白鹈鹕体内对盲囊线虫种类的鉴定及其ITS序列分析

为了鉴定从广东某地圈养的白鹈鹕体内的线虫种类,2个样本通过形态学观察初步鉴定为对盲囊线虫后,对虫体核糖体DNA（rDNA）内转录间隔区ITS-1、ITS-2及5.8SrDNA序列进行扩增和测序,并与GenBankTM公布的序列进行比对,构建系统发育树分析,确定其种类.结果显示,白鹈鹕体内线虫符合对盲囊线虫的形态学特征,其ITS-1序列长度为463 bp,与Contracaecum sp.（GenBankTM登录号：KF990496.1）ITS-1的序列相似性分别为98.9％、99.8％;ITS-2序列长度分别为288-289 bp,与C.bancrofii（GenBankTM登录号：FM177887.1）的ITS-2序列的相似性分别为96％、95％;5.8SrDNA序列长度为157 bp.通过以ITS-1序列为分子标记的系统发育树分析,白鹈鹕体内线虫与C.bancrofti属同一分支,应为C.bancrofii.形态学鉴定方法结合ITS序列分析可以准确鉴定白鹈鹕体内线虫的种类,为其他线虫的快速准确鉴定提供参考.

The Identification and ITS Sequence Analysis of Ascaridoid Nematode from White Pelican（Pelecanus onocrotalus）

Based on morphology, we identified two ascaridoid nematodes from white pelican（ Pelecanus onocrotalus） in Guangdong Povince as Contracaecum spp. We then amplified the internal transcribed spacers（ ITS -1, ITS -2）, 5. 8S of ribosomal DNA and cloned them for sequencing. The sequences were compared with those published in GenBankTM , and the phylogenetic tree of those sequences was built and analyzed to confirm the identity of the ascaridoid nematode. The morphological characteristics of the ascaridoid nematode from the white pelican matched Contracaecum sp. The ITS - 1 sequences of the ascaridoid nematode were 463bp, which similarity was 98.9% and 99.8% with Contracaecum sp. （accession number, KF990496. 1 in GenBankTM）. The ITS -2 sequences were 289bp and 288bp, and similarity was 96% and 95% with Contracaecum bancrofti（ accession number, FM177887. 1 in GenBankTM）, respectively. The 5. 8S sequences were both 157bp. The ascaridoid nematode from the white pelican fell within the same branch as Contracaecum bancrofti by analysis of the phylogenetic tree with iTS - 1 sequences as molecular markers, which was identified as Contracaecum bancrofti. Morphological observation and ITS rDNA sequences analysis could be used for rapid and exact identification of the ascaridoid nematode from the white pelican, and provide the reference for the rapid identification of other nematodes.