von Nickisch-Rosenegk M, Brown W M, Boore J L
Department of Biology, University of Michigan, USA.
Mol Biol Evol. 2001 May;18(5):721-30. doi: 10.1093/oxfordjournals.molbev.a003854.
Using "long-PCR," we amplified in overlapping fragments the complete mitochondrial genome of the tapeworm Hymenolepis diminuta (Platyhelminthes: Cestoda) and determined its 13,900-nt sequence. The gene content is the same as that typically found for animal mitochondrial DNA (mtDNA) except that atp8 appears to be lacking, a condition found previously for several other animals. Despite the small size of this mtDNA, there are two large noncoding regions, one of which contains 13 repeats of a 31-nt sequence and a potential stem-loop structure of 25 bp with an 11-member loop. Large potential secondary structures were identified also for the noncoding regions of two other cestode mtDNAS: Comparison of the mitochondrial gene arrangement of H. diminuta with those previously published supports a phylogenetic position of flatworms as members of the Eutrochozoa, rather than placing them basal to either a clade of protostomes or a clade of coelomates.
我们使用“长链聚合酶链式反应（long-PCR）”，以重叠片段的形式扩增了微小膜壳绦虫（扁形动物门：绦虫纲）的完整线粒体基因组，并测定了其13900个核苷酸的序列。该基因组成与动物线粒体DNA（mtDNA）的典型组成相同，只是似乎缺少atp8基因，这种情况在其他几种动物中也曾出现过。尽管这种线粒体DNA的规模较小，但存在两个较大的非编码区，其中一个包含一段31个核苷酸序列的13次重复以及一个由25个碱基对构成的潜在茎环结构，该茎环结构带有一个由11个成员组成的环。另外两种绦虫线粒体DNA的非编码区也鉴定出了较大的潜在二级结构：将微小膜壳绦虫的线粒体基因排列与先前发表的基因排列进行比较，支持了扁形动物作为真螺旋动物成员的系统发育位置，而不是将它们置于原口动物分支或体腔动物分支的基部。
