Lin Rui-Qing, Liu Guo-Hua, Song Hui-Qun, Zhang Yuan, Li Ming-Wei, Zou Feng-Cai, Yuan Zi-Guo, Weng Ya-Biao, Zhu Xing-Quan
State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu Province, PR China.
Mitochondrial DNA. 2012 Jun;23(3):182-6. doi: 10.3109/19401736.2012.668892.
In this study, sequence variation in three mitochondrial DNA regions, namely cytochrome c oxidase subunit (cox1) and NADH dehydrogenase subunits 1 and 4 (nad1 and nad4), between Oesophagostomum dentatum and O. quadrispinulatum isolated from pigs in different geographical origins in Mainland China was examined, and their phylogenetic relationships were reconstructed. A partial of the cox1 (pcox1), nad1, and nad4 genes (pnad1 and pnad4) were amplified separately from individual nodule worms by PCR and were subjected to direct sequencing in order to define sequence variations. While the intraspecific sequence variations within each of the two species were 0.3-5.2% for pcox1, 0-4.9% for pnad1, and 0-7.1% for pnad4, the interspecific sequence differences were significantly higher, being 10.7-13.4% for pcox1, 11-14.6% for pnad1, and 14.9-18% for pnad4, respectively. There were a number of nucleotide positions in the pcox1, pnad1, and pnad4 sequences with no apparent intraspecific variation but distinct interspecific differences among those samples of Oesophagostomum spp. examined, which may be used as genetic makers for the identification and differentiation of the Oesophagostomum spp. Phylogenetic analyses using three inference methods, namely Bayesian inference, maximum likelihood, and maximum parsimony based on the combined sequences of pcox1, pnad1, and pnad4 revealed that the O. dentatum and O. quadrispinulatum form monophyletic groups, respectively. These findings demonstrated clearly the usefulness of the three mitochondrial sequences for studying systematics, population genetic structures, and the molecular ecology of Oesophagostomum spp.
本研究检测了从中国大陆不同地理区域猪体内分离出的齿状食道口线虫和四刺食道口线虫之间三个线粒体DNA区域，即细胞色素c氧化酶亚基（cox1）以及NADH脱氢酶亚基1和4（nad1和nad4）的序列变异，并重建了它们的系统发育关系。通过PCR分别从单个结节线虫中扩增出部分cox1（pcox1）、nad1和nad4基因（pnad1和pnad4），并进行直接测序以确定序列变异。两个物种各自的种内序列变异，pcox1为0.3 - 5.2%，pnad1为0 - 4.9%，pnad4为0 - 7.1%，而种间序列差异明显更高，pcox1分别为10.7 - 13.4%，pnad1为11 - 14.6%，pnad4为14.9 - 18%。在所检测的食道口线虫属样本中，pcox1、pnad1和pnad4序列存在许多核苷酸位置，它们在种内无明显变异，但种间差异明显，这些位置可作为食道口线虫属鉴定和区分的遗传标记。基于pcox1、pnad1和pnad4的联合序列，使用贝叶斯推断、最大似然法和最大简约法这三种推断方法进行系统发育分析，结果显示齿状食道口线虫和四刺食道口线虫分别形成单系类群。这些发现清楚地证明了这三个线粒体序列在研究食道口线虫属的系统学、种群遗传结构和分子生态学方面的有用性。
