Donner corps aux interactions (l'interaction enfin concrétisée)

Depuis plusieurs années, nous utilisons IODA comme méthode de description et de réalisation de simulations multi-agents. Cette méthode a pour originalité de concrétiser les interactions de manière à ce qu'elles soient génériques et réutilisables dans différents contextes. Cet article a pour objectif d'identifier les problèmes durs dans ce type de simulation et de montrer comment IODA apporte une aide à leur résolution. Since several years, we use in our team the IODA methodology to describe and realize multi-agent simulations. This method is original and not similar to the others because it makes Interactions becoming concrete and then able to become sufficiently general to be reused in many contexts. The aim of this paper is to identify some hard problems in this kind of simulation and to show how IODA can be helful to solve them

Groupes sanguins et maladie de marek chez la poule: résistance d'un génotype hétérozygote

International audienc

Feed-back on the development of a small scale Contact Erosion Test in the laboratory (characteristic size ~ 30 cm)

To determine the hydraulic load requested to initiate contact erosion process, tests are performed with an apparatus called the “Contact Erosion Test”. This device originally results from research carried out by Grenoble University, Électricité de France and Compagnie Nationale du Rhône, at the scale of ~60 cm. It has been adapted to a smaller scale in geophyConsult laboratory to conduct tests on samples extracted from core drilling. The instrumentation was improved to enable a better control of the hydraulic loading and avoid biases. The test protocol was modified, especially to better constrain the soil density at the interface. From the first series of test, we drew conclusions on the test repeatability and on the influence of parameters of the soil state. Discrepancies with previous results obtained at the scale of ~60 cm were identified. Therefore, a new erosion test campaign was planned to confirm and determine the reasons for these differences

Development of an ELISA test to assess Salmonella status of pig herds

A total of 70 herds were characterized by serology with an indirect ELISA and bacteriology on environmental swabs. Then they were classified according to a factorial analysis followed by a hierarchical clustering into 3 classes, negative, intermediate and strongly positive. Serological and bacteriological methods were correlated for extreme herds but the results were not so clear for intermediate herds. Nevertheless the correlation between the mean calibrated optical density (mean COD) obtained by serology and the percentage of positive herds obtained by bacteriology was high

Characterization of a new coronavirus strain of poultry infections bronchitis

Un coronavirus a été isolé chez des poules pondeuses présentant des signes cliniques sévères évoquant la bronchite infectieuse aviaire, maladie contre laquelle, elles avaient été immunisées avec un vaccin préparé à partir du sérotype dominant Massachusetts ; ce virus présente des dif férences antigéniques avec les sérotypes Massachusetts et Connecticut ainsi qu’avec les quatre sérotypes « variants » isolés par l’Institut de Doom aux Pays-Bas. La maladie a été reproduite chez le poulet et la poule : les symptômes respiratoires ont été sévères dans les deux cas et la chute de ponte a été intense et persistante chez les pondeuses. Le fait de développer une prophylaxie médicale adaptée est discuté.A coronavirus was isolated in an infectious bronchitis (IB) vaccinated (Massachusetts strain) layers flock showing severe IB-like clinical signs. The isolate is antigenically different from the Massachusetts and the Connecticut serotypes and from the four « variant » serotypes isolated by the Doom Institute in Holland. The disease was reproduced in chickens and layers. Respiratory signs were severe in both groups. In layers, egg drop was intense and long-lasting. The eventual need for a suitable medical prophylaxy is discussed

IBPOWER Project, Intermediate band materials and solar cells for photovoltaics with high efficiency and reduced cost

IBPOWER is a Project awarded under the 7th European Framework Programme that aims to advance research on intermediate band solar cells (IBSCs). These are solar cells conceived to absorb below bandgap energy photons by means of an electronic energy band that is located within the semiconductor bandgap, whilst producing photocurrent with output voltage still limited by the total semiconductor bandgap. IBPOWER employs two basic strategies for implementing the IBSC concept. The first is based on the use of quantum dots, the IB arising from the confined energy levels of the electrons in the dots. Quantum dots have led to devices that demonstrate the physical operation principles of the IB concept and have allowed identification of the problems to be solved to achieve actual high efficiencies. The second approach is based on the creation of bulk intermediate band materials by the insertion of an appropriate impurity into a bulk semiconductor. Under this approach it is expected that, when inserted at high densities, these impurities will find it difficult to capture electrons by producing a breathing mode and will cease behaving as non-radiative recombination centres. Towards this end the following systems are being investigated: a) Mn: In1-xGax N; b) transition metals in GaAs and c) thin films

Up-Regulation of Mcl-1 and Bak by Coronavirus Infection of Human, Avian and Animal Cells Modulates Apoptosis and Viral Replication

Virus-induced apoptosis and viral mechanisms that regulate this cell death program are key issues in understanding virus-host interactions and viral pathogenesis. Like many other human and animal viruses, coronavirus infection of mammalian cells induces apoptosis. In this study, the global gene expression profiles are first determined in IBV-infected Vero cells at 24 hours post-infection by Affymetrix array, using avian coronavirus infectious bronchitis virus (IBV) as a model system. It reveals an up-regulation at the transcriptional level of both pro-apoptotic Bak and pro-survival myeloid cell leukemia-1 (Mcl-1). These results were further confirmed both in vivo and in vitro, in IBV-infected embryonated chicken eggs, chicken fibroblast cells and mammalian cells at transcriptional and translational levels, respectively. Interestingly, the onset of apoptosis occurred earlier in IBV-infected mammalian cells silenced with short interfering RNA targeting Mcl-1 (siMcl-1), and was delayed in cells silenced with siBak. IBV progeny production and release were increased in infected Mcl-1 knockdown cells compared to similarly infected control cells, while the contrary was observed in infected Bak knockdown cells. Furthermore, IBV infection-induced up-regulation of GADD153 regulated the expression of Mcl-1. Inhibition of the mitogen-activated protein/extracellular signal-regulated kinase (MEK/ERK) and phosphoinositide 3-kinase (PI3K/Akt) signaling pathways by chemical inhibitors and knockdown of GADD153 by siRNA demonstrated the involvement of ER-stress response in regulation of IBV-induced Mcl-1 expression. These results illustrate the sophisticated regulatory strategies evolved by a coronavirus to modulate both virus-induced apoptosis and viral replication during its replication cycle

Transcriptional activity of transposable elements in maize

<p>Abstract</p> <p>Background</p> <p>Mobile genetic elements represent a high proportion of the Eukaryote genomes. In maize, 85% of genome is composed by transposable elements of several families. First step in transposable element life cycle is the synthesis of an RNA, but few is known about the regulation of transcription for most of the maize transposable element families. Maize is the plant from which more ESTs have been sequenced (more than two million) and the third species in total only after human and mice. This allowed us to analyze the transcriptional activity of the maize transposable elements based on EST databases.</p> <p>Results</p> <p>We have investigated the transcriptional activity of 56 families of transposable elements in different maize organs based on the systematic search of more than two million expressed sequence tags. At least 1.5% maize ESTs show sequence similarity with transposable elements. According to these data, the patterns of expression of each transposable element family is variable, even within the same class of elements. In general, transcriptional activity of the <it>gypsy</it>-like retrotransposons is higher compared to other classes. Transcriptional activity of several transposable elements is specially high in shoot apical meristem and sperm cells. Sequence comparisons between genomic and transcribed sequences suggest that only a few copies are transcriptionally active.</p> <p>Conclusions</p> <p>The use of powerful high-throughput sequencing methodologies allowed us to elucidate the extent and character of repetitive element transcription in maize cells. The finding that some families of transposable elements have a considerable transcriptional activity in some tissues suggests that, either transposition is more frequent than previously expected, or cells can control transposition at a post-transcriptional level.</p

A Recombinant Avian Infectious Bronchitis Virus Expressing a Heterologous Spike Gene Belonging to the 4/91 Serotype

We have shown previously that replacement of the spike (S) gene of the apathogenic IBV strain Beau-R with that from the pathogenic strain of the same serotype, M41, resulted in an apathogenic virus, BeauR-M41(S), that conferred protection against challenge with M41 [1]. We have constructed a recombinant IBV, BeauR-4/91(S), with the genetic backbone of Beau-R but expressing the spike protein of the pathogenic IBV strain 4/91(UK), which belongs to a different serogroup as Beaudette or M41. Similar to our previous findings with BeauR-M41(S), clinical signs observations showed that the S gene of the pathogenic 4/91 virus did not confer pathogenicity to the rIBV BeauR-4/91(S). Furthermore, protection studies showed there was homologous protection; BeauR-4/91(S) conferred protection against challenge with wild type 4/91 virus as shown by the absence of clinical signs, IBV RNA assessed by qRT-PCR and the fact that no virus was isolated from tracheas removed from birds primarily infected with BeauR-4/91(S) and challenged with IBV 4/91(UK). A degree of heterologous protection against M41 challenge was observed, albeit at a lower level