To see the other types of publications on this topic, follow the link: Embryonic.
Dissertations / Theses on the topic 'Embryonic'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Embryonic.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Montgomery, Sarah Lynn. "Impedance measurement system for embryonic stem cell and embryoid body cultures." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/24661.
Full text
2
Salanga, Matthew Charles. "EMBRYONIC VASCULAR DEVELOPMENT." Diss., The University of Arizona, 2011. http://hdl.handle.net/10150/203435.
Full textAbstract:
The formation of the embryonic vasculature is essential for life. The components driving this process are well conserved across vertebrate species. At the core of vascular development is the specification of endothelial precursor cells from nascent mesoderm. Transcription factors of the ETS family are important regulators of endothelial specification. In this document we characterize the role of the ETS transcription factors, ETV2, during embryonic vascular development.Expression analysis shows that Etv2 is highly expressed in hematopoietic and endothelial precursor cells in the Xenopus embryo. In gain-of-function experiments, ETV2 is sufficient to activate ectopic expression of vascular endothelial markers. In addition, ETV2 activated expression of hematopoietic genes representing the myeloid but not the erythroid lineage. Loss-of-function studies indicate that ETV2 is required for expression of all endothelial markers examined. However, knockdown of ETV2 has no detectable effects on expression of either myeloid or erythroid markers. This contrasts with studies in mouse and zebrafish where ETV2 is required for development of the myeloid lineage. Our studies confirm an essential role for ETV2 in endothelial development, but also reveal important differences in hematopoietic development between organisms.Although ETV2 is a pivotal molecule in development it remains unidentified in the chicken genome. We hypothesize that chicken Etv2 is expressed in the early Gallus embryo, and is necessary for endothelial specification consistent with its role in other species. To test this hypothesis we attempted to amplify Etv2 transcripts from Gallus embryos using degenerate PCR. Disappointingly this strategy did not reveal a putative Etv2 candidate. However, some important findings were uncovered, including the cloning of a previously uncharacterized Gallus ETS protein, SPDEF. Additionally the identification of an annotation error mis-identifying Ets gene "Erf" as "Etv3" (also an Ets gene) provided details on gene arrangement previously unknown. The workflow described could be used in future studies for the identification of other members of gene families that exhibit gaps, keeping in mind the goal of the study and the limitations of each technology.
3
Bailleul, Richard. "Embryonic patterning of the avian skin : mathematical modelling of embryonic dynamics." Electronic Thesis or Diss., Sorbonne université, 2019. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2019SORUS022.pdf.
Full textAbstract:
Depuis la publication par Alan Turing de son article ‘The Chemical Basis of Morphogenesis” en 1952, une révolution moléculaire a eu lieu en biologie et les mathématiciens ont fourni un nombre croissant de cadres théoriques afin de modéliser des motifs observés dans la nature. Cette thèse a pour objectif d’unifier les récentes découvertes dans ces deux domaines en proposant un cadre théorique et des schémas de développement pour l’émergence des motifs cutanés aviaires par l’étude de la dynamique de formation du plumage dorsal. J'ai caractérisé l'apparition des primordiums de plumes dans le dos de plusieurs espèces d'oiseaux : poulets, cailles, faisans, diamants mandarins, émeus et manchots. Chez les quatre premières espèces, la peau est structurée de manière reproductible : de minces domaines de compétence longitudinaux, marqués par la bêta-caténine, déclenchent une vague de rangées formant des plumes qui se propagent latéralement. Le processus est très différent chez les émeus et manchots: les plumes s'individualisent dans des domaines compétents et apparaissent rapidement sur toute la peau, de manière régulière ou irrégulière. J'ai ensuite reproduit les attributs de cette dynamique avec un modèle unifié de réaction-diffusion-chimiotactisme, avec un terme de prolifération logistique. En ajustant les conditions initiales, ce modèle récapitule les différentes dynamiques de patterning observées, et prédit que la prolifération cellulaire contrôle la synchronisation du processus de configuration. Ce modèle étude ouvre des perspectives concernant l'évolution des motifs cutanés et discute les origines de propriétés de ces motifs tels que leur régularité et leur directionalité<br>Since Alan Turing’s milestone paper ‘The Chemical Basis of Morphogenesis” in 1952, a molecular revolution has taken place in biology and mathematicians have provided an increasing number of theoretical models that are able to generate many of the patterns observed in nature. This thesis aimed at unifying the extensive findings in both fields to propose theoretical frameworks and developmental schemes for the emergence of avian skin patterns, with a particular focus on dorsal plumage dynamics. I characterised the appearance of feather primordia in the dorsum of several bird species, namely chickens, quails, pheasants, zebra finches, emus and penguins. In the first four species, the patterning of the dorsal skin occurs in a highly reproducible manner: thin longitudinal domains of competence, marked by beta-catenin, trigger a wave of feather-forming rows that propagate laterally in a timely fashion, eventually forming feather tracts. In flightless emus and penguins, the process is much different: feathers first individualise within large competent domains, and later appear throughout the whole skin, in a quick and regular or irregular fashion. I then reproduced shared and varying attributes of these dynamics with a unified reaction-diffusion-chemotaxis model with logistic cell proliferation, which I used in a predictive way. It recapitulates all varying attributes of the patterning processes by tuning initial conditions, and predicts that cell proliferation controls the timing of the patterning process. Our framework opens up evolutionary perspectives, and the origins of pattern attributes such as regularity and directionality are discussed
4
Nortjé, Nico. "The moral status of embryonic stem cell research in the South African context /." Link to the online version, 2007. http://hdl.handle.net/10019.1/1372.
Full text
5
Harrison, Sarah Ellys. "Utilising embryonic and extra-embryonic stem cells to model early mammalian embryogenesis in vitro." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/275424.
Full textAbstract:
Successful mammalian development to term requires that embryonic and extra-embryonic tissues communicate and grow in coordination, to form the body. After implanting into the uterus, the mouse embryo is comprised of three cell lineages: first, the embryonic epiblast (EPI) that forms the embryo proper, second, the extra-embryonic ectoderm (ExE) which contributes to the foetal portion of the placenta, and third, the visceral endoderm (VE) that contributes to the yolk sac. These three tissues form a characteristic ‘egg-cylinder’ structure, which allows signals to be exchanged between them and sets the stage for body axis establishment and subsequent tissue patterning. The mechanisms underlying this process are difficult to study in vivo because a different genetically manipulated mouse line must be generated to investigate each factor involved. This difficulty has prompted efforts to model mammalian embryogenesis in vitro, using cell lines, which are more amenable to genetic manipulation. The pluripotent state of the EPI can be captured in vitro as mammalian embryonic stem cells (ESCs). Although mouse ESCs have been shown to contribute to all adult tissues in chimeric embryos, they cannot undertake embryogenesis when allowed to differentiate in culture. Previous studies have shown that ESCs formed into three-dimensional (3D) aggregates, called embryoid bodies, can become patterned and express genes associated with early tissue differentiation. However, embryoid bodies cannot recapitulate embryonic architecture and therefore may not accurately reflect what happens in the embryo. In this study, a new technique was developed to model early mouse development which is more faithful to the embryo. ESCs were co-cultured with stem cells derived from the ExE, termed trophoblast stem cells (TSCs), embedded within extracellular matrix (ECM). These culture conditions lead to the self-assembly of embryo-like structures with similar architecture to the mouse egg cylinder. They were comprised of an embryonic compartment derived from ESCs abutting an extra-embryonic compartment derived from TSCs, and hence were named ‘ETS-embryos’. These structures developed a continuous cavity at their centre, which formed via a similar sequence of events to those that lead to pro-amniotic cavity formation in the mouse embryo, and required active Nodal/Activin signalling. After cavitation, ‘ETS-embryos’ developed regionalised mesodermal tissue and primordial germ cell-like cells originating at the boundary between embryonic and extra-embryonic compartments. Inhibitor studies revealed that this occurred in response to endogenous Wnt and BMP signalling, pathways which also govern these tissue specification events in the early mouse embryo. To demonstrate that ‘ETS-embryos’ were comparable to mouse embryos at the global transcriptional level, RNA-sequencing was then performed on different tissue regions of ‘ETS-embryos’ and the resulting transcriptomes were compared to datasets from mouse embryos. These data showed that ‘ETS-embryos’ were highly similar to mouse embryos at post-implantation stages in their overall gene expression patterns. Taken together, these results indicate that ‘ETS-embryos’ are an accurate in vitro model of mammalian embryogenesis, which can be used to complement studies undertaken in vivo to investigate early development.
6
Fijnvandraat, Arnoldus Cornelis. "Embryonic stem cell-derived cardiomyocytes." [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2003. http://dare.uva.nl/document/68354.
Full text
7
Brochu, Richard. "Pacemaking in embryonic chick heart." Thesis, McGill University, 1990. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=59533.
Full textAbstract:
Experiments were conducted to determine the currents involved in the pacemaker activity of aggregates and single cells from the embryonic chick heart. Two microelectrode voltage clamp studies of embryonic chick ventricular heart cell aggregates revealed two time-dependent current components in the pacemaker range of potentials ($-$60 to $-$120 mV). Barium (Ba, 5 mM) blocked the more negatively activated time-dependent component unmasking a component which remained inwardly directed for hyperpolarizing steps beyond the potassium equilibrium potential (E$ sb{ rm K}$). This component, which was blocked by cesium (Cs, 2 mM), is consistent with an inward current which activates upon hyperpolarization (the I, model) as proposed by DiFrancesco (1981a,b), for Purkinje fibers.<br>In order to minimize the problems associated with the accumulation/depletion of ions in the extracellular space during voltage clamp experiments, studies were carried out on single ventricular cells or small clusters of ventricular cells.
8
McCluskey, Jane T. "Mechanisms of embryonic wound healing." Thesis, University of Oxford, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.318851.
Full text
9
Tata, M. A. J. "Vascular regulation of embryonic neurogenesis." Thesis, University College London (University of London), 2016. http://discovery.ucl.ac.uk/1531030/.
Full textAbstract:
Neural progenitor cells (NPCs) in the embryonic nervous system generate a large number and variety of neurons in a process known as neurogenesis. NPCs reside in a regulatory ‘niche’ that provides an extensive array of diverse signals, and loss of any one of these signals can deplete the pool of NPCs and therefore impair neural development. These niche signals are most commonly studied in the forebrain, where a complex array of cell divisions yields a set of diverse NPCs. In contrast, little is known on the role of niche signals in regulating the behaviour of NPCs in the hindbrain, the evolutionary oldest part of the brain that is essential for many vital bodily functions. In the adult brain, blood vessels and the vascular growth factor VEGF-A regulate the behaviour of neural stem cells (NSC). However, it is not known whether either also regulates hindbrain neurogenesis. For my PhD research, I have used the mouse embryo hindbrain as a model to examine the role of blood vessels and VEGF-A receptors in developmental neurogenesis. My studies have revealed that NPCs divide most actively during a period of extensive blood vessel growth in the hindbrain, that hindbrain NPCs reside within a well-vascularised germinal zone (GZ) and that they make physical contact with the GZ vasculature. To establish whether VEGF-A receptors or hindbrain blood vessels regulate the behaviour of hindbrain NPCs, I have analysed mouse embryos lacking the neurovascular cell surface receptor NRP1 in either the neural or endothelial lineages. I found that NRP1 regulates the proliferative behaviour of hindbrain NPCs through its role in promoting GZ vascularisation, but not as a receptor for VEGF-A in NPCs. I have further shown that GZ vasculature sustains the size of the NPC pool through the period of hindbrain neurogenesis and may do so by limiting the expression of pro-differentiation signals to set the pace of neurogenesis. Even though blood vessels are best know for their role in tissue oxygenation, my results also show that NRP1-dependent GZ vasculature does not regulate hindbrain NPC behaviour through its role in oxygenating the neuroepithelium. In conclusion, my results identify an essential role for blood vessels in regulating NPC behaviour in the embryonic hindbrain and have increased our understanding of the regulatory niche that orchestrates developmental neurogenesis.
10
Losa, Llabata Marta. "Gene regulation in embryonic development." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/gene-regulation-in-embryonic-development(8a9efb79-1ca9-409e-89b9-9d66213e593f).html.
Full textAbstract:
Branchial arches (BAs) are a series of transient structures that develop on the ventro-lateral surface of the head in vertebrate embryos. BAs initially appear as a series of similar segments; as development proceeds each BA will contribute to different structures. Here, it was investigated the transcriptional mechanisms that instruct the different fates of the BAs in development. Initially, each BA contains a blood vessel, known as aortic arch (AA) artery, that connects the dorsal aorta with the heart. Remodelling of the AAs is crucial to form the adult heart circulation. This process leads to regression of the anterior AAs, running though the first and second BAs (BA1 and BA2), and persistence of the AAs contained in more posterior BAs (PBA). To identify the mechanisms that control remodelling of the AAs, we compared the transcriptomes and epigenomic landscapes of different BAs. Using RNA-seq and H3K27Ac ChIP-seq, we uncovered the activation of a vascular smooth muscle cell (VSMC) differentiation transcriptional program exclusively in the PBAs (and not in BA1/BA2). In support of this finding, we show that VSMC differentiation occurs specifically in the PBAs, but not BA1-2 in mouse embryonic development. Despite the absence of VSMC differentiation in developing BA1-2, cells harvested from these tissues reveal a spontaneous tendency to differentiate towards VSMC fate when grown in vitro, and activate several VSMC-specific genes (Myocd, Acta2, Tagln, Jag1). Together, our results suggest that forming VSMCs is a key process for the persistence of AAs. We also showed that cells derived from all BAs have the potential to differentiate to VSMCs in vitro. However, only cells in the PBAs differentiate to VSMCs in vivo, resulting in the maintenance of posterior AAs. In this study, we also uncovered a novel transcriptional principle that specifies the fate of BA2. Using ChIP-seq, we found that binding of Meis transcription factors establish a ground pattern in the BAs. Hoxa2, which specifies BA2 identity, selects a subset of Meis-bound sites. Meis binding is strongly increased at these sites, which coincide with active enhancers, linked to genes highly expressed in the BA2 and regulated by Hoxa2. Thus, Hoxa2 modifies a ground state binding of Meis to instruct segment-specific transcriptional programs.
11
Sargent, Carolyn Yeago. "Effects of hydrodynamic culture on embryonic stem cell differentiation: cardiogenic modulation." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/34710.
Full textAbstract:
Stem and progenitor cells are an attractive cell source for the treatment of degenerative diseases due to their potential to differentiate into multiple cell types and provide large cell yields. Thus far, however, clinical applications have been limited due to inefficient differentiation into desired cell types with sufficient yields for adequate tissue repair and regeneration. The ability to spontaneously aggregate in suspension makes embryonic stem cells (ESCs) amenable to large-scale culture techniques for the production of large yields of differentiating cell spheroids (termed embryoid bodies or EBs); however, the introduction of hydrodynamic conditions may alter differentiation profiles within EBs and should be methodically examined. The work presented here employs a novel, laboratory-scale hydrodynamic culture model to systematically interrogate the effects of ESC culture hydrodynamics on cardiomyocyte differentiation through the modulation of a developmentally-relevant signaling pathway. The fluidic environment was defined using computational fluid dynamic modeling, and the effects of hydrodynamic conditions on EB formation, morphology and structure were assessed. Additionally, EB differentiation was examined through gene and protein expression, and indicated that hydrodynamic conditions modulate differentiation patterns, particularly cardiogenic lineage development. This work illustrates that mixing conditions can modulate common signaling pathways active in ESC differentiation and suggests that differentiation may be regulated via bioprocessing parameters and bioreactor design.
12
Schacker, Maria Anna. "Defining the transcriptional and epigenetic signature of mouse embryonic stem cells with compromised developmental potency." Thesis, University of Cambridge, 2019. https://www.repository.cam.ac.uk/handle/1810/287725.
Full textAbstract:
Mouse embryonic stem (ES) cells have played a crucial role in studying developmental processes and gene function in vivo. They are extremely useful in the generation of transgenic animals as they can be genetically manipulated and subsequently microinjected into blastocyst stage embryos, where they combine with the inner cell mass and contribute to the developing embryo. Some of the resulting pups are chimaeric, consisting of a mixture of cells derived from the host blastocyst and the injected ES cells. We have identified several ES cell clones arising from gene targeting experiments with an impaired capacity to generate viable chimaeras. When injected into blastocysts, these clones cause embryonic death during mid to late gestation, suggesting that the cells are able to contribute to the embryo but interfere with normal embryonic development. The aim of this work was to identify the underlying changes in the transcriptome, epigenome or cell surface markers that have occurred in these compromised ES cells and to further define the developmental phenotype of the chimaeric embryos. Different stages during development were analysed and whereas there was little difference in embryonic death at gestational day e13.5, there was a significant decrease in embryos surviving to gestational day e17.5. Additionally, severe haemorrhaging was observed in all the dead embryos and small foci of haemorrhaging could also be seen in a number of embryos that were still alive. This was also observed at e13.5, albeit to a less severe extent. Using RNA sequencing to discover differences in the transcriptome between control ES cells and the compromised ES cells, five genes were identified that were downregulated in the compromised cells. Four of these, Gtl2, Rtl1as, Rian and Mirg are all located in the imprinted Dlk1-Dio3 region on chromosome 12 and are normally expressed from the maternal genome. This pattern was also validated in tissues from e17.5 chimaeric embryos. The expression of this locus is to a large extent regulated by a differentially methylated region located approximately 13kb upstream of the Gtl2 promoter, the IG-DMR. Whereas this is usually only methylated on the paternal copy, in the compromised ES cells both the paternal and the maternal copy were fully methylated, likely causing the silencing of Gtl2, Rtl1as, Rian and Mirg. Using the DNA methyltransferase inhibitor 5-azacytidine, expression of Gtl2 could be rescued. Injection of those 5-azacytidine treated cells into blastocysts did partially rescue the embryonic lethal phenotype. Additionally, cell surface markers were analysed in a phenotypic screen using phage display. NGS analysis of the phage outputs indicates that there may be additional differences in cell surface markers between the control and compromised ES cell clones, but their specific details remain to be identified. Overall, we have identified the maternally expressed genes of the Dlk1-Dio3 region as markers that can distinguish between ES cells with normal or compromised developmental potency and propose to include these genes in the pre-blastocyst injection screening routine for experiments involving the production of chimaeras or genetically modified mouse strains.
13
Van, Vranken Benjamin Eugene. "The influence of embryonic lung mesenchyme on the differentiation of embryonic stem cells in co-culture." Thesis, Imperial College London, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.416628.
Full text
14
Anderson, Kathryn Gayle Victoria. "Conserved mode of endoderm induction acts to promote context dependent embryonic and extra-embryonic lineage specification." Thesis, University of Edinburgh, 2015. http://hdl.handle.net/1842/16473.
Full textAbstract:
In mammalian development, endoderm formation occurs in two phases and the fate of these populations is different. In the blastocyst, inner cell mass (ICM) cells generate the primitive endoderm (PrE), which will give rise to the extra-embryonic parietal (PE) and visceral endoderm (VE). Hematopoietically expressed homeobox (Hhex) protein is initially expressed throughout the PrE and subsequently becomes restricted to the anterior visceral endoderm (AVE), one of two important early embryonic signalling centres in the mouse. During gastrulation a second wave of endoderm differentiation occurs, the definitive endoderm (DE), generating the foregut. Immediately following the induction of DE, regional identity is initially established in the anterior region with the expression of Hhex. One of the earliest specification events in this lineage is the specification of anterior fate by Hhex, this time in a second signalling centre, the anterior definitive endoderm (ADE). The ADE is both important for embryonic patterning, and as the precursor population for differentiating to the foregut and its derivatives the thyroid, liver and pancreas. The literature surrounding these early embryonic patterning events is covered in depth in chapter 1. Embryonic stem cells (ESCs) are normal cell lines derived from the mammalian blastocyst at the time that it is making PrE. A number of laboratories have generated protocols to make endoderm from ESCs and in my thesis I define approaches to distinguish between PrE and DE. I generated a new ESC reporter line utilising a gene normally expressed in both the PrE and later in hepatic endoderm; this reporter contains a GFP in the first exon of the Hnf4α locus. This was combined with a second fluorescent reporter containing DSRed in the Hhex locus. This cell line is described and characterised in chapter 3. As Hnf4α is initially expressed in PrE prior to Hhex, but in the DE following Hhex, I was able to use the temporal expression of this reporter to distinguish the induction of PrE from DE. As Activin and Wnt are known to induce endoderm from ESCs, I was then able to ask what sort of endoderm the combination of these two signals induced. In chapter 4 I found that normal ESCs would readily differentiate to iPrE in the presence of Activin and Wnt3a. While this has not been described previously, my analysis suggests that ESC protocols applying these cytokines directly to ESCs have produced PrE. Given that ESCs are derived from the blastocyst, the generation of iPrE from Wnt3a/Activin treatment fits with developmental paradigms. However, Act/Wnt3a is used routinely on Human ESCs (hESCs) and so I attempted to reconcile these observations. HESCs, while derived from the blastocyst, appear to progress developmentally in vitro, to a stage closer to the epiblast, immediately prior to gastrulation. I therefore assessed the effect of Activin and Wnt3a on mouse stem cell lines derived from the epiblast (Epiblast Stem Cells, EpiSCs), that are grown under similar conditions to hESCs. When Wnt3a/Act is applied to these cells I found that they made DE rather than PrE, which I describe in chapter 4. Taken together my observations suggest that Act/Wnt3a are general endoderm inducers that induce context specific differentiation in vitro. The cell type derived in response to this treatment depends on the developmental stage of the starting stem cell culture. During the course of this work, I also observed that PrE was growing under Activin/Wnt3a treatment. As a number of cell culture systems have been established that reflect PE, but not truly bipotent PrE, I investigated the conditions under which PrE can be expanded. In chapter 5 I characterize a new PrE culture system, in which bipotent extra-embryonic endoderm can be expanded indefinitely in culture. I also explore a bit more precisely the nature of the starting cells that initially become exposed to Activin/Wnt3a treatment. Previous work has extensively characterized the existence of a primed population of PrE in ESC culture and in chapter 6 I explore the existence of a primed DE population in EpiSC culture. Taken together, my thesis is the first demonstration that Activin/Wnt3a can induce different endoderm populations in different embryonic stem cell populations. It underlies the notion that the evolutionary origin of both cell types is the same and that the pathways evolved for extra-embryonic development in mammals just exploit the ancient modes of germ layer specification that evolved with gastrulation.
15
Wilde, Mark H. "The relationship between embryonic diversity and embryonic loss during the first twelve days of porcine gestation /." The Ohio State University, 1989. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487676261010897.
Full text
16
Vaahtokari, Anne. "Molecular mechanisms in embryonic tooth development." Helsinki : Dept. of Dentistry, Division of Pedodontics and Orthodontics, Institute of Biotechnology and Dept. of Biosciences, Division of Biochemistry, University of Helsinki, 1996. http://catalog.hathitrust.org/api/volumes/oclc/35253532.html.
Full text
17
Jurczak, Daniel. "Stemness in human embryonic stem cells." Thesis, University of Skövde, School of Life Sciences, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-3509.
Full textAbstract:
<p>Stem cells are cells that have a unique ability to divide for an indefinite period. Additionally, they can give rise to a plethora of specialized cell types. The advent of high-throughput technologies made it possible to investigate gene expression on a large scale. This enabled scientists to perform comprehensive gene profiling studies of stem cells. Several authors have suggested that there might be a common set of genes that control the stemness of stem cells. In this study, we suggest that ”stemness” genes that are related to ”stemness” characteristics show a statistically significant down-regulation between undifferentiated and differentiated cells. For this we have analyzed microarray data from five different cell lines and compared their global expression profiles. Common down-regulated transcripts among those data sets were de- rived by using a well-established gene expression analysis procedure called Significance Analysis of Microarrays. Since all three data sets were provided by Cellartis AB, the derived list of common transcripts was subsequently compared with an external study. Moreover, we also performed a comparison with down-regulated genes derived from mouse embryonic stem cells. This was done to determine if there is a common set of stemness genes even across distinct species. Re- sults were further evaluated using a comprehensive data-set from a study by Skottman et al. (2005). All results where compared uti- lizing using a range of false discovery rate threshold values and the results were subsequently used for gene ontology term enrichment. GO terms where utilized to functionally annotate and classify those embryonic stem cell transcripts, that were found to be common in all data-sets and identify over-represented biological processes related to those genes.</p>
18
Shivji, Nadia. "GnRH neuron migration during embryonic development." Thesis, University of Cambridge, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.611556.
Full text
19
Jörg, David Josef. "Genetic Oscillations and Vertebrate Embryonic Development." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-159034.
Full textAbstract:
Recurrent processes are a general feature of living systems, from the cell cycle to circadian day-night rhythms to hibernation and flowering cycles. During development and life, numerous recurrent processes are controlled by genetic oscillators, a specific class of genetic regulatory networks that generates oscillations in the level of gene products. A vital mechanism controlled by genetic oscillators is the rhythmic and sequential segmentation of the elongating body axis of vertebrate embryos. During this process, a large collection of coupled genetic oscillators gives rise to spatio-temporal wave patterns of oscillating gene expression at tissue level, forming a dynamic prepattern for the precursors of the vertebrae. While such systems of genetic oscillators have been studied extensively over the past years, many fundamental questions about their collective behavior remain unanswered. In this thesis, we study the behavior and the properties of genetic oscillators from the single oscillator scale to the complex pattern forming system involved in vertebrate segmentation.
Genetic oscillators are subject to fluctuations because of the stochastic nature of gene expression. To study the effects of noisy biochemical coupling on genetic oscillators, we propose a theory in which both the internal dynamics of the oscillators as well as the coupling process are inherently stochastic. We find that stochastic coupling of oscillators profoundly affects their precision and synchronization properties, key features for their viability as biological pacemakers. Moreover, stochasticity introduces phenomena not known from deterministic systems, such as stochastic switching between different modes of synchrony.
During vertebrate segmentation, genetic oscillators play a key role in establishing a segmental prepattern on tissue scale. We study the spatio-temporal patterns of oscillating gene expression using a continuum theory of coupled phase oscillators. We investigate the effects of different biologically relevant factors such as delayed coupling due to complex signaling processes, local tissue growth, and tissue shortening on pattern formation and segmentation. We find that the decreasing tissue length induces a Doppler effect that contributes to the rate of segment formation in a hitherto unanticipated way. Comparison of our theoretical findings with experimental data reveals the occurrence of such a Doppler effect in vivo. To this end, we develop quantification methods for the spatio-temporal patterns of gene expression in developing zebrafish embryos.
On a cellular level, tissues have a discrete structure. To study the interplay of cellular processes like cell division and random cell movement with pattern formation, we go beyond the coarse-grained continuum theories and develop a three-dimensional cell-based model of vertebrate segmentation, in which the dynamics of the segmenting tissue emerges from the collective behavior of individual cells. We show that this model is able to describe tissue formation and segmentation in a self-organized way. It provides the first step of theoretically describing pattern formation and tissue dynamics during vertebrate segmentation in a unified framework involving a three-dimensional tissue with cells as distinct mechanical entities.
Finally, we study the synchronization dynamics of generic oscillator systems whose coupling is subject to phase shifts and time delays. Such phase shifts and time delays are induced by complex signaling processes as found, e.g., between genetic oscillators. We show how phase shifts and coupling delays can alter the synchronization dynamics while leaving the collective frequency of the synchronized oscillators invariant. We find that in globally coupled systems, fastest synchronization occurs for non-vanishing coupling delays while in spatially extended systems, fastest synchronization can occur on length scales larger than the coupling range, giving rise to novel synchronization scenarios. Beyond their potential relevance for biological systems, these results have implications for general oscillator systems, e.g., in physics and engineering.
In summary, we use discrete and continuous theories of genetic oscillators to study their dynamic behavior, comparing our theoretical results to experimental data where available. We cover a wide range of different topics, contributing to the general understanding of genetic oscillators and synchronization and revealing a hitherto unknown mechanism regulating the timing of embryonic pattern formation.
20
Page, Nigel Mark. "Gene insertion into avian embryonic cells." Thesis, University of Reading, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333871.
Full text
21
Abdullah, A. R. "Mathematical modelling of embryonic tissue development." Thesis, University of Liverpool, 2018. http://livrepository.liverpool.ac.uk/3028456/.
Full text
22
Mazzocchi-Jones, David. "Electrophysiological characterisation of embryonic striatal grafts." Thesis, Cardiff University, 2006. http://orca.cf.ac.uk/55058/.
Full textAbstract:
The striatum, a region of the rodent forebrain, is part of an interconnected set of structures known as the basal ganglia and has long been implicated in the initiation and control of motor behaviour (Graybiel et al., 1994 Groenewegen, 2003). However, emerging evidence suggests that the basal ganglia also plays a role in a variety of other cognitive functions such as motor learning, habit formation, and goal rewarded behaviour (Graybiel, 2000 Oberg and Divac, 1975).
23
Cheung, Kwok Kuen. "Purinergic signaling during rat embryonic development." Thesis, University College London (University of London), 2004. http://discovery.ucl.ac.uk/1446895/.
Full textAbstract:
Adenosine 5'-triphosphate (ATP) has been shown to be an important extracellular signaling molecule that mediates various physiological activities via the P2 (P2X and P2Y) receptors. However, information on the expression patterns of the P2 receptors during mammalian embryogenesis is limited. We therefore examined the expression patterns of different P2 receptor subtypes in rat embryos. In the hindbrain neural tube, the P2X3 receptor was transiently expressed at embryonic day E11 in the cranial motor neurons and the outgrowing axons. ATP significantly inhibited neurite outgrowth from neural tube explants. P2X3 receptors were also prominently expressed in sensory ganglia at this early stage and were coexpressed with P2X2 receptors in El6.5 embryos. Other P2X receptor subtypes were observed in different brain regions such as subventricular zones, the site of postnatal neurogenesis. In addition, the P2Y receptor expression was detected in the somites and subsequently in the developing skeletal muscle but was downregulated as development proceeded. While the P2Y1 receptor was no longer expressed in the adult skeletal muscle, the expression of P2Y2 receptor was present, although restricted in the satellite cells and the P2Y4 receptor showed reduced expression in adult skeletal muscle. Likewise, the expression of the P2Y receptors was initially expressed throughout the myocardium (El2) but was gradually restricted to the trabeculated myocardium (El4-18). Studies on Ca2+ influx showed that particular P2 receptor subtypes of P2X2, P2X4, P2Y1, P2Y2, P2Y4 and P2Y6 receptors responded to nucleotides in E14 cardiomyocytes. P2X7 receptor expression was detected in developing pancreatic islet cells and later coexpressed with glucagon in ?-cells. In addition, transient expression of the P2X7 receptor in insulin-expressing cells was observed in the embryonic, but not in adult, islet cells. Together, the results indicated that widespread and dynamic expression of P2 receptors was found in the three-germ layer-derived embryonic tissues, particularly in some transient embryonic structures during development, which suggested they may be important in embryonic organogenesis.
24
Ma, Pei. "OPTICAL IMAGING OF EMBRYONIC CARDIAC CONDUCTION." Case Western Reserve University School of Graduate Studies / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=case1464714110.
Full text
25
Cunningham, Michael Lawrence. "The embryonic macrophage : scavenger or sculptor? /." Thesis, Connect to this title online; UW restricted, 1996. http://hdl.handle.net/1773/5687.
Full text
26
Meadows, Stryder. "Transcriptional Regulation In Early Embryonic Development." Diss., The University of Arizona, 2008. http://hdl.handle.net/10150/194034.
Full textAbstract:
Transcription factors are a class of proteins that function to regulate the expression of genes. During early development, their role is to provide the precise order of activation or suppression of genes that are required for the formation of an embryo. A major goal of a developing embryo is to establish a complete body plan that includes the development of all of the organ systems. Thus it is paramount that the correct genes are switched on or off to insure that all organ systems form.Our studies investigate the role of several transcription factors involved in coordinating the expression of genes that are essential for the development of skeletal muscle and blood vessels.In the formation of skeletal muscle, a class of transcription factors called the myogenic regulatory factors (MRFs) is known to promote the induction of the structural genes that comprise the skeletal muscle. In fact, the MRF family member, MyoD, has been termed the "master regulator" of skeletal muscle gene expression. However, a recently discovered transcription factor, MASTR, has been suggested to play a role in skeletal muscle development. Our studies of MASTR are the first to demonstrate that, in vivo, MASTR is necessary and sufficient to activate genes involved in the formation of skeletal muscle. Furthermore, MASTR cooperates with MRFs to induce skeletal muscle genes and therefore places MASTR among a group of transcription factors, such as the MRFs, that are essential regulators of skeletal muscle development.In vascular development, the Flk-1 gene is critical to the formation of blood vessels. Mice lacking Flk-1 do not produce angioblasts, the precursor cells that give rise to the endothelial cells that make up blood vessels. In our efforts to understand the regulation of this important vascular gene, we have discovered a new function of the Kruppel-like transcription factor 2 (KLF2) to activate Flk-1 expression. Moreover, we have identified a new Ets transcription factor (Etsrp) capable of inducing Flk-1 expression alone and in cooperation with KLF2. These findings uncover a novel mechanism by which KLF2 and Etsrp act to promote the expression of Flk-1 during embryonic vascular development.
27
Jung, Marc [Verfasser]. "OCT4 regulated transcription networks in human embryonic stem cells and human embryonal carcinoma cells / Marc Jung." Berlin : Freie Universität Berlin, 2009. http://d-nb.info/1023957345/34.
Full text
28
Basuki, Edi 1957. "Ecdysteroid levels and implications for embryonic and post-embryonic development of the blowfly Lucilia cuprina (Wied.) (Diptera:Calliphoridae)." Monash University, Dept. of Biological Sciences, 2000. http://arrow.monash.edu.au/hdl/1959.1/8436.
Full text
29
Lau, Daniel Christian Crews Stephen T. "Embryonic regulation and post-embryonic function of the single-minded gene in the Drosophila central nervous system." Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2009. http://dc.lib.unc.edu/u?/etd,2529.
Full textAbstract:
Thesis (Ph. D.)--University of North Carolina at Chapel Hill, 2009.<br>Title from electronic title page (viewed Oct. 5, 2009). "... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Biology." Discipline: Biology; Department/School: Biology.
30
Ladd, Sabine Margaret. "Effects of Diethylstilbestrol on Murine Early Embryonic Stem Cell Differentiation Using an Embryoid Body Culture System." Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/31999.
Full textAbstract:
Objectives: The effects of estrogens on immune system formation and function are well documented. Diethylstilbestrol (DES), a synthetic estrogen, has been linked to neoplasia and immune cell dysfunction in humans and animals exposed in-utero. In-vitro effects of DES exposure of murine embryonic stem (ES) cells on the early embryonic immune system development and the expression of cellular surface markers associated with common hemangioblastic and hematopoietic precursors of the endothelial, lymphoid & myeloid lineages were investigated.
Hypothesis: Early ES cell expression of CD45 a marker common to lymphoid lineage hematopoietic stem cells and differentiation of lymphoid lineage precursors are affected by in-vitro exposure to DES.
Methods: Murine ES cells were cultured using a variety of techniques: an OP9 co-culture system, and formation of embryoid bodies (EBs) in a liquid medium and hanging drop system. The OP9 co-culture system did not appear to give rise to well differentiated lymphoid lineage cells during 12 days of differentiation. The hanging drop EB culture system, previously shown to promote differentiation of endothelial and lymphoid precursor cells, was chosen for further studies of ES cell differentiation. ES cells were harvested at five time points: undifferentiated (day 0), and differentiated (days 3, 8, 12 and 16). Differentiating ES cells were treated with DES beginning on day 3. The synthetic estrogen, DES, was chosen as a treatment because of its similar potency to 17β estradiol and documented association with neoplasia in women exposed in-utero. Surface marker expression, measured by real-time RT-PCR amplification, was recorded using fluorogenic TaqMan(R) probes designed specifically for the surface proteins of interest: oct4, c-Kit, Flk1, ERα, ERβ, CD45, Flt1, & VE-cadherin.
Analysis & Results: Changes in surface marker gene expression between day 0 and day 16 of differentiation were analyzed using the RT-PCR threshold counts (CT) and the comparative threshhold cycle method. The expression of each target mRNA was normalized internally to a housekeeping gene (18s rRNA) and calculated relative to day 0. ANOVA (Type 3 fixed-effects analysis, SAS) was performed using the unexponentiated ΠΠCT values. The effects of DES, time, and the interaction between DES and time were evaluated for days 8, 12 and 16. Additionally, the effects of DES on the expression of each marker were evaluated for day 16. Expression of estrogen receptor receptor α
& β (ERα & β) in the EBs was established, and did not appear to be affected at any time by treatment with DES. ERα was expressed in significant levels on day 16, while ERβ was expressed in low levels throughout the period of differentiation. The expression of the cell surface marker, c-Kit was significantly (P<0.0001) altered by the presence of DES between the three time points sampled. The expression of the VEGF receptor, Flt1, and the adhesion molecule, VE-cadherin, markers of endothelial cells, were also significantly (P<0.026) altered by treatment with DES on day 16 of differentiation. Treatment with DES appeared to have no effect on the expression of CD45, a marker common to lymphoid precursor cells.
Conclusions: These results indicate the presence of estrogen receptors in differentiating ES cells as early as day three in-vitro (ERβ) until day 16 (ERα). DES alters expression of common hemangioblastic and hematopoietic precursor, as well as endothelial lineage markers, but has no effect on expression of the marker of lymphoid lineage development before day 16. These effects coincided with the expression of ERα. The enduring effects of DES exposure in-utero may not be manifest in this ES model, or may occur at later stages of differentiation or in selected subpopulations of CD45+ cells.<br>Master of Science
31
Ericson, Robin J. "Bridging solutions to the religion and science conflict over human embryonic stem cell research." Fairfax, VA : George Mason University, 2007. http://hdl.handle.net/1920/2926.
Full textAbstract:
Thesis (Ph. D.)--George Mason University, 2007.<br>Title from PDF t.p. (viewed Jan. 17, 2008). Thesis director: Richard E. Rubenstein. Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Conflict Analysis and Resolution. Vita: p. 228. Includes bibliographical references (p. 222-227). Also available in print.
32
Matsuura, Rie, Hiroshi Kogo, Takunori Ogaeri, et al. "Crucial transcription factors in endoderm and embryonic gut development are expressed in gut-like structures from mouse ES cells." Alpha Med Press, 2006. http://hdl.handle.net/2237/7444.
Full text
33
Sullivan, Denise D. "Incorporation of bio-inspired microparticles within embryonnic stem cell aggregates for directed differentiation." Thesis, Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/54909.
Full textAbstract:
Embryonic stem cells (ESCs) are a unique cell population that can differentiate into all three embryonic germ layers (endoderm, mesoderm, and ectoderm), rendering them an invaluable cell source for studying the molecular mechanisms of embryogenesis. Signaling molecules that direct tissue patterning during embryonic development are secreted by ESC aggregates, known as embryoid bodies (EBs). As many of these signaling proteins interact with the extracellular matrix (ECM), manipulation of the ESC extracellular environment provides a means to direct differentiation. ECM components, such as glycosaminoglycans (GAGs), play crucial roles in cell signaling and regulation of morphogen gradients during early development through binding and concentration of secreted growth factors. Thus, engineered biomaterials fabricated from highly sulfated GAGs, such as heparin, provide matrices for manipulation and efficient capture of ESC morphogens via reversible electrostatic and affinity interactions. Ultimately, biomaterials designed to efficiently capture and retain morphogenic factors offer an attractive platform to enhance the differentiation of ESCs toward defined cell types. The overall objective of this work was to examine the ability of microparticles synthesized from both synthetic and naturally-derived materials to enhance the local presentation of morphogens to direct ESC differentiation. The overall hypothesis was that microparticles that mimic the ECM can modulate ESC differentiation through sequestration of endogenous morphogens present within the EB microenvironment.
34
Schötz, Eva-Maria. "Dynamics and Mechanics of Zebrafish Embryonic Tissues." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2008. http://nbn-resolving.de/urn:nbn:de:swb:14-1191291301268-96071.
Full textAbstract:
Developmental biologists try to elucidate how it is possible for cells, all originating from the same egg, to develop into a variety of highly specialized structures, such as muscles, skin, brain and limbs. What organizes the behavior of these cells, and how can the information encoded in the DNA account for the observed patterns and developmental processes? Cell movements and tissue flow during embryogenesis constitute a beautiful problem of bridging scales: On the microscopic scale, cells are expressing particular genes which determine their identities and also their fate during morphogenesis. These molecular determinants then lead to the macroscopic phenomena of cell movements and tissue arrangements, for which one needs a continuum description in terms of active fluids. Taking into account that the number of cells is fairly small, a complete coarse graining is not possible, and a characterization of both mesoscopic (individual cell motion) and macroscopic (flow) behavior is required for a full description. In the here presented work, a set of different experimental methods was applied to investigate the mechanical and dynamical properties of zebrafish embryonic cells and tissues. This thesis is structured as follows: In chapter 2, we introduce the fundamental concepts that are important for the study of cell motion during zebrafish embryonic development. In chapter 3, the materials and methods applied in this work are described. The experimental results of my thesis-work are presented in chapters 4-8: Chapter 4 concentrates on the physical properties of whole tissues. It is shown that tissues are viscoelastic materials. Tissue viscoelasticity is not a new concept, but this study is the first one to quantify the mechanical properties of tissues that are in actual contact in a developing embryo. In chapter 5, cell rearrangements in culture, such as cell sorting and tissue wetting are discussed. These experiments show that tissue interactions are largely determined by tissue surface and interfacial tensions. In chapter 6, an optical stretcher device is applied to measure, solely by means of laser light, the material properties of individual cells. Hereby it is shown that single cells from the two investigated tissue types differ in their mechano-physical properties. After the study of cell and tissue mechanics, the dynamics of cell migration in three dimensions in tissue aggregates and in developing zebrafish embryos is addressed: In chapter 7, 3D-cell migration in multicellular aggregates is analyzed quantitatively by studying the mean square displacement, cell velocity distribution and velocity autocorrelation. In chapter 8, we study the cell motion within the developing zebrafish embryo. By following the motion of many cells in four dimensions, we are able to generate a velocity flow profile for this cell-flow. Chapter 9 gives a brief summary of the obtained results and an outlook to future projects motivated by the presented study. The final part of this thesis are four appendices. Appendix A contains protocols and additional methods. Appendix B contains several calculations, whose results were used in the main part of this work. Appendix C contains additional data and discussions, which were excluded from the main part due to space limitations. Finally, Appendix D consists of a compact disc with 11 movies and a movie description, which serves as supplemental material to the presented data. (Die Druckexemplare enthalten jeweils eine CD-ROM als Anlagenteil: 650 MB: Movies - Nutzung: Referat Informationsservice der SLUB)
35
Harding, Heather Darby. "Oct-4 expression in equine embryonic cells." Texas A&M University, 2005. http://hdl.handle.net/1969.1/4793.
Full textAbstract:
The Oct-4 transcription factor is believed to co-regulate early embryonic
development of mammals due to the correlation of its presence with the maintenance of
pluripotency. It is commonly used as a marker for the identification of embryonic stem
(ES) cells for this reason. Until 1999, Oct-4 studies were limited to in vivo-produced
embryos; equine embryos have not been studied for their Oct-4 expression patterns. In
addition, equine stem-like cells (defined by marker expression, induced differentiation,
passage survival, and morphology) have recently been isolated from in vivo-produced
embryos, but no work has been performed in horses to isolate ES cells from in vitroproduced
embryos.
This study investigated the expression of Oct-4 transcription factor using
immunocytochemistry in 42 in vitro-produced embryos aged 1-10 days and in 5 in vivoproduced
blastocysts aged 7-10 days. Effective conditions for rapid establishment of a
feeder layer of equine fetal fibroblasts were established, and this feeder layer was used to
grow isolated equine inner cell mass (ICM) cells from in vitro-produced embryos. The
expression of Oct-4 was examined in resultant cell growths.
In vitro-produced embryos less than 6 days of age showed variable staining
within blastomeres of the same embryo, and the peak of variability correlated with maternal-zygotic transition. After Oct-4 staining of in vitro-produced blastocysts, no
cells could be identified as an ICM based on a difference in fluorescent intensity from
the other cells of the blasyocysts. However, in vitro-produced blastocysts that were
subsequently cultured in vivo contained a presumptive ICM, visible based on greater
fluorescent intensity of Oct-4 stain. The trophoblast of all blastocysts also stained
positively for Oct-4 protein. Fibroblasts were successfully isolated from equine feti.
Treatment with 20 õg/ml of Mitomycin C arrested cell growth without causing excessive
death. Fibroblasts were inactivated and frozen, then thawed as needed to establish a
confluent monolayer for ICM isolation overnight. ICMs from in vitro-produced
embryos formed outgrowths, but none that could be identified morphologically as ES
cells. Outgrowth cells contained about 20% Oct-4 expressing cells in sporadic
groupings. Assuming appropriate binding of the Oct-4 antibody, Oct-4 expressing cells
(potentially indicating pluripotency) are found throughout the embryo in early
development and in the feeder layer after co-culture.
36
Joannides, Alexis. "Neural differentiation of human embryonic stem cells." Thesis, University of Cambridge, 2009. https://www.repository.cam.ac.uk/handle/1810/252121.
Full textAbstract:
Human embryonic stem cells (hESCs) are a potential source of defined cell types for studying early human development and application in regenerative medicine. Realising this potential requires a number of challenges to be overcome. The experimental findings reported represent a systematic approach in establishing controlled and standardised conditions for differentiating hESCs down the neural lineage, and characterising neural derivatives both <i>in vitro</i> and <i>in vivo.</i> Human embryonic stem cell cultures were established from two independently-derived liens, H9 and UES9. A novel, efficient method for propagating hESCs is described, avoiding the use of enzymatic products which may lead to karyotypic instability. Controlled neuroectodermal differentiation is demonstrated using a chemically defined system over a period of 16 days, and this process is shown to be dependent on endogenous fibroblast growth factor (FGF) signalling. Neural progenitors generated with this system are subsequently expanded for over 180 days and shown to retain neural stem cell (NSC) identity at the clonal level. Evidence is provided that hESC-derived NSCs follow a developmentally predictable timecourse of neurogenesis followed by gliogenesis, and their <i>in vitro</i> and <i>in vivo</i> behaviour is characterised with respect to temporal maturation and phenotypic potential.
37
Antonica, Francesco. "Modelling thyroid embryogenesis using embryonic stem cells." Doctoral thesis, Universite Libre de Bruxelles, 2013. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209551.
Full textAbstract:
Congenital hypothyroidism (CH) is the most frequent of the rare endocrine diseases (e.g. Addison's disease, Cushing's syndrome, Congenital adrenal hyperplasia.), which affects 1:2000 – 4000 newborns. If not immediately diagnosed after birth, thyroid hormones deficiency causes severe defects in brain and skeletal development leading to a complex clinical scenario called cretinism. CH can be due to a defective synthesis of thyroid hormones (dyshormonogenesis) or an abnormal embryonic development of the gland. Data obtained using knockout mouse models have shown the pivotal role of four specific transcription factors (NKX2.1, PAX8, FOXE1 and HHEX) for the correct organogenesis or function of the gland. Although mutations in those genes have been identified in few cases of CH patients, the pathogenetic mechanisms remain still elusive in the vast majority of CH cases (95%).<p>For the identification of new genes and molecular events controlling thyroid organogenesis it would be useful to develop an in vitro cellular model to recapitulate thyroid embryogenesis in a dish. Embryonic Stem Cells (ESCs) have recently emerged as system model to recapitulate the embryogenesis of several tissues in vitro.<p>Induced overexpression of defined transcription factors has been shown to have a directing effect on the differentiation of pluripotent stem cells into specific cell types. In this thesis I show that a transient overexpression of the transcription factors NKX2.1 and PAX8 is sufficient to direct the differentiation of murine ESCs into thyroid follicular cells (TFC) and promotes in vitro self- assembly of TFC into three-dimensional follicular structures, when associated to a subsequent thyrotropin (TSH) treatment. Cells differentiated by this protocol showed significant iodide organification activity, a hallmark of thyroid tissue function. Importantly, athyroid mice grafted with mESC-derived thyroid follicles show normalization of plasma T4 levels with concomitant decrease of plasma TSH. In addition, a full normalization of body temperature at 4 weeks after transplantation was observed. Together, these data clearly demonstrate that grafting of our mESC-derived thyroid cells rescues the hypothyroid state and triggers symptomatic recovery along with the normalization of plasma hormone concentrations. The high efficiency of TFC differentiation and follicle morphogenesis in our system will provide an unprecedented opportunity for future studies to decipher regulatory mechanisms involved in embryonic thyroid development, a major research need towards an improved understanding of the molecular mechanisms underlying congenital hypothyroidism, the most common congenital endocrine disorder in humans.<br>Doctorat en Sciences biomédicales et pharmaceutiques<br>info:eu-repo/semantics/nonPublished
38
Gordon-Keylock, Sabrina Anne Megan. "Haematopoietic differentiation of murine embryonic stem cells." Thesis, University of Edinburgh, 2009. http://hdl.handle.net/1842/29123.
Full textAbstract:
This thesis aimed to determine which subregions of the E10.5 aorta-gonad-mesonephros (AGM) were responsible for the haematopoietic enhancing effects that primary AGM regions had on differentiating ES cells. To this end, a novel co-culture system has been established to test the enhancing effects of a panel of clonal stromal cell lines derived from different subregions of the midgestational AGM. Three stromal cell lines derived from the dorsal aorta and surrounding mesenchyme (AM) subregion of the AGM were able to significantly enhance the frequency of ES cell derived multipotent haematopoietic progenitors. Two stromal cell lines derived from the urogenital ridges (UG) of the AGM did not enhance haematopoietic differentiation of ES cells. The haematopoietic enhancing effects were not retained by extracellular matrices isolated from the AM stromal cell layers and the effects were dependent on direct ES cell-stromal cell contact. Co-culture of an ES cell line carrying a <i>Brachyury-</i>eGFP reporter gene demonstrated that the stromal lines mediated their effects post-<i>Brachyury </i>(mesoderm) induction in the ES cells. In addition, co-culture of sorted ES cell populations confirmed that <i>Brachyury<sup>+</sup>, </i>but not <i>Brachyury<sup>-</sup>, </i>cells gave rise to haematopoietic progenitors in AM co-culture, supporting the notion that ES cell differentiation recapitulated the <i>in vivo</i> pattern of lineage specification. Transplantation of co-cultured ES cells into irradiated adult NOD/SCID mouse recipients led to low levels of engraftment in the spleen and bone marrow. Adult bone marrow cells achieved repopulation more readily in the NOD/SCID animal model when transplanted intra-splenically, compared to intravenous injection. This suggests that transplantation of ES-derived haematopoietic cells directly into the haematopoietic niche, by intra-splenic or intra-femoral injection, could facilitate repopulation.
39
Sneesby, Kyra, and n/a. "Gene Expression in Embryonic Chick Heart Development." Griffith University. School of Biomolecular and Biomedical Science, 2003. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20030924.153514.
Full textAbstract:
Establishment of the biochemical and molecular nature of cardiac development is essential for us to understand the relationship between genetic and morphological aspects of heart formation. The molecular mechanisms that underly heart development are still not clearly defined. To address this issue we have used two approaches to identify genes involved in early chick cardiac development. Differential display previously conducted in our laboratory led to the identification of two gene fragments differentially expressed in the heart that are further described in this thesis. The full-length cDNA sequence of both eukaryotic translation initiation factor-2b (eIF-2b) and NADH cytochrome b5 reductase (b5R) were isolated using library screening. The upreglation of these genes during heart development is expected given the heart is the first functional organ to form in vertebrates and protein synthesis and cell metabolism at this stage of development is maximal. Limitations in the differential display approach led to the development and optimisation of a subtractive hybridisation approach for use with small amounts of cells or tissue. To focus on cardiac gene expression during the initial phases of heart development, subtractive hybridization was performed between the cardiogenic lateral plate mesoderm of Hamburger and Hamilton stage 4 embryos and the heart primordia of stage 9 embryos. Of the 87 independent clones identified by this procedure, 59 matched known sequences with high homology, 25 matched unknown expressed sequence tag (EST) sequences with high homology, and 3 did not match any known sequence on the database. Known genes isolated included those involved in transcription, translation, cell signalling, RNA processing, and energy production. Two of these genes, high mobility group phosphoprotein A2 (HMGA2) and C1-20C, an unknown gene, were chosen for further characterisation. The role of each gene in early chick heart development and indeed development in general, was addressed using techniques such as in situ hybridisation, transfection analysis, in ovo electroporation and RNAi. HMGA2 is a nuclear phosphoprotein commonly referred to as an architectural transcription factor due to its ability to modulate DNA conformation. In keeping with this function, HMGA2/GFP fusion protein was shown to localise to the nucleus and in particular, the nucleolus. In situ hybridisation analysis suggested a role for HMGA2 in heart and somite development. HMGA2 expression was first detected at HH stage 5 in the lateral plate mesoderm, a region synonymous with cells specified to the cardiac fate. HMGA2 was also strongly expressed in the presomitic segmental plate mesoderm and as somites developed from the segmental plate mesoderm, the expression of HMGA2 showed an increasingly more restricted domain corresponding to the level of maturation of the somite. Restriction of HMGA2 expression was first detected in the dorsal region of the epithelial somite, then the dorsomedial lip of the dermomyotome, and finally the migrating epaxial myotome cells. The novel intronless gene, C1-20C, predicts a protein of 148 amino acids containing a putative zinc finger binding domain and prenyl binding motif. Zinc binding assays showed that the zinc finger domain of C1-20C/MBP fusion protein bound over six times the quantity of zinc compared to MBP alone, although not in a 1:1 stoichiometric molar ratio. C1-20C/GFP fusion protein was shown to localise to as yet unidentified intracellular cytoplasmic vesicular compartments. These compartments did not colocalise with the endosome/lysosome pathway, aparently ruling out a role for C1-20C in protein trafficking, recycling or degradation. Expression of C1-20C in the chick embryo suggests a possible role in heart and notochord development and preliminary results using siRNA suggest that C1-20C is involved in normal heart looping.
40
Lake, Julie-anne. "Differentiation of pluripotential murine embryonic stem cells." Adelaide Thesis (Ph.D.) -- University of Adelaide, Department of Biochemistry, 1996. http://hdl.handle.net/2440/18794.
Full text
41
Peeters, Maria Catharina Elisabeth. "Embryonic axial curvature relationships to neuropore closure /." [Maastricht : Maastricht : Universiteit Maastricht] ; University Library, Maastricht University [Host], 1998. http://arno.unimaas.nl/show.cgi?fid=8249.
Full text
42
Dumoulin, Johannes Christianus Marie. "Taurine and preimplantation embryonic development in vitro." Maastricht : Maastricht : Universitaire Pers Maastricht ; University Library, Maastricht University [Host], 1997. http://arno.unimaas.nl/show.cgi?fid=5937.
Full text
43
Both, Sanne Karijn. "Embryonic stem cells in bone tissue engineering." Enschede : University of Twente [Host], 2008. http://doc.utwente.nl/58765.
Full text
44
Pupavac, Mihaela. "Mmachc is required for mouse embryonic development." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=104863.
Full textAbstract:
The cblC form of combined methylmalonic aciduria and homocystinuria (OMIM 277400) is the most frequent inborn error of vitamin B12 (cobalamin, Cbl) metabolism, with over 500 patients identified worldwide. Due to mutations in the MMACHC gene, patients with this disease are unable to convert cobalamin into the two active forms, methylcobalamin and adenosylcobalamin, which are cofactors required by mammalian methionine synthase and methylmalonyl-CoA mutase, respectively. Clinical features of patients can include hematological, neurological, and ophthalmological findings, along with developmental delay. In this study, the requirement of Mmachc during mouse embryonic development is examined. The Mmachc gene was found to be expressed in head mesenchyme, dorsal root ganglia, heart, trachea, lung, esophagus, gut, mesonephric mesenchyme, and notochord during organogenesis in the mouse embryo. Mice containing a genetrap in intron 1 of the Mmachc gene were characterized. Mmachc heterozygous mice for the genetrap were shown to be fertile and viable, although a small number of heterozygous and wild type embryos were found to be phenotypically abnormal. Mice and embryos heterozygous for the MmachcGT1 allele were found in higher numbers than expected by Mendelian ratios. Embryos homozygous for the MmachcGT1 were only observed at embryonic day 3.5. These findings show that Mmachc is required during mouse embryonic development.<br>La forme cblC de l'acidurie méthylmalonique et l'homocystinurie combinée (OMIM 277400) est la maladie génétique la plus fréquente affectant le métabolisme de la vitamine B12 (cobalamine, Cbl), avec plus de 500 patients identifiés à travers le monde. En raison de mutations dans le gène MMACHC, les patients atteints de cette maladie sont incapables de convertir la cobalamine en les deux formes actives, soit la méthylcobalamine et l'adénosylcobalamine, qui sont des cofacteurs requis par les enzymes mammifères méthionine synthase et methylmalonyl-CoA mutase, respectivement. Les symptômes cliniques des patients peuvent être de l'ordre hématologique, neurologique, ophtalmologique ou d'un retard de développement. Dans cette étude, l'importance de MMACHC durant le développement embryonnaire de la souris est examinée. Le gène Mmachc est démontré comme étant exprimé dans le mésenchyme de la tête, les ganglions de la racine dorsale, le cœur, la trachée, les poumons, l'œsophage, l'intestin, mésenchyme mésonéphrique et la notochorde au cours de l'organogenèse chez l'embryon de souris. Une mutation de type « genetrap » a été insérée dans l'intron 1 du gène Mmachc, noté MmachcGT1, afin de bloquer la production d'une protéine fonctionnelle MMACHC. Les souris adultes hétérozygotes pour le « genetrap » Mmachc se sont avérées être fertiles et viables, même si un pourcentage d'embryons hétérozygotes possédait un phénotype anormal. Les souris et embryons hétérozygotes pour l'allèle MmachcGT1 ont été trouvés dans un nombre plus élevé que prévu par les ratios mendéliens. Les embryons homozygotes pour MmachcGT1 n'ont été observés qu'au jour embryonnaire 3.5. Ces résultats démontrent que le gène Mmachc est essentiel au cours du développement embryonnaire de la souris.
45
Love, Rebecca Margaret. "Improving the survival of embryonic dopaminergic neurons." Thesis, University of Oxford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343277.
Full text
46
Karunadasa, Delicia Kumari. "Embryonic development of GnRH and vomeronasal neurons." Thesis, University of Cambridge, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.615881.
Full text
47
Mak, Shiu-kwong Thomas, and 麥肇鑛. "Modeling diabetic cardiomyopathy using embryonic stem cells." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hdl.handle.net/10722/193562.
Full textAbstract:
Diabetic cardiomyopathy (DCM), a disorder of the heart muscle, is one of the major and most rampant culprits claiming thousands and thousands of lives around the globe every year by interfering with the blood circulation and causing the development of heart failure eventually. The progression of the disease is asymptomatic and having a long latent period, and it is characterized functionally by ventricular dilation, diastolic dysfunction, interstitial fibrosis and cardiomyocytes hypertrophy. It was suggested the pathogenesis of the disease and the related complications are related to the effects of hyperglycemia on cardiomyocytes. So understanding the physiology of both the normal and pathological conditions, and the underlying mechanisms involved are of paramount importance to derive therapies to cope with this disease. However, it is difficult, if not impossible, to study the physiology in vivo using a live sample or to build a cellular model with adult cardiomyocytes due to the insufficient number of the cells harvested. This is not until the emergence of Embryonic Stem Cells (ESCs) that a cellular model with clinical sufficient number of cardiomyocytes could be built for investigation and drug screening.
With a view to mimicking the situation of the Diabetic cardiomyopathy of the Type II Diabetes mellitus (DM) patients, mouse ESCs are used to differentiate into cardiomyocytes using the traditional hanging drop method to produce Embryoid body (EB). The cardiomyocytes were then enriched and plated so that different testing conditions could be applied. The effect of high glucose (HG), Insulin and the combination of high glucose and insulin were then analyzed. This was to show the significance of hyperglycemia, hyperinsulinemia due to insulin resistance and the role of insulin in hyperglycemia on cardiomyocytes respectively.
The results agreed with previous findings that high glucose and insulin alone do induce cells apoptosis while the combination of insulin and glucose did decrease the number of apoptosis and while the co-culture of insulin with High dosage of glucose has shown to reduce the effect of hypertrophy.<br>published_or_final_version<br>Medicine<br>Master<br>Master of Medical Sciences
48
Zhang, Xiaoxiao. "Cell Fate Decisions in Early Embryonic Development." Thesis, Harvard University, 2013. http://dissertations.umi.com/gsas.harvard:10792.
Full textAbstract:
The basis of developmental biology lies in the idea of when and how cells decide to divide or to differentiate. Previous studies have established several signaling pathways that determine cell fate decisions, including Notch, Wingless, Hedgehog, Bone morphogenetic protein, and Fibroblast growth factor. Signaling converges on transcriptional factors that regulate gene expression. In mouse embryonic stem cells, I explored how pluripotency and differentiation are regulated through opposing actions of beta-catenin-mediated canonical Wnt signaling, and the mechanisms underlying Sonic hedgehog signaling in generating progenitor cells in the ventral neural tube.
49
Henderson, Janet Katharine. "Investigations of human embryonic implantation in vitro." Thesis, University of Sheffield, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.341905.
Full text
50
Ruangvutilert, Pornpimol. "Genetic analysis of embryonic and fetal tissues." Thesis, University College London (University of London), 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326239.
Full text