Staphylococcus aureus virulence and metabolism are dramatically affected by Lactococcus lactis in cheese matrix

International audienceIn complex environments such as cheeses, the lack of relevant information on the physiology and virulence expression of pathogenic bacteria and the impact of endogenous microbiota has hindered progress in risk assessment and control. Here, we investigated the behaviour of Staphylococcus aureus, a major foodborne pathogen, in a cheese matrix, either alone or in the presence of Lactococcus lactis, as a dominant species of cheese ecosystems. The dynamics of S. aureus was explored in situ by coupling a microbiological and, for the first time, a transcriptomic approach. Lactococcus lactis affected the carbohydrate and nitrogen metabolisms and the stress response of S. aureus by acidifying, proteolysing and decreasing the redox potential of the cheese matrix. Enterotoxin expression was positively or negatively modulated by both L. lactis and the cheese matrix itself, depending on the enterotoxin type. Among the main enterotoxins involved in staphylococcal food poisoning, sea expression was slightly favoured in the presence of L. lactis, whereas a strong repression of sec4 was observed in cheese matrix, even in the absence of L. lactis, and correlated with a reduced saeRS expression. Remarkably, the agr system was downregulated by the presence of L. lactis, in part because of the decrease in pH. This study highlights the intimate link between environment, metabolism and virulence, as illustrated by the influence of the cheese matrix context, including the presence of L. lactis, on two major virulence regulators, the agr system and saeRS

Exercise therapy for chronic symptomatic peripheral artery disease:A clinical consensus document of the European Society of Cardiology Working Group on Aorta and Peripheral Vascular Diseases in collaboration with the European Society of Vascular Medicine and the European Society for Vascular Surgery

All guidelines worldwide strongly recommend exercise as a pillar in the management of patients affected by lower extremity peripheral artery disease (PAD). Exercise therapy in this setting presents different modalities, and a structured programme provides optimal results. This clinical consensus paper is intended to promote and assist the set up of comprehensive exercise programmes and best advice for patients with symptomatic chronic PAD. Different exercise training protocols specific for patients with PAD are presented. Data on patient assessment and outcome measures are described based on the current best evidence. The document ends by highlighting supervised exercise programme access disparities across Europe and the evidence gaps requiring further research.</p

Exercise therapy for chronic symptomatic peripheral artery disease

Summary: All guidelines worldwide strongly recommend exercise as a pillar in the management of patients affected by lower extremity peripheral artery disease (PAD). Exercise therapy in this setting presents different modalities, and a structured programme provides optimal results. This clinical consensus paper is intended to promote and assist the set up of comprehensive exercise programmes and best advice for patients with symptomatic chronic PAD. Different exercise training protocols specific for patients with PAD are presented. Data on patient assessment and outcome measures are described based on the current best evidence. The document ends by highlighting supervised exercise programme access disparities across Europe and the evidence gaps requiring further research

Design and planning of a transdisciplinary investigation into farmland pollinators: rationale, co-design, and lessons learned

To provide a complete portrayal of the multiple factors negatively impacting insects in agricultural landscapes it is necessary to assess the concurrent incidence, magnitude, and interactions among multiple stressors over substantial biogeographical scales. Trans-national ecological field investigations with wide-ranging stakeholders typically encounter numerous challenges during the design planning stages, not least that the scientific soundness of a spatially replicated study design must account for the substantial geographic and climatic variation among distant sites. ‘PoshBee’ (Pan-European assessment, monitoring, and mitigation of Stressors on the Health of Bees) is a multi-partner transdisciplinary agroecological project established to investigate the suite of stressors typically encountered by pollinating insects in European agricultural landscapes. To do this, PoshBee established a network of 128 study sites across eight European countries and collected over 50 measurements and samples relating to the nutritional, toxicological, pathogenic, and landscape components of the bees’ environment. This paper describes the development process, rationale, and end-result of each aspect of the of the PoshBee field investigation. We describe the main issues and challenges encountered during the design stages and highlight a number of actions or processes that may benefit other multi-partner research consortia planning similar large-scale studies. It was soon identified that in a multi-component study design process, the development of interaction and communication networks involving all collaborators and stakeholders requires considerable time and resources. It was also necessary at each planning stage to be mindful of the needs and objectives of all stakeholders and partners, and further challenges inevitably arose when practical limitations, such as time restrictions and labour constraints, were superimposed upon prototype study designs. To promote clarity for all stakeholders, for each sub-component of the study, there should be a clear record of the rationale and reasoning that outlines how the final design transpired, what compromises were made, and how the requirements of different stakeholders were accomplished. Ultimately, multi-national agroecological field studies such as PoshBee benefit greatly from the involvement of diverse stakeholders and partners, ranging from field ecologists, project managers, policy legislators, mathematical modelers, and farmer organisations. While the execution of the study highlighted the advantages and benefits of large-scale transdisciplinary projects, the long planning period emphasized the need to formally describe a design framework that could facilitate the design process of future multi-partner collaborations

The Effect of the Madden–Julian Oscillation on the North Atlantic Oscillation Using Idealized Numerical Experiments

International audienceThe aim of the paper is to investigate the influence of the Madden-Julian oscillation (MJO) on the North Atlantic Oscillation (NAO) using a quasigeostrophic model on the sphere. A simplified forcing based on potential vorticity anomalies in the tropics is used to mimic the MJO. The idealized nature of our setup allows us to determine the distinct roles played by stationary and synoptic waves. This is done by means of several series of almost 10 000 short runs of 30 days. Ensemble averages and a streamfunction budget analysis are used to study the modifications of the flow induced by the MJO. We find that a stationary Rossby wave is excited in the tropics during MJO phase 3. The western part of the Pacific jet is displaced poleward, which modifies the transient eddy activity in that basin. These changes create a ridge south of Alaska, which favors equatorward propagation of synoptic waves and larger poleward eddy momentum fluxes from the eastern Pacific toward the Atlantic, increasing the frequency of occurrence of the positive NAO events. The situation is essentially reversed following phase 6 of the MJO and conducive to the negative phase of the NAO. For a realistic MJO forcing amplitude, we find increases in both NAO phases to be around 30%, in reasonable agreement with the observations given the model simplicity. Finally, we present a series of experiments to assess the relative importance of linear versus nonlinear effects

Linking warm Arctic winters, Rossby waves, and cold spells: an idealized numerical study

International audienceThe changes of midlatitude Rossby waves and cold extreme temperature events (cold spells) during warm Arctic winters are analyzed using a dry three-level quasigeostrophic model on the sphere. Two long-term simulations are compared: the first run has the observed wintertime climatology, while the second run includes the composite of the global anomalies associated with the six hottest Arctic winters. A spectral analysis shows a large increase in wave amplitude for near-zero and westward phase speeds and a more moderate decrease for high eastward phase speeds. The increase in low-frequency variability (periods greater than a week) associated with the power shift to slower waves is largely responsible for an increase in midlatitude long-lasting cold spells. In midlatitude regions, in the presence of a mean warming, that increase in low-frequency variance compensates the increase of the mean temperature, resulting at places in a frequency of cold spells that remains by and large unaltered. In presence of mean cooling, both the increase in variance and the decrease in the mean temperature participate in an increased frequency of cold spells. Sensitivity experiments show that the power shift to slower waves is mainly due to the tropical anomalies that developed during those particular winters and less importantly to changes in the background flow at higher latitudes associated with the Arctic amplification pattern

Touch-Based Interfaces for Interacting with 3D Content in Public Exhibitions

International audienceA museum exhibition on the Lascaux caves provides the opportunity to experiment with touch-based interfaces manipulating 3D virtual objects. The researchers targeted three tasks: observing rare objects, reassembling object fragments, and reproducing artwork

Etude des interactions entre staphylococcus aureus et lactococcus lactis en matrice fromagère.

Staphylococcus aureus est une bactérie pathogène, cause majeure d’intoxication alimentaire, en particulier dans le lait et les produits laitiers. Dans les fromages, S. aureus est en interaction avec des bactéries lactiques, dont Lactococcus lactis, capables de les inhiber. Au cours du procédé fromager, ces microorganismes sont sujets à des conditions environnementales particulières qui diffèrent largement des conditions de laboratoire. Ainsi, l’étude in situ de l’interaction entre S. aureus et L. lactis en matrice fromagère est une approche qui nous permet de caractériser les facteurs et les stress qui influencent le potentiel antagoniste de L. lactis vis à vis de S. aureus en conditions technologiques. L’effet de L. lactis sur le profil transcriptomique de S. aureus en culture mixte en matrice fromagère a été étudiée sur une cinétique de sept jours. Le profil d’expression de S. aureus en culture pure a été comparé au transcriptome de S. aureus en culture mixte afin de déterminer l’impact de L. lactis. L. lactis provoque une légère inhibition de la croissance de S. aureus et génère un stress acide. L’expression de la virulence est atténuée avec, en particulier, une absence d’induction de deux régulateurs majeurs de la virulence, RNAIII et sarA. Le stress acide n’est que partiellement responsable de cette inhibition. L’identification des mécanismes à l’origine du potentiel antagoniste de L. lactis nous permettra de mieux contrôler les contaminations à S. aureus et de proposer de nouveaux critères pour la sélection des ferments lactique

Atténuation de la virulence de staphylococcus aureus en matrice fromagère et en interaction avec lactococcus lactis

Staphylococcus aureus, bactérie pathogène majeure, est une des principales causes de toxi-infections alimentaires collectives (TIAC) en France en raison de la production d’entérotoxines par certaines souches. Les produits laitiers, en particulier les fromages, sont particulièrement incriminés dans les TIACs à S. aureus. Si la physiologie et la virulence de S. aureus sont largement étudiées en condition de laboratoire, elles sont assez peu documentées dans le contexte fromage. Le fromage constitue un écosystème dynamique et complexe dans lequel S. aureus est soumis à des conditions physico-chimiques changeantes et particulières : divers stress (température, milieu nutritionnel pauvre en acides aminés libres), croissance en milieu liquide puis matrice solide. De plus, S. aureus se trouve en interaction avec d’autres flores telles que les bactéries lactiques (BL), qui, outre leur rôle dans la fabrication du fromage, sont capables de les inhiber.Notre objectif est d’étudier la dynamique d’expression de S. aureus in situ, en matrice fromagère, en culture pure ou en présence de Lactococcus lactis, BL modèle. Afin de mieux comprendre les mécanismes impliqués dans les interactions de S. aureus avec la matrice et avec L. lactis, une puce dédiée spécifique de S. aureus a été utilisée, permettant de suivre l’expression des gènes impliqués dans la virulence, l’adaptation aux stress, le transport de peptides, ainsi que des gènes appartenant au métabolisme central et à la machinerie cellulaire. Le profil d’expression de S. aureus en culture pure en matrice fromagère a été comparé au transcriptome de S. aureus cultivé en mode planctonique en milieu chimiquement défini (MCD) afin de caractériser l’effet de la matrice. Puis, il a été comparé au profil d’expression de S. aureus en culture mixte en matrice fromagère afin de déterminer l’impact de L. lactis. Seul en matrice fromagère, S. aureus reste métaboliquement actif pendant 7 jours et subit un stress modéré. De manière surprenante, l’expression de plusieurs facteurs de virulence sécrétés et notamment des entérotoxines est réprimée par rapport à une croissance en MCD. La présence de L. lactis provoque une légère inhibition de la croissance de S. aureus (1 log d’inhibition à 7 jours) et génère un stress acide. L’atténuation de la virulence est renforcée avec, en particulier, une absence d’induction de deux régulateurs majeurs de la virulence de S. aureus, RNAIII (effecteur du système agr) et sarA. Le stress acide n’est que partiellement responsable de cette inhibition de la virulence.Cette approche transcriptomique in situ, dans des conditions proches des conditions technologiques renforce l’idée d’une relation forte entre environnement, métabolisme et virulence. Une atténuation de plusieurs facteurs de virulence a été observée, imputable à la fois à la matrice et à L. lactis. L’identification des mécanismes à l’origine du potentiel antagoniste de L. lactis sur S. aureus, mais également de la matrice, nous permettra de mieux contrôler les contaminations à S. aureus et de proposer de nouveaux critères pour la sélection des ferments lactique

Etude des interactions entre staphylococcus aureus et lactococcus lactis en matrice fromagère.

Staphylococcus aureus est une bactérie pathogène, cause majeure d’intoxication alimentaire, en particulier dans le lait et les produits laitiers. Dans les fromages, S. aureus est en interaction avec des bactéries lactiques, dont Lactococcus lactis, capables de les inhiber. Au cours du procédé fromager, ces microorganismes sont sujets à des conditions environnementales particulières qui diffèrent largement des conditions de laboratoire. Ainsi, l’étude in situ de l’interaction entre S. aureus et L. lactis en matrice fromagère est une approche qui nous permet de caractériser les facteurs et les stress qui influencent le potentiel antagoniste de L. lactis vis à vis de S. aureus en conditions technologiques. L’effet de L. lactis sur le profil transcriptomique de S. aureus en culture mixte en matrice fromagère a été étudiée sur une cinétique de sept jours. Le profil d’expression de S. aureus en culture pure a été comparé au transcriptome de S. aureus en culture mixte afin de déterminer l’impact de L. lactis. L. lactis provoque une légère inhibition de la croissance de S. aureus et génère un stress acide. L’expression de la virulence est atténuée avec, en particulier, une absence d’induction de deux régulateurs majeurs de la virulence, RNAIII et sarA. Le stress acide n’est que partiellement responsable de cette inhibition. L’identification des mécanismes à l’origine du potentiel antagoniste de L. lactis nous permettra de mieux contrôler les contaminations à S. aureus et de proposer de nouveaux critères pour la sélection des ferments lactique