Somerville C C, Jouannic S, Martin W F, Kloareg B, Loiseaux-de Goër S
Centre d'Etudes Océanologiques et de Biologie Marine, CNRS-UPR 4601, Roscoff, France.
Plant Mol Biol. 1993 Mar;21(5):779-87. doi: 10.1007/BF00027111.
The entire nucleotide sequence of a 23S rRNA gene from the brown alga Pylaiella littoralis (L.) Kjellm has been determined. The predicted length of the 23S rRNA is 2948 nucleotides, including the 4.5S rRNA-like region at the 3' end of the molecule. The putative transcript has been folded into a secondary structure by comparison to existing structure models, and the predicted helical regions were inspected by identifying compensatory downstream base changes. The 23S rRNA secondary structure presented here has features that are unique to P. littoralis (no other chromophyte or red algal 23S rRNA sequences are yet available), but has none of the features specific to the chloroplast rRNAs of green plants and green algae. The Pylaiella sequence was aligned with analogous plastidial and eubacterial gene sequences, and the alignment was used to construct a phylogenetic tree. The plastidial sequences formed a coherent cluster closely associated with the 23S rRNA of the cyanobacterium Anacystis nidulans. Within the plastid group, the P. littoralis sequence was most closely related to that of Euglena gracilis confirming earlier analyses based upon 16S rRNA sequences.
已测定了褐藻小海带（Pylaiella littoralis (L.) Kjellm）23S rRNA基因的完整核苷酸序列。预测的23S rRNA长度为2948个核苷酸，包括分子3'端的4.5S rRNA样区域。通过与现有结构模型比较，将推定的转录本折叠成二级结构，并通过识别补偿性下游碱基变化来检查预测的螺旋区域。此处呈现的23S rRNA二级结构具有小海带特有的特征（尚无其他色藻或红藻23S rRNA序列），但没有绿色植物和绿藻叶绿体rRNA特有的特征。将小海带序列与类似的质体和真细菌基因序列进行比对，并利用该比对构建系统发育树。质体序列形成了一个与蓝细菌集胞藻（Anacystis nidulans）的23S rRNA紧密相关的连贯聚类。在质体组内，小海带序列与纤细裸藻（Euglena gracilis）的序列关系最为密切，这证实了基于16S rRNA序列的早期分析。
