Exploration fonctionnelle de la réponse au stress chez des micro-organismes d'intérêt technologique : dynamique de la réponse membranaire suite au stress éthanolique chez Saccharomyces cerevisiae

The study of membrane response induced by ethanol stress in Saccharomyces cerevisiae aims to understand mechanisms involved in the survival of eukaryotic cells submitted to high ethanol concentrations. The cell membrane by its position between the intra- and extracellular environment is the first target of ethanolic perturbations. Experiments performed in this study aimed to characterize the maintain of the functional integrity of the membrane in relation to the sterol composition in the yeast S. cerevisiae submitted to different types of ethanolic disturbances: increasing concentrations of ethanol in the growth medium; ethanolic shocks of increasing magnitude; shock 20% ethanol for 15 minutes and then return in a medium without ethanol ("pulse" 20% ethanol)). Our results demonstrate the importance of ergosterol in maintaining membrane integrity and also support the hypothesis of the vector role of ethanol in cell oxidation, whose effectiveness is dependent on the nature of sterols at the membrane level. In addition, our results analyzing the kinetics of transcription of genes involved in oxidative stress response suggest an increased formation of reactive oxygen species (ROS) induced by ethanol in the Δerg6 mutant, affected in the biosynthetic pathway of ergosterol.L’étude de la réponse membranaire suite au stress éthanolique chez Saccharomyces cerevisiae vise à comprendre les mécanismes impliqués dans la survie des eucaryotes aux concentrations en éthanol élevées. La membrane cellulaire, par sa position entre l’environnement intra et extracellulaire, est la première cible des perturbations éthanoliques. Les expérimentations effectuées dans cette étude visent à caractériser le maintien de l’intégrité fonctionnelle en relation avec la composition en stérols membranaires chez la levure S. cerevisiae soumise à différents types de perturbations éthanoliques (augmentation de la concentrations en éthanol dans le milieu de croissance, chocs éthanoliques d’amplitude croissante et suivi au cours du temps ; choc à 20% pendant 15 minutes puis suivi au cours du temps après retour dans un milieu sans éthanol (« pulse » 20% d’éthanol)). Les résultats obtenus démontrent l’importance de l’ergostérol dans le maintien de l’intégrité membranaire et supportent également l’hypothèse du rôle « vecteur » de l’éthanol vis à vis d’une oxydation, dont l’efficacité serait dépendante de la nature des stérols présents au niveau membranaire. Les premiers résultats analysant la cinétique de transcription de gènes impliqués dans la réponse au stress oxydatif suggèrent une formation plus importante de formes réactives de l’oxygène (ROS), induite par le choc éthanol chez un mutant Δerg6, affecté dans la voie de biosynthèse de l’ergostérol

Evaluating the effect of self-interference on the performance of full-duplex two-way relaying communication with energy harvesting

In this paper, we study the throughput and outage probability (OP) of two-way relaying (TWR) communication system with energy harvesting (EH). The system model consists two source nodes and a relay node which operates in full-duplex (FD) mode. The effect of self-interference (SI) due to the FD operation on the system performance is evaluated for both one-way full duplex (OWFD) and two-way full duplex (TWFD) diagrams where the amplify-and-forward (AF) relay node collects energy harvesting with the time switching (TS) scheme. We first propose an individual OP expression for each specific source. Then, we derive the exact closed-form overall OP expression for the OWFD diagram. For the TWFD diagram, we propose an approximate closed-form expression for the overall OP. The overall OP comparison among hybrid systems (Two-Way Half-Duplex (TWHD), OWFD, TWFD) are also discussed.  Finally, the numerical/simulated results are presented for Rayleigh fading channels to demonstrate the correction of the proposed analysis

On The Performance of Underlay Relay Cognitive Networks

The bit error rate (BER) performance of underlay relay cognitive networks in the presence of Rayleigh fading is thoroughly analyzed in this paper. New exact and asymptotic analytic expressions under consideration of both interference power constraint and maximum transmit power constraint are derived in closed-form and are extensively corroborated by Monte-Carlo simulations. These expressions facilitate in evaluating effectively the network performance behaviour in key operation parameters as well as in optimizing system parameters. A multitude of analytical results expose that underlay relay cognitive networks experience the performance saturation phenomena while their performance considerably depends on the number of hops for the linear network model. Additionally, optimum relay position is significantly dependent of maximum transmit power, maximum interference power, and licensee location. Moreover, the appropriate order of locating unlicensees with different maximum transmit power levels can dramatically improve the network performance

Biosynthesis of silver nanoparticles using curcumin against the bovine mastitis bacteria

Bovine mastitis is the most common disease and has greatly affected economies around the world. This study aimed to determine the antibacterial ability of bovine mastitis by curcumin - silver nanoparticles (Cur-AgNPs). The study included experiments on presenting a new process for synthesizing silver nanoparticles using curcumin from fresh turmeric as a reducing agent and stabilizer. UV visible spectroscopy of the samples revealed the localized surface plasmon resonance absorbance of the dispersion of silver nanoparticles at 430 nm. The prepared Cur-AgNPs has a spherical shape with an average size of 30 nm and a size distribution of 15–47 nm. FT-IR (Fourier transform infrared spectroscopy) measurements of the samples showed that silver nanopartilces has been encapsulated well by curcumin. Cur-AgNPs with a concentration of 50-200 μg/mL has very effect to Staphylococcus aureus, Pseudomonas aeruginosa causing bovine mastitis in vitro. The maximum inhibition zone formed was 15 ± 0.85 mm for Staphylococcus aureus and 14 ± 0.56 mm for Pseudomonas aeruginosa. Plant materials mediating for the synthesis of silver nanoparticles have relatively rapid, less expensive, and widespread applications for antimicrobial therapy in the livestock sector

Comparison of dispersion characteristics of hollow-core photonic crystal fibers filled with aromatic compounds

In this paper, hollow-core photonic crystal fibers (PCFs) infiltrated with benzene and nitrobenzene are designed and investigated. Their dispersion characteristics are numerically simulated. The results show that using the aromatic-compounds-filled hollow core of PCFs makes dispersion curves flat. In addition, the dispersion curves approach the zero-dispersion line closer than previously published dispersion curves of PCFs with toluene, thus significantly improving the supercontinuum generation to create the ultra-flat spectrum expansion

Network Coding with Multimedia Transmission and Cognitive Networking: An Implementation based on Software-Defined Radio

Network coding (NC) is considered a breakthrough to improve throughput, robustness, and security of wireless networks. Although the theoretical aspects of NC have been extensively investigated, there have been only few experiments with pure NC schematics. This paper presents an implementation of NC under a two-way relay model and extends it to two\ua0non-straightforward scenarios: (i) multimedia transmission with layered coding and multiple-description coding, and (ii) cognitive radio with Vandermonde frequency division multiplexing (VFDM). The implementation is in real time and based on software-defined radio (SDR). The experimental results show that, by combining NC and source coding, we can control the quality of the received multimedia content in an on-demand manner. Whereas in the VFDM-based cognitive radio, the quality of the received content in the primary receiver is low (due to imperfect channel estimation) yet retrievable. Our implementation results serve as a proof for the practicability of network coding in relevant applications

Network Coding with Multimedia Transmission and Cognitive Networking: An Implementation based on Software-Defined Radio

Network coding (NC) is considered a breakthrough to improve throughput, robustness, and security of wireless networks. Although the theoretical aspects of NC have been extensively investigated, there have been only few experiments with pure NC schematics. This paper presents an implementation of NC under a two-way relay model and extends it to two non-straightforward scenarios: (i) multimedia transmission with layered coding and multiple-description coding, and (ii) cognitive radio with Vandermonde frequency division multiplexing (VFDM). The implementation is in real time and based on software-defined radio (SDR). The experimental results show that, by combining NC and source coding, we can control the quality of the received multimedia content in an on-demand manner. Whereas in the VFDM-based cognitive radio, the quality of the received content in the primary receiver is low (due to imperfect channel estimation) yet retrievable. Our implementation results serve as a proof for the practicability of network coding in relevant applications

Host Transcription Profile in Nasal Epithelium and Whole Blood of Hospitalized Children Under 2 Years of Age With Respiratory Syncytial Virus Infection.

BACKGROUND: Most insights into the cascade of immune events after acute respiratory syncytial virus (RSV) infection have been obtained from animal experiments or in vitro models. METHODS: In this study, we investigated host gene expression profiles in nasopharyngeal (NP) swabs and whole blood samples during natural RSV and rhinovirus (hRV) infection (acute versus early recovery phase) in 83 hospitalized patients <2 years old with lower respiratory tract infections. RESULTS: Respiratory syncytial virus infection induced strong and persistent innate immune responses including interferon signaling and pathways related to chemokine/cytokine signaling in both compartments. Interferon-α/β, NOTCH1 signaling pathways and potential biomarkers HIST1H4E, IL7R, ISG15 in NP samples, or BCL6, HIST2H2AC, CCNA1 in blood are leading pathways and hub genes that were associated with both RSV load and severity. The observed RSV-induced gene expression patterns did not differ significantly in NP swab and blood specimens. In contrast, hRV infection did not as strongly induce expression of innate immunity pathways, and significant differences were observed between NP swab and blood specimens. CONCLUSIONS: We conclude that RSV induced strong and persistent innate immune responses and that RSV severity may be related to development of T follicular helper cells and antiviral inflammatory sequelae derived from high activation of BCL6

The Association of Cytokines with Severe Dengue in Children

Background: Dengue virus infection is a major public health problem. A hypothesis put forward for severe dengue is the cytokine storm, a sudden increase in cytokines that induces vascular permeability. Previous studies and our recent meta-analysis showed that IL-6, IL-8, IFNγ, TNFα, VEGF-A and VCAM-1 are associated with dengue shock syndrome. Therefore, in this study we aim to validate the association of these cytokines with severe dengue. Methods & Findings: In a hospital based-case control study in Vietnam, children with dengue fever, other febrile illness and healthy controls were recruited. Dengue virus infection was confirmed by several diagnostic tests. Multiplex immunoassay using Luminex technology was used to measure cytokines simultaneously. A positive association with dengue shock syndrome was found for VCAM-1, whereas a negative association was found for IFNγ. Furthermore, multivariate logistic analysis also showed that VCAM-1 and IFNγ were independently correlated with dengue shock syndrome. Conclusion: IFNγ and VCAM-1 were associated with dengue shock syndrome, although their role in the severe dengue pathogenesis remains unclear. Additional studies are required to shed further light on the function of these cytokines in severe dengue