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Luis A del Río

Publications and source records attributed to Luis A del Río.

12 recordsLinked to original sources
PubMed2006

The expression of different superoxide dismutase forms is cell-type dependent in olive (Olea europaea L.) leaves.

Superoxide dismutase (SOD) is a key antioxidant enzyme present in prokaryotic and eukaryotic cells as a first line of defense against the accumulation of superoxide radicals. In olive leaves, the SOD enzymatic system was characterized and was found to be comprised of three isozymes, an Mn-SOD, an Fe-SOD and a CuZn-SOD. Transcript expression analysis of whole leaves showed that the three isozymes represented 82, 17 and 0.8% of the total SOD expressed, respectively. Using the combination of laser capture microdissection (LCM) and real-time quantitative reverse transcription-PCR (RT-PCR), the expression of these SOD isozymes was studied in different cell types of olive leaves, including spongy mesophyll, palisade mesophyll, xylem and phloem. In spongy mesophyll cells, the isozyme proportion was similar to that in whole leaves, but in the other cells the proportion of expressed SOD isozymes was different. In palisade mesophyll cells, Fe-SOD was the most abundant, followed by Mn-SOD and CuZn-SOD, but in phloem cells Mn-SOD was the most prominent isozyme, and Fe-SOD was present in trace amounts. In xylem cells, only the Mn-SOD was detected. On the other hand, the highest accumulation of superoxide radicals was localized in vascular tissue which was the tissue with the lowest level of SOD transcripts. These data show that in olive leaves, each SOD isozyme has a different gene expression depending on the cell type of the leaf.

DNA, Plant↗
PubMed2006

Antioxidative enzymes from chloroplasts, mitochondria, and peroxisomes during leaf senescence of nodulated pea plants.

In this work the influence of the nodulation of pea (Pisum sativum L.) plants on the oxidative metabolism of different leaf organelles from young and senescent plants was studied. Chloroplasts, mitochondria, and peroxisomes were purified from leaves of nitrate-fed and Rhizobium leguminosarum-nodulated pea plants at two developmental stages (young and senescent plants). In these cell organelles, the activity of the ascorbate-glutathione cycle enzymes ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), and glutathione reductase (GR), and the ascorbate and glutathione contents were determined. In addition, the total superoxide dismutase (SOD) activity, the pattern of mitochondrial and peroxisomal NADPH-generating dehydrogenases, some of the peroxisomal photorespiratory enzymes, the glyoxylate cycle and oxidative metabolism enzymes were also analysed in these organelles. Results obtained on the metabolism of cell organelles indicate that nodulation with Rhizobium accelerates senescence in pea leaves. A considerable decrease of the ascorbate content of chloroplasts, mitochondria, and peroxisomes was found, and in these conditions a metabolic conversion of leaf peroxisomes into glyoxysomes, characteristic of leaf senescence, took place.

Aging↗
PubMed2006

Localization of S-nitrosoglutathione and expression of S-nitrosoglutathione reductase in pea plants under cadmium stress.

S-nitrosoglutathione (GSNO) is considered a natural nitric oxide (NO.) reservoir and a reactive nitrogen intermediate in animal cells, but little is known about this molecule and its metabolism in plant systems. In this work, using pea plants as a model system, the presence of GSNO in collenchyma cells was demonstrated by an immunohistochemical method. When pea plants were grown with a toxic Cd concentration (50 microM) the content of GSNO in collenchyma cells was drastically reduced. Determination of the nitric oxide (NO.) and gluthathione contents in leaves by confocal laser scanning microscopy and HPLC, respectively, showed a marked decrease of both compounds in plants treated with cadmium. The analysis of the S-nitrosoglutathione reductase (GSNOR) activity and its transcript expression in leaves showed a reduction of 31% by cadmium. These results indicate that GSNO is associated with a specific plant cell type, and this metabolite and its related catabolic activity, GSNOR, are both down-regulated under Cd stress.

Cadmium↗
PubMed2006

Constitutive arginine-dependent nitric oxide synthase activity in different organs of pea seedlings during plant development.

Nitric oxide (NO) is an important signalling molecule in different animal and plant physiological processes. Little is known about its biological function in plants and on the enzymatic source or site of NO production during plant development. The endogenous NO production from L-arginine (NO synthase activity) was analyzed in leaves, stems and roots during plant development, using pea seedlings as a model. NOS activity was analyzed using a novel chemiluminescence-based assay which is more sensitive and specific than previous methods used in plant tissues. In parallel, NO accumulation was analyzed by confocal laser scanning microscopy using as fluorescent probes either DAF-2 DA or DAF-FM DA. A strong increase in NOS activity was detected in stems after 11 days growth, coinciding with the maximum stem elongation. The arginine-dependent NOS activity was constitutive and sensitive to aminoguanidine, a well-known irreversible inhibitor of animal NOS, and this NOS activity was differentially modulated depending on the plant organ and seedling developmental stage. In all tissues studied, NO was localized mainly in the vascular tissue (xylem) and epidermal cells and in root hairs. These loci of NO generation and accumulation suggest novel functions for NO in these cell types.

Arginine↗
PubMed2005

Peroxisomal monodehydroascorbate reductase. Genomic clone characterization and functional analysis under environmental stress conditions.

In plant cells, ascorbate is a major antioxidant that is involved in the ascorbate-glutathione cycle. Monodehydroascorbate reductase (MDAR) is the enzymatic component of this cycle involved in the regeneration of reduced ascorbate. The identification of the intron-exon organization and the promoter region of the pea (Pisum sativum) MDAR 1 gene was achieved in pea leaves using the method of walking polymerase chain reaction on genomic DNA. The nuclear gene of MDAR 1 comprises nine exons and eight introns, giving a total length of 3,770 bp. The sequence of 544 bp upstream of the initiation codon, which contains the promoter and 5' untranslated region, and 190 bp downstream of the stop codon were also determined. The presence of different regulatory motifs in the promoter region of the gene might indicate distinct responses to various conditions. The expression analysis in different plant organs by northern blots showed that fruits had the highest level of MDAR. Confocal laser scanning microscopy analysis of pea leaves transformed with Agrobacterium tumefaciens having the binary vectors pGD, which contain the autofluorescent proteins enhanced green fluorescent protein and enhanced yellow fluorescent protein with the full-length cDNA for MDAR 1 and catalase, indicated that the MDAR 1 encoded the peroxisomal isoform. The functional analysis of MDAR by activity and protein expression was studied in pea plants grown under eight stress conditions, including continuous light, high light intensity, continuous dark, mechanical wounding, low and high temperature, cadmium, and the herbicide 2,4-dichlorophenoxyacetic acid. This functional analysis is representative of all the MDAR isoforms present in the different cell compartments. Results obtained showed a significant induction by high light intensity and cadmium. On the other hand, expression studies, performed by semiquantitative reverse transcription-polymerase chain reaction demonstrated differential expression patterns of peroxisomal MDAR 1 transcripts in pea plants grown under the mentioned stress conditions. These findings show that the peroxisomal MDAR 1 has a differential regulation that could be indicative of its specific function in peroxisomes. All these biochemical and molecular data represent a significant step to understand the specific physiological role of each MDAR isoenzyme and its participation in the antioxidant mechanisms of plant cells.

2,4-Dichlorophenoxyacetic Acid↗
PubMed2004

Cellular and subcellular localization of endogenous nitric oxide in young and senescent pea plants.

The cellular and subcellular localization of endogenous nitric oxide (NO.) in leaves from young and senescent pea (Pisum sativum) plants was studied. Confocal laser scanning microscopy analysis of pea leaf sections with the fluorescent probe 4,5-diaminofluorescein diacetate revealed that endogenous NO. was mainly present in vascular tissues (xylem and phloem). Green fluorescence spots were also detected in the epidermal cells, palisade and spongy mesophyll cells, and guard cells. In senescent leaves, NO. generation was clearly reduced in the vascular tissues. At the subcellular level, by electron paramagnetic resonance spectroscopy with the spin trap Fe(MGD)(2) and fluorometric analysis with 4,5-diaminofluorescein diacetate, NO. was found to be an endogenous metabolite of peroxisomes. The characteristic three-line electron paramagnetic resonance spectrum of NO., with g = 2.05 and a(N) = 12.8 G, was detected in peroxisomes. By fluorometry, NO. was also found in these organelles, and the level measured of NO. was linearly dependent on the amount of peroxisomal protein. The enzymatic production of NO. from l-Arg (nitric oxide synthase [NOS]-like activity) was measured by ozone chemiluminiscence. The specific activity of peroxisomal NOS was 4.9 nmol NO. mg(-1) protein min(-1); was strictly dependent on NADPH, calmodulin, and BH(4); and required calcium. In senescent pea leaves, the NOS-like activity of peroxisomes was down-regulated by 72%. It is proposed that peroxisomal NO. could be involved in the process of senescence of pea leaves.

Animals↗
PubMed2004

Nitric oxide and nitric oxide synthase activity in plants.

Research on NO in plants has gained considerable attention in recent years mainly due to its function in plant growth and development and as a key signalling molecule in different intracellular processes in plants. The NO emission from plants is known since the 1970s, and now there is abundant information on the multiple effects of exogenously applied NO on different physiological and biochemical processes of plants. The physiological function of NO in plants mainly involves the induction of different processes, including the expression of defence-related genes against pathogens and apoptosis/programmed cell death (PCD), maturation and senescence, stomatal closure, seed germination, root development and the induction of ethylene emission. NO can be produced in plants by non-enzymatic and enzymatic systems. The NO-producing enzymes identified in plants are nitrate reductase, and several nitric oxide synthase-like activities, including one localized in peroxisomes which has been biochemically characterized. Recently, two genes of plant proteins with NOS activity have been isolated and characterized for the first time, and both proteins do not have sequence similarities to any mammalian NOS isoform. However, different evidence available indicate that there are other potential enzymatic sources of NO in plants, including xanthine oxidoreductase, peroxidase, cytochrome P450, and some hemeproteins. In plants, the enzymatic production of the signal molecule NO, either constitutive or induced by different biotic/abiotic stresses, may be a much more common event than was initially thought.

Nitric Oxide↗
PubMed2003

Peroxisomes from pepper fruits (Capsicum annuum L.): purification, characterisation and antioxidant activity.

Pepper is a vegetable of importance in human nutrition. Currently, one of the most interesting properties of natural products is their antioxidant content. In this work, the purification and characterisation of peroxisomes from fruits of a higher plant was carried out, and their antioxidative enzymatic and non-enzymatic content was investigated. Green and red pepper fruits (Capsicum annuum L., type Lamuyo) were used in this study. The analysis by electron microscopy showed that peroxisomes from both types of fruits contained crystalline cores which varied in shape and size, and the presence of chloroplasts and chromoplasts in green and red pepper fruits, respectively, was confirmed. Peroxisomes were purified by differential and sucrose density-gradient centrifugations. In the peroxisomal fractions, the activity of the photorespiration, beta-oxidation and glyoxylate cycle enzymes, and the ROS-related enzymes catalase, superoxide dismutase, xanthine oxidase, glutathione reductase and NADP(+)-dehydrogenases, was determined. Most enzymes studied had higher specific activity and protein content in green than in red fruits. By native PAGE and western blot analysis, the localisation of a Mn-SOD in fruit peroxisomes was demonstrated. The ascorbate and glutathione levels were also determined in crude extracts and in peroxisomes purified from both green and red peppers. The total ascorbate content (200-220 mg per 100 g FW) was similar in crude extracts from the two types of fruits, but higher in peroxisomes from red peppers. The glutathione concentration was 2-fold greater in green pepper crude extracts than in red fruits, whereas peroxisomes from both tissues showed similar values. The presence in pepper peroxisomes of different antioxidative enzymes and their corresponding metabolites implies that these organelles might be an important pool of antioxidants in fruit cells, where these enzymes could also act as modulators of signal molecules (O2*-, H202) during fruit maturation.

Antioxidants↗
PubMed2003

Plant peroxisomes, reactive oxygen metabolism and nitric oxide.

In plant cells, as in most eukaryotic organisms, peroxisomes are probably the major sites of intracellular H2O2 production, as a result of their essentially oxidative type of metabolism. Like mitochondria and chloroplasts, peroxisomes also produce superoxide radicals (O2*-) and there are, at least, two sites of superoxide generation: one in the organelle matrix, the generating system being xanthine oxidase, and another site in the peroxisomal membranes dependent on NAD(P)H. In peroxisomal membranes, three integral polypeptides (PMPs) with molecular masses of 18, 29, and 32 kDa have been shown to generate O2*- radicals. Besides catalase, several antioxidative systems have been demonstrated in plant peroxisomes, including different superoxide dismutases, the four enzymes of the ascorbate-glutathione cycle plus ascorbate and glutathione, and three NADP-dependent dehydrogenases. A CuZn-SOD and two Mn-SODs have been purified and characterized from different types of plant peroxisomes. The presence of the enzyme nitric oxide synthase (NOS) and its reaction product, nitric oxide (NO*), has been recently demonstrated in plant peroxisomes. Different experimental evidence has suggested that peroxisomes have a ROS-mediated cellular function in leaf senescence and in stress situations induced by xenobiotics and heavy metals. Peroxisomes could also have a role in plant cells as a source of signal molecules like NO*, O2*- radicals, H2O2, and possibly S-nitrosoglutathione (GSNO). It seems reasonable to think that a signal molecule-producing function similar to that postulated for plant peroxisomes could also be performed by human, animal and yeast peroxisomes, where research on oxy radicals, antioxidants and nitric oxide is less advanced than in plant peroxisomes.

Nitric Oxide↗
PubMed2003

Mitochondrial and peroxisomal manganese superoxide dismutase: differential expression during leaf senescence.

In pea (Pisum sativum L.) leaves, manganese superoxide dismutase (Mn-SOD) is mainly localized in mitochondria as well as in peroxisomes. In this work, the effect of leaf senescence on the peroxisomal and mitochondrial Mn-SOD was studied in detached leaves from pea plants which were incubated in the dark at 25 degrees C for 3-11 d. Northern blots hybridized with a cDNA encoding mitochondrial Mn-SOD from pea leaves and a mitochondrial Mn-SOD transit peptide-specific probe showed increased Mn-SOD transcript levels during leaf senescence, due in part to in creased mitochondrial Mn-SOD mRNA. Recombinantly-expressed mitochondrial Mn-SOD was used to raise polyclonal antibodies which cross-reacted with Mn-SOD in peroxisomes purified from pea leaves. Western blot assays of crude extracts with the antibodies to pea mitochondrial Mn-SOD showed that the levels of total Mn-SOD protein gradually increased with leaf senescence. By native PAGE, the total Mn-SOD activity of pea leaves increased with senescence. EM immunocytochemistry was used to distinguish mitochondrial and peroxisomal Mn-SOD in senescent leaves. Increased Mn-SOD labelling in mitochondria was intensified, whereas the immunogold labelling of peroxisomes did not change with senescence. Overall, these results show that mitochondrial and peroxisomal Mn-SOD expression is regulated differently. The expression of mitochondrial Mn-SOD is induced during the senescence of pea leaves, whereas peroxisomal Mn-SOD could be post-translationally activated. Previously described results showing decreased mitochondrial Mn-SOD activity and increased peroxisomal Mn-SOD activity may be reflective of post-translational events regulating enzymatic activity during leaf senescence.

Apoptosis↗
PubMed2002

Reactive oxygen species, antioxidant systems and nitric oxide in peroxisomes.

Peroxisomes are subcellular organelles with an essentially oxidative type of metabolism. Like chloroplasts and mitochondria, plant peroxisomes also produce superoxide radicals (O2*(-)) and there are, at least, two sites of superoxide generation: one in the organelle matrix, the generating system being xanthine oxidase, and another site in the peroxisomal membranes dependent on NAD(P)H. In peroxisomal membranes, three integral polypeptides (PMPs) with molecular masses of 18, 29 and 32 kDa have been shown to generate radicals O2*(-). Besides catalase, several antioxidative systems have been demonstrated in plant peroxisomes, including different superoxide dismutases, the ascorbate-glutathione cycle, and three NADP-dependent dehydrogenases. A CuZn-SOD and two Mn-SODs have been purified and characterized from different types of peroxisomes. The four enzymes of the ascorbate-glutathione cycle (ascorbate peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase, and glutathione reductase) as well as the antioxidants glutathione and ascorbate have been found in plant peroxisomes. The recycling of NADPH from NADP(+) can be carried out in peroxisomes by three dehydrogenases: glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, and isocitrate dehydrogenase. In the last decade, different experimental evidence has suggested the existence of cellular functions for peroxisomes related to reactive oxygen species (ROS), but the recent demonstration of the presence of nitric oxide synthase (NOS) in plant peroxisomes implies that these organelles could also have a function in plant cells as a source of signal molecules like nitric oxide (NO*), superoxide radicals, hydrogen peroxide, and possibly S-nitrosoglutathione (GSNO).

Antioxidants↗