133 research outputs found

Toulouse – 16 rue LĂ©on-TolstoĂŻ

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Le projet de construction d’une rĂ©sidence a suscitĂ© une fouille prĂ©ventive en fin d’annĂ©e 2015. L’objectif de cette opĂ©ration s’inscrit dans une volontĂ© de caractĂ©riser l’occupation de la marge mĂ©ridionale de la vaste agglomĂ©ration du second Ăąge du Fer de Toulouse-Saint-Roch. L’emprise concernĂ©e se situe de fait sur le bas de versant des coteaux du Pech David, Ă  environ 200 m Ă  vol d’oiseau au sud de la caserne Niel. Sur une superficie avoisinant 2 000 m2, 46 structures ont Ă©tĂ© mises au jour...

GREASE OR SAND THE WHEEL? THE EFFECT OF INDIVIDUAL BRIBES ON THE DRIVERS OF AGGREGATE PRODUCTIVITY GROWTH

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The Asian paradox suggests a net grease-the-wheel effect of corruption. Under the assumption of diminishing returns to bribes, going beyond the single-representative-firm assumption, we argue that the grease and sand-the-wheel effects are likely to co-exist among a large number of firms, and that the industrial effect of corruption depends on the productivity drivers that fuel firm’s dynamics. We decompose Indonesian manufacturing labor productivity growth while contrasting and comparing the contributions of no-, low- and high-bribing firms over the period 1975-94. We confirm the coexistence of grease and sand-the-wheel effects. Industrial productivity gains stem first from the net entry of non-corrupted firms, evidencing a sand-the-wheel effect. Market share reallocation from low to high productivity growth incumbents paying low bribes is the second source of productivity growth, pointing at a grease-the-wheel effect. Intra- plant productivity growth is overall negative and largely attributable to high-corruption plants, suggesting a sand-the-wheel effect

Controlling the Biological Effects of Spermine Using a Synthetic Receptor

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Polyamines play an important role in biology, yet their exact function in many processes is poorly understood. Artificial host molecules capable of sequestering polyamines could be useful tools for studying their cellular function. However, designing synthetic receptors with affinities sufficient to compete with biological polyamine receptors remains a huge challenge. Binding affinities of synthetic hosts are typically separated by a gap of several orders of magnitude from those of biomolecules. We now report that a dynamic combinatorial selection approach can deliver a synthetic receptor that bridges this gap. The selected receptor binds spermine with a dissociation constant of 22 nM, sufficient to remove it from its natural host DNA and reverse some of the biological effects of spermine on the nucleic acid. In low concentrations, spermine induces the formation of left-handed DNA, but upon addition of our receptor, the DNA reverts back to its right-handed form. NMR studies and computer simulations suggest that the spermine complex has the form of a pseudo-rotaxane. The spermine receptor is a promising lead for the development of therapeutics or molecular probes for elucidating spermine’s role in cell biology.

Vieille-Toulouse (Haute-Garonne) : des vestiges de préparations culinaires ?

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Two-photon intravital imaging of lungs during anthrax infection reveals long-lasting macrophage-dendritic cell contacts.

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International audience: Dynamics of the lung immune system at a microscopic level are largely unknown because of inefficient methods to rid chest motion during image acquisition. In this study, we developed an improved intravital method for two-photon lung imaging uniquely based on a posteriori parenchymal tissue motion correction. We took advantage of the alveolar collagen pattern given by second harmonic generation signal as a reference for frame registration. We describe here for the first time a detailed dynamic account of two major lung immune cell populations, alveolar macrophages and CD11b-positive dendritic cells, during homeostasis and infection by spores of Bacillus anthracis, the agent of anthrax. We show that after alveolar macrophages capture spores, CD11b-positive dendritic cells come in prolonged contact with infected macrophages. Dendritic cells are known to carry spores to the draining lymph nodes and elicit the immune response in pulmonary anthrax. The intimate and long-lasting contacts between these two lines of defense may therefore coordinate immune responses in the lung through an immunological synapse-like process

La pompe à efflux MexEF-OprN de pseudomonas aeruginosa exporte la molécule de communication intercellulaires 4-hydroxy-2-heptyliquinoline (HHQ)

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La bactĂ©rie pathogĂšne opportuniste Pseudomonas aeruginosa est la cause d’infections chroniques chez les personnes atteintes de la fibrose kystique (FK). De plus, P. aeruginosa est naturellement trĂšs rĂ©sistante aux antimicrobiens, ce qui rend l’antibiothĂ©rapie souvent inefficace. Les pompes Ă  efflux sont des dĂ©terminants majeurs de la rĂ©sistance aux antibiotiques chez cette bactĂ©rie. Elles permettent la rĂ©sistance simultanĂ©e Ă  diffĂ©rentes classes d'antibiotiques. La pompe Ă  efflux MexEF-OprN promeut la rĂ©sistance au chloramphĂ©nicol, au trimĂ©thoprime, au triclosan et aux fluoroquinolones. L’expression continue de l’opĂ©ron mexEF-oprN est observĂ©e chez des mutants de mexS, gĂšne dont la fonction est inconnue. Une mutation dans mexS affecte aussi les mĂ©canismes de quorum sensing (QS), c’est-Ă -dire de communication intercellulaire. Le QS contrĂŽle l’expression de facteurs de virulence et la formation de biofilms, observĂ©es dans les voies respiratoires des personnes atteintes de FK. Le QS est contrĂŽlĂ© par des rĂ©gulateurs transcriptionnels qui, pour ĂȘtre actifs, doivent ĂȘtre couplĂ©s Ă  de petites molĂ©cules signales nommĂ©es auto-inducteurs. Alors que la population bactĂ©rienne se densifie, les auto-inducteurs s’accumulent dans le milieu extracellulaire jusqu’à atteindre une concentration-seuil, Ă  laquelle le "quorum" est atteint. MvfR est un rĂ©gulateur du QS et contrĂŽle l’expression de plusieurs gĂšnes importants pour la virulence, dont ceux de l’opĂ©ron pqsABCDE, impliquĂ©s dans la biosynthĂšse des 4-hydroxy-2-alkylquinolines (HAQ). Un auto-inducteur associĂ© Ă  MvfR est le 3,4-dihydroxy-2- heptylquinoline (PQS; Pseudomonas Quinolone Signal). L’enzyme PqsH est responsable de la synthĂšse du PQS et utilise un HAQ, le 4-hydroxy-2-heptylquinoline (HHQ), comme substrat. Étrangement, la quantitĂ© de PQS produit par les mutants mexS est substantiellement rĂ©duite. Afin de mieux comprendre l’influence de cette mutation sur les HAQ, nous avons quantifiĂ© leurs concentrations par LC-MS/MS chez la souche parentale PA14 et son mutant isogĂ©nique mexS. Cette expĂ©rience fut effectuĂ©e en absence ou prĂ©sence d’inhibiteurs des pompes Ă  efflux. De plus, le niveau d’expression de plusieurs gĂšnes du QS fĂ»t dĂ©terminĂ© grĂące Ă  des fusions transcriptionnelles entre les rĂ©gions promotrices des gĂšnes Ă  l’étude et le gĂšne rapporteur lacZ. Mis ensemble, nos rĂ©sultats dĂ©montrent que c’est l’exportation du HHQ par MexEF-OprN qui cause le dĂ©ficit en PQS. Puisque des souches qui surexpriment mexEF-oprN sont dĂ©fectueuses pour le QS et moins virulentes, il serait intĂ©ressant d’identifier de nouvelles molĂ©cules Ă  potentiel thĂ©rapeutique qui permettrait de moduler l’activitĂ© de la pompe MexEF-OprN. Cela pourrait faciliter le traitement des infections pulmonaires Ă  P. aeruginosa

Drosophila melanogaster as a Model Host for the Burkholderia cepacia Complex

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Colonization with bacterial species from the Burkholderia cepacia complex (Bcc) is associated with fast health decline among individuals with cystic fibrosis. In order to investigate the virulence of the Bcc, several alternative infection models have been developed. To this end, the fruit fly is increasingly used as surrogate host, and its validity to enhance our understanding of host-pathogen relationships has been demonstrated with a variety of microorganisms. Moreover, its relevance as a suitable alternative to mammalian hosts has been confirmed with vertebrate organisms.The aim of this study was to establish Drosophila melanogaster as a surrogate host for species from the Bcc. While the feeding method proved unsuccessful at killing the flies, the pricking technique did generate mortality within the populations. Results obtained with the fruit fly model are comparable with results obtained using mammalian infection models. Furthermore, validity of the Drosophila infection model was confirmed with B. cenocepacia K56-2 mutants known to be less virulent in murine hosts or in other alternative models. Competitive index (CI) analyses were also performed using the fruit fly as host. Results of CI experiments agree with those obtained with mammalian models.We conclude that Drosophila is a useful alternative infection model for Bcc and that fly pricking assays and competition indices are two complementary methods for virulence testing. Moreover, CI results indicate that this method is more sensitive than mortality tests
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