Shi Yan, Liu Tian-Yuan, Jiang Hong-Bo, Liu Xiao-Qiang, Dou Wei, Park Yoonseong, Smagghe Guy, Wang Jin-Jun
Key Laboratory of Entomology and Pest Control Engineering, College of Plant Protection, Southwest University, Chongqing, China.
Academy of Agricultural Sciences, Southwest University, Chongqing, China.
Front Physiol. 2019 Mar 18;10:151. doi: 10.3389/fphys.2019.00151. eCollection 2019.
Ecdysis triggering hormone (ETH), released by the Inka cells, is a master hormone in regulating the ecdysis process in insect. Here we investigated the presence and role of the ETH signaling in the female adult of the oriental fruit fly, (Hendel) that is one of the most important invasive pest insects in agriculture worldwide. In the female adult, ETH was confirmed in the Inka cells at the tracheae by immunostaining and also exposure to ETH stimulated the isolated corpora allata of adult in activity. Then we prepared cDNA of females at 0, 5, 10, 15, and 20 days after adult eclosion, and RT-qPCR showed that the expression pattern of and its receptor started from a peak at the day of adult eclosion (day 0), then dropped to basal levels and increased again between day 10 and 15 which is also the period corresponding to ovary growth. In contrast, was absent with Ct values of >33. The expression patterns of the ecdysteroid-producing Halloween genes and , and the vitellogenin genes , , and co-occurred with peak levels at days 10-15, and also juvenile hormone acid methyltransferase () showed increased levels on day 15. Further in RNAi assays to better understand the role of ETH and ETHR, dsRNA was injected to adult and this led to a respective decrease in expression of 62 and 56% for and , while stayed absent with Ct values of 33. In these RNAi-females, there was an apparently decreased expression for and , together with a significant decrease of the JH titer and egg production. Injection of the JH mimetic methoprene could rescue expression and egg production. Upstream, in ds/ds-injected females, 20-hydroxyecdysone (20E) injection rescued the transcriptions of and and also egg production. In summary, our results shed more light on the pivotal role that the ETH peptide hormone and its receptor ETHR-B play an essential role in the reproduction of the female adult of , via the regulation of JH and vitellogenin, which are controlled by a pulse of 20E.
由印卡细胞释放的蜕皮触发激素（ETH）是调节昆虫蜕皮过程的主要激素。在此，我们研究了ETH信号在桔小实蝇雌性成虫中的存在情况及其作用，桔小实蝇是全球农业中最重要的入侵害虫之一。在雌性成虫中，通过免疫染色在气管的印卡细胞中证实了ETH的存在，并且暴露于ETH会刺激成虫离体的咽侧体的活性。然后，我们制备了羽化后0、5、10、15和20天雌性的cDNA，逆转录定量聚合酶链反应（RT-qPCR）显示，[相关基因]及其受体[相关受体]的表达模式在羽化当天（第0天）从峰值开始，然后降至基础水平，并在第10天至15天之间再次升高，这也是与卵巢生长相对应的时期。相比之下，[另一基因]不存在，其Ct值>33。蜕皮甾体生成的“万圣节”基因[相关基因]和[相关基因]以及卵黄蛋白原基因[相关基因]、[相关基因]和[相关基因]的表达模式在第10 - 15天出现峰值，并且保幼激素酸甲基转移酶（JHAMT）在第15天也显示出水平升高。进一步通过RNA干扰试验以更好地了解ETH和ETHR（ETH受体）的作用，将双链RNA注射到成虫体内，这导致[相关基因]和[相关受体]的表达分别下降了62%和56%，而[另一基因]仍不存在，其Ct值为33。在这些RNA干扰的雌性中，[相关基因]和[相关基因]的表达明显下降，同时保幼激素滴度和产卵量显著降低。注射保幼激素类似物烯虫酯可以挽救[相关基因]的表达和产卵量。在上游，在注射双链RNA/双链RNA的雌性中，注射20 - 羟基蜕皮酮（20E）可以挽救[相关基因]和[相关基因]的转录以及产卵量。总之，我们的结果进一步揭示了ETH肽激素及其受体ETHR - B通过调节保幼激素和卵黄蛋白原，在桔小实蝇雌性成虫的繁殖中起着关键作用，而保幼激素和卵黄蛋白原受20E脉冲的控制。
