Inflammation in sinuses and ears of Cby^−/− mice. (A and B) H&E staining of sinus sections from adult Cby^+/+ (A) and Cby^−/− (B) mice. Asterisks label accumulation of protein-rich fluid. (C and D) H&E staining of middle ear sections from Cby^+/+ (C) and Cby^−/− (D) mice. The asterisk indicates accumulation of inflammatory cells in protein-rich fluid. (E and F) H&E staining of sinus sections of the control (E) and Cby^−/− (F) adult mice infected with P. aeruginosa. Upon intranasal infection, Cby^−/− animals failed to clear bacteria and, at 72 h, developed a severe exudative sinusitis characterized by abundant accumulation of inflammatory cells and bacterial debris admixed in protein-rich fluid (asterisks). (G) Quantification of CFUs in the lungs of infected mice. A one-way analysis of variance test did not reveal a difference between three groups of mice (P = 0.6079). Results for individual mice are shown by dots and plotted on a log scale. Lines represent the mean number for each genotype. (H) Data shown are short circuit currents (Isc) or change in short circuit currents in response to amiloride, UTP, or forskolin added sequentially to the preparations. Open bars represent control tracheas (n = 6), and shaded bars represent Cby^−/− tracheas (n = 4). Results are represented as means ± SEM. (I) MCT in the nasopharynx of adult control (n = 6) and Cby^−/− (n = 4) mice. Data are represented as means ± SEM. KO, knockout. Bars, 500 µm.