Shared larval rearing environment, sex, female size and genetic diversity shape Ae. albopictus bacterial microbiota

The Asian tiger mosquito Aedes albopictus became of public health concern as it can replicate and transmit viral and filarial pathogens with a strong invasive success over the world. Various strategies have been proposed to reduce mosquito population's vectorial capacity. Among them, symbiotic control of mosquito borne disease offers promising perspectives. Such method is likely to be affected by the dynamics of mosquito-associated symbiotic communities, which might in turn be affected by host genotype and environment. Our previous study suggested a correlation between mosquitoes' origin, genetic diversity and midgut bacterial diversity. To distinguish the impact of those factors, we have been studying the midgut bacterial microbiota of two Ae. albopictus populations from tropical (La Re A union) and temperate (Montpellier) origins under controlled laboratory conditions. the two populations experienced random mating or genetic bottleneck. Microbiota composition did not highlight any variation of the alpha and beta-diversities in bacterial communities related to host's populations. However, sizes of the mosquitoes were negatively correlated with the bacterial a-diversity of females. Variations in mosquito sex were associated with a shift in the composition of bacterial microbiota. The females' mosquitoes also exhibited changes in the microbiota composition according to their size and after experiencing a reduction of their genetic diversity. These results provide a framework to investigate the impact of population dynamics on the symbiotic communities associated with the tiger mosquito.Peer reviewe

Is Toxin-Producing Planktothrix sp. an Emerging Species in Lake Constance?

Recurring blooms of filamentous, red-pigmented and toxin-producing cyanobacteria Planktothrix rubescens have been reported in numerous deep and stratified prealpine lakes, with the exception of Lake Constance. In a 2019 and 2020 Lake Constance field campaign, we collected samples from a distinct red-pigmented biomass maximum below the chlorophyll-a maximum, which was determined using fluorescence probe measurements at depths between 18 and 20 m. Here, we report the characterization of these deep water red pigment maxima (DRM) as cyanobacterial blooms. Using 16S rRNA gene-amplicon sequencing, we found evidence that the blooms were, indeed, contributed by Planktothrix spp., although phycoerythrin-rich Synechococcus taxa constituted most of the biomass (>96% relative read abundance) of the cyanobacterial DRM community. Through UPLC–MS/MS, we also detected toxic microcystins (MCs) in the DRM in the individual sampling days at concentrations of ≤1.5 ng/L. Subsequently, we reevaluated the fluorescence probe measurements collected over the past decade and found that, in the summer, DRM have been present in Lake Constance, at least since 2009. Our study highlights the need for a continuous monitoring program also targeting the cyanobacterial DRM in Lake Constance, and for future studies on the competition of the different cyanobacterial taxa. Future studies will address the potential community composition changes in response to the climate change driven physiochemical and biological parameters of the lake.publishe

Bacterial microcompartments for isethionate desulfonation in the taurine-degrading human-gut bacterium Bilophila wadsworthia

BackgroundBilophila wadsworthia, a strictly anaerobic, sulfite-reducing bacterium and common member of the human gut microbiota, has been associated with diseases such as appendicitis and colitis. It is specialized on organosulfonate respiration for energy conservation, i.e., utilization of dietary and host-derived organosulfonates, such as taurine (2-aminoethansulfonate), as sulfite donors for sulfite respiration, producing hydrogen sulfide (H2S), an important intestinal metabolite that may have beneficial as well as detrimental effects on the colonic environment. Its taurine desulfonation pathway involves the glycyl radical enzyme (GRE) isethionate sulfite-lyase (IslAB), which cleaves isethionate (2-hydroxyethanesulfonate) into acetaldehyde and sulfite.ResultsWe demonstrate that taurine metabolism in B. wadsworthia 3.1.6 involves bacterial microcompartments (BMCs). First, we confirmed taurine-inducible production of BMCs by proteomic, transcriptomic and ultra-thin sectioning and electron-microscopical analyses. Then, we isolated BMCs from taurine-grown cells by density-gradient ultracentrifugation and analyzed their composition by proteomics as well as by enzyme assays, which suggested that the GRE IslAB and acetaldehyde dehydrogenase are located inside of the BMCs. Finally, we are discussing the recycling of cofactors in the IslAB-BMCs and a potential shuttling of electrons across the BMC shell by a potential iron-sulfur (FeS) cluster-containing shell protein identified by sequence analysis.ConclusionsWe characterized a novel subclass of BMCs and broadened the spectrum of reactions known to take place enclosed in BMCs, which is of biotechnological interest. We also provided more details on the energy metabolism of the opportunistic pathobiont B. wadsworthia and on microbial H2S production in the human gut.publishe

P-TEFb et Brd4

La physiologie d’une cellule est dictée par l’intégration des signaux qu’elle reçoit et la mise en place de réponses adaptées par le biais, entre autres, de programmes transcriptionnels adéquats. Pour assurer un contrôle optimal de ces réponses, des mécanismes de régulation ont été sélectionnés, dont un processus de pause transcriptionnelle et de levée de cette pause par P-TEFb (positive transcription elongation factor) et Brd4 (bromodomain-containing protein 4). Le dérèglement de ce processus peut conduire à l’apparition de pathologies. P-TEFb et Brd4 ont ainsi émergé au cours des dernières années comme des cibles thérapeutiques potentielles dans le cadre des cancers et du syndrome d‘immunodéficience acquise (sida) notamment

A top 5 list for French general practice

International audienceBackground: Medical overuse is an issue that has recently gained attention. The "Choosing Wisely" campaign invited each specialty in each country to create its own top five lists of care procedures with a negative benefit-risk balance to promote dialogue between patients and physicians. This study aims to create such a list for French general practice.Methods: A panel of general practitioners (GPs) suggested care procedures that they felt ought to be prescribed less. Using the Delphi method, a short list of those suggestions was selected. Systematic literature reviews were performed for each item on the short list. The results were presented to the panel to assist with the final selection of the top five list.Results: The panel included 40 GPs. The list includes: i/ antibiotics prescription for acute bronchitis, nasopharyngitis, otitis media with effusion, or uncomplicated influenza, ii/ systematic prostate specific antigen testing in men older than 50, iii/ prescription of cholinesterase inhibitors for mild cognitive impairment and for Alzheimer's disease and memantine for Alzheimer's disease, iv/ statins prescription in primary prevention of cardio-vascular risk in older patients, and v/ benzodiazepine or benzodiazepine-like agents prescription for generalised anxiety, insomnia, and for all indications in older patients.Conclusions: This study resulted in a French top five list in general practice using a panel of GPs. All the items selected have a negative risk-benefit balance and are frequently prescribed by French general practitioners. This list differs from other top five lists for general practice, reflecting the local medical culture

Relationship between mosquito size and the midgut bacterial α-diversity.

<p>Fitted GAMM model (solid line) and its standard errors (dashed lines) are represented for (A) Male and (B) female samples.</p

Samples used in the study.

<p>Samples used in the study.</p