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Syphacia obvelata is a rodent nematode with high prevalence in laboratory mice. In the present study, we examined the genetic variability of S. obvelata from naturally infected laboratory mice in four different provinces, China. Five mitochondrial (mt) DNA regions, namely cytochrome c oxidase subunit 1 (p cox1), cytochrome b (p cytb), large subunit ribosomal RNA (p rrnL) and NADH dehydrogenase subunits 1 and 5 (p nad1 and p nad5), were amplified separately from individual nematodes by PCR, and then sequenced directly. The size of the sequences of p cox1, p cytb, p rrnL, p nad1 and p nad5 was 628 bp, 555 bp, 548 bp, 548 bp and 561 bp, respectively. While the intra-specific sequence variations within S. obvelata were 0-1.0% for p cox1, 0-1.6% for p cytb, 0-2.8% for p rrnL, 0-2.0% for p nad1 and 0-1.8% for p nad5, the inter-specific sequence differences among members of the Oxyuridae were significantly higher, being 14.0-17.5% for p cox1, 27.5-32.9% for p cytb, 35.8-37.2% for p rrnL, 22.2-26.8% for p nad1 and 22.3-25.2% for p nad5, respectively. Phylogenetic analyses based on combined sequences of four mt protein-coding genes, using Bayesian inference (BI), maximum likelihood (ML) and maximum parsimony (MP) methods, indicated that all of the S. obvelata samples grouped together with high statistical support, but samples from the same geographical origin did not always cluster together. These findings demonstrated the existence of low-level intra-specific variation in five mtDNA sequences among S. obvelata isolates from laboratory mice, but no obvious geographical distinction among S. obvelata isolates from laboratory mice in different geographic regions in China. These results provide basic information for further studies of systematics and population genetics of S. obvelata. [ABSTRACT FROM AUTHOR]

Sequence variability in three mitochondrial DNA (mtDNA) regions, namely portions of cytochrome c oxidase subunit 1 (p cox1), NADH dehydrogenase subunit 1 (p nad1) and NADH dehydrogenase subunit 4 (p nad4), for Toxocara canis. Baylisacaris transfuga. Ascaris suum and Parascaris equorum from Canis lupus. Ursus thibetanus. Sus scrofa and Equus burchelli in China were examined. The lengths of the sequences of p cox1, p nad1 and p nad4 were 711 bp, 648 bp and 666 bp, respectively. No intra-species differences were detected in p cox1 for the four examined ascarid species, in p nad1 for T. canis. A. suum and P. equorum, and in p nad4 for B. transfuga and P. equorum. Sequence differences in p nad4 for six roundworm samples of T. canis and P. equorum were 0-0.1% and 0-0.3%, respectively, and were 0-0.3% in p nad1 for six roundworm samples isolate of B. transfuga. The inter-specific sequence differences among four species were 8.7-12.4% for p cox1, 13.9-17.7% for p nad1, and 14.0-25.7% for p nad4. Phylogenetic analyses suggested that the three mtDNA fragments could be used to identify ascarid species in families Ascaridiae and Toxocaridae. [ABSTRACT FROM AUTHOR]