Figure 4.

AtNramp expression increases Cd²⁺ sensitivity and Cd²⁺ content in yeast. (A) Growth of INVSc1 yeast cells expressing AtNramp1, AtNramp3, or AtNramp4 on plates containing synthetic dextrose-ura buffered to pH 6 with 50 mM Mes without CdCl₂ (Left) or supplemented with 10 μM CdCl₂ (Right). The plates were incubated at 30°C for 3 days before photography. (B) Cd²⁺ content of INVSc1 yeast cells expressing AtNramp1, AtNramp3, or AtNramp4 grown for 24 h in liquid synthetic dextrose-ura supplemented with 3 μM Cd²⁺, as measured by the uptake of ¹⁰⁹Cd²⁺. INVSc1 yeast cells were transformed either with the empty pDR195 vector, or with pDR195 containing the AtNramp1, AtNramp3, or AtNramp4 cDNA. Transformed strains were grown overnight in synthetic dextrose-ura. The cultures were then spotted on plates or inoculated in 10 ml synthetic dextrose-ura at an OD of 0.01. Error bars represent the SE from four independent experiments (P < 0.03, 0.06, and 0.07 for AtNramp1, AtNramp3, and AtNramp4, respectively).