Arabidopsis aquaporins mediate arsenic influx into yeast as monitored by growth and transport assays. (A) Growth assay. Plasmids expressing aquaporin homologs rAQP9, AtNIP5;1, Atnip5;1Δ2–67, AtNIP6;1, Atnip6;1Δ2–29, Atnip6;1Δ2–69, AtNIP7;1 or Atnip7;1Δ
2–35 as well as an empty vector control (pYES2.1) were transformed into Δfps1 Δacr3 Δycf1. The transformants were grown in liquid medium and 10-fold serial dilutions of the cultures were spotted on agar plates with or without arsenite (As(III)). Growth was monitored after 2 to 3 days at 30°C. (B) As(III) uptake. The Δfps1 Δacr3 Δycf1 mutant harboring the empty pYES2.1 plasmid or plasmids expressing the indicated proteins were exposed to As(III) and intracellular arsenic levels were determined as described in Methods. The data shown represent the average of at least three independent experiments and the error bars represent the standard deviation.