Novel Two-Step Hierarchical Screening of Mutant Pools Reveals Mutants under Selection in Chicks

Contaminated chicken/egg products are major sources of human salmonellosis, yet the strategies used by Salmonella to colonize chickens are poorly understood. We applied a novel two-step hierarchical procedure to identify new genes important for colonization and persistence of Salmonella enterica serotype Typhimurium in chickens. A library of 182 S. Typhimurium mutants each containing a targeted deletion of a group of contiguous genes (for a total of 2,069 genes deleted) was used to identify regions under selection at 1, 3, and 9 days postinfection in chicks. Mutants in 11 regions were under selection at all assayed times (colonization mutants), and mutants in 15 regions were under selection only at day 9 (persistence mutants). We assembled a pool of 92 mutants, each deleted for a single gene, representing nearly all genes in nine regions under selection. Twelve single gene deletion mutants were under selection in this assay, and we confirmed 6 of 9 of these candidate mutants via competitive infections and complementation analysis in chicks. STM0580, STM1295, STM1297, STM3612, STM3615, and STM3734 are needed for Salmonella to colonize and persist in chicks and were not previously associated with this ability. One of these key genes, STM1297 (selD), is required for anaerobic growth and supports the ability to utilize formate under these conditions, suggesting that metabolism of formate is important during infection. We report a hierarchical screening strategy to interrogate large portions of the genome during infection of animals using pools of mutants of low complexity. Using this strategy, we identified six genes not previously known to be needed during infection in chicks, and one of these (STM1297) suggests an important role for formate metabolism during infection.     

Reasoning in psychosis: risky but not necessarily hasty

Introduction. A liberal acceptance (LA) threshold for hypotheses has been put forward to explain the well-replicated “jumping to conclusions” (JTC) bias in psychosis, particularly in patients with paranoid symptoms. According to this account, schizophrenia patients rest their decisions on lower subjective probability estimates. The initial formulation of the LA account also predicts an absence of the JTC bias under high task ambiguity (i.e., if more than one response option surpasses the subjective acceptance threshold).

Methods. Schizophrenia patients (n?=?62) with current or former delusions and healthy controls (n?=?30) were compared on six scenarios of a variant of the beads task paradigm. Decision-making was assessed under low and high task ambiguity. Along with decision judgments (optional), participants were required to provide probability estimates for each option in order to determine decision thresholds (i.e., the probability the individual deems sufficient for a decision).

Results. In line with the LA account, schizophrenia patients showed a lowered decision threshold compared to controls (82% vs. 93%) which predicted both more errors and less draws to decisions. Group differences on thresholds were comparable across conditions. At the same time, patients did not show hasty decision-making, reflecting overall lowered probability estimates in patients.

Conclusions. Results confirm core predictions derived from the LA account. Our results may (partly) explain why hasty decision-making is sometimes aggravated and sometimes abolished in psychosis. The proneness to make risky decisions may contribute to the pathogenesis of psychosis. A revised LA account is put forward.     

Toward Truly Water‐Soluble Rodlike Polyelectrolytes: Synthesis of Poly(para‐phenylenes) Wrapped in Ethylene Oxideand Amino Side Groups

Suzuki and Yamamoto cross‐coupling protocols are applied to synthesize water‐soluble poly(p‐phenylene) (PPP) derivatives decorated with oligoethylene oxide (OEO) and tertiary amino side groups. It is shown that constitutionally well‐defined PPPs can be obtained having degrees of polycondensation, P _n, of 30–60. In some cases, however the heteroatoms in the side chains affect the monomer synthesis and prevent proper chain growth through coordination of metal species present in the reaction medium. It is shown that essentially uncharged but still water‐soluble PPPs result if (i) the side groups bear their heteroatoms in the right position, and (ii) if the water‐soluble segments of the lateral substituents prevent intermolecular hydrophobic interactions of the apolar main chains reliably. In other words, the lateral substituents have to wrap the PPP core structure tightly in a closed outer shell of water‐soluble OEO moieties. These PPPs constitute a valuable new pool of model systems for future polyelectrolyte research, being highly complementary to what has been available so far.

     

Dispersities of Polyesters of Various Diphenols Prepared by Irreversible Polycondensations

Polyesters of bisphenol‐A, bisphenol‐P, catechol, and sebacic acid are prepared and different synthetic methods are compared. The diphenols are condensed with sebacoyl chloride either in dichloromethane/pyridine or in refluxing chlorobenzene without HCl‐acceptor. Furthermore, bisphenol‐A acetate is polycondensed with sebacic acid in bulk. All experiments are worked up so that fractionation is avoided. The extent of cyclization is estimated by matrix‐assisted laser desorption/ionization mass spectrometry (MALDI MS) and the molar mass distribution by size exclusion chromatography (SEC). Polycondensations in solution yield larger fractions of cyclics and higher dispersities (up to 11). Polycondensations in bulk give lower fractions of cycles and dispersities from 4.6 to 6.3 for high molar mass polyesters or 2.8 to 3.5 for low molar mass products. Characteristic curves describing the dependence of the dispersity on the initial monomer concentration are elaborated.

     

Ophthalmic epidemiology in Europe: the “European Eye Epidemiology” (E3) consortium

The European Eye Epidemiology (E3) consortium is a recently formed consortium of 29 groups from 12 European countries. It already comprises 21 population-based studies and 20 other studies (case–control, cases only, randomized trials), providing ophthalmological data on approximately 170,000 European participants. The aim of the consortium is to promote and sustain collaboration and sharing of data and knowledge in the field of ophthalmic epidemiology in Europe, with particular focus on the harmonization of methods for future research, estimation and projection of frequency and impact of visual outcomes in European populations (including temporal trends and European subregions), identification of risk factors and pathways for eye diseases (lifestyle, vascular and metabolic factors, genetics, epigenetics and biomarkers) and development and validation of prediction models for eye diseases. Coordinating these existing data will allow a detailed study of the risk factors and consequences of eye diseases and visual impairment, including study of international geographical variation which is not possible in individual studies. It is expected that collaborative work on these existing data will provide additional knowledge, despite the fact that the risk factors and the methods for collecting them differ somewhat among the participating studies. Most studies also include biobanks of various biological samples, which will enable identification of biomarkers to detect and predict occurrence and progression of eye diseases. This article outlines the rationale of the consortium, its design and presents a summary of the methodology.     

Effectiveness of metacognitive interventions for mental disorders in adults—A systematic review and meta‐analysis (METACOG)

We evaluated the effectiveness and acceptability of metacognitive interventions for mental disorders. We searched electronic databases and included randomized and nonrandomized controlled trials comparing metacognitive interventions with other treatments in adults with mental disorders. Primary effectiveness and acceptability outcomes were symptom severity and dropout, respectively. We performed random‐effects meta‐analyses. We identified Metacognitive Training (MCTrain), Metacognitive Therapy (MCTherap), and Metacognition Reflection and Insight Therapy (MERIT). We included 49 trials with 2,609 patients. In patients with schizophrenia, MCTrain was more effective than a psychological treatment (cognitive remediation, SMD = ?0.39). It bordered significance when compared with standard or other psychological treatments. In a post hoc analysis, across all studies, the pooled effect was significant (SMD = ?0.31). MCTrain was more effective than standard treatment in patients with obsessive–compulsive disorder (SMD = ?0.40). MCTherap was more effective than a waitlist in patients with depression (SMD = ?2.80), posttraumatic stress disorder (SMD = ?2.36), and psychological treatments (cognitive–behavioural) in patients with anxiety (SMD = ?0.46). In patients with depression, MCTherap was not superior to psychological treatment (cognitive–behavioural). For MERIT, the database was too small to allow solid conclusions. Acceptability of metacognitive interventions among patients was high on average. Methodological quality was mostly unclear or moderate. Metacognitive interventions are likely to be effective in alleviating symptom severity in mental disorders. Although their add‐on value against existing psychological interventions awaits to be established, potential advantages are their low threshold and economy.     

Obesity and dysregulated central and peripheral macrophage–neuron cross‐talk

The involvement of macrophages in the pathogenesis of obesity has been recognized since 2003. Early studies mostly focused on the role of macrophages in adipose tissue (AT) and in obesity‐associated chronic low‐grade inflammation. Lately, AT macrophages were shown to undergo intrinsic metabolic changes that affect their immune function (i.e., immunometabolism), corresponding to their unique properties along the range of pro‐ versus anti‐inflammatory activity. In parallel, recent studies in mice revealed critical neuronal–macrophage interactions, both in the CNS and in peripheral tissues, including in white and brown AT. These intercellular activities impinge on energy and metabolic homeostasis, partially by also engaging adipocytes in a neuronal–macrophage–adipocyte ménage à trois. Finally, neuropeptides (NP), such as NPY and appetite‐reducing NPFF, may prove as mediators in such intercellular network. In this concise review, we highlight some of these recent insights on adipose macrophage immunometabolism, as well as central and peripheral neuronal–macrophage interactions with emphasis on their impact on adipocyte biology and whole‐body metabolism. We also discuss the expanding view on the role of the NP, NPY and NPFF, in obesity.     

Electrospun Bacteria‐Gold Nanoparticle/Polymer Composite Mesofiber Nonwovens for Catalytic Application

Polymer composite nonwovens with living Micrococcus luteus (ML), a very common gram‐positive bacterium present on human skin, are prepared by electrospinning followed by coating via the chemical vapor deposition (CVD) of poly(p‐xylylene) (PPX). The encapsulated living ML convert Au(III) ions to gold nanoparticles (AuNPs) when the composite nonwovens are dipped in an aqueous chloroauric acid solution. As a result of this process, AuNPs are formed on the ML. The ML‐immobilized AuNPs can be used for catalytic reactions with acetone as the solvent at a very low gold concentration. Despite the presence of acetone, ML survive the catalytic reaction. Interestingly, the catalytic reactions are possible only when the ML in the nonwovens are alive. In contrast, nonwovens with dead ML do not show any significant catalytic activity.