Search results for "Invasive"
showing 10 items of 1141 documents
Mise en place d'un modèle in vivo de colonisation digestive stable à C. Abicans chez la souris immunocompétente
2012
Les levures du genre Candida sont des agents pathogènes opportunistes responsables de candidoses invasives chez les sujets immunodéprimés, et sont associées à un taux de mortalité élevé. Elles représentent 8 à 15% des infections nosocomiales hématogènes et Candida albicans est l’espèce la plus fréquemment isolée en pathologie humaine. Initialement C. albicans appartient à la flore commensale intestinale, buccale et vaginale de l’homme. Ce commensalisme résulte d’un équilibre entre les propriétés biologiques de la levure et les systèmes de défense de l’hôte. La rupture de cet équilibre chez un patient fragilisé aura pour conséquence une colonisation intense des muqueuses favorisant un envahi…
Ecology and impact of an emerging invasive species in France: western ragweed (Ambrosia psilostachya DC.)
2015
Western ragweed (Ambrosia psilostachya DC.) is a perennial member of the Asteraceae native to North America that was introduced into France at the end of the 19th Century. Field observations have provided evidence of a recent expansion and of the emergence of dense clonal populations potentially threatening the biodiversity of certain Mediterranean sensitive or degraded habitats. This study therefore aimed to identify the habitats colonized and the ecological conditions favouring successful colonization by this species, and to determine its impact on the plant communities of the semi-natural habitats invaded. Ambrosia psilostachya mostly colonizes ruderal (61 %) and cultivated (14 %) enviro…
Characterisation of phenotypic plasticity in seedling stage of native and invasive populations in Ambrosia artemisiifolia L.
2012
Increased phenotypic plasticity has often been invoked as an hypothesis to explain the capacity of alien invasive plant species to colonize new environments, because it may enhance the ability of plants to cope with new biotic and abiotic conditions. Following this hypothesis, alien invasive populations should be represented by more plastic genotypes than populations in the native range. In annual species, the seedling stage is of crucial importance for population dynamics but surprisingly very few studies have investigated differences in phenotypic plasticity on seedling traits. Based on populations from the native range (North America) and the invasive range (France) of Ambrosia artemisii…
Do the high phenotypic plasticity of A. artemisiifolia L. explain its invasive success in France?
2008
International audience; Ambrosia artemisiifolia (Asteraceae) is an invasive annual plant introduced from North America to Europe over 100 years ago. This plant species is now widespread in numerous countries all over the world, causing damages to agricultural crops and human health. Ambrosia artemisiifolia is spreading as a weed in many field crops but is also able to invade a wide range of areas such as various human disturbed habitats or riverbanks (Figure 1). A considerable variability of the life history traits of A. artemisiifolia was previously observed among and within different populations (Fumanal et al., 2007). Since the success of colonization of some invasive plant species may r…
La diversité des communautés végétales des forêts alluviales de l’Allier est-elle affectée par l’invasion de l’Érable négundo, du Robinier faux-acaci…
2012
Identifiant ProdInra 270418 SPE EcolDur CT3; Master; L’objectif de notre étude a été d’analyser les effets de l’invasion de 3 espèces végétales (Érable négundo, Robinier faux-acacia, Renouée de Bohême) sur la diversité spécifique et fonctionnelle ainsi que sur la structure et la composition spécifique des communautés végétales des forêts alluviales de l’Allier. Des relevés de végétation ont été réalisés dans des paires de quadrats contiguës, envahis et non envahis par les 3 espèces invasives étudiées et dans 3 habitats envahis des forêts alluviales de l’Allier (Saulaie-peupleraie de niveau topographique haut et bas et Chênaie pédonculée-ormaie). Complémentairement à cette approche, un gradi…
Common ragweed national maps & public policies in France
2014
Common ragweed (Ambrosia artemisiifolia L.) has been detected in France in the middle of the XIXth century. It has spread throughout the territory during the XXth century with a critical evolution. Public policies have not been able to contain this spread at the moment, and it is now difficult to find ways to tackle the invasion. Publication of national and regional maps seems to be an effective tool to draw up an overview of the situation and build management strategies. With a set of historical and modern data collected all over the French territory, and from many different stakeholders, we consider the progress of the species in time. The system of legislation applied locally is analyzed…
Growth and reproduction responses of French invasive and North American native populations of common ragweed, Ambrosia artemisiifolia L. to defoliati…
2012
Enemy release and Evolution of Increased Competitive Ability hypotheses have been put forward to explain invasion success of introduced plant species. These hypotheses assume that the loss of natural enemies could induce an evolutionary change in plant defence and in resource allocation allowing the introduced plant populations to increase in vigour and fitness. To detect changes in functional traits following defoliation, we compared native and introduced populations of common ragweed, grown in a common garden environment. We compared six populations of Ambrosia artemisiifolia L., three from the North American native range and three from the French introduction range. We explored the effec…
Rôle de la diversité fonctionnelle des communautés végétales sur leur résistance à l’invasion par l’Ambroisie à feuilles d’Armoise (Ambrosia artemisi…
2012
Rapport de Stage de Master 2 SPE EcolDur CT3; Master; Les invasions biologiques posent de nombreux problèmes écologiques et économiques. Il est important de déterminer les facteurs à l’origine du succès des espèces exotiques envahissantes afin de maîtriser ce phénomène. Le but de la présente étude est d’évaluer le rôle de trois caractéristiques des communautés végétales (diversité spécifique, diversité fonctionnelle et densité) sur leur résistance à l’invasion par l’ambroisie à feuilles d’armoise, Ambrosia artemisiifolia. Des assemblages artificiels de plantes fréquemment rencontrées dans les communautés envahies par l’Ambroisie ont été effectués et soumis à l’invasion par l’espèce. Trois t…
Ambroisie à feuilles d'armoise : une enquête sur son passé
2006
National audience
Acetone Vapor-Sensing Properties of Chitosan-Polyethylene Glycol Using Surface Plasmon Resonance Technique
2020
To non-invasively monitor and screen for diabetes in patients, there is need to detect low concentration of acetone vapor in the range from 1.8 ppm to 5 ppm, which is the concentration range of acetone vapor in diabetic patients. This work presents an investigation for the utilization of chitosan-polyethylene glycol (PEG)-based surface plasmon resonance (SPR) sensor in the detection of trace concentration acetone vapor in the range of breath acetone in diabetic subjects. The structure, morphology, and elemental composition of the chitosan-PEG sensing layer were characterized using FTIR, UV-VIS, FESEM, EDX, AFM, and XPS methods. Response testing was conducted using low concentration of aceto…