The Uptake of Nitrite by the DiatomPhaeodactylum: Interactions between Nitrite and Nitrate

Abstract
Freshly harvested ammonium-grown cells of the diatom Phaeodactylum tricornutum cannot take up nitrite but they acquire the ability to do so after a period (about 3 h) of nitrogen deprivation under conditions that allow photosynthesis. Addition of cycloheximide (1.0 μg ml−1) prevents development as does incubation in Na+ or K+-free medium. Nitrite uptake is dependent on the presence of Na+ in the medium and is inhibited by ammonium and nitrite uptake but it is concluded that the inhibition of nitrite uptake by nitrate is not of the competitive type.