Electrophoretic analysis of sequence variability in three mitochondrial DNA regions for ascaridoid parasites of human and animal health significance
✍ Scribed by Ming-Wei Li; Rui-Qing Lin; Hui-Qun Song; Rehana A. Sani; Xiang-Yun Wu; Xing-Quan Zhu
- Publisher
- John Wiley and Sons
- Year
- 2008
- Tongue
- English
- Weight
- 313 KB
- Volume
- 29
- Category
- Article
- ISSN
- 0173-0835
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✦ Synopsis
Abstract
Sequence variability in three mitochondrial DNA (mtDNA) regions, namely cytochrome c oxidase subunit 1 (__cox__1), NADH dehydrogenase subunits 1 and 4 (__nad__1 and __nad__4), among and within Toxocara canis, T. cati, T. malaysiensis, T. vitulorum and Toxascaris leonina from different geographical origins was examined by a mutation‐scanning approach. A portion of the __cox__1 gene (p__cox__1), a portion of the __nad__1 and __nad__4 genes (p__nad__1 and p__nad__4) were amplified separately from individual ascaridoid nematodes by polymerase chain reaction and the amplicons analyzed by single‐strand conformation polymorphism (SSCP). Representative samples displaying sequence variation in SSCP profiles were subjected to sequencing in order to define genetic markers for their specific identification and differentiation. While the intra‐specific sequence variations within each of the five ascaridoid species were 0.2–3.7% for p__cox__1, 0–2.8% for p__nad__1 and 0–2.3% for p__nad__4, the inter‐specific sequence differences were significantly higher, being 7.9–12.9% for p__cox__1, 10.7–21.1% for p__nad__1 and 12.9–21.7% for p__nad__4, respectively. Phylogenetic analyses based on the combined sequences of p__cox__1, p__nad__1 and p__nad__4 revealed that the recently described species T. malaysiensis was more closely related to T. cati than to T. canis. These findings provided mtDNA evidence for the validity of T. malaysiensis and also demonstrated clearly the usefulness and attributes of the mutation‐scanning sequencing approach for studying the population genetic structures of these and other nematodes of socio‐economic importance.