Contracaecum ogmorhini复合种线粒体rrnL基因的多态性

Polymorphism in the mtDNA rrnL gene of Contracaecum ogmorhini complex

本项目应用聚合酶链式反应单链构象多态性(PCR SSCP) 及DNA序列分析的方法, 研究了南半球Contracaecum ogmorhini两个不同种群和北半球C. margolisi一个种群在线粒体核糖体大亚基( rrnL) 基因部分序列的差异及种群遗传关系。结果显示: 南半球C. ogmorhini 两个种群在种群间及种群内的rrnL 序列相似性很高; 而北半球种群与南半球种群的rrnL序列相似性则相对较低, 它们之间rrnL 序列种间遗传差异大于种内遗传变异, 而且存在着可区分两个姊妹种的2个碱基差异。rrnL 序列分析结果支持北半球C. margolisi 相对于南半球C. ogmorhini而言, 的确是一个不同的物种。

This study examined genetic variation among three populations of C.ogmorhini and C.margolisi from different otariid hosts and geographical locations, namely, one C.ogmorhini population from Arctocephalus pusillus pusillus (CoAPP) from South Africa, another from Arctocephalus pusillus doriferus(CoAPD) from Australia, and one C.margolisi population from Zalophus californianus(CoZC) from Pacific Canada, using a polymerase chain reaction (PCR)-based mutation detection approach.A portion of the large subunit of ribosomal RNA (rrnL) gene in mitochondrial DNA (mtDNA) was amplified from individual nematodes by PCR, analysed by single-strand conformation polymorphism (SSCP), and samples displaying variable SSCP profiles were subjected to sequencing.The results showed that polymorphism existed in SSCP profiles of rrnL among different samples of CoAPP, CoAPD and CoZC.The difference in SSCP profiles between CoAPP and CoAPD was not significant, whereas the difference between CoZC and CoAPP/CoAPD was relatively distinct.Sequence analysis revealed that the nucleotide similarity between CoZC and CoAPP/CoAPD was lower than that between CoAPP and CoAPD.Two genetic markers were defined for the differentiation between CoZC and CoAPP/CoAPD.These findings confirmed that C.ogmorhini from the northern and southern hemisphere does represent a complex of two species (i.e., C.ogmorhini and C.margolisi), and rrnL could provide a genetic marker for the specific identification and differentiation of C. ogmorhini complex.