Biosynthesis of sterols and wax esters by Euglena of acid mine drainage biofilms: Implications for eukaryotic evolution and the early Earth
Biosynthesis of sterols and wax esters by Euglena of acid mine drainage biofilms: Implications for eukaryotic evolution and the early Earth
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DOI：
10.1016/j.chemgeo.2012.03.003
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发表时间：
2012-05
期刊：
影响因子：
3.9
通讯作者：
S. Dasgupta;Jiasong Fang;S. Brake;S. Hasiotis;Li Zhang
中科院分区：
文献类型：
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作者：
S. Dasgupta;Jiasong Fang;S. Brake;S. Hasiotis;Li Zhang
对印第安纳州西部一个酸性矿山排水(AMD)场地的底栖生物和漂浮生物的脂质分析表明，光合作用生物以裸藻为主，其中含有丰富的植二烯、植醇、植醇、多不饱和正烯、多不饱和脂肪酸、短链(C25-32)蜡酯(WE)、麦角甾醇和生育酚。WE可能是在缺氧条件下在线粒体中合成的，而甾醇(麦角固醇和麦角-7，22-二烯-3β-ol)可能是在分子氧存在下在胞浆中由嗜酸、光合微真核生物Euglena合成的。好氧和厌氧两条生物合成途径可能是地球厌氧过去的生化遗迹。Euglena生物合成机制的保守区划可能允许早期真核生物在早期地球上生存和多样化，尽管它们在进化，但它们保存了这种生理。真核生物能够产生短链WE，可被认为是低分子(C12-16)正构烷烃的前体，可作为检测前寒武纪地层中此类真核生物的代用品。此外，麦角甾醇及其衍生物也可作为此类生物的生物标志物。
Lipid analysis of benthic and floating biofilms from an acid mine drainage (AMD) site in western Indiana revealed the dominance of photosynthetic organisms, mainly Euglena, as indicated by the detection of abundant phytadiene, phytol, phytanol, polyunsaturated n-alkenes, polyunsaturated fatty acids, short-chain (C25–32) wax esters (WE), ergosterol, and tocopherols. The WE were probably synthesized in mitochondria under anoxic conditions, whereas the sterols (ergosterol and ergosta-7,22-dien-3β-ol) were likely synthesized in the cytosol in the presence of molecular oxygen by the acidophilic, photosynthetic microeukaryotes Euglena. The dual aerobic and anaerobic biosynthetic pathways may be the biochemical relics of the anaerobic past of the Earth. The conserved compartmentalization of Euglena biosynthetic machinery may have allowed early eukaryotes to survive and diversify on early Earth, and despite their evolution, they preserved this physiology. Euglenids are capable of producing suites of short-chain WE that can be considered precursors for low-molecular weight (C12–16) n-alkanes, which can serve as proxies for the detection of such eukaryotic organisms in Precambrian strata. In addition, ergosterol and its derivative can also serve as biomarkers for such organisms.