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Pseudogenes Document Protracted Parallel Regression of Oral Anatomy in Myrmecophagous Mammals
No full textInternational audienceAdaptation to ant and/or termite consumption (myrmecophagy) in mammals constitutes a textbook example of convergent evolution, being independently derived in several mammalian lineages. Myrmecophagous species are characterized by striking convergent morphological adaptations such as skull elongation, enlargement of salivary glands, and long claws to dig into ant and termite nests. These evolutionary modifications also include anatomical regression, such as dental simplification or loss, reduction of masticatory muscles, and possessing a reduced set of taste buds. To gain insights into the molecular changes underlying the regression of these morpho-anatomical traits, we investigated the functionality of candidate genes related to dentition, gustation, and mastication in nine convergent myrmecophagous mammalian lineages. We examined these genes in a comparative phylogenetic context, paired with molecular evolutionary analyses, to estimate the relative timing of loss of gene function over the evolutionary history of each convergent lineage. We found that gustatory reduction and pseudogenization of masticatory myosin often were associated with the regression of dental genes. Evidence of pseudogenization events linked to oral anatomy dates to as early as the Cretaceous/Paleogene boundary, and is an ongoing process including examples of incipient gene inactivations. Whereas we found evidence for gene inactivations across all three functional categories occurring during distinct temporal intervals, there was variation in the sets of genes lost and the relative timing of inactivation events. The combined evidence suggests that the convergent evolution of myrmecophagy has occurred as a protracted process with distinct phases of anatomical evolution, over timescales as long as 60 Myr
Tarsal lipids regulate xenobiotic penetration in Drosophila melanogaster
No full textInternational audienceInsects touch their proximal environment with their tarsi. The immediate contact with xenobiotics occurs with the tarsal cuticle surface that is covered with cuticular hydrocarbons (CHCs). In this work, we tested the hypothesis that xenobiotics entry through the tarsi depended on CHC amounts and composition. Applying RNA interference, we suppressed the expression of genes coding for the key enzymes of CHC production Cyp4G1 (total CHC), desat1 (unsaturated CHCs) and FASN2 (branched CHCs) in lipid producing oenocytes and analyzed the penetration efficiency of the insecticides DDT and chlorantraniliprole and of the inert dye Eosin Y in the respective flies. As expected, in walking experiments, reduction of CHC amounts (cyp4G1RNAi) enhanced insecticide and dye penetration into the tarsi. In the same assay, we identified unsaturated CHCs as the main CHC component attenuating DDT and chlorantraniliprole at low concentrations. Likewise, tarsal adhesion and uptake of Eosin Y depended rather on unsaturated than on branched CHCs. Extrapolating from our data, we propose a two‐step model of xenobiotics penetration through the tarsal cuticle: first, modulated by unsaturated CHCs, the molecule is repelled or adheres to the cuticle surface; upon adhesion, the molecule penetrates the cuticle and accumulates in the tarsal lumen in a second step. Whether these mechanisms apply to molecules other than Eosin Y remains to be investigated. Taken together, the tarsal cuticle constitutes a selective bipartite barrier against uncontrolled uptake of contact xenobiotics
One-Sided Enforcement in a Model with Persistent Adverse Selection
No full textNational audienceWe study a repeated buyer-seller relationship with persistent adverse selection and one-sided enforcement, where a prepaid seller can breach by taking the money and running. The optimal stationary contract depends on enforcement strength and the discount factor. Three regimes arise. With a strong legal system, penalties deter breach and the optimal static contract can be repeated. With a weak system, the penalty caps transfers, forcing bunching among efficient (low-cost) types. With a very weak system, compliance relies on relational rents, causing large downward distortions. Strengthening public enforcement relaxes both incentive and enforcement constraints, reducing allocative inefficiency
To be or not to be value-free? A tension in the European Code of Conduct for Research Integrity
No full textInternational audienceIn this paper, we document a tension in the European Code of Conduct for Research Integrity: the Code seeks to limit the influence of non-epistemic values, and yet, it recognizes that such values play a legitimate role in research. By comparing various versions of the Code, we argue that, over time, there has been less explicit recognition of the complexity of the relation between research and societal values. Currently, the Code does not give guidance on what value influence count as undesirable or as "undue pressure", and conflates the issues of value-freedom and scientific freedom. As the impact of non-epistemic values is becoming increasingly evident, we recommend that future codes start by explicitly acknowledging the challenges inherent in the relation between science and societal values, and we offer an example of how the ECoC could be revised to meet this recommendation
From forest decline to salvage logging: cascading impacts on saproxylic beetle diversity
No full textInternational audienceUnderstanding the cascading effects of forest decline on saproxylic communities is fundamental for optimizing the management of disturbed forests toward biodiversity conservation objectives. We postulated that the nature and intensity of cascading pathways would vary along decline gradients, encompassing stages from stand decline to mortality and subsequent salvage logging, as mediated by shifts in habitat conditions and resource availability. This study was conducted across three representative European forest contexts: fir forests in the French Pyrenees, spruce forests in the Bavarian Alps, and oak forests in the lowlands of the Loire Valley. Within these systems, we assessed how the taxonomic and functional α-diversity of saproxylic beetles responded to variations in both the diversity and density of deadwood and tree-related microhabitats (TreMs). Our analyses identified key cascading effects of stand decline and mortality that were shaped by the considered beetle guild and by the forest type, reflecting tree species–specific disturbance legacies. Stand decline and mortality produced distinct responses within saproxylic beetle assemblages, as different successional guilds preferentially utilized either dying or dead trees. The overall influence of decline processes was positive in conifer-dominated forests. TreMs played a central role in mediating cascading processes structuring saproxylic beetle communities throughout the forest decline continuum. The increase in TreM heterogeneity associated with stand decline or mortality enhanced saproxylic diversity, with exposed wood and trunk injuries identified as particularly influential microhabitats. Snags and large deadwood elements, especially in spruce forests, and deadwood diversity further contributed to sustaining high levels of beetle diversity. Conversely, salvage logging exerted detrimental effects on numerous guilds, primarily through reductions in TreM diversity, decreased TreM trait dispersion, and the depletion of saproxylic TreMs. Given the pronounced context dependency of the processes driving these cascading community dynamics, and considering the increasing frequency, severity, and spatial extent of forest disturbances and global forest decline, it is imperative to integrate this complexity into management and conservation frameworks. Addressing these mechanisms with greater precision will be critical for maintaining functional biodiversity within rapidly changing forest ecosystems
Characterization using ultra-deep sequencing of the intra-host distribution of the mutations associated with H. pylori antibiotic resistance
No full textInternational audienceIntroduction: Helicobacter pylori is a slow-growing, gram-negative strictly pathogenic bacterium, which colonizes the stomachs of half the global population and is responsible for gastritis, peptic ulcer and even adenocarcinoma, Treatment of choice for eradication is a combination of PPIs and multiple antibiotic therapy. Recently, therapeutic failures began to be attributable to increased antibiotic resistance due to mutations in identified genes (rpoB , 16S rRNA coding gene, gyrA , 23S rRNA coding gene, pbp1A , frxA , rdxA) . Objectives: This study aimed to determine, using ultra-deep sequencing, the distribution of mutations in patient s hospitalized or undergoing screening for H. pylori . Methods: Gastric biopsies were obtained from two different anatomical regions (antrum/fundus) in 18 patients’ samples from 1998 to 2021, in four French hospitals. Following automated extraction, DNA of H. pylori was amplified using multiplexed PCR, before sequencing on the Illumina iSeq100 platform. Results: Antral diversification of H. pylori populations is significantly greater than that at the fundic level for rpoB and rdxA . Fundic diversification of H. pylori populations is significantly greater than that at the antral level for the 23S rRNA coding, rdxA and rpoB genes ( p < 0.05), with inter-individual variation.Conversely, the 16S rRNA, frxA, gyrA and pbp1A genes exhibited no significant variation ( p > 0.05). Discussion: This first study using in-house high-throughput sequencing of H. pylori on clinical biopsies from the same patients reinforces the hypothesis that the bacterial population within the same host is heterogeneous. The presence of minority variants justifies the need for at least two biopsies to ensure robust testing of the H. pylori antibiotic susceptibility profile
Mapping heartwater risk in Guadeloupe using a combination of spatial modelling approaches
No full textSource Agritrop Cirad (https://agritrop.cirad.fr/616397/) * Autres projets (id;sigle;titre): 58–3022–1–018-F;RACE;(USA) Risk of Arthropod-borne diseases in the Caribbean// FEADER_M16_2021_01;TISARU;(EU) Tiques et risques sanitaires en élevage de ruminants//International audienceHeartwater is a tick-borne disease affecting livestock in Africa and the Caribbean, including Guadeloupe, where it threatens animal health and productivity. While Amblyomma variegatum has long been recognized as the primary vector, recent studies suggest Rhipicephalus microplus may also transmit Ehrlichia ruminantium, the causative agent. This study presents a spatial modelling framework to assess heartwater risk across Guadeloupe. Tick presence data collected during livestock inspections were combined with environmental variables derived from satellite imagery and other geospatial sources. Ecological Niche Factor Analysis identified key environmental predictors, which were then used to build MaxEnt models and generate suitability maps for both tick species. These maps revealed distinct ecological preferences and were integrated with cattle density data using a Multi-Criteria Decision Analysis approach, with expert-derived weighting, to produce a composite risk index. The resulting maps provide the first spatially explicit assessment of heartwater risk in Guadeloupe. This approach offers a reproducible method for mapping tick-borne disease risk in data-limited tropical regions and can guide targeted surveillance and control strategies
La mondialisation face à l'urgence écologique
No full textNational audienceLa mondialisation face à l'urgence écologique
Stress-induced amorphization as a transformation plasticity mechanism demonstrated in forsterite
No full textInternational audienceAlthough stress-induced amorphization has recently been identified as a new and distinctive plasticity mechanism, a formal framework for its systematic application in materials engineering is still lacking. In this study, we establish that stress-induced amorphization in Mg2SiO4 forsterite exhibits all the key features of phase transformation plasticity, a well-known phenomenon that has enabled the development of high-performance materials. By analogy with the Transformation-Induced Plasticity (TRIP) effect, we introduce the concept of amorphous-TRIP (a-TRIP). We demonstrate that the a-TRIP features, in particular the orientation effect of stress-induced amorphization (particularly strong in forsterite), can be exploited to design materials with enhanced toughness, a notable advance for a class of materials traditionally limited by brittle behavior
Impacts de systèmes sobres en produits phytosanitaires sur la biologie du sol
No full textCe numéro fait suite au carrefour de l'innovation agronomique dédié au résultats des projets DEPHY EXPE 2 - Des systèmes utilisant les pesticides en ultime recours : résultats et enseignements de 6 ans d’expérimentations le 13 mars 2025 co-organisé par Inrae, Agreenium, la cellule d'Animation Nationale du réseau DEPHY Ecophyto et le lycée agricole du Valentin. Sont présenté les résultats des projets DEPHY EXPE 2 arrivant à leur terme en décembre 2024 pour diffuser les connaissances des principaux enseignements de ces essais « systèmes » qui ont éprouvé pendant 6 ans des combinaisons de leviers alternatifs à la lutte chimique pour maîtriser les bioagresseurs des cultures : diversification de l’agroécosystème, méthodes de contrôle biologique, choix de matériel végétal, stratégie d’évitement, prophylaxie… Les modalités de mises en œuvre des alternatives testées, leurs conditions de réussite et de diffusion et leurs impacts sur les performances techniques, économiques et environnementales de systèmes ont été discutées.National audienceIn the Grand Est French region, agricultural stakeholders conducted experiments between 2018 and 2024 on farming systems with limited use of plant protection products. The systems tested included: - a system with no plant protection products (0 PP), - an integrated protection system with 50% fewer plant protection products (PIC), - and a reduced tillage system without glyphosate (AC). In all three systems, indicators of biological soil fertility were measured to determine the impact of these practices on soil biology. Some biological indicators showed that the three systems are equivalent, while others highlight differences: in particular, the 0 PP system favored nematodes and the decomposition of teabag. The abundance of microorganisms, on the other hand, gave contrasting results depending on the analysis methods usedEn Grand Est, les acteurs agricoles ont conduit, de 2018 à 2024, des expérimentations de systèmes de culture limitant l'usage des produits phytosanitaires. Parmi les systèmes testés figuraient : un système sans produits phytosanitaires (0 PP), un système en protection intégrée avec -50 % de produits phytosanitaires (PIC), et un système en réduction du travail du sol sans glyphosate (AC). Dans les trois systèmes, des indicateurs de fertilité biologique des sols ont été mesurés afin de déterminer l'impact de ces systèmes sur la biologie du sol. Certains indicateurs biologiques montrent que les trois systèmes sont équivalents, tandis que d'autres mettent en évidence des différences : en particulier, le système 0 PP a favorisé les nématodes et la décomposition du thé rouge. L'abondance des microorganismes, quant à elle, donne des résultats contrastés selon les méthodes d'analyse utilisées