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首页> 外文期刊>Protoplasma: An International Journal of Cell Biology >Cyclosis-mediated transfer of H_2O_2 elicited by localized illumination of Chara cells and its relevance to the formation of pH bands
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Cyclosis-mediated transfer of H_2O_2 elicited by localized illumination of Chara cells and its relevance to the formation of pH bands

机译：Chara细胞的局部光照引起的环化介导的H_2O_2转移及其与pH带的形成有关

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Cytoplasmic streaming occurs in most plant cells and is vitally important for large cells as a means of longdistance intracellular transport of metabolites and messengers. In internodal cells of characean algae, cyclosis participates in formation of light-dependent patterns of surface pH and photosynthetic activity, but lateral transport of regulatory metabolites has not been visualized yet. Hydrogen peroxide, being a signaling molecule and a stress factor, is known to accumulate under excessive irradiance. This study was aimed to examine whether H_2O_2 produced in chloroplasts under high light conditions is released into streaming fluid and transported downstream by cytoplasmic flow. To this end, internodes of Chara corallina were loaded with the fluorogenic probe dihydrodichlorofluorescein diacetate and illuminated locally by a narrow light beam through a thin optic fiber. Fluorescence of dihydrodichlorofluorescein (DCF), produced upon oxidation of the probe by H_2O_2, was measured within and around the illuminated cell region. In cells exhibiting active streaming, H_2O_2 first accumulated in the illuminated region and then entered into the streaming cytoplasm, giving rise to the expansion of DCF fluorescence downstream of the illuminated area. Inhibition of cyclosis by cytochalasin B prevented the spreading of DCF fluorescence along the internode. The results suggest that H_2O_2 released from chloroplasts under high light is transported along the cell with the cytoplasmic flow. It is proposed that the shift of cytoplasmic redox poise and light-induced elevation of cytoplasmic pH facilitate the opening of H~+/OH~?-permeable channels in the plasma membrane.
机译：细胞质流发生在大多数植物细胞中，对于大细胞至关重要，这是代谢物和信使的长距离细胞内运输的一种手段。在查拉藻藻的节间细胞中，环化作用参与了表面pH和光合活性的光依赖性模式的形成，但尚未观察到调节代谢产物的横向转运。众所周知，过氧化氢是信号分子和应激因素，会在过度辐照下积聚。这项研究旨在检查在高光条件下叶绿体中产生的H_2O_2是否释放到流动液中并通过细胞质流向下游输送。为此，在Chara Corallina的节间装有荧光探针二氢二氯荧光素二乙酸盐，并通过细光束通过细光束局部照明。测量了被照射的细胞区域内和周围的H_2O_2氧化探针后产生的二氢二氯荧光素（DCF）的荧光。在表现出活跃流的细胞中，H_2O_2首先在被照亮的区域中积累，然后进入到被照流的细胞质中，导致DCF荧光在被照亮区域的下游扩展。细胞松弛素B抑制环化作用阻止了DCF荧光沿节间扩散。结果表明，高光下从叶绿体释放的H_2O_2与细胞质流一起沿细胞转运。有人提出，细胞质氧化还原平衡的改变和光诱导的细胞质pH的升高促进了质膜中H〜+ / OH〜β渗透通道的开放。

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