3,883 research outputs found

    Global turnover of histone post-translational modifications and variants in human cells

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    <p>Abstract</p> <p>Background</p> <p>Post-translational modifications (PTMs) on the N-terminal tails of histones and histone variants regulate distinct transcriptional states and nuclear events. Whereas the functional effects of specific PTMs are the current subject of intense investigation, most studies characterize histone PTMs/variants in a non-temporal fashion and very few studies have reported kinetic information about these histone forms. Previous studies have used radiolabeling, fluorescence microscopy and chromatin immunoprecipitation to determine rates of histone turnover, and have found interesting correlations between increased turnover and increased gene expression. Therefore, histone turnover is an understudied yet potentially important parameter that may contribute to epigenetic regulation. Understanding turnover in the context of histone modifications and sequence variants could provide valuable additional insight into the function of histone replacement.</p> <p>Results</p> <p>In this study, we measured the metabolic rate of labeled isotope incorporation into the histone proteins of HeLa cells by combining stable isotope labeling of amino acids in cell culture (SILAC) pulse experiments with quantitative mass spectrometry-based proteomics. In general, we found that most core histones have similar turnover rates, with the exception of the H2A variants, which exhibit a wider range of rates, potentially consistent with their epigenetic function. In addition, acetylated histones have a significantly faster turnover compared with general histone protein and methylated histones, although these rates vary considerably, depending on the site and overall degree of methylation. Histones containing transcriptionally active marks have been consistently found to have faster turnover rates than histones containing silent marks. Interestingly, the presence of both active and silent marks on the same peptide resulted in a slower turnover rate than either mark alone on that same peptide. Lastly, we observed little difference in the turnover between nearly all modified forms of the H3.1, H3.2 and H3.3 variants, with the notable exception that H3.2K36me2 has a faster turnover than this mark on the other H3 variants.</p> <p>Conclusions</p> <p>Quantitative proteomics provides complementary insight to previous work aimed at quantitatively measuring histone turnover, and our results suggest that turnover rates are dependent upon site-specific post-translational modifications and sequence variants.</p

    Metacognition, Social Cognition, and Mentalizing In Psychosis: Are These Distinct Constructs When It Comes To Subjective Experience Or Are We Just Splitting Hairs?

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    Research using the integrated model of metacognition has suggested that the construct of metacognition could quantify the spectrum of activities that, if impaired, might cause many of the subjective disturbances found in psychosis. Research on social cognition and mentalizing in psychosis, however, has also pointed to underlying deficits in how persons make sense of their experience of themselves and others. To explore the question of whether metacognitive research in psychosis offers unique insight in the midst of these other two emerging fields, we have offered a review of the constructs and research from each field. Following that summary, we discuss ways in which research on metacognition may be distinguished from research on social cognition and mentalizing in three broad categories: (1) experimental procedures, (2) theoretical advances, and (3) clinical applications or indicated interventions. In terms of its research methods, we will describe how metacognition makes a unique contribution to understanding disturbances in how persons make sense of and interpret their own experiences within the flow of life. We will next discuss how metacognitive research in psychosis uniquely describes an architecture which when compromised – as often occurs in psychosis – results in the loss of persons’ sense of purpose, possibilities, place in the world and cohesiveness of self. Turning to clinical issues, we explore how metacognitive research offers an operational model of the architecture which if repaired or restored should promote the recovery of a coherent sense of self and others in psychosis. Finally, we discuss the concrete implications of this for recovery-oriented treatment for psychosis as well as the need for further research on the commonalities of these approaches

    The global field of multi-family offices: An institutionalist perspective

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    We apply the notion of the organisational field to internationally operating multi-family offices. These organisations specialise on the preservation of enterprising and geographically dispersed families’ fortunes. They provide their services across generations and countries. Based on secondary data of Bloomberg’s Top 50 Family Offices, we show that they constitute a global organisational field that comprises two clusters of homogeneity. Clients may decide between two different configurations of activities, depending on their preferences regarding asset management, resource management, family management, and service architecture. The findings also reveal that multi-family offices make relatively similar value propositions all over the world. The distinctiveness of the clusters within the field is not driven by the embeddedness of the multi-family offices in different national environments or their various degrees of international experience. Rather, it is weakly affected by two out of four possible value propositions, namely the exclusiveness and the transparency of services

    Metacognition Is Necessary for the Emergence of Motivation in People With Schizophrenia Spectrum Disorders: A Necessary Condition Analysis

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    Metacognition deficits are a putative cause of reduced motivation in people with schizophrenia spectrum disorders. However, it is unclear whether certain levels of metacognition are necessary for motivation to emerge. This study used a Necessary Condition Analysis (NCA) to test whether metacognition was necessary for the presence of motivation and to identify the minimum level of metacognition necessary for high motivation to be possible in people with schizophrenia spectrum disorders (N=175). Participants completed clinician-rated measures of metacognition and motivation. NCA revealed that metacognition is a necessary condition for motivation and that high levels of motivation were only possible, although not guaranteed, when at least a basic level of metacognition was present. Findings suggest that metacognition is a necessary building block for the development of motivation. Results suggest that targeting metacognition may be essential for improving motivation among people with schizophrenia spectrum disorders who do not meet this metacognition threshold

    Entrepreneurial sons, patriarchy and the Colonels' experiment in Thessaly, rural Greece

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    Existing studies within the field of institutional entrepreneurship explore how entrepreneurs influence change in economic institutions. This paper turns the attention of scholarly inquiry on the antecedents of deinstitutionalization and more specifically, the influence of entrepreneurship in shaping social institutions such as patriarchy. The paper draws from the findings of ethnographic work in two Greek lowland village communities during the military Dictatorship (1967–1974). Paradoxically this era associated with the spread of mechanization, cheap credit, revaluation of labour and clear means-ends relations, signalled entrepreneurial sons’ individuated dissent and activism who were now able to question the Patriarch’s authority, recognize opportunities and act as unintentional agents of deinstitutionalization. A ‘different’ model of institutional change is presented here, where politics intersects with entrepreneurs, in changing social institutions. This model discusses the external drivers of institutional atrophy and how handling dissensus (and its varieties over historical time) is instrumental in enabling institutional entrepreneurship
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