Rennes – Place Sainte-Anne

La fouille de la station de métro « place Sainte-Anne » à Rennes a été entreprise à partir de la fin du mois de janvier 1998 et s’est achevée au cours du mois de juin. Les sondages d’évaluation réalisés en 1992 avaient permis de diagnostiquer la présence de vestiges antiques et laissaient présager l’existence d’une occupation des lieux à l’époque médiévale. Cette occupation, surtout connue grâce aux études d’archives entreprises, est caractérisée essentiellement par la présence d’un hôpital m..

Rennes – 16-18 rue Saint-Louis

Un projet de réhabilitation et d’extension d’un immeuble ancien, situé au 16-18 rue Saint-Louis dans le périmètre « archéologiquement sensible » de la ville, a été récemment déposé par la société Lamotte-immobilier. Ce projet fait suite à une précédente étude réalisée en 1993 par l’Association Diocésaine. Le programme d’alors ne répondant pas à un certain nombre de contraintes réglementaires, le permis de construire n’a pas été délivré et les lieux sont restés inoccupés. À cette époque, un pr..

Synthèse de la littérature sur les risques de maladies virales inter-espèces en élevage canin en France.

La mortalité pré-sevrage en élevage canin est élevée. Les maladies infectieuses, notamment virales, en sont en grande partie responsable. Ces infections peuvent être transmises aux chiens suite au contact direct ou indirect avec d'autres espèces animales. Après avoir dressé un panorama des différentes maladies virales du chien en France, cette thèse cherche à déterminer les espèces sauvages et domestiques qui peuvent transmettre ces virus aux chiens dans l'élevage. Des mesures prophylactiques médicales et sanitaires, essentielles pour réduire au maximum la probabilité d'infection, sont également évoquées et sont à adapter en fonction des risques contagieux

Cooperation of polarized cell intercalations drives convergence and extension of presomitic mesoderm during zebrafish gastrulation

During vertebrate gastrulation, convergence and extension (C&E) movements narrow and lengthen the embryonic tissues, respectively. In zebrafish, regional differences of C&E movements have been observed; however, the underlying cell behaviors are poorly understood. Using time-lapse analyses and computational modeling, we demonstrate that C&E of the medial presomitic mesoderm is achieved by cooperation of planar and radial cell intercalations. Radial intercalations preferentially separate anterior and posterior neighbors to promote extension. In knypek;trilobite noncanonical Wnt mutants, the frequencies of cell intercalations are altered and the anteroposterior bias of radial intercalations is lost. This provides evidence for noncanonical Wnt signaling polarizing cell movements between different mesodermal cell layers. We further show using fluorescent fusion proteins that during dorsal mesoderm C&E, the noncanonical Wnt component Prickle localizes at the anterior cell edge, whereas Dishevelled is enriched posteriorly. Asymmetrical localization of Prickle and Dishevelled to the opposite cell edges in zebrafish gastrula parallels their distribution in fly, and suggests that noncanonical Wnt signaling defines distinct anterior and posterior cell properties to bias cell intercalations

Polarized cortical tension drives zebrafish epiboly movements

The principles underlying the biomechanics of morphogenesis are largely unknown. Epiboly is an essential embryonic event in which three tissues coordinate to direct the expansion of the blastoderm. How and where forces are generated during epiboly, and how these are globally coupled remains elusive. Here we developed a method, hydrodynamic regression (HR), to infer 3D pressure fields, mechanical power, and cortical surface tension profiles. HR is based on velocity measurements retrieved from 2D+T microscopy and their hydrodynamic modeling. We applied HR to identify biomechanically active structures and changes in cortex local tension during epiboly in zebrafish. Based on our results, we propose a novel physical description for epiboly, where tissue movements are directed by a polarized gradient of cortical tension. We found that this gradient relies on local contractile forces at the cortex, differences in elastic properties between cortex components and the passive transmission of forces within the yolk cell. All in all, our work identifies a novel way to physically regulate concerted cellular movements that might be instrumental for the mechanical control of many morphogenetic processes.Peer ReviewedPostprint (author's final draft

Plasticity of the MAPK signaling network in response to mechanical stress

Cells display versatile responses to mechanical inputs and recent studies have identified the mitogen-activated protein kinase (MAPK) cascades mediating the biological effects observed upon mechanical stimulation. Although, MAPK pathways can act insulated from each other, several mechanisms facilitate the crosstalk between the components of these cascades. Yet, the combinatorial complexity of potential molecular interactions between these elements have prevented the understanding of their concerted functions. To analyze the plasticity of the MAPK signaling network in response to mechanical stress we performed a non-saturating epistatic screen in resting and stretched conditions employing as readout a JNK responsive dJun-FRET biosensor. By knocking down MAPKs, and JNK pathway regulators, singly or in pairs in Drosophila S2R+ cells, we have uncovered unexpected regulatory links between JNK cascade kinases, Rho GTPases, MAPKs and the JNK phosphatase Puc. These relationships have been integrated in a system network model at equilibrium accounting for all experimentally validated interactions. This model allows predicting the global reaction of the network to its modulation in response to mechanical stress. It also highlights its context-dependent sensitivity

Répertoire des céramiques de Rennes aux XVe et XVIe siècles, à partir des découvertes du site hospitalier de la place Sainte-Anne (Ille-et-Vilaine, Bretagne)

Cette présentation fait suite à un premier article publié dans les actes de la table ronde de Caen en 2007, où le lot du dépotoir D2 est évoqué dans son ensemble, montrant de façon succincte les formes et les groupes techniques associés, sans développer la typologie (Labaune, Pouille, 2011). Les lots découverts sur ce site hospitalier par leur volume exceptionnel, constituent des ensembles de premier ordre pour l’étude céramique de la cité médiévale et moderne et sont donc la base de la typo-chronologie présentée ici par type de récipient avec une classification des pâtes, de façon à établir les bases d’un référentiel rennais pour la période : fin xve-première moitié du xvie siècle.This presentation follows upon a first article published in the acts of the round table of Caen in 2007, when the set of the garbage dump D2 is evoked in general, showing in a brief way the forms and the technical groups, without developing the typology. Lots discovered on this hospital site by their exceptional volume, constitute excellent sets for the ceramic study of the medieval and modern city and they are the base of the typo-chronology presented here by type of bowl with a classification of fabrics, so as to establish the bases of Rennes reference table for this period : the end of the 15th century-first half of the 16th century

Differential inhibition onto developing and mature granule cells generates high-frequency filters with variable gain

Adult hippocampal neurogenesis provides the dentate gyrus (DG) with heterogeneous populations of granule cells (GC) originated at different times. The specific contribution of these cells to the encoding of information arriving to the hippocampus is under current investigation. Here we show that spike trains arriving to the DG are channeled into activation of different populations of GC determined by the stimulation frequency and GC age. Immature GC respond to a wider range of afferent stimuli arriving at 1-40 Hz, whereas mature GC are less effective in following higher frequencies. This difference is dictated by the activation of feed forward inhibition, which predominantly restricts mature GC activation. Although it restricts frequency responsiveness, the stronger inhibition of mature GC results in a higher temporal fidelity compared to that of immature GC. Thus, activity arriving to the hippocampus at different frequencies activates two populations of neurons with variable frequency filters: immature cells, with wide range of responses, that are reliable transmitters of the incoming frequency, and mature neurons, with narrow responses to frequency, that are precise at informing the beginning of the stimulus, but with a sparse activity.Fil: Pardi, Belén. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigación En Biomedicina de Buenos Aires; Argentina. Fundación Instituto Leloir; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquimicas de Buenos Aires; ArgentinaFil: Ogando, Mora. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigación En Biomedicina de Buenos Aires; ArgentinaFil: Schinder, Alejandro Fabian. Fundación Instituto Leloir; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquimicas de Buenos Aires; ArgentinaFil: Marin Burgin, Antonia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigación En Biomedicina de Buenos Aires; Argentin

Optimization Space Pruning without Regrets

International audienceMany computationally-intensive algorithms benefit from the wide parallelism offered by Graphical Processing Units (GPUs). However , the search for a close-to-optimal implementation remains extremely tedious due to the specialization and complexity of GPU architectures.We present a novel approach to automatically discover the best performing code from a given set of possible implementations. It involves a branch and bound algorithm with two distinctive features: (1) an analytic performance model of a lower bound on the execution time, and (2) the ability to estimate such bounds on a partially-specified implementation.The unique features of this performance model allow to aggressively prune the optimization space without eliminating the best performing implementation. While the space considered in this paper focuses on GPUs, the approach is generic enough to be applied to other architectures.We implemented our algorithm in a tool called Telamon and demonstrate its effectiveness on a huge, architecture-specific and input-sensitive optimization space. The information provided by the performance model also helps to identify ways to enrich the search space to consider better candidates, or to highlight architectural bottlenecks

Active Tension Network model suggests an exotic mechanical state realized in epithelial tissues.

Mechanical interactions play a crucial role in epithelial morphogenesis, yet understanding the complex mechanisms through which stress and deformation affect cell behavior remains an open problem. Here we formulate and analyze the Active Tension Network (ATN) model, which assumes that the mechanical balance of cells within a tissue is dominated by cortical tension and introduces tension-dependent active remodeling of the cortex. We find that ATNs exhibit unusual mechanical properties. Specifically, an ATN behaves as a fluid at short times, but at long times supports external tension like a solid. Furthermore, an ATN has an extensively degenerate equilibrium mechanical state associated with a discrete conformal - "isogonal" - deformation of cells. The ATN model predicts a constraint on equilibrium cell geometries, which we demonstrate to approximately hold in certain epithelial tissues. We further show that isogonal modes are observed in the fruit y embryo, accounting for the striking variability of apical areas of ventral cells and helping understand the early phase of gastrulation. Living matter realizes new and exotic mechanical states, the study of which helps to understand biological phenomena