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首页> 外文期刊>Marine biology >UV- and salinity-induced oxidative effects in the marine diatom Cylindrotheca closterium during simulated emersion
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UV- and salinity-induced oxidative effects in the marine diatom Cylindrotheca closterium during simulated emersion

机译：紫外线和盐度诱导的海洋生物硅藻圆柱藻在氧化过程中的氧化作用

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摘要

The diatom Cylindrotheca closterium was exposed to transient light- and osmotic conditions as occur during its tidal emersion. The objective was to analyze how this simulated emersion contributes to the production of active oxygen species (AOS) and via this, to oxidative cell damage. Light- and salinity conditions were varied in factorial combination: low light (no UVB) or high light (unweighted UVB-dose rates of respectively 0.01; 0.07; 0.24; 1.03 W m~(-2)) at normal (30 psu) or high salinity (60 psu). UVB (0.01-0.24 W m~(-2)) and high salinity had a significant, negative effect on the photosynthetic efficiencies ΔF/F_m' (steady-state quantum yield) and F_v/F_m (maximum yield). UVB at 1.03 W m~(-2) (15 kJ m~(-2) d~(-1)) almost arrested electron transport. At ecologically relevant UVB levels, i.e. below 0.24 W m~(-2) ( ≈ 3.4 kJ m~(-2) d~(-1)) with UVB:PAR < 0.4:100 (PAR photosynthetically active radiation) only dynamic photoinhibition was observed (protection via heat dissipation). Non-photochemical quenching was positively correlated with the de-epoxidation of diadinoxanthin (DD) to diatox-anthin (DT). A decreasing ratio DT/(DD + DT) after 4 h of UVB at > 0.07 W m~(-2) and at 60 psu indicated a reversal of the diatom xanthophyll cycle (diminished photoprotection) which may be caused by an enhanced AOS production. Oxidative stress and -damage to C. closterium cells were assessed applying fluorescent indicator dyes, via confocal microscopy and quantitative image analysis. AOS production rates (cellular DCF fluorescence) were stimulated by UV, and were ～50% higher at 60 psu. AOS production decreased with an increasing pre-exposure (0-4 h) to normal UVB (0.24 W m~(-2)), which indicated a stimulation of the antioxidative defence. Non-protein thiols (indicator CMF) and glutathione pools (HPLC-analyzed) decreased with UVB-dose rates (0.01-0.24 W m~(-2)), most likely due to AOS-mediated thiol oxidation. Hypersa-linity (60 psu) and UVB (0.01-0.24 W m~(-2)) caused membrane depolarization (dye DIBAC_4(3)) and phos-pholipid hydrolysis (phospholipase A_2 dye: bis-BO-DIPY FL-C_(11)PC). AOS production may have diminished the membrane polarity, and peroxidized the membrane lipids (HPLC-analyzed malondialdehyde) which enhanced PLA_2 activity. The dyes indicated an increased oxidative (lipid) damage at a 15% inhibition of photosynthesis in this diatom, at UVB levels and salinities that can be expected in situ during its periodic tidal emersion.
机译：硅藻Cylindrotheca closterium在潮汐出现期间曾暴露于短暂的光和渗透条件下。目的是分析这种模拟的分泌物如何促进活性氧（AOS）的产生，并由此促进氧化性细胞损伤。光照和盐度条件在因子组合中有所不同：在正常（30 psu）或低光照（无UVB）或高光照（未加权的UVB剂量比率分别为0.01; 0.07; 0.24; 1.03 W m〜（-2））或高盐度（60 psu）。 UVB（0.01-0.24 W m〜（-2））和高盐度对光合效率ΔF/ F_m'（稳态量子产率）和F_v / F_m（最大产量）具有显着的负面影响。在1.03 W m〜（-2）（15 kJ m〜（-2）d〜（-1））的UVB几乎阻止了电子传输。在生态相关的UVB水平下，即低于0.24 W m〜（-2）（≈3.4 kJ m〜（-2）d〜（-1））且UVB：PAR <0.4：100（PAR光合有效辐射）时，仅动态光抑制观察到（通过散热保护）。非光化学淬灭与二恶英黄嘌呤（DD）还原为重氮杂蒽醌（DT）呈正相关。 UVB在> 0.07 W m〜（-2）和60 psu下4 h后DT /（DD + DT）的比率降低表明硅藻叶黄素循环的逆转（光保护减弱），这可能是由于AOS产量增加所致。通过共聚焦显微镜和定量图像分析，使用荧光指示剂染料评估氧化应激和对梭状芽胞杆菌细胞的损害。 UV刺激了AOS的产生速率（细胞DCF荧光），在60 psu时提高了约50％。随着预暴露时间（0-4 h）的增加，AOS的产量下降至正常UVB（0.24 W m〜（-2）），这表明抗氧化防御能力得到了增强。非蛋白硫醇（指标CMF）和谷胱甘肽库（HPLC分析）随UVB剂量率（0.01-0.24 W m〜（-2））降低，最可能是由于AOS介导的硫醇氧化。高盐度（60 psu）和UVB（0.01-0.24 W m〜（-2））引起膜去极化（染料DIBAC_4（3））和磷脂水解（磷脂酶A_2染料：bis-BO-DIPY FL-C_（ 11）PC）。 AOS的产生可能降低了膜的极性，并过氧化了膜脂质（HPLC分析的丙二醛），从而增强了PLA_2的活性。这些染料表明，在该硅藻的光合作用受到15％抑制的同时，UVB水平和盐度可能会在其周期性潮汐出现期间原位预期，从而增加了氧化（脂质）损害。

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  • 来源
    《Marine biology》 |2005年第5期|p.1063-1073|共11页
  • 作者

    J. W. Rijstenbil;

  • 作者单位

    Netherlands Institute of Ecology (NIOO-KNAW), Centre for Estuarine and Marine Ecology, Korringaweg 7, 4401 NT, Yerseke, The Netherlands;

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  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 环境生物学;
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