Salmonella enterica Flagellin Is Recognized via FLS2 and Activates PAMP-Triggered Immunity in Arabidopsis thaliana

Infections with Salmonella enterica belong to the most prominent causes of food poisoning and infected fruits and vegetables represent important vectors for salmonellosis. Recent evidence indicates that plants recognize S. enterica and raise defense responses. Nonetheless, the molecular mechanisms controlling the interaction of S. enterica with plants are still largely unclear. Here, we show that flagellin from S. enterica represents a prominent pathogenassociated molecular pattern （PAMP） in Arabidopsis thaliana, which induces PAMP-triggered immunity （PTI） via the recognition of the fig22 domain by the receptor kinase FLS2. The Arabidopsis fls2 mutant shows reduced though not abolished PTI activation, indicating that plants rely also on recognition of other S. enterica PAMPs. Interestingly, the S. enterica type III secretion system （T3SS） mutant prgH- induced stronger defense gene expression than wild-type bacteria in Arabidopsis, suggesting that T3SS effectors are involved in defense suppression. Furthermore, we observe that S. enterica strains show variation in the fig22 epitope, which results in proteins with reduced PTI-inducing activity. Altogether, these results show that S. enterica activates PTI in Arabidopsis and suggest that, in order to accomplish plant colonization, S. enterica evolved strategies to avoid or suppress PTI.     

Matrix Conditions and KLF2-Dependent Induction of Heme Oxygenase-1 Modulate Inhibition of HCV Replication by Fluvastatin

Background & Aims

HMG-CoA-reductase-inhibitors (statins) have been shown to interfere with HCV replication in vitro. We investigated the mechanism, requirements and contribution of heme oxygenase-1(HO-1)-induction by statins to interference with HCV replication.

Methods

HO-1-induction by fluva-, simva-, rosuva-, atorva- or pravastatin was correlated to HCV replication, using non-infectious replicon systems as well as the infectious cell culture system. The mechanism of HO-1-induction by statins as well as its relevance for interference with HCV replication was investigated using transient or permanent knockdown cell lines. Polyacrylamide(PAA) gels of different density degrees or the Rho-kinase-inhibitor Hydroxyfasudil were used in order to mimic matrix conditions corresponding to normal versus fibrotic liver tissue.

Results

All statins used, except pravastatin, decreased HCV replication and induced HO-1 expression, as well as interferon response in vitro. HO-1-induction was mediated by reduction of Bach1 expression and induction of the Nuclear factor (erythroid-derived 2)-like 2 (NRF2) cofactor Krueppel-like factor 2 (KLF2). Knockdown of KLF2 or HO-1 abrogated effects of statins on HCV replication. HO-1-induction and anti-viral effects of statins were more pronounced under cell culture conditions mimicking advanced stages of liver disease.

Conclusions

Statin-mediated effects on HCV replication seem to require HO-1-induction, which is more pronounced in a microenvironment resembling fibrotic liver tissue. This implicates that certain statins might be especially useful to support HCV therapy of patients at advanced stages of liver disease.     

Ultra‐High Voltage Multijunction Organic Solar Cells for Low‐Power Electronic Applications

Low power electronics are an ideal application for organic photovoltaics (OPV) where a low‐cost OPV device can be integrated directly with a battery to provide a constant power source. We demonstrate ultra‐high voltage small molecule multijunction devices with open circuit voltage (V_OC) values of up to 7V. Optical modelling is employed to aid the optimisation of the complex multi‐layer stacks and ensure current balancing is achieved between sub‐cells, and optimised multijunction devices show power conversion efficiencies of up to 3.4% which is a modest increase over the single junction devices. Sub‐cell donor/acceptor pairs of boron subphthalocyanine chloride (SubPc)/fullerene (C₆₀) and SubPc/Cl₆‐SubPc were selected both for their high V_OC in order to minimise the required number of junctions, but also for their absorption overlap to reduce the spectral dependence of the device performance. As a result, the devices are shown to directly charge a micro‐energy cell type battery under both low illumination intensity white light and monochromatic illumination.     

Diagnostic assessment of mycodiversity in environmental samples by fungal ITS1 rDNA length polymorphism

Biodiversity research rapidly progresses due to the continuous improvement of high-throughput analysis platforms, which facilitate detailed analyses of the composition and architecture of microbial communities in various environmental niches. In the fields of applied forestry and agriculture, microbial communities are also increasingly considered, because they are involved in various kinds of biotic interactions with plants and therefore have high diagnostic value for assessing the health status of plants and soils. While in-depth identification of microbial species in environmental samples is currently achieved by next generation sequencing or microarray techniques, profiling of whole microbial communities can be accomplished via less labor-intensive approaches. We modified the protocol for automated ribosomal intergenic spacer analysis (ARISA) by targeting length polymorphism of the fungal ITS1 rRNA gene for a rapid diagnostic assessment of fungal community composition and surveyed its application spectrum. The approach allowed for spatial and temporal differentiation among fungal assemblages in soil samples and different plant species, and is therefore particularly useful for environmental screening and monitoring projects. Standardized experimental conditions permit the cumulative gathering of data, for instance during long-term projects.     

Multiple testing in candidate gene situations: a comparison of classical, discrete, and resampling-based procedures

In candidate gene association studies, usually several elementary hypotheses are tested simultaneously using one particular set of data. The data normally consist of partly correlated SNP information. Every SNP can be tested for association with the disease, e.g., using the Cochran-Armitage test for trend. To account for the multiplicity of the test situation, different types of multiple testing procedures have been proposed. The question arises whether procedures taking into account the discreteness of the situation show a benefit especially in case of correlated data. We empirically evaluate several different multiple testing procedures via simulation studies using simulated correlated SNP data. We analyze FDR and FWER controlling procedures, special procedures for discrete situations, and the minP-resampling-based procedure. Within the simulation study, we examine a broad range of different gene data scenarios. We show that the main difference in the varying performance of the procedures is due to sample size. In small sample size scenarios,the minP-resampling procedure though controlling the stricter FWER even had more power than the classical FDR controlling procedures. In contrast, FDR controlling procedures led to more rejections in higher sample size scenarios.     

A genome-wide association study of upper aerodigestive tract cancers conducted within the INHANCE consortium

Genome-wide association studies (GWAS) have been successful in identifying common genetic variation involved in susceptibility to etiologically complex disease. We conducted a GWAS to identify common genetic variation involved in susceptibility to upper aero-digestive tract (UADT) cancers. Genome-wide genotyping was carried out using the Illumina HumanHap300 beadchips in 2,091 UADT cancer cases and 3,513 controls from two large European multi-centre UADT cancer studies, as well as 4,821 generic controls. The 19 top-ranked variants were investigated further in an additional 6,514 UADT cancer cases and 7,892 controls of European descent from an additional 13 UADT cancer studies participating in the INHANCE consortium. Five common variants presented evidence for significant association in the combined analysis (p≤5×10⁻⁷). Two novel variants were identified, a 4q21 variant (rs1494961, p = 1×10⁻⁸) located near DNA repair related genes HEL308 and FAM175A (or Abraxas) and a 12q24 variant (rs4767364, p = 2×10⁻⁸) located in an extended linkage disequilibrium region that contains multiple genes including the aldehyde dehydrogenase 2 (ALDH2) gene. Three remaining variants are located in the ADH gene cluster and were identified previously in a candidate gene study involving some of these samples. The association between these three variants and UADT cancers was independently replicated in 5,092 UADT cancer cases and 6,794 controls non-overlapping samples presented here (rs1573496-ADH7, p = 5×10⁻⁸; rs1229984-ADH1B, p = 7×10⁻⁹; and rs698-ADH1C, p = 0.02). These results implicate two variants at 4q21 and 12q24 and further highlight three ADH variants in UADT cancer susceptibility.     

Mutational analysis of photosystem I of Synechocystis sp. PCC 6803: the role of four conserved aromatic residues in the j-helix of PsaB

Photosystem I is the light-driven plastocyanin-ferredoxin oxidoreductase in the photosynthetic electron transfer of cyanobacteria and plants. Two histidyl residues in the symmetric transmembrane helices A-j and B-j provide ligands for the P700 chlorophyll molecules of the reaction center of photosystem I. To determine the role of conserved aromatic residues adjacent to the histidyl molecule in the helix of B-j, we generated six site-directed mutants of the psaB gene in Synechocystis sp. PCC 6803. Three mutant strains with W645C, W643C/A644I and S641C/V642I substitutions could grow photoautotrophically and showed no obvious reduction in the photosystem I activity. Kinetics of P700 re-reduction by plastocyanin remained unaltered in these mutants. In contrast, the strains with H651C/L652M, F649C/G650I and F647C substitutions could not grow under photoautotrophic conditions because those mutants had low photosystem I activity, possibly due to low levels of proteins. A procedure to select spontaneous revertants from the mutants that are incapable to photoautotrophic growth resulted in three revertants that were used in this study. The molecular analysis of the spontaneous revertants suggested that an aromatic residue at F647 and a small residue at G650 may be necessary for maintaining the structural integrity of photosystem I. The (P700⁺ - P700) steady-state absorption difference spectrum of the revertant F647Y has a ∼5 nm narrower peak than the recovered wild-type, suggesting that additional hydroxyl group of this revertant may participate in the interaction with the special pair while the photosystem I complexes of the F649C/G650T and H651Q mutants closely resemble the wild-type spectrum. The results presented here demonstrate that the highly conserved residues W645, W643 and F649 are not critical for maintaining the integrity and in mediating electron transport from plastocyanin to photosystem I. Our data suggest that an aromatic residue is required at position of 647 for structural integrity and/or function of photosystem I.     

The Impact of Paternal and Maternal Smoking on Semen Quality of Adolescent Men

Background

Maternal smoking during pregnancy has been reported to negatively impact sperm counts of the sons. Sufficient data on the effect of paternal smoking is lacking.

Objectives

We wished to elucidate the impact of maternal and paternal smoking during pregnancy and current own smoking on reproductive function of the male offspring.

Methods

Semen parameters including sperm DNA integrity were analyzed in 295 adolescents from the general population close to Malmö, Sweden, recruited for the study during 2008–2010. Information on maternal smoking was obtained from the Swedish Medical Birth Register, and regarding own and paternal smoking from questionnaires. The impacts of maternal, paternal and own smoking were evaluated in a multivariate regression model and by use of models including interaction terms. Totally, three exposures and five outcomes were evaluated.

Results

In maternally unexposed men, paternal smoking was associated with 46% lower total sperm count (95%CI: 21%, 64%) in maternally unexposed men. Both paternal and maternal smoking were associated with a lower sperm concentration (mean differences: 35%; 95%CI: 8.1%, 55% and 36%; 95%CI: 3.9%, 57%, respectively) if the other parent was a non-smoker. No statistically significant impact of own smoking on semen parameters was seen.

Conclusions

Prenatal both maternal and paternal smoking were separately associated with some decrease in sperm count in men of whom the other parent was not reported to smoke.     

A systematic study of the energetics involved in structural changes upon association and connectivity in protein interaction networks

The study of protein binding mechanisms is a major topic of research in structural biology. Here, we implement a combination of metrics to systematically assess the cost of backbone conformational changes that protein domains undergo upon association. Through the analyses of 2090 unique unbound → bound transitions, from over 12,000 structures, we show that two-thirds of these proteins do not suffer significant structural changes upon binding, and could thus fit the lock-and-key model well. Among the remaining proteins, one-third explores the bound conformation in the unbound state (conformational selection model) and, while most transitions are possible from an energetic perspective, a few do require external help to break the thermodynamic barrier (induced fit model). We also analyze the relationship between conformational transitions and protein connectivity, finding that, in general, domains interacting with many partners undergo smaller changes upon association, and are less likely to freely explore larger conformational changes.