Fig. 2

Ligand-dependent Cre-mediated recombination.

(a) Scheme of the ligand-dependent recombination event in cells of the red-to-green reporter line. The chimeric CreER^T2 recombinase is retained in the cytoplasm in the absence of the ligand. After administration of TAM which is converted to the active ligand 4-OHT, CreER^T2 translocates to the nucleus, where it catalyzes the recombination event. (b) Expression of CreER^T2 in the diencephalon of the Tg(pax2a:CreER^T2)^#19 line at early segmentation stages revealed by in situ hybridization. (c) EGFP expression in the diencephalon of double transgenic embryos at 24 hpf bearing the red-to-green reporter and the Tg(pax2a:CreER^T2)^#19 alleles after TAM treatment at mid-gastrulation stages. (d) Expression of CreER^T2 in rhombomere 3 and 5 of the Tg(pax2a:CreER^T2)^#45 line at early segmentation stages revealed by in situ hybridization. (e) EGFP expression in rhombomere 3 and 5 of double transgenic embryos at 24 hpf bearing the red-to-green reporter and the Tg(pax2a:CreER^T2)^#45 alleles after TAM treatment at mid-gastrulation stages. Abbreviations: f, forebrain; h, hindbrain; m, midbrain. Scale bar, 50 μm.