Fig. 3. Expression of AQP-x5 in Xenopus oocytes. (A) Osmotic water permeability (Pf) was calculated from the initial rate of oocyte swelling. Oocytes were microinjected with water or cRNA encoding AQP-x5. A portion of the AQP-x5-injected oocytes was incubated with 0.3 mmol l^-1 HgCl₂. All data shown are given as the mean ± s.e.m. of measurements from 8-11 oocytes (as indicated above the bars) in each experimental group. ^*P<0.001 vs water, ^**P<0.001 vs AQP-x5. (B) Immunofluorescence images of AQP-x5 protein in AQP-x5-injected oocytes. (1) After completion of the swelling experiments, immunoreactive AQP-x5 substances are visible, predominantly in the plasma membrane. (2) The corresponding Nomarski differential interference image. (3) In the absorption test, positive immunoreactive substances obtained with anti-AQP-x5 are nearly eliminated at background levels in AQP-x5-injected oocyte. (4) As in 3, only background levels are seen in the water-injected oocyte with anti-AQP-x5. Arrowheads indicate plasma membrane. Scale bar, 50 µm.