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Characterization of trehalase from Acyrthosiphon pisum for the design of new insecticides SummaryAphids are major pests in agriculture, causing direct damage to plants and acting as vectors for phytopathogenic viruses. Conventional insecticides are widely used to control them, but their toxicity and efficacy pose problems in terms of the environment, human health and the emergence of resistance to these compounds. New alternatives are therefore needed, such as biological control using predators or parasitoids. However, these methods are not always economically viable on a large scale. As part of this thesis, another approach is being explored which involves developing new insecticides targeting the biochemical functions of aphids.The project aims to discover new inhibitors of trehalase, an enzyme essential for insect energy metabolism. Inhibition of this enzyme could disrupt vital insect functions without affecting mammals. This research involved several stages: the purification and complete characterization of trehalase from Acyrthosiphon pisum (the model for this study), the in vivo, in vitro and in silico analysis of commercial inhibitors on this enzyme, before moving on to the search for new inhibitors. Two points of integrated insect management were explored, biological and chemical control.The biological side saw the study of a strain of Streptomyces naturally producing trehalase-inhibiting metabolites, notably validamycin A, a molecule recognized in the literature as one of the best inhibitors, but not applicable as an insecticide. Other molecules appear to have interesting features, but we have not been able to isolate and characterize them.The chemical side has enabled us to create a pharmacophore hypothesis based on experimental results on molecules obtained by virtual screening. Although these molecules are not usable as insecticides as they stand, this hypothesis provides a better understanding of trehalase inhibitors in general and can be used to refine future analyses. JuryProf. Jean-Yves MATROULE (UNamur), presidentDr Catherine MICHAUX (UNamur), promoter and secretaryProf. Frédéric FRANCIS (ULiège), co-promoterProf. André MATAGNE (ULiège)Dr Rudy CAPARROS (ULiège)Dr Morgan HANS (Biocidal)

Thesis subject Use of BioID within mitochondria: examples with the study of human mitochondrial co-translational import process and with the identification of MPV17 function Summary This thesis was divided into two different parts dedicated to the study of a mitochondrial process and of a mitochondrial protein using a proximity labelling assay called BioID. The first project was dedicated to the study of a poorly characterized process, the mitochondrial co-translational import. In this process, translation is coupled to the translocation of the mitochondrial proteins, alleviating the energy cost typically associated with the post-translational import relying on chaperone systems. However, the mechanisms are still unclear with only few actors identified but none that have been described in mammals yet. We thus profiled endogenously the TOM20 proxisome using BioID. Despite the enrichment of RNA binding proteins in the TOM20 proxisome, we could not demonstrate a role for a selected candidate, LARP4, in the mitochondrial co-translational import process. Nonetheless, additional uses of this BioID cell line were highlighted such as the monitoring of protein entry inside mitochondria and a potential application in the prediction of mitochondrial protein half-life.The second project was dedicated to the study of MPV17, a protein of the inner mitochondrial membrane whose gene is associated with mitochondrial DNA depletion syndrome. However, the exact molecular function of the protein is still unclear. The approach used in this project was to identify the interacting partners of MPV17, using BioID, to get additional clues about the protein function. In this project we demonstrated an interaction of MPV17 with the MICOS complex but the KO of MPV17 didn't impact mitochondria ultrastructure. However, the depletion of MPV17 protein led to increased mitochondria-derived vesicle formation. Therefore, we investigated a potential degradation of the mtDNA as the cause of the mtDNA depletion observed in MPV17 KO cells but, despite a higher mitophagy level in KO cells, the blockade of the lysosomal activity didn't prevent the depletion. Additional in silico analyses suggested a channel activity of MPV17 further supported by its direct interaction with the Cyclophilin D, a protein of the mitochondrial permeability transition pore. Interestingly, MPV17 KO cells also display higher level of mitochondrial calcium which would be related to the degradation of the mtDNA since the blockade of mitochondrial calcium entry prevents the depletion. We thus propose a role of MPV17 as a potential new member of the mitochondrial permeability transition pore whereas in the absence of the protein, the build-up of calcium inside the mitochondria would lead to the observed mtDNA degradation. Jury Prof. Benoît MUYLKENS (UNamur), ChairmanProf. Patsy RENARD (UNamur), Promoter and SecretaryProf. Thierry ARNOULD (UNamur), Co-PromoterProf. Dr. David PLA-MARTIN (Heinrich Heine University Düsseldorf, Germany)Dr. Timothy WAI (Institut Pasteur Paris, France)Prof. David PLA-MARTIN (Heinrich Heine University Düsseldorf, Germany)Dr. Timothy WAI (Institut Pasteur de Paris, France)Prof. Guy LENAERS (Université d'Angers, France)Prof. Sven EYCKERMAN (Universiteit Gent)

Summary: Impact of the UPR pathway on the establishment of the UVB-induced senescent phenotype Skin aging, influenced by a combination of intrinsic and extrinsic factors, leads to damage capable of altering skin functions. Among extrinsic factors, ultraviolet (UV) radiation is responsible for skin photoaging. In particular, these elements lead to an accumulation of senescent cells capable of contributing to the development of age-related pathologies such as skin cancers. Indeed, senescence is accompanied by profound morphological and molecular changes within the cell. This includes a modification of its secretome, which becomes enriched with pro-inflammatory cytokines, growth factors and extracellular matrix remodeling enzymes, altering the characteristics of tissues as they age. Nevertheless, the precise mechanisms leading to the senescent phenotype induced by UVB remain largely unknown. In this context, the main objective of this work was to identify molecular mechanisms underlying the establishment of UVB-induced senescence in normal human dermal fibroblasts (NHDFs), mechanisms that could contribute to skin aging. In vitro, we confirmed that repeated UVB exposures induce premature senescence in NHDFs and that this state is associated with activation of the three branches of the UPR (Unfolded Protein Response) pathway responsible for maintaining homeostasis of the endoplasmic reticulum (ER), the primary secretory compartment. These observations were supported by transcriptomic analysis, revealing regulatory elements linked to major senescence pathways and ER functions in UVB-exposed NHDFs. Subsequently, we showed that the ATF6α branch plays a central role in the occurrence of biomarkers of the UVB-induced senescent phenotype. Indeed, ATF6α invalidation not only protects against UVB-induced morphological changes, but reduces the percentage of SA-βgalactosidase (SA-βgal)-positive cells, prevents persistent DNA damage, and alters the expression of major factors of the senescence-associated secretory phenotype (SASP). As SASP exerts, among other things, a pro-tumoral action, we sought to assess whether the conditioned medium (CM) of UVB-exposed fibroblasts invalidated for ATF6α could impact the migration and invasion potential of melanoma-derived cells. However, we did not observe any ATF6α-dependent pro-migratory or pro-invasive effects.To highlight a potential role for ATF6α in another biological process, we exploited our transcriptomic and secretomic analyses and identified a possible effect of ATF6α on the paracrine control of the skin environment. To explore this, we focused on SASP factors (cytokines and metalloproteases) regulated by ATF6α and whose impact on the tissue environment was known. Next, we treated a reconstructed human epidermis (RHE) model with MC derived from NHDFs exposed to UVB or not, and invalidated or not for ATF6α. Surprisingly, we observed that MC from UVB-exposed NHDFs increased RHE thickness and basal keratinocyte proliferation, via an ATF6α-dependent mechanism. Finally, we identified IL8 as a major paracrine factor involved in this process, since IL-8 blockade by neutralizing antibodies prevents excessive keratinocyte proliferation. In conclusion, we report the role of ATF6α in UVB-induced senescence as well as its impact on the preservation of skin homeostasis under stress conditions notably through the regulation of the expression of SASP components. This suggests that ATF6α and its effectors could be promising targets controlling the effects of skin aging.Abstract: Impact of the UPR pathway on the establishment of the senescent phenotype induced by UVBSkin aging, influenced by a combination of intrinsic and extrinsic factors, can result in damage that has the potential to alter skin functions. Among extrinsic factors, ultraviolet (UV) radiation is responsible for skin photoaging. These factors notably contribute to the accumulation of senescent cells which in turn can contribute to the development of age-related pathologies, including skin cancers. Indeed, senescence is characterized by profound morphological and molecular changes within the cell. This includes a modification of its secretome, which becomes enriched in pro-inflammatory cytokines, growth factors, and matrix-remodeling enzymes, altering tissue characteristics during aging. However, the exact mechanisms driving the senescent phenotype induced by UVB remain largely unknown. In this context, the main objective of this work was to identify the underlying molecular mechanisms responsible for the establishment of UVB-induced senescence in normal human dermal fibroblasts (NHDFs), mechanisms that may play a role in skin aging. In vitro, we confirmed that repeated exposures to UVB induce premature senescence of NHDFs and that this state is associated with the activation of the three branches of the Unfolded Protein Response (UPR), which are responsible for maintaining endoplasmic reticulum (ER) homeostasis, the primary cellular secretion compartment. These observations were supported by transcriptomic analysis, revealing regulatory elements related to major senescence pathways and ER functions in UVB-exposed NHDFs. Subsequently, we demonstrated that the ATF6α branch plays a central role in the development of the UVB-induced senescent phenotype. Indeed, the silencing of ATF6α not only protects against morphological changes induced by UVB, but also reduces the percentage of senescence-associated β-galactosidase (SA-βgal) positive cells, prevents the persistence of DNA damage, and alters the expression of major factors associated with the senescence-associated secretory phenotype (SASP).The SASP, exerting a pro-tumoral action, led us to assess whether the conditioned medium (CM) from UVB-exposed fibroblasts invalidated for ATF6α could impact the migration and invasion potential of melanoma cells. However, we did not observe any ATF6α-dependent pro-migratory or pro-invasive effects. To highlight a potential role of ATF6α in another biological process, we further analyzed our transcriptomic and secretomic analyses and identified a possible effect of ATF6α on the paracrine control of the skin environment. To explore this, we focused on SASP factors (cytokines and metalloproteinases) regulated by ATF6α and whose impact on tissue environment was known. Subsequently, we treated a reconstructed human epidermis (RHE) model with CM from NHDFs exposed or not to UVB and invalidated or not for ATF6α. Surprisingly, we observed that the CM from UVB-exposed NHDFs increased the thickness of the RHE as well as the proliferation of basal keratinocytes, via an ATF6α-dependent mechanism. Finally, we identified IL8 as a major paracrine factor involved in this process, as blocking IL-8 with neutralizing antibodies prevented excessive proliferation of keratinocytes. In conclusion, we report the role of ATF6α in UVB-induced senescence and its impact on the preservation of skin homeostasis under stress conditions, particularly through the regulation of the expression of SASP components. This suggests that ATF6α and its effectors could be promising targets for controlling the effects of skin aging. Jury Prof. Yves POUMAY (Department of Medicine, UNamur), chairmanProf. Florence CHAINIAUX (Department of Biology, UNamur), promoter and secretaryProf. Olivier PLUQUET (Canther, University of Lille), co-promoterProf. Isabelle PETROPULOS (Adaptation Biologique et Vieillissement, Sorbonne Université)Prof. Jérôme LAMARTINE (Laboratoire de Biologie Tissulaire et d'Ingénierie thérapeutique, Université Claude Bernard Lyon 1)Prof. Fabienne FOUFELLE (Maladies métaboliques, diabète et comorbidités, Sorbonne Université)

Initiated in 1969 by Pullmann and Del Re, the congress is an annual meeting to promote collaboration and friendship between Latin-speaking theoretical chemists. In its early years, European researchers were the main contributors. Subsequently, the Latin American community has made a major contribution, with the emergence of teams whose international reputation now extends far beyond our own community.We are delighted to be holding this meeting at the University of Namur, 55 years after the first CHITEL was organised in Paris, France. We are sure that this 2024 edition will once again be an opportunity to take advantage of the good humour and dynamism of Latin to encourage, develop and strengthen scientific exchanges.We look forward to welcoming you at the University of Namur,The CHITEL 2024 Local Organising Committee. Website

EMBO Courses and Workshops are selected for their excellent scientific quality and timelines, provision of good networking activities for all participants and speaker gender diversity (at least 40% of speakers must be from the underrepresented gender). Organisers are encouraged to implement measures to make the meeting environmentally more sustainable.Upon registration - More info and registration on the EMBO website.

On Thursday May 30, for our last Chill&Sciences of the season, Candy Sonvaux and Alexis Coyette, mathematics researchers, invite you to discover the mathematics where the movements of the planets and the spread of viruses intertwine until they impact our society.Chill&Science: enriching encountersWith nearly 20 years' experience of scientific cafés, the Confluent des Savoirs has set up a new concept of scientific encounters. The Chill&Sciences are a unique opportunity for the public to come and discuss and ask questions of experts on research topics related to current affairs and citizen issues.Come and enjoy the unique, relaxed atmosphere of Quai22. Researchers and experts from the seven faculties of the University of Namur will present their research and discuss with you over a drink (or two, but never without exaggeration).In practiceThe meetings are open to everyone aged 16 and over. Evenings are limited to around 20 people to ensure a relaxed atmosphere and to facilitate discussions. Meetings take place if a minimum of 10 people are registered. Except in exceptional circumstances, meetings take place every 2 months at the University of Namur's cultural space, Quai22, located at n°22 Rue du Séminaire.Tarif Participation in a Chill&Sciences costs 5€. A discounted annual pass is available. Please note: preferential rate for students (discount code: PromoCDS).The booking fee includes a drink* (soft or beer), a snack (chips and cookies) and management fees linked to the organization Unless cancelled by us, bookings are non-refundable. (*additional drinks will be available upon electronic payment.)

Title of the dissertation: Ion implantation in Low-E coatings Low-emissivity (Low-E) coating technology revolutionizes glass applications for windows, offering high optical transparency while reducing heat transfer. They consist of a silver-based thin film deposited on a glass panel by physical vapor deposition. However, these coatings are fragile and must be placed inside a double-glazing cavity where an inert gas resides. Otherwise, they can be easily degraded by bad atmospheric conditions.The thesis approach is to combine low-E technology with a post-treatment of ion implantation. The research question driving this thesis is: how does ion implantation enhance the durability of low-E coatings containing silver?The experiments conducted during the thesis show that implantation indeed increases the coating resistance while having a small impact on its color. However, the treatment degrades the thermal insulation properties. Hence, a series of hypotheses are formulated based on the literature to explain and control this behavior.A deeper investigation shows that implantation impacts the silver nanostructure. First by dewetting the film which allows reorganization into larger crystallites, second by forcing silver mixing at its interface through ballistic ejections. These two phenomena increase the toughness of the silver interface by interlocking effects. However, dewetting has also been linked to thermal insulation properties degradation. Nonetheless, it was shown that using light gas implantation limits the destructive effect (dewetting) while still inducing good durability (due to interface mixing).. Jury Prof. Julien COLAUX (UNamur), presidentProf. Stéphane LUCAS (UNamur), promoter and secretaryDr Amory JACQUES (Service Public de Wallonie)Dr Philippe ROQUINY (AGC Glass Europe)Prof. Rony SNYDERS (University of Mons)

Dear teachers, We are pleased to invite you to a unique educational experience at the Antoine Thomas Astronomical Observatory. Offer your students the opportunity to discover the Antoine Thomas Astronomical Observatory, an observatory built on the very site where the Jesuit fathers established their own observation, training and research dome in the 19th century. Located in downtown Namur, in the heart of the university, our observatory is equipped with state-of-the-art instruments, for both night-time and daytime observation, with one of Belgium's largest solar telescopes. A visit to the observatory allows you to discover how astronomy is practiced today and - weather conditions permitting - to observe the sun in complete safety. Plan your visit today! To organize a school visit, please complete the registration form available on our website. Practical information:Guided tour 1ère to 6ème secondaire 1:30 pm to 2:30 pm or 3:00 pm to 4:00 pm Faculty of Medicine - Place du Palais de Justice, Namur Gratuit - Sur inscription The observatory is not accessible to people with reduced mobility Next date:February 11, 2025This activity is organized with the support of Wallonie Recherche. Visit registration

Dear teachers, We are pleased to invite you to a unique educational experience at the Antoine Thomas Astronomical Observatory. Offer your students the opportunity to discover the Antoine Thomas Astronomical Observatory, an observatory built on the very site where the Jesuit fathers established their own observation, training and research dome in the 19th century. Located in downtown Namur, in the heart of the university, our observatory is equipped with state-of-the-art instruments, for both night-time and daytime observation, with one of Belgium's largest solar telescopes. A visit to the observatory allows you to discover how astronomy is practiced today and - weather conditions permitting - to observe the sun in complete safety. Plan your visit today! To organize a school visit, please complete the registration form available on our website. Practical information:Guided tour 1ère to 6ème secondaire 1:30 pm to 2:30 pm or 3:00 pm to 4:00 pm Faculty of Medicine - Place du Palais de Justice, Namur Free - On registration The observatory is not accessible to people with reduced mobility This activity is organized with the support of Wallonie Recherche. Visit registration

JuryProf. Nicolas DENDONCKER (UNamur), PresidentProf. Sabine HENRY (UNamur), SecretaryDr. Sébastien DUJARDIN (UNamur)Prof. Pierre OZER (ULiège)Prof. Emmanuel TWARABAMENYE (University of Rwanda)Prof. Caroline MICHELLIER (MRAC and UCLouvain)AbstractThis research investigates community vulnerability to landslides and floods in Northwestern Rwanda, hazards that frequently interact to produce compound disasters. The research focused on understanding the institutional, social, and structural factors that shape vulnerability and adaptive capacity in this disaster-prone region. Using a mixed-methods approach at local-scale, including institutional analysis, household surveys (n = 904), and field observations, the research highlights how vulnerability is shaped by socio-economic conditions, weak institutional coordination, and limited adaptive capacity. A Contextualized Vulnerability Index (CoVI) was developed to map vulnerability patterns, revealing particularly high vulnerability in landslide-prone and dual-hazard zones. The analysis of adaptive capacity showed that while awareness of hazards is high due to lived experiences, financial constraints, and limited technical knowledge hinder communities' ability to adapt effectively. The study contributes to the literature on social vulnerability and disaster risk reduction by emphasizing the importance of locally grounded, evidence-based strategies to strengthen community resilience in hazard-prone regions.

JuryProf. Eli THORÉ (UNamur), PresidentProf. Patrick KESTEMONT (UNamur), SecretaryProf. Ranjàna RANDRIANARIVO (Université d'Antananarivo)Dr. Valérie CORNET (UNamur)Dr. Omayma MISSAWI (UNamur)Prof. Catherine MOUNEYRAC (Université Catholique de l'Ouest)Prof. Gauthier EPPE (ULiège)SummaryThe widespread production and use of plastics have led to their continuous release into the environment. Microplastics (MPs) are now ubiquitous in aquatic ecosystems, where their bioavailability to organisms and potential entry into the food web raise serious environmental and public health concerns. Substantial progress has been made in understanding MP toxicity, and their hazardous potential is now widely acknowledged. However, MP toxicity studies remain complex, as multiple particle characteristics, such as size, shape, polymer type, and sorbed contaminants might influence both bioavailabilityTo bridge this gap, the present thesis adopted a dual, complementary approach: (i) characterizing the environmental occurrence and bioavailability of MPs, and (ii) assessing the ecological relevance of using environmentally derived MPs in in vivo toxicity experiments.Overall, this thesis provides insights into the reproductive and transgenerational effects of environmentally relevant MPs while underscoring the importance of considering particle-pollutant interactions. By combining in situ field data with in vivo laboratory experiments, it demonstrates that the use of environmentally derived MPs represents a more realistic and ecologically meaningful approach to hazard characterization. Further studies should be carried out in this same perspective to generate robust, exploitable data and contribute to establishing a comprehensive MP risk characterization.

The biodiversity crisis is not only destroying nature: it also threatens our societies, our well-being, and our survival. Based on scientific assessments and findings from IPBES, this Francqui Chair explores our toxic relationship with nature, the global failure to protect it, and the multiple values of living organisms. We will examine ways to recognize these values, repair our relationship, and bring about the transformative change that is needed.Keen to put the protection of ecosystems back at the center of public debate, UNamur is organizing a second Francqui Chair in Law this academic year with Professor Delphine Misonne on a related theme: "Need for the environment, need for law?"Free event upon registration.  More information and full program I'm signing up