650 research outputs found
Beyond the flammantia moenia mundi: the Transgressive Notion of the Sublime in Lucretius’ De rerum natura
pp. 64-78 of the Journal of the LUCAS Graduate Conference, Issue 4 (2016). The complete issue can be found at: http://hdl.handle.net/1887/38532Wetensch. publicati
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Happiness and Superlative Value in the Eudemian Ethics
In my dissertation Happiness and Superlative Value in the Eudemian Ethics, I analyze dimensions of the Eudemian Ethics (EE) that, as I see it, make the EE a distinctive contribution to ethics. The EE discusses a superlative excellence called kalokagathia, the virtue of being-beautiful-and-good, which does not figure in the Nicomachean Ethics (NE). The agent who possesses kalokagathia is the best agent of Aristotle’s EE. Scholars tend to hold that the practically wise person, the phronimos, or the theoretically wise person, the sophos, are the best agents of the NE. If my reading of the EE is right, then the EE and the NE conceive differently of the best agent. This is salient in both treatises’ construals of the unity of the virtues. In the NE, the unity of the virtues includes the character virtues and phronêsis. In the EE, it additionally includes the virtues of theoretical thinking, or so I argue. The EE starts with what I call the Superlative Thesis (ST): happiness is what is best, most beautiful, and most pleasant of all. I take this beginning to be programmatic. Aristotle aims to show how these three kinds of value combine in the best human life, rather than coming apart. The Pleasure Thesis (PT) is the most contested aspect of ST: happiness is the most pleasant thing of all. On my reading, Aristotle fully embraces PT. In laying out his proposal for the best human life, the Aristotle of the EE develops a distinctive kind of naturalism, which I call Natural Goods Naturalism. I reconstruct this position in two steps: by interpreting the EE’s function argument; and by exploring the notion of natural goods, which is central to the EE, but does not figure in the NE. In sum, my dissertation argues that the EE contains a distinctive and under-appreciated option within ancient ethics, and that it contains ideas that are relevant to today’s virtue ethics and ethical naturalism
HIstome—a relational knowledgebase of human histone proteins and histone modifying enzymes
Histones are abundant nuclear proteins that are essential for the packaging of eukaryotic DNA into chromosomes. Different histone variants, in combination with their modification ‘code’, control regulation of gene expression in diverse cellular processes. Several enzymes that catalyze the addition and removal of multiple histone modifications have been discovered in the past decade, enabling investigations of their role(s) in normal cellular processes and diverse pathological conditions. This sudden influx of data, however, has resulted in need of an updated knowledgebase that compiles, organizes and presents curated scientific information to the user in an easily accessible format. Here, we present HIstome, a browsable, manually curated, relational database that provides information about human histone proteins, their sites of modifications, variants and modifying enzymes. HIstome is a knowledgebase of 55 human histone proteins, 106 distinct sites of their post-translational modifications (PTMs) and 152 histone-modifying enzymes. Entries have been grouped into 5 types of histones, 8 types of post-translational modifications and 14 types of enzymes that catalyze addition and removal of these modifications. The resource will be useful for epigeneticists, pharmacologists and clinicians. HIstome: The Histone Infobase is available online at http://www.iiserpune.ac.in/∼coee/histome/ and http://www.actrec.gov.in/histome/
Vitellogenin Underwent Subfunctionalization to Acquire Caste and Behavioral Specific Expression in the Harvester Ant Pogonomyrmex barbatus
PMCID: PMC3744404This is an open-access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication
RNA Binding to CBP Stimulates Histone Acetylation and Transcription
CBP/p300 are transcription co-activators whose binding is a signature of enhancers, cis-regulatory elements that control patterns of gene expression in multicellular organisms. Active enhancers produce bi-directional enhancer RNAs (eRNAs) and display CBP/p300-dependent histone acetylation. Here, we demonstrate that CBP binds directly to RNAs in vivo and in vitro. RNAs bound to CBP in vivo include a large number of eRNAs. Using steady-state histone acetyltransferase (HAT) assays, we show that an RNA binding region in the HAT domain of CBP—a regulatory motif unique to CBP/p300—allows RNA to stimulate CBP’s HAT activity. At enhancers where CBP interacts with eRNAs, stimulation manifests in RNA-dependent changes in the histone acetylation mediated by CBP, such as H3K27ac, and by corresponding changes in gene expression. By interacting directly with CBP, eRNAs contribute to the unique chromatin structure at active enhancers, which, in turn, is required for regulation of target genes
Thymus-homing peripheral dendritic cells constitute two of the three major subsets of dendritic cells in the steady-state thymus
Many dendritic cells (DCs) in the normal mouse thymus are generated intrathymically from common T cell/DC progenitors. However, our previous work suggested that at least 50% of thymic DCs originate independently of these progenitors. We now formally demonstrate by parabiotic, adoptive transfer, and developmental studies that two of the three major subsets of thymic DCs originate extrathymically and continually migrate to the thymus, where they occupy a finite number of microenvironmental niches. The thymus-homing DCs consisted of immature plasmacytoid DCs (pDCs) and the signal regulatory protein α–positive (Sirpα+) CD11b+ CD8α− subset of conventional DCs (cDCs), both of which could take up and transport circulating antigen to the thymus. The cDCs of intrathymic origin were mostly Sirpα− CD11b− CD8αhi cells. Upon arrival in the thymus, the migrant pDCs enlarged and up-regulated CD11c, major histocompatibility complex II (MHC II), and CD8α, but maintained their plasmacytoid morphology. In contrast, the migrant cDCs proliferated extensively, up-regulated CD11c, MHC II, and CD86, and expressed dendritic processes. The possible functional implications of these findings are discussed
The thymic medulla: a unique microenvironment for intercellular self-antigen transfer
Central tolerance is shaped by the array of self-antigens expressed and presented by various types of thymic antigen-presenting cells (APCs). Depending on the overall signal quality and/or quantity delivered in these interactions, self-reactive thymocytes either apoptose or commit to the T regulatory cell lineage. The cellular and molecular complexity underlying these events has only recently been appreciated. We analyzed the ex vivo presentation of ubiquitous or tissue-restricted self-antigens by medullary thymic epithelial cells (mTECs) and thymic dendritic cells (DCs), the two major APC types present in the medulla. We found that the ubiquitously expressed nuclear neo–self-antigen ovalbumin (OVA) was efficiently presented via major histocompatibility complex class II by mTECs and thymic DCs. However, presentation by DCs was highly dependent on antigen expression by TECs, and hemopoietic cells did not substitute for this antigen source. Accordingly, efficient deletion of OVA-specific T cells correlated with OVA expression by TECs. Notably, OVA was only presented by thymic but not peripheral DCs. We further demonstrate that thymic DCs are constitutively provided in situ with cytosolic as well as membrane-bound mTEC-derived proteins. The subset of DCs displaying transferred proteins was enriched in activated DCs, with these cells being most efficient in presenting TEC-derived antigens. These data provide evidence for a unique, constitutive, and unidirectional transfer of self-antigens within the thymic microenvironment, thus broadening the cellular base for tolerance induction toward promiscuously expressed tissue antigens
The genomes of two key bumblebee species with primitive eusocial organization
Background: The shift from solitary to social behavior is one of the major evolutionary transitions. Primitively eusocial bumblebees are uniquely placed to illuminate the evolution of highly eusocial insect societies. Bumblebees are also invaluable natural and agricultural pollinators, and there is widespread concern over recent population declines in some species. High-quality genomic data will inform key aspects of bumblebee biology, including susceptibility to implicated population viability threats. Results: We report the high quality draft genome sequences of Bombus terrestris and Bombus impatiens, two ecologically dominant bumblebees and widely utilized study species. Comparing these new genomes to those of the highly eusocial honeybee Apis mellifera and other Hymenoptera, we identify deeply conserved similarities, as well as novelties key to the biology of these organisms. Some honeybee genome features thought to underpin advanced eusociality are also present in bumblebees, indicating an earlier evolution in the bee lineage. Xenobiotic detoxification and immune genes are similarly depauperate in bumblebees and honeybees, and multiple categories of genes linked to social organization, including development and behavior, show high conservation. Key differences identified include a bias in bumblebee chemoreception towards gustation from olfaction, and striking differences in microRNAs, potentially responsible for gene regulation underlying social and other traits. Conclusions: These two bumblebee genomes provide a foundation for post-genomic research on these key pollinators and insect societies. Overall, gene repertoires suggest that the route to advanced eusociality in bees was mediated by many small changes in many genes and processes, and not by notable expansion or depauperation
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