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1
Jawdat, Razan S. „Investigating the role of mitochondria at the preimplantation stages of human embryonic development“. Thesis, University College London (University of London), 2018. http://discovery.ucl.ac.uk/10047392/.
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Mitochondria are the major energy producers in cells in the form of ATP. Proteins required for mitochondrial function are encoded by both mitochondrial (mtDNA) and nuclear DNA (nDNA) necessitating compatibility between the two genomes. Good quality oocytes containing an optimal number of mitochondria and sufficient levels of ATP produce higher quality blastocysts. Recent data suggests an elevated level of mtDNA may be associated with aneuploidy in blastocysts. In this study, preimplantation embryo development was investigated in relation to mtDNA template number and aneuploidy. ATP levels were measured in blastocysts and linked to aneuploidy. To investigate possible nDNA/mtDNA mismatch, DNA from couples with repeated miscarriage or repeated implantation failure (RM/RIF) was compared with DNA from couples with no history of infertility but who had preimplantation genetic diagnosis (PGD) for monogenic disorders. DNA from both groups was genotyped using SNP arrays. Sequencing of the mitochondrial genome and a set of 53 nuclear-encoded genes important in mitochondrial function was also performed. Further sequencing of the selected nuclear genes in embryos from the PGD group was used to identify variants in the nuclear and mitochondrial genomes associated with poor embryo development. Our data showed that arrested embryos that were euploid had more mtDNA than arrested embryos that were aneuploid. Aneuploidy in blastocysts resulted in variability in ATP levels. When aneuploidy was present in more than ten chromosomes, ATP was almost undetectable. From the sequencing analysis, significantly more couples with RM/RIF (5/12) had partners from the same mtDNA haplogroup compared with the PGD group of couples (1/11). Yet, SNP data analysed by identity by state (IBS) showed no significant differences between partners in couples based on their nDNA even when the HLA region was considered separately. Within the PGD group, the presence of the T haplogroup in the male partner was associated with a smaller percentage of embryos developing to blastocysts. Analysis of embryos from these couples suggested a link with SNPs in nuclear genes (specifically COQ9 and PPARGC1a) encoding mitochondrial proteins which may contribute to poor embryo development due to a disturbance in the electron transport chain or mitochondrial biogenesis respectively. Determining the mitochondrial haplogroups of both parents is a useful tool to investigate potential mismatch between the nuclear and mitochondrial genomes in embryos which may influence their development.
2
Ghosh, Samiran. „Identification of low temperature resistant embryonic stages for improving seed production in muga silkworm, antheraea assama, westwood for cold preservation of eggs“. Thesis, University of North Bengal, 2018. http://ir.nbu.ac.in/handle/123456789/2697.
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3
Lamoureux, Denis Oswald. „Development of the embryonic dentition in Xenopus laevis, Daudin, descriptive and experimental studies between stages 54 and 61“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/nq21589.pdf.
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4
Allan-Wojtas, Paula. „Ultrastructural characteristics of yolk in the chicken egg. Mechanisms for yolk absorption and its digestion by the yolk sac at different stages of embryonic development“. Thesis, University of Ottawa (Canada), 1994. http://hdl.handle.net/10393/6930.
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An ultrastructural study using electron microscopy was undertaken of yolk and yolk sac to elucidate digestive mechanisms and to gather evidence to further substantiate the belief that intracellular digestion of yolk takes place in yolk sac epithelial cells during incubation. Initial work focused on the ultrastructure yolk in unincubated eggs using transmission electron microscopy of thin sections of yolk which had been fixed using conventional and novel fixatives. The next phase of the study involved the ultrastructural comparison of granules from sub-blastodermic fluid from 9 day old embryos, and extracellular yolk attached to the yolk sac of 15 day old embryos with the granules from yolk of unincubated eggs. The third phase of the study was the ultrastructural description of yolk sacs at 3 ages (3 days, 8 days and 15 days of incubation). A transport system for yolk lipid and its digestion products to the embryo was demonstrated ultrastructurally using the Imidazole-buffered Osmium Tetroxide protocol of Angermuller and Fahimi (1982) which enhanced lipid staining. We observed no ultrastructural changes in extracellular yolk granules and matrix particles at any age studied. Granules and matrix particles are taken up by endocytosis, and ultrastructural changes of yolk granules occur in epithelial cells, in acid phosphatase-containing vacuoles (which we have identified as secondary lysosomes), which are part of the functioning intracellular digestive system. We have ultrastructurally demonstrated the transport of lipids, which becomes more evident in 13 day old embryos. On the basis of the above evidence we conclude that yolk is digested in epithelial cells of the yolk sac, and the digestion products enter the blood sinuses and travel in the bloodstream to deliver nutrients to the developing embryo. (Abstract shortened by UMI.)
5
Pinho, Sandra Isabel da Rocha Lourenco de. „Regulation of pluripotent states in human embryonic stem cells“. Thesis, Imperial College London, 2009. http://hdl.handle.net/10044/1/5884.
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A growing array of mouse and human pluripotent stem cell lines has been derived from the early embryo as well as from adult cells reprogrammed by ectopic expression of transcription factors – i.e. induced pluripotent stem (iPS) cells. These cell lines share the expression of key pluripotency markers and are able to self-renew and to generate differentiated progenies when induced. Their relationship to each other and whether they correspond to different pluripotent states with distinct developmental capacities and affiliations in vivo remains unclear, however. Profiling chromatin in a particular cell line has proven to be a valuable signature for cell identity and developmental stage. One approach has been to assay the timing of DNA replication across a panel of loci, as an indicator of chromatin accessibility. Of interest, this replication timing profiling was capable of discriminating pluripotent mouse ES (mES) cells from cells with a more restricted differentiation capacity. In this study, I have addressed whether distinct pluripotent states could be reliably discriminated at the chromatin level. In particular, I characterised the replication timing profile of a number of human ES (hES) cell lines alongside mES and mouse epiblast-derived stem (mEpiS) cell lines. I showed that mES cells have a steady and mostly early-replicating profile, regardless of their genetic background. In contrast, the profile of undifferentiated H1, H7 and H9 hES cell lines harboured an increased proportion of late-replicating loci during S-phase. Moreover, hES cell replication profile greatly varied between cultures and cell lines; a level of replication timing variability also observed among mEpiS cells, as opposed to mES cells. These results highlighted that hES and mEpiS cells share a common unstable or transitional state: primed on the verge of differentiation. This view was, however, further challenged by exploring how hES cell cultures could be modulated towards an ES-like versus epiblast-like state under different conditions. In particular, extensive and dynamic shifts of replication timing, from late to early, were consistently observed at many target loci in hES and hiPS cells upon increased Smad2/3 and p300 histone acetyltransferase activity. Importantly, these alterations were reversible and associated with differential gene expression profiles and functional properties of hES cells. Collectively, these data revealed the existence of distinct but interchangeable pluripotent hES cell states and proposed a key role for TGF-β/Activin signalling and the HAT p300 in modulating the balance between a naive versus primed state in hES cell cultures.
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Cho, Ting-yin. „Conversion from mouse embryonic to extra-embryonic endoderm stem cells reveals distinct differentiation capacities of pluripotent stem cell states“. Thesis, University of Cambridge, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.607991.
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7
Autio, Matias. „Investigating the regulation of distinct epigenetic states in human embryonic stem cells“. Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/11046.
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Accumulating evidence suggest that pluripotency – the ability to generate all somatic cell types – is not a fixed state. Pluripotent cell populations encompass a heterogeneous group of cells with different phenotypic and functional properties in equilibrium. At least two phases of pluripotency, immature and primed for differentiation, have been identified during early mouse development, and these are typified by the two distinct stem cell populations – mouse embryonic (mES) and epiblast-‐derived (mEpiS) stem cells – isolated from epiblast layers of pre-‐ and post-‐implantation embryo, respectively. Many lines of human ES (hES) cells have also been established in vitro from the inner cell mass of pre-‐ implantation blastocysts yet the precise in vivo lineage affiliation of these cells remains largely unresolved. Profiling chromatin in a particular cell line has proven to be a valuable signature for cell identity and developmental stage. One approach has been to assay the timing of DNA replication during S-‐phase of the cell cycle across a panel of loci, as an indicator of chromatin accessibility. This replication timing profiling was notably capable of discriminating pluripotent mES cells from cells with a more restricted differentiation capacity. This study sought to address whether distinct pluripotent states could be reliably discriminated at the chromatin level. In particular, the replication timing profiles of a number of hES cell lines were characterised and compared to those of mES and mEpiS cell lines derived from different genetic backgrounds. Profiles of undifferentiated H1, H7 and H9 hES cell lines typically harboured an increased proportion of late-‐replicating loci during S-‐ phase when compared to mES cells, which were confirmed to have a steady and mostly early-‐replicating profile regardless of their genetic background. Moreover, hES cell replication profile greatly varied between cultures and cell lines; a level of replication timing variability also observed among mEpiS cells, as opposed to mES cells. These results highlight that hES and mEpiS cells most likely share a common unstable epigenetic state or transitional state primed on the verge of differentiation. The epigenetic state of hES cell lines was further interrogated by analysing cells grown under two different culture conditions, both however similarly relying on TGF-‐β/Activin signalling. Results demonstrated that hES cells could adopt distinct yet reversible epigenetic signatures while retaining their pluripotency. In particular, extensive and dynamic shifts of replication timing, from late-‐to-‐early, were consistently observed at many target loci in hES cells as well as in human induced pluripotent cells (iPS) cells, upon increased SMAD2/3-‐associated P300/CBP histone acetyltransferase (HAT) activity. This was accompanied by fluctuations in the expression of NANOG and REX1 (also known as ZFP42), and a change in hES cell’s functional properties, as judged by their responsiveness to differentiation-‐inducing signals. Interestingly, inhibiting P300/CBP HAT activity by curcumin treatment in undifferentiated hES cells was sufficient to revert back to a late-‐replicating profile associated with a histone hypoacetylated state. Stable knockdown of P300 in hES cell cultures, however, resulted in a gradual loss of the pluripotent identity through differentiation or apoptosis, preventing further analysis of effects on replication timing. Collectively, these data strongly support the view that different but interchangeable pluripotent states exist within hES cell cultures and suggest a role for P300/CBP HAT activity in determining distinct epigenetic states in hES cells. As mentioned above, REX1 was also significantly upregulated in H1 hES cells upon culture condition change. REX1 is a developmental stage-‐specific marker that is expressed in the ICM of both mouse and human embryos, as well as in pluripotent mES, hES and iPS cells. However, its function in hES cells remains largely unclear. Human ES cells overexpressing REX1 were here generated to investigate the role of REX1 in regulating hES cell pluripotent identity. These cells expressed similar levels of key pluripotency markers than their normal counterparts and remained capable of self-‐renewing and differentiating into the three germ layers in vitro. Interestingly, however, upon withdrawal of exogenous Activin A, REX1 overexpressing hES cells in contrast to control cells retained a comparatively high level of OCT4 and stained positive for alkaline phosphatase, a known marker of undifferentiated hES cells. Taken together, these results point to a possible role for REX1 in sustaining hES cell self-‐renewal ability.
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Lange, Léa. „Influences environnementales précoces et plasticité phénotypique : étude d’un modèle amphibien avec soins parentaux prénataux, l’Alyte accoucheur“. Thesis, La Rochelle, 2020. http://www.theses.fr/2020LAROS016.
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L’Alyte accoucheur (Alytes obstetricans) est une espèce d’amphibien où les soins parentaux sont réalisés par le mâle exclusivement. En effet, après l’accouplement, durant lequel le mâle participe activement à l’émission des oeufs, il attache sa ponte autour des articulations de ses membres postérieurs et la porte ainsi pendant tout le développement embryonnaire. Les amphibiens sont très sensibles à l’environnement abiotique, notamment aux conditions hydriques et thermiques. Pour éviter les températures extrêmes, ils peuvent thermoréguler comportementalement, par exemple en sélectionnant des refuges aux conditions microclimatiques favorables. Les Alytes accoucheurs ont montré une sélection de leurs refuges sur la base de leurs propriétés hydriques et thermiques. Les stades de développement précoces sont particulièrement sensibles à la température. Les parents peuvent alors réaliser des comportements parentaux pour en limiter les effets. Un effet phénologique paternel a été observé chez les Alytes accoucheurs, dont les mâles favorisent des températures plus élevées lorsqu’ils portent des oeufs. Les comportements parentaux sont cependant coûteux pour les adultes. Les Alytes accoucheurs ont présenté des performances de locomotion diminuées pendant le port des oeufs, ce qui pourrait induire une diminution de l’aptitude. De plus, les comportements parentaux influencent fortement le développement des jeunes. L’environnement thermique rencontré pendant le stade embryonnaire, et donc pendant la période de soins parentaux chez l’Alyte accoucheur, a eu des effets à court terme et des effets persistants sur la phénologie. L’environnement thermique rencontré pendant le stade larvaire peut également être déterminant. Chez l’Alyte accoucheur, l’environnement thermique postnatal a induit un basculement vers un développement pluriannuel lors d’un développement à 16°C, avec un hivernage au stade têtard, alors qu’il a été annuel lors d’un développement à 20°C et 24°C. L’environnement thermique postnatal a également impliqué des modifications morphologiques, physiologiques et comportementales. Enfin, une implication de la physiologie, et notamment de la fréquence cardiaque, a été observée tout au long du développement embryonnaire et larvaire des jeunesThe common Midwife toad (Alytes obstetricans) is a species of amphibian in which parental care is performed exclusively by the male. Indeed, after mating, during which the male actively helps the female for the emission of the eggs, he attaches the clutch around the joints of his hind limbs and thus carries it throughout embryonic development. Amphibians are very sensitive to the abiotic environment, especially to hydric and thermal conditions. To avoid extreme temperatures, they can behaviourally thermoregulate, for example by selecting refuges with favourable microclimatic conditions. The common Midwife toad has shown a selection of their refuges based on their hydric and thermal properties. The early stages of development are particularly sensitive to temperature. Parents can then carry out parental care to limit the effects. A paternal phenological effect has been observed in common Midwife toad, whose males favour higher temperatures when they carry eggs. Parental care is costly for adults, however. The common Midwife toad exhibited decreased locomotion performances during egg carrying, which could lead to decreased fitness. In addition, parental care strongly influences the development of young. The thermal environment encountered during the embryonic stage, and therefore during the period of parental care in the common Midwife toad, had both short-term and persistent effects on the phenology. The thermal environment encountered during the larval stage can also be decisive. In the common Midwife toad, the postnatal thermal environment induced a switch to multi-year development during development at 16 ° C, with overwintering at the tadpole stage, whereas it was annual during development at 20 ° C and 24 ° C. The postnatal thermal environment has also involved morphological, physiological, and behavioural changes. Finally, an involvement of physiology, and in particular heart rate, has been observed throughout the embryonic and larval development of the young
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Pinnock, Howard A. „A proposed framework for an embryonic environmental review process for Jamaica“. Thesis, Virginia Tech, 1988. http://hdl.handle.net/10919/43268.
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Jamaica is faced with a number of serious environmental problems. Perhaps the most promising approach to address these problems is to subject development proposals to a process of environmental review while they are in the central government's planning approval process. Jamaica has never had such an environmental review process. In this thesis an attempt was made to develop the framework for an environmental review process that can be integrated into the Jamaican planning approval process.
Guided by case studies of the environmental review processes in three U.S. states and Puerto Rico, as well as an analysis of Jamaica's unique conditions as they affect the implementation of an environmental review process, an attempt was made to synthesize a framework for an environmental review process that can be both implementable and effective in Jamaica. In addition, an attempt was made to suggest some general strategies for achieving the implementation of the environmental review process.
A simple yet potentially effective EIA framework was developed. However, the necessary preconditions for effective implementation, i.e., political support, do not exist in Jamaica. Unless the environment becomes a major issue in Jamaica's political economy, it is unrealistic to expect the implementation of an effective process.Master of Urban and Regional Planning
10
McKenna, Erin N. „Embryonic policies the stunted development of in vitro fertilization in the United States, 1975-1992 /“. Connect to this title online, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=bgsu1143490658.
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11
Kazakevych, Juri [Verfasser]. „Epigenetic chromatin states during embryonic development and adult homeostasis of the mammalian gut / Juri Kazakevych“. Mainz : Universitätsbibliothek Mainz, 2017. http://d-nb.info/1132229375/34.
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12
McKenna, Erin Nicole. „Embryonic Policies: The Stunted Development of In Vitro Fertilization in the United States, 1975-1992“. Bowling Green State University / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1143490658.
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13
Nutakki, Gopi Chand. „Appearance Based Stage Recognition of Drosophila Embryos“. TopSCHOLAR®, 2010. http://digitalcommons.wku.edu/theses/217.
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Stages in Drosophila development denote the time after fertilization at which certain specific events occur in the developmental cycle. Stage information of a host embryo, as well as spatial information of a gene expression region is indispensable input for the discovery of the pattern of gene-gene interaction. Manual labeling of stages is becoming a bottleneck under the circumstance of high throughput embryo images. Automatic recognition based on the appearances of embryos is becoming a more desirable scheme. This problem, however, is very challenging due to severe variations of illumination and gene expressions. In this research thesis, we propose an appearance based recognition method using orientation histograms and Gabor filter. Furthermore, we apply Principal Component Analysis to reduce the dimension of the low-level features, aiming to accelerate the speed of recognition. With the experiments on BDGP images, we show the promise of the proposed method.
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Trayer, Vincent. „Rôle du cortisol dans le développement des ionocytes de la peau chez l'embryon de médaka (Oryzias Latipes) et conséquences sur l'osmorégulation des stades larvaires“. Thesis, Rennes 1, 2013. http://www.theses.fr/2013REN1S144/document.
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Le cortisol est reconnu pour être une hormone clé dans le maintien de la balance hydrominérale en eau douce et dans l'adaptation à l'eau de mer, chez de nombreux téléostéens juvéniles. Cependant, son rôle au cours du développement embryonnaire est encore mal connu, notamment son implication dans le développement des cellules spécialisées dans le transport ionique, les ionocytes. L'objectif de ma thèse a été de déterminer l'implication du cortisol lors de la mise en place du lignage des ionocytes de la peau chez l'embryon de médaka (Orysias latipes) puis d'étudier les conséquences d'une élévation du cortisol embryonnaire sur les capacités osmorégulatrices des larves lors d’un transfert dans une eau pauvre en ions ou en eau de mer. Dans un premier temps, une attention particulière a été portée à la dynamique d'apparition des ionocytes de la peau du sac vitellin des embryons. Ces derniers apparaissent en deux vagues successives avec une cinétique propre. Nous avons alors proposé un modèle de développement des ionocytes pour chacune de ces vagues. Grâce à cette première étude, nous avons ensuite montré que du cortisol exogène ne modifie pas le taux de prolifération et/ou de différenciation des ionocytes épidermiques mais accélère leur différenciation. De plus, nous avons identifié un des récepteurs aux glucocorticoïdes (GR2) comme régulateur de l’ontogenèse des ionocytes, très probablement grâce à ces transcrits maternels. Enfin, nous avons montré que les larves de médaka sont capables de réguler très rapidement leurs contenus en ions Na+ et Cl- après de chocs hypo- et hyper-osmotiques. En revanche, la capacité des larves à réguler les contenus en Ca2+ est plus limitée lors d’un choc hypo-osmotique. Un doute important sur l’efficacité du traitement cortisol lors de cette dernière partie ne nous permet pas de mettre en lien le rôle du cortisol dans l’ontogenèse des ionocytes avec la fonction d’osmorégulation de ces derniers à l’éclosion. Ces travaux ont donc permis d’établir les bases de l’ontogenèse des ionocytes embryonnaires ainsi que de l’osmorégulation des larves chez le médaka pour la caractérisation du rôle du cortisol et de ses récepteurs. De façon similaire, ce modèle pourra être utilisé comme support pour l’identification et la caractérisation de nouveaux régulateursCortisol is a key hormone regulating in teleost fish water and ionic homeostasis in freshwater and seawater and in acclimation during salinity changes. However, its role during embryonic stages is still poorly known, especially its involvement in the development of ionic transport specialized cell, namely the ionocytes. The aim of my thesis was to determine cortisol involvement in epidermal ionocyte lineage establishment in medaka (Orysias latipes) embryos and to study consequences of cortisol elevation in medaka embryos on larval osmoregulatory abilities during transfer from freshwater to ion-poor environment or to seawater transfer. In a first part, we studied the dynamic of ionocyte appearance in yolk-sac epithelium of embryos. Ionocytes appear in two distinct waves with their own kinetic. This allowed us to propose a model of ionocyte development for each wave. In the continuity of this first part, we have showed that exogenous cortisol doesn’t modify the proliferation and/or differentiation rate of epidermal ionocytes but rather accelerate their differentiation. In addition, we have identified GR2, one of glucocorticoid receptors, as the main regulator of ionocyte ontogenesis, most likely through its maternal transcripts. Finally, we have showed that medaka larvae are able to quickly regulate their Na+ and Cl- ion contents after hypo- or hyper-osmotic challenges. In contrast, larvae ability to regulate Ca2+ ion contents is more limited during hypo-osmotic challenge. A doubt on the effectiveness of the cortisol treatment, in this last part, prevent us to understand the relationship between cortisol role in ionocyte ontogenesis and its osmoregulatory functions after hatching. These studies have established in medaka the basis of embryonic ionocyte ontogenesis and larval osmoregulation in order to clarify the role of cortisol and its receptors. Similarly, this fish model could be used as a support for identification and characterization of new regulators of the osmoregulation function
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SHAMS, S. SAMADI. „IDENTIFYING THE MOLECULAR PLAYERS ASSOCIATED WITH TRANSITION BETWEEN PLURIPOTENT AND TOTIPOTENT-LIKE STATES“. Doctoral thesis, Università degli Studi di Milano, 2017. http://hdl.handle.net/2434/471389.
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The presence of rare transient cells within pluripotent stem cell population that resemble functional and transcriptional features of totipotent 2-cell-stage embryos has emerged several questions regarding their mechanism of reactivation. Although few recent works have aimed to characterize them both at transcriptional and functional level, the mechanism of transition to 2C-like state is poorly investigated. Here we identified a new pathway, whose activation through several compounds could induce transition to 2C-like state. Interestingly, inhibition of this pathway by specific inhibitors could collectively restrain the majority of the 2C-like state transcriptional alterations including MuERV-L and Zscan4 gene family. Finally, we found that developmental potential of induced 2C-like cells could be extended to embryonic plus extra-embryonic tissues in contrast to embryonic stem cells in culture. Our finding provides a better understanding of cellular plasticity at early embryonic state, which could be important for the potential therapeutic avenues.
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Collier, Amanda. „Characterising the reprogramming dynamics between human pluripotent states“. Thesis, University of Cambridge, 2019. https://www.repository.cam.ac.uk/handle/1810/287952.
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Human pluripotent stem cells (hPSCs) exist in multiple states of pluripotency, broadly categorised as naïve and primed states. These provide an important model to investigate the earliest stages of human embryonic development. Naïve cells can be obtained through primed-to-naïve reprogramming; however, there are no reliable methods to prospectively isolate unmodified naïve cells during this process. Moreover, the current isolation strategies are incompatible for enrichment of naïve hPSCs early during reprogramming. Consequently, we know very little about the temporal dynamics of transcriptional changes and remodelling of the epigenetic landscape that occurs during the reprogramming process. To address this knowledge gap, I sought to develop an isolation strategy capable of identifying nascent naïve hPSCs early during reprogramming. Comprehensive profiling of cell-surface markers by flow cytometry in naïve and primed hPSCs revealed pluripotent state-specific antibodies. By compiling the identified state-specific markers into a multiplexed antibody panel, I was able to distinguish naïve and primed hPSCs. Moreover, the antibody panel was able to track the dynamics of primed-to-naïve reprogramming, as the state-specific surface markers collectively reflect the change in pluripotent states. Through using the newly identified surface markers, I found that naïve cells are formed at a much earlier time point than previously realised, and could be subsequently isolated from a heterogeneous cell population early during reprogramming. This allowed me to perform the first molecular characterisation of nascent naïve hPSCs, which revealed distinct transcriptional changes associated with early and late stage naïve cell formation. Analysis of the DNA methylation landscape showed that nascent naïve cells are globally hypomethylated, whilst imprint methylation is largely preserved. Moreover, the loss of DNA methylation precedes X-chromosome reactivation, which occurs primarily during the late-stage of primed-to-naïve reprogramming, and is therefore a hallmark of mature naïve cells. Using the antibody panel at discrete time points throughout reprogramming has allowed an unprecedented insight into the early molecular events leading to naïve cell formation, and permits the direct comparison between different naïve reprogramming methods. Taken together, the identified state-specific surface markers provide a robust and straightforward method to unambiguously define human PSC states, and reveal for the first time the order of transcriptional and epigenetic changes associated with primed to naïve reprogramming.
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Kobayashi(Yurugi), Takami. „Effective contribution of transplanted vascular progenitor cells derived from embryonic stem cells to adult neovascularization in proper differentiation stage“. Kyoto University, 2003. http://hdl.handle.net/2433/148717.
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Grillo, Jean-Marie. „Etude du nucléole de l'embryon humain pendant les premiers stades de la segmentation : activation des gènes ribosomiques au cours de la nucléologenèse“. Aix-Marseille 2, 1990. http://www.theses.fr/1990AIX21902.
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Brannan, Katla Jorundsdottir. „Telomerase and its reverse transcriptase subunit TERT : identification and oestrogenic modulation of telomerase transcription in two aquatic test species - European Purple Sea Urchin (Paracentrotus Lividus) and Rainbow Trout (Oncorhynchus Mykiss)“. Thesis, University of Exeter, 2012. http://hdl.handle.net/10871/16556.
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A plethora of naturally-produced steroid hormones, or artificial homologues of them, are being introduced into the aquatic and terrestrial environments each year. Two examples of these are the natural oestrogen 17ï¢-oestradiol (E2) and the oestrogen receptor antagonist, Bisphenol A (BPA), both of which target the ribonucleoprotein telomerase through upregulation of its telomerase reverse transcriptase component, TERT. The main objectives of this study were firstly to isolate and characterize the actual mRNA sequence for the telomerase catalytic subuninit, Tert, in rainbow trout (Oncorhynchus mykiss) (Walbaum, 1792) and European purple sea urchin (Paracentrotus lividus) (Lamarck, 1816), with the aim of developing qPCR assays for the amplification and quantification of Tert. Further objectives were to use these assays in controlled exposure studies to establish whether and to what extent the aforementioned chemicals regulate Tert transcription and by doing so further understand the mechanism of Telomerase gene expression and the extent to which environmental oestrogen can interfere. The initial step of sequence characterization and assay devlopment was successful in the case of rainbow trout where two possible splice variants of Tert mRNA are identified, omTertShort and omTertLong. Two qPCR assays were developed for the relative quantification of both of these splice variants in rainbow trout samples, the latter of these successfully amplifying its target in test samples. In order to demonstrate in vitro and in vivo modulation of telomerase activity and mRNA expression, early life-stages of rainbow trout and purple sea urchin, as well as rainbow trout hepatocytes, were exposed to a range of concentrations of E2 and BPA. Purple sea urchin embryos were exposed to 200, 20 and 2 ng E2/ml for 28 hours until they had reached the stage of pluteus larvaes. Rainbow trout embryos were exposed to 500, 20 and 0.1 ng E2/ml and 600 and 150 ng BPA/ml for 167 days from immediately after fertilization. Rainbow trout hepatocytes were exposed to 20 and 2 ng E2/ml for 48 hours. The results from this study show that telomerase activity as well as TERT mRNA expression can be significantly modulated by exposure to oestrogens and other oestrogenic chemicals. E2 concentrations as low as 20 ng/ml lead to an increase in telomerase activity early-life stages of purple sea urchin and upregulation in the transcription of Tert mRNA in unhatched rainbow trout embryos. BPA induced similar response (600 ng/ml) in hatched rainbow trout alevins larvae. Very high exposures to E2 (500 ng/ml) do however lead to downregulation of Tert mRNA in hatched alevins larvae. Differential regulatory response can be observed between different tissue types of 167 day old fry, with an upregulatory response observed at 0.1 ng E2/ml in liver and muscle tissues, but not in brain. Similarly, brain tissues were observed expressing significantly less mRNA than liver and muscle samples when exposed to BPA (150 ng/ml). It is evident that the previously observed link between environmental oestrogens and telomerase is also present in the two test species examined; purple sea urchin and rainbow trout.
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McManigal, Barney. „Controlling controversial science : biotechnology policy in Britain and the United States (1984-2004)“. Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:eda8d57b-66dc-4cd6-8ad4-d863ae43e8ed.
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This thesis addresses the puzzle of variation in first-generation regulatory policies for controversial science and technology, as demonstrated in the cases of agricultural genetically modified organisms (GMOs) and human embryonic stem cell research in the United Kingdom and the United States. Why did policy outcomes vary in each technology case? This study answers this question by placing greater emphasis on institutional factors. Although works within institutional analysis, bureaucracy and regulation literatures make significant progress in revealing how existing institutions can shape outcomes, how far one can characterize bureaucratic behavior and whether interest groups capture regulation, they nevertheless create an opening for research that: describes a mechanism for path dependence to explain variation in policies; shows the degree to which bureaucratic behaviors can influence outcomes; and, highlights instances in which regulatory officials hold power. This thesis makes an original contribution by providing new historical details relating to these cases, and by providing an extensive elaboration of Pierson’s criteria for increasing returns and a so-called secondary test of path dependence to explain outcomes. The study recounts the biography of key policy documents in each case by tracing the process of decision-making through government and archival sources, secondary literature and more than 40 elite interviews. In doing so, it details the activities of key governmental bodies within the European Union, UK and US. Moreover, it shows how the Coordinated Framework (1986) and Human Fertilisation and Embryology Act 1990 framework represented decision-making structures which triggered changes in actors and interests and shaped permissive outcomes for GMOs and stem cell research in the US and UK, respectively. Furthermore, lack of comparable structures may help account for restrictive policies for GMOs in Europe and the UK, and for stem cell research in the US.
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GNOCCHI, ANDREA. „UNDERSTANDING THE IMPACT OF REPLICATION STRESS ON THE EXPRESSION OF EARLY GENES IN MOUSE EMBRYONIC STEM CELLS“. Doctoral thesis, Università degli Studi di Milano, 2021. http://hdl.handle.net/2434/814703.
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Embryonic stem cells (ESCs) are characterized by a rapid cell cycle, which leads to high replication stress (RS) in otherwise unperturbed conditions. The mechanisms that ESCs adopt to cope with their endogenous RS, however, remain to this day elusive. In our recent work we demonstrated that the activation of the checkpoint kinase ATR in response to RS leads to a broad activation of 2-cells stage specific genes in mouse ESCs. This response relies on the up-regulation of Dux, a transcription factor encoded in a macrosatellite sequence repeated in tandem. Dux is repressed by variant Polycomb repressive complex 1 (vPRC1) in unperturbed ESCs, independently from PRC2 presence.
Here we demonstrate that RS causes a major rearrangement of both PRC1 and PRC2 in ESCs nuclei, resulting in a major loss of both repressive marks in correspondence to target promoters. Surprisingly, Dux undergoes an increase in vPRC1 occupancy upon RS in an ATR-dependent manner, possibly due to PRC1 involvement in the replication of highly repeated DNA sequences. More interestingly, Dux activation upon RS requires the presence of PRC2. This result is possibly due to PRC2 proved role in the processing of stalled replication forks, which are the main structure signaling RS. In agreement to this data, also the fork remodeling translocases HLTF and ZRANB3 displayed an effect in Dux activation following RS.
Taken together, our results show that the up-regulation of 2-cells genes following RS not only requires ATR activation, but also downstream remodeling processes.
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Rahimian, Shayan [Verfasser], Matthias [Akademischer Betreuer] Gauly, Christoph [Gutachter] Knorr und Jürgen [Gutachter] Hummel. „Studies on the Ascaridia galli embryonal stages, potential maternal protection and immune response in chicken / Shayan Rahimian ; Gutachter: Christoph Knorr, Jürgen Hummel ; Betreuer: Matthias Gauly“. Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2017. http://d-nb.info/112380348X/34.
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Popken, Jens [Verfasser], und Thomas [Akademischer Betreuer] Cremer. „Stage-dependent changes of the nuclear architecture, envelope and lamina during mammalian early embryonic development studied with a novel 3D structured illumination microscopy protocol / Jens Popken. Betreuer: Thomas Cremer“. München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2016. http://d-nb.info/1096162822/34.
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Popken, Jens Verfasser], und Thomas [Akademischer Betreuer] [Cremer. „Stage-dependent changes of the nuclear architecture, envelope and lamina during mammalian early embryonic development studied with a novel 3D structured illumination microscopy protocol / Jens Popken. Betreuer: Thomas Cremer“. München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2016. http://nbn-resolving.de/urn:nbn:de:bvb:19-193177.
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Réalis-Doyelle, Emilie. „Influence de la température sur les premiers stades de vie de trois espèces de poissons dulcicoles : étude de la survie et de la plasticité phénotypique“. Thesis, Université de Lorraine, 2016. http://www.theses.fr/2016LORR0272/document.
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D’après le dernier rapport du groupe d'experts intergouvernemental sur l'évolution du climat (GIEC), le réchauffement climatique devrait se poursuivre au cours du siècle prochain. La température atmosphérique moyenne pourrait augmenter de 0,3°C à 4,8°C avec des valeurs extrêmes allant de 1°C à 6°C en 2100. Ces changements de température auront des conséquences directes et indirectes sur l’ensemble de la biodiversité et plus particulièrement sur les poissons qui sont des animaux poïkilothermes. Dans cette étude, trois espèces ont été choisies en prenant en compte leur stratégie de reproduction et leur différence de tolérance thermique : la truite commune (Salmo trutta), le brochet (Esox lucius) et la carpe commune (Cyprinus carpio). Nous avons, pour chacune des trois espèces, appliqué les mêmes différences de température par rapport à leur température de référence (-4, -2, Tref, +2, +4°C) et étudié les effets sur la survie et le développement des embryons et des larves au cours de l’ensemble de la période d’alimentation endogène. Ce travail a confirmé la loi générale de l’impact de la température sur la période d’incubation (Q10 ~3). La truite commune montre une forte diminution de sa survie lors d’une augmentation de quatre degrés, néanmoins les larves survivantes sont plus grandes et ont un contenu énergétique plus important. La survie des larves de brochet augmente avec la température, ces larves sont les plus grandes et leur contenu énergétique est plus important à la température la plus élevée. La survie de la carpe n’est pas affectée par la température ; néanmoins les larves élevées à basse température sont les plus petites et présentent un faible contenu énergétique. Les résultats de survie pour les premiers stades de vie sont en concordance avec les modélisations des aires de répartition actuelle. Dans le futur, la prise en compte de la niche thermique théorique des premiers stades de vie pourrait permettre d’affiner les prévisions des aires de répartitionAccording to the latest report of the Intergovernmental Panel on Climate Change (IPCC), global warming is expected to continue over the next century, the average temperature could increase by 0.3 ° C to 4.8 ° C with extreme values ranging from 1 ° C to 6 ° C by 2100. These temperature changes will have direct and indirect consequences on the overall biodiversity and specifically fish which are poikilotherms. In this study three species were selected taking into account their reproductive strategy and their thermal tolerance: brown trout (Salmo trutta), pike (Esox lucius) and common carp (Cyprinus carpio). We have applied for all three species the same temperature range of from their referential temperature (-4, -2, Tref °C, +2, + 4 ° C). To carry out this study, we investigated biological traits related to survival and development during the endogenous feeding period. This work confirmed the general law of the impact of temperature during incubation phase (Q10 ~ 3). For brown trout, the results show a collapse of its population with an increase of four degrees; nevertheless surviving larvae were the longest and had a more energetic content. The survival rate of pike larvae increased when temperature increased, these larvae were the longest and the had more energetic content. The survival of the carp was not affected by temperature; nevertheless, at the lowest temperature (16°C), the larvae were smaller and had a lower energetic content. The survival results for the early stages of life are an agreement with the current distribution models. In view of this study the theoretical thermal niche species of early live stage should be undertaken to continue to refine prediction models from range
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Ronteix, Gustave. „Inferring cell-cell interactions from quantitative analysis of microscopy images“. Thesis, Institut polytechnique de Paris, 2021. http://www.theses.fr/2021IPPAX111.
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Les systèmes biologiques sont bien plus que la somme de leurs constituants. En effet, ils sont souvent caractérisés par des comportements macroscopiques complexes résultant de boucles d'interactions et de rétroactions. Par exemple, la régulation et le rejet éventuel des tumeurs par le système immunitaire est le résultat de multiples réseaux de régulation, influençant à la fois le comportement des cellules cancéreuses et immunitaires. Pour simuler ces effets complexes in-vitro, j'ai conçu une puce microfluidique permettant de confronter des sphéroïdes de mélanome à de multiples cellules T et d'observer les interactions qui en résultent avec une haute résolution spatio-temporelle et sur de longues périodes de temps. En utilisant de l'analyse d'images avancée, combinée à des modèles mathématiques, je démontre qu'une boucle de rétroaction positive conduit l'accumulation de cellules T sur la tumeur, ayant pour conséquence une fragmentation accrue des sphéroïdes. Cette étude met en lumière l'initiation de la réponse immunitaire à l'échelle de la cellule unique : elle montre que même le tout premier contact entre une cellule T et un sphéroïde tumoral augmente la probabilité que la cellule T suivante arrive sur la tumeur. Elle montre également qu'il est possible de récapituler des comportements antagonistes complexes in-vitro, ce qui ouvre la voie à l'élaboration de protocoles plus sophistiqués, impliquant par exemple un micro-environnement tumoral plus complexe.De nombreux processus biologiques sont le résultat d'interactions entre de multiples types de cellules, en particulier au cours du développement. Le foie fœtal est le lieu de la maturation et de l'expansion du système hématopoïétique, mais on sait peu de choses sur sa structure et son organisation. De nouveaux protocoles expérimentaux ont été récemment mis au point pour imager cet organe et j'ai développé des outils pour interpréter et quantifier ces données, permettant la construction d'un "réseau jumeau" de chaque foie fœtal. Cette méthode permet de combiner les échelles unicellulaire et de l'organe dans une seule analyse, révélant l'accumulation de cellules myéloïdes autour des vaisseaux sanguins irriguant le foie fœtal aux derniers stades du développement de l'organe. À l'avenir, cette technique permettra d'analyser précisément les environnements de cellules d'intérêt de manière quantitative. Ceci pourrait à son tour nous aider à comprendre les étapes du développement de types cellulaires cruciaux tels que les cellules souches hématopoïétiques.Les interactions entre les bactéries et leur environnement sont essentielles pour comprendre l'émergence de comportements collectifs complexes tels que la formation de biofilms. Un mécanisme d'intérêt est celui de la rhéotaxie, par lequel le mouvement bactérien est entraîné par les gradients de la contrainte de cisaillement du fluide dans lequel les cellules se déplacent. J'ai développé une méthode pour calculer les équations semi-analytiques guidant le mouvement des bactéries dans la contrainte de cisaillement. Ces équations prédisent des comportements qui ne sont pas observés expérimentalement, mais la divergence est résolue une fois que la diffusion rotationnelle est prise en compte. Les résultats expérimentaux correspondent bien à la prédiction théorique : les bactéries dans les gouttelettes se séparent de manière asymétrique lorsqu'un cisaillement est généré dans le milieuIn his prescient article “More is different”, P. W. Anderson counters the reductionist argument by highlighting the crucial role of emergent properties in science. This is particularly true in biology, where complex macroscopic behaviours stem from communication and interaction loops between much simpler elements. As an illustration, I hereby present three different instances in which I developed and used quantitative methods in order to learn new biological processes.For instance, the regulation and eventual rejection of tumours by the immune system is the result of multiple positive and negative regulation networks, influencing both the behaviour of the cancerous and immune cells. To mimic these complex effects in-vitro, I designed a microfluidic assay to challenge melanoma tumour spheroids with multiple T cells and observe the resulting interactions with high spatiotemporal resolution over long (>24h) periods of time. Using advanced image analysis combined with mathematical modelling I demonstrate that a positive feedback loop drives T cell accumulation to the tumour site, leading to enhanced spheroid fragmentation. This study sheds light on the initiation if the immune response at the single cell scale: showing that even the very first contact between T cell and tumour spheroid increases the probability of the next T cell to come to the tumour. It also shows that it is possible to recapitulate complex antagonistic behaviours in-vitro, which paves the way for the elaboration of more sophisticated protocols, involving for example a more complex tumour micro-environment.Many biological processes are the result of complex interactions between cell types, particularly so during development. The foetal liver is the locus of the maturation and expansion of the hematopoietic system, yet little is known about its structure and organisation. New experimental protocols have been recently developed to image this organ and I developed tools to interpret and quantify these data, enabling the construction of a “network twin” of each foetal liver. This method makes it possible to combine the single-cell scale and the organ scale in the analysis, revealing the accumulation of myeloid cells around the blood vessels irrigating the foetal liver at the final stages of organ development. In the future, this technique will make it possible to analyse precisely the environmental niches of cell types of interest in a quantitative manner. This in turn could help us understand the developmental steps of crucial cell types such as hematopoietic stem cells.The interactions between bacteria and their environment is key to understanding the emergence of complex collective behaviours such a biofilm formation. One mechanism of interest is that of rheotaxis, whereby bacterial motion is driven by gradients in the shear stress of the fluid the cells are moving in. I developed a framework to calculate the semi-analytical equations guiding bacteria movement in shear stress. These equations predict behaviours that aren’t observed experimentally, but the discrepancy is solved once rotational diffusion is taken into account. Experimental results are well-fitted by the theoretical prediction: bacteria in droplets segregate asymmetrically when a shear is generated in the media.Although relating to very different topics, these three studies highlight the pertinence of quantitative approaches for understanding complex biological phenomena: biological systems are more than the sum of their constituents.a
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Tallec, Kevin. „Impacts des nanoplastiques et microplastiques sur les premiers stades de vie (gamètes, embryons, larves) de l'huître creuse Crassostrea gigas Surface functionalization determines behavior of nanoplastic solutions in model aquatic environments, in Chemosphere 225, June 2019 Nanoplastics impaired oyster free living stages, gametes and embryos, in Environmental Pollution 242 (Part B), November 2018 Constraints and priorities for conducting experimental exposures of marine organisms to microplastics, in Frontiers in Marine Science 5(252), July 2018 Cellular responses of Pacific oyster (Crassostrea gigas) gametes exposed in vitro to polystyrene nanoparticles, in Chemosphere 208, October 2018“. Thesis, Brest, 2019. http://www.theses.fr/2019BRES0103.
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Depuis 70 ans, les débris plastiques dont la fin de vie a été négligée par les sociétés humaines s’accumulent dans les océans. L’évaluation des effets engendrés par cette contamination ubiquitaire est une préoccupation majeure, notamment au regard des micro- et potentiels nanoplastiques (MNP ; < 5 mm) du fait de leur biodisponibilité pour la plupart des organismes marins. L’objectif de cette thèse était de déterminer les effets des MNP sur les jeunes stades de vie d’une espèce ingénieure des habitats côtiers, l’huître creuse Crassostrea gigas. Les impacts des MNP sur ces jeunes stades sont apparus dépendants de la taille des particules. Le rapport surface/volume important des nanosphères de polystyrène (nano-PS ; 50 nm) a favorisé les interactions avec les gamètes et embryons, induisant une inhibition de la fécondation et de l’embryogénèse tandis que les microsphères (0,5 et 2 μm) n’ont causé aucun effet phénotypique visible. La toxicité des nano-PS est apparue dépendante de leurs propriétés de surface (e.g groupements chimiques, charge) qui dirigent leur agrégation dans l’eau de mer et les interactions avec les membranes biologiques. Les nano-PS cationiques, qui restent à l’échelle nanométrique dans l’eau de mer, sont à l’origine des effets toxiques les plus marqués. L’exposition embryonnaire à une dose non létale a notamment diminué les performances larvaires et modulé la réponse de la génération suivante à une réexposition embryonnaire. Toutefois, ces effets néfastes sont observés à des concentrations numéraires supposément non-représentatives de l’environnement actuel (la quantité de NP n’étant pas caractérisée en mer à ce jour), suggérant un risque limité des micro- et nanosphères de polystyrène sur les jeunes stades de C.gigas. Les prochaines études devront tenir compte de la complexité et de la réalité des MNP environnementaux (e.g. polymères, formes, contaminants adsorbés, concentrations) sur plusieurs générations de bivalves dans le but d’appréhender plus précisément le risque pour les écosystèmes côtiersFor 70 years, mismanaged plastic waste accumulates in the oceans. Risk assessment of this contamination is a major concern, especially regarding micro- and presumably nanoplastics (MNP; <5 mm) which are bioavailable for most marine species. The objective of this thesis was to assess adverse effects of MNP to early life stages of the oyster Crassostrea gigas, a key engineer species in coastal ecosystems. MNP toxicity on oyster young stages depended on the particle size. The high surface area- to - volume ratio of polystyrene nanobeads (nano- PS; 50 nm) promoted their reactivity and interactions with biological membranes of gametes and embryos, leading to an inhibition of the fertilization and embryogenesis success while 0.5 and 2 μm polystyrene beads had any detectable effects. The nano-PS toxicity depended on the particle surface properties (e.g. surface functionalization and charge) which govern their aggregation in seawater and affinity with biological membranes. Furthermore, cationic nano- PS which remained at nanometric scale in seawater, had the highest toxic potential to oyster gametes and embryos. Embryonic exposure to these particles at a non-lethal dose reduced first generation larval performances and modulated larval growth at the second generation in response to the same embryonic exposure. All adverse effects were observed at supposedly unrealistic environmental concentrations (no in situ data exists on NP), suggesting low risk of polystyrene beads to oyster early life stages. Future studies will have to take into account the complexity and reality of MNP in oceans (e.g. polymer and shape diversity, concentrations, contaminants adsorption) to assess effects on bivalve species across generations in order to establish more accurately the risks for coastal environments
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Fauquet, Mireille. „Etude des stades precoces de la differenciation du systeme nerveux peripherique chez l'oiseau“. Paris 6, 1987. http://www.theses.fr/1987PA066162.
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Pagliaro, Sarah Beatriz De Oliveira. „Transcriptional control induced by bcr-abl and its role in leukemic stem cell heterogeneity. Single-Cell Transcriptome in Chronic Myeloid Leukemia: Pseudotime Analysis Reveals Evidence of Embryonic and Transitional Stem Cell States Single Cell Transcriptome in Chronic Myeloid Leukemia (CML): Pseudotime Analysis Reveals a Rare Population with Embryonic Stem Cell Features and Druggable Intricated Transitional Stem Cell States A novel neuronal organoid model mimicking glioblastoma (GBM) features from induced pluripotent stem cells (iPSC) Experimental and integrative analyses identify an ETS1 network downstream of BCR-ABL in chronic myeloid leukemia (CML)“. Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASQ032.
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La leucémie myéloïde chronique est une hématopoïèse maligne clonale, caractérisée par l'acquisition de la translocation t (9;22) conduisant au chromosome Ph1 et à son homologue l'oncogène BCR-ABL, dans une cellule souche hématopoïétique très primitive. La LMC est un modèle de thérapies ciblées, car il a été démontré que la preuve de la faisabilité du ciblage de l'activité tyrosine kinase (TK) BCR-ABL à l'aide d'inhibiteurs de TK (TKI) entraîne des réponses et des rémissions majeures. Cependant, les problèmes actuels rencontrés dans ces thérapies sont la résistance des cellules souches leucémiques primitives et leur persistance qui serait liée à l'hétérogénéité des cellules souches au moment du diagnostic, ce qui conduit à la sélection clonale de cellules résistant aux thérapies TKI. J'ai appliqué la technologie de l'analyse du transcriptome des cellule uniques aux cellules de la LMC en utilisant un panel de gènes impliqués dans différentes voies, combinée à l'analyse d'inférence de trajectoire au modèle d'expression des gènes. Les résultats ont montré un état transitoire des cellules souches comprenant des gènes embryonnaires identifiés dans les cellules de la LMC au moment du diagnostic, ce qui pourrait contribuer à la résistance et à la persistance de la LSC. En outre, l'oncoprotéine Bcr-Abl est la tyrosine kinase constitutivement active produite par le gène chimérique BCR-ABL dans la leucémie myéloïde chronique (LMC). Les cibles transcriptionnelles de Bcr-Abl dans les cellules leucémiques n'ont pas été étudiées de manière approfondie. Une expérience de transcriptome utilisant la lignée cellulaire UT7 hématopoïétique exprimant BCR-ABL, a identifié la surexpression du facteur d'élongation eucaryote kinase 2 (eEF2K) qui joue un rôle majeur dans la survie des cellules en cas de privation de nutriments. Dans l'ensemble, les données suggèrent que la surexpression de eEF2K dans la LMC est associée à une sensibilité accrue à la privation de nutrimentsChronic myeloid leukemia is a clonal hematopoietic malignancy, characterized by the acquisition of the t (9;22) translocation leading to Ph1 chromosome and its counterpart BCR-ABL oncogene, in a very primitive hematopoietic stem cell. CML is a model of targeted therapies as the proof of concept of the feasibility of targeting the tyrosine kinase (TK) activity BCR-ABL using TK inhibitors (TKI) has been shown to lead to major responses and remissions. However, the current problems encountered in these therapies are primitive leukemic stem cells resistance and their persistence which is thought to be related to the heterogeneity of the stem cells at diagnosis leading to clonal selection of cells resisting to TKI therapies. I have applied the technology of single cell transcriptome analysis to CML cells using a panel of genes involved in different pathways combined with trajectory inference analysis to the gene expression pattern. The results showed a transitional stem cell states including embryonic genes identified in CML cells at diagnosis which could contribute to LSC resistance and persistence. Furthermore, the oncoprotein Bcr-Abl is the constitutively active tyrosine kinase produced by the chimeric BCR-ABL gene in chronic myeloid leukemia (CML). The transcriptional targets of Bcr-Abl in leukemic cells have not been extensively studied. A transcriptome experiment using the hematopoietic UT7 cell line expressing BCR-ABL, has identified the overexpression of eukaryotic elongation factor kinase 2 (eEF2K) which plays a major role in the survival of cells upon nutrient deprivation. Overall, the data suggest that overexpression of eEF2K in CML is associated with an increased sensitivity to nutrient-deprivation
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Souchet, Jérémie. „Effets de l'hypoxie d'altitude sur le développement embryonnaire et les performances juvéniles chez la couleuvre vipérine, Natrix maura, dans le contexte actuel du changement climatique“. Thesis, Toulouse 3, 2020. http://www.theses.fr/2020TOU30179.
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Le changement climatique pourrait entrainer, d'ici 2100, une hausse de la température moyenne à la surface de la Terre de 1°C à 6.5°C par rapport à la température moyenne estimée entre 1986 et 2005. Cela est susceptible d'augmenter le risque d'extinction des espèces, de modifier leur aire de répartition, en impactant la phénologie de reproduction et de migration des organismes, entraînant un changement des schémas de biodiversité à l'échelle mondiale. Les ectothermes, dont l'ensemble des traits physiologiques et comportementaux sont dépendants des températures environnementales, vont d'autant plus être affectés par le changement climatique et devront migrer vers des zones thermiques plus favorables, comme les zones de haute altitude. Cependant, en altitude, la diminution de la pression partielle de l'air réduit la quantité d'oxygène disponible. Cette nouvelle contrainte environnementale, l'hypoxie d'altitude, pourrait limiter leurs chances de coloniser ces milieux. Cette thèse cherche à mettre en évidence les réponses physiologiques à l'hypoxie d'altitude chez la Couleuvre vipérine, Natrix maura, une colonisatrice historique qui subit une expansion de gamme vers le haut, et à définir sa capacité à utiliser les espaces montagnards comme refuge face au changement climatique. Les objectifs sont, d'abord mesurer les effets de l'hypoxie d'altitude et de l'interaction qu'elle peut avoir avec la température sur le développement par l'intermédiaire du suivi de l'activité métabolique embryonnaire et des taux de développement. Puis, d'observer la persistance potentielle de ces effets sur les performances et le métabolisme des juvéniles. Les résultats de ces travaux suggèrent que, chez la Couleuvre vipérine, les réponses physiologiques plastiques des embryons à l'hypoxie de haute-altitude pourraient faciliter l'expansion de l'aire de répartition altitudinale à travers le maintien des phénotypes corporels et des performances physiques des juvénilesBy 2100, climate change could lead to an increase in the average temperature on the Earth's surface of 1°C to 6.5°C compared to the average temperature estimated between 1986 and 2005. This is likely to increase the risk of species extinction or change species ranges by impacting the reproductive phenology and the migration of organisms, leading to a change in biodiversity patterns on a global level. Ectotherms, whose set of physiological and behavioural traits are dependent on environmental temperatures, will be further affected by climate change and will have to migrate to more favourable thermal zones, such as to high altitude. However, at higher altitudes, the decrease in the partial pressure of the air reduces the availability of oxygen. This new environmental constraint, high-elevation hypoxia, could limit organisms' chances of colonizing these environments. This thesis seeks to highlight the physiological responses to high-elevation hypoxia in the Viperine snake, Natrix maura, a historical colonizer currently undergoing an upward range expansion, and to define its capacity to use mountain areas as a refuge in the context of climate change. The objectives are, in the first instance, to measure the effects of high-elevation hypoxia and the interaction it may have with temperature on development through monitoring embryonic metabolic activity and development rates. The second objective is to observe the potential persistence of these effects on the performance and metabolism of juveniles. The results of this work suggest that, in the Viperine Snake, the plastic physiological responses of embryos to high-elevation hypoxia could facilitate the expansion of the altitudinal range through the maintenance of body phenotypes and physical performance of juveniles
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Weeks, Santos Shannon. „Étude des réponses adaptatives et délétères des premiers stades du développement de truite arc-en-ciel, Oncorhynchus mykiss, exposés à des produits phytosanitaires utilisés en viticulture“. Thesis, Bordeaux, 2019. http://www.theses.fr/2019BORD0003.
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L’utilisation excessive de pesticides engendre des pollutions et des dégradations importantes de l’environnement y compris sur les écosystèmes aquatiques. L’activité viticole ne fait pas exception à cette règle, et c’est pour cette raison que ce travail de thèse s’est intéressé aux réponses adaptatives ou délétères aux premiers stades de vie de poissons exposés à trois produits phytosanitaires utilisés en viticulture ainsi qu’à leur mélange et à des échantillons environnementaux. La thèse s’intéresse aux stades précoces de développement de la truite arc-en-ciel, mais également à la lignée cellulaire de foie de truite RTL-W1. Les embryons de truite ont été exposés au cuivre, au glyphosate et au chlorpyrifos seuls ou en mélange. Une autre partie de ce travail a consisté à étudier les effets toxiques des échantillons environnementaux d’eau et de sédiment provenant d’un cours d’eau, La Livenne, à proximité de parcelles viticoles. Toutes les expériences ont été faites en conditions contrôlées de laboratoire. Les réponses induites par ces expositions ont été mesurées à différents niveaux d’organisation biologique : au niveau moléculaire, phénotypique et comportemental pour l’étude in vivo (larves de la truite arc-en-ciel) ; et l’analyse des effets cytotoxiques de l’induction des espèces réactives de l’oxygène (ROS) et des dommages à l’ADN pour l’étude in vitro (lignée RTL-W1). Les résultats de ce travail ont montré que l’exposition aux pesticides individuels, ou en mélange, chez les larves de truites arc-en-ciel n’a pas produit d’effets létaux aux concentrations testés. En revanche, ces substances ont provoqués différents effets sub-létaux, selon le composé et les concentrations étudiés, dont des effets tératogènes, des perturbations du comportement natatoire, des effets génotoxiques et l’expression différentielle de gènes cibles. Le cuivre s’est avéré le plus toxique provoquant un échec d’éclosion important. Des effets cytotoxiques et une production d’espèces réactives de l’oxygène (ERO) ont été observés sur cellules de truite exposées à des extraits d’eau de rivière. Par ailleurs, des effets comportementaux ont été observés sur les larves de truites exposées pendant 48 h à des sédiments et de l’eau de la Livenne. En conclusion, ces travaux de thèse ont mis en évidence des effets sub-létaux sur les cellules et les stades précoces de développement de truite arc-en-ciel exposés à des concentrations environnementales de pesticides utilisés en viticultureThe excessive use of pesticides generates significant pollution and degradation of the environment, including aquatic ecosystems. The viticultural activity is not an exception for this rule, and this is why the aim of this work is to study the adaptive or deleterious responses in the early life stages of fish exposed to three phytosanitary products used in viticulture as well as to their mixture and environmental samples. The thesis focuses on the early stages of development of rainbow trout, but also on the trout liver cell line RTL-W1. Trout embryos were exposed to copper, glyphosate and chlorpyrifos alone or as a mixture. Another part of this work consisted in studying the toxic effects of environmental samples of water and sediment coming from a river, La Livenne, close to vineyard plots. All experiments were done under controlled laboratory conditions. The responses induced by these exposures were measured at different levels of biological organization: at the molecular, phenotypic and behavioral level for the in vivo study (rainbow trout larvae); and the analysis of cytotoxic effects and induction of reactive oxygen species (ROS) and DNA damage for the in vitro study (RTL-W1 line). The results of this work showed that exposure to individual or mixed pesticides in rainbow trout larvae did not produce lethal effects at the tested concentrations. In contrast, these substances caused different sub-lethal effects, depending on the compound and concentrations studied, including teratogenic effects, swim behavior disturbances, genotoxic effects, and differential expression of target genes. Copper was found to be the most toxic causing a major hatching failure. Cytotoxic effects and production of reactive oxygen species (ROS) were observed on trout cells exposed to river water extracts. In addition, behavioral effects were observed on trout larvae exposed for 48 h to sediments and Livenne water. In conclusion, these thesis studies revealed sub-lethal effects on cells and early stages of development of rainbow trout exposed to environmental concentrations of pesticides
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Hennequin-Marot, Elisabeth. „Utilisation des réactions nucléaires (neutron, α) et (neutron, proton) pour la détection d'isotopes stables en biologie“. Rouen, 1986. http://www.theses.fr/1986ROUES023.
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Exemple de l'application en biologie des détecteurs solides de traces: localisation quantitative de la réaction nucléaire 6 lithium (neutron, alpha) 3 hydrogène dans l'étude du transfert placentaire du lithium, au cours du développement embryonnaire de la souris. Recherche des conditions d'obtention de détecteurs à bas mouvement propre dans le but d'appliquer la technique à la détection d'autres éléments tels que l'azote et l'oxygène
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Bassalert, Cécilia. „Influence des voies de signalisation IGF et MAPK sur la spécification des lignages de l'embryon de souris préimplantatoire“. Thesis, Université Clermont Auvergne (2017-2020), 2018. http://www.theses.fr/2018CLFAC029.
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Au cours de la préimplantation, l'embryon de souris produit deux lignages cellulaires, le trophectoderme (TE), et la masse cellulaire interne (MCI) qui elle-même se différencie en épiblaste (Epi) et en endoderme primitif (EPr), caractérisés respectivement par l'expression exclusive de Nanog et de Gata6. La voie FGF/MAPK joue un rôle critique dans l’acquisition de l’identité EPr. J’ai examiné l’expression de pERK, DUSP4 et ETV5 qui permettent de visualiser l'activité des MAPK. Ces analyses ont été effectuées en activant ou inhibant la voie FGF/MAPK, ainsi que dans des embryons mutants pour Nanog et/ou Gata6. Ceci a permis d’observer l’activation de la voie FGF/MAPK dès E3,25. Un autre volet de mon travail a été d'analyser la voie de l’IGF dans les embryons préimplantatoires afin de comprendre l’influence de cette voie dans les différents lignages. J’ai montré que le récepteur activé pIGF1R est exprimé de manière différentielle dans le TE, l’EPr et l’Epi au cours du développement. Une supplémentation d’IGF1 induit une augmentation du nombre de cellules en deux phases, d'abord de l’Epi puis de l’EPr. A l’inverse, une perte de fonction d’IGF1R induit une diminution du nombre de cellules entre E3,75 et E4,25During preimplantation, mouse embryo produces two cellular lineages, the trophectoderm (TE), and the inner cell mass (ICM), which differentiates in epiblast (Epi) and primitive endoderm (PrE), characterized respectively by the complementary expression of Nanog and Gata6. FGF/MAPK pathway plays a critical role in the acquisition of a PrE identity. I examined the expression of the markers of MAPK activity pERK, DUSP4 and ETV5. The analyze was performed with activation or inhibition of FGF/MAPK pathway and in mutant embryos for Nanog or Gata6. This showed that FGF/MAPK pathway is activated as soon as E3,25. I have also analyzed the IGF pathway in preimplantation embryos in order to understand the role of this pathway in embryonic lineages. I showed that active receptor pIGF1R is differentially expressed in TE, PrE and Epi during embryonic development. Supplementation with IGF1 induces an increase in cell number in two phases, first in Epi then in PrE. Conversely, loss of function of IGF1R induces a decrease in cell number between E3,75 and E4,25
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Hubaud, Alexis. „Dynamique de la signalisation cellulaire au cours de la segmentation des Vertébrés“. Thesis, Strasbourg, 2016. http://www.theses.fr/2016STRAJ101/document.
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La segmentation de l’axe antéro-postérieur en somites est une caractéristique majeure des Vertébrés. Ce processus est basé sur un oscillateur, l’« horloge de segmentation ». Cette thèse cherche à comprendre la dynamique de signalisation régulant ce processus. Nous avons étudié la régulation transcriptionnelle de Mesp2 et nous avons montré que Tbx6 contrôle son expression chez le poulet. Nous présentons également un système d’étude ex vivo présentant des oscillations stables du gène cyclique Lfng. Nous avons mis en évidence un effet de population régulant la génération de ces oscillations et reposant sur la voie Notch et des facteurs mécaniques que nous interprétons avec un modèle d’oscillateur excitable. De plus, nous avons démontré un effet dose-dépendant de la voie Fgf sur la différenciation cellulaire, remettant ainsi en question le modèle actuel de segmentation. Par ailleurs, ce système d’étude nous a permis d’identifier un rôle du taux de traduction dans le contrôle de la période de l’horloge. Enfin, nous présentons des travaux, où nous cherchons à reconstituer l’horloge de segmentation in vitro à partir de cellules souches murines différenciéesThe segmentation of the anteroposterior axis in somites is a major feature of Vertebrates. This process relies on an oscillator, the “segmentation clock”. The present thesis addresses the signaling dynamics regulating this process. We studied the transcriptional regulation of Mesp2 and showed that Tbx6 controls its expression in chicken. We established an ex vivo experimental system with stable oscillations of the cyclic gene Lfng. We demonstrated the existence of a population behavior that controls the generation of oscillations and involves the Notch pathway and mechanical factors. We interpreted these observations in the framework of an excitable oscillator. Moreover, we evidenced a dose-dependent effect of Fgf signaling on cell determination that challenges current models of segmentation. Furthermore, this experimental system has enabled us to identify a role of the translation rate on the clock period. Last, we showed ongoing work aiming to recapitulate the segmentation in vitro using differentiated mouse embryonic stem cells
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Delage, Nicolas. „Etude expérimentale des effets des conditions environnementales (température, oxygène, polluants) sur la survie, le développement et le comportement des stades embryo-larvaires d'esturgeon européen, Acipenser sturio“. Thesis, Bordeaux, 2015. http://www.theses.fr/2015BORD0115/document.
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L'esturgeon européen Acipenser sturio est un poisson migrateur amphihalin qui a connu un fort déclin au cours du 20ème siècle. La dernière population vit dans le bassin Gironde-Garonne-Dordogne (GGD) et sa dernière reproduction connue date de 1994. Les individus relachés lors de repeuplements sont supposés venir se reproduire prochainement. Du fait du changement global et de l'évolution des activités humaines, une meilleure connaissance de la vulnérabilité des jeunes stades de A. sturio vis-à-vis de la température, de la disponibilité en oxygène et des polluants s'est avérée nécessaire. La sensibilité aux conditions oxythermiques actuelles et à venir a été évaluée ainsi que la qualité des sédiments des frayères. Enfin, la sensibilité des jeunes stades de cette espèce à des mélanges de polluants représentatifs du bassin GGD a été également évaluée. Une forte sensibilité des jeunes stades de A. sturio au taux d'oxygène a été mise en évidence. Les fenêtres optimales et critiques de tolérance ont été estimées. La toxicité des sédiments de frayères de Dordogne est globalement supérieur à celle des sédiments de frayères de Garonne. Beauregard et Pessac-sur-Dordogne semblent être respectivement les sites les plus favorables et défavorables aux jeunes stades. La sensibilité de A. sturio aux polluants rencontrés dans le bassin est relativement faible. Les conditions environnementales actuelles du bassin GGD semblent globalement satisfaisantes pour accueillir le développement de jeunes stades de A. sturio. Les données collectées dans cette étude pourront servir pour d'autres programmes de réintroduction de cette espèceThe European sturgeon Acipenser sturio is a diadromous species which has exibited a drastic decline during the 20th century. Its last population lives in the Gironde-Garonne-Dordogne (GGD) catchment where the last documented reproduction occured in 1994. Individuals released in the context of restocking actions are expected to re-enter the system for reproduction in the next few years. Because of global changes and human activity evolution, environmental conditions have changed from the last reproduction. Improved knowledge on the sensitivity of the European sturgeon to temperature, dissolved oxygen and pollutant is required to evaluate its capacities to recolonize the GGD catchment. Sentivity to present and future, considering global changes, oxygen and temperature conditions were evaluated as well as quality of the substratum of potential spawning grounds. The sensitivity of the early stages toward a mix of pollutants found in the GGD catchment was evaluated. Results obtained show a high sensitivity of the young stages of this species to oxygen concentration. Thermal optimum, optimal and critical tolerance windows were determined. Sensitivity to pollutants mixtures found in the GGD was relatively low. Dordogne river substratum was globally more toxic than Garonne river substratum. Beauregard and Pessac-sur-Dordogne were tested respectively as the best and the worst potential spawning ground for the development of the European sturgeon early stages according to their toxicological effects. Current conditions in the GGD catchment seems to be sustainable for European sturgeon early stages. Data from this study would be useful for further restocking programs in the historical european sturgeon reproduction area
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Perez, Romero Carmina Angelica. „Noise and robustness downstream of a morphogen gradient : Quantitative approach by imaging transcription dynamics in living embryos“. Electronic Thesis or Diss., Sorbonne université, 2019. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2019SORUS306.pdf.
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La différenciation des cellules est souvent déclenchée par les gradients de molécules appelées morphogènes. Un paradigme simple pour l’étude des morphogènes est le gradient de Bicoid, qui détermine l’identité cellulaire le long de l’axe antéro-postérieur chez la mouche du vinaigre. Ce facteur de transcription permet l'expression rapide de son principal gène cible, hunchback, dans la moitié antérieure de l’embryon dans un domaine d’expression avec une bordure très franche. En utilisant le système MS2 rendant fluorescents des ARN dans les embryons vivants, nous avons montré que la transcription au promoteur d’hunchback est « bursty ». De manière surprenante, il suffit de 3 minutes, après la première détection de transcription à l’antérieur, pour que la bordure franche du domaine d’expression soit précisément positionnée au milieu de l’embryon. Afin de mieux comprendre le rôle des facteurs de transcription autres que Bicoid dans ce processus, j’ai utilisé une double stratégie impliquant des gènes rapporteurs MS2 synthétiques combinés à l’analyse du gène rapporteur hunchback MS2 dans des contextes génétiques mutants. L’analyse des gènes rapporteurs synthétiques indique que Bicoid est capable d’activer la transcription à elle seule en se fixant sur le promoteur mais de manière stochastique. La fixation d’Hunchback sur un promoteur régulé par Bicoid réduit cette stochasticité alors que Caudal agirait comme un gradient postérieur répresseur. L’ensemble de ces travaux apporte un éclairage nouveau sur les mécanismes assurant une réponse transcriptionnelle précise en aval du morphogène BicoidDuring development, cell differentiation frequently occurs upon signaling from gradients of molecules, called morphogens. A simple paradigm to study morphogens is the Bicoid gradient, which determines antero-posterior patterning in fruit fly embryos. This transcription factor allows the rapid expression of its major target gene hunchback, in an anterior domain with a sharp boundary. Using the MS2 system to fluorescently tag RNA in living embryos, we were able to show that the ongoing transcription process at the hunchback promoter is bursty Surprisingly, it takes only 3 minutes, from the first hints of transcription at the anterior to reach steady state with the setting of the sharp expression border in the middle of the embryo. To better understand the role of transcription factors other than Bicoid in this process, I used a two-pronged strategy involving synthetic MS2 reporters combined with the analysis of the hunchback MS2 reporter in various mutant backgrounds. The synthetic reporter approach, indicate that Bicoid is able to activate transcription on its own when bound to the promoter but in a stochastic manner. The binding of Hunchback to the Bicoid-dependent promoter reduces this stochasticity while Caudal might act as a posterior repressor gradient. Altogether, this work provide a new light on the mechanisms insuring a precise transcriptional response downstream of Bicoid
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Oblette, Antoine. „Spermatogenèse in vitro chez la souris : impact sur la qualité nucléaire du spermatozoïde, sur le développement et l'épigénétique de l'embryon issu d'ICSI“. Thesis, Normandie, 2019. http://www.theses.fr/2019NORMR004.
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Depuis quelques années, une biopsie testiculaire suivie d’une congélation du tissu testiculaire est proposée aux enfants atteints de cancer avant introduction d’un traitement gonadotoxique. Cette procédure de préservation de la fertilité est proposée avec l’espoir qu’une méthode de restauration de la fertilité soit développée. Le tissu testiculaire décongelé pourrait ainsi être utilisé afin d’effectuer une maturation in vitro, évitant la réintroduction de cellules tumorales, pour produire des spermatozoïdes. Ce travail de thèse a consisté, dans un premier temps, à évaluer la mise en place de la méthylation de l’ADN au sein du tissu testiculaire prépubère de souris au cours de la spermatogenèse in vitro. La culture de tissu testiculaire frais ou décongelé de souris prépubère permet le maintien des niveaux d’expression des ADN méthyltransférases 1 et 3a dans les spermatogonies et les spermatocytes. De plus, la méthylation de l’ADN est retrouvée jusque dans les spermatozoïdes produits in vitro. Par la suite, la qualité nucléaire des spermatozoïdes ainsi obtenus a été analysée. La culture de tissu testiculaire n’a pas d’impact sur le taux d’aneuploïdie, la condensation de la chromatine et la fragmentation de l’ADN spermatique. Cependant, la congélation suivie par la culture organotypique augmente la proportion de spermatozoïdes avec un ADN oxydé. Enfin, la fonctionnalité des spermatozoïdes produits in vitro a été analysée par micro-injection ovocytaire et la dynamique de différentes marques épigénétiques a été étudiée au cours du développement préimplantatoire. Les taux de développement embryonnaire sont diminués par l’utilisation de spermatozoïdes produits in vitro. Les niveaux des histones H3K4me3, H3K27me3 et H3K9ac sont peu modifiés dans les embryons issus de spermatozoïdes générés in vitro alors que la méthylation et déméthylation de l’ADN sont plus impactées. La production de spermatozoïdes après culture de tissu prépubère frais ou décongelé dans le modèle murin a permis de mettre en évidence que cette procédure n’est pas sans impact sur l’embryon précoce bien que la qualité des spermatozoïdes produits soit peu altéréeIn recent years, testicular biopsy followed by the freezing of testicular tissue has been proposed to children with cancer before the introduction of a gonadotoxic treatment. This fertility preservation procedure is offered with the hope that a fertility restoration method will be developed. The thawed testicular tissue could thus be used to perform in vitro maturation, avoiding the reintroduction of tumor cells, to produce spermatozoa. This thesis work first consisted in assessing the establishment of DNA methylation in mouse prepubertal testicular tissue during in vitro spermatogenesis. The culture of fresh or thawed mouse testicular testicular tissue allows the expression levels of DNA methyltransferases 1 and 3a to be maintained in spermatogonia and spermatocytes. In addition, DNA methylation is found even in in vitro produced spermatozoa. The nuclear quality of these spermatozoa was then analyzed. The culture of testicular tissue has no impact on sperm aneuploidy rate, chromatin condensation and DNA fragmentation. However, freezing followed by organotypic culture increases the proportion of spermatozoa with oxidized DNA. Finally, the functionality of in vitro produced spermatozoa was analyzed by oocyte microinjection and the dynamics of different epigenetic marks was studied during preimplantation development. Embryo developmental rates are decreased when using in vitro produced spermatozoa. The levels of H3K4me3, H3K27me3 and H3K9ac are slightly modified in embryos derived from spermatozoa generated in vitro whereas DNA methylation and demethylation are more affected. The production of spermatozoa after culture of fresh or thawed prepubertal tissue in the mouse model has shown that this procedure is not without impact on the early embryo, although the quality of the spermatozoa produced is relatively unaltered
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Da, Silva Mylène. „Les liquides amniotique et allantoïque de l'oeuf de poule : caractérisation et rôles dans la protection de l'embryon au cours du développement“. Thesis, Tours, 2017. http://www.theses.fr/2017TOUR4048.
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Avec le développement concomitant de l’embryon et des structures extra-embryonnaires, les défenses initiales de l’œuf de poule s’altèrent, ce qui suggère la mise en place de systèmes relais pour protéger l’embryon jusqu’à son éclosion. Pour comprendre le rôle des fluides extra-embryonnaires dans cette fonction, nous avons analysé la composition et les propriétés biochimiques et antibactériennes des fluides amniotique et allantoïque de l’œuf. Comme chez l’humain, le fluide amniotique chez la poule protège l’embryon contre les agressions physiques et microbiennes. De plus, nous avons démontré que le transfert des molécules antibactériennes du blanc au 12ème jour d’incubation augmente son potentiel antibactérien, assurant ainsi une protection de l’embryon jusqu’à l’éclosion, et probablement après, dans son tractus digestif, après l’ingestion du fluide amniotique. Les spécificités phylogénétiques de certaines des protéines identifiées suggèrent un processus d’adaptation des oiseaux à la flore microbienne terrestre. Pour le fluide allantoïque en revanche, nous n’avons pas pu confirmer son rôle antibactérien, mais nous avons mis en évidence la présence de protéases actives qui pourraient contribuer à la digestion et au recyclage des déchets métaboliques de l’embryonConcomitantly with the development of the embryo and extra-embryonic structures, initial chicken egg defenses are progressively altered, which suggests that alternative mechanisms appear to protect the embryo until hatching. To better understand the role of extra-embryonic fluids in the chicken egg defense during incubation, we analyzed the biochemical composition and antibacterial properties of the chicken amniotic and allantoic fluids. As for humans, the chicken amniotic fluid protects the embryo against mechanical shocks and microbial infections. Moreover, at the 12th day of incubation, the transfer of antibacterial molecules from the egg white increases the antibacterial potential of the chicken amniotic fluid, thus protecting the embryo until hatching, and probably after, all along its digestive tract, after oral absorption of the amniotic fluid. Some of these antibacterial proteins are specific to oviparous species and/or birds, which highlights the processes of evolution and adaptation of birds to their terrestrial environment. On the other hand, the antibacterial potential of the allantoic fluid still needs to be explored, but our study demonstrated the presence of active proteases, which could contribute to the digestion and recycling of embryonic metabolic wastes
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BAUD, CHRISTIANE. „Contribution a l'etude des permeabilites ioniques membranaires de l'oeuf a la blastula, par les techniques electrophysiologiques“. Paris 6, 1987. http://www.theses.fr/1987PA066252.
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Didelot, Gallois Dominique. „Organogenèse et différenciation des glandes annexes males du criquet migrateur : Locusta migratoria migratorioides (R et F)“. Paris 6, 1986. http://www.theses.fr/1986PA066394.
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Lebrun, Diane. „Caractérisation et généralisation de l’implication de la voie NOTCH cytoplasmique au cours des processus de transition épithélio-mésenchymateuse chez l’embryon de poulet“. Thesis, Lyon, 2018. http://www.theses.fr/2018LYSE1092/document.
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La transition épithélio-mésenchymateuse (EMT) est un processus incontournable dans de nombreux contextes normaux et pathologiques, tels que gastrulation, organogenèse, fibroses et cancers. Cette transformation de cellule épithéliale en cellule mésenchymateuse est indissociable de l'acquisition de propriétés migratoires et est généralement associée à un changement de destin cellulaire. Différentes voies moléculaires sont impliquées selon le contexte de l'EMT concernée. Récemment, notre laboratoire a mis en évidence que la voie Notch cytoplasmique contrôle l'EMT des cellules de la lèvre dorso-médiale du somite (DML). Les crêtes neurales exprimant DLL1 activent « en passant » le récepteur NOTCH, liberant ainsi le domaine intra-cytoplasmique de NOTCH (NICD). Dans le cytoplasme, NICD inhibe la kinase GSK3ß, conduisant à la stabilisation de SNAIL, un gène maître de la transition épithélio-mésenchymateuse. Il en résulte une libération de la βcaténine des jonctions adhérentes qui, après translocation dans le noyau, active la transcription des gènes de la myogénèse (Myf5). Ainsi, l'activation de la voie Notch cytoplasmique permet une induction concomitante de l'EMT et de la myogénèse. La fonction cytoplasmique de Notch reste controversée et le mécanisme par lequel NICD inhibe GSK3ß reste obscur. Au cours de ma thèse j'ai cherché à élucider le mécanisme par lequel NICD inhibe l'activité kinase de GSK3ß. J'ai confirmé l'interaction de GSK3ß et de NICD en démontrant leur interaction via CoIP. Après avoir démontré l'implication de la sérine-thréonie kinase AKT dans la myogenèse des cellules de la DML, j'ai mis en évidence, via CoIP et électroporation, que l'inhibition GSK3ß par NICD est très certainement médiée par AKT, connue pour être impliquée dans l'EMT et inhiber GSK3ß par phosphorylation. En comparant le NICD1 de poulet et les 4 NICD de souris, j'ai montré que l'expression exogène de ces 5 molécules induit l'EMT et la différenciation myogénique de manière similaire. J'ai aussi montré que parmi des différents domaines de NICD, le domaine RAM, connu pour se lier à l'ADN (via RBPJ), est nécessaire et suffisant à l'inhibition de GSK3ß. Un second axe de ma thèse a été de tester l'implication de la voie Notch cytoplasmique dans d'autres contextes d'EMT. Pour ce faire, j'ai mis en évidence que cette voie est impliquée dans les autres lèvres du dermomyotome mais aussi dans les crêtes neurales qui délaminent du toit du tube neural. J'ai en particulier mis en évidence une co-activation des voies Wnt et Notch, une inhibition de la kinase GSK3ß par NICD cytoplasmique ainsi qu'une inhibition de la différenciation en présence d'une ß-caténine mutée, retenue à la membrane, ou en présence d'une molécule SNAIL2 dominant-négative. Le dernier axe de ma thèse a consisté à élucider le mécanisme de régulation de l'induction de l'EMT et de la myogenèse via l'activation de NICD. Il a été mis en évidence que toutes les cellules de la DML peuvent être activées via DLL1 et que la surexpression massive de NICD dans la DML provoque une différenciation massive et une déplétion du groupe de cellules progénitrices. Afin de déterminer si la régulation de cette initiation se fait avant ou après induction de NICD, j'ai créé un plasmide permettant de répondre à cette question et afin de visualiser son expression in vivo, j'ai initié une collaboration avec une équipe de l'ILM afin de créer un microscope vertical SPIM biphoton permettant l'observation d'embryon de poulets vivants [etc...]The epithelio-mesenchymal transition (EMT) is a well-known mechanism by which epithelial cells lose their adherent connections and gain migratory properties, associated with a gain of a mesenchymal phenotype. This EMT is required in numerous processes as gastrulation, organogenesis, fibrosis and cancers. Various molecular pathways orchestrate the EMT depending on the EMT biological context. Recently, our laboratory highlighted the implication of the cytoplasmic Notch pathway in the dorso-medial lip (DML) EMT. In the DML tissue, theEMT is synchronized with differentiation pathways, to generate cells forming the primary myotome. Our laboratory showed that neural crests cells expressing DLL1 activate NOTCH receptor of the DML cells, via a “kiss and run” model. This leads to NOTCH cleavage, releasing an activated intra-cytoplasmic NOTCH domain (NICD). In the cytoplasm, NICD inhibits the GSK3ß kinase, leading to the stabilization of SNAIL and the free cytoplasmic ßcatenin. These molecules translocate into the nucleus and lead to the activation of MRF as Myf5 (ß-catenin) and to the repression of adherent genes (SNAIL). Therefore, Notch cytoplasmic pathway allows a synergized induction of both, the EMT and myogenic programs. This pathway remains controversial and the precise mechanism how NICD inhibits GSK3ß needs to be elucidated. Therefore, the aim of my thesis project was to clarify how NICD inhibits GSK3ß activity. First, I confirmed that NICD and GSK3ß physically interact by CoIP. Moreover, I demonstrated that the serin-threonin kinase AKT, known to inhibit GSK3ß by phosphorylation and also to mediate EMT in cancer, can physically interact with NICD in the cytoplasm. I have also shown that AKT mediates the induction of the myogenic program through the inhibitory phosphorylation of GSK3ß and that SNAIL is downstream of AKT. Together, these experiments indicate that AKT mediates, through phosphorylation, the cytoplasmic NICD inhibition of GSK3ß leading to myogenesis. A comparison of the chicken NICD1 and the 4 isoforms of mouse NICD highlighted that these 5 proteins induce EMT and myogenesis similarly. The dissection of the different conserved domains in the 5 different NICD proteins demonstrated that the RAM domain, known to activate transcription by binding to RBPJ, is necessary and sufficient for GSK3ß inhibition. A second axis of the thesis has been to test the involvment of the cytoplasmic Notch pathway in other EMT contexts. First, I highlighted that this pathway induces myogenesis, showing that NICD inhibits GSK3ß activity in the ventro-lateral lip. I further demonstrated that the cytoplasmic Notch pathway is implicated in the EMT and differentiation of the neural crests cells delaminating from the dorsal neural tube. Particularly, I have shown a co-activation of the Wnt and Notch pathway in premigratory and migratory neural crests. Moreover, I demonstrated a cytoplasmic inhibition of the kinase activity of GSK3ß by NICD, as well as the induction of the differentiation by cytoplasmic ß-catenin or SNAIL2. In a third axis of my thesis, I tried to clarify the regulatory mechanism involved in Notch activation. Previously it has been demonstrated that in all the DML cells Notch can be activated by an overexpression of DLL1 and that an ectopic expression of NICD in the DML cells induce a massive differentiation and depletion of the progenitor pool. To determine if the regulation of this initiation of the myogenic program occurs before or after Notch activation, I designed a plasmid to visualize Notch activation in vivo. In order to be able to follow the DLM cells and Notch activation in vivo, I initiated a collaboration with an ILM team to create a vertical SPIM biphoton microscope. In the future, this microscope will allow us to follow cells in living chicken embryos [etc...]
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Yeoh, Choo-Guan. „The effects of hormones on development of embryonic and post embryonic salmonids, and hormone metabolism during these stages“. Thesis, 1993. http://hdl.handle.net/1957/36163.
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The importance of hormone reservoirs in mature teleost eggs is
unknown. To elucidate the effects of hormones on embryonic development,
steelhead trout eggs, Oncorhynchus mykiss, were immersed in either cortisol,
testosterone, or thyroxine at two different stages of development. Elevated
concentrations of cortisol were detectable in the trout eggs or embryos after
immersion. Eggs exposed to cortisol during water hardening hatched faster
than eggs exposed at the eyed stage. Eggs that hatched faster had elevated
cortisol and cortisol glucuronide concentrations at hatch compared to groups
immersed at eyed or control groups. The dedine of these elevated
concentrations of cortisol and cortisol glucuronide during embryonic
development suggest conversion, clearance or both. Eggs exposed to cortisol
at the earlier developmental stage did not appear to clear or convert cortisol
as efficiently as those exposed at a later stage. Testosterone did not
accelerate hatching in steelhead trout. Thyroxine accelerated hatching in
eggs immersed at the eyed stages but had no effect when given at water
hardening. These eggs that hatched faster were more synchronous in
hatching time compared to other groups. Prior to exogenous feeding (50
days post fertilization, dpf), animals immersed in cortisol when eye pigments
had higher mean condition factor (Kn) than other experimental or control
groups, but this effect was gone by 83 dpf. However, at 130 dpf, cortisol
groups that were immersed at the eyed stage were again heavier, longer, and
more robust than other groups. At 50 dpf, animals immersed in thyroxine at
water hardening were significantly longer and less robust (smaller condition
factor, Kn). These effects disappeared by 83 dpf.Graduation date: 1993
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Ting, Hao, und 丁豪. „Characterization of zebrafish syndecan-4 gene function during the embryonic developmental stages“. Thesis, 2009. http://ndltd.ncl.edu.tw/handle/45051937120875311445.
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碩士臺北醫學大學
醫學科學研究所
97
Syndecans are a family of transmembrane proteoglycans that are known to modulate a large number of signaling pathway through the interaction with ECM (extracellular matrix) or growth factor and to regulate a great diversity of biological function. Glycosaminoglycan chains of syndecan-4 is responsible for focal adhesion formation in response to ECM coordinated integrin. Results of in vitro experiments suggest that syndecan-4 also modulate cell spreading and migration through NXIP motif of ectodomain. Syndecan-4 signaling and its role in cell adhesion is understood in mammalian cell culture systems. However, little is understood in terms of its role in development. Recently research suggested that syndecan-4 seems to play an important role in organism development. Evidence reveals syndecan-4 is involved in the signaling regulate neural induction and neural crest cells migration during early embryo development. In this study, we aim to unravel the role of syndecan-4 in zebrafish embryo development. Overexpression of syndecan-4 seems to have little defect in morphology, however, overexpression of functional motif-deleted form of syndecan-4 resulted in abnormal muscle distribution and variation of cardiovascular development. The embryo overexpressed normal or mutant form of syndecan-4 also shows the defect of lateral line system in neuraomasts. Taken together, these results suggest that syndecan-4 plays an important role in several types of cells during zebrafish development.
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You, Pei-Jyun, und 游培鈞. „Characterization of zebrafish DnaJA3a and DnaJA3b gene functions during the embryonic developmental stages“. Thesis, 2010. http://ndltd.ncl.edu.tw/handle/34810609838705162840.
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碩士臺北醫學大學
醫學科學研究所
98
The Drosophila lethal tumourous imaginal disc gene, Tid56, has been classified as a tumor suppressor gene. Tid1, the human homologue of the Drosophila Tid56 gene, encodes two alternative splicing isoforms (Tid1 long form and short form). Tid1 belongs to DnaJA3 protein is the member of DnaJ family and act as co-chaperones interact with the Hsp70 chaperone by DnaJ domain. The zebrafish homologue of the hTid1 genes were DnaJA3a and DnaJA3b. By whole mount in situ hybridization and RT-PCR, the expression of DnaJA3a mRNA was ubiquitously during the developmental stages and adult tissues, the expression of DnaJA3b mRNA was mainly at 72hpf during the developmental stages and adult brain and muscle. To investigate the effect of DnaJA3a and DnaJA3b proteins during developmental stage, we constructed the plasmids that expressed the (wild type and DnaJ-domain mutant forms) of DnaJA3a and DnaJA3b proteins. Our result showed that overexpression of wild type DnaJA3a and mutant form DnaJ3b in early zebrafish embryo had sever defect in morphogenesis, but not wild type DnaJ3b. In this study, we demonstrates that the zebrafish homologue of the hTid1 genes (DnaJA3a and DnaJA3b) were required for morphogenesis in zebrafish embryo.
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程偉政. „Molecular characterization of Obox6, a novel homeobox gene preferentially expressed in early embryonic stages“. Thesis, 2003. http://ndltd.ncl.edu.tw/handle/73035383892412544963.
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Vieira, Raquel Susana Fernandes. „Effects of synthetic and plant-based fungicides on biomarkers in the early stages of zebrafish development“. Master's thesis, 2018. http://hdl.handle.net/10348/9070.
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Original Dissertation for the purpose of obtaining a Master's Degree in Biochemistry at the University of Trás-os-Montes and Alto DouroA produção agrícola é frequentemente afetada pelas condições ambientais inerentes às mudanças climatéricas. Esta situação acarreta o aumento da utilização de pesticidas, como é o exemplo de fungicidas para controlar o míldio e oídio na vitivinicultura. Neste sentido, a utilização dos fungicidas têm sido associados ao aparecimento dos seus resíduos no solo e lençóis de água com possíveis efeitos tóxicos nos ecossistemas. Contudo, o estudo e o conhecimento toxicológico acerca dos resíduos e efeitos destes compostos são limitados ou inexistentes. Assim este trabalho teve como objetivo avaliar a toxicidade de fungicidas sintéticos (azoxistrobina, tebuconazole e mancozeb) e de compostos de origem natural (extrato de Mimosa tenuiflora, extrato de Equisetum arvense e timol) recorrendo à utilização de embriões de peixe-zebra como modelo. Numa primeira abordagem procedeu-se ao cálculo dos valores das concentrações médias letais para 96h de exposição (96h-LC50) iniciada em embriões na fase de blástula (~2 horas pós-fertilização). Com base no valor de 96h-LC50, os embriões foram expostos a concentrações que variaram entre 0.001 e 0.1 mgL-1 para a azoxistrobina (LC50 = 1.15 mgL-1 ), 0.0005 e 0.05 mgL-1 para o mancozebe (LC50 = 5.13 mgL-1 ) e 0.05 e 5 mgL-1 para o tebuconazole (LC50 = 7.25 mgL-1 ). Para os compostos de origem natural, os embriões foram expostos a concentrações que variaram entre 0.00625 e 0.625 mgL-1 para o extrato aquoso de Equisetum arvense (LC50 = 435.31 mgL-1 ), 0.008 e 0.8 mgL-1 para o extrato etanólico de Mimosa tenuiflora (LC50 = 123.87 mgL-1 ) e 0.01 e 1 mgL-1 para o timol (LC50 = 32.67 mgL-1 ). Durante a exposição foram avaliados diversos parâmetros letais (mortalidade, destacamento da cauda e da cabeça), sub-letais (desenvolvimento dos somitos, olhos, otólitos, edema, pigmentação, movimentos espontâneos, sistema circulatório e eclosão), teratogénicos (malformações), bem como a análise morfométrica das larvas. Outros parâmetros bioquímicos como enzimas ligadas ao stresse oxidativo (SOD, CAT, GPx e GR), níveis de ROS, níveis de glutationas (GSH e GSSG), enzimas relativas a degradação de compostos (GST e CarE), ligadas a neurotransmissão (AcHE) e respiração anaeróbia (LDH), foram também analisados. Os embriões expostos a compostos sintéticos apresentaram uma maior percentagem de efeitos letais, sub-letais e a nível enzimático. Os embriões expostos a mancozebe apresentam um decréscimo na sua taxa de eclosão muito acentuado para todas as concentrações avaliadas, e um grande número de malformações (edemas cardíacos e do saco vitelino, bem como torções na coluna) apresentavam uma maior prevalência na concentração mais elevada, sendo assim efeitos dose-dependentes. Já os expostos a azoxistrobina na concentração mais baixa apresentam um aumento dos ROS bem como um aumento da SOD, GST, CarE e AcHE, bem como uma diminuição da atividade da CAT e dos níveis de GSH e GSSG. Não se verificaram diferenças no desenvolvimento dos embriões expostos a tebuconazole, bem como a fungicidas à base dos compostos naturais. Conclui-se assim que a presença de compostos sintéticos no ambiente pode causar alterações significativas nos ecossistemas aquáticos, podendo estes serem substituídos pelos compostos naturais. Contudo, mais estudo são necessários para comprovar na totalidade a segurança e sensibilidade dos compostos testados.
Agriculture is affected by the environmental conditions inherent in climate change. This phenomenon is associated with increased use of pesticides in order to control fungi and pests (eg, mildew and powdery mildew) that attack agricultural, especially wine production. In this sense, the use of fungicides have been associated with the appearance of their residues in the soil and water sheets with possible toxic effects on ecosystems However, the study and toxicological knowledge about the residues and effects of these compounds are limited or non-existent. The objective of this work was to evaluate the toxicity of synthetic fungicides (azoxystrobin, tebuconazole and mancozeb) and compounds of natural origin (extract of Mimosa tenuiflora, extract of Equisetum arvense and thymol) using zebrafish embryos as a toxicological model. In a first approach, we calculated the mean lethal concentration values for 96h exposure (96h-LC50) in embryos in the blastula phase (~ 2 hours post-fertilization). Based on the 96h-LC50 value, the embryos were exposed to concentrations ranging from 0.001 to 0.1 mgL-1 for azoxystrobin (LC50 = 1.15 mgL-1 ), 0.0005 and 0.05 mgL-1 for mancozeb = 5.13 mgL-1 ) and 0.05 and 5 mgL-1 for tebuconazole (LC50 = 7.25 mgL-1 ). For the compounds of natural origin, the embryos were exposed to concentrations ranging from 0.00625 to 0.625 mgL-1 for the aqueous extract of Equisetum arvense (LC50 = 435.31 mgL-1 ), 0.008 and 0.8 mgL-1 for the Mimosa tenuiflora extract (LC50 = 123.87 mgL-1 ) and 0.01 and 1 mgL-1 for thymol (LC50 = 32.67 mgL-1 ). During the exhibition, several lethal parameters (mortality, tail and head detachment), sub-lethal (development of somites, eyes, otoliths, edema, pigmentation, spontaneous movements, circulatory system and hatching), teratogenic (malformations) such as the morphometric analysis of the larvae. Other biochemical parameters such as oxidative stress-linked enzymes (SOD, CAT, GPx and GR), ROS levels, glutathione levels (GSH and GSSG), compounds degradation enzymes (GST and CarE), neurotransmission and anaerobic respiration (LDH), were also analyzed. Embryos exposed to synthetic compounds showed a higher percentage of lethal, sublethal and enzymatic effects. Embryos exposed to mancozeb showed a marked decrease in their hatching rate for all concentrations evaluated, and a large number of malformations (cardiac and yolk sac edema as well as spinal torsions) had a higher prevalence at the highest concentration, thus being dose-dependent effects. On the other hand, those exposed to azoxystrobin at the lowest concentration present an increase in ROS as well as an increase in SOD, GST, CarE and AcHE, as well as a decrease in CAT activity and GSH and GSSG levels. There were no differences in the development of embryos exposed to tebuconazole, as well as fungicides based on natural compounds. It is thus concluded that the presence of synthetic compounds in the environment can cause significant changes in aquatic ecosystems, and these can be replaced by natural compounds. However, further study is needed to fully demonstrate the safety and sensitivity of the compounds tested.
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Huang, Tzu-Wei, und 黃子瑋. „Effects and regulatory mechanisms of berberine on mouse embryonic development in both pre- and post-implantation stages“. Thesis, 2011. http://ndltd.ncl.edu.tw/handle/zdwk86.
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碩士中原大學
生物科技研究所
99
Berberine is an alkaloid isolated from Coptis Chinensis, Phellodendron and other plant extracts. Berberine is a traditional Chinese medicine in China which has been applied for a long time. Berberine has been evaluated as anti-diarrhea, anti-bacterial, anti-arrhythmic, anti-vascular smooth muscle proliferation and cholesterol-lowering. Berberine also performs a wide range of applications in the cardiovascular system and nervous system diseases. Several studies have demonstrated that berberine is able to induce apoptosis process in cancer cells. However, a study regarding the embryonic toxicity of berberine has not yet been done. In this study, mouse embryos were used to study the effects of berberine on embryonic development and proliferation. The study results showed that blastocysts treated with 5 or 10 μM of berberine that resulted a significant dose-dependent increase in apoptosis and inhibited cell proliferation. To evaluate the alteration of inner cell mass (ICM) and trophoblast cell (TE) of mouse blastocysts, we used differential staining and TUNEL assay. Statistics showed, TE subject to more damage than ICM. Furthermore, the immunofluorescence staining, revealed that berberine induced apoptosis in mouse blastocysts by reducing expression of anti-apoptotic Bcl-2 protein and increasing expression of the pro-apoptotic Bax protein, which increases the ratio of Bax/Bcl-2. Conclusion, berberine induced embryo cell apoptosis and caused hazardous effects on embryonic development.
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Magro, Martim Ramos Chaves Lopes. „Effect of temperature on embryonic development, larval viability and biomarkers in the first stages of life of Octopus Vulgaris (Cuvier, 1797)“. Master's thesis, 2015. http://hdl.handle.net/10400.1/8233.
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Dissertação de Mestrado, Aquacultura e Pescas, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2015O cultivo de Octopus vulgaris, apresenta diversos problemas, principalmente durante os primeiros estádios de desenvolvimento. Nas últimas décadas, muitos grupos de investigação têm feito um esforço no sentido de conseguir perceber quais as soluções para os problemas do cultivo desta espécie. O presente estudo tem como objetivo analisar o efeito de diferentes temperaturas de incubação (19ºC e 22ºC) no desenvolvimento embrionário da postura de apenas uma fêmea. Foram analisados biomarcadores de crescimento, stresse fisiológico, defesas antioxidantes e atividade neuronal (RNA/DNA, HSP70, GST e AChE, respetivamente). Os ovos foram incubados a partir do estádio XV até à eclosão e posteriormente foram mantidos à temperatura ambiente (22±1ºC) durante 14 dias. Sobrevivência, crescimento específico, biomassa e peso seco foram medidos nesse período. Foram recolhidas amostras com o intuito de analisar os diferentes biomarcadores por individuo. Para analisar HSP70, utilizaram-se “pools” de paralarvas (7-8). Os resultados apresentam diferenças significativas relativamente à sobrevivência e crescimento específico entre temperaturas. Os resultados do rácio de RNA/DNA e GST (0 e 14 dias) e HSP70 (0,7 e 14 dias) apresentam diferenças significativas entre diferentes idades e temperaturas. Na análise efetuada à AChE não foram encontradas diferenças significativas de atividade entre os diferentes grupos (idades e temperaturas). É notável a ampla variabilidade de resposta aos biomarcadores das paralarvas provenientes da mesma postura. Os resultados demonstram que o rácio RNA/DNA, GST e HSP70 como biomarcadores sensíveis para o crescimento, stress térmico e defesas antioxidantes em paralarvas. No entanto, o crescimento e a temperatura parece não alterar o sistema neurotransmissor dos indivíduos.
European Research COST AQUAGAMETE FA1205, CEPHSINACTION FA1301
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Lien, Ching-Yi, und 練慶儀. „Homology Comparison of the cDNA Sequences in Vertebrates for Screening the Commonly Expressed Genes with Related Functions during Early Embryonic Stages“. Thesis, 2007. http://ndltd.ncl.edu.tw/handle/13224388575139240792.
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碩士臺灣大學
動物科學技術學研究所
95
The early embryonic stages of mammals are the developmental process from zygote to preimplantation. The stages of embryogenesis are critical for embryonic development in vertebrates. Several key developmental events occurr in these stages, such as cell growth, migration, differentiation, and morphogenesis. In spite of the importance occurring in the early embryogenesis, limited information has been provided by previous studies. For this reason, the purpose of this study is to utilize the public databases to screen those commonly expressed genes with their related functions at early embryonic stages in vertebrates. The UniGene and the Gene Index databases in the National Center for Biotechnology Information (NCBI) and The Institute for Genomic Research (TIGR) were designed to collect and assemble sequences of expressed sequences tags (ESTs) and mRNA. Each assembled entry is a set of transcript sequences that appear to come from the same transcription locus. The numbers of unigene entries and tentative consensuses (TC) of embryos before implantation collected from Bos taurus (Bt), Mus musculus (Mm), Sus scrofa (Ssc) and Xenopus laevis (Xl) were 2,407, 13,705, 4,015, and 15,329, respectively. The analytic results among four species were divided into seven groups. All of the commonly expressed genes were 1,414 for Mm and Bt; 1,909 for Mm and Ssc; 2,372 for Mm and Xl; 411 for Mm, Bt and Ssc; 602 for Mm, Bt and Xl and 860 for Mm, Ssc and Xl. However, there were 254 genes commonly expressed in all these four species. Furthermore, the unigenes of Mm were classified according to the Gene Ontology (GO) by three categories: biological process (P), molecular function (F) and cellular component (C). The results among Mm, Bt, Ssc and Xl showed the entries with GO identifiers were 112 (P), 113 (F) and 105 (C); the results between Mm and Ssc showed the entries with GO identifiers were 857 (P), 926 (F) and 862 (C); the results between Mm and Xl showed the entries with GO identifiers were 1,208 (P), 1,281 (F) and 1,145 (C). For the entries that mapped to biological processes, most of them with their functional annotations were related to metabolic processes. For molecular function, most of the commonly expressed genes were related to some macromolecule or ion binding. In addition, these activated genes are expressed intracellularly at early developmental stages. The commonly expressed genes and their related functions might be annotated using comparison tool among sequence databases of different species. The analytical procedure would assist animal scientists to screen the conserved genes with fundamental roles and functions.
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Gong, Zhigang [Verfasser]. „In-vitro cultured ventral mesencephalic precursor cells from rat embryos at different embryonic stages : an exploration from cells to genes / vorgelegt von Zhigang Gong“. 2007. http://d-nb.info/984744614/34.
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