A TRE (Tet response element; 318bp) from pTRE-Tight (Clontech), a GCaMP3 coding sequence (1353bp), a WPRE (609bp), and a SV40 poly A signal (189bp) from pTRE-Tight were inserted into a PCR-generated ROSA26 intron sequences and then subcloned into pKOV-KanF for homologous recombination in E. coli carrying the 200kb BAC clone RP23-401D9. (J:256098)