Plantes médicinales et populations autochtones en Guyane : perception chamanique, législation et gouvernance de la biodiversité

Les plantes médicinales sont perçues de manière très contrastée selon les différents protagonistes et usagers de la nature : pour les autochtones de Guyane elles font sens dans une approche spirituelle de la Nature, tandis que pour de nombreux autres acteurs, notamment dans le domaine pharmaceutique, elles sont perçues comme des usines à molécules bioactives, ou encore à travers leur potentiel économique. Après une description de ces différentes approches, et la manière dont elles se traduisent (ou pas) dans les textes élaborés pour protéger la biodiversité et les ressources génétiques (la CDB, le protocole de Nagoya, le dispositif d’Accès et de Partage des Avantages [APA]), leur mise en place en Guyane, le projet de loi sur la biodiversité, nous évoquerons le piège que représentent ces questions juridiques internationales pour les peuples autochtones mais aussi les dynamiques nouvelles qu’elles engendrent en termes de gouvernance pour l’ensemble des acteurs impliqués dans l’accès et le partage des avantages.Healing plants are perceived in very different ways according to various users of nature: for the Natives of French Guiana, they make sense in a spiritual approach of Nature, whereas for the other numerous actors, they are perceived as factories of bioactive molecules, or through their economic potential. After a description of these various approaches, and the way they are translated (or not) in texts developed to protect biological diversity and genetic resources (CDB, Nagoya protocol, protocols of access to the resources and sharing of the advantages) applied in Guiana’s Region, French law’s project on biodiversity, we discuss the trap posed by these legal questions for indigenous peoples, but also the new dynamics they generate in terms of governance for all stakeholders involved in Acces and Benefit Sharing (ABS)

Arcueil – Bassin de Rétention

Faisant suite à un diagnostic effectué en 1997, une opération s’est déroulée du 16 février au 27 mars sur le chantier de construction du bassin de retenue réalisé au lieu-dit le Moulin de la Roche par les services de l’eau et de l’assainissement du Conseil général du Val-de-Marne (DSEA). Les mouvements de terre n’ont eu lieu qu’à l’intérieur du bassin circulaire délimité par une paroi moulée (diamètre : 40 m ; profondeur : 15 m, dont 7 m jusqu’au substrat tertiaire) et pour la réalisation du ..

Développement et validation d'une métasurface acoustique orientable large bande composée de résonateurs électroacoustiques actifs

Nous proposons un concept de métasurface acoustique orientables en réflexion, effective sur une large bande de fréquences, à l’aide de cellules actives. La métasurface est composée d’un réseau de haut-parleurs petits devant la longueur d’onde, dont l’impédance acoustique peut être programmée par contrôle actif afin d’ajuster la phase du coefficient de réflexion en tout point de la métasurface. La stratégie de contrôle s’inspire des Résonateurs Electroacoustiques Actifs, utilisant un asservissement en courant du transducteur basé sur une captation microphonique devant sa membrane, permettant d’obtenir une large gamme d’impédances acoustiques sur un même haut-parleur. Ce papier présente la méthodologie de dimensionnement des Résonateurs Electroacoustiques permettant d’obtenir un angle de réflexion prédéfini pour une incidence donnée, et des validations numériques et expérimentales permettent de vérifier les performances du concept. L’aspect large-bande du contrôle sera en particulier discuté

Toward Wideband Steerable Acoustic Metasurfaces with Arrays of Active Electroacoustic Resonators

We introduce an active concept for achieving acoustic metasurfaces with steerable reflection properties, effective over a wide frequency band. The proposed active acoustic metasurface consists in a surface array of subwavelength loudspeakers diaphragms, each with programmable individual active acoustic impedances allowing for local control over the different reflection phases over the metasurface. The active control framework used for controlling the reflection phase over the metasurface is derived from the Active Electroacoustic Resonator concept. Each unit-cell simply consists of a current-driven electrodynamic loudspeaker in a closed box, whose acoustic impedance at the diaphragm is judiciously adjusted by connecting an active electrical control circuit. The control is known to achieve a wide variety of acoustic impedances on a single loudspeaker diaphragm used as an acoustic resonator, with the possibility to shift its resonance frequency by more than one octave. The paper presents a methodology for designing such active metasurface elements. An experimental validation of the achieved individual reflection coefficients is presented, and full wave simulations present a few examples of achievable reflection properties, with a focus on the bandwidth of operation of the proposed control concept

New insights on the mechanism of quinoline-based DNA methyltransferase inhibitors

Among the epigenetic marks, DNA methylation is one of the most studied. It is highly deregulated in numerous diseases, including cancer. Indeed, it has been shown that hypermethylation of tumor suppressor genes promoters is a common feature of cancer cells. Because DNA methylation is reversible, the DNA methyltransferases (DNMTs), responsible for this epigenetic mark, are considered promising therapeutic targets. Several molecules have been identified as DNMT inhibitors and, among the non-nucleoside inhibitors, 4-aminoquinoline-based inhibitors, such as SGI-1027 and its analogs, showed potent inhibitory activity. Here we characterized the in vitro mechanism of action of SGI-1027 and two analogs. Enzymatic competition studies with the DNA substrate and the methyl donor cofactor, S-adenosyl-L-methionine (AdoMet), displayed AdoMet non-competitive and DNA competitive behavior. In addition, deviations from the Michaelis-Menten model in DNA competition experiments suggested an interaction with DNA. Thus their ability to interact with DNA was established; although SGI-1027 was a weak DNA ligand, analog 5, the most potent inhibitor, strongly interacted with DNA. Finally, as 5 interacted with DNMT only when the DNA duplex was present, we hypothesize that this class of chemical compounds inhibit DNMTs by interacting with the DNA substrate

Molecular characterization of genetic diversity within the Africa/Middle East/Asia Minor and Sub-Saharan African groups of the Bemisia tabaci species complex

International audienceBemisia tabaci Gennadius is a major plant pest in many agricultural systems worldwide. It is a complex of cryptic species that differ in many ecological respects, including damage-causing potential. Monitoring the genetic composition of B. tabaci populations in the field is, therefore, essential for achieving effective control. Sequencing is costly and time consuming; thus, efficient diagnostic tools must be developed to perform epidemiological studies involving hundreds of individuals. Here, we describe a polymerase chain reaction (PCR) restriction fragment length polymorphism (RFLP) method for identifying all the putative species comprising the Africa/Middle East/Asia Minor group, including those that are the most devastating crop pests. Moreover, intra-specific diversity associated with specific symbiotic bacteria known to manipulate insect host phenotypes can also be detected. In addition, this method discriminates between the Africa/Middle East/Asia Minor and the Sub-Saharan African groups, which are sympatric in some areas. This simple, reliable and cost-effective diagnostic tool is ideal for the rapid analysis of a high number of individuals and, thus, has potential applications in field contexts, where it could provide valuable baseline information for pest management programs

AMMA information system: an efficient cross-disciplinary tool and a legacy for forthcoming projects

International audienceIn the framework of the African Monsoon Multidisciplinary Analyses (AMMA) programme, several tools have been developed in order to facilitate and speed up data and information exchange between researchers from different disciplines. The AMMA information system includes a multidisciplinary user-friendly distributed data management and distribution system, a reports and quick looks archive associated with a display website and scientific papers exchange systems. All the applications have been developed by several French institutions and fully duplicated in Niamey, Niger

Evidence of diversity and recombination in Arsenophonus symbionts of the Bemisia tabaci species complex

<p>Abstract</p> <p>Background</p> <p>Maternally inherited bacterial symbionts infecting arthropods have major implications on host ecology and evolution. Among them, the genus <it>Arsenophonus</it> is particularly characterized by a large host spectrum and a wide range of symbiotic relationships (from mutualism to parasitism), making it a good model to study the evolution of host-symbiont associations. However, few data are available on the diversity and distribution of <it>Arsenophonus</it> within host lineages. Here, we propose a survey on <it>Arsenophonus</it> diversity in whitefly species (Hemiptera), in particular the <it>Bemisia tabaci</it> species complex. This polyphagous insect pest is composed of genetic groups that differ in many ecological aspects. They harbor specific bacterial communities, among them several lineages of <it>Arsenophonus</it>, enabling a study of the evolutionary history of these bacteria at a fine host taxonomic level, in association to host geographical range and ecology.</p> <p>Results</p> <p>Among 152 individuals, our analysis identified 19 allelic profiles and 6 phylogenetic groups, demonstrating this bacterium's high diversity. These groups, based on <it>Arsenophonus</it> phylogeny, correlated with <it>B. tabaci</it> genetic groups with two exceptions reflecting horizontal transfers<it>.</it> None of three genes analyzed provided evidence of intragenic recombination, but intergenic recombination events were detected. A mutation inducing a STOP codon on one gene in a strain infecting one <it>B. tabaci</it> genetic group was also found. Phylogenetic analyses of the three concatenated loci revealed the existence of two clades of <it>Arsenophonus.</it> One, composed of strains found in other Hemiptera, could be the ancestral clade in whiteflies. The other, which regroups strains found in Hymenoptera and Diptera, may have been acquired more recently by whiteflies through lateral transfers.</p> <p>Conclusions</p> <p>This analysis of the genus <it>Arsenophonus</it> revealed a diversity within the <it>B. tabaci</it> species complex which resembles that reported on the larger scale of insect taxonomy. We also provide evidence for recombination events within the <it>Arsenophonus</it> genome and horizontal transmission of strains among insect taxa. This work provides further insight into the evolution of the <it>Arsenophonus</it> genome, the infection dynamics of this bacterium and its influence on its insect host's ecology.</p

Functional role of ɛ-tubulin in the assembly of the centriolar microtubule scaffold

Centrioles and basal bodies fascinate by their spectacular architecture, featuring an arrangement of nine microtubule triplets into an axial symmetry, whose biogenesis relies on yet elusive mechanisms. However, the recent discovery of new tubulins, such as δ-, ɛ-, or η-tubulin, could constitute a breakthrough for deciphering the assembly steps of this unconventional microtubule scaffold. Here, we report the functional analysis in vivo of ɛ-tubulin, based on gene silencing in Paramecium, which demonstrates that this protein, which localizes at the basal bodies, is essential for the assembly and anchorage of the centriolar microtubules