Figure 5. Generation of luciferase reporter mice (mR26CS-Luc).

(A) Flp-RMCE into the modRosa26^FRT locus was performed, replacing the HygR in the modRosa26^FRT ES cells with the FRT/FRTwt-flanked sequence from the Flp-RMCE targeting plasmid. The Flp-RMCE targeting plasmid contains the pCAG promoter followed by a LoxP-flanked (floxed) STOP cassette (STOP2), the luciferase cDNA and a NeoR cassette, flanked as a group by FRT3/FRTwt sites. Successfully targeted ES cells were used to generate mR26CS-Luc mice. After crossing mR26CS-Luc mice with Cre mice, ubiquitous or tissue-restricted luciferase reporter expression can be obtained to monitor reporter expression in living mice upon Luciferin injection. Using Xenogen imaging, adult mR26CS-Luc/CMV-Cre mice show ubiquitous luciferase activity throughout the body (B), while mR26CS-Luc/AlbCre mice show luciferase activity restricted to the liver upon Luciferin injection (C). Luciferin-injected mR26SC-Luc control mice never showed luciferase activity.