Determination Of Complete Mitochondrial Genome Of Hymenolepis Nana And Studies Of Sequence Variations In Mitochondrial DNA

hymenolepis nana, commonly is the most common tapeworm of humans and rodents, and can cause hymenolepiasis. Although this zoonotic tapeworm is of socio-economic significance in many counties of the world, its genetics, systematic,epidemiology and biology are poorly understood. Hymenolepiasis as a neglect zoonotic parasitic disease needs more attention.The present study examined sequence diversity in three mitochondrial(mt) genes namely NADH dehydrogenase subunits 5(nad5), small subunit ribosomal RNA(rrn S) and ATPase subunit 6(atp6) of H. nana from mice in different geographical regions of China. A part of nad5, rrn S and atp6 were amplified separately from individual H. nana using polymerase chain reaction(PCR) and then sequenced. The sequences of pnad5, rrn S and atp6 were 710 bp, 704 ~ 711 bp and 516 bp in length, respectively. The A+T contents of the sequences were 70.1% ~ 73.5%(pnad5), 70.1% ~ 71.7%(rrn S) and 76.6% ~ 77.9%(atp6).Sequences variation was 0 ~ 1.4% for atp6, 0 ~ 1.7% for rrn S and 0 ~ 0.7% for pnad5. The inter-specific sequence differences between H. nana and Hymenolepis diminuta were significantly higher, which was 16.1% ~ 17.6%(rrn S), 26.5% ~ 27.1%(atp6) and 31.6% ~31.7%(pnad5).Phylogenetic analysis based on the combined three sequences was conduced using maximum parsimony(MP) method.The isolates from zhangjiankou were grouped together,the samples from the same geographical regions(except for zhangjiakou) did not appear genetically more closer than to samples from other geographical locations,suggesting that there were no obvious geographical distinction in the H. nana based on the sequences.Phylogenetic analyses provided some support that H. nana is a species complex or ’cryptic’ species.Complete mitochondrial(mt) genome of H. nana. was sequenced and characterized The mt genome was 13,764 bp in size and encodes of 36 genes, including 12 protein-coding, 2ribosomal RNA and 22 transfer RNA genes. All genes were transcribed in the same direction. The gene order and genome content was completely identical with its congener H.diminuta. Phylogenetic analyses based on concatenated amino acid sequences of 12protein-coding genes by Bayesian inference, maximum likelihood and maximum parsimony showed the division of class Cestoda into two orders, supported the monophylies of the both orders Cyclophyllidea and Pseudophyllidea. Analyses of mt genome sequences also supported the monophylies of the three families Taeniidae,Hymenolepididae and Diphyllobothriidae.This novel mt genome provided useful genetic markers for studying the molecular epidemiology, systematic and population genetics of the dwarf tapeworm and should have implications for the diagnosis, prevention and control of hymenolepiasis in humans.