Sulfamethoxazole and isoproturon degradation and detoxification by a laccase-mediator system: Influence of treatment conditions and mechanistic aspects

The potential of laccase-mediator systems (LMS) for the removal and detoxification of two wastewater micropollutants, the antibiotic sulfamethoxazole (SMX) and the herbicide isoproturon (IPN), was assessed. The influence of various parameters on micropollutant oxidation rates, such as pH, mediator, enzyme and pollutant concentrations, was investigated with three mediators: 2,2'′-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS), syringaldehyde (SA) and acetosyringone (AS). Both pollutants were completely transformed within a few hours in presence of laccase and ABTS, as well as, for SMX, in presence of AS or SA. The three mediators were consumed during the reaction (no catalytic reactions observed), at a ratio mediator/pollutant between 1.1 and 16  mol/mol. Faster oxidation kinetics were observed at lower pH values, but also higher mediator/pollutant ratios were required. Several transformation products were formed, including cross-coupled products. Product mixtures were always less toxic to algae than untreated pollutants. Finally, a kinetic model that could explain the experimental observations was established. Based on the findings in this study LMS appears to be a promising option to treat concentrated and potentially toxic industrial effluents

Loss-of-Function Mutations in LRRC6, a Gene Essential for Proper Axonemal Assembly of Inner and Outer Dynein Arms, Cause Primary Ciliary Dyskinesia

Primary ciliary dyskinesia (PCD) is a group of autosomal-recessive disorders resulting from cilia and sperm-flagella defects, which lead to respiratory infections and male infertility. Most implicated genes encode structural proteins that participate in the composition of axonemal components, such as dynein arms (DAs), that are essential for ciliary and flagellar movements; they explain the pathology in fewer than half of the affected individuals. We undertook this study to further understand the pathogenesis of PCD due to the absence of both DAs. We identified, via homozygosity mapping, an early frameshift in LRRC6, a gene that encodes a leucine-rich-repeat (LRR)-containing protein. Subsequent analyses of this gene mainly expressed in testis and respiratory cells identified biallelic mutations in several independent individuals. The situs inversus observed in two of them supports a key role for LRRC6 in embryonic nodal cilia. Study of native LRRC6 in airway epithelial cells revealed that it localizes to the cytoplasm and within cilia, whereas it is absent from cells with loss-of-function mutations, in which DA protein markers are also missing. These results are consistent with the transmission-electron-microscopy data showing the absence of both DAs in cilia or flagella from individuals with LRRC6 mutations. In spite of structural and functional similarities between LRRC6 and DNAAF1, another LRR-containing protein involved in the same PCD phenotype, the two proteins are not redundant. The evolutionarily conserved LRRC6, therefore, emerges as an additional player in DA assembly, a process that is essential for proper axoneme building and that appears to be much more complex than was previously thought

Mettre en œuvre un service de questions-réponses en ligne

En quelques années, les bibliothèques françaises ont développé des services de questions-réponses en ligne. Beaucoup d'établissements en sont encore à la phase de réflexion, d'autres démarrent, des réseaux s'élaborent. Dans le contexte actuel du repérage, de la sélection et de la validation de l'information pléthorique disponible sur Internet, les services de questions-réponses en ligne ont un rôle primordial à jouer. En effet, ils valorisent l'offre des bibliothèques dans le contexte du développement des services aux publics et des services à distance. Leur mise en place interroge le professionnel sous de multiples facettes : organisation du travail, politique de services, choix des outils… Ces différents aspects sont abordés, s'appuyant sur des expériences françaises et étrangères, qu'elles soient locales, coopératives et/ou collaboratives. Un éventail d'offres existe aujourd'hui, selon les objectifs, les besoins, les publics, les moyens mis à disposition et les technologies choisies. Le plan s'articule autour de quatre parties pragmatiques et opératoires : construire le projet, développer un savoir-répondre, organiser et travailler au sein d'une équipe et, enfin, adapter le service à l'environnement et à la nature de ses publics. Cet ouvrage collectif, coordonné par Claire Nguyen, se veut un guide utile à tous les professionnels qui veulent créer, maintenir ou faire évoluer un service de questions-réponses à distance

Brucella abortus Induces the Premature Death of Human Neutrophils through the Action of Its Lipopolysaccharide

Most bacterial infections induce the activation of polymorphonuclear neutrophils (PMNs), enhance their microbicidal function, and promote the survival of these leukocytes for protracted periods of time. Brucella abortus is a stealthy pathogen that evades innate immunity, barely activates PMNs, and resists the killing mechanisms of these phagocytes. Intriguing clinical signs observed during brucellosis are the low numbers of Brucella infected PMNs in the target organs and neutropenia in a proportion of the patients; features that deserve further attention. Here we demonstrate that B. abortus prematurely kills human PMNs in a dose-dependent and cell-specific manner. Death of PMNs is concomitant with the intracellular Brucella lipopolysaccharide (Br-LPS) release within vacuoles. This molecule and its lipid A reproduce the premature cell death of PMNs, a phenomenon associated to the low production of proinflammatory cytokines. Blocking of CD14 but not TLR4 prevents the Br-LPS-induced cell death. The PMNs cell death departs from necrosis, NETosis and classical apoptosis. The mechanism of PMN cell death is linked to the activation of NADPH-oxidase and a modest but steadily increase of ROS mediators. These effectors generate DNA damage, recruitments of check point kinase 1, caspases 5 and to minor extent of caspase 4, RIP1 and Ca++ release. The production of IL-1β by PMNs was barely stimulated by B. abortus infection or Br-LPS treatment. Likewise, inhibition of caspase 1 did not hamper the Br-LPS induced PMN cell death, suggesting that the inflammasome pathway was not involved. Although activation of caspases 8 and 9 was observed, they did not seem to participate in the initial triggering mechanisms, since inhibition of these caspases scarcely blocked PMN cell death. These findings suggest a mechanism for neutropenia in chronic brucellosis and reveal a novel Brucella-host cross-talk through which B. abortus is able to hinder the innate function of PMN.Fondo Especial de la Educación Superior/[0500-13]/FEES/Costa RicaFondo Especial de la Educación Superior/[0504-13]/FEES/Costa RicaFondo Especial de la Educación Superior/[0505-13]/FEES/Costa RicaFondo Especial de la Educación Superior/[0248-13]/FEES/Costa RicaUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias de la Salud::Centro de Investigación en Enfermedades Tropicales (CIET)UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias de la Salud::Instituto Clodomiro Picado (ICP)UCR::Vicerrectoría de Docencia::Salud::Facultad de Microbiologí

Evaluation de la Self Interaction Chromatography comme méthode prédictive de l agrégation des protéines en solution

BORDEAUX2-BU Santé (330632101) / SudocSudocFranceF

Modelling the effect of fluctuating herbicide concentrations on algae growth

Herbicide concentrations fluctuate widely in watercourses after crop applications and rain events. The level of concentrations in pulses can exceed the water chronic quality criteria. In the present study, we proposed modelling the effects of successive pulse exposure on algae. The deterministic model proposed is based on two parameters: (i) the typical growth rate of the algae, obtained by monitoring growth rates of several successive batch cultures in growth media, characterizing both the growth of the control and during the recovery periods; (ii) the growth rate of the algae exposed to pulses, determined from a doseresponse curve obtained with a standard toxicity test. We focused on the herbicide isoproturon and on the freshwater alga Scenedesmus vacuolatus, and we validated the model prediction based on effect measured during five sequential pulse exposures in laboratory. The comparison between the laboratory and the modelled effects illustrated that the results yielded were consistent, making the model suitable for effect prediction of the herbicide photosystem II inhibitor isoproturon on the alga S. vacuolatus. More generally, modelling showed that both pulse duration and level of concentration play a crucial role. The application of the model to a real case demonstrated that both the highest peaks and the low peaks with a long duration affect principally the cell density inhibition of the alga S. vacuolatus. It is therefore essential to detect these characteristic pulses when monitoring of herbicide concentrations are conducted in rivers. (C) 2014 Elsevier Inc. All rights reserved