Elevated temperatures and ultraviolet radiation cause oxidative stress and inhibit photosynthesis in symbiotic dinoflagellates
Elevated temperatures and ultraviolet radiation cause oxidative stress and inhibit photosynthesis in symbiotic dinoflagellates
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DOI：
10.4319/lo.1996.41.2.0271
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发表时间：
1996-03-01
影响因子：
4.5
通讯作者：
Lesser, MP
中科院分区：
文献类型：
--
作者：
Lesser, MP
温度升高和太阳紫外线(UV)辐射被认为是珊瑚和其他具有光自养共生体的无脊椎动物失去共生藻类(即漂白)的原因。当百慕大共生线虫的培养物暴露在高温下时，细胞内超氧阴离子自由基和过氧化氢的浓度显著增加，同时有和没有紫外线辐射。这种氧化应激的增加伴随着光系统2荧光量子产率的下降和羧化酶Rubisco的蛋白质特异性活性的下降。在紫外线辐射和高温(31摄氏度)下，抗氧化酶活性的增加无法保护这些细胞免受氧化应激的影响。然而，外源活性氧清除剂的加入改善了虫黄藻的光合作用表现，但不能改善暴露在高温和紫外线辐射下的预暴露速率，证实了氧化胁迫在UV辐射和高温抑制光合作用中的作用。在UV辐射和温度升高下，290-375 nm之间的UV辐射对光合作用的抑制作用谱显著大于单独暴露于UV辐射下的Zoxanthele。
Elevated temperatures and solar ultraviolet (UV) radiation have been implicated as causes for the loss of symbiotic algae in corals and other invertebrates with photoautotrophic symbionts (i.e. bleaching). Significantly higher cellular concentrations of superoxide radicals and hydrogen peroxide are observed when cultures of Symbiodinium bermudense are exposed to elevated temperatures with and without exposure to UV radiation. This increase in oxidative stress is accompanied by a reduction in the quantum yield of fluorescence for photosystem 2 and protein-specific activities of the carboxylating enzyme, Rubisco. An increase in antioxidant enzyme activities is unable to protect these cells from oxidative stress during exposure to UV radiation and elevated temperatures (31 degrees C). The addition of exogenous scavengers of active oxygen, however, improves photosynthetic performance, but not to pre-exposure rates in zooxanthellae exposed to both elevated temperature and UV radiation, confirming a role for oxidative stress in the inhibition of photosynthesis by UV radiation and elevated temperatures. After exposure of zooxanthellae to UV radiation and elevated temperatures, an action spectrum for the inhibition of photosynthesis shows significantly greater wavelength-dependent effects of UV radiation between 290 and 375 nm than for zooxanthellae exposed to UV radiation alone.