Comparison And Phylogenetic Analyses Of Complete Mitochondrial Genomes Of Three Trematodes In Duck

Infection of trematodes are serious harmful to duck.At present,most of the studies on trematodes in duck focus on morphology,epidemiology,pathogen diagnosis and comprehensive control,but few reports on mitochondrial genome and its relationship.The present study,for the first time,and presents the complete Echinostoma miyagawai,Tracheophilus cymbius and Amphimerus anatis mitochondrial genome.A comparative analysis of closely related speciesis is presented,then the reconstructed phylogenetic relationship of them with other trematodes.The the mitochondrial gene of three trematodes were amplified by PCR.Phylogenetic analyses using concatenated amino acid sequences of 12 protein-coding genes by MP,BI and ML methods to explore the relationship of the three trematodes and other trematodes.The mt genome of E.miyagawai,T.cymbius and A.anatis was 14 416 bp,13 733 bp and 14 588 bp,respectively.There are 36 genes in mitochondrial gene,which contains 12 protein-coding genes,22 transfer RNA genes,two ribosomal RNA genes,and one or two non-coding region.E.miyagawai and T.cymbius has one non-coding region.A.anatis has two non-coding region.All E.miyagawai,T.cymbius and A.anatis genes are transcribed in the same direction.The A+T content of complete E.miyagawai,T.cymbius and A.anatis mitochondrial genome are 65.29%,62.80% and 59.80%,respectively.The whole E.miyagawai mitochondrial sequence is most similar to Echinostoma caproni and sequence similarity is 88.5% at the nucleotide level.The whole T.cymbius mitochondrial sequence is most similar to Echinochasmus japonicus and sequence similarity is76.4%.The whole A.anatis mitochondrial sequence is most similar to Opisthorchis felineus and Metorchis orientalis and sequence similarity is 83.6%.The Echinostomata clade contains three families,Echinostomatidae,Cyclocoelidae,and Fasciolidae.All of the Echinostomatidae species cluster together within the Echinostomatidae clade,except Es.hortense.Es.hortense clusters with the five Fasciola species used in our study.Our results support the suggestion that the subfamily Echinochasminae should be elevated to the family Echinochasmidae.A.anatis cluster together with other Opisthorchiidae trematodes in a clade.The relationship between E.miyagawai and T.cymbius was closer than A.anatis.In this study,the complete mitochondrial genome sequence of E.miyagawai,T.cymbius and A.anatis were completed for the first time.It not only supplemented the data of the mitochondrial genome database of trematode,but also laid a foundation for the genetic variation and molecular classification evolution of the three trematode.