Bombyx mori vitellogenin (BmVg) is highly upregulated during pupation, and the 20-hydroxyecdysone and amino acids may regulate stage-specific BmVg expression. However, previous studies showed that other factors may also affect stage-specific BmVg expression. Here, we characterized effective BmVg transcription factors by identifying the corresponding cis-regulatory elements (CREs). We prepared transgenic B. mori, in which DsRed was driven by various lengths of BmVg promoter. qRT-PCR analysis showed that DsRed expression driven by a 1.0-kb BmVg promoter (VgP1.0K) was consistent with endogenous BmVg. VgP1.0K specificity was closer to the endogenous BmVg promoter than that of VgP0.8K. These results suggest that CREs affecting stage-specific BmVg expression were localized to the 1.0-kb BmVg promoter. We investigated the effects of certain CREs that could influence the stage specificity of BmVg promoter on BmVg expression in transgenic B. mori. The relative DsRed expression was significantly reduced in transgenic female B. mori and the peak in DsRed expression was delayed after E-box CRE mutation. These results demonstrate that the E-box element enhanced BmVg expression and also affected stage-specific BmVg expression. Moreover, the relative DsRed expression was significantly increased in transgenic female of B. mori after 3×BD CRE mutation in BmVg promoter. However, the stage specificity of the mutated promoter was consistent with that of the endogenous BmVg promoter. The 3×BD element downregulated BmVg but had no effect on stage-specific BmVg expression. The present study promoted the process of elucidating the regulatory network for stage-specific BmVg expression and furnished a theoretical basis for the application of BmVg promoter.

中文翻译：

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某些顺式调控元件对家蚕特定阶段卵黄蛋白原表达的影响（鳞翅目：家蝇科）。

家蚕中的家蚕卵黄蛋白原（BmVg）在化脓过程中高度上调，并且20-羟基蜕皮激素和氨基酸可能调节阶段特异性BmVg的表达。但是，以前的研究表明，其他因素也可能影响阶段特异性BmVg的表达。在这里，我们通过鉴定相应的顺式调控元件（CRE）来表征有效的BmVg转录因子。我们制备了转基因桑蚕，其中DsRed由各种长度的BmVg启动子驱动。qRT-PCR分析显示DsRed表达由1.0-kb BmVg驱动启动子（VgP1.0K）与内源性BmVg一致。VgP1.0K特异性比VgP0.8K更接近内源性BmVg启动子。这些结果表明，影响阶段特异性BmVg表达的CRE定位于1.0-kb BmVg启动子。我们研究了可能影响BmVg启动子阶段特异性的CRE对转基因桑蚕BmVg表达的影响。DsRed的相对表达在转基因雌性B. mori中显着降低，并且在DsRed中达到峰值E-box CRE突变后表达被延迟。这些结果证明，E-box元件增强了BmVg表达，并且还影响了阶段特异性的BmVg表达。此外，在BmVg启动子中3×BD CRE突变后，相对的DsRed表达在家蚕的转基因雌性中显着增加。然而，突变的启动子的阶段特异性与内源性BmVg启动子的阶段特异性一致。3×BD元素下调BmVg，但对阶段特异性BmVg表达没有影响。本研究促进了阐明特定阶段BmVg的监管网络的过程表达并为BmVg启动子的应用提供了理论基础。