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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

Development of computational approaches for whole-genome sequence variation and deep phenotyping

Haimel, Matthias January 2019 (has links)
The rare disease pulmonary arterial hypertension (PAH) results in high blood pressure in the lung caused by narrowing of lung arteries. Genes causative in PAH were discovered through family studies and very often harbour rare variants. However, the genetic cause in heritable (31%) and idiopathic (79%) PAH cases is not yet known but are speculated to be caused by rare variants. Advances in high-throughput sequencing (HTS) technologies made it possible to detect variants in 98% of the human genome. A drop in sequencing costs made it feasible to sequence 10,000 individuals including 1,250 subjects diagnosed with PAH and relatives as part of the NIHR Bioresource - Rare (BR-RD) disease study. This large cohort allows the genome-wide identification of rare variants to discover novel causative genes associated with PAH in a case-control study to advance our understanding of the underlying aetiology. In the first part of my thesis, I establish a phenotype capture system that allows research nurses to record clinical measurements and other patient related information of PAH patients recruited to the NIHR BR-RD study. The implemented extensions provide a programmatic data transfer and an automated data release pipeline for analysis ready data. The second part is dedicated to the discovery of novel disease genes in PAH. I focus on one well characterised PAH disease gene to establish variant filter strategies to enrich for rare disease causing variants. I apply these filter strategies to all known PAH disease genes and describe the phenotypic differences based on clinically relevant values. Genome-wide results from different filter strategies are tested for association with PAH. I describe the findings of the rare variant association tests and provide a detailed interrogation of two novel disease genes. The last part describes the data characteristics of variant information, available non SQL (NoSQL) implementations and evaluates the suitability and scalability of distributed compute frameworks to store and analyse population scale variation data. Based on the evaluation, I implement a variant analysis platform that incrementally merges samples, annotates variants and enables the analysis of 10,000 individuals in minutes. An incremental design for variant merging and annotation has not been described before. Using the framework, I develop a quality score to reduce technical variation and other biases. The result from the rare variant association test is compared with traditional methods.
42

Multispectral aerial images to phenotype yield potential and tree inventory mapping: case studies in dry pea (Pisum sativum) and apple (Malus domestica) nursery / Imagens aéreas multiespectrais para fenotipagem e contagem de plantas: estudos de caso em ervilha (Pisum sativum) e viveiro de maçã (Malus domestica)

Quiros Vargas, Juan Jose 25 October 2017 (has links)
Field data collection involves time and money consuming processes, additionally carrying possible measurement errors. With the technological advance in the last years, low cost remote sensing tools have emerged to facilitate procedures for in-field measurements, being one of the most known techniques the use of multispectral cameras coupled to RPA. These tools are complemented by the implementation of procedures in GIS and image-processing software, from which are developed methodologies leading to extract target values from a certain original set of data. In this work, multispectral images were used in two case studies: (1) for yield estimation in pea plots for breeding research, and (2) for plant counting in an apple nursery planted directly on the soil; both fields are located in Washington State, USA. In the first case, a reliable and replicable methodology for yield estimation was created as a high throughput phenotyping technique; while in the second case an algorithm capable of identifying the number of apple plants with more than 95% accuracy was developed. In both studies, remote sensing is used as an efficient and practical way to improve field operations under the specified conditions of each case. / A coleta de dados de campo envolve processos de grande consumo em tempo e dinheiro, ademais de levar o risco de possíveis erros de medição. Com o avanço tecnológico nos últimos anos, surgiram ferramentas de sensoriamento remoto de baixo custo para facilitar procedimentos de medição em campo, sendo uma das técnicas mais conhecidas o uso de câmeras multiespectrales acopladas a um ARP. Essas ferramentas são complementadas pela implementação de procedimentos em programas SIG e de processamento de imagens, a partir dos quais são desenvolvidas metodologias que visam extrair valores alvo desde um determinado conjunto original de dados. Neste trabalho, foram utilizadas imagens multiespectrais no desenvolvimento de dois estudos de caso: (1) para estimativa de produtividade em parcelas para pesquisa de ervilha, e (2) para contagem de plantas em um viveiro de maçã plantado diretamente no solo; ambos os campos localizados no estado de Washington, EUA. No primeiro caso, foi criada uma metodologia confiável e replicável para estimativa de produtividade como técnica de fenotipagem de alto rendimento; enquanto no segundo caso, foi desenvolvido um algoritmo capaz de identificar o número de plantas de maçã com mais de 95% de exatidão. Em ambos os estudos, o sensoriamento remoto é usado como uma ferramenta eficiente e prática na melhora de operações de campo.
43

Identification of growth-related tonoplast proteins in Arabidopsis thaliana

Arvidsson, Samuel Janne January 2010 (has links)
In a very simplified view, the plant leaf growth can be reduced to two processes, cell division and cell expansion, accompanied by expansion of their surrounding cell walls. The vacuole, as being the largest compartment of the plant cell, plays a major role in controlling the water balance of the plant. This is achieved by regulating the osmotic pressure, through import and export of solutes over the vacuolar membrane (the tonoplast) and by controlling the water channels, the aquaporins. Together with the control of cell wall relaxation, vacuolar osmotic pressure regulation is thought to play an important role in cell expansion, directly by providing cell volume and indirectly by providing ion and pH homestasis for the cytosoplasm. In this thesis the role of tonoplast protein coding genes in cell expansion in the model plant Arabidopsis thaliana is studied and genes which play a putative role in growth are identified. Since there is, to date, no clearly identified protein localization signal for the tonoplast, there is no possibility to perform genome-wide prediction of proteins localized to this compartment. Thus, a series of recent proteomic studies of the tonoplast were used to compile a list of cross-membrane tonoplast protein coding genes (117 genes), and other growth-related genes from notably the growth regulating factor (GRF) and expansin families were included (26 genes). For these genes a platform for high-throughput reverse transcription quantitative real time polymerase chain reaction (RT-qPCR) was developed by selecting specific primer pairs. To this end, a software tool (called QuantPrime, see http://www.quantprime.de) was developed that automatically designs such primers and tests their specificity in silico against whole transcriptomes and genomes, to avoid cross-hybridizations causing unspecific amplification. The RT-qPCR platform was used in an expression study in order to identify candidate growth related genes. Here, a growth-associative spatio-temporal leaf sampling strategy was used, targeting growing regions at high expansion developmental stages and comparing them to samples taken from non-expanding regions or stages of low expansion. Candidate growth related genes were identified after applying a template-based scoring analysis on the expression data, ranking the genes according to their association with leaf expansion. To analyze the functional involvement of these genes in leaf growth on a macroscopic scale, knockout mutants of the candidate growth related genes were screened for growth phenotypes. To this end, a system for non-invasive automated leaf growth phenotyping was established, based on a commercially available image capture and analysis system. A software package was developed for detailed developmental stage annotation of the images captured with the system, and an analysis pipeline was constructed for automated data pre-processing and statistical testing, including modeling and graph generation, for various growth-related phenotypes. Using this system, 24 knockout mutant lines were analyzed, and significant growth phenotypes were found for five different genes. / Sehr vereinfacht gesagt kann Blattwachstum auf zwei Prozesse reduziert werden, Zellteilung und Zellexpansion, gefolgt von Zellwandexpansion. Die Vakuole, das größte Organell der Zelle, übt durch die Kontrolle des Wasserhaushaltes der Pflanze eine wichtige Funktion im Zusammenhang mit der Zellexpansion aus. Dies geschieht durch die Regulierung des osmotischen Druckes, durch Import und Export von organischen und anorganischen Ionen über die Vakuolenmembran (den Tonoplast) und durch die Kontrolle ihrer Wasserkanäle (der Aquaporine). Es wird angenommen, dass die Regulierung des vakuolären osmotischen Druckes eine große Rolle bei der Zellexpansion spielt, da der osmotische Druck die Stärke der mechanischen Kraft des Tonoplast auf die Plasmamembran und die Zellwand bestimmt. In dieser Dissertation wird die Rolle von Tonoplastproteinen und ihrer Gene auf die Zellexpansion anhand der Modellpflanze Arabidopsis thaliana (Ackerschmalwand) untersucht, und Kandidaten für wachstumsrelevante Gene werden identifiziert. Da bisher noch kein Signal für die Lokalisierung von Proteinen im Tonoplast identifiziert wurde, gibt es keine Möglichkeit, genomweite Voraussagen über solche Proteinlokalisierungen zu machen. Daher haben wir eine Reihe von aktuellen Proteom-Studien genutzt, um eine Liste von 117 Genen, die für transmembrane tonoplastproteinkodierende Gene kodieren, zusammenzustellen. Zusätzlich wurden andere wachstumsrelevante Gene und Zellzyklus-Gene in die Liste aufgenommen (38 Gene). Die Expression der Gene während der Blattentwicklung sollte mittels einer sensitiven Technik, der quantitativen Polymerasekettenreaktion (qPCR), untersucht werden. Um rasch die für dieses Verfahren notwendigen Oligonukleotide zu entwerfen, wurde ein Computerprogramm („QuantPrime“) entwickelt. Das Programm entwirft automatisch solche Oligonukleotide und überprüft deren Spezifizität in silico auf Ebene der Transkriptome und Genome um Kreuz-Hybridisierungen zu vermeiden, die zu unspezifischen Amplifikationen führen würden. Die qPCR-Plattform wurde in einer Expressions-Studie eingesetzt, um wachstumsrelevante Gen-Kandidaten zu identifizieren. Um wachstumsaktive und nichtaktive Prozesse vergleichen zu können, wurden Proben von unterschiedlichen Bereichen des Blattes zu unterschiedlichen Wachstumsstadien beprobt. Eine musterbasierte Expressionsdatenanalyse wurde eingesetzt, um die Gene hinischtlich ihrer Assoziation mit der Blattexpansionen in eine Rangordnung zu bringen. Die Gene mit dem höchsten Rang wurden als Kandidaten für weitere Experimente ausgewählt. Um die funktionelle Beteiligung dieser Gene auf einer makroskopischen Ebene zu untersuchen, wurden Knockout-Mutanten für die Gen-Kandidaten hinsichtlich ihres Wachstums analysiert. Zu diesem Zweck wurde ein System für die automatisierte Phänotypisierung des Blattwachstums etabliert. Zum einen wurde ein Programm-Paket für detaillierte Annotation von Wachstumsstadien und zum anderen ein Analyse-Paket für automatisierte Datenvorbereitung und statistische Tests entwickelt. Das Analyse-Paket erlaubt die Modellierung und graphische Darstellung verschiedener wachstumsrelevanter Phänotypen. Mit Hilfe dieses Systems wurden 24 Knockout-Mutanten untersucht und signifikante Phänotypen wurden für fünf verschiedene Gene gefunden.
44

Novel technologies for high-throughput and high-content studies on zebrafish larvae

Pardo, Carlos 08 June 2015 (has links)
The zebrafish larva is an ideal candidate for in vivo high-throughput screening: it is a small vertebrate, it is optically transparent, possesses complex organs, and is easy to culture. In addition, genetic mutants and models of human diseases are widely available. Despite these attractive features there are no tools capable of screening at sufficient throughput and resolution to fully exploit the zebrafish. Here, I present a collection of technologies that enable high-throughput studies on zebrafish larvae at cellular resolution. / Engineering and Applied Sciences
45

Genetic polymorphism in dextromethorphan metabolism by CYP2D6 and CYP3A4 enzyme isoforms / Mthokozisi Muziwandile Nkosingiphile Mgwabi

Mgwabi, Mthokozisi Muziwandile Nkosingiphile January 2003 (has links)
Most administered drugs are metabolised in the liver by Phase I enzymes and more importantly by the cytochrome P450 (CYP) system. The extent of first-pass metabolism is important in determining whether the drug will have therapeutic or adverse effects after being administered to a patient. To date the CYP family has been shown to consist of 74 families denoted as CYPl to CYP118, and only a few families are significantly involved in drug metabolism. CYP3A4 is the most important isoenzyme followed by CYP2D6, CYP2C9, and CYP2C19 with a small contribution by CYP2E1, CYP2A6, and CYPlA4. CYP2D6 and CYP3A4 enzyme isoforms have been well established to exhibit interethnic and interindividual variability with regard to drug metabolising capacity. Mutation on the gene coding for a metabolising enzyme is a major cause of variation in drug metabolism. This mutation gives rise to allelic variants producing enzymes with altered metabolising activity. The presence of an allele with decreased metabolic activity in an individual gives rise to the poor metabolising (PM) phenotype. When the PM phenotype occurs at a frequency of more than 1% within a given population, then the term genetic polymorphism applies. The aberrant metabolic capacity translates into variable drug responses of more than 20-fold, leading to different susceptibility to sub-therapeutic effects or adverse drug reactions. A significant number of drugs, such as the B-adrenergic blockers, antidepressants, antipsychotic and antiarrhythmic agents, are entirely or partly metabolised by CYP2D6 and CYP3A4. Genetic polymorphism is especially important for drugs with a narrow therapeutic/toxicity window. Phenotyping involves the use of a probe drug that is administered to the subject, followed by determination of the parent drug and its metabolites in the urine. The aim of this study was to develop and validate an HPLC method for phenotypic determination of the CYP3A4 and CYP2D6 enzymes, followed by the application of the assay in a random heterogeneous population of males. Dextromethorphan (DXM) was used as an in vivo probe for simultaneous determination of the phenotypic expression of CYP2D6 and CYP3A4. An HPLC method coupled with a fluorescence detector was developed for the phenotypic determination of CYP2D6 and CYP3A4 iso-enzymes as determined by the concentration of dextromethorphan/dextrophan (DXM/DX) and dextromethorphan/3methoxy-morphinan (DXM/3MM) metabolic ratios respectively. The compounds were separated on a phenyl column (150 x 4,6 mm, 5-um particle size) serially connected to nitrile column (250 x 4,6 mm, 5-um particle size) using mobile phase of 80% (1.5% glacial acetic acid and 0.1% triethyl amine in distilled water) and 20% acetonitrile. Solid phase extraction was used to extract the analytes from urine samples using silica cartridges. The suitability of the method was demonstrated in a preliminary study with sixteen healthy Caucasian males. After a single oral 30 mg DXM dose, the volunteers were required to collect all urine samples voided 8 hours post oral dose. DXM/3HM and DXM/DX metabolic ratios were determined from collected urine samples. The method was validated for DXM and DX at a concentration range of 0.25 - 30 ug/ml, and at 0.025 - 3 ug/ml for 3MM. Calibration curves were linear with R2 values of at-least 0.999 for all compounds of interest. Recoveries were 97%, 93%, and 65% for DX, DXM and 3MM, respectively. The method was reproducible with intra-day precision having coefficients of variation percentage (CV%) of less than 17% for all analytes. Inter-day precision had a CV% of less than 14% for all analytes. The limit of detection was 30 ug/ml for all compounds. All volunteers were classified with an extensive metaboliser (EM) phenotype. In conclusion the method described is suitable for polymorphic determination of CYP2D6 and CYP3A4 in a population study, and may have value in further studies planned at investigating the critical issue of racial genetic polymorphism in ethnic groups in South Africa. / Thesis (M.Sc. (Pharm.))--North-West University, Potchefstroom Campus, 2004.
46

Modeling neuropsychiatric phenotypes in mice in the frame of translational neuroscience

Tantra, Martesa 17 September 2013 (has links)
No description available.
47

Genetic polymorphism in dextromethorphan metabolism by CYP2D6 and CYP3A4 enzyme isoforms / Mthokozisi Muziwandile Nkosingiphile Mgwabi

Mgwabi, Mthokozisi Muziwandile Nkosingiphile January 2003 (has links)
Most administered drugs are metabolised in the liver by Phase I enzymes and more importantly by the cytochrome P450 (CYP) system. The extent of first-pass metabolism is important in determining whether the drug will have therapeutic or adverse effects after being administered to a patient. To date the CYP family has been shown to consist of 74 families denoted as CYPl to CYP118, and only a few families are significantly involved in drug metabolism. CYP3A4 is the most important isoenzyme followed by CYP2D6, CYP2C9, and CYP2C19 with a small contribution by CYP2E1, CYP2A6, and CYPlA4. CYP2D6 and CYP3A4 enzyme isoforms have been well established to exhibit interethnic and interindividual variability with regard to drug metabolising capacity. Mutation on the gene coding for a metabolising enzyme is a major cause of variation in drug metabolism. This mutation gives rise to allelic variants producing enzymes with altered metabolising activity. The presence of an allele with decreased metabolic activity in an individual gives rise to the poor metabolising (PM) phenotype. When the PM phenotype occurs at a frequency of more than 1% within a given population, then the term genetic polymorphism applies. The aberrant metabolic capacity translates into variable drug responses of more than 20-fold, leading to different susceptibility to sub-therapeutic effects or adverse drug reactions. A significant number of drugs, such as the B-adrenergic blockers, antidepressants, antipsychotic and antiarrhythmic agents, are entirely or partly metabolised by CYP2D6 and CYP3A4. Genetic polymorphism is especially important for drugs with a narrow therapeutic/toxicity window. Phenotyping involves the use of a probe drug that is administered to the subject, followed by determination of the parent drug and its metabolites in the urine. The aim of this study was to develop and validate an HPLC method for phenotypic determination of the CYP3A4 and CYP2D6 enzymes, followed by the application of the assay in a random heterogeneous population of males. Dextromethorphan (DXM) was used as an in vivo probe for simultaneous determination of the phenotypic expression of CYP2D6 and CYP3A4. An HPLC method coupled with a fluorescence detector was developed for the phenotypic determination of CYP2D6 and CYP3A4 iso-enzymes as determined by the concentration of dextromethorphan/dextrophan (DXM/DX) and dextromethorphan/3methoxy-morphinan (DXM/3MM) metabolic ratios respectively. The compounds were separated on a phenyl column (150 x 4,6 mm, 5-um particle size) serially connected to nitrile column (250 x 4,6 mm, 5-um particle size) using mobile phase of 80% (1.5% glacial acetic acid and 0.1% triethyl amine in distilled water) and 20% acetonitrile. Solid phase extraction was used to extract the analytes from urine samples using silica cartridges. The suitability of the method was demonstrated in a preliminary study with sixteen healthy Caucasian males. After a single oral 30 mg DXM dose, the volunteers were required to collect all urine samples voided 8 hours post oral dose. DXM/3HM and DXM/DX metabolic ratios were determined from collected urine samples. The method was validated for DXM and DX at a concentration range of 0.25 - 30 ug/ml, and at 0.025 - 3 ug/ml for 3MM. Calibration curves were linear with R2 values of at-least 0.999 for all compounds of interest. Recoveries were 97%, 93%, and 65% for DX, DXM and 3MM, respectively. The method was reproducible with intra-day precision having coefficients of variation percentage (CV%) of less than 17% for all analytes. Inter-day precision had a CV% of less than 14% for all analytes. The limit of detection was 30 ug/ml for all compounds. All volunteers were classified with an extensive metaboliser (EM) phenotype. In conclusion the method described is suitable for polymorphic determination of CYP2D6 and CYP3A4 in a population study, and may have value in further studies planned at investigating the critical issue of racial genetic polymorphism in ethnic groups in South Africa. / Thesis (M.Sc. (Pharm.))--North-West University, Potchefstroom Campus, 2004.
48

Duffy ir Kidd antigenų sistemų fenotipavimo ir genotipavimo reikšmė, atliekant dažnas eritrocitų transfuzijas / The value of phenotyping and genotyping of Duffy and Kidd antigen systems in case of frequent red blood cell transfusions

Remeikienė, Diana 18 June 2014 (has links)
Nors yra žinoma, kad pacientams, kuriems neseniai atliktos eritrocitų transfuzijos, kraujo grupių nustatymo hemagliutinacijos reakcija rezultatai gali būti nepatikimi dėl kraujyje cirkuliuojančių donoro ertrocitų, tačiau literatūroje nėra aiškių rekomendacijų, kuriais atvejais reikėtų naudoti molekulinius tyrimo metodus. Serologinis Duffy ir Kidd sistemų antigenų ir antikūnų prieš juos nustatymas – viena svarbiausių imunohematologinių problemų transfuzinėje medicinoje. Šiame darbe pirmą kartą Lietuvoje atlikti moksliniai tyrimai imunohematologijos srityje ir panaudoti genetiniai Duffy ir Kidd antigenų sistemų tyrimo metodai. Siekiant įvertinti Duffy ir Kidd antigenų sistemų fenotipavimo ir genotipavimo reikšmę, mes nagrinėjome klinikinių, demografinių, imunohematologinių bei su transfuzija susijusių veiksnių įtaką tyrimų rezultatams. Mūsų tyrimo metu nustatytas didesnis nei 30 proc. nesutapimų dažnis tarp Duffy ir Kidd antigenų sistemų fenotipavimo ir genotipavimo rezultatų patvirtino genetinių tyrimų naudą, atliekant dažnas eritrocitų transfuzijas. Atliekant šį darbą, pirmą kartą Lietuvoje nustatytas Duffy ir Kidd antigenų sistemų fenotipų paplitimas. Nustatytas laiko tarpas, per kurį įprastai klinikinėje praktikoje naudojamų serologinių tyrimų (hemagliutinacijos reakcijos) rezultatai gali būti patikimi, bei pateiktos atitinkamos rekomendacijos didina šio tyrimo praktinę vertę ir yra novatoriška šiuolaikinėje transfuzinėje medicinoje. / Accurate phenotyping of multitransfused patients is often complicated - mostly due to the presence of circulating transfused donor’s RBCs in the recipient’s blood, leading to discrepancies in the assessment of test results. The question when genotyping including Duffy and Kidd systems should be used for patients undergoing chronic RBC transfusions is still being discussed. Serological testing and evaluation of the antigens and antibodies of Duffy and Kidd systems are among the main problems in multitransfused patients. The research on immunohematology and blood group genetics has been caried out for the first time in Lithuania. A high rate (more than 30%) of disagreements between the results of phenotyping and genotyping in our study demonstrates the benefit of DNA-based testing for chronically-transfused patients. In order to estimate the value of phenotyping and genotyping of Duffy and Kidd antigen systems in patients undergoing long-term RBC transfusions, the impact of demographic, clinical, immunohaematological or transfusion-related factors, on the discrepancy of the results, was investigated. Time frame that could be appropriate to obtain reliable results of conventionaly used serologic tests (hemmagglutination reaction) after the last transfusion was established as well as appropriate recommendations were made. We believe that these studies could be helpful for clinical practice as well as in decreasing the risk of transfusion of red blood cells.
49

Genetic and environmental control of microfibril angle on Eucalyptus wood : its effects on wood traits and implication for selection / Contrôle génétique et environnemental de l'angle des microfibrilles dans le bois d'Eucalyptus : effets sur les propriétés du bois et implication pour la sélection

Gherardi Hein, Paulo Ricardo 16 June 2011 (has links)
Le contrôle génétique et l'environnemental de l'angle des microfibrilles (MFA), les corrélations génétiques du MFA avec d'autres caractères du bois et de croissance, et par conséquent les implications pour la sélection sont très peu documentés pour les Eucalyptus. Les objectifs de cette étude étaient d'établir la variation spatiale du MFA, de la densité du bois (ρ) et de sa rigidité (E); de déterminer les relations entre MFA et propriétés du bois et enfin d'estimer le contrôle génétique et environnemental des caractères du bois et de la croissance dans le cadre de tests clonaux et de test de descendances d'Eucalyptus au Brésil et au Congo. Méthodes classiques, résonance, diffraction des rayons-X et la spectroscopie proche infrarouge ont été combinées pour évaluer les propriétés du bois. La variation du MFA représente 44% de la variation du module spécifique (E/ρ) du bois. La densité du bois est le principal déterminant de la rigidité et de la résistance du bois alors que le MFA joue un rôle secondaire. Les estimations de l'héritabilité sont de modéré à élevées pour le MFA, ρ, E, la lignine de Klason (KL) et les caractères de croissance, selon la position spatiale et le dispositif expérimental. Le contrôle génétique du MFA, ρ et E et leurs corrélations génétiques avec KL et la circonférence à 1.3 mètre des arbres varient avec l'âge. Les résultats suggèrent que les arbres à forte croissance sont génétiquement plus aptes à produire du bois de faible densité et un MFA plus faible pour assurer la rigidité du bois nécessaire à leur développement. La plupart des propriétés du bois sont génétiquement corrélées négativement avec la croissance, bien que corrélations génétiques favorables entre propriétés du bois sont observés. Les corrélations génétiques et environnementales sont parfois de signes opposés selon les caractères considérés. Ceci peut s'expliquer par l'effet pléiotropique des gènes et/ou par le déséquilibre de liaison. Les conséquences de ces résultats sur les stratégies de sélection sont discutées selon l'usage final du bois d'Eucalyptus. / The genetic and environmental control of microfibril angle (MFA), the genetic correlations with other wood and growth traits, and therefore the implications for selection are poorly documented for Eucalyptus. Thus, the objectives of this study were to determine the spatial variation of the MFA, wood density (ρ) and stiffness (E); to determine the relationship between MFA and wood traits and finally to estimate the genetic and environmental control of wood and growth traits from clonal and progeny tests of Eucalyptus in Brazil and Congo. Conventional methods, resonance, X-ray diffraction and spectroscopy were combined to evaluate the wood properties. MFA variation accounted for 44 percent of the variation in specific modulus (E/ρ) of wood. The ρ was the prime determinant on wood stiffness and strength while the MFA played a secondary role. The heritability estimates were moderate to high for the MFA, ρ, E, Klason lignin (KL) and growth traits according to the spatial position and the experimental design. Genetic control of the MFA, ρ and E and their genetic correlations with KL and circumference of 1.3 meters of trees varied with age. The results suggest that tree with potential to grow fast are genetically more likely to produce low ρ and also to decrease the MFA for ensuring stiffness required for their development. Most wood properties were genetically negatively correlated with growth, although favorable genetic correlations between many wood traits were observed. Genetic and environmental correlations were sometimes of opposite signs according to the considered trait. This can be explained by the pleiotropic effect of genes and / or linkage disequilibrium. The implications of these findings for selection strategies are discussed according to the final use of Eucalyptus wood.
50

Microfluidics and live imaging advances : applications in host/pathogen, immunity and stem cell single cell phenotyping

Zhai, Weichao January 2018 (has links)
Live single-cell imaging has emerged as an advanced single-cell study tool for approaching a quantitative understanding of many biological questions in recent years. In previous cell studies using bulk cell measurements, the population averages can miss the information from cell to cell variability and mask the underlying signaling networks and mechanisms. Currently, some single cell analysis methods, including but not limited to, live single-cell imaging experiments that built around a fluorescent imaging setup and microfluidic devices enable the measurement and analysis of cell dynamics and responses of single cells across a population and across time. Furthermore, by changing the cells’ environmental conditions in well controlled ways, e.g. balanced steady growth, or temporal pulses, live single-cell imaging can record the cellular behaviors corresponding to these changes in exquisite details. An important question of current interest in both developmental, stem cell and cancer biology is the question of epigenetic differentiation. Continuous long-term live single-cell observations offer insights into the molecular control of cell fate. However, maintaining the imaged cells in a healthy state remains a major challenge. One of our aims in this work was to develop a semi-automated single-cell live imaging and analysis platform to obtain dynamic information of the cellular processes. An imaging incubator that controls and regulates the environmental conditions of the imaged cells also had to be designed and tested. In this thesis, I address the key design considerations of developing a single-cell live imaging platform and demonstrate the capability of this technology through three case studies. To test the design and fabrication of microfluidic devices and micro-valves in imaging malaria infected red blood cells (iRBCs), I recorded the flow of iRBCs through microfluidic channels and constrictions in Chapter 3. Our results illustrate the behaviors of iRBCs with different flow rates and the potential to offer dynamic control in studying the infection probability of iRBCs by implementing the micro-valve system. In order to develop a more adaptable live cell imaging platform, we further developed our semi-automated imaging software and in house built imaging incubator to explore the link between proliferation and differentiation of CD4+ T cells in Chapter 4. By using cells expressing an IL-13-GFP reporter, we distinguished between differentiating and non-differentiating CD4+ T cell population and demonstrated a positive association between cycling differentiation of CD4+ T cells. In Chapter 5, we incorporated the FUCCI cell reporter system in our single cell live imaging system to reveal the effect of different media conditions on the cell cycle progression and cell fate choices of mouse embryonic stem (mES) cells. By improving different factors such as longer pre-incubation time before imaging and exchanging media during the experiments, we maintained a healthy state of mES cells during live cell imaging for extended periods. We observed significant differences in time between divisions of mES cells cultured in 2i +LIF and serum + LIF media, and also small but significant differences in durations of sub-cell cycle phases (G1,G1/S,S/G2/M) between the two media conditions. We further applied this imaging setup to study the behaviors of differentiating mES cells in vitro, and observed lengthening of the G1 phase for both 2i-LIF and serum-LIF cells in agreement with literature. Overall, our semi-automated single cell imaging platform not only offers adjustable intervals between fluorescent imaging, but also provides a constant temperature and gas feeding devices that allows the cells to proliferate for extended microscope imaging. Commercially produced incubators that fit onto the microscope stage and satisfied all requirements in restriction of the cell movement, gas feeding, temperature regulation and optical accessibility are not easily available. Thus, there exists a significant potential for our imaging setup to provide a versatile and adaptable live cell imaging platform for both academia and industrial researchers.

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