A dual-fluorescence reporter in the Eomes locus for live imaging and medium-term lineage tracing.

The T-box transcription factor Eomes (also known as Tbr2) shows short-lived expression in various localized domains of the embryo, including epiblast cells during gastrulation and intermediate progenitor cells in the cerebral cortex. In these tissues Eomes fulfills crucial roles for lineage specification of progenitors. To directly observe Eomes-dependent cell lineages in the living embryo, we generated a novel dual-fluorescence reporter allele that expresses a membrane-bound tdTomato protein for investigation of cell morphology and a nuclear GFP for cell tracing.