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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.
1

Discohesive growth pattern (Disco-p) as an unfavorable prognostic factor in lung adenocarcinoma: an analysis of 1062 Japanese patients with resected lung adenocarcinoma / 肺腺癌の予後不良因子としての非結合性増殖パターン(Disco-p):肺腺癌を切除した日本人患者1062人の解析

Kurata, Mariyo 26 September 2022 (has links)
京都大学 / 新制・課程博士 / 博士(医学) / 甲第24186号 / 医博第4880号 / 新制||医||1060(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 中山 健夫, 教授 平井 豊博, 教授 中本 裕士 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM
2

Stromal collagens in colorectal cancer and in colorectal liver metastases : tumour biological implications and a source for novel tumour markers

Nyström, Hanna January 2013 (has links)
Background: Colorectal cancer (CRC) remains one of the leading causes of cancer-related mortality. About 50 % of patients with CRC will develop subsequent liver metastases (CLM). The survival for untreated CLM is only a few months and liver resection provides the only chance for a lasting cure. It is therefore essential to detect CLM early, enabling successful surgical resection and achieving a long-term cure. There are no optimal tumour markers for CRC or CLM. The best marker available is Carcinoembryonic Antigen (CEA), a marker found elevated in about 50-60% of patients with CLM, but also in many other conditions. The main focus of cancer research has been on the malignant cancer cell. However, a tumour consists of more than cancer cells. A major part of all solid tumours is made up by the stroma. The tumour stroma is defined as the non-malignant cells of a tumour such as fibroblasts, the cells of the vascular and immune systems as well as the extracellular matrix (ECM). The basement membrane (BM) is a specialized form of the ECM in which type IV collagen is the major protein component. All epithelial cells need a contact to the BM and the definition of an invasive cancer is the degradation of the BM and the spread of cancer cells beyond this structure. Different metastatic growth patterns of CLM have previously been described, namely the desmoplastic, pushing and replacement type of CLM. These differ in their stromal reaction in the border, which separates the tumour from the normal liver. In this thesis the tumour stroma of CRC and CLM is studied with a special emphasis on stromal collagens. The aim is to investigate whether stromal collagens/ circulating type IV collagen can be used as tumour markers for CRC and CLM, and to compare this to the conventional marker CEA. The circulating type IV collagen level is also measured in liver metastases from other primary tumours than CRC. Furthermore, the differences between the stroma of a primary CRC that metastasizes to the liver when compared to a CRC that never spreads are analysed. Additionally, the metastatic growth pattern of CLM is studied in relation to the primary tumour, stromal components and survival. We also sought out to find whether CRC cell lines possess the trait to produce ECM proteins endogenously, and in response to a normal liver stroma in a novel organotypic model for CLM. Methods: Expression patterns of type I, III and IV collagen were studied by immunofluorescence (IF), chemical staining and immunohistochemistry (IHC) in normal colorectal tissue, normal liver, CRC, CLM, benign liver lesions and in liver metastases of other origin than CRC. Circulating plasma levels of type IV collagen were analysed in healthy controls, patients with CRC (T stage I-III) and in patients with CLM. Samples were analysed at the time of diagnosis, during and after oncological and surgical treatment and at the time of relapsing or progressive disease. Additionally, circulating levels were analysed in patients with benign liver lesions and in liver metastases of other origin than CRC. The metastatic growth pattern of CLM was classified according to earlier descriptions. CRC cell lines were studied regarding their production of type IV collagen. The growth, invasiveness and stromal production in CRC cell lines were also investigated in a new organotypic model for CLM using human liver specimens. Results: Circulating type IV collagen levels are increased in patients with CLM and other epithelial-derived liver metastases, and is found normal in patients with primary CRC (stage I-III), with liver metastases from tumours of non-epithelial origin, benign liver lesions and in healthy controls. The type IV collagen levels in patients with CLM reflect the tumour burden in the liver, decreases in response to therapy and is found increased in progressive or relapsing disease. The combination of circulating type IV collagen and CEA increased the sensitivity and specificity for detecting CLM. Livermetastatic CRC displayed an increased stromal production when compared to non-metastatic CRC, with an increased type IV collagen expression in the direct vicinity of the CRC cells. The earlier described growth patterns of CLM were verified, with the pushing type of CLM associated with a short survival and poor outcome. Furthermore, CRC cell lines possess the trait of endogenously producing type IV collagen. The novel organotypic liver model revealed that CRC cell lines grown in the context of normal liver stroma, devoid of other cells, does not elicit a desmoplastic reaction. Conclusion: Circulating type IV collagen is a promising tumour marker for CLM, where the levels reflect the hepatic tumour burden and can detect disease relapse after liver surgery. The combination of the tumour markers CEA and type IV collagen is superior to CEA alone. The stromal composition of primary CRC predicts the risk of subsequent CLM and the metastatic growth pattern of CLM is related to survival.
3

Entrepreneurial Growth Pattern : A Comparison Study on the Growth Pattern of Dotcoms vs. Brick-and-Mortars

Salehi Taleghani, Amir January 2012 (has links)
Entrepreneurship is the foundation of the economic for each country. It has an inevitable impact onmicro- and macro-economic factors such as GDP, economic growth, employment/unemploymentrate, regional development, etc. Thus, entrepreneurial practices are crucial for each country in orderto have better economic conditions.Growth is the dominant part of entrepreneurial practices from which the success of small firms canbe assessed and evaluated. Firm’s growth involves different aspects such as motives, finance andownership strategies, indicators, and growth stimulus. These factors together provide a pattern ofgrowth that is different from one company to another.Since the advent of the Internet there has been changes in the business world and the terms such asdotcom, digital entrepreneurship, e-services, e-banking, etc. made a dramatic change in the way ofdoing business. Some companies were established based on the Internet and their income andexistence relied on the Internet. Some others on the other hand, use traditional method of businessbesides using the Internet as an extra tool.This study examines the small business growth pattern in order to find out how small firms grow.Furthermore, the difference between the growth pattern of digital firms and traditional companies isexamined to find out how the pattern of growth differs from dotcoms to the brick-and-mortars.This study is based on a qualitative research method with the approach of a case study research. Thecase study is designed on one major case to go deep while having four other supporting companiesin order to get the best results with the least subjectivity. The questionnaire was designed on a semistructureand the results were coded for the pattern. The questions were designed based on theconceptual framework which was changes based on the results and optimized.The results from this study provide a framework that gives a pattern of growth for small firms. Thesuggested framework of growth pattern has some major components: growth motive, growthstrategy, growth indicator, and growth stimulus. Furthermore, the research findings define the majordifferences between the growth pattern of dotcoms and brick-and-mortars.
4

Protecting Stream Ecosystem Health in the Face of Rapid Urbanization and Climate Change

Wu, Hong 14 January 2015 (has links)
The ability to anticipate and evaluate the combined impacts of urbanization and climate change on streamflow regimes is critical to developing proactive strategies that protect aquatic ecosystems. I developed an interdisciplinary modeling framework to compare and contrast the effectiveness of integrated stormwater management, or its absence, with two regional growth patterns for maintaining streamflow regimes in the context of climate change. In three adjacent urbanizing watersheds in Oregon's Willamette Valley, I conducted a three-step sequence to: 1) simulate land use change under four future development scenarios with the agent-based model Envision; 2) model resultant hydrological change under the recent past and two future climate regimes using the Soil and Water Assessment Tool; and 3) assess scenario impacts on streamflow regimes using 10 ecologically significant flow metrics. I evaluated each scenario in each basin using a flow metric typology based on the magnitude of change in each metric and the degree to which such changes could be mitigated, i.e., insensitive, sensitive and manageable, and sensitive and resistant. My results demonstrated distinct signatures of urbanization and climate change on flow regimes. Urbanization and climate change in isolation led to significant flow alterations in all three basins. Urbanization consistently led to increases in flow regime flashiness and severity of extreme flow events, whereas climate change primarily caused a drying trend. Climate change tended to exacerbate the impacts of urbanization but also mitigated urban impacts on several metrics. The combined impacts of urbanization and climate change caused substantial changes to metric sensitivities, which further differed by basin and climate regime, highlighting the uncertainties of streamflow regime responses to development and the value of spatially explicit modeling that can reveal complex interactions between natural and human systems. Scenario comparisons demonstrated the importance of integrated stormwater management and, secondarily, compact regional growth. My findings reveal the need for regional flow-ecology research that substantiates the ecological significance of each flow metric, develops specific targets for manageable ones, and explores potential remedies for resistant ones. The interdisciplinary modeling framework shows promise as a transferable tool for local watershed management. This dissertation includes previously unpublished co-authored material.
5

MICROMECHANICS OF DEBOND GROWTH AND INTERFACIAL WEAR UNDER FATIGUE LOADING IN A TRANSPARENT CERAMIC COMPOSITE

Varadarajan, Bhadri Narayanan January 2000 (has links)
No description available.
6

Padrão de expansão, características morfológicas e anatômicas e valor nutritivo de lâminas foliares de capim-elefante cv. Napier / Expansion pattern, anatomical and morphological characteristics and nutritive value of leaves of elephantgrass cv. Napier

Garcia, Larissa Fernanda 08 February 2019 (has links)
Dentre as estruturas que compõem os fitômeros das gramíneas, a folha tem grande importância, pois é a fonte primária de produção de fotoassimilados para a planta como um todo e também é o componente de maior valor nutritivo. Em gramíneas, o alongamento de folhas e, consequentemente da nervura central, ocorre de forma não proporcional, afetando a morfologia e a anatomia das lâminas foliares e interferindo em seu valor nutritivo. Com o intuito de avaliar a relação entre tamanho final do limbo foliar, proporção e espessura da nervura central (NC) e sua relação com as características anatômicas e o valor nutritivo (VN) em lâminas foliares de diferentes tamanhos e ordens de inserção, foram conduzidos dois experimentos concomitantes utilizando um protocolo de plantas isoladas desenvolvido especificamente para esta finalidade no verão de 2017 (janeiro a março). A espécie estudada foi o Pennisetum purpureum Schum. cv. Napier (capim-elefante). O objetivo do primeiro experimento foi caracterizar o padrão de expansão e a morfologia da lâmina foliar seccionada em 10 fragmentos de mesmo tamanho, e caracterizar a anatomia ao longo dos segmentos basal, mediano-basal, mediano, mediano-apical e apical, ambos em lâminas foliares de perfilhos basais de diferentes tamanhos e ordens de inserção (fitômeros 5 a 16) em função de sua programação ontogênica. As coletas de amostras tiveram início a partir da expansão da 5ª folha (fitômero 5) e foram encerradas quando a 16ª folha completou sua expansão (fitômero 16). Para avaliar o efeito da idade da folha sobre a deposição de tecidos de sustentação, foram coletadas todas as folhas de dois perfilhos (um para avaliações anatômicas e um para avaliações morfológicas) no momento da expansão da 16ª folha, seguindo os mesmos critérios de avaliação descritos anteriormente. As plantas foram distribuídas segundo um delineamento em blocos completos casualizados com quatro repetições. O objetivo do segundo experimento foi caracterizar a relação entre o padrão de expansão das folhas (proporção de nervura central) e seu valor nutritivo ao longo dos segmentos de folhas descritos acima, nas mesmas folhas. A amostragem foi realizada quando a 16ª folha concluiu seu desenvolvimento e expôs sua lígula. Foram cultivadas 1320 plantas, divididas em três blocos homogêneos com 440 plantas cada, de modo a proporcionar a quantidade mínima necessária de material seco e moído para análises de proteína bruta (PB) e digestibilidade in vitro da matéria seca (DIVMS). As lâminas foliares apresentaram o mesmo padrão de expansão, apesar de diferentes valores de largura e comprimento final. A massa de nervura central variou linearmente com o aumento de massa da lâmina foliar, e apresentou redução em sua proporção da base para a porção apical da folha. Não houve variações significativas nas características anatômicas entre os segmentos das lâminas foliares quando a nervura central não foi considerada. Excluindo os segmentos em processo de senescência (fitômeros 5 a 7), as porções finais de folhas grandes apresentaram valor nutritivo semelhante àquele de folhas pequenas. As análises multivariadas de agrupamento (Cluster) e de componentes principais (PCA) agruparam e classificaram as folhas de acordo com seu nível de inserção no perfilho e aporte estrutural. As folhas mais longas foram caracterizadas como segue: 1- frações basais por altos valores de esclerênquima (ESC), massa seca da nervura (MSN), largura da nervura (LN) e mesofilo (MES) e baixos valores PB, área foliar específica (AFE), DIVMS e epiderme total (EpiT); 2- frações medianas com altos valores de feixes vasculares (FV), comprimento da folha (CF), comprimento do segmento (CS), massa seca do limbo (MSL), massa seca total (MST), largura do limbo (LL) e largura total (LT) e baixos valores de matéria mineral (MM); e 3- frações apicais (próximas ao ápice foliar) com altos valores de PB, AFE, DIVMS e EpiT e baixos valores de ESC, MSN, LN e MES. As folhas mais curtas, independentemente de suas porções ou segmentos, se caracterizaram por altos valores de DIVMS, MM, PB, EpiT e AFE e baixos valores de FV, ESC, MES, MSN, CF, CS. Os resultados podem ser utilizados para desenvolver modelos de crescimento tridimensional das plantas com a capacidade de predizer valor nutritivo e ingestão de nutrientes de animais em pastejo, bem como auxiliar no estabelecimento de metas de manejo do pastejo. / Among the structures comprising grass phytomers, the leaf is important because it is the primary source of assimilate for the entire plant and is also the component of greatest nutritive value. In grasses, leaf elongation, and consequently mid rib elongation, occurs in a non proportional way, affecting the morphology and the anatomy of the leaf blade and impacting its nutritive value. This study aimed at evaluating the relationship between final leaf blade length and the proportion and thickness of the mid rib, as well as their relation with anatomical characteristics and nutritive value along the blades of leaves with different sizes and levels of insertion on the tiller (leaf age - phytomers 5 to 16). Two concomitant experiments were carried out during summer of 2017 (January to April) using an isolated plant protocol specifically developed for this purpose. Elephantgrass (Pennisetum purpureum Schum. cv. Napier) was used as model plant. The objective of the first experiment was to characterize the pattern of leaf expansion and the morphology and anatomy of the leaf blade in sections along its length (basal, median-basal, median, median-apical, apical) using leaves of different sizes and levels of insertion (phytomers 5 to 16) on basal tillers according to their ontogenetic organization. Sampling started when the fifth leaf (phytomer 5) completed its expansion and ended when the 16th leaf (phytomer 16) completed its expansion. In order to evaluate the effect of leaf age on the synthesis of support tissues, all leaves from two tillers (one for anatomical and other for morphological evaluations) were harvested when the 16th leaf completed its expansion, following the same procedures described above for individual leaves. The experimental design was a randomized complete block, with four replications. The objective of the second experiment was to characterize the relationship between the pattern of leaf expansion (proportion of mid rib in leaf blade) and nutritive value along the length (basal, median-basal, median, median-apical, apical portions) using leaves of different sizes and levels of insertion (phytomers 5 to 16) on basal tillers. Sampling was done when the 16th leaf completed its expansion and exposed its ligule. A total of 1,320 plants were cultivated in three homogeneous blocks of 440 plants each, ensuring the minimum amount of dry, ground material for the chemical analyses of crude protein (CP) and in vitro dry matter digestibility (IVDMD). There was a common pattern of leaf expansion despite the different final leaf blade width and length. The weight of mid rib varied linearly in relation to the increase in leaf blade mass, and showed a decreasing gradient of proportion from the basal to the apical portion of the leaf. Anatomically, there were no significant changes in tissue proportions along the length of the leaf blade when the mid rib was not considered. Except for the senescing apical portion of older leaves (phytomers 5 - 7), the apical portion of large leaves showed similar nutritive value (IVDMD and CP) to that of small leaves. The multivariate analyses of Cluster and Principal Components grouped and stratified phytomers according to their level of insertion on the tiller and structural support, with longer leaves characterized as: 1- basal portions with high values of sclerenchyma (SCL), mid rib mass (MRM), mid rib width (MRW) and mesophyll (MES) and low values of CP, specific leaf area (SLA), IVDMD and total epidermis (EPIt); 2- median portions with high values of vascular bundles (VB), leaf blade length (LBL), portion length (PL), non-mid rib leaf blade mass (LBM), total leaf blade mass (TLBM), non mid rib leaf blade width (LBW) and total leaf blade width (TLBW) and low values of mineral matter (MM); and 3- apical portion with high values of CP, SLA, IVDMD and EPIt and low values of SCL, MRM, MRW and MES. Shorter leaves were characterized by high values of IVDMD, MM, CP, EPIt and SLA and low values of VB, SCL, MES, MRM, LBL and PL. The results can be used for developing tridimensional plant growth models capable to estimate the nutritive value and nutrient intake by grazing animals, as well as to assist in establishing grazing management targets.
7

Cell adhesion proteins in different invasive patterns of colon carcinomas : a morphometric and molecular genetic study

Hahn-Strömberg, Victoria January 2008 (has links)
Colorectal carcinoma is the second most common type of cancer in both men and women in Sweden. Cancer of the colon and rectum are often considered together and their ten year survival rate is approximately 50 – 60 % depending on sex and location. Different histopathological characteristics of such cancers, including the complexity of growth, are of importance for prognosis. This thesis has compared different morphometric methods in order to achieve a quantitative and objective measurement of the invasive front of colon carcinoma. Since the growth pattern is dependent on the cell adhesiveness of different proteins we studied the distribution and localization of E-cadherin, Beta-catenin, Claudin 1,2,7 and Occludin as well as screened the genes for mutations. We found a perturbed protein expression of E-cadherin, Beta-catenin, Claudin 1,2,7 and Occludin in tumor sections compared to normal mucosa, but no relation to tumor volume or growth pattern could be seen. The tumor volume was found to be correlated to the growth pattern but not responsible to the perturbed protein expression. In the mutation screening we found a SNP in exon 13 the E-cadherin gene in the tumor, as well as in exon 2 of Claudin 1 and exon 4 of Claudin 7 in both tumor and normal mucosa. No correlation between mutations and growth pattern or tumor volume was found. In conclusion, this thesis shows that the computer image analysis with estimation of fractal dimension and number of free tumor cell clusters is superior to the semi quantitative visual grading of tumor invasive complexity. The aberrant expression of cell adhesion proteins in the tumor compared to normal mucosa as well as polymorphisms in the cell adhesion genes CLDN1 and CLDN7 in both tumor and normal mucosa can suggest that these aberrations are important in the tumorigenesis of colon carcinoma.
8

Growth and progression in colorectal cancer

Hörkkö, T. (Tuomo) 21 November 2006 (has links)
Abstract Colorectal cancer is the second most common malignancy in the Western World. The overall 5-year survival is still only 50–60%. Thus, better prognostic markers are needed to improve survival of the disease. Most colorectal cancers develop from pre-existing adenomas including conventional, flat and serrated adenomas. The most important prognostic factors include tumour stage, histologic subtype and poor differentiation. The prognosis of colorectal cancer depends mainly on tumour stage. The growth of colorectal cancer is determined by cell proliferation, differentation and apoptosis. The progression of colorectal cancer is associated with the growth pattern of colorectal cancer and its invasive margin. Cancer cell budding means the presence of cells scattered in the stroma at the invasive margin, and is associated with β-catenin, an adhesion protein involved in the nuclear Wnt/β-catenin pathway. Hormones may be directly involved in the growth of a cancer, for example sex hormones play an important role in the development of most gynaecological cancers. The knowledge about the dependency of cancers on other hormones, such as thyroid hormones, is limited. This thesis focuses on factors affecting growth and prognosis in colorectal cancer. Antibodies for Ki-67, caspase cleavage site for keratin 18, β-catenin and TRβ1 were used to determine their possible associations with colorectal cancer growth patterns and the characteristics of the invasive margin. Apoptosis and proliferation were decreased at the invasive margin, particularly in serrated adenocarcinomas. The invasive margin showed a presence of budding cell clusters in 24.0% of the cases and this predicted a very poor 5-year-survival (15.4%, P < 0.00001), but nuclear β-catenin accumulation did not predict budding. Thyroid hormone receptor TRβ1 was associated with polypoid growth, presence of KRAS mutations and also with a higher WHO histological grade and advanced Dukes' stage, and in in vitro analysis, thyroid hormone T3 had a modulatory effect on colorectal cancer cell protein synthesis and apoptosis. In conclusion, the growth type of colorectal cancer, i.e. conventional polypoid, flat or serrated, has an association with the characteristics of the invasive margin. Budding margin is associated with poor prognosis in colorectal cancer, and could be utilised in diagnostic pathology. Association of TRβ1 expression with polypoid growth pattern and the presence of KRAS mutations suggest that abnormalities in thyroid hormone signalling involving TRβ1 play a role in the development of some types of colorectal adenocarcinomas.
9

Instabilité développementale chez les racines latérales du maïs : une analyse multi-échelle / Developmental instability in lateral roots of maize : a multi-scale analysis

Moreno-Ortega, Beatriz 12 December 2016 (has links)
Dans l’optique d’une seconde Révolution Verte, visant, à la différence de la première, à accroître les rendements des cultures dans un contexte de faible fertilité, les stratégies mises en place par les plantes pour une assimilation optimale des nutriments du sol se trouvent au cœur du problème. Afin de le résoudre et d’identifier les variétés idéales parmi la diversité génétique des plantes cultivées, les systèmes racinaires, leur développement et leur architecture, sont appelés à jouer le premier rôle. La variabilité au sein des racines latérales semble s’avérer une caractéristique cruciale pour l’optimisation de l’exploration du sol et de l’acquisition de ses ressources mobiles et immobiles, mais ce phénomène est encore mal appréhendé.Le travail présenté dans cette thèse se concentre sur les racines latérales du maïs (Zea mays L.) dans un effort pour révéler les processus à l’origine des variations intrinsèques dans le développement racinaire. Il s’appuie en particulier sur le phénotypage des racines latérales à une échelle sans précédent, suivant la croissance journalière de milliers d’entre elles à haute résolution spatiale, pour caractériser précisément les variations spatio-temporelles entre et au sein des individus racinaires. Les profils individuels de vitesse de croissance ont été analysés à l’aide d’un modèle statistique qui a identifié trois principales tendances temporelles dans les vitesses de croissance menant à la définition de trois classes de racines latérales avec une vitesse et durée de croissance distinctes. Des différences de diamètre à l’émergence de ces racines (dont l’origine remonte au stade du primordium) conditionnent probablement la tendance ultérieur de croissance mais ne suffisent pas à déterminer le destin de la racine. Finalement, ces classes racinaires sont distribuées aléatoirement le long de la racine primaire, ce qui suggère qu’aucune stimulation ou inhibition locale n’existe entre racines voisines.Pour expliquer l’origine des variations observées dans la croissance, ce travail a été complété par une caractérisation multi-échelle de groupes de racines latérales présentant une croissance distincte, à un niveau cellulaire, anatomique et moléculaire. Un effort particulier a été dirigé à l’analyse des profils de longueur de cellules dans des apex racinaires pour lequel nous avons introduit un modèle de segmentation pour identifier des zones développementales. Grâce à cette méthode, une forte modulation dans la longueur des zones de division et d’élongation a été mise en évidence, en lien avec les variations de la croissance des racines latérales. Le rôle régulateur de l’auxine sur l'équilibre entre les processus de prolifération et d’élongation cellulaire a été montré avec l’utilisation de lignées mutantes. En fin de compte, les variations de la croissance entre racines latérales sont remontées jusqu’à l’allocation d’assimilats carbonés et la capacité de transport de la racine, ce qui suggère l’existence d’un mécanisme de rétroaction qui pourrait jouer un rôle déterminant dans la mise en place de tendances contrastées dans la croissance des racines latérales. / In the perspective of a second Green Revolution, aiming, unlike the first one, to enhance yields of crops in a low fertility context, the strategies used by plants for an optimal uptake of soil nutrients are at the core of the problem. To solve it and identify ideal breeds among the genetic diversity of crops, plant root systems, their development and their architecture, are called upon to play the leading role. The variability among secondary roots appears as a crucial feature for the optimality of soil exploration and acquisition of mobile and immobile resources, but this phenomenon remains poorly understood. The work presented in this thesis focuses on the lateral roots of maize (Zea mays L.) and attempts to unravel the processes at the origin of intrinsic variations in lateral root development. It relies notably on the phenotyping of individual lateral roots at an unprecedented scale, tracking the daily growth of thousands of them at a high spatial resolution, in order to characterize precisely the spatio-temporal variations existing both between and within root individuals. Individual growth rate profiles were analyzed with a statistical model that identified three main temporal trends in growth rates leading to the definition of three lateral root classes with contrasted growth rates and growth duration. Differences in lateral root diameter at root emergence (originating at the primordium stage) were likely to condition the followed growth trend but did not seem enough to entirely determine lateral root fate. Lastly, these lateral root classes were randomly distributed along the primary root, suggesting that there is no local inhibition or stimulation between neighbouring lateral roots. In order to explain the origin of the observed differences in growth behaviour, we complemented our study with a multi-scale characterization of groups of lateral roots with contrasted growth at a cellular, anatomical and molecular level. A particular focus is set on the analysis of cell length profiles in lateral root apices for which we introduced a segmentation model to identify developmental zones. Using this method, we evidenced strong modulations in the length of the division and elongation zones that could be closely related to variations in lateral root growth. The regulatory role of auxin on the balance between cellular proliferation and elongation processes is demonstrated through the analysis of mutant lines. Ultimately, variations in lateral root growth are traced back to the allocation of carbon assimilates and the transport capacity of the root, suggesting that a feedback control loop mechanism could play a determinant role in the setting out of contrasted lateral root growth trends.
10

Drosophila Eye Model to Study Dorso-Ventral (DV) Patterning and Neurodegenerative Disorders

Gogia, Neha January 2019 (has links)
No description available.

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