The complete mitochondrial DNA of three monozoic tapeworms in the Caryophyllidea: a mitogenomic perspective on the phylogeny of eucestodes.
The complete mitochondrial DNA of three monozoic tapeworms in the Caryophyllidea: a mitogenomic perspective on the phylogeny of eucestodes.
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石竹总科三种单生代绦虫的完整线粒体DNA：从线粒体基因组学角度观察真丝虫的系统发育
DOI：
10.1186/s13071-017-2245-y
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发表时间：
2017-06-27
影响因子：
3.2
通讯作者：
Wang GT
中科院分区：
文献类型：
--
作者：
Li WX;Zhang D;Boyce K;Xi BW;Zou H;Wu SG;Li M;Wang GT
外切分和内proglog石化是长尾藻的重要进化特征。基于部分线粒体基因和核rDNA序列，单生石蕊虫被认为是最早分化的原足动物，但目前还没有完整的有丝分裂基因组。因此，我们对3种石竹属植物和多生子叶类植物进行了完整的有丝分裂基因组测序，探讨了原子叶属植物的系统发育关系，并比较了未分段和分段的原子叶属植物的基因排列。结果huonensis的环状有丝分裂基因组序列最长，为15,130 bp， khawia sinensis为14,620 bp, breviscolex orientalisis14,011 bp， schyzocotyle acheilognathi为14,046 bp。这三种石核树的A-T含量低于其他已发表的有丝分裂基因组。在非编码区（ncr）中发现了高度重复的区域。利用全部36个基因重构的mtDNA大片段，确定了5个目（石竹目、双叶竹目、双叶竹目、protecephalalidea和Cyclophyllidea）的进化关系与形态学预测一致。对这5目的54个有丝分裂基因组的分析表明，除了Cyclophyllidea有两个与Diphyllobothriidea和Proteocephalidea相同的类型外，每个目都有一个独特的排列。在比较未分割的和分割的子囊的基因顺序时，发现分割的子囊由于长距离的转位事件而具有较低的相似性。四种排列类别之间的所有重排事件都发生在ncr常见的rrns - trnaarg （P1）交界处。结论4种蠓的ncr中均存在高度重复的区域。在未分割的和分割的细胞之间推断出一个长距离的转位事件。带绦虫科和环虫科其余科的基因排列分别与姐妹目Proteocephalidea和相对较基础的目Diphyllobothriidea相同。
BackgroundExternal segmentation and internal proglottization are important evolutionary characters of the Eucestoda. The monozoic caryophyllideans are considered the earliest diverging eucestodes based on partial mitochondrial genes and nuclear rDNA sequences, yet, there are currently no complete mitogenomes available. We have therefore sequenced the complete mitogenomes of three caryophyllideans, as well as the polyzoicSchyzocotyle acheilognathi, explored the phylogenetic relationships of eucestodes and compared the gene arrangements between unsegmented and segmented cestodes.ResultsThe circular mitogenome ofAtractolytocestus huronensiswas 15,130 bp, the longest sequence of all the available cestodes, 14,620 bp forKhawia sinensis, 14,011 bp forBreviscolex orientalisand 14,046 bp forSchyzocotyle acheilognathi. The A-T content of the three caryophyllideans was found to be lower than any other published mitogenome. Highly repetitive regions were detected among the non-coding regions (NCRs) of the four cestode species. The evolutionary relationship determined between the five orders (Caryophyllidea, Diphyllobothriidea, Bothriocephalidea, Proteocephalidea and Cyclophyllidea) is consistent with that expected from morphology and the large fragments of mtDNA when reconstructed using all 36 genes. Examination of the 54 mitogenomes from these five orders, revealed a unique arrangement for each order except for the Cyclophyllidea which had two types that were identical to that of the Diphyllobothriidea and the Proteocephalidea. When comparing gene order between the unsegmented and segmented cestodes, the segmented cestodes were found to have the lower similarities due to a long distance transposition event. All rearrangement events between the four arrangement categories took place at the junction ofrrnS-tRNAArg(P1) where NCRs are common.ConclusionsHighly repetitive regions are detected among NCRs of the four cestode species. A long distance transposition event is inferred between the unsegmented and segmented cestodes. Gene arrangements of Taeniidae and the rest of the families in the Cyclophyllidea are found be identical to those of the sister order Proteocephalidea and the relatively basal order Diphyllobothriidea, respectively.