Nehaz Muhammad1, Mian Sayed Khan2, Vasyl V Tkach3, Hanif Ullah4, Muhammad Ehsan1, Jun Ma5, Xing-Quan Zhu6,7. 1. State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu, 730046, People's Republic of China. 2. Department of Zoology, University of Swabi, Swabi, Khyber Pakhtunkhwa, Pakistan. 3. Department of Biology, University of North Dakota, Grand Forks, ND, 58202-9019, USA. vasyl.tkach@und.edu. 4. Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Key Laboratory of Animal Parasitology, Shanghai, 20041, People's Republic of China. 5. State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu, 730046, People's Republic of China. majun@caas.cn. 6. State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu, 730046, People's Republic of China. xingquanzhu1@hotmail.com. 7. College of Veterinary Medicine, Shanxi Agricultural University, Taigu, 030801, Shanxi, People's Republic of China. xingquanzhu1@hotmail.com.
Abstract
BACKGROUND: The Eucotylidae Cohn, 1904 (Superfamily: Microphalloidea), is a family of digeneans parasitic in kidneys of birds as adults. The group is characterized by the high level of morphological similarities among genera and unclear systematic value of morphological characters traditionally used for their differentiation. In the present study, we sequenced the complete or nearly complete mitogenomes (mt genome) of two eucotylids representing the genera Tamerlania (T. zarudnyi) and Tanaisia (Tanaisia sp.). They represent the first sequenced mt genomes of any member of the superfamily Microphalloidea. METHODS: A comparative mitogenomic analysis of the two newly sequenced eucotylids was conducted for the investigation of mitochondrial gene arrangement, contents and genetic distance. Phylogenetic position of the family Eucotylidae within the order Plagiorchiida was examined using nucleotide sequences of mitochondrial protein-coding genes (PCGs) plus RNAs using maximum likelihood (ML) and Bayesian inference (BI) methods. BI phylogeny based on concatenated amino acids sequences of PCGs was also conducted to determine possible effects of silent mutations. RESULTS: The complete mt genome of T. zarudnyi was 16,188 bp and the nearly complete mt genome of Tanaisia sp. was 13,953 bp in length. A long string of additional amino acids (about 123 aa) at the 5' end of the cox1 gene in both studied eucotylid mt genomes has resulted in the cox1 gene of eucotylids being longer than in all previously sequenced digeneans. The rrnL gene was also longer than previously reported in any digenean mitogenome sequenced so far. The TΨC and DHU loops of the tRNAs varied greatly between the two eucotylids while the anticodon loop was highly conserved. Phylogenetic analyses based on mtDNA nucleotide and amino acids sequences (as a separate set) positioned eucotylids as a sister group to all remaining members of the order Plagiorchiida. Both ML and BI phylogenies revealed the paraphyletic nature of the superfamily Gorgoderoidea and the suborder Xiphidiata. CONCLUSIONS: The average sequence identity, combined nucleotide diversity and Kimura-2 parameter distances between the two eucotylid mitogenomes demonstrated that atp6, nad5, nad4L and nad6 genes are better markers than the traditionally used cox1 or nad1 for the species differentiation and population-level studies of eucotylids because of their higher variability. The position of the Dicrocoeliidae and Eucotylidae outside the clade uniting other xiphidiatan trematodes strengthened the argument for the need for re-evaluation of the taxonomic content of the Xiphidiata.
BACKGROUND: The Eucotylidae Cohn, 1904 (Superfamily: Microphalloidea), is a family of digeneans parasitic in kidneys of birds as adults. The group is characterized by the high level of morphological similarities among genera and unclear systematic value of morphological characters traditionally used for their differentiation. In the present study, we sequenced the complete or nearly complete mitogenomes (mt genome) of two eucotylids representing the genera Tamerlania (T. zarudnyi) and Tanaisia (Tanaisia sp.). They represent the first sequenced mt genomes of any member of the superfamily Microphalloidea. METHODS: A comparative mitogenomic analysis of the two newly sequenced eucotylids was conducted for the investigation of mitochondrial gene arrangement, contents and genetic distance. Phylogenetic position of the family Eucotylidae within the order Plagiorchiida was examined using nucleotide sequences of mitochondrial protein-coding genes (PCGs) plus RNAs using maximum likelihood (ML) and Bayesian inference (BI) methods. BI phylogeny based on concatenated amino acids sequences of PCGs was also conducted to determine possible effects of silent mutations. RESULTS: The complete mt genome of T. zarudnyi was 16,188 bp and the nearly complete mt genome of Tanaisia sp. was 13,953 bp in length. A long string of additional amino acids (about 123 aa) at the 5' end of the cox1 gene in both studied eucotylid mt genomes has resulted in the cox1 gene of eucotylids being longer than in all previously sequenced digeneans. The rrnL gene was also longer than previously reported in any digenean mitogenome sequenced so far. The TΨC and DHU loops of the tRNAs varied greatly between the two eucotylids while the anticodon loop was highly conserved. Phylogenetic analyses based on mtDNA nucleotide and amino acids sequences (as a separate set) positioned eucotylids as a sister group to all remaining members of the order Plagiorchiida. Both ML and BI phylogenies revealed the paraphyletic nature of the superfamily Gorgoderoidea and the suborder Xiphidiata. CONCLUSIONS: The average sequence identity, combined nucleotide diversity and Kimura-2 parameter distances between the two eucotylid mitogenomes demonstrated that atp6, nad5, nad4L and nad6 genes are better markers than the traditionally used cox1 or nad1 for the species differentiation and population-level studies of eucotylids because of their higher variability. The position of the Dicrocoeliidae and Eucotylidae outside the clade uniting other xiphidiatan trematodes strengthened the argument for the need for re-evaluation of the taxonomic content of the Xiphidiata.
Authors: Sean A Locke; Alex Van Dam; Monica Caffara; Hudson Alves Pinto; Danimar López-Hernández; Christopher A Blanar Journal: Int J Parasitol Date: 2018-10-19 Impact factor: 3.981