Search results for "cycle"
showing 10 items of 3119 documents
Loss in microbial diversity affects nitrogen cycling in soil
2013
National audience; Microbial communities have a central role in ecosystem processes by driving the Earth’s biogeochemical cycles. However, the importance of microbial diversity for ecosystem functioning is still debated. Here, we experimentally manipulated the soil microbial community using a dilution approach to analyze the functional consequences of diversity loss. A trait-centered approach was embraced using the denitrifiers as model guild due to their role in nitrogen cycling, a major ecosystem service. How various diversity metrics related to richness, eveness and phylogenetic diversity of the soil denitrifier community were affected by the removal experiment was assessed by 454 sequen…
Linking microbial diversity and ecosystem functioning: The nitrogen cycle example
2014
Microbial communities have a central role in ecosystem processes by driving the Earth’s biogeochemical cycles. However, the importance of microbial diversity for ecosystem functioning is still debated. While functional trait-based approaches are commonly used for at least two decades in microbiology, most microbial diversity studies are still carried out with the rRNA genes. This talk will show how metagenomic approaches targeting microbial guilds involved in nitrogen cycling can help bridging microbial community ecology and ecosystem processes in terrestrial environments.
A core microbiota of plant and earthworm interaction? Phylogenetic and functional aspects
2017
International audience; The core microbiota concept has been proposed to describe the subset of a microbiota (e.g. the rhizosphere microbial community) associated with a given host (e.g. a plant) going beyond macroenvironment differences (e.g. soil type), and characterized by taxonomic markers (e.g. 16S rRNA gene sequences). Its existence has been questioned by geographical studies, showing the overruling soil type effect in shaping microbial communities. As far as biotic determinants are concerned, several “hosts” or macroorganisms are impacting a given habitat and its specific microbial community. In soils, there is an overlap between the so-called rhizosphere and the drilosphere, defined…
Les maladies du bois de la vigne : recherches pour apporter des solutions de lutte aux Professionnels
2017
Les travaux réalisés sur deux maladies du bois de la vigne (esca, BDA) ont montré leur effet sur la récolte et la croissance de la pousse printanière qui était annulé deux années après l’apparition des symptômes. Ces maladies ont aussi conduit à des modifications des propriétés analytiques des moûts et des vins. Les vins issus de raisins collectés sur des ceps symptomatiques n’étaient pas toujours les plus dépréciés. Les études effectuées sur le cycle biologique ont permis de mettre au point des outils pour différencier les individus de deux espèces de Botryosphaeriaceae et des outils d’hybridation in situ qui permettront de les localiser précisément dans les tissus. Elles ont aussi identif…
Activity, size and structure of the nitrate reducer community in relation to land-use and fertilization regime in Madagascar
2007
Communication orale, résumé; absent
Interactions in the network of Usher syndrome type 1 proteins
2004
International audience; Defects in myosin VIIa, harmonin (a PDZ domain protein), cadherin 23, protocadherin 15 and sans (a putative scaffolding protein), underlie five forms of Usher syndrome type I (USH1). Mouse mutants for all these proteins exhibit disorganization of their hair bundle, which is the mechanotransduction receptive structure of the inner ear sensory cells, the cochlear and vestibular hair cells. We have previously demonstrated that harmonin interacts with cadherin 23 and myosin VIIa. Here we address the extent of interactions between the five known USH1 proteins. We establish the previously suggested sans-harmonin interaction and find that sans also binds to myosin VIIa. We …
Spatial distribution of ammonia-oxidizing bacteria and archaea across a 44-hectare farm related to ecosystem functioning
2011
Characterization of spatial patterns of functional microbial communities could facilitate the understanding of the relationships between the ecology of microbial communities, the biogeochemical processes they perform and the corresponding ecosystem functions. Because of the important role the ammonia-oxidizing bacteria (AOB) and archaea (AOA) have in nitrogen cycling and nitrate leaching, we explored the spatial distribution of their activity, abundance and community composition across a 44-ha large farm divided into an organic and an integrated farming system. The spatial patterns were mapped by geostatistical modeling and correlations to soil properties and ecosystem functioning in terms …
Widespread diminishing anthropogenic effects on calcium in freshwaters
2019
Calcium (Ca) is an essential element for almost all living organisms. Here, we examined global variation and controls of freshwater Ca concentrations, using 440 599 water samples from 43 184 inland water sites in 57 countries. We found that the global median Ca concentration was 4.0 mg L−1 with 20.7% of the water samples showing Ca concentrations ≤ 1.5 mg L−1 , a threshold considered critical for the survival of many Ca-demanding organisms. Spatially, freshwater Ca concentrations were strongly and proportionally linked to carbonate alkalinity, with the highest Ca and carbonate alkalinity in waters with a pH around 8.0 and decreasing in concentrations towards lower pH. However, on a temporal…
Pd.D Graduates in France : Training, Careers and Policy Issues
1999
International audience; This paper presents french policy on the training of Ph.D graduates since the 80's, the actual training of Ph.D graduates in France and give some data on employment of Ph.D graduates. Cet article présente rapidement la politique française menée en matière de formation des docteurs depuis le début des années 80, la formation des docteurs et donne des informations sur le devenir des docteurs sur le marché du travail.
Docteurs travaillant sur l'enseignement supérieur : formation et carrière professionnelle en France
2000
In this panel, the topic discussed is the training of young researchers in the particular field of "Higher education" and their prospects. This is in order to assess the chances in the Research in Higher education. This paper presents the Ph.D training in general and some characteristics of the Ph.D training in "Higher education". After, it pays some attention to what is required by young researchers for careers in Higher education research.