Résultats de recherche

Cet événement sera consacré aux progrès en matière d'alimentation, de nutrition et de santé dans le cadre d'un système allant de la ferme à la table. Des sessions plénières, des ateliers et des visites de centres de recherche et d’universités seront également organisés. Cet événement unique sera l'occasion :D'explorer des solutions durablesDe découvrir l'expertise scientifique de la Wallonie,D'accéder aux dernières recherches et innovations dans le secteur,D'échanger avec des experts internationaux et développer votre réseau,De collaborer à des projets concrets pour avoir un impact positif et durable.2 jours avec plus de 150 participants internationaux et entreprises belges. L'inscription est gratuite mais obligatoire.Plus d'infos, inscriptions et programme complet ICI ! 

Jury Prof. Benoît MUYLKENS (URVI, Université de Namur), PrésidentProf. Carine MICHIELS (URBC, Université de Namur), SecrétaireProf. Xavier DE BOLLE (URBC, Université de Namur)Prof. René REZSOHAZY (LIBST, Université catholique de Louvain)Prof. Florian STEINER (Dept. of Molecular and Cellular Biology, Université de Genève)Prof. Germano CECERE (Department of developmental and Stem Cell Biology, Institut Pasteur) Résumé Chez les animaux, les cellules germinales se distinguent souvent des lignées somatiques dès les premières étapes de l'embryogenèse. Dans certains organismes, les blastomères germinaux semblent entrer dans un état de quiescence transcriptionnelle. Par exemple, chez le ver Caenorhabditis elegans, la transcription est activée dans les blastomères somatiques dès le stade 4 cellules, alors qu’elle ne s’initie dans les blastomères germinaux qu’au stade 100 cellules. Cette répression transcriptionnelle dans les blastomères germinaux a été attribuée à la protéine PIE-1, spécifiquement localisée dans ces cellules dès la première division embryonnaire. PIE-1 aurait pour rôle d’inhiber l’activité de CDK-9, une kinase dépendante des cyclines, jusque-là considérée comme essentielle pour la phosphorylation de la sérine 2 (CTD-Ser2) du domaine C-terminal (CTD) de l’ARN polymérase II et pour l’élongation de la transcription. Cependant, des études récentes, montrant que l’embryogenèse se déroule normalement dans une souche mutante exprimant un CTD dans lequel la sérines 2 est remplacée par une alanine (CTD-S2A) et identifiant CDK-12 comme la principale kinase phosphorylant la CTD-Ser2, remettent en question ce modèle.Pour étudier le transcriptome des blastomères germinaux chez le ver C. elegans, une approche combinant tri cellulaire et séquençage de l’ARN (RNA-seq) a été développée. Des analyses pilotes ont validé cette méthode sur une souche wild-type, permettant ainsi son utilisation sur une souche dans laquelle PIE-1 peut être spécifiquement dégradé grâce au système AID (Auxin-Inducible Degron). Cela a permis d’examiner l’effet de la déplétion de PIE-1 sur le transcriptome des blastomères germinaux révélant ainsi qu’en son absence, les blastomères germinaux adoptent un profil transcriptionnel proche de celui des blastomères somatiques, confirmant le rôle fondamental de PIE-1 dans la préservation de l’identité germinale durant l’embryogenèse. En parallèle, la levure de fission Schizosaccharomyces pombe a été utilisée pour analyser les conséquences de l’expression de PIE-1 dans un organisme hétérologue. Les résultats ont montré que PIE-1 en se localisant près des sites de fin de transcription induit une poursuite de la transcription par l’ARN polymérase II au-delà du site de terminaison, conduisant à une transcription de régions intergéniques.  Ces observations ont permis de formuler l’hypothèse que chez C. elegans, au sein des blastomères germinaux, PIE-1 pourrait réguler la polyadénylation alternative dans les régions 3' non traduites, produisant ainsi des isoformes d’ARN plus longs, susceptibles d’être dégradés. En l’absence de PIE-1, des isoformes plus courts pourraient être générés, permettant ainsi l’accumulation de transcrits somatiques et potentiellement la dégradation des ARNm maternels via la traduction de protéines somatiques. Bien que des investigations supplémentaires soient nécessaires chez C. elegans pour valider cette hypothèse, elle fournit un cadre conceptuel innovant pour comprendre le rôle de PIE-1, indépendamment de la phosphorylation de la CTD-Ser2. 

Jury Prof. Marielle BOONEN (UNamur), présidenteProf. Henri-François RENARD (UNamur), secrétaireProf. Claire HIVROZ (PSL University)Prof. Michel GHISLAIN (UCLouvain)Prof. Pierre VAN DER BRUGGEN (UCLouvain)Prof. Ludger JOHANNES (PSL University)Prof. Pierre MORSOMME (UCLouvain) Résumé Clathrin-independent endocytosis (CIE) mediates the cellular uptake of endogenous and exogenous cargoes, including bacterial toxins and viruses. Endophilin A3-mediated endocytosis is a specific CIE mechanism that differs from fast endophilin-mediated endocytosis (FEME), with ALCAM and L1CAM being the first confirmed Endophilin A3-specific cargoes. Here, we report ICAM1 as a new Endophilin A3-dependent endocytic cargo. ALCAM and ICAM1 are important components of immune synapses (IS), which are polarized structures formed between immune cells and target cells, such as cancer cells. These molecules transduce essential co-stimulatory signals to T cells to help their effective activation and proliferation. We find that both ALCAM and ICAM1 serve as cargoes for retromer-dependent retrograde transport to the trans-Golgi network (TGN) in cancer cells. Interestingly, disrupting Endophilin A3-mediated endocytosis or retromer-dependent retrograde transport machinery impairs activation of autologous cytotoxic CD8 T cells, likely by affecting the polarized redistribution of immune synapse components at the plasma membrane. Altogether, our findings demonstrate that CIE and retrograde transport are key pathways in cancer cells that promote the activation of cytotoxic CD8 T cells.

Jury Prof. Yves CAUDANO (UNamur), présidentProf. André FÜZFA (UNamur), secrétaireProf. Dominique LAMBERT (UNamur)Dr Jérémy REKIER (Observatoire royal de Belgique et UCLouvain)Prof. Dr Félix FINSTER (Regensburg University) Résumé Sonder l'Univers avec un voilier solaire relativiste ou des fermions d’Einstein-DiracL' Univers exerce sur l'homme une curiosité à la fois indéniable et fondamentale. Pour percer les mystères du Cosmos, l’homme est conduit  à développer deux grandes stratégies d'investigation : une exploration directe par l'envoie de sondes spatiales, et une exploration indirecte par l’observation des champs électromagnétiques cosmiques, des ondes gravitationnelles  ou de particules telles que les fermions.Suivant ces deux stratégie, nous développons dans cette thèse, dans la première approche (consistant à envoyer une sonde spatiale),  un modèle cinématique et dynamique relativiste de voiles photoniques (light sails) ayant une réflectivité et une absorbance arbitraires, se déplaçant de manière non rectiligne dans le but d’explorer l’espace interstellaire. Le problème consiste à déterminer la trajectoire de la voile dans un espace-temps de Minkowski, une variété à quatre dimensions. À partir de calculs détaillés, nous obtenons la ligne d’univers de la voile dans le référentiel du laser en fonction du temps propre de la voile.La seconde approche applique le formalisme à deux vecteurs d’état (Two-State Vector Formalism) et les mesures faibles à un cadre cosmologique homogène et isotrope. En couplant les spineurs de Dirac à la gravité classique, nous calculons les valeurs faibles du tenseur énergie-impulsion, de la composante Z du spin ainsi que celles des états purs. Prolongeant les travaux de Finster et Hainzl sur la cosmologie d’Einstein-Dirac, nous montrons que l’expansion accélérée de l’Univers peut être interprétée comme une conséquence de la post-sélection. Nous démontrons également que les mesures faibles peuvent amplifier les signaux au moyen d’un équipement plus simple, grâce à une sélection judicieuse des vecteurs d’état initial et final. En outre, ce procédé met en évidence certaines propriétés géométriques de l'espace tridimensionel du Cosmos, offrant une nouvelle manière d’explorer la structure de l’Univers.Nous examinons également la structure mathématique sur laquelle repose l’équation de Dirac au-delà de la dimension et de la signature habituelles. Cela révèle une riche symétrie interne et donne lieu à une représentation diagrammatique particulièrement esthétique. Abstract Probing the Universe with a Relativistic Light Sail or Einstein-Dirac FermionsHumanity’s profound curiosity about the cosmos is both undeniable and fundamental. To demystify the Universe, humankind is compelled to develop both direct and indirect probing strategies: direct exploration through physical visits using probes, and indirect exploration by observing cosmic electromagnetic field, gravitational waves and particles such as fermions.Building on these two strategies, this thesis proposes two distinct approaches to probing the Universe. In the first approach, we present a relativistic kinematic and dynamic model of light sails with arbitrary reflectivity and absorptance, undergoing non-rectilinear motion as a method of interstellar exploration. The problem involves solving for the trajectory of the sail in a 4-dimensional Minkowski spacetime manifold. By detailed computation, we derive the worldline of the sail in the laser’s frame in the sail’s proper time.The second approach applies the Two-State Vector Formalism and weak measurements to a spatially homogeneous and isotropic cosmological framework. Coupling Dirac spinors with classical gravity, we compute weak values of the energy-momentum tensor, the Z-component of spin, and pure states. Extending the work of Finster and Hainzl on Einstein-Dirac cosmology, we demonstrate that the Universe’s accelerated expansion can be interpreted as a consequence of post-selection. We show also that weak measurements can amplify signals with simpler equipment by carefully selecting initial and final state vectors. This process also reveals geometric properties of the spacelike three-manifold of the Cosmos, opening new way on probing the structure of the Universe.We explore also the mathematical framework underlying the Dirac equation beyond the standard dimension and signature. This enterprise reveals its symmetric rich properties and aesthetic diagrammatic representation.

Charting the DNA methylome landscape in cancer, chronic disease and phenotype Abstract: Our team has developed some of the first pipelines for genome-scale DNA methylation analysis. Our work has revealed aberrant methylation and expression patterns in several cancer types and revealed new mechanism of epigenetic regulation in cancer cells. We are now applying cutting-edge whole genome scale DNA methylation analysis in tissues as well as well as in cell free DNA (epigenetic liquid biopsy) and epigenetic editing platforms to investigate clinically relevant biomedical questions in cancer (for example, methylation map of colorectal, prostate, lung cancer and pancreatic cancer patients). Our work in epigenetic editing has implication in revealing causal function and new epigenetic regulation. In this talk, I will present the key findings from some of our works over the years and also elaborate on some recent and future directions in understanding the role of DNA methylation events in cancer metastasis, early detection, and treatment monitoring in solid cancers and also in chronic diseases and phenotype. More information on the ILEE website

High-Sensitivity Birefringence Mapping Using Near-Circularly Polarized Light I will describe several techniques for mapping a two-dimensional birefringence distribution, which can be classified according to the optical schemes and principles of work:Illumination geometry (transmitted light/reflected light)Image acquisition (sequential acquisition/simultaneous acquisition)Polarization control (electrically controlled variable retardance/mechanical rotation).This classification facilitates a comparative analysis of the capabilities and limitations in these methods for birefringence characterization. Polychromatic polarizing microscopy (PPM) provides unique capabilities to alternative methods. It leverages vector interference to generate vivid, full-spectrum colors at extremely low retardances, down to < 10 nm. PPM is a significant departure from conventional polarizing microscopes that rely on Newton interference, which requires retardances above 400 nm for color formation. Furthermore, PPM's color output directly reflects the orientation of the birefringent material, a feature absent in conventional microscopy where color is solely determined by retardance.Joint seminar of ILEE & NISM!Le séminaire est accessible à des personnes externes également, pas besoin de s'inscrire. Plus d'infos

Abstract Radiotherapy is a cornerstone of cancer treatment and is currently administered to approximately half of all cancer patients. However, the cytotoxic effects of ionizing radiation on normal tissues represent a major limitation, as they restrict the dose that can be safely delivered to patients and, consequently, reduce the likelihood of effective tumor control. In this context, delivering radiation at ultra-high dose rates (UHDR, > 40 Gy/s) is gaining increasing attention due to its potential to spare healthy tissues surrounding the tumor and to prevent radiation-induced side effects, as compared to conventional dose rates (CONV, on the order of Gy/min).The mechanism underlying this protective effect—termed the FLASH effect—remains elusive, driving intensive research to elucidate the biological processes triggered by this type of irradiation.In vitro models offer a valuable tool to support this research, allowing for the efficient screening of various beam parameters and biological responses in a time- and cost-effective manner. In this study, multicellular tumor spheroids and normal cells were exposed to proton irradiation at UHDR to evaluate its effectiveness in controlling tumor growth and its cytotoxic impact on healthy tissues, respectively.We report that UHDR and CONV irradiation induced a comparable growth delay in 3D tumor spheroids, suggesting similar efficacy in tumor control. In normal cells, both dose rates induced similar levels of senescence; however, UHDR irradiation led to lower apoptosis induction at clinically relevant doses and early time points post-irradiation.Taken together, these findings further highlight the potential of UHDR irradiation to modulate the response of normal tissues while maintaining comparable tumor control.JuryProf. Thomas BALLIGAND (UNamur), PrésidentProf. Stéphane LUCAS (UNamur), SecrétaireProf. Carine MICHIELS (UNamur)Dr Sébastien PENNINCKX (Hôpital Universitaire de Bruxelles)Prof. Cristian FERNANDEZ (Université de Bern)Dr Rudi LABARBE (IBA)

Abstract Due to their unique chemical, physical and photophysical properties, organoboron compounds and in particular triarylboranes play a central role in chemistry and in catalysis. Trivalent neutral boron Lewis acids, which are planar trigonal species, have been shown to exhibit enhanced Lewis acidity and electrophilicities when constrained in a pyramidal trigonal environment. Within the context of the emerging area of geometrically constrained main-group elements, the fundamental experimental and computational investigations of the impact of structural deformation on the physicochemical properties and reactivity of borane derivatives is of interest. This thesis will explore successively the development of geometrically constrained intramolecular FLP and of cationic boron Lewis superacid based on the aza-boratriptycene scaffold, then the synthesis of pyramidalyzed electron-deficient borenium cation with tethered pyridine and NHC ligands embedded in the triptycene scaffold and will finally focus on chiral borenium cations as new Lewis acids. A collaborative work dealing with the combination of the strong 9-sulfonium-10-boratriptycene with hindered Lewis bases is finally performed for developing latent FLP. This work deepens our understanding of the synthesis of constrained boron Lewis acids species, a key step to develop new pyramidal boron Lewis superacids, deblocking new kinds of reactivity in main-group chemistry. For instance, electrophilic Csp2–H borylation reactions of electron-poor aromatics were observed, new unusual binding mode at weakly coordinating anions were discovered and encouraging steps were initiated for reaching new chiral boron-based Lewis acids, opening the path toward new horizons in main-group chemistry.JuryProf. Benoît CHAMPAGNE (UNamur), PrésidentProf. Guillaume BERIONNI (UNamur), SecrétaireProf. Olivier CHUZEL (Aix-Marseille Université)Prof. Raphaël ROBIETTE (UCLouvain)Prof. Stéphane VINCENT (UNamur)

The scientific programme will include 14 academics presenting their work during keynote lectures, a series of oral communications presented by tenured professors, experienced researchers, PhD students or postdoctoral fellows, and two poster sessions. More information and registration

JuryProf. Alexandre MAUROY (UNamur), présidentProf. Timoteo CARLETTI (UNamur), promoteur et secrétaireProf. Malbor ASLLANI (Florida State University)Prof. Renaud LAMBIOTTE (Oxford Mathematical Institute)Prof. Filippo COLOMO (Università degli studi di Firenze)Prof. Christian WALMSLEY HAGENDORF (UCLouvain)RésuméFlocks of birds, people clapping in unison or the World Wide Web are some instances of complex systems in which a large number of entities interact with each other and produce some emergent phenomena. In this thesis, we pay special attention to two such complex systems, namely crowded random walks on networks, and domino tilings and vertex models. In recent years, networks and generalizations thereof have emerged as an efficient tool to model the pattern of interactions among a set of entities. Examples include social networks, transportation networks and ecological networks. A cornerstone of network science is the interplay between network structure and dynamics on networks. Among those dynamical processes, random walks play a central role. In the first part of this thesis, we study the dynamics of multiple random walkers moving across the nodes of the network, assuming the latter to be endowed with limited available space. We characterize, both analytically and numerically, the stationary states, and we subsequently apply the latter framework to a real ecological network. In the second part of the thesis, we move on to the study of the arctic curve phenomenon arising in domino tilings of double Aztec rectangles and configurations of the six-vertex model with partial domain wall boundary conditions. The latter two models manifest in the scaling limit a spatial phase separation between ordered regions and a central disordered region. We compute the arctic curve of the aforementioned models using the tangent method.

Consanguinity refers to the offspring produced from the union of two closely related individuals who share at least one common ancestor (Temaj et al. 2022). Some communities have high rates of consanguineous marriages, especially in the Middle East, where consanguinity rates of first-cousin marriages vary in Gulf countries from 20 to 50 % (Ben-Omran et al. 2020). This high rate of consanguineous marriages is due to cultural, geographical, historical, financial, political, or religious reasons (Temaj et al. 2022) (Ben-Omran et al. 2020).Consanguinity increases the chance/risk/probability to be homozygous for rare mutations in the general population (Temaj et al. 2022). These mutations can cause recessive autosomal pathologies that may be extremely rare known as rare diseases (Temaj et al. 2022). In many Middle Eastern populations, consanguineous relationships are very common, providing geneticists with a valuable source for discovering "new" genes and identifying their functions (Ben-Omran et al. 2020). Identifying these genes can help carry out diagnostic and predictive tests (genetic counseling) in affected families (Ben-Omran et al. 2020; Temaj et al. 2022). In some cases, understanding the pathophysiological mechanisms involved in diseases can also lead to new therapeutic strategies (Salzberg 2018).In recent years, the development of Next Generation Sequencing (NGS) technologies has led to a faster identification of genes involved in rare diseases (Lal et al. 2016). Sequencing the entire genome (Whole Genome Sequencing, WGS) or the exome (Whole Exome sequencing, WES) can be achieved quickly and inexpensively (Salzberg 2018).Rare diseases are Mendelian monogenic diseases, that result from specific pathogenic variants in single genes, called germline mutations. These mutations occurring in the coding or the non-coding regions in the gene, can be inherited in dominant, recessive, or X-linked transmission modes within a family (Tukker et al. 2021). Coding sequences, known as exons, directly encode the amino acid sequence of proteins essential for various cellular functions, including enzymatic reactions, cell signaling, and structural support. Pathogenic variants within coding sequences can lead to significant disruptions and alterations in the protein structure, function, and stability (Li et al. 2013).  However non-coding sequences that represents around 98% of the entire human genome, include introns, enhancers, promotors, and regulatory elements that regulate genes’ expression. The presence of a pathogenic variant in one of these regions can alter mRNA processing and gene expression and disrupt the delicate balance of gene regulation. REFERENCEWhile coding regions, constitutes around 1 to 2% of the entire genome, , the precise functions of non-coding regions are still unraveled (Moyon et al. 2022).Our project has two main objectives.A) Firstly, to identify the pathogenic variant responsible for a syndromic neurodevelopmental disorder (NDD) in a young boy from a consanguineous Lebanese family. This step was achieved in 2020 and our results were published in Clinical Genetics. Indeed, a homozygous stop gain mutation in the BOD1 gene (p.R151*) was identified and was shown to be involved in the disease observed in this family. BOD1 is a crucial protein that inhibits the PP2A-B56 phosphatase at the kinetochore, which regulates the recruitment of various proteins (such as PLK1: Polo like Kinase 1 ) to ensure proper chromosome orientation during mitosis (Porter et al. 2013). Additionally, BOD1 is a part of a cytosolic variant of the SET1B/COMPASS complex, which affects the expression of genes related to fatty acid metabolism (Wang et al. 2017). Studies in Drosophila have shown that BOD1 depletion in neurons causes synapse morphological abnormalities and learning defects (Esmaeeli-Nieh et al. 2016). Moreover, BOD1 was described to be responsible for ataxic-like behaviors in mice with conditional in what tissue? Knock-Out (KO) of exon 2 of this gene in the lobes IV-V of the cerebellum  (Liu et al. 2022). On another note, a homozygous nonsense mutation in BOD1 gene (p.R112*) was identified in two related Iranian females, who were diagnosed with moderate form of ID (Intellectual Disability) and primary/secondary amenorrhea (Esmaeeli-Nieh et al. 2016).B) Secondly, we aimed to study the effect of the p.R151* mutation in BOD1 gene on protein expression. To achieve this, we used the CRISPR-Cas9 genome editing technique to create a knock-in (KI) of the mutation in HEK293T cells. We then analyzed the effect of this mutation on the expression of Bod1 protein using Western blot technique. Furthermore, we wanted to investigate the physiological and developmental function of the BOD1 gene. For this purpose, we have generated a conditional knock-out cKO mouse model.

Entrez dans l’univers fascinant de la Space Week Namur 2024 ! Préparez-vous à un voyage extraordinaire à travers les étoiles et les mystères de l’espace. Voici le programme de cette semaine cosmique : Expositions “Objectif étoiles” : Avec cette exposition d'astrophotographie, plongez dans un océan d’étoiles scintillantes et laissez vous émerveiller par les secrets de notre galaxie. “Stellar Scape” :  Une aventure immersive où l'art et les sciences vous transporteront au cœur des paysages stellaires, où chaque étoile raconte une histoire. Événements "Mission ISS : Improvisation Space Station" :  Un spectacle de l’ImproNam, le kot-à-projet namurois d’improvisation théâtrale."Rencontre des astronautes" : Une chance unique pour les jeunes explorateurs de rencontrer des héros de l’espace et d’écouter leurs récits d’aventures au-delà de notre monde. “Mercredi des Savoirs” : Des ateliers interactifs pour les jeunes esprits curieux, prêts à découvrir les merveilles de la science.“Chill & Sciences” : Un moment convivial pour discuter avec un chercheur et un artiste, et explorer les mystères de l’univers. "Premier contact - Arrival" : Un ciné-rencontre proposé par le Caméo et Le Pavillon. "5 ans de l'Observatoire astronomique Antoine Thomas"Visites Visite de l’Observatoire astronomique Antoine Thomas : Une expédition guidée pour percer les secrets de l’observation astronomique et contempler les merveilles du cosmos. Ne manquez pas cette opportunité de plonger dans un univers fantastique et de partager des moments inoubliables avec des passionnés de tous horizons. Rendez-vous à Namur du 7 au 12 octobre 2024 pour la Space Week ! 🚀✨  Cliquez ici pour télécharger le programme et pour vous inscrire aux activités