Oskar Bordeaux
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Final Report of the DIGEMAC Project "Genetic Diversity in the Massif Central". Technical and methodological support mission to study the resilience of forests to climate change in three Regional Nature Parks (PNR). Project funded under the “Biodiversity of the Inter-Parks of the Massif Central” initiative. Operation “Ancient Forests – Phase 4”
No full textFinancement dans le cadre du projet « Biodiversité de l'inter-parcs du Massif central ». Opération « Forêts anciennes volet 4 » Mission d'accompagnement technique et méthodologique pour étudier la résilience des forêts face au changement climatique dans 3 parcs naturels régionaux (PNR) du Massif central</div
Importance of stomatal patchiness in the biological response to water stress
No full textDroughts are increasing in frequency and intensity across all biomes, affecting plant survival and productivity. During drought, the stomatal response, although effective against water loss, is detrimental to CO2 uptake, highlighting the trade-off between transpiration and assimilation. Stomatal patchiness, defined by a non-uniform distribution of stomatal openings across the leaf surface, represents an emerging collective behaviour that optimises gas exchange in response to environmental stimuli. Advanced imaging techniques, such as thermal and chlorophyll fluorescence imaging, have become essential methods to visualise and quantify this phenomenon. This research investigates dynamics of stomatal patchiness along drought, examining both long-term and short-term stomatal responses using dual imaging. Our results show consistent patterns in thermal and quantum efficiency in relation to stomatal conductance, with both measures showing variability at the onset of stress, indicating some plasticity in the face of changes in water potential optimising gas exchange. Stomatal patchiness emerges as a complex, multiscale phenomenon characterised by the fragmentation of macroscale leaf patches into distinct unit patches. This hierarchical organisation is manifested by intra-patch dynamics as a short-term response to environmental conditions, but decreases in the long term as water stress increases. The relationship between patch-level behaviour and overall leaf physiology highlights the biological significance of this spatial heterogeneity in plant water regulation strategies, leading to a better understanding of the mechanisms underlying drought resistance. Understanding stomatal patchiness and its role in drought response is crucial for developing strategies to enhance plant resilience to water stress in the context of climate change
Satellite Magnetic Attitude Control in Sun-Safe Mode Using Control Lyapunov Function
No full textThe sun-safe mode is employed to restore the satellite to normal operating conditions in the event of a serious attitude control malfunction. In this article, a fully magnetic attitude controller based on control Lyapunov function (CLF) is proposed. This approach allows the satellite to maintain sun-pointing on the target axis while slowly rotating around this axis, thereby ensuring the satellite's stability and providing a reliable energy supply. First, an affine nonlinear system is constructed based on sun vector dynamics and attitude dynamics, and an appropriate magnetic control law is developed using a CLF to solve the stability problem of this system. Then, the magnetic control law is proven to achieve asymptotic stability without restrictive assumptions on the satellite inertia matrix. Compared with state-of-the-art magnetic control methods for sun-safe mode, the proposed method has a wider application scope and better control performance, as demonstrated by the simulation results. Finally, hardware-in-the-loop experimental results substantiate that the proposed method is both applicable and effective
Commun Biol
No full textHereditary Hemorrhagic Telangiectasia (HHT) is a rare vascular disease mainly caused by pathogenic mutations in ACVRL1 and ENG genes. Despite advances in HHT diagnosis, the molecular origin of some cases remains unclear. Recently, we observed a high prevalence of HHT-causing 5'UTR variants in ENG. These variants commonly introduce upstream AUG codons (uAUGs) at the origin of upstream open reading frames (upORFs) overlapping the coding sequence, all terminating at the same stop codon located at position c.125 (uAUG-c.125). Here, we analyzed all 5'UTR ENG single nucleotide variants that could alter upORFs in silico. Interestingly, we found that 85% of uAUG-c.125 variants alter the protein levels. Furthermore, we identified 2 variants creating uAUG-c.125 and uCUG-c.125 in HHT patients and experimentally demonstrated their association with reduced endoglin levelsThis study provides new elements for the interpretation of upORF-altering variants in the 5'UTR of ENG with new insights for the molecular diagnosis of HHT
Bordeaux Facility for Tomato Genome Editing (EDITOM)
No full textFor over 20 years, the Flowering, Fruit development and Environemental Constraints Team (FDFE) has been leader in producing transgenic tomato lines including overexpressing lines, miRNA lines, reporter lines for its own research and collaborative projects. The team rapidly adopted genome-editing tools for its research, enabling the production of edited tomato plants. As a result, FDFE team has developed large expertise in every step of the pipeline required for producing edited tomatoes. This includes the design and production of genetic constructs (molecular biology), tomato transformation (in vitro culture), genotyping by sequencing, and ploidy verification (molecular biology and flow cytometry). In addition, the team transfers its expertise via the training of students, PhDs or visiting scientists.Since 2023, we have established a tomato transformation facility (EDITOM), supported by part-time contributions from an engineer and two technicians. This facility provides transgenic tomatoes, including genome-edited plants, to various research teams. So far, we have successfully produced 12 CRISPR knockout lines and 17 overexpressing lines across four different genotypes, serving three INRAE and one international research teams
Virome Survey of Banana Plantations and Surrounding Plants in Malawi
No full textA virome survey of banana plantations and their surrounding plants was carried out at nation-wide level in Malawi using virion associated nucleic acids (VANA) high throughput sequencing (HTS) on pooled samples and appropriate alien controls. In total, 366 plants were sequenced, and 23 plant virus species were detected, three species on banana (275 plants) and 20 species in surrounding plants (91 plants). Two putative novel virus species; ginger tymo-like virus and pepper derived totivirus were detected and confirmed by RT-PCR on ginger and pepper. Nine known virus species and detected a host plant was identified for two of them. No viral exchange between banana and surrounding plants was observed. Results from the VANA protocol, applied to pooled banana samples, were compared with previous targeted PCR results obtained from individual banana samples. HTS test detected better BanMMV than IC-(RT)-PCR on individual samples (better inclusivity) but detected with much lower sensitivity BBTV and BSV species, often with less than 10 reads per sample. Detection of novel and known viruses and new host plants calls for strengthened sanitory and phytosanitory measures within and beyond banana production systems. Our research confirms that HTS sensitivity depends on sampling, pooling protocol and targeted virus species
Culture of tumour-infiltrating T cells after inhibition of epithelial-mensenchymal transition
No full textLe microenvironnement tumoral (MET) est l'écosystème qui entoure une tumeur à l'intérieur du corps. Il comprend, en plus des cellules tumorales, plusieurs types de cellules accessoires qui interagissent constamment et s'influencent mutuellement, de manière positive ou négative. Adaptables et plastiques, les cellules tumorales façonnent ce MET et provoque des mécanismes cellulaires qui favorisent leur progression. L’un de ces mécanismes majeurs est la transition épithélio-mésenchymateuse (TEM). La TEM est un programme cellulaire essentiel au cours du développement embryonnaire, qui permet aux cellules épithéliales polarisées de passer à un phénotype mésenchymateux avec une motilité cellulaire accrue. Les cellules de carcinome exploitent la TEM pour faciliter leur dissociation de la tumeur primaire et leur diffusion dans la circulation sanguine. La TEM confère également aux cellules tumorales un caractère de cellule souche et une résistance accrue à la clairance immunitaire et à diverses agressions thérapeutiques. Alethia Biotherapeutics développe un anticorps AB-16B5 qui inhibe cette TEM en ciblant une protéine centrale dans ce programme cellulaire, la clusterine sécrétée. Cette inhibition permet de resensibiliser la tumeur à la chimiothérapie et d’améliorer l’infiltration immune. Je développe pour le laboratoire une thérapie cellulaire adoptive de lymphocytes infiltrant la tumeur, qui tire profit de l’amélioration de l’infiltration immune apportée par le 16B5 dans le traitement du cancer du poumon. Pour cette thérapie, les propres cellules immunitaires d'un individu sont prélevées, manipulées et readministrées dans le but de fournir une réponse à médiation cellulaire spécifique à la tumeur contre le cancer. Cette thèse définit les notions théoriques nécessaire à la compréhension de ces mécanismes biologiques et présentent les premiers résultats expérimentaux de culture de lymphocytes à partir de morceaux de tumeur dans un modèle de souris.The tumour microenvironment (TME) is the ecosystem that surrounds a tumour inside the body. It includes, in addition to tumour cells, several types of accessory cells that constantly interact and influence each other, positively or negatively. Adaptable and plastic, tumour cells shape this TME and induce cellular mechanisms that promote their progression. One of these major mechanisms is the epithelial-mesenchymal transition (EMT). EMT is an essential cellular programme during embryonic development, which allows polarised epithelial cells to transition to a mesenchymal phenotype with increased cell motility. Carcinoma cells exploit EMT to facilitate their dissociation from the primary tumour and diffusion into the bloodstream. EMT also confers on tumour cells a stem cell character and increased resistance to immune clearance and various therapeutic assaults. Alethia Biotherapeutics is developing an AB-16B5 antibody that inhibits this EMT by targeting a central protein in this cellular programme, the secreted clusterin. This inhibition makes it possible to resensitise the tumour to chemotherapy and improve immune infiltration. I am developing for the laboratory an adoptive cell therapy of tumour-infiltrating lymphocytes, which takes advantage of the improved immune infiltration provided by 16B5 in the treatment of lung cancer. In this therapy, an individual's own immune cells are harvested, manipulated and re-administered to provide a tumour-specific cell-mediated response to cancer. This thesis defines the theoretical concepts necessary to understand these biological mechanisms and presents the first experimental results of lymphocyte culture from tumour pieces in a mouse model
