The flatworm mitochondrial genome: an expansion into the phylogeny and molecular epidemiology of taeniid tapeworms

推测了线虫的线粒体遗传密码。在扁形蠕虫中，UAA密码子被指定为酪氨酸；然而，很明显，它像其他后生动物一样是终止密码子。此外，我们还确定了GUG密码子作为起始密码子。测定了多房棘球绦虫和猪带绦虫线粒体基因组(MtDNA)的完整DNA序列。E，多房线粒体DNA是一个环状基因组(全长13,738个核苷酸)，包含36个基因(12个参与氧化磷酸化的蛋白质，2个rRNAs和22个tRNAs)，但ATP8基因缺失。所有的基因都以相同的方向转录。ND1和Cox1基因之间的部分组织结构与环节动物mtDNA相似，提示扁形线虫起源于真鞭毛虫。立枯丝核菌mtDNA全长13,709个碱基，其基因序列与多房链霉菌mtDNA序列一致。在ND1的一个基因中，第一次在扁虫mtDNA中证实了缩写的终止密码子U。CDNA的序列分析表明，完整的终止密码子UAA是由多聚腺苷酸化在转录后产生的。利用聚合酶链式反应扩增Cox1和Cytb基因序列，在不同地理样本之间确定了遗传多样性。来自中国、泰国、伊里安·查亚和印度的亚洲样本形成了一个单独的簇；然而，来自墨西哥、秘鲁、厄瓜多尔、玻利维亚和巴西的拉丁美洲样本与来自坦桑尼亚、莫桑比克和喀麦隆的非洲样本结合形成了一个额外的簇。这些结果和猪驯化的历史数据表明，Solium是最近从欧洲不同地区传入拉丁美洲和非洲的，另一来源的绦虫是在亚洲国家独立传播的。

The mitochondrial genetic code of cestodes was presumed. In the Platyhelminthes the codon UAA was assigned as tyrosine; however, it became clear that it is the termination codon like other metazoan animals. Moreover, we defined that the codon GUG serves as an initiation codon.The complete DNA sequences of the mitochondrial genomes (mtDNA) of the tapeworm Echinococcus multilocularis and Taenia solium have been determined. The E, multilocularis mtDNA is a circular genome (13,738 bp in length) and contains 36 genes (12 for proteins involved in oxidative phosphorylation, 2 for rRNAs and 22 for tRNAs) but a gene for ATP8 is missing. All genes are transcribed in the same direction. The gene arrangement is characteristic but the partial organization between ND1 and Cox1 genes is similar to those of annelid mtDNAs, suggesting that the Platyhelminthes is derived within the Eutrochozoa. The T. solium mtDNA is 13,709 bp in length and its gene arrangement is identical with that of the E. multilocularis mtDNA. In a gene for ND1, the abbreviated stop codon U was confirmed for the first time in flatworm mtDNAs. A sequence analysis of CDNA demonstrated that the complete termination codon UAA is created post-transcriptionally by polyadenylation.Genetic polymorphism was determined among geographic samples of T. solium, using PCR-amplified sequences of Coxl and Cytb genes. The Asian samples from China, Thailand, Irian Jaya, and India formed a single cluster; however, the Latin American samples from Mexico, Peru, Ecuador, Bolivia, and Brazil combined with the African samples from Tanzania, Mozambique, and Cameroon to form an additional cluster. These results and historical data of swine domestication suggest that T. solium was introduced recently into Latin America and Africa from different parts of Europe and that the tapeworm of another origin was independently spread in Asian countries.