Dissertations / Theses on the topic 'Canard souchet'
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Moreau, Axelle. "Relation entre les invertébrés d’eau douce et le Canard souchet Spatula clypeata en halte prénuptiale dans deux zones humides de Vendée (France)." Electronic Thesis or Diss., La Rochelle, 2023. http://www.theses.fr/2023LAROS004.
Full text"Income breeder", the Northern shoveler Spatula clypeata makes several stopovers between its wintering and breeding site in order to replenish its reserves and complete its pre-breeding migration. Freshwater invertebrates are the main prey of the Northern shoveler and are captured mainly by filtration. This research project had three main objectives: (1) to understand the abundance, diversity, and habitat of freshwater invertebrates in two wetlands known for their high abundance of Northern shoveler, the Marais breton, and the Marais poitevin; (2) to study the environmental and nutrient characteristics of the habitats used by the Northern shoveler during its prenuptial stopover; (3) to define habitat management measures in favour of all of the species groups studied. This study showed that the ponds studied were abundant in freshwater invertebrates. The study defined four habitat typologies based on environmental variables and the presence of some key invertebrate taxa. During migratory stopover, the Northern shoveler used different habitats with a nychthemeral rhythm. Daytime sites were deep and sparsely vegetated habitats dominated by microcrustaceans, while nighttime sites were shallow and vegetated habitats with high invertebrate taxonomic diversity. Home range sizes did not differ between the two wetlands, between sexes or between age classes (juveniles and adults). Finally, this study revealed that during the prenuptial stopover, the Northern shoveler fed mainly on Cladocera, Copepoda, Chironomidae larvae, Pleidae and Particulate Organic Matter. The results of this work could help to define management and habitat conservation measures for all the species studied
Dupiellet, Jean-Paul. "Mycoplasmes de l'oie et du canard : contribution à l'étude sérologique et moléculaire de souches apparentées à Mycoplasma gallisepticum." Bordeaux 2, 1988. http://www.theses.fr/1988BOR22021.
Full textDupiellet, Jean-Paul. "Mycoplasmes de l'oie et du canard contribution à l'étude sérologique et moléculaire de souches apparentées à Mycoplasma gallisepticum /." Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb37613341q.
Full textAyad, Oualid. "Caractérisation fonctionnelle des cellules souches cardiaques humaines dans un but thérapeutique." Thesis, Poitiers, 2017. http://www.theses.fr/2017POIT2303/document.
Full textThe aim of this thesis was to develop and characterize a model of human heart stem cells in a context of cell therapy.A population of mesenchymal stem cells, expressing the W8B2 marker (CSCs W8B2+), was first isolated from human auricles and characterized using high-throughput RT-qPCR techniques, immuno-labeling, western-blot and calcium fluorescence imaging. These experiments were focused on 1. the gene expression of ion channels and calcium signaling proteins; and 2. the study of CSCs W8B2+ in vitro differentiation and associated intracellular calcium activity changes.The results show that CSCs W8B2+ tend to differentiate into pacemaker cells. Some nodal specific genes such as Tbx3, HCN, ICaT, L, Kv, NCX, are expressed during differentiation. The recording of calcium activity (via an optogenetic probe) shows the presence of calcium oscillations that change in frequency and intensity during differentiation. IP3 sensitive calcium stocks and the NCX exchanger would play a fundamental role in these variations.Then we studied the importance of the BKCa channel and the sphingosine 1-phosphate (S1P) receptors in the regulation of the fundamental properties of the W8B2+ CSCs. Inhibition of BKCa reduces cell proliferation by accumulating cells in the G0 / G1 phase, suppresses cell self-renewal but does not affect migration properties. Concerning S1P, it decreases proliferation and self-renewal without stimulate S1P1,2,3 receptors.This work highlights fundamental potential molecular targets in a context of cardiac cell therapy
Andin, Nicolas. "Etude des potentialités de production de polyhydroxyalcanoates (PHA) à partir de graisses de canard par la souche Pseudomonas pufida KT2440." Thesis, Toulouse, INSA, 2016. http://www.theses.fr/2016ISAT0056.
Full textPolyHydroxyAlkanoates (PHA) production by the strain Pseudomonas putida KT2440, from duck fats has been investigated. The first studies were realized on model substrates such as glycerol and fatty acids, composing this lipid substrate. The kinetic and stoichiometric characterizations of Fed-Batch mode cultivations on each of thèse substrates were performed by coupling PHA production and a residual growth monitored by the nitrogen feeding. Through this strategy from fatty acids, it succeeds to optimize the intracellular catbon and energy distribution reaching an overall carbon yield of 0.7 Cmo1e.Cmole''. From glycerol, kinetics and yields productions were tess interesting becapse PHA are the results of an energy-consumîng biosynthesis. Beyond thèse performances, some relationships between the culture conditions for the PHA production and the properties of the final polymers were determined. Indeed, function of the substrate, the metabolic pathways used, different polymers more or less crystalline are obtained. PHA with the lowest unsaturated monomers fraction (<12%u'.cle.mole 1) and a main kind qf monomer in their. composition have the highest degree of‘ ‘* cÎystalliniÎy. Thej adÂpt the appeàrance ot à vêry inferesting ela‘sfic’Îilùi àfter êxbaction. ConŸêtsely,‘po1ynierswith a high unsaturated monomers fraction and homogeneity of monomers proportions resemble unmanageable amorphous sticky dough, with a limited industrial interest
Tremblay, Sophie. "Exploration des déterminants du soutien social chez les personnes aînées immigrantes et canadiennes de souche." Mémoire, Université de Sherbrooke, 2012. http://hdl.handle.net/11143/6083.
Full textOlivier, Stéphane. "Développement de la plateforme cellulaire EB66 dérivée de cellules souches embryonnaires de canard pour la production industrielle d’anticorps thérapeutiques à activité ADCC améliorée." Nantes, 2010. http://www.theses.fr/2010NANT33VS.
Full textMonoclonal antibodies (mAbs) represent the fastest growing class of pharmaceuticals. However, prohibitive therapeutic costs call to develop cheaper and more active molecules. To this end, one of the promising strategies is to enhance mAbs efficacy through an improved antibody dependent cell cytotoxicity (ADCC) correlated with mAbs fucosylation level. EB66 cell line, a duck embryonic stem cell-derived substrate, displays unique regulatory and industrial features: they are genetically stable, immortal, and reach high cell densities in serum-free medium. The fact that avian species have been described to naturally produce low-fucosylated antibodies prompted the investigation on the use of the duck EB66 cells for the production of mAbs with reduced fucose content and enhanced ADCC activity. The aim of this work was to establish and optimize technologies dedicated to the development of the EB66 cellular platform for the production of therapeutic mAbs. A selection procedure has been developed to isolate producer clones. A yield titer higher to 1 g/l has been reached thanks to the optimization of a specific expression vector associated to the development of the production process. The mAbs produced on EB66 cells display a glycosylation profile comparable with mAbs produced on the Chinese hamster ovary cells, with a naturally reduced fucose content resulting in a strongly enhanced ADCC activity. Furthermore, we observed a correlation between mAbs fucosylation and expression level of the alpha 1,6-fucosyltransferase within producer clones. The EB66 cells have therefore the potential to evolve as a novel cellular platform for the production of high potency therapeutic antibodies
Chafai, Magda. "Effets du PACAP et du VIP sur la différenciation neuronale des cellules souches embryonnaires de souris." Rouen, 2009. http://www.theses.fr/2009ROUES026.
Full textMouse embryonic stem (ES) cells are isolated from the inner mass of the blastocyst. Pituitary adenylate cyclase activating polypeptide (PACAP) and vasoactive intestinal polypeptide (VIP) are known to be implicated early during ontogenesis. The aim of the present study was to determine the effects of VIP and PACAP on functional differentiation of ES cells. Our results showed an inversion of the expression pattern of PAC1 and VPAC1 receptors. ES cells expressed ERK1/2 and JNK. Both peptides modified the shape of undifferentiated ES cells into bipolar. Electrophysiological recording showed that VIP and PACAP enhanced potassium and calcium current. These findings demonstrate that PACAP and VIP induce morphological and functional differentiation of ES cells into a neuronal phenotype. Our results on the pro-differentiating effect of compound X indicate that this molecule facilitates the commitment of ES cells into the neuronal pathway
Terrie, Élodie. "Rôle de la signalisation calcique dépendante des Store-Operated Channels (SOC) dans les cellules souches neurales adultes et les cellules souches cancéreuses de glioblastomes." Thesis, Poitiers, 2019. http://www.theses.fr/2019POIT2322.
Full textNeural stem cells (NSC) persist in the brain of adult mammals and fuel the brain with new neurons and glial cells all lifelong. Recruited by brain injuries, NSC are considered with great interest by regenerative medicine. However, the development of new therapeutic approaches based on the use of NSC requires an in-depth knowledge of the mechanism regulating these cells. Glioblastomas are the most frequent and deadliest form of adult brain tumors. Within the tumor, glioblastoma stem cells (GSC) form a subpopulation of cells that is considered as responsible of tumor initiation, propagation and relapse, as these cells are particularly resistant to anti-tumoral treatments. GSC and NSC share key characteristics and numerous studies suggest that GSC arise from transformed NSC. Transcriptomic analysis of NSC and of GSC revealed an enrichment of calcium signaling transcripts in these two cell populations. Representing a major way of calcium influx into cells, Store-Operated Channels (SOC) are mobilized in response to a wide range of extracellular factors. SOC regulate many cellular processes and are often hijacked in cancer to promote tumor progression.The aim of this thesis is to evaluate potential SOC involvement in NSC and GSC regulation.The first part of this work, relying on in vitro and in vivo studies, demonstrates that NSC from adult mice express functional SOC whose inhibition by pharmacological agents reduces NSC proliferation and self-renewal. In the second part of this thesis, we demonstrate that GSC from primary cultures derived from patients express SOC, as do NSC, and that SOC inhibition reduces GSC ability to proliferate and self-renew.Accordingly, the results of this thesis demonstrate that SOC regulate NSC and GSC self-renewal, a property that is essential to maintain stem cells pool. As GSC are responsible for glioblastomas treatment resistance, our studies point to a potential new therapeutic way, via calcium channels, against this deadly pathology
L'Hostis-Guidet, Anne. "Des xénopes transgéniques pour l’étude de la neurogénèse : analyse et propriétés fonctionnelles de neuroblastes exprimant un gène rapporteur sous contrôle du promoteur de NeuroD." Rennes 1, 2007. http://www.theses.fr/2007REN1S139.
Full textElectrical activity involved in neurogenesis during embryonic development of vertebrates is dependant of calcium permeabilities whose characterization requires the ability to locate neuroblasts. Transgenic lines expressing EGFP under the control of the NeuroD (neuronal differentiation factor) and the Neuro β-tubulin (neuronal marker) promoters were produced in Xenopus laevis. The transgene expression is restricted to neurons and non differentiated cells exclusively in nervous system in these transgenic animals. Confocal calcium imaging suggests that EGFP expressing cells with the NeuroD promoter would have different functional properties compared to cells without transgene expression. The combination of transgenesis and functional cellular imaging is a promising tool for characterization of neuroblasts expressing bHLH NeuroD factor
Torossian, Frédéric. "Contribution à l'étude de la diversité des cellules souches mésenchymateuses et hématopoïétiques : caractérisation de canaux calciques et d'un récepteur de SDF-1." Rouen, 2009. http://www.theses.fr/2009ROUES042.
Full textOur study is based on three research axes : i) calcium homeostasis and its molecular targets in mesenchymal stem cells (MSC) in order to differentiation ex vivo, ii) MSC heterogeneity and iii) a low affinity receptor for SDF-1 in haematopoietic stem cells. We show homeostasis of MSC implicate the activity of L-, T- and N-type calcium channels, potassium and sodium channels, calcium activated potassium channels, TRPC-1, -2 and -6 calcium channels, sodium/potassium ATPase and sodium/calcium exchanger. Moreover, the use of pharmacological tools or siRNA decrease the proliferation of MSC and sometimes initiate its differentiation. Our results show a differential gene expression between MSC cultures result from different colonies, as indicate the molecular profiles obtained by the technique of differential display RT-PCR, suggesting MSC heterogeneity. Moreover, we indicate SDF-1, a chimiokine known for activation of a high affinity receptor CXCR4, could activate a low affinity receptor syndecan 4. This conclusion is illustrated by microscopy electronic, Western blot and RT-PCR. The functional tests show that effect of a low SDF-1 concentration is inhibited by AMD3100 (CXCR4 antagonist) and its of a high concentration by an antibody anti-SD4
Noyer, Lucile. "Role of Orai1 in prostate cancer proliferation and cancer stem cell quiescence/activation transition." Thesis, Lille 1, 2019. http://www.theses.fr/2019LIL1S111.
Full textProstate cancer (PCa) is the most frequent and the third deadliest cancer in men in Europe. Cancer stem cells (CSC) are a rare subset of cancer cells possessing stem cell properties leading to a high resistance to therapy and an enhanced tumorigenicity. As a result, CSCs have been linked to tumor dormancy and relapse upon reactivation. Thus, the mechanisms regulating CSC dormancy/activation transition are of critical importance in PCa. Previous studies showed the importance of Orai proteins in PCa, through their roles in SOC (store-operated channel) and ARC (arachidonic acid-regulated calcium channel) channels. But the role of Orai1 in PCa proliferation and CSC physiology remained to be studied. Moreover, in order to bypass current targeting limitations for Orai1, we aimed to identify a partner protein able to regulate Orai1 in PCa. For this purpose, we focused on the Sigma 1 receptor (S1R), a chaperone protein capable of ion channel regulation. Interestingly, S1R expression is increased in PCa and this protein can bind many pharmacological compounds currently used for other clinical applications. This work thus aimed to first study the role of Orai1 in PCa and CSC physiology, and then characterize the role of S1R as a new regulator of Orai1 in PCa. Our results first show that Orai1 is a key regulator of CSC transition between quiescence and proliferation via the NFAT pathway. Moreover, this role is not limited to PCa, since these results were also confirmed in melanoma CSCs. We also show here that the S1R directly interacts with Orai1 and increases its activity, thus modulating PCa cell proliferation. Finally, we characterized the regulation of Orai1 and S1R expression by androgens, which is highly significant during PCa development. Our results therefore allowed the identification of a key regulator of PCa proliferation (Orai1), and propose an alternative method for its targeting via the identification of its partner protein (S1R). These results could lead to the development of new markers and innovative therapeutic strategies
Qian, Yu. "Analyser le gène PKC-2 chez Caernorhabditis elegans et crible les mutants contre sérotonine chez le C. elegans souche pkc-2 (ok328)." Phd thesis, Université Claude Bernard - Lyon I, 2009. http://tel.archives-ouvertes.fr/tel-00712129.
Full textDrouin, Érika Véronique. "L'utilisation des cellules souches embryonnaires à des fins thérapeutiques." Thèse, 2003. http://hdl.handle.net/1866/2381.
Full textThe embryonic stem cells discovery and the immense therapeutic potential glven to them has created big hopes in the world of today. The appearance of new revolutionary therapies to treat sorne of the most serious known diseases are now conceivable. However, the treatment of life to its earliest stage is questionned. The legal status recognized to the foetus and the embryo has, in fact, a direct effect to the research area and industry as weil as to its therapeutic use. Therefore, we have examined and studied the CUITent canadian law with respect to the legal status of the foetus and embryo. Following this study, we have noticed the uncertainty that prevails in Canada concerning the said legal status. Afierwards, we have examined ail the different canadian norms and regulations already established regarding the use of embryonic stem cells for therapeutic ends. We also did the comparaison between those norms and regulations so as to see their differences and similarities. It appears from our analysis that ail the canadian litterature generally treat the subject in the same way and that there have been few changes from 1993 up until now with respect to the forbidden researchs activities in Canada. We also have analysed the foreign law standards and regulations in United States and Great Britain concerning those forbidden researchs activities. We did the exercise of comparing the state of the law in these three countries with different parameters. It emerges from that that Great Britain is the most liberal country, United States being the most conservative and Canada being in between them.
"Mémoire présenté à la Faculté des études supérieures en vue de l'obtention du grade de Maîtrise en droit (L.L.M.) Option recherche"
Vigneault, Patrick. "Rôle fonctionnel des canaux potassiques activés par le calcium au sein de progéniteurs cardiaques : implication en médecine régénérative." Thèse, 2018. http://hdl.handle.net/1866/23541.
Full textHeart failure (HF) is a progressive disease characterized by extensive pathological remodelling of the heart and myocardial damage. Regardless of the etiology, a decrease of about 30% in the number of ventricular cardiomyocytes is observed at the terminal stage of HF. Based on converging preclinical data in HF models, the innovative concept of cell therapy has generated a great deal of enthusiasm in cardiology. Although the role of cardiac stem cells in cardiac homeostasis is highly controversial, the multipotent progenitors that persist within the adult myocardium possess the ideal characteristics for cardiac regeneration, especially because of their cardiogenic committment. Plasma membrane ion channels are involved in the fundamental processes of virtually all cells that make up the human body, including stem cells. A wide range of functional ion channels was identified in ex vivo proliferated endogenous cardiac progenitor cells (eCPCs), but their function remains poorly understood. We have completed the very first characterization of the ionic profile of freshly-isolated c-Kit+ eCPCs. We found that the intermediate conductance Ca2+-activated potassium current (IKCa3.1) is the predominant conductance and contributes to the determination of membrane potential (Vmem). The hyperpolarization generated by the activation of the KCa3.1 channel (SK4; KCNN4) maintains the electrical gradient and promotes store-operated Ca2+-entry (SOCE) that activates progenitor cell proliferation. Experimental congestive heart failure (CHF) significantly decreased the expression of KCa3.1 as well as cell cycle regulatory proteins. Taken together, these findings suggest that alterations in KCa3.1 may have pathophysiological and therapeutic significance in regenerative medicine In addition to c-Kit+ eCPCs, cardiac explants-derived cells (EDCs) represent another promising cell product for myocardial repair. EDCs are obtained as a heterogeneous mixture composed of complementary subpopulations. Interestingly, it was found that a high proportion of CD90+ cells reduce the functional benefits of EDCs therapy. Consistent with this observation, it has recently been shown that the CD90- population constitutes the active fraction in terms of therapeutic efficacy. In order to gain insight into the ionic determinants of EDCs function, the electrophysiological properties of the CD90+ and CD90- populations were studied. Considering the importance of KCa3.1 in c-Kit+ CPCs, we evaluated the presence of KCa channels in human EDCs. We have identified 2 types of KCa channels in ex vivo expanded EDCs. While KCa1.1 (BKCa; KCNMA1) channel was homogeneously expressed in both subpopulations, KCa3.1 was found exclusively in the CD90- cell fraction. Similar to our previous observations in freshly isolated c-Kit+ eCPCs, KCa3.1 was responsible for the determination of Vmem under resting conditions and during SOCE. Importantly, we demonstrated that transplantation of genetically-modified EDCs to over-express KCNN4 potentiates cardiac regeneration in a murine model of ischemic cardiomyopathy. This study provides the first evidence in the literature that modulating the activity of a single plasma membrane ion channel can truly improves the therapeutic efficacy of progenitor cells.