An Arabidopsis mutant (rnc1) with a mutation at the 313th nucleotide from the translational start site of AtNRT3.1 was isolated. The mutation resulted in the replacement of aspartate by asparagine at the 105th amino acid in a region conserved among higher plants. In the rnc1 mutant, both the nitrate concentrations in plants and the nitrate uptake from the medium were <13% compared with those of...

This article discusses how nitrate assimilation is integrated with nitrate uptake, with ammonium assimilation and amino acid synthesis, with pH regulation, and with the sugar supply in tobacco leaves. During the first part of the light period, nitrate assimilation exceeds nitrate uptake by 2-fold and ammonium assimilation by 50%, leading to rapid depletion of nitrate and accumulation of ammoniu...

Identification of mechanisms that decrease cadmium accumulation in plants is a prerequisite for minimizing dietary uptake of cadmium from contaminated crops. Here, we show that cadmium inhibits nitrate transporter 1.1 (NRT1.1)-mediated nitrate (NO3 (-)) uptake in Arabidopsis (Arabidopsis thaliana) and impairs NO3 (-) homeostasis in roots. In NO3 (-)-containing medium, loss of NRT1.1 function in...

G udrun D. Trogisch*, H elm ut Köcher**, and W olfram R. Ullrich* * Institut für Botanik, Technische Hochschule, Schnittspahnstraße 3. D-6100 Darmstadt, Bundesrepublik Deutschland ** Hoechst AG, D-6230 Frankfurt 80. Bundesrepublik Deutschland Z. Naturforsch. 44c, 33 — 38 (1989); received July 13/November 11, 1988 Dedicated to Professor Wilhelm Simonis on the occasion o f his 80th birthday Ammon...

The Colorado River is contaminated with low levels of perchlorate. Perchlorate has the potential to disrupt thyroid function by inhibiting the uptake of iodide. Brassica are rich sources of thiocyanate and nitrate, also inhibitors of iodide uptake. This study was conducted to estimate potential human exposure to perchlorate, thiocyanate, and nitrate from Brassica sp. irrigated with Colorado Riv...

The effects of CO(2)-limited photosynthesis on (15)NO(3) (-) uptake and reduction by maize (Zea mays, DeKalb XL-45) seedlings were examined in relation to concurrent effects of CO(2) stress on carbohydrate levels and in vitro nitrate reductase activities. During a 10-hour period in CO(2)-depleted air (30 microliters of CO(2)/ per liter), cumulative (15)NO(3) (-) uptake and reduction were restri...

Dinoflagellates readily use diverse inorganic and organic compounds as nitrogen sources, which is advantageous in eutrophied coastal areas exposed to high loads of anthropogenic nutrients, e.g., urea, one of the most abundant organic nitrogen substrates in seawater. Cell-to-cell variability in nutritional physiology can further enhance the diversity of metabolic strategies among dinoflagellates...