Synthesis of nitrate reductase protein and increases in nitrate reductase activity occurred in cultures of the yeast Candida nitratophila when they were incubated in medium containing ammonium nitrate. Similar treatment with glutamine plus nitrate resulted in little increase in nitrate reductase activity, in cultures grown previously with reduced nitrogen compounds, and decreases in enzyme acti...

The effect of nitrogen form (NH(4)-N, NH(4)-N + NO(3) (-), NO(3) (-)) on nitrate reductase activity in roots and shoots of maize (Zea mays L. cv INRA 508) seedlings was studied. Nitrate reductase activity in leaves was consistent with the well known fact that NO(3) (-) increases, and NH(4) (+) and amide-N decrease, nitrate reductase activity. Nitrate reductase activity in the roots, however, co...

Desiccation of 8- to 13-day-old seedlings, achieved by withholding nutrient solution from the vermiculite root medium, caused a reduction in nitrate reductase activity of the leaf tissue. Activity declined when leaf water potentials decreased below -2 bars and was 25% of the control at a leaf water potential of -13 bars. Experiments were conducted to determine whether the decrease in nitrate re...

Synthesis and turnover of nitrate reductase molecules and soluble proteins of tobacco XD cells were studied by labeling pre-existing proteins with 14C-arginine to make them radioactive and with 99 atom % ‘5N to increase their buoyant density. The cells were then transferred to medium in which new proteins were synthesized from 14N and were radioactively labeled with 3H-arginine. The breakdown o...

nitrate is one of the major sources of nitrogen for the growth of plants. it is taken up by plant roots and transported to the leaves where it is reduced to nitrite in the. the main objective of this research was to investigate stimulatory effects of sodium nitrate, potassium nitrate, ammonia and urea on the production/generation of the nitrate reductase mrna in triticum aestivum plants. the pl...

Germinating cotton (Gossypium hirsutum L. cv. Deltapine 16) cotyledons developed two peaks of in vitro nitrate reductase activity; the first was stable in vitro and appeared 24 hours after imbibition; and the second, which was extremely labile in vitro, began to develop after the seedlings had emerged and developed chlorophyll. Nitrite reductase activity peaked only after the seedlings had emer...

A barley (Hordeum vulgare L.) mutant, nar1a (formerly Az12), deficient in NADH nitrate reductase activity is, nevertheless, capable of growth with nitrate as the sole nitrogen source. In an attempt to identify the mechanism(s) of nitrate reduction in the mutant, nitrate reductase from nar1a was characterized to determine whether the residual activity is due to a leaky mutation or to the presenc...

Levels of nitrate reductase activity (EC 1.9.6.1.) as high as 11 mumoles nitrite produced/hour gram fresh weight were found in barley (Hordeum vulgare cv. Compana) roots grown under low oxygen conditions. Roots of plants given identical treatment under sterile conditions did not develop the high levels of nitrate reductase activity. The results suggest that the buildup of particulate, reduced v...

Molybdenum is absolutely required for the nitrate-reducing activity of the nicotinamide adenine dinucleotide nitrate reductase complex isolated from Chlorella fusca. The whole enzyme nicotinamide adenine dinucleotide nitrate reductase is formed by cells grown in the absence of added molybdate, but only its first activity (nicotinamide adenine dinucleotide diaphorase) is functional. The second a...

NADPH nitrate reductase activity in higher plants has been attributed to the presence of NAD(P)H bispecific nitrate reductases and to the presence of phosphatases capable of hydrolyzing NADPH to NADH. To determine which of these conditions exist in barley (Hordeum vulgare L. cv. Steptoe), we characterized the NADH and NADPH nitrate reductase activities in crude and affinity-chromatography-purif...