Department of Biology, National Museum of Natural Science, Taiwan, Taichung, Republic of China.
J Exp Zool A Ecol Integr Physiol. 2023 Oct;339(8):788-798. doi: 10.1002/jez.2729. Epub 2023 Jul 5.
Sugar transporters (Sts) play important roles in controlling carbohydrate transport and are responsible for mediating the movement of sugars into cells. Few studies have been conducted on expressions of Sts during insect embryonic development. In the present study, we investigated temporal expressions of St genes during the embryonic diapause process in Bombyx mori. We found that in HCl-treated developing eggs, high gene expressions of trehalose transporter 1 (Tret1) were detected during middle and later embryonic development. St4 and St3 gene expressions gradually increased during the early stages, reached a small peak on Day 3, and large peaks were again detected on Day 7. However, in diapause eggs, expression levels of the Tret1, St4, and St3 genes all remained at low levels. Differential temporal changes in expressions of the Tret1, St4, and St3 genes found between diapause and HCl-treated eggs were further confirmed using nondiapause eggs. Our results showed that nondiapause eggs exhibited similar changing patterns as those of HCl-treated eggs, thus clearly indicating potential correlations between expressions of these genes and embryonic development. In addition, high gene expressions of Tret1 were also detected when dechorionated eggs were incubated in the medium. The addition of LY294002 (a specific phosphatidylinositol 3-kinase [PI3K] inhibitor) and U0126 (a mitogen-activated protein kinase/extracellular signal-regulated kinase [ERK] kinase [MEK] inhibitor) partially inhibited Tret1 gene expression in dechorionated eggs, but did not affect either ecdysteroid-phosphate phosphatase gene expression or ecdysteroid biosynthesis, clearly indicating that both PI3K and ERK are involved in increased gene expression of Tret1 that was independent of ecdysteroid levels. To our knowledge, this is the first comprehensive report to demonstrate the transcriptional regulation of St genes during embryonic development, thus providing useful information for a clearer understanding of insect egg diapause mechanisms.
糖转运蛋白（Sts）在控制碳水化合物运输中发挥着重要作用，负责介导糖进入细胞的运动。关于昆虫胚胎发育过程中 Sts 的表达，很少有研究。在本研究中，我们研究了 St 基因在桑蚕胚胎滞育过程中的时空表达。我们发现，在 HCl 处理的发育卵中，海藻糖转运蛋白 1（Tret1）在中晚期胚胎发育过程中高表达。St4 和 St3 基因的表达在早期逐渐增加，在第 3 天达到小高峰，然后在第 7 天再次检测到大高峰。然而，在滞育卵中，Tret1、St4 和 St3 基因的表达水平均保持在低水平。在非滞育卵中进一步证实了 Tret1、St4 和 St3 基因在滞育和 HCl 处理卵之间的表达存在差异的时间变化。我们的结果表明，非滞育卵表现出与 HCl 处理卵相似的变化模式，因此清楚地表明这些基因的表达与胚胎发育之间存在潜在的相关性。此外，脱壳卵在培养基中孵育时也检测到 Tret1 基因的高表达。添加 LY294002（一种特异性磷脂酰肌醇 3-激酶 [PI3K]抑制剂）和 U0126（丝裂原激活蛋白激酶/细胞外信号调节激酶 [ERK]激酶 [MEK]抑制剂）部分抑制脱壳卵中 Tret1 基因的表达，但不影响蜕皮甾酮-磷酸磷酸酶基因的表达或蜕皮甾酮的生物合成，这清楚地表明 PI3K 和 ERK 都参与了与蜕皮甾酮水平无关的 Tret1 基因表达的增加。据我们所知，这是首次全面报道在胚胎发育过程中 St 基因的转录调控，为更清楚地了解昆虫卵滞育机制提供了有用信息。
