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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.
171

Genetic variation of Aspergillus fumigatus from Auckland, New Zealand / Contemporary gene flow is a major force shaping the Aspergillus fumigatus population in Auckland, New Zealand

Korfanty, Gregory January 2019 (has links)
Aspergillus fumigatus is a globally present opportunistic fungal pathogen that plays a key role in degrading organic matter. A. fumigatus can cause a vast array of diseases, collectively known as aspergilloses. The most serious of these is invasive aspergillosis, that has a mortality rate of 30 to 95% with treatment. Recent studies have indicated that the global A. fumigatus population consists of multiple divergent genetic clusters that are broadly distributed geographically. However, most of the previously analyzed samples have come from continental Eurasia and the Americas where the effects of historical or contemporary gene flow is difficult to distinguish. My thesis project, therefore, focused on analyzing the genetic diversity of the Auckland, New Zealand A. fumigatus population, as it is geographic distant from all previously analyzed populations. Here, we obtained 104 A. fumigatus isolates from Auckland and compared the genotypes of these isolates to population data obtained from nine other countries from Europe, Africa, North America, and Asia. The goal was to analyze the potential effects of historical differentiation and gene flow within this population. We determined that the Auckland population had a low, non-significant level of differentiation compared to most previously surveyed global populations. However, the Auckland population also contained unique genetic elements not present within populations from other geographic regions. Though the hypothesis of random recombination was rejected, we found abundant evidence for phylogenetic incompatibility and recombination within the Auckland A. fumigatus population. Lastly, we identified two triazole resistant strains within the Auckland population, with one carrying the common TR34/L98H cyp51A mutation. Our results suggest that contemporary gene flow, likely due to anthropogenic factors, is a major force shaping the New Zealand A. fumigatus population. These results contribute to our understanding of the high levels of gene flow observed within and among many geographic populations of A. fumigatus. / Thesis / Master of Science (MSc) / Aspergillus fumigatus is a globally distributed fungal mold capable of causing serious diseases in individuals with weakened immune systems or lung damage. In the environment, A. fumigatus lives in the soil where it degrades organic matter and contributes to the cycling of nitrogen and carbon across the planet. Due to the airborne nature of its spores, people inhale this fungus daily, and those at risk may develop disease. These diseases, collectively known as aspergilloses, can result in long term chronic illnesses, and in the case of invasive aspergillosis, the death rate can be as high as 95%, even with treatment. Medical treatment of aspergilloses involves the use of antifungal drugs. However, some A. fumigatus strains have developed resistance. I am interested in the patterns of global genetic diversity of A. fumigatus populations. For my MSc thesis, I investigated the A. fumigatus population within Auckland, New Zealand, as it is both geographically isolated and distant from other previously surveyed populations. Our data illustrated that the New Zealand population contains pockets of unique diversity as well as high levels of similarity to the previously surveyed populations within Europe. My results suggest that human influences, likely due to travel and trade, have played a large role in shaping the genetic diversity of the A. fumigatus population from Auckland, New Zealand.
172

Selección genómica en poblaciones reducidas de vacuno de leche

Jiménez Montero, José Antonio 21 March 2013 (has links)
La selección genómica está cambiando profundamente el mercado del vacuno de leche. En la actualidad, es posible obtener una alta precisión en las valoraciones genéticas de animales muy jóvenes sin la necesidad del fenotipo propio o el de sus hijas. Por tanto, la respuesta genética de un programa genómico bien diseñado supera netamente a la selección tradicional. Esta mejora está modificando uno de los principios tradicionales del mercado de vacuno de leche como era la preferencia de uso de toros con altas fiabilidades frente a otros animales con valores genéticos a priori superiores. Esta tesis contiene seis capítulos en los cuales se estudian de las bases para la implementación del programa de selección genómica en el vacuno de leche español. Para ello se realizaron estudios de simulación y valoraciones genómicas con datos reales de la primera población nacional de referencia. El objetivo principal de esta tesis es contribuir a la implementación de la selección genómica en el vacuno de leche español. Los objetivos específicos son: (1) Estudiar alternativas de genotipado en poblaciones reducidas de vacuno lechero. (2) Desarrollar y validar metodología para la evaluación de grandes cantidades de genotipos. (3) Estudiar el efecto de los procesos de imputación de genotipos en la capacidad predictiva de los genotipos resultantes. Las principales cuestiones relacionadas con la selección genómica en vacuno lechero fueron discutidas en el capítulo 1 incluyendo: aspectos estadísticos y genéticos en los que se basa la selección genómica, diseño de poblaciones de referencia, revisión del estado del arte en cuanto a la metodología desarrollada para evaluación genómica, diseño y métodos de los algoritmos de imputación, e implementación de la selección genómica en vacuno de leche a nivel de programa de selección, centro de inseminación y de granja comercial. En el capítulo 2 se realizó un estudio de simulación comparando estrategias de genotipado selectivo en poblaciones de hembras frente al uso de selección tradicional o selección genómica con una población de referencia de machos. La población de referencia española estaba formada en principio por algo más de 1,600 toros con prueba de progenie. Este tamaño no es, en principio, suficiente para obtener predicciones genómicas de alta fiabilidad. Por tanto, debían evaluarse diferentes alternativas para incrementar la habilidad predictiva de las evaluaciones. Las estrategias que consisten en usar como población de referencia los animales en los extremos de la distribución fenotípica permitían mejorar la precisión de la evaluación. Los resultados usando 1,000 genotipos fueron 0.50 para el carácter de baja heredabilidad y 0.63 para el de heredabilidad media cuando la variable dependiente fue el fenotipo ajustado. Cuando se usaron valores genéticos como variable dependiente las correlaciones fueron 0.48 y 0.63 respectivamente. Para los mismos caracteres, una población de 996 machos obtuvo correlaciones de 0.48 y 0.55 en las predicciones posteriores. El estudio concluye que la estrategia de genotipado que proporciona la mayor correlación es la que incluye las hembras de ambas colas de la distribución de fenotipos. Por otro lado se pone de manifiesto que la mera inclusión de las hembras élite que son las habitualmente genotipadas en las poblaciones reales produce resultados no satisfactorios en la predicción de valores genómicos. En el capítulo 3, el Random Boosting (R-Boost) es comparado con otros métodos de evaluación genómica como Bayes-A, LASSO Bayesiano y G-BLUP. La población de referencia española y caracteres incluidos en las evaluaciones genéticas tradicionales de vacuno lechero fueron usados para comparar estos métodos en términos de precisión y sesgo. Las predicciones genómicas fueron más precisas que el índice de pedigrí tradicional a la hora de predecir los resultados de futuros test de progenie como era de esperar. Las ganancias en precisión debidas al empleo de la selección genómica dependen del carácter evaluado y variaron entre 0.04 (Profundidad de ubre) y 0.42 (Porcentaje de grasa) unidades de correlación de Pearson. Los resultados promediados entre caracteres mostraron que el LASSO Bayesiano obtuvo mayores correlaciones superando al R-Boost, Bayes-A y G-BLUP en 0.01, 0.03 y 0.03 unidades respectivamente. Las predicciones obtenidas con el LASSO Bayesiano también mostraron menos desviaciones en la media, 0.02, 0.03 y 0.10 menos que Bayes-A, R-Boost y G-BLUP, respectivamente. Las predicciones usando R-Boost obtuvieron coeficientes de regresión más próximos a la unidad que el resto de métodos y los errores medios cuadráticos fueron un 2%, 10% y 12% inferiores a los obtenidos a partir del B-LASSO, Bayes-A y G-BLUP, respectivamente. El estudio concluye que R- Boost es una metodología aplicable a selección genómica y competitiva en términos de capacidad predictiva. En el capítulo 4, el algoritmo de machine learning R-Boost evaluado en el capítulo 3 es descrito e implementado para selección genómica adaptado a la evaluación de grandes bases de datos de una forma eficiente. Tras la incorporación en el consorcio Eurogenomics, el programa genómico español pasó a disponer de más de 22,000 toros probados como población de referencia, por tanto era necesario implementar un método capaz de evaluar éste gran conjunto de datos en un tiempo razonable. El nuevo algoritmo denominado R-Boost realiza de forma secuencial un muestreo aleatorio de SNPs en cada iteración sobre los cuales se aplica un predictor débil. El algoritmo fue evaluado sobre datos reales de vacuno de leche empleados en el capítulo 3 estudiando más en profundidad el comportamiento de los parámetros de sintonización. Esta propuesta de modificación del Boosting puede obtener predicciones sin perdida de precisión o incrementos de sesgo empleando tan solo un 1% del tiempo de computación original. En el capítulo 5 se evalúa el efecto de usar genotipos de baja densidad imputados con el software Beagle en cuanto a su posterior habilidad predictiva cuando son incorporados a la población de referencia. Para ello se emplearon dos métodos de evaluación R-Boost y un BLUP con matriz genómica. Animales de los que se conocían los SNPs incluidos en los chips GoldenGate Bovine 3K y BovineLD BeadChip, fueron imputados hasta conocer los SNPs incluidos en el BovineSNP50v2 BeadChip. Posteriormente, un segundo proceso de imputación obtuvo los SNPs incluidos en el BovineHD BeadChip. Tras imputatar desde dos genotipados a baja densidad, se obtuvo similar capacidad predictiva a la obtenida empleando los originales en densidad 50K. Sin embargo, sólo se obtuvo una pequeña mejora (0.002 unidades de Pearson) al imputar a HD. El mayor incremento se obtuvo para el carácter días abiertos donde las correlaciones en el grupo de validación aumentaron en 0.06 unidades de Pearson las correlaciones en el grupo de validación cuando se emplearon los genotipos imputados a HD. En función de la densidad de genotipado, el algoritmo R-Boost mostró mayores diferencias que el G-BLUP. Ambos métodos obtuvieron resultados similares salvo en el caso de porcentaje de grasa, donde las predicciones obtenidas con el R-Boost fueron superiores a las del G-BLUP en 0.20 unidades de correlación de Pearson. El estudio concluye que la capacidad predictiva para algunos caracteres puede mejorar imputando la población de referencia a HD así como empleando métodos de evaluación capaces de adaptarse a las distintas arquitecturas genéticas posibles. Finalmente en el capitulo 6 se desarrolla una discusión general de los estudios presentados en los capítulos anteriores y se enlazan con la implementación de la selección genómica en el vacuno lechero español, que se ha desarrollado en paralelo a esta tesis doctoral. La primera población de referencia con unos 1.600 toros fue evaluada en el capítulo 4 y fue usada para comparar los distintos métodos y escenarios propuestos en los capítulos 3, 4 y 5. La primera evaluación genómica obtenida para los caracteres incluidos en el capítulo 4 de esta tesis estuvo disponible para los centros de inseminación incluidos en el programa en septiembre de 2011. La población de Eurogenomics se incorporó en Noviembre de dicho año, completándose la primera evaluación para los caracteres incluidos en el índice de selección ICO en Febrero de 2012 empleando el R-Boost descrito en el capítulo 3. En mayo de 2012 las evaluaciones del carácter proteína fueron validadas por Interbull y finalmente el 30 de Noviembre del 2012 las primeras evaluaciones genómicas oficiales fueron publicadas on-line por la federación de ganaderos CONAFE (http://www.conafe.com/noticias/20121130a.htm). / Jiménez Montero, JA. (2013). Selección genómica en poblaciones reducidas de vacuno de leche [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/27649
173

Continuous Continuous Probabilistic Genotyping: A differentiable model and modern Bayesian inference techniques for forensic DNA mixtures

Susik, Mateusz 19 June 2024 (has links)
DNA samples are a part of the collected physical evidence during the comtemporary crime scene investigation procedure. After processing the samples, a laboratory obtains short tandem repeat electropherograms. In case of mixed DNA profiles, i.e., profiles that contain DNA material from more than one contributor, the laboratory needs to estimate the test statistic (likelihood ratio) that could provide evidence, either inculpatory or exculpatory, against the person of interest. This is automated with probabilistic genotyping (PG) software with (fully-)continuous models: the ones that consider the heights of the observed peaks. In this thesis, we provide understanding of the modern PG methods. We then show how to improve measurable indicators of the algorithm performance, such as precision and inference runtime, that directly correspond to the efficiency and efficacy of work performed in a lab. With quicker algorithms the forensics laboratories can process more samples and provide more comprehensive results by reanalysing the mixtures with different hypotheses and hyperparameterisations. With more precise algorithms, there will be a grater confidence in their results. The precision of the solution would ameliorate the admissibility of the provided evidence and reliability of the results. We achieve improvements over the state-of-the-art by utilising probabilistic programming and modern Bayesian inference methods. We describe a differentiable (and hence continuous) continuous model that can be used with different estimators from both the sampling and variational families of techniques. Finally, as the different PG products output different likelihood ratios, we provide explanation of some of the factors causing this behaviour. This is of high importance because if two solutions are used for the same crime case, the difference must be understood. Otherwise, because of lack of consensus, the results would cause confusion or, in the worst case, would not be admitted by the court.
174

Molecular Marker Applications in Oat (Avena Sativa L.) Breeding and Germplasm Diagnostics

Benazir Katarina, Marquez 27 May 2014 (has links)
The ability to identify germplasm and select traits accurately is fundamental to successful plant breeding. Pedigrees and molecular markers facilitate these processes; however misleading experimental results can occur when incorrect relationships and/or cultivar names are recorded. Molecular markers can identify these inconsistencies, and with advances in genotyping technology these diagnostics can be done faster and more objectively. This study aimed to develop molecular marker assays and graphical genotyping methodologies for cultivar identification, seed purity assessment and trait selection in oat (Avena sativa L.). KBioscience’s Allele-Specific PCR (KASP™) and genotyping-by-sequencing (GBS) technologies were applied to a set of current Canadian oat cultivars to evaluate their utility for identifying cultivars and detecting intra-cultivar variation. Both KASP™ and GBS detected different extents of heterogeneity among a set of 160 seeds that originated from four seed sources of four cultivars. In both cases, the detected variation did not appear to be limited to a specific cultivar or seed source, reinforcing that all cultivars are heterogeneous. Graphical genotyping localized heterogeneity to specific chromosome regions, thereby distinguishing physical contamination from true genetic heterogeneity and heterozygosity. Pre-existing genotype data for 700 oat cultivars and breeding lines were also used to construct graphical genotypes for pedigree validation and discovery of potential sources for favourable quantitative trait loci (QTL) alleles. This methodology used historical QTLs and anchoring markers to identify 25 putative “high oil” allele carriers. The results from this study will provide diagnostic tools for cultivar identification and pedigree validation, in addition to meaningful information about existing heterogeneity and possible QTL locations in current cultivars.
175

Molecular Marker Applications in Oat (Avena Sativa L.) Breeding and Germplasm Diagnostics

Benazir Katarina, Marquez January 2014 (has links)
The ability to identify germplasm and select traits accurately is fundamental to successful plant breeding. Pedigrees and molecular markers facilitate these processes; however misleading experimental results can occur when incorrect relationships and/or cultivar names are recorded. Molecular markers can identify these inconsistencies, and with advances in genotyping technology these diagnostics can be done faster and more objectively. This study aimed to develop molecular marker assays and graphical genotyping methodologies for cultivar identification, seed purity assessment and trait selection in oat (Avena sativa L.). KBioscience’s Allele-Specific PCR (KASP™) and genotyping-by-sequencing (GBS) technologies were applied to a set of current Canadian oat cultivars to evaluate their utility for identifying cultivars and detecting intra-cultivar variation. Both KASP™ and GBS detected different extents of heterogeneity among a set of 160 seeds that originated from four seed sources of four cultivars. In both cases, the detected variation did not appear to be limited to a specific cultivar or seed source, reinforcing that all cultivars are heterogeneous. Graphical genotyping localized heterogeneity to specific chromosome regions, thereby distinguishing physical contamination from true genetic heterogeneity and heterozygosity. Pre-existing genotype data for 700 oat cultivars and breeding lines were also used to construct graphical genotypes for pedigree validation and discovery of potential sources for favourable quantitative trait loci (QTL) alleles. This methodology used historical QTLs and anchoring markers to identify 25 putative “high oil” allele carriers. The results from this study will provide diagnostic tools for cultivar identification and pedigree validation, in addition to meaningful information about existing heterogeneity and possible QTL locations in current cultivars.
176

Identification of Molecular Markers Associated with the <i>Rps</i>8 locus in Soybean and Evaluation of Microsporogenesis in <i>Rps</i>8/<i>rps</i>8 Heterozygous Lines

Ortega, Maria Andrea January 2009 (has links)
No description available.
177

Microarray Technology for Genotyping in Pharmacogenetics

Liljedahl, Ulrika January 2004 (has links)
The studies in this thesis describe the development of a microarray based minisequencing system and its application to highly parallel genotyping of single nucleotide polymorphisms. The technical developments included identification of a three-dimensional microarray surface coating with high binding capacity for oligonucleotides modified with amino groups as the most optimal one for the system. The system was also established for multiplexed, reproducible quantitative analysis of SNP alleles both on the level of DNA and RNA. The sensitivity of the system to distinguish SNP alleles present as a minority in a mixed sample was found to be 1-6%. The microarray based minisequencing system was applied in a pharmacogenetic study on antihypertensive drug response. A panel of 74 SNPs located in candidate genes related to blood pressure regulation were genotyped in DNA samples from hypertensive patients that had been treated with the antihypertensive drugs irbesartan or atenolol. Multiple regression analysis of the genotype data against the reduction in blood pressure identified genotype combinations of four to five SNPs that explain 44-56% of the reduction in blood pressure in the two treatment groups. The genotypes of two individual SNPs in the angiotensinogen (AGT) gene and a SNP in the low density lipoprotein receptor (LDLR) gene appeared to be associated to reduced blood pressure after treatment with atenolol, while a SNP in the apolipoprotein B (APOB) gene was associated to blood pressure reduction after irbesartan treatment. The genotype of one SNP in the adrenergic alpha-2A-receptor gene (ADRA2A) was related to the reduction in left ventricular mass following atenolol treatment while the genotypes of two SNPs, one in the APOB gene and one in the AGT gene were related to the reduction in left ventricular mass in the patients treated with irbesartan.
178

Development of a Blood Antigen Molecular Profiling Panel using Genotyping Technologies for Patients Requiring Frequent Transfusions

Mongrain, Ian 07 1900 (has links)
Contexte. Les phénotypes ABO et Rh(D) des donneurs de sang ainsi que des patients transfusés sont analysés de façon routinière pour assurer une complète compatibilité. Ces analyses sont accomplies par agglutination suite à une réaction anticorps-antigènes. Cependant, pour des questions de coûts et de temps d’analyses faramineux, les dons de sang ne sont pas testés sur une base routinière pour les antigènes mineurs du sang. Cette lacune peut résulter à une allo-immunisation des patients receveurs contre un ou plusieurs antigènes mineurs et ainsi amener des sévères complications pour de futures transfusions. Plan d’étude et Méthodes. Pour ainsi aborder le problème, nous avons produit un panel génétique basé sur la technologie « GenomeLab _SNPstream» de Beckman Coulter, dans l’optique d’analyser simultanément 22 antigènes mineurs du sang. La source d’ADN provient des globules blancs des patients préalablement isolés sur papiers FTA. Résultats. Les résultats démontrent que le taux de discordance des génotypes, mesuré par la corrélation des résultats de génotypage venant des deux directions de l’ADN, ainsi que le taux d’échec de génotypage sont très bas (0,1%). Également, la corrélation entre les résultats de phénotypes prédit par génotypage et les phénotypes réels obtenus par sérologie des globules rouges et plaquettes sanguines, varient entre 97% et 100%. Les erreurs expérimentales ou encore de traitement des bases de données ainsi que de rares polymorphismes influençant la conformation des antigènes, pourraient expliquer les différences de résultats. Cependant, compte tenu du fait que les résultats de phénotypages obtenus par génotypes seront toujours co-vérifiés avant toute transfusion sanguine par les technologies standards approuvés par les instances gouvernementales, les taux de corrélation obtenus sont de loin supérieurs aux critères de succès attendus pour le projet. Conclusion. Le profilage génétique des antigènes mineurs du sang permettra de créer une banque informatique centralisée des phénotypes des donneurs, permettant ainsi aux banques de sang de rapidement retrouver les profiles compatibles entre les donneurs et les receveurs. / Background. ABO and Rh(D) phenotyping of both blood donors and transfused patients is routinely performed by blood banks to ensure compatibility. These analyses are done by antibody-based agglutination assays. However, blood is not routinely tested for minor blood group antigens on a regular basis because of cost and time constraints. This can result in alloimmunization of the patient against one or more minor antigens and may complicate future transfusions. Study design and Methods. To address this problem, we have generated an assay on the GenomeLab SNPstream genotyping system (Beckman Coulter, Fullerton, CA) to simultaneously test polymorphisms linked to 22 different blood antigens using donor’s DNA isolated from minute amounts of white blood cells. Results. The results showed that both the error rate of the assay, as measured by the strand concordance rate, and the no-call rate were very low (0.1%). The concordance rate with the actual red blood cell and platelet serology data varied from 97 to 100%. Experimental or database errors as well as rare polymorphisms contributing to antigen conformation could explain the observed differences. However, these rates are well above requirements since phenotyping and cross-matching will always be performed prior to transfusion. Conclusion. Molecular profiling of blood donors for minor red blood cell and platelet antigens will give blood banks instant access to many different compatible donors through the set-up of a centralized data storage system.
179

Analyse génotypique des cellules initiatrices de tumeurs exprimant CD133 dans le neuroblastome

Cournoyer, Sonia 03 1900 (has links)
Le neuroblastome (NB) est la tumeur solide extracranienne la plus fréquente et mortelle chez les jeunes enfants. Il se caractérise par une résistance à la chimiothérapie possiblement en partie dû à la présence de cellules initiatrices de tumeurs (TICs). Des études ont mis en évidence le rôle de CD133 comme un marqueur des TICs dans divers types de cancers. Les buts de notre travail étaient d’abord de démontrer les vertus de TICs des cellules exprimant CD133 et ensuite, en utilisant une analyse globale du génome avec des polymorphismes nucléotidiques simples (SNPs), d’effectuer une analyse différentielle entre les TICs et les autres cellules du NB afin d’en identifier les anomalies génétiques spécifiques. Des lignées cellulaires de NB ont été triées par cytométrie de flux afin d’obtenir deux populations: une enrichie en CD133 (CD133high), l’autre faible en CD133 (CD133low). Afin de déterminer si ces populations cellulaires présentent des propriétés de TICs, des essais sur les neurosphères, les colonies en agar mou et les injections orthotopiques de 500 cellules sélectionnées dans 11 souris ont été réalisées. Après une isolation de l’ADN des populations sélectionnées, nous avons effectué une analyse génotypique par SNP utilisant les puces « Affymetrix Genome-Wide Human SNP Array 6.0 ». Pour vérifier l’expression des gènes identifiés, des Western Blots ont été réalisés. Nos résultats ont démontré que la population CD133 avait des propriétés de TICs in vitro et in vivo. L’analyse génotypique différentielle a permis d’identifier deux régions communes (16p13.3 and 19p13.3) dans la population CD133high ayant des gains et deux autres régions (16q12.1 and 21q21.3) dans la population CD133low possédant des pertes d’hétérozygoties (LOH). Aucune perte n’a été observée. Parmi les gènes étudiés, l’expression protéique d’éphrine-A2 était corrélée à celle de CD133 dans 6 tumeurs et 2 lignées cellulaires de NB. De plus, l’augmentation de la concentration d’anticorps anti-éphrine-A2 dans le milieu diminue la taille des neurosphères. Ainsi, la population CD133high, qui a des vertus de TICs, possède des caractéristiques génotypiques différentes par rapport à celle CD133low. La présence d’éphrine-A2 dans les cellules exprimant CD133 souligne son importance dans le développement des TICs. Ces résultats suggèrent la présence de potentielle cible pour de nouvelles thérapeutiques ciblant les TICs mise en évidence par l’étude génomique. / Neuroblastoma (NB) is the most common and deadly extracranial solid tumor of childhood characterized by a resistance to chemotherapy possibly due to the presence of tumor initiating cells (TICs). Studies showed the role of CD133 as a marker of TICs in various types of cancers. Our goals were first to demonstrate the stemness of TICs expressing CD133 and then, using a global genomic analysis with single nucleotide polymorphism (SNPs), to perform a differential analysis between TICs and other cells of NB to identify the specific genetic abnormalities. NB cell lines were sorted by flow cytometry to obtain two populations: one enriched in CD133 (CD133high), the other low in CD133 (CD133low). To determine whether these cell populations have TICs properties, we test the ability of cells to form either neurosphères or, colonies in soft agar and we also test their carcinogenic properties by orthotopic injections of 500 selected cells in 11 mice. After a DNA extraction on selected populations, a differential genotyping analysis has been made with Affymetrix Genome-Wide Human SNP Array 6.0. To verify the expression of the genes identified, Western blots had been made. Our results have demonstrated that CD133high population presented TICs properties in vitro and in vivo. The differential genotyping analysis allowed identifying two gains common regions (16p13.3 and 19p13.3) in CD133high population and two others loss of heterozygosity (LOH) (16q12.1 and 21q21.3) in CD133low population . No losses were observed. Among the genes studied, ephrin-A2 protein expression was correlated to CD133 expression in 6 NB tumors and 2 NB cell lines. Also, ephrin-A2’s increased concentration influenced the neurospheres by decreasing their size. Thereby, CD133high population, which had TICs properties, possess different genotyping characteristics compared to CD133low population. The presence of ephrine-A2 in cells expressing CD133 emphasizes its importance in the development of TICs. These results suggest the presence of potential target for new therapies targeting the TICs demonstrated by the genomic study.
180

The Development, Validation and Implementation of a Broad-Based ADME Genotyping Assay into Research and Clinical Trials

Brown, Andrew M.K. 12 1900 (has links)
Afin d’adresser la variabilité interindividuelle observée dans la réponse pharmacocinétique à de nombreux médicaments, nous avons créé un panel de génotypage personnalisée en utilisant des méthodes de conception et d’élaboration d’essais uniques. Celles-ci ont pour but premier de capturer les variations génétiques présentent dans les gènes clés impliqués dans les processus d'absorption, de distribution, de métabolisme et d’excrétion (ADME) de nombreux agents thérapeutiques. Bien que ces gènes et voies de signalement sont impliqués dans plusieurs mécanismes pharmacocinétiques qui sont bien connues, il y a eu jusqu’à présent peu d'efforts envers l’évaluation simultanée d’un grand nombre de ces gènes moyennant un seul outil expérimental. La recherche pharmacogénomique peut être réalisée en utilisant deux approches: 1) les marqueurs fonctionnels peuvent être utilisés pour présélectionner ou stratifier les populations de patients en se basant sur des états métaboliques connus; 2) les marqueurs Tag peuvent être utilisés pour découvrir de nouvelles corrélations génotype-phénotype. Présentement, il existe un besoin pour un outil de recherche qui englobe un grand nombre de gènes ADME et variantes et dont le contenu est applicable à ces deux modèles d'étude. Dans le cadre de cette thèse, nous avons développé un panel d’essais de génotypage de 3,000 marqueurs génétiques ADME qui peuvent satisfaire ce besoin. Dans le cadre de ce projet, les gènes et marqueurs associés avec la famille ADME ont été sélectionnés en collaboration avec plusieurs groupes du milieu universitaire et de l'industrie pharmaceutique. Pendant trois phases de développement de cet essai de génotypage, le taux de conversion pour 3,000 marqueurs a été amélioré de 83% à 97,4% grâce à l'incorporation de nouvelles stratégies ayant pour but de surmonter les zones d'interférence génomiques comprenant entre autres les régions homologues et les polymorphismes sous-jacent les régions d’intérêt. La précision du panel de génotypage a été validée par l’évaluation de plus de 200 échantillons pour lesquelles les génotypes sont connus pour lesquels nous avons obtenu une concordance > 98%. De plus, une comparaison croisée entre nos données provenant de cet essai et des données obtenues par différentes plateformes technologiques déjà disponibles sur le marché a révélé une concordance globale de > 99,5%. L'efficacité de notre stratégie de conception ont été démontrées par l'utilisation réussie de cet essai dans le cadre de plusieurs projets de recherche où plus de 1,000 échantillons ont été testés. Nous avons entre autre évalué avec succès 150 échantillons hépatiques qui ont été largement caractérisés pour plusieurs phénotypes. Dans ces échantillons, nous avons pu valider 13 gènes ADME avec cis-eQTL précédemment rapportés et de découvrir et de 13 autres gènes ADME avec cis eQTLs qui n'avaient pas été observés en utilisant des méthodes standard. Enfin, à l'appui de ce travail, un outil logiciel a été développé, Opitimus Primer, pour aider pour aider au développement du test. Le logiciel a également été utilisé pour aider à l'enrichissement de cibles génomiques pour d'expériences séquençage. Le contenu ainsi que la conception, l’optimisation et la validation de notre panel le distingue largement de l’ensemble des essais commerciaux couramment disponibles sur le marché qui comprennent soit des marqueurs fonctionnels pour seulement un petit nombre de gènes, ou alors n’offre pas une couverture adéquate pour les gènes connus d’ADME. Nous pouvons ainsi conclure que l’essai que nous avons développé est et continuera certainement d’être un outil d’une grande utilité pour les futures études et essais cliniques dans le domaine de la pharmacocinétique, qui bénéficieraient de l'évaluation d'une longue liste complète de gènes d’ADME. / In order to better assess the inter-individual variability observed in a patient’s pharmacokinetic response to many medications, we have created a custom genotyping panel that uses unique assay designs to analyze variation present in key genes involved in the absorption, distribution, metabolism and excretion (ADME) of many therapeutic agents. These genes and pathways involved in most pharmacokinetic mechanisms are well known. However, as yet, there has been little effort to develop tools that can interrogate a large number of variations in most known drug metabolizing genes simultaneously within a single experimental tool. Pharmacogenomic research has historically been conducted using two approaches: targeted studies that screen a small number of specific functional markers to identify known metabolic status phenotypes, and genome-wide studies that identify novel genetic correlations with drug response phenotypes. Thus, a gap currently exists for a targeted ADME research tool that can evaluate a large number of key ADME genes and variants in a format that can be applicable to both types of study designs. As part of this thesis, we have developed a 3000 SNP broad based ADME genotyping panel that can address this need. Genes and markers for the genotyping panel were selected in collaboration with many groups from both academia and the pharmaceutical industry in an effort to capture all pertinent genes and metabolic pathways that have been implicated in drug metabolism. The final assay design was composed of over 3000 markers in 181 genes. Over three phases of iterative development, the assay conversion rate for the 3000 markers was improved from 83.0% to 97.4% through the incorporation of novel design strategies to overcome areas of genomic interference such as regions of homology and underlying polymorphisms. Accuracy of the assay was validated by screening more than 200 samples of known genotype with a concordance of 99%. Additionally, data from the assay has also been compared to data from different technological platforms and has an overall concordance of 99.5%. The effectiveness of the design strategy was demonstrated in the successful utilization of the assay in the screening of over 1000 samples which identified several novel pharmacogenetic associations between ADME variations and adverse drug reactions in children. Another goal of this thesis was to demonstrate what added benefit/utility the 3000 SNP ADME panel would have when compared to currently available genotyping assays. Using 150 extensively investigated liver samples, the broad based assay was not only able to detect and validate 13 previously reported cis eQTLs in ADME genes but further identified an additional 13 novel ADME cis eQTLs that had never been observed before, doubling the number previously identified using standard methods on the same samples. Finally, in support of this work, a number of bioinformatic tools had to be developed to help expedite this research. These tools have been further refined and are currently being used to assist with enrichment of genomic targets for next generation sequencing experiments. In conclusion, this work has led to a better understanding of ADME genetics and the nuances of assaying ADME genes. The content and designs of the developed assay sets it apart from currently available commercial assays that contain only functional markers in a small number of genes or do not have adequate coverage across ADME genes. The assay has the ability to play a significant role in pharmacogenomic studies to identify known and novel pharmacogenomic biomarkers. These will lead to improved biomarkers that will help better stratify pharmaceutical clinical trial populations or assist physicians to select better, more personalized, efficacious and safer therapies for their patients.

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