Okude Genta, Ogihara Mari H, Moriyama Minoru, Yamagishi Takahiro, Yamamoto Hiroshi, Fukatsu Takema, Futahashi Ryo
Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, 113-0033, Japan.
Molecular Biosystems Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, 305-8566, Japan.
Sci Rep. 2025 Jul 1;15(1):21971. doi: 10.1038/s41598-025-08387-3.
Ecdysteroids are critical in regulating biological processes such as ecdysis, metamorphosis, embryogenesis, and reproduction in insects. Nevertheless, the ecdysteroid repertoire and expression patterns of their synthesis genes in Odonata (dragonflies and damselflies), which belong to the most-ancestral winged insect group, have remained elusive. In this study, we examined the ecdysteroid profile of eight Odonata species and the ecdysteroid fluctuation during metamorphosis in the damselfly Ischnura senegalensis (Zygoptera, Coenagionidae) and the dragonfly Pseudothemis zonata (Anisoptera, Libellulidae). We found that ecdysone and 20-hydroxyecdysone (20E) titers corresponded to the progression of ecdysis in the penultimate nymphal instar and metamorphosis in the final nymphal instar, whereas 7-dehydrocholesterol was consistently present in the hemolymph of all the examined species and developmental stages. Considering that a higher amount of 20E was detected than ecdysone, 20E is important for inducing ecdysis and metamorphosis in Odonata, like other insects. We also confirmed that the majority of ecdysteroidogenic genes were conserved in Odonata, and their stage- and region-specific expression patterns were examined in I. senegalensis and P. zonata. Unexpectedly, most ecdysteroidogenic genes were expressed in a variety of tissues. Our study provides insights into the evolution and diversification of the ecdysteroidogenic pathway among insects.
蜕皮甾类在调节昆虫的蜕皮、变态、胚胎发育和繁殖等生物学过程中起着关键作用。然而，属于最古老有翅昆虫类群的蜻蜓目（蜻蜓和豆娘）中蜕皮甾类的种类及其合成基因的表达模式仍不清楚。在本研究中，我们检测了8种蜻蜓目的蜕皮甾类特征，以及豆娘塞内加尔异痣蟌（均翅亚目，色蟌科）和蜻蜓黄带伪蜻（差翅亚目，蜻科）变态过程中的蜕皮甾类波动情况。我们发现，蜕皮激素和20-羟基蜕皮激素（20E）的滴度与倒数第二龄若虫的蜕皮进程以及末龄若虫的变态进程相对应，而7-脱氢胆固醇在所有被检测物种和发育阶段的血淋巴中均持续存在。鉴于检测到的20E含量高于蜕皮激素，与其他昆虫一样，20E对诱导蜻蜓目的蜕皮和变态很重要。我们还证实，大多数蜕皮甾类生成基因在蜻蜓目中是保守的，并在塞内加尔异痣蟌和黄带伪蜻中研究了它们在不同阶段和区域的特异性表达模式。出乎意料的是，大多数蜕皮甾类生成基因在多种组织中表达。我们的研究为昆虫蜕皮甾类生成途径的进化和多样化提供了见解。
