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An Integrative Approach With Cytogenetic and Molecular Data of the Leaf‐Cutting Ant Acromyrmex hystrix (Latreille, 1802) Highlights a Notably Derived Karyotype in the Genus
No full textInternational audienceFungus‐growing ants are a peculiar ant group that cultivates fungi for food. Within this group, the so‐called leaf‐cutting ants ( Atta Fabricius, 1804, Acromyrmex Mayr, 1865 and Amoimyrmex Cristiano et al. 2020) hold significant ecological and economic importance. Previous studies have highlighted conserved chromosome numbers with 2 n = 22 in Atta and Amoimyrmex , and 2 n = 38 in Acromyrmex , with the single exception of the social parasite Acromyrmex ameliae De Souza et al. 2007, with 2 n = 36, as a result of Robertsonian fusion. Although Acromyrmex hystrix (Latreille, 1802) is the type species of Acromyrmex , it is one of the least‐known species of this genus. In this study, we described its karyotype and inferred the phylogenetic relationships within Acromyrmex . A distinct chromosome number was detected for the species, with 2 n = 28 chromosomes and a karyotypic formula of 10m + 16sm + 2st. Our phylogenetic reconstruction revealed Ac. hystrix constituted a separate clade within Acromyrmex . This karyotype is derived within Acromyrmex , with a chromosome number reduction from 2 n = 38 to 28. Cytogenetic and molecular data revealed the evolutionary divergence of Ac. hystrix within Acromyrmex . Although leaf‐cutting ants are among the most studied ants, many gaps remain in our understanding of these insects. The inclusion of additional species in the molecular phylogeny, coupled with chromosomal information, could provide insights into the evolution of Acromyrmex
The social sustainability of food systems: addressing the inequality-unsustainability nexus: Introduction to the Special Issue
No full textInternational audienceThis is the introduction paper of a Special Issue devoted to the Social Sustainability of Food systems. We draw the theoretical framework and present how the different articles contribute to the Issue
Mechanosensing and Sphingolipid-Docking Mediate Lipopeptide-Induced Immunity in <i>Arabidopsis</i>
No full textBacteria-derived lipopeptides are immunogenic triggers of host defenses in metazoans and plants. Root-associated rhizobacteria produce cyclic lipopeptides that activate systemically induced resistance (IR) against microbial infection in various plants. How these molecules are perceived by plant cells remains elusive. Here, we reveal that immunity activation in Arabidopsis thaliana by the lipopeptide elicitor surfactin is mediated by docking into specific sphingolipid-enriched domains and relies on host membrane deformation and subsequent activation of mechanosensitive ion channels. This mechanism leads to host defense potentiation and resistance to the necrotroph B. cinerea but is distinct from host pattern recognition receptor-mediated immune activation and reminiscent of damage-induced plant immunity. Main TextLipopeptides (LPs) represent a prominent and structurally heterogeneous class of molecules among the broad spectrum of small specialized metabolites synthesized by bacteria. Besides serving key functions for the ecological fitness of the producer (motility, biofilm formation, colonization, nutrient acquisition, or antagonism towards competing neighbors), some LPs also act as triggers of immune responses that restrict pathogen infection of metazoans and plants 1,2 . The vast majority of LPs formed by plant-associated bacteria are comprised of a partly or fully cyclized oligopeptide linked to a single fatty acid chain. Some of these cyclic lipopeptides (CLP) formed by beneficial species belonging to the Pseudomonas and Bacillus genera are potent elicitors of immune responses in the host plant leading to a systemically induced resistance (IR) against infection by microbial pathogens 2,3 .</div
Intervention introductive du Séminaire Politique des sciences: L’INRAE emmuré ; les relations entre le monde agricole et le monde scientifique
No full textInternational audienceLe 27 novembre 2024, à l’appel de la FNSEA de Seine et Marne, une centaine d’agriculteurs érigeaient un mur autour des locaux de l’INRAE. Cette action militante, condamnée immédiatement par la direction de l’Institut, n’a pas entraîné de condamnations de la part du monde politique ni de communiqués du gouvernement défendant les chercheurs ainsi montrés du doigt. Dans quelle mesure, cet épisode marque-t-il une évolution plus large des rapports entre science agronomique et monde agricole ? Cette quatrième séance du séminaire Politique des sciences sera l’occasion de revenir sur l’histoire longue des savoirs agricoles et environnementaux dans leur rapport à l’agriculture.Intervenants :•Joël Lallier, sociologue (CMH, Université d’Orléans)•Tamara Ben Ari (CR INRAE, Montpellier)•François Dedieu, sociologue (INRAE)•Christian Huyghes, ancien directeur scientifique agriculture à l’INRAE•Ivan Bruneau, sociologue (Université Lyon 2
Faith-Based Platforms
No full textWe develop a new model of faith-based organizations (FBOs) as multi-sided platforms. Faithbased platforms (FBPs) offer two types of services. The first is a religious service that includes providing a moral narrative, giving guidance and counselling, and proposing access to the divine through prayer, meditation or rituals. The second is a networking service that allows members to connect with members who come for the religious service. By offeringboth types of service, FBPs benefit from the spill-over effect of the religious service, whichhelps to screen for trustworthy network members. FBPs are more profitable than organizations that only offer areligious service, often even per capita, and are generally larger in size. The optimal community size depends on the type of interactions the FBP fosters and how much it invests in the quality of the religious service. This can explain the diversity of FBOs that continue to thrive despite secular competition and some recent phenomena that cannot be fully explained by existing models of FBOs, such as the growth of religion in some urban settings and the emergence of religious communities that have grown very large without sacrificing high profits per member
Larval survival in European seabass (Dicentrarchus labrax) is shaped by the natural thermal regime of their population of origin and the level of introgression of Atlantic and Mediterranean genomes
No full textInternational audienceBetter characterizing fish survival at the most vulnerable larval stage, represents a challenge in a context of global warming and for effective resource management. The European seabass provides a good model to study the interactive effects of temperature and genetics on survival. The species is structured into three genetically distinguishable populations along a geographic gradient from Atlantic (AT) to Western Mediterranean (WM) and then Eastern Mediterranean (EM), with populations a priori adapted to different natural environments. Larval survival was studied in four thermal regimes reflecting natural temperatures of the three populations, and a typical temperature regime used in hatcheries. The AT population showed higher survival in colder regimes compared to the Mediterranean populations. Conversely, larval survival in warmer regimes was higher for the EM population. The WM population had the lowest survival in all thermal regimes. A quadratic relationship was revealed between larval survival and temperature with an estimated maximum around 13.6 degrees C for AT survival, compared to above 17 degrees C for the Mediterranean populations. The level of reciprocal introgression of Atlantic and Mediterranean genomes strongly affected larval survival. The greater the degree of introgression the lower the survival, which partly explained the poor performance of the central WM population. These results demonstrate local adaptation of AT and EM populations to their natural regimes. For the introgression effect, we found a strong purging effect acting on the introgressed ancestry or reproductive isolation barriers. In this species, therefore, population introgression should be carefully considered in strategies for establishing domesticated and/or selected lineages
A semi-automated sensitivity-based approach for simplifying marine biogeochemical models for targeted applications: A case study with the Eco3M-MED model
No full textInternational audienceMarine biogeochemical models are being increasingly used to support scenario-based analyses of climate change and ecosystem dynamics. However, their high structural complexity and large parameter space often limit computational efficiency, interpretability, and adaptability in applications requiring the exploration of many scenarios. To address these issues, we propose a Semi-Automated Iterative Simplification (SAIS) approach that integrates local sensitivity analysis with model mechanistic guidance and Kling-Gupta Efficiency (KGE) metrics to evaluate each simplification step. Using the marine biogeochemical model Eco3M-MED as an example, we specified three objectives for model simplification: (1) fidelity of state variables, (2) fidelity of marine ecosystem indicators, and (3) applicability for coupling with higher trophic level models. For each objective, we assessed model sensitivity to parameters and applied the SAIS approach to simplify the model, and obtained three simplified models. KGE-based fidelity evaluations are used to validate each final simplified model against the reference model. The results show that computational time can be reduced by up to approximately 30% without compromising the model's mechanistic foundation. Overall, this method offers a flexible and scalable approach for generating simplified versions of complex biogeochemical models, suitable for applications in regional marine ecosystem assessments, climate scenario explorations, and model coupling frameworks
Connecting mitochondrial metabolism and mitotic fidelity to control vulnerability of high grade serous ovarian cancer patients to taxane-based chemotherapy
No full textHigh-grade serous ovarian carcinoma (HGSOC), which accounts for approximately 75% of ovarian cancer cases, is associated with poor clinical outcome. Although most patients initially achieve a complete response to conventional chemotherapy, HGSOC almost invariably develops chemoresistance. There is therefore an urgent need to identify predictive biomarkers of treatment response. Here, through integrative analyses of molecular and clinical data from HGSOC patient cohorts, we identify syntabulin (SYBU), a microtubule-associated protein originally described as a regulator of mitochondrial transport along neuronal microtubules, as a critical determinant of chemosensitivity in HGSOC. Low SYBU expression in tumors correlates with higher tumor grade and increased aggressiveness, yet paradoxically with enhanced sensitivity to chemotherapy. SYBU-deficient cancer cells display impaired oxidative phosphorylation and a metabolic shift toward glycolysis characteristic of the Warburg effect, together with mitotic defects such as chromosome lagging that promote aneuploidy. Mechanistically, syntabulin forms a complex with the mitochondrial outer membrane porin VDAC1 and the inner membrane protein MIC60, a major regulator of mitochondrial cristae organization. Functionally, the syntabulin-MIC60 axis controls cristae architecture and mitotic fidelity, thereby connecting mitochondrial metabolism to cell division. These findings highlight new therapeutic vulnerabilities to overcome chemoresistance in ovarian cancer. SIGNIFICANT STATEMENT Ovarian cancer remains the deadliest gynecologic malignancy, largely due to the systematic emergence of resistance to chemotherapy. Identifying molecular mechanisms involved in response to treatment is therefore a major clinical challenge. Here, we uncover an unexpected role for the mitochondrial protein syntabulin in regulating chemotherapy sensitivity in high-grade serous ovarian cancer. We demonstrate that syntabulin coordinates cancer cell mitotic progression with mitochondrial structure and metabolism through interactions with cristae-shaping proteins. These findings reveal a previously unrecognized link between mitotic regulation and mitochondrial architecture, and identify syntabulin as a potential therapeutic target in ovarian cancer to induce vulnerability to taxane-based chemotherapy
L’avenir de la ressource en eau face aux changements climatiques dans les Pays de la Loire: Rapport spécial Eau
No full textEn Pays de la Loire, les évolutions climatiques transforment profondément le cycle de l’eau. La hausse des températures, l’augmentation de l’évapotranspiration et la modification du régime des précipitations accentuent les déficits estivaux, fragilisent la recharge des nappes et renforcent les tensions sur les cours d’eau. Dans le même temps, les risques d’inondation et de submersion demeurent, tandis que la qualité de l’eau reste un défi majeur pour les milieux et l’alimentation en eau potable.Ces effets ne s’expriment pas de manière homogène sur le territoire régional. Selon les bassins versants, les caractéristiques géologiques, l’occupation des sols et l’intensité des usages, la disponibilité de la ressource et les marges d’adaptation varient fortement. Derrière une apparente abondance, des déséquilibres structurels s’installent, rendant certains territoires plus exposés aux pénuries, aux conflits d’usages et aux dégradations écologiques. Une question centrale s’impose alors : comment adapter la gestion de l’eau sans aggraver les vulnérabilités existantes ?Ce rapport du GIEC des Pays de la Loire propose une analyse scientifique de l’avenir de la ressource en eau dans la région. Il éclaire les mécanismes à l’oeuvre, documente les vulnérabilités territoriales et identifie les leviers d’action mobilisables. Il rappelle que l’adaptation ne peut se limiter à des réponses ponctuelles, mais qu’elle suppose une transformation durable des pratiques, fondée sur la sobriété, la protection des milieux et une gouvernance capable d’anticiper les évolutions à venir
From Teacher Quality to Teaching Quality: Instructional Productivity and Teaching Practices
No full textInternational audienceThis paper estimates the causal effects of math instructional time on student achievement using within-student variation across math topics in the TIMSS 2011 data. Based on the assessment's detailed measurement of math skills, it shows that each weekly hour of math instruction in a given topic increases student test scores in that topic by 4.3% of a SD. However, the productivity of instructional time varies significantly based on the implementation of teaching practices that prioritize student active participation: teachers emphasizing these practices are more than twice as productive as other teachers. This result holds true regardless of student gender, social origin, and is observed internationally in 42 countries