1,180 research outputs found
In vivo analysis of NHPX reveals a novel nucleolar localization pathway involving a transient accumulation in splicing speckles
Full text linkThe NHPX protein is a nucleolar factor that binds directly to a conserved RNA target sequence found in nucleolar box C/D snoRNAs and in U4 snRNA. Using enhanced yellow fluorescent protein (EYFP)– and enhanced cyan fluorescent protein–NHPX fusions, we show here that NHPX is specifically accumulated in both nucleoli and Cajal bodies (CBs) in vivo. The fusion proteins display identical localization patterns and RNA binding specificities to the endogenous NHPX. Analysis of a HeLa cell line stably expressing EYFP–NHPX showed that the nucleolar accumulation of NHPX was preceded by its transient accumulation in splicing speckles. Only newly expressed NHPX accumulated in speckles, and the nucleolar pool of NHPX did not interchange with the pool in speckles, consistent with a unidirectional pathway. The transient accumulation of NHPX in speckles prior to nucleoli was observed in multiple cell lines, including primary cells that lack CBs. Inhibitor studies indicated that progression of newly expressed NHPX from speckles to nucleoli was dependent on RNA polymerase II transcription, but not on RNA polymerase I activity. The data show a specific temporal pathway involving the sequential and directed accumulation of NHPX in distinct subnuclear compartments, and define a novel mechanism for nucleolar localization. © 2002 Leung et al. This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.jcb.org/misc/terms.shtml). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 3.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/3.0/). </p
Direct interaction between hnRNP-M and CDC5L/PLRG1 proteins affects alternative splice site choice
Full text linkHeterogeneous nuclear ribonucleoprotein-M (hnRNP-M) is an abundant nuclear protein that binds to pre-mRNA and is a component of the spliceosome complex. A direct interaction was detected in vivo between hnRNP-M and the human spliceosome proteins cell division cycle 5-like (CDC5L) and pleiotropic regulator 1 (PLRG1) that was inhibited during the heat-shock stress response. A central region in hnRNP-M is required for interaction with CDC5L/PLRG1. hnRNP-M affects both 50 and 30 alternative splice site choices, and an hnRNP-M mutant lacking the CDC5L/PLRG1 interaction domain is unable to modulate alternative splicing of an adeno-E1A mini-gene substrate.</p
Spatial organization of large scale chromatin domains in the nucleus: a magnified view of single chromosome territories.
No full textWe have analyzed the spatial organization of large scale chromatin domains in chinese hamster fibroblast, human lymphoid (IM-9), and marsupial kidney epithelial (PtK) cells by labeling DNA at defined stages of S phase via pulsed incorporation of halogenated deoxynucleosides. Most, if not all, chromosomes contribute multiple chromatin domains to both peripheral and internal nucleoplasmic compartments. The peripheral compartment contains predominantly late replicating G/Q bands, whereas early replicating R bands preferentially localize to the internal nucleoplasmic compartment. During mitosis, the labeled chromatin domains that were separated in interphase form a pattern of intercalated bands along the length of each metaphase chromosome. The transition from a banded (mitotic) to a compartmentalized (interphasic) organization of chromatin domains occurs during the late telophase/early G1 stage and is independent of transcriptional activation of the genome. Interestingly, generation of micronuclei with a few chromosomes showed that the spatial separation of early and late replicating chromatin compartments is recapitulated independently of chromosome number, even in micronuclei containing only a single chromosome. Our data strongly support the notion that the compartmentalization of large-scale (band size) chromatin domains seen in the intact nucleus is a magnified image of a similar compartmentalization occurring in individual chromosome territories.</p
Autumn leaves : sound and the environment in artistic practice
No full textThis publication is a book that represents an innovative, international and multi-disciplinary approach to conceptualising the dynamic relationships between sound and the environment. The editorial process involved directly commissioning textual, graphic and photographic work. The vast majority of the book represents new work, produced specifically for this publication. For the purposes of tracing historical development, an article from 1974 and three older projects have been revived and recontextualised. In addition to the editorial responsibility, the researcher wrote the introduction and conducted three original interviews. The book draws work from visual, sound and performance art, acoustic science, anthropology, cultural studies, public policy, and architectural theory. Just as it is true to say that these disciplines have not previously been brought together in this way, equally, it is no exaggeration to identify the contributors as the leading international lights in the field: Chris Watson, Tim Ingold, Hildegard Westerkamp, Christina Kubisch, Alvin Lucier, David Toop. The book is published by Double Entendre, the French publisher of the premier sound arts journal, Vibro. The book is accompanied by an audio compilation published by the German record label, Gruenrekorder (Gruen 053). www.autumn-leaves.gruenrekorder.de. The researcher co-curated the compilation, selecting relevant work that illustrated the book’s themes. The book was the catalyst for a one-day symposium at the Tate Britain called The Performance of Sound (May 19th, 2006), which the researcher co-organised. The researcher was invited to speak on the book at the Audio Extranautes: Flux, Distance, Sociability symposium at the Villa Arson in Nice in December 2007. Autumn Leaves has been reviewed in the French journal Mouvement; in MCD where the reviewer reported that “this book deserves to be translated into French”; and Soundscape: The Journal of Acoustic Ecology. Soundscape 7 (1), Autumn, 2007 reprinted an interview conducted by the author from the book. Autumn Leaves, edited by CRiSAP co-director Angus Carlyle, seeks to draw together a number of different perspectives on how the environment is made audible through sound. The perspectives contained in the book are made manifest through more traditional textual analyses, interviews, image-based works (both photography and graphic illustration) and ‘artist’s pages’ (which combine different registers of information).
Among the articles included in the book are a superb deconstruction of the concept of soundscape by anthropologist Tim Ingold; an intriguing analysis of sound from an acoustic point-of-view (or point-of-audition) by Bill Davies; Steve Goodman’s dynamic opening up of city sound to a bass materialism provoked by Greg Lynn’s ‘blob’ architecture; Salome Voegelin’s evocative mapping of sci-fi aesthetics onto the project of acoustic ecology; a wonderful meditation on the heard and the unheard by David Toop; Sylvain Marquis powerfully drawing out the ‘presence’ of Phill Niblock; Rahma Khazam finding new ways of listening through an inspired conceptual conversation between art, architecture and relational aesthetics; and a re-print of Hildegard Westerkamp’s pioneering discussion of soundwalking from 1974.
Interviews include a wide-ranging discussion with Alvin Lucier about his work and working practices; an exploration of Christina Kubisch’s long-standing commitment to teasing out the complexities of the sounds that surround us; Peter Cusack providing an exciting account of his Sound of Dangerous Places project; Chris Watson talking us through his inspirational field-recording; and Max Dixon offering fresh perspectives on how the development of strategies for noise in urban environments meshes policy with research into bio-acoustics, acoustics and creative practice.
Images include Dan Holdsworth’s haunting representations of anechoic chambers through Charles Fox’s photographs of microphone arrays in the wilderness, Axel Stockburger’s ASCII art evocations of video-game space and Nicholas Gansterer’s intricate diagrams of our heard world.
What remains of the book is devoted to the artists’ pages. In these a whole host of contemporary practitioners spanning the disciplines of graphic design, music, photography, performance and visual art offer their provocative takes on sound and the environment. Here we encounter John Wynne and Tim Wainwright presenting their collaborative work in Harefield Hospital; Aki Onda pursuing his Cinemage project; Claudia Wegener finding poetry in ear- and eye-witnessing; an unpacking of the theories and technologies behind the exciting Locus Sonus audio streams; NYSAE opening up its portfolio of acoustic ecology-inspired activities; Goran Vejvoda mobilising a modular manifesto from his three decades of sound art; the Gruenrekorder label reviewing the thinking behind its 40 releases; Jem Finer show-casing his Score For A Hole in the Ground; Cathy Lane mapping her memories of the Hebrides; Zoe Irvine making an art of places out of abandoned audio tape; and Mira Choi introducing her noise-responsive graphic software.
The editorial work and its presentation has been a collaborative venture with the designer Ian Noble.
Autumn Leaves is CRiSAP's first book and is edited by CRiSAP Co-Director Angus Carlyle[/b] and published by the exciting French sound art initiative Vibro / Double Entendre. It contains work by a variety of artists including several of CRiSAP's members - Salomé Voegelin, John Wynne, Peter Cusack, Cathy Lane and David Toop
Templeman, Angus William Lamond
No full textSecond run. Large index cards ordered alphabetically. Include staff particulars and salary information
Analysis of Nucleolar Protein Dynamics Reveals the Nuclear Degradation of Ribosomal Proteins
Full text linkBackground: The nucleolus is a subnuclear organelle in which rRNAs are transcribed, processed, and assembled with ribosomal proteins into ribosome subunits. Mass spectrometry combined with pulsed incorporation of stable isotopes of arginine and lysine was used to perform a quantitative and unbiased global analysis of the rates at which newly synthesized, endogenous proteins appear within mammalian nucleoli. Results: Newly synthesized ribosomal proteins accumulated in nucleoli more quickly than other nucleolar components. Studies involving time-lapse fluorescence microscopy of stable HeLa cell lines expressing fluorescent-protein-tagged nucleolar factors also showed that ribosomal proteins accumulate more quickly than other components. Photobleaching and mass-spectrometry experiments suggest that only a subset of newly synthesized ribosomal proteins are assembled into ribosomes and exported to the cytoplasm. Inhibition of the proteasome caused an accumulation of ribosomal proteins in the nucleus but not in the cytoplasm. Inhibition of rRNA transcription prior to proteasomal inhibition further increased the accumulation of ribosomal proteins in the nucleoplasm. Conclusions: Ribosomal proteins are expressed at high levels beyond that required for the typical rate of ribosome-subunit production and accumulate in the nucleolus more quickly than all other nucleolar components. This is balanced by continual degradation of unassembled ribosomal proteins in the nucleoplasm, thereby providing a mechanism for mammalian cells to ensure that ribosomal protein levels are never rate limiting for the efficient assembly of ribosome subunits. The dual time-lapse strategy used in this study, combining proteomics and imaging, provides a powerful approach for the quantitative analysis of the flux of newly synthesized proteins through a cell organelle
p53-Dependent subcellular proteome localization following DNA damage
No full textThe nucleolus is involved in regulating several aspects of stress responses and cell cycle arrest through the tumor suppressor p53. Under normal conditions, p53 is a short-lived protein that is present in cells at a barely detectable level. Upon exposure of cells to various forms of exogenous stress, such as DNA damage, there is a stabilization of p53 which is then responsible for an ensuing cascade of events. To further investigate the effect of p53 activation, we used a MS-based proteomics method to provide an unbiased, quantitative and high-throughput approach for measuring the subcellular distribution of the proteome that is dependent on p53. The spatial proteomics method analyses a whole cell extract created by recombining differentially labeled subcellular fractions derived from cells in which proteins have been mass labeled with heavy isotopes [Boisvert, F.-M., Lam, Y. W., Lamont, D., Lamond, A. I., Mol. Cell. Proteomics 2010, 9, 457-470]. This was used here to measure the relative distribution between cytoplasm, nucleus and nucleolus of around 2000 proteins in HCT116 cells that are either expressing wild-type p53 or null for p53. Spatial proteomics also facilitates a proteome-wide comparison of changes in protein localization in response to a wide range of physiological and experimental perturbations. We used this method to study differences in protein localization in HCT116 cells either with or without p53, and studied the differences in cellular response to DNA damage following treatment of HCT116 cells with etoposide in both p53 wild-type and null genetic backgrounds.</p
A protein phosphatase network controls the temporal and spatial dynamics of differentiation commitment in human epidermis
Full text linkEpidermal homeostasis depends on a balance between stem cell renewal and terminal differentiation. The transition between the two cell states, termed commitment, is poorly understood. Here we characterise commitment by integrating transcriptomic and proteomic data from disaggregated primary human keratinocytes held in suspension to induce differentiation. Cell detachment induces several protein phosphatases, five of which - DUSP6, PPTC7, PTPN1, PTPN13 and PPP3CA – promote differentiation by negatively regulating ERK MAPK and positively regulating AP1 transcription factors. Conversely, DUSP10 expression antagonises commitment. The phosphatases form a dynamic network of transient positive and negative interactions that change over time, with DUSP6 predominating at commitment. Boolean network modelling identifies a mandatory switch between two stable states (stem and differentiated) via an unstable (committed) state. Phosphatase expression is also spatially regulated in vivo and in vitro. We conclude that an auto-regulatory phosphatase network maintains epidermal homeostasis by controlling the onset and duration of commitment
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