Quantitative Analysis of Gene Expression in Preimplantation Mouse Embryos Using Green Fluorescent Protein Reporter1

We have developed a method to monitor noninvasively, quantitatively, and in real-time transcription in living preimplantation mouse embryos by measuring expression of a short half-life form of enhanced green fluoresecent protein (EGFP) following microinjection of a plasmid-borne EGFP reporter gene. A standard curve was established by injecting known amounts of recombinant green fluorescent protein, and transcriptional activity was then determined by interpolating the amount of fluoresence in the DNA-injected embryos. This approach permitted multiple measurements in single embryos with no significant detrimental effect on embryonic development as long as light exposure was brief (