ZmDUR3 mediates urea uptake in S. cerevisiae . Growth of the urea uptake-deficient strain YNVW1 expressing ZmDUR3 and ZmDUR3
. The mutant YNVW1 transformed with the vector pDR197 (first row), and pDR197 carrying ORFs ZmDUR3 (middle row) or ZmDUR3
(third row). Medium contained 0.5% of ammonium sulphate (SD) or urea at three different concentrations (1, 2 or 3 mM urea) as a sole nitrogen source. Pictures were taken after 5 days of incubation.