Institute of Parasitology, Slovak Academy of Sciences, Hlinkova 3, 040 01, Košice, Slovakia.
Parasitol Res. 2012 May;110(5):1621-9. doi: 10.1007/s00436-011-2673-0. Epub 2011 Oct 11.
Sequence structure of complete internal transcribed spacer 1 and 2 (ITS1 and ITS2) of the ribosomal DNA region and partial mitochondrial cytochrome c oxidase subunit I (cox1) gene sequences were studied in the monozoic tapeworm Atractolytocestus sagittatus (Kulakovskaya et Akhmerov, 1965) (Cestoda: Caryophyllidea), a parasite of common carp (Cyprinus carpio carpio L.). Intraindividual sequence diversity was observed in both ribosomal spacers. In ITS1, a total number of 19 recombinant clones yielded eight different sequence types (pairwise sequence identity, 99.7-100%) which, however, did not resemble the structure typical for divergent intragenomic ITS copies (paralogues). Polymorphism was displayed by several single nucleotide mutations present exclusively in single clones, but variation in the number of short repetitive motifs was not observed. In ITS2, a total of 21 recombinant clones yielded ten different sequence types (pairwise sequence identity, 97.5-100%). They were mostly characterized by a varying number of (TCGT)(n) repeats resulting in assortment of ITS2 sequences into two sequence variants, which reflected the structure specific for ITS paralogues. The third DNA region analysed, mitochondrial cox1 gene (669 bp) was detected to be 100% identical in all studied A. sagittatus individuals. Comparison of molecular data on A. sagittatus with those on Atractolytocestus huronensis Anthony, 1958, an invasive parasite of common carp, has shown that interspecific differences significantly exceeded intraspecific variation in both ribosomal spacers (81.4-82.5% in ITS1, 74.4-75.2% in ITS2) as well as in mitochondrial cox1, which confirms validity of both congeneric tapeworms parasitic in the same fish host.
核糖体 DNA 区的完整内部转录间隔区 1 和 2(ITS1 和 ITS2)以及部分线粒体细胞色素 c 氧化酶亚基 I(cox1)基因序列的结构在单殖吸虫类 Atractolytocestus sagittatus(Kulakovskaya et Akhmerov,1965)(Cestoda: Caryophyllidea)中进行了研究,该寄生虫是鲤鱼(Cyprinus carpio carpio L.)的寄生虫。在这两个核糖体间隔区都观察到了个体内序列多样性。在 ITS1 中,总共产生了 19 个重组克隆,产生了 8 种不同的序列类型(成对序列同一性,99.7-100%),但这些序列类型与典型的发散基因组内 ITS 拷贝(旁系同源物)结构不同。几个单核苷酸突变仅存在于单个克隆中,表现出多态性,但没有观察到短重复基序数量的变化。在 ITS2 中,总共产生了 21 个重组克隆,产生了 10 种不同的序列类型(成对序列同一性,97.5-100%)。它们主要表现为(TCGT)(n)重复的数量不同,导致 ITS2 序列分为两种序列变体,这反映了 ITS 旁系同源物特有的结构。分析的第三个 DNA 区域,线粒体 cox1 基因(669 bp)在所有研究的 A. sagittatus 个体中均完全相同。将 A. sagittatus 的分子数据与入侵性寄生虫普通鲤鱼的 Huronensis 属 Atractolytocestus Anthony,1958 的分子数据进行比较,结果表明,核糖体间隔区(ITS1 中的 81.4-82.5%,ITS2 中的 74.4-75.2%)和线粒体 cox1 的种间差异明显大于种内差异,这证实了在同一鱼类宿主中寄生的两个同类绦虫的有效性。