陕西省榆林地区鸡蛔虫核糖体18S rRNA与ITS-2序列分析及种系发育关系研究

Sequence analysis of ribosome 18S rRNA and ITS-2 of Ascaridia galli in Yulin region,Shaanxi Province and study on their phylogenetic relationship

为了探究陕西省榆林地区鸡蛔虫核糖体18S rRNA、ITS-2基因序列特征及其种系发育关系,试验以采集于该地区的28条鸡蛔虫为样品,PCR扩增其18S rRNA、ITS-2基因的部分序列,测序后分别对鸡蛔虫18S rRNA、ITS-2基因序列的碱基组成进行分析,计算A、T、G和C的含量,并对这两个基因的遗传多样性进行分析,比较其种内、种间差异,构建种系发育树。结果表明:测序所获得的鸡蛔虫18S rRNA、ITS-2基因序列的长度分别为637,350 bp;其中18S rRNA基因序列的A、T、G和C的含量分别为24.5%~25.2%、26.1%~26.4%、28.3%~28.7%和20.3%~20.9%,A+T含量为50.6%~51.6%,G+C含量为48.6%~49.6%,种内差异为0~1.6%;与猪蛔虫(MF358962)、人蛔虫(LC422643)、犬弓首蛔虫(FJ418788)及狮弓蛔虫(JF837179)种间差异为5.18%~61.38%;ITS-2基因序列中的A、T、G和C的含量分别为28.9%~29.1%、38.0%~38.6%、19.1%~19.7%与12.9%~13.7%,A+T含量为66.9%~67.7%,G+C含量为32.0%~33.4%,种内差异为0~2.3%,与猪蛔虫(MF358962)、人蛔虫(LC422643)、犬弓首蛔虫(FJ418788)及狮弓蛔虫(JF837179)种间差异为55.95%~58.42%。此外,所构建的两个种系发育树具有类似的拓扑结构,均显示来自于陕西省榆林地区的28条鸡蛔虫共同聚为一个分支。说明来自于陕西省榆林地区鸡蛔虫的ITS-2序列呈AT偏好,其18S rRNA、ITS-2基因序列均具有种内差异小而种间差异大的特点,且个体之间存在一定程度的遗传差异,但它们之间的亲缘关系较近。

In order to explore the sequence characteristics of the ribosome 18S rRNA and ITS-2 genes in Ascaridia galli in Yulin region,Shaanxi Province and their phylogenetic relationship,in the experiment,28 individuals of Ascaridia galli were collected in this region as the samples,and PCR was used to amplify partial sequences of its 18S rRNA and ITS-2 genes,which were sequenced.The base composition of the 18S rRNA and ITS-2 gene sequences of Ascaridia galli were analyzed respectively,and the contents of A,T,G and C were calculated.The genetic diversity of the two genes was analyzed,and their intraspecific and interspecific differences were obtained,and a germline development tree was constructed.The results showed that the lengths of the 18S rRNA and ITS-2 gene sequences obtained by sequencing were 637,350 bp,respectively.Among them,the contents of A,T,G and C of 18S rRNA gene sequence were 24.5%-25.2%,26.1%-26.4%,28.3%-28.7%and 20.3%-20.9%,respectively.The A+T content was 50.6%-51.6%,and the G+C content was 48.6%-49.6%;the intraspecific difference was 0-1.6%;the interspecific difference with Ascaris suum(MF358962),Ascaris lumbricoides(LC422643),Toxocara canis(FJ418788)and Toxascaris leonina(JF837179)was 5.18%-61.38%.The contents of A,T,G and C in ITS-2 gene sequence were 28.9%-29.1%,38.0%-38.6%,19.1%-19.7%and 12.9%-13.7%,respectively.The A+T content was 66.9%-67.7%,and the G+C content was 32.0%-33.4%;the intraspecific difference was 0-2.3%,and the interspecific difference with Ascaris suum(MF358962),Ascaris lumbricoides(LC422643),Toxocara canis(FJ418788)and Toxascaris leonina(JF837179)was 55.95%-58.42%.In addition,the two phylogenetic trees constructed had similar topological structure,both of which showed that 28 individuals of Ascaridia galli collected in Yulin region,Shaanxi Province were clustered in one branch.The results suggested that the ITS-2 sequences of Ascaridia galli collected in Yulin region,Shaanxi Province showed AT preference.Its 18S rRNA and ITS-2 gene sequences had the characteristics of small intraspecific difference and large interspecific difference,and there was certain genetic difference between individuals,but they were closely related.