Heat stress stimulates nitric oxide production in Symbiodinium microadriaticum:: A possible linkage between nitric oxide and the coral bleaching phenomenon
Heat stress stimulates nitric oxide production in Symbiodinium microadriaticum:: A possible linkage between nitric oxide and the coral bleaching phenomenon
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DOI：
10.1093/pcp/pcn037
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发表时间：
2008-04-01
影响因子：
4.9
通讯作者：
Yamasaki, Hideo
中科院分区：
文献类型：
--
作者：
Bouchard, Josee Nina;Yamasaki, Hideo
一氧化氮（NO）是一种在植物、动物和细菌中发挥多种生理功能的气体。硝酸还原酶和NO合酶被认为参与了植物和藻类中NO的产生，但这些酶在生理条件下NO产生中的意义仍然不清楚。共生藻（英语：Symbiodinium microadriaticum）是一种海洋微生物，通常与刺胞动物（包括造礁珊瑚）共生。在这里，我们证明了NO生产zooxanthropium补充亚硝酸钠或L-精氨酸作为底物。电化学检测了亚硝酸盐依赖的NO产生，并通过应用特异性NO清除剂2-（4-羧基苯基）-4，4，5，5-四甲基咪唑啉-1-氧基-3-氧化物（cPTIO）来证实。用二氨基荧光素（一种NO荧光探针）染色的细胞显示，在补充亚硝酸钠和L-精氨酸后，荧光强度增加。DAF染色细胞的显微镜观察证实，NO在细胞内产生。在S.发现当细胞暴露于急性热胁迫时，微干旱增加，这也导致PSII的光合效率（F-v/F-m）下降。这项研究提供了大量的证据，以证实，虫黄藻可以合成NO，即使它们不是在一个共生协会与珊瑚主机。在高温下NO产量的增加表明，热应激刺激微藻NO产量的温度依赖性的方式。这些研究结果的影响进行了讨论，在光的珊瑚漂白现象，这是与升高的海面温度，由于全球变暖。
Nitric oxide (NO) is a gas displaying multiple physiological functions in plants, animals and bacteria. The enzymes nitrate reductase and NO synthase have been suggested to be involved in the production of NO in plants and algae, but the implication of those enzymes in NO production under physiological conditions remains obscure. Symbiodinium microadriaticum, commonly referred to as zooxanthellae, is a marine microalga commonly found in symbiotic association with a cnidarian host including reef-building corals. Here we demonstrate NO production in zooxanthellae upon supplementation of either sodium nitrite or L-arginine as a substrate. The nitrite-dependent NO production was detected electrochemically and confirmed by the application of 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO), a specific NO scavenger. Cells stained with the diaminofluorescein, DAF-2 DA, an NO fluorescent probe, showed an increase in fluorescence intensity upon supplementation of both sodium nitrite and L-arginine. Microscopic observations of DAF-stained cells verified that NO was produced inside the cells. NO production in S. microadriaticum was found to increase upon exposure of cells to an acute heat stress which also caused a decline in the photosynthetic efficiency of PSII (F-v/F-m). This study provides substantial evidence to confirm that zooxanthellae can synthesize NO even when they are not in a symbiotic association with a coral host. The increase in NO production at high temperatures suggests that heat stress stimulates the microalgal NO production in a temperature-dependent manner. The implications of these findings are discussed in the light of the coral bleaching phenomenon which is associated with elevated sea surface temperature due to global warming.