1,525 research outputs found

    Boundary Crossing in School Governing Bodies: Perspectives from the Business Community

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    Policy changes to school governance have led to Governing Bodies (GBs) increasingly appointing skilled professionals from the business community. Research into these GBs views governors from business as a threat to lay governors and the stakeholder model (Young, 2017). Whilst there has been exploration of the contributions of business governors, the ways in which business volunteers develop into their new roles as business governors have not been captured. This paper is drawn from an evaluation of Lloyds Banking Group’s (LBG) school governance programme where 18 LBG employees were interviewed throughout the first year in their governor roles. Adapting Young’s (2017) categorisation of knowledge as ‘managerial’, ‘educational’ and ‘lay’, this paper articulates how LBG governors acquired ‘educational’ and ‘lay’ knowledge to transform their practices and how this was underpinned by ‘authenticity’ associated with the stakeholder model (Connolly, 2017). The paper presents perspectives from other GB stakeholders which suggest that the transformation of the LBG governors’ practice impacted upon GBs, with them crossing boundaries between landscapes of practice (Wenger-Trayner and Wenger-Trayner, 2014). The implications are that, within the context of performativity, the wider business sector has a role to play in school governance and understanding governor professional development is key to this

    Transcytosis in MDCK cells: identification of glycoproteins transported bidirectionally between both plasma membrane domains.

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    MDCK cells display fluid-phase transcytosis in both directions across the cell. Transcytosis of cell surface molecules was estimated by electron microscopic analysis of streptavidin-gold-labeled frozen sections of biotinylated cells. Within 3 h, approximately 10% of the surface molecules, biotinylated on the starting membrane domain, were detected on the opposite surface domain irrespective of the direction of transcytosis. This suggests that the transcytosis rates for surface molecules are equal in both directions across the cell as shown previously for fluid-phase markers

    Nocodazole-Dependent Transport, and Brefeldin A-Sensitive Processing and Sorting, of Newly Synthesized Membrane-Proteins in Cultured Neurons

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    The envelope glycoproteins of Semliki Forest virus (SFV), Vesicular Stomatitis virus (VSV), and Influenza Fowl Plague virus (FPV) are vectorially targeted in neurons to the plasma membrane of dendrites (SFV and VSV) and axons (FPV), To gain insight into the mechanisms responsible for such polarized delivery we have examined the effects on neurons of nocodazole and brefeldin A (BFA), which are known to cause microtubule depolymerization and disassembly of the Golgi apparatus, respectively, Nocodazole treatment blocked transport of all viral glycoproteins to both axons and dendrites, BFA treatment induced disruption of the Golgi complex, including the trans-Golgi network (TGN), and tubulation of endosomes, However, the delivery of the SFV and FPV glycoproteins to the cell surface was not affected significantly by BFA, although processing and sorting were altered as revealed by surface biotinylation and immunofluorescence microscopy of fixed nonpermeabilized cells, These results demonstrate the involvement of microtubules in axonal and dendritic transport of integral membrane glycoproteins, and the existence of a BFA-sensitive component in the sorting but not in the transport machinery

    Biogenesis of phagolysosomes proceeds through a sequential series of interactions with the endocytic apparatus

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    We have examined the modifications occurring during the transformation of phagosomes into phagolysosomes in J-774 macrophages. The use of low density latex beads as markers of phagosomes (latex bead compartments, LBC) allowed the isolation of these organelles by flotation on a simple sucrose gradient. Two-dimensional gel electrophoresis, immunocytochemistry, and biochemical assays have been used to characterize the composition of LBC at different time points after their formation, as well as their interactions with the organelles of the endocytic pathway. Our results show that LBC acquire and lose various markers during their transformation into phagolysosomes. Among these are members of the rab family of small GTPases as well as proteins of the lamp family. The transfer to the LBC of lamp 2, a membrane protein associated with late endocytic structures, was shown to be microtubule dependent. Videomicroscopy showed that newly formed phagosomes were involved in rapid multiple contacts with late components of the endocytic pathway. Collectively, these observations suggest that phagolysosome formation is a highly dynamic process that involves the gradual and regulated acquisition of markers from endocytic organelles

    Direct visualization of Ras proteins in spatially distinct cell surface microdomains

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    Localization of signaling complexes to specific microdomains coordinates signal transduction at the plasma membrane. Using immunogold electron microscopy of plasma membrane sheets coupled with spatial point pattern analysis, we have visualized morphologically featureless microdomains, including lipid rafts, in situ and at high resolution. We find that an inner-plasma membrane lipid raft marker displays cholesterol-dependent clustering in microdomains with a mean diameter of 44 nm that occupy 35% of the cell surface. Cross-linking an outer-leaflet raft protein results in the redistribution of inner leaflet rafts, but they retain their modular structure. Analysis of Ras microlocalization shows that inactive H-ras is distributed between lipid rafts and a cholesterol-independent microdomain. Conversely, activated H-ras and K-ras reside predominantly in nonoverlapping, cholesterol-independent microdomains. Galectin-1 stabilizes the association of activated H-ras with these nonraft microdomains, whereas K-ras clustering is supported by farnesylation, but not geranylgeranylation. These results illustrate that the inner plasma membrane comprises a complex mosaic of discrete microdomains. Differential spatial localization within this framework can likely account for the distinct signal outputs from the highly homologous Ras proteins

    Elevated CO\u3csub\u3e2\u3c/sub\u3e Enhances Productivity and the C/N Ratio of Grasses in the Colorado Shortgrass Steppe

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    Atmospheric CO2 concentrations have been increasing since the industrial revolution, and are projected to double within this century over today\u27s concentration of 360 ”mol mol-1 . This study used six open-top chambers in the Colorado, USA shortgrass steppe to investigate how increasing CO2 will affect productivity and C and N status of indigenous perennial grasses and forbs. From March until October, chambers were placed on two plots in each of the three blocks. In each block, one chamber was assigned an ambient CO2 treatment (~360 ”mol mol-1), the other an elevated CO2 treatment (~720 ”mol mol-1). Each block also had an unchambered control plot. Growth under elevated CO2 increased above-ground phytomass an average 31% in 1997 and 47% in 1998, with no differences in relative growth responses of C3 and C4 grasses and forbs. Growth in chambers was greater than non-chambered control plots, presumably due to warmer temperatures in chambers and a longer growing season. Shoot N concentrations were reduced 21% and C/N ratios increased 23% in elevated compared to ambient chambers. Variation in aboveground phytomass due to year, CO2 and chamber effects correlated well to % shoot N and C/N ratios, although for both traits different regression lines were required for green plant material (harvested in July) and senescent plant material (harvested in October). Results suggest increased growth and reduced N concentrations in this mixed C3/C4 grassland in an elevated CO2 environment

    Rab17, a novel small GTPase, is specific for epithelial cells and is induced during cell polarization

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    The rab subfamily of small GTPases has been demonstrated to play an important role in the regulation of membrane traffic in eukaryotic cells. Compared with nonpolarized cells, epithelial cells have distinct apical and basolateral transport pathways which need to be separately regulated. This raises the question whether epithelial cells require specific rab proteins. However, all rab proteins identified so far were found to be equally expressed in polarized and nonpolarized cells. Here we report the identification of rab17, the first epithelial cell-specific small GTPase. Northern blot analysis on various mouse organs revealed that the rab17 mRNA is present in kidney, liver, and intestine but not in organs lacking epithelial cells nor in fibroblasts. To determine whether rab17 is specific for epithelial cells we studied its expression in the developing kidney. We found that rab17 is absent from the mesenchymal precursors but is induced upon their differentiation into epithelial cells. In situ hybridization studies on the embryonic kidney and intestine revealed that rab17 is restricted to epithelial cells. By immunofluorescence and immunoelectron microscopy on kidney sections, rab17 was localized to the basolateral plasma membrane and to apical tubules. Rab proteins associated with two distinct compartments have been found to regulate transport between them. Therefore, our data suggest that rab17 might be involved in transcellular transport

    Rab8, a small GTPase involved in vesicular traffic between the TGN and the basolateral plasma membrane

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    Small GTP-binding proteins of the rab family have been implicated as regulators of membrane traffic along the biosynthetic and endocytic pathways in eukaryotic cells. We have investigated the localization and function of rab8, closely related to the yeast YPT1/SEC4 gene products. Confocal immunofluorescence microscopy and immunoelectron microscopy on filter-grown MDCK cells demonstrated that, rab8 was localized to the Golgi region, vesicular structures, and to the basolateral plasma membrane. Two-dimensional gel electrophoresis showed that rab8p was highly enriched in immuno-isolated basolateral vesicles carrying vesicular stomatitis virus-glycoprotein (VSV-G) but was absent from vesicles transporting the hemagglutinin protein (HA) of influenza virus to the apical cell surface

    Ancient agriculture in Southeast Arabia: A three thousand year record of runoff farming from central Oman (Rustaq)

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    Runoff farming is a key hydro-agricultural strategy that has proven efficient in arid areas. Research in Arabia on the function, development, maintenance, durability and abandonment of this technology is scarce. A multiproxy investigation (cartography, sedimentology, pedology, geochemistry, paleo-ecology and chronology) was conducted on a recently abandoned terraced area in Rustaq, Northern Oman. The aim was to characterize the formation, function and management of this runoff system and the driving factors behind its success. Cycles of cultivation were identified during the Iron Age II/III periods (specifically 750–450 BCE), the Early Pre-Islamic Period (PIR) (specifically 350–200 BCE), the Early and Middle Islamic periods (specifically 8–10th C CE, 13th-14th C CE) and the late Islamic period (specifically 17th C CE and later). This expansion and perenniality was possible thanks to: 1- available water (local to micro-regional orogenic precipitation despite a regional aridification during these periods); 2- suitable soils (weathered geological outcrops, probable aeolian /dust particles); 3- a system of production combining crops and husbandry; 4- a progressive increase in agricultural specialization (crops grown and techniques) in parallel with a diversification in hydraulic technology. These results are to some degree in accordance with known phases of settlement intensification and economic growth, but also reveal the persistence of small-scale rural livelihoods during periods of harsh conditions for which archaeological traces are very scarce
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