Hemizygous IRG transgenic mice are viable and fertile, with widespread expression of a loxP-flanked optimized red fluorescent protein variant (DsRed-Express) directed to embryonic and adult tissues by the CAG promoter prior to exposure to Cre recombinase. When bred to cre-expressing mice, the resulting offspring have the DsRed-Express cassette deleted in the cre-expressing tissue(s), allowing expression of the enhanced green fluorescent protein (EGFP) cassette located just downstream. These IRG transgenic mice are a double-fluorescent, Cre-reporter strain; with widespread expression of red fluorescence prior to Cre recombinase exposure, and green fluorescence following cre-mediated recombination in a pattern determined by cre expression, and should provide a versatile tool for analyzing complex cellular relationships in a wide variety of tissues.
For example, when using IRG transgenic mice along with Nestin-Cre mice (see Stock No. 003771), red and green native fluorescence can be imaged simultaneously in thick tissue sections by confocal microscopy; thus allowing for analysis of complex reconstructions suitable for studying neuronal morphologies as well as neurovascular interactions in brain.
