Infeção Perinatal por Streptococus do Grupo B: Prevenção

Instructional software is more en more used in education. This drives pedagogy and computer science toward research on its own design. We submit in this paper a design method which is on the one hand based on the original properties of numeric information, and on the other hand on the pedagogical management of this information. Our method is founded on a model of information’s representation (the Logical Units) along with a design approach that actually allows the representation of the information according to the model. We finally describe an experiment we completed, in order to apply and evaluate ourL’usage des supports hypermédia dans la formation est aujourd’hui en pleine expansion. Cette expansion invite les pédagogues et les informaticiens à réfléchir sur la conception de tels supports. Nous proposons, au travers de cet article une méthode de conception fondée d’une part sur les propriétés originales du support et d’autre part sur l’exploitation de ce support dans un cadre de formation. Notre approche est basée sur un modèle de représentation de l’information (les Unités Logiques) et sur une logique de conception permettant effectivement de représenter l’information sous une telle forme. Nous présentons également une expérience qui nous a permis de mettre en oeuvre et de commencer à évaluer nos travauxCrozat Stéphane, Trigano Philippe. Une démarche de conception des supports hypermédias orientée vers leur exploitation pédagogique : modèle et expérience . In: Spirale. Revue de recherches en éducation, n°28, 2001. Nouveaux outils, nouvelles écritures, nouvelles lectures, sous la direction de Annette Beguin. pp. 83-104

Commitment to the Regulatory T Cell Lineage Requires CARMA1 in the Thymus but Not in the Periphery

Regulatory T (Treg) cells expressing forkhead box P3 (Foxp3) arise during thymic selection among thymocytes with modestly self-reactive T cell receptors. In vitro studies suggest Foxp3 can also be induced among peripheral CD4+ T cells in a cytokine dependent manner. Treg cells of thymic or peripheral origin may serve different functions in vivo, but both populations are phenotypically indistinguishable in wild-type mice. Here we show that mice with a Carma1 point mutation lack thymic CD4+Foxp3+ Treg cells and demonstrate a cell-intrinsic requirement for CARMA1 in thymic Foxp3 induction. However, peripheral Carma1-deficient Treg cells could be generated and expanded in vitro in response to the cytokines transforming growth factor beta (TGFβ) and interleukin-2 (IL-2). In vivo, a small peripheral Treg pool existed that was enriched at mucosal sites and could expand systemically after infection with mouse cytomegalovirus (MCMV). Our data provide genetic evidence for two distinct mechanisms controlling regulatory T cell lineage commitment. Furthermore, we show that peripheral Treg cells are a dynamic population that may expand to limit immunopathology or promote chronic infection

Post-replicative pairing of sister ter regions in Escherichia coli involves multiple activities of MatP

Funder: Université Toulouse III - Paul Sabatier (University of Toulouse III Paul Sabatier); doi: https://doi.org/10.13039/501100009160Abstract: The ter region of the bacterial chromosome, where replication terminates, is the last to be segregated before cell division in Escherichia coli. Delayed segregation is controlled by the MatP protein, which binds to specific sites (matS) within ter, and interacts with other proteins such as ZapB. Here, we investigate the role of MatP by combining short-time mobility analyses of the ter locus with biochemical approaches. We find that ter mobility is similar to that of a non ter locus, except when sister ter loci are paired after replication. This effect depends on MatP, the persistence of catenanes, and ZapB. We characterise MatP/DNA complexes and conclude that MatP binds DNA as a tetramer, but bridging matS sites in a DNA-rich environment remains infrequent. We propose that tetramerisation of MatP links matS sites with ZapB and/or with non-specific DNA to promote optimal pairing of sister ter regions until cell division

Co-evolution of segregation guide DNA motifs and the FtsK translocase in bacteria: identification of the atypical Lactococcus lactis KOPS motif

Bacteria use the global bipolarization of their chromosomes into replichores to control the dynamics and segregation of their genome during the cell cycle. This involves the control of protein activities by recognition of specific short DNA motifs whose orientation along the chromosome is highly skewed. The KOPS motifs act in chromosome segregation by orienting the activity of the FtsK DNA translocase towards the terminal replichore junction. KOPS motifs have been identified in γ-Proteobacteria and in Bacillus subtilis as closely related G-rich octamers. We have identified the KOPS motif of Lactococcus lactis, a model bacteria of the Streptococcaceae family harbouring a compact and low GC% genome. This motif, 5′-GAAGAAG-3, was predicted in silico using the occurrence and skew characteristics of known KOPS motifs. We show that it is specifically recognized by L. lactis FtsK in vitro and controls its activity in vivo. L. lactis KOPS is thus an A-rich heptamer motif. Our results show that KOPS-controlled chromosome segregation is conserved in Streptococcaceae but that KOPS may show important variation in sequence and length between bacterial families. This suggests that FtsK adapts to its host genome by selecting motifs with convenient occurrence frequencies and orientation skews to orient its activity

Fitness Landscape Transformation through a Single Amino Acid Change in the Rho Terminator

Regulatory networks allow organisms to match adaptive behavior to the complex and dynamic contingencies of their native habitats. Upon a sudden transition to a novel environment, the mismatch between the native behavior and the new niche provides selective pressure for adaptive evolution through mutations in elements that control gene expression. In the case of core components of cellular regulation and metabolism, with broad control over diverse biological processes, such mutations may have substantial pleiotropic consequences. Through extensive phenotypic analyses, we have characterized the systems-level consequences of one such mutation (rho*) in the global transcriptional terminator Rho of Escherichia coli. We find that a single amino acid change in Rho results in a massive change in the fitness landscape of the cell, with widely discrepant fitness consequences of identical single locus perturbations in rho* versus rhoWT backgrounds. Our observations reveal the extent to which a single regulatory mutation can transform the entire fitness landscape of the cell, causing a massive change in the interpretation of individual mutations and altering the evolutionary trajectories which may be accessible to a bacterial population

The plant apoplasm is an important recipient compartment for nematode secreted proteins

Similarly to microbial pathogens, plant-parasitic nematodes secrete into their host plants proteins that are essential to establish a functional interaction. Identifying the destination of nematode secreted proteins within plant cell compartment(s) will provide compelling clues on their molecular functions. Here the fine localization of five nematode secreted proteins was analysed throughout parasitism in Arabidopsis thaliana. An immunocytochemical method was developed that preserves both the host and the pathogen tissues, allowing the localization of nematode secreted proteins within both organisms. One secreted protein from the amphids and three secreted proteins from the subventral oesophageal glands involved in protein degradation and cell wall modification were secreted in the apoplasm during intercellular migration and to a lower extent by early sedentary stages during giant cell formation. Conversely, another protein produced by both subventral and dorsal oesophageal glands in parasitic stages accumulated profusely at the cell wall of young and mature giant cells. In addition, secretion of cell wall-modifying proteins by the vulva of adult females suggested a role in egg laying. The study shows that the plant apoplasm acts as an important destination compartment for proteins secreted during migration and during sedentary stages of the nematode

Structuration et scénarisation de documents pédagogiques numériques dans une logique de massification

In one hand digital documents are more en more used and in the other hand new needs are emerging in the field of institutional education and professional training. The consequence is a skyrocketing development of instructional digital documents. In this paper we submit an industrial design model that aims to conciliate a generic documentary meta-model along with specific pedagogical models, in a mass-production context. Our research is based on a theoretical approach from the state of the art study (content/form separation, content ! scenario separation and content ! actions association) and on a empirical approach from practical experiments (XF01 and SCENARI). The result of our work is PS/LU metamodel which enables a methodological and a technological framework in order to : logically represent multimedia and pedagogical information (as Logical-Units), deal information towards pedagogical scripts (as Pedagogical-Schemas) and present information so that it can be manipulated (as Interaction-Sheets).La croissance spectaculaire du numérique (internet en tête), combinée aux besoins nouveaux dans le domaine de la formation (professionnelle notamment ) ont conduit à un développement considérable de la production de documents pédagogiques numériques. Notre travail s’inscrit au sein de cette problématique, afin d’élaborer un modèle de conception industrielle qui permette l'application d’un modèle documentaire générique, et l'intégration de modèles pédagogiques spécifiques, dans une perspective de massification. Ce modèle a été conçu à partir d’une approche théorique depuis l’état de l’art (séparation fond/forme, séparation contenu/scénarisation et association information/actions) et une approche empirique depuis nos expérimentations (XF01 et SCENARl). Le résultat de ce travail est le métamodèle SP/UL qui propose une approche méthodologique et technologique afin de représenter logiquement l’information multimédia pédagogique (sous forme d’unités logiques), de distribuer l’information au sein de scénarii pédagogiques (sous forme de schémas pédagogiques), et de présenter l’information pour la manipuler (sous forme de feuilles de comportement).Crozat Stéphane, Trigano Philippe. Structuration et scénarisation de documents pédagogiques numériques dans une logique de massification. In: Sciences et techniques éducatives, volume 9 n°3-4, 2002. pp. 371-408

Identification of Mouse Cytomegalovirus Resistance Loci by ENU Mutagenesis

Host resistance to infection depends on the efficiency with which innate immune responses keep the infectious agent in check. Innate immunity encompasses components with sensing, signaling and effector properties. These elements with nonredundant functions are encoded by a set of host genes, the resistome. Here, we review our findings concerning the resistome. We have screened randomly mutagenized mice for susceptibility to a natural opportunistic pathogen, the mouse cytomegalovirus. We found that some genes with initially no obvious functions in innate immunity may be critical for host survival to infections, falling into a newly defined category of genes of the resistome

Identification of Mouse Cytomegalovirus Resistance Loci by ENU Mutagenesis

Host resistance to infection depends on the efficiency with which innate immune responses keep the infectious agent in check. Innate immunity encompasses components with sensing, signaling and effector properties. These elements with nonredundant functions are encoded by a set of host genes, the resistome. Here, we review our findings concerning the resistome. We have screened randomly mutagenized mice for susceptibility to a natural opportunistic pathogen, the mouse cytomegalovirus. We found that some genes with initially no obvious functions in innate immunity may be critical for host survival to infections, falling into a newly defined category of genes of the resistome