Jun-Feng Gao

The complete mitochondrial genome of Orientobilharzia turkestanicum supports its affinity with African Schistosoma spp.

Orientobilharzia turkestanicum is a blood fluke of many mammals and causes orientobilharziasis that is also a neglected parasitic zoonosis because the cercaria of O. turkestanicum can infect humans and cause cercarial dermatitis. The present study determined the complete sequence of mt genome of O. turkestanicum and revised its phylogenetic position based on mt gene content and arrangement. The complete mtDNA sequence of O. turkestanicum was 14,755 bp in length, which is slightly larger than the mtDNA genomes of three species of the blood flukes, Schistosoma mekongi (14,072 bp), Schistosoma japonicum (14,085 bp) and Schistosoma mansoni (14,415 bp), but smaller than Schistosoma haematobium (15,003 bp) and Schistosoma spindale (16,901 bp). The mt genome of O. turkestanicum contains 12 protein-coding genes, 22 transfer RNA genes and two ribosomal RNA genes, but lacks an atp8 gene, consistent with that of Schistosoma species. The mt genome arrangement of O. turkestanicum contains an AT-rich region and two non-coding regions (NCRs), including long non-coding region (LNR) and short non-coding region (SNR). Phylogenetic analysis based on amino acids sequences showed that O. turkestanicum belonged to the genus Schistosoma, and is phylogenetically closer to the African schistosome group (S. haematobium, S. spindale and S. mansoni) than to the Asian group (S. mekongi and S. japonicum). But the arrangement of mtDNA protein-coding genes for O. turkestanicum is the same as Asian group, and distinct from the African species. Combining content and arrangement of mtDNA for O. turkestanicum, we conclude that O. turkestanicum should be considered a member of the Schistosoma genus, which shares a closer affinity to the African schistosomes than the Asian species, and gene order of mt genome in O. turkestanicum would be considered sympleisiomorphic (perhaps retained from the ancestor).

Seroprevalence of Neospora caninum Infection in Dairy Cattle in Northeastern China

Abstract The seroprevalence of Neospora caninum infection in Chinas northeastern Heilongjiang Province was surveyed between 2007 and 2008. In total, 540 serum samples of dairy cattle from 9 counties were examined for antibodies to N. caninum by enzyme-linked immunosorbent assay (ELISA). The overall seroprevalence of N. caninum in dairy cattle was 13.3% (72/540). The seroprevalence of N. caninum in aborting cows (14.9%) was slightly higher than that in nonaborting cows (10.3%). Dairy cattle with 5 pregnancies had the highest seroprevalence (22.7%). However, there was no apparent association between N. caninum seropositivity and aborting age or number of pregnancies (P > 0.05). There was, however, an apparent association between N. caninum seroprevalence and animal husbandry practices, with the cattle under confinement feeding having significantly lower seroprevalence than the grazing cows (P < 0.05). The results of the present survey indicates that infection with N. caninum in dairy cattle is widespread in Heilongjiang Province, and that it appears to be an important cause of bovine abortion.

Comparative analyses of the complete mitochondrial genomes of the two ruminant hookworms Bunostomum trigonocephalum and Bunostomum phlebotomum

Bunostomum trigonocephalum and Bunostomum phlebotomum are blood-feeding hookworms of sheep and cattle, causing considerable economic losses to the live stock industries. Studying genetic variability within and among hookworm populations is critical to addressing epidemiological and ecological questions. Mitochondrial (mt) DNA is known to provide useful markers for investigations of population genetics of hookworms, but mt genome sequence data are scant. In the present study, the complete mitochondrial DNA (mtDNA) sequences of the sheep and goat hookworm B. trigonocephalum were determined for the first time, and the mt genome of B. phlebotomum from yak in China was also sequenced for comparative analyses of their gene contents and genome organizations. The lengths of mt DNA sequences of B. trigonocephalum sheep isolate, B. trigonocephalum goat isolate and B. phlebotomum China yak isolate were 13,764bp, 13,771bp and 13,803bp in size, respectively. The identity of the mt genomes was 99.7% between B. trigonocephalum sheep isolate and B. trigonocephalum goat isolate. The identity of B. phlebotomum China yak isolate mt genomes was 85.3% with B. trigonocephalum sheep isolate, and 85.2% with B. trigonocephalum goat isolate. All the mt genes of the two hookworms were transcribed in the same direction and gene arrangements were consistent with those of the GA3 type, including 12 protein-coding genes, 2 rRNA genes and 22 tRNA genes, but lacking ATP synthetase subunit 8 gene. The mt genomes of B. trigonocephalum and B. phlebotomum were similar to prefer bases A and T, the contents of A+T are 76.5% (sheep isolate), 76.4% (goat isolate) and 76.9% (China yak isolate), respectively. Phylogenetic relationships reconstructed using concatenated amino acid sequences of 12 protein-coding genes with three methods (maximum likelihood, Bayesian inference and neighbor joining) revealed that the B. trigonocephalum and B. phlebotomum represent distinct but closely-related species. These data provide novel and useful genetic markers for studying the systematics, and population genetics of the two ruminant hookworms.

Complete Mitochondrial genome of an equine intestinal parasite, Triodontophorus brevicauda (Chromadorea: Strongylidae): the first characterization within the genus.

The complete mitochondrial (mt) genome sequence of Triodontophorus brevicauda, an intestinal equine nematode parasite was determined for the first time. The circular T. brevicauda mt genome is 14,305 bp in length and contains 36 genes, of which 12 code for protein, 22 for transfer RNA, and two for ribosomal RNA, and lacks atp8 mtDNA gene. Phylogenetic analysis based on the concatenated amino acid sequence of the 12 protein-coding genes was performed using three different tree-building methods. The Strongyloidea cluster divides into two large branches, and each nematode family included in our study forms an independent clade, though paraphyly confounds the issue at some nodes. T. brevicauda clusters together with Cylicocyclus insignis with high statistical support. The mtDNA data in this study not only provide a new mtDNA resource for phylogeny, but also become a novel and useful genetic marker for further studies on the identification, population genetics, and molecular epidemiology of the genus Triodontophorus in equine.

The complete mitochondrial genome of Metorchis orientalis (Trematoda: Opisthorchiidae): Comparison with other closely related species and phylogenetic implications

Metorchis orientalis (Trematoda: Opisthorchiidae) is an important trematode infecting many animals and humans, causing metorchiasis. In the present study, the complete mitochondrial (mt) genome of M. orientalis was sequenced. The complete mt genome of M. orientalis is 13,834 bp circular DNA molecule and contains 12 protein-coding genes, 22 transfer RNA genes, and two ribosomal RNA genes. The gene content and arrangement of M. orientalis is the same as those of Opisthorchiidae trematodes (Opisthorchis viverrini, Opisthorchis felineus and Clonorchis sinensis), but distinct from Schistosoma spp. Phylogenetic analyses using concatenated amino acid sequences of 12 protein-coding genes with three different computational algorithms (Bayesian inference, maximum likelihood and maximum parsimony) revealed that M. orientalis and O. viverrini represent sister taxa. The mt genome provides a novel genetic marker for further studies of the identification, classification and molecular epidemiology of Opisthorchiidae trematodes, and should have implications for the diagnosis, prevention and control of metorchiasis in animals and humans.

Sequencing and characterization of the complete mitochondrial genome from the pancreatic fluke Eurytrema pancreaticum (Trematoda: Dicrocoeliidae).

The trematode Eurytrema pancreaticum is a parasite of ruminant pancreatic and bile ducts, and also occasionally infects humans, causing eurytremiasis. In spite of it being a common fluke of cattle and sheep in endemic regions, little is known about the genomic resources of the parasite. We sequenced the complete mitochondrial (mt) genome of E. pancreaticum. It is 15,031 bp in size, and encodes 36 genes: 12 protein-coding genes, two ribosomal RNA genes, and 22 transfer RNA genes. The E. pancreaticum mt gene order is the same as that of Dicrocoelium chinensis and Dicrocoelium dendriticum, and all genes are transcribed in the same direction. Phylogenetic analysis based on the concatenated amino acid sequences of 12 protein-coding genes by Bayesian inference shows that E. pancreaticum is closely related to D. chinensis and other members of the family Dicrocoeliidae with strong posterior probability support. The E. pancreaticum mt genome should prove to be a useful resource for comparative mt genomic studies of digenetic trematodes, and will provide a rich source of DNA markers for studies into the systematics, epidemiology, and population genetics of this parasite and other digenean trematodes.

Comparative analyses of the complete mitochondrial genomes of the two murine pinworms Aspiculuris tetraptera and Syphacia obvelata.

Pinworms Aspiculuris tetraptera and Syphacia obvelata are important parasitic nematodes of laboratory mice, rat and other rodents. However, the mitochondrial (mt) genome of these parasites have not been known yet. In the present study, the complete mt genomes of A. tetraptera and S. obvelata were sequenced, which were 13,669 bp and 14,235 bp in size, respectively. Both genomes included 12 protein-coding genes, two rRNA genes, 22 tRNA genes and one non-coding region. The mt genomes of A. tetraptera and S. obvelata preferred bases A and T, with the highest for T and the lowest for C. The mt gene arrangements of the two pinworms were the same as that of the GA8 type. Phylogenetic analysis using mtDNA data revealed that the Bayesian inference (BI) trees contained two big branches: species from Oxyuridomorpha, Rhabditomorpha and Ascaridomorpha formed one branch, and those from Spiruromorpha formed another branch with high statistical support. The two murine pinworms A. tetraptera and S. obvelata have closer relationship than to other pinworms. This study provides a foundation for studying the population genetics, systematics and molecular phylogeny of pinworms.

The complete mitochondrial genome sequence of Drepanidotaenia lanceolata (Cyclophyllidea: Hymenolepididae).

Abstract The complete mitochondrial genome of Drepanidotaenia lanceolata was sequenced. The complete mtDNA sequence is 13 573 bp long and contains 12 protein-coding genes (cox1–3, nad1–6, nad4L, atp6, and cytb), two ribosomal RNA (rRNA) genes, 22 transfer RNA (tRNA) genes, and 2 non-coding regions (NCR). Phylogenetic analysis using three methods (Bayesian inference, maximum parsimony, and maximum likelihood) demonstrates with high statistical support that D. lanceolata is closely related to the genus Hymenolepis. This study reports the first complete mt genome sequence of a representative species of the genus Drepanidotaenia and should provide novel genetic data for further studies of the taxonomy, systematics, and population genetics of these and other related cestodes of socio-economic significance.