Functional analysis of the magnetosome island in Magnetospirillum gryphiswaldense: the mamAB operon is sufficient for magnetite biomineralization

Bacterial magnetosomes are membrane-enveloped, nanometer-sized crystals of magnetite, which serve for magnetotactic navigation. All genes implicated in the synthesis of these organelles are located in a conserved genomic magnetosome island (MAI). We performed a comprehensive bioinformatic, proteomic and genetic analysis of the MAI in Magnetospirillum gryphiswaldense. By the construction of large deletion mutants we demonstrate that the entire region is dispensable for growth, and the majority of MAI genes have no detectable function in magnetosome formation and could be eliminated without any effect. Only <25% of the region comprising four major operons could be associated with magnetite biomineralization, which correlated with high expression of these genes and their conservation among magnetotactic bacteria. Whereas only deletion of the mamAB operon resulted in the complete loss of magnetic particles, deletion of the conserved mms6, mamGFDC, and mamXY operons led to severe defects in morphology, size and organization of magnetite crystals. However, strains in which these operons were eliminated together retained the ability to synthesize small irregular crystallites, and weakly aligned in magnetic fields. This demonstrates that whereas the mamGFDC, mms6 and mamXY operons have crucial and partially overlapping functions for the formation of functional magnetosomes, the mamAB operon is the only region of the MAI, which is necessary and sufficient for magnetite biomineralization. Our data further reduce the known minimal gene set required for magnetosome formation and will be useful for future genome engineering approaches

Exploring the neural substrates of misinformation processing

It is well known that information that is initially thought to be correct but then revealed to be false, often continues to influence human judgement and decision making despite people being aware of the retraction. Yet little research has examined the underlying neural substrates of this phenomenon, which is known as the ‘continued influence effect of misinformation’ (CIEM). It remains unclear how the human brain processes critical information that retracts prior claims. To address this question in further detail, 26 healthy adults underwent functional magnetic resonance imaging (fMRI) while listening to brief narratives which either involved a retraction of prior information or not. Following each narrative, subjects’ comprehension of the narrative, including their inclination to rely on retracted information, was probed. As expected, it was found that retracted information continued to affect participants’ narrative-related reasoning. In addition, the fMRI data indicated that the continued influence of retracted information may be due to a breakdown of narrative-level integration and coherence-building mechanisms implemented by the precuneus and posterior cingulate gyrus

Charge Dynamics of a CuO Thin Film on Picosecond to Microsecond Timescales Revealed by Transient Absorption Spectroscopy

Understanding the mechanism of charge dynamics in photocatalysts is the key to design and optimize more efficient materials for renewable energy applications. In this study, the charge dynamics of a CuO thin film are unraveled via transient absorption spectroscopy (TAS) on the picosecond to microsecond timescale for three different excitation energies, i.e., above, near, and below the band gap, to explore the role of incoherent broadband light sources. The shape of the ps-TAS spectra changes with the delay time, while that of the ns-TAS spectra is invariant for all the excitation energies. Regardless of the excitations, three time constants, τ1 ∼ 0.34–0.59 ps, τ2 ∼ 162–175 ns, and τ3 ∼ 2.5–3.3 μs, are resolved, indicating the dominating charge dynamics at very different timescales. Based on these observations, the UV–vis absorption spectrum, and previous findings in the literature, a compelling transition energy diagram is proposed. Two conduction bands and two defect (deep and shallow) states dominate the initial photo-induced electron transitions, and a sub-valence band energy state is involved in the subsequent transient absorption. By solving the rate equations for the pump-induced population dynamics and implementing the assumed Lorentzian absorption spectral shape between two energy states, the TAS spectra are modeled which capture the main spectral and time-dependent features for t > 1 ps. By further considering the contributions from free-electron absorption during very early delay times, the modeled spectra reproduce the experimental spectra very well over the entire time range and under different excitation conditions

Extension of corporate services brands: the effect of perceived similarity extension and perceived quality brand

O principal objetivo deste estudo é avaliar o efeito da qualidade percebida da marca-mãe e da similaridade percebida sobre as avaliações de extensões de marcas corporativas de serviços. Adicionalmente, também se deseja verificar se a elaboração das características da extensão contribuem para a sua avaliação. As hipóteses foram testadas por meio de três experimentos que envolveram no total 1.131 respondentes. No Estudo 1 foram utilizadas marcas fictícias como estímulo e verificou-se que a qualidade da marca-mãe teve efeito mais importante que a similaridade percebida sobre as avaliações de uma extensão de marca de serviços. No Estudo 2, utilizando como estímulos marcas reais, os mesmos resultados do Estudo 1 foram obtidos. No Estudo 3 verificou-se que a elaboração das características da extensão contribuiu positivamente apenas para uma das extensões propostas para a marca-mãe de alta qualidade, mas não teve nenhum efeito para as extensões propostas para a marca-mãe de baixa qualidade. Tomados em conjunto, os resultados sugerem que a qualidade percebida da marca-mãe tem papel fundamental na avaliação de extensões de marcas corporativas de serviços. O estudo contribui ainda com diversas hipóteses para estudos futuros e implicações gerenciais para gerentes de marcas corporativas de serviços.The main objective of this study is to assess the effect of parent brand perceived quality and perceived similarity on the evaluation of corporate service brand extensions. It is also the intention of this study to verify whether providing information cues about the characteristics of the extension contributes to the brand extension evaluation. The hypotheses were tested by means of three experiments involving 1,131 subjects. The results of Study 1, conducted with fictitious brands as stimuli, demonstrated that the perceived quality of the parent brand played a more significant role than perceived similarity on the evaluations of brand extensions. In Study 2, where real brands were used as stimuli, the results were the same as in Study 1. Study 3 found that providing information cues about the characteristics of the extensions had a positive effect for one of the extensions of the high quality parent brand but not for the two proposed extensions of the low quality parent brand. Taken as a whole, the results suggest that the perceived quality of the parent-brand plays a fundamental role in the evaluation of corporate service brand extensions. The study also contributes several hypotheses for future studies and managerial implications for managers of corporate service brands

Epinephrine-induced hyperpolarization of pancreatic islet cells is sensitive to PI3K–PDK1 signaling

AbstractEpinephrine inhibits insulin release by activation of K+ channels and subsequent hyperpolarization of pancreatic beta cells. The present study explored whether epinephrine-induced hyperpolarization is modified by phosphatidylinositol 3-kinase (PI3K) and phosphatidylinositide-dependent kinase PDK1. Perforated patch-clamp was performed in islet cells isolated from PDK1 hypomorphic mice (pdk1fl/fl), expressing only 20% of PDK1, and in their wild-type littermates. At 16.8mM glucose, the cell membrane was hyperpolarized by epinephrine (1μM), an effect significantly blunted in pdk1fl/fl and abrogated in wild-type cells by inhibition of PI3K with wortmannin (100nM) or LY294002 (10μM). The hyperpolarizing effect of epinephrine in pancreatic islet cells is thus sensitive to PI3K and PDK1

Activation of Microglial Poly(ADP-Ribose)-Polymerase-1 by Cholesterol Breakdown Products during Neuroinflammation: a Link between Demyelination and Neuronal Damage

Multiple sclerosis (MS) is a chronic demyelinating disease in which it has only recently been suggested that damage to neuronal structures plays a key role. Here, we uncovered a link between the release of lipid breakdown products, found in the brain and cerebrospinal fluid (CSF) of MS patients as well as in experimental autoimmune encephalomyelitis, and neuronal damage mediated by microglial activation. The concentrations of the breakdown product 7-ketocholesterol detected in the CSF of MS patients were capable of inducing neuronal damage via the activation and migration of microglial cells in living brain tissue. 7-ketocholesterol rapidly entered the nucleus and activated poly(ADP-ribose)-polymerase (PARP)-1, followed by the expression of migration-regulating integrins CD11a and intercellular adhesion molecule 1. These findings reveal a novel mechanism linking demyelination and progressive neuronal damage, which might represent an underlying insidious process driving disease beyond a primary white matter phenomenon and rendering the microglial PARP-1 a possible antiinflammatory therapeutic target

Continuously expanding CAR NK-92 cells display selective cytotoxicity against B-cell leukemia and lymphoma

Background aims Natural killer (NK) cells can rapidly respond to transformed and stressed cells and represent an important effector cell type for adoptive immunotherapy. In addition to donor-derived primary NK cells, continuously expanding cytotoxic cell lines such as NK-92 are being developed for clinical applications. Methods To enhance their therapeutic utility for the treatment of B-cell malignancies, we engineered NK-92 cells by lentiviral gene transfer to express chimeric antigen receptors (CARs) that target CD19 and contain human CD3ζ (CAR 63.z), composite CD28-CD3ζ or CD137-CD3ζ signaling domains (CARs 63.28.z and 63.137.z). Results Exposure of CD19-positive targets to CAR NK-92 cells resulted in formation of conjugates between NK and cancer cells, NK-cell degranulation and selective cytotoxicity toward established B-cell leukemia and lymphoma cells. Likewise, the CAR NK cells displayed targeted cell killing of primary pre-B-ALL blasts that were resistant to parental NK-92. Although all three CAR NK-92 cell variants were functionally active, NK-92/63.137.z cells were less effective than NK-92/63.z and NK-92/63.28.z in cell killing and cytokine production, pointing to differential effects of the costimulatory CD28 and CD137 domains. In a Raji B-cell lymphoma model in NOD-SCID IL2R γnull mice, treatment with NK-92/63.z cells, but not parental NK-92 cells, inhibited disease progression, indicating that selective cytotoxicity was retained in vivo. Conclusions Our data demonstrate that it is feasible to generate CAR-engineered NK-92 cells with potent and selective antitumor activity. These cells may become clinically useful as a continuously expandable off-the-shelf cell therapeutic agent