NO和H2O2在IBA诱导万寿菊不定根形成中的作用

 研究了一氧化氮（NO）和过氧化氢（H₂O₂）在吲哚丁酸（IBA）诱导万寿菊（Tagetes erecta L.）外植体不定根形成过程中的作用及其相互关系。结果表明：外源IBA与NO、H₂O₂一样对万寿菊外植体不定根形成有促进作用,且IBA与NO,IBA与H₂O₂协同增效。NO清除剂cPTIO和H₂O₂清除剂CAT均能抑制IBA对不定根形成的促进作用。同样,cPTIO和CAT亦能抵消IBA对NPA抑制不定根形成的逆转作用。可见,NO和H₂O₂是IBA诱导万寿菊不定根形成的必要条件。IBA处理提高了外植体内源NO和H₂O₂的含量,说明IBA是通过增加内源NO和H₂O₂水平实现对不定根形成的促进作用。cPTIO和L-NAME抑制了IBA对H₂O₂含量的促进作用,而CAT和DPI却不能抑制IBA对NO含量的促进作用。可见,NO和H₂O₂是IBA诱导万寿菊不定根形成的两个下游信号分子,且NO可能位于H₂O₂的上游。     

番茄果实采后一氧化氮处理对活性氧代谢的影响

 以番茄品种‘百利’为试材, 研究了NO处理对其采后活性氧代谢的影响。结果表明: NO处理可推迟果实呼吸和乙烯高峰的出现, 抑制O·₂ 和H₂O₂ 的累积, 保持了贮藏后期SOD、CAT、POD、APX 较高的活性以及GSH和AsA含量的较高水平, 延缓了MDA含量和膜相对透性的升高, 降低膜脂过氧化程度, 延缓了果实衰老。     

草酸对冷藏期间桃果实抗氧化系统和PPO活性的影响

 桃( Prunus persica L. ) 栽培品种‘八月脆’果实采后经5 mmol·L ^{- 1}草酸溶液浸泡10 min后在低温条件下贮藏, 与对照相比, 果实的CAT和PPO活性提高, SOD和POD活性在贮藏10 d后较高; 还原型抗坏血酸(AsA) 含量下降减缓; 超氧阴离子(O₂· ) 生成速率随贮藏增加, 过氧化氢(H₂O₂ ) 含量先升后降, 但经草酸处理后O₂ ·生成速率和H₂O₂ 含量分别在5 d和5、10 d时显著低于对照。说明草酸处理通过提高果实抗氧化防御系统的能力和PPO活性来延缓果实成熟和增强果实抗病能力。     

草酸处理对杧果采后果实AsA-GSH循环系统的影响

 杧果（Mangifera indica L.）栽培品种‘圣心’采前套袋果实采后经5 mmol · L^-1草酸溶液浸泡10 min后常温（25 ℃）下贮藏,期间果实硬度系数、病情指数、腐烂率、黄化都显著低于对照;其中,处理果实果皮的还原型抗坏血酸（AsA）和还原型谷胱甘肽（GSH）含量保持较高,抗坏血酸氧化酶（APX）和谷胱甘肽还原酶（GR）活性在贮藏9 d后提高,同时,超氧阴离子（）生成速率、过氧化氢（H₂O₂）含量和丙二醛（MDA）含量降低,说明草酸处理可通过提高果皮AsA-GSH循环系统中抗氧化酶活性和抗氧化剂水平来增强清除活性氧自由基（ROS）能力,减轻膜脂过氧化伤害,进而有利于延缓套袋杧果采后成熟衰老进程,提高果实的商品率。     

外源硫化氢对镉胁迫下黄瓜胚轴和胚根生理生化特性的影响

 以黄瓜（Cucumis sativus L.）种子为试材,研究了外源H₂S预处理对镉胁迫下黄瓜胚轴和胚根生理生化特性的影响。结果表明：用浓度为300、600、900和1 200 μmol · L^-1的H₂S供体NaHS预处理黄瓜种子均能显著缓解镉胁迫对其胚轴和胚根的抑制作用,其中以900 μmol · L^-1 NaHS处理效果最好。NaHS处理显著提高了镉胁迫下黄瓜子叶中淀粉酶的活性及胚轴与胚根中SOD、POD、CAT和APX活性,提高了二苯代苦味酰基自由基（DPPH· ）清除能力和羟基自由基（OH· ）清除能力,从而降低了MDA和H₂O₂含量,而其他钠盐（Na₂S、Na₂SO₄、NaHSO₄、Na₂SO₃、NaHSO₃和NaAc）处理效果甚微,表明NaHS缓解镉胁迫对黄瓜胚轴和胚根生长的抑制作用归因于其释放出的H₂S。     

硒对酥梨叶片衰老及抗氧化酶系统的影响

 研究喷施Na₂SeO₃对砀山酥梨（Pyrus bretschneider Rehd.‘Dangshan Suli’）叶片衰老及抗氧化酶系统的影响。结果表明：与对照相比,喷施低浓度的硒（5 mg · L^-1）,可明显延迟衰老叶片含水量、干样质量、叶绿素和可溶性蛋白含量的下降,显著提高SOD和GSH-Px活性,降低H₂O₂、和MDA含量,平均延迟落叶7.25 d;喷施中等（10 mg · L^-1）和高浓度（20 mg · L^-1）的硒对延缓叶片衰老的效果变差,且浓度越高,效果越差;叶面喷硒对POD活性具有抑制作用。硒延缓梨树叶片衰老存在浓度差异,低浓度的硒可能通过提高SOD、GSH-Px等酶的活性参与叶片衰老进程的调控,从而降低膜脂过氧化水平,延长叶片功能期。     

钙对盐胁迫下黄瓜幼苗抗氧化系统的影响

以黄瓜（Cucumis sativus L.）品种‘津春2号’为材料,采用Hogland营养液栽培研究了Ca2+对盐（NaCl）胁迫下黄瓜幼苗体内可溶性蛋白和丙二醛（MDA）含量、超氧阴离子（）产生速率以及超氧化物歧化酶（SOD）、过氧化物酶（POD）、过氧化氢酶（CAT）活性的影响。结果表明：盐胁迫处理下,黄瓜幼苗体内可溶性蛋白和MDA含量、产生速率以及抗氧化酶SOD、POD、CAT活性均高于对照;营养液中加入Ca2+（8 mmol • L-1）后,幼苗体内可溶性蛋白含量和SOD、POD、CAT抗氧化酶活性进一步提高,而MDA含量和的产生速率降低;而营养液缺钙处理下幼苗体内MDA和产生速率进一步提高,可溶性蛋白含量和抗氧化酶活性较盐胁迫降低。可见外源Ca2+可通过促进盐胁迫下黄瓜幼苗植株体内抗氧化酶活性的提高,降低膜脂过氧化水平,减缓盐胁迫对植株的伤害,从而增强对盐胁迫的适应性。     

干旱胁迫下外源ABA对姜叶片活性氧代谢的影响

为探讨外源ABA调控姜干旱胁迫的生理机制,以‘莱芜大姜’为试材,采用砂培,通过模拟干旱（5% PEG）和根系外施ABA（0.05 mmol ? L-1）,研究ABA对姜叶片活性氧代谢的影响。结果表明,外源ABA显著增加了姜叶片内源ABA含量,且以干旱胁迫下增加量为最多;同时,外源ABA亦有利于保持姜叶片较高的相对含水量。姜根系外施ABA早期,植株叶片的超氧化物歧化酶（SOD）、过氧化物酶（POD）及过氧化氢酶（CAT）活性均增强,进而显著降低了叶片中超氧阴离子（）产生速率及过氧化氢（H2O2）含量,延缓了膜脂过氧化产物丙二醛（MDA）含量的增加;虽外源ABA处理后期,随干旱胁迫时间的延长,外施ABA处理植株叶片抗氧化酶活性有所降低,但其活性氧水平及MDA含量仍显著低于单一的干旱胁迫处理。表明外施0.05 mmol ? L-1ABA有利于维持姜叶片活性氧代谢的正常进行,降低膜脂过氧化水平,增强植株抗干旱能力。     

水分胁迫对马铃薯试管苗抗氧化酶活性的影响

采用聚乙二醇(Polyethylene Glycol-6000)(PEG-6000)模拟根际水分胁迫法,对马铃薯试管苗进行了水分胁迫处理,选用了陇薯3号和大西洋2个品种,设对照(0% PEG)和处理(10% PEG)2个水平,对MDA含量和消除活性氧代谢的保护酶(CAT、POD和SOD)的活性进行了动态变化规律研究.结果表明:经水分胁迫后,马铃薯试管苗叶片MDA含量、CAT、POD和SOD活性上升;再经过一定时间的水分胁迫后,陇薯3号和大西洋叶片MDA含量、CAT、POD和SOD活性分别达到不同峰值,随后各品种活性氧清除酶类SOD、POD和CAT活性及MDA含量开始下降;当解除水分胁迫后,CAT、POD、SOD活性开始上升,MDA含量降低,试验中2个马铃薯品种对水分胁迫敏感程度存在差异.     

硅对黄瓜幼苗生长及活性氧清除系统的影响

在水培条件下,研究了营养液中硅对黄瓜幼苗生长和活性氧清除系统的影响。结果表明,施硅处理可以促进黄瓜植株的生长,叶片中叶绿素含量增加,内源抗氧化物质抗坏血酸(AsA)含量增加,超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性升高,丙二醛(MDA)含量降低。     

核黄素处理促进‘巨峰’葡萄提早成熟的研究

基于核黄素在光照下易分解产生活性氧的特性,设其浓度梯度为0(对照)、0.1、0.5、1.0mmol·L~(-1),分别于‘巨峰’葡萄花后40 d喷施,研究外源活性氧对葡萄果实发育的影响。结果表明:不同浓度的核黄素处理均可促进‘巨峰’葡萄果实提前成熟,以0.5 mmol·L~(-1)效果最好,使果实提前成熟16 d。0.5 mmol·L~(-1)核黄素处理后,显著提升了果实发育前期可溶性糖及转色期花青苷的含量,果实发育前期过氧化氢(H_2O_2)含量,同时也提高了果胶酶(PG)、纤维素酶及脂氧合酶(LOX)的活性,虽然NADPH氧化酶(NOX)活性有所提升,但超氧化物歧化酶(SOD)活性及超氧阴离子产生速率均下降,推测前期升高的H_2O_2可能来源于LOX等其他途径,而H_2O_2含量的上升并没有引起细胞损伤(MDA含量无差异),适宜浓度的外源活性氧能够启动与葡萄果实快速发育有关活性氧产生途径,从而促进果实的发育。     

Response of mitochondrial reactive oxygen species in pulmonary arterial smooth muscle cells under acute hypoxic condition

AIM:To observe the response of mitochondrial reactive oxygen species (ROS) in rat pulmonary artery smooth muscle cells (PASMCs) under acute hypoxic condition. METHODS:The cultured PASMCs were under normoxic (35 ℃, 5% CO2, 21% O2, 74% N2) or acute hypoxic (35℃, 5% CO2, 1% O2, 94% N2) condition. The cells were incubated with molecular probes chloromethyl dichlorodihydrofluorescein diacetate (CM-H2DCF/DA) and RedoxSensor Red CC-1 to detect the ROS generation by laser scanning confocal microscopy. The mitochondria were isolated and mitochondrial inhibitors were used to detect the ROS generation functional unit sites by spectrophotometry under acute hypoxic condition. RESULTS:Under acute hypoxic condition, the intracellular ROS was significantly increased in hypoxia group with 3.35 folds higher of H2O2 than that in normoxia group. The contents of H2O2 and O-·2 in hypoxia group were 1.61 folds higher than those in normoxia group. Compare with hypoxia goup, pretreatment with the mitochondrial electron transport chain (ETC) complex I inhibitor MPP, the complex II inhibitors NPA and TTFA as well as the complex III pre-ubisemiquinone site inhibitor myxothiazol all remarkably reduced hypoxia-induced increase in ROS generation in PASMCs (reduced by 60%, 73%, 75% and 61%, respectively, P<0.01), whereas the complex III postubisemiquinone site inhibitor antimycin A and the complex IV inhibitor NaN3 had no effect on hypoxia-induced increase in ROS generation (increased by 13% and 9.1%, respectively, P>0.05). Direct detection of mitochondrial ROS showed the same results as the intracellular ROS. CONCLUSION: The intracellular ROS increases significantly in rat PASMCs under acute hypoxic condition. The mitochondrial ETC complex I, complex II and complex III pre-ubisemiquinone sites increase ROS generation, whereas the complex III postubisemiquinone site and complex IV do not produce this effect under acute hypoxic condition.     

水杨酸对根际低氧胁迫八棱海棠幼苗活性氧代谢的影响

 采用营养液水培系统,以苹果砧木八棱海棠(Malus robusta Rehd.)为试材,用叶面喷施的方法,研究了外源水杨酸(salicylic acid ,SA)对根际低氧胁迫下八棱海棠叶片活性氧(ROS)代谢的影响。结果表明：低氧胁迫下八棱海棠叶片丙二醛(MDA)、超氧阴离子 (O₂)、过氧化氢(H₂O₂)、谷胱甘肽(GSH)含量和抗氧化酶活性均高于对照,而抗坏血酸(AsA)含量低于对照;外源SA明显抑制MDA和O₂的积累,显著增强超氧化物歧化酶(SOD)、过氧化物酶(POD)、抗坏血酸过氧化物酶(APX)和谷胱甘肽还原酶(GR)的活性。说明SA作为化学诱抗剂,可抑制低氧胁迫下苹果幼苗体内活ROS的产生,提高抗氧化酶的活性,降低膜脂过氧化水平,从而减轻低氧胁迫对植株的伤害。     

Protective effect of hydrogen sulfide on hypoxia-induced injury of rat cortical neurons

AIM:To explore the role of hydrogen sulfide (H 2S) in cortial neuronal injury induced by hypoxia.METHODS:The SD rat cortical neurons were cultured in hypoxic conditions (2% O 2, 5% CO 2 and 93% N 2 at 37 °C) to establish the hypoxic model. Sodium hydrosulfide (NaHS) was used as the donor of H 2S and neuronal viability was detected by CCK-8 assay. Neuronal content of reactive oxygen species (ROS) was determined by DCFH-DA method, and mitochondrial membrane potential (MMP) was detected using Rh123 staining. Lactate dehydrogenase (LDH) release rate was measured by a commercial kit to reflect the degree of neuronal injury. RESULTS:Hypoxic treatment increased ROS content and the release rate of LDH in the neurons. However, NaHS pretreatment significantly inhibited the hypoxia-induced increases in ROS content and LDH release. Hypoxia decreased MMP and cell viability. Pretreatment with NaHS and N-acetyl-L-cysteine (NAC), a ROS scavenger, significantly inhibited the decreases in MMP and viability of the neurons. CONCLUSION:Hypoxia induces ROS generation in the neurons, thereby decreases MMP and neuronal viability. H 2S significantly attenuates hypoxia-induced neuronal injury by its antioxygenation.     

Critical role of cystic fibrosis transmembrane conductance regulator in hypoxia-induced apoptosis of H9c2 cardiomyocytes

AIM:To explore the roles of cystic fibrosis transmembrane conductance regulator (CFTR) in hypoxia-induced apoptosis of H9c2 cardiomyocytes and the underlying mechanisms. METHODS:The rat H9c2 cardiomyocytes were exposed to a 1% hypoxic environment in a hypoxic chamber. After CFTR overexpression, H9c2 cardiomyocytes were cultured in a hypoxic environment. The mRNA and protein levels of CFTR were examined by RT-qPCR and Western blot, respectively. The cell viability was measured by MTT assay. The apoptotic rate was determined by Hoechst 33342 and Annexin V-FITC/PI staining, and the production of reactive oxygen species (ROS) was examined by dichloro-dihydro-fluorescein diacetate (DCF-DA) staining. RESULTS:Hypoxic exposure caused the apoptosis of H9c2 cardiomyocytes, which was accompanied by the down-regulation of CFTR at mRNA and protein levels and over-production of ROS (P<0.05). After CFTR overexpression, the apoptotic rate of the H9c2 cardiomyocytes induced by hypoxia was significantly reduced, with a prominent inhibition of ROS production (P<0.05). However, pretreatment with CFTRinh-172, a specific inhibitor of CFTR, reversed the protective effect of CFTR overexpression in H9c2 cardiomyocytes. CONCLUSION:CFTR has a critical role in protecting against hypoxia-induced apoptosis of H9c2 cells, which may be through inhibiting the generation of ROS.     

Carnosine protects against high glucose-induced injury in H9c2 cells

AIM： To explore the protective effect of carnosine (Car) on cardiomyocytes with high glucose (HG)-induced injury. METHODS：Rat H9c2 cardiomyocytes were cultured in vitro and divided into three groups: normal control (NC) group, HG group and Car pretreatment (Car+HG) group. The survival rate of H9c2 cells was measured by MTT assay. Intracellular level of reactive oxygen species (ROS) was detected by fluorescent probe DCFH-DA. The protein expression of caspase-8, caspase-9 and caspase-3 was determined by Western blotting. RESULTS：The survival rate of H9c2 cells decreased with the increases in glucose concentration and time, while pretreatment with 20 mmol/L Car could increase the survival rate significantly (P<0.05). The intracellular level of ROS in HG group was significantly increased compared with NC group (P<0.05), while that in Car+HG group was significantly decreased compared with HG group (P<0.05). The expression of caspase-8, caspase-9 and caspase-3 proteins in HG group was significantly increased compared with NC group (P<0.05). Compared with HG group, the expression of caspase-9 and caspase-3 was significantly decreased in Car+HG group (P<0.05), but the expression of caspase-8 did not obviously change (P>0.05). CONCLUSION：Carnosine can protect H9c2 cells against the injury of oxidative stress and apoptosis induced by high glucose.     

N-acetylcysteine protects H9c2 cells against injuries induced by methyl-glyoxal

AIM: To investigate the protective effect of N-acetylcysteine(NAC) on H9c2 cells from injuries induced by methylglyoxal(MG) and the potential mechanism. METHODS: H9c2 cells were divided into control group, MG treatment group, NAC + MG treatment group, SP600125 pretreatment + MG group, NAC group and SP600125 group. The viability of the H9c2 cells was measured by CCK-8 assay. The protein levels of p-JNK and t-JNK were tested by Western blot. The changes of intracellular reactive oxygen species(ROS) were evaluated by 2', 7'-dichlorofluorescein diacetate(DCFH-DA) staining. Mitochondrial membrane potential(MMP) was measured by rhodamine 123(Rh123) staining. The morphological changes in apoptotic cardiomyocytes were detected by Hoechst 33258 staining. RESULTS: Du-ring 100~800μmol/L concentration range, MG caused significantly reduced viability of the H9c2 cells in a dose-dependent manner. NAC had a protective effect on H9c2 cells against the injuries induced by MG during 500~1500μmol/L concentration range through raising cell viability, inhibiting cellular oxidative stress and improving MMP(P<0.01). SP600125, an inhibitor of JNK, showed the protective effect similar to NAC on H9c2 cells against MG-induced injuries, including attenuating oxidative stress, improving MMP and suppressing apoptosis.CONCLUSION: N-acetylcysteine offers obvious protective effect on H9c2 cells against the injuries induced by methylglyoxal. The underlying mechanisms may be associated with decreasing the production of ROS, ameliorating MMP, inhibiting the activation of JNK and suppressing apoptosis.     

Inhibitory effect of acetylcholine on apoptosis of myocardial H9c2 cells induced by norepinephrine

AIM: To investigate the inhibitory effect of acetylcholine (ACh) on the apoptosis of myocardial H9c2 cells induced by norepinephrine (NE). METHODS: The apoptosis model of myocardial H9c2 cells was established by treating the cells with NE at different concentrations, and ACh was used to observed the protective effect. The cell viability was measured by MTT assay and the optimal doses of NE and ACh were selected. Four blockers related to different signaling pathways were also used. The apoptotic rate was analyzed by flow cytometry with Annexin V-FITC/PI staining. JC-1 staining was used to observe the changes of mitochondrial membrane potential of the H9c2 cells. DCFH-DA staining was used to observe intracellular reactive oxygen species (ROS) production. RESULTS: The viability of H9c2 cells was decreased by treatment with NE at 10 μmol/L. The membrane potential of mitochondria was decreased, while ROS production and apoptotic rate were increased significantly (P<0.05). Pretreatment with ACh at 10 mmol/L resulted in the increase in cell viability and decrease in the ROS production, and inhibited the loss of mitochondrial membrane potential and cell apoptosis (P<0.05). After treatment with the 4 signaling pathway blockers before ACh, the protective effect of ACh was significantly reduced only by PDTC. CONCLUSION: ACh inhibits the apoptosis of H9c2 cells induced by NE, and its mechanism may be related to NF-κB signaling pathway.     

Regulatory effects of reactive oxygen species on the production of PAI-1 in 3T3-L1 adipocytes and its related possible mechanisms

AIM: To investigate the regulatory effects of reactive oxygen species (ROS) on the production of plasminogen activator inhibitor 1 (PAI-1), and try to determine the signaling cascades involved in it. METHODS: 3T3-L1 cells were cultured and differentiated into mature adipocytes. Cell viability was measured by MTT. The PAI-1 mRNA expression levels were evaluated by quantitative real-time PCR. Quantification of the PAI-1 protein levels secreted into conditioned medium was performed by multiplex immunoassay and sandwich ELISA. The phosphorylation status of protein kinases was determined by Bio-Plex phosphoprotein assays. RESULTS: In 3T3-L1 adipocytes, H2O2 significantly augmented the expression of PAI-1. Also, H2O2 activated several signaling pathways including ERK1/2, JNK, Akt, p70 S6K and JAK/STAT. Verified by protein kinase inhibitors, Akt, JAK/STAT and ERK1/2 may participate in the H2O2-induced increase in PAI-1. CONCLUSION: H2O2 markedly up-regulates the production of PAI-1 in 3T3-L1 adipocytes via some intracellular signaling pathways such as Akt, JAK/STAT and ERK1/2.     

H_2O_2位于ABA的上游参与葡萄对低温的应答

以抗寒性较强的葡萄品种(砧木)贝达1 a生枝条叶片为材料,研究低温胁迫下贝达叶片中H2O2与ABA含量的变化及外源H2O2和抗坏血酸(AsA)对贝达叶片中ABA含量的影响。结果表明:低温胁迫下贝达叶片中H2O2与ABA含量先增加后降低,具有猝发现象,H2O2猝发时间早于ABA;外施一定浓度的H2O2可以促进贝达内源ABA的积累,缓解5℃低温对膜的伤害;而外施H2O2的清除剂AsA显著降低内源ABA的含量。表明H2O2与ABA参与了贝达对低温胁迫的应答,H2O2可能位于ABA的上游。