General Information

Development

The cloned expression vector contains the CAG promoter and a LoxP-tdTOMATO (an N-terminal membrane-tagged version of tdTOMATO) -pA-LoxP-EGFP (an N-terminal membrane-tagged version of EGFP) -pA cassette expression vector. Positive Rosa26 knock-in ES mice were obtained using the method of cellular embryonic microinjection. These mT/mG mice can be used as a Cre reporter line; they express red fluorescence before Cre-mediated recombination and green fluorescence after in a wide range of cell and tissue types. The viability of homozygous mice is normal.

tdTomato (mT) is flanked by loxP sites and expresses strong red fluorescence in all detected tissues and cell types. Compared to wild-type mice, the red and green double-fluorescent mice exhibit red fluorescence in their tails or throughout their bodies.

B6-mT/mG Mice Applications

1. This dual-fluorescence system allows for the direct, real-time observation of recombined and non-recombined cells at the single-cell resolution, providing an internal control for the phenotypic analysis of Cre-induced mosaic mutants and offering a second marker for lineage tracing applications.

2. The localization of the fluorescent proteins on membrane structures outlines cell morphology and allows for the resolution of fine cellular processes.

3. The expression of tdTomato and EGFP can be precisely controlled through the Cre recombinase system. In the absence of Cre recombinase, tdTomato is expressed by default; in the presence of Cre recombinase, recombination mediated by the LoxP sites removes tdTomato and initiates the expression of EGFP. This mechanism allows researchers to track the lineage and fate of specific cells.

Reference

1. Muzumdar MD, Tasic B, Miyamichi K, et al. A global double-fluorescent Cre reporter mouse. Genesis. 2007, 45(9):593-605.