Role of dimethylsulfoniopropionate as an osmoprotectant following gradual salinity shifts in the sea-ice diatom Fragilariopsis cylindrus
Role of dimethylsulfoniopropionate as an osmoprotectant following gradual salinity shifts in the sea-ice diatom Fragilariopsis cylindrus
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DOI：
10.1071/en14269
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发表时间：
2016-01-01
影响因子：
4.3
通讯作者：
DiTullio, Giacomo R.
中科院分区：
文献类型：
--
作者：
Lyon, Barbara R.;Bennett-Mintz, Jennifer M.;DiTullio, Giacomo R.
环境背景二甲基磺酰基丙酸酯（DMSP）是一种由藻类生物合成的小硫化合物，在全球气候中发挥着重要作用，特别是在极地地区。我们研究了盐度对 DMSP 水平的影响，并首次提供了 DMSP 的实验测量结果以及极地硅藻在一系列代表海冰条件的逐渐盐度变化范围内的相关生理变化。盐度变化后极地硅藻中 DMSP 的定量估计将有助于建立新的数学模型来预测季节性响应和对气候变化的反应。 摘要 尽管已提出海冰内的极端环境梯度可以刺激硅藻中二甲基磺酰基丙酸盐（DMSP）的积累，而硅藻是温带对应物浓度相对较低的分类群，但这尚未在代表海冰条件的一系列盐度范围内进行实验验证。本研究考察了广泛分布的极地硅藻 Fragilariopsis cylindrus 中 DMSP 浓度的变化，以响应逐渐盐度变化（代表海冰形成和融化过程中遇到的盐度变化）。在 70 盐度培养物中，DMSP 浓度升高至 127%。低盐度变化以梯度依赖性方式降低细胞内 DMSP 浓度，这表明在较温和的低盐度变化下 DMSP 循环而不是释放。在 10 盐度细胞中检测到的渗透膜与 45% 相似；因此，膜完整性的丧失可能只能部分解释最低盐度组中 DMSP 的释放。生长速率、光系统 II 的光合效率和活性氧检测表明该生物体仅受到盐度胁迫的部分损害。因此，实验证据支持 DMSP 作为兼容溶质在海冰硅藻适应大盐度梯度过程中的作用，并且相关生理变化的测量将改善对环境测量的解释。
Environmental context Dimethylsulfoniopropionate (DMSP), a small sulfur compound biosynthesised by algae, plays an important role in global climate, particularly in polar regions. We investigated salinity effects on DMSP levels, and provide the first experimental measurements of DMSP and associated physiological changes in a polar diatom across to a range of gradual salinity shifts representative of sea-ice conditions. Quantitative estimates of DMSP in polar diatoms following salinity changes will facilitate new mathematical models to predict seasonal responses and reactions to climate change.Abstract Although extreme environmental gradients within sea-ice have been proposed to stimulate dimethylsulfoniopropionate (DMSP) accumulation in diatoms, a taxa whose temperate counterparts show relatively low concentrations, this has yet to be experimentally validated across a range of salinities representative of sea-ice conditions. The present study examined changes in DMSP concentrations in the widespread polar diatom Fragilariopsis cylindrus in response to gradual salinity shifts representative of those encountered during sea-ice formation and melt. DMSP concentrations were elevated up to 127% in 70-salinity cultures. Low-salinity shifts decreased intracellular DMSP concentrations in a gradient-dependent manner that suggests DMSP recycling rather than release under milder hyposalinity shifts. Permeable membranes were detected in similar to 45% of 10-salinity cells; therefore, loss of membrane integrity may only partially explain DMSP release in the lowest-salinity group. Growth rates, photosynthetic efficiency of photosystem II and reactive oxygen species detection indicated only partial impairment by salinity stress in this organism. Thus, experimental evidence supports the role of DMSP as a compatible solute in the acclimation of a sea-ice diatom across large salinity gradients and measurements of associated physiological changes will improve interpretation of environmental measurements.