Fig. 4. Functional expression of tilapia AQP3 in Xenopus oocytes. (A) Representative data of osmotic oocyte volume V changes in control oocytes (control), tilapia AQP3 cRNA-injected oocytes (AQP3), those with 0.3 mmol l^–1 HgCl₂ treatment (AQP3+Hg) and those with HgCl₂ treatment followed by 5 mmol l^–1 ß-mercaptoethanol (AQP3+Hg+2ME). (B) Osmotic water permeability (Pf) in different experimental groups. Values are means ± S.E.M. Values marked with different letters are significantly different from one another at P<0.01.