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Petal-shaped femoral lobes facilitate gliding in orchid mantises
No full textInternational audienceTo glide in forest canopies, arboreal vertebrates evolved various skin-derived aerodynamic structures, such as patagial membranes or webbing, but no comparable structure has been reported from wingless arboreal arthropods.1,2,3 Orchid mantises (Hymenopus coronatus) have been traditionally considered a textbook example of flower mimicry for ∼200 years due to their highly expanded, petal-shaped femoral lobes. However, the empirical evidence substantiating the petal-mimicry function of the femoral lobes has not been entirely conclusive.4,5,6 Observational and experimental evidence suggests that these lobes do not contribute to flower mimicry for luring pollinators6,7 and likely serve other functions.7,8 After observing their aerial escape initiated with active jumping, we hypothesized that orchid mantises can glide and that their femoral lobes are used for gliding. Through behavioral investigations and morphological analyses, we show that orchid mantis nymphs are excellent gliders, exhibiting the shallowest gliding trajectories observed in terrestrial invertebrates.9,10,11,12,13 The lobe extensions on their femoral segments are cambered airfoils, which increase the mantis projected area by ∼36% and play a vital role in the aerodynamic underpinning of the observed gliding. Despite a 165-fold increase in body mass throughout ontogeny, older female mantis nymphs maintained a persistent gliding capability. We further showed a notable 40%–56% reduction in wing loading attributed to the positive size allometry of these lobes, indicating a clear promotion of gliding throughout ontogeny. This is the first documentation of gliding-adapted “leg wings” in a wingless arthropod. The evolution of such structures is potentially common among arboreal arthropods and demands a systematic re-examination
The structural landscape and diversity of Pyricularia oryzae MAX effectors revisited
No full textInternational audienceMagnaporthe AVRs and ToxB-like (MAX) effectors constitute a family of secreted virulence proteins in the fungus Pyricularia oryzae (syn . Magnaporthe oryzae) , which causes blast disease on numerous cereals and grasses. In spite of high sequence divergence, MAX effectors share a common fold characterized by a ß-sandwich core stabilized by a conserved disulfide bond. In this study, we investigated the structural landscape and diversity within the MAX effector repertoire of P . oryzae . Combining experimental protein structure determination and in silico structure modeling we validated the presence of the conserved MAX effector core domain in 77 out of 94 groups of orthologs (OG) identified in a previous population genomic study. Four novel MAX effector structures determined by NMR were in remarkably good agreement with AlphaFold2 (AF2) predictions. Based on the comparison of the AF2-generated 3D models we propose a classification of the MAX effectors superfamily in 20 structural groups that vary in the canonical MAX fold, disulfide bond patterns, and additional secondary structures in N- and C-terminal extensions. About one-third of the MAX family members remain singletons, without strong structural relationship to other MAX effectors. Analysis of the surface properties of the AF2 MAX models also highlights the high variability within the MAX family at the structural level, potentially reflecting the wide diversity of their virulence functions and host targets
Environmental trade-offs of meeting nutritional requirements with a lower share of animal protein for adult subpopulations
No full textInternational audienceDecreasing the share of protein contributed by animal-based foods is recommended to move towards more sustainable and healthier diets. This study aimed to assess potential environmental impacts of diets with a lower share of animal protein. The diets were modeled to include the minimum share of animal protein in total protein that met nutrient requirements and did not increase costs. The new diets also minimized the difference in the quantity of food from those of observed (OBS) diets. They were modeled for five adult subpopulations (defined by sex and age) using mathematical optimization. The model was created by combining the INCA2 database (to model OBS diets in the French population) and a database of 207 food items to adjust nutritional and price parameters. All modeled diets satisfied nutritional and cost constraints. A low-animal-protein (LAP) diet was identified for each subpopulation by progressively decreasing the share of animal protein by steps of 5% until the recommended quantity of protein and/or consumption constraints were no longer satisfied. Potential environmental impacts of the LAP diets in eight impact categories were calculated using life cycle assessment (LCA) and life cycle inventories from Agribalyse® 3.0. A LAP diet for the entire population was calculated as a weighted mean of the subpopulations’ LAP diets. The share of animal protein decreased from 70% in the OBS diet to 50% in the LAP diet. Compared to the OBS diet, the LAP diet decreased five environmental impacts: climate change (greenhouse gas emissions), acidification (emissions of acidifying compounds) and land occupation (all by more than 30%), cumulative energy demand (by 23%) and marine eutrophication (by 13%). Conversely, it increased three environmental impacts: freshwater eutrophication and water use (both by ca. 40%) and biodiversity damage potential (potential loss of species associated with land use) (by 66%). These results suggest that decreasing the share of animal protein to 50% is compatible with nutritional requirements, affordability and consumption constraints, but would have mixed effects on the environment
Farmers' Behavior and Innovations' Adoption Processes in Rural Sahel: Case of Supplemental Irrigation from Farm Ponds in Burkina Faso
No full textInternational audienceSince 2012, development actors have promoted supplemental irrigation from farm ponds to cope with rainfall variability in Burkina Faso, but few farmers have adopted the innovation. Although harvesting runoff water in ponds is an old practice in Sahelian Burkina Faso, farmers were not accustomed to irrigating crops with stored rainwater. In the context of low adoption rates of innovation, it is useful to understand the behavior and profile of those who do adopt innovations. This article analyzes farmers’ adoption processes by focusing on their socio-economic characteristics and on stakeholders’ social representations of the innovation. We conducted field surveys of 18 institutional actors and 33 adopters. Our results showed that farmers have favorable attitudes towards adoption and that institutional actors help strengthen these intentions by influencing farmers’ social norms and capacities to act, but that the farmers’ perceptions of difficulties, risk, and social norms prevent them from adopting. As supplemental irrigation from farm ponds is a labor-intensive innovation, farmers who cannot call on community labor or hire seasonal workers are limited in their adoption of the innovation. In addition, the fear of being subjected to mockery by members of the community or the fear of losing social prestige is a social norm that may limit the adoption of the innovation. We characterized the profile of adopters, who mainly have a low income but a high social status that allows them to receive support from policy-makers. Farmers have a preference for growing cash crops rather than subsistence crops the latter being the goal of most institutional actors. Our study showed that farmers’ preferences and perceptions of social norms, as well as the characteristics of innovations, are important as socio-economic and technical factors in farmers’ adoption processes
Quantitative imaging and semiotic phenotyping of mitochondrial network morphology in live human cells
No full textInternational audienceThe importance of mitochondria in tissue homeostasis, stress responses and human diseases, combined to their ability to transition between various structural and functional states, makes them excellent organelles for monitoring cell health. There is therefore a need for technologies to accurately analyze and quantify changes in mitochondrial organization in a variety of cells and cellular contexts. Here we present an innovative computerized method that enables accurate, multiscale, fast and cost-effective analysis of mitochondrial shape and network architecture from confocal fluorescence images by providing more than thirty features. In order to facilitate interpretation of the quantitative results, we introduced two innovations: the use of Kiviat-graphs (herein named MitoSpider plots) to present highly multidimensional data and visualization of the various mito-cellular configurations in the form of morphospace diagrams (called MitoSigils). We tested our fully automated image analysis tool on rich datasets gathered from live normal human skin cells cultured under basal conditions or exposed to specific stress including UVB irradiation and pesticide exposure. We demonstrated the ability of our proprietary software (named MitoTouch) to sensitively discriminate between control and stressed dermal fibroblasts, and between normal fibroblasts and other cell types (including cancer tissue-derived fibroblasts and primary keratinocytes), showing that our automated analysis captures subtle differences in morphology. Based on this novel algorithm, we report the identification of a protective natural ingredient that mitigates the deleterious impact of hydrogen peroxide (H2O2) on mitochondrial organization. Hence we conceived a novel wet-plus-dry pipeline combining cell cultures, quantitative imaging and semiotic analysis for exhaustive analysis of mitochondrial morphology in living adherent cells. Our tool has potential for broader applications in other research areas such as cell biology and medicine, high-throughput drug screening as well as predictive and environmental toxicology
Lipolysis of Burkholderia lata LBBIO-BL02 lipase in simulated human digestive environments: A candidate for enzyme replacement therapy
No full textInternational audienceLipases, crucial enzymatic tools for potential replacement therapy, must possess specific characteristics for ideal functionality. An effective lipase replacement therapy necessitates the maintenance of robust lipolytic activity at both acidic and neutral pH levels, as well as in the presence of normal and low physiological concentrations of intra-intestinal bile salts. Additionally, it should resist proteolytic digestion by pepsin and trypsin, actively hydrolyzing a wide range of dietary triacylglycerols. This study focuses on the production, purification and biochemical characterization of Burkholderia lata LBBIO-BL02 lipase, emphasizing its potential in digestive environments. The enzyme demonstrated activity against fatty acids with carbon chains from 8 to 20, displaying a preference for palmitic (16:0) and oleic (18:1) acids. It displayed regioselectivity for the external positions sn-1 and sn-3 of triacylglycerol. Kinetic revealed Michaelis-Menten behavior, with a Km of 22 mmol and Vmax of 12.7 mmol/min, with kcat 225s(-1) and catalytic efficiency 10(4) mol(-1) s(-1). Operating optimally at 55 degrees C, the enzyme showed stability at 60 degrees C. The optimal pH range was 4-9, retaining >100% of initial activity in the pH range 2.2-10.0. In simulated gastric environments, the lipase exhibited high activity and stability under low pH conditions, demonstrating remarkable activation in the presence of high bile salt concentrations. BLL emerged as an enzyme comparable in potency to gastric and pancreatic lipases, encompassing a substrate variety while resisting proteases and bile salts. The biochemical insights from this study lay a robust foundation for further exploration of BLL in enzyme replacement therapy
Delimiting species with single-locus DNA sequences
No full textInternational audienceDNA sequences are increasingly used for large-scale biodiversity inventories. Because these genetic data avoid the time-consuming initial sorting of specimens based on their phenotypic attributes, they have been recently incorporated into taxonomic workflows for overlooked and diverse taxa. Major statistical developments have accompanied this new practice, and several models have been proposed to delimit species with single-locus DNA sequences. However, proposed approaches to date make different assumptions regarding taxon lineage history, leading to strong discordance whenever comparisons are made among methods. Distance-based methods, such as Automatic Barcode Gap Discovery (ABGD) and Assemble Species by Automatic Partitioning (ASAP), rely on the detection of a barcode gap (i.e., the lack of overlap in the distributions of intraspecific and interspecific genetic distances) and the associated threshold in genetic distances. Network-based methods, as exemplified by the REfined Single Linkage (RESL) algorithm for the generation of Barcode Index Numbers (BINs), use connectivity statistics to hierarchically cluster-related haplotypes into molecular operational taxonomic units (MOTUs) which serve as species proxies. Tree-based methods, including Poisson Tree Processes (PTP) and the General Mixed Yule Coalescent (GMYC), fit statistical models to phylogenetic trees by maximum likelihood or Bayesian frameworks. Multiple webservers and stand-alone versions of these methods are now available, complicating decision-making regarding the most appropriate approach to use for a given taxon of interest. For instance, tree-based methods require an initial phylogenetic reconstruction, and multiple options are now available for this purpose such as RAxML and BEAST. Across all examined species delimitation methods, judicious parameter setting is paramount, as different model parameterizations can lead to differing conclusions. The objective of this chapter is to guide users step-by-step through all the procedures involved for each of these methods, while aggregating all necessary information required to conduct these analyses. The “Materials” section details how to prepare and format input files, including options to align sequences and conduct tree reconstruction with Maximum Likelihood and Bayesian inference. The Methods section presents the procedure and options available to conduct species delimitation analyses, including distance-, network-, and tree-based models. Finally, limits and future developments are discussed in the Notes section. Most importantly, species delimitation methods discussed herein are categorized based on five indicators: reliability, availability, scalability, understandability, and usability, all of which are fundamental properties needed for any approach to gain unanimous adoption within the DNA barcoding community moving forward
Analyse des sorties internationales des firmes : quelles lectures complémentaires au couple motifs-modalités de sortie ? Illustration par le cas de Carrefour en Asie
No full textInternational audienceAlors qu’ils sont aussi nombreux que les cas d’entrées à l’international, les retraits de marchés ont reçu peu d’intérêt de la recherche académiques et ont souvent été assimilés à des échecs commerciaux, stratégiques ou financiers, à travers des analyses empiriques souvent limités à des niveaux organisationnels et nationaux. Dans cette recherche empirique qualitative basée sur un recueil de données externes (presse et rapports d’activité) et appliquée à la présence asiatique de Carrefour, nous analysons les mouvements d’entrées-sorties de la firme de distribution française dans une optique longitudinale (2000-2020) afin d’expliquer ses principaux retraits des marchés asiatiques. En l’espace de 20 ans, le groupe français s’est retiré de la quasi-totalité des pays asiatiques (Japon, Inde, Chine, Indonésie, Thaïlande, etc.) alors que cette région était considérée comme prioritaire au début des années 90. Les résultats confirment la nécessité d’une analyse combinée des motifs et des modalités de sortie et suggèrent l’intégration d’un regard macro régional et multi-niveaux de l’internationalisation. Enfin cette recherche propose plusieurs lectures complémentaires. Nos résultats suggèrent des explications des retraits internationaux en termes de liens entre les entrées et les sorties, une analyse par les actions-réactions stratégiques des groupes et des concurrents et esquissent les contours d’un modèle « séquentiel » des sorties des firmes des marchés
Historical Review of Sugarcane Streak Mosaic Virus that Has Recently Emerged in Africa
No full textInternational audienceSugarcane streak mosaic virus (SCSMV), now assigned to the genus Poacevirus of the family Potyviridae, was reported for the first time in 1932 in Louisiana and was believed to be strain F of sugarcane mosaic virus (SCMV) for more than six decades. SCMV-F was renamed SCSMV in 1998 after partial sequencing of its genome and phylogenetic investigations. Following the development of specific molecular diagnostic methods in the 2000s, SCSMV was recurrently found in sugarcane exhibiting streak mosaic symptoms in numerous Asian countries but not in the Western hemisphere or in Africa. In this review, we give an overview of the current knowledge on this disease and the progression in research on SCSMV. This includes symptoms, geographical distribution and incidence, diagnosis and genetic diversity of the virus, epidemiology, and control. Finally, we highlight future challenges, as sugarcane streak mosaic has recently been found in Africa, where this disease represents a new threat to sugarcane production