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Abstract：
The small- and large-subunit mitochondrial ribosomal RNA genes (mt-s-rRNA and mt-l-rRNA) of the nematode worms Caenorhabditis elegans and Ascaris suum encode the smallest rRNAs so far reported for metazoa. These size reductions correlate with the previously described, smaller, structurally anomalous mt-tRNAs of C. elegans and A. suum. Using primer extension analysis, the 5\' end nucleotides of the mt-s-rRNA and mt-l-rRNA genes were determined to be adjacent to the 3\' end nucleotides of the tRNA(Glu) and tRNA(His) genes, respectively. Detailed, consensus secondary-structure models were constructed for the mt-s-rRNA genes and the 3\' 64% of mt-l-rRNA genes of the two nematodes. The mt-s-rRNA secondary-structure model bears a remarkable resemblance to the previously defined universal core structure of E. coli 16S rRNA: most of the nucleotides that have been classified as variable or semiconserved in the E. coli model appear to have been eliminated from the C. elegans and A. suum sequences. Also, the secondary structure model constructed for the 3\' 64% of the mt-l-rRNA is similar to the corresponding portion of the previously defined E. coli 23S rRNA core secondary structure. The proposed C. elegans/A. suum mt-s-rRNA and mt-l-rRNA models include all of the secondary-structure element-forming sequences that in E. coli rRNAs contain nucleotides important for A-site and P-site (but not E-site) interactions with tRNAs. Sets of apparently homologous sequences within the mt-s-rRNA and mt-l-rRNA core structures, derived by alignment of the C. elegans and A. suum mt-rRNAs to the corresponding mt-rRNAs of other eukaryotes, and E. coli rRNAs were used in maximum-likelihood analyses. The patterns of divergence of metazoan phyla obtained show considerable agreement with the most prevalent metazoan divergence patterns derived from more classical, morphological, and developmental data.
摘要：
线虫线虫线虫和A虫的小亚基和大亚基线粒体核糖体RNA基因（mt-s-rRNA和mt-l-rRNA）编码迄今为止报道的最小rRNA。这些尺寸减小与前面描述的相关，更小,线虫和A.suum的结构异常mt-tRNA。使用引物延伸分析，确定mt-s-rRNA和mt-l-rRNA基因的5个末端核苷酸与tRNA（Glu）和tRNA（His）基因的3个末端核苷酸相邻，分别。Detailed,为两种线虫的mt-s-rRNA基因和3/64％的mt-l-rRNA基因构建了共有二级结构模型。mt-s-rRNA二级结构模型与先前定义的大肠杆菌16SrRNA的通用核心结构非常相似：在大肠杆菌模型中被分类为可变或半保守的大多数核苷酸似乎已从秀丽隐杆线虫和A.suum序列中消除。此外，为3/64％的mt-l-rRNA构建的二级结构模型类似于先前定义的大肠杆菌23SrRNA核心二级结构的相应部分。拟议的C.elegans/A.suummt-s-rRNA和mt-l-rRNA模型包括所有二级结构元件形成序列,其在大肠杆菌rRNA中含有对于与tRNA的A位点和P位点(但非E位点)相互作用重要的核苷酸。mt-s-rRNA和mt-l-rRNA核心结构内的一组明显同源序列，通过将C.elegans和A.suummt-rRNA与其他真核生物的相应mt-rRNA进行比对而得出，和大肠杆菌rRNA用于最大似然分析。获得的后生动物门的发散模式与从更经典的，形态学,和发展数据。
