Wu Jian-Jian, Chen Feng, Yang Rui, Shen Chen-Hui, Ze Long-Ji, Jin Lin, Li Guo-Qing
Education Ministry Key Laboratory of Integrated Management of Crop Diseases and Pests, State & Local Joint Engineering Research Center of Green Pesticide Invention and Application, Department of Entomology, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
Biology (Basel). 2022 Nov 9;11(11):1640. doi: 10.3390/biology11111640.
Ecdysone-induced protein 93F (E93) plays triple roles during post-embryonic development in insects whose juvenile instars are more than four. However, it only acts as a specifier of adult structures in flies whose larval instars are fixed at three. In this study, we determined the functions of E93 in the eggplant lady beetle (), which has four larval instars. We uncovered that was abundantly expressed at the prepupal and pupal stages. A precocious inhibition of the juvenile hormone signal by RNA interference (RNAi) of or , two vital downstream developmental effectors, at the penultimate instar larval stage increased the expression of , Conversely, ingestion of JH by the third-instar larvae stimulated the expression of but repressed the transcription of either or However, disturbance of the JH signal neither drove premature metamorphosis nor caused supernumerary instars. In contrast, depletion of at the third- and fourth-instar larval and prepupal stages severely impaired pupation and caused a larval-pupal mixed phenotype: pupal spines and larval scoli were simultaneously presented on the cuticle. RNAi of at the pupal stage affected adult eclosion. When the beetles had suffered from a ds injection at the fourth-instar larval and pupal stages, a few resultant adults emerged, with separated elytra, abnormally folded hindwings, a small body size and short appendages. Taken together, our results suggest the larval instars are fixed in ; E93 serves as a repressor of larval characters and a specifier of adult structures during the larval-pupal-adult transition.
蜕皮激素诱导蛋白93F（E93）在幼龄期超过4个的昆虫胚后发育过程中发挥三重作用。然而，在幼虫龄期固定为3个的果蝇中，它仅作为成虫结构的决定因子。在本研究中，我们确定了E93在具有4个幼虫龄期的茄二十八星瓢虫中的功能。我们发现E93在预蛹期和蛹期大量表达。在倒数第二龄幼虫期通过RNA干扰（RNAi）对两个重要的下游发育效应因子或进行早熟的保幼激素信号抑制，会增加E93的表达，相反，三龄幼虫摄入保幼激素会刺激E93的表达，但会抑制或的转录。然而，保幼激素信号的干扰既不会导致过早变态，也不会导致龄期增多。相比之下，在三龄和四龄幼虫以及预蛹期缺失E93会严重损害化蛹，并导致幼虫 - 蛹混合表型：蛹刺和幼虫刚毛同时出现在表皮上。在蛹期对E93进行RNA干扰会影响成虫羽化。当甲虫在四龄幼虫期和蛹期接受双链RNA注射时，会出现一些成虫，其鞘翅分离、后翅异常折叠、体型小且附肢短。综上所述，我们的结果表明茄二十八星瓢虫的幼虫龄期是固定的；E93在幼虫 - 蛹 - 成虫转变过程中作为幼虫特征的抑制因子和成虫结构的决定因子。
