Publications by authors named "Stella Castro"

18 Publications

  • Page 1 of 1

Targeting redox metabolism of the maize-Azospirillum brasilense interaction exposed to arsenic-affected groundwater.

Physiol Plant 2021 Jul 30. Epub 2021 Jul 30.

Instituto de Investigaciones Agrobiotecnológicas - Consejo Nacional de Investigaciones Científicas y Técnicas (INIAB-CONICET), Departamento de Ciencias Naturales, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Córdoba, Argentina.

Arsenic in groundwater constitutes an agronomic problem due to its potential accumulation in the food chain. Among the agro-sustainable tools to reduce metal(oid)s toxicity, the use of plant growth-promoting bacteria (PGPB) becomes important. For that, and based on previous results in which significant differences of As translocation were observed when inoculating maize plants with Az39 or CD Azospirillum strains, we decided to decipher the redox metabolism changes and the antioxidant system response of maize plants inoculated when exposed to a realistic arsenate (As ) dose. Results showed that As caused morphological changes in the root exodermis. Photosynthetic pigments decreased only in CD inoculated plants, while oxidative stress evidence was detected throughout the plant, regardless of the assayed strain. The antioxidant response was strain-differential since only CD inoculated plants showed an increase in superoxide dismutase, glutathione S-transferase (GST), and glutathione reductase (GR) activities while other enzymes showed the same behavior irrespective of the inoculated strain. Gene expression assays reported that only GST23 transcript level was upregulated by arsenate, regardless of the inoculated strain. As diminished the glutathione (GSH) content of roots inoculated with the Az39 strain, and CD inoculated plants showed a decrease of oxidized GSH (GSSG) levels. We suggest a model in which the antioxidant response of the maize-diazotrophs system is modulated by the strain and that GSH plays a central role acting mainly as a substrate for GST. These findings generate knowledge for a suitable PGPB selection, and its scaling to an effective bioinoculant formulation for maize crops exposed to adverse environmental conditions.
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http://dx.doi.org/10.1111/ppl.13514DOI Listing
July 2021

Unraveling the impact of arsenic on the redox response of peanut plants inoculated with two different Bradyrhizobium sp. strains.

Chemosphere 2020 Nov 21;259:127410. Epub 2020 Jun 21.

Instituto de Investigaciones Agrobiotecnológicas - Consejo Nacional de Investigaciones Científicas y Técnicas (INIAB-CONICET), Departamento de Ciencias Naturales, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto (UNRC), Ruta 36, Km 601, X5800, Río Cuarto, Córdoba, Argentina. Electronic address:

Arsenic (As) can be present naturally in groundwater from peanut fields, constituting a serious problem, as roots can accumulate and mobilize the metalloid to their edible parts. Understanding the redox changes in the legume exposed to As may help to detect potential risks to human health and recognize tolerance mechanisms. Thirty-days old peanut plants inoculated with Bradyrhizobium sp. strains (SEMIA6144 or C-145) were exposed to a realistic arsenate concentration, in order to unravel the redox response and characterize the oxidative stress indexes. Thus, root anatomy, reactive oxygen species detection by fluorescence microscopy and, ROS histochemical staining along with the NADPH oxidase activity were analyzed. Besides, photosynthetic pigments and damage to lipids and proteins were determined as oxidative stress indicators. Results showed that at 3 μM As, the cross-section areas of peanut roots were augmented; NADPH oxidase activity was significantly increased and O˙¯and HO accumulated in leaves and roots. Likewise, an increase in the lipid peroxidation and protein carbonyls was also observed throughout the plant regardless the inoculated strain, while chlorophylls and carotenes were increased only in those inoculated with Bradyrhizobium sp. C-145. Interestingly, the oxidative burst, mainly induced by the NADPH oxidase activity, and the consequent oxidative stress was strain-dependent and organ-differential. Additionally, As modifies the root anatomy, acting as a possibly first defense mechanism against the metalloid entry. All these findings allowed us to conclude that the redox response of peanut is conditioned by the rhizobial strain, which contributes to the importance of effectively formulating bioinoculants for this crop.
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http://dx.doi.org/10.1016/j.chemosphere.2020.127410DOI Listing
November 2020

Proline metabolic dynamics and implications in drought tolerance of peanut plants.

Plant Physiol Biochem 2020 Jun 17;151:566-578. Epub 2020 Apr 17.

Department of Biochemistry, Redox Biology Center, University of Nebraska-Lincoln, Lincoln, NE, 68588, USA.

Proline accumulation and metabolism are associated with mechanisms of abiotic stress avoidance in plants. Proline accumulation generally improves osmotic stress tolerance whereas proline metabolism can have varying effects from ATP generation to the formation of reactive oxygen species. To further understand the roles of proline in stress protection, two peanut cultivars with contrasting tolerance to drought were examined by transcriptional and biochemical analyses during water stress. Plants exposed to polyethylene glycol had diminished relative water content and increased proline content; while, only the drought sensitive plants, cultivar Granoleico, showed lipid oxidative damage (measured as thiobarbituric acid reactive substances). The expression of proline biosynthesis genes (P5CS1, P5CS2a, P5CS2b, P5CR) was increased in both cultivars upon exposure to water stress. However, the relative expression of proline catabolism genes (ProDH1, ProDH2) was increased only in the sensitive cultivar during stress. Exogenous addition of proline and the proline analogue thiazolidine-4-carboxylic acid (T4C), both substrates of proline dehydrogenase, was also used to exacerbate and identify plant responses. Pretreatment of plants with T4C induced unique changes in the drought tolerant EC-98 cultivar such as higher mRNA levels of proline biosynthetic and catabolic ProDH genes, even in the absence of water stress. The increased levels of ProDH gene expression, potentially associated with higher T4C conversion to cysteine, may contribute to the tolerant phenotype.
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http://dx.doi.org/10.1016/j.plaphy.2020.04.010DOI Listing
June 2020

Metabolic features involved in drought stress tolerance mechanisms in peanut nodules and their contribution to biological nitrogen fixation.

Plant Sci 2017 Oct 30;263:12-22. Epub 2017 Jun 30.

Biochemistry and Physiology of Plants, Bielefeld University, D-33501 Bielefeld, Germany.

Legumes belong to the most important crops worldwide. They increase soil fertility due their ability to establish symbiotic associations with soil microorganisms, known as rhizobia, capable of fixing nitrogen from the atmosphere. However, they are frequently exposed to abiotic stress conditions in particular drought. Such adverse conditions impair the biological nitrogen fixation (BNF) and depend largely on the legume. Therefore, two peanut cultivars with contrasting tolerance to drought, namely the more tolerant EC-98 and the sensitive Granoleico, were investigated to elucidate the relative contribution of BNF to the tolerance to drought. The tolerant cultivar EC-98 sustained growth and BNF similar to the control condition despite the reduced water potential and photosynthesis, suggesting the functioning of distinct metabolic pathways that contributed to enhance the tolerance. The biochemical and metabolomics approaches revealed that nodules from the tolerant cultivar accumulated trehalose, proline and gamma-aminobutyric acid (GABA), metabolites with known function in protecting against drought stress. The amide metabolism was severely affected in nodules from the sensitive cultivar Granoleico as revealed by the low content of asparagine and glutamine in the drought stressed plants. The sensitive cultivar upon rehydration was unable to re-establish a metabolism similar to well-watered plants. This was evidenced by the low level of metabolites and, transcripts and specific activities of enzymes from the carbon (sucrose synthase) and nitrogen (glutamine synthetase) metabolism which decreased below the values of control plants. Therefore, the increased content of metabolites with protective functions under drought stress likely is crucial for the full restoration upon rehydration. Smaller changes of drought stress-related metabolites in nodule are another trait that contributes to the effective control of BNF in the tolerant peanut cultivar (EC-98).
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http://dx.doi.org/10.1016/j.plantsci.2017.06.009DOI Listing
October 2017

Antioxidant responses of peanut roots exposed to realistic groundwater doses of arsenate: Identification of glutathione S-transferase as a suitable biomarker for metalloid toxicity.

Chemosphere 2017 Aug 24;181:551-561. Epub 2017 Apr 24.

Departamento de Ciencias Naturales, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Ruta 36 Km 601, 5800 Río Cuarto, Córdoba, Argentina.

Arsenic (As)-polluted groundwater constitutes a serious problem for peanut plants, as roots can accumulate the metalloid in their edible parts. Characterization of stress responses to As may help to detect potential risks and identify mechanisms of tolerance, being the induction of oxidative stress a key feature. Fifteen-day old peanut plants were treated with arsenate in order to characterize the oxidative stress indexes and antioxidant response of the legume under realistic groundwater doses of the metalloid. Superoxide anion (O) and hydrogen peroxide (HO) histochemical staining along with the activities of NADPH oxidase, superoxide dismutase (SOD), catalase (CAT) and thiol (glutathione and thioredoxins) metabolism were determined in roots. Results showed that at 20 μM HAsO, peanut growth was reduced and the root architecture was altered. O and HO accumulated at the root epidermis, while lipid peroxidation, NADPH oxidase, SOD, CAT and glutathione S-transferase (GST) activities augmented. These variables increased with increasing As concentration (100 μM) while glutathione reductase (GR) and glutathione peroxidase/peroxiredoxin (GPX/PRX) were significantly decreased. These findings demonstrated that the metalloid induced physiological and biochemical alterations, being the NADPH oxidase enzyme implicated in the oxidative burst. Additionally, the strong induction of GST activity, even at the lowest HAsO doses studied, can be exploited as suitable biomarker of As toxicity in peanut plants, which may help to detect risks of As accumulation and select tolerant cultivars.
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http://dx.doi.org/10.1016/j.chemosphere.2017.04.104DOI Listing
August 2017

Dynamic responses of photosynthesis and the antioxidant system during a drought and rehydration cycle in peanut plants.

Funct Plant Biol 2016 Apr;43(4):337-345

Departamento de Ciencias Naturales, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Ruta 36, Km. 601, 5800 Río Cuarto, Córdoba, Argentina.

Drought stress is one of the most important environmental factors that adversely affect the productivity and quality of crops. Most studies focus on elucidating plant responses to this stress but the reversibility of these effects is less known. The aim of this work was to evaluate whether drought-stressed peanut (Arachis hypogaea L.) plants were capable of recovering their metabolism upon rehydration, with a focus on their antioxidant system. Peanut plants in the flowering phase (30 days after sowing) were exposed to drought stress by withholding irrigation during 14 days and subsequent rehydration during 3 days. Under these conditions, physiological status indicators, reactive oxygen species production and antioxidant system activity were evaluated. Under drought stress, the stomatal conductance, photosynthetic quantum yield and 13C:12C ratio of the peanut plants were negatively affected, and also they accumulated reactive oxygen species. The antioxidant system of peanut plants showed increases in superoxide dismutase-, ascorbate peroxidase- and glutathione reductase-specific activities, as well as the total ascorbate content. All of these responses were reversed upon rehydration at 3 days. The efficient and dynamic regulation of variables related to photosynthesis and the antioxidant system during a drought and rehydration cycle in peanut plants was demonstrated. It is suggested that the activation of the antioxidant system could mediate the signalling of drought stress responses that enable the plant to survive and recover completely within 3 days of rehydration.
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http://dx.doi.org/10.1071/FP15206DOI Listing
April 2016

Physiological responses of a halophytic shrub to salt stress by Na2SO4 and NaCl: oxidative damage and the role of polyphenols in antioxidant protection.

AoB Plants 2014 Jul 24;6. Epub 2014 Jul 24.

Fisiología Vegetal, Físico Químicas y Naturales, Universidad Nacional de Río Cuarto, Río Cuarto, Argentina

Salt stress conditions lead to increased production of reactive oxygen species (ROS) in plant cells. Halophytes have the ability to reduce these toxic ROS by means of a powerful antioxidant system that includes enzymatic and non-enzymatic components. In this research, we used the halophytic shrub Prosopis strombulifera to investigate whether the ability of this species to grow under increasing salt concentrations and mixtures was related to the synthesis of polyphenolic compounds and to the maintenance of leaf pigment contents for an adequate photosynthetic activity. Seedlings of P. strombulifera were grown hydroponically in Hoagland's solution, gradually adding Na2SO4 and NaCl separately or in mixtures until reaching final osmotic potentials of -1, -1.9 and -2.6 MPa. Control plants were allowed to develop in Hoagland's solution without salt. Oxidative damage in tissues was determined by H2O2 and malondialdehyde content. Leaf pigment analysis was performed by high-performance liquid chromatography with ultraviolet, and total phenols, total flavonoids, total flavan-3-ols, condensed tannins, tartaric acid esters and flavonols were spectrophotometrically assayed. Treatment with Na2SO4 increased H2O2 production and lipid peroxidation in tissues and induced a sharp increase in flavonoid compounds (mainly flavan-3-ols) and consequently in the antioxidant activity. Also, Na2SO4 treatment induced an increased carotenoid/chlorophyll ratio, which may represent a strategy to protect photosystems against photooxidation. NaCl treatment, however, did not affect H2O2 content, lipid peroxidation, pigments or polyphenols synthesis. The significant accumulation of flavonoids in tissues under Na2SO4 treatment and their powerful antioxidant activity indicates a role for these compounds in counteracting the oxidative damage induced by severe salt stress, particularly, ionic stress. We demonstrate that ionic interactions between different salts in salinized soils modify the biochemical and morpho-physiological responses of P. strombulifera plants to salinity.
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http://dx.doi.org/10.1093/aobpla/plu042DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4153985PMC
July 2014

Antioxidant enzyme activities and gene expression patterns in peanut nodules during a drought and rehydration cycle.

Funct Plant Biol 2014 Jul;41(7):704-713

Biochemistry and Physiology of Plants, Bielefeld University, D-33501 Bielefeld, Germany.

Drought stress is one of the most important environmental factors that affect plant growth and limit biomass production. Most studies focus on drought stress development but the reversibility of the effects receives less attention. Therefore, the present work aims to explore the biological nitrogen fixation (BNF) of the symbiotic association between peanut (Arachis hypogaea L.) and Bradyrhizobium sp. during a drought-recovery cycle with a focus on the response of enzyme activity and gene expression of the antioxidant system. Peanuts exposed to drought stress had impaired BNF, as indicated by lower nitrogenase activity, and decreased leghaemoglobin content; the latter was reversed to control values upon rehydration. Previous results demonstrated that reactive oxygen species (O2·- and H2O2) were accumulated as a consequence of drought stress, suggesting that nodules experience oxidative stress. In addition, marker transcripts responsive to drought, abscisic acid and H2O2 were upregulated. Increased transcript levels of glutathione reductase were associated with an increased enzyme activity but superoxide dismutase and glutathione S-transferase activities were unchanged, despite upregulated gene transcription. In contrast, increased activity of ascorbate peroxidase (APX) was unrelated with changes in cytosolic APX transcript levels suggesting isogene specificity. In conclusion, the work exemplarily demonstrates the efficient and dynamic regulation of antioxidant enzymes and marker compounds during drought cycling, which is likely to be a prerequisite for functional optimisation of nodule metabolism.
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http://dx.doi.org/10.1071/FP13311DOI Listing
July 2014

Influence of cadmium on the symbiotic interaction established between peanut (Arachis hypogaea L.) and sensitive or tolerant bradyrhizobial strains.

J Environ Manage 2013 Nov 26;130:126-34. Epub 2013 Sep 26.

Departamento de Ciencias Naturales, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Ruta 36 Km 601, 5800 Río Cuarto, Córdoba, Argentina. Electronic address:

Heavy metals in soil are known to affect rhizobia-legume interaction reducing not only rhizobia viability, but also nitrogen fixation. In this work, we have compared the response of the symbiotic interaction established between the peanut (Arachis hypogaea L.) and a sensitive (Bradyrhizobium sp. SEMIA6144) or a tolerant (Bradyrhizobium sp. NLH25) strain to Cd under exposure to this metal. The addition of 10 μM Cd reduced nodulation and nitrogen content in both symbiotic associations, being the interaction established with the sensitive strain more affected than that with the tolerant one. Plants inoculated with the sensitive strain accumulated more Cd than those inoculated with the tolerant strain. Nodules showed an increase in reactive oxygen species (ROS) production when exposed to Cd. The histological structure of the nodules exposed to Cd revealed a deposit of unknown material on the cortex and a significant reduction in the infection zone diameter in both strains, and a greater number of uninfected cells in those nodules occupied by the sensitive strain. In conclusion, Cd negatively impacts on peanut-bradyrhizobia interaction, irrespective of the tolerance of the strains to this metal. However, the inoculation of peanut with Bradyrhizobium sp. NLH25 results in a better symbiotic interaction suggesting that the tolerance observed in this strain could limit Cd accumulation by the plant.
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http://dx.doi.org/10.1016/j.jenvman.2013.08.056DOI Listing
November 2013

Antioxidant defense system responses and role of nitrate reductase in the redox balance maintenance in Bradyrhizobium japonicum strains exposed to cadmium.

Enzyme Microb Technol 2013 Oct 2;53(5):345-50. Epub 2013 Aug 2.

Departamento de Ciencias Naturales, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Ruta 36 Km 601, 5800 Río Cuarto, Córdoba, Argentina. Electronic address:

In this work, we evaluated the effects of cadmium (Cd) on the antioxidant defense system responses and the role of nitrate reductase (NR) in the redox balance maintenance in Bradyrhizobium japonicum strains. For that, B. japonicum USDA110 and its NR defective mutant strain (GRPA1) were used. Results showed that the addition of 10μM Cd did not modify the aerobic growth of the wild type strain while the mutant strain was strongly affected. Anaerobic growth revealed that only the parental strain was able to grow under this condition. Cd reduced drastically the NR activity in B. japonicum USDA110 and increased lipid peroxide content in both strains. Cd decreased reduced glutathione (GSH)/oxidized glutathione (GSSG) ratio in B. japonicum USDA110 although, a significant increased was observed in the mutant GRPA1. GSH-related enzymes were induced by Cd, being more evident the increase in the mutant strain. This different behavior observed between strains suggests that NR enzyme plays an important role in the redox balance maintenance in B. japonicum USDA 110 exposed to Cd.
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http://dx.doi.org/10.1016/j.enzmictec.2013.07.007DOI Listing
October 2013

Visual pathway abnormalities were found in most multiple sclerosis patients despite history of previous optic neuritis.

Arq Neuropsiquiatr 2013 Jul;71(7):437-41

Department of Ophthalmo-Otolaryngology, Faculty of Medical Sciences, Universidade Estadual de Campinas, Campinas SP, Brazil.

Objective: It was to investigate visual field (VF) abnormalities in a group of multiple sclerosis (MS) patients in the remission phase and the presence of magnetic resonance imaging (MRI) lesions in the optic radiations.

Methods: VF was assessed in 60 participants (age range 20-51 years): 35 relapsing-remitting MS patients [20 optic neuritis (+), 15 optic neuritis (-)] and 25 controls. MRI (3-Tesla) was obtained in all patients.

Results: Visual parameters were abnormal in MS patients as compared to controls. The majority of VF defects were diffuse. All patients except one had posterior visual pathways lesions. No significant difference in lesion number, length and distribution was noted between patients with and without history of optic neuritis. One patient presented homonymous hemianopsia.

Conclusion: Posterior visual pathway abnormalities were found in most MS patients despite history of previous optic neuritis.
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http://dx.doi.org/10.1590/0004-282X20130058DOI Listing
July 2013

Contribution of phytochelatins to cadmium tolerance in peanut plants.

Metallomics 2012 Oct 17;4(10):1119-24. Epub 2012 Sep 17.

Departamento de Ciencias Naturales, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Ruta 36 Km 601, 5800 Río Cuarto, Córdoba, Argentina.

Cadmium (Cd) is a well known heavy metal considered as one of the most toxic metals on Earth, affecting all viable cells that are exposed even at low concentration. It is introduced to agricultural soils mainly by phosphate fertilizers and causes many toxic symptoms in cells. Phytochelatins (PCs) are non-protein thiols which are involved in oxidative stress protection and are strongly induced by Cd. In this work, we analyzed metal toxicity as well as PCs implication on protection of peanut plants exposed to Cd. Results showed that Cd exposure induced a reduction of peanut growth and produced changes in the histological structure with a deposit of unknown material on the epidermal and endodermal cells. When plants were exposed to 10 μM Cd, no modification of chlorophyll, lipid peroxides, carbonyl groups, or hydrogen peroxide (H₂O₂) content was observed. At this concentration, peanut leaves and roots glutathione (GSH) content decreased. However, peanut roots were able to synthesize different types of PCs (PC2, PC3, PC4). In conclusion, PC synthesis could prevent metal disturbance on cellular redox balance, avoiding oxidative damage to macromolecules.
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http://dx.doi.org/10.1039/c2mt20146aDOI Listing
October 2012

Involvement of glutathione and enzymatic defense system against cadmium toxicity in Bradyrhizobium sp. strains (peanut symbionts).

Biometals 2012 Feb 16;25(1):23-32. Epub 2011 Jul 16.

Departamento de Ciencias Naturales, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Ruta 36 km 601, 5800, Río Cuarto, Córdoba, Argentina.

In this study, the effects of cadmium (Cd) on cell morphology and antioxidant enzyme activities as well as the distribution of the metal in different cell compartments in Bradyrhizobium sp. strains were investigated. These strains were previously classified as sensitive (Bradyrhizobium sp. SEMIA 6144) and tolerant (Bradyrhizobium sp. NLH25) to Cd. Transmission electron micrographs showed large electron-translucent inclusions in the sensitive strain and electron-dense bodies in the tolerant strain, when exposed to Cd. Analysis of Cd distribution revealed that it was mainly bounded to cell wall in both strains. Antioxidant enzyme activities were significantly different in each strain. Only the tolerant strain was able to maintain a glutathione/oxidized glutathione (GSH/GSSG) ratio by an increase of GSH reductase (GR) and GSH peroxidase (GPX) enzyme activities. GSH S-transferase (GST) and catalase (CAT) activities were drastically inhibited in both strains while superoxide dismutase (SOD) showed a significant decrease only in the sensitive strain. In conclusion, our findings suggest that GSH content and its related enzymes are involved in the Bradyrhizobium sp. tolerance to Cd contributing to the cellular redox balance.
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http://dx.doi.org/10.1007/s10534-011-9480-zDOI Listing
February 2012

Cadmium accumulation and tolerance in Bradyrhizobium spp. (peanut microsymbionts).

Curr Microbiol 2011 Jan 1;62(1):96-100. Epub 2010 Jun 1.

Departamento de Ciencias Naturales, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Ruta 36 km 601, 5800, Rio Cuarto, Córdoba, Argentina.

In this study, the effect of cadmium (Cd) on cell viability and its accumulation in Bradyrhizobium spp. (peanut microsymbionts) as well as the role of glutathione (GSH) in the tolerance to this metal were investigated. A reference strain recommended as peanut inoculant (Bradyrhizobium sp. SEMIA6144) grew up to 10 μM Cd meanwhile a GSH-deficient mutant strain (Bradyrhizobium sp. SEMIA6144-S7Z) was unable to grow at this concentration. Two native peanut isolates obtained from Córdoba soils (Bradyrhizobium sp. NLH25 and Bradyrhizobium sp. NOD31) tolerated up to 30 μM Cd. The analysis of Cd content showed that Bradyrhizobium sp. SEMIA6144 accumulated a high amount of this metal, but a considerable inhibition of growth was observed compared to tolerant strains at 10 μM Cd. At this concentration, the intracellular GSH content of all the Bradyrhizobium sp. strains was not modified in comparison to control conditions. However, at 30 μM Cd, the intracellular GSH content significantly increased in Bradyrhizobium sp. strains NLH25 and NOD31. Thus, the distinct response of each Bradyrhizobium sp. strain to Cd reveals that, even in closely related lineages, there are strain-specific variations influencing the levels of tolerance to this metal. Indeed, the native peanut isolates tolerated higher Cd concentration than the reference strain, possibly due to an increase in GSH levels which could act as a detoxifying agent.
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http://dx.doi.org/10.1007/s00284-010-9675-5DOI Listing
January 2011

Visual control in children with developmental dyslexia.

Arq Bras Oftalmol 2008 Nov-Dec;71(6):837-40

Universidade Estadual de Campinas - Campinas (SP) - Brazil.

Purpose: To assess binocular control in children with dyslexia.

Methods: Cross-sectional study with 26 children who were submitted to a set of ophthalmologic and visual tests.

Results: In the dyslexic children less eye movement control in voluntary convergence and unstable binocular fixation was observed.

Conclusion: The results support the hypothesis that developmental dyslexia might present deficits which involve the magnocellular pathway and a part of the posterior cortical attentional network.
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http://dx.doi.org/10.1590/s0004-27492008000600014DOI Listing
July 2009

Importance of glutathione in the nodulation process of peanut (Arachis hypogaea).

Physiol Plant 2008 Oct 15;134(2):342-7. Epub 2008 May 15.

Departamento de Ciencias Naturales, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Ruta 36 Km 601, 5800 Río Cuarto, Córdoba, Argentina.

GSH appears to be essential for proper development of the root nodules during the symbiotic association of legume-rhizobia in which the entry of rhizobia involves the formation of infection threads. In the particular case of peanut-rhizobia symbiosis, the entry of rhizobia occurs by the mechanism of infection called 'crack entry', i.e. entry at the point of emergence of lateral roots. We have previously shown the role of GSH content of Bradyrhizobium sp. SEMIA 6144 during the symbiotic association with peanut using a GSH-deficient mutant obtained by disruption of the gshA gene, encoding gamma-glutamylcysteine synthetase (gamma-GCS), which was able to induce nodules in peanut roots without alterations in the symbiotic phenotype. To investigate the role of the peanut GSH content in the symbiosis, the compound L-buthionine-sulfoximine (BSO), a specific inhibitor of gamma-GCS in plants, was used. There were no differences in the plant growth and the typical anatomic structure of the peanut roots when the plants grew in the Fahraeus medium either in presence or in absence of 0.1 mM BSO. However, the GSH content was reduced by 51% after treatment with BSO. The BSO-treated plants inoculated with wild-type or mutant strains of Bradyrhizobium sp. showed a significant reduction in the number and dry weight of nodules, suggesting that GSH content could play an important role in the nodulation process of root peanut with Bradyrhizobium sp.
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http://dx.doi.org/10.1111/j.1399-3054.2008.01126.xDOI Listing
October 2008

Role of glutathione in the growth of Bradyrhizobium sp. (peanut microsymbiont) under different environmental stresses and in symbiosis with the host plant.

Can J Microbiol 2006 Jul;52(7):609-16

Departamento de Ciencias Naturales, Facultad de Ciencias Exactas, Universidad Nacional de Río Cuarto, Argentina.

Glutathione (GSH) plays an important role in the defence of microorganisms and plants against different environmental stresses. To determine the role of GSH under different stresses, such as acid pH, saline shock, and oxidative shock, a GSH-deficient mutant (Bradyrhizobium sp. 6144-S7Z) was obtained by disruption of the gshA gene, which encodes the enzyme gamma-glutamylcysteine synthetase. Growth of the mutant strain was significantly reduced in liquid minimal saline medium, and the GSH content was very low, about 4% of the wild-type level. The defect, caused by disruption of the gshA gene in the growth of mutant strain, cannot be reversed by the addition of GSH (up to 100 micromol/L) to the liquid minimal saline medium, and the endogenous GSH level was approximately the same as that observed without the addition of GSH. In contrast, the wild-type strain increased the GSH content under these conditions. However, the growth of the mutant strain in a rich medium (yeast extract--mannitol) increased, suggesting that at least some but not all of the functions of GSH could be provided by peptides and (or) amino acids. The symbiotic properties of the mutant were similar to those found in the wild-type strain, indicating that the mutation does not affect the ability of the mutant to form effective nodules.
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http://dx.doi.org/10.1139/w06-007DOI Listing
July 2006

Peanut nodulation kinetics in response to low pH.

Plant Physiol Biochem 2005 Aug 13;43(8):754-9. Epub 2005 Jul 13.

Departamento de Ciencias Naturales, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Ruta 36 Km 601, 5800 Río Cuarto, Córdoba, Argentina.

In this work, the peanut nodulation kinetics by acid-sensitive and tolerant isolates under acid stress condition was analyzed. The results demonstrated that the acid pH produced a decrease in the number of nodules formed only when peanut plants were inoculated with acid-sensitive isolates but increased steadily by the addition of 10 mM Ca2+, reaching higher values than those obtained at pH 7.0. On the contrary, the peanut nodulation by acid-tolerant isolates was not affected by this stressing condition. These data suggest that acid-tolerant isolates could be used as a potential source of strains for preparing highly effective inoculants for peanut plants growing in acid soils.
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http://dx.doi.org/10.1016/j.plaphy.2005.05.012DOI Listing
August 2005
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