Characterization Of The Complete Mitochondrial Genomes Of Nematodes Ostertagia Trifurcata And Trichuris Skrjabini And Their Phylogenetic Implications

Gastrointestinal parasites cause major economic losses to livestock industry all over the world.Among those parasites,Ostertagia spp.which is a reddish brown worm and present in the abomasum of ruminants is a major cause of parasitic gastritis(ostertagiosis)worldwide particularly in temperate climates.Helminthiases,a neglected tropical disease has accounted for devastating effect on human health.According to an estimate,helminths transmitted from soil(geo-helminths),most commonly whipworms(Trichuris),hookworms(Ancyclostoma and Necator spp.),and roundworm(Ascaris),prevailing in less privileged regions of the world infects about one billion people.Mitochondria are a subcellular organelle with important biochemical functions.This organelle is the powerhouse of the eukaryotic cell.The mitochondrial(mt)genome is located within the organelle,independent of nuclear genome but having a closer relationship to each other.The complete mitochondrial(mt)genome of Ostertagia trifurcata,a parasitic nematode of small ruminants,has been sequenced and its phylogenetic relationship with selected members from the superfamily Trichostrongyloidea was investigated on the basis of deduced datasets of mt amino acid sequences.The entire mt genome of Ostertagia trifurcata is circular and 14,151 bp in length.It consists of a total of 36 genes comprising 12 genes coding for proteins(PCGs),2 genes for ribosomal RNA(rRNA),22 transfer RNA(tRNA)genes and 2 non-coding regions,since all genes are transcribed in the same direction.The phylogenetic analysis based on the concatenated datasets of predicted amino acid sequences of the 12 protein coding genes supported monophylies of the Haemonchidae,Dictyocaulidae and Molineidae families,but rejected monophylies of the Trichostrongylidae family.The complete characterization and provision of the mtDNA sequence of Ostertagia trifurcata provides novel genetic markers for molecular epidemiological investigations,systematics,diagnostics and population genetics of Ostertagia trifurcata and its correspondents.Whipworms(Trichuris spp.)have been described with somewhat slender range regarding its biometrical and morphological features.Insufficient discrimination among its closely related species also marks its importance.The complete mitochondrial(mt)genome of Trichuris skrjabini has been determined in the present study and subsequently compared with the closely related species by phylogenetic analysis based on concatenated datasets of mt amino acid sequences.The whole mt genome of Trichuris skrjabini is circular and 14.011 bp in length.It consists a total of 37 genes including 13 protein coding genes(PCGs),2 ribosomal RNA(rRNA)genes,22 transfer RNA(tRNAs)genes and 2 non-coding regions.The gene arrangement and contents were consistent to other members of Trichuridae family including Trichuris suis,Trichuris trichuira,Trichuris ovis and Trichuris discolor.Phylogenetic analysis based on datasets of concatenated datasets of amino acids of the 12 PCGs predicted the distinctiveness of Trichuris skrjabini as compared to other members of Trichuridae family.Overall,our study supports the hypothesis that Trichuris skrjabini is a distinct species.The provision of molecular data of whole mt genome of Trichuris skrjabini delivers novel genetic markers for future studies of diagnostics,systematics,population genetics and molecular epidemiology of T.skrjabini.