浮游生物需要養(yǎng)分磷來生長及合成構(gòu)成它們細(xì)胞的分子,，包括脂肪一樣的類脂分子,。在海洋中的某些地方，磷可能會極為稀缺,，然而一類浮游生物,，即能夠進(jìn)行光合作用的浮游植物，似乎能夠應(yīng)對這種狀況?，F(xiàn)在,，這一現(xiàn)象的原因已被發(fā)現(xiàn)：它們能夠產(chǎn)生不含磷的類脂分子。
我們知道,，浮游植物通過減少它們細(xì)胞中的磷含量來應(yīng)對磷供應(yīng)量所受限制,， 而現(xiàn)在用來自“馬尾藻海”低磷酸鹽海水所做實驗表明，浮游植物（而不是異養(yǎng)菌）能夠用含硫和氮的類脂取代它們細(xì)胞膜中的磷脂,。利用這些替代性類脂的能力在低磷環(huán)境中也許能夠提供一種競爭優(yōu)勢。（生物谷Bioon.com）
生物谷推薦原始出處：
Nature 458, 69-72 (5 March 2009) | doi:10.1038/nature07659
Phytoplankton in the ocean use non-phosphorus lipids in response to phosphorus scarcity
Benjamin A. S. Van Mooy1, Helen F. Fredricks1, Byron E. Pedler1,11, Sonya T. Dyhrman2, David M. Karl3, Michal Koblíek4,5, Michael W. Lomas6, Tracy J. Mincer1, Lisa R. Moore7, Thierry Moutin8, Michael S. Rappé9 & Eric A. Webb10
1 Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA
2 Department of Biology, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA
3 Department of Oceanography, University of Hawaii, Honolulu, Hawaii, USA
4 Institute of Microbiology, Czech Academy of Sciences, Tebo, Czech Republic
5 Institute of Physical Biology, University of South Bohemia, Nové Hrady, Czech Republic
6 Bermuda Institute of Ocean Sciences, St. George, Bermuda
7 Department of Biological Sciences, University of Southern Maine, Portland, Maine, USA
8 Laboratoire d'Océanographie Physique et Biogéochimique, Centre d'Océanologie de Marseille, Aix-Marseille University, France
9 Hawaii Institute of Marine Biology, University of Hawaii, Kaneohe, Hawaii, USA
10 Department of Biological Sciences, University of Southern California, Los Angeles, California, USA
11 Present address: Scripps Institution of Oceanography, University of California at San Diego, La Jolla, California, USA.
Phosphorus is an obligate requirement for the growth of all organisms; major biochemical reservoirs of phosphorus in marine plankton include nucleic acids and phospholipids1, 2, 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 scarce1, 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.
