Mitochondrial Genome Analysis Of Five Intestinal Fluke Species Of Wood Frog

Wood frogs,as amphibians,play a vital role in the connect of water and land environment in ecosystems,and is one of the most essential components of the biological community.Wood frogs breeding not only ensures human food,medicine and research applications,but also protects wild resources,parasite infection is one of the important factors affecting the development of wood frogs breeding.Now information on these trematodes is limited to the morphology and prevalence,however the complete mt DNA,genetic evolution,phylogenetic relationship of thesetrematodes are relatively rare.Thus,the objective of our study was to amplify the complete mt genome sequences including Diplodiscus japonicus,Diplodiscus mehari,Pleurogenoides japonicus,Glypthelmins jilinenisis and Dolichosaccus huabeiensis,and do comparision and analysis of these mt genomes.Phylogenetic analyses using concatenated amino acid sequences of 12 protein-coding genes by BI and ML methods to explore the taxonomic status of five trematodes and the relationship of 7 orders,26 families and 86 species of trematodes.The complete circular mt sequence of D.japonicus,D.mehari,P.japonicus,G.jilinenisis and D.huabeiensis were 14 210 bp,14 179 bp,15 044 bp,14 522 bpand 14 313 bp in length,respectively.Both mt genomes comprised 36 functional subunits,consisting of 12 protein-coding genes,two ribosomal RNA genes and 22 transferRNA genes,were transcribed in the same direction,and the gene arrangements were identical to those of trematodes.Five trematodes all have one non-coding region.Tandem repeats were found in D.japonicus,P.japonicus,G.jilinenisis and D.huabeiensis,except for D.mehari.The A+T content of complete mitochondrial genome are 64.99%,58.73%,69.00%,66.63% and 62.63%,respectively.The results of homology analysis,sliding windows analysis and non-synonymous/synonymous mutation rates showed that the cox1 gene was the most conserved gene in Paramphistomoidea,Microphalloidea and Plagiorchioidea.Phylogenetic analyses revealed that other orders or suborders clustered together except Echinostomata,Strigeidida,and Xiphidiata.In Paramphistomoidea,all trematodes are clustered together;Glypthelmins,Dolichosaccus and Orientocreadium are clustered together on the Plagiorchioidea branch;Pleurogenoides and Prosthogonimus are clustered together,more closely relationship.In conclusion,the complete mitochondrial genome sequence of D.japonicus,D.mehari,P.japonicus,G.jilinenisis and D.huabeiensis were completed for the first time.Comparative and phylogenetic analysis shows the flukes parasitic in amphibians and ruminants with two monophyletic.It is suggested that the genetic relationship in Paramphistomoidea is closely related to the host species.This study not only supplemented the data of the mitochondrial genome database of trematodes,but also laid a foundation for the genetic variation and molecular classification evolution of trematodes.