Internal and external relationships of the Cnidaria : implications of primary and predicted secondary structure of the 5'–end of the 23S–like rDNA
Internal and external relationships of the Cnidaria : implications of primary and predicted secondary structure of the 5'–end of the 23S–like rDNA
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刺胞动物的内部和外部关系：23S 样 rDNA 5 端一级结构和预测二级结构的影响
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发表时间：
1997
期刊：
影响因子：
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通讯作者：
David J. Miller
中科院分区：
文献类型：
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作者：
D. Odorico;David J. Miller
由于根据18 S和（部分）16 S rDNA序列数据的分析，刺胞动物的内部（类别水平）和外部关系仍然不清楚，因此我们检查了23 S样rDNA 5 '端的信息性。在这里，我们描述了一级和预测的二级结构数据的分析，这一地区从栉水母Bolinopsis sp.，板形动物粘毛板（Trichoplaxadhaerens）、海绵Hymeniacidonheliophila以及所有四种刺胞纲的代表。一级序列分析清楚地将刺胞动物与其他低等后生动物区分开来，支持Scyphozoa和Cubozoa之间以及Ctenophora和Placozoa之间的姐妹群关系，并证实了珊瑚虫在刺胞动物中的基础地位。此外，在栉水母、扁盘动物和海绵中，需要非规范碱基配对来维持B12区的二级结构，而在刺胞动物中情况并非如此。虽然这一分子特征的系统发育意义尚不清楚，我们的分析不支持刺胞动物和Placozoa之间的密切关系的建议，以前的研究。
Since both internal (class–level) and external relationships of the Cnidaria remain unclear on the basis of analyses of 18S and (partial) 16S rDNA sequence data, we examined the informativeness of the 5'–end of the 23S-like rDNA. Here we describe analyses of both primary and predicted secondary structure data for this region from the ctenophore Bolinopsis sp., the placozoan Trichoplax adhaerens, the sponge Hymeniacidon heliophila, and representatives of all four cnidarian classes. Primary sequence analyses clearly resolved the Cnidaria from other lower Metazoa, supported sister group relationships between the Scyphozoa and Cubozoa and between the Ctenophora and the Placozoa, and confirmed the basal status of the Anthozoa within the Cnidaria. Additionally, in the ctenophore, placozoan and sponge, non-canonical base pairing is required to maintain the secondary structure of the B12 region, whereas amongst the Cnidaria this is not the case. Although the phylogenetic significance of this molecular character is unclear, our analyses do not support the close relationship between Cnidaria and Placozoa suggested by previous studies.