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  • 1
    Electronic Resource
    Electronic Resource
    Cadmium induces senescence symptoms in leaf peroxisomes of pea plants (2001)
    Oxford, UK : Blackwell Science, Ltd
    Plant, cell & environment 24 (2001), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The effect of growing pea (Pisum sativum L.) plants with a toxic CdCl2 concentration (50 µm) on the metabolism and proteolytic activity of leaf peroxisomes was studied. In peroxisomes purified from plants treated with cadmium, an increase in the total protein concentration and in the activity and protein level of the photorespiratory enzyme glycolate oxidase was found. The glyoxylate cycle enzymes, malate synthase and isocitrate lyase, whose activity is normally very low in leaf peroxisomes, were enhanced by Cd treatment. The activity of the endogenous proteases of leaf peroxisomes was determined. Two leucine-aminopeptidase isozymes (AP1-AP2) were detected, and their activity was slightly higher in Cd-treated plants. Five endopeptidases (EP1-EP5) were present in pea leaf peroxisomes, and in plants grown with Cd the activity of isozymes EP1-EP4 was increased. The ultrastructural analysis of pea leaves showed that Cd produced a disorganization of the chloroplast structure, with an increase in the number of plastoglobuli, and the formation of vesicles in the vacuoles. Taken together, these results indicate that Cd induces senescence symptoms in leaf peroxisomes, and probably a metabolic transition of leaf peroxisomes into glyoxysomes, and suggest that the peroxisomal proteases could participate in the metabolic changes produced by Cd.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3040.2001.00750.x
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  • 2
    Electronic Resource
    Electronic Resource
    Cadmium-induced subcellular accumulation of O2·− and H2O2 in pea leaves (2004)
    Oxford, UK : Blackwell Science Ltd
    Plant, cell & environment 27 (2004), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Cadmium is a toxic metal that produces disturbances in plant antioxidant defences giving rise to oxidative stress. The effect of this metal on H2O2 and O2·− production was studied in leaves from pea plants growth for 2 weeks with 50 µm Cd, by histochemistry with diaminobenzidine (DAB) and nitroblue tetrazolium (NBT), respectively. The subcellular localization of these reactive oxygen species (ROS) was studied by cytochemistry with CeCl3 and Mn/DAB staining for H2O2 and O2·−, respectively, followed by electron microscopy observation. In leaves from pea plants grown with 50 µm CdCl2 a rise of six times in the H2O2 content took place in comparison with control plants, and the accumulation of H2O2 was observed mainly in the plasma membrane of transfer, mesophyll and epidermal cells, as well as in the tonoplast of bundle sheath cells. In mesophyll cells a small accumulation of H2O2 was observed in mitochondria and peroxisomes. Experiments with inhibitors suggested that the main source of H2O2 could be a NADPH oxidase. The subcellular localization of O2·− production was demonstrated in the tonoplast of bundle sheath cells, and plasma membrane from mesophyll cells. The Cd-induced production of the ROS, H2O2 and O2·−, could be attributed to the phytotoxic effect of Cd, but lower levels of ROS could function as signal molecules in the induction of defence genes against Cd toxicity. Treatment of leaves from Cd-grown plants with different effectors and inhibitors showed that ROS production was regulated by different processes involving protein phosphatases, Ca2+ channels, and cGMP.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.2004.01217.x
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  • 3
    Electronic Resource
    Electronic Resource
    Cadmium causes the oxidative modification of proteins in pea plants (2002)
    Oxford, UK : Blackwell Science Ltd
    Plant, cell & environment 25 (2002), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: In pea (Pisum sativum L.) leaves from plants grown in the presence of 50 µm CdCl2 the oxidative production of carbonyl groups in proteins, the rate of protein degradation and the proteolytic activity were investigated. In leaf extracts the content of carbonyl groups measured by derivatization with 2,4-dinitrophenylhydrazine (DNPH), was two-fold higher in plants treated with Cd than in control plants. The identification of oxidized proteins was carried out by sodium dodecyl sulphate-polyacrylamide gel electrophoresis of proteins derivatized with DNPH and immunochemical detection with an antibody against DNPH. The intensity of the reactive bands was higher in plants exposed to Cd than in controls. By using different antibodies some of the oxidized proteins were identified as Rubisco, glutathione reductase, manganese superoxide dismutase, and catalase. The incubation of leaf crude extracts with increasing H2O2 concentrations showed a progressive enhancement in carbonyl content and the pattern of oxidized proteins was similar to that found in Cd-treated plants. Oxidized proteins were more efficiently degraded, and the proteolytic activity increased 20% due to the metal treatment. In peroxisomes purified from pea leaves a rise in the carbonyl content similar to that obtained in crude extracts from Cd-treated plants was observed, but the functionality of the peroxisomal membrane was not apparently affected by Cd. Results obtained demonstrate the participation of both oxidative stress, probably mediated by H2O2, and proteolytic degradation in the mechanism of Cd toxicity in leaves of pea plants, and they appear to be involved in the Cd-induced senescence previously reported in these plants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3040.2002.00850.x
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  • 4
    Electronic Resource
    Electronic Resource
    Reactive oxygen species-mediated enzymatic systems involved in the oxidative action of 2,4-dichlorophenoxyacetic acid (2004)
    Oxford, UK : Blackwell Science Ltd
    Plant, cell & environment 27 (2004), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 2,4-dichlorophenoxyacetic acid (2,4-D) is an analogue compound to the plant hormone indole-3-acetic acid (IAA), which is used either as a growth-promoting substance or as a herbicide, depending on its concentration. In this work, the effect of 2,4-D on the growth and ROS metabolism of pea (Pisum sativum L.) leaves is reported. The herbicide considerably reduced the plant growth and negatively influenced several physiological parameters in a dose-dependent manner. At structural level, damage of the mesophyll cells and the enlargement and dilation of thylakoids were observed in 2,4-D-treated plants. 2,4-D notably affected xanthine oxidase and superoxide dismutase activities, as well as the activity and transcript levels of the ascorbate–glutathione cycle enzymes, ascorbate peroxidase, monodehydroascorbate reductase, and glutathione reductase. Furthermore, in herbicide-treated plants, an increase in the H2O2 production, levels of lipid peroxidation, endopeptidase activity and oxidatively modified proteins took place. Results obtained showed that an overproduction of superoxide radicals (O2−) and hydrogen peroxide (H2O2) could take place in plants treated with 2,4-D, thus contributing to the generation of oxidative stress, with the concomitant degradation of proteins. A model of the role of ROS-mediated enzymatic systems in the oxidative mode of action of 2,4-D and other auxinic herbicides is proposed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.2004.01219.x
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  • 5
    Electronic Resource
    Electronic Resource
    Evolution of the nucleotide sequence of influenza virus RNA segment 7 during drift of the H3N2 subtype
    Amsterdam : Elsevier
    Gene 23 (1983), S. 233-239 
    Details
    ISSN: 0378-1119
    Keywords: Escherichia coli ; Molecular cloning ; restriction enzymes ; reverse transcriptase ; sequence determination ; spontaneous mutation
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0378-1119(83)90055-0
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  • 6
    Electronic Resource
    Electronic Resource
    Mitochondrial and peroxisomal ascorbate peroxidase of pea leaves (1998)
    Copenhagen : Munksgaard International Publishers
    Physiologia plantarum 104 (1998), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The isoenzyme pattern and the substrate specificity of the membrane-bound mitochondrial and peroxisomal ascorbate peroxidases (APX; EC 1.11.1.11) from pea leaves are studied. The substrate specificity of both APXs was assayed using the electron donors ascorbate and pyrogallol, whereas o-dianisidine, hydroquinone, tetramethylbenzidine and 4-methoxy-α-naphthol were also assayed with mitochondrial APX (mitAPX). In leaf mitochondria, the specific activity of APX was similar with pyrogallol and ascorbate, the activity being inhibited by p-CMS. mitAPX showed low activity with the guaiacol peroxidase (GPX)-type substrates, tetramethylbenzidine and 4-methoxy-α-naphthol. Activity of mitAPX with hydroquinone suggest a potential role of mitAPX in the drainage of electrons from the mitochondrial electron chain at the level of ubiquinone. In peroxisomes, the APX (perAPX) specific activity was much higher with pyrogallol than with ascorbate. This perAPX was more sensitive to incubation with Triton X-100 than the mitAPX. By native PAGE the mitAPX was resolved in 6 isoenzyme bands, and the activity of the 3 main bands (mitAPX III, III′ and IV) was inhibited by p-CMS. These 3 major isozymes were also present in mitochondrial membrane fractions. Staining for GPX activity with 4-methoxy-α-naphthol revealed that the APX detected in mitochondria did not have the capacity to oxidize 4-MN, and therefore cannot be considered as true GPX. When intact peroxisomes and peroxisomal membranes were subjected to native PAGE, no APX activity could be detected and this was probably due to the inactivation of perAPX. Results obtained suggest that pea mitochondrial APX (mitAPX) represent a distinct and novel isozyme different from those APXs of chloroplast and cytosolic origin previously reported. The peroxisomal APX (perAPX), however, appears to ressemble the chloroplast APXs as regards its sensitivity to Triton X-100.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1399-3054.1998.1040424.x
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  • 7
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    Characterization by X-ray computed tomography of water absorption in a limestone used as building stone in the Oviedo Cathedral (Spain) (2003)
    In:  Geological Society Special Publication 215: 127-134.
    Details
    Publication Date: 2003-01-01
    Description: Water plays a fundamental role in rock weathering processes. Its penetration and movement inside rocks greatly influences the nature and intensity of damage affecting building stones. X-ray computed tomography (CT) is a useful technique for non-destructive mapping of water penetration. For the reported study, CT was used to investigate the internal structure and water penetration patterns for the Piedramuelle Stone, a Cretaceous limestone used as building material in the Oviedo Cathedral (North of Spain). X-ray CT provides good images of the internal structure of the samples: the sedimentary layering due to differences in composition and porosity is clearly seen, as well as other textural features. The movement and penetration rate of water was monitored during standard free absorption water tests. The images that were obtained show a clear difference between dry and wet zones in the interior of the sample. Water movement is related to the petrographic characteristics of the rock, mainly to layering which controls the direction of water penetration. Hounsfield Unit numbers provide a quantitative approach for assessing the penetration rate of water.
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  • 8
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    Laboratory Demonstration of an Infrared-to-Visible Up-Conversion Interferometer for Spatial Coherence Analysis (2008)
    American Physical Society
    Details
    Publication Date: 2008-04-16
    Print ISSN: 0031-9007
    Electronic ISSN: 1079-7114
    Topics: Physics
    Published by American Physical Society
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  • 9
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    Ground-based remote-sensing techniques for diagnosis of the current state and recent evolution of the Monte Perdido Glacier, Spanish Pyrenees (2018)
    Cambridge University Press
    Details
    Publication Date: 2018
    Description: 〈div data-abstract-type="normal"〉〈p〉This work combines very detailed measurements from terrestrial laser scanner (TLS), ground-based interferometry radar (GB-SAR) and ground-penetrating radar (GPR) to diagnose current conditions and to analyse the recent evolution of the Monte Perdido Glacier in the Spanish Pyrenees from 2011 to 2017. Thus, this is currently one of the best monitored small glacier (2) worldwide. The evolution of the glacier surface was surveyed with a TLS evidencing an important decline of 6.1 ± 0.3 m on average, with ice losses mainly concentrated over 3 years (2012, 2015 and 2017). Ice loss is unevenly distributed throughout the study period, with 10–15 m thinning in some areas while unchanged areas in others. GB-SAR revealed that areas with higher ice losses are those that are currently with no or very low ice motion. In contrast, sectors located beneath the areas with less ice loss are those that still exhibit noticeable ice movement (average 2–4.5 cm d〈span〉─1〈/span〉 in summer, and annual movement of 9.98 ma〈span〉─1〈/span〉 from ablation stakes data). GPR informed that ice thickness was generally 〈/p〉〈/div〉
    Print ISSN: 0022-1430
    Electronic ISSN: 1727-5652
    Topics: Geography , Geosciences
    Published by Cambridge University Press on behalf of The International Glaciological Society (IGS).
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  • 10
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    A new cellular function for peroxisomes related to oxygen free radicals? (1990)
    Springer
    Details
    Publication Date: 1990-10-01
    Print ISSN: 0014-4754
    Topics: Biology , Medicine
    Published by Springer
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