Ezrin enrichment on curved membranes requires a specific conformation or interaction with a curvature-sensitive partner

One challenge in cell biology is to decipher the biophysical mechanisms governing protein enrichment on curved membranes and the resulting membrane deformation. The ERM protein ezrin is abundant and associated with cellular membranes that are flat, positively or negatively curved. Using in vitro and cell biology approaches, we assess mechanisms of ezrin's enrichment on curved membranes. We evidence that wild-type ezrin (ezrinWT) and its phosphomimetic mutant T567D (ezrinTD) do not deform membranes but self-assemble antiparallelly, zipping adjacent membranes. EzrinTD's specific conformation reduces intermolecular interactions, allows binding to actin filaments, which reduces membrane tethering, and promotes ezrin binding to positively-curved membranes. While neither ezrinTD nor ezrinWT senses negative curvature alone, we demonstrate that interacting with curvature-sensing I-BAR-domain proteins facilitates ezrin enrichment in negatively-curved membrane protrusions. Overall, our work demonstrates that ezrin can tether membranes, or be targeted to curved membranes, depending on conformations and interactions with actin and curvature-sensing binding partners.Peer reviewe

Amélioration des conditions de franchissement à Poutès

International audienc

Développement et mise à jour du modèle de dynamique de population du saumon de l'Allier. Année 2015

M 216

New insights into early MIS 5 lithic technological behavior in the Levant: Nesher Ramla, Israel as a case study.

Interpreting human behavioral patterns during the Middle Paleolithic in the Levant is crucial for better understanding the dispersals and evolution of Homo sapiens and their possible interactions with other hominin groups. Here, we reconstruct the technological behavior, focusing on the centripetal Levallois method at Nesher Ramla karst sinkhole, Israel. Nesher Ramla karst sinkhole is dated to the Marine Isotope stages (MIS) 6 and 5 and represents one of the oldest occurrences of the centripetal Levallois reduction strategy in the Near East. The Levallois centripetal technology is often seen as a marker of human dispersals and adaptations in the Middle Paleolithic/Middle Stone Age of Africa and the Near East. This technology is documented in East African sites as early as 300 kya and in the Levant as early as 130 kya. However, the degree of similarity between African and Levantine centripetal technology and whether it originates from the same source remain under debate. In this paper, we focus on describing the lithic organization at Unit III of Nesher Ramla (dated to MIS 5), which is dominated by the centripetal Levallois method in association with other reduction sequences. Both preferential and recurrent centripetal Levallois modes were used at the site to produce oval and rectangular flakes. Other minor reduction sequences include unidirectional convergent method for Levallois points production and a specific method for the manufacture of naturally backed knives. The lithic data from Unit III of Nesher Ramla is further used in inter-site comparisons suggesting that the mid-Middle Paleolithic sites in the Near East possess common technological characteristics, especially the use of the centripetal Levallois method as predominant reduction strategy. This trend differs from what is usually observed in Africa and Europe, where the centripetal Levallois method is modestly represented during MIS 5 and is accompanied by other, more dominant, reduction strategies

De la recherche à la gestion : transfert d'un modèle de dynamique de population vers un opérateur de la gestion. Cas du saumon de l'Allier

INRA UMR Ecobiop Saint Pée sur Nivelle - Localisation bibliothèque M 213

Expected effects of a dam removal or mitigation on the persistence of the Atlantic salmon population of the Allier river

RésuméInternational audienc

Comprendre les déterminants du non-recours aux programmes d’éducation thérapeutique du patient à partir du modèle de Levesque appliqué à un programme ambulatoire

Introduction : En France, environ la moitié des patients à qui est proposé un programme d’éducation thérapeutique du patient (ETP) le suivent. Objectif : L’objectif de cette étude était de comprendre les déterminants du non-recours à l’ETP à partir du modèle de Levesque. Méthode : Une étude qualitative pilote a été réalisée en 2019 auprès de six familles d’enfants asthmatiques n’ayant pas participé à un programme d’ETP baptisé Ateliers du Souffle malgré la proposition. Une analyse de contenu a été menée à partir d’une grille d’entretien reprenant quatre des dimensions de Levesque : perception des besoins, recherche du recours à l’ETP, atteinte des programmes d’ETP et utilisation des programmes d’ETP. Résultats : Ils montrent un défaut de perception des besoins d’accompagnement lié au patient lui-même mais également au système de santé. La recherche du recours à l’ETP est rendue difficile par une méfiance vis-à-vis du système de santé et un besoin d’autonomie. L’atteinte de l’ETP est limitée par des inégalités sociales et territoriales. Enfin, la non utilisation de l’ETP interroge le degré de motivation du patient et le format d’ETP proposé. Des stratégies pour favoriser le recours à l’ETP sont également exposées. Conclusion: Le modèle de Levesque est un cadre d’analyse adapté à l’étude des déterminants du non-recours à l’ETP et à la définition de stratégies d’amélioration du recours à l’ETP. Informer les patients et leurs proches, former les médecins prescripteurs et rendre l’ETP accessible via des ateliers au plus proche du domicile ou via les outils de communication à distance sont des enjeux actuels de l’ETP

Separating wild versus stocking components in fish recruitment without identification data: a hierarchical modelling approach

Salmonid juvenile stocking programs are often poorly monitored due to the lack of identification between stocked and wild fish. In this study, a hierarchical Bayesian model is developed to take advantage of spatio-temporal variations of stocking and wild recruitment for estimating these two components despite the absence of identification data. It is first tested by means of simulated data, and then applied to the 37 years abundance data set of the Atlantic salmon population of the Allier catchment (France). Despite the absence of identification data, juvenile densities could be estimated and split into wild and stocked components. We found that the stocked juveniles contributed significantly to the total juvenile production, while the wild reproduction continued to provide an important contribution. This approach is encouraging and promising from a management advice perspective. It is flexible enough to accommodate for case study specificities and shows that long term monitoring of abundances can be useful to assess the impact of stocking programs even in the absence of direct means of identifying stocked vs wild fish.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Estimating spatial distribution of Atlantic salmon escapement using redd counts despite changes over time in counting procedure : application to the Allier River population

International audienceIn salmonid species, such as Atlantic salmon (Salmo salar L.), the most frequent type of data set available related to adult escapements are redd counts. When collected over a broad spatio-temporal domain, redd counts data are of great interest for tracking the variation through time of the spatial distribution of the potential spawners. This is important for management purposes when the habitat quality is variable across river sections of a catchment or when the spatial distribution can vary depending on management actions or on environmental factors. However, long-term data sets are prone to changes in data collection methodology. In this article, we present a new hierarchical Bayesian modelling approach that allows both (i) to account for a change in the data collection procedure and (ii) to analyse the variation through time of the potential spawners’ spatial distribution. The value of the proposed approach is demonstrated by its application to the Atlantic salmon redd counts data collected in Allier (France) catchment from 1977 to 2011. The Allier can be divided into three main sections according to management and habitat considerations, and an important change occurred in the redd data collection in 1997: counts by foot or by boat were replaced by counts from a helicopter. A significant effect of this change on methodology is detected: less redds counted when using the helicopter counts. However, its explicit consideration in the modelling makes little difference with regard to the estimates of potential spawner abundance and their associated uncertaint