ED Sciences Chimiques
Self-assembling columnar liquid crystalline matrices with large T1-S0 gap for anisotropic delayed luminescence emitters
by Wilson DE OLIVEIRA (Centre de Recherche Paul Pascal)
The defense will take place at 13h30 - Auditório Professor Faruk Nome UFSC - Campus Universitário - Trindade, 88040-900, , Florianópolis - SC, Brazil
in front of the jury composed of
- Harald BOCK - Directeur de recherche - Centre de recherche Paul Pascal - Directeur de these
- Aloir Antonio MERLO - Professeur - Universidade Federal do Rio Grande do Sul - Rapporteur
- Eduard WESTPHAL - Professeur - Universidade Federal de Santa Catarina - CoDirecteur de these
- Caroline Da Ros Montes D'OCA - Professeure - Universidade Federal do Paraná - Rapporteur
The design and photophysical behavior of self-assembling liquid crystalline matrices for anisotropic delayed luminescence applications were investigated, focusing on C₃-symmetric mesogens derived from 1,3,5-triazine, tris(triazolotriazine) (TTT), and tris(N-phenyltriazole) (TPT) cores. A homologous set of compounds was synthesized, systematically varying alkyl chain length and substitution patterns to probe the structure–property relationships governing mesomorphism and emission. Trinaphthyl-triazine derivatives displayed a robust mesomorphic behavior, with meta-like ester substitution leading to stable enantiotropic nematic and hexagonal columnar phases. These materials exhibited partial homeotropic alignment after fast cooling and demonstrated large triplet-to-groundstate gaps, properties favorable for host matrices in optoelectronic applications. The aromatic core dominated their photophysical response, with ester substitution exerting stronger influence on mesophase stability than on electronic transitions. The TTT series, incorporating extended triazine cores through triazolotriazine formation, yielded predominantly glassy states at room temperature without stable mesophases. Although mesomorphism was not achieved, these systems provided insights into vitrification behavior and energy gap modulation by expanded conjugation. By contrast, the TPT derivatives revealed mesomorphism strongly dependent on regiochemistry. Meta-substituted analogues favored nematic alignment with relatively lower clearing points, whereas para-substituted derivatives stabilized hexagonal columnar phases and induced red-shifted luminescence. These findings underscore the sensitivity of supramolecular self-assembly and emission properties to substitution geometry, offering a design pathway for tuning both mesomorphic stability and photophysical response. In summary, this work demonstrates that careful selection of aromatic cores and ester substitution patterns enables the rational design of liquid crystalline host matrices combining mesomorphism, vitrification, and controlled electronic gaps. The complementary behaviors of triazine, TTT, and TPT derivatives establish a versatile molecular platform for developing anisotropic emissive environments in advanced OLEDs and related optoelectronic devices.
Mechanisms of membrane-induced Tau aggregation
by Clara PIERSSON (Institut de Chimie & de Biologie des Membranes & des Nano-objets)
The defense will take place at 9h30 - IECB Auditorium 2 rue Robert Escarpit 33600 Pessac
in front of the jury composed of
- Martina HUBER - Associate Professor - Leiden University - Rapporteur
- Isabelle LANDRIEU - Directeur de recherche - Université de Lille / CNRS - Rapporteur
- Erick DUFOURC - Directeur de recherche émérite - Université de Bordeaux / CNRS - Examinateur
- Lucie KHEMTEMOURIAN - Directrice de recherche - Université de Bordeaux / CNRS - Examinateur
Tau is a protein found in the brain where it regulates microtubule activity. It is an intrinsically disordered protein, which means that it does not have a unique three-dimensional structure. Tau can form highly-ordered aggregates that are directly involved in several neurodegenerative diseases, called tauopathies, including Alzheimer's disease (AD). Advances in cryo-electron microscopy have enabled to resolve with high resolution the structure of tau aggregates extracted from human brains. Each tauopathy is characterized by a specific fibril structure, establishing a structure–pathology relationship. These studies also showed additional non-protein densities within and around the fibril core, which may correspond to post-translational modifications, bound cofactors, or other associated molecules. Recent research has shown that Tau protein can interact directly and indirectly with the neuronal membrane, mainly composed of lipids. Moreover, Tau amyloid fibers have been colocalized with membrane lipids such as phosphatidylcholine, cholesterol, and sphingolipid in the context of AD. In vitro, the interaction between Tau and lipids has been shown to promote Tau aggregation. however, the mechanisms through which the protein-lipid interaction might modulate tau aggregation pathways remains poorly understood. This thesis ambitions three central goals: (i) Quantitatively describe the interaction of tau with lipid membranes, (ii) Understand how membrane lipid composition influences Tau binding and aggregation, and (iii) reveal the structural properties of membrane-induced Tau amyloid. We present a biochemical and biophysical characterization of tau amyloid filament formed in presence of different membrane models. In particular, we used Electron Paramagnetic Resonance (EPR) to directly quantify the population of tau bound to the membrane and to quantify the affinity between Tau and lipids. We show that the arrangement and the nature of anionic lipids at the membrane surface modulate the tau-membrane interaction, which in turn influence the aggregation of Tau into amyloid fibrils. The results suggest that lipid-induced Tau aggregation begins with electrostatic binding, is enhanced by local charge clustering, and requires conformational changes that expose aggregation-prone regions. The structural analysis has so far revealed a poorly structured amyloid filaments that is not amenable to 3D helicoidal reconstruction by cryoEM. Together, our results show that cellular membranes might be an important modulator of tau amyloid formation by altering both aggregation nucleation and structural convergence.
ED Entreprise Economie Société
Weather, Natural disasters and International exchanges
by Alex BAO (BSE - Bordeaux sciences économiques)
The defense will take place at 9h30 - Salle des Thèses Université de Bordeaux, 16 Avenue Léon Duguit, 33608 Pessac
in front of the jury composed of
- Jean-Marie CARDEBAT - Professeur des universités - Université de Bordeaux - Directeur de these
- Anne-Célia DISDIER - Directrice de recherche - INRAE, Paris School of Economics - Rapporteur
- Céline NAUGES - Directrice de recherche - INRAE, Toulouse School of Economics - Rapporteur
- Raphaël CHIAPPINI - Professeur des universités - Université de Bordeaux - CoDirecteur de these
- Charlotte EMLINGER - Senior Economist - Centre d'Etudes Prospectives et d'Informations Internationales (CEPII) - Examinateur
- Kym ANDERSON - Professeur émérite - University of Adelaide - Examinateur
- Philippe BONTEMS - Directeur de recherche - INRAE, Toulouse School of Economics - Examinateur
This dissertation investigates the impact of extreme weather conditions and natural disasters on international exchanges, distinguishing between trade flows from capital flows. The first chapter analyses both theoretically and empirically exporters' strategies in response to supply shocks caused by extreme weather events, in addition to demand shocks. Our findings indicate that poor conditions reduce the intensive and extensive margins of trade, as well as prices. Moreover, when shocks occur the exporters concentrate their shipments towards core markets rather than peripheral destinations. In the second chapter, we empirically examine the impact of natural disasters on the composition of exports. We extend the analysis of trade determinants by incorporating these shocks, and comparing their static and dynamic effects. We provide evidence of a significant impact on the intensive margin of traded flows, while the extensive margin and prices do not react to these shocks. This suggests the existence of hysteresis effects in export volumes following environmental shocks. In the last chapter, we estimate how the intensity of natural disasters influence capital inflows. We find a negative relationship, hose magnitude varies by type of disaster and by category of financial flow. Furthermore, weak structural development characteristics, such as low institutional stability, increases the vulnerability of countries to these shocks. These results highlight the importance of the choice of indicators in identifying the transmission channels through which natural disasters affect capital inflows.
ED Sciences de la Vie et de la Santé
Identification and characterisation of new molecular tools to study the Planar Cell Polarity signalling and its role in cognitive processes
by Eloise DANIEL (Neurocentre Magendie)
The defense will take place at 14h30 - Amphithéâtre centre Broca Nouvelle-Aquitaine Centre Broca Nouvelle-Aquitaine 146 rue Léo Saignat 33000 Bordeaux
in front of the jury composed of
- Roseline POIRIER - Maîtresse de conférences - Institut NeuroPSI - UMR9197 - Rapporteur
- Claire RAMPON - Directrice de recherche - Centre de Biologie Intégrative - Rapporteur
- Susanna PIETROPAOLO - Chargée de recherche - Institut de neurosciences cognitives et intégratives d'Aquitaine - Examinateur
- Mathieu WOLFF - Directeur de recherche - Institut de neurosciences cognitives et intégratives d'Aquitaine - Examinateur
A good memory is not just about correctly recalling learned information, but also about encoding memories distinctly from one another and being able to retrieve a complete memory from partial information. These two cognitive processes are pattern separation – or memory discrimination – and pattern completion – or memory generalisation. Both rely on the hippocampus, a brain structure that is crucial for learning, consolidating, and recalling memories. To accomplish these complex tasks, the hippocampus relies on the trisynaptic circuit composed of the entorhinal cortex, the dentate gyrus, and the CA3 region of the hippocampus. These structures can be compromised by alterations in intra- and intercellular signalling, either in adulthood or during normal and pathological ageing, or during the maturation of neural circuits. Numerous studies have shown that receptors, adhesion molecules, or scaffolding proteins may play a role in these memory processes. Among these genes and proteins are members of the planar cell polarity (PCP) signalling pathway. This signalling pathway is conserved and known to shape tissues during development by regulating adhesion complexes and cytoskeletal dynamics. In this project, we are testing the hypothesis that modulation of PCP signalling disrupts the structural organisation of neurons in the dentate gyrus, which regulates specific cognitive processes such as pattern separation and pattern completion. We propose to characterise the role of C-Daam1 truncation – the C-terminal domain of the endogenous Daam1 protein belonging to PCP signalling – in specific brain functions. To do this, we combined molecular and cellular biology approaches with complex hippocampus-dependent behavioural tasks designed to capture the properties and elementary components of declarative memory in animals. Our results show that overexpression of C-Daam1 in adult mice reduces the dendritic complexity of granule cells in the dentate gyrus and neuronal activity in both the dentate gyrus and CA3. Behaviourally, this translates into enhanced mnemonic discrimination (pattern separation) but impaired memory generalisation (pattern completion). In addition, PCP signalling dependent on Daam1 has recently been associated with synaptic dysfunction induced by β-amyloid accumulation, a protein directly involved in Alzheimer's disease. We therefore evaluated the potential effect of C-Daam1 in transgenic mice modelling this pathology. Strikingly, C-Daam1 enables long-term memory maintenance in the early stages of the disease. This project provides new insights into the mechanisms supporting functional memory and opens up new therapeutic avenues for maintaining mnemonic abilities during pathological ageing.
Impact of FMRP deletion on presynaptic mechanisms at hippocampal mossy fiber
by Simon LECOMTE (Institut Interdisciplinaire de Neurosciences)
The defense will take place at 14h30 - Amphithéâtre 2 Rue Dr Hoffmann Martinot, 33000 Bordeaux
in front of the jury composed of
- Andreas FRICK - Directeur de recherche - NEUROCENTRE MAGENDIE - U1215 - Examinateur
- Ingrid BUREAU - Chargée de recherche - INSERM, Unit 1249, INMED, Marseille, France - Rapporteur
- Pierre VINCENT - Directeur de recherche - CNRS UMR 5203 – Inserm U1191, IGF, Université de Montpellier - Rapporteur
- Joana LOURENçO - Chargée de recherche - Institut du Cerveau, Hôpital Pitié-Salpêtrière - Examinateur
Fragile X syndrome (FXS), the most common inherited form of intellectual disability and a major cause of autism spectrum disorder, results from silencing of the Fmr1 gene encoding the RNA-binding protein, FMRP. While most research has focused on dendritic and postsynaptic mechanisms, emerging evidence suggests a presynaptic role of FMRP, particularly through cAMP-dependent signaling pathways. This project investigates how loss of FMRP affects presynaptic mechanisms in the CA3 region of the hippocampus, with a specific emphasis on cAMP-protein kinase A (PKA) signaling. Using patch-clamp electrophysiology and imaging in acute and fixed mouse hippocampal slices with targeted genetic mutations in dentate gyrus cells, I show that presynaptic loss of FMRP disrupts mossy fiber-CA3 synaptic transmission. My results indicate a deregulation of cAMP-PKA signaling and altered presynaptic calcium-dependent mechanisms, providing new insights into the presynaptic contribution of FMRP to synaptic function in FXS.
REVISITING THE EARLY SECRETORY PATHWAY IN PLANT CELL : IDENTIFICATION OF A DYNAMIC TUBULO-VESICULATED ER-GOLGI (ERGIC) THAT MATURE IN GOLGI.
by Louise FOUGERE (Laboratoire de Biogenese Membranaire)
The defense will take place at 13h30 - Amphithéâtre Colette & Josy Bové 71 avenue Edouard Bourlaux, 33140 Villenave d'Ornon INRA Bordeaux Aquitaine
in front of the jury composed of
- Yohann BOUTTE - Directeur de recherche - Université de Bordeaux - Directeur de these
- Farhah ASSAAD - Professeure - Technical University of Munich - Rapporteur
- Hubert SCHALLER - Directeur de recherche - CNRS - Rapporteur
- Marie-Cécile CAILLAUD - Directrice de recherche - CNRS - Examinateur
- Marie BARBERON - Assistant professor - Université de Genève - Examinateur
- Frédéric DELMAS - Maître de conférences - INRAE - Examinateur
In the conventional secretion model, it is assumed that the various cargoes synthesized in the endoplasmic reticulum (ER) pass through the Golgi apparatus and the post-Golgi station called the trans-Golgi network (TGN) before reaching their final destination. The Golgi apparatus is a stack of several cisternae. In animal cells, a single unit of the Golgi apparatus is present in the form of a ribbon and the intermediate ER-Golgi compartment (ERGIC) provides transport between the ER and the Golgi. In plant cells, there are hundreds of mini Golgi apparatus interacting close to the ER. It was therefore thought until now that ERGIC did not exist in plant cells. During my PhD thesis, I used a combination of quantitative monitoring of intracellular compartments in living cells, inducible release from the ER of genetically encoded cargoes and super-resolution microscopy methods to question the existence of ERGIC in plant cells. My results identified a tubulovesicular network at the ER-Golgi interface that interacts dynamically with the ER or Golgi and stabilizes in the vicinity of pre-existing Golgi apparatus. My work has also shown that sphingolipid ceramides play an important role both in the generation of the ERGIC network from the ER and in its stabilization in the Golgi. This stabilization creates a new pre-cisterna of the Golgi apparatus which will become an integrated cisterna of the Golgi. These results completely change our vision of Golgi organization in plant cells and reveal the existence of ERGIC in this kingdom of life, a question that has been hotly debated until now. In addition, this thesis revises the classical transport via vesicles and suggests that ER-Golgi traffic exists through a network of tubules. Following on from these findings, I have undertaken further research to find out whether conventional vesicle COP transporters are found in this network and what the functional role of ERGIC is in plant cell physiology.
ED Sociétés, Politique, Santé Publique
Enabling psychological resources for ecological performance in organizations: The role of organizational climate, character strengths, well-being, and eco-emotions in ecological action within French Small and Middle-sized Enterprises
by Alexis GAY (Laboratoire de Psychologie)
The defense will take place at 14h00 - Amphi Pitres Campus Victoire 3ter Pl. de la Victoire - 33000 Bordeaux
in front of the jury composed of
- Cécile DANTZER - Maîtresse de conférences - Université de Bordeaux - Directeur de these
- Fabien FENOUILLET - Professeur des universités - Université Paris Nanterre - Rapporteur
- Isabelle FAURIE - Professeure des universités - Université Toulouse - Jean Jaures - Rapporteur
- Davy CASTEL - Maître de conférences - Université de Picardie Jules Verne - Examinateur
- Rebecca SHANKLAND - Professeur des universités - Université Lumière Lyon 2 - Examinateur
- Marie-Line FELONNEAU - Professeur émérite - Université de Bordeaux - Examinateur
This thesis focuses on ecological performance in SMEs, examined through the lens of psychosocial resources mobilized at work. It starts from the observation that conventional indicators, which are predominantly techno-economic, struggle to capture the human, cultural, and subjective dynamics that shape organizations' ecological commitment. Three psychological dimensions are explored: character strengths (Peterson & Seligman, 2004), ecological emotions (Albrecht, 2012; Pihkala, 2020), and socio-moral (Pircher Verdorfer et al., 2013) and ecological climate. These are connected with four ecological performance indicators specifically developed for this thesis: pro-ecological behaviors, adherence to the transition project, perceptions of the company's ecological actions, and ecological empowerment. The analysis draws on several empirical studies: two quantitative surveys among SME employees (N > 1600), a pilot study (N = 27), and an intervention-based research study using serious games designed within the framework of this thesis (N = 59). The results show that employees' psychological resources are significant and interdependent levers of ecological commitment, particularly through the alignment of strengths, the regulation of emotions, and the perception of a favorable socio-moral and ecological climate. The thesis thus proposes an analytical framework and intervention tools that make it possible to integrate the subjective dimensions of transition into the evaluation and support of ecological practices in SMEs. It opens theoretical and practical perspectives for an ecology of work grounded in the joint transformation of individuals and organizations.