Some eukaryotes, such as plant and fungi, are capable of utilizing nitrate as the sole nitrogen source. Once transported into the cell, nitrate is reduced to ammonium by the consecutive action of nitrate and nitrite reductase. How nitrate assimilation is balanced with nitrate and nitrite efflux is unknown, as are the proteins involved. The nitrate assimilatory yeast Hansenula polymorpha was use...

In plants, the nitrate transporters, NRT1.1 and NRT2.1, are mainly responsible for nitrate uptake. Intriguingly, both nitrate transporters are located in a complementary manner in different cells layers of the mature root suggesting that their coordination should occur during nitrate uptake and plant growth. This hypothesis was examined on 5-d-old rape seedlings grown on agar medium supplemente...

Excretion of nitrite during nitrate assimilation by phytoplankton is examined in relation to estimates of new production. Evidence from the literature indicates that nitrite excretion is exhibited by a wide variety of phytoplankton species in cultures and can represent up to 25, 45 and 50"0 of nitrate uptake in Thalassiosira pseudonana, Prorocentrum minimum and Skeletonema costa turn respective...

Long-distance transport of nitrate requires xylem loading and unloading, a successive process that determines nitrate distribution and subsequent assimilation efficiency. Here, we report the functional characterization of NRT1.8, a member of the nitrate transporter (NRT1) family in Arabidopsis thaliana. NRT1.8 is upregulated by nitrate. Histochemical analysis using promoter-beta-glucuronidase f...

PURPOSE: Backwaters connected to large rivers efficiently retain nitrate and can play an important role in reducing downstream loading to coastal marine environments. However, biotic assimilation and transient storage can account for a significant portion of the nitrate uptake versus denitrification. The fate of this nitrogen (N) pool is largely unknown. Is assimilated nitrate stored temporaril...