片形吸虫第一内转录间隔区DNA多态性的研究

以不同地区的片形吸虫虫株为研究对象 ,经PCR扩增出了ITS 1部分基因片段 ,采用单链构象多态性 (SSCP)方法 ,并结合序列分析研究了不同地区片形吸虫ITS 1DNA的多态性。不同地区的样品经SSCP分析 ,显示 3种带型 ,第 1种为大片形吸虫的带型 ,第 2种为肝片形吸虫的带型 ,第 3种为 2种带形的混合带型。广西区样品和大部分贵州省样品属于大片形吸虫带型 ;四川省、黑龙江省和部分贵州省样品为混合带型 ;南京市和甘肃省样品为肝片形吸虫带型或混合带型。测序结果表明 ,根据ITS 1基因的序列变异位点可区分 2种片形吸虫 ;表现为混合带型的样品在变异位点具有多态性。本研究结果显示 ,ITS 1片段可作为遗传标记用以区分大片形吸虫和肝片形吸虫 ,同时也证实 ,在我国除了这 2种片形吸虫外 ,还可能存在着“中间型”的片形吸虫

DNA polymorphism in first internal transcribed spacer (ITS-1) rDNA of Fasciola from Mainland China

The objective of the present study was to examine the DNA polymorphism in the first (internal) transcribed spacers (ITS-1) ribosomal DNA (rDNA) of Fasciola from different host species and geographical locations in China. The partial ITS-1 was amplified by PCR from individual Fasciola and analysed by single-strand conformation polymorphism (SSCP). The results showed that all Fasciola could be classified into three groups:F. hepatica, F. gigantica and the intermediate Fasciola. The Guangxi isolates and the majority of Guizhou isolates were (identified) as F. gigantica, and the Sichuan isolates, Heilongjian isolates and some Guizhou isolates were identified as intermediate Fasciola and the others were (identified) as either F. hepatica or intermediate Fasciola. The SSCP results were confirmed by sequencing. For those intermediate Fasciola, polymorphism existed in the variable sequence positions. This study showed that ITS-1 could be applied as genetic marker in classifying Fasciola and also indicated that intermediate Fasciola may exist in China.