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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.
41

Identification and Localization of Quantitative Trait Loci (QTL) and Genes Associated with Oil Concentration in Soybean [Glycine max (L.) Merrill] Seed

Eskandari, Mehrzad 13 December 2012 (has links)
Soybean [Glycine max (L.) Merr.] seed is a major source of edible oil in the world and the main renewable raw material for biodiesel production in North America. Oil, which on average accounts for 20% of the soybean seed weight, is a complex quantitative trait controlled by many genes with mostly minor effects and influenced by environmental conditions. Because of its quantitative nature, the seed oil concentration may have an indirect effect on other economically important and agronomic traits such as seed yield and protein concentration. Increasing the oil concentration in soybean has been given more attention in recent years due to increasing demand for both edible oil and feedstock. To achieve this objective, it is important to understand the genetic control of the oil accumulation and its relationship with other traits. The main objectives of this thesis were to identify quantitative trait loci (QTL) and genes involved in oil biosynthesis in soybean. Two recombinant inbred line (RIL) populations were developed from crosses between moderately high oil soybean cultivars with high seed yield and protein concentration. In a population of 203 F3:6 RILs from a cross of ‘OAC Wallace’ and ‘OAC Glencoe’, a total of 11 genomic regions located on nine different chromosomes were identified as associated with oil concentration using multiple QTL mapping (MQM) and single-factor ANOVA. Among the 11 oil-associated QTL, four QTL were also validated in a population of 211 F3:5 RILs from a cross of ‘RCAT Angora’ and ‘OAC Wallace’. There were six oil QTL identified in this study that were co-localized with seed protein QTL and four for seed yield QTL. The oil-beneficial allele of the QTL tagged by marker Sat_020, on Chromosome 9, was positively associated with seed protein concentration. The oil-enhancing alleles at markers Satt001 and GmDGAT2B were positively correlated with seed yield. In this study, three sequence mutations were also discovered in either the coding or non-coding regions of three DGAT soybean genes (GmDGAT2B, GmDGAT2C, and GmDGAT1B) between ‘OAC Wallace’ and ‘OAC Glencoe’ that showed significant effects on some of the traits evaluated. GmDGAT2B showed significant association with seed oil and yield across different environments. The oil-favorable allele of the gene GmDGAT2B from ‘OAC Glencoe’ was also positively correlated with seed yield. GmDGAT2C was associated with seed yield, whereas GmDGAT1B showed significant effects on seed yield and protein concentration. However, neither of these two genes showed any association with seed oil. The yield-enhancing allele of GmDGAT1B showed negative association with protein concentration. The identification of oil QTL that were either positively associated with seed yield and protein or neutral to both traits and the development of new gene-based markers will facilitate marker-assisted breeding to develop high oil soybean cultivars with high yield and minimal effect on protein concentration. / Generous funding to conduct this research was provided by the Alternative Renewable Fuels II Program of the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA) and by the Grain Farmers of Ontario.
42

The identification of candidate genes using cDNA microarray and the analysis of two SNPs of the reelin gene in a South African austistic population

Hajirah Gameeldien January 2009 (has links)
<p>Autism is a pervasive developmental disorder (PDD) that&rsquo / s incidence is approximately 1 in 158. It is four times more prevalent in males than females and is believed to be caused by both genetic and environmental factors. Research indicates that several genes are involved in autism and it is believed that these genes act together to produce autism. Many genes implicated in this disorder are involved with brain structure formation and brain functioning. Studies have identified the reelin (RELN) gene as necessary for proper formation of brain, which indicates that RELN abnormalities could contribute to the aetiology of several neurogenetic diseases such as schizophrenia, bipolar and autism. The aims of the study were (i) to genotype two SNPs (exonic rs3622691 and intronic rs736707) in the RELN gene using Taqman&reg / SNP Genotyping assays to detect association with autism in three distinct South African (SA) ethnic groups (Black, Caucasian and Mixed), and (ii) to detect candidate genes that are over and under-expressed in the samples taken from a SA Caucasian autistic group and compare those with samples taken from a healthy Caucasian group using cDNA microarray. The Taqman&reg / study indicated significant association for the intronic SNP, rs736707, with a p-value of 0.0009 in the total SA group. More so, the Mixed group displayed the highest significance amongst the ethnic groups, with a p-value of 0.00014. The microarray study yielded 21 genes with 95% significance in the Caucasian sample group. Most genes were hypothetical proteins and formed part of the FAM90A family. The LOC83459 showed the highest level of expression in the autistic samples, while the BTNL8 gene was shown to be highly suppressed in the control samples.</p>
43

Développement de nouvelles approches thérapeutiques dans la lutte contre les infections à arénavius : vaccination et immunothérapie passive / Development of new therapeutic approaches in the fight against arenavirus infections : vaccination and passive immunotherapy

Zaza, Amélie 25 January 2018 (has links)
La famille des Arenaviridae comporte sept virus responsables de fièvres hémorragiques humaines. Ces virus représentent un risque naturel pour les populations vivant dans les zones endémiques, ou y séjournant comme les militaires français déployés. Ce risque peut également toucher des populations vivant en dehors des zones endémiques en raison du risque d'importation d'un patient infecté ou consécutivement à l'utilisation intentionnelle et malveillante de tels virus dans le cadre d'une attaque bioterroriste. Les fièvres hémorragiques humaines causées par les arénavirus sont relativement rares et les premiers symptômes, non spécifiques, sont souvent confondus avec ceux de maladies plus fréquentes dans ces régions, comme le paludisme ou les arboviroses. Par conséquent, le diagnostic clinique est souvent retardé, ce qui réduit l'efficacité du seul traitement étiologique actuellement préconisé, la ribavirine. Dans ce contexte, le développement de solutions prophylactiques similaires au vaccin Candid #1, protégeant contre l'arénavirus Junin, constituent une alternative intéressante. Dans le cadre du développement de candidats vaccins, la première stratégie utilisée dans ce travail a consisté à atténuer la pathogénicité du virus d'intérêt en ciblant une étape clé de la réplication des arénavirus. Nous avons choisi l'étape du bourgeonnement viral, dont l'acteur principal est la protéine Z. Une preuve de concept a été réalisée avec le virus de la chorioméningite lymphocytaire (LCMV). Pour cela, nous avons conçu un système de génétique inverse qui exprime un segment L viral où le gène de la protéine Z est remplacé par un gène d'intérêt. De manière surprenante, ce virus recombinant était capable de produire en culture cellulaire une progénie à un titre très faible sans l'apport en trans de la protéine Z. Nous avons identifié des domaines tardifs dans la séquence peptidique de la nucléoprotéine, motifs peptidiques permettant le détournement de la machinerie cellulaire impliquée dans la production d'exosomes et présents dans les protéines de matrices virales, comme la protéine Z des arénavirus. Nous avons observé que ces domaines pourraient partiellement compenser l'absence de la protéine Z. Des résultats similaires ont été obtenus avec deux autres arénavirus ayant une importance majeure en santé publique, les virus Lassa et Machupo, tous deux responsables de fièvres hémorragiques humaines. Cette suppression pourrait constituer une stratégie d'atténuation et semblerait prometteuse en vue du développement de candidats vaccins réplicatifs atténués. En effet, elle pourrait être utilisée sur plusieurs arénavirus responsables de pathologies humaines. Une approche complémentaire à cette stratégie vaccinale a été envisagée. Dans le but de développer un traitement d'urgence, utilisant des immunoglobulines équines hautement purifiées, les F(ab')2, selon la méthodologie de la société Fab'entech, deux études préliminaires ont été réalisées. La première a permis de vérifier la capcité des virus à se répliquer dans les cellules immunitaires circulantes de cheval. La seconde a permis l'évaluation du cahier des charges qualité de particules virales en vue de leur utilisation comme source d'antigène afin de produire les F(ab')2. Une seconde stratégie vaccinale a été envisagée, basée sur une modification du nombre de segments génomiques viraux. Des travaux précédents ont montré qu'un arénavirus à 3 segments, au lieu de 2, était viable et atténué, tout en pouvant exprimer 2 gènes d'intérêt supplémentaires. Cette stratégie a été utilisée sur le virus Machupo, responsable de fièvres hémorragiques en Bolivie. Ce virus recombinant devrait exprimer les glycoprotéiques tronquées des virus Chapare et Guanarito. Ce candidat vaccin a été caractérisé en culture cellulaire, et a induit une protection de 50% des animaux lors d'une administration en post-exposition [etc...] / The Arenaviridae family comprises seven viruses responsible for human hemorrhagic fevers. These viruses represent a natural threat to the local populations, healthcare workers and scientists, as well as to the French forces deployed in the regions where these viruses are endemic. This viral threat can also be intentional in case of a bioterrorist attack. Human hemorrhagic fevers caused by arenaviruses are relatively rare and the first symptoms, frequently non-specific, are often confused with more common diseases such as malaria. Therefore, their diagnosis is delayed, which reduces the efficacy of ribavirin, the only etiological treatment currently recommended. ln this context, the development of prophylactic treatments, such as the Candid #1 vaccine targeting the Junin arenavirus, are an interesting alternative. The first strategy developed in this work to produce a vaccine candidate relied on the attenuation of the virus of interest by targeting a key stage of its replication. We chose the egress step, in which the main actor is the Z protein. This work was conducted using the lymphocytic choriomeningitis virus (LCMV). We therefore designed a reverse genetic system, and replaced the Z gene by the fluorescent protein eGFP reporter gene. Surprisingly, during its cellular infection, a progeny was detected in absence of the Z protein trans-complementation although the titer remained very low. ln this infectious model, we further identified late motifs in the nucleoprotein genome, comparable to those known in the Z protein. These NP late motifs seemed to play an essential role in the compensation of the absence of the Z protein. Similar results were observed using two others arenaviruses of medical importance, the Lassa and Machupo viruses, responsible of human hemorrhagic fevers. The strong diminution of the resulting vaccine candidate replication suggests that this strategy would render safe enough BSL-4 viruses to be used as a multivalent vaccine platform in humans. A complementary approach has been studied in this work. ln order to develop an emergency treatment, based on the production of highly purified F(ab')2 equine immunoglobulins, according to the Fab'entech technology. Two preliminary studies were carried out. The first one consisted in the study of the replication of arenaviruses in circulating horse's white blood cells. The second tested the specifications of attenuated viral particles that could be used as an antigen source to produce the F(ab')2 under good manufacturing practices. Another vaccine strategy was developed using the previously described duplication of the LCMV S genomic small segment in order to produce a tri-segmented recombinant virus. This genetic modification, known to attenuate the LCMV virus pathogenicity, allows the expression of two genes of interest. This strategy has been applied onto the South American Machupo virus, responsible for hemorrhagic fevers in Bolivia. A recombinant Machupo virus was designed to express the truncated glycoproteins of the Chapare and Guanarito viruses, two other New World mammarenaviruses responsible of human hemorrhagic fevers. This vaccine candidate was characterized in cell culture, and showed a 50% post-exposure protective effect in the animal model used. Taken together this work led to the development of two vaccine strategies and to the identification of a promising source of antigens to be used to produce highly purified F(ab')2 polyclonal immunoglobulin, which is the first step to the development of an emergency treatment
44

Dissection of quantitative resistance to rice diseases

Manosalva, Patricia M. January 1900 (has links)
Doctor of Philosophy / Department of Plant Pathology / Jan E. Leach / Because it is predicted to be durable and broad spectrum, quantitative trait loci (QTL)-based resistance is an important option for rice disease control. However, manipulation of this type of resistance requires knowledge of the contributing genes. This study demonstrates the contribution of two of three defense response (DR) genes to QTL-governed resistance, and identifies a third gene that negatively regulates resistance. The contribution to QTL-governed resistance of one of nine rice OsPAL genes, which encode phenylalanine ammonia-lyase, was determined using reverse genetics. Mutant ospal4 contains a 750 bp deletion in OsPAL4 and was identified using a PCR-pooling strategy. OsPAL4 underlies a QTL on chromosome 2, and is located in cluster with three other OsPAL members. Rice lines mutated in OsPAL4 are more susceptible to a virulent strain of Xanthomonas oryzae pv. oryzae (Xoo) than lines with the wild type allele. RNAi suppression was used to evaluate the contributions of genes encoding oxalate oxidase-like proteins (OsOXL) and a 14-3-3 protein (GF14-e) to disease resistance. Silencing of 12 OsOXL genes clustered on chromosome 8, varied from suppression of a few gene members to silencing of all expressed family members. Screening of transgenic lines by challenge with Magnaporthe grisea (Mg), the rice blast pathogen, revealed that the more chromosome 8 OsOXL genes suppressed, the more susceptible the plants were to Mg. GF14-e co-localizes with a disease resistance QTL on chromosome 2. Specific suppression of GF14-e by RNAi silencing did not result in enhanced susceptibility to Mg. Instead, the lines exhibited spontaneous HR-type lesions. The presence of this lesion mimic phenotype correlated with enhanced resistance to a virulent strain of Xoo, suggesting that the GF14-e encoded 14-3-3 protein functions as a negative regulator of plant cell death and bacterial resistance in rice. This study supports the hypothesis that DR genes, such as OsOXL and OsPAL4 contribute to disease resistance governed by QTL. The role of GF14-e is less clear, however its down regulation may contribute to QTL-governed resistance. Thus, incorporation of regions harboring the effective DR gene alleles into rice will enhance broad spectrum and durable resistance.
45

The identification of candidate genes using cDNA microarray and the analysis of two SNPs of the reelin gene in a South African austistic population

Gameeldien, Hajirah January 2009 (has links)
Magister Scientiae - MSc / Autism is a pervasive developmental disorder (PDD) that's incidence is approximately 1 in 158. It is four times more prevalent in males than females and is believed to be caused by both genetic and environmental factors. Research indicates that several genes are involved in autism and it is believed that these genes act together to produce autism. Many genes implicated in this disorder are involved with brain structure formation and brain functioning. Studies have identified the reelin (RELN) gene as necessary for proper formation of brain, which indicates that RELN abnormalities could contribute to the aetiology of several neurogenetic diseases such as schizophrenia, bipolar and autism. The aims of the study were (i) to genotype two SNPs (exonic rs3622691 and intronic rs736707) in the RELN gene using Taqman® SNP Genotyping assays to detect association with autism in three distinct South African (SA) ethnic groups (Black, Caucasian and Mixed), and (ii) to detect candidate genes that are over and under-expressed in the samples taken from a SA Caucasian autistic group and compare those with samples taken from a healthy Caucasian group using cDNA microarray. The Taqman® study indicated significant association for the intronic SNP, rs736707, with a p-value of 0.0009 in the total SA group. More so, the Mixed group displayed the highest significance amongst the ethnic groups, with a p-value of 0.00014. The microarray study yielded 21 genes with 95% significance in the Caucasian sample group. Most genes were hypothetical proteins and formed part of the FAM90A family. The LOC83459 showed the highest level of expression in the autistic samples, while the BTNL8 gene was shown to be highly suppressed in the control samples. / South Africa
46

Aggregate uncertainty, framing effects, and candidate entry

Solow, Benjamin Lewis 09 November 2016 (has links)
This dissertation studies how different voter characteristics and electoral rules affect the incentives and decisions to seek political office. The focus is on generalizing standard approaches to observed differences in the runoff rule and incorporating more accurate descriptions of voter behavior which may not be fully rational. In each chapter, I consider a model of strategic entry by candidates for office in democratic elections. In the first chapter, I incorporate the observed differences in thresholds for first-round victory in a model of runoff elections. The set of equilibria varies substantially with the threshold, indicating that the 50 percent threshold used in most models is not innocuous. The set of equilibria immediately contains equilibria that were thought to exist only under plurality rule, whereas for thresholds above 50 percent, there is no change in the set of equilibria. Additionally, for any threshold under one half, there exist equilibria in which a candidate who loses with certainty still chooses to run. The set of two candidate equilibria is invariant to all thresholds under one third, and the set of multicandidate equilibria is invariant to all thresholds above one half. In the second chapter, I introduce aggregate uncertainty by making candidates unsure of the distribution of voter preferences in the electorate. The set of three candidate equilibria expands and equilibrium platforms become more diverse. This provides a theoretical basis for Duverger’s Hypothesis. Equilibria also feature two common empirical phenomena. For instance, some candidates choose to enter despite losing with certainty in equilibrium. Also, in some equilibria, a Condorcet winning candidate (a candidate who would win every pairwise election) fails to win the election. In the third chapter, I generalize the citizen-candidate model to a multidimensional setting and characterize the set of equilibria. I later incorporate two well-documented violations of the Weak Axiom of Revealed Preference in a model of plurality elections: the compromise and attraction effects. Entry by an extreme candidate may shift the frame of reference for some voters in ways which favor particular moderate candidates. Incorporating these preferences generate equilibria in which extremist candidates enter plurality elections in order to attractively frame their preferred moderate, even if the extremist has probability zero of obtaining office themselves.
47

Itineraries of Spoiled Children: An Analysis of Candidate Selection Processes for European Elections.

Kelbel, Camille 19 September 2018 (has links) (PDF)
This PhD dissertation analyses the processes used by political parties to select candidates for the European elections, making the unique institutional setting and electoral dynamics of the European Parliament a “litmus test” for party organisations. By applying an institutional design theory to the ways parties nominate their candidates for the EP, I can test a wide range of pre-existing postulates about parties’ behaviours, and can do so across many different countries (thus considering various electoral settings and socio-political arenas) while also accounting for the multi-level setting in which they operate. To this end, I thoroughly explore the intra-party “machinery” at work in the drafting of nominees. More specifically, this dissertation first provides a descriptive account of the main intra-party formal rules that govern the EP selection procedures from a comparative perspective. Concretely, this descriptive analysis serves to measure the relative power of individuals, party organs, and party levels, and to establish what imperatives (membership fees, endorsements, incompatibilities, quotas) are prescribed by the various parties. On that basis, I identify the patterns of selection rules put in place by the parties. I then explore the factors that condition the parties' choices of procedures by relating the aforementioned observations to a number of national- and EU-level characteristics. Later, I confront these rules with the parties’ informal practices during the actual process, and further trace an entire process from the rules' enactment to the choice of candidates. In doing so, I hope to contribute a small but important building block to the understanding of current political parties, while also speaking directly to those who are more generally interested in comparative politics and EU politics. / Doctorat en Sciences politiques et sociales / info:eu-repo/semantics/nonPublished
48

The Intersection of Politics and Sports

Curry, Alexander Lawrence 09 August 2012 (has links) (PDF)
Candidates for public office expend a tremendous amount of time, energy, and financial resources in the hopes of connecting with voters. And because voters differ in their levels of political involvement, candidates need to utilize various avenues to make these connections with the electorate. One way that candidates convey their personal values and characteristics is by showcasing themselves as being involved in and knowledgeable about sports. This thesis utilized an experimental design to analyze whether a candidate's involvement in sports actually has an impact on how voters evaluate the candidate's image. Results indicated that voters' gender, as well as their levels of political knowledge, helps predict how they will evaluate a political candidate's image.
49

Successes and Pitfalls in Running a Small Program MMI

Humphreys, Cathy 27 May 2016 (has links)
Purpose: Academic programs are faced with the important task of selecting health professional students who not only possess necessary cognitive abilities to perform their future job, but also have valuable personal/professional characteristics to draw upon in the provision of quality patient care. There is therefore "widespread agreement that it is desirable to broaden the scope of assessment beyond academic achievement" (Eva, Reiter, Trinh, Wasi, Rosenfeld, Norman, 2009, p.768) in candidate selection. The Child Life Studies Program at McMaster University used a 4-station multiple mini-interview (MMI) as part of the admission selection process. This study sought to determine the feasibility, degree of acceptability and reliability of this 4-station MMI design, and if there were any predictors of candidate's performance on the MMI. Methods: A group of 35 applicants in 2014, and 40 applicants in 2015 screened through admission procedures participated in a 4-station MMI. Each station was 15 minutes in length with 5 minutes for scoring each candidate. Anonymous stakeholder surveys were used in 2015 to assess participant and interviewer's perceptions and acceptability of the MMI in applicant selection. Generalizability coefficients were calculated to determine reliability. In addition, candidate's experience in healthcare, professional work experience, experience with children with disabilities, and previous child life course work (or lack thereof) were analyzed through independent t-tests to report any relationship with candidate's performance on the MMI. A one-way ANOVA was also completed to report any relationship between candidate's undergraduate degree type and his/her MMI performance. Results: The 4-station MMI was found to be feasible for a small program with a marked increase found in the number of candidates interviewed in a shorter period of time. It was also found to be highly acceptable among candidates and faculty. However, this studies' findings did not show statistically significant differences in MMI performance based on identified predictors, or undergraduate degree type. The reliability of the 4-station design in 2014 was G=0.718, however, was only G=0.089 in 2015, far lower than expected based on the prior year’s G Coefficient. The potential pitfalls in running a small program MMI are discussed with specific suggestions and modifications provided to enhance reliability of candidate selections across professions. / Thesis / Master of Science (MSc)
50

QUANTITATIVE ANALYSIS OF TABU SEARCH ALGORITHM FOR A VLSI PLACEMENT APPLICATION

SHARMA, VIKAS 11 October 2001 (has links)
No description available.

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