The observation that exposure of the leaf canopy to increasing concentrations of CO(2) (100-400 mul/l) decreases the influx of nitrate to the leaf blades, but not to the roots or stalks (largely leaf sheaths), was reconfirmed using (15)NO(3) (-). Decreases in leaf nitrate supply were associated with decreases in induction of nitrate reductase, thus supporting the view that the influx of nitrate...

The tellurium oxyanion tellurite (TeO3 (2-)) is extremely harmful for most organisms. It has been suggested that a potential bacterial tellurite resistance mechanism would consist of an enzymatic, NAD(P)H-dependent, reduction to the less toxic form elemental tellurium (Te(0)). To date, a number of enzymes such as catalase, type II NADH dehydrogenase and terminal oxidases from the electron trans...

Glycine, a photorespiratory intermediate, enhanced the in vivo reduction of nitrate in barley (Hordeum vulgare L.) leaf slices, when included in the assay medium. Isonicotinyl hydrazide, an inhibitor of glycine oxidation, partially reduced NO(2) (-) production. The enhancement caused by glycine treatment was reversed by isonicotinyl hydrazide when both were present together in the medium. Simil...

Ascorbic acid and hemoglobins have been linked to nitric oxide metabolism in plants. It has been hypothesized that ascorbic acid directly reduces plant hemoglobin in support of NO scavenging, producing nitrate and monodehydroascorbate. In this scenario, monodehydroascorbate reductase uses NADH to reduce monodehydroascorbate back to ascorbate to sustain the cycle. To test this hypothesis, rates ...

1. In rice seedlings synthesis of methyl viologen-nitrite reductase was stimulated by light, as was that of NADH-nitrate oxidoreductase (EC 1.6.6.1). A small residual effect of light on the synthesis of the enzymes persisted in the dark for a short time. 2. In etiolated seedlings exposed to light and nitrate, a lag period of 3 h was necessary before enzyme synthesis commenced, whereas in green ...

A cDNA clone was isolated from a maize (Zea mays L. cv W64AxW183E) scutellum lambdagt11 library using maize leaf NADH:nitrate reductase Zmnr1 cDNA clone as a hybridization probe; it was designated Zmnr1S. Zmnr1S was shown to be an NADH:nitrate reductase clone by nucleotide sequencing and comparison of its deduced amino acid sequence to Zmnr1. Zmnr1S, which is 1.8 kilobases in length and contain...

Assimilatory nitrate reductase was particle-bound in extracts from Azotobacter vinelandii. Nitrate reduction by particle fractions was dependent on NADPH and a particle-bound electron carrier. When the enzyme was solubilized from the particles by treatment with detergents, the particle-bound electron carrier could be substituted by ferredoxin or flavodoxin. Flavodoxin reduced at the expense of ...

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...

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...

Catasetum fimbriatum is an epiphytic orchid from South America that has been used for 15 years as a model plant for metabolic and developmental studies in our laboratory. In this work, C. fimbriatum plants were aseptically grown with 6 mol m(-3) of either glutamine or inorganic nitrogen forms (NO(3)(-):NH(4)(+) ratios). The highest biomass accumulation was found in plants supplied with glutamin...