Diversity among mycoplasma-like organisms inducing grapevine yellows in France

As antibodies and molecular probes which were previously obtained for diagnosis of grapevine flavescence doree (FD; a yellows disease induced by a MLO), showed to be highly specific, a survey of grapevine samples collected in different viticultural areas in France was undertaken, using a PCR method with primers allowing amplification of a part of the 16S rRNA gene of most MLOs, and restriction analyses of the amplified products (AHRENS and SEEMÜLLER 1992). The presence of MLO was established in all the different grapevine samples, and their diversity was demonstrated. The typcial pattern yielded by FD sensu stricto-MLO was found in samples from southern vineyards, including a symptomless rootstock. Two different patterns were found in samples affected by bois noir disease of northern French vineyards, one of these patterns being previously undescribed. The present survey was non exhaustive and should be followed in the frame of a large collaboration between viticultural countries. It showed the diversity in causal agents of diseases which converge in symptomatology, and emphasizes on the need of specific diagnosis tools, for identification of each of the vector species, for epidemiological studies, and availability of planting material

Detection of flavescence dorée phytoplasma in grapevine in northern Spain

Research NoteGrapevine yellows diseased stocks were observed in vineyards of the Alt Emporda area, northern Spain. Phytoplasma was detected and characterized by PCR-RFLP in the region of the 16S rDNA of phytoplasmas or by ELISA. For the first time a FD phytoplasma was detected in Spain

Segmentation géométrique d'images 3D par analyse topologique de représentations compactes

La reconnaissance et la caractérisation des formes sont des questions clés de l'analyse d'image. Nous proposons ici une nouvelle méthode de segmentation géométrique d'images 3D basée sur l'analyse topologique de l'axe médian. Cette technique permet de décomposer un volume en parties de forme planaire ou tubulaire pour en extraire des paramètres géométriques quantitatifs et analyser des réseaux poreux complexes. Après l'avoir valider sur un fantôme, on applique cette méthode sur des images réelles de réseaux trabéculaires osseux afin de la comparer à une approche basée sur un squelette

Is flood defense changing in nature? Shifts in the flood defense strategy in six European countries

In many countries, flood defense has historically formed the core of flood risk management but this strategy is now evolving with the changing approach to risk management. This paper focuses on the neglected analysis of institutional changes within the flood defense strategies formulated and implemented in six European countries (Belgium, England, France, the Netherlands, Poland, and Sweden). The evolutions within the defense strategy over the last 30 years have been analyzed with the help of three mainstream institutional theories: a policy dynamics-oriented framework, a structure-oriented institutional theory on path dependency, and a policy actors-oriented analysis called the advocacy coalitions framework. We characterize the stability and evolution of the trends that affect the defense strategy in the six countries through four dimensions of a policy arrangement approach: actors, rules, resources, and discourses. We ask whether the strategy itself is changing radically, i.e., toward a discontinuous situation, and whether the processes of change are more incremental or radical. Our findings indicate that in the European countries studied, the position of defense strategy is continuous, as the classical role of flood defense remains dominant. With changing approaches to risk, integrated risk management, climate change, urban growth, participation in governance, and socioeconomic challenges, the flood defense strategy is increasingly under pressure to change. However, these changes can be defined as part of an adaptation of the defense strategy rather than as a real change in the nature of flood risk management

Detección y profilaxis del fitoplasma del amarilleamiento del olmo en Francia

Surveys conducted since 1998, showed that symptoms typical of Elm Yellows (EY) were quite frequent in the elm conservatories of Nogent-sur-Vernisson and Guémené- Penfao, France, and on forest trees in several locations in western Europe. Phytoplasmas were detected in symptomatic trees and plants using Polymerase Chain Reaction amplification followed by Restriction Fragment Length Polymorphism analyses of conserved regions of 16S rDNA of phytoplasmas, or of the EY group-specific non ribosomal DNA fragment FD9. Potential vectors were searched among leafhoppers and planthoppers trapped in conservatories and tested for the presence of phytoplasma in their body. Sanitation of multiplication material was experimented using soaking of dormant cuttings and branches in hot water, according to the method devised for destruction of phytoplasma in grapevine multiplication material. Phytoplasmas detected in a number of the elm clones held in the conservatories and in several forest or hedgerow elm trees, showed some diversity, according to restriction analyses of the FD9 fragment. Both American and European types were characterized. Four leaf- and planthopper species were found to carry an EY phytoplasma. Plants grown from cuttings taken from EY-infected clones and soaked in hot water (50 °C, 45 mn) never developed symptoms and tested phytoplasma negative. Most of untreated control plants were all symptomatic and positive. In the future, EY phytoplasma should be carefully checked, especially in sensitive cultivars. More studies of EY phytoplasma variability and potential vecteurs and the assessment of routine use of hot water therapy in multiplication of material should be conducted.Las observaciones realizadas desde 1998 han mostrado que los síntomas típicos del amarilleamiento del olmo (EY) son muy frecuentes en los bancos de olmo de Nogent- sur-Vernisson y Guémené-Penfao, Francia, y en árboles en campo de varias localidades de Europa occidental. La presencia de fitoplasmas se detectó, mediante el uso de la reacción en cadena de la polimerasa seguida de análisis de polimorfismo de longitud de los fragmentos de restricción en regiones conservadas de rADN de16S de fitoplasmas, o del fragmento FD9 de ADN no ribosómico, específico del fitoplasma del EY, en árboles y plantas sintomáticos. Se buscó vectores potenciales entre homópteros cicadélidos y fulgóridos capturados en los invernáculos y estudiados con el fin de detectar la presencia de fitoplasmas en su cuerpo. Como tratamiento profiláctico del material reproductivo, se experimentó sumergiendo las estaquillas y ramas durmientes en agua caliente, de acuerdo con el método desarrollado para la destrucción de fitoplasmas en material de reproducción de la vid. Según el análisis de restricción del fragmento FD9, los fitoplasmas que fueron detectados en algunos clones de olmo conservados en los bancos clonales, así como en varios olmos de campo, mostraron una cierta diversidad genética. Tanto el tipo americano como el europeo fueron caracterizados. Se encontró que cuatro de las especies de cicadélidos y fulgóridos eran portadoras del fitoplasma del EY. Las plantas que se desarrollaron a partir de estaquillas de clones infectados por el EY y que habían sido sumergidas en agua caliente (50 ºC, 45 minutos) nunca presentaron síntomas. Igualmente, las pruebas para la detección del fitoplasma fueron negativas. Por el contrario, todas las plantas control que no habían sido tratadas presentaron síntomas, y los resultados de las pruebas fueron positivos. En el futuro, la presencia del fitoplasma del EY deberías ser comprobada sistemáticamente, especialmente en cultivares sensibles. Deberían desarrollarse más estudios sobre la variabilidad del fitoplasma del EY y vectores potenciales, y sobre la evaluación del uso continuo del tratamiento con agua caliente en la multiplicación del material

Grapevine yellows: Comparison of different procedures for DNA extraction and amplification with PCR for routine diagnosis of phytoplasmas in grapevine

In order to devise a procedure to be used as reference for detection of grapevine phytoplasmas and monitoring of Flavescence dorée, 12 combinations comprising three methods of plant DNA extraction and 4 procedures for amplification in polymerase chain reaction of phytoplasma DNA were examined in parallel using the same plant tissues infected with phytoplasmas. In a first series tissues of periwinkles (Catharanthus roseus) infected with phytoplasma isolates of the Elm yellows group (16SrV) and maintained in the greenhouse, were used. In a second series tissues of grapevines (Vitis vinifera) naturally infected with Flavescence dorée or Palatinate grapevine yellows phytoplasma were used. The DNA preparations obtained with each of the three extraction procedures were used undiluted or serially diluted, as target DNA in the 4 nested-polymerase chain reactions. The results showed differences in the efficiency among different methods of extraction as well as in the sensitivity among the DNA amplification procedures, which improved when DNA extracted from field grapevines was diluted. After additional comparative validation on numerous field-collected samples of GY-affected grapevines, the quickest extraction procedure was selected for use in routine diagnosis, with nested-PCR amplification either of ribosomal DNA or of the FD9 DNA fragment specific for Flavescence dorée and other 16SrV group phytoplasmas

Flood risk mitigation in Europe: how far away are we from the aspired forms of adaptive governance?

Flood mitigation is a strategy that is growing in importance across Europe. This growth corresponds with an increasing emphasis on the need to learn to live with floods and make space for water. Flood mitigation measures aim at reducing the likelihood and magnitude of flooding and complement flood defenses. They are being put in place through the implementation of actions that accommodate (rather than resist) water, such as natural flood management or adapted housing. The strategy has gained momentum over the past 20 years in an effort to improve the sustainability of flood risk management (FRM) and facilitate the diversification of FRM in the pursuit of societal resilience to flooding. Simultaneously, it is increasingly argued that adaptive forms of governance are best placed to address the uncertainty and complexity associated with social-ecological systems responding to environmental challenges, such as flooding. However, there have been few attempts to examine the extent to which current flood risk governance, and flood mitigation specifically, reflect these aspired forms of adaptive governance. Drawing from EU research into flood risk governance, conducted within the STAR-FLOOD project, we examine the governance of flood mitigation in six European countries: Belgium, England, France, the Netherlands, Poland, and Sweden. Using in-depth policy and legal analysis, as well as interviews with key actors, the governance and implementation of flood mitigation in these countries is evaluated from the normative viewpoint of whether, and to what extent, it can be characterized as adaptive governance. We identify five criteria of adaptive governance based on a comprehensive literature review and apply these to each country to determine the “distance” between current governance arrangements and adaptive governance. In conclusion, the flood mitigation strategy provides various opportunities for actors to further pursue forms of adaptive governance. The extent to which the mitigation strategy is capable of doing so varies across countries, however, and its role in stimulating adaptive governance was found to be strongest in Belgium and England

Efficacité théorique d'un indice de sélection sur collatéraux pour le foie gras de l'oie Landaise

L’efficacité théorique d’un indice de sélection sur collatéraux pour améliorer le poids du foie gras de l’oie Landaise est étudiée. Sur m oisons disponibles par oie et saison de reproduction, n sont gavés et abattus pour servir de test des reproducteurs, m - n animaux contemporains (dont la moitié de chaque sexe) sont candidats à la sélection. Cela revient à chercher l’optimum pour n, de façon à maximiser le produit de l’intensité de sélection par la corrélation entre la valeur génétique additive et celle estimée par l’indice de sélection. Une solution sub-optimale est trouvée, pour un intervalle de génération de un an. Une solution pratique est proposée pour un noyau de sélection de faible effectif (160 oies).Theoretical efficacy of a selection index to increase fat liver production of Landaise goose is studied. For m goslings per goose in each reproductive season, n are force feeded and slaughtered for the test of breeding animals, m - n contemporaneous animals (half of each sex) are candidates for selection. We have to look for an optimum for n, number of animals of test, in order to maximise the product of selection intensity and correlation between additive genetic value and the one estimated by the selection index. A sub optimum solution is found, with a generation interval of one year. A practical solution is proposed for a nucleus of limited size (160 geese)

Etude de quelques facteurs de variation du poids à deux mois et des performances de prégavage et de gavage d'oies Landaises en station

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