Explosive breeding in tropical anurans: Environmental triggers, community composition and acoustic structure

Background: Anurans largely rely on acoustic communication for sexual selection and reproduction. While multiple studies have focused on the calling activity patterns of prolonged breeding assemblages, species that concentrate their reproduction in short-time windows, explosive breeders, are still largely unknown, probably because of their ephemeral nature. In tropical regions, multiple species of explosive breeders may simultaneously aggregate leading to massive, mixed and dynamic choruses. To understand the environmental triggers, the phenology and composition of these choruses, we collected acoustic and environmental data at five ponds in French Guiana during a rainy season, assessing acoustic communities before and during explosive breeding events. Results: We detected in each pond two explosive breeding events, lasting between 24 and 70 h. The rainfall during the previous 48 h was the most important factor predicting the emergence of these events. During explosive breeding events, we identified a temporal factor that clearly distinguished pre- A nd mid-explosive communities. A common pool of explosive breeders co-occurred in most of the events, namely Chiasmocleis shudikarensis, Trachycephalus coriaceus and Ceratophrys cornuta. Nevertheless, the species composition was remarkably variable between ponds and for each pond between the first and the second events. The acoustic structure of explosive breeding communities had outlying levels of amplitude and unexpected low acoustic diversity, significantly lower than the communities preceding explosive breeding events. Conclusions: Explosive breeding communities were tightly linked with specific rainfall patterns. With climate change increasing rainfall variability in tropical regions, such communities may experience significant shifts in their timing, distribution and composition. In structurally similar habitats, located in the same region without obvious barriers, our results highlight the variation in composition across explosive breeding events. The characteristic acoustic structure of explosive breeding events stands out from the circadian acoustic environment being easily detected at long distance, probably reflecting behavioural singularities and conveying heterospecific information announcing the availability of short-lived breeding sites. Our data provides a baseline against which future changes, possibly linked to climate change, can be measured, contributing to a better understanding on the causes, patterns and consequences of these unique assemblagesThis research was supported by the Labex CEBA (Centre d’Étude de la Biodiversité Amazonienne), which provided fnancial and logistic support for the data collection. JSU was supported by COLCIENCIAS (Doctoral Scholarship of the Colombian government, 2014 call #646). DLL was supported by a Global Marie S. Curie fellowship (European Commission, program H2020, EAVESTROP–661408), a postdoctoral grant Atracción de Talento Investigador (Comunidad de Madrid, CAM, Spain, 2016-T2/AMB-1722), and acknowledges funding provided by the Ministerio de Economía, Industria y Competitividad (CGL2017-88764-R, MINECO/AEI/FEDER, Spain). None of the funders had any role in the design, analysis, interpretation of results or writing the manuscrip

Multiple-contrast X-ray micro-CT visualization of colon malformations and tumours in situ in living mice

International audienc

IL-26 inhibits hepatitis C virus replication in hepatocytes

Publisher Copyright: © 2021 European Association for the Study of the LiverBackground & Aims: Interleukin-26 (IL-26) is a proinflammatory cytokine that has properties atypical for a cytokine, such as direct antibacterial activity and DNA-binding capacity. We previously observed an accumulation of IL-26 in fibrotic and inflammatory lesions in the livers of patients with chronic HCV infection and showed that infiltrating CD3+ lymphocytes were the principal source of IL-26. Surprisingly, IL-26 was also detected in the cytoplasm of hepatocytes from HCV-infected patients, even though these cells do not produce IL-26, even when infected with HCV. Based on this observation and possible interactions between IL-26 and nucleic acids, we investigated the possibility that IL-26 controlled HCV infection independently of the immune system. Methods: We evaluated the ability of IL-26 to interfere with HCV replication in hepatocytes and investigated the mechanisms by which IL-26 exerts its antiviral activity. Results: We showed that IL-26 penetrated HCV-infected hepatocytes, where it interacted directly with HCV double-stranded RNA replication intermediates, thereby inhibiting viral replication. IL-26 interfered with viral RNA-dependent RNA polymerase activity, preventing the de novo synthesis of viral genomic single-stranded RNA. Conclusions: These findings reveal a new role for IL-26 in direct protection against HCV infection, independently of the immune system, and increase our understanding of the antiviral defense mechanisms controlling HCV infection. Future studies should evaluate the possible use of IL-26 for treating other chronic disorders caused by RNA viruses, for which few treatments are currently available, or emerging RNA viruses. Lay summary: This study sheds new light on the body's arsenal for controlling hepatitis C virus (HCV) infection and identifies interleukin-26 (IL-26) as an antiviral molecule capable of blocking HCV replication. IL-26, which has unique biochemical and structural characteristics, penetrates infected hepatocytes and interacts directly with viral RNA, thereby blocking viral replication. IL-26 is, therefore, a new player in antiviral defenses, operating independently of the immune system. It is of considerable potential interest for treating HCV infection and other chronic disorders caused by RNA viruses for which few treatments are currently available, and for combating emerging RNA viruses.Peer reviewe

The hydrophobic region of the Leishmania peroxin 14 : requirements for association with a glycosome mimetic membrane

This work was funded by operating grants from the Canadian Institutes of Health Research (CIHR) and a Natural Sciences Engineering Research Council of Canada (NSERC) Discovery grant [Fonds de recherche du Québec — Nature et technologies (FRQNT) Regroupement Stratégique grant to the Centre for Host-Parasite Interactions (A.J.)]. N.C. was supported by a doctoral research scholarship from FRQNT. E.B. was supported by a Banting postdoctoral fellowship from CIHR. This work was also supported in part by Wellcome Trust grants [086658 and 093228] to T.K.S. C.S. recognizes the financial support from the Natural Sciences and Engineering Research Council of Canada and a Canada Foundation for Innovation grant [16299].Protein import into the Leishmania glycosome requires docking of the cargo-loaded peroxin 5 (PEX5) receptor to the peroxin 14 (PEX14) bound to the glycosome surface. To examine the LdPEX14-membrane interaction, we purified L. donovani promastigote glycosomes and determined the phospholipid and fatty acid composition. These membranes contained predominately phosphatidylethanolamine, phosphatidylcholine, and phosphatidylglycerol (PG) modified primarily with C18 and C22 unsaturated fatty acid. Using large unilamellar vesicles (LUVs) with a lipid composition mimicking the glycosomal membrane in combination with sucrose density centrifugation and fluorescence-activated cell sorting technique, we established that the LdPEX14 membrane-binding activity was dependent on a predicted transmembrane helix found within residues 149-179. Monolayer experiments showed that the incorporation of PG and phospholipids with unsaturated fatty acids, which increase membrane fluidity and favor a liquid expanded phase, facilitated the penetration of LdPEX14 into biological membranes. Moreover, we demonstrated that the binding of LdPEX5 receptor or LdPEX5-PTS1 receptor-cargo complex was contingent on the presence of LdPEX14 at the surface of LUVs.PostprintPeer reviewe

Prévalence et implication dans la mortalité des complexes QRS de durée anormale et des potentiels tardifs ventriculaires chez le sujet sain et le sujet coronarien

TOULOUSE3-BU Santé-Centrale (315552105) / SudocSudocFranceF

Contribution à la modélisation du transfert des nitrates au travers de la zone non saturée à l'échelle régionale (application au bassin de la Seine)

Les contaminations en nitrates observées depuis les années 1950 dans les hydrosystèmes constituent un enjeu environnemental important. Pour respecter les normes de qualité fixées (Directive Cadre sur l'Eau), une bonne connaissance de leur dynamique est donc nécessaire et passe par un travail de modélisation. Nous nous focalisons ici sur la modélisation des transferts à travers la zone non saturée située entre le sol et la nappe. Ce milieu peut en effet générer des délais importants entre une contamination en surface et un impact sur la qualité des ressources en eau souterraines. Nous avons donc en premier lieu étudié précisément ces transferts via des tests effectués avec un modèle numérique à bases physiques. Nous avons également évalué avec ces tests l'impact du battement de nappe sur ces transferts. Dans le modèle intégré des hydrosystèmes Eau-dyssée, l'approche utilisée pour simuler ces transferts est volontairement simplifiée pour limiter les temps de calcul et le nombre de paramètres requis. Nous proposons alors une évaluation et une amélioration de cette approche. Nous obtenons ainsi une dynamique de transfert des solutés se comparant mieux à ce qui est observé sur le terrain. Une application du modèle à l'échelle régionale, sur le bassin de la Seine, a permis également de mettre en exergue les problèmes posés par l'initialisation des teneurs en nitrates dans le milieu souterrain avant les débuts de l'agriculture intensive. Nous proposons donc une méthode permettant de restituer l'évolution de la médiane des teneurs souterraines en nitrates dans les trois principaux aquifères de ce bassin (Oligocène, Eocène, Craie).PARIS-MINES ParisTech (751062310) / SudocSudocFranceF