Search results for "030306 microbiology"
showing 10 items of 772 documents
Phylogenomics of Mycobacterium africanum reveals a new lineage and a complex evolutionary history.
2021
Coscolla et al.
A New Phylogenetic Framework for the Animal-adaptedMycobacterium tuberculosisComplex
2018
Tuberculosis (TB) affects humans and other animals and is caused by bacteria from the Mycobacterium tuberculosis complex (MTBC). Previous studies have shown that there are at least nine members of the MTBC infecting animals other than humans; these have also been referred to as ecotypes. However, the ecology and the evolution of these animal-adapted MTBC ecotypes are poorly understood. Here we screened 12,886 publicly available MTBC genomes and newly sequenced 17 animal-adapted MTBC strains, gathering a total of 529 genomes of animal-adapted MTBC strains. Phylogenomic and comparative analyses confirm that the animal-adapted MTBC members are paraphyletic with some members more closely relate…
Snapshots of a shrinking partner: Genome reduction inSerratia symbiotica
2016
AbstractGenome reduction is pervasive among maternally-inherited endosymbiotic organisms, from bacteriocyte- to gut-associated ones. This genome erosion is a step-wise process in which once free-living organisms evolve to become obligate associates, thereby losing non-essential or redundant genes/functions. Serratia symbiotica (Gammaproteobacteria), a secondary endosymbiont present in many aphids (Hemiptera: Aphididae), displays various characteristics that make it a good model organism for studying genome reduction. While some strains are of facultative nature, others have established co-obligate associations with their respective aphid host and its primary endosymbiont (Buchnera). Further…
One-Cell Doubling Evaluation by Living Arrays of Yeast, ODELAY!
2016
Abstract Cell growth is a complex phenotype widely used in systems biology to gauge the impact of genetic and environmental perturbations. Due to the magnitude of genome-wide studies, resolution is often sacrificed in favor of throughput, creating a demand for scalable, time-resolved, quantitative methods of growth assessment. We present ODELAY (One-cell Doubling Evaluation by Living Arrays of Yeast), an automated and scalable growth analysis platform. High measurement density and single-cell resolution provide a powerful tool for large-scale multiparameter growth analysis based on the modeling of microcolony expansion on solid media. Pioneered in yeast but applicable to other colony formin…
Long-term genomic coevolution of host-parasite interaction in the natural environment
2017
Antagonistic coevolution of parasite infectivity and host resistance may alter the biological functionality of species, yet these dynamics in nature are still poorly understood. Here we show the molecular details of a long-term phage–bacterium arms race in the environment. Bacteria (Flavobacterium columnare) are generally resistant to phages from the past and susceptible to phages isolated in years after bacterial isolation. Bacterial resistance selects for increased phage infectivity and host range, which is also associated with expansion of phage genome size. We identified two CRISPR loci in the bacterial host: a type II-C locus and a type VI-B locus. While maintaining a core set of conse…
Évaluation du kit de PCR en temps réel MycoGENIE ® Pneumocystis jirovecii pour le diagnostic moléculaire de la pneumocystose
2017
Pneumocystis jirovecii (Pj) est un champignon pathogene opportuniste strictement humain. Il colonise transitoirement et sans symptome l’arbre respiratoire des patients immunocompetents, et peut etre responsable d’infections pulmonaires severes chez les patients immunodeprimes. Le diagnostic biologique de pneumocystose repose sur la mise en evidence du pathogene a l’examen direct d’un prelevement pulmonaire profond. Si l’examen direct manque souvent de sensibilite, de nombreuses techniques de PCR se sont developpees pour ameliorer la sensibilite de detection du champignon. Les techniques de PCR quantitatives (qPCR) permettent de quantifier la charge fongique dans le prelevement, et potentiel…
Emergence and spread of a SARS-CoV-2 variant through Europe in the summer of 2020.
2020
A variant of SARS-CoV-2 emerged in early summer 2020, presumably in Spain, and has since spread to multiple European countries. The variant was first observed in Spain in June and has been at frequencies above 40% since July. Outside of Spain, the frequency of this variant has increased from very low values prior to 15th July to 40-70% in Switzerland, Ireland, and the United Kingdom in September. It is also prevalent in Norway, Latvia, the Netherlands, and France. Little can be said about other European countries because few recent sequences are available. Sequences in this cluster (20A.EU1) differ from ancestral sequences at 6 or more positions, including the mutation A222V in the spike pr…
Human Phageprints: A high-resolution exploration of oral phages reveals globally-distributed phage families with individual-specific and temporally-s…
2019
AbstractMetagenomic studies have revolutionized the study of novel phages. However these studies trade the depth of coverage for breadth. In this study we show that the targeted sequencing of a phage genomic region as small as 200-300 base pairs, can provide sufficient sequence diversity to serve as an individual-specific barcode or “Phageprint”. The targeted approach reveals a high-resolution view of phage communities that is not available through metagenomic datasets. By creating instructional videos and collection kits, we enabled citizen scientists to gather ∼700 oral samples spanning ∼100 individuals residing in different parts of the world. In examining phage communities at 6 differen…
Production of β-glucosidases by European Armillaria species
2020
International audience; Abstract Production of β-glucosidase was investigated in nine isolates of Armillaria representing four species found in Europe: Armillaria mellea and Armillaria ostoyae, considered to be pathogenic and moderately pathogenic, respectively, and Armillaria. gallica and Armillaria cepistipes, both considered to be non-pathogenic. β-glucosidase was predominantly produced in the rhizomorphs, while the vegetative mycelium produced only a low amount of enzyme. Pachlewski's medium containing ammonium tartrate, glucose, maltose and thiamine was very efficient in promoting differentiation and growth of rhizomorphs. In A. ostoyae and A. cepistipes, a large proportion of β-glucos…
L'impact du mercure sur les bactéries telluriques
1999
Les polluants toxiques, tels que le mercure, affectent largement les ecosystemes aquatiques, mais aussi les sols. Comment les bacteries telluriques reagissent-elles ?