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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
    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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  • 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
    Copper-binding proteins and copper tolerance in Pisam sativum L. (1990)
    Springer
    Planta 181 (1990), S. 487-495 
    Details
    ISSN: 1432-2048
    Keywords: Copper-binding protein (characterization) ; Copper sensitivity, tolerance ; Metal toxicity ; Pisum (copper tolerance)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of high nutrient levels of copper on the low-molecular-weight copper-proteins of leaves from plants of two cultivars of Pisum sativum L., with different sensitivity to copper, was investigated. Gel-filtration chromatography of leaf extracts from Cu-tolerant and Cu-sensitive plants grown with 1 μM Cu(II), showed the presence of only two copper peaks (I and II), but growth of plants with 240 μM Cu(II) induced two additional copper fractions (III and IV). Fractions II and III were purified by solvent extraction, gel-filtration and ion-exchange chromatography, and their molecular weights, subunit sizes, absorption spectra, metalprotein stoichiometry and amino-acid contents were determined. Fraction II was a polypeptide of Mr 15000 composed of a single chain. The purification of fraction III produced a copper-containing fraction (III-1) of Mr 3700, and a copper-protein (III-2) with an Mr, by sodium dodecyl sulfate-urea-polyacrylamide gel electrophoresis, of 66000. The metal contents of fractions III-1 and III-2 were higher in Cu-tolerant than in Cu-sensitive plants. On the basis of amino-acid analyses, fraction III-1 appeared to be complexes of Cu(II)-poly-isoleucine and Cu(II)-poly-leucine. The results rule out the existence, in pea leaves, of any protein similar to either animal metallothioneins or to any of the low-molecularweight metal-binding proteins or peptides described in other plants and reported to be involved in metal tolerance. In the mechanism of copper tolerance at the leaf level, fractions III-1 (Mr 3700), III-2 (Mr 66000), and IV (Mr 2000) appear to have a role, fraction IV being specifically induced in the tolerant cultivar by Cu(II). Fractions III-1 and III-2 could participate in a different mechanism, adaptive in character, involving an enhanced capacity to bind copper in Cu-tolerant plants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00193001
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  • 5
    Electronic Resource
    Electronic Resource
    A new cellular function for peroxisomes related to oxygen free radicals? (1990)
    Springer
    Cellular and molecular life sciences 46 (1990), S. 989-992 
    Details
    ISSN: 1420-9071
    Keywords: Oxygen free radicals ; superoxide ; superoxide dismutase ; peroxisomes ; cellular metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Although in cell biology peroxisomes are still ‘young’ organelles, it is becoming increasingly clear that they are involved in important cellular functions. Recent results have indicated the presence of the metalloenzyme superoxide dismutase in peroxisomes and the production of superoxide free radicals (O 2 − ) in these oxidative organelles. These findings, together with other experimental evidence, point towards the existence of new roles for peroxisomes in cellular active oxygen metabolism, something that has a potential impact in multiple areas of cell biology, particularly in biochemistry and biomedicine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01940651
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  • 6
    Electronic Resource
    Electronic Resource
    On the use of fluorescent dyes for concentration measurements in water flows (1990)
    Springer
    Experiments in fluids 10 (1990), S. 177-180 
    Details
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract An experiment was performed to evaluate the characteristics of various fluorescent dyes used as tracers for concentration measurements in water flows, by laser induced fluorescence. Three common fluorescent dyes (fluorescein, rhodamine B and rhodamine 6G) were used, to select the most suitable fluorescent dye and identify its range of linear response. The results showed that, in terms of the stability of the solution, fluorescein is inferior to either rhodamine B or rhodamine 6G and that for concentrations of rhodamine B less than 0.08 mg/1 the response of fluorescent to the incident light is linear.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00215028
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