Tg(Tg-cre/ERT2)1Kero

RedE/RedT-recombination was used to insert a cassette encoding tamoxifen-inducible cre (cre/ERT2), an frt-flanked ampicillin selection marker, and the bovine growth hormone polyadenylation signal at the ATG start codon of the thyroglobulin (Tg) gene in a P1 artificial chromosome (PAC). Following recombination, flp-mediated deletion of the ampicillin marker was performed. The verified construct was linearized, then used for injection of C57BL/6 fertilized oocytes. 5/35 pups tested positive for cre by PCR. Founders were tested for specificity and inducibility of cre recombinase by breeding to lacZ reporter mice and treating double mutants with tamoxifen. 4 founders showed cre activity only in the thyroid gland, and one line with strong and homogenous cre activity was chosen for detailed analyses. (J:211398)