Li Jingjing, Liao Xianghua
Ichthyology Laboratory, Department of Biology, Zhongshan University, Guangzhou 510275, People's Republic of China.
J Parasitol. 2003 Aug;89(4):792-9. doi: 10.1645/GE-3078.
The traditional classification of the ligulid tapeworms into 2 genera, Ligula Bloch, 1782 and Digramma Cholodkovsky, 1914, remains controversial. Molecular data of sequences for the 5' end of the nuclear 28S ribosomal ribonucleic acid (rRNA) gene, the mitochondrial cytochrome c oxidase subunit I (COI) gene, and the nicotinamide adenine dinucleotide dehydrogenase subunit 1 (ND1) gene, as well as the first internal transcribed spacer (ITS1) of the nuclear ribosomal deoxyribonucleic acid (DNA), were used to characterize Digramma and to investigate its relationship with Ligula. Digramma spp. exhibited identical sequences with Ligula intestinalis both in the 28S rRNA and the COI gene and differed from L. intestinalis by 0.7% in the ITS1 region and 7.4% in the ND1 gene, respectively. A high degree of genetic conservation within 28S ribosomal DNA, COI, ITS1, and even ND1 genes, was found in Ligula and Digramma. The low genetic divergence in the 4 genes between Ligula and Digramma indicates that Digramma is probably not an independent genus. Therefore, it is proposed that Ligula and Digramma should be considered as 2 species within the genus Ligula and the tapeworms of Digramma collected from diverse localities in China belong to the same species. The present study also suggests that ITS1 and ND1 sequences can act as useful genetic markers to distinguish Ligula and Digramma.
将舌状绦虫传统分类为2个属，即1782年的舌状属（Ligula Bloch）和1914年的双型属（Digramma Cholodkovsky），仍然存在争议。利用核糖体核糖核酸（rRNA）基因核28S 5′端、线粒体细胞色素c氧化酶亚基I（COI）基因、烟酰胺腺嘌呤二核苷酸脱氢酶亚基1（ND1）基因的序列分子数据，以及核糖体脱氧核糖核酸（DNA）的第一个内部转录间隔区（ITS1），对双型属进行特征描述，并研究其与舌状属的关系。双型属物种在28S rRNA和COI基因中与肠舌状绦虫（Ligula intestinalis）表现出相同的序列，在ITS1区域与肠舌状绦虫分别相差0.7%，在ND1基因中相差7.4%。在舌状属和双型属中发现28S核糖体DNA、COI、ITS1甚至ND1基因内都有高度的遗传保守性。舌状属和双型属之间4个基因的低遗传差异表明双型属可能不是一个独立的属。因此，建议将舌状属和双型属视为舌状属内的2个物种，并且从中国不同地区采集的双型属绦虫属于同一物种。本研究还表明，ITS1和ND1序列可作为区分舌状属和双型属的有用遗传标记。
