REAL-TIME IMAGING OF TRANSCRIPTIONAL ACTIVITY IN LIVE MOUSE PREIMPLANTATION EMBRYOS USING A SECRETED LUCIFERASE

Study of gene expression kinetics during preimplantation mammalian dev elopment is difficult because of the limited amount of material and th e usually destructive, static nature of molecular analyses. We describ e continuous, noninvasive monitoring of gene expression in preimplanta tion embryos by using a secreted luminescent reporter, Vargula lucifer ase. Transgene expression profiles were followed by assaying aliquots of culture medium or by direct visualization of Vargula luciferase sec retion from living embryos in real time through photon imaging, With t his approach, it is possible to observe epigenetic modulations of gene expression and to link this over time to the developmental capacity o f individual embryos. In addition, by developing a strategy where expr ession from integrated transgenes is enhanced relative to that from no nintegrated DNA, we provide evidence that rapid detection of transgene integration prior to the blastocyst stage should be possible. Thus, i maging of Vargula luciferase secretion may also be useful in the early screening of embryos, for example, in the production of transgenic li vestock.