四种璃眼蜱ITS2基因的序列分析

SEQUENCE ANALYSIS OF ITS2 GENE IN 4 SPECIES OF HYALOMMA （ ACARI： IXODIDAE）

对采自新疆准噶尔盆地的亚洲璃眼蜱指名亚种、亚东璃眼蜱、残缘璃眼蜱和盾糙璃眼蜱进行总DNA提取，PCR扩增和测序，并从GenBank中下载的6种硬蜱ITS2序列，应用软件分析ITS2片段长度、变异位点、G＋C含量和进化关系。结果显示，亚洲璃眼蜱指名亚种和亚东璃眼蜱的ITS2序列长度均为1458bp，全序列存在3个变异位点（A、G转换）和2个碱基缺失＼插入，同源性达99％，残缘璃眼蜱和盾糙璃眼蜱的ITS2全长均为1561bp，存在12个变异位点，同源性达99％；12种硬蜱的ITS2序列中G＋C含量较高，为61．2％-62．7％。系统进化分析表明亚洲璃眼蜱指名亚种和亚东璃眼蜱、残缘璃眼蜱和盾糙璃眼蜱分别处在两个分支上，这两个分支分别与嗜驼璃眼蜱和小亚璃眼蜱聚为一支。璃眼蜱属、革蜱属和扇头蜱属聚为一大支，血蜱属单独构成一大支。

The total DNA was extracted, amplified and sequenced by PCR from 4 species of Hyalomma ticks, Hy. a. asiaticum, Hy. asiaticum, Hy. detritum and Hy. scupense, collected from Junggar Basin of Xinjiang Uygur Autonomous Region. The ITS2 sequences of 6 species of Ixodes were downloaded from GenBank, and then the fragment length of ITS2, the variant sites, G ＋ C contents and the phylogenetic relationships were analyzed with bioinformatics software. It has been recognized that the fragment length of ITS2. sequence in both Hy. asiaticum asiaticum and Hy. asiaticum were 1 458 bp with 3 variant sites （A←→G conversion） . 2 of base deletion/insertion, and the homology reached to 99% ; while the fragment length of ITS2 sequence in both Hy. detritum and Hy. scupense were 1 561 bp with 12 variant sites, the homology reached also to 99%. The G ＋ C contents of ITS2 sequence m the 12 Ixodes ticks were 61.2%-62. 7%. Phylogenetic analysis indicated that Hy. a. asiaticum and Hy. asiaticum, and Hy. detritum and Hy. scupense were respectively clustered in different branches of phylogenetic tree, and the both branches were then clustered together with Hy. dromedarri and Hy. a. anatolicum. Ticks of Hyalomma. Dermacetor and Rhipicephalus were clustered together forming a big branch, and those of Haemaphysalis forms alone another big branch.