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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
81

Effect of Oxygen Concentration and Promoters on the Performance of Copper Catalysts During Catalytic Reduction of Nitrogen Monoxide

Liu, Kai-Chung 14 September 2001 (has links)
This study utilized Cu-catalysts to catalyze a NO reduction reaction using CH4 as a reductant. Due to CH4 being a weak reductant and is easily affected by O2 concentration, we undertook a series experiments with O2 concentration and promoters, so that we could better understand their influence. The experiment conditions were as follows : reaction temperature between 150¢J- 800¢J¡Fa catalysts weight of 0.5 g¡F total gas flow rate of 1000 ml/min¡Frelative humidity at 0.9 %¡Fan O2 concentration between 0 - 6%¡Fand CH4 concentration between 1000 - 10000 ppm. First, we sorted out the best metal carriers and calcining temperature, from this we decide to use £^-Al2O3 as a carrier with a calcining temperature under 500¢Jto produce our catalysts. During the O2 concentration experiment, when the inflow O2 concentration was below 1% (including 0% O2), Cu-catalysts reduce NO above 550¢J.The conversion reached a rate of 95 % at a temperature of 750¢J¡Fwhen the oxygen concentration was between 3% and 6% O2, catalysts reacted within 300 - 500¢J with NO converting to NO2¡Fat a concentration between 1.5% and 2% O2, NOx underwent reduction at 750¢J,and NOx conversion raised from 0 % to above 90%. Therefore in analyzing the experiment results, it shows that NOx will reduce violently when the O2 concentration is below 0.7% and while using CH4 as a reductant. This result was also apparent in O2 concentrations between 1.5 % and 2%. In the experiments of M/O ratio (the ratio of CH4 and O2 inflow), we found M/O ratio was not a deciding factor within the reaction mechanics, furthermore the limiting factor of O2 concentration decreases under 0.7%¡Fin addition it was also found that adding large amounts of CH4 could quicken the reduction process. Lastly, a mass balance was performed, which had a result over 70 %. In the experiments where Y¡BLa¡BSr¡BCo were added as promoters to the Cu-catalysts, we found that Cu-La/£^-Al2O3¡BCu-Sr/£^-Al2O3 and Cu-Co/£^-Al2O3 can accelerate O2 depletion. Henceforth, it is possible to deduce promoters will be a useful method in solving O2 limiting. In the comparison of metals loading methods, we found no difference in activity using separate-impregnation and co-impregnation methods, whereas in the BET and SEM co-impregnation experiments, there was a larger surface-area and dispersion.
82

Epigenetic regulation of the human genome by transposable elements

Huda, Ahsan 07 July 2010 (has links)
Nearly one half of the human genome is composed of transposable elements (TEs). Once dismissed as 'selfish' or 'junk' DNA, TEs have also been implicated in a numerous functions that serve the needs of their host genome. I have evaluated the role of TEs in mediating the epigenetic mechanisms that serve to regulate human gene expression. These findings can be broadly divided into two major mechanisms by which TEs affect human gene expression; by modulating nucleosome binding in the promoter regions and by recruiting epigenetic histone modifications that enable them to serve as promoters and enhancers. Thus. the studies encompassed in this thesis elucidate the contributions of TEs in epigenetically regulating human gene expression on a global as well as local scale.
83

Design of substrate induced transcription for control of recombinant protein production in Escherichia coli

Boström, Maria January 2004 (has links)
No description available.
84

Regulation of the human neuronal nitric oxide synthase gene via alternate promoters

Hartt, Gregory Thomas, January 2003 (has links)
Thesis (Ph. D.)--Ohio State University, 2003. / Title from first page of PDF file. Document formatted into pages; contains xii, 152 p. : ill., (some col.). Includes abstract and vita. Advisor: Anthony Young, Molecular, Cellular, and Developmental Biology Program. Includes bibliographical references (p. 137-150).
85

Tissue-specific gene expression and promoter characterization in triticale

Penniket, Carolyn Renee January 2013 (has links)
Triticale (x Triticosecale Whitm.) is a cereal with favorable agronomic traits for a Canadian bioproduction platform crop. Appropriate tissue sampling times were determined and gene expression profiles were evaluated in five triticale seed tissues and eleven vegetative tissues using the Affymetrix Wheat GeneChip®. Genes that were expressed, not expressed, tissue-specific, tissue-enriched and developmentally regulated were identified. The percentage of probe sets on the wheat GeneChip with gene ontology annotations was improved from less than 3% to over 76% using homologous sequence identification and annotation transfer. This information was used to determine functions and processes over-represented within the identified gene lists and provide biological meaning to the results. Expression of candidate genes was further evaluated using qRT-PCR, RNA in situ hybridization and promoter characterization. This study has provided a comprehensive triticale gene expression atlas; knowledge regarding triticale development, gene function, expression and regulation; and tools enabling further triticale research and development. / xxiii, 425 leaves : col. ill. ; 29 cm
86

A Q-sort analysis of how sports information directors of universities in the Mid-American Conference relate to Grunig's four public relations models

Graham-Reinhardt, Tamu January 1998 (has links)
This study attempted to examine the public relations activities of sports information departments of universities within the Mid-American conference. The activities were categorized according to James E. Grunig and Todd Hunt's four public relations models.The researcher provided ten sports information directors with thirty-six statements regarding various public relations activities which a public relations department would perform. Each respondent was asked to sort the responses according to how they perceived public relations activities were carried out within their respective departments.The Q-method program was used to determine two factor groups from the ten responses received. Factor I consisted of nine sports information directors and Factor II consisted of one sports information director.While sports information directors in both groups agreed that truth is important in a public relations program (a public information model), the two groups differed significantly in the types of public relations activities they carried out. Factor I respondents perceived their departments as performing a more press agentry/publicity style of public relations (model 1). The Factor II respondent perceived his department more along the lines of two-way asymmetric and two-way symmetric public relations (models 3 and 4). Neither of the two groups practiced each of these models exclusively but rather practiced one dominant form of public relations while using the other models to a lesser extent. / Department of Journalism
87

Synergistic use of promoter prediction algorithms: a choice of small training dataset?

Oppon, Ekow CruickShank January 2000 (has links)
<p>Promoter detection, especially in prokaryotes, has always been an uphill task and may remain so, because of the many varieties of sigma factors employed by various organisms in transcription. The situation is made more complex by the fact, that any seemingly unimportant sequence segment may be turned into a promoter sequence by an activator or repressor (if the actual promoter sequence is made unavailable). Nevertheless, a computational approach to promoter detection has to be performed due to number of reasons. The obvious that comes to mind is the long and tedious process involved in elucidating promoters in the &lsquo / wet&rsquo / laboratories not to mention the financial aspect of such endeavors. Promoter detection/prediction of an organism with few characterized promoters (M.tuberculosis) as envisaged at the beginning of this work was never going to be easy. Even for the few known Mycobacterial promoters, most of the respective sigma factors associated with their transcription were not known. If the information (promoter-sigma) were available, the research would have been focused on categorizing the promoters according to sigma factors and training the methods on the respective categories. That is assuming that, there would be enough training data for the respective categories. Most promoter detection/prediction studies have been carried out on E.coli because of the availability of a number of experimentally characterized promoters (+- 310). Even then, no researcher to date has extended the research to the entire E.coli genome.</p>
88

Exogenous gene expression from heterologous promoters in fish cell cultures

Sharps, Angela 10 June 1992 (has links)
Cell culture systems have provided many insights into eukaryotic gene expression and other biochemical mechanisms. Since the cell represents the smallest living unit of any organism it provides a desirable in vitro system, allowing biochemical studies without the complex physiology of an entire animal. However, processes involving intracellular mechanisms, such as development, aging or carcinogenis, eventually require the analysis of the intact organism. Transgenic animals are a very promising tool to approach questions of this magnitude. Fish in general and the zebrafish (Brachydanio rerio) in particular are an excellent model system for transgenic research, mainly due to their extramaternal fertilization and development and their short generation cycle throughout the year. The recent derivation of zebrafish cell lines has opened up possibilities for in vitro analysis of this popular model species, and expression of heterologous genes under the influence of promoter and other regulatory nucleic acid aequences. In contrast to mammalian expression systems, little nucleic acid sequences controlling gene expression in fish are known. Therefore we examined mammalian expression systems in fish cells in order to determine their efficiency quantitatively. Emphasis was given to zebrafish cultures with the goal of eventually injecting in vitro manipulated embryo cells into host embryos and thereby creating transgenic chimera. / Graduation date: 1993
89

Characterisation of an expression system for commercial production of proteins / by Lene Jorgensen.

Jorgensen, Lene, 1962- January 1997 (has links)
Bibliography: leaves 167-176. / xvi, 176 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / The aim of this thesis is to characterise a bacterial expression system for recombinant production of proteins with relevance to industry. Recombinant protein expression under control of stationary-phase inducible promoters is characterised, and the expression levels are quantitatively compared with those under control of IPTG-inducible promoters. A number of bacterial expression systems are constructed using promoter::cat transcriptional fusions. / Thesis (Ph.D.)--University of Adelaide, Depts. of Microbiology and Immunology and Chemical Engineering, 1997
90

Characterization and identification of transcription factors that bind to the tumor necrosis factor -308 polymorphism

Woo, Andrew Jonghan January 2003 (has links)
[Formulae and special characters can only be approximated. Please see the pdf version of this abstract for an accurate reproduction.] Tumor necrosis factor (TNF) is a pleiotropic cytokine that mediates a long list of immunological and pathophysiological processes. TNF is produced by a wide variety of cells including immune and non-immune cells, however in most cell types TNF is not expressed prior to stimulation. The function of TNF is mediated via its trimeric domain by binding to TNF receptors that are found on most types of cells, especially of the haematopoietic systems, hence transpiring its effects on a wide variety of cells and organ systems. The cytotoxic (apoptosis) and pro-inflammatory (differentiation, proliferation and activation) functions of TNF are protective but can also result in pathological or deleterious consequences. A biallelic G to A transition polymorphism in the promoter region of TNF at nucleotide position 308 from the transcription start site is suggested to be involved in differential transcriptional regulation of TNF expression. The high TNF producing 308A allele is associated with susceptibility to or worse outcome of many infectious diseases in addition to autoimmune and other pathophysiological conditions. A previous study in our laboratory observed a selective affinity towards the polymorphic 308A allele by an EMSA protein(s) complex, named E. Several other protein complexes were found along with complex E and one of them was identified as Sp1. The identification of complex E was unsuccessful but it was hypothesized to play a major role as transcriptional activator in 308A allele individuals hence transpiring its effect in various pathophysiological states. In this study, the EMSA complexes observed in the TNF promoter region between nucleotides 322 to 283, encompassing the 308 polymorphism, is characterized. EMSA using mutated oligonucleotides mapped the binding sites of complexes B, C, D and E. TRANSFAC database search in addition to previous work revealed the identity of complex C as Sp1 but the rest of complexes remained unknown. Moreover, in contrast to our previous study, the protein(s) in the complex E was found to preferentially bind 308G nucleotide hence posing as a transcriptional repressor, resulting in decreased production state of TNF in 308G allele individuals than 308A allele individuals. In order to characterize putative transcription factors binding to the promoter region, first the biochemical characteristics such as the effects of temperature, salts and cations on DNA binding ability of EMSA complexes were studied. EMSA complexes B, C, DI and E required cations, probably Zn+2, to bind DNA. By optimizing a technique that couples EMSA with SDS-PAGE, the molecular weight of C, DI and E was determined. A novel technique that couples EMSA with IEF determined the pI of complexes B, C, D, DI and E. Although a commonly used technique of identifying unknown DNA-binding protein of interest, Yeast One-Hybrid assay, did not identify complex E, the novel identification method involving chromatography, two-dimensional electrophoresis, EMSA, mass spectrometry and database interrogation successfully identified TNF EMSA complex E as transcription factor Ying Yang 1 (YY1). Supershift EMSA confirmed complex E as YY1. In addition, the supershift assay showed presence of Sp1 and Sp3 in complex C. Similarly, complex DI is identified as Sp3. The novel method in identifying DNA-binding proteins is particularly useful as this technique allows identification of protein seen in EMSA without the need of extensive identification process. YY1 binds to a 6 base pair sequence, 5? TTGAGG 3?, from nt 295 to 290 of TNF promoter. The loss of affinity in 308A allele is caused by transition of underlined G nucleotide to A. The determined and described molecular weight of YY1 in literature is 60 kDa while the theoretical weight is 45 kDa. Both the determined and theoretical pI of YY1 is 5.8. YY1 is a multifunctional transcription factor implicated in both positive and negative regulation of gene expression as well as in initiation of transcription. It is ubiquitously expressed in growing, differentiated, and growth-arrested cells. Although future experiment is yet to establish in vivo presence of YY1 in TNF promoter, our study so far provides convincing evidence that the putative transcription factor that has selective affinity towards 308G allele is indeed YY1.

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