Lu Hu-Na, Zhang Peiyan, Wang Yifan, Luo Kai, Yan Ziyu, Zeng Mei, Lv Ya-Nan, Bai Shali, Zeng Jiaming, Li Sheng, Bai Yu, Luan Yun-Xia
Guangdong Provincial Key Laboratory of Insect Development Biology and Applied Technology, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou, China.
Insect Sci. 2025 Feb 19. doi: 10.1111/1744-7917.13504.
Insects represent one of the most evolutionarily successful groups, with their diversity hypothesized to be related to the regulatory roles of Hox genes, a set of related genes encoding homeodomain transcription factors determining the identity of segments along the anterior-posterior axis of the embryo. However, functional insights into the roles of Hox genes in primitive ametabolous insects, which represent the critical transition from aquatic crustaceans to winged insects, have been limited. In this study, we identified complete protein-coding sequences of 10 Hox genes in the Zygentoma Thermobia domestica, and applied clustered regularly interspaced short palindromic repeats (CRISPR) / CRISPR-associated nuclease 9 (Cas 9) mediated gene knockout (KO) to decipher their functions. We found that the roles of pb, Dfd, and Scr are vital in specifying the appendages of the head in T. domestica, and these roles are relatively conserved in crustaceans and winged insects. Antp is essential for the development of the prothorax segment and the first pair of legs in T. domestica. Ubx and abd-A fully repress appendage development in the abdomen of T. domestica, which implies a functional switch from crustaceans to insects. Additionally, the role of ftz in segmenting the abdomen of T. domestica suggests it has acquired new functions in primitive insects, beyond its traditional Hox-like roles. Although KOs of lab, Hox3, and Abd-B did not result in obvious external phenotypic changes, they led to a significant decrease in hatching rates and substantial deviations in daily survival numbers compared to the negative control. These findings underscore the indispensable roles of all Hox genes during the embryonic development of T. domestica. Our study sheds new light on the functional evolution of Hox genes in ametabolous insects and enhances our understanding of the genetic underpinnings of insect development and diversification.
昆虫是进化上最为成功的类群之一，据推测它们的多样性与Hox基因的调控作用有关，Hox基因是一组相关基因，编码同源结构域转录因子，决定胚胎前后轴上各节段的特征。然而，对于原始无变态昆虫中Hox基因作用的功能研究却很有限，而原始无变态昆虫代表了从水生甲壳类动物到有翅昆虫的关键过渡阶段。在本研究中，我们鉴定了衣鱼Thermobia domestica中10个Hox基因的完整蛋白质编码序列，并应用成簇规律间隔短回文重复序列（CRISPR）/CRISPR相关核酸酶9（Cas 9）介导的基因敲除（KO）来解析它们的功能。我们发现，pb、Dfd和Scr在确定衣鱼头部附肢方面起着至关重要的作用，并且这些作用在甲壳类动物和有翅昆虫中相对保守。Antp对于衣鱼前胸节段和第一对腿的发育至关重要。Ubx和abd - A完全抑制衣鱼腹部附肢的发育，这意味着从甲壳类动物到昆虫的功能转变。此外，ftz在衣鱼腹部节段划分中的作用表明，它在原始昆虫中获得了新功能，超出了其传统的类Hox基因作用。虽然lab、Hox3和Abd - B的基因敲除没有导致明显的外部表型变化，但与阴性对照相比，它们导致孵化率显著降低，并且每日存活数量出现大幅偏差。这些发现强调了所有Hox基因在衣鱼胚胎发育过程中不可或缺的作用。我们的研究为无变态昆虫中Hox基因的功能进化提供了新的见解，并增进了我们对昆虫发育和多样化的遗传基础的理解。
