Lenaers G, Scholin C, Bhaud Y, Saint-Hilaire D, Herzog M
Département de Biologie Cellulaire et Moléculaire, Université de Paris VI, CNRS UA 117, Banyuls-sur-Mer, France.
J Mol Evol. 1991 Jan;32(1):53-63. doi: 10.1007/BF02099929.
The sequence of two divergent domains (D1 and D8) from dinoflagellate 24S large subunit rRNA was determined by primer extension using total RNA as template. Nucleotide sequence alignments over 401 bases have been analyzed in order to investigate phylogenetic relationships within this highly divergent and taxonomically controversial group of protists of the division Pyrrhophyta. Data are provided confirming that dinoflagellates represent a monophyletic group. For 11 out of the 13 investigated laboratory grown species, an additional domain (D2) could not be completely sequenced by reverse transcription because of a hidden break located near its 3'-terminus. Two sets of sequence alignments were used to infer dinoflagellate phylogeny. The first [199 nucleotides (nt)] included conservative sequences flanking the D1 and D8 divergent domains. It was used to reconstruct a broad evolutionary tree for the dinoflagellates, which was rooted using Tetrahymena thermophila as the outgroup. To confirm the tree topology, and mainly the branchings leading to closely related species, a second alignment (401 nt) was considered, which included the D1 and D8 variable sequences in addition to the more conserved flanking regions. Species that showed sequence similarities with other species lower than 60% on average (Knuc values higher than 0.550) were removed from this analysis. A coherent and convincing evolutionary pattern was obtained for the dinoflagellates, also confirmed by the position of the hidden break within the D2 domain, which appears to be group specific. The reconstructed phylogeny indicates that the early emergence of Oxyrrhis marina preceded that of most Peridiniales, a large order of thecate species, whereas the unarmored Gymnodiniales appeared more recently, along with members of the Prorocentrales characterized by two thecal plates. In addition, the emergence of heterotrophic species preceded that of photosynthetic species. These results provide new perspectives on proposed evolutionary trees for the dinoflagellates based on morphology, biology, and fossil records.
以总RNA为模板，通过引物延伸法测定了甲藻24S大亚基rRNA两个不同结构域（D1和D8）的序列。为了研究这一高度分化且在分类学上存在争议的甲藻门原生生物类群内部的系统发育关系，对401个碱基的核苷酸序列比对进行了分析。提供的数据证实甲藻代表一个单系类群。在13个实验室培养的被研究物种中，有11个物种的另一个结构域（D2）由于其3'端附近存在一个隐藏的断裂点，无法通过逆转录完全测序。使用两组序列比对来推断甲藻的系统发育。第一组[199个核苷酸（nt）]包括D1和D8不同结构域两侧的保守序列。它被用于构建甲藻的广泛进化树，该进化树以嗜热四膜虫作为外类群进行根定。为了确认树的拓扑结构，主要是确认导致亲缘关系密切物种的分支，考虑了第二组比对（401 nt），它除了更保守的侧翼区域外，还包括D1和D8可变序列。平均而言，与其他物种序列相似性低于60%（Knuc值高于0.550）的物种被排除在该分析之外。甲藻获得了一个连贯且令人信服的进化模式，D2结构域内隐藏断裂点的位置也证实了这一点，该断裂点似乎具有类群特异性。重建的系统发育表明，尖尾藻的早期出现早于大多数具壳甲藻目（一个大型的具壳物种目），而无甲的裸甲藻目出现得更近，同时出现的还有以两个壳板为特征的原甲藻目成员。此外，异养物种的出现早于光合物种。这些结果为基于形态学、生物学和化石记录提出的甲藻进化树提供了新的视角。
