小地老虎2种不同类型肌动蛋白基因的克隆与序列分析

本研究以鳞翅目夜蛾科昆虫小地老虎［Agrotis ipsilon（Hüfnagel）］3龄幼虫整个虫体为材料提取总RNA，利用RT-PCR和cDNA末端快速扩增技术（RACE），分别扩增得到2条肌动蛋白的cDNA序列Aiactin1和Aiactin2。GenBank数据库搜索及序列比对结果表明，克隆的2条肌动蛋白基因应属于2种不同类型的肌动蛋白，Aiactin1为肌肉特异型肌动蛋白，Aiactin2为细胞质特异型肌动蛋白。Aiactin1的cDNA序列含有1 469个碱基，Aiactin2的cDNA序列含有1 408个碱基。2条基因的cDNA序列均包括一个1 131个碱基的开放阅读框，编码一个含376个氨基酸的蛋白。Aiactin1肌动蛋白分子量约为41.77 ku，等电点5.22；Aiactin2肌动蛋白分子量约为41.83 ku，等电点5.47。Prosite软件分析结果表明，Aiactin1和Aiactin2肌动蛋白氨基酸序列中都存在3个肌动蛋白特征片段。2个基因的cDNA序列已经登录GenBank并获得登录号。

Molecular cloning and sequence analysis of two types of actin cDNA from the black cutworm, Agrotis ipsilon

Total RNA was isolated from the third instar larval body of the black cutworm, Agrotis ipsilon (Hüfnagel).The two actin cDNA sequences were cloned by RT-PCR and rapid amplification of cDNA ends (RACE) and were designated as Aiactin1 and Aiactin2, respectively.Blast search in GenBank and sequence comparisons with actin amino acid sequences from other species suggested that the Aiactin1 cDNA sequence encoded a cytoplasmic actin, while the Aiactin2 cDNA sequence encoded a muscle actin.The Aiactin1 cDNA, 1 469 base pairs in length, contained an open reading frame of 1 131 base pairs, coding for a polypeptide of 376 amino acid residues, with a predicted molecular weight of 41.77 ku and pI 5.22.Aiactin2 cDNA, 1 408 base pairs in length, contained an open reading frame of 1 131 base pairs, coding for a polypeptide of 376 amino acid residues, with a predicted molecular weight of 41.83 ku and pI 5.47.The deduced amino acid sequences of Aiactin1 and Aiactin2 were predicted to have three actin signature fragments by using the software Prosite.The two actin cDNA sequences have been deposited in GenBank with accession numbers EU601172 for Aiactin1 and EU601173 for Aiactin2.