Search results for "VARIATION"
showing 10 items of 2124 documents
A la découverte des odeurs
2019
Often taken for granted, the sense of smell has seldom been discussed or understood. However, since the start of the 20th Century, studies in this area have grown exponentially and today there is a greater understanding of the olfactory system – at both structural and functional levels. Scientists now concern themselves with questions about the holistic nature of our sense of smell and are investigating the role of odors in interpersonal relations, in food intake processes, in the diagnosis of certain illnesses, and many other areas. The beginnings of this knowledge are as fascinating as they are abundant and numerous disciplines are involved: psychology, physiology, genetics, neuroscience,…
Phylogeographical footprints of the Strait of Gibraltar and Quaternary climatic fluctuations in the western Mediterranean: a case study with the grea…
2005
Correspondance: cosson@supagro.inra.fr; International audience; We used mitochondrial cyt b sequences to investigate the phylogenetic relationships of Crocidura russula (sensu lato) populations across the Strait of Gibraltar, western Europe, Maghreb, and the Mediterranean and Atlantic islands. This revealed very low genetic divergence between European and Moroccan populations. The application of a molecular clock previously calibrated for shrews suggested that the separation of European from Moroccan lineages occurred less than 60 000 bp, which is at least 5 million years (Myr) after the reopening of the Strait of Gibraltar. This means that an overwater dispersal event was responsible for t…
[Norovirus infections: an overview]
2010
National audience; Noroviruses belong to the Caliciviridae family. They are a major cause of sporadic cases and outbreaks of gastroenteritis in all age groups, and are responsible for a considerable disease burden in industrialized countries. Noroviruses are single-stranded RNA viruses, and show great genetic diversity making their detection difficult. Noroviruses can be divided into 5 genogroups, which themselves are subdivided into genotypes. Besides chance mutations that occur during viral replication, the great heterogeneity observed among noroviruses is also due to intra and inter-genotypic recombination events between strains. Some of these new variants or new recombinants are frequen…
Microbial diversity and structure are drivers of the biological barrier effect against Listeria monocytogenes in soil
2013
International audience; Understanding the ecology of pathogenic organisms is important in order to monitor their transmission in the environment and the related health hazards. We investigated the relationship between soil microbial diversity and the barrier effect against Listeria monocytogenes invasion. By using a dilution-to-extinction approach, we analysed the consequence of eroding microbial diversity on L. monocytogenes population dynamics under standardised conditions of abiotic parameters and microbial abundance in soil microcosms. We demonstrated that highly diverse soil microbial communities act as a biological barrier against L. monocytogenes invasion and that phylogenetic compos…
Gestion du pâturage au printemps en système bovin allaitant : diversité des pratiques en Saône-et-Loire
2009
National audience; Grazed grass is the cheapest forage for making meat'. In order to incite farmers to make their forage systems more self-sufficient and thrifty, the 'Chambre d'Agriculture de Saone-et-Loire' (a professional agricultural organization for that departement) has been monitoring for five years the management of spring grazing on 23 farms. The analysis of farmers' practices lead to considerations as to put to the best use the grazed grass, according to the pedo-climatic conditions and the constraints of the farms. With the aim of optimizing the pasture resources in order to limit the purchase of concentrates and to cope with the climatic hazards, the study of the management of s…
A mathematical method for determining genome divergence and species delineation using AFLP.
2002
The delineation of bacterial species is presently achieved using direct DNA-DNA relatedness studies of whole genomes. It would be helpful to obtain the same genomically based delineation by indirect methods, provided that descriptions of individual genome composition of bacterial genomes are obtained and included in species descriptions. The amplified fragment length polymorphism (AFLP) technique could provide the necessary data if the nucleotides involved in restriction and amplification are fundamental to the description of genomic divergences. Firstly, in order to verify that AFLP analysis permits a realistic exploration of bacterial genome composition, the strong correspondence between …
Population Structure and Comparative Genome Hybridization of European Flor Yeast Reveal a Unique Group of Saccharomyces cerevisiae Strains with Few G…
2014
Wine biological aging is a wine making process used to produce specific beverages in several countries in Europe, including Spain, Italy, France, and Hungary. This process involves the formation of a velum at the surface of the wine. Here, we present the first large scale comparison of all European flor strains involved in this process. We inferred the population structure of these European flor strains from their microsatellite genotype diversity and analyzed their ploidy. We show that almost all of these flor strains belong to the same cluster and are diploid, except for a few Spanish strains. Comparison of the array hybridization profile of six flor strains originating from these four co…
Variability of Christmas rose (Helleborus niger L.) populations and its potential use in genetic breeding
2005
International audience; The Christmas rose (Helleborus niger L.) is widely distributed in Southern and Central Europe, and Slovenia is probably one of the centers of its diversity. The investigation was aimed at evaluating phenotypic diversity among selected wild populations in Slovenia and neighboring Croatia. Some of the analyzed traits expressed relatively very high variation (e.g., number of leaves per plant, number of inflorescences per plant). The variation ranges of some of the analyzed traits were found to be wider than those mentioned in the literature. Statistical analysis indicated that variability was more expressed within than between populations. In terms of present market req…
Highlighting the role of diversity in driving weed dynamics and weed-crop interactions
2017
SPEBIOME INRA; Le Microscope à Dissection Laser (MDL) est composé de l’association d’un microscope équipé d’objectifs permettant un grossissement x2 à x100 et d’un système optique de découpe laser. Il permet de microdisséquer de façon ciblée des échantillons biologiques, de type bactérien, animal ou végétal. Sa finesse de dissection permet de sélectionner, d’isoler puis de récupérer des cellules cibles afin de concentrer le matériel. Ainsi, il est possible de réaliser des analyses de transcriptomique, de génomique ou de protéomique à partir de cellules cibles. Avant de microdisséquer, la préparation des échantillons est primordiale pour s’assurer de récupérer une qualité et une quantité suf…
Effets du cuivre sur quelques indicateurs de la qualité biologique des sols viticoles. Etude à différentes échelles
2008
Des produits à base de cuivre sont utilisés depuis plus d’un siècle en viticulture pour lutter contre le mildiou (et d’autres maladies). Cet élément s’accumule dans le sol, où il peut atteindre des concentrations importantes, susceptibles d’en altérer le fonctionnement biologique. Bien que potentiellement dangereux pour la biocénose des sols, le cuivre est toujours utilisé, notamment en Agriculture Biologique. Dans ce travail, nous avons cherché à préciser les impacts du cuivre sur quelques aspects de la qualité biologique des sols viticoles en conditions « réelles », à court, moyen et long terme. Les effets à long terme ont été appréciés à l’échelle d’une région viticole (la Champagne) à t…