Thesis (Ph. D.)--University of Wisconsin--Madison, 1982. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin, 1996. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M. Inst. Agrar.)(Animal Production)--University of Pretoria, 2006. / Includes summary. Includes bibliographical references. Available on the Internet via the World Wide Web.

Three strains of the green alga Scenedesmus quadricauda were selected to be specifically resistant to the presence of high concentrations of inorganic Se. The strain SeIV was found to be resistant to high doses of selenite, the strain SeVI was resistant to selenate, and the strain Se(IV+VI) to the presence of both Se compounds. It has been shown that both the dose and chemical form of Se are the critical factors in the cellular response. In this PhD. thesis are results from experiments with the resistant strains (activity of thioredoxin reductase, content of selenium and selenomethionine, effect of sulphur deficiency).

Made available in DSpace on 2014-06-11T19:23:59Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-12-05Bitstream added on 2014-06-13T18:20:02Z : No. of bitstreams: 1 fonseca_la_me_botfmvz.pdf: 1011021 bytes, checksum: fb95abcb9e3e92fdfd7d1fea74329e0f (MD5) / Outros / Animais de policiamento possuem alterações no ritmo de cortisol condizente com uma situação de estresse crônico, portanto, avaliou-se a influência da atividade de policiamento urbano antes e após a suplementação com vitamina E, selênio e cromo sobre parâmetros hematológicos, bioquímicos e hormonais. O experimento foi realizado no Regimento de Polícia Montada da Polícia Militar, localizado no Município de Serra-ES. Foram utilizados 22 eqüinos adultos, todos mestiços da raça Crioula, machos, com idades entre dez e vinte anos. Todos os animais foram mantidos em semelhantes condições de estabulação, alimentação e manejo higiênico-sanitário. Cada animal recebia uma dose diária de 2,8mg/400kg de peso vivo de selênio e 2.000 UI/400kg de peso vivo de vitamina E, ou 11mg/400kg de peso vivo de cromo, via oral, seguindo normas da National Research Council (NRC), 2007, durante 30 dias. Foram analisadas as atividades séricas das enzimas marcadoras de lesão muscular (CK, AST e LDH), de cortisol e insulina, glicose e lactato plasmáticos, além dos parâmetros hematológicos dos animais em repouso e após o exercício. Concluiu-se que os cavalos submetidos à atividade de policiamento sofrem os efeitos do exercício físico, refletidos pelo aumento na atividade sérica da CK e AST, na concentração plasmática de lactato e glicose e na diminuição dos valores de insulina. Concluiu-se ainda que a suplementação com vitamina E e selênio contribuiu para a diminuição do valores médios de CK, cortisol e lactato e que a suplementação com cromo contribuiu para a diminuição do valores médios de lactato e insulina. A suplementação contribuiu ainda para uma melhor adaptação dos animais a atividade física do policiamento urbano e os fatores externos que levam o animal a situação de estresse crônico. / Policing animals have changes in rate of cortisol compatible with situation of chronic stress. The influence of activity policing urban before and after the vitamin E, selenium and chrome supplementation on hematological, biochemical and hormonal parameters were evaluated. The experiment was carried out in Regimento de Polícia Montada da Polícia Militar, located in Serra- ES. Were used, 22 equines, adults, cross Crioula, male, between 10 and 20 years old. All animals were kept in similar conditions of stable, food and healthhygienic management. Each animal received 2,8mg/400kg live weight of selenium and 2000UI/400kg live weight of vitamin E, or 11mg/400kg of chromium live weight, oral, following the rules of National Research Council (NRC), 2007, during 30 days. Were analyzed the serum activities of injury muscle markers (CK, AST and LDH), cortisol and insulin, plasma glucose and lactate and hematological parameters of animals at rest and after the exercise. It was concluded that the horses submitted to the activity of policing suffer the effects of physical exercise, reflected by the increase in activity of serum CK and AST, and plasma lactate and glucose and decrease of insulin. It was concluded that the supplementation with selenium and vitamin E contributed to the decrease serum cortisol, plasma lactate and CK serum activities and supplementation with chromium contributed to the decrease the values of plasma lactate and insulin. In addition supplementation contributed to better adaptation of the animals to physical activity policing urban and external factors that take the animal the situation of chronic stress.

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Please read the abstract in the dissertation. / Dissertation (MSc Agric)--University of Pretoria, 2013. / gm2014 / Animal and Wildlife Sciences / unrestricted

Runoff and effluent discharge from mining activities has resulted in elevated concentrations of selenium in aquatic ecosystems. Bioavailability is dependent on chemical speciation. Although dissolved inorganic Se species are not directly toxic to organisms, uptake by primary producers and subsequent biotransformation to organo-selenium species substantially increase risk and bioaccumulation potential, potentially impairing reproduction in high-order organisms. The effects of dietary selenium exposure were assessed in two aquatic invertebrates: Ceriodaphnia dubia and Chironomus dilutus. Two generations of these organisms were exposed to seleniferous algae grown in 0-40 μg L-1 selenate. Dissolved selenate was readily absorbed and concentrated by algal species Pseudokirchneriella subcapitata and Chlorella kesslerii. Se had no effect on survival at treated concentrations. Dietary selenium exposures had little effect on reproductive endpoints in either invertebrate species, suggesting that invertebrates have the ability to regulate chronic Se exposures from dietary sources. These results provide valuable information concerning the effects of dietary selenium in aquatic invertebrates.

Methylmercury (MeHg) is a ubiquitous contaminant and potent neurotoxicant with no completely effective therapy, although selenium antagonises MeHg toxicity. Furthermore, nanoparticles are promising as a novel drug delivery system. We researched the potential of selenium nanoparticles (SeNPs) in antagonising MeHg neurotoxicity compared to selenomethionine (SeMet) using primary astrocyte cell cultures and examining outcomes related to oxidative stress. We found that SeNPs were more toxic than SeMet. Increasing SeNPs significantly decreased MeHg cellular uptake and MeHg significantly decreased uptake of SeNPs at the highest concentration. Finally, SeNPs alone produced significantly higher reactive oxidative species and altered the ratio of reduced-to-oxidised glutathione, but MeHg, SeMet, and co-exposures did not. There were no significant effects on glutathione peroxidase or reductase activity. This suggests that SeNPs are more toxic than MeHg in cerebellar astrocytes and that they may not be suitable as a therapy at the doses and formulation used in this research.