Complete sequence and structure of the mitochondrial genome of the human tapeworm, Taenia asiatica (Platyhelminthes; Cestoda).
ABSTRACT The complete Taenia asiatica mitochondrial genome was amplified by long extension polymerase chain reaction (long PCR) to yield overlapping fragments that were then completely sequenced. The whole mitochondrial genome was 13 703 bp long and contained 12 protein-encoding, 2 ribosomal RNA (small and large subunits), 22 transfer RNA genes and a short non-coding region. Thus, its gene contents are like those typically found in metazoan animal mitochondrial genomes (apart from the absence of atp8). All the genes were transcribed from the same strand. The 3' end 34 bp region of nad4L overlapped with the 5' end portion of nad4. The tRNA genes were 61-69 bp long, and the secondary structures of 18 tRNAs had typical clover-leaf shapes with paired DHU arms. However, trnC, trnS1, trnS2 and trnR had unpaired DHU arms that were 7-12 bp in length. The tRNAs that transferred serine lacked a DHU arm, as is also observed in a number of parasitic platyhelminths and metazoans. However, the trematode trnRs have paired DHU arms. The T. asiatica mtDNA non-coding region was like that in other cestodes since it was composed of a short non-coding region of 72 nucleotides and a long non-coding region of 176 nucleotides separated by a trnL1/, trnS2/, trnL2/, trnR/, nad5 gene cluster. The sequences of the cox1 genes between T. asiatica and T. saginata differ by 4.6%, while the T. asiatica cob gene differs by 4.1% and 12.9% from the cob genes of T. saginata and T. solium, respectively. In conclusion, the T. asiatica mitocondrial genome should provide a resource for comparative mitochondrial genomics and systematic studies of parasitic cestodes.
Article: The complete mitochondrial DNA sequence of the monogenean Gyrodactylus thymalli (Platyhelminthes: Monogenea), a parasite of grayling (Thymallus thymallus).[show abstract] [hide abstract]
ABSTRACT: We present the complete mitochondrial (mt) genome of Gyrodactylus thymalli, a monogenean ectoparasite on grayling (Thymallus thymallus). The circular genome is 14788 bp in size and includes all 35 genes recognized from other flatworm mt genomes. The overall A+T content of the mt genome is 62.8%. Twenty regions of non-coding DNA ranging from 1 to 111 bp in length were identified in addition to 2 highly conserved large non-coding regions 799 bp and 767 bp in size. Compared to the recently described mt DNA of the closely related G. salaris from Atlantic salmon from Signaldalselva, Norway, the mitochondrial genome of G. thymalli from Hnilec, Slovakia, differs on average by 2.2%.Molecular and Biochemical Parasitology 09/2007; 154(2):190-4. · 2.55 Impact Factor
Article: Complete mitochondrial genomes of Taenia multiceps, T. hydatigena and T. pisiformis: additional molecular markers for a tapeworm genus of human and animal health significance.[show abstract] [hide abstract]
ABSTRACT: Mitochondrial genomes provide a rich source of molecular variation of proven and widespread utility in molecular ecology, population genetics and evolutionary biology. The tapeworm genus Taenia includes a diversity of tapeworm parasites of significant human and veterinary importance. Here we add complete sequences of the mt genomes of T. multiceps, T. hydatigena and T. pisiformis, to a data set of 4 published mtDNAs in the same genus. Seven complete mt genomes of Taenia species are used to compare and contrast variation within and between genomes in the genus, to estimate a phylogeny for the genus, and to develop novel molecular markers as part of an extended mitochondrial toolkit. The complete circular mtDNAs of T. multiceps, T. hydatigena and T. pisiformis were 13,693, 13,492 and 13,387 bp in size respectively, comprising the usual complement of flatworm genes. Start and stop codons of protein coding genes included those found commonly amongst other platyhelminth mt genomes, but the much rarer initiation codon GTT was inferred for the gene atp6 in T. pisiformis. Phylogenetic analysis of mtDNAs offered novel estimates of the interrelationships of Taenia. Sliding window analyses showed nad6, nad5, atp6, nad3 and nad2 are amongst the most variable of genes per unit length, with the highest peaks in nucleotide diversity found in nad5. New primer pairs capable of amplifying fragments of variable DNA in nad1, rrnS and nad5 genes were designed in silico and tested as possible alternatives to existing mitochondrial markers for Taenia. With the availability of complete mtDNAs of 7 Taenia species, we have shown that analysis of amino acids provides a robust estimate of phylogeny for the genus that differs markedly from morphological estimates or those using partial genes; with implications for understanding the evolutionary radiation of important Taenia. Full alignment of the nucleotides of Taenia mtDNAs and sliding window analysis suggests numerous alternative gene regions are likely to capture greater nucleotide variation than those currently pursued as molecular markers. New PCR primers developed from a comparative mitogenomic analysis of Taenia species, extend the use of mitochondrial markers for molecular ecology, population genetics and diagnostics.BMC Genomics 01/2010; 11:447. · 4.07 Impact Factor
Article: What is Asian Taenia?[show abstract] [hide abstract]
ABSTRACT: Asian Taenia is a human tapeworm which was first recognized in Taiwan aborigines and subsequently from Asian countries: Korea, Indonesia, Vietnam, and China. It was originally described as T. asiatica Eom and Rim, 1993 based on the morphology in its adult and larval stage. A taxonomic disagreement on whether it is species or subspecies level is mainly due to the morphological similarity of this tapeworm with T. saginata, but a sympatric distribution of these two tapeworms is also known in China. The life cycle is quite distinct from T. saginata in using the pig as intermediate host and parasitizing visceral organs such as liver, lung and omentum. A long unresolved question in Asian countries concerns the inconsistency between worm ratio and the food preferences was clarified with this viscerotropic tapeworm. Molecular biological differentiation is possible with DNA techniques and a complete genome of mtDNA was sequenced recently which may provide a resource for comparative mitochondrial genomics and systematic studies of parasitic cestodes. This is a young parasite discovered most recently with many research questions yet to be clarified.Parasitology International 02/2006; 55 Suppl:S137-41. · 2.13 Impact Factor