钙对玉米幼苗热激诱导抗盐性的影响

热激处理的玉米幼苗抗盐性提高,盐胁迫期间的谷胱甘肽还原酶(GR)活性和脯氨酸含量也较高.Ca2 处理可增强热激诱导的玉米幼苗抗盐性,GR活性和脯氨酸含量也进一步提高;Ca2 螯合剂EGTA处理的效果正好相反.     

抗氧化系统在热激诱导的玉米幼苗耐热性形成中的作用

玉米幼苗经过42℃热激4h并恢复4h后,显著提高了玉米幼苗在高温处理下的存活率。热激并恢复4h后,不同程度地提高了抗氧化酶系统过氧化氢酶(CAT),超氧化物歧化酶(SOD),谷胱甘肽还原酶(GR),抗坏血酸过氧化物酶(APX)和过氧化物酶(GPX)的活性以及抗氧化剂还原型抗坏血酸(ASA)和谷胱甘肽(GSH)的含量,且经过热激的玉米幼苗在高温处理期间及其后的恢复过程中均能保持相对较高的抗氧化酶活性和抗氧化剂水平,说明保持较高的抗氧化酶活性和抗氧化剂水平是热激诱导的玉米幼苗耐热性形成的生理基础之一。     

钙对玉米幼苗谷胱甘肽还原酶活性的影响

CaCl2浸种或酶提取液中加入CaCl2均可显著提高两品种玉米幼苗中谷胱甘肽还原酶（GR）活性,且不同钙盐对GR的激活效应基本相同。Ca^2 专一螯合剂EGTA浸种或加入到酶提取液中则可显著抑制GR活性,表明GR活性至少部分受Ca^2 调控。     

氯化钙浸种对玉米幼苗抗逆性的影响及其与谷胱甘肽还原酶的关系

两个抗逆性不同的玉米品种经过CaCl2 浸种处理后 ,能显著提高其幼苗在低温、高温、干旱和盐胁迫下的存活率 ;相反 ,Ca2 螯合剂EGTA浸种处理会降低玉米幼苗在上述逆境胁迫下的存活率 ,表明外源Ca2 处理能增强玉米幼苗对低温、高温、干旱和盐胁迫的多重抗逆性。此外 ,Ca2 浸种处理能使玉米幼苗在多种逆境胁迫下保持相对较高的谷胱甘肽还原酶 (GR)活性 ,而EGTA处理正好相反 ,表明GR可能参与了Ca2 提高的玉米幼苗多重抗逆性的调控     

热激诱导的玉米幼苗耐热性及其与脯氨酸的关系

研究了热激对玉米幼苗耐热性的效应及其与脯氨酸的关系。结果表明,培养2.5 d的玉米幼苗经过42℃热激4 h并于26.5℃下恢复4 h后,提高了玉米幼苗在48℃下的存活率,并且热激及其后的恢复过程中都表现出脯氨酸的积累。不同浓度的外源脯氨酸预处理也可提高玉米幼苗内源脯氨酸的水平和抗氧化酶抗坏血酸过氧化物酶(APX)、过氧化氢酶(CAT)、超氧化物歧化酶(SOD)、谷胱甘肽还原酶(GR)、过氧化物酶(GPX)的活性,从而提高玉米幼苗在高温胁迫下的存活率。这些结果暗示热激过程中脯氨酸的积累所诱发的抗氧化酶活性的增强可能是热激诱导的玉米幼苗耐热性形成的生理基础之一。     

高等植物热激转录因子生物学特性及其在非生物胁迫适应中的作用

热激转录因子(HSFs)参与了植物生长发育的调控以及多种非生物胁迫适应基因的表达调控。HSFs通常形成同源三聚体,激活转录活性从而发挥功能。本文综述了热激转录因子的基本结构、亚细胞定位、转录调控、功能多样性及其在植物适应极端温度、盐害、干旱、强光和氧化胁迫等非生物胁迫过程中的作用。HSFs是提高高等植物抗多重胁迫的优质候选基因,对其深入研究具有重要的应用价值。未来,通过生物基因工程等手段利用HSFs提高各类作物抗性具有广阔的发展前景。     

涝渍逆境下玉米叶片中谷胱甘肽的含量变化及其作用

涝渍逆境下玉米叶片ＧＳＨ含量和ＧＳＨ还原酶活性都明显下降,但前者的降幅小于后者,两者的变化均与叶片质膜透性以及ＭＤＡ的积累呈显著性负相关。施加外源ＧＳＨ明显减少ＭＤＡ和Ｈ２Ｏ２含量,降低Ｏ＾－２产生速率。而叶面喷施８－羟基喹啉和抗坏血酸等活性氧清除剂则减缓因涝渍而引起的ＧＳＨ含量下降。     

热激对水稻幼苗耐冷性及热激蛋白合成的诱导

萌发的水稻种子经42℃热激处理后其幼苗的耐冷性明显增强,膜伤害程度降低,脯氨酸含量增加,超氧物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)活性和抗氧化物质抗坏血酸含量增加,而膜脂过氧化的关键酶脂氧合酶(LOX)活性及其产物丙二醛(MDA)含量下降.并且热激诱导萌发的水稻胚合成78、70、64、60、46、38、24、17、16kD的热激蛋白(HSP),其中属于HSP70的内质网结合蛋白(BiP)的合成与水稻幼苗耐寒性的提高有关.     

玉米胚发育过程中热激蛋白的合成

35S-Met标记玉米胚蛋白合成结果表明,热激处理(42℃)与对照(25℃)的蛋白合成趋势相近,热激抑制16 DAP的蛋白合成,增加22和34 DAP蛋白合成.SDS-PAGE自显影图谱表明,热激诱导16DAP的胚合成86.4、80.0、73.2 kD等3种分子量较高的热激蛋白,22DAP后热激诱导合成86.4、80.0、73.2、24.4、18.2、16.8和13.6 kD等7种分子量的热激蛋白.2D-PAGE自显影图谱进一步显示,热激诱导22和28 DAP的胚合成近20种热激蛋白,其中超过10种为小分子热激蛋白.特异热激蛋白BiP(HsP70)、PDI(HsP60)Western blot表明,这2种热激蛋白在玉米胚发育过程均有高水平的表达,热激对其合成影响不明显.     

喜树幼苗中喜树碱和10-羟基喜树碱对热激的响应特点和意义

植物在长期的生态环境适应过程中,产生了包括生物碱在内的大量次生代谢物。本文以我国特有树种——喜树(Camptotheca acuminata Decaisne)为材料,研究其不同器官中喜树碱(camptothecin,CPT)和10-羟基喜树碱(10-hydroxycamptothecin,HCPT)在不同热激温度和时间情况下的含量变化。CPT和HCPT变化呈现出较好的相互消长关系,并且分别在38℃和40℃达到各自的峰值,比以丙二醛和叶绿素为指标的致死温度低了2-4℃：HCPT在热激过程中的变化较CPT活跃;极易受到攻击和伤害的嫩叶中的生物碱含量变化最大。由此推断,CPT和HCPT遵循“幼嫩和生殖器官优先保护”的原则,从而有效地缓解了高温胁迫,并且HCPT和CPT代表了不同的防御策略。     

照光对玉米黄化幼苗超氧物歧化酶活性的影响

玉米黄化苗经光照（80μmolm－2s－1）后超氧物歧化酶（SOD）活性提高,放线菌酮抑制光下SOD活性的提高。照光能提高玉米幼苗O-2产生速率;百草枯（0．01mmol／L）可提高照光和黑暗条件下SOD活性,抗坏血酸和甘露醇却消除光对SOD的激活作用。     

外源超氧化物歧化酶基因MnSOD在玉米中的过量表达及抗逆性的提高

为研究过量表达的超氧化物歧化酶基因MnSOD对玉米抗逆性的作用,构建了小麦来源MnSOD基因的单子叶植物高效表达载体,用基因枪法转化优良玉米自交系胚性愈伤组织。经潮霉素梯度浓度培养基筛选,从阳性愈伤组织再生获得9个正常结实的植株。其中5株经PCR和Southern印迹检测表现为阳性,表明外源基因己整合到玉米基因组中。提取SOD酶液,非变性聚肉烯酰胺浓度梯度凝胶电泳分离,用H2O2 5mmol／L抑制FeSOD和CU／ZnSOD活性,氯化硝基四氮唑蓝染色检测MnSOD酶活性。Southern印迹呈阳性的5个植株,MnSOD酶活性均高于未转基因的对照。甲基紫精氧化损伤处理后,用电解质渗漏率法测定阳性株系的叶片渗透液的电导率。结果表明,转基因株系的抗氧化损伤能力显著高于对照。     

植物超氧化物歧化酶（SOD）的研究进展

超氧化物歧化酶(superoxide dismutase,SOD)在需氧原核生物和真核生物中广泛存在,是活性氧清除系统中第一个发挥作用的抗氧化酶。植物正常代谢过程和在各种环境胁迫下均能产生活性氧和自由基,活性氧和自由基的积累引起细胞结构和功能的破坏。SOD岐化超氧物阴离子自由基生成过氧化氢和分子氧,在保护细胞免受氧化损伤过程中具有十分重要的作用。本文综述了SOD的功能、在细胞中的分布、表达调控和与植物抗逆性的关系。 Abstract:Superoxide Dismutases (SODs) are ubiquitously expressed antioxidant enzyme in aerobic organisms and catalyze dismutation of superoxide anion to hydrogen and molecular oxygen,the first step in active oxygen-scavenging systems.SODs play a central role in protecting cells against the toxic effects of reactive oxygen species generated during normal cellular metabolic activity or as a result of various environmental stresses.This paper reviews the expression and regulation of Sod genes and their functional role(s) during development and in response to stresses.     

几种外源因子对大豆幼苗SOD活性的影响

高氧能促使大豆幼苗细胞内产生O_2~+速率增加,同时又使幼苗内SOD活性水平提高,以减轻O_2~+增加所引起的细胞伤害。高氧诱发O_2~+同时发生在叶绿体、线粒体和细胞溶质中,与细胞呼吸水平无明显相关。棓酸丙酯有清除体内O_2~+的能力,当浓度在1μmol/L时,能减轻大豆幼苗的氧伤害。相反,DDC是SOD的有效抑制剂,当它的浓度大于5 mmol/L时,显著抑制大豆幼苗SOD活性,增加了体内O_2~+的积累,影响了幼苗的正常生长以及幼苗氧伤害的加剧。     

铜、锌对水稻幼苗生长及超氧物歧化酶的影响

用缺Cu或Zn,与缺Cu、Zn的木村B营养溶液培养杂交水稻威优48(V_(48)),威优49(V_(49))与常规稻竹系26(ZX_(26))幼苗至七叶期。缺Cu的稻苗,上部新生叶(六、七叶)先端扭曲,叶尖枯黄。缺Zn与缺Cu、Zn的稻苗,六、七叶脉间全部褪绿,植株矮小,根系衰退。凡是缺素培养的稻苗,根与叶的超氧物歧化酶(SOD)活性均显著减弱,叶绿体基粒与间质片层明显减少,缺Cu、Zn的叶绿体还出现较大的淀粉“液泡”。经凝胶电泳,显示出水稻SOD有4组活性带,缺Cu或Zn与缺Cu、Zn使迁移率较高的3组活性带的活性明显减弱。     

磷脂化修饰影响超氧化物歧化酶细胞亲和力的研究

目的:研究磷脂化修饰对重组人超氧化物歧化酶(SOD)进入人冠状动脉内皮细胞(HCAEC)、人心肌细胞(HCM)能力的影响。方法:分别运用流式细胞术和蛋白印迹分析磷脂化修饰的超氧化物歧化酶(PC-SOD)和SOD与HCAEC、HCM的结合能力,并用激光共聚焦显微术分析修饰前后的SOD可显著增强PC-SOD与细胞的亲和力,并可显著增强PC-SOD进入人冠状动脉内皮细胞和人心肌细胞的能力。     

Doxorubicin Resistance Conferred by Selective Enhancement of Intracellular Glutathione Peroxidase or Superoxide Dismutase Content in Human MCF-7 Breast Cancer Cells

To examine the role of doxorubicin-stimulated oxyradical formation in tumor cell killing, we introduced glutathione peroxidase (GSH Px) or superoxide dismutase (SOD) into MCF-7 cells by “scrape loading.” Control cytoplasmic GSH Px and SOD levels increased from (mean ± S.E.) 0.37nmol/min/mg and 0.58 μg SOD/mg, respectively, to 3.99 or 7.63 nmol/min/mg and 1.40 or 1.83 μg SOD/mg after treatment with either 150 or 300 units/ml of GSH Px or 20 or 40mg/ml SOD. Resistance to doxorubicin was cbrrelated with the level of GSH Px introduced into the MCF-7 cells: a one-hour exposure to 1.75 μM doxorubicin decreased the cloning efficiency of control cells loaded with medium alone to 34%, whereas doxorubicin-treated cells augmented with 150 or 300 units/ml of GSH Px had plating efficiencies of 56 or 86%, P < 0.05. Introduction of SOD increased MCF-7 resistance to doxorubicin similarly. The heat-inactivated enzymes were not protective. Cells loaded with GSH Px were also resistant to the redox cycling anticancer quinone mitomycin C but not to the redox inactive analogs 5-iminodaunorubicin and mitoxan-trone. suggesting that amplification of GSH Px or SOD levels can produce doxorubicin resistance in MCF-7 cells.     

From Haemocuprein to Copper-Zinc Superoxide Dismutase: A History on the Fiftieth Anniversary of the Discovery of Haemocuprein and the Twentieth Anniversary of the Discovery of Superoxide Dismutase

Haemocuprein was discovered fifty years ago by T. Mann and D. Keilin as a copper protein of red blood cells, later named erythrocuprein. Superoxide dismutase was discovered twenty years ago by J.M. McCord and I. Fridovich as an enzymatic activity in preparations of carbonic anhydrase or myoglobin that inhibited the aerobic reduction of cytochrome c by xanthine oxidase. Astonishingly the superoxide dismutase proved to be haemocuprein. Around this time zinc was found in haemocuprein, in equimolar amount to the copper. Haemocuprein thus became copper-zinc superoxide dismutase after thirty years as an obscure cupropro-tein of red blood cells. This historical article is a tribute to the achievement of J.M. McCord and I. Fridovich. Their discovery of superoxide dismutase revolutionized the study of oxygen free-radicals in biochemistry.     

Catalase and Superoxide Dismutase in the Cells of Strictly Anaerobic Microorganisms

Strictly anaerobic microorganisms relating to various physiological groups were screened for catalase and superoxide dismutase (SOD) activity. All of the investigated anaerobes possessed SOD activity, necessary for protection against toxic products of oxygen reduction. High specific activities of SOD were found in Acetobacterium woodii and Acetobacterium wieringae. Most of the investigated clostridia and acetogens were catalase-negative. A significant activity of catalase was found in Thermohydrogenium kirishiense, in representatives of the genus Desulfotomaculum, and in several methanogens. Methanobrevibacter arboriphilus had an exceptionally high catalase activity after growth in medium supplemented with hemin. Hemin also produced a strong positive effect on the catalase activity in many other anaerobic microorganisms. In methanogens, the activities of the enzymes of antioxidant defense varied in wide ranges depending on the stage of growth and the energy source.