Phytoplankton in the ocean use non-phosphorus lipids in response to phosphorus scarcity
Phytoplankton in the ocean use non-phosphorus lipids in response to phosphorus scarcity
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DOI：
10.1038/nature07659
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发表时间：
2009-03-05
期刊：
影响因子：
64.8
通讯作者：
Webb, Eric A.
中科院分区：
文献类型：
--
作者：
Van Mooy, Benjamin A. S.;Fredricks, Helen F.;Webb, Eric A.
磷是所有生物生长所必需的；海洋浮游生物中磷的主要生化储存库包括核酸和磷脂(1-3)。然而，当环境中的磷缺乏时，真核浮游植物和蓝藻(统称为浮游植物)有能力减少它们细胞内的磷含量(1，4，5)。让浮游植物限制其磷需求并保持生长的生化机制在很大程度上是未知的。在这里，我们展示了浮游植物，在磷酸盐稀缺的少营养海洋区域，通过用非磷膜脂替代磷脂来减少细胞对磷的需求。在马尾藻海，磷酸盐浓度低于10nmoL L(-1)，我们发现只有1.3+/-0.6%的磷酸盐被用于磷脂合成；相反，在南太平洋副热带环流，磷酸盐大于100nmoL L(-1)，浮游生物利用了17+/-6%(参考文献)。6)。对这两个地点浮游膜脂的检查表明，马尾藻海中不含磷的含硫和含氮膜脂类比南太平洋更为丰富。此外，在我们研究的所有浮游植物物种的磷限制培养中，这些无磷的“替代脂”占主导地位。相反，我们研究的海洋异养细菌不含替代脂，只含有磷脂。因此，异养细菌在马尾藻海等营养稀少的区域与浮游植物争夺营养物质，似乎有一种生化磷需求，而浮游植物通过使用替代脂来避免这种需求。我们的结果表明，磷脂替代是浮游植物在磷限制下保持生长的基本生化机制。
Phosphorus is an obligate requirement for the growth of all organisms; major biochemical reservoirs of phosphorus in marine plankton include nucleic acids and phospholipids(1-3). However, eukaryotic phytoplankton and cyanobacteria (that is, 'phytoplankton' collectively) have the ability to decrease their cellular phosphorus content when phosphorus in their environment is scarce(1,4,5). The biochemical mechanisms that allow phytoplankton to limit their phosphorus demand and still maintain growth are largely unknown. Here we show that phytoplankton, in regions of oligotrophic ocean where phosphate is scarce, reduce their cellular phosphorus requirements by substituting non-phosphorus membrane lipids for phospholipids. In the Sargasso Sea, where phosphate concentrations were less than 10 nmol l(-1), we found that only 1.3 +/- 0.6% of phosphate uptake was used for phospholipid synthesis; in contrast, in the South Pacific subtropical gyre, where phosphate was greater than 100 nmol l(-1), plankton used 17 +/- 6% (ref. 6). Examination of the planktonic membrane lipids at these two locations showed that classes of sulphur- and nitrogen-containing membrane lipids, which are devoid of phosphorus, were more abundant in the Sargasso Sea than in the South Pacific. Furthermore, these non-phosphorus, 'substitute lipids' were dominant in phosphorus-limited cultures of all of the phytoplankton species we examined. In contrast, the marine heterotrophic bacteria we examined contained no substitute lipids and only phospholipids. Thus heterotrophic bacteria, which compete with phytoplankton for nutrients in oligotrophic regions like the Sargasso Sea, appear to have a biochemical phosphorus requirement that phytoplankton avoid by using substitute lipids. Our results suggest that phospholipid substitutions are fundamental biochemical mechanisms that allow phytoplankton to maintain growth in the face of phosphorus limitation.