This study presents findings from the opportunistic cruise, which performed microplastic and chemical contaminant sampling in surface waters, sediments, and ice in a sector of the western Arctic and the southwestern part of the Antarctic Peninsula. Microplastics were detected in 100 % of the samples. Floating microplastic densities (100–5000 μm) reached up to 314,251 items/km2 in Antarctica and 63,593 items/km2 in the Arctic. The smallest particles (100–300 μm) dominated in southwestern Antarctic Peninsula (97 %) where the fibers (80 %) and fragments (19 %) were the main components. In the eastern Arctic, the two size classes (100–300 μm and 300–1000 μm) were more evenly distributed (58 % and 40 % respectively) and polymer diversity. Sediment microplastic concentrations were higher in the Arctic (up to 470 items/kg) compared to southwestern Antarctic Peninsula (maximum 399 items/kg). OrganoPhosphate Esters and PhthAlate Esters were also measured for the first time in southwestern Antarctic Peninsula seawater (35.18 ±18.31 ng/L and 72.68 ± 39.71 ng/L, respectively) and ice (50.44 ±24.79 ng/L and 16.72 ±11.46 ng/L, respectively). This study demonstrates the utility of cruise ship-based sampling for monitoring remote regions and it contributes critical baseline data for global microplastic assessments.

Helioseismology infers the interior of the Sun from oscillations which are continuously excited by near-surface turbulent convection and observed in the photosphere. Global helioseismology reconstructs global structures from free oscillations which manifest as ridges in power spectrums of Dopplergrams. On the other hand, techniques in local helioseismology, e.g. time-distance helioseismology and far-side helioseismic holography, are based on correlation of Dopplergrams to reconstruct local perturbations (e.g. in flow and sound speed). After choosing a mathematical equation together with boundary conditions to model oscillations, for global seismology, an eigensolver needs to be constructed, while for correlation-based techniques, be this qualitative or quantitative, Born approximation or iterative, a wave solver to compute Green's kernel is required. In this talk, I will give an overview of various Green's kernels we have obtained. These results are achieved with in-house software Hawen, which solves scalar and vector equations modeling solar waves, for backgrounds ranging from radially symmetric standard models with or without Cowling approximation, to differential rotation. The equations with radially symmetric backgrounds are solved in 1D via spherical harmonics decomposition, the ones with differential rotation in 2D via azimuthal decomposition, and general backgrounds without flow and rotation in 3D. These direct solvers serve as essential steps towards inversion, in particular full-wave form inversion. As a first validation, our power spectrums computed for model S show ridges in agreement with HMI observation. Secondly, in simulations with realistic differential rotation, our spectrums reproduce the observed splitting in azimuthal modes due to rotation.

The objective of this PhD. project was to synthetize original electron-rich ligands containing iminophosphorane moieties and evaluate their potential to develop earth abundant metal (3d) complexes for applications in molecular catalysis.Initially, a thorough experimental study paired with theoretical calculations (calculations done by Prof. A. Monari) investigated the electronic properties of bidentate iminophosphorane ligands, especially the influence of the nitrogen’s substituents on electron donation of this function. Four bidentate iminophosphorane-phosphine ligands with different substituents on the nitrogen (i.e. isopropyl, phenyl, trimethylsilane or hydrogen groups) were synthetized for this purpose. They were then coordinated to palladium(II) precursors to form square planar diamagnetic complexes. Introducing one or two isonitrile probes into the complexes allowed for the appraisal of the donation of the iminophosphoranes. This study underlined the importance of the choice of the nitrogen’s substituent on the electron donation potential of iminophosphoranes. Later, this was exemplified in the synthesis of different tridentate iminophosphorane ligands for molecular catalysis applications.A series of three neutral NNN ligands featuring an iminophosphorane (with three different phosphine groups: triethyl, triphenyl or tricyclohexyl phosphine), a central amine and a pyridine, was designed and coordinated to iron(II), cobalt(II) and manganese(II). Theses complexes were all proven active in the catalytic transfer hydrogenation of ketones with low catalytic loadings (1 mol%). Given the scarcity of examples of CoII and MnII catalysts for this reaction, we focused our study on these complexes. They were efficient on a large scope of ketones. Despite the paramagnetism of the involved species, some additional experiments were conducted to get an insight into the mechanism of this catalytic reaction. They suggest a metal-hydride complex as the active catalyst.In parallel, an original anionic ONP ligand bearing a hydroxy moiety, a central iminophosphorane and a phosphine was synthetized and was successfully coordinated to nickel(II) metal precursors. These complexes were very efficient in the catalytic hydrosilylation of olefins (with an anti-Markovnikov selectivity) and even ketones, with low catalytic loadings (1 mol%), at room temperature in 1 hour. This contrasts with literature precedents where very few nickel(II) complexes exhibit comparable activity to convert ketones. Furthermore, this catalyst is to our knowledge the only one able to selectively target ketones in a mixed olefin-ketone substrate. Some experiments suggest the involvement of a nickel-hydride as active catalyst. DFT calculations (done by Prof. V. Gandon) were very helpful in understanding the possible intermediates of this reaction, in particular by suggesting a distortion of the ligand into a butterfly shape, which allows the insertion of the substrate.The synthesis of tridentate ligands with a central phosphorus unit was also explored. A neutral NPN ligand with a central phosphine moiety and two lateral iminophosphoranes was built-up and coordinated to cobalt(II). This cobalt complex was shown to be catalytically active in the hydrosilylation of internal olefins with low catalytic loadings (1.5 mol%), at 60 °C within 6 hours, which is amongst the best performances reported until now.This PhD project is an illustrative specimen of the potential of using earth-abundant iminophosphorane complexes for catalytic applications.

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The Mediterranean corn borer (MCB) is a major corn pest causing significant yield losses, which leads to the use of insecticides in France. In the native range, its caterpillars are attacked by the insect parasitoid, Cotesia typhae, a potential biological control agent against MCB. In the CoteBio project, we tested the parasitism efficiency of C. typhae in greenhouses and estimated the environmental risk of introducing this non-native species in France. In greenhouses, a single release of C. typhae resulted in a 98% reduction in the MCB population. The risk to non-target species was tested on 8 lepidoptera. On average, only 4.4% of caterpillars died following parasitism, and only 0.4 to 2% of caterpillars of 4 species allowed parasitoid development. The likelihood of C. typhae establishing in the French environment is further compromised by its sensitivity to winter temperatures (10-15°C). A new Ecophyto project, BIOCOSMA, aims to develop a biological control solution against the MCB through annual releases of C. typhae in the field.

La colonisation bronchique par Aspergillus fumigatus (Af) constitue une source majeure de complications infectieuses chez les patients atteints de maladies pulmonaires chroniques. L'efficacité limitée des antifongiques disponibles, associée à l'émergence croissante de souches résistantes aux azolés, rend nécessaire l'exploration de nouvelles stratégies thérapeutiques. Dans ce contexte, les peptides antimicrobiens (PAM) constituent une alternative prometteuse. Le peptide modifié ETD151, dérivé d'un PAM de lépidoptère, a notamment démontré une activité antifongique contre Botrytis cinerea, un champignon phytopathogène. L'objectif de cette thèse était d'évaluer l'effet anti-Aspergillus d'ETD151 ainsi que son éventuel rôle sur la réponse inflammatoire des cellules épithéliales bronchiques primaires humaines (CEBPH). Le peptide a été testé sur des souches sensibles et résistantes aux azolés, avec des résultats probants. ETD151 induit un raccourcissement et une hyper-ramification des filaments fongiques. Un test cinétique à la résazurine a révélé une inhibition significative de l'activité métabolique, atteignant un maximum avec 1,25 µM d'ETD151. L'activité lytique du peptide a été confirmée par des colorations au calcofluor et au Sytox Green. Des essais de compétition, ainsi que l'utilisation d'une souche de Af délétée pour un gène codant les glucosylcéramides, ont permis de confirmer que ces lipides membranaires sont la cible de ETD151. Par ailleurs, des repiquages successifs sur 16 génération du champignon en présence de ETD151 n'ont pas permis de mettre en évidence le développement de résistance du champignon vis avis du peptide. Enfin, le peptide ne provoque ni libération d'IL-8 par les CEBPH, ni cytotoxicité. Enfin, son effet antifongique sur les CEBPH infectées par Af a été confirmé par dénombrement des CFU et observation en microscopie confocale. Ces résultats soulignent le potentiel des PAM comme agents antifongiques innovants, notamment face aux souches résistantes aux traitements conventionnels.

Pour de nombreux endoparasitoïdes ichneumonides, le succès parasitaire dépend de leur association avec un polydnavirus symbiote. Les particules virales, produites exclusivement dans les ovaires, sont injectées dans la chenille du lépidoptère au moment de l’oviposition. L’expression des gènes viraux dans les tissus infectés induit des altérations importantes dans la croissance, le développement et la réponse immunitaire de l’hôte, ce qui permet le développement de la progéniture du parasitoïde. Les gènes vankyrines constituent une famille multigénique que l’on retrouve dans tous les génomes de polydnavirus séquençés jusqu’à présent. Ils codent pour des protéines homologues aux facteurs IkappaBs, inhibiteurs des facteurs de transcription Rel/NF-kB, dont le représentant le plus étudié chez les insectes est la protéine Cactus de Drosophila melanogaster. Les vankyrines possèdent un domaine ARD constitué de quatre répétitions de type ankyrines qui, chez les IkBs sont essentielles pour leur interaction avec les facteurs NF-kB. Mais contrairement aux IkB cellulaires, les vankyrines n'ont pas les domaines de régulation nécessaires à la dissociation du complexe NF-kB/IkB : elles formeraient donc un complexe irréversible avec les NF-kB, ce qui aurait pour conséquence d’empêcher les NF-kB de se fixer sur leurs sites kB et donc empêcherait l’expression de gènes impliqués dans la réponse immunitaire et/ou le développement de l’hôte parasité. Nous avons identifié neuf gènes vankyrines dans le génome du polydnavirus HdIV, présent chez Hyposoter didymator [Hyménoptère : Ichneumonidae], un endoparasitoïde larvaire de certaines noctuelles, appartenant notamment au genre Spodoptera spp. L’analyse spatio-temporelle des vankyrines de HdIV a mis en évidence l’expression largement prédominante de la vankyrine Hd27-vank1 au cours du parasitisme des larves de S. frugiperda par H. didymator. Pour tenter de comprendre le rôle de Hd27-vank1, nous avons produit un baculovirus recombinant exprimant la protéine virale. Nous avons alors mesuré les effets de l’expression de la protéine virale sur la viabilité des larves de S. frugiperda et des cellules Sf9 infectées avec le baculovirus recombinant. Nous présenterons les résultats obtenus au cours de ce congrès.

Stenoma decora Zeller, 1854 (Lepidoptera: Depressariidae), is considered a pest of the cacao tree, Theobroma cacao L. (Malvaceae), causing direct losses by damaging the fruits. In this study, we searched for parasitoids of Stenoma decora. Caterpillars were obtained from fruits and stems in commercial plantations of T. cacao in Mutuípe, Bahia, Brazil, and reared in laboratory. Here we describe the new species Neocardiochiles tropicalis sp. nov. (Hymenoptera: Braconidae) as a parasitoid of S. decora. Parasitised individuals can be readily identified, as the parasitoid kills the prepupa and produces a light-coloured silk cocoon in place of the host’s dark, sclerotised pupal exuviae. This is the first species of the Neocardiochiles recorded in Brazil, and the southernmost record for the genus so far. The presence of this parasitoid in a commercial crop area provides an important context for biological control, representing a new perspective for the management of S. decora.

Cushion plants, which dominate nival ecosystems, are known to host a large diversity of plant, microbe, and animal life. However, a comprehensive assessment of this diversity is still lacking, particularly with regard to invertebrate soil fauna. In this study, we sampled soil beneath cushion plants in various climatic and geological conditions throughout the French Alps. Our results demonstrate that cushion plants host a remarkably high abundance and diversity of invertebrates, with some individual cushions hosting nearly 400 specimens belonging to 15 different families. Across all samples, 8845 specimens were found. The taxonomic diversity is particularly notable, with groups such as Collembola, Acari, and Nematoda, as well as Gastropoda, Diptera, Coleoptera, Hymenoptera, and Hemiptera. In total, 44 different families were identified. In particular, our findings show that cushion plants not only function as habitats for adult invertebrates, but also as site for the egg laying and larval development of several insect groups, including Diptera, Hemiptera, and Lepidoptera. In addition, different species of cushion plant tend to host distinct invertebrate communities, which makes them a key driver spatial variation in invertebrate populations. However, the factors determining the alpha diversity of invertebrates assemblages in nival environments remain unclear. Overall, our results emphasize the key role of cushion plants in maintaining biodiversity in the nival vegetation belt.