Attardo Geoffrey M, Higgs Stephen, Klingler Kimberley A, Vanlandingham Dana L, Raikhel Alexander S
Department of Entomology, University of California, Riverside, CA 92521, USA.
Proc Natl Acad Sci U S A. 2003 Nov 11;100(23):13374-9. doi: 10.1073/pnas.2235649100. Epub 2003 Oct 31.
Blood feeding tightly regulates the reproductive cycle in anautogenous mosquitoes. Vitellogenesis (the synthesis of yolk protein precursors) is a key event in the mosquito reproductive cycle and is activated in response to a blood meal. Before blood feeding, Aedes aegypti is in a state of reproductive arrest during which the yolk protein precursor genes (YPPs) are repressed. The regulatory region of the major YPP gene vitellogenin (Vg) has multiple GATA-binding sites required for the high expression level of this gene. However, a GATA factor (AaGATAr) likely acts as a repressor, preventing activation of this gene before a blood meal. Here we report in vivo data confirming the role of AaGATAr as a repressor of the Vg gene at the state of previtellogenic arrest. Using an RNA interference (RNAi)-mediated technique in conjunction with the Sindbis viral expression system, we show that knockdown of the AaGATAr gene results in an increased basal level of expression of the Vg gene and an elevated response to the steroid hormone 20-hydroxyecdysone in mosquitoes in a state of arrest. These experiments have revealed a component in the molecular mechanism by which anautogeny is maintained in A. aegypti.
吸食血液严格调控非自育性蚊子的生殖周期。卵黄生成（卵黄蛋白前体的合成）是蚊子生殖周期中的关键事件，且会因吸食血液而被激活。在吸食血液之前，埃及伊蚊处于生殖停滞状态，在此期间卵黄蛋白前体基因（YPPs）受到抑制。主要的YPP基因卵黄原蛋白（Vg）的调控区域有多个GATA结合位点，该基因的高表达水平需要这些位点。然而，一种GATA因子（AaGATAr）可能作为一种阻遏物，在吸食血液之前阻止该基因的激活。在此，我们报告体内实验数据，证实了AaGATAr在卵黄生成前停滞状态下作为Vg基因阻遏物的作用。通过使用RNA干扰（RNAi）介导的技术并结合辛德毕斯病毒表达系统，我们发现敲低AaGATAr基因会导致处于停滞状态的蚊子中Vg基因的基础表达水平增加，以及对类固醇激素20-羟基蜕皮酮的反应增强。这些实验揭示了埃及伊蚊维持非自育性的分子机制中的一个组成部分。
