Tobacco is an important crop in South Africa. The genetic basis of tobacco breeding is very narrow and cultivars are closely related. The production of new tobacco hybrids with novel characteristics through classical breeding techniques is difficult. Genetic engineering could assist plant breeders to introduce new herbicide, disease and pest resistance traits into existing proven cultivars. Plant genetic engineering has not previously been applied to the improvement of South African commercial tobacco cultivars. Agrobacterium-mediated leaf disc transformation was used to create transgenic tobacco plants from South African commercial tobacco cultivars TL33, J6 and 20/19. The cultivar samsun was also used to create transgenic plants. The Agrobacterium tumefaciens helper strain C58C1 (pGV2260) containing the binary vector pJIT119 was used to carry out the transformation. As well as the leaf disc transformation method, other methods of obtaining transgenic tobacco plants were explored. These methods included the use of Agrobacterium-mediated transformation of tobacco cell cultures and direct DNA-mediated transformation of tobacco protoplasts. The vector pJIT119 encodes the uidA gene for the β-glucuronidase (GUS) enzyme, the nptl/ gene for neomycin phosphotransferase (NPTII) and the sul I gene for the dihydropteroate enzyme conferring asulam resistance. The presence and expression of these three foreign genes uidA , npt/l and sul I from pJIT119 in transgenic tobacco plants was confirmed by a variety of experimental approaches, including the culture of transgenic plants on medium containing kanamycin or asulam, the GUS histochemical assay, the neomycin phosphotransferase assay, DNA dot-blot analysis, in situ hybridization, computerized image analysis, polymerase chain reaction and progeny analysis. A detailed analysis of individual transgenic plants is necessary in order to select those plants which express the foreign genes maximally. Only these plants would be given to plant breeders for field trial assessment. A high level of foreign gene inactivation was observed in transgenic tobacco plants obtained from the Agrobacterium-mediated leaf disc transformation method. Approximately 20% of the original transgenic plants were discarded as "escapes" as they contained a defective npt/l gene. The remaining kanamycin resistant plants, however, had inactive copies of either the sul I or the uidA gene, or both. The use of in situ hybridization and the polymerase chain reaction (PCR) helped to explain the foreign gene inactivation. The lack of foreign gene expression in individual transgenic plants was not due to the physical loss of entire foreign genes, DNA methylation or the position effect. The lack of expression was due to possible T-DNA rearrangements or deletions which disabled certain genes carried on the T-DNA. Transcription and translation of these foreign genes occurred, but the final uidA and sul I gene products (β-glucuronidase and dihydropteroate synthase, respectively) were possibly defective and did not confer GUS activity or asulam resistance on the transgenic plants The tissue specific activity of the uidA gene under the control of the cauliflower mosaic virus (CaMV) 358 promoter was studied. In the vegetative structures of transgenic tobacco plants, the uidA gene activity was located within the cells surrounding the vascular traces and within the glandular hairs. The effects of stress on 358 promoter activity was also investigated. Chemical and nutrient stess in vitro did not have a significant effect to decrease uidA gene expression under 358 promoter control. Foreign gene expression (uidA) under CaMV 358 promoter control may be enhanced by in vitro stress. Oxygen stress (anaerobic culture under waterlogged conditions) induced uidA expression in areas of the plant which usually did not show usual tissue specific patterns of uidA expression. The stage of differentiation in tissue culture when compared to the mature hardened off transgenic plant, also had an effect on the amount of uidA gene expression. Mature hardened off plants expressed less GUS activity than immature in vitro plants. The tissue specific pattern of foreign gene expression under CaMV 358 promoter direction was conserved in the reproductive structures of transgenic tobacco plants. In floral organs, the pattern of uidA gene expression was essentially the same as that found in vegetative tissues. In all floral organs examined, uidA expression was found associated with the vascular system and within the glandular hairs. The uidA gene with a CaMV 358 promoter was not expressed in pollen. Because of the ease of transformation of tobacco, it is possible that genes for pharmaceutically valuable proteins and peptides could be expressed in tobacco, for agricultural scale fine chemical production("pharming"). This could be of economic advantage for the survival of tobacco as a commercial agricultural crop in the future when tobacco smoking is no longer popular. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1994.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-03-03T12:02:25Z No. of bitstreams: 1 ricardosilvacampos.pdf: 2339851 bytes, checksum: 393ac64fca56412bb1c699c3db8a0c70 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-03-06T20:05:36Z (GMT) No. of bitstreams: 1 ricardosilvacampos.pdf: 2339851 bytes, checksum: 393ac64fca56412bb1c699c3db8a0c70 (MD5) / Made available in DSpace on 2017-03-06T20:05:36Z (GMT). No. of bitstreams: 1 ricardosilvacampos.pdf: 2339851 bytes, checksum: 393ac64fca56412bb1c699c3db8a0c70 (MD5) Previous issue date: 2011-08-29 / A modelagem da eletrofisiologia cardíaca é uma importante técnica para compreender e reproduzir o fenômeno de propagação de ondas elétricas no coração. Cada onda é chamada de potencial de ação e é responsável pela sincronização dos batimentos cardíacos. Este potencial depende de vários fatores, como a capacitância da membrana celular e concentrações de diferentes íons nos meios intra e extracelulares. Tipicamente, estes componentes podem ser representados por circuitos elétricos, que podem ser descritos por equações diferenciais ordinárias. Entretanto, o processo de geração do potencial de ação é complexo e de natureza não-linear. Para simulá-lo através de experimentos in silico, é necessário descrevê-lo através de dezenas de equações e parâmetros. Além disto, é necessário resolver as equações por meio de métodos numéricos eficientes. Visando auxiliar este processo de modelagem, este trabalho possui dois objetivos: 1) desenvolver uma ferramenta para descrever modelos computacionais que funcione através da Web e permita a edição de arquivos CellML { um padrão XML desenvolvido para descrever modelos celulares; 2) aprimorar os métodos numéricos utilizados pela ferramenta AGOS, que transforma CellML em um arquivo C++ que permite a simulação dos modelos. Diferentes métodos de passo de tempo adaptativo foram implementados e os algoritmos foram paralelizados via OpenMP. Esses métodos e técnicas computacionais foram comparados aos já então amplamente adotados pela área, métodos de Euler e BDF, avaliação parcial e Lookup- Tables, para a simulação de quatro diferentes modelos de células cardíacas. Os resultados mostraram que os métodos adaptativos combinados com as técnicas computacionais podem ser até 100 vezes mais velozes do que o método de Euler. / Cardiac electrophysiology modeling is an important technique for studying and simulating the electrical wave propagation on cardiac tissue. The electrical wave initiates and propagates as a pulse that is known as action potential. The action potential is responsible for synchronizing the contraction and relaxation of the cardiac cells during a heartbeat. The cellular components and functions involved in the generation of an action potential are typically described by sets of ordinary differential equations. In-silico experiments of this complex phenomenon involve the description of the mathematical model and its numerical resolution. In this respect, this work targets two different goals. First, we have implemented a Web tool to create and edit cellular components and mathematical equations, based on a XML standard named CellML. The second goal is to improve the numerical resolution of models described in CellML. To this end we implemented different improvements to a previously published tool called AGOS. AGOS translates a CellML file to a C++ code that can be used for the numerical resolution of the model via the Euler or BDF methods. In this work, we have improved the numerical methods of AGOS by implementing and testing two different ways to adapt the time step. In addition, we have implemented a parallel version of the numerical solvers based on OpenMP directives, and added two numerical techniques known as Partial Evaluation and Lookup Tables to AGOS. We compared these computational techniques in terms of execution time, memory consumption and numerical error. Our preliminary results suggest that the adaptive time step methods combined with OpenMP or Lookup Tables and Partial Evaluation can be 100 times faster than the originally implemented Euler Method.

This Bachelor?s Thesis concerns 20 points at the MDA educational program (People, Computers and Work) at Blekinge Institute of Technology in Ronneby. The MDA educational program focuses on how people use Information Technology and its design and development. Volvo Car Corporation is looking at the future possibilities of their development of their Drivers Information Module, DIM . Today all their instruments are analogical and as time go by, new features are added in the car. This overflow of instruments and information is more likely to confuse the driver than to assist him. Instead Volvo wants to focus on showing only the relevant information for the driver. So Volvo is designing a new Drivers Information Module, which works like a computer monitor. This gives a new perspective on how to show information for the driver. Our goal in this project is to give ideas on how the information can be displayed in this new version of the DIM and in what situations.