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Inverting the lady’s slipper orchid: development and active–passive mechanisms in a ‘living machine’
No full textInternational audienceCardoso JCF, Johnson SD, Oliveira PE. 2025. Flowers meet Newton: testing the role of gravitational pull in resupination of orchid flowers. Journal of Experimental Botany 76, 433–444. https://doi.org/10.1093/jxb/erae413Resupination, the downwards re-orientation of flowers, is a key trait for angiosperms, especially orchids. The study of a lady’s slipper orchid from Brazil by Cardoso et al. (2025) shows that the seemingly basic mechanism is far from simple and that both passive and active mechanisms are at play. Turning upside down is not only a process of gravitropism; it also requires deft positioning of the flower mass to act as a counterweight, and compliance of the flower stalk to act as a hinge. Developmental timing, functional traits, and viewing functional ensembles as living machines broaden our understanding of evolutionary process and drive novel bio-inspired technologies
DNA methylation landscapes before and after Pacific Oyster Mortality Syndrome are different within and between resistant and susceptible Magallana gigas
No full textInternational audiencePacific oysters face recurring outbreaks of Pacific Oyster Mortality Syndrome (POMS), a polymicrobial multifactorial disease. Although this interaction is increasingly understood, the role of epigenetics (e.g., DNA methylation) appears to be of fundamental importance because of its ability to shape oyster resistance/susceptibility and respond to environmental triggers, including infections. In this context, we comprehensively characterized basal (no infection) and POMS-induced changes in the methylome of resistant and susceptible oysters, focusing on the gills and mantle. Our analysis identified differentially methylated regions (DMRs) that revealed distinct methylation patterns uniquely associated with the susceptible or resistant phenotypes in each tissue. Enrichment analysis of genes bearing DMRs highlighted that these epigenetic changes were specifically linked to immunity, signaling, metabolism, and transport. Notably, 31 genes with well-known immune functions were differentially methylated after POMS, with contrasting methylation patterns between the phenotypes. Based on the methylome differences between phenotypes, we identified a set of candidate epibiomarkers that could characterize whether an oyster is resistant or susceptible (1998 candidates) and whether a site has been exposed to POMS (164 candidates). Overall, the findings provide a deeper understanding of the molecular in teractions between oysters and POMS infection, opening new questions about the broader implications of epigenetic mechanisms in host-pathogen dynamics and offering promising strategies for mitigating the impacts of this devastating disease. Beyond its biological aspects, this study provides insights into potential epigenetic biomarkers for POMS disease management and targets for enhancing oyster health and productivity
A scoping review of the impacts of forest dynamics on acari-borne diseases: beyond forest fragmentation
No full textInternational audienceAbstract Background: Forest cover has undergone significant changes, which have accelerated over recent decades. Acari vectors such as ticks and chigger mites are intricately linked to forest ecosystems because of the suitable hosts and microclimates they provide. However, the implications of forest cover change and dynamics on acari vectors and their pathogens remain poorly understood. This study aims to investigate the impacts of forest dynamics on the risk of acari-borne diseases worldwide through a comprehensive review of the literature. Methods: We conducted a scoping review following the PRISMA Method to retrieve citations related to forest dynamics and acari-borne diseases. Eligibility criteria were predefined and relevant data were extracted from selected articles. The analysis employed a descriptive approach and thematic narrative synthesis. Results: Our review reveals that the influence of forest dynamics on acari-borne diseases and related vectors was predominantly discussed within a Western context, particularly with regard to Ixodes ticks and Lyme disease. Four types of forest dynamics have been identified in the literature: deforestation, fragmentation, conversion and reforestation. However, there was no consensus on the impacts of those dynamics on the vectors and their associated pathogens. Studies have reported conflicting findings including: protective or risk effects, nonlinear relationships, dependent effects influenced by additional factors altering relationships or nonsignificant effects. Those outcomes had been reported across different forest dynamics and various locations. Although, there is limited empirical evidence on tropical contexts as well as for reforestation and conversion dynamics, making it difficult to draw conclusions regarding pathogen and vector trends. Differences in results trends emerge when comparing the entire article sample (n = 111) to empirical studies (n = 73), with literature reviews often overestimating the dilution effect observed in empirical research. Finally, our review identifies a notable absence of studies on scrub typhus disease in the context of forest dynamics. Conclusions: This scoping review offers a novel and comprehensive overview of global literature on the impacts of forest dynamics on acari vectors and the infectious agents they transmit. It highlights research gaps and the need for future research targeting specific forest dynamics, particularly chigger mite vectors in a tropical context
Analysis of the impact of vertical variation and temporal frequency of the chlorophyll forcing field on modelled temperature in the Mediterranean Sea and potential implications for regional climate projections
No full textInternational audienceThe urgency of climate change calls for the exploration of a variety of multi-forcing scenarios based on Shared Socio-economic Pathways. Ensuring the reliability of the climate projections is therefore an imperative prerequisite. In this paper, we examined the impact of the vertical variability and temporal frequency of the chlorophyll field used to force the NEMOMED12 ocean circulation model in the absence of a biogeochemical model on some key physical characteristics, mainly seawater temperature. Our analysis reveals that forcing by a chlorophyll field that is homogeneous in the vertical direction favours heat accumulation below the Deep Chlorophyll Maximum, leading to a positive temperature bias increasing with time. The extrapolation of the trend determined over the 11-year simulations leads to a bias in temperature as high as +1 • C after 100 years in the intermediate layer. Comparison with in situ data clearly shows that forcing the model with a realistically varying Chl field over the vertical allows the model to better represent temperature and avoid the presence of this bias. Additionally, we find that using the same chlorophyll field saved at different time frequencies, namely daily, monthly and monthly climatology, to force the NEMOMED12 model also creates temperature differences between simulations that increase with time, especially in the intermediate layer. The simulation forced by the daily chlorophyll is warmer in the surface layers than the two others, and we suggest that this is due to the asymmetric role of chlorophyll extremes on heat distribution. Finally, using a monthly chlorophyll climatology to force the NEMOMED12 ocean circulation model seems to be sufficient for physical modelling of the Mediterranean basin if the vertical variability of the Chl field is realistic.</div
Building a reliable 16S mini-barcode library of wild bees from Occitania, south-west of France
No full textInternational audienceDNA barcoding and metabarcoding are now powerful tools for studying biodiversity and especially the accurate identification of large sample collections belonging to diverse taxonomic groups. Their success depends largely on the taxonomic resolution of the DNA sequences used as barcodes and on the reliability of the reference databases. For wild bees, the barcode sequences coverage is consistently growing in volume, but some incorrect species annotations need to be cared for. The COI (Cytochrome Oxydase subunit 1) gene, the most used in barcoding/metabarcoding of arthropods, suffers from primer bias and difficulties for covering all wild bee species using the classical Folmer primers. We present here a curated database for a 250 bp mini-barcode region of the 16S rRNA gene, suitable for low-cost metabarcoding wild bees in applications, such as eDNA analysis or for sequencing ancient or degraded DNA. Sequenced specimens were captured in Occitania (south-west of France) and morphologically identified by entomologists, with a total of 530 individuals belonging to 171 species and 19 genera. A customised workflow including distance-tree inferences and a second round of entomologist observations, when necessary, was used for the validation of 348 mini-barcodes covering 148 species. Amongst them, 93 species did not have any 16S reference barcode available before our contribution. This high-quality reference library data are freely available to the scientific community, with the aim of facilitating future large-scale characterisation of wild bee communities in a context of pollinators' decline
Direct and indirect effects of pesticide exposure on the gut microbiota of a farmland raptor
No full textInternational audienceRecent studies in humans have shown that certain pesticides could affect the composition and functions of thegut microbiota, an essential modulator of vertebrate physiology, leading to potential dysbiosis. However, thisrelationship remains largely unknown in wild birds despite the implications of pesticides in the current decline offarmland species. The present study sought to fill this gap by providing data on the association between pesticideconcentrations in blood and gut microbiota characteristics in relation to individual traits in a farmland raptor,the Montagu’s harrier (Circus pygargus). Results showed that females with higher body condition and higherpesticide load exhibited greater gut bacterial richness and diversity, while the relationship was opposite in maleswith higher body condition. In terms of taxonomic composition, Proteobacteria emerged as the dominant phylumacross all nestlings. Differences in the abundance of specific phyla and genera were observed according to pesticide load, with higher levels of Bacteroidota and Leifsonia, but lower levels of Bulkholderia, in nestlings withhigher pesticide concentrations in their blood. This study highlights differences in microbiota and contaminationby several pesticides according to the phenotypic characteristics of a wild raptor, and shows that farmland birdscan represent relevant biosentinels for assessing the health/proper functioning of ecosystems (One Healthapproach)
An approach for modular environmental life cycle assessment of effluent treatment: Configuration of effluent treatment modules based on decision tree tailored to best available techniques
No full textInternational audienceAn approach was developed to configure treatment scenarios for a given industrial effluent based on pollutant composition, intended end use, available technologies, as well as environmental impact assessments of the scenarios. To overcome the complexity of configuring the industrial effluent treatment chain due to the variety of contaminants and diverse available treatment technologies, a decision tree was developed based on the best available technology tailored to pollutant types. A parametric life cycle inventory was developed for the operation phase of fifteen conventional and advanced treatment technology modules to facilitate a comparative environmental impact assessment, including parametric sensitivity and uncertainty analysis. The comparative modular life cycle assessment revealed the hotspots and contributions of fifteen treatment modules to the environmental impacts of treating of 1m3 effluent, with nanofiltration, reverse osmosis, and ion-exchange having the highest overall impacts, whereas cartilage, sand filtration, and UV have the lowest environmental impacts. Sensitivity analysis unveiled high sensitivity of midpoint and endpoint environmental impacts to energy, resin and chemical consumptions. This approach offers a foundational framework for further decision tree developments as a supporting tool for treatment configuration in the effluent treatment industry, as well as sustainability assessment of treatment scenarios derived from the decision trees. Modular treatment configuration integrated into a decision tree promises more flexibility in setting up fit-for-purpose treatment scenarios and conducting modular life cycle assessments for more sustainable effluent treatment
Complementarities of nanoindentation and atomic force microscopy for exploring micromechanical features of ancient flax fibres
No full textInternational audienceThe use of flax (Linum usitatissimum L.) fibres for textile dates back to several millennia; in Ancient Egypt flax was widely used in many everyday items. While flax fibres continue to diversify today as composite reinforcements, the study of their historical use is highly relevant when it comes to their durability; archaeological samples offer unique lenses for understanding changes in intrinsic fibre properties after long–time periods. Through a comprehensive examination of ancient Egyptian flax fibres from four archaeological artefacts, this study carries out a detailed characterisation of the fibre ultrastructure and micromechanical properties by combining nanoindentation (NI) and atomic force microscopy (AFM). This work highlights the complementary of these techniques for both heritage and materials science; it demonstrates on some samples, the remarkable cell wall stiffness, even after thousands of years, which is a key element for the bio-based composites sector, to better understand the degradation mechanisms of plant fibres
Redox variations in glass manufacturing: effects of oxygen fugacity and temperature on glass and melt properties
No full textInternational audienceAt the time of the energy transition, it is important to modify the manufacturing conditions of glasses, in particular by reducing the CO 2 footprint. How do changes in the oxygen fugacity of a furnace affect the redox and properties of glass and melts? In this short article, we present redox calculations for some glass compositions and property measurements on a simplified low-iron glass composition. The increase in glass transition temperature by 10°C when the redox ratio Fe 3+ /(Fe 2+ +Fe 3+ ) changes from 0.4 to 0.73 highlights the role of iron as a network-former in glass.</div
3D imaging of the Bayeux Tapestry using photogrammetry and integration into virtual reality: Results of a feasibility test
No full textInternational audienceThe Bayeux Tapestry is one of the most famous pieces of medieval art. Our objective is to report on a 3D image processing experiment carried out to test and prepare further dedicated and more systematic observation campaigns. We have tested the capacity of the Structure-from-Motion photogrammetry range imaging technique to compute detailed 3D models of the Tapestry through its protecting window, using a Nikon Z7II full frame mirrorless camera. Tests have been carried out both at the global scale and at the local scale on four scenes, including the Halley comet. We show that 3D details up to the fabric weft level can be obtained locally using this photogrammetry technique, in addition to a global digital model. We have also computed a 3D model of the interior of the nearby Bayeux Cathedral. A Virtual Reality simulation has been created to showcase a subset of the Tapestry inside the Bayeux Cathedral, in order to validate a proof of concept for potential future digital outreach and scientific enhancement projects