Growth of yeast cells expressing aquaporin homologs from Oryza sativa. Δfps1 Δacr3 Δycf1 transformed with the empty vector pYES2.1 (control) or rAQP9, OsNIP2;1, OsNIP2;2 or OsNIP3;2 were spotted at an A600 of 0.01 on medium containing various concentrations of (A) As(III) or (B) As(V) as indicated. Growth was recorded after 4 days at 30°C. (C) OsNIP2;1 mediates uptake of As(III) into yeast. As(III) transport was measured as described in Methods.