顽拗性黄皮种子脱水过程中活性氧清除酶活性的变化

以正常性种子花生为对照,研究了顽拗性黄皮种子脱水过程中活性氧清除酶、膜脂过氧化作用以及电解质渗漏率的变化。随着含水量的下降,黄皮胚的电解质渗漏率和膜脂过氧化产物丙二醛(MDA)含量均显著增加;当黄皮胚含水量下降至40％后,SOD活性开始急剧下降,而POD和CAT活性在胚含水量下降过程中呈现出缓慢下降的趋势。花生胚在含水量从45％降至14％的过程中,电解质渗漏率没有明显增加,MDA含量只有少量增加;当含水量降至14％后,电解质渗漏率出现少量增加。花生胚脱水初期,活性氧清除酶活性明显增加,并在整个脱水过程中维持较高的水平。以上结果表明顽拗性种子黄皮的脱水敏感性与活性氧清除酶相对活性变化有关。脱水引起黄皮胚活性氧清除酶活性降低,活性氧清除能力下降,膜脂过氧化作用加强,膜透性增大。黄皮胚的膜系统可能是脱水伤害的靶位之一。     

顽拗性黄皮种子税水过程中活性氧清除酶活性的变化

以正常性种子花生为对照,研究了顽拗性黄皮种子脱水过程中活性氧清除酶、膜脂过氧化作用以及电解质渗漏率的变化。随着含水量的下降,黄皮胚的电解质渗漏率和膜脂过氧化产物丙二醛（MDA）含量均显著增加;当黄皮胚含水量下降致40％后,SOD活性开始急剧下降,而POD和CAT活性在胚含水量下降过程中呈现出缓慢下降的趋势。花生胚在含水量从45％降至145的过程中,电解质渗漏率没有明显增加,MDA含量只有少量增加;当含水量降至14％后,电解质渗漏率出现少量增加,花生胚脱水初期,活性氧清除酶活怀明显增加,并在整个脱水过程中维持较高的水平。以上结果表明：顽拗性处子黄皮的脱水敏感性与活性氧清除酶相对活性变化有关。脱水引起黄皮胚活性氧清除酶活性降低,活性氧清除能力下降,膜脂过氧化作用加强,膜透性增大。黄皮胚的膜系统可能是脱水伤害的靶位之一。     

氰化钾预处理对黄皮［Clausena lansium（Lour.） Skeels］种子脱水敏感性的影响

比较了ＫＣＮ 预处理与未处理黄皮种子在脱水后活力的变化,表明ＫＣＮ 预处理可有效降低黄皮种子脱水敏感性。电解质渗漏率分析表明,ＫＣＮ 预处理在一定程度上推迟了黄皮种子胚轴在脱水过程中的膜损伤。此外,ＫＣＮ 预处理显著抑制了黄皮胚轴在脱水初期的呼吸速率,在脱水过程中也维持在较低水平,但复水后该抑制很快消失, 在脱水６ ｄ 后的复水吸胀过程中呼吸速率恢复较对照为快,并维持在较高水平。呼吸途径分析表明,黄皮胚轴及其线粒体的呼吸以细胞色素途径为主。还分析了脱水对黄皮胚轴线粒体蛋白质及其氧化磷酸化水平的影响。     

甜高粱种子人工老化过程中活性氧清除酶活性的变化

研究甜高粱品种‘意达利’种子人工老化过程中种子活力与活性氧清除酶活性之间关系的结果表明：随着老化处理（100％RH,43℃）的时间进程,种子的萌发率、活力指数以及由存活种子形成的幼苗鲜重下降,相对渗漏率增加,丙二醛含量下降。超氧物歧化酶、抗坏血酸过氧化物酶、过氧化氢酶、谷胱甘肽还原酶和脱氢抗坏血酸还原酶的活性在人工老化初期增加,而后下降。据此认为活性氧清除酶活性下降可能是甜高粱种子活力丧失的原因之一。     

甜高梁种子人工老化过程中活性氧清除酶活性的变化

研究甜高粱品种'意达利'种子人工老化过程中种子活力与活性氧清除酶活性之间关系的结果表明:随着老化处理(100%RH,43℃)的时间进程,种子的萌发率、活力指数以及由存活种子形成的幼苗鲜重下降,相对渗漏率增加,丙二醛含量下降.超氧物歧化酶、抗坏血酸过氧化物酶、过氧化氢酶、谷胱甘肽还原酶和脱氢抗坏血酸还原酶的活性在人工老化初期增加,而后下降.据此认为活性氧清除酶活性下降可能是甜高粱种子活力丧失的原因之一.     

低氧训练对骨骼肌p53及其调控的线粒体有氧代谢信号通路基因表达的影响

目的:探讨低氧训练对大鼠骨骼肌p53及其调控的线粒体有氧代谢信号通路基因表达的影响,以及对线粒体有氧氧化供能能力的影响。方法:30只雄性Wistar大鼠随机分为3组(n=10),低住低练组(LoLo)、高住高练组(HiHi)和高住高练低训组(HiHiLo)。以当地海拔1 500 m为常氧环境,模拟海拔3 500 m为低氧环境,各组大鼠按训练方案训练5周后,取股四头肌行匀浆及提取线粒体。Real-time PCR检测p53、细胞色素c氧化酶合成2(SCO2),细胞色素c氧化酶亚基Ⅰ(COXⅠ)和谷氨酰胺酶2(GLS2) mRNA表达,Westem blot检测p53、SCO2、COXⅠ和GLS2蛋白表达;ELISA测定α-酮戊二酸脱氢酶(α-KGDHC),细胞色素c氧化酶(COX)及ATP合酶(ATP synthase)活性。结果:(1)与LoLo组比较,HiHi和HiHiLo组p53 mRNA水平显著升高(P<0.01),HiHiLo组p53蛋白表达水平显著下降(P<0.01);HiHi和HiHiLo组SCO2 mRNA水平和蛋白表达水平均显著升高(P<0.01);H...     

高温加速老化过程中甜菜种子线粒体小分 子量热激蛋白22的变化

甜菜(BetavulgarisLcv.Loke)种子的人工老化(30℃,100％RH)导致种子的干重、生活力和活力逐渐丧失,线粒体的呼吸速率、细胞色素c氧化酶和苹果酸脱氢酶的活性下降。线粒体蛋白质随着种子老化而显著变化,小分子量热休克蛋白(LMWHSP)22从老化的0d到30d增加,然后从30d到90d下降。可以认为甜菜种子人工老化过程中线粒体活性和LMWHSP22的含量变化与种子活力密切相关。     

NaHCO3处理对西伯利亚蓼叶细胞膜脂过氧化和活性氧清除酶活性的影响

对西伯利亚蓼扦插苗进行不同浓度和不同时间NaHCO₃处理;研究了NaHCO₃处理浓度和时间对西伯利亚蓼叶细胞膜脂过氧化和活性氧清除酶活性的影响。研究表明;NaHCO₃处理浓度分别与过氧化氢酶活性、丙二醛含量和细胞膜透性之间存在极显著正相关性;与超氧化物歧化酶活性之间存在显著正相关性;与过氧化物酶活性之间无显著相关性;不同NaHCO₃浓度处理间;超氧化物歧化酶活性、过氧化氢酶活性及丙二醛含量差异极显著;过氧化物酶活性和细胞膜相对透性差异显著;不同时间的NaHCO₃处理;过氧化物酶活性、过氧化氢酶活性、丙二醛含量及细胞膜透性差异显著;超氧化物歧化酶活性和过氧化氢酶活性差异极显著。     

NaHCO3处理对西伯利亚蓼叶细胞膜脂过氧化和活性氧清除酶活性的影响

对西伯利亚蓼扦插苗进行不同浓度和不同时间NaHCO₃处理,研究了NaHCO₃处理浓度和时间对西伯利亚蓼叶细胞膜脂过氧化和活性氧清除酶活性的影响。研究表明,NaHCO₃处理浓度分别与过氧化氢酶活性、丙二醛含量和细胞膜透性之间存在极显著正相关性,与超氧化物歧化酶活性之间存在显著正相关性,与过氧化物酶活性之间无显著相关性;不同NaHCO₃浓度处理间,超氧化物歧化酶活性、过氧化氢酶活性及丙二醛含量差异极显著,过氧化物酶活性和细胞膜相对透性差异显著;不同时间的NaHCO₃处理,过氧化物酶活性、过氧化氢酶活性、丙二醛含量及细胞膜透性差异显著,超氧化物歧化酶活性和过氧化氢酶活性差异极显著。     

KCl和NaCl对毕氏海蓬子生长和几种抗氧化酶活性的影响

50-200 mmol·L-1NaCl显著促进海蓬子生长和抗氧化酶[超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)]活性,与NaCl浓度相同的KCl明显抑制海蓬子生长和此3种酶的活性,但KCl下的超氧阴离子(O2-)和丙二醛(MDA)含量增加程度则明显高于同浓度的NaCI处理.据此认为,KCl伤害海蓬子的原因之一是抗氧化酶活性下降,不能及时清除活性氧,以致活性氧和MDA积累,引起质膜伤害,海蓬子生长受抑和生长量下降.     

The Response Difference of Mitochondria in Recalcitrant Antiaris toxicaria Axes and Orthodox Zea mays Embryos to Dehydration Injury

Long-term preservation of recalcitrant seeds is very difficult because the physiological basis on their desiccation sensitivity is poorly understood. Survival of Antiaris toxicaria axes rapidly decreased and that of immature maize embryos very slowly decreased with dehydration. To understand their different responses to dehydration, we examined the changes in mitochondria activity during dehydration. Although activities of cytochrome （Cyt） c oxidase and malate dehydrogenase of the A. toxicaria axis and maize embryo mitochondria decreased with dehydration, the parameters of maize embryo mitochondria were much higher than those of A. toxicaria, showing that the damage was more severe for the A. toxicaria axis mitochondria than for those of maize embryo. The state I and III respiration of the A. toxicaria axis mitochondria were higher than those of maize embryo, the former rapidly decreased, and the latter slowly decreased with dehydration. The proportion of Cyt c pathway to state III respiration for the A. toxicaria axis mitochondria was low and rapidly decreased with dehydration, and the proportion of alternative oxidase pathway was high and slightly increased with dehydration. In contrast, the proportion of Cyt c pathway for maize embryo mitochondria was high, and that of alternative oxidase pathway was low. Both pathways decreased slowly with dehydration.     

Reactive Oxygen Species Scavenging Enzymes and Down-Adjustment of Metabolism Level in Mitochondria Associated with Desiccation-Tolerance Acquisition of Maize Embryo

It is a well-known fact that a mature seed can survive losing most of its water, yet how seeds acquire desiccation- tolerance is not well understood. Through sampling maize embryos of different developmental stages and comparatively studying the integrity, oxygen consumption rate and activities of antioxidant enzymes in the mitochondria, the main origin site of reactive oxygen species （ROS） production in seed cells, we found that before an embryo achieves desiccation-tolerance, its mitochondria shows a more active metabolism, and might produce more ROS and therefore need a more effective ROS scavenging system. However, embryo dehydration in this developmental stage declined the activities of most main antioxidant enzymes and accumulated thiobarbituric acid-reactive products in mitochondria, and then destroyed the structure and functional integrity of mitochondria. In physiologically-matured embryos （dehydration- tolerant）, mitochondria showed lower metabolism levels, and no decline in ROS scavenging enzyme activities and less accumulation of thiobarbituric acid-reactive products after embryo dehydration. These data indicate that seed desiccation- tolerance acquisition might be associated with down-adjustment of the metabolism level in the late development stage, resulting in less ROS production, and ROS scavenging enzymes becoming desiccation-tolerant and then ensuring the structure and functional integrity of mitochondria.     

12/15-Lipoxygenase targets neuronal mitochondria under oxidative stress

12/15-Lipoxygenase (12/15-LOX) is an important mediator of brain injury following experimental stroke in rodents. It contributes to neuronal death, but the underlying mechanism remains unclear. We demonstrate here that in neuronal HT22 cells subjected to glutamate-induced oxidative stress, 12/15-LOX damages mitochondria, and this represents the committed step that condemns the cell to die. Importantly these events, including breakdown of the mitochondrial membrane potential, the production of reactive oxygen species, and cytochrome c release, can all be replicated by incubation of 12/15-LOX with mitochondria in vitro , without the need to add other cytosolic factors. Proteasome activity is required downstream of mitochondrial damage to complete the cell death cascade, but proteasome inhibition is only partially protective. These findings position 12/15-LOX as the central executioner in an oxidative stress-related neuronal death program.     

脱水速率对黄皮胚轴脱水敏感性及膜脂过氧化的影响

以黄皮种子离体胚轴为材料,研究了不同干燥速率对胚轴脱水反应和膜脂过氧化的影响.在脱水过程中,胚轴的萌发率、活力指数、电解质渗漏速率,超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性逐渐降低,膜脂过氧化产物MDA的含量不断增加.脱水速率愈快,胚轴的半致死含水量就愈低.快速干燥的胚轴能在较低的含水量下存活是因为缩短了在中间含水量下发生的膜脂过氧化作用的时间,以及保持较高的SOD、POD和CAT活性;缓慢干燥的胚轴当与周围环境达到水分平衡后,生活力的丧失将与保持在水分平衡后的时间有关.因此,脱水速率是一种影响顽拗性种子或者胚轴脱水敏感性的重要因子.