EST sequencing of Onychophora and phylogenomic analysis of Metazoa.
EST sequencing of Onychophora and phylogenomic analysis of Metazoa.
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DOI：
10.1016/j.ympev.2007.09.002
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发表时间：
2007-12
影响因子：
4.1
通讯作者：
F. Roeding;Silke Hagner-Holler;H. Ruhberg;I. Ebersberger;A. von Haeseler;M. Kube;R. Reinhardt;T. Bur
中科院分区：
文献类型：
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作者：
F. Roeding;Silke Hagner-Holler;H. Ruhberg;I. Ebersberger;A. von Haeseler;M. Kube;R. Reinhardt;T. Bur
Onychophora（天鹅绒蠕虫）代表了一个被认为与真节足动物门有关的小动物分类群。从绒毛虫Epiperipatus sp.获得1873条5′端cDNA序列（expressed sequence tags，ESTs），它们被组装成833个重叠群。BLAST相似性搜索显示，51.9%的重叠群在蛋白质数据库中匹配，期望值低于10−4。大多数EST与脊索动物或节肢动物的蛋白质有最好的命中（分别为约40%）。EST包括27个核糖体蛋白的序列。从包括其他EST项目在内的数据库中获得了来自广泛门的其他28个物种的正向序列。构建了包含5021个位置的串联氨基酸比对，当去除有问题的区域时，其覆盖4259个位置。贝叶斯和最大似然法将Epiperipatus置于单系蜕皮动物（Onychophora，Arthropoda，Tardigrada和Nematoda）中，但其与Euarthropoda的确切关系仍未得到解决。“关节”概念未得到支持。缓步动物和线虫形成了一个支持良好的单门，这表明缓步动物实际上是Cycloneuralia。与以前的研究一致，我们已经证明，随机测序的cDNA的结果在序列信息，适合于多基因组方法来解决后生动物的关系。
Onychophora (velvet worms) represent a small animal taxon considered to be related to Euarthropoda. We have obtained 1873 5′ cDNA sequences (expressed sequence tags, ESTs) from the velvet worm Epiperipatus sp., which were assembled into 833 contigs. BLAST similarity searches revealed that 51.9% of the contigs had matches in the protein databases with expectation values lower than 10−4. Most ESTs had the best hit with proteins from either Chordata or Arthropoda (∼40% respectively). The ESTs included sequences of 27 ribosomal proteins. The orthologous sequences from 28 other species of a broad range of phyla were obtained from the databases, including other EST projects. A concatenated amino acid alignment comprising 5021 positions was constructed, which covers 4259 positions when problematic regions were removed. Bayesian and maximum likelihood methods place Epiperipatus within the monophyletic Ecdysozoa (Onychophora, Arthropoda, Tardigrada and Nematoda), but its exact relation to the Euarthropoda remained unresolved. The “Articulata” concept was not supported. Tardigrada and Nematoda formed a well-supported monophylum, suggesting that Tardigrada are actually Cycloneuralia. In agreement with previous studies, we have demonstrated that random sequencing of cDNAs results in sequence information suitable for phylogenomic approaches to resolve metazoan relationships.