Department of Bioproductive Science, Faculty of Agriculture, Takasaki University of Health and Welfare, Gunma, Japan.
Faculty of Agriculture, Utsunomiya University, Tochigi, Japan.
Arch Insect Biochem Physiol. 2024 Jan;115(1):e22076. doi: 10.1002/arch.22076.
In the present study, we tried to clarify when and how pupal commitment (PT) better to use PC occurs and what is involved in the PT of Bombyx mori. To clarify this, we examined the responsiveness of a wing disc to ecdysone, referring to metamorphosis-related BR-C, development-related Myc and Wnt, and chromatin remodeling-related genes at around the predicted PT stage of the Bombyx wing disc. Wing disc responsiveness to juvenile hormone (JH) and ecdysone was examined using Methoprene and 20-hydroxyecdysone (20E) in vitro. The body weight of B. mori increased after the last larval ecdysis, peaked at Day 5 of the fifth larval instar (D5L5), and then decreased. The responsiveness of the wing disc to JH decreased after the last larval ecdysis up to D3L5. Bmbr-c (the Broad Complex of B. mori) showed enhanced expression in D4L5 wing discs with 20E treatment. Some chromatin remodeler and histone modifier genes (Bmsnr1, Bmutx, and Bmtip60) showed upregulation after being cultured with 20E in D4L5 wing discs. A low concentration of 20E is suggested to induce responsiveness to 20E in D4L5 wing discs. Bmbr-c, Bmsnr1, Bmutx, and Bmtip60 were upregulated after being cultured with a low concentration of 20E in D4L5 wing discs. The expression of Bmmyc and Bmwnt1 did not show a change after being cultured with or without 20E in D4L5 wing discs, while enhanced expression was observed with 20E in D5L5 wing discs. From the present results, we concluded that PT of the wing disc of B. mori occurred beginning on D4L5 with the secretion of low concentrations of ecdysteroids. Bmsnr1, Bmutx, Bmtip60, and BR-C are also involved.
在本研究中，我们试图阐明蛹期承诺（PT）何时以及如何更好地发生，以及家蚕的 PT 涉及哪些方面。为了阐明这一点，我们检查了家蚕翅盘对蜕皮激素的反应性，参考了与变态相关的 BR-C、与发育相关的 Myc 和 Wnt 以及与染色质重塑相关的基因，这些基因大约在预测的家蚕翅盘 PT 阶段。使用 Methoprene 和 20-羟基蜕皮激素（20E）在体外检查了翅盘对保幼激素（JH）和蜕皮激素的反应性。家蚕的体重在最后一次幼虫蜕皮后增加，在第五龄幼虫的第五天（D5L5）达到峰值，然后下降。翅盘对 JH 的反应性在最后一次幼虫蜕皮后直至 D3L5 下降。Bmbr-c（家蚕的 Broad Complex）在用 20E 处理 D4L5 翅盘时表达增强。一些染色质重塑酶和组蛋白修饰酶基因（Bmsnr1、Bmutx 和 Bmtip60）在用 20E 培养后在 D4L5 翅盘中上调。低浓度的 20E 被认为可以诱导 D4L5 翅盘中对 20E 的反应性。Bmbr-c、Bmsnr1、Bmutx 和 Bmtip60 在 D4L5 翅盘中用低浓度 20E 培养后上调。Bmmyc 和 Bmwnt1 的表达在用或不用 20E 培养 D4L5 翅盘后没有变化，而在用 20E 培养 D5L5 翅盘时表达增强。从目前的结果来看，我们得出结论，家蚕翅盘的 PT 从 D4L5 开始发生，此时分泌低浓度的蜕皮激素。Bmsnr1、Bmutx、Bmtip60 和 BR-C 也参与其中。
