Gene network robustness as a multivariate character

Robustness to genetic or environmental disturbances is often considered as a key property of living systems. Yet, in spite of being discussed since the 1950s, how robustness emerges from the complexity of genetic architectures and how it evolves still remains unclear. In particular, whether or not robustness is independent to various sources of perturbations conditions the range of adaptive scenarios that can be considered. For instance, selection for robustness to heritable mutations is likely to be modest and indirect, and its evolution might result from indirect selection on a pleiotropically-related character (e.g., homeostasis). Here, I propose to treat various robustness measurements as quantitative characters, and study theoretically, by individual-based simulations, their propensity to evolve independently. Based on a simple evolutionary model of a gene regulatory network, I showed that different ways to measure the robustness of gene expression to genetic or non-genetic disturbances were substantially correlated. Yet, robustness was mutationally variable in several dimensions, and robustness components could evolve differentially under direct selection pressure. Therefore, the fact that the sensitivity of gene expression to mutations and environmental factors rely on the same gene networks does not preclude distinct evolutionary histories of robustness components.Comment: 27 pages, 5 figures, 8 annexe

LPS-Induced Production of Inflammatory Mediators in the Liver of Postnatal Animals

Lipopolysaccharide (LPS) is the primary component of the outer membrane of Gram-negative bacteria and is responsible for the majority of inflammatory effects of infections from Gram-negative bacteria. To gain better understanding of the effects that postnatal age has on the inflammatory response, pups were randomly assigned to be treated with 250 µg/kg of LPS or saline at postnatal day (P) 1, P21, and P70. Two hours post stimulation, the pups were sacrificed and their livers were harvested for total RN A extraction. Relative mRNA levels of inflammatory genes and �-actin were determined using RT-PCR analysis with appropriate rat sense and antisense primers. The specific inflammatory mediators examined were toll-like receptor-4 (TLR4), cluster of differentiation 14 (CD14), myeloid differentiation factor 88 (Myd88), cytokines including interleukin (IL )-1 �. IL-6, and tumor necrosis factor (TNF)-a, and chemokines including macrophage inflammatory protein (MIP)-1 �, MIP-2, and monocyte chemotactic protein (MCP)-1. We found that the LPS-induced mRNA expression of the cytokines and chemokines examined appear to be increased as compared to the control pups. Furthermore, we showed that an activation of cytokines and chemokines in the liver exhibited age-dependency in pups treated with LPS at Pl, P21, and P70. The pattern shows an increase in relative mRNA expression of cytokines and chemokines as development progresses. Furthermore, we compared the kinetics of cytokine and chemokine induction in PI and P2 l animals. We found that that there was a delayed cytokine and chemokine induction at PI as compared to P2 l pups. Our data suggest that the hepatic innate immunity undergo significant development during early postnatal development, and the delayed inflammatory response in Pl animals may contribute to increased susceptibility of neonatal animals to infections

Getting routers out of the core: Building an optical wide area network with "multipaths"

We propose an all-optical networking solution for a wide area network (WAN) based on the notion of multipoint-to-multipoint lightpaths that, for short, we call "multipaths". A multipath concentrates the traffic of a group of source nodes on a wavelength channel using an adapted MAC protocol and multicasts this traffic to a group of destination nodes that extract their own data from the confluent stream. The proposed network can be built using existing components and appears less complex and more efficient in terms of energy consumption than alternatives like OPS and OBS. The paper presents the multipath architecture and compares its energy consumption to that of a classical router-based ISP network. A flow-aware dynamic bandwidth allocation algorithm is proposed and shown to have excellent performance in terms of throughput and delay

The Vpr protein from HIV-1: distinct roles along the viral life cycle

The genomes of human and simian immunodeficiency viruses (HIV and SIV) encode the gag, pol and env genes and contain at least six supplementary open reading frames termed tat, rev, nef, vif, vpr, vpx and vpu. While the tat and rev genes encode regulatory proteins absolutely required for virus replication, nef, vif, vpr, vpx and vpu encode for small proteins referred to "auxiliary" (or "accessory"), since their expression is usually dispensable for virus growth in many in vitro systems. However, these auxiliary proteins are essential for viral replication and pathogenesis in vivo. The two vpr- and vpx-related genes are found only in members of the HIV-2/SIVsm/SIVmac group, whereas primate lentiviruses from other lineages (HIV-1, SIVcpz, SIVagm, SIVmnd and SIVsyk) contain a single vpr gene. In this review, we will mainly focus on vpr from HIV-1 and discuss the most recent developments in our understanding of Vpr functions and its role during the virus replication cycle

Communes de Thouarcé et Vauchrétien

La prospection-inventaire entreprise entre 1997 et 1998 dans les communes de Thouarcé et Vauchrétien a contribué à l’enregistrement de 55 indices de sites ou sites nouveaux. Traversé par la rivière du Layon, Thouarcé offre une géographie variée avec une zone de plaine au sud-ouest du bourg et une zone de coteaux en vignoble exposée nord-sud. Cette dernière paraissait propice à une implantation humaine dès la Préhistoire ce que la prospection pédestre a confirmé avec la découverte de 13 indice..

Estimation of Genetic Effects and Genotype-Phenotype Maps

Determining the genetic architecture of complex traits is a necessary step to understand phenotypic changes in natural, experimental and domestic populations. However, this is still a major challenge for modern genetics, since the estimation of genetic effects tends to be complicated by genetic interactions, which lead to changes in the effect of allelic substitutions depending on the genetic background. Recent progress in statistical tools aiming to describe and quantify genetic effects meaningfully improves the efficiency and the availability of genotype-to-phenotype mapping methods. In this contribution, we facilitate the practical use of the recently published ‘NOIA’ quantitative framework by providing an implementation of linear and multilinear regressions, change of reference operation and genotype-to-phenotype mapping in a package (‘noia’) for the software R, and we discuss theoretical and practical benefits evolutionary and quantitative geneticists may find in using proper modeling strategies to quantify the effects of genes

The Use of Triboemission Imaging and Charge Measurements to Study DLC Coating Failure

We present a study on the simultaneous evolution of the electron emission and surface charge accumulation that occurs during scratching tests in order to monitor coating failure. Steel discs coated with a diamond-like-carbon (DLC) film were scratched in both vacuum (~10−5 Torr) and atmospheric conditions, with electron emission and surface charge being measured by a system of microchannel plates and an electrometer, respectively. The results highlight a positive correlation between emission intensity values, surface charge measurements and surface damage topography, suggesting the effective use of these techniques to monitor coating wear in real time

Le droit à l'instruction dans la jurisprudence de la Cour européenne des droits de l'Homme

The Protection of the right to education has been the subject of endness debates troughout thepreparatory work on the European Convention of Human Rights. While the idea of a right to educationfor all was quite evident in the mind of the drafters of the European Convention of Human Rights, therespect for religious and philosophical convictions of parents, who come first in the education of theirchildren, has been more controversial. Theses doubts explain the inscription of this right in Article 2 ofthe Protocol to the Convention on 20 March 1952. Its importance mustn’t be overlooked. Described asa « matrix right », the right to education contributes to a concrete and effective guarantee of the rightsand freedoms protected by the European Convention of Human Rights. It ensures personal blossomingand the right to make up their own minds. Therefore, everybody can claim this right, whether it be apupil or a student, regardless of the institution (public or private school, primary school or furthereducation). Aware of this key issue to protect a democratic society, the European Court of HumanRights has interpreted article 2 of the Protocol in order to reach a fair balance between the nationalmargin of appreciation and the protection of the right to education. That’s the reason why the Courtrequires States to achieve some positive obligations especially to enable everyone to use existingeducation means. Through the guarantee to an equal access of everyone to education institutions, theEuropean Court of Human Rights also encourages national authorities to observe the distinctivefeatures of each individual. In order to do so, the authorities must remain neutral both in educationalinstitutions and their curriculum. No pupil or student must feel excluded or chastised because of hispersonal convictions. Then, securing the universal right to education implies securing the right to apluralistic education.La protection du droit à l’instruction a fait l’objet de longues discussions lors des travaux préparatoiresà la Convention européenne des droits de l’Homme. Si l’idée d’un droit à l’instruction pour tous s’esttrès vite imposée dans l’esprit de ses rédacteurs, le respect des convictions religieuses etphilosophiques des parents, qui assurent en priorité l’éducation et l’enseignement de leurs enfants, afait l’objet de davantage de controverses. Ces hésitations expliquent la présence de ce droit à l’article 2du premier protocole additionnel à la Convention du 20 mars 1952. Son importance n’est cependantpas à négliger. Qualifié de droit matriciel, le droit à l’instruction participe à la garantie concrète eteffective des autres droits et libertés de la pensée protégés par le corpus européen. Il assure en celal’épanouissement de la personne et lui garantit le droit de se déterminer librement. Il peut donc êtrerevendiqué par tous, élève ou étudiant, et peu importe la structure fréquentée (établissement public,privé, scolaire ou supérieur). Consciente de cet enjeu décisif pour la sauvegarde d’une sociétédémocratique, la Cour européenne des droits de l’Homme a su interpréter l’article 2 du Protocoleadditionnel de manière à assurer un juste équilibre entre la marge nationale d’appréciation et lapromotion du droit à l’instruction. Pour cela, elle a mis à la charge des Etats des obligations positivesafin d’assurer à chacun la possibilité, notamment, de se servir des moyens d’instruction existants. Engarantissant ainsi l’égal accès de tous aux structures existantes, la Cour européenne des droits del’Homme a également incité les autorités étatiques à respecter les particularités de chacun. A cette fin,une obligation de neutralité leur est imposée aussi bien dans les établissements d’enseignement quedans les programmes dispensés. Aucun élève ni étudiant ne doit se sentir exclu ou stigmatisé en raisonde ses convictions propres. La garantie d’un droit universel à l’instruction implique alors la garantied’un droit à une instruction pluraliste

Harvest-induced disruptive selection increases variance in fitness-related traits

The form of Darwinian selection has important ecological and management implications. Negative effects of harvesting are often ascribed to size truncation (i.e. strictly directional selection against large individuals) and resultant decrease in trait variability, which depresses capacity to buffer environmental change, hinders evolutionary rebound and ultimately impairs population recovery. However, the exact form of harvest-induced selection is generally unknown and the effects of harvest on trait variability remain unexplored. Here we use unique data from the Windermere (UK) long-term ecological experiment to show in a top predator (pike, Esox lucius) that the fishery does not induce size truncation but disruptive (diversifying) selection, and does not decrease but rather increases variability in pike somatic growth rate and size at age. This result is supported by complementary modelling approaches removing the effects of catch selectivity, selection prior to the catch and environmental variation. Therefore, fishing most likely increased genetic variability for somatic growth in pike and presumably favoured an observed rapid evolutionary rebound after fishery relaxation. Inference about the mechanisms through which harvesting negatively affects population numbers and recovery should systematically be based on a measure of the exact form of selection. From a management perspective, disruptive harvesting necessitates combining a preservation of large individuals with moderate exploitation rates, and thus provides a comprehensive tool for sustainable exploitation of natural resources