title: Using the small subunit of nuclear ribosomal DNA to reveal the phylogenetic position of the plerocercoid larvae of Spirometra tapeworms.
abstract: Although medically important, the systematics of Spirometra and the taxonomic position of S. erinaceieuropaei remain unclear. In this study, the 18S rDNA gene of S. erinaceieuropaei sparganum from naturally infected frogs caught in 14 geographical locations of China was sequenced. In addition, all available 18S sequences of the family Diphyllobothriidae in the Genbank database were included to reconstruct the phylogeny of diphyllobothriid tapeworms. The secondary structure model of the 18S rDNA was also predicated to further explore the sequence variation. Phylogenetic analyses were performed using maximum parsimony (MP), maximum likelihood (ML) and Bayesian inference (BI) methods. The intraspecific divergences of 18S rDNA in Chinese sparganum isolates ranged from 0.0 to 0.4%. Regions of V2, V4 and V7 were the most variable regions in the secondary structure of 18S rDNA. With the exception of genera Duthiersia and Probothriocephalus, other genera (i.e., Adenocephalus, Diphyllobothrium, Diplogonoporus, Duthiersia, Schistocephalus and Spirometra) selected in the Diphyllobothriidae shared similar topologies of V2, V4 and V7 structures. The topology of generated phylogenetic trees revealed close relationships among Adenocephalus, Digramma, Diphyllobothrium, Diplogonoporus, Ligula, Sparganum and Spirometra. The exact phylogenetic position of Spirometra species should be further analyzed with more sampling and more useful molecular markers.
authors.affiliation: Department of Parasitology, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou 450001, China.
authors.forename: Xi
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Department of Parasitology, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou 450001, China.
authors.forename: Jiang Yang
authors.initials: JY
authors.lastname: Duan
authors.affiliation: Department of Parasitology, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou 450001, China. Electronic address: wangzq@zzu.edu.cn.
authors.forename: Zhong Quan
authors.initials: ZQ
authors.lastname: Wang
authors.affiliation: Department of Parasitology, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou 450001, China.
authors.forename: Peng
authors.initials: P
authors.lastname: Jiang
authors.affiliation: Department of Parasitology, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou 450001, China.
authors.forename: Ruo Dan
authors.initials: RD
authors.lastname: Liu
authors.affiliation: Department of Parasitology, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou 450001, China. Electronic address: cuij@zzu.edu.cn.
authors.forename: Jing
authors.initials: J
authors.lastname: Cui
mesh_terms: D000818:Animals; D001499:Bayes Theorem; D002589:Cestoda / Q000145:classification / Q000235:genetics; D002681:China; D004275:DNA, Ribosomal / Q000737:chemistry*; D016013:Likelihood Functions; D009690:Nucleic Acid Conformation; D010802:Phylogeny; D012337:RNA, Ribosomal, 18S / Q000235:genetics*; D011898:Ranidae; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D013032:Sparganum / Q000145:classification / Q000235:genetics; D013146:Spirometra / Q000145:classification* / Q000235:genetics
chemical_list: D004275:DNA, Ribosomal; D012337:RNA, Ribosomal, 18S
keywords: 18S rDNA; Diphyllobothriidae; Phylogeny; Secondary structure; Spirometra erinaceieuropaei