Evidence for an active rare biosphere within freshwater protists community
Evidence for an active rare biosphere within freshwater protists community
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DOI：
10.1111/mec.13116
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发表时间：
2015-03-01
影响因子：
4.9
通讯作者：
Domaizon, Isabelle
中科院分区：
文献类型：
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作者：
Debroas, Didier;Hugoni, Mylene;Domaizon, Isabelle
在RNA水平上对活性稀有生物圈的研究主要集中在细菌和藻类，而没有包括参与地球主要地球化学循环的原生生物。在这项研究中，丰富，组成和稀有原生生物生物圈的活动，确定从两个湖泊的时间调查焦磷酸测序。在这些生态系统中，稀有OTU占总OTU的77.2%，占系统发育多样性的76.6%。从计算的各种系统发育指数，系统发育单位（PU）构成的总是罕见的OTU完全区别于其他PU。因此，稀有生物圈主要包括与主要生物圈相比远离参考数据库的类群。此外，最稀有的OTU代表了rRNA描绘的活性生物圈的59.8%，并且活性（rRNA：rDNA比率）随着稀有度的增加而增加。在罕见的馏分中确定的高rRNA：rDNA比例突出表明，一些原生生物在低丰度下是活跃的，并有助于生态系统功能。有趣的是，总是罕见和活跃的OTU的特点是与测量的主要环境参数的季节性变化。总之，稀有的真核生物是湖泊生态系统中一个活跃的、动态的和被忽视的部分。
Studies on the active rare biosphere at the RNA level are mainly focused on Bacteria and Archaea and fail to include the protists, which are involved in the main biogeochemical cycles of the earth. In this study, the richness, composition and activity of the rare protistan biosphere were determined from a temporal survey of two lakes by pyrosequencing. In these ecosystems, the always rare OTUs represented 77.2% of the total OTUs and 76.6% of the phylogenetic diversity. From the various phylogenetic indices computed, the phylogenetic units (PUs) constituted exclusively by always rare OTUs were discriminated from the other PUs. Therefore, the rare biosphere included mainly taxa that are distant from the reference databases compared to the dominant ones. In addition, the rarest OTUs represented 59.8% of the active biosphere depicted by rRNA and the activity (rRNA:rDNA ratio) increased with the rarity. The high rRNA:rDNA ratio determined in the rare fraction highlights that some protists were active at low abundances and contribute to ecosystem functioning. Interestingly, the always rare and active OTUs were characterized by seasonal changes in relation with the main environmental parameters measured. In conclusion, the rare eukaryotes represent an active, dynamic and overlooked fraction in the lacustrine ecosystems.