FIG. 1.

Characterization of the double fusion (DF) firefly luciferase (Fluc) and enhanced green fluorescent protein (eGFP) transduced D3 murine embryonic stem cells (mESCs). (A) Schema of the DF reporter gene containing Fluc and eGFP driven by an ubiquitin promoter. (B) Stably transduced mESCs show a robust correlation between cell number and reporter gene activity. BLI of a 24-well plate containing increasing numbers of mESCs are shown above the corresponding graph depicting correlation between cell number and Fluc activity. (C) Flow cytometric analysis of transduced mESCs (D3-DF) shows robust expression of eGFP following transduction with the DF reporter gene, as compared to nontransduced mESCs (D3). (D) Flow cytometric analysis of undifferentiated mESCs shows robust expression of pluripotency marker SSEA-1, but minimal expression of MHC-I (H-2k^b) or MHC-II (I-A^b) antigens. In contrast, cells isolated from a 6-week-old teratoma derived from mESCs (mES-TCs) express low amounts of SSEA-1 but significant levels of MHC-I and MHC-II antigens. Filled histograms represent isotype control antibodies. (E) Phase-contrast images of undifferentiated mESCs and mES-TCs cultured in vitro.