Dissertations / Theses on the topic 'Morphogenesis'
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Thomas, Nicole. "Bone morphogenetic proteins and hair and wool follicle morphogenesis." Title page, contents and abstract only, 2002. http://web4.library.adelaide.edu.au/theses/09PH/09pht4592.pdf.
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Bibliography: leaves 119-135. A thesis which describes a study to establish the relative roles that the bone morphogenetic proteins BMP-2 and BMP-4 play in initiating hair and derived wool follicles by first establishing their expression patterns by in situ hybridisation and then manipulating them in vitro.
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COSBITT, NICOLE. "MORPHOGENESIS: BUILDING AS A NATIVE PLANT." University of Cincinnati / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1179327038.
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Cocho, Bermejo Ana. "EmDeplo morphogenesis." Doctoral thesis, Universitat Politècnica de Catalunya, 2012. http://hdl.handle.net/10803/97040.
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These thesis will argue about the importance of Dynamic Parametric Architecture versus Static Parametric Architecture.
Describing the architectonical and the algorithmic context within which the Emergency Deployable System emerged, it will be
discussed the importance of adaptability as the missing concept of parametric architecture.
Developing the concept of Human Oriented Parametric architecture, it will be discussed the need of implementing
time as the lost parameter in current design techniques.
Using the media-tic building, of the Spanish architect Enrique Ruiz Geli, as an example of a current design that tries
to implement new technologies and parametric ideas in its design process, it will be explained the idea of the need of the
building of working with the environment, not defending against it as the basis for a good adaptability. Geli¿s design is
currently using 104 Arduino chips for an individual control and performance of the 104 ETFE pillows of the building façade.
Through the creation of a virtual stimulus-reaction model of the system façade versus a model in which machine
learning have been implemented for a better environmental performance, the efficacy on insulation of both models will be
compared.
Morphogenetic processes idea will be discussed through also the principle of an adaptable membrane, as the
thought solution for future architecture design processes improvement.
A model implementing a unique Arduino on the façade, will control the performance of the façade patterns, through,
an Artificial Neural Network that will decide the kind of scenario the building is in, activating a Genetic Algorithm that will
optimize insulation performance of the ETFE pillows.
The final virtual model will be able to obtained the goal proposed, for this thesis, a homogeneous temperature in all
the spaces of the building of 22ºC. The maximum thermal optimization obtained, nevertheless, appears if the opening of the
pillows is free within and interval of 0 and 1 m thickness. The constrains of the opening of the ETFE pillows to three positions,
will be demonstrated more effective than a just stimulus-reaction behaviour, but also, much less effective that an
unconstrained façade system.
The EmDeplo System will work with a Global behaviour, pattern performance of the façade, but also with a local
behaviour for each pillow, giving the option of individual sun shading control.
Machine learning implementation will give the façade the possibility to learn from the efficacy of its decisions through
time, eliminating the need of an on-off behaviour for defending against the environment. Instead it will work with it, adapting to
it, and evolving with its variabilities.Esta tesis debatira la importancia de la Arquitectura Parametrica Dinamica versus la Arquitectura Parametrica Estatica.Describiento el actual escenario arquitectonico y algoritmico dentro del cual el "Emergency Deployable System" emergio,sera debatida la importancia de la adaptabilidad como el concepto perdido actualmente el la arquitectura parametrica. Desarrollando el concepto de "Human Oriented Parametric Architecture", sera discutida la necesidad de implementar el tiempo como el parametro perdido en los actuales procedimientos de diseño. Empleando el edificio Media-Tic, del arquitecto español Enrique Ruiz Geli, como un ejemplo de un diseño actual que intenta implementar nuevas tecnologias e ideas parametricas en su proceso de diseño,sera explicada la idea de la necesidad del edificio de trabajar con el entorno, no de defenderse contra el, como base para una buena adaptabilidad. El diseño de Geli usa 104 chipsArduino para un control y comportamiento individual de los 104 cojines de ETFe en su fachada. A traves de la creacion de un sistema virtual estimulo-reaccion de la fachada versus un modelo virtual en el cual el aprendizaje de maquinas ha sido implementado para un mejor comportamiento ambiental, la eficacia de ambos modelos sera compararda. La idea de los procesos Morfogeneticos sera discutida a traves del pricipio de una mebrana adaptable, como la solucion propuesta para la mejora futura del proceso de diseño arquitectonico. Un modelo implementando un unico Arduino en la fachada, controlara el comportamiento de los patrones de la fachada a traves de una Red Neuronal Artificial que decidira el tipo de escenario de entorno en que el edificio se encuentra, activando un Algoritmo Genetico que optimizara el aislamiento termico de os cojines ETFE. La maqueta virtual final sera capaz de llegar a la meta propuesta para esta tesis doctoral, una temperatura homogenea en todos los espacios del edificio de 22ºC. La maxima optimizacion termica obtenida, sin embargo, aparece si la posibilidad de apertura de los cojines ETFE es libre en un intervalo entre o y 1m de espesor. La reduccion de las posibilidades de apertura de los cojines a tres posiciones unicamente, sera demostrada como una posibilidad mejoor que el comportamiento estimulo-reaccion, sin embargo, mucho menos efectivo que una posibilidad de apertura de rango libre. El sistema EmDeplo funcionara con un comportamiento global, la variabilidad del patron de la fachada, pero tambien con un comportamiento local, el de cada cojin ETFE, dando la opcion de un control de sombra-sol individual. El aprendizaje de maquinas implementado dara a la fachada la posibilidad de aprender de la eficacia de sus decisiones a lo largo del tiempo, eliminando la necisidad de un comportamiento on-off para defenderse del entorno. En lugar de esta defensa, trabajara con el, adaptamdose a el, y evolucionando con su variabilidad.
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Saygun, Yakup. "Computational Stochastic Morphogenesis." Thesis, Uppsala universitet, Avdelningen för beräkningsvetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-257096.
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Self-organizing patterns arise in a variety of ways in nature, the complex patterning observed on animal coats is such an example. It is already known that the mechanisms responsible for pattern formation starts at the developmental stage of an embryo. However, the actual process determining cell fate has been, and still is, unknown. The mathematical interest for pattern formation emerged from the theories formulated by the mathematician and computer scientist Alan Turing in 1952. He attempted to explain the mechanisms behind morphogenesis and how the process of spatial cell differentiation from homogeneous cells lead to organisms with different complexities and shapes. Turing formulated a mathematical theory and proposed a reaction-diffusion system where morphogens, a postulated chemically active substance, moderated the whole mechanism. He concluded that this process was stable as long as diffusion was neglected; otherwise this would lead to a diffusion-driven instability, which is the fundamental part of pattern formation. The mathematical theory describing this process consists of solving partial differential equations and Turing considered deterministic reaction-diffusion systems. This thesis will start with introducing the reader to the problem and then gradually build up the mathematical theory needed to get an understanding of the stochastic reaction-diffusion systems that is the focus of the thesis. This study will to a large extent simulate stochastic systems using numerical computations and in order to be computationally feasible a compartment-based model will be used. Noise is an inherent part of such systems, so the study will also discuss the effects of noise and morphogen kinetics on different geometries with boundaries of different complexities from one-dimensional cases up to three-dimensions.
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Nelsen, Brian. "Morphogenesis a theory of places /." This title; PDF viewer required. Home page for entire collection, 2010. http://archives.udmercy.edu:8080/dspace/handle/10429/9.
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Briggs, Laura Joanne. "Flagellar morphogenesis in Trypanosoma brucei." Thesis, University of Oxford, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.427895.
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Hooley, Clare Verity. "Morphogenesis of Drosophila renal tubules." Thesis, University of Cambridge, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.604211.
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The renal or Malpighian tubules (MpTs) are the major excretory organs of insects. Drosophila has 4 MpTs, an anterior and posterior pair. During embryogenesis these MpTs undergo a morphogenetic programme such that cell rearrangement by convergent extension causes the MpTs to elongate so the short fat tubules become longer thin tubules. In addition directed migration or pathfinding occurs that the MpTs take up a specific location within the body cavity. In this study an analysis of wild type development demonstrates that several aspects of normal MpT morphogenesis are invariant whilst other aspects are less defined. The shape of an organ is a consequence of both extrinsic factors and intrinsic properties. I demonstrate that external tissues and other regulators are controlling morphogenesis of the MpTs through alterations in the cytoskeleton. I find that when the visceral mesoderm is disrupted genetically the MpTs have an aberrant morphology; the visceral mesoderm acts as an extrinsic cue for normal MpT pathfinding. The visceral mesoderm secretes Decapentaplegic (Dpp) and my analysis suggests that Dpp is an attractant controlling the normal MpT migratory behaviour. Downstream activators of the dpp signalling pathway are present in the MpTs and ectopic expression of Dpp in tissues near the extending MpTs affects their morphogenesis. The convergent extension process itself may be intrinsic to the MpTs and can be disrupted when signalling via the Rho family of small GTPases is perturbed. In order to identify novel genes involved in MpT morphogenesis I have analysed lines from a mutagenesis screen previously performed to select for MpT defects. One locus was mapped and characterised as an allele of D-Cbl, previously shown to be in inhibitor of the EGF pathway. I present evidence to show that when the regulation of EGF signalling is disrupted subtle defects on MpT morphology are observed, thus revealing a requirement for the activity of this pathway during MpT morphogenesis.
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Farzaneh, Ali. "Computational morphogenesis of city tissues." Thesis, Open University, 2017. http://oro.open.ac.uk/49302/.
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Scientific discoveries of the 20th century had a profound impact not only on the study of the natural sciences but disciplines worldwide. The studies were rooted in understanding the complex process of organisation, development and evolution in natural systems before attempting to emulate the behaviours in artificial systems, leading to the emergence of new disciplines such as systems theory, complexity science, genetics, developmental and evolutionary biology. The discoveries had a profound impact in understanding the nature of cities as they develop over time. Once considered top-down models in equilibrium, the dynamic qualities of cities could be explained through the study of dynamic complex systems, exhibiting non-deterministic characteristics that over time emerge as organised structures. These characteristics are not exclusive to cities alone; they are inherent to all complex systems. The understanding of cities as complex systems has stimulated a body of research through mathematical and scientific modelling in understanding the behaviour of cities over time. The studies have been strongly focused on the analytical performance of city morphologies and less on the relational qualities of how systems interact to produce functioning spatial configurations. With the rapid rate of urbanisation and the emergence of new cities around the world, the approach to the design of cities remains rooted in static, top-down models. The implications of such models have led to high energy consumption, lack of integration and poor performance. It is a contradiction to consider cities as complex systems but design them as simple systems. The thesis explores principles of complex systems through the study of biological morphogenesis (the formation and development of organisms over time) for their implementation in formalising a design model for the formation, development and evolution of cities. The central contribution of the thesis lies in the computational modelling of cities in three main areas. The first is the co-evolution of networks and block systems towards the generation of differentiated spatial morphologies. Network systems are generated by coupling multi-agent systems and branching systems from the mathematics of natural systems, and the block systems are generated through procedural subdivision and volumetric modelling. The process involves substantial computational coding and the integration of knowledge from outside disciplines including biology, genetics, complexity theory and mathematics. The second is the development of a unified computational model combining morphological, topological and analytical modelling. The integration of the models is contingent on the writing of classes including graph theory, centrality measures and environmental calculations - all classes were written in C#. The third area is the evolutionary modelling of urban systems. The process utilised the open-source evolutionary solver Octopus in evolving solutions. The advantage lay in the populace-based nature of the model in generating differentiated phenotypes - or geometries - as a response to multiple-objectives. The model has been designed to enable the integration of systems of different types. Analytical data can be used as input to influence the model on the types of decisions it can make. The model has also been designed to enable the exploration of multiple design objectives at varying spatial and time scales. A significant part of the design model takes advantage of open source software including the open source language C#. The software have been extensively modified by hard coding. The model is mutable so that others may add new classes and procedures in the future.
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Bunt, Stephanie Marie. "Renal tubule morphogenesis in Drosophila." Thesis, University of Cambridge, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.612231.
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Rauzi, Matteo. "Mapping Subcellular Forces Controlling Morphogenesis." Thesis, Aix-Marseille 2, 2010. http://www.theses.fr/2010AIX22025.
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Pendant le développement d’un embryon, le remodelage des tissus amène un changement de forme: les tissu peuvent s’allonger, s’envaginer, s’étirer etc. Différentes voies de signalisation règlent ces comportements dans le temps et l’espace à travers le contrôle du cytosquelette d’actine et des tensions produites par ce dernier en interaction avec le moteur moléculaire Myosine-II.Quelle est la distribution des forces subcellulaires qui contrôlent la morphogenèse des tissus? Quelle est la nature des forces engendrée set pour finir, quelle est l’origine de ces forces? Voici les questions pour lesquelles ma thèse cherche des réponses. J’utilise l’élongation de la bande germinale de l’embryon de Drosophile comme système modèle afin d’investiguer la mécanique de la morphogenèse des tissusDuring embryonic development tissue remodeling leads to shape changes: for example, tissues can elongate, invaginate, and stretch. Distinct signaling pathways regulate in space and time these behaviors through the control ofthe actin cytoskeleton and of myosin-based tension required for cell shapechange. What is the spatiotemporal pattern of subcellular forcesthat orient tissue morphogenesis? What is the nature of the generated forces and finally, what lies at the origin of such forces? These are the main questions that my thesis tries to illuminate. I use the germbandelongation of the Drosophila embryo as a model system to investigate themechanics of tissue morphogenesis
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Balbi, Valentina. "Modeling morphogenesis in living matter." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066382/document.
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Parmi les processus fondamentaux qui ont lieu pendant le développement d'un organisme, la morphogenèse est un des plus complexes. De nombreuses études expérimentales ont contribué à mieux comprendre les mécanismes morphogénétiques dans les organismes vivants. Cependant peu de modèles mathématiques ont été proposés afin d'étudier la morphogenèse dans les tissus vivants. Dans ce contexte, la thèse se propose de développer de nouveaux modèles mathématiques pour étudier les changements de forme dans les tissus mous tubulaires. L'approche adoptée est macroscopique où le tissu biologique est considéré comme un milieu continu déformable. L'hypothèse principale sur laquelle se basent les modèles proposés est la suivante: pendant les processus de croissance et remodelage, des contraintes résiduelles peuvent s'accumuler dans le tissu et, une fois une valeur critique dépassée, le mener à un changement morphologique sous la forme d'une instabilité élastique. Pour cela, les modèles développés intègrent les théories modernes de croissance et remodelage, dans le cadre de la thermomécanique des systèmes ouverts. Ensuite, l'analyse de stabilité linéaire permet de calculer les seuils et modes de l'instabilité élastique en utilisant la méthode des déformations incrémentales superposées aux déformations finies. L'ensemble de ces techniques (théorie morpho-élastique) est utilisé dans cette thèse afin de modéliser deux différents processus morphogénétiques ayant lieu dans les tissus mous tubulaires : la formation d'une variété des formes dans le système gastro-intestinal et le flambage hélicoïdal dans les organes tubulaires avec précontraintesAmong the fundamental processes involved in the development of an organism, morphogenesis is one of the most complex. During the past centuries, an amount of experimental studies have improved our actual knowledge of the mechanisms which drive many morphogenetic processes in living organisms. Only recently, experiments have been complemented with mathematical modeling as a tool for proving novel insights on morphogenesis in soft tissues. In this context, this thesis aims at developing new mathematical models for the formation of patterns and forms in soft tubular organs. A macroscopic approach is adopted, where the tissue is considered as a continuum body undergoing growth and remodeling. The main idea behind the proposed models is that during growth and remodeling, residual stresses can arise and once they exceed a critical value, an elastic instability can occur in the tissue and lead to a morphological change. Therefore, the morphoelastic models are developed integrating the modern theories of growth and remodeling within the framework of the thermo-mechanics of open systems. The occurrence of the elastic instability is investigated using the method of incremental deformations superposed on finite deformations. The critical thresholds for the onset of the instability are determined together with the modes of the associated instability pattern. The morphoelastic theory is applied to the modeling of different morphogenetic processes occurring in soft tubular organs and gives useful insights in two interesting problems: the formation of the wide range of patterns in the gastro-intestinal system and the occurrence of torsional instabilities in pre-stressed tubular organs
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Ding, Mei. "Epidermal morphogenesis in Caenorhabditis elegans /." Diss., Digital Dissertations Database. Restricted to UC campuses, 2004. http://uclibs.org/PID/11984.
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Lehmann, Naida L. "Homeosis in floral development emphasizing the perianth and androecium." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=28820.
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Homeosis, the expression of features characteristic of one structure in the position of a different structure, and its role in floral development and evolution is explored in several different species of angiosperms. The expression of perianth features in stamen positions, and of inflorescence features within the flower is demonstrated in a comparative study of single- and double-flowering begonias. Floral development in three native plant species is then described, and compared to published accounts of development and phylogeny in related species to show: the expression of petal features in stamen positions in Sanguinaria canadensis; the replacement of petals with stamens and vice versa within and among plants of Actaea rubra; and the replacement of stamens with tepals in Calla palustris. These three species are all examples of naturally occurring homeosis, suggesting an important role for homeosis as an evolutionary process.
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Caraguel, Flavien. "Prolifération au cours de la régénération de la forme bilobée de la nageoire et de la peau lépidogène chez le zébrafish." Thesis, Grenoble, 2013. http://www.theses.fr/2013GRENS043/document.
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La régénération de la nageoire caudale et de la peau chez le poisson zèbre impliquent la formation d’un tissu de remplacement, structurellement et fonctionnellement identique à celui précédant la lésion. Ces mécanismes nécessitent la mise en place et la prolifération de cellules progénitrices, capables de reformer lors d’une phase de « patterning » les tissus lésés.Au cours de ma thèse j’ai étudié les évènements prolifératifs qui permettent cette néo-formation des tissus. Dans le cas de la nageoire, mes travaux ont conduit à la mise en évidence d’un mécanisme commun entre régénération et développement de croissance saltatoire des segments osseux. Ils expliquent en partie le retour à la forme bilobée observée lors de la repousse. De la même façon, dans le cas de la peau, l’avènement de la prolifération dans le derme et dans l’épiderme précède la mise en place des signaux, communs au développement, requis pour la distribution et la formation des écailles.De plus, j’ai effectué une caractérisation précise de l’ensemble du processus cicatriciel chez le poisson zèbre, conduisant à la formation d’une peau intégralement régénérée. Au cours de la cicatrisation, la fermeture de la blessure est complétée rapidement en quelques heures par migration épidermique. Une fois la zone lésée fermée, un mécanisme de morphogénèse de la peau est réactivé chez l’adulte. La prolifération cellulaire est présente simultanément dans le derme et l’épiderme. Elle n’est déclenchée qu’après la mise en place de l’assise basale de l’épiderme. Dans celui-ci, elle affecte d’une part des cellules éparses au sein de la couche basale et d’autre part la majorité des cellules de la couche intermédiaire. Ces derniers travaux suggèrent que chez les téléostéens, les cellules souches épidermiques sont localisées dans la couche basale, alors que la prolifération des cellules transientes a lieu dans la couche intermédiaire. D’autre part, ils mettent en évidence un processus commun de cicatrisation rapide en milieu liquide impliquant une fermeture de la blessure par néo-épithélialisation, semblable au cas de la cornée et de la muqueuse orale chez les mammifèresCaudal fin and skin regeneration in zebrafish both require new tissues formation, structurally and functionally identical to the former ones. They imply the formation and especially the proliferation of progenitor cells, and then during a patterning phase, they differentiate into a well-organized structure.During my PhD, I have studied in zebrafish model the proliferative events that conduct to the neoformation of caudal fin in one hand and the proliferative events implicated in the cutaneous wound healing in the other hand.The first part of this work supports the evidences of a common saltatory growth mechanism in both regeneration and development of caudal fin bony rays, and that the bi-lobed shape restoration of the fin could be a consequence of this bony segment salutary growth.During skin wound healing, proliferation is necessary in order to allow dermis and epidermis neo-morphogenesis and these events are over before the scale formation is initiated. In the second part of this study I characterized the entire skin wound healing process in the zebrafish model, from the wound closure to a fully regenerated skin including appendages. According to my results, the wound closure is a very fast event completed only in a few hours and it occurs only by epidermal cells migration. Cellular proliferation was detected after complete wound closure and once the epidermal basal layer differentiation is achieved. Cell proliferation appears to be restricted to a few basal cells whereas the major proliferation is detected in the intermediates layers of the epidermis.Taken together, these results suggest that in teleosteans, the epidermal stem cells and transient cells might be respectively located in the basal and intermediate layers. Moreover, there might be a common process due to aquatic environment, leading to a fast wound closure by re-epithelialization, between teleost skin and mammal’s cornea as well as oral mucosa
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Böhm, Bernd R. "Quantitative modelling of mouse limb morphogenesis." Doctoral thesis, Universitat Pompeu Fabra, 2011. http://hdl.handle.net/10803/31967.
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In this thesis we combine quantitative measurements of mouse limb morphogenesis and computer modelling to test a well established theory about the cellular mechanisms promoting limb elongation. A distally directed gradient of cellular proliferation was believed to be the driving mechanism for limb outgrowth. We find that the empirically measured spatial proliferation pattern fails to promote normal development - a reverse engineering algorithm was applied and revealed a proliferation pattern that could indeed carry out normal development. The differences between those patterns is dramatic and suggests that isotopic cellular proliferation alone has very little impact on limb morphogenesis and other – non isotropic - mechanisms need to be involved.En esta tesis tratamos de testar una bien establecida teor´ıa sobre los mecanismos celulares que promueven de la elongaci´on de las extremidades. Para eso combinamos mediciones cuantitativas del proceso morfogen ´etico de la extremidad del rat´on con modelos computacionales. Se cre´ıa que la fuerza conductora del crecimiento de las extremidades era un gradiente en sentido distal del incremento de la proliferaci´on celular. Descubrimos que el patr´on de proliferaci´on celular basado en medidas emp´ıricas no consegu´ıa promover un desarrollo normal, mientras que un algoritmo de ingenier´ıa inversa aplicado al proceso revel´o un patr´on que si podr´ıa. La diferencia entre estos dos patrones es inmensa y sugiere que la proliferaci´on celular isotropica por si sola tiene muy poco impacto sobre la morfog´enesis de las extremidades, indicando as´ı la necesidad de que otros procesos no isotr´opicos se hallen involucrados.
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Okuda, Satoru. "Multicellular Biomechanical Simulation of Tissue Morphogenesis." 京都大学 (Kyoto University), 2013. http://hdl.handle.net/2433/174923.
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Kyoto University (京都大学)0048
新制・課程博士
博士(工学)
甲第17557号
工博第3716号
新制||工||1566(附属図書館)
30323
京都大学大学院工学研究科マイクロエンジニアリング専攻
(主査)教授 安達 泰治, 教授 楠見 明弘, 准教授 井上 康博, 教授 琵琶 志朗
学位規則第4条第1項該当
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Cosbitt, Nicole. "Morphogenesis building as a native plant /." Cincinnati, Ohio : University of Cincinnati, 2007. http://www.ohiolink.edu/etd/view.cgi?acc%5Fnum=ucin1179327038.
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Thesis (Master of Architecture)--University of Cincinnati, 2007.Title from PDF t.p. (viewed on July 17, 2007.) Keywords: morphogenesis, morphogenetic design, emergence, emergent design. Includes bibliographical references.
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Painter, Kevin John. "Chemotaxis as a mechanism for morphogenesis." Thesis, University of Oxford, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389127.
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Bilsborough, G. D. "Leaf margin morphogenesis in crucifer plants." Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:7304164b-d674-4cef-a899-947d8497bd13.
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A key question in developmental biology is how form is generated. The model species Arabidopsis thaliana produces simple leaves with marginal outgrowths termed serrations. Serration development in A. thaliana requires both the transcription factor CUP-SHAPED COTYLEDON2 (CUC2) and the auxin efflux facilitator PIN-FORMED1 (PIN1), which regulates polar auxin transport by forming convergence points (Hay et al., 2006; Nikovics et al., 2006; Scarpella et al., 2006). In Chapter 3, I investigate how CUC2, PIN1 and auxin interact to control serration development. I demonstrate that CUC2 promotes PIN1 convergence point and auxin activity foci formation along the margin of the leaf, whilst high auxin activity represses CUC2 expression. Furthermore, interspersed peaks of CUC2 and auxin activity pattern serration development along the proximo-distal axis of the leaf. Thus, auxin, PIN1 and CUC2 form a negative feedback loop that patterns serration development. CUC genes and PIN1 are required for leaflet development in Cardamine hirsuta (Barkoulas et al., 2008; Blein et al., 2008), a close relative of A. thaliana that produces compound leaves subdivided into units termed leaflets. However, it is unclear how CUC and PIN1 interact to control leaflet development. In Chapter 4, I demonstrate that similar to A. thaliana, CUC genes promote PIN1 convergence point and auxin activity foci formation at the C. hirsuta leaf margin, whilst high auxin activity represses CUC2 expression. These genetic interactions likely create interspersed peaks of CUC2 and auxin activity that pattern leaflet development. Thus, the same negative feedback loop between CUC, PIN1 and auxin patterns both leaflet development in C. hirsuta and serration development in A. thaliana. KNOTTED1-LIKE HOMEOBOX (KNOX) genes are expressed in C. hirsuta leaves, and interact with ChCUC and PIN1 in positive and negative feedback loops, respectively, to control leaflet development (Barkoulas et al., 2008; Blein et al., 2008). KNOX genes are not expressed in A. thaliana leaves, but deeply lobed margins reminiscent of leaflets develop in association with ectopic KNOX expression in leaves (Chuck et al., 1996; Hay et al., 2006). However, it is unclear whether regulatory interactions of PIN1, CUC and KNOX which occur in C. hirsuta leaflets are employed during KNOX-induced lobe development in A. thaliana. In Chapter 5, I demonstrate that CUC2 and polar auxin transport are required for ectopic KNOX expression. Conversely, I show that KNOX misexpression up-regulates CUC2 expression in A. thaliana leaves. Thus, interactions between KNOX, CUC and PIN1 that occur in leaflet development in C. hirsuta also occur in association with KNOX-induced lobe development in A. thaliana. In addition to investigating the regulatory interactions between known components of leaf development pathways, I sought to identify novel genes that mediate CUC2-dependent serration development in A. thaliana. In Chapter 6, I identify a suppressor of the smooth margin phenotype of cuc2 leaves that partially restores PIN1 localisation in the absence of functional CUC2. Finally, in the General Discussion I evaluate how interlinking feedback loops between CUC, KNOX and auxin pattern serration and leaflet development. I then discuss why interlinking feedback loops may have been deployed to control outgrowths in both plant and animal systems.
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Leng, P. "Control of morphogenesis in Candida albicans." Thesis, University of Aberdeen, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.592939.
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This thesis describes the cloning the characterisation of three C. albicans genes: CaTBP1 encoding the TATA-binding protein, CaRAD6 encoding a ubiquitin-conjugating (E2) enzyme, the CaALS7 encoding an agglutinin-like cell-surface protein. Finally, the ALS7 promoter has been discussed. The CaTBP1 open reading frame is 716 bp long and encodes a functional TATA Binding Protein (TBP) of 27 kDa. Comparison of the predicted amino acid sequences of TBPs from a range of organisms reveals at least 80% amino acid sequence identity in the C-terminal domain. CaTbp1p binds specifically to a TATA box in vitro, substitutes for the human TBP to activate basal transcription in vitro, and suppress the lethal Δspt15 (tbp1) mutation in S. cerevisiae. CaRAD6 contains a 573-nucleotide ORF with the potential to encode a 179 amino acid polypeptide with a molecular mass of 19.7 kDa. The CaRAD6 open reading frame is interrupted by two introns which both contain consensus splicing signal sequences. A comparison of the predicted amino acid sequences of Rad6 proteins from a range of organisms reveals strong conservation within their N-terminal domains (70% amino acid sequence identity). The CaRAD6 gene complements the UV sensitivity and defective UV mutagenesis of a S. cerevisiae rad6Δ mutant. RAD6 expression decreases during hyphal development in C. albicans. Elevated RAD6 expression levels inhibit hyphal development, and Rad6p depletion enhances hyphal growth. These effects are dependent on the Efg1p morphogenetic signalling pathway. Therefore, RAD6 is a negative regulator of hyphal development, revealing for the first time, a mechanistic link between ubiquitination and fungal morphogenesis. CaALS7 is a member of the ALS gene family encoding agglutinin-like cell surface proteins in C. albicans. The ALS7sequence has a 3141-nucleotide open reading frame with the potential to encode a 1047 amino acid polypeptide.
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Horne, Kirsty L. "Characterisation of morphogenesis mutants in Arabidopsis." Thesis, Durham University, 1998. http://etheses.dur.ac.uk/4892/.
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In this thesis is described the identification and characterisation of two morphogenesis mutants of Arabidopsis thaliana. One, vertically challenged (vch1) exhibits much reduced cellular elongation. The second, altered suspensor fate (asf1) is embryonic- lethal. A thorough phenotypic analysis of both mutants is presented, as are the results of genetic analysis. Vch1 exhibits a severe reduction in cellular elongation throughout the plant, resulting in a dwarfed phenotype. Despite its stunted morphology, vch1 exhibits normal cellular patterning, demonstrating that cell morphogenesis can be uncoupled from correct cellular pattern formation, vch1 follows a normal life history by all parameters examined demonstrating that the timing of developmental events can be uncoupled from correct morphogenesis. The phenotype of vch1 cannot be rescued by the exogenous supply of a range of hormones, signalling inhibitors or growth conditions, although it can respond to each, in a proportionately similar manner to wild type seedlings. No defects in cell wall architecture nor in cytoskeletal organisation were detected during this study. Speculative models for the role of the VCH gene are proposed. In asf1, the embryo proper arrests at the transition stage of embryogenesis. The wild type suspensor is a single file of cells which serves to anchor the embryo proper to the maternal tissue and acts as a conduit for, and source of, nutrients to the developing embryo. In asf1, suspensor cells undergo inappropriate proliferation following the arrest of the embryo proper. Evidence is presented from cytological and ultrastructural examination, and expression of spatially restricted gus-fusion marker genes, that the ectopically divided suspensor cells take on aspects of embryo proper-like character. Models for the role of the ASF1 gene are proposed. It is likely that the mutant phenotype results from disruption of intercellular communication between the embryo proper and suspensor.
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許霖慶 and Lam-hing Hui. "Studies on explant regeneration and morphogenesis." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1985. http://hub.hku.hk/bib/B3120692X.
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Russell, Angela Julia. "Morphogenesis in the moss Physcomitrella patens." Thesis, University of Leeds, 1993. http://etheses.whiterose.ac.uk/1535/.
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A method was developed for recording the development of moss protonema using time-lapse video microscopy. This has provided a detailed record of the time-course of development from spore germination to the production of gametophores. Detailed records of the growth of primary and secondary chloronema, the transition of primary chloronema to caulonema, and the development of side-branches were obtained. Filaments were found to undergo the transition to caulonema earlier than previously thought. The majority of caulonemas ide-branches were found to begin as chloronema and switch to caulonema after one or two cell cycles. The early cell divisions of bud formation were found to follow a distinct pattern, which was upset by high concentrations of cytokinin and lanthanum. The response of caulonema apical cells to polarotropic light was recorded and compared to the gravitropic response. The time-lapse studies provided the basis for the further development of the quantitative analysis of protonemal branching patterns to include second and third side-branches of a sub-apical cell, and transitional caulonema. Analysing side-branch patterns should allow the detection of developmental mechanisms underlying the determination of side-branch fate. The potential of this method for assessing the effect of hormone treatments and for analysing more precisely mutant phenotypes was explored. An analysis of bud spacing was carried out to determine if the formation of a bud on a filament was inhibitory to other buds forming on the same filament. It was found, to the contrary, that buds tended to form in clusters. The hypothesis that the primary mode of action of cytokinin is an enhanced influx of calcium ions into the cell was investigated. Classical electrophysiology was used in order to detect any change in membrane potential suggestive of ionic fluxes in response to cytokinin treatment. No definitive changes in membrane potential were detected in response to cytokinin. This appeared to rule out the involvement of voltage-regulated channels in cytokinin action. The effects of some inhibitors used in studies of calcium on the moss protonemal system were examined. It is suggested that the concentrations commonly used had toxic effects that were not specific to calcium channels. The ionophore A23187 was used to characterise the protonemal response to a sustained influx of calcium. Some mutant strains were found to have a differential response to the ionophore. This may mean that they have mutations affecting their calcium regulatory system. Two new techniques of imaging calcium were used in order to detect changes in intracellular calcium in response to cytokinin. A method was developed for loading the dual wavelength fluorescent dye Indo-1 into moss protonema using iontophoretic microinjection, and intracellular calcium was imaged using ratio-image technology. Wild-type moss and some mutant strains were also successfully transformed with the gene for apoaequorin, and calcium luminescence measured in response to cold-shock and plant hormones. Some different responsesto temperatures hock were apparent in one of the transformed mutants. Preliminary experiments did not reveal any aequor independent calcium luminescence in response to cytokinin.
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Kolatsi, Maria. "Hepatocyte growth factor and renal morphogenesis." Thesis, University College London (University of London), 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243452.
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Heyman, Isobel. "Morphogenesis and differentiation of rhombomere boundaries." Thesis, King's College London (University of London), 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.283288.
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Archer, Julie Elizabeth. "Analysis of microtububule morphogenesis in vivo." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/41002.
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Bhattacharyya, Arnab. "Modelling morphogenesis as an amorphous computation." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/36794.
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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2006.Includes bibliographical references (leaves 57-58).
This thesis presents a programming-language viewpoint for morphogenesis, the process of shape formation during embryological development. We model morphogenesis as a self-organizing, self-repairing amorphous computation and describe how we can program large-scale shape formation by giving local instructions to cell-like objects. Our goal is to simulate systems that display properties, like robustness, regeneration, and evolvability, that are present in biological systems but ordinarily not present in computer systems. Consistent with the theory of facilitated variation from evolutionary biology, we find that many of these properties can be introduced and conserved by a hierarchical organization of growth specification.
by Arnab Bhattacharyya.
M.Eng.
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Brodsky, Micah Z. (Micah Zev). "Synthetic morphogenesis : space, time, and deformation." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/92963.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2014.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 127-133).
Synthetic biology has presented engineers with a fascinating opportunity: can we understand the principles of our origins { animal embryonic development - by re-engineering it in the laboratory? I investigate, from an engineer's perspective, some of problems that arise in developing geometric form in a deformable substrate. More abstractly, I attack the problem of establishing spatial patterns, when rearranging and deforming parts of the system is inherent to the process. Deformable, foam-like cellular surfaces are developed as a model for embryonic epithelia (polarized cellular sheets), one of the principal tissue types in early animal development. I explore ways in which simple agent programs running within the individual cells can collectively craft large-scale structures. The mechanical properties of the substrate prove crucial to the patterning process. In such a distributed, heterogeneous substrate, little can be assumed about the progress of time. In one branch of my work, I develop patterning techniques where convergence is transparently and locally detectable, drawing insights from clockless digital circuits and casting the problem as distributed constraint propagation. In another branch of work, I avoid the problem of timing by making all patterns self- correcting. In self-correcting patterning, I attempt to understand "canalization" - how development is naturally robust to perturbations. I formulate a model for regional patterning, inspired by regeneration experiments in developmental biology, and using mathematical principles from classical models of magnetic domains and phase separation. The problem again becomes a form of distributed constraint propagation, now using soft constraints. I explore some of the resulting phenomena and then apply the mechanism to crafting surface geometries, where self-correction makes the process robust to both damage and self-deformation. I conclude with a look at how this naturally leads to an example of partial redundancy { multiple systems that partly but not completely overlap in function - yielding confusing responses to the effects of virtual knock-out experiments, reminiscent of the confusing behavior of knock-out experiments in biology.
by Micah Z. Brodsky.
Ph. D.
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Giorgi, Mario. "Mechanobiological predictions of fetal joint morphogenesis." Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/28582.
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This PhD thesis explores, through the use of a mechanobiological simulation of prenatal joint morphogenesis, the hypotheses on how fetal movements, shapes and position impact on the shape of the developing joint. A novel mechanoregulation algorithm specific for cartilage growth was developed and, for the first time, a 3D mechanobiological simulation of joint morphogenesis in which the effects of a range of movements and different initial joint shapes was proposed. Both pre- and post-cavitational phases of joint development were simulated and the effect of rigid paralysis on joint shape was also explored. This study concluded that the starting joint configuration and applied movement are fundamental for the development of specific and anatomically recognisable joint shapes. Moreover, for the first time, a mechanobiological simulation of prenatal hip joint morphogenesis was used to investigated the effects of reduced, or asymmetric, movement at various stages of fetal hip joint development. This study concluded that normal fetal movements are important for the emergence of a physiological hip joint shape and that movements during development tend to minimise the natural trend of decreasing stability. Results showed that reduced movements at an early stage of development lead to decreased sphericity and acetabular coverage of the femoral head, increasing the risk of subluxation or dislocation of the hip. It also shows that, in the case of mal-positioning or joint laxity in utero, movements may actually lead to an abnormal hip joint shape with characteristics of developmental dysplasia of the hip (DDH). This PhD thesis has advanced the basic understanding of prenatal joint shape development and the implication that different mechanical environments within the joint region, might have on developmental skeletal diseases such as DDH.
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Brown, James. "Cell wall morphogenesis in Bacillus subtilis." Thesis, University of Newcastle upon Tyne, 2016. http://hdl.handle.net/10443/3373.
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Almost all bacteria are surrounded by a peptidoglycan cell wall. This cell wall imposes the shape of the bacterial cell and enables the cell to resist turgor pressure, localise proteins and coordinate cell division. Despite being ‘essential’, bacteria can grow and divide indefinitely in a wall-less state known as the L-form. Conventionally, L-form bacteria in the laboratory are grown at high concentrations of osmoprotectant such as salt or sucrose due to their sensitivity to turgor. However, L-forms have been isolated from various environments, including from persistent infections where such isotonic conditions may not be relevant. Here I show that L-forms derived from the Gram-positive model organism Bacillus subtilis can be readily adapted to media containing very low concentrations of osmoprotectant (sucrose or salt), lending support to theories regarding the natural role of L-forms. Regeneration of the wall of the adapted strains revealed a raft of phenotypic changes including, but not limited to: cell branching, misplaced septa and increased cell length. Whole genome sequencing of these mutant strains revealed several mutations. Among the mutations identified was a partial deletion of the gene coding for the actin homologue, MreB. In the walled state, MreB directs and coordinates the peptidoglycan synthesis machinery as a means to control the morphology of the cell. Characterisation of the mutation in mreB revealed that loss of this important protein is sufficient to enable the growth of L-forms in low osmolarites. The cell wall of Gram-positive bacteria also contains teichoic acids (TA). TAs linked to the lipids in the cell membrane (Lipoteichoic acids; LTA) are essential for the viability of the pathogen Staphylococcus aureus. In contrast, LTA is dispensable in B. subtilis, where loss of the primary synthase, LtaS, acts as a suppressor mutation in strains that lack the MreB homologue, Mbl. Based on the observation that loss of ltaS improved the growth of a Δmbl mutant in B. subtilis a screening method was previously developed from which 5 candidate actinomycete strains producing potential inhibitors of LtaS were identified. Preliminary experiments narrowed the focus to one strain that reproducibly produced an active compound, which was purified and characterised. Various properties of the compound 4 were consistent with it acting as an inhibitor of LtaS. Mass spectrometry (MS) and MS-MS data suggested a potential identity for the inhibitor that could plausibly represent a substrate analogue. Treatment with the compound impaired the growth of S. aureus.
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Anderson, Kerri-Ann. "A Mathematical Model of Cytokinetic Morphogenesis." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1429607984.
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Divakaruni, Arun Venkat. "Control of morphogenesis in Caulobacter crescentus." Diss., Restricted to subscribing institutions, 2007. http://proquest.umi.com/pqdweb?did=1428838421&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.
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Hui, Lam-hing. "Studies on explant regeneration and morphogenesis /." [Hong Kong : University of Hong Kong], 1985. http://sunzi.lib.hku.hk/hkuto/record.jsp?B1231481X.
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Enemchukwu, Nduka Obichukwu. "Bioartificial matrices to modulate epithelial morphogenesis." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/52938.
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Acute injury of major epithelial organ systems (kidney, liver, lung, etc.) is collectively a principal cause of death worldwide. Regenerative medicine promises to meet these human health challenges by harnessing intrinsic cellular processes to repair or replace damaged tissues.
Epithelial morphogenesis is a hard-wired, multicellular differentiation program that dynamically integrates microenvironmental cues to coordinate cell fate processes including adhesion, migration, proliferation, and polarization. Thus, epithelial morphogenesis is an instructive mode of tissue assembly, maintenance, and repair. Three-dimensional epithelial cell cultures in natural basement membrane (BM) extracts produce hollow, spherical cyst structures and have indicated that the BM provides the critical cell adhesion ligands to facilitate cell survival, stimulate proliferation, and promote polarization and lumen formation. However, the utility of natural BMs for detailed studies is generally limited by lot-to-lot variations, uncontrolled cell adhesive interactions, or growth factor contamination.
The goal of this thesis was to engineer bioartificial extracellular matrices (ECM) that would support and modulate epithelial cyst morphogenesis. We have engineered hydrogels, based on a multi-arm maleimide-terminated poly (ethylene glycol) (PEG-4MAL), that present cell adhesive molecules and enzymatic degradation substrates and promote polarized epithelial cyst differentiation in vitro.
To investigate the influence of matrix physical and biochemical signals on cyst morphogenesis, we independently varied the polymer weight percentage (wt%), the density of a cell adhesion ligand (RGD), and crosslink degradation rates of the hydrogels. Then, we evaluated functional outcomes including Madin-Darby canine kidney (MDCK II) epithelial cell survival, proliferation, cyst polarization, and lumen formation. We found that cell proliferation, but not cell survival, was sensitive to the polymer wt%, which is related to elastic modulus and crosslink density. This result defined a working range of PEG-4MAL concentration (3.5% - 4.5%) that promotes robust proliferation. Analysis of mature cysts indicated that 4.0% and 4.5% gels produced cysts resembling those typically grown in type I collagen gels while 3.5% gels produced cysts with higher incidence of inverted polarity and multiple lumens. Perturbation of matrix degradability using a slow-degrading crosslink peptide or matrix metalloproteinase inhibitors showed that the rate of matrix degradation exerts major influence on cyst growth in PEG-4MAL gels. We employed 4.0% PEG-4MAL hydrogels with RGD ligand density ranging over 0 – 2000 uM to discover that (1) lumen formation was eliminated in the absence of RGD, (2) extent of lumen formation increased with increasing RGD concentration, and (3) cyst polarity was inverted below a threshold of integrin binding to RGD.
Together, these results show that the biochemical and physical properties of the matrix, particularly integrin binding and matrix degradability, effectively modulate establishment of apico-basal polarity and lumen phenotypes in MDCK II epithelial cyst structures. Furthermore, these studies validate PEG-4MAL hydrogels as a powerful culture platform to enable detailed investigation of matrix-directed modulation of epithelial morphogenesis.
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Abad, Vivero Ursula Citlalli. "Morphogenesis at the shoot Apical Meristem." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEN088/document.
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Le phénomène de morphogenèse est le fruit de la division des cellules et de leur expansion, qui sont contrôlées de façon différentielle selon les types cellulaires et les tissus. Dans le cas des plantes, le méristème apical caulinaire (MAC) produit de façon continue les organes aériens à partir de primordia qui sont initiés suite à l’accumulation locale d’une hormone végétale, l’auxine. Pour étudier le processus de formation des organes aériens, nous utilisons l’inflorescence d’Arabidopsis thaliana, dont les fleurs sont mises en place selon un patron régulier à partir de cellules dérivées de cellules souches. Au cours de ce processus, ARF5/MP– un facteur de réponse à l’auxine se liant à l’ADN – joue un rôle central. Une fois activé, il induit l’expression des facteurs de transcription LEAFY, AINTEGUMENTA et AINTEGUMENTA-LIKE6, qui sont nécessaires pour la spécification de l’identité florale et pour la croissance proliférative. A l’échelle cellulaire, des excroissances latérales sont initiées suite à des hétérogénéités locales de croissance. Dans les cellules végétales, ces différences sont dues à des modifications de la paroi cellulaire impliquant l’auxine et ses cibles, qui induisent des variations dans la dynamique des microtubules corticaux résultant en des changements de direction de croissance. Dans une moindre mesure, l’auxine diminue la rigidité des parois cellulaires préalablement à la formation d’un nouvel organe, conduisant à des changements de taux de croissance. Ceci est corrélé à l’activation transcriptionnelle de nombreux gènes qui sont impliqués dans les modifications de la paroi. Ainsi, la voie de signalisation de l’auxine régule l’initiation des primordia en intégrant d’une part l’activation d’un réseau de régulation transcriptionnelle et, d’autre part, la rigidité et l’anisotropie de la paroi cellulaire, impactant directement le taux et la direction de croissance.Cette thèse soutient l’idée selon laquelle l’initiation des organes dans le MAC repose sur des boucles de rétroaction là où des changements locaux de propriétés de la paroi cellulaire influent sur le réseau moléculaire. Il est probable que d’autres hormones soient nécessaires afin de canaliser l’initiation des organesThe process of morphogenesis is driven by cell division and expansion, which are controlled ina differential manner among cell types and tissues. In plants, the above ground organs arecontinuously produced by the shoot apical meristem (SAM), where the initiation of newprimordia is triggered by the local accumulation of the plant hormone auxin. We study theprocess of morphogenesis in the inflorescence of Arabidopsis thaliana, where flowers areformed in a regular pattern from the SAM.The DNA-binding auxin response factor ARF5/MP plays a central role in the initiation offlowers. After its activation, it induces the expression of LEAFY, AINTEGUMENTA andAINTEGUMENTA-LIKE6 transcription factors necessary for the specification of floralidentity and proliferative growth. However, at the cellular level, the initiation of lateraloutgrowths depends on regional differences in growth. In plant cells, these processes areregulated via modifications of the cell wall. Auxin and its downstream targets are also involvedin these processes, by activating changes in the dynamics of the cortical microtubules, whichresult in changes in growth direction. Auxin also slightly reduces wall rigidity prior to organoutgrowth in the SAM, which results in changes in growth rate. This is correlated with thetranscriptional activation of a number of cell wall modifying genes.Thus, auxin signaling regulates primordium initiation by integrating the activation of atranscriptional regulatory network and both the stiffness and anisotropy of the cell wall, whichdirectly influence the rate and direction of growth.The findings of this thesis provide evidence indicating that the mechanisms of organ initiationat the SAM involve feedbacks where changes in the local properties of the cell wall influencethe molecular regulation of the transcriptional regulatory network. Our results suggest that thismight require the influence from other hormones, different from auxin, that funnel theinitiation of lateral outgrowths
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Partridge, Roland William. "Morphogenesis and morphology of intestinal villi." Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/28884.
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Paediatric intestinal failure following bowel resection causes significant morbidity and mortality. There is a pressing need for improved treatment modalities. Following loss of bowel, the remaining intestine undergoes a period of adaptation, characterised by an increase in height of the intestinal villi. Better understanding the factors that govern the formation and growth of villi may lead to therapeutic interventions that amplify the intrinsic adaptation response. This thesis aims to explore the processes by which intestinal villi form during embryological development, the contribution of intestinal stem cells to this, and candidate signalling pathways that may yield insights into new therapeutic interventions for patients with intestinal failure. Abstract: Aim I will examine the morphogenesis and morphology of intestinal villi by investigating three themes: 1) Villus morphogenesis: When and where do villi form along the gut tube? Can this process be quantified, both in vivo and in vitro? Is this initiated by a dominolike signaling-cascade along the bowel, or location-specific intrinsic triggers? 2) Stem cells: What is the spatiotemporal appearance of the Lgr5-expressing intestinal stem cells during development? How does this relate to the process of villus morphogenesis? 3) Signalling pathways: Can a genetic mutation mouse model help elucidate pathways by which post bowel resection adaptation might occur? Can this be used to help identify potential intestinotrophic agents? Abstract: Materials and Methods Three mice models were used as the foundation for this work. Embryonic tissue was analysed from wild-type CD1 and Lgr5-eGFP-IRES-CreERT2 mice, and adult intestinal tissue examined from tamoxifen-activated Villin-Cre-ERT2 Pten-/- Brafv600E mice. Culture of wild-type embryonic mouse intestine with and without segments removed and / or reversed was performed to investigate the question of what triggers the proximal-to-distal wave of villus morphogenesis. Immunohistochemical interrogation using anti-GFP antibodies was used in the Lgr5- GFP mice to identify the location of Lgr5-expressing cells during the development of villi. Bright-field microscopy, time-lapse in-incubator microscopy, and histological sections assessed villus morphology. The Villin-Cre-ERT2 Pten-/- Brafv600E mouse mutant was explored regarding the intestinal epithelial morphometric changes that occur following tamoxifen-induction. Abstract: Results The proximal-to-distal wave of villus morphogenesis was observed both in vivo and in vitro. Villus morphogenesis commences at embryonic day 14.5 in vivo and after three days in culture from e11.5 in vitro. The villus structures formed in vitro are significantly attenuated compared to in vivo development. An attempt was made to overcome this by providing intestinal explants with a blood supply to aid growth. Evidence is presented that suggest the proximal-to-distal wave of villus morphogenesis is driven by location specific factors intrinsic to each part of the bowel, rather than a domino-like signalling cascade travelling along the intestine. Lgr5-expressing intestinal stem cells were present in early development. Prior to villus morphogenesis they were uniformly distributed along the luminal surface of the intestinal epithelia. During the intense proliferation associated with villus morphogenesis they progressively congregated to the inter-villus spaces. Once villi are fully formed they were absent from the villi but identified in the inter-villus spaces. The Pten/Braf mouse mutant demonstrates villus morphological changes similar to those found following post-bowel resection adaptation. This suggests that there may be a role for Pten/Braf in the epithelial proliferation following extensive bowel resection. Signalling factors in these pathways may be candidate intestinotrophic agents for the treatment of short bowel syndrome. Abstract: Conclusions Before any processes that manipulate intestinal epithelia can be safely translated into therapies to aid adaptation in patients with intestinal failure, it is important to have a full and detailed understanding of the basic science principles that underpin the behaviour of the epithelial cells, both during development and in adulthood. I have explored and quantified the process of villus morphogenesis in the embryonic mouse, investigated the timing of appearance of Lgr5 intestinal stem cells, and interrogated a genetic mouse model with morphometric changes similar to those seen following small bowel resection. I propose two candidate intestinotrophic agents that may hold regenerative potential to augment post small bowel resection adaptation. The next stage of investigation would be to use a mouse model of small bowel resection with manipulation of cell signalling factors to assess impact on post resection adaptation. The ultimate goal would be to investigate epithelial activity in human neonatal intestine and explore methods of modulating this to improve the outcomes from post bowel resection intestinal failure.
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Poulain, Fabienne. "Stathmin family phosphoproteins and neuronal morphogenesis." Paris 6, 2007. http://www.theses.fr/2007PA066492.
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Le développement des prolongements neuronaux requiert une réorganisation dynamique des microtubules. Les protéines de la famille de la stathmine (dont SCG10, SCLIP et RB3) participent au contrôle de la dynamique des microtubules en séquestrant la tubuline. Leur profil d’expression dans le système nerveux suggère qu’elles jouent des rôles distincts et complémentaires lors de la morphogenèse neuronale. Cette étude visait à mieux comprendre leur diversité fonctionnelle et a permis de caractériser les fonctions spécifiques de SCLIP dans l’axonogenèse et la dendritogenèse. Nous avons ainsi démontré que SCLIP régule la morphogenèse axonale des neurones d’hippocampe différemment d’SCG10, contrôlant le développement de nouvelles branches et non la surface du cône de croissance. Nous avons de plus révélé que SCLIP est fortement exprimée dans les cellules de Purkinje lors du développement du cervelet et joue un rôle primordial dans leur développement dendritique. Ces résultats ouvrent ainsi de nouvelles perspectives quant aux régulations fonctionnelles des protéines de la famille de la stathmine dans les neurones.
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Schliffka, Markus. "Multiscale study of mouse preimplantation morphogenesis." Electronic Thesis or Diss., Université Paris sciences et lettres, 2023. http://www.theses.fr/2023UPSLS021.
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Au cours du développement embryonnaire, les animaux suivent une séquence complexe de changements de forme provoqués par des forces issues de la contractilé cellulaire, générées par le cytosquelette de l’actomyosine. Chez l’embryon de mammifère, la morphogenèse débute dès la phase préimplantatoire, qui commence par la fécondation et aboutit à la formation du blastocyste, la structure qui s’implante dans l’utérus maternel. Ainsi, l’embryon préimplantatoire suit une série de mouvements morphogénétiques contrôlés par la contractilité qui aboutissent avec la formation du premier lumen au sein du blastocyste.Nous avons mené la première étude examinant l’effet de la perte complète de contractilité sur le développement préimplantatoire. Nous avons généré les mutants maternels-zygotiques simples et double des gènes Myh9 et Myh10, codants pour les chaînes lourdes de la myosine non musculaire de type II, ce qui nous a permis d’étudier la contribution relative de ces deux paralogues dans la génération de la contractilité cellulaire. Nous avons constaté que Myh9 est le principal contributeur dans ce processus, car sa perte entraîne un retard du cycle cellulaire, une réduction du nombre de cellules, de la compaction et de la différenciation. La perte de Myh10 n’a pas d’impact fort par rapport aux embryons de type sauvage. Néanmoins, un phénotype plus sévère a pu être observé chez les embryons double mutants dont la cytocinèse échoue dans la plupart des cas, suggérant une compensation par Myh10 dans les mutants Myh9. Malgré le manque de cellules, la différenciation et la formation du lumen se poursuivent dans les double mutants. Dans les cas les plus extrêmes, des embryons composés d’une seule et unique cellule accumulent du fluide dans des compartiments intracellulaires, ce qui indique que le programme préimplantatoire est exécuté indépendamment du nombre de cellules.Dans les embryons sauvages, le blastocyste se forme suivant un processus de fracturation hydraulique produisant un réseau de microlumens qui murit en un lumen unique entourée de plusieurs cellules. Bien que le mécanisme global de ce processus soit compris, on ne sait toujours pas comment les cellules régulent localement la dynamique des microlumens. Ici, nous décrivons des blebs inversés aux contacts entre cellules. Les blebs inversés sont des invaginations membranaires de courte durée qui gonflent dans le cytoplasme avant d’être repoussées par la contractilité cellulaire. Les blebs inversés se forment à la suite de l’augmentation globale de la pression du fluide intercellulaire et du confinement local du fluide par l’adhésion cellulaire. Nous proposons que les blebs inversés agissent comme des pompes hydrauliques pour diriger le fluide au sein du réseau de microlumens, promouvant ainsi son murissement.Ces résultats approfondissent notre compréhension moléculaire, cellulaire et biophysique de la façon dont la contractilité cellulaire façonne l’embryon de mammifèreDuring development, embryos undergo a complex sequence of morphogenetic shape changes powered by cellular contractile forces which allow the embryo to correctly form tissues and organs. Contractile cellular forces in morphogenesis are chiefly generated by the actomyosin cytoskeleton. In the mammalian embryo, morphogenesis begins during preimplantation development, which commences with fertilization and leads up to the formation of the blastocyst, the structure that implants into the maternal uterus. During preimplantation development, the embryo undergoes a series of contractility-driven morphogenetic steps that culminate in the positioning of the first lumen of development in the blastocyst.Here, we conducted the first study investigating the effect of complete contractility loss on preimplantation development. We performed single and double maternal-zygotic knockout of the non-muscle myosin heavy chain genes Myh9 and Myh10, which allowed us to study the relative contribution of these two paralogs to contractility generation in preimplantation development. We found that Myh9 is the main contributor in this process, as its maternal-zygotic loss results in cell cycle delay, reduced cell number, compaction and differentiation. Loss of Myh10 did not have a strong detectable impact compared to wildtype embryos. Nevertheless, a more severe phenotype could be observed in Myh9 and Myh10 double knockout embryos as cytokinesis failed in most cases, suggesting some compensation by Myh10 in Myh9 single mutants. Despite severely reduced cell number, differentiation and lumen formation still somehow continued in double knockout embryos. In the most extreme cases, single-celled embryos accumulated fluid in intracellular compartments, indicating that the preimplantation developmental program is executed independently of cell number.In WT embryos, the blastocyst forms in a process of hydraulic fracturing producing hundreds of microlumen followed by their coarsening into a single lumen surrounded by multiple cells. While the global mechanism of this process is understood, it remains unclear how cells regulate microlumen dynamics locally. Here, we describe inverse blebs at cell-cell contacts during microlumen formation. Inverse blebs are short-lived membrane protrusions expanding into the cytoplasm before being retracted by actomyosin contraction. We show that inverse blebs form due to a global increase in intercellular fluid pressure and require local fluid confinement by cell-cell adhesion. We propose that inverse blebs serve as hydraulic pumps to push the fluid within the microlumen network, thereby supporting the coarsening of the first mammalian lumen.Together, these finding expand our molecular, cellular and physical understanding of how cell contractility shapes the early mammalian embryo
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Deacon, William Jack. "Quantification of cell and tissue behaviours during morphogenesis." Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610643.
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Joglekar, Chandrashekhar. "Widerborst Interacts With Bitesize To Regulate Wing Hair Morphogenesis." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2005. http://nbn-resolving.de/urn:nbn:de:swb:14-1122295800716-91033.
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The work presented in the thesis was carried with the aim to understand how Widerborst (Wdb) regulate planar cell polarity in Drosophila wing. In search of proteins interacting with Wdb I carried a Yeast Two Hybrid screen and identified a protein, bitesize, with tandem C2 domains in its C terminus interacting with Wdb. Wdb also interacts with btsz genetically and removal of one copy each of Wdb and btsz enhances the truncated hair phenotype observed in Wdb EMS mutants and btsz P element insertion mutants. There are at least three predicted isoforms of bitesize and loss of the btsz-II isoform is lethal. Clonal analysis of a btsz mutant, btszJ5-2, which removes the btsz II isoform resulted in truncated wing hair outgrowth. On the other hand over expression of a myc-btsz-II construct resulted in hair duplication phenotype. However, over expression of the GFP-CT is sufficient to give wing hair duplication phenotype and this hair duplication phenotype is stronger than that caused by myc-btsz-II over expression. The Myc tagged btsz-II protein shows apical localization. Though most of the protein is confined to cytoplasm, btsz-II also marks the plasma membrane. The GFP-CT construct marks the plasma membrane strongly and is enriched in the apical region. The over expression of CT domain is sufficient to give hair duplication phenotype and the strong difference observed in the localization pattern of full length btsz-II protein and GFP-CT together suggest that regulation of membrane localization of btsz through its CT region is important to regulate hair morphogenesis. As the loss of function (truncated wing hair) and gain of function (hair duplication) both affect the process of hair morphogenesis, it can be said that btsz is a positive regulator of hair morphogenesis. Since no defect in cortical polarization of Fmi was observed in cells lacking btsz-II, btsz is required for establishment of cortical domains. However with the present study it remains unknown how exactly the C2 domains might regulate hair morphogenesis and whether Wdb targets btsz for dephophorylation to PP2A catalytic subunit.
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Burn, Sally. "Origin and morphogenesis of the murine spleen." Thesis, University of Edinburgh, 2007. http://hdl.handle.net/1842/23965.
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This thesis establishes methods to investigate early spleen development in the mouse embryo. An expression analysis of early Nkx2.5 expression is reported, along with the finding that Nkx2.5 may be the earliest marker of splenic precursors in the mouse. Expression of Nkx2.5 is also shown for the first time to overlap considerably with that of Nkx3.2 – a major gut development gene upstream of Nkx2.5. An in silico analysis of the evolutionary conserved regions upstream of Nkx2.5 is presented along with the establishment and analysis of stable transgenic reporter lines expressing LacZ under the control of an Nkx2.5 gut regulatory sequence (NGRS). NGRS confers spleen, posterior stomach, and pyloric sphincter expression, with very little of the cardiac expression associated with endogenous Nkx2.5. This enhancer is thus ideal for gut studies, providing a tool for directing gut-specific expression and genetic manipulations. NGRS was also found not to require Nkx3.2 for its activity. Finally, NGRS is demonstrated to have the potential to mark abnormal spleen development, in a previously unreported splenic mutant: the Rwhs mutant. Potential uses for NGRS are explored. An approach was taken to mark and follow spleen development, using NGRS-LacZ in an organ culture system. Data generated from these experiments shed some light on how the E11.5 spleen develops, providing evidence for migration of splenic precursors along the stomach, and suggesting that an inhibitory “anchor” effect is normally exerted by the posterior spleno-pancreatic mesenchyme, disruption of which permits precocious spleen development. Finally, an analysis of the role of Wnt signalling in development of the spleno-pancreatic region is presented. Wnt signalling is active in the developing spleen at E11.5, E12.5 and E14.5. A number of Wnt and Frz genes are expressed in the E14.5 spleen.
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Sidhaye, Jaydeep. "Cellular dynamics in Zebrafish optic cup morphogenesis." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2018. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-232445.
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Organ formation is an important step during development of an organism that combines different scales from the molecular to the tissue level. Many organogenesis phenomena involve epithelial morphogenesis, where sheets of cells undergo rearrangements to form complex architectures – organ precursors, which subsequently develop into mature organs. Timely development of the characteristic architectures of the organ precursors is crucial for successful organogenesis and is determined by the choice of epithelial rearrangements that organise the constituent cells in space and time. However, for many organogenesis events the cellular dynamics underlying such epithelial rearrangements remain elusive. In the work presented here, I investigated the morphogenesis of the hemispherical retinal neuroepithelium (RNE), that serves as an organ precursor of the neural retina. Formation of RNE is an important event in vertebrates that shapes the optic cup and sets the stage for subsequent eye development. I investigated RNE morphogenesis in the developing zebrafish embryo by visualising and investigating the cellular dynamics of the process in vivo. My findings show that the zebrafish RNE is shaped by the combined action of two different epithelial rearrangements – basal shrinkage of the neuroepithelial cells and involution of cells at the rim of the developing optic cup. The basal shrinkage of the neuroepithelial cells bends the neuroepithelial sheet and starts the process of invagination. However, my results show that the major player in RNE morphogenesis is rim involution. Rim involution translocates prospective RNE cells to their designated location in the invaginating layer and contributes to RNE invagination. My work unravelled the so far unknown mechanism of rim involution. I show that the rim cells involute by collective epithelial migration using directed membrane protrusions and dynamic cell-matrix contacts. If rim migration is perturbed, the prospective RNE cells cannot reach the invaginating layer. As a result, these migration-defective cells attain the RNE fate at an ectopic location and disrupt the tissue architecture. Therefore, rim migration coordinates the cellular location with the timing of RNE fate determination and orchestrates RNE morphogenesis in space and time. Overall, my work highlights how morphogenetic processes shape the organ precursor architecture and ensure timely organ formation. These findings provide important insights not only for eye development but also for epithelial morphogenesis and organogenesis in many other systemsFür die Entwicklung eines Organismus ist die Bildung von Organen (Organogenese) von zentraler Bedeutung. Organogenese umfasst Prozesse auf allen Ebenen der Längenskala: von der molekularen Ebene, der Gewebeebene, bis hin zur Ebene des ganzen Organismus. Viele Phänomene der Organogenese beinhalten dabei Veränderungen von Epithelien, bei der sich Schichten von Zellen zu komplexen Strukturen - Organvorläufern - umwandeln. Diese entwickeln sich später zu vollständigen Organen. Die rechtzeitige Entwicklung der charakteristischen Architektur der Organvorläufer ist entscheidend für eine erfolgreiche Organogenese und wird durch die Wahl der epithelialen Umwandlungsprozessen bestimmt, welche die Zellen in Raum und Zeit koordinieren müssen. Für viele dieser Prozesse ist jedoch genau diese zugrundeliegende Zelldynamik unklar. In der hier vorgestellten Arbeit untersuchte ich die Bildung des hemisphärischen retinalen Neuropepithels (RNE). Das RNE ist der Organvorläufer der neuralen Retina, weshalb dessen korrekte Bildung die Voraussetzung für die korrekte Entwicklung der Augen ist. Ich untersuchte die RNE-Morphogenese in sich entwickelnden Zebrafisch-Embryos durch Visualisierung und Untersuchung der zellulären Dynamik der beteiligten Prozesse in vivo. Meine Ergebnisse zeigen, dass das RNE in Zebrafischen durch die kombinierte Umwandlung von zwei verschiedenen Epithelien geformt wird. Zum einen findet eine Verkleinerung des basalen Prozesses der neuroepithelialen Zellen statt, zum anderen die Involution von Randzellen. Die basale Verkleinerung der neuroepithelialen Zellen verbiegt die neuroepitheliale Schicht und führt zur Einstülpung des RNE. Meine Ergebnisse zeigten allerdings, dass Involution von Randzellen noch bedeutsamer für die RNE-Morphogenese ist. Die involution von Randzellen transportiert potenzielle RNE-Zellen in das Neuroepithel und trägt zur RNE-Einstülpung bei. Die Bedeutung meiner Arbeit liegt darin, den bisher unbekannten Mechanismus der Randzell-Involution entdeckt zu haben. Ich zeigte, dass die Randzellen sich aktiv durch kollektive epitheliale Migration bewegen indem sie gerichtete Membranforsätze und dynamische Zell zu Matrix Kontakte etablieren. Wird die Migration der Randzellen inhibiert, so führt dies dazu, dass diese Zellen die eingestülpte RNE Schicht nicht erreichen. Sie landen dann an den falschen Positionen, wo sie die Gewerbearchitektur stören können. Daher koordiniert die Randzellmigration die Position der Zellen und orchestriert die RNE-Morphogenese in Raum und Zeit. Insgesamt zeigt meine Arbeit, wie morphogenetische Prozesse die Organvorläuferarchitektur prägen und eine rechtzeitige Organbildung sicherstellen. Diese Erkenntnisse sind sowohl für das Verständnis der Augenentwicklung, als auch für das der epithelialen Morphogenese und Organogenese in anderen Systemen von großer Bedeutung
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Pedersen, Roberta Vicki Kostiw. "Morphogenesis of planktotrophic veligers of naticidean gastropods." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0006/MQ32675.pdf.
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Kachurina, Nadezda. "Morphogenesis of opaque form «Candida albicans» cells." Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40831.
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ABSTRACT We followed the localization of GFP-tagged myosin I (Myo5), septin (Cdc12) and rhodamin-stained actin during bud and shmoo formation in opaque-phase cells of Candida albicans, and monitored the mating-associated processes of cell fusion, zygote budding, septum formation, daughter cell development and the dynamics of nuclear migration and division. The localization of Myo5p, Cdc12p and actin during budding in opaque and white cells is similar. In pheromone-stimulated cells, these proteins localize in shmoos in patterns consistent with hyphal formation in white-phase cells. MTLa cells generate shmoos 5-7 hours earlier than MTLα cells in mixed populations. In the daughter cell generated after mating, Cdc12p, Myo5p and actin localize as they do under vegetative budding conditions. Intriguingly, isogenicity for the mating type locus is involved in the positioning of the nuclear division; in MTLa cells the nucleus divides within the mother cell up to 70% of the time, rather than across the mother-bud neck.RÉSUMÉ Nous avons déterminé la localisation de l'actine ainsi que de la myosine I (Myo5) et de la septine (Cdc12) modifiées avec la protéine fluorescente verte (GFP) chez Candida albicans en phase opaque (reproductive) et blanche (végétative). Plus particulièrement, nous avons porté notre attention sur les processus associé à la reproduction tel le bourgeonnement et l'expansion cellulaire (shmoo), la conjugaison et la fusion cellulaire, le bourgeonnement et le développement des zygotes (cellules -filles issues de la conjugaison). Nous avons aussi observé la configuration subcellulaire de Myo5p, Cdc12p et de l’actine lors de la migration et de la division nucléaire en phase blanche. Que ce soit en phase opaque ou en phase blanche, la localisation de Myo5p, Cdc12p et de l'actine reste similaire lors du bourgeonnement. Lors d’une stimulation à la phéromone, en phase opaque, ces trois protéines ont le même patron d’organisation cellulaire que lors de la formation d'hyphes en phase blanche. Les cellules de type MTLa produisent des shmoo entre 5 et 7 heures plus tôt que les cellules de type MTLα dans une population mixte. Dans les zygotes, Cdc12p, Myo5p et l'actine ont la même localisation que celle observée dans les cellule-filles issues du bourgeonnement en mode végétatif. Étonnamment, l'isogénicité du locus génétique déterminant le type sexuel de la cellule influence la position du noyau lors de la division; Ainsi, dans 70% des cas, le noyau des cellules de type MTLa se divise à l'intérieur de la cellule-mère plutôt qu'au travers du col entre la cellule-mère et le bourgeon.
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Rymar, Vladimir. "Novel aspects of the mammalian forebrain morphogenesis." Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66743.
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The theme of this dissertation has been to look at characteristics of neurogenesis of the interneurons of mammalian telencephalon, mainly in the striatum and cortex, and compare with neurogenesis patterns of projection neurons. In addition, we have looked at developmental postnatal anterograde thalamostriatal survival mechanisms of striatal neuronal populations and their possible implications in Huntington's disease. Interestingly, most if not all interneurons of the striatum and cortex, at least in case of rodents, are generated far from the germinal zones of these telencephalon divisions. Parvalbumin- and calretinin-positive interneurons, which represent major GABAergic interneuron subpopulations in striatum and cortex originated in germinal zones of the medial and lateral ganglionic eminences, respectively. Neurogenesis timetable and gradients of the striatal calretinin-positive interneurons were determined with respect to the patch/matrix compartmentalization in the second chapter of this thesis using bromo-deoxyuridine-labeling techniques along with the stereological approach for analysis. This data was compared with neurogenetic patterns of other striatal interneuron and projection neuron subtypes previously described in our laboratory and by others. In the third chapter of this thesis we compare neurogenesis patterns of parvalbumin- and calretinin-immunoreactive interneurons with projection neurons in somatosensory cortex as well as with their striatal interneuron counterparts. Interestingly cortical and striatal parvalbumin- and calretinin-positive interneurons were born during the same period of time in keeping with the same place of origin. Laminar fate of cortical GABAergic interneurons is dependent on both birthdate and phenotype. Calretinin-immunopositive interneurons populate cerebral cortex with "outside-in" neurogenessis gradient, heterochronous to neighboring neurons. In contrast, parCette dissertation avait pour but de mettre l'accent sur les caractéristiques de la neurogénèse des interneurones du téléencéphale mammifère, principalement dans le cortex et les corps striés, tout en comparant les motifs de neurogénèse des neurones projectrices. De plus, nous nous sommes attardés aux populations neuronales des corps striés et leurs mécanismes de survie dits antérogrades thalamostriataux survenant dans le développement postnatal et de leurs possibles implications dans la maladie de Huntington. Curieusement, la plupart sinon tous les interneurones provenant du striatum et du cortex, dû moins dans les rongeurs, originent loin des zones germinales de ces divisions téléencéphaliques. Les interneurones exprimants la parvalbumine et la calrétinine, lesquels représentent la majorité des sous-populations d'interneurones GABAergiques dans le striatum et le cortex, proviennent respectivement des zones germinales des éminences ganglioniques latérale et médiale. Dans le second chapitre de cette thèse, une évaluation temporielle de la neurogénèse ainsi que des gradients des interneurones à calrétinine furent determinés avec l'aide de bromo-deoxyuridine ainsi que de la stéréologie tout en considérant la compartimentalization patch/matrice.Ces résultats furent comparés avec des modèles de neurogénèses appartenant à d'autres interneurones des corps striés et des sous-catégories de neurones projectrices qui ont été précedemment décrites par des collègues de notre laboratoire.Dans le troisième chapitre de cette thèse, nous comparons des modèles de neurogénèse d'interneurones contenant de la parvalbumine et de la calrétinine avec des neurones projectrices appartenants aux six couches du cortex somatosensoriel ainsi qu'avec leurs comparses interneurones du cortex. Curieusement, les interneurones corticaux exprimant la parvalbumine et la calrétinine ont$
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Vrljicak, Pavle J. "Role of Smads during renal branching morphogenesis." Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=19397.
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Transforming growth factor-p (TGFp) pathways have been shown to regulate renal branching morphogenesis, one of the key processes determining the final number of nephrons. Although Smads are known to be downstream mediators of these signals, little is known about their role in kidney development. Using RT-PCR and in situ hybridization we investigated the expression of Smads during kidney development. We have found that the receptor regulated Smads (1, 2, 3, 5 and 8) as well as the common partner (Smad4), are expressed in the developing kidney during nephrogenesis. These factors have a specific expression pattern that overlaps with the expression of the signalling molecules BMP-4 and TGFpi. Expression of Smads 1, 3, 4, 5 and 8 is mainly found in undifferentiated mesenchymal cells of the nephrogenic zone as well as ureteric bud tips, but is downregulated in condensing mesenchymal structures. Smad 2 is mostly expressed in the stromal cell compartment. The distinct, yet overlapping, expression of Smads suggests that the specificity of TGFp signals might be determined in part by the combination of Smads expressed in a particular cell type. To better characterize the role of TGFP in kidney development, mouse embryonic kidney explants were treated with soluble TGFP ligands. Addition of BMP-2 and TGFpi inhibited renal branching morphogenesis through their effects on proliferation and survival. Similarly, proliferation and survival appeared to be the critical processes affected by TGFP signalling in the mIMCD-3 model of tubulogenesis. The direct role of Smads was examined by overexpression of a Smad3-GFP fusion protein in mIMCD-3 cells. Apoptosis was most frequently co-localized to Smad-3 transfected cells, which was consistent with the effects observed from the ligand, TGFpi. To test these observations in vivo, we developed a novel method for the manipulation of embryonic kidney explants in culture. GFP-expression vectors were introduced in kidney explants without loss in viability, and the expression of GFP was found to be rapid and sustained for several days in culture. In summary, this study has placed Smads downstream of TGFP signals in the developing kidney, and it opens the door to finding molecules that might be affected by these signals.
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Campbell, K. A. "Cell polarity and tissue morphogenesis in Drosophila." Thesis, University of Cambridge, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.597249.
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The renal system of Drosophila consists of 4 single cell-layered epithelial tubes. Organogenesis of these tubes involves both cellular rearrangement, as they elongate, and the integration of an additional cell population from the surrounding mesoderm. To understand how polarity is established and maintained during these processes, I have characterised the activity of cell polarity genes throughout development. My data suggest that there is a temporal difference in the requirement for one of the key apical proteins, Crumbs, between the epidermis and the tubules. In the epidermis, Crumbs is essential for the formation of the Zonula Adherens junctions (ZAs) so that in Crumbs mutants, the epidermis falls apart at the onset of germ band elongation. The tubules however, form ZAs and localise polarity markers during early stages of development, but by the end of embryogenesis, they lose their tubular organisation and mislocalise both polarity and junctional proteins. The requirement for Crumbs in the tubules occurs at the onset of cellular rearrangement and cell integration. I have used genetics to stall both these morphogenetic movements and find that Crumbs is not longer required to maintain polarity in the tubules. These data suggest that the temporal difference in the requirement for Crumbs between the two tissues is due to the timing of their major morphogenetic movements. This suggests that Crumbs is required to maintain polarity when tissues are morphogenetically active. A key event that could trigger the requirement for Crumbs is the integration of the second mesenchymal cell population, the stellate cells. I have analysed how polarity is established in the stellate cells and how this relates to tubule polarity. I have shown that cell polarity genes become localised in the stellate cells once they have integrated into the tubule epithelium.
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Fox, Helen. "PP1 localisation and function during fungal morphogenesis." Thesis, University of East Anglia, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327586.
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Isherwood, Beverley Jane. "Hepatitis C virus : particle assembly and morphogenesis." Thesis, University of Glasgow, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.410179.
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Graham, Helen K. "Studies of collagen fibrillogenesis during tendon morphogenesis." Thesis, University of Manchester, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.488298.
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Collagen fibrils, which are large, multicomponent protein assemblies, are the principal source of mechanical strength in animal tissues and can grow to millimetre lengths. The mechanism of fibril formation and the influence of non-collagenous components, particularly proteoglycans, in the hierarchical assembly and organisation of collagen fibrils have yet to be fully determined. In this study, quantitative mass mapping by scanning transmission electron microscopy of entire tendon fibrils showed that some fibrils exhibited thinned regions. The axial mass distributions (AMDs) corresponding to the thinned regions were smooth and linear troughs in mass, consistent with the fusion of two fibril tips. In addition, fusion of entire fibrils isolated from tissue has been induced in vitro for the first time. Tissue fibrils fused at their tips in buffered solution to form either fibril rings (having no ends) or elongated fibrils with thinned regions, which lends support to the hypothesis that fusion of fibril tips can occur and that fusion is a mechanism of fibril elongation during the organisation of the extracellular matrix of tendon. Negative staining showed that fusion occurred between the N-tip of a unipolar or bipolar fibril and the C-tip of a unipolar fibril. Fusion between two N-tips was not observed. In one instance fusion was seen between the C-ends of two unipolar fibrils, indicating that fusion between fibril tips must involve the C-end of a unipolar fibril. Cuprolinic blue staining of intact fibrils localised surface-bound proteoglycans predominantly to the shaft region, with markedly depleted levels at the tips. After enzymic removal of proteoglycans, fibrils aggregated laterally in solution. It is likely that a threshold surface concentration of proteoglycans on the fibril shaft prevents lateral aggregation of fibrils whilst being permissive of fibril elongation by tip-to-tip fusion in vivo. Immunoprecipitation experiments with cultured skin fibroblasts using anti-decorin antibodies and anti-collagen antibodies demonstrated the presence of procollagen-decorin complexes in the cell media, suggesting that decorin (a small proteoglycan found in collagen-rich tissues) binds procollagen prior to fibril assembly. This thesis shows that a relationship exists between collagen and proteoglycans throughout the hierarchical assembly of collagen fibrils. An early step in the formation of fibrils appears to be the assembly of procollagen-proteoglycan complexes, which subsequently assemble into well-defined early fibrils. The early fibrils fuse at their tips to form elongated fibrils and the fusion is regulated by proteoglycans located on the fibril shafts.