Real time imaging of transcriptional activity in live mouse preimplantation embryos using a secreted luciferase.

Study of gene expression kinetics during preimplantation mammalian development is difficult because of the limited amount of material and the usually destructive, static nature of molecular analyses. We describe continuous, noninvasive monitoring of gene expression in preimplantation embryos by using a secreted luminescent reporter, Vargula luciferase. Transgene expression profiles were followed by assaying aliquots of culture medium or by direct visualization of Vargula luciferase secretion from living embryos in real time through photon imaging. With this approach, it is possible to observe epigenetic modulations of gene expression and to link this over time to the developmental capacity of individual embryos. In addition, by developing a strategy where expression from integrated transgenes is enhanced relative to that from nonintegrated DNA, we provide evidence that rapid detection of transgene integration prior to the blastocyst stage should be possible. Thus, imaging of Vargula luciferase secretion may also be useful in the early screening of embryos, for example, in the production of transgenic livestock. IMAGES:

哺乳动物着床前发育（preimplantation mammalian development）过程中的基因表达动力学（gene expression kinetics）研究颇具难度，这是由于该阶段样本量有限，且分子分析通常兼具破坏性与静态性特征。
我们介绍了一种利用分泌型荧光报告因子（secreted luminescent reporter）——海萤荧光素酶（Vargula luciferase）对着床前胚胎的基因表达进行连续无创监测的方法。
通过检测培养液等分试样，或借助光子成像（photon imaging）技术对活胚胎分泌的海萤荧光素酶进行实时直接可视化观测，即可追踪转基因表达谱（transgene expression profiles）。
借助该方法，可观测基因表达的表观遗传调控（epigenetic modulations），并能随时间推移将其与单个胚胎的发育潜能（developmental capacity）相关联。
此外，本研究开发了一种相较于非整合DNA（nonintegrated DNA）可增强整合型转基因（integrated transgenes）表达的策略，并据此证明在囊胚期（blastocyst stage）之前即可快速检测转基因整合事件。
因此，海萤荧光素酶分泌成像技术或可用于胚胎的早期筛查，例如在转基因家畜（transgenic livestock）制备过程中。
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