中文摘要：

【目的】鉴定中华按蚊Anopheles sinensis、冈比亚按蚊Anopheles gambiae、埃及伊蚊Aedes aegypti和致倦库蚊Culex quinquefasciatus 4种重要医学媒介蚊虫的离子受体基因IR8a与IR25a以及代表性的iGluRs基因和IRs基因,研究这些基因的特征及其系统发育关系,确定IR8a与IR25a基因在离子谷氨酸受体基因中的分类地位。【方法】以黑腹果蝇Drosophila melanogaster的iGluRs和IRs基因序列作为询问序列,用BLASTP和BLASTN方法分别搜索中华按蚊、冈比亚按蚊、埃及伊蚊和致倦库蚊的基因组数据库,以鉴定这4个种内的iGluRs和IRs基因序列;用生物信息学方法比较分析鉴定获得的IR8a与IR25a及代表性的iGluRs和IRs基因氨基酸序列的特征;用最大似然法、贝叶斯法和最大简约法构建并讨论这些基因氨基酸序列的系统发育关系;用PAML软件计算这些基因的dN/dS（ω）值并分析其选择压力。【结果】通过对中华按蚊、冈比亚按蚊、埃及伊蚊和致倦库蚊中离子谷氨酸受体基因进行生物信息学鉴定,获得了所有IR8a和IR25a基因,24个代表性的iGluRs基因和30个代表性的IRs基因的序列。特征比较和系统发育关系分析结果表明,在4种蚊虫和黑腹果蝇中IR8a与IR25a基因的氨基酸序列长度与iGluRs的更接近,其平均值远大于其他IRs的;IR25a和IR8a有与传统iGluRs相同的氨基酸末端区域（amino-terminal domain,ATD）,虽然IR8a的序列不太保守,而IRs则没有ATD;IR8a与IR25a序列有与传统iGluRs一样保守的配体结合区S1和S2,而IRs没有。所有这些基因的ω值远小于1,意味着这些基因在进化过程中都经历了纯化选择,而IR8a与IR25a的ω值更接近iGluRs。此外,IR8a与IR25a还有与non-NMDA相似的特异性位点,而这些位点在IRs不存在。再者,IR8a和IR25a与non-NMDA聚在一枝,形成一个姐妹群,群内序列间的遗传距离小于本研究中任何其他序列间的距离。根据这些研究结果,我们将IR8a与IR25a分类?

英文摘要：

[ Aim ] To identify the ionotropic receptor genes IR8a and IR25a, and the representative iGluRs and IRs genes in four vector mosquito species of medical importance, Anopheles sinensis, Anopheles gambiae, Aedes aegypti and Culex quinquefasciatus, and to investigate the characteristics and phylogenetic relationships of these genes, so as to determine the classification position of the IR8a and IR25a genes in the group of ionotropie glutamate receptor genes. [ Methods] By using BLASTP and BLASTN searching against the genomes of these four mosquito species with the iGluRs and IRs gene sequences of Drosophila melanogaster as query sequences, the sequences of iG[uRs and IRs genes of these four mosquito species were identified. The characteristics of the amino acid sequences of IR8a and IR25a and the representative iGluRs and IRs genes identified were predicted and comparatively analyzed by bioinformatics methods. The phylogenetic relationships of these genes in the five species were deduced and discussed by using maximum likelihood, Bayesian and maximum parsimony methods based on amino acid sequences, and the selection pressures of these genes were analyzed with the dN/ds （t~） values calculated by using PAML software. [ Results ] The sequences of IRSa and IR25a, 24 representative traditional iGluRs genes and 30 representative IRs genes in mosquitoes An. sinensis, An. gambiae, An. aegypti and Cx. quinquefasciatus were identified by bioinformatics methods. The comparative analyses of characteristics and phylogenetic relationships of these genes showed that the amino acid sequence lengths of IRSa and IR25a in the four mosquito species and D. melanogaster are closer to those of iGluRs, and their mean values are significantly longer than those of other IRs. IR25 a has the amino-terminal domain （ATD） that is the characteristic of traditional iGluRs, and IRSa also has a region similar to ATD, although it is not conservative, while IRs have no ATD. IR8a and IR25 also have the conserved S1 and $2 ligand-binding domain ?