Unveiling the organisms behind novel eukaryotic ribosomal DNA sequences from the ocean
Unveiling the organisms behind novel eukaryotic ribosomal DNA sequences from the ocean
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DOI：
10.1128/aem.68.9.4554-4558.2002
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发表时间：
2002-09-01
影响因子：
4.4
通讯作者：
Pedrós-Alió, C
中科院分区：
文献类型：
--
作者：
Massana, R;Guillou, L;Pedrós-Alió, C
尽管最小的真核生物（直径小于5微米的细胞）在海洋食物网中发挥着关键作用，特别是在开放的贫营养区，但对其原位多样性的研究仅在一年前开始。最近的研究中最引人注目的发现可能是发现了全新的系统发生谱系，例如属于层孔门和蜂窝门的新分支。在北大西洋、赤道太平洋、南极和地中海沃茨的遗传文库中，这两个新的群体占克隆的很大一部分。然而，这些生物的身份和生态相关性仍然未知。在这里，我们调查的系统发育关系，形态，在原地丰度，和生态作用的新strageliles。它们形成至少8个独立的分支内的层生基枝，表明一个大的系统发育的多样性组内。两个谱系可视化，并列举了现场样品和富集荧光原位杂交使用特定的rRNA靶向寡核苷酸探针。目标生物体为直径2- 3 μ m、圆形、无色素的鞭毛虫。此外，它们被发现是噬菌的。一个谱系占高达46%（平均在一年的周期，19%）的异养鞭毛虫在沿海环境中，提供证据表明，新的strageliles是重要的和未被识别的组成部分的细菌食草动物的总库存。
Despite the fact that the smallest eukaryotes (cells less than 5 mum in diameter) play key roles in marine food webs, particularly in open oligotrophic areas, the study of their in situ diversity started just one year ago. Perhaps the most remarkable finding of the most recent studies has been the discovery of completely new phylogenetic lineages, such as novel clades belonging to the stramenopile and alveolate phyla. The two new groups account for a significant fraction of clones in genetic libraries from North Atlantic, equatorial Pacific, Antarctic, and Mediterranean Sea waters. However, the identities and ecological relevance of these organisms remain unknown. Here we investigate the phylogenetic relationships, morphology, in situ abundance, and ecological role of novel stramenopiles. They form at least eight independent clades within the stramenopile basal branches, indicating a large phylogenetic diversity within the group. Two lineages were visualized and enumerated in field samples and enrichments by fluorescent in situ hybridization using specific rRNA-targeted oligonucleotide probes. The targeted organisms were 2- to 3-mum-diameter, round-shaped, nonpigmented flagellates. Further, they were found to be bacterivorous. One lineage accounted for up to 46% (average during an annual cycle, 19%) of heterotrophic flagellates in a coastal environment, providing evidence that novel stramenopiles are important and unrecognized components of the total stock of bacterial grazers.