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Culturable macroplastic-associated potential human pathogens in coral reef lagoons, Madagascar
No full textInternational audiencePotentially human pathogenic bacteria (PHPBs) have been detected in plastic-associated marine microbiomes, primarily through DNA-based methods. However, data on their culturability and concentrations on plastics remain limited, yet are essential to assess actual health risks. To address this gap, 70 floating macroplastic and 20 seawater samples were collected from two human-impacted reef lagoons in southwestern Madagascar (Atsimo-Andrefana region). PHPBs were cultured from their microbiomes using selective media and quantified. Macroplastics were predominantly polypropylene (34 %) and polyamide (31 %). In increasing order of concentration, four culturable PHPBs, Staphylococcus aureus, Escherichia coli, Enterococcus faecalis, and Vibrio Harveyi clade species, were identified on both macroplastics and in seawater, across all sites and polymer types. Notably, 52 % of macroplastic samples harbored two PHPB species simultaneously, while only 7 % were PHPB-free. Concentrations of all PHPBs were consistently and significantly higher on macroplastics than in seawater, regardless of the measurement unit or polymer type, with the Vibrio Harveyi clade being the most abundant. No significant correlations were observed among PHPB species concentrations, suggesting limited interaction and independent colonization. These findings indicate that floating macroplastics may serve as reservoirs and fomites for viable PHPBs. However, their potential impacts on ecosystems and human health should be interpreted cautiously. We emphasize the need to contextualize PHPB concentration data by considering factors such as exposure pathways, environmental persistence, and bacterial virulence, rather than relying solely on concentration-based comparisons, which may lead to misinterpretation
Introducing gold-standard essential gene datasets for Pseudomonas aeruginosa to enhance Tn-Seq analyses
No full textInternational audienceTransposon Sequencing (Tn-Seq) is a high-throughput technique that utilizes transposon mutant libraries to assess gene fitness or essentiality under specific conditions potentially identifying novel therapeutic targets. However, the diversity of statistical methods, bioinformatics tools, and parameters complicates the selection of the most appropriate and reliable analysis pipeline for a given dataset. A significant limitation of existing studies is the absence of a gold-standard set of essential genes (EGs) for evaluating the analysis process. Relying on the original study as a gold-standard is suboptimal, as these results may have been obtained using non-optimal tools. Here, we introduce reliable EG datasets for Pseudomonas aeruginosa to enhance Tn-Seq analyses. By utilizing literature data and sequencing of six samples from PA14 Wild-Type (WT) and PA14 OprD-deficient (Δ oprD ), grown in LB medium, we compared EG lists generated by several statistical methods of TRANSIT2 and by the FiTnEss tools. We established a reference dataset of 84 genes found in P. aeruginosa and another gold-standard set composed of 115 genes specific to PA14 grown in LB. Our findings revealed that depending on the analysis method used, retrieval rates of gold-standard genes ranged from 0% to 100%. The Hidden-Markov Model (HMM) method available in TRANSIT2 identified approximately 90% of gold-standard EGs, while FiTnEss identified up to 100%. This study addressed a critical gap in the field by providing gold-standard sets of EGs, enabling comparative evaluation of Tn-Seq analysis methods to help researcher select the most suitable bioinformatics pipeline for a given Tn-Seq dataset. We anticipate that our results will facilitate Tn-Seq analysis comparisons, harmonize P. aeruginosa -related studies, promote standardization and enhance reproducibility. Ultimately, this will lead to more reliable identification of EGs and potential therapeutic targets in P. aeruginosa , advancing our understanding of this important pathogen
Health-related quality of life in nondialysis CKD patients: a comprehensive description of five-year trajectories among the CKD–REIN cohort
No full textInternational audienceBackground Few studies have analyzed the quality-of-life trajectories of CKD patients not receiving kidney replacement therapy, and the results are inconsistent. This study aimed to identify subgroups of long-term trajectories of the physical (PCS) and mental components summary (MCS) of the KDQOL-36 in patients with CKD stages 3-5 and to describe their associations with patient characteristics. MethodsWe used a joint latent class-mixed model to identify the PCS and MCS trajectories of 2716 patients with CKD stages 3-5 enrolled in the CKD-Renal Epidemiology and Information Network (CKD-REIN) cohort study. Qualityof-life was assessed annually using the Kidney Disease Quality-of-life-36. All the participants had scores for at least one-time point. ResultsDuring a median follow-up of 5.56 (4.77-6.16) years, 664 participants started KRT, and 465 died before KRT. We identified three profiles of PCS: a "High and declining PCS trajectory" which included 5.89% of patients, characterized by a higher initial score and a decline of more than 10 points over three years; a "High and stable PCS trajectory" in 50.96%, characterized by a higher initial score that remained stable; and a "Low and stable PCS trajectory" in 43.15%, characterized by a lower initial score that remained stable. For MCS, we identified a single, stable mean trajectory over time. A decline in eGFR was faster in participants with a "High and declining PCS trajectory" (-4.30 mL/min per years). Patients in the high and stable trajectory had a more favorable clinical and biological profile at baseline. The evolution of the specific dimensions of CKD within each PCS trajectory followed a pattern similar to that of the PCS itself. Conclusions The study highlights substantial heterogeneity in PCS evolution in patients with CKD, which contrasts with the stability of that for MCS.</div
Switching cell wall-bound polysaccharides to secreted polysaccharides in lactobacilli
No full textInternational audienceBacterial exopolysaccharides (EPS) are carbohydrate polymers secreted into the environment. EPS produced by lactic acid bacteria have many valuable properties in the food and health sectors. In this study, we isolated spontaneous mutants of lactobacilli that overproduce EPS, using a selection method based on their slow sedimentation rate in a semi-liquid medium. In the mutants selected from several strains, we detected a missense mutation in epsD, which encodes a tyrosine kinase, or an insertion in epsC, which encodes its transmembrane modulator. Both genes were located within a gene cluster involved in Wzy-dependent polysaccharide biosynthesis. We then characterized selected Lacticaseibacillus rhamnosus mutants in detail to gain insights into the mechanisms involved in EPS overproduction. We demonstrated that the single mutation D94L in the EpsD catalytic site prevents EpsD autophosphorylation. The chemical structure of the overproduced EPS was established, and consists of heptasaccharide repeating units with pyruvate substituents. In the wild-type parental strain, a polysaccharide with an identical structure was found covalently bound to the cell wall (CW) and covering the bacterial surface. In conclusion, our results indicate that the switch from CW-bound polysaccharides to EPS released into the environment is associated with a defect in autophosphorylation of the EpsD tyrosine kinase
A new chemotype that opens the S2∗ pocket of the 3CL protease exhibits antiviral activity against SARS-CoV-2
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Mitral Annulus Calcification: Pathophysiology, Outcome, and Imaging Evaluation
No full textInternational audienceMitral annulus calcification (MAC) is a chronic, degenerative process characterized by calcium deposition in the mitral annulus. It is commonly observed in elderly individuals and those with chronic kidney disease, hypertension, and metabolic disorders. MAC has been increasingly recognized as a marker of cardiovascular disease and is associated with adverse clinical outcomes, including mitral valve dysfunction, arrhythmias, and increased cardiovascular mortality. The pathophysiology of MAC involves endothelial dysfunction, chronic inflammation, and osteogenic differentiation of valvular interstitial cells, driven by risk factors such as aging, chronic kidney disease, diabetes mellitus, and hypertension. Imaging modalities, including echocardiography and computed tomography (CT) play a crucial role in the diagnosis, assessment, and risk stratification of MAC. The presence of MAC complicates mitral valve interventions, making surgical and transcatheter approaches challenging. Despite advancements in imaging and therapeutic strategies, MAC remains a significant challenge in cardiovascular medicine, necessitating further research into its pathophysiology, optimal management strategies, and long-term outcomes
Évaluation d'un atelier délibératif portant sur la Note de Politique "Vaccination, freins et leviers tirés de l'expérience du COVID-19 au Niger"
No full textInternational audienceIntroduction: As part of the Alliance SHS Africa (ASA) project, the Center for Medical and Health Research (CERMES) organized a Deliberative Workshop (DA) on January 15, 2025, to present the results, discuss, and co-develop recommendations based on a Policy Note (PN) entitled "Vaccination: Obstacles and Opportunities Drawn from the Experience of COVID-19 in Niger." Methodology: The workshop brought together 46 institutional stakeholders, healthcare professionals, researchers, the population receiving vaccinations, and community representatives. The evaluation, consisting of a qualitative descriptive analysis, was based on a 19-item self-administered semi-structured questionnaire addressing the relevance, clarity, and feasibility of the recommendations, as well as the intention to use the results. Results: 1) Participants largely praised the clarity of the PN and the relevance of the recommendations; 2) The group discussions led to the reformulation of certain proposals, strengthening their realism and contextualization; 3) A large proportion of participants expressed their intention and ability to apply the recommendations in their professional settings, while others highlighted the institutional and hierarchical obstacles to their implementation; 4) the overall evaluation of the knowledge transfer strategy was considered positive, emphasizing the effectiveness of intersectoral dialogue and the increased ownership of research results. Discussion: This experience illustrates the added value of a participatory knowledge transfer mechanism for bridging the gap between science and public policy, while also highlighting the need for monitoring mechanisms to ensure the sustainability of knowledge transfer.Introduction : Dans le cadre du projet Alliance SHS Afrique (ASA), le Centre de Recherche Médicale et Sanitaire (CERMES) avait organisé, le 15 janvier 2025, un Atelier Délibératif (AD) afin de présenter les résultats, discuter et co-construire des recommandations à partir d’une Note de Politique (NP) intitulée « Vaccination, freins et leviers tirés de l’expérience du COVID-19 au Niger ». Méthode : L’atelier a réuni 46 acteurs institutionnels, professionnels de santé, chercheurs, population bénéficiaire des vaccinations et représentants communautaires. L’évaluation ayant consisté en un analyse descriptive qualitative, se fondait sur un questionnaire semi-directif auto-administré de 19 items portant sur la pertinence, la clarté et la faisabilité des recommandations, ainsi que sur l’intention d’utiliser les résultats. Résultats : 1) les participants avaient largement salué la clarté de la NP et la pertinence des recommandations ; 2) les discussions collectives avaient permis de reformuler certaines propositions, renforçant leur réalisme et leur contextualisation ; 3) une grande partie des participants exprimait leur intention et leur capacité à appliquer les recommandations dans leurs milieux professionnels, tandis qu’une autre partie soulignait les obstacles institutionnels et hiérarchiques à leur mise en œuvre ; 4) l’évaluation globale de la stratégie de transfert était jugée positive, tout en mettant en avant l’efficacité du dialogue intersectoriel et l’appropriation accrue des résultats de recherche. Discussion : Cette expérience illustre la valeur ajoutée d’un dispositif de TC participatif pour rapprocher science et décision publique, tout en soulignant la nécessité de mécanismes de suivi afin d’assurer la durabilité de l’appropriation
An open-source closed-loop Virtual Reality system to investigate social interactions and collective behavior in fish
No full textCorrection: An open-source closed-loop Virtual Reality system to investigate social interactions and collective behavior in fishhttps://journals.plos.org/plosone/article?id=10.1371/journal.pone.0343509International audienceAbstract This study introduces a low-cost, open source, immersive Virtual Reality (VR) system designed to investigate real-time social interactions and collective behaviors in fish. Understanding collective animal behaviors, such as schooling in fish, presents significant observational challenges due to rapid and complex interactions. To address these difficulties, we developed an innovative closed-loop VR environment allowing precise control and measurement of interactions between real and virtual fish. This setup incorporates high-speed 3D tracking, real-time visual feedback, and automated data processing, creating realistic and interactive scenarios. We present experimental results, obtained with Rummy-nose tetras ( Hemigrammus rhodostomus ), showing that freely moving real fish consistently adjusted their speed, depth, and spatial positioning to follow virtual fish effectively. Fish matched moderate virtual speeds comfortably, struggled slightly at higher speeds, and actively maintained vertical positioning to sustain group cohesion. Fish also displayed significant environmental awareness, adjusting their proximity to the tank walls while maintaining visual contact with virtual fish. The implementation of this VR system provides critical insights into sensory and cognitive processes underlying collective movement and decision-making in fish. By revealing both flexibility and constraints in fish behavior, our findings underscore the potential of VR technology to study social interactions in controlled yet realistic settings. Ultimately, this VR system advances our understanding of collective animal behaviors and lays a foundation for future studies across different species, enhancing insights into the neural and behavioral mechanisms of group dynamics
Co-speciation and host-switching drives diversity of picornaviruses and sapoviruses in Malagasy fruit bats
No full textInternational audienceBats are reservoir hosts for numerous well-known zoonotic viruses, but their broader virus-hosting capacities remain understudied. Picornavirales are an order of enteric viruses that cause disease across a wide range of mammalian hosts, including Hepatitis A in humans and foot-and-mouth disease in ungulates. Host-switching and recombination drive the diversification of Picornavirales worldwide. Picornaviridae and Caliciviridae (families within Picornavirales) have been described in bats across mainland Africa, but surveillance for these viruses has been rare in the Southwest Indian Ocean Islands. Prior work in Madagascar has described numerous bat viruses, some with zoonotic potential, that demonstrate both high identity to and extreme divergence from viruses found in sister bat species in Africa. Using metagenomic Next Generation Sequencing of urine and fecal samples obtained from three species of endemic Malagasy fruit bats (Eidolon dupreanum, Pteropus rufus, and Rousettus madagascariensis), we identify and describe 13 full-length and 38 partial-length genomic sequences within the Picornaviridae and Caliciviridae families (36 picornavirus and 15 Sapovirus sequences). We find evidence that host-switching between Madagascar and mainland African bat picornaviruses and sapoviruses, followed by host-parasite co-speciation, likely shaped the diversification pattens of these novel sequences, with little evidence for cross-species transmission among Malagasy bat species in close contact
Two anchoring proteins control daughter apical complex assembly in Toxoplasma gondii
No full textDuring Toxoplasma gondii division, the apical complex—comprising the conoid, apical polar ring (APR), and preconoidal rings—assembles with precise spatiotemporal coordination to form functional daughter buds. Despite their essential roles in invasion, motility, and division, the scaffolding proteins orchestrating this ordered assembly have remained largely unidentified. Here, we identify and characterize RCC1-2 and APR8 as essential factors directing distinct, sequential phases of daughter cell apical complex construction. Both proteins are recruited with precise spatial and temporal dynamics to the daughter buds, where they function as scaffolds rather than static structural components. APR8 transiently occupies the basal region of the APR specifically in early daughter cells. It is dispensable for conoid and PCR initiation, yet its loss causes APR collapse, abolishes SPMT anchoring, and eventually arrests conoid maturation. In contrast, RCC1-2 localizes beneath the APR basal layer and persists throughout daughter cell development, where it contributes to stabilizing the attachment of SPMTs to the APR. Notably, in situ cryo-electron tomography further reveals that the interspersed pillars bridging SPMTs ends to the APR fail to form properly in RCC1-2-depleted parasites. These findings map a hierarchical RCC1-2/APR8-dependent scaffolding process that advances our understanding of parasite replication