Publications (30)80.21 Total impact
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Article: Proteomic identification of a basic peroxidase stabilized within acetylated polymannan polysaccharide of Aloe barbadensis.
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ABSTRACT: Acetylated polymannan polysaccharide (ApmP) isolated from Aloe barbadensis Miller contains a stable peroxidase that was solubilized to investigate its biochemical, electrophoretic, immunological, and proteomic properties. In the electrophoretic band corresponding to the solubilized peroxidase, proteomic analysis detected seven tryptic peptides that matched homologous peptides covering one third of the ATP22a peroxidase of Arabidopsis thaliana. All the characteristics tested indicated that the activity stabilized within the ApmP pertains to the basic secretory peroxidase family, which includes members that have several biotechnological uses. Hence ApmP might yield a widely used peroxidase in stabilized form.Bioscience Biotechnology and Biochemistry 06/2012; 76(6):1169-72. · 1.28 Impact Factor -
Article: Activity, polypeptide and gene identification of thylakoid Ndh complex in trees: potential physiological relevance of fluorescence assays.
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ABSTRACT: Three evergreen (Laurus nobilis, Viburnum tinus and Thuja plicata) and two autumnal abscission deciduous trees (Cydonia oblonga and Prunus domestica) have been investigated for the presence (zymogram and immunodetection) and functionality (post-illumination chlorophyll fluorescence) of the thylakoid Ndh complex. The presence of encoding ndh genes has also been investigated in T. plicata. Western assays allowed tentative identification of zymogram NADH dehydrogenase bands corresponding to the Ndh complex after native electrophoresis of solubilized fractions from L. nobilis, V. tinus, C. oblonga and P. domestica leaves, but not in those of T. plicata. However, Ndh subunits were detected after SDS-PAGE of thylakoid solubilized proteins of T. plicata. The leaves of the five plants showed the post-illumination chlorophyll fluorescence increase dependent on the presence of active Ndh complex. The fluorescence increase was higher in autumn in deciduous, but not in evergreen trees, which suggests that the thylakoid Ndh complex could be involved in autumnal leaf senescence. Two ndhB genes were sequenced from T. plicata that differ at the 350 bp 3' end sequence. Comparison with the mRNA revealed that ndhB genes have a 707-bp type II intron between exons 1 (723 bp) and 2 (729 bp) and that the UCA 259th codon is edited to UUA in mRNA. Phylogenetically, the ndhB genes of T. plicata group close to those of Metasequoia, Cryptomeria, Taxodium, Juniperus and Widdringtonia in the cupresaceae branch and are 5' end shortened by 18 codons with respect to that of angiosperms.Physiologia Plantarum 02/2012; 146(1):110-20. · 3.11 Impact Factor -
Article: Plastid ndh genes in plant evolution.
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ABSTRACT: The plastid ndh genes encode components of the thylakoid Ndh complex which purportedly acts as an electron feeding valve to adjust the redox level of the cyclic photosynthetic electron transporters. During the process of evolution from endosymbiosis to modern chloroplast, most cyanobacterial genes were lost or transferred to nucleus. Eleven ndh genes are among the 150-200 genes remaining in higher plant chloroplast DNA, out of some 3000 genes in the original prokaryotic Cyanobacteria in which homologues to ndh genes encode components of the respiratory Complex I and probably other complexes. The ndh genes are absent in all sequenced plastid DNAs of algae except for the Charophyceae and some Prasinophyceae. With the possible exclusion of some Conifers and Gnetales, the plastid DNA of all photosynthetic land plants contains the ndh genes, whereas they are absent in epiphytic plants that have also lost genes for the photosynthetic machinery. Therefore, the functional role of the ndh genes seems closely related to the land adaptation of photosynthesis. Transcripts of several plastid genes require C to U editing. The ndh genes concentrate about 50% of the editing sites of angiosperm plastid transcripts. Editing sites may be remnants from an ancestor in which a number of T to C inactivating mutations took place in the ndh genes which, during evolution, are being corrected back to T. The comparison of homologous editing sites in the mRNAs of angiosperm ndh genes provides a tool to investigate selective and permissive environmental conditions of past evolutionary events.Plant Physiology and Biochemistry 08/2010; 48(8):636-45. · 2.84 Impact Factor -
Article: Entropy decrease associated to solute compartmentalization in the cell.
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ABSTRACT: We have deduced equations to quantify the entropy associated to the compartmentalization of components in eukaryotic cells as a function of cell and compartment volumes, and of the concentration of solutes. On the basis of known and plausible values of volume and solute concentrations and the deduced equations, we estimate that the contribution of compartmentalization to the decrease of entropy is approximately -14.4 x 10(-14)JK(-1)cell(-1) (-0.7 J K(-1)L(-1)) in the case of Saccharomyces cerevisiae, a typical eukaryotic cell, and approximately -49.6 x 10(-14)JK(-1)cell(-1) (-1.0 J K(-1)L(-1)) in the more complex Chlamydomonas reinhardtii. When compared with other potential contributing factors, such as the informational entropy of DNA and the conformational entropy of proteins, compartmentalization appears as an essential development that significantly decreased the entropy of living cells during biological evolution.Bio Systems 08/2009; 98(1):31-6. · 1.27 Impact Factor -
Article: Functional characterization of the thylakoid Ndh complex phosphorylation by site-directed mutations in the ndhF gene.
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ABSTRACT: To investigate the phosphorylation of the NDH-F subunit of the thylakoid Ndh complex, we constructed three site-directed mutant transgenic tobaccos (Nicotiana tabacum) (T181A, T181S and T181D) in which the (541)ACT(543) triplet encoding the Thr-181 has been substituted by GCT, TCT or GAT encoding alanine, serine and aspartic acid, respectively. Western blots with phospho-threonine antibody detected the 73 kD NDH-F phosphorylated polypeptide in control but not in mutant tobaccos. Differences in Ndh activity, chlorophyll fluorescence and photosynthesis among mutants and control plant demonstrate the key role of the phosphorylation of conserved Thr-181 in the activity and function of the Ndh complex. The substitution of aspartic acid for threonine in T181D mimics the presumable activation effects of the threonine phosphorylation in Ndh activity, post-illumination increase of chlorophyll fluorescence and photosynthesis rapid responses to changing light intensities. A tentative role of the phosphorylation-activated Ndh complex is suggested to poise the redox level and, consequently, optimizing the rate of cyclic electron transport under field conditions.Biochimica et Biophysica Acta 04/2009; 1787(7):920-8. · 4.66 Impact Factor -
Article: Multiple phosphorylation sites in the beta subunit of thylakoid ATP synthase.
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ABSTRACT: Proteomic analyses of the beta subunit of the plastid ATP synthase of barley (Hordeum vulgare L.) revealed that mature protein was not carboxy terminus processed and suggested the correction of the 274 codon (GAT to AAT) in the data bank that was confirmed by DNA sequencing. Six isoforms of the ATP synthase beta subunit with pI ranging from 4.95 to 5.14 were resolved by two-dimensional electrophoresis (2-DE). Mass spectrometry analyses indicated that the six isoforms differ in their phosphorylation degree, which was confirmed by the disappearance of more acidic forms after incubation with the protein phosphatase calcineurin. Six Ser and/or Thr were detected as phosphorylated, among them the conserved Thr-179 that is also phosphorylated in the beta subunit of human mitochondria. The results are discussed in relation with the proposed regulation of the ATP synthase by phosphorylation and 14-3-3 proteins.Photosynthesis Research 08/2006; 89(1):11-8. · 3.24 Impact Factor -
Article: Subchloroplast localization of polypeptides synthesized by chloroplasts during senescence
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ABSTRACT: To study the localization of polypeptides synthesized by isolated senescent chloroplasts we have fractionated the chloroplasts into stroma, envelope and thylakoid components. The validity of the fractionation procedure was tested by assaying both chlorophyll and enzyme markers, as well as the polypeptide composition of each fraction. Plastids in the transition of etioplast to chloroplast, senescent chloroplasts and kinetin-treated chloroplasts produced acceptable fractions, although their polypeptide compositions varied considerably during the ontogeny, particularly those of the envelope. Most of the polypeptides synthesized by isolated senescent chloroplasts were incorporated into the thylakoids except for a 58 kDa polypeptide localized in the stroma and some minor polypeptides present in both stroma and envelope. Although most of the polypeptides synthesized by isolated chloroplasts from kinetin-treated leaves were incorporated into the thylakoid membrane, several polypeptides were found in the stroma (90, 80, 65 and 54 kDa) and in the envelope (100, 75, 48 and 28–30 kDa). The results indicate that early in senescence, the polypeptides of the envelope change but, that probably, most of the new polypeptides are synthesized in the cytoplasm.Physiologia Plantarum 04/2006; 75(3):382 - 388. · 3.11 Impact Factor -
Article: Protein synthesis by chloroplasts during the senescence of barley leaves
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ABSTRACT: Chloroplasts were isolated from senescent leaf segments of barley (Hordeum vulgare L. var. Mozoncillo) and assayed for protein synthesis. Protein synthesis activity of the chloroplasts greatly increased after 10–20 h of incubation of leaf segments in the dark in spite of an intense degradation of chloroplast rRNA. The rise in the activity of protein synthesis was more pronounced when kinetin was present in the incubation medium. However, as deduced from SDS-polyacrylamide gel electrophoresis of the products, different proteins were synthesized under the two conditions of incubation of the leaf segments. The activity of protein synthesis of the chloroplasts decreased during the first hours of incubation of the leaf segments in the light.Cutting and incubation in the dark of the leaf segments enhanced the synthesis of a few proteins also formed by chloroplasts in attached senescing leaves. Hormone and senescence treatments changed the type and the rate of the protein synthesized by chloroplasts, which suggests that hormones may control senescence through a modulation of the protein synthesized by the chloroplasts.Physiologia Plantarum 04/2006; 57(2):260 - 266. · 3.11 Impact Factor -
Article: Control by phytochrome of the synthesis of protein related to senescence in chloroplasts of barley (Hordeum vulgare)
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ABSTRACT: Protein synthesis has been measured in chloroplast isolated from detached leaves of barley (Hordeum vulgare L. cv. Hassan). The effects of hormone and light treatments of the leaves on chloroplast protein synthesis have been compared with effects on other senescence symptoms. Interruption of the dark with red light retards senescence and increases chloroplast protein synthesis. The effect of red light was reversed by far-red light. Red light did not act additively with kinetin, and it competed with ethylene and abscisic acid, accelerators of senescence, which decreased protein synthesis. In contrast to the interruption of the dark with red light, continuous light decreased chloroplast protein synthesis. It may be concluded effects on chloroplast protein synthesis. The retardation of senescence by continuous light is not necessarily related to Pu Instead, energy provided by photosynthesis may be an important factor.Physiologia Plantarum 04/2006; 71(3):341 - 344. · 3.11 Impact Factor -
Article: Are organisms committed to lower their rates of entropy production? Possible relevance to evolution of the Prigogine theorem and the ergodic hypothesis.
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ABSTRACT: The physiology at limiting and stress conditions challenges the current view that the overall reaction of metabolic processes is always far from equilibrium and, therefore, that organisms are not committed to lower their rates of entropy production. Plausibly, critical steps of natural selection takes place at limiting conditions, near equilibrium, in the linear range response of entropy production, and consequently the trend to lower the rate of entropy production could be the fitness arrow of biological evolution. The evolutionary relevance of the Prigogine theorem is discussed in connection with the ergodic hypothesis of Boltzmann. The emergence of metabolic strategies to economise carbon/energy resources, of resource-waste systems like active transport and the irreversible increase in the complexity of organisms during evolution may be consequences of a more general trend of metabolic systems to lower the rates of entropy production.Biosystems 02/2006; 83(1):10-7. · 1.78 Impact Factor -
Article: Editing of plastid RNA in Arabidopsis thaliana ecotypes.
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ABSTRACT: Post-transcriptional maturation of plastid-encoded mRNAs from land plants includes editing by making cytidine to uridine alterations at highly specific positions; this usually restores codon identities for conserved amino acids that are important for the proper function of the affected proteins. In contrast to the rather constant number of editing sites their location varies greatly, even between closely related taxa. Here, we experimentally determined the specific pattern of editing sites (the editotype) of the plastid genome of Arabidopsis thaliana ecotype Columbia (Col-0). Based on phylogenetic analyses of plastid open reading frames, we identified 28 editing sites. Two editing events in the genes matK and ndhB seem to have evolved late during the evolution of flowering plants. Strikingly, they are embedded in almost identical sequence elements and seem to be phylogenetically co-processed. This suggests that the two sites are recognized by the same trans-factor, which could help to explain the hitherto enigmatic gain of editing sites in evolution. In order to trace variations in editotype at the subspecies level we examined two other A. thaliana accessions, Cape Verde Islands (Cvi-0) and Wassilewskija (Ws-2), for the Col-0 editing sites. Both Cvi-0 and Ws-2 possess and process the whole set of editing sites as determined in Col-0, but the consequences of RNA editing differ at one position between the ecotypes.The Plant Journal 10/2005; 43(5):708-15. · 6.16 Impact Factor -
Article: Involvement of the thylakoidal NADH-plastoquinone-oxidoreductase complex in the early responses to ozone exposure of barley (Hordeum vulgare L.) seedlings.
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ABSTRACT: A possible implication of the plastid NADH-plastoquinone-oxidoreductase (Ndh) complex in the response against ozone-mediated oxidative stress in barley (Hordeum vulgare L.) leaves was investigated. After a 4 h treatment, exposure of barley seedlings to moderate ozone concentrations produced leaf-age-dependent increases in lipid peroxidation, peroxidase, and Ndh complex activities in the thylakoid membranes. A significant amount and activity of the Ndh complex were detected in mature barley leaves, but not in young barley leaves. In fact, young barley leaves behaved like ndh-deficient leaves in most of the aspects studied. When plants were exposed to photo-oxidative light after ozone fumigation, the recovery of Fv/Fm was lower in young leaves than in mature leaves. Ozone treatment significantly decreased non-photochemical quenching (qN) in young leaves, but not in mature leaves. Mature leaves showed higher levels of the energy (DeltamuH+) dependent (qE) component of qN. Treatment with antimycin A, an inhibitor of cyclic electron flow, increased the decay of qN produced by ozone in young leaves, but not in mature ones. The reduction state of plastoquinone increased after ozone treatment in mature dark-adapted leaves and was strongly quenched by far red light. It is proposed that the function of the Ndh complex helps the maintenance of qN, probably through the poising of the redox steady-state level of the intersystem carriers and then by optimizing the rate of cyclic electron flow. This should constitute an age-dependent early response in barley leaves, by contributing to minimize photoinhibition in the presence of ozone and high light.Journal of Experimental Botany 02/2005; 56(409):205-18. · 5.36 Impact Factor -
Article: Topology of the plastid Ndh complex and its NDH-F subunit in thylakoid membranes.
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ABSTRACT: We have investigated the topologies of Ndh (a plastid complex with NADH dehydrogenase activity) and its NDH-F subunit in thylakoids by trypsin and proteinase V8 digestion of both intact and Triton X-100-permeabilized barley thylakoids and identification of the products with antibodies against specific sequences of the NDH-A, NDH-K and NDH-F subunits. Antibody binding and protection against proteinases were also assayed. The analysis of the digestion products of NDH-F by immunodetection and matrix-assisted laser-desorption ionization-time-of-flight allowed us to propose its membrane topology and to compare it with bioinformatic predictions and with that of the homologous subunit (ND5/NuoL/NQO12) of the respiratory complex I. Results indicate that the thylakoid Ndh complex may have an L-shaped structure, similar to that of respiratory complex I, with the hydrophilic arm orientated towards the stroma and the hydrophobic arm inserted into the thylakoid. NDH-A and NDH-K may be located at the bridge between the two arms. Similar to ND5/NuoL/NQO12 of complex I, NDH-F must be distally located in the hydrophobic arm. NDH-F would include up to 15 transmembrane helices and 14 hydrophilic regions. A conserved His-349 in the X transmembrane helix could be involved in H+ pumping. The conserved Thr-181 NDH-F, whose probable phosphorylation increases the activity of the Ndh complex, is located within the hydrophilic region between the V and VI transmembrane helices.Biochemical Journal 09/2004; 382(Pt 1):145-55. · 4.90 Impact Factor -
Article: The activity of the chloroplastic Ndh complex is regulated by phosphorylation of the NDH-F subunit.
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ABSTRACT: Hydrogen peroxide (H(2)O(2)) induces increases, to different degrees, in transcripts, protein levels, and activity of the Ndh complex (EC 1.6.5.3). In the present work, we have compared the effects of relatively excess light, H(2)O(2), dimethylthiourea (a scavenger of H(2)O(2)), and/or EGTA (a Ca(2+) chelator) on the activity and protein levels of the Ndh complex of barley (Hordeum vulgare cv Hassan) leaf segments. The results show the involvement of H(2)O(2) in the modulation of both the protein level and activity of the Ndh complex and the participation of Ca(2+) mainly in the activity regulation of pre-existing protein. Changes in Ndh complex activity could not be explained only by changes in Ndh protein levels, suggesting posttranslational modifications. Hence, we investigate the possible phosphorylation of the Ndh complex both in thylakoids and in the immunopurified Ndh complex using monoclonal phosphoamino acid antibodies. We demonstrate that the Ndh complex is phosphorylated in vivo at threonine residue(s) of the NDH-F polypeptide and that the level of phosphorylation is closely correlated with the Ndh complex activity. The emerging picture is that full activity of the Ndh complex is reached by phosphorylation of its NDH-F subunit in a H(2)O(2)- and Ca(2+)-mediated action.Plant physiology 06/2003; 132(1):256-62. · 6.53 Impact Factor -
Article: Post-transcriptional control of chloroplast gene expression. Accumulation of stable psaC mRNA is due to downstream RNA cleavages in the ndhD gene.
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ABSTRACT: Intergenic cleavages, intron splicing, and editing of primary transcripts of the plastid ndhH-D operon produce multiple overlapping RNAs, of which the most abundant by far is the monocistronic 400-nucleotide mRNA of psaC (encoding the PsaC protein of photosystem I), in contrast with the low level of transcripts of the six ndh genes. Like other plastid operons containing genes for functionally unrelated proteins, the contrasting accumulation of ndh and psaC transcripts provides a model to investigate the mechanisms of the post-transcriptional control of gene expression, a feature of chloroplast genetic machinery, with a minimum of interference by transcriptional control. In leek (Allium porrum L), the ndhD transcript (which follows the psaC gene and ends the ndhH-D operon) requires C --> U editing to restore its start codon and may be used as a marker for the processing of psaC and ndhD transcripts. By determining the editing state and 5' end sequences of specific transcripts, we demonstrated that stable monocistronic psaC mRNA results from downstream cleavages in the ndhD sequence, which renders non-functional ndhD transcripts as by-products. Alternative psaC-ndhD intergenic cleavages produce complete mRNAs for both genes, but only take place in precursors containing editing-restored ndhD start codons. Hence, post-transcriptional control acts by promoting the ndhD cleavage alternative, which allows the accumulation of psaC mRNA at the expense of ndhD mRNA levels.Journal of Biological Chemistry 10/2002; 277(39):36457-64. · 4.77 Impact Factor -
Article: Age-related loss of rooting capability in Arabidopsis thaliana and its reversal by peptides containing the Arg-Gly-Asp (RGD) motif.
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ABSTRACT: We describe here an experimental system to study the age-related decline of adventitious root formation in Arabidopsis thaliana L. (Heynh), ecotype Landsberg erecta (Ler). The system is based on the different rooting capacity of hypocotyls from de-rooted juvenile (12-day-old) and adult (26-day-old) plants. Hypocotyls from de-rooted juvenile plants rooted readily within a week of culture, and the rooting process was not dependent on exogenous auxin. In contrast, hypocotyls from de-rooted adult plants rooted poorly and only after longer periods of time. Exogenously applied auxin had no effect on rooting of hypocotyls from de-rooted adult plants. Rooting capacity, although correlated with the transition to flowering, did not depend on this transition. Root induction declined in a similar manner when the transition to flowering was delayed, either genetically with the fve mutant or physiologically with short days. The results showed that rooting of hypocotyls from de-rooted adult plants depended on the effect of peptides containing the RGD motif. Both the percentage of rooting and the number of roots were largely increased when the hypocotyls were treated transiently with the RGD peptide. The effect of the RGD peptide was a necessary, but not sufficient, condition for rooting of hypocotyls from de-rooted adult plants.Physiologia Plantarum 05/2002; 114(4):601-607. · 3.11 Impact Factor -
Article: Differential leaf stress responses in young and senescent plants.
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ABSTRACT: Responses to low temperature, mechanical wounding and salicylic acid (SA) treatments were studied in 3-week-old (young) and 6-week-old (senescent) Arabidopsis thaliana (L.) Heynh. plants by analyzing increases in Pal1 and Pr1 expression and superoxide dismutase (SOD; EC 1.15.1.1) and peroxidase (POX; EC 1.11.1.7) activities. Young plants showed higher Pal1 transcript accumulation after low temperature and wounding. In contrast, senescent plants presented higher accumulation of Pr1 transcripts after SA treatments. Similar results were obtained with the ethylene-insensitive etr1 mutant, suggesting that these differences are not related to increased ethylene content in senescent tissues. SOD activity and inducibility were lower, whereas POX activity and inducibility were higher in senescent plants. A possible relationship between senescence-associated changes in responses to stress and in the metabolism of active oxygen species is discussed.Physiologia Plantarum 12/2001; 113(3):409-415. · 3.11 Impact Factor -
Article: Chlororespiration and Poising of Cyclic Electron Transport
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ABSTRACT: Polypeptides encoded by plastid ndhgenes form a complex (Ndh) which could reduce plastoquinone with NADH. Through a terminal oxidase, reduced plastoquinone would be oxidized in chlororespiration. However, isolated Ndh complex has low activity with plastoquinone and no terminal oxidase has been found in chloroplasts, thus the function of Ndh complex is unknown. Alternatively, thylakoid hydroquinone peroxidase could oxidize reduced plastoquinone with H2O2. By immunoaffinity chromatography, we have purified the plastid Ndh complex of barley (Hordeum vulgareL.) to investigate the electron donor and acceptor specificity. A detergent-containing system was reconstructed with thylakoid Ndh complex and peroxidase which oxidized NADH with H2O2 in a plastoquinone-dependent process. This system and the increases of thylakoid Ndh complex and peroxidase activities under photooxidative stress suggest that the chlororespiratory process consists of the sequence of reactions catalyzed by Ndh complex, peroxidase (acting on reduced plastoquinone), superoxide dismutase, and the non-enzymic one-electron transfer from reduced iron-sulfur protein (FeSP) to O2. When FeSP is a component of cytochrome b 6·fcomplex or of the same Ndh complex, O2 may be reduced with NADH, without requirement of light. Chlororespiration consumes reactive species of oxygen and, eventually, may decrease their production by lowering O2 concentration in chloroplasts. The common plastoquinone pool with photosynthetic electron transport suggests that chlororespiratory reactions may poise reduced and oxidized forms of the intermediates of cyclic electron transport under highly fluctuating light intensities.Journal of Biological Chemistry 01/2000; 275(2):942-948. · 4.77 Impact Factor -
Article: Effects of growth regulators and light on chloroplasts NAD(P)H dehydrogenase activities of senescent barley leaves
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ABSTRACT: The activities NADH and NADPH dehydrogenases were measured with ferricyanide as electron-acceptor (NADH-FeCN-ox and NADPH-FeCN-ox, respectively) in mitochondria-free chloroplasts of barley leaf segments after receiving various treatments affecting senescence. NADPH-FeCN-ox declined during senescence in the dark, in a way similar to chlorophyll and Hill reaction, and increased when leaf segments were incubated at light. These results suggest that NADPH-FeCN-ox is related to some photosynthetic electron transporter activity (probably ferredoxin-NADP+ oxidoreductase). In contrast, NADH-FeCN-ox is notably stable during senescence in the dark and at light. This activity increased during incubation with kinetin or methyl-jasmonate (Me-JA) but decreased when leaf segments were treated with abscisic acid (ABA). The effects of the inhibitors of protein synthesis cycloheximide and chloramphenicol suggest that the changes of NAD(P)H dehydrogenase activities may depend on protein synthesis in chloroplasts. In senescent leaf, chloroplast NADH dehydrogenase might be a way to dissipate NADH produced in the degradation of excess carbon which is released from the degradation of amino acids.Plant Growth Regulation 10/1995; 17(3):225-232. · 1.60 Impact Factor -
Article: Translational control of chloroplast protein synthesis during senescence of barley leaves
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ABSTRACT: A light-driven homologous system for the translation of chloroplast mRNA has been prepared from chloroplasts isolated from senescent barley leaves and treated with micrococcal nuclease. We have investigated the potential of this system for studies on translational specificity. Chloroplast mRNAs from senescent and kinetin-treated leaves have been translated in the homologous system and the products have been compared with the polypeptides synthesized by intact chloroplasts isolated from senescent and kinetin-treated leaves. Isolated intact chloroplasts from senescent barley leaves specifically synthesized polypeptides of: 80,66,58,50,48 and 35 kDa but did not synthesize the 54 kDa large subunit of ribulose-1, 5-bisphosphate carboxylase oxygenase. Chloroplasts isolated from leaves treated for 18 h with kinetin specifically synthesized polypeptides of: 85,75 and 54 kDa. Several polypeptides (40,32,25 and 18 kDa) are synthesized by chloroplasts of both senescent and kinetin-treated leaves. The homologous translation system derived from senescent chloroplasts synthesized only senescence polypeptides whether it was supplied with chloroplast mRNA from senescent leaves or leaves treated with kinetin for 18 h. The homologous translation system derived from chloroplasts of kinetin-treated leaves synthesized either senescence polypeptides or kinetin-induced polypeptides depending on the source of chloroplast mRNA, senescent leaves or leaves treated with kinetin, respectively. The results indicate that kinetin controls chloroplast gene expression in senescent leaves at both the transcriptional and translational level.Physiologia Plantarum 02/1989; 75(3):374 - 381. · 3.11 Impact Factor
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Institutions
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1984–2012
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Universidad de Alcalá
- • Departamento de Biología Vegetal
- • Facultad de Biología
Alcalá de Henares, Madrid, Spain
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1995
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Universidad de Murcia
- Facultad de Biología
Murcia, Murcia, Spain
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