ED Sciences Chimiques
Development of a correlative cryo-nanoimaging approach for metals and proteins using synchrotron X-ray fluorescence and optical fluorescence: application to metal neurotoxicity
by Ines KELKOUL (Laboratoire de Physique des 2 Infinis de Bordeaux)
The defense will take place at 10h00 - Salle des séminaires Marie Curie Laboratoire de physique des 2 infinis de Bordeaux, 19 chemin du Solarium, 33170 Gradignan
in front of the jury composed of
- Asuncion CARMONA - Chargée de recherche - CNRS / Université de Bordeaux - Directeur de these
- Sylvain BOHIC - Chargé de recherche - INSERM / Université de Grenoble - ESRF - Rapporteur
- Sandra MOUNICOU - Directrice de recherche - CNRS / Université de Pau et des Pays de l'Adour - Rapporteur
- Yann FICHOU - Chargé de recherche - CNRS / IECB / CBMN / Université de Bordeaux - Examinateur
- Géraldine SARRET - Directrice de recherche - CNRS / Institut des Sciences de la Terre / Université Grenoble Alpes - Examinateur
- Richard ORTEGA - Directeur de recherche - CNRS / LP2ib - Examinateur
Metals such as manganese, mercury, and cadmium are well-established neurotoxicants, yet the cellular and subcellular mechanisms through which they impair neuronal function remain poorly characterized. A major limitation of existing approaches is the lack of methods capable of localizing a metal at the nanoscale while unambiguously associating it with an identified subcellular structure, such as an organelle, synapse, or membrane compartment, in cells preserved close to their native state. This thesis work aimed to develop and apply a correlative imaging approach combining synchrotron radiation-induced X-ray fluorescence (SXRF) with optical fluorescence microscopy, performed under cryogenic conditions on primary hippocampal neurons cultured on silicon nitride membranes. Cryofixation preserves the native distribution of chemical elements and the ultrastructural integrity of cells, while fluorescent labeling, using fluorescent protein fusions, immunolabeling, or live-cell probes, provides the structural specificity required to interpret elemental maps. SXRF acquisitions were performed at the ID16A and ID21 beamlines at the European Synchrotron Radiation Facility (ESRF) and at the Nanoscopium beamline at SOLEIL, with spatial resolutions reaching 15 nm, enabling the analysis of individual organelles and subcellular structures such as dendritic spines or individual mitochondria. This methodology was applied to investigate the neurotoxicity of three metals in primary rat hippocampal neurons (E18) following 24 h exposure. Manganese preferentially accumulated in the Golgi apparatus and at postsynaptic compartments, providing insight into the cellular mechanisms underlying its neurotoxicity and potentially informing the revision of international health recommendations. Mercury was localized within dendritic spines, providing a first indication of its potential impact on synaptic structure and function. In contrast, no accumulation of cadmium was detected in any of the four subcellular compartments investigated—mitochondria, endoplasmic reticulum, lysosomes, and postsynaptic density. This negative result is nevertheless informative, directing hypotheses toward other subcellular targets or a more diffuse distribution of the element. In parallel, the observation of axonal varicosities was discussed as a potential indicator of degeneration or, alternatively, of an adaptive response to metal exposure. Beyond the biological findings, this work demonstrates that the main strength of the developed approach lies in its ability to link quantitative chemical information to a specific and individually identified biological structure at a spatial scale inaccessible to conventional elemental bioimaging methods. The methodological and experimental limitations of the approach are discussed, together with prospects for technical improvements and its extension to other metals and cellular models. Overall, this work contributes both to the methodological development of correlative cryo-SXRF/fluorescence imaging and to a better understanding of metal neurotoxicity at the subcellular scale.
ED Droit
The international protection of European agri-food geographical indications
by Lise BERNARD (CENTRE DE RECHERCHES ET DE DOCUMENTATION EUROPÉENNES ET INTERNATIONALES)
The defense will take place at 14h00 - Salle des thèses Université de Bordeaux, campus Montesquieu (Pessac), bâtiment C1, rez-de-chaussée, salle des thèses.
in front of the jury composed of
- Loïc GRARD - Professeur des universités - Université de Bordeaux - Directeur de these
- Richard OUELLET - Professeur des universités - Université Laval - CoDirecteur de these
- Cécile RAPOPORT - Professeure des universités - Université de Rennes - Rapporteur
- Théodore GEORGOPOULOS - Professeur des universités - Université de Reims - Rapporteur
- Mathilde FRAPPIER - Professeure des universités - Université de Lorraine - Examinateur
- Olivier DELAS - Professeur des universités - Université Laval - Examinateur
The European Union (hereinafter, the EU) protects more than 3,500 denominations for agri-food products, wines and spirits within its territory through a comprehensive legal framework built around geographical indications (hereinafter, GIs). The associated labels, grounded in the valorisation of origin, quality and traditional savoir-faire, constitute a major economic and cultural instrument. Yet the effectiveness of this system reaches its limits beyond the EU's borders. Many European denominations, such as Camembert de Normandie, Parma Ham or Feta, are used freely in certain third countries, particularly in the New World, where a significantly different approach to the protection of these distinctive signs prevails. The EU therefore seeks to extend its sui generis protection system in order to secure the recognition of its GIs abroad and to have competing uses qualified as acts of usurpation. Against this backdrop, the thesis examines the legal strategy deployed by the European Union to ensure the protection of its geographical indications on the territory of third countries. The first part demonstrates that the existing multilateral frameworks, whether those established within the World Trade Organization and the World Intellectual Property Organization or under other United Nations instruments, provide only limited protection for European geographical indications. Such protection remains significantly less binding and less comprehensive than that guaranteed within the EU's own legal order, despite the stated ambition to secure their recognition on an international scale. Faced with this structural shortcoming in international law, the EU has undergone a strategic shift, making GIs a sine qua non condition for the conclusion of its free trade agreements. Over the past fifteen years, the inclusion of GIs in regional trade agreements (hereinafter, RTAs) has thus become a central feature of the EU's external trade policy. The second part analyses the practical implementation of this strategy. It appears that the EU adopts a pragmatic and selective approach to choosing its trading partners, favouring States with which it has sufficient negotiating leverage to promote its model of protection. An examination of recent RTAs reveals a twofold rationale: an uncompromising stance in principle on the protection of European denominations, combined with flexibility as regards the modalities of implementation and the selection of protected products. This adaptability reflects a necessary subjectivist approach to safeguarding GIs, one that accounts for the legal, economic and cultural contexts specific to each partner. This strategy yields markedly positive outcomes for the EU. The proliferation and interlinking of trade agreements enable a progressive, network-based extension of the protection of European GIs on the international stage, creating what may be likened to a “spider's web” of protection, and thereby strengthening the EU's position as a normative power in this field. The thesis concludes that this dynamic, which may be characterised as intersubjectivist, now constitutes the most effective instrument for protecting certain European GIs beyond the EU's borders, notwithstanding its limitations.