Résultats de recherche

Une équipe de chercheurs américains, avec l’aide de Frédérik De Laender, professeur au Département de biologie de l’UNamur, vient de publier dans la prestigieuse revue Nature. Leur étude décrit comment l’évolution des températures des cours d’eau et les introductions de poissons par l’humain peuvent modifier la biodiversité des rivières aux États-Unis.

Chaque début d’année académique, le Conseil d’administration octroie un statut de « Fellow NARC » à des chercheurs faisant preuve d’un CV de recherche de haut niveau, ayant reçu récemment un prix ou un financement prestigieux. Retour sur le fellowship du Professeur Frederik De Laender.

En 2021, l’Union européenne s’est lancée dans un chantier titanesque : sauvegarder le génome de toutes les espèces eucaryotes en Europe. Soit l’ensemble du vivant, à l’exception des bactéries et des archées (micro-organismes). Dénommé ERGA, pour European Reference Genome Atlas, et auquel participe l’UNamur grâce à la professeure Alice Dennis, ce projet espère ainsi participer à la sauvegarde de la biodiversité, alors même qu’un cinquième des espèces européennes sont en danger d'extinction.

Le F.R.S.-FNRS vient de publier les résultats de ses différents appels 2024. Appels équipement, crédits et projets de recherche, bourses de doctorat FRIA et Mandant d’Impulsion Scientifique (MIS), les instruments sont nombreux pour soutenir la recherche fondamentale. Découvrez les résultats de l’UNamur en détail.

Catherine Linard, chercheuse du Département de géographie de l’UNamur, a été récompensée pour ses travaux à la croisée de la géographie et de l’épidémiologie. Ce mandat Francqui-Collen lui permettra, dès septembre et pendant trois ans, d’être déchargée de la majeure partie de ses enseignements afin de se consacrer davantage à ses recherches sur l’influence des changements environnementaux sur propagation des maladies infectieuses. 

RésuméIn this work, I aimed at simulating accurately the Raman optical activity (ROA) signatures of flexible solute molecules in their environment. Indeed, these systems are quite challenging due to potentially huge number of conformers, i.e. local minimum on the potential energy surface (PES). Moreover, the environment can drastically change the PES which can be observed on the experimental ROA spectra that vary quite a lot with the conformation of the molecule and its surroundings. In order to tackle this issue, we have designed a hierarchy of methodology named M1, M2, M3. In M1 and M2, the so-called static approach is used: one or more conformers are found, their geometry are reoptimized at the Density Functional Theory (DFT) level, and their vibrational signatures are simulated, usually at the harmonic approximation. The initial list of conformers was obtained by using the CREST algorithm. In M1, the solvent is considered implicitly while in M2, explicit solvent molecules are added around the solute molecule. In M3, we perform an ab-initio molecular dynamics of the solute molecule surrounded by explicit solvent molecules. The spectrum is obtained by evaluation time-correlation functions along the trajectory. Our first systems of interest were cryptophane derivatives. They are flexible cage-like systems made of two hemispheres connected by three -O-(CH2)n-O- (denoted Cr–nnn) linkers that exhibit chiroptical properties. For Cr–111, the smallest cryptophane possible, M1 methodology gave a good agreement with respect to experiment, especially in the fingerprint region. However, we have demonstrated that the relative ratio between the different conformers was strongly impacted by the choice of the exchange-correlation (XC) functional in our DFT calculations demonstrating the sensibility of the description of the PES. Cr–222 molecules have shown to be more flexible, as demonstrated by a greater number of significant conformers. The overall agreement with experiment was also satisfactory. Finally, to test our different approaches (M1-M3), I have performed new ROA measurements of amino acids in water at the University of Bordeaux in the lab of Dr. Daugey. When compared to our simulations, we have clearly seen an improvement on the ROA signatures when explicit water molecules are added in our simulations (M2 vs M1). Unfortunately, M3 method did not perform as expected and further investigations are needed. Overall, I have shown that the PES as described by our various methodologies is very sensitive to various parameters of the simulation such as the XC functional, the number and position of explicit solvent molecules, … and that all these impact strongly the simulated ROA signatures.JuryProf. Francesca CECCHET (UNamur), PrésidenteProf. Vincent LIÉGEOIS (UNamur), SecrétaireProf. Benoît CHAMPAGNE (UNamur)Prof. Carine CLAVAGUÉRA (Université Paris-Saclay)Dr Nicolas DAUGEY (Université de Bordeaux)

RésuméEnvironmental change rarely arrives as a single, isolated event; organisms and communities typically experience one stressor against the backdrop of another already passed. Arunima Sikder's doctoral thesis asks whether an organism's past environment shapes its response to the environment that follows, and whether that influence propagates upward to affect the stability of the communities these organisms belong to.The thesis addresses this question in Synechococcus sp., a globally significant marine primary producer, using thermal and chemical stressors as its two environmental drivers. Working across three levels of biological organisation, the work accounts for how past environments shape responses to subsequent ones arriving in sequence, in fluctuation, or in combination — with functional traits as the common currency for measuring these responses.The results show three things. First, sensitivity to a stressor depends on the sequence of exposure, not on the stressor alone. Second, response diversity predicts community stability only when measured under the community's actual acclimation history, rather than under sustained conditions as convention assumes. Third, an apparent contradiction of biodiversity–ecosystem-function theory — a negative relationship between functional diversity and performance.Together, these findings argue that sensitivity, response diversity, and functional diversity should be treated as state-dependent quantities rather than fixed properties, with consequences for how the performance of biological systems is measured and modelled under increasingly variable environmental regimes.JuryProf. Alice DENNIS (UNamur), PrésidenteProf. Frederik DE LAENDER (UNamur), SecrétaireProf. Maren STRIEBEL (Carl-von-Ossietzky University Oldenburg)Prof. Giulia GHEDINI (Monash University)Prof. Eli THORÉ (UNamur)

L’Université de Stanford a publié un classement prestigieux qui met en lumière les chercheurs les plus influents dans un large éventail de domaines scientifiques. Cette liste, établie sur base de critères bibliographiques, vise à fournir un moyen normalisé d'identifier les leaders scientifiques mondiaux. Il s’agit d’un critère parmi d’autres permettant d’évaluer la qualité de la recherche scientifique. Douze chercheurs de l’Université de Namur en font partie !

Une délégation de l’Université de Namur a participé à une mission exploratoire à l’Université Cheikh Anta Diop (UCAD) de Dakar, au Sénégal. L’objectif : découvrir les recherches menées sur le terrain, rencontrer les chercheurs de l’UCAD et initier de futures collaborations entre les deux institutions.