家蚕保幼激素甲基转移酶基因的克隆与表达分析

Cloning and Characterization of Juvenile Hormone Methyltransgerase Gene,JHAMT2,in Silkworm,Bombyx mori

根据家蚕表达序列标签(ESTs),克隆了一个家蚕保幼激素甲基转移酶基因(JHAMT2)的全长cDNA序列。序列分析表明,该基因全长1007 bp,序列分析有4个外显子,定位于家蚕第12号染色体的nscaf 2 993上,推导的编码蛋白序列长度为266AA,有一个甲基转移酶超家族功能位点,与烟草天蛾(Manduca sexta)JHAMT同源性达到38%。JHAMT2基因在家蚕丝腺、特别是中部丝腺组织特异表达,发育时期表现为4龄期有比较高的表达量,5龄期只在5龄第3日有表达,性别差异表现为雄性体内持续表达时间比雌性中长。JHAMT2基因表达受到外源激素MH的负调控和JHA的正调控,雌性对外源昆虫激素的感受更敏感。

A full length cDNA, 1007 bp, was cloned according to thc expression sequence tags （ESTs） of Bombyx mori. This gune contains four exons, located on the nscaf 2993 of the 12th chromosome of B. mot/. The deduced protein sequence is 266aa with a functional locus of methyhransgcrase super family. It owns 38 % homology with JHAMT in Manduca sexta and therefore the cloning gene was named as juvenile hormone mcthyltransgcrasc gcne of Bombyx mori, JHAMT2. The JHAM72 specially expressed in the silkgland, especially in the middle silkgland. During different developmental stages, it had a relatively higher expression level in the 4th instar larvas, while it only expressed on the third day during the whole fifth larvae. The sexual differences were reflected by a longer continuous expression time in males than that in females. The expression level of JHAMT2 was negatively regulated by exogenous MH and positively regulated by JHA during the middle stage of the 5th instal＇. Males were more sensitive to exogenous insect hormones than females.