Illustrative experiments. (A) Water transport. After incubation in plain water, an oocyte expressing AQP1 and an oocyte expressing AQP10 were microphotographed at different time points for cell volume measurements. (B) Expression of wild-type and mutant AQPs by Western blot analyses. Samples correspond to cell surface proteins detected with an anti-AQP1 Ab (left) or an anti-AQP10 Ab (right). In each panel, water-injected oocytes were used as negative controls. (C) Immunofluorescence experiments. Cryosections postfixed in paraformaldehyde were obtained from AQP-expressing oocytes after a 3-d incubation in medium B1 at 18°C. Wild-type and mutant AQPs were detected with an anti-AQP1 Ab (left) or an anti-AQP10 Ab (right). For each Ab, water-injected oocytes were used as negative controls. Micrographs were taken under confocal microscopy and are shown in the panel for some of the AQPs: (top left) water, (second left) AQP1_1-10-1, (third left) AQP1_{LGRND→IFATY}, (bottom left) AQP1_L84C, (top right) water, (second right) wild-type AQP10, (third right) AQP10_N208Y, and (bottom right) AQP10_G62F/G202H. Note that each of the micrographs is ~300 μm in actual width.