Publications scientifiques

Quorum Quenching (QQ) is a proven anti-biofouling strategy in Membrane Bioreactors (MBRs). This study presents a novel approach for preparing and characterizing Poly (vinyl alcohol) (PVA) and Alginate (ALG) sheets for biofouling mitigation in MBRs. A significant challenge is posed in achieving QQ sheet preparation without using boric acid (H3BO3), a toxic crosslinker, and in a single-step crosslinking process. In this context, novel PVA-ALG sheets were prepared using sodium nitrate (NaNO3) and calcium chloride (CaCl2) in a single crosslinking step. Another new type of porous sheets was also prepared using a primary crosslinking solution composed of H3BO3, NaNO3, and CaCl2. The structural, mechanical, and textural properties of newly prepared sheets were compared to those of sheets crosslinked using the conventional primary crosslinking solution containing H3BO3 and CaCl2. Additionally, degradation of the QS signal molecule C8-HSL was investigated using all types of sheets entrapped with the QQ bacteria Rhodococcus sp. BH4. Differences in the composition of the crosslinking solutions among the various sheet types led to variations in their structural properties, characterized by increased crosslinking density and macro-void formation. Mesopores dominate in all PVA-ALG sheets, while their specific surface areas range from 45 m2/g to 77 m2/g, and tensile strength between 0.1 MPa and 0.3 MPa. New sheets crosslinked with NaNO3 and CaCl2 display the highest tensile strength and specific surface area. Furthermore, QQ sheets crosslinked with NaNO3 and CaCl2 demonstrated a superior C8-HSL degradation capacity compared to those prepared using the conventional crosslinking method involving boric acid. Graphical Abstract

The Allis shad (Alosa alosa L.) is a diadromous fish distributed along the coastal areas from Germany to Portugal. After approximately five years at sea, adults migrate upstream for hundreds of kilometres to reach spawning grounds in the middle and upper sections of river catchments, where they reproduce. Photoperiod is a key environmental factor, known to influence fish reproduction in temperate regions. This study examines the influence of photoperiod on the nocturnal spawning of Allis shad in the Loire River catchment (France). Results reveal a consistent spawning dynamic across the locations where it occurs in the study area, with activity beginning 1 h and 45 min before the start of dark night, peaking at 2 h after the start of dark night, and ending at 6 h after the start of dark night, with a total activity duration of 7 h and 45 min. However, variations in spawning dynamics were observed throughout the spawning season, with significant differences between long and short nights. Specifically, spawning dynamic was shorter and more intense during short nights, while it was longer and more moderate during long nights. These findings highlight the role of photoperiod in regulating the spawning dynamics of Allis shad.

While the Late Glacial evolution of Pyrenean glaciers is rather well-known, Holocene glacier behavior is much less constrained, except for the Little Ice Age period. In this study, we attempt to bridge this knowledge gap by dating four moraines in the Western-Central Pyrenees using in situ chlorine-36 cosmic-ray exposure dating of moraine boulders. Ages of 11.2 ± 1.5 ka, 7.8 ± 1.1 ka, 3.0 ± 0.6 ka and 972 ± 208 yr were obtained, constituting the most robust directly dated Holocene glacier chronology in the Pyrenees. The moraine age of 7.8 ± 1.1 ka (n = 5) is a novel finding as no evidence for significant contemporary glacial advance exists at any other site in the Pyrenees or in the Alps/elsewhere in Europe. We tentatively link this moraine to the 8.2 ka cold event. We propose a paleoclimatic interpretation of this Holocene glacial evolution, in conjunction with the radiocarbon ages from nearby peat bog cores. Further, we hypothesize on the role of Mid-Holocene warm periods on the melting of permafrost within rock glacier complexes and how they translate into peat bog deposits in the vicinity of the moraines. Finally, based on archeological evidence (construction and ceramic remains) collected in the center of Troumouse Cirque, the possible influence of its glacier variability on first human settlements in the region is discussed.

Cecropia obtusa is a Neotropical myrmecophyte (i.e., plant sheltering ant colonies in hollow structures in exchange for protection against different enemies) that, in French Guiana, is associated with the dolichoderine ants Azteca alfari or A. ovaticeps that nest in this tree’s internodes and are provided food, mostly food bodies called Müllerian bodies. We show that the workers of the ectatommine ant Ectatomma tuberculatum are able to select small C. obtusa individuals (i.e., they were never noted on trees more than 3 m tall) to ambush the Azteca workers exiting the entrance holes to the internodes on these trees. Their presence is more frequent diurnally when the Azteca must leave their nest to harvest Müllerian bodies, whose production requires sunlight, than at night. We witnessed 36 E. tuberculatum foragers ambushing Azteca workers, then seizing and stinging them. Exceptionally, they captured three Azteca workers successively. In all cases, they retrieved them by carrying them between their mandibles. These results confirm that E. tuberculatum foragers, which nest at the base of different tree species, are well adapted to ambushing insect prey, including social insects exiting their nests.

The genus Harttiella, belonging to the armoured catfish family Loricariidae subfamily Loricariinae (Siluriformes), comprises species with narrow geographical ranges, predominantly endemic to river basins in French Guiana and Suriname. Despite recent taxonomic advancements, including the description of new species, Harttiella faces conservation challenges due to its rarity, limited dispersal capacities, and habitat fragmentation. To elucidate the evolutionary history and aid in conservation efforts, we sequenced complete mitochondrial genomes for all known Harttiella species. Our analysis revealed distinctive molecular features, including unique stop codon usage and positioning, potentially serving as molecular synapomorphies for the genus. Phylogenetic reconstructions supported previous findings and highlighted the complex evolutionary relationships within the genus. Furthermore, our study provides foundational genomic resources for developing targeted environmental DNA approaches to monitor and conserve Harttiella populations effectively. These findings contribute to a comprehensive understanding of Harttiella evolution and inform conservation strategies aimed at preserving this unique group of freshwater fish.

The future of the northern peatland carbon (C) sink is uncertain as the effects of warming on microbial metabolisms are unclear. While increased microbial CO2 emissions are expected under warming, the response of microbial photosynthesis remains unknown, complicating predictions of net microbial effects on peatland carbon emissions. Here, using a continental-scale experimental study, we show that warming amplifies microbial photosynthesis by 3.4 mgC m−2 h−1 per 1 °C increase. By 2100, this increase translates to a gain of 51.1 Tg of carbon per year from the northern peatland area under the pessimistic SSP 5-8.5 climatic change scenario, offsetting ~14% of projected heterotrophic CO2 emissions in northern peatlands. By linking field and microcosm experiments, we further show that enhanced microbial photosynthesis accelerates peatland CO2 uptake as photosynthetic microbial-C subsidies stimulate nutrient mineralization. These results underscore the importance of photosynthetic microbes for mitigating carbon emissions and supporting long-term carbon storage in peatlands. The authors use experimental and modelling approaches to understand the response of microbial photosynthesis to peatland warming. They show that warming amplifies microbial photosynthesis, which could offset rising CO2 emissions from northern peatlands by 6.0–13.7% in 2100 (SSP 2-4.5–SSP 5-8.5).

Plant adaptation to terrestrial life started 450 million years ago and has played a major role in the evolution of life on Earth. The genetic mechanisms allowing this adaptation to a diversity of terrestrial constraints have been mostly studied by focusing on flowering plants. Here, we gathered a collection of 133 accessions of the model bryophyte Marchantia polymorpha and studied its intraspecific diversity using selection signature analyses, a genome–environment association study and a pangenome. We identified adaptive features, such as peroxidases or nucleotide-binding and leucine-rich repeats (NLRs), also observed in flowering plants, likely inherited from the first land plants. The M. polymorpha pangenome also harbors lineage-specific accessory genes absent from seed plants. We conclude that different land plant lineages still share many elements from the genetic toolkit evolved by their most recent common ancestor to adapt to the terrestrial habitat, refined by lineage-specific polymorphisms and gene family evolution. Pangenome analyses of 133 wild accessions of the model bryophyte Marchantia polymorpha identify adaptive features and provide insights into the mechanisms of plant adaptation to the terrestrial environment.

Biphasic macroporous Hydroxyapatite/β-Tricalcium Phosphate (HA/β-TCP) scaffolds (BCPs) are widely used for bone repair. However, the high-temperature HA and β-TCP phases exhibit limited bioactivity (low solubility of HA, restricted surface area, low ion release). Strategies were developed to coat such BCPs with biomimetic apatite to enhance bioactivity. However, this can be associated with poor adhesion, and metastable solutions may prove difficult to handle at the industrial scale. Alternative strategies are thus desirable to generate a highly bioactive surface on commercial BCPs. In this work, we developed an innovative “coating from” approach for BCP surface remodeling via hydrothermal treatment under supercritical CO2, used as a reversible pH modifier and with industrial scalability. Based on a set of complementary tools including FEG-SEM, solid state NMR and ion exchange tests, we demonstrate the remodeling of macroporous BCP surface with the occurrence of dissolution–reprecipitation phenomena involving biomimetic CaP phases. The newly precipitated compounds are identified as bone-like nanocrystalline apatite and octacalcium phosphate (OCP), both known for their high bioactivity character, favoring bone healing. We also explored the effects of key process parameters, and showed the possibility to dope the remodeled BCPs with antibacterial Cu2+ ions to convey additional functionality to the scaffolds, which was confirmed by in vitro tests. This new process could enhance the bioactivity of commercial BCP scaffolds via a simple and biocompatible approach.

This paper presents a new implementation method of the Extended-Oxley analytical model, previously proposed by Lalwani in 2009, for orthogonal cutting of metals with a Johnson–Cook thermo-elastoplastic flow law. The present work aims to improve the implementation of this analytical model in order to propose a unified solution that overcomes the main shortcomings of the original model: the non-uniqueness of the solution, the low accuracy of the obtained solution, and the relatively long computational time for a purely analytical approach. In the proposed implementation, the determination of the optimal set of model parameters is based on an optimization method using the Python LMFIT library with which we have developed a dual Levenberg–Marquardt optimization algorithm. In this paper, the performance and efficiency of the developed model are presented by comparing our results for a 1045 steel with the simulation results obtained in the original paper proposed by Lalwani. The comparison shows a considerable gain in terms of computational speed (more than 2000 times faster than the original model), uniqueness of the obtained solution, and accuracy of the obtained numerical solution (almost zero force imbalance).

Ceramic coatings have a long history in the orthopaedic field, with plasma sprayed coatings of hydroxyapatite as leading standard in the manufacturing process; however, these coatings can contain secondary phases resulting from the decomposition of hydroxyapatite at high temperatures, which limit the lifetime of implants and their osseointegration. This work aims to produce coatings that can maximize bone osseointegration of metallic implants. In order to preserve the raw characteristics of hydroxyapatite powders that are thermally unstable, coatings were deposited by cold spray onto Ti6Al4V alloy substrates. In contrast with other thermal spray technologies, this process presents the advantage of spraying particles through a supersonic gas jet at a low temperature. On top of hydroxyapatite, carbonated nanocrystalline apatite was synthesized and sprayed. This biomimetic apatite is similar to bone minerals due to the presence of carbonates and its poor crystallinity. FTIR and XRD analyses proved that the biomimetic characteristics and the non-stoichiometric of the apatite were preserved in the cold spray coatings. The cold spray process did not affect the chemistry of the raw material. The adhesion of the coatings as well as their thicknesses were evaluated, showing values comparable to conventional process. Cold spraying appears as a promising method to preserve the characteristics of calcium phosphate ceramics and to produce coatings that offer potentially improved osseointegration.

Wood (secondary xylem) formation is regulated by auxin, which plays a pivotal role as an integrator of developmental and environmental cues. However, our current knowledge of auxin-signaling during wood formation is incomplete. Our previous genome-wide analysis of Aux/IAAs in Eucalyptus grandis showed the presence of the non-canonical paralog member EgrIAA20 that is preferentially expressed in cambium. We analyzed its cellular localization using a GFP fusion protein and its transcriptional activity using transactivation assays, and demonstrated its nuclear localization and strong auxin response repressor activity. In addition, we functionally tested the role of EgrIAA20 by constitutive overexpression in Arabidopsis to investigate for phenotypic changes in secondary xylem formation. Transgenic Arabidopsis plants overexpressing EgrIAA20 were smaller and displayed impaired development of secondary fibers, but not of other wood cell types. The inhibition in fiber development specifically affected their cell wall lignification. We performed yeast-two-hybrid assays to identify EgrIAA20 protein partners during wood formation in Eucalyptus, and identified EgrIAA9A, whose ortholog PtoIAA9 in poplar is also known to be involved in wood formation. Altogether, we showed that EgrIAA20 is an important auxin signaling component specifically involved in controlling the lignification of wood fibers.

Edible oil extraction is a large and well-developed sector based on solvent assisted extraction using volatile organic compounds such as hexane. The extraction of oil from oilseeds generates large volumes of oilseed by-products rich in proteins, fibres, minerals and secondary metabolites that can be valued. This work reviews the current status and the bio-macro-composition of oilseeds, namely soybean, rapeseed, sunflower and flaxseed, and the refining process, comprising the extraction of oil, the valorisation and separation of valuable secondary metabolites such as phenolic compounds, and the removal of anti-nutritional factors such as glucosinolates, while retaining the protein in the oilseed meal. It also provides an overview of alternative solvents and some of the unconventional processes used as a replacement to the conventional extraction of edible oil, as well as the solvents used for the extraction of secondary metabolites and anti-nutritional factors. These biologically active compounds, including oils, are primordial raw materials for several industries such as food, pharmaceutical or cosmetics.

All-flesh tomato cultivars are devoid of locular gel and exhibit enhanced firmness and improved postharvest storage. Here, we show that SlMBP3 is a master regulator of locular tissue in tomato fruit and that a deletion at the gene locus underpins the All-flesh trait. Intriguingly, All-flesh varieties lack the deleterious phenotypes reported previously for SlMBP3 under-expressing lines and which preclude any potential commercial use. We resolve the causal factor for this phenotypic divergence through the discovery of a natural mutation at the SlAGL11 locus, a close homolog of SlMBP3.

An experimentally validated and self-standing CFD (computational fluid dynamics) model was used to analyze chromia volatilization under high-velocity conditions close to industrial applications range, in wet air and pure O2 environment at 800 and 900 ℃. A rig of complex geometry with several lined-up samples was designed. The simulations revealed the combined and non-trivial influences of gas-phase enrichment from upstream samples, local gas velocity and ratio between sample surface and corresponding free volume for gas flow. The CFD results also validated the often-used analytical approach for single sample planar geometries. For more complex situations, the CFD route is necessary.

Abstract Climate change has an impact on the distribution of numerous species around the world, which for many signifies an increase in the risk of extinction. Human activities, especially the pet trade, often have a negative impact on tarantula spiders. Many species of Mexican tarantulas are considered endangered, such as those that belong to the Tliltocatl complex. Using two datasets containing individuals determined anatomically and/or genetically to be Tliltocatl vagans (Ausserer 1875), we developed distribution models using the MaxEnt algorithm considering past, present, and future climate scenarios. Past scenarios range from the last interglacial period through to the middle Holocene period and future scenarios consider the RCP 4.5 and the RCP 8.5. Our current distribution model of T. vagans covers the known distribution of the genus Tliltocatl. During the last interglaciation (LIG) period, the modelled distribution of this genus was extensive in Central and South America, before being markedly restricted during the last glaciation event. The current distribution is also more concentrated in southern Mexico compared to the initial distribution during the LIG. Future modelled distributions based on the increased temperature scenarios show a drastic decrease in suitable areas, with potential extinction risks in the western part of their current distribution. Given the current context of increasing human activity in the southern regions of Mexico and the future effects of climate change, there is great cause for concern for the conservation of Mexican tarantulas, particularly if no measures are taken to ensure their survival. Implication for insect conservation This work provides important new information showing the high risk of disappearance of Mexican tarantulas’ areas of occupancy in the near future due to climate change. The identification and protection of refuge areas for Mexican tarantulas is essential for their conservation.

Ferritic spheroidal graphite cast irons can be susceptible to intermediate temperature embrittlement between 350 °C and 500 °C. It has been reported that the corresponding loss of ductility increases with the sulfur and magnesium content of the alloy but can be eliminated if the phosphorus content is adapted to ensure a sufficiently low ratio of magnesium to phosphorus contents. Using a low-sulfur, low-phosphorus and high-silicon alloy, previous work clarified the role of magnesium and suggested that small MgO precipitates, developing at grain boundaries due to diffusion of oxygen from the atmosphere during tensile tests, contributed to the generation of brittleness. The present work aimed to clarify how the addition of phosphorus could effect this process and make spheroidal graphite cast irons immune to brittleness at intermediate temperatures. The findings suggest that Mg–P precipitates appeared at high temperature during the cooling process after casting, and that they catch excess magnesium at grain boundaries. During mechanical testing, these Mg–P precipitates tighten the oxygen that penetrates along the grain boundaries to form large Mg–P–O precipitates that are not detrimental to ductility, while preventing the massive formation of small Mg–O precipitates.

Diet plays a pivotal role in the biology of apex predators, shaping their ecological niche, population dynamics, distribution, and adaptability to global changes. The African wolf (Canis lupaster), a large canid endemic to Africa, was recently delineated as a distinct species, taxonomically phagocytizing what was formerly considered the African golden jackal. In this study, we characterised for the first time through DNA metabarcoding the omnivorous diet of the African wolf based on faecal samples collected in northern Algeria. Our results highlighted PCR false negatives in COI (arthropods), while 12S (vertebrates) and trnl (plants) were, respectively, prone to host DNA over-representation and lower taxonomic resolution. Despite these limitations, DNA metabarcoding detected a broader range of consumed items than the morphological analysis applied to the faecal samples, and revealed two vertebrate species, one order of arthropods, and 11 plant families not previously described as part of the African wolf’s diet. The African wolf exhibited an overall reliance on vertebrates and plants with both wild and domestic origins, suggesting yet unobserved cooperative hunting of large prey (wild boar) and regular feeding on livestock carcasses in anthropized areas. Our results indicate that the species employs an opportunistic foraging strategy, with a seasonal shift driven by the abundant consumption of a cultivated fruit (Ficus carica) in summer. Because reliance on farming activities might exacerbate conflicts with humans, there is a need for better knowledge on the foraging strategies of the African wolf, to which further improved, multigene DNA metabarcoding can contribute.

Une étude menée par des chercheurs du CNRS et de l'Université de Toulouse révèle que la majorit

Stomata exert considerable effects on global carbon and water cycles by mediating gas exchange and water vapour1,2. Stomatal closure prevents water loss in response to dehydration and limits pathogen entry3,4. However, prolonged stomatal closure reduces photosynthesis and transpiration and creates aqueous apoplasts that promote colonization by pathogens. How plants dynamically regulate stomatal reopening in a changing climate is unclear. Here we show that the secreted peptides SMALL PHYTOCYTOKINES REGULATING DEFENSE AND WATER LOSS (SCREWs) and the cognate receptor kinase PLANT SCREW UNRESPONSIVE RECEPTOR (NUT) counter-regulate phytohormone abscisic acid (ABA)- and microbe-associated molecular pattern (MAMP)-induced stomatal closure. SCREWs sensed by NUT function as immunomodulatory phytocytokines and recruit SOMATIC EMBRYOGENESIS RECEPTOR-LIKE KINASE (SERK) co-receptors to relay immune signalling. SCREWs trigger the NUT-dependent phosphorylation of ABA INSENSITIVE 1 (ABI1) and ABI2, which leads to an increase in the activity of ABI phosphatases towards OPEN STOMATA 1 (OST1)—a key kinase that mediates ABA- and MAMP-induced stomatal closure5,6—and a reduction in the activity of S-type anion channels. After induction by dehydration and pathogen infection, SCREW–NUT signalling promotes apoplastic water loss and disrupts microorganism-rich aqueous habitats to limit pathogen colonization. The SCREW–NUT system is widely distributed across land plants, which suggests that it has an important role in preventing uncontrolled stomatal closure caused by abiotic and biotic stresses to optimize plant fitness. A plant endogenous peptide-receptor signaling pathway termed SCREW–NUT is described; it counteracts microbe-associated molecular pattern (MAMP)- and abscisic acid-induced stomatal closure to regulate the reopening of stomata after biotic and abiotic stresses.

The operating conditions can have uncontrolled effects on the voltage of a High-Temperature Proton Exchange Membrane Fuel Cell (HT-PEMFC). For instance, the HT-PEMFC can be used at ambient pressure, i.e., without having a back pressure regulator. In this case, the variation in the atmospheric pressure directly affects pressures inside the fuel cell, which induces voltage variation. Moreover, in transient phases, several coupled phenomena can have an uncontrolled effect on the voltage. For example, following a change in the current operating point, thermal conditions in the fuel cell can vary, and the temperature stabilization then leads to a voltage variation. This article introduces a readjustment method for the fuel cell voltage to compensate for the effects of the pressure and temperature variations that are undergone and to decouple their effects. This methodology is based on the realization of a design of experiments to characterize the voltage sensitivity to pressure ([1; 1.5 bar]) and temperature ([120; 180 °C]) between 0.2 and 1 A/cm2 of an Advent PBI MEA (formerly BASF Celtec®-P 1100 W). The data obtained allowed identifying an empirical model that takes into account the aging caused by the experiment. Finally, the methodology is criticized before proposing an alternative method.