尽管蜕皮类固醇在调节家蚕卵滞育过程中的作用已得到充分证明,与蜕皮类固醇生物合成及其下游信号有关的基因表达水平的时间变化尚不清楚。在本研究中,我们研究了与蜕皮类固醇生物合成有关的基因表达水平的变化及其在胚胎发育过程中的下游信号。结果表明,在滞育卵中,蜕皮类固醇磷酸盐磷酸酶(EPPase)基因和万圣节基因(Spook[Spo]和Shade[Shd])的表达保持在非常低的水平。然而,在由HCl阻止滞育的卵中,EPPase的信使RNA(mRNA)水平显着增加,斯波,在胚胎发育过程中检测到Shd。其他万圣节基因(梦幻岛[Nvd]和幻影[Phm])在滞育和HCl处理的鸡蛋之间也显示出不同的变化。然而,脱身(Dib)和阴影(Sad)的基因在滞育和HCl处理的卵中均显示出相似的变化。我们进一步调查了蜕皮激素受体基因表达水平的变化(EcRA,EcRB1和USP)和下游信号基因(E75A,E75B,E74A,E74B,Br-C,HR3、HR4、KR-H1和FTZ-F1)。结果表明,EcRA和其他核受体的基因(E75A,E75B,E74A,HR3,HR4,KR-H1和FTZ-F1)在滞育和HCl处理的卵之间表现出明显的差异模式,在HCl处理的卵中,在胚胎发育的后期检测到水平升高。使用非滞育卵进一步证实了在滞育和HCl处理的卵之间发现的涉及蜕皮类固醇生物合成及其下游信号的基因表达的差异时间变化。我们的结果表明,非滞育卵表现出与HCl处理卵相同的变化模式,从而清楚地表明这些基因的表达与B.mori胚胎发育之间的潜在相关性。据我们所知,这是研究蜕皮类固醇和蜕皮类固醇信号基因转录调控的第一份综合报告,从而为更清楚地了解昆虫卵滞育机制提供有用的信息。
Although the role of ecdysteroids in regulating egg diapause process in Bombyx mori is well documented, temporal changes in expression levels of genes involved in ecdysteroid biosynthesis and its downstream signaling are less well understood. In the present study, we studied changes in expression levels of genes involved in ecdysteroid biosynthesis and its downstream signaling during embryonic development of B. mori. Results showed that in diapause eggs, the expression of ecdysteroid-phosphate phosphatase (EPPase) gene and Halloween genes (Spook [Spo] and Shade [Shd]) remained at very low levels. However, in eggs whose diapause initiation was prevented by HCl, significant increases in the messenger RNA (mRNA) levels of EPPase, Spo, and Shd were detected during embryonic development. Other Halloween genes (Neverland [Nvd] and Phantom [Phm]) also showed different changes between diapause and HCl-treated eggs. However, genes of Disembodied (Dib) and Shadow (Sad) showed similar changes in both diapause and HCl-treated eggs. We further investigated changes in expression levels of ecdysone receptor genes (EcRA, EcRB1, and USP) and downstream signaling genes (E75A, E75B, E74A, E74B, Br-C, HR3, HR4, KR-H1, and FTZ-F1). Results showed that genes of EcRA and the other nuclear receptors (E75A, E75B, E74A, HR3, HR4, KR-H1, and FTZ-F1) exhibited significant differential patterns between diapause and HCl-treated eggs, with increased levels being detected during later stages of embryonic development in HCl-treated eggs. Differential temporal changes in expressions of genes involved ecdysteroid biosynthesis and its downstream signaling found between diapause and HCl-treated eggs were further confirmed using nondiapause eggs. Our results showed that nondiapause eggs exhibited the same changing patterns as those in HCl-treated eggs, thus clearly indicating potential correlations between expressions of these genes and embryonic development in B. mori. To our knowledge, this is the first comprehensive report to study the transcriptional regulation of ecdysteroidogenic and ecdysteroid signaling genes, thus providing useful information for a clearer understanding of insect egg diapause mechanisms.