红光熊蜂卵黄原蛋白基因的cDNA全长序列克隆和表达分析

红光熊蜂Bombus ignitus Smith是许多经济作物和野生植物的重要授粉昆虫之一。卵黄原蛋白基因(vitellogenin,Vg)在昆虫的生殖调控中和行为方面起到重要的作用,本试验对Vg基因全长cDNA的克隆和测序及在蜂王、工蜂和雄性蜂三型蜂中的表达分析得出:Vg基因的全长cDNA为5 481 bp,GenBank中的登录号为FJ913883,有一个完整的开放阅读框(ORF),编码1 772个氨基酸,N-末端的前16个氨基酸为一个信号肽。接近C-末端区域存在保守的GL/ICG基元,其后含有9个半胱氨酸,而且DGXR位于GL/ICG基元上游18个氨基酸残基处。其氨基酸序列与韩国的熊蜂B.ignitus和B.hypocrita相似性高达95%,与西方蜜蜂Apis mellifera的相似性达到51%。Vg的mRNA首先在蜂王蛹期的白眼蛹(Pw)时期出现,其表达量在蜂王整个蛹期发育过程中呈上升趋势,且在黑眼蛹(Pbd)时期达到最高,在成年蜂的脂肪体中的表达量仍在升高,甚至更高。Vg也在工蜂蛹期的白眼蛹(Pw)时期被检测到,然后在整个蛹期发育过程中呈现上升趋势,在刚羽化出房时达到高峰,Vg的mRNA水平随着成年蜂日龄的增加而增加,到15日龄时达到最高,然后呈现下降趋势。对于雄性蜂,Vg的mRNA虽然卵黄原蛋白基因的mRNA水平几乎在整个蛹期发育阶段都表达,但是表达水平非常低,只有在刚羽化出房时期表达水平较高。

The expression of the mRNA and cloning for the vitellogenin cDNA in the bumblebee, Bombus ignitus

Bombus ignitus Smith is one of the important pollinators of many economically important crops and wildflowers. vitellogenin （Vg） plays a key role in the control of reproduction and reproductive behavior of this species. In this study, Vg cDNA of B. ignitus was cloned and sequenced. It is composed of 5 481 bp and contains an ORF of 1 772 amino acids within a putative signal peptide of 16 residues （GenBank accession number FJ913883）. Close to the C-terminus there is a GL/ICG motif followed by nine cysteines, and a DGXR motif is located 18 residues upstream of the GL/ICG motif. BLASTX analysis of the conceptual translation products revealed 95% similarity to B. ignitus from Korea and to B. hypocrita. The deduced amino acid sequence shows significant similarity with Apis mellifera （51% ） and a high number of conserved motifs. The mRNA of B. ignitus vitellogenin（Vg）was analysed in queens, workers and drones, from pupae to adults. Vg mRNA was found in the white-eyed pupal （Pw） stage in queens and its expression increased during the entire pupal development, reaching a peak in the dark brown pupal （Pbd） stage. It also had a high expression in the adult fatbody. In workers, the Vg expression was detected in the white-eyed pupal （Pw）stage, its levels increasing with age and reaching a high point in 15 d, after which it decreased progressively. Vg mRNA was also observed in drones, the highest level of expression being observed in newly emerged adult drones.