Differential Selection on Carotenoid Biosynthesis Genes as a Function of Gene Position in the Metabolic Pathway: A Study on the Carrot and Dicots

Background: Selection of genes involved in metabolic pathways could target them differently depending on the position of genes in the pathway and on their role in controlling metabolic fluxes. This hypothesis was tested in the carotenoid biosynthesis pathway using population genetics and phylogenetics. Methodology/Principal Findings: Evolutionary rates of seven genes distributed along the carotenoid biosynthesis pathway

Réalisation de l'outil cartographique des habitats potentiels sur l'estuaire de la Gironde : rapport

[Departement_IRSTEA]Eaux [TR1_IRSTEA]QUASARELes biens et services rendus par les estuaires à la société classent ces écosystèmes parmi les plus productifs de la planète. En particulier, la productivité et la richesse biologique de ces milieux sont liées à la capacité de leur mosaïque d’habitats à assurer des fonctions essentielles aux cycles biologiques des espèces qui les fréquentent. Comme dans les autres grands estuaires, la compréhension et la caractérisation des enjeux environnementaux dans l’estuaire de la Gironde passent par une meilleure connaissance du rôle écologique des habitats estuariens. En 2006, le GIP Loire Estuaire (GIPLE) a initié une démarche qui a abouti à l’élaboration d’un SIG dit ‘SIG Habitat Fonctionnels’ (SIG-HF) destiné à cartographier les fonctionnalités écologiques majeures associées à la mosaïque d’habitats de la partie aval de l’estuaire de la Loire. Le SIG-HF est un outil novateur d’évaluation spatialisée des fonctionnalités environnementales de l’estuaire qui permet de dépasser les aspects purement patrimoniaux pour appréhender l’écosystème d’un point de vue fonctionnel. Il consiste à cartographier les fonctionnalités écologiques associées aux habitats de l’estuaire. Il repose sur la capacité à modéliser et cartographier la distribution des principales espèces faunistiques dans le milieu et à caractériser leur utilisation des habitats i.e. les fonctions écologiques associées (ex. nourricerie, alimentation, reproduction, corridor migratoire pour les poissons, halte migratoire, hivernage pour les oiseaux…)

Rosa spp.

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Outils chimiques, bio-informatiques et bases de données en écologie chimique

International audienceCe chapitre présente quelques techniques utilisées en Écologie chimique. Depuis quelques années, des équipements de plus en plus performants permettent en effet d’obtenir des analyses profondes de métabolites secondaires et d’acides nucléiques. Ces approches vont souvent de pair avec la production de masses de données énormes rendant indispensable la comparaison automatique avec des bases de données en ligne. Des innovations techniques majeures, basées sur ces performances d’analyse chimique, ont aussi vu le jour en imagerie. Il est ainsi de plus en plus fréquent d’imager une molécule donnée avec une résolution approchant l’ordre du µm. Ce chapitre présente ces aspects ainsi que quelques axes possibles d’innovation

Vers l'évaluation des conséquences écologiques des évolutions hydromorphologiques de l'estuaire de la Gironde : Une approche préliminaire combinant SIG et modélisation hydrodynamique

International audienceEstuaries are composed of a mosaic of habitat providing various ecological functions for many biological communities and many goods and services to society. At the interface between continents and oceans, estuaries in general, and particularly large estuaries, are also environments which concentrate important ecological issues but also many environmental climatic and anthropogenic pressures. The Gironde estuary, one of the largest European estuaries, is thus an emblematic case. Historically, it has undergone major evolutions of its hydromorphosedimentary characteristics due to impacts of climate change and human activities. The aim of this work is to assess the ecological consequences of these changes through the study of the evolution of surfaces of estuarine available habitats and the knowledge of ecological functions associated with these habitats. To do this, we propose to combine two approaches: ecological and hydromorphosedimentary. First, work was undertaken to determine, from scientific literature, tolerances and preferences of representative species of the ecosystem for each of the parameters determining estuarine aquatic habitats (depth, salinity, sedimentary facies ...). Thus, combining available map data and results from a hydrodynamic model implemented in the Gironde, we can map the spatial distribution of these species in the estuary using a geographic information system (GIS). Then, we characterized the ecological functions associated with each habitat (eg. nursery role for sole, migration for eels ...). On the other hand, old maps of the environment have been digitized and analysis was undertaken to characterize the evolution of morphology, hydrological and sedimentary dynamics of the estuary in recent decades. The potential distribution maps we obtained allowed defining a kind of ecological potential that can be used as a reference for assessing effects of development issues, management measures or climate change scenarios. Results highlighted small changes in functional habitats distributions but high vulnerability of some of them (nursery grounds)

Effects of Lightly Doped Drain and Channel Doping Variations on Flash Memory Performances and Reliability

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Impact of transposable elements on the organization and function of allopolyploid genomes

Transposable elements (TEs) represent an important fraction of plant genomes and are likely to play a pivotal role in fuelling genome reorganization and functional changes following allopolyploidization. Various processes associated with allopolyploidy (i.e. genetic redundancy, bottlenecks during the formation of allopolyploids or genome shock following genome merging) may allow accumulation of TE insertions. Our objective in carrying out a survey of the literature and a comparative analysis across different allopolyploid systems is to shed light on the structural, epigenetic and functional modifications driven by TEs during allopolyploidization and subsequent diploidization. The available evidence indicates that TE proliferation in the short or the long term after allopolyploidization may be restricted to a few TEs, in specific polyploid systems. By contrast, data indicate major structural changes in the TE genome fraction immediately after allopolyploidization, mainly through losses of TE sequences as a result of recombination. Emerging evidence also suggests that TEs are targeted by substantial epigenetic changes, which may impact gene expression and genome stability. Furthermore, TEs may directly or indirectly support the evolution of new functionalities in allopolyploids during diploidization. All data stress allopolyploidization as a shock associated with drastic genome reorganization. Mechanisms controlling TEs during allopolyploidization as well as their impact on diploidization are discussed

The molecular signatures of compatible and incompatible pollination in Arabidopsis.

BACKGROUND: Fertilization in flowering plants depends on the early contact and acceptance of pollen grains by the receptive papilla cells of the stigma. Deciphering the specific transcriptomic response of both pollen and stigmatic cells during their interaction constitutes an important challenge to better our understanding of this cell recognition event. RESULTS: Here we describe a transcriptomic analysis based on single nucleotide polymorphisms (SNPs) present in two Arabidopsis thaliana accessions, one used as female and the other as male. This strategy allowed us to distinguish 80% of transcripts according to their parental origins. We also developed a tool which predicts male/female specific expression for genes without SNP. We report an unanticipated transcriptional activity triggered in stigma upon incompatible pollination and show that following compatible interaction, components of the pattern-triggered immunity (PTI) pathway are induced on the female side. CONCLUSIONS: Our work unveils the molecular signatures of compatible and incompatible pollinations both at the male and female side. We provide invaluable resource and tools to identify potential new molecular players involved in pollen-stigma interaction