Mycorrhizal plants from a variety of ecosystems have the capacity to take up organic forms of nitrogen, yet the fraction of plant nitrogen demand met by organic N (ON) uptake remains unclear. ON uptake by mycorrhizal plants is a biochemical process that involves multiple steps, including breakdown and uptake of soil ON by mycorrhizal fungi, internal transformation of ON, and transfer of N to th...

In an attempt to more fully understand the dissolved inorganic nitrogen dynamics of the Neuse River estuary, r5NHq+ and 15N0,uptake rates were measured and daily depth-integrated rates calculated for seven stations distributed along the salinity gradient. Measurements were made at 2-3-wk intervals from March 1985 to February 1989. Significant dark NH,+ uptake occurred and varied both spatially ...

Several untested aspects of the regulation of inorganic nutrient uptake were examined using nutrient depletion experiments with the symbiotic coral Stylophora pistillata. The total inhibition of phosphate uptake in artificial seawater lacking sodium indicates the involvement of a sodium/phosphate symporter for the uptake of phosphate across host membranes. Addition of ammonium or nitrate (up to...

Amino acid uptake and utilization of various nitrogen sources (amino acids, nitrite, nitrate and ammonia) were studied in Nostoc ANTH and i ts mu tant (Het(-)Nif(-)) isolate defective in heterocyst formation and N2-fixation. Both parent and its mutant grew at the expense of glutamine, asparagine and arginine as a source of fixed-nitrogen. Growth was better in glutamine-and asparagine-media as c...

Nitrogen responsiveness of three-finger millet genotypes (differing in their seed coat colour) PRM-1 (brown), PRM-701 (golden), and PRM-801 (white) grown under different nitrogen doses was determined by analyzing the growth, yield parameters and activities of nitrate reductase (NR), glutamine synthetase (GS), glutamate synthase; GOGAT, and glutamate dehydrogenase (GDH) at different developmenta...

Measurement of pulmonary gas uptake and elimination is often performed, using nitrogen as marker gas to measure gas flow, by applying the Haldane transformation. Because of the inability to measure nitrogen with conventional equipment, measurement is difficult during inhalational anesthesia. A new method is described, which is compatible with any inspired gas mixture, in which fresh gas and exh...

Climate and terrestrial biosphere models consider nitrogen an important factor in limiting plant carbon uptake, while operational environmental models view nitrogen as the leading pollutant causing eutrophication in water bodies. The community Noah land surface model with multiparameterization options (Noah-MP) is unique in that it is the next-generation land surface model for the Weather Resea...

The uptake of methylamine as the sole nitrogen, but not carbon, source by Pseudomonas sp. strain MA was investigated. Under these growth conditions, a high-affinity, low-capacity uptake system was present having a Km of 16 microM and Vmax of 2 nmol.min-.mg (dry weight) of cells that was competitively inhibited by ammonium chloride. The transport system was induced by growth on succinate with me...

Nitrogen availability is often a limiting factor in plant growth and crop productivity, but the application of nitrogen fertilizers to counteract nitrogen deficiencies can have detrimental economic and environmental effects. Therefore, it is important to understand mechanisms of nitrogen uptake, transport, and utilization within the plant. The most common form in which nitrogen is assimilated b...