Tissue and Single-cell Determination

For tissue determinations, we assayed tissue lysate using a commercially available kit (Abcam Inc.). For single cell determinations, we transfected alveoli with the probe, GlnK-GFP (Perceval, gift of Dr. G. Yelen, Harvard University)^{35 (link)}. We complexed the Perceval plasmid (2.5 µg µl⁻¹) with liposomes (20 µg µl⁻¹, 100-nm pore size; DOTAP, Avanti Lipids) that we suspended in sterile PBS to a final plasmid concentration of 1 µg µl⁻¹. We gave mice intranasal instillations of the plasmid-liposome mixture (50 µl), then 48 h later we imaged Perceval fluorescence in alveoli. For control, we transfected empty vector.