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.
In an attempt to offer alleles on well-characterized or multiple genetic backgrounds, alleles are frequently moved to a genetic background different from that on which an allele was first characterized. It should be noted that the phenotype could vary from that originally described. We will modify the strain description if necessary as published results become available.
