Fasting induces cyanide-resistant respiration and oxidative stress in the amoeba Chaos carolinensis:: implications for the cubic structural transition in mitochondrial membranes
Fasting induces cyanide-resistant respiration and oxidative stress in the amoeba Chaos carolinensis:: implications for the cubic structural transition in mitochondrial membranes
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DOI：
10.1007/s007090200017
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发表时间：
2002-01-01
期刊：
影响因子：
2.9
通讯作者：
Mannella, CA
中科院分区：
文献类型：
--
作者：
Deng, YR;Kohlwein, SD;Mannella, CA
大型自由生活的变形虫(Chaos Carolinens)可以在没有食物摄取的情况下在泉水中存活数周。饥饿与线粒体脊的巨大变化有关，从随机的管状形态转变为有序的(准晶体)立方形态。采用全细胞极谱技术监测空腹期间呼吸活动的变化。在饥饿过程中，单位细胞的基础呼吸逐渐下降，而抗氰化物的部分增加。荧光分光光度法检测细胞裂解产物中的过氧化氢和活性氧(ROS)(使用染料2‘，7’-二氯荧光素二乙酸酯)表明，饥饿的细胞中的过氧化氢和ROS的生成量高于被喂养的细胞。用相同的染料孵育的完整细胞的荧光显微镜显示，过氧化氢和ROS倾向于在液泡中积累。在饥饿的细胞中观察到在加入KCN后产生了显著的O-2，这可能是由于H_2O_2从这些隔室释放到细胞质中，在那里它可以与过氧化氢酶反应。在一起。这些观察表明，禁食增加了阿米巴体内的氧化应激，这种生物有几种保护机制来应对它，包括激活一种类似植物的替代氧化酶。提出的假说是线粒体内膜的立方结构转变代表了另一种保护机制，通过增加H_2O_2和ROS的外流来减少氧化损伤，并通过降低膜脂对氧化剂的敏感性来减少氧化损伤。
Large free-living amoeba (Chaos carolinensis) can survive in spring water without food intake for several weeks. Starvation is associated with a dramatic change in mitochondrial cristae from random tubular to ordered (paracrystalline) cubic morphology. Whole-cell polarography was used to monitor changes in respiratory activity during fasting. Basal respiration per cell decreased progressively during starvation, while the cyanide-resistant fraction increased. Spectrofluorometric assay of H2O2 and reactive oxygen species (ROS) in cell lysates (using the dye 2',7'-dichlorofluorescein diacetate) indicates greater H2O2 and ROS generation in starved than in fed cells. Fluorescence microscopy of intact cells incubated with the same dye demonstrates that H2O2 and ROS tend to accumulate in vacuoles. A remarkable generation of O-2 observed with starved cells after addition of KCN may be explained by release of H2O2 from these compartments into the cytosol, where it can react with catalase. Together. these observations suggest that fasting increases oxidative stress in the amoeba and that this organism has several protective mechanisms to deal with it, including activation of a plantlike alternative oxidase. The hypothesis is forwarded that the cubic structural transition of the mitochondrial inner membrane represents another protective mechanism, reducing oxidative damage by enhancing the efflux of H2O2 and ROS and by reducing the susceptibility of membrane lipids to the oxidants.