Oxygen had an immediate and reversible inhibitory effect on nitrate respiration by denitrifying cultures of Pseudomonas aeruginosa. Inhibition of nitrate utilization by oxygen appeared to be at the level of nitrate uptake, since nitrate reduction to nitrite in cell extracts was not affected by oxygen. The degree of oxygen inhibition was dependent on the concentration of oxygen, and increasing n...

BACKGROUND AND AIMS Plant shoots form a sink for NH3, and are able to utilize it as a source of N. NH3 was used as a tool to investigate the interaction between foliar N uptake and root N uptake. To what extent NH3 can contribute to the N budget of the plant or can be regarded as a toxin, was investigated in relation to its concentration and the N supply in the root environment. METHODS Brass...

The sessile lifestyle of plants constrains their ability to acquire mobile nutrients such as nitrate. Whereas proliferation of roots might help in the longer term, nitrate-rich patches can shift rapidly with mass flow of water in the soil. A mechanism that allows roots to follow and capture this source of mobile nitrogen would be highly desirable. Here, we report that variation in nitrate conce...

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...

The uptake of nitrogen (N) by roots is known to change with supply in a manner that suggests that the N status of plants is somehow sensed and can feedback to regulate this process. The most abundant source of N in soils for crops is nitrate. Uptake systems for nitrate, ammonium, and amino acids are present in the roots of most plants including crops. As nitrate is assimilated via conversion to...

Received: 17, March, 2015 Final Accepted: 17, April, 2015 Published Online: 25, April, 2015 This study examined the effect of 25.0 and 50.0 μM arsenic (As) on nitrate uptake in Chlorella vulgaris when grown under different nitrogen regime. The changes in nitrate uptake of test alga exposed to As under different N regimes show that the control cultures of test alga showed maximum nitrate uptake ...

Pedospheric nitrate uptake is closely integrated with the nitrogen (N) status and demand of the whole tree. Signaling substances communicating the N demand of the shoot to the roots are required in an integrated regulatory system. Besides phloem mobility, such signal compounds must have the potential to repress or increase nitrate uptake either at the transcriptional or post-transcriptional lev...

Root nitrate uptake is well known to adjust to the plant's nitrogen demand for growth. Long-distance transport and/or root storage pools are thought to provide negative feedback signals regulating root uptake. We have characterized a vascular specific nitrate transporter belonging to the high-affinity Nitrate Transporter2 (NRT2) family, OsNRT2.3a, in rice (Oryza sativa ssp. japonica 'Nipponbare...

0305-7364/0 * For corre bcgn.grignon. There is still disagreement about whether crop growth rate or soil nitrate concentration control nitrogen absorption by crops under ®eld conditions. The in ̄uence of these factors on the control of N uptake rate was examined in the absence of water stress, using data on dry matter production, above-ground nitrogen accumulation and soil nitrate concentration ...

[1] Global radiative forcing of nitrate and ammonium aerosols has mostly been estimated from aerosol concentrations calculated at thermodynamic equilibrium or using approximate treatments for their uptake by aerosols. In this study, a more accurate hybrid dynamical approach (HDYN) was used to simulate the uptake of nitrate and ammonium by aerosols and the interaction with tropospheric reactive ...