Transgenic mouse embryos expressing genetically encoded fluorescent proteins.
Transgenic mouse embryos expressing genetically encoded fluorescent proteins

At present, it remains debated how cells in the mammalian pre-implantation embryo acquire the first developmental differences that can predict lineage-patterning events leading to the blastocyst with two different cell populations: the inner cell mass (ICM), which gives rise to the embryo proper, and the trophectoderm (TE), which will develop into the placenta.

While recent developments in single-cell genetic and genomic techniques have provided much insight in the molecular mechanisms regulating development, these approaches offer limited information of biological dynamics in vivo.

Here, we aim to address the controversy about early lineage allocation in the embryo by taking advantage of one of our transformative technologies - primed conversion: we are combining the power of recently engineered photoconvertible fluorescent proteins for primed conversion (pr-pcFPs) with volumetric and quantitative imaging to extend our previous work of early lineage specification in the early mammalian embryo.

Briefly, our quantitative analysis of the transcription factor (TF) Oct4–paGFP kinetics using the fluorescence decay after photoactivation (FDAP) in vivo assay enabled us to predict pluripotency in the early mammalian embryo as early as at the 4-cell stage before morphological or transcription factor expression level differences occur. Our work will be focused on the following goals: i) investigate the emergence of TF asymmetry in mouse embryos, and ii) discover the molecular mechanisms/factors responsible for the observed TF kinetic differences.