Fig 1.

Permanent cell labeling by doxycycline-inducible recombination in triple-transgenic mice. (a) Triple-transgenic mice were produced in which doxycycline activates rtTA expressed under control of the SP-C promoter. The rtTA then activates Cre that excises and religates the target gene, inactivating β-galactosidase (lacZ), and permanently labeling the cell by activating AP or GFP in the ZAP or ZEG mice, respectively. Dams were treated with doxycycline from E6.5 to day of killing. (b) Whole mount AP staining on an E13.5 lung from an SP-C-rtTA/tetO-Cre/ZAP embryo. Most intrapulmonary epithelial cells and some extrapulmonary airway cells stained for AP. (c) GFP fluorescence in trachea from an SP-C-rtTA/tetO-Cre/ZEG transgenic mouse on PN7. GFP-positive cells are organized in a linear fashion along the trachea and numbers of labeled cells increased from proximal to peripheral extrapulmonary airways (lower right corner, magnification, ×5). (d) Widespread GFP fluorescence was seen in lung parenchyma from an SP-C-rtTA/tetO-Cre/ZEG mouse on PN7. (Bars = 1 mm.)