Wu Qinglong L, Chatzinotas Antonis, Wang Jianjun, Boenigk Jens
State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography & Limnology, Chinese Academy of Sciences, East Beijing Road 73, Nanjing 210008, People's Republic of China.
Microb Ecol. 2009 Oct;58(3):569-81. doi: 10.1007/s00248-009-9526-8. Epub 2009 May 16.
Eukaryotic plankton assemblages in 11 high-mountain lakes located at altitudes of 2,817 to 5,134 m and over a total area of ca. one million square kilometers on the Eastern Tibet Plateau, spanning a salinity gradient from 0.2 (freshwater) to 187.1 g l(-1) (hypersaline), were investigated by cultivation independent methods. Two 18S rRNA gene-based fingerprint approaches, i.e., the terminal restriction fragment length polymorphism and denaturing gradient gel electrophoresis (DGGE) with subsequent band sequencing were applied. Samples of the same lake type (e.g., freshwater) generally shared more of the same bands or T-RFs than samples of different types (e.g., freshwater versus saline). However, a certain number of bands or T-RFs among the samples within each lake were distinct, indicating the potential presence of significant genetic diversity within each lake. PCA indicated that the most significant environmental gradient among the investigated lakes was salinity. The observed molecular profiles could be further explained (17-24%) by ion percentage of chloride, carbonate and bicarbonate, and sulfate, which were also covaried with change of altitude and latitude. Sequence analysis of selected major DGGE bands revealed many sequences (largely protist) that are not related to any known cultures but to uncultured eukaryotic picoplankton and unidentified eukaryotes. One fourth of the retrieved sequences showed < or =97% similarity to the closest sequences in the GenBank. Sequences related to well-known heterotrophic nanoflagellates were not retrieved from the DGGE gels. Several groups of eukaryotic plankton, which were found worldwide and detected in low land lakes, were also detected in habitats located above 4,400 m, suggesting a cosmopolitan distribution of these phylotypes. Collectively, our study suggests that there was a high beta-diversity of eukaryotic plankton assemblages in the investigated Tibetan lakes shaped by multiple geographic and environmental factors.
利用非培养方法，对位于青藏高原东部海拔2817至5134米、总面积约100万平方公里的11个高山湖泊中的真核浮游生物组合进行了研究，这些湖泊的盐度梯度范围为0.2（淡水）至187.1克/升（超盐水）。应用了两种基于18S rRNA基因的指纹分析方法，即末端限制性片段长度多态性分析和变性梯度凝胶电泳（DGGE），并对随后的条带进行测序。同一湖泊类型（如淡水湖）的样本通常比不同类型（如淡水湖与盐湖）的样本共享更多相同的条带或末端限制性片段（T-RF）。然而，每个湖泊内的样本之间存在一定数量不同的条带或T-RF，这表明每个湖泊内可能存在显著的遗传多样性。主成分分析（PCA）表明，所研究湖泊中最显著的环境梯度是盐度。观察到的分子图谱可以由氯化物、碳酸盐、碳酸氢盐和硫酸盐的离子百分比进一步解释（17%-24%），这些离子百分比也与海拔和纬度的变化相关。对选定的主要DGGE条带进行序列分析，发现许多序列（主要是原生生物）与任何已知培养物无关，但与未培养的真核微微型浮游生物和未鉴定的真核生物有关。检索到的序列中有四分之一与GenBank中最相近序列的相似度小于或等于97%。未从DGGE凝胶中检索到与已知异养纳米鞭毛虫相关的序列。在海拔4400米以上的栖息地中也检测到了几组在全球范围内都能找到且在低地湖泊中也能检测到的真核浮游生物，这表明这些系统发育型具有全球分布性。总体而言，我们的研究表明，在受多种地理和环境因素影响的青藏高原湖泊中，真核浮游生物组合具有较高的β多样性。
