microRNAs reveal the interrelationships of hagfish, lampreys, and gnathostomes and the nature of the ancestral vertebrate
microRNAs reveal the interrelationships of hagfish, lampreys, and gnathostomes and the nature of the ancestral vertebrate
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DOI：
10.1073/pnas.1010350107
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发表时间：
2010-11-09
影响因子：
11.1
通讯作者：
Peterson, Kevin J.
中科院分区：
文献类型：
--
作者：
Heimberg, Alysha M.;Cowper-Sallari, Richard;Peterson, Kevin J.
盲鳗和七鳃鳗是无颌脊椎动物（无颌类）的唯一现存代表，与有颌脊椎动物（有颌类）相比，它们提供了对祖先脊椎动物的胚胎学、基因组学和身体结构的深入了解。然而，这种见解因它们之间相互关系的争议而被掩盖。形态学分支分析已确定七鳃鳗和颌口动物是最近亲，而分子系统发育研究则恢复了单系环口目（盲鳗和七鳃鳗是最近亲）。在这里，我们通过小RNA文库的深度测序，结合基因组调查，表明环口目是单系的：盲鳗和七鳃鳗共享4个独特的microRNA家族，15个更原始的microRNA家族的独特旁系同源物，以及对成熟基因产物的22个独特取代。对形态学数据的重新分析表明，对环口类并系动物的支持很大程度上是基于不正确的字符编码，并且修订后的数据集对于单口类与单口类的对比并不具有决定性。环口动物并系。此外，我们发现七鳃鳗、盲鳗和颚口动物器官中 microRNA 表达模式的基本保守性，这意味着特定器官中 microRNA 的作用与其在基因组中的出现一致，并且随着时间的推移而保守。总之，这些数据支持了圆口动物的单系性，并表明所有现存脊椎动物的最后共同祖先是一种比比较形态学家和发育生物学家通常接受的更为复杂的生物体。
Hagfish and lampreys are the only living representatives of the jawless vertebrates (agnathans), and compared with jawed vertebrates (gnathostomes), they provide insight into the embryology, genomics, and body plan of the ancestral vertebrate. However, this insight has been obscured by controversy over their interrelationships. Morphological cladistic analyses have identified lampreys and gnathostomes as closest relatives, whereas molecular phylogenetic studies recover a monophyletic Cyclostomata (hagfish and lampreys as closest relatives). Here, we show through deep sequencing of small RNA libraries, coupled with genomic surveys, that Cyclostomata is monophyletic: hagfish and lampreys share 4 unique microRNA families, 15 unique paralogues of more primitive microRNA families, and 22 unique substitutions to the mature gene products. Reanalysis of morphological data reveals that support for cyclostome paraphyly was based largely on incorrect character coding, and a revised dataset is not decisive on the mono-vs. paraphyly of cyclostomes. Furthermore, we show fundamental conservation of microRNA expression patterns among lamprey, hagfish, and gnathostome organs, implying that the role of microRNAs within specific organs is coincident with their appearance within the genome and is conserved through time. Together, these data support the monophyly of cyclostomes and suggest that the last common ancestor of all living vertebrates was a more complex organism than conventionally accepted by comparative morphologists and developmental biologists.