal are a = 38.8 Å, b = 38.8 Å, c = 256 Å, and α = β = γ = 90°. These crystals can grow in layers. For a three-dimensional image reconstruction this necessitates the determination of the crystal thickness in order to combine information from low dose images of crystals of the same thickness. In the past, the highest resolution image (to 3.9 Å) recorded from a crotoxin complex crystal on the electron microscope was from a crystal embedded in glucose. However, since glucose cannot be removed in order to accurately determine the crystal thickness, a different embedding technique (amorphous ice embedding) and tried. It was determined that high resolution image information (to 3.9 Å) can be recorded from crotoxin complex crystals embedded in amorphous ice. Five images of crystals preserved in amorphous ice, all exhibiting resolution to at least 9 Å, were first processed by a global averaging method from which two-dimensional projection maps were calculated. These maps were not interpretable due to variations in the images as demonstrated by a second processing method. In the second processing method the images were divided into smaller areas, or patches, and these patches were averaged. The patchwork images produced from the second process indicate that there is variation across the original images. The most likely explanation for the variation is the bending, or lack of flatness, of the crystals on the grid. The determination of mass thickness of the crystals from optical density differences between the crystals and the carbon support in images of freeze-dried crystals was explored. It was found that this method could not determine the mass thickness of crotoxin complex crystals to within one layer (64 Å), but could clearly distinguish between one and three overlapping layers of freeze-dried purple membrane which was used as a test specimen.

Os acidentes ofídicos representam um problema de saúde pública nos países tropicais, sendo listada pela Organização Mundial de Saúde (OMS) com uma doença negligenciada. A manutenção de serpentes em cativeiro tornou-se uma alternativa para a obtenção do veneno para pesquisas imunológicas e produção de soro antiofídico. No Brasil, o gênero Crotalus é responsável por 10% dos acidentes ofídicos registrados e apresenta a maior taxa de letalidade, por volta de 1,0%. O Instituto Butantan, conta com o Laboratório de Herpetologia que desde a década de 60 mantém o programa de criação de serpentes em sistema intensivo. Muitas serpentes de vida livre que morrem pouco depois da chegada ao cativeiro, ou ainda na pós-captura, sofrem da “ síndrome de má adaptação ". Esta síndrome é caracterizada por anorexia, emagrecimento progressivo, fragilidade dos tecidos e maior susceptibilidade às infecções por microrganismos. Todas essas alterações ocorrem devido a imunossupressão desencadeada pelo estresse. Por esse motivo a presença de endo e ectoparasitos torna-se um problema na manutenção dos animais, pois além de provocar enfermidades, a presença dos parasitos interfere na produção de veneno, uma vez que sua quantidade e qualidade estão diretamente associadas à alimentação e saúde das serpentes. Por este motivo o objetivo da presente pesquisa foi determinar as alterações hematológicas, bioquímicas provocadas pela ação de endoparasitas em Crotalus durissus terrificus e correlacioná-las com as níveis plasmáticos de corticosterona para determinar se animais parasitados apresentam valores maiores de corticosterona do que animais sadios, outra intenção da pesquisa foi determinar as alterações anatomopatológicas provocadas pelos parasitos nas serpentes e ainda determinar quais os principais parasitos que acometem a espécie em questão. As alterações hematológicas observadas, estatisticamente significante ocorreram no VCM e HCM das serpentes indicando uma possível anemia regenerativa com recrutamento de células jovens. Os parâmetros bioquímicos mantiveram-se praticamente iguais entre os Grupos do estudo. Com relação a concentração plasmática de corticosterona, os animais parasitados apresentaram maiores valores basais em todas as coletas, evidenciando que animais parasitados são mais estressados e consequentemente mais susceptíveis à infecções. Alterações histopatológicas foram observadas em ambos os Grupos, mas apenas os animais parasitados apresentaram inflamações granulomatosas, congestão gástrica além da presença de parasitas no sistema digestório. Com relação a determinação dos parasitos, em nossa pesquisa utilizamos técnicas moleculares (PRC) para determinar quais gêneros são mais frequentes e encontramos 80% de parasitismo por ascarídeo do gênero Ophidascaris sp. / Snakebite accidents represent a public health problem in tropical countries, being listed by the World Health Organization (WHO) with a neglected disease. The maintenance of captive snakes has become an alternative for obtaining venom for immunological research and the production of anti-venom. In Brazil, the genus Crotalus is responsible for 10% of recorded ophidian accidents and has the highest lethality rate, around 1.0%. The Instituto Butantan, counts on the Laboratory of Herpetology that since the decade of 60 maintains the program of creation of snakes on captivity. Many free-living snakes that die shortly after arrival in captivity, or even post-capture, suffer from the ” maladaptation syndrome ” This syndrome is characterized by anorexia, progressive thinning, tissue fragility and greater susceptibility to infections by microorganisms. All of these changes occur due to stress-induced immunosuppression. For this reason, the presence of endo and ectoparasites becomes a problem in the maintenance of the animals, because in addition to causing diseases, the presence of parasites interferes in the production of venom, since their quantity and quality are directly associated with food and health of the animals. snakes Therefore, the aim of the present study was to determine the hematological, biochemical alterations caused by endoparasites in Crotalus durissus terrificus and to correlate them with plasma corticosterone levels to determine if parasitized animals present higher values of corticosterone than healthy animals, another The aim of the research was to determine the anatomopathological alterations caused by the parasites in the snakes and to determine the main parasites that affect the species in question. The observed hematological alterations, statistically significant, occurred in MVC and MCH of the snakes indicating a possible regenerative anemia with recruitment of young cells. The biochemical parameters remained practically equal between the study Groups. Regarding the plasma corticosterone concentration, the parasitized animals presented higher baseline values in all collections, showing that parasitized animals are more stressed and consequently more susceptible to infections. Histopathological changes were observed in both Groups, but only the parasitized animals presented granulomatous inflammation, gastric congestion and the presence of parasites in the digestive system. With regard to the determination of the parasites, in our research we used molecular techniques (PCR) to determine which genera are most frequent and found 80% of parasitism per ascarid of the genus Ophidascaris sp.