| Pinworms, including Aspicularis tetraptera and Syphacia obvelata are important parasiticnematodes which inhabit in colon and cecum of laboratory mice, rat and other rodents. Althoughmice pinworm infection usually has no obvious clinical symptoms, serious infections causingrectal prolapse, intussusception, enteritis and weight loss. Also the mice as importantexperimental animals, the enterobiasis would influence scientificity and accuracy of animalexperiments by generating the humoral and cellular immune response. So the present study, wewill examine phylogenetic relationship, genetic variability and mitochondrial (mt) genome ofS.obvelata and A.tetraptera, having important implications for controlling the disease.Firstly, genetic variations within mitochondrial genes of A. tetraptera and S.obvelata indifferent provinces were examined. Using polymerase chain reaction (PCR), five partial mtgenes, namely cytochrome c oxidase subunit1(pcox1), NADH dehydrogenase subunit1(pnad1)and5(pnad5), large subunit ribosomal RNA (prrnL)(only Syphacia obvelata) and cytochrome b(pcytb) were amplified separately from individual pinworms, which A. tetraptera worms wereisolated from laboratory mice in Heilongjiang, Jiangsu, Gansu and Yunnan, and S.obvelatasamples were collected from Jilin, Guangdong, Beijing and Gansu province. The result showedthat minimum sequence variations of intra-(0-0.5%,0-1.0%) and inter-(13.7-17.0%,14.0-17.5%) specific of A. tetraptera and S.obvelata were in cox1, the maximum sequence variationsof intra-(0-1.8%) and inter-(24.5-34.7%) specific of A. tetraptera were in nad1and cytb, andthe maximum sequence variations of intra-(0-2.8%) and inter-(35.8-37.2%) specific ofS.obvelata were within rrnL. The nucleotide variation were related mainly to the changes at thethird codon position. These results revealed low-level intra-specific variation in mtDNAsequences among A. tetraptera and S.obvelata isolates from different geographic regions.Phylogenetic analyses were performed using three different inference methods [Bayesianinference (BI), maximum likelihood (ML) and maximum parsimony (MP)], and the resultshowed A. tetraptera and S.obvelata were in one clade, indicating the genetic relationship of A.tetraptera and S.obvelata from mice was very close.Sencondly, the study was to amplify, sequence and analyses of mt genomes of A. tetrapteraand S.obvelata. The phylogenetic trees were also re-constructed based on the protein-codinggene sequences of mt genomes to study the phylogenetic relationships between the A. tetraptera,S.obvelata and other members of Oxyuridae. The complete mt genome sequences of A.tetraptera and S.obvelata were13700bp and14235bp, respectively. Both including12protein-coding genes,2rRNA genes,22tRNA genes and1non-coding. The mt genomes of A. tetraptera and S.obvelata were simlar to bases. The mt gene arrangements of two pinworms belonged tothe GA8type.To determine the phylogenetic relationship of the A. tetraptera and S.obvelata samples withmembers of Oxyuridae, the combined amino acid sequences of the12protein-coding genesequences were analyzed using BI, ML and MP methods, and similar tree topologies, with smalldifferences in bootstrap values. Using Trichuris suis as the outgroup, this tree revealedStrongylata, Ascaridida, Filariata, Spirurida and Oxyurida became independent branches,respectively. Within the family of Oxyurata, A. tetraptera and S.obvelata were close thanEnterobius vermicularis and Wellcomia siamensis. These results were consistent with those oftraditional method, suggesting that the complete mt genome sequence was a reliable geneticmarker for phylogenetic studies.In conclusion, the present study revealed sequence variability based on partial mt DNA genesequences of A. tetraptera and S.obvelata isolated from different geographic regions, with lowintra-specific variations but higher inter-specific differences in these mt genes. The complete mtgenome sequences were firstly obtained for A. tetraptera and S.obvelata. Phylogenetic treesbased on mt genome sequences clearly indicated genetic relationships of A. tetraptera andS.obvelata and other nematodes. This study provides a foundation for studying the populationgentics, systematics and ecology of other pinworms and parasites. |
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