138 research outputs found

    A multidimensional systems biology analysis of cellular senescence in aging and disease.

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    BACKGROUND: Cellular senescence, a permanent state of replicative arrest in otherwise proliferating cells, is a hallmark of aging and has been linked to aging-related diseases. Many genes play a role in cellular senescence, yet a comprehensive understanding of its pathways is still lacking. RESULTS: We develop CellAge (http://genomics.senescence.info/cells), a manually curated database of 279 human genes driving cellular senescence, and perform various integrative analyses. Genes inducing cellular senescence tend to be overexpressed with age in human tissues and are significantly overrepresented in anti-longevity and tumor-suppressor genes, while genes inhibiting cellular senescence overlap with pro-longevity and oncogenes. Furthermore, cellular senescence genes are strongly conserved in mammals but not in invertebrates. We also build cellular senescence protein-protein interaction and co-expression networks. Clusters in the networks are enriched for cell cycle and immunological processes. Network topological parameters also reveal novel potential cellular senescence regulators. Using siRNAs, we observe that all 26 candidates tested induce at least one marker of senescence with 13 genes (C9orf40, CDC25A, CDCA4, CKAP2, GTF3C4, HAUS4, IMMT, MCM7, MTHFD2, MYBL2, NEK2, NIPA2, and TCEB3) decreasing cell number, activating p16/p21, and undergoing morphological changes that resemble cellular senescence. CONCLUSIONS: Overall, our work provides a benchmark resource for researchers to study cellular senescence, and our systems biology analyses reveal new insights and gene regulators of cellular senescence

    Crystallization and X-ray diffraction analysis of the C-terminal domain of the flax rust effector protein AvrM

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    The flax rust effector AvrM is a secreted protein of unknown fold that is recognized by the M resistance protein in flax. In order to investigate the structural basis of the AvrMM interaction and possible virulence-associated functions of AvrM, the C-terminal domains of two different AvrM variants (AvrM-A and avrM) were crystallized. Crystals of native AvrM-A were obtained using pentaerythritol ethoxylate (15/4 EO/OH) as a precipitant and diffracted X-rays to 2.9 angstrom resolution. Selenomethionine-derivative crystals of similar quality were obtained using PEG 1500 as a precipitant. Both the native and selenomethionine-labelled AvrM-A crystals had symmetry of space group C2221 with eight molecules in the asymmetric unit. Crystals of avrM had symmetry of space group P212121 and diffracted X-rays to 2.7 angstrom resolution. Initial AvrM-A phases were calculated using the single-wavelength anomalous dispersion (SAD) method and a partial model was built. Phases for avrM were obtained by molecular replacement using the partial AvrM-A model

    Testimonial Injustice and Vulnerability: A Qualitative Analysis of Participation in the Court of Protection

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    This article explores participation in Court of Protection (COP) proceedings by people considered vulnerable. The paper is based on original data obtained from observing COP proceedings and reviewing COP case files. It is argued that the observed absence of the subject of proceedings is a form of testimonial injustice, that is, a failure to value a person in their capacity as a giver of knowledge. The issue of competence to give evidence is considered but it is argued that it is not the formal evidential rules that prohibit a vulnerable adult from giving evidence. Instead, it is the result of a persistent assumption that they are inherently vulnerable and therefore lack credibility as a knowledge giver. This assumption results in the voices of vulnerable adults being routinely absent from legal proceedings. It is argued that having a voice in the courtroom is essential and has a number of intrinsic and instrumental benefits. The paper concludes with a discussion about the implications of the research, including the current trend towards the increased use of special measures, and recommends a presumption in favour of the subject of COP proceedings giving evidence

    Age is no barrier: predictors of academic success in older learners

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    Although predictors of academic success have been identified in young adults, such predictors are unlikely to translate directly to an older student population, where such information is scarce. The current study aimed to examine cognitive, psychosocial, lifetime, and genetic predictors of university-level academic performance in older adults (50–79 years old). Participants were mostly female (71%) and had a greater than high school education level (M = 14.06 years, SD = 2.76), on average. Two multiple linear regression analyses were conducted. The first examined all potential predictors of grade point average (GPA) in the subset of participants who had volunteered samples for genetic analysis (N = 181). Significant predictors of GPA were then re-examined in a second multiple linear regression using the full sample (N = 329). Our data show that the cognitive domains of episodic memory and language processing, in conjunction with midlife engagement in cognitively stimulating activities, have a role in predicting academic performance as measured by GPA in the first year of study. In contrast, it was determined that age, IQ, gender, working memory, psychosocial factors, and common brain gene polymorphisms linked to brain function, plasticity and degeneration (APOE, BDNF, COMT, KIBRA, SERT) did not influence academic performance. These findings demonstrate that ageing does not impede academic achievement, and that discrete cognitive skills as well as lifetime engagement in cognitively stimulating activities can promote academic success in older adults

    Respectful leadership:Reducing performance challenges posed by leader role incongruence and gender dissimilarity

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    We investigate how respectful leadership can help overcome the challenges for follower performance that female leaders face when working (especially with male) followers. First, based on role congruity theory, we illustrate the biases faced by female leaders. Second, based on research on gender (dis-)similarity, we propose that these biases should be particularly pronounced when working with a male follower. Finally, we propose that respectful leadership is most conducive to performance in female leader–male follower dyads compared with all other gender configurations. A multi-source field study (N = 214) provides partial support for our hypothesis. While our hypothesized effect was confirmed, respectful leadership seems to be generally effective for female leaders irrespective of follower gender, thus lending greater support in this context to the arguments of role congruity rather than gender dissimilarity

    Bacteriophage Crosstalk: Coordination of Prophage Induction by Trans-Acting Antirepressors

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    Many species of bacteria harbor multiple prophages in their genomes. Prophages often carry genes that confer a selective advantage to the bacterium, typically during host colonization. Prophages can convert to infectious viruses through a process known as induction, which is relevant to the spread of bacterial virulence genes. The paradigm of prophage induction, as set by the phage Lambda model, sees the process initiated by the RecA-stimulated self-proteolysis of the phage repressor. Here we show that a large family of lambdoid prophages found in Salmonella genomes employs an alternative induction strategy. The repressors of these phages are not cleaved upon induction; rather, they are inactivated by the binding of small antirepressor proteins. Formation of the complex causes the repressor to dissociate from DNA. The antirepressor genes lie outside the immunity region and are under direct control of the LexA repressor, thus plugging prophage induction directly into the SOS response. GfoA and GfhA, the antirepressors of Salmonella prophages Gifsy-1 and Gifsy-3, each target both of these phages' repressors, GfoR and GfhR, even though the latter proteins recognize different operator sites and the two phages are heteroimmune. In contrast, the Gifsy-2 phage repressor, GtgR, is insensitive to GfoA and GfhA, but is inactivated by an antirepressor from the unrelated Fels-1 prophage (FsoA). This response is all the more surprising as FsoA is under the control of the Fels-1 repressor, not LexA, and plays no apparent role in Fels-1 induction, which occurs via a Lambda CI-like repressor cleavage mechanism. The ability of antirepressors to recognize non-cognate repressors allows coordination of induction of multiple prophages in polylysogenic strains. Identification of non-cleavable gfoR/gtgR homologues in a large variety of bacterial genomes (including most Escherichia coli genomes in the DNA database) suggests that antirepression-mediated induction is far more common than previously recognized
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