Distribution and sources of cyclic pheophorbides in the marine environment
Distribution and sources of cyclic pheophorbides in the marine environment
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海洋环境中环状脱镁叶绿酸的分布及来源
DOI：
10.4319/lo.2000.45.1.0200
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发表时间：
2000
影响因子：
4.5
通讯作者：
M. A. Bell
中科院分区：
文献类型：
--
作者：
R. Goericke;S. Strom;M. A. Bell
不稳定的叶绿素a（Chl a1）降解产物，132，173-环脱镁叶绿酸a烯醇（CPP 516），最近才在海洋沉积物中发现，它可以贡献溶剂可提取的沉积二氢卟酚的重要部分。为了研究CPP 516在海洋环境中的分布和来源，建立了一种新的CPP 516的色谱分析方法。我们发现高浓度的CPP 516在表层沉积物和颗粒物中收集的沉积物陷阱。它贡献了40至70%的总和Chl a1降解产物的粪便材料从草食性微型浮游动物和大型浮游动物。我们没有发现CPP 516在指数增长或静止期藻类培养物。这些数据表明，CPP 516的主要来源是以浮游植物为食的食草动物。我们还在沉积物和沉积物捕集器样品中发现了一系列类似于CPP 516的化合物。质谱和紫外（UV）/可见光谱分析表明，这些是二乙烯基-Chl a和Chl bs和Chl cs的CPP 516类似物，结论必须通过合成来证实。CPP 516溶于有机溶剂，在有氧条件下容易降解为132-oxopyropheophorbide a和叶绿素a。当与颗粒物结合时，CPP 516在好氧水生环境中稳定的时间尺度为几天，可能通过螯合金属阳离子来稳定。CPP 516的发色团与其他Chl a1降解产物的发色团显著不同;其在360、426和688 nm处具有最大吸收。CPP 516不像其他Chl a1降解产物那样发出荧光。因此，它对基于荧光的“色素”分析是不可见的。因此，当CPP 516对总二氢卟酚有显著贡献时，与肠道荧光和Chl预算方法结合使用时，从这些测量得出的放牧和生长速率将低估真实速率。
The labile chlorophyll a (Chl a1 ) degradation product, 132, 173‐cyclopheophorbide a enol (CPP516), was only recently found in marine sediments, where it can contribute a significant fraction to solvent‐extractable sedimentary chlorins. We developed a new chromatographic method for the analysis of CPP516 to study its distribution and sources in the marine environment. We found high concentrations of CPP516 in surficial sediments and particulate matter collected in sediment traps. It contributed 40 to 70% to the sum of all Chl a1 degradation products in fecal material from herbivorous microzooplankton and macrozooplankton. We did not find CPP516 in exponentially growing or stationary phase algal cultures. These data suggest that a major source of CPP516 is herbivores feeding on phytoplankton. We also found a series of compounds similar to CPP516 in sediments and sediment‐trap samples. Mass‐spectrometric and ultraviolet(UV)/visible‐spectrometric analyses suggest that these are CPP516 analogs of divinyl‐Chl a and Chl bs and Chl cs, conclusions that have to be confirmed by synthesis. CPP516, dissolved in organic solvents, easily degrades to 132 ‐oxopyropheophorbide a and chlorophyllone a under oxic conditions. When associated with particles, CPP516 is stable in oxic aquatic environments on a timescale of days, possibly stabilized by the chelation of metal cations. The chromophore of CPP516 differs substantially from that of other Chl a1 degradation products; it has absorption maxima at 360, 426, and 688 nm. CPP516 does not fluoresce as other Chl a1 degradation products. As a consequence, it is invisible to fluorescence‐based analyses of “pheopigments.” Thus, rates of grazing and growth derived from such measurements, as used in conjunction with the gut fluorescence and the Chl‐budget method, will be underestimates of true rates when CPP516 contributes significantly to total chlorins.