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Simulated precipitation in a desert ecosystem reveals specific response of rhizosphere to water and a symbiont response in freshly emitted roots
No full textDemultiplexed sequences data are available at NCBI, SRA GenBank (BioProject: PRJNA1099423).International audienceHighlights: • Desert ecosystems are subjected to high water stress, limiting plant growth. • Drought increases the abundance of drought-tolerant Actinobacteria and Acidobacteria. • Microbiota of Haloxylon salicornicum roots and rhizosphere is responsive to water. • Symbionts taxa are differentially expressed following watering. • Little studied dark septate endophytes may be important plant symbiont.Abstract: Soil microbiota plays a fundamental role in nutrient cycles and plant fitness. However, the response of bacterial and fungal communities interacting with plants to an increase in the water regime in natural ecosystems has yet to be extensively studied. To address this matter, we studied the response of rhizospheric and root endophytic microbial communities to simulated intense precipitation in a natural desert environment. We used amplicon sequencing to identify bacterial (16S) and fungal (ITS) communities of Haloxylon salicornicum (Moq) Bunge ex Boiss., a pivotal plant species in natural ecosystems with a high potential for land restauration. Bacterial community composition included mostly Actinobacteriota in roots and Chloroflexi in rhizospheres, whereas fungal communities were mostly represented by Ascomycota. The decomposition of beta diversity revealed a significant share of i) turnover for bacteria between compartments, ii) nestedness for fungi according to compartments, and iii) nestedness for bacteria in both rhizosphere and roots according to watering. Differential abundances analyses between watering conditions identified respectively i) 29 and 37 differentially abundant bacterial families, and ii) 7 and 6 differentially abundant fungal families for rhizosphere and roots. Watering induced a rapid response from little characterized microbiota potentially involved in nutrient recycling, such as rhizobia and dark septate endophytes. These results provided evidence of the fundamental role of rare and intense precipitation in modifying the microbial composition of roots and rhizosphere of one desert plant species. Moreover, little studied taxa potentially crucial to the plant health in desert environments such as dark septate endophytes and Planctomycetota were identified as pioneer taxa colonizing freshly emitted roots. Collectively, our results help to improve the understanding of desert taxa response to water availability, and may guide future research on natural ecosystems restauration.Graphical abstract:https://ars.els-cdn.com/content/image/1-s2.0-S0929139324001434-ga1.jp
The Main Features and Microbiota Diversity of Fermented Camel Milk
No full textInternational audienceFermented camel milk, named shubat in Central Asia, is historically and culturally important because it is mainly consumed by Kazakh people who live not only in Kazakhstan but also in close neighboring countries. However, despite its cultural and dietetic significance for this local population, research on its composition and processing technology and the richness of its microflora is relatively scarce. The present review of this product, which is an important beverage in the Kazakh culture, provides up-to-date information regarding its main components and their variability according to different factors, surveys recent changes in the processing technologies for making it using modern techniques, and explores the biodiversity of its microflora. It was reported that the protein, vitamin C, and calcium contents in shubat vary between 1.19 and 5.63%, 28 and 417 mg L−1, and 1.03 and 1.88 g L−1. The lactose content totally disappears. Shubat contains a complex microbial consortium that contributes to its strong reputation for health benefits, but a scientific demonstration of these claims has only been partially achieved
Quantifying pesticide-contaminated sediment sources in tropical coastal environments (Galion Bay, French West Indies)
No full textInternational audiencePurpose Over the last 60 years, intensification of soil cultivation led to an acceleration of soil erosion and sediment delivery to river systems. In Martinique, this acceleration has led to the remobilization of a toxic insecticide (i.e. chlordecone) used in the 1970s-1990s to control banana weevil. A previous study attributed this accelerated remobilization to the application of glyphosate in plantations from the 1990s onwards. To further unambiguously confirm this link, the identification of soil erosion sources supplied to coastal sediment is essential. Methods Accordingly, sediment fingerprinting tools were adapted and applied to a coastal sediment core collected in the Galion Bay. Potential source samples (n=37) were collected across the drainage area. Along with the coastal sediment core layers, these samples were analysed for potential tracing properties. The optimal suite of tracers was then selected and introduced into an un-mixing model to quantify their contributions to coastal sediment. Results Results showed that subsoil (i.e. soil layer < 30 cm depth) and banana plantation soil surface supply the major sources of sediment (49-78% and 12-36%, respectively) to the Galion Bay and that their contributions increased since 2000, in line with chlordecone and glyphosate fluxes. Conclusion This evolution may be attributed to the higher sensitivity of banana plantations to erosion that may have been enhanced by the glyphosate application leaving the soil uncovered with vegetation and to the contamination of both topsoil and deep soil layers (< 30 cm) layers with chlordecone due to its vertical transfer along the soil profile and its redistribution across hillslope
Exploring the Impact of Urbanization on Avian Malaria Dynamics in Great Tits: Insights from a Study Across Urban and Non-Urban Environments
No full textCaptures were performed under personal ringing permits delivered by the CRBPO (Centre de Recherches par le Baguage des Populations d’Oiseaux, e.g., ringing permit for Anne Charmantier number 1907) for the Research Ringing Programme number 369. All experimental protocols were approved by the ethics committee for animal experimentation of Languedoc Roussillon (CEEA-LR, most recently approvedin 2018 for APAFIS#8608-2017012011062214 ) as well as by Regional Institutions (most recent bylaw issued on 07/04/2022 by the Prefecture n° 2B-2022-04-07-00002).Data and code used for this study are freely available on Zenodo (https://doi.org/10.5281/zenodo.10849522; Caizergues, 2024) and Gitub (https://github.com/AudeCaizergues/Malaria_Great_Tits), as well as the supplementary materials.International audienceUrbanization is a worldwide phenomenon that modifies the environment. By affecting the reservoirs of pathogens and the body and immune conditions of hosts, urbanization alters the epidemiological dynamics and diversity of diseases. Cities could act as areas of pathogen dilution or amplification, depending on whether urban features have positive or negative effects on vectors and hosts. In this study, we focused on a host species and investigated the prevalence and diversity of avian malaria parasites (Plasmodium/Haemoproteus sp. and Leucocytozoon sp.) in great tits (Parus major) living across an urbanization gradient. In general, we observed high prevalence in adult birds (from 95% to 100%), yet lower prevalence in fledglings (from 0% to 38%). We found a slight tendency for increased Plasmodium sp. prevalence with increasing urbanization in adults. Urban nestlings had higher Plasmodium sp. infection rates than non-urban nestlings. We found evidence of higher diversity of parasites in the most natural urban park; however, parasite diversity was similar across other urbanization levels (e.g. from a little artificialized park to a highly anthropized industrial area). Parasite lineages were not habitat specific. Only one Plasmodium sp. lineage (YWT4) was associated with urban areas and some rare lineages (e.g., AFR065) were present only in a zoo area, perhaps because of the presence of African birds. This study suggests that urbanization can lead to a parasite amplification effect and can favor different avian malaria lineages
En Inde, un contre modèle coopératif de micro- fermes avec peu de grands troupeaux
No full textInternational audienceL’élevage de bovins et buffles a une place historique en Inde en particulier pour la force de traction (et pour la fumure) qu’il a longtemps fourni aux cultures. Cette multifonctionnalité perdure dans les exploitations et les régions d’agriculture pluviale mais a été bouleversée ailleurs par la révolution verte. Les plus grandes exploitations irriguées ont tendance à abandonner l’élevage alors que celles de taille petite et moyenne, et même certains ouvriers agricoles sans terre, ont développé un élevage plus spécialisé dans la production de lait, profitant des réseaux de collecte coopératifs mis en place par la révolution blanche (1970-1996). L’élevage laitier contribue ainsi aux revenus de dizaines de millions de familles qui élèvent 3 bovins ou buffles et disposent pour plus de 60% d’entre elles de moins d’un hectare de terre cultivée. Elles s’appuient sur une diversité de ressources fourragères, parmi lesquelles les pailles de blé et de riz occupent une place centrale, complétées par des fourrages cultivés sur de micro-parcelles pour celles accédant à l’irrigation et par du fourrage spontané collecté ou pâturé pour les autres. D’après les données statistiques, l’ensemble permet une croissance continue de la production laitière de l’Inde, devenu premier producteur mondial à la fin des années 1990. Le pays assure ainsi son autosuffisance en matière laitière, et le niveau moyen de consommation de lait par habitant a progressé au cours des dernières décennies malgré la croissance démographique
How quality conventions shape the governance of the dairy value chains of Senegal
No full textInternational audienceBackground: Over the past few decades, the Senegalese dairy sector has undergone a rapid transformation. Urbanization and shifts in urban consumers’ eating habits have contributed to increased demand for dairy products and the emergence of new quality requirements. Aim: This paper examines how quality conventions influence the governance of dairy value chains in Senegal. We argue that value chain governance is not only determined by transaction characteristics, but also by how “lead firms” incorporate different quality conventions and translate these into value chain governance mechanisms. Methods: Through semi-structured interviews with consumer groups and stakeholders in the dairy value chain (producers, importers, processors, and retailers), we collected information on consumers’ selection criteria for dairy products and processors’ quality strategies, as well as on coordination mechanisms, contracts, and power relations within the value chain. Results: Our results show that the way lead firms normalize consumer expectations leads to specific organizational mechanisms in buyer-supplier relationships. Some combinations of quality strategies and governance mechanisms are better suited to fostering the sustainability of the local milk value chain in terms of social and economic development. Processors building viable relations with local milk producers are in particular ensuring the sustainability of the value chain, since they are able to cater to consumer preferences for fair and local milk-based products, while offering the guarantee of food safety processes. Conclusions: Our study highlights the indirect power that downstream actors (consumers) have on upstream actors (producers) via strategies (normalization) implemented by actors operating in an intermediate segment of the chain (processors). In other words, it shows that consumers, through their purchasing preferences, are playing a key role in the development of the local livestock sector
Introduction - La recherche interdisciplinaire en santé animale : enjeux et retours d’expériences
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Optimisation de l’usage des antibiotiques : vers des dispositifs multicritères de suivi de la santé et du bien-être des porcs et volailles
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The development of terrestrial ecosystems emerging after glacier retreat
No full textInternational audienceThe global retreat of glaciers is dramatically altering mountain and high-latitude landscapes, with new ecosystems developing from apparently barren substrates1–4. The study of these emerging ecosystems is critical to understanding how climate change interacts with microhabitat and biotic communities and determines the future of ice-free terrains1,5. Here, using a comprehensive characterization of ecosystems (soil properties, microclimate, productivity and biodiversity by environmental DNA metabarcoding6) across 46 proglacial landscapes worldwide, we found that all the environmental properties change with time since glaciers retreated, and that temperature modulates the accumulation of soil nutrients. The richness of bacteria, fungi, plants and animals increases with time since deglaciation, but their temporal patterns differ. Microorganisms colonized most rapidly in the first decades after glacier retreat, whereas most macroorganisms took longer. Increased habitat suitability, growing complexity of biotic interactions and temporal colonization all contribute to the increase in biodiversity over time. These processes also modify community composition for all the groups of organisms. Plant communities show positive links with all other biodiversity components and have a key role in ecosystem development. These unifying patterns provide new insights into the early dynamics of deglaciated terrains and highlight the need for integrated surveillance of their multiple environmental properties5
Evidence for circulation of Rift Valley fever virus in wildlife and domestic animals in a forest environment in Gabon, Central Africa
No full textInternational audienceRift Valley fever (RVF) is a mosquito-borne viral zoonosis caused by the Rift Valley fever virus (RVFV) that can infect domestic and wild animals. Although the RVFV transmission cycle has been well documented across Africa in savanna ecosystems, little is known about its transmission in tropical rainforest settings, particularly in Central Africa. We therefore conducted a survey in northeastern Gabon to assess RVFV circulation among wild and domestic animals. Among 163 wildlife samples tested using RVFV-specific RT-qPCR, four ruminants belonging to subfamily Cephalophinae were detected positive. The phylogenetic analysis revealed that the four RVFV sequences clustered together with a virus isolated in Namibia within the well-structured Egyptian clade. A cross-sectional survey conducted on sheep, goats and dogs living in villages within the same area determined the IgG RVFV-specific antibody prevalence using cELISA. Out of the 306 small ruminants tested (214 goats, 92 sheep), an overall antibody prevalence of 15.4% (95% CI [11.5–19.9]) was observed with a higher rate in goats than in sheep (20.1% versus 3.3%). RVFV-specific antibodies were detected in a single dog out of the 26 tested. Neither age, sex of domestic animals nor season was found to be significant risk factors of RVFV occurrence. Our findings highlight sylvatic circulation of RVFV for the first time in Gabon. These results stress the need to develop adequate surveillance plan measures to better control the public health threat of RVFV