中国米虾bursicon基因的功能及作用机制

为探讨米虾鞣化激素在其蜕皮周期及表皮角质层形成过程中的作用, 采用PCR技术克隆得到了米虾鞣化激素两个亚基基因的开放阅读框(ORF)序列。bursicon-α ORF全长441 bp, 共编码146个氨基酸; bursicon-β ORF全长411 bp, 共编码136个氨基酸。利用实时荧光定量PCR分析米虾整个蜕皮周期中鞣化激素2个亚基基因的表达特征, 结果发现, 鞣化激素bursicon-α和bursicon-β在米虾蜕皮周期的各个阶段的相对表达量存在差异, 在蜕皮前期(D期)相对表达量开始上升, 到D₃期时相对表达量最高, 蜕皮期E期相对表达量最低。RNA干扰(RNA interference, RNAi)介导bursicon-α和bursicon-β基因沉默后, 发现米虾的蜕皮周期延长, 表皮角质层明显变薄。结果提示, 鞣化激素(Bursicon)与新形成的外骨骼中角质层的加厚与硬化密切相关, 进而影响蜕皮时间。

THE FUNCTION AND MECHANISM OF BURSICON GENE IN CARIDINA

To study the function of bursicon gene in Caridina during molting and cuticle formation, its open reading frame (ORF) containing two subunits genes were amplified by PCR respectively. The ORF of bursicon-α is 441 bp in length, encoding a protein with 146 amino acid residues. The ORF of bursicon-β is 411 bp in length, encoding a protein with 136 amino acid residues. The dynamic changes in the expression of both bursicon subunit genes during the molt cycle in Caridina have been analyzed by the real-time quantitative PCR. Relative expression of both bursicon-α and bursicon-β had different levels in different stages of the molt cycle, which increased through premolt stage (D stage) and reached their peak level at the D₃ stage. The mRNA accumulation decreased to its lowest level at the molt stage (E stage). RNA interference-mediated knockdown of bursicon-α and bursicon-β retard the molting process and ecdysis behavior of Caridina. The cuticle of dsRNA-treated Caridina was thinner than that in the control group. These findings demonstrate that bursicon is involved in the thickening and hardening of cuticle in newly formed exoskeleton. Moreover, bursicon plays an important role in molt cycle.