Sequence variability in four mitochondrial genes among pinworm Aspicularis tetraptera isolates from laboratory mice in four provinces, China.

This research aimed at exploring sequence variability in four mitochondrial (mt) genes, namely, cytochrome c oxidase subunit 1 ( cox1), cytochrome b ( cytb) and NADH dehydrogenase subunits 1 and 5 ( nad1 and nad5), among pinworm Aspicularis tetraptera isolates from laboratory mice in four different provinces, China. A part of the cox1 (p cox1), cytb (p cytb), nad1 and nad5 genes (p nad1 and p nad5) were amplified separately from individual pinworms by polymerase chain reaction (PCR) and sequenced to determine sequence variations and examine their phylogenetic relationships. Herein, the intra-specific sequence variations within A. tetraptera were 0-0.5% for p cox1, 0-1.4% for p cytb, 0-1.8% for p nad1 and 0-1.7% for p nad5, respectively. In contrast, the inter-specific sequence differences among members of the Oxyuridae were significantly higher, being 13.7-17.0% for p cox1, 24.5-34.7% for p cytb, 26.6-29.6% for p nad1 and 24.4-25.5% for p nad5, respectively. Three methods, namely, Bayesian inference (BI), maximum likelihood (ML) and maximum parsimony (MP), were used for phylogenetic analyses based on the combined sequences of the four mt gene sequences, and the results indicated that all A. tetraptera samples form monophyletic groups, but samples from the same geographical origin did not always cluster together. This study demonstrated the existence of low-level intra-specific variation in four mtDNA sequences among A. tetraptera isolates from laboratory mice in different geographic regions in China, indicating no obvious geographical distinction among A. tetraptera isolates in China. These findings have important implications for studying systematics, molecular epidemiology and population genetics of A. tetraptera. [ABSTRACT FROM AUTHOR]