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1.
In plants, salicylic acid (SA) is a signaling molecule that regulates disease resistance responses, such as systemic acquired resistance (SAR) and hypertensive response (HR). SA has been implicated as participating in various biotic and abiotic stresses. This study was conducted to investigate the role of SA in adventitious root formation (ARF) in mung bean (Phaseolus radiatus L) hypocotyl cuttings. We observed that hypocotyl treatment with SA could significantly promote the adventitious root formation, and its effects were dose and time dependent. Explants treated with SA displayed a 130% increase in adventitious root number compared with control seedlings. The role of SA in mung bean hypocotyl ARF as well as its interaction with hydrogen peroxide (H2O2) were also elucidated. Pretreatment of mung bean explants with N, N’-dimethylthiourea (DMTU), a scavenger for H2O2, resulted in a significant reduction of SA-induced ARF. Diphenyleneiodonium (DPI), a specific inhibitor of membrane-linked NADPH oxidase, also inhibited the effect of adventitious rooting triggered by SA treatment. The determination of the endogenous H2O2 level indicated that the seedlings treated with SA could induce H2O2 accumulation compared with the control treatment. Our results revealed a distinctive role of SA in the promotion of adventitious rooting via the process of H2O2 accumulation. This conclusion was further supported by antioxidant enzyme activity assays. Based on these results, we conclude that the accumulation of free H2O2 might be a downstream event in response to SA-triggered adventitious root formation in mung bean seedlings.  相似文献   

2.
Our previous results have demonstrated that both nitric oxide (NO) and hydrogen peroxide (H2O2) are involved in the promotion of adventitious root development in marigold (Tagetes erecta L.). However, not much is known about the intricate molecular network of adventitious root development triggered by NO and H2O2. In this study, the involvement of calcium (Ca2+) and calmodulin (CaM) in NO- and H2O2-induced adventitious rooting in marigold was investigated. Exogenous Ca2+ was capable of promoting adventitious rooting, with a maximal biological response at 50 μM CaCl2. Ca2+ chelators and CaM antagonists prevented NO- and H2O2-induced adventitious rooting, indicating that both endogenous Ca2+ and CaM may play crucial roles in the adventitious rooting induced by NO and H2O2. NO and H2O2 treatments increased the endogenous content of Ca2+ and CaM, suggesting that NO and H2O2 enhanced adventitious rooting by stimulating the endogenous Ca2+ and CaM levels. Moreover, treatment with Ca2+ enhanced the endogenous levels of NO and H2O2. Additionally, Ca2+ might be involved as an upstream signaling molecule for CaM during NO- and H2O2-induced rooting. Altogether, the results suggest that both Ca2+ and CaM are two downstream signaling molecules in adventitious rooting induced by NO and H2O2.  相似文献   

3.
Hydrogen peroxide (H2O2), an active oxygen species, is widely generated in many biological systems and mediates various physiological and biochemical processes in plants. In the present study, we present a signaling network involving H2O2, nitric oxide (NO), calcium (Ca2+), cyclic guanosine monophosphate (cGMP), and the mitogen-activated protein kinase (MAPK) cascade during adventitious rooting in mung bean seedlings. Both exogenous H2O2 and the NO donor sodium nitroprussiate were capable of promoting the formation and development of adventitious roots. H2O2 and NO signaling pathways were elicited in parallel in auxin-induced adventitious rooting. Cytosolic Ca2+ was required for adventitious rooting, and Ca2+ served as a downstream component of H2O2, as well as cGMP or MAPK, signaling cascades. cGMP and MAPK cascades function downstream of H2O2 signaling and depend on auxin responses in adventitious root signaling processes.  相似文献   

4.
It is well known that plant adventitious root formation can be stimulated by the application of nitric oxide (NO) and hydrogen peroxide (H2O2) exogenously but the mechanism of this physiological response is still unclear. Ground-cover chrysanthemum (Dendranthema morifolium ‘Beiguozhicun’) was used to understand the effects of NO and H2O2 on the rooting of plant cuttings and the associated biochemical changes of the rooting zone during the rhizogenesis process. The results showed that the effect of NO or H2O2 on rooting of ground-cover chrysanthemum cuttings was dose-dependent, with a maximal biological response at 50 μM of NO donor sodium nitroprusside (SNP) or 200 μM H2O2. There was a synergistic effect between NO and H2O2 on mediating rooting. NO and H2O2 treatments at the proper dosage might increase the activities of polyphenol oxidase (PPO) and indoleacetic acid oxidase (IAAO) and the content of water-soluble carbohydrate (WSC) and total nitrogen, while decreasing the total polyphenol content of ground-cover chrysanthemum cuttings. In addition, rooting percentage was significantly correlated with these biochemical constituent activities or contents. Together, these results indicated that NO and H2O2 treatments enhanced adventitious root development synergistically and independently by stimulating the activities of PPO and IAAO enzymes and the content of carbohydrate and nitrogen and simultaneously repressing the production of polyphenol.  相似文献   

5.
For perennial woody plants, softwood cutting is an efficient technique for larger scale propagation and adventitious rooting of cuttings is one of the most crucial steps. To evaluate the significance of juvenility on adventitious rooting, rooting rates was compared between softwood cuttings collected from apomictic seedlings (juvenile), in vitro cultured plants (rejuvenated), suckers (juvenile like) and canopy shoots (adult) of reproductively mature trees in Malus xiaojinensis. After pre-treatment with indole-3-butytric acid (IBA) (3,000 mg L?1) + H2O2 (50 mM), rooting rates in cutting from juvenile, juvenile like and rejuvenated donor plants were significantly higher (>90 %) than that from adult trees. The effects of IBA on adventitious rooting were enhanced significantly by exogenous H2O2. After 15 passages of in vitro subculture, the micro-shoots from adult phase explants were rejuvenated successfully, marked by the elevated expression of miR156 in the leaflets of the micro-shoots. But the rooting ability of rejuvenated micro-shoots was recovered delayed at the 18th or 21st passage of subculture. During the process of rejuvenation, the leaf indole-3-acetic acid contents and the expressions of rooting related genes CKI1, ARRO-1, ARF7 and ARF19 increased significantly. In contrary, the leaf abscisic acid contents decreased. A lack of juvenility is the most important limiting factor governing adventitious rooting of softwood cuttings in apple rootstocks.  相似文献   

6.
The present paper reports results of experiments to develop a system for studying adventitious root initiation in cuttings derived from seedlings. Hypocotyl cuttings of 2-week-old eastern white pine (Pinus strobus L.) seedlings were treated for 5 min with 0, 100, 200, 300, 400, 500 or 600 mg l?1 (0, 0.54, 1.07, 1.61, 2.15, 2.69 or 3.22 mM) 1-naphthaleneacetic acid (NAA) to determine the effect on root initiation. The number of root primordia per cutting was correlated with NAA concentration and the square of NAA concentration. Thus, the number increased from less than one per cutting in the 0 NAA treatment to approximately 40 per cutting at 300 mg l-1 NAA, above which no substantial further increase was observed. The larger number of root primordia formed in response to increasing concentrations of NAA was due to the formation of primordia over a larger proportion of the hypocotyls. Histological analysis of the timing of root primordium formation in hypocotyl cuttings revealed three discernible stages. Progression through these stages was relatively synchronous among NAA-treated hypocotyl cuttings and within a given cutting, but variation was observed in the portion of different cuttings undergoing root formation. Control-treated hypocotyl cuttings formed root primordia at lower frequencies and more slowly than NAA-treated cuttings, with fewer primordia per cutting. Epicotyl cuttings from 11-week-old seedlings also formed adventitious roots, but more slowly than hypocotyl cuttings. NAA treatment of epicotyl cuttings caused more rapid root initiation and also affected the origin of adventitious roots in comparison with nontreated cuttings. NAA-treated epicotyl cuttings formed roots in a manner analogous to that of the hypocotyl cuttings, directly from preformed vascular tissue, while control-treated epicotyl cuttings first formed a wound or callus tissue and subsequently differentiated root primordia within that tissue. This system of inducing adventitious roots in pine stem cuttings lends itself to studying the molecular and biochemical steps that occur during root initiation and development.  相似文献   

7.
Tetrastigma hemsleyanum suspension cells were treated with four metal salts to screen suitable elicitors for the promotion of plant cell biomass and flavonoid production. The effects of calcium ions (Ca2+) on induction were also studied. It was found that the most effective elicitors were 50 μM of the heavy metal ion copper (Cu2+) and 100 μM of the rare earth element cerium (Ce3+). The maximal biomass levels under respective treatments over a 16-d culture period increased by 1.3- and 1.6-fold, and the total flavonoid content was 1.8- and 1.6-fold greater than the control, respectively. Reducing the exogenous Ca2+ concentration or adding Ca2+ antagonists (1 mM ethylene glycol-bis(2-aminoethylether)-N,N,N′,N-tetraacetc acid (EGTA) or 1 mM verapamil) strengthened inductive effects of metal elicitors and enhanced flavonoid production. However, 0.5 μM of the calcium ionophore A23187 showed contrary results. The increase in exogenous Ca2+ concentration in the presence of A23187 suppressed H2O2 bursts and peroxidase activity caused by metal elicitors. The results suggest that Ca2+ plays an inhibitory role in the plant cell response to metal elicitors. This suppression could have been caused by Ca2+ preventing the cells from absorbing metal ions and then easing the induction, or because the decrease of Ca2+ concentration worked as an induction signal. Therefore, reducing the Ca2+ concentration in culture medium, or adding Ca2+ antagonists could be used to improve flavonoid production and cell growth in combination with induction by metal elicitors during in vitro culture of T. hemsleyanum suspension cells.  相似文献   

8.
The effects of Ca2+ on antioxidative enzymes and indole-3-acetic acid (IAA) oxidase during adventitious rooting were investigated in mung bean (Vigna radiata). CaCl2 significantly promoted the formation and growth of adventitious roots. EGTA (a Ca2+ chelator) or ruthenium red (a Ca2+-channel blocker) significantly inhibited root formation and growth, but these inhibitory effects could be partially reversed by CaCl2. Furthermore, inclusion of 5 mM CaCl2 significantly increased superoxide dismutase (SOD) activity by 10% at 3 h and catalase (CAT) activity by an average of 29.6% at each time point. CaCl2 decreased peroxidase (POD) activity by 9.4% and 21% at 12 and 24 h, respectively, and ascorbate peroxidase (APX) activity by an average of 13.9% at each time point. These CaCl2-induced changes in enzymatic activities were similar to changes caused by indole-3-butyric acid (IBA). Treatment with EGTA or ruthenium red decreased SOD activity by an average of 18.4% and 15.2%, respectively; POD activity by 27.4% and 57.6%, respectively; APX activity by 10.3% and 15.6%, respectively; and CAT activity by 19.3% and 5.2%, respectively, when compared with CaCl2. In addition, CaCl2 increased IAA oxidase activity by an average of 5.5% beginning at 6 h, whereas EGTA significantly decreased IAA oxidase activity by 29.2%, 22.9%, and 13.5% at 6, 9, and 12 h, respectively. The inhibitory effects of EGTA could be partially suppressed by addition of CaCl2. These results imply that the stimulative effect of Ca2+ on adventitious rooting is partially related to Ca2+-induced changes in the activities of antioxidative enzymes and IAA oxidase.  相似文献   

9.
Seaweed tissue culture (STC) is an important micropropagation tool that has been applied for strain improvement, micropropagation and genetic engineering. Because the mechanisms associated with STC are poorly understood, its application to these organisms lags far behind that of tissue culture propagation of higher plants. Auxin, calcium (Ca2+) and hydrogen peroxide (H2O2) fluxes all play key roles during plant growth and development. In this study, we therefore measured indole‐3‐acetic acid, Ca2+ and H2O2 fluxes of Gracilaria lichenoides explants during adventitious branches (ABs) formation for the first time using noninvasive micro‐test technology. We confirmed that polar auxin transport (PAT) also occurs in the marine red alga G. lichenoides. We additionally found that N‐1‐naphthylphthalamic acid may suppress auxin efflux via ABCB1 transporters and then inhibit ABs formation from the apical region of G. lichenoides segments. The involvement of Ca2+ and H2O2 fluxes in PAT‐mediated AB formation in G. lichenoides was also investigated. We propose that complex feedback among Ca2+, H2O2 and auxin signaling and response systems may occur during ABs polar formation in G. lichenoides explants, similar to that in higher plants. Our results provide innovative insights that should aid future elucidation of mechanisms operative during STC.  相似文献   

10.
To determine the contribution of polar auxin transport (PAT) to auxin accumulation and to adventitious root (AR) formation in the stem base of Petunia hybrida shoot tip cuttings, the level of indole-3-acetic acid (IAA) was monitored in non-treated cuttings and cuttings treated with the auxin transport blocker naphthylphthalamic acid (NPA) and was complemented with precise anatomical studies. The temporal course of carbohydrates, amino acids and activities of controlling enzymes was also investigated. Analysis of initial spatial IAA distribution in the cuttings revealed that approximately 40 and 10 % of the total IAA pool was present in the leaves and the stem base as rooting zone, respectively. A negative correlation existed between leaf size and IAA concentration. After excision of cuttings, IAA showed an early increase in the stem base with two peaks at 2 and 24 h post excision and, thereafter, a decline to low levels. This was mirrored by the expression pattern of the auxin-responsive GH3 gene. NPA treatment completely suppressed the 24-h peak of IAA and severely inhibited root formation. It also reduced activities of cell wall and vacuolar invertases in the early phase of AR formation and inhibited the rise of activities of glucose-6-phosphate dehydrogenase and phosphofructokinase during later stages. We propose a model in which spontaneous AR formation in Petunia cuttings is dependent on PAT and on the resulting 24-h peak of IAA in the rooting zone, where it induces early cellular events and also stimulates sink establishment. Subsequent root development stimulates glycolysis and the pentose phosphate pathway.  相似文献   

11.
Rat and pigeon heart mitochondria supplemented with antimycin produce 0.3–1.0nmol of H2O2/min per mg of protein. These rates are stimulated up to 13-fold by addition of protophores (carbonyl cyanide p-trifluoromethoxyphenylhydrazone, carbonyl cyanide m-chloromethoxyphenylhydrazone and pentachlorophenol). Ionophores, such as valinomycin and gramicidin, and Ca2+ also markedly stimulated H2O2 production by rat heart mitochondria. The enhancement of H2O2 generation in antimycin-supplemented mitochondria and the increased O2 uptake of the State 4-to-State 3 transition showed similar protophore, ionophore and Ca2+ concentration dependencies. Thenoyltrifluoroacetone and N-bromosuccinimide, which inhibit succinate–ubiquinone reductase activity, also decreased mitochondrial H2O2 production. Addition of cyanide to antimycin-supplemented beef heart submitochondrial particles inhibited the generation of O2, the precursor of mitochondrial H2O2. This effect was parallel to the increase in cytochrome c reduction and it is interpreted as indicating the necessity of cytochrome c13+ to oxidize ubiquinol to ubisemiquinone, whose autoxidation yields O2. The effect of protophores, ionophores and Ca2+ is analysed in relation to the propositions of a cyclic mechanism for the interaction of ubiquinone with succinate dehydrogenase and cytochromes b and c1 [Wikstrom & Berden (1972) Biochim. Biophys. Acta 283, 403–420; Mitchell (1976) J. Theor. Biol. 62, 337–367]. A collapse in membrane potential, increasing the rate of ubisemiquinone formation and O2 production, is proposed as the molecular mechanism for the enhancement of H2O2 formation rates observed on addition of protophores, ionophores and Ca2+.  相似文献   

12.
Hydrogen peroxide (H2O2), an active oxygen species, is widely generated in many biological systems and mediates various physiological and biochemical processes in plants. In this study we demonstrated that the exogenous H2O2 was able to promote the formation and development of adventitious roots in mung bean seedlings. Treatments with 1–100 mM H2O2 for 8–18 h significantly induced the formation and development of adventitious roots. Catalase (CAT) and ascorbic acid, which are H2O2 scavengers or inhibitors, eliminated the adventitious root-promoting effects of exogenous H2O2. H2O2 may have a downstream signaling function in the auxin signaling pathway and be involved in auxin-induced adventitious root formation. 2,3,5-Triiodobenzoic acid (TIBA), an inhibitor of auxin polar transport, strongly inhibited adventitious rooting of mung bean seedlings; however, the inhibiting effects of TIBA on adventitious rooting can be partially reversed by the exogenous IBA or H2O2. Diphenylene iodonium (DPI) strongly inhibits the activity of NADPH oxidase, which is one of the main sources of H2O2 formation in plant cells. DPI treatment strongly inhibited the formation of adventitious roots in mung bean, but the inhibitory effects of DPI on rooting can be partially reversed by the exogenous H2O2 or IBA. This indicates that the formation of adventitious roots was blocked once the generation of H2O2 through NADPH oxidase was inhibited, and H2O2 mediated the IBA-induced adventitious root formation. Furthermore, a rapid increase in the endogenous level of H2O2 was detected during incubation with water 12–36 h after the primary root removal in mung bean seedlings. Three hours after the primary root removal, the generation of endogenous H2O2 was markedly induced in IBA-treated seedlings in comparison with water-treated seedlings. This implies that IBA induced overproduction of H2O2 in mung bean seedlings, and that IBA promoted adventitious root formation via a pathway involving H2O2. Results obtained suggest that H2O2 may function as a signaling molecule involved in the formation and development of adventitious roots in mung bean seedlings.  相似文献   

13.
Salinity is among the environmental factors that affect plant growth and development and constrain agricultural productivity. Salinity stress triggers increases in cytosolic free Ca2+ concentration ([Ca2+]i) via Ca2+ influx across the plasma membrane. Salinity stress, as well as other stresses, induces the production of reactive oxygen species (ROS). It is well established that ROS also triggers increases in [Ca2+]i. However, the relationship and interaction between salinity stress-induced [Ca2+]i increases and ROS-induced [Ca2+]i increases remain poorly understood. Using an aequorin-based Ca2+ imaging assay we have analyzed [Ca2+]i changes in response to NaCl and H2O2 treatments in Arabidopsis thaliana. We found that NaCl and H2O2 together induced larger increases in [Ca2+]i in Arabidopsis seedlings than either NaCl or H2O2 alone, suggesting an additive effect on [Ca2+]i increases. Following a pre-treatment with either NaCl or H2O2, the subsequent elevation of [Ca2+]i in response to a second treatment with either NaCl or H2O2 was significantly reduced. Furthermore, the NaCl pre-treatment suppressed the elevation of [Ca2+]i seen with a second NaCl treatment more than that seen with a second treatment of H2O2. A similar response was seen when the initial treatment was with H2O2; subsequent addition of H2O2 led to less of an increase in [Ca2+]i than did addition of NaCl. These results imply that NaCl-gated Ca2+ channels and H2O2-gated Ca2+ channels may differ, and also suggest that NaCl- and H2O2-evoked [Ca2+]i may reduce the potency of both NaCl and H2O2 in triggering [Ca2+]i increases, highlighting a feedback mechanism. Alternatively, NaCl and H2O2 may activate the same Ca2+ permeable channel, which is expressed in different types of cells and/or activated via different signaling pathways.  相似文献   

14.
An efficient protocol for adventitious root induction from leaf explants of Morinda citrifolia treated with different concentrations of indole-3-butyric acid (IBA) and α-naphthaleneacetic acid (NAA) was established in relation to physiological process changes during adventitious root induction under different light sources (fluorescent, red, blue, red + blue, and far-red). Among the different concentrations of IBA and NAA, 1.0 mg l−1 IBA was proven as the best auxin source for adventitious root induction under fluorescent light. Higher concentrations of IBA and NAA trigger callus formation in both light and dark conditions. Maximum numbers of adventitious roots were induced under red light (26) followed by blue light (22) and the lowest under far-red light (6). In contrast, numerous callus formations were induced by red + blue followed by red and blue, while the highest root length (1.66 cm) with negligible callusing was observed under fluorescent light. Catalase and guaicacol peroxidase activities were highest under red light followed by fluorescent light and the lowest under red + blue light, but superoxide dismutase activity was not significantly influenced by different light sources. Ascorbate peroxidase played an important role in detoxification of the harmful effects of hydrogen peroxide (H2O2). Under fluorescent light, significantly lower accumulation of H2O2 was observed. Accumulation of H2O2 in the induced root under different light showed a positive correlation with peroxidation of lipids and was observed higher under far-red followed by red + blue and blue light.  相似文献   

15.
16.
Oxidative reactions can result in the formation of electronically excited species that undergo radiative decay depending on electronic transition from the excited state to the ground state with subsequent ultra‐weak photon emission (UPE). We investigated the UPE from the Fe2+–EDTA (ethylenediaminetetraacetic acid)–AA (ascorbic acid)–H2O2 (hydrogen peroxide) system with a multitube luminometer (Peltier‐cooled photon counter, spectral range 380–630 nm). The UPE, of 92.6 μmol/L Fe2+, 185.2 μmol/L EDTA, 472 μmol/L AA, 2.6 mmol/L H2O2, reached 1217 ± 118 relative light units during 2 min measurement and was about two times higher (P < 0.001) than the UPE of incomplete systems (Fe2+–AA–H2O2, Fe2+–EDTA–H2O2, AA–H2O2) and medium alone. Substitution of Fe2+ with Cr2+, Co2+, Mn2+ or Cu2+ as well as of EDTA with EGTA (ethylene glycol‐bis(β‐aminoethyl ether)‐N,N,N′,N′‐tetraacetic acid) or citrate powerfully inhibited UPE. Experiments with scavengers of reactive oxygen species (dimethyl sulfoxide, mannitol, sodium azide, superoxide dismutase) revealed the dependence of UPE only on hydroxyl radicals. Dimethyl sulfoxide at the concentration of 0.74 mmol/L inhibited UPE by 79 ± 4%. Plant phenolics (ferulic, chlorogenic and caffec acids) at the concentration of 870 μmol/L strongly enhanced UPE by 5‐, 13.9‐ and 46.8‐times (P < 0.001), respectively. It is suggested that augmentation of UPE from Fe2+–EDTA–AA–H2O2 system can be applied for detection of these phytochemicals.  相似文献   

17.
Functional interactions of calcium ions, hydrogen peroxide, and nitric oxide as signal mediators in root cells of wheat (Triticum aestivum L.) seedlings upon induction of their heat resistance was studied with use of inhibitor-based analysis. Treatment of the seedlings with hydrogen peroxide or a combination of calcium chloride with ionophore A23187 significantly increased their content of nitric oxide, which peaked 0.5–1 h after the start of the treatment. CaCl2 or exogenous NO donor (sodium nitroprusside, SNP) transitorily increased the hydrogen peroxide level in the roots. Seedlings pretreatments with calcium chelator (EGTA), blocker of Ca2+ channels (LaCl3), inhibitor of phospholipase C (neomycin), or antagonist of cyclic adenosine-5'-diphosphatribose formation (nicotinamide) more or less prevented the rise in the nitric oxide content in roots caused by exogenous H2O2; the SNP-induced rise in hydrogen peroxide was also damped down. However, the seedlings pretreatment with antioxidants ionol or dimethylthiourea did not hinder the increase in the NO level, which was caused by exogenous Ca2+. The inhibitors of NO synthase (NG-nitro-L-arginine methyl ester, L-NAME) or nitrate reductase (sodium tungstate) did not interfere in the accumulation of H2O2 in root tissues stimulated by exogenous calcium. Calcium antagonists diminished the seedlings heat resistance increased by hydrogen peroxide or SNP. Antioxidants and inhibitors of NO synthase or nitrate reductase weakened the calcium-stimulated enhancement in the seedlings heat resistance. It was concluded that calcium may activate NO- and H2O2-generating enzymatic systems as well as participate in the transduction of signals of these mediators into genetic apparatus and in the formation of physiological reactions underlying the enhanced heat resistance.  相似文献   

18.
It has been widely suggested that selenium (Se) deficiency play an important role in the pathophysiology of epilepsy. It has been reported that Se provides protection against the neuronal damage in patients and animals with epilepsy by restoring the antioxidant defense mechanism. The neuroprotective effects of topiramate (TPM) have been reported in several studies but the putative mechanism of action remains elusive. We investigated effects of Se and TPM in neuronal PC12 cell by evaluating Ca2+ mobilization, lipid peroxidation and antioxidant levels. PC12 cells were divided into eight groups namely control, TPM, Se, H2O2, TPM + H2O2, Se + H2O2, Se + TPM and Se + TPM + H2O2. The toxic doses and times of H2O2, TPM and Se were determined by cell viability assay which is used to evaluate cell viability. Cells were incubated with 0.01 mM TPM for 5 h and 500 nM Se for 10 h. Then, the cells were exposed to 0.1 mM H2O2 for 10 h before analysis. The cells in all groups except control, TPM and Se were exposed to H2O2 for 15 min before analysis. Cytosolic Ca2+ release and lipid peroxidation levels were higher in H2O2 group than in control, Se and TPM combination groups although their levels were decreased by incubation of Se and TPM combination. However, there is no difference on Ca2+ release in TPM group. Glutathione peroxidase activity, reduced glutathione and vitamin C levels in the cells were lower in H2O2 group than in control, Se and TPM groups although their values were higher in the cells incubated with Se and TPM groups than in H2O2 groups. In conclusion, these results indicate that Se induced protective effects on oxidative stress in PC12 cells by modulating cytosolic Ca2+ influx and antioxidant levels. TPM modulated also lipid peroxidation and glutathione and vitamin C concentrations in the cell system.  相似文献   

19.
Reactive oxygen species (ROS) generated by a variety of endogenous factors and roles in embryonic stem (ES) cells has yet to be identified. Thus, we examined role of arachidonic acid (AA) in H2O2‐indued proliferation of mouse ES cells and its related signaling molecules. AA release was maximally increased in response to 10?4 M H2O2 for 1 h. In addition, H2O2 increased intracellular Ca2+ concentration ([Ca2+]i) and the phosphorylation of protein kinase C (PKC), p44/42, p38 mitogen‐activated protein kinase (MAPK), and JNK/SAPK. Moreover, H2O2 induced an increase in the phosphorylation of epidermal growth factor receptor (EGFR), which was blocked by the inhibition of p44/42 or p38 MAPKs. The inhibition of each signal molecule with specific inhibitors blocked H2O2‐induced cytosolic phospholipase A2 (cPLA2) activation and AA release. H2O2 increased NF‐κB phosphorylation to induce an increase in the levels of cyclooxygenase (COX)‐2 proteins. Subsequently, H2O2 stimulated PGE2 synthesis, which was reduced by the inhibition of NF‐κB activation. Moreover, each H2O2 or PGE2 increased DNA synthesis and the number of cells. However, H2O2‐induced increase in DNA synthesis was inhibited by the suppression of cPLA2 pathway. In conclusion, H2O2 increased AA release and PGE2 production by the upregulation of cPLA2 and COX‐2 via Ca2+/PKC/MAPKs and EGFR transactivation, subsequently proliferation of mouse ES cells. J. Cell. Biochem. 106: 787–797, 2009. © 2009 Wiley‐Liss, Inc.  相似文献   

20.
The involvement of NO in O2 ·− generation, rootlet development and antioxidant defence were investigated in the adventitious root cultures of mountain ginseng. Treatments of NO producers (SNP, sodium nitroprusside; SNAP, S-nitroso-N-acetylpenicillamine; and sodium nitrite with ascorbic acid), and NO scavenger (PTIO, 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl3-oxide) revealed that NO is involved in the induction of new rootlets. Severe decline in number of new rootlets compared to the control under PTIO treatment indicates that NO acts downstream of auxin action in the process. NO producers (SNP, SNAP and sodium nitrite with ascorbic acid) activated NADPH oxidase activity, resulting in greater O2 ·− generation and higher number of new rootlets in the adventitious root explants. Moreover, treatment of diphenyliodonium chloride, a NADPH oxidase inhibitor, individually or along with SNP, inhibited root growth, NADPH oxidase activity and O2 ·− anion generation. NO supply also enhanced the activities of antioxidant enzymes that are likely to be responsible for reducing H2O2 levels and lipid peroxidation as well as modulation of ascorbate and non-protein thiol concentrations in the adventitious roots. Our results suggest that NO-induced generation of O2 ·− by activating NADPH oxidase activity is related to adventitious root formation in mountain ginseng.  相似文献   

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