Oxford Eprints
(1.101 recursos)
Oxford E-prints is a cross-disciplinary digital archive for research articles written by Oxford University authors. The repository has been developed as part of the SHERPA (Securing a Hybrid Environment for Research Preservation and Access) project and is running on eprints.org open archives software.
Mostrando recursos 1 - 13 de 13
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Advanced patch-clamp techniques and single-channel analysis - White, PJ; Biskup, B; Elzenga, JTM; Homann, U; Thiel, G; Wissing, F; Maathuis, FJM
Much of our knowledge of ion-transport mechanisms in plant cell membranes comes from experiments using voltage-clamp. This technique allows the measurement of ionic currents across the membrane, whilst the voltage is held under experimental control. The patch-clamp technique was developed to study the ionic currents flowing through single channels, but in its whole-cell configuration it is probably the most widely used voltage-clamp technique. This article provides a basic introduction to several advanced patch-clamp techniques, and evaluates methods for single-channel analysis. The initial sections describe the fabrication and use of perfusion pipettes, which enable the experimenter to manipulate the composition of...
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Plant acuaporins: their molecular biology, biophysics and significance for plant water relations - Tyerman, SD; Bohnert, HJ; Maurel, C; Steudle, E; Smith, JAC
Over the last decade, considerable advances have occurred in understanding the molecular biology and biophysics of water permeation across plant membranes and tissues. Spurred on by the rapid advances in cloning and functional characterization of a super-family of major intrinsic proteins, some of which function as aquaporins, the biophysics of transport of water and small non-electrolytes across plant membranes is being re-examined based on the proposed function of these membrane-integral proteins in their native membranes. This review focuses on a number of issues that are central to an understanding of aquaporin function: (1) the need to be able to test...
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Imaging techniques in plant transport: meeting review - Fricker, MD; Oparka, KJ
This review covers recent advances in imaging techniques that were presented during the 11th International Workshop on Plant Membrane Biology, Cambridge, August 1998. Cell biology has been revolutionized by the arrival of green fluorescent protein (GFP) and GFP is now routinely used as a cell-lineage marker in plants, to localize proteins to subcellular compartments or as a tag to follow dynamics in endomembrane compartments. More recent developments include modification of GFP to form physiological sensors for calcium and pH. These provide a transgenic approach in parallel with conventional chemical dyes to track signalling events or follow membrane recycling pathways. Confocal...
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Cell and Molecular Biology, Biochemistry and Molecular Physiology. Intracellular pH regulation in maize root tips exposed to ammonium at high external pH - Gerendás, J.; Ratcliffe, R.G.
Ammonium-induced changes in the cytoplasmic and vacuolar pH values of excised maize (Zea mays L.) root tips, measured by in vivo 31P nuclear magnetic resonance (NMR) spectroscopy, were correlated with the ammonium content of the tissue, determined by 14N NMR. Calculations based on these measurements indicated that the pH changes observed during exposure to 10 mM ammonium for 1 h at pH 9.0, and in the recovery following the removal of the external ammonium supply, were largely determined by the influx and efflux of the weak base NH3. Carboxylate synthesis, detected by both in vivo 13C NMR and the incorporation...
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Mitochondria-targeted GFP highlights the heterogeneity of mitochondrial shape, size and movement within living plant cells - Logan, David C.; Leaver, Christopher J.
Little is known concerning the heterogeneity of mitochondrial shape, size, number, cytoplasmic distribution, and motility in planta. Ultrastructural studies using the electron microscope have shown a variety of mitochondrial shapes and sizes within fixed cells, however, it is not possible to dismiss the possibility that any heterogeneity observed resulted from preparation or fixation artefacts. Unambiguous demonstration of the extent and nature of mitochondrial heterogeneity in vivo necessitates the use of a truly in vivo mitochondrial detection system. Green fluorescent protein is an excellent in vivo marker for gene expression and protein localization studies. It is particularly useful for real-time spatiotemporal...
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Regulation of Growth, Development and Whole Organism Physiology. Anoxia tolerance in the aquatic monocot Potamogeton pectinatus: absence of oxygen stimulates elongation in association with an unusually large Pasteur effect - Summers, Jacky E.; Ratcliffe, R. George; Jackson, Michael B.
Elongation by stems of overwintered tubers of Potamogeton pectinatus (L.) is strongly promoted over several days by oxygen-free conditions. Characteristics of the respiration underpinning this unusual response were examined. Anaerobic plants produced ethanol and CO2 in approximately equimolar amounts, indicating that glycolysis coupled to alcoholic fermentation was the principal CO2-producing respiratory pathway. Rates of CO2 evolution by aerobic and anaerobic whole plants (shoot and tuber) were similar, suggesting a rate of glycolysis three times that of aerobic plants, i.e. a strong Pasteur effect. In the shoot alone, anaerobic CO2 production was twice the aerobic rate indicating a 6-fold increase in...
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Regulation of Growth, Development and Whole Organism Physiology. Restoration of gravitropic sensitivity in starch-deficient mutants of Arabidopsis by hypergravity - Fitzelle, Karli J.; Kiss, John Z.
Despite the extensive study of plant gravitropism, there have been few experiments which have utilized hypergravity as a tool to investigate gravisensitivity in flowering plants. Previous studies have shown that starch-deficient mutants of Arabidopsis are less sensitive to gravity compared to the wild-type (WT). In this report, the question addressed was whether hypergravity could restore the sensitivity of starch-deficient mutants of Arabidopsis. The strains examined include a WT, a starchless mutant and a reduced-starch mutant. Vertical orientation studies with dark-grown seedlings indicate that increased centrifugal acceleration improves orientation relative to the acceleration vector for all strains, even the WT. For...
9.
Approaches to understanding Metabolism at the Single Cell. Confocal imaging of metabolism in vivo: pitfalls and possibilities - Fricker, M.D.; Meyer, A.J.
Confocal laser scanning microscopy (CLSM) has had wide application in morphological studies and ion imaging in plants, but little impact so far on biochemical investigations. This position is likely to change as the range of fluorescent probes increases. To illustrate the type of kinetic information that can be obtained using CLSM in an intact, living system, an analysis has been made of the two-step detoxification of monochlorobimane (MCB) following conjugation to glutathione (GSH) by a glutathione S-transferase in the cytoplasm and vacuolar sequestration of the fluorescent glutathione S-bimane (GSB) by a glutathione S-conjugate (GSX) pump. Fluorescence from the cytoplasm and...
10.
Utilization of glycine and serine as nitrogen sources in the roots of Zea mays and Chamaegigas intrepidus - Hartung, W.; Ratcliffe, R. G.
Glycine and serine are potential sources of nitrogen for the aquatic resurrection plant Chamaegigas intrepidus Dinter in the rock pools that provide its natural habitat. The pathways by which these amino acids might be utilized were investigated by incubating C. intrepidus roots and maize (Zea mays) root tips with [15N]glycine, [15N]serine and [2-13C]glycine. The metabolic fate of the label was followed using in vivo NMR spectroscopy, and the results were consistent with the involvement of the glycine decarboxylase complex (GDC) and serine hydroxymethyltransferase (SHMT) in the utilization of glycine. In contrast, the labelling patterns provided no evidence for the involvement...
11.
Sporophytic self-incompatibility in Senecio squalidus L. (Asteraceae)- the search for S - Hiscock, Simon J.; McInnis, Stephanie M.; Tabah, David A.; Henderson, Catherine A.; Brennan, Adrian C.
Senecio squalidus (Oxford Ragwort) is being used as a model species to study the genetics and molecular genetics of self-incompatibility (SI) in the Asteraceae. S. squalidus has a strong system of sporophytic SI (SSI) and populations within the UK contain very few S alleles probably due to a population bottleneck experienced on its introduction to the UK. The genetic control of SSI in S. squalidus is complex and may involve a second locus epistatic to S. Progress towards identifying the female determinant of SSI in S. squalidus is reviewed here. Research is focused on plants carrying two defined S alleles,...
12.
Elevated sucrose-phosphate synthase activity in transgenic tobacco sustains photosynthesis in older leaves and alters development - Baxter, Charles J.; Foyer, Christine H.; Turner, Janice; Rolfe, Stephen A.; Quick, W. Paul
Constitutive over-expression of a maize sucrose-phosphate synthase (SPS) gene in tobacco (Nicotiana tabacum) had major effects on leaf carbohydrate budgets with consequences for whole plant development. Transgenic tobacco plants flowered earlier and had greater flower numbers than wild-type plants. These changes were not linked to modified source leaf carbon assimilation or carbon export, although sucrose to starch ratios were significantly higher in leaves expressing the transgene. The youngest and oldest leaves of plants over-expressing SPS had up to 10-fold wild-type maximal extractable SPS activity, but source leaf SPS activities were only 2-3 times greater in these lines than in the...
13.
Effects of a PAL inhibitor on phenolic accumulation and UV-B tolerance in Spirodela intermedia (Koch.) - Gitz, Dennis C.; Liu-Gitz, Lan; McClure, Jerry W.; Huerta, Alfredo J.
Duckweed (Spirodela intermedia) was grown axenically on 1/2 strength Hutner's nutrient solution plus 1% sucrose, with the l-phenylalanine ammonia-lyase (PAL) inhibitor 2-aminoindan-2-phosphonic acid (AIP) at 0.0, 0.05, or 10 µM, at constant 25 font=symbol charset=fontspecific code=176C and a light intensity of 300 µmol m-2 s-1 photosynthetically active radiation from CW fluorescent lamps. Growth with 10 µM AIP led to decreased frond area and fresh weight, but dry weight was unchanged. Microscopic examination of fronds revealed increased frond thickness and a lack of reticulate aerenchyma. Ultraviolet epifluorescence microscopy and UV-Vis spectroscopy of methanolic extracts confirmed the dose-dependent inhibition of secondary phenolic...
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