RESUMEN

We investigated the mechanism of selenium (Se) tolerance using an Arabidopsis thaliana knockout mutant of a sulfate transporter, sultr1;2. Se stress inhibited plant growth, decreased chlorophyll contents, and increased protein oxidation and lipid peroxidation in the wild type, whereas the sultr1;2 mutation mitigated damage of these forms, indicating that sultr1;2 is more tolerant of Se than the wild type is. The accumulation of symplastic Se was suppressed in sultr1;2 as compared to the wild type, and the chemical speciation of Se in the mutant was different from that in the wild type. Regardless of Se stress, the activities of ascorbate peroxidase, catalase, and peroxidase in the mutant were higher than in the wild type, while the activity of superoxide dismutase in the mutant was the same as in the wild type. These results suggest that the sultr1;2 mutation confers Se tolerance on Arabidopsis by decreasing symplastic Se and maintaining antioxidant enzyme activities.

Asunto(s)

Proteínas de Transporte de Anión/genética , Proteínas de Arabidopsis/genética , Arabidopsis/genética , Raíces de Plantas/genética , Tolerancia a la Sal/genética , Compuestos de Selenio/farmacología , Selenio/farmacología , Adaptación Fisiológica/genética , Proteínas de Transporte de Anión/deficiencia , Antioxidantes/metabolismo , Arabidopsis/efectos de los fármacos , Arabidopsis/metabolismo , Ascorbato Peroxidasas/metabolismo , Catalasa/metabolismo , Técnicas de Inactivación de Genes , Peroxidación de Lípido/efectos de los fármacos , Peroxidación de Lípido/genética , Mutación , Estrés Oxidativo/efectos de los fármacos , Estrés Oxidativo/genética , Peroxidasas/metabolismo , Raíces de Plantas/efectos de los fármacos , Raíces de Plantas/metabolismo , Plantas Modificadas Genéticamente/efectos de los fármacos , Plantas Modificadas Genéticamente/metabolismo , Ácido Selénico , Selenio/metabolismo , Compuestos de Selenio/metabolismo , Estrés Fisiológico/genética , Superóxido Dismutasa/metabolismo

RESUMEN

An abscisic acid (ABA)-insensitive Vicia faba mutant, fia (fava bean impaired in ABA-induced stomatal closure) had previously been isolated. In this study, it was investigated how FIA functions in ABA signalling in guard cells of Vicia faba. Unlike ABA, methyl jasmonate (MeJA), H(2)O(2), and nitric oxide (NO) induced stomatal closure in the fia mutant. ABA did not induce production of either reactive oxygen species or NO in the mutant. Moreover, ABA did not suppress inward-rectifying K(+) (K(in)) currents or activate ABA-activated protein kinase (AAPK) in mutant guard cells. These results suggest that FIA functions as an early signal component upstream of AAPK activation in ABA signalling but does not function in MeJA signalling in guard cells of Vicia faba.

Asunto(s)

Ácido Abscísico/farmacología , Vicia faba/metabolismo , Acetatos/farmacología , Ciclopentanos/farmacología , Óxido Nítrico/farmacología , Oxilipinas/farmacología , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Estomas de Plantas/efectos de los fármacos , Estomas de Plantas/metabolismo , Plantas Modificadas Genéticamente/efectos de los fármacos , Plantas Modificadas Genéticamente/genética , Plantas Modificadas Genéticamente/metabolismo , Vicia faba/efectos de los fármacos , Vicia faba/genética

RESUMEN

We found that glutathione (GSH) is involved in abscisic acid (ABA)-induced stomatal closure. Regulation of ABA signaling by GSH in guard cells was investigated using an Arabidopsis mutant, cad2-1, that is deficient in the first GSH biosynthesis enzyme, γ-glutamylcysteine synthetase, and a GSH-decreasing chemical, 1-chloro-2,4-dinitrobenzene (CDNB). Glutathione contents in guard cells decreased along with ABA-induced stomatal closure. Decreasing GSH by both the cad2-1 mutation and CDNB treatment enhanced ABA-induced stomatal closure. Glutathione monoethyl ester (GSHmee) restored the GSH level in cad2-1 guard cells and complemented the stomatal phenotype of the mutant. Depletion of GSH did not significantly increase ABA-induced production of reactive oxygen species in guard cells and GSH did not affect either activation of plasma membrane Ca(2+)-permeable channel currents by ABA or oscillation of the cytosolic free Ca(2+) concentration induced by ABA. These results indicate that GSH negatively modulates a signal component other than ROS production and Ca(2+) oscillation in ABA signal pathway of Arabidopsis guard cells.

Asunto(s)

Ácido Abscísico/farmacología , Arabidopsis/fisiología , Glutamato-Cisteína Ligasa/genética , Glutatión/metabolismo , Estomas de Plantas/efectos de los fármacos , Especies Reactivas de Oxígeno/metabolismo , Arabidopsis/efectos de los fármacos , Arabidopsis/enzimología , Arabidopsis/genética , Calcio/metabolismo , Señalización del Calcio/efectos de los fármacos , Membrana Celular/metabolismo , Citosol/metabolismo , Dinitroclorobenceno/metabolismo , Prueba de Complementación Genética , Glutamato-Cisteína Ligasa/metabolismo , Glutatión/análogos & derivados , Glutatión/farmacología , Mutación , Transducción de Señal/efectos de los fármacos

RESUMEN

We tested synthetic food colorants for their antioxidative potential by the in vitro superoxide generation assay in differentiated HL-60 cells in response to phorbol ester. Among the 12 colorants tested, such fluorescein-type red colorants as rose bengal showed potent inhibitory activity without any cytotoxicity under dark conditions. The intracellular accumulation and superoxide anion scavenging effect of rose bengal were at least partly involved in the inhibitory activity.

Asunto(s)

Diferenciación Celular/efectos de los fármacos , Colorantes de Alimentos/farmacología , Superóxidos/metabolismo , Células HL-60 , Humanos , Neutrófilos/citología , Neutrófilos/efectos de los fármacos , Neutrófilos/metabolismo

RESUMEN

The application of exogenous proline and glycinebetaine (betaine) confers salt tolerance on plants under salt stress. The effects of exogenous proline and betaine on apoplastic flow in rice plants under saline conditions were investigated using trisodium-8-hydroxy-1,3,6-pyrenetrisulphonic acid (PTS), an apoplastic tracer. Rice plants took up more PTS under light conditions than under dark conditions. Salt stress increased PTS uptake and Na(+) content of rice leaves, but did not affect K(+) content, resulting in a lower K(+)/Na(+) ratio. Addition of proline or betaine to the saline medium suppressed Na(+)-induced PTS uptake and Na(+) accumulation, while the K(+) content was slightly increased, which led to a high K(+)/Na(+) ratio under saline conditions. These results suggest that exogenous proline and betaine suppressed Na(+)-enhanced apoplastic flow to reduce Na(+) uptake in rice plants.

Asunto(s)

Apoptosis/efectos de los fármacos , Betaína/farmacología , Oryza/metabolismo , Prolina/farmacología , Sodio/metabolismo , Oryza/crecimiento & desarrollo , Hojas de la Planta/metabolismo , Estrés Fisiológico

RESUMEN

(-)-Epigallocatechin-3-gallate (EGCG) has been reported to possess a wide range of biological and pharmacological properties. In this study, we investigated the effects of EGCG on IL-13 gene expression in human basophilic KU812 cells. The IL-13 mRNA expression level was dose-dependently increased by treatment with EGCG (5-20 microM) for 1 h and additional incubation in a medium for 23 h. EGCG significantly increased the intracellular peroxide level as detected by the peroxide-sensitive probe 2',7'-dichlorodihydrofluorescein diacetate. A pharmacological experiment using catalase and a structure-activity relationship study revealed that the exogenously produced H(2)O(2) significantly, but partially, contributed to the IL-13 expression as well as the intracellular oxidative status. Furthermore, EGCG at the concentration required for IL-13 up-regulation activated c-Jun NH(2)-terminal kinase (JNK), but not extracellular signal-regulated protein kinase or p38 mitogen-activated protein kinase in KU812 cells. Transfection of a JNK-specific siRNA as well as treatment with a JNK-specific inhibitor, SP600125, significantly reduced the EGCG-induced IL-13 mRNA expression, by 47.1 and 44.6%, respectively. In addition, we observed the nuclear translocation, mRNA up-regulation, and activation of DNA binding with the IL-13 promoter of nuclear factor of activated T cells (NFATc1) in the EGCG-treated cells. These data provide biological evidence that EGCG induces IL-13 mRNA expression via the JNK-dependent NFATc1 pathway in KU812 cells.

Asunto(s)

Basófilos/efectos de los fármacos , Catequina/análogos & derivados , Expresión Génica/efectos de los fármacos , Interleucina-13/genética , Proteínas Quinasas JNK Activadas por Mitógenos/metabolismo , Factores de Transcripción NFATC/metabolismo , Antracenos/farmacología , Basófilos/metabolismo , Catequina/farmacología , Línea Celular , Relación Dosis-Respuesta a Droga , Ensayo de Inmunoadsorción Enzimática , Humanos , Peróxido de Hidrógeno/metabolismo , Interleucina-13/biosíntesis , Proteínas Quinasas JNK Activadas por Mitógenos/antagonistas & inhibidores , Peróxidos/metabolismo , Fosforilación/efectos de los fármacos , ARN Mensajero/efectos de los fármacos , ARN Mensajero/genética , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Relación Estructura-Actividad , Regulación hacia Arriba/efectos de los fármacos , Regulación hacia Arriba/genética

RESUMEN

Cellular phototoxicity induced by UVA irradiation and its potential application to therapy has been reported. In the present study, the induction of apoptosis induced by beta-carotene and dimethyl tetrasulfide (Me(2)S(4)) assisted by UVA irradiation in HL-60 cells was assessed. beta-carotene assisted by UVA significantly decreased the cell viability and induced DNA fragmentation in HL-60 cells. Me(2)S(4) combined with beta-carotene and assisted by UVA significantly inhibited the cell viability, and enhanced the caspase-3 activity which was completely inhibited by N-acety-L-cysteine. beta-carotene was significantly degraded by UVA, but this was not accelerated by Me(2)S(4) in a cell culture system. The photodegradation products of beta-carotene prepared by UVA irradiation regardless of the addition of Me(2)S(4) showed lower cytotoxicity than beta-carotene itself in HL-60 cells. These results suggest that the ROS- and caspase-3-dependent apoptosis induced by beta-carotene and Me(2)S(4) assisted by UVA was due to a synergistic action rather than to the sole effect of the photodegradation products of beta-carotene in HL-60 cells.

Asunto(s)

Antineoplásicos/farmacología , Apoptosis/efectos de los fármacos , Apoptosis/efectos de la radiación , Sulfuros/farmacología , Rayos Ultravioleta , beta Caroteno/farmacología , Acetilcisteína/farmacología , Antineoplásicos/química , Antioxidantes/farmacología , Caspasa 3/metabolismo , Proliferación Celular/efectos de los fármacos , Proliferación Celular/efectos de la radiación , Supervivencia Celular/efectos de los fármacos , Supervivencia Celular/efectos de la radiación , Activación Enzimática/efectos de los fármacos , Activación Enzimática/efectos de la radiación , Células HL-60 , Humanos , Células Jurkat , Fotólisis/efectos de los fármacos , Especies Reactivas de Oxígeno/metabolismo , beta Caroteno/química

RESUMEN

Environmental stress, including heavy metal stress, can cause oxidative damage to plants. Up-regulation of the antioxidant defense system induced by proline and glycinebetaine (betaine) alleviates the damaging effects of oxidative stress in plants. Here, we investigated the protective effects of exogenously applied proline and betaine on growth, accumulation of proline and betaine, lipid peroxidation and activity of antioxidant enzymes in cultured tobacco Bright Yellow-2 (BY-2) cells exposed to cadmium (Cd) stress. Cadmium stress (at 100 microM Cd) caused a significant inhibition of the growth of BY-2 cells, and both proline and betaine significantly mitigated this inhibition. In addition, the mitigating effect of proline was more pronounced than that of betaine. Cadmium stress leads to an accumulation of Cd and endogenous proline in cultured cells, increased lipid peroxidation and peroxidase (POX) activity, and decreased activity of superoxide dismutase (SOD) and catalase (CAT). Exogenous application of proline resulted in a decrease in lipid peroxidation and an increase in SOD and CAT activities without reducing Cd contents under Cd stress, while application of betaine resulted in a decrease in lipid peroxidation and an increase in CAT activity with reducing Cd accumulation. Furthermore, exogenous proline and betaine intensified the accumulation of proline and betaine in Cd-stressed BY-2 cells, respectively. The present study suggests that proline and betaine confer tolerance to Cd stress in tobacco BY-2 cells by different mechanisms.

Asunto(s)

Antioxidantes/metabolismo , Betaína/farmacología , Cadmio/metabolismo , Nicotiana/efectos de los fármacos , Estrés Oxidativo/efectos de los fármacos , Proteínas de Plantas/metabolismo , Prolina/farmacología , Betaína/metabolismo , Catalasa/metabolismo , Células Cultivadas , Peroxidación de Lípido/efectos de los fármacos , Prolina/metabolismo , Superóxido Dismutasa/metabolismo , Nicotiana/crecimiento & desarrollo , Nicotiana/metabolismo

RESUMEN

In the present study, we found that (-)-epigallocatechin-3-gallate (EGCG) significantly up-regulated the mRNA expression of the Th1/Th2 cytokines including IL-2, IFN-gamma, IL-5 and IL-13 in Jurkat T cells. The EGCG-induced mRNA up-regulation of IL-2 and IL-5 was predominantly affected by the extracellular signal-regulated protein kinase (ERK) signalling, whereas IL-13 gene expression, the most responsive to the EGCG treatment, was dependent on neither ERK nor c-jun NH(2)-terminal kinase (JNK) signalling. IFN-gamma gene expression was partially mitigated by both inhibitors of the ERK and JNK pathways. Furthermore, catalase significantly attenuated the intracellular peroxide production, phosphorylation of ERK and JNK, and all cytokine gene expressions induced by EGCG. In addition, physiologically relevant concentrations of both EGCG and H(2)O(2)-induced up-regulation of IL-5 gene expression. Our findings provide biological evidence that EGCG induces Th1/Th2 cytokine mRNA expression via H(2)O(2) production followed by activation of ERK or JNK in Jurkat T cells.

Asunto(s)

Catequina/análogos & derivados , Citocinas/genética , Células TH1/efectos de los fármacos , Células TH1/inmunología , Células Th2/efectos de los fármacos , Células Th2/inmunología , Secuencia de Bases , Catequina/farmacología , Cartilla de ADN/genética , Humanos , Peróxido de Hidrógeno/metabolismo , Peróxido de Hidrógeno/farmacología , Interferón gamma/genética , Interleucina-13/genética , Interleucina-2/genética , Interleucina-5/genética , Células Jurkat , Sistema de Señalización de MAP Quinasas/efectos de los fármacos , Modelos Inmunológicos , ARN Mensajero/genética , ARN Mensajero/metabolismo , Células TH1/metabolismo , Células Th2/metabolismo , Regulación hacia Arriba/efectos de los fármacos

RESUMEN

Salt stress causes oxidative damage and cell death in plants. Plants accumulate proline and glycinebetaine (betaine) to mitigate detrimental effects of salt stress. The aim of this study was to investigate the protective effects of proline and betaine on cell death in NaCl-unadapted tobacco (Nicotiana tabacum) Bright Yellow-2 suspension-cultured cells subjected to salt stress. Salt stress increased reactive oxygen species (ROS) accumulation, lipid peroxidation, nuclear deformation and degradation, chromatin condensation, apoptosis-like cell death and ATP contents. Neither proline nor betaine affected apoptosis-like cell death and G(1) phase population, and increased ATP contents in the 200mM NaCl-stressed cells. However, both of them effectively decreased ROS accumulation and lipid peroxidation, and suppressed nuclear deformation and chromatin condensation induced by severe salt stress. Evans Blue staining experiment showed that both proline and betaine significantly suppressed increment of membrane permeability induced by 200mM NaCl. Furthermore, among the ROS scavenging antioxidant defense genes studied here, mRNA levels of salicylic acid-binding (SAbind) catalase (CAT) and lignin-forming peroxidase (POX) were found to be increased by proline and betaine under salt stress. It is concluded that both proline and betaine provide a protection against NaCl-induced cell death via decreasing level of ROS accumulation and lipid peroxidation as well as improvement of membrane integrity.

Asunto(s)

Antioxidantes/metabolismo , Betaína/farmacología , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , Nicotiana/citología , Prolina/farmacología , Cloruro de Sodio/farmacología , Estrés Fisiológico/efectos de los fármacos , Adenosina Trifosfato/metabolismo , Ciclo Celular/efectos de los fármacos , Muerte Celular/efectos de los fármacos , Núcleo Celular/efectos de los fármacos , Núcleo Celular/genética , Células Cultivadas , Fragmentación del ADN/efectos de los fármacos , Espacio Intracelular/efectos de los fármacos , Espacio Intracelular/metabolismo , Peroxidación de Lípido/efectos de los fármacos , ARN Mensajero/genética , ARN Mensajero/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Nicotiana/efectos de los fármacos , Nicotiana/genética , Nicotiana/inmunología

RESUMEN

Docosahexaenoic acid (22: 6n-3; DHA) is a long chain polyunsaturated fatty acid that exists highly enriched in fish oil, and it is one of the low molecular weight food chemicals which can pass a blood brain barrier. A preliminary survey of several fatty acids for expression of growth-associated protein-43 (GAP-43), a marker of axonal growth, identified DHA as one of the most potent inducers. The human neuroblastoma SH-SY5Y cells exposed to DHA showed significant and dose-dependent increases in the percentage of cells with longer neurites. To elucidate signaling mechanisms involved in DHA-enhanced basal neuritogenesis, we examined the role of extracellular signal-regulated kinase (ERK)1/2 and intracellular reactive oxygen species (ROS) production using SH-SY5Y cells. From immunoblotting experiments, we observed that DHA induced the ROS production, protein tyrosine phosphatase inhibition, mitogen-activated protein kinase (MAPK)/ERK kinase (MEK) phosphorylation, and sequentially ERK1/2 phosphorylation, the last of which was significantly reduced by MEK inhibitor U0126. Both antioxidants and MEK inhibitor affected DHA-induced GAP-43 expression, whereas the specific PI3K inhibitor LY294002 did not. We found that total protein tyrosine phosphatase activity was also downregulated by DHA treatment, which was counteracted by antioxidant pretreatment. These results suggest that the ROS-dependent ERK pathway, rather than PI3K, plays an important role during DHA-enhanced neurite outgrowth.

Asunto(s)

Ácidos Docosahexaenoicos/farmacología , Neuritas/fisiología , Especies Reactivas de Oxígeno/metabolismo , Línea Celular Tumoral , Activación Enzimática , Humanos , Proteína Quinasa 1 Activada por Mitógenos/metabolismo , Proteína Quinasa 3 Activada por Mitógenos/metabolismo , Neuritas/efectos de los fármacos , Neuroblastoma/metabolismo , Fármacos Neuroprotectores/farmacología , Transducción de Señal

RESUMEN

Organosulfur compounds have been established to possess anticancer effects. To provide a better understanding of the biological function of dimethyl sulfides, dimethyl monosulfide (Me(2)S), dimethyl disulfide (Me(2)S(2)), dimethyl trisulfide (Me(2)S(3)) and dimethyl tetrasulfide (Me(2)S(4)) were used as experimental materials to investigate their effects on apoptosis induction in human leukemia Jurkat cells and HL-60 cells. Treatment with 20 muM dimethyl sulfides for 24 h decreased the viability of both cells. The cell viability-reducing effect of these sulfides was in the following order: Me(2)S(4) asymptotically equal to Me(2)S(3) > Me(2)S(2) asymptotically equal to Me(2)S for Jurkat cells and Me(2)S(4) > Me(2)S(3) > Me(2)S(2) asymptotically equal to Me(2)S for HL-60 cells. Me(2)S(3) and Me(2)S(4) significantly induced DNA fragmentation and caspase-3 activation. The addition of GSH or NAC completely suppressed the sulfide-induced apoptosis. Our results indicate that dimethyl sulfides with a larger number of sulfur atoms more strongly induced apoptosis in both human leukemia cells via ROS production and caspase-3 activation.

Asunto(s)

Apoptosis/efectos de los fármacos , Leucemia/patología , Sulfuros/farmacología , Animales , Antioxidantes/metabolismo , Caspasa 3/metabolismo , Bovinos , Supervivencia Celular/efectos de los fármacos , Cistina/análogos & derivados , Cistina/metabolismo , Activación Enzimática/efectos de los fármacos , Glutatión/metabolismo , Células HL-60 , Humanos , Espacio Intracelular/efectos de los fármacos , Espacio Intracelular/metabolismo , Células Jurkat , Leucemia/metabolismo , Estrés Oxidativo/efectos de los fármacos , Especies Reactivas de Oxígeno/metabolismo , Regulación hacia Arriba/efectos de los fármacos

RESUMEN

(-)-Epigallocatechin-3-gallate (EGCG)-induced apoptosis was along both the extracellular signal-regulated protein kinase (ERK) and c-jun N-terminal kinase (JNK) pathways in Jurkat cells. Co-treatment with EGCG potentiated the cytotoxicity induced by benzyl isothiocyanate (BITC) and H(2)O(2), both being inhibited by ERK and JNK inhibitors. These results suggest the significant role of mitogen-activated protein kinase (MAPK) signaling in the apoptosis induction regulated by EGCG alone and in combination.

Asunto(s)

Catequina/análogos & derivados , Peróxido de Hidrógeno/toxicidad , Isotiocianatos/toxicidad , Linfocitos T/efectos de los fármacos , Apoptosis/efectos de los fármacos , Catequina/farmacología , Humanos , Células Jurkat , Proteínas Quinasas Activadas por Mitógenos/metabolismo , Transducción de Señal/efectos de los fármacos , Linfocitos T/metabolismo

RESUMEN

We investigated the role of glutathione (GSH) in stomatal movements using a GSH deficient mutant, chlorinal-1 (ch1-1). Guard cells of ch1-1 mutants accumulated less GSH than wild types did. Light induced stomatal opening in ch1-1 and wild-type plants. Abscisic acid (ABA) induced stomatal closure in ch1-1 mutants more than wild types without enhanced reactive oxygen species (ROS) production. Therefore, GSH functioned downstream of ROS production in the ABA signaling cascade.

Asunto(s)

Ácido Abscísico/farmacología , Arabidopsis/efectos de los fármacos , Arabidopsis/efectos de la radiación , Glutatión/metabolismo , Luz , Estomas de Plantas/efectos de los fármacos , Estomas de Plantas/efectos de la radiación , Arabidopsis/citología , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Mutación/genética , Estomas de Plantas/metabolismo , Especies Reactivas de Oxígeno/metabolismo

RESUMEN

Carotenoids are used in wide-ranging food applications, but they are susceptible to degradation by many factors including light. We examined the photodegradation of five kinds of carotenoids and three kinds of anthocyanins to clarify which structures of pigments were favorable to accelerated degradation by sulfides under UVA irradiation. Under UVA irradiation, crocetin and crocin were decomposed more rapidly in the presence of dimethyl tetrasulfide than in the absence of the sulfide, but not as rapidly as beta-carotene, zeaxanthin and beta-cryptoxanthin were. However, cyanidin was decomposed more slowly in the presence of sulfide than in the absence of sulfide. Moreover, the photodegradation of kuromanin and keracyanin was not affected by the addition of a sulfide. We also examined the mechanism for this accelerated degradation. Normal hexane was more favorable to the photodegradation of beta-carotene than methanol and ethanol. The accelerated degradation was inhibited by free radical scavengers, but enhanced by the addition of deuterium oxide. These results suggest that conjugated double bonds were favorable to the accelerated photodegradation by sulfide and that this reaction was mediated by free radicals.

Asunto(s)

Carotenoides/química , Sulfuros/química , Rayos Ultravioleta , Antocianinas/química , Cinética , Estructura Molecular , Fotoquímica , Presión , Espectrofotometría

RESUMEN

Methyl jasmonate (MeJA) as well as abscisic acid (ABA) induces stomatal closure with their signal crosstalk. We investigated the function of a regulatory A subunit of protein phosphatase 2A, RCN1, in MeJA signaling. Both MeJA and ABA failed to induce stomatal closure in Arabidopsis rcn1 knockout mutants unlike in wild-type plants. Neither MeJA nor ABA induced reactive oxygen species (ROS) production and suppressed inward-rectifying potassium channel activities in rcn1 mutants but not in wild-type plants. These results suggest that RCN1 functions upstream of ROS production and downstream of the branch point of MeJA signaling and ABA signaling in Arabidopsis guard cells.

Asunto(s)

Ácido Abscísico/metabolismo , Acetatos/metabolismo , Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Ciclopentanos/metabolismo , Oxilipinas/metabolismo , Proteína Fosfatasa 2/metabolismo , Transducción de Señal , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Ácido Ocadaico/farmacología , Estomas de Plantas/efectos de los fármacos , Estomas de Plantas/metabolismo , Canales de Potasio de Rectificación Interna/metabolismo , Proteína Fosfatasa 2/genética , Especies Reactivas de Oxígeno/metabolismo

RESUMEN

Salt stress impairs reactive oxygen species (ROS) and methylglyoxal (MG) detoxification systems, and causes oxidative damage to plants. Up-regulation of the antioxidant and glyoxalase systems provides protection against NaCl-induced oxidative damage in plants. Thiol-disulfide contents, glutathione content and its associated enzyme activities involved in the antioxidant defense and glyoxalase systems, and protein carbonylation in tobacco Bright Yellow-2 cells grown in suspension culture were investigated to assess the protection offered by proline and glycinebetaine against salt stress. Salt stress increased protein carbonylation, contents of thiol, disulfide, reduced (GSH) and oxidized (GSSG) forms of glutathione, and the activity of glutathione-S-transferase and glyoxalase II enzymes, but decreased redox state of both thiol-disulfide and glutathione, and the activity of glutathione peroxidase and glyoxalase I enzymes involved in the ROS and MG detoxification systems. Exogenous application of proline or glycinebetaine resulted in a reduction of protein carbonylation, and in an increase in glutathione redox state and activity of glutathione peroxidase, glutathione-S-transferase and glyoxalase I under salt stress. Neither proline nor glycinebetaine, however, had any direct protective effect on NaCl-induced GSH-associated enzyme activities. The present study, therefore, suggests that both proline and glycinebetaine provide a protective action against NaCl-induced oxidative damage by reducing protein carbonylation, and enhancing antioxidant defense and MG detoxification systems.

Asunto(s)

Antioxidantes/metabolismo , Betaína/farmacología , Nicotiana/citología , Nicotiana/efectos de los fármacos , Prolina/farmacología , Piruvaldehído/metabolismo , Cloruro de Sodio/farmacología , Células Cultivadas , Citoprotección/efectos de los fármacos , Disulfuros/metabolismo , Glutatión/metabolismo , Glutatión Peroxidasa/metabolismo , Glutatión Transferasa/metabolismo , Inactivación Metabólica , Lactoilglutatión Liasa/metabolismo , Oxidación-Reducción/efectos de los fármacos , Carbonilación Proteica/efectos de los fármacos , Compuestos de Sulfhidrilo/metabolismo , Tioléster Hidrolasas/metabolismo , Nicotiana/enzimología

RESUMEN

In the present study, papaya (Carica papaya) seed and edible pulp were carefully separated and then the contents of benzyl isothiocyanate and the corresponding glucosinolate (benzyl glucosinolate, glucotropaeolin) quantified in each part. The papaya seed with myrosinase inactivation contained >1 mmol of benzyl glucosinolate in 100 g of fresh seed. This content is equivalent to that of Karami daikon (the hottest Japanese white radish) or that of cress. The papaya seed extract also showed a very high activity of myrosinase and, without myrosinase inactivation, produced 460 micromol of benzyl isothiocyanate in 100 g of seed. In contrast, papaya pulp contained an undetectable amount of benzyl glucosinolate and showed no significant myrosinase activity. The n-hexane extract of the papaya seed homogenate was highly effective in inhibiting superoxide generation and apoptosis induction in HL-60 cells, the activities of which are comparable to those of authentic benzyl isothiocyanate.

Asunto(s)

Antineoplásicos Fitogénicos/aislamiento & purificación , Carica/química , Isotiocianatos/aislamiento & purificación , Extractos Vegetales/aislamiento & purificación , Antineoplásicos Fitogénicos/farmacología , Carica/enzimología , Fragmentación del ADN/efectos de los fármacos , Glucosinolatos/aislamiento & purificación , Glucosinolatos/farmacología , Glicósido Hidrolasas/metabolismo , Células HL-60 , Humanos , Isotiocianatos/farmacología , Extractos Vegetales/farmacología , Semillas/química , Semillas/enzimología

RESUMEN

Up-regulation of the antioxidant system provides protection against NaCl-induced oxidative damage in plants. Antioxidants and activity of enzymes involved in the ascorbate-glutathione (ASC-GSH) cycle in tobacco Bright Yellow-2 (BY-2) were investigated to assess the antioxidant protection offered by exogenous proline and glycinebetaine (betaine from now on) against salt stress using cells grown in suspension culture. Reduced ascorbate (ASC) was detected in BY-2 cells but dehydroascorbate (DHA) was not. Large quantities of a reduced form of glutathione (GSH) and smaller quantities of an oxidized form of glutathione (GSSG) were detected in BY-2 cells. Salt stress significantly reduced the contents of ASC and GSH as well as activities of ASC-GSH cycle enzymes such as ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), and glutathione reductase (GR). Exogenous proline or betaine increased the activities of all enzymes except MDHAR involved in NaCl-induced ASC-GSH cycle. Levels of ASC and GSH in BY-2 cells under salt stress were lower in the presence of proline or betaine than in the absence of proline or betaine whereas there was no difference in redox status. Proline proved more effective than betaine in maintaining the activity of enzymes involved in NaCl-induced ASC-GSH cycle. Neither proline nor betaine had any direct protective effect on NaCl-induced enzyme activity involved in the antioxidant system; however, both improved salt tolerance by increasing enzyme activity. The present study, together with our earlier findings [Hoque MA, Okuma E, Banu MNA, Nakamura Y, Shimoishi Y, Murata Y. Exogenous proline mitigates the detrimental effects of salt stress more than exogenous betaine by increasing antioxidant enzyme activities. J Plant Physiol 2006;164:553-61.], suggests that proline offered greater protection against salt stress than betaine did because proline was more effective in increasing the activity of enzymes involved in the antioxidant system.

Asunto(s)

Ácido Ascórbico/metabolismo , Betaína/farmacología , Glutatión/metabolismo , Nicotiana/citología , Prolina/farmacología , Cloruro de Sodio/farmacología , Antioxidantes/metabolismo , Células Cultivadas , Regulación de la Expresión Génica de las Plantas , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Protoplastos/efectos de los fármacos , Nicotiana/efectos de los fármacos , Nicotiana/enzimología , Regulación hacia Arriba

RESUMEN

Methyl jasmonate (MeJA) elicits stomatal closing similar to abscisic acid (ABA), but whether the two compounds use similar or different signaling mechanisms in guard cells remains to be clarified. We investigated the effects of MeJA and ABA on second messenger production and ion channel activation in guard cells of wild-type Arabidopsis (Arabidopsis thaliana) and MeJA-insensitive coronatine-insensitive 1 (coi1) mutants. The coi1 mutation impaired MeJA-induced stomatal closing but not ABA-induced stomatal closing. MeJA as well as ABA induced production of reactive oxygen species (ROS) and nitric oxide (NO) in wild-type guard cells, whereas MeJA did not induce production of ROS and NO in coi1 guard cells. The experiments using an inhibitor and scavengers demonstrated that both ROS and NO are involved in MeJA-induced stomatal closing as well as ABA-induced stomatal closing. Not only ABA but also MeJA activated slow anion channels and Ca(2+) permeable cation channels in the plasma membrane of wild-type guard cell protoplasts. However, in coi1 guard cell protoplasts, MeJA did not elicit either slow anion currents or Ca(2+) permeable cation currents, but ABA activated both types of ion channels. Furthermore, to elucidate signaling interaction between ABA and MeJA in guard cells, we examined MeJA signaling in ABA-insensitive mutant ABA-insensitive 2 (abi2-1), whose ABA signal transduction cascade has some disruption downstream of ROS production and NO production. MeJA also did not induce stomatal closing but stimulated production of ROS and NO in abi2-1. These results suggest that MeJA triggers stomatal closing via a receptor distinct from the ABA receptor and that the coi1 mutation disrupts MeJA signaling upstream of the blanch point of ABA signaling and MeJA signaling in Arabidopsis guard cells.

Asunto(s)

Ácido Abscísico/metabolismo , Acetatos/metabolismo , Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Ciclopentanos/metabolismo , Canales Iónicos/metabolismo , Ácido Abscísico/farmacología , Acetatos/farmacología , Arabidopsis/citología , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Calcio/metabolismo , Ciclopentanos/farmacología , Mutación , Óxido Nítrico/metabolismo , Oxilipinas , Fosfoproteínas Fosfatasas/genética , Especies Reactivas de Oxígeno/metabolismo , Transducción de Señal