Fruit consumption, seed dispersal and seed fate in the vine Strychnos erichsonii in a French Guianan forest

La consommation des fruits et la dissémination des graines ont été analysées chez trois individus de la liane Strychnos erichsonii (Loganiaceae) en forêt mature de Guyane française, pendant la saison de production minimale en fleurs et fruits. Cinq espèces consommatrices, oiseaux ou mammifères diurnes ou nocturnes, ont été observées, alors qu'un rongeur terrestre a été capturé dans des pièges appâtés avec de la pulpe de fruits ou des graines de S. erichsonii. Un mammifère diurne et un nocturne ont dispersé les graines à grande distance. Les frugivores arboricoles consommaient les fruits à mesure de leur apparition, et mangeaient également des fruits immatures. L'utilisation de collecteurs a montré que le taux de prélèvement de fruits était plus élevé la nuit chez les lianes les plus productives (productivité « instantanée »). Plus des deux-tiers des graines échantillonnées sur des transects jusqu'à 30 m du pied-mère étaient mortes ou parasitées, sans qu'une relation claire ait pu être établie avec leur localisation (sous ou au-delà de la couronne). La densité de graines chutait dans les premiers mètres à partir du pied-mère, mais restait non négligeable jusqu'à 15 m de la couronne sur certains transects. Les quelques plantules trouvées étaient réparties indépendamment de leur position sous ou au-delà de la couronne. Une mortalité élevée des graines et un faible nombre en même temps qu'un renouvellement rapide des plantules sous et à proximité du pied-mère suggèrent que la dispersion des graines à grande distance est primordiale pour la régénération de la plante. La dispersion à grande distance semble assurée par un petit nombre d'espèces variées. Par sa fructification régulière pendant la période de disponibilité minimale en fleurs et fruits et par sa place privilégiée dans le régime alimentaire de plusieurs mammifères frugivores, S. erichsonii constitue probablement une ressource importante pour ces espèces pendant la saison de faible disponibilité alimentaire

A combinatorial algorithm for microbial consortia synthetic design

International audienceSynthetic biology has boomed since the early 2000s when it started being shown that it was possible to efficiently synthetize compounds of interest in a much more rapid and effective way by using other organisms than those naturally producing them. However, to thus engineer a single organism, often a microbe, to optimise one or a collection of metabolic tasks may lead to difficulties when attempting to obtain a production system that is efficient, or to avoid toxic effects for the recruited microorganism. The idea of using instead a microbial consortium has thus started being developed in the last decade. This was motivated by the fact that such consortia may perform more complicated functions than could single populations and be more robust to environmental fluctuations. Success is however not always guaranteed. In particular, establishing which consortium is best for the production of a given compound or set thereof remains a great challenge. This is the problem we address in this paper. We thus introduce an initial model and a method that enable to propose a consortium to synthetically produce compounds that are either exogenous to it, or are endogenous but where interaction among the species in the consortium could improve the production line. Synthetic biology has been defined by the European Commission as " the application of science, technology, and engineering to facilitate and accelerate the design, manufacture, and/or modification of genetic materials in living organisms to alter living or nonliving materials ". It is a field that has boomed since the early 2000s when in particular Jay Keasling showed that it was possible to efficiently synthetise a compound–artemisinic acid–which after a few more tricks then leads to an effective anti-malaria drug, artemisini

BacHBerry: BACterial Hosts for production of Bioactive phenolics from bERRY fruits

BACterial Hosts for production of Bioactive phenolics from bERRY fruits (BacHBerry) was a 3-year project funded by the Seventh Framework Programme (FP7) of the European Union that ran between November 2013 and October 2016. The overall aim of the project was to establish a sustainable and economically-feasible strategy for the production of novel high-value phenolic compounds isolated from berry fruits using bacterial platforms. The project aimed at covering all stages of the discovery and pre-commercialization process, including berry collection, screening and characterization of their bioactive components, identification and functional characterization of the corresponding biosynthetic pathways, and construction of Gram-positive bacterial cell factories producing phenolic compounds. Further activities included optimization of polyphenol extraction methods from bacterial cultures, scale-up of production by fermentation up to pilot scale, as well as societal and economic analyses of the processes. This review article summarizes some of the key findings obtained throughout the duration of the project

The structure of marsupial community in French Guiana

Présentation d'éléments nouveaux sur la diversité spécifique et l'habitat des marsupiaux de Guyane française.L'accent est mis sur l'influence du stade de succession de la végétation sur la structure du peuplement de marsupiaux, à partyir d'une comparaison entre forêt primaire (forêt mature intacte) et forêt secondair

Experimental programme on absolute fission fragment yields wth the Lohengrin spectrometer at ILL: new optical and statistical methodologies

International audienceThe study of fission yields has a major impact on the characterization and understanding of the fission process and is mandatoryfor reactor applications. The mass and isotopic yields of the fission fragments have a direct influence on the amount of neutronpoisons that limit the fuel burnup and on the evaluation of the residual power of the reactor after shutdown. The fission yields ofthe plutonium nuclides are also mandatory for the studies on the fuel multi-recycling. In order to significantly improve the precisionof nuclear data, more and more fundamental fission models are used in the evaluation processing. Therefore, tests of fissionmodels become a central issue to achieve a coherent libraries of nuclear data. In this framework, an important investigation inthe experimental limits of facilities is required to provide complete sets of data with their coherent variance-covariance matrices.In the past with the LOHENGRIN spectrometer of the ILL, priority has been given for the studies in the light fission fragmentmass range. The LPSC in collaboration with ILL and CEA has developed a measurement program on symmetric and heavy massfission fragment distributions. The combination of measurements with ionisation chamber and Ge detectors is necessary to describeprecisely the heavy fission fragment region in mass and charge. Recently, new measurements of fission yields and kineticenergy distributions, with different fissioning systems, were performed with this facility. The focus has been done on the selfnormalizationof the data to provide new absolute measurements, independently of any libraries, and the experimental covariancematrix. To reach precise measurements, a new experimental procedure was developed along with a new analysis methodbased on metadata. Because of the complex correction scheme from count rates to yields, a classical propagation uncertaintyis not possible. The new analysis path gives the mean value of mass yields, its probability density function and the associatedexperimental variance-covariance matrices. All this information is a first step to bring nuclear data into statistical tests of theunderlying hypothesis of fission models