<p>OBJECTIVETo study the effect of NH4(+)-N/NO3(-)-N ratios in the applied supplementary fertilizer on the growth, nitrogen metabolis related enzymes activity and photosynthetic characteristics of Isatis indigotica.p><p>METHODThe sand culture experiment was conducted, and seedling of I. indigotica was fertilized with the mixed nutrition that containing the Hoagland's macro elements and the Aron's micro elements, the additional 63 mmol N was supplementary with the NH4(+)-N/NO3(-)-N ratio of 100:0, 75:25, 50:50, 25:75 and 0:100.p><p>RESULTThe biomass of I. indigotica increased at first when the supplementary N of NH4(+)-N/NO3(-)-N ratio changed from 100:0 to 50:50 and decreased afterwards. The maximum value was at 50:50 and the minimum at 100: 0. With increasing the ratio of NO3(-)-N, the activity of nitrate reductase and glutamine synthetase increased and then decreased and the relationship between the activity and the ratio could be described with an approximate parabola curve. The net photosynthetic rate of I. indigotica was the highest at the NH4(+)-N/NO3(-)-N ratio of 75:25 and the lowest at 100:0.p><p>CONCLUSIONIncreasing the NO3(-)-N ratio properly was beneficial to promote the growth and improve the activity of nitrate reductase and glutamine synthetase and net photosynthetic rate of I. indigotica.p>
Biomass ; Fertilizers ; analysis ; Isatis ; chemistry ; enzymology ; growth & development ; metabolism ; Nitrate Reductase ; metabolism ; Nitrate Reductases ; metabolism ; Nitrates ; analysis ; metabolism ; Nitrogen ; analysis ; metabolism ; Photosynthesis ; Plant Proteins ; metabolism ; Quaternary Ammonium Compounds ; analysis ; metabolism

OBJECTIVE: The aim of this study was to measure circulating levels of nitric oxide metabolites (nitrites) in the uteroplacental, fetoplacental, and peripheral circulation in women with normal pregnancy and preeclampsia. METHODS: Two groups of pregnant women were included : 20 patients with preeclampsia and 18 normotensive women. At cesarean, blood samples were taken from the antecubital vein and uterine vein draining the placental site before delivery of the baby, and the umbilical vein after delivery of the baby. Plasma nitric oxide concentrations were determined with the Griess reaction by measuring combined oxidation products of nitric oxide, plasma nitrite and nitrate after reduction with nitrate reductase. RESULTS: Significantly higher serum nitrite concentrations were found in umbilical (46.53+/-22.01 vs. 17.51+/-7.43 M/L, p<0.05), uterine (51.78+/-14.19 vs. 21.23+/-11.6 M/L, p<0.05) and antecubital (66.41+/-20.87 vs. 21.26+/-9.54 M/L, p<0.05) venous plasma in the preeclamptic group compared with the control group. CONCLUSION: We observe higher levels of nitirc oxide metabolites in the uteroplacental, fetoplacental, and peripheral circulation in women with preeclampsia than in normal pregnancy. These results support the hypothesis that increased nitric oxide production may be a compensatory response to improve blood flow and offset the pathologic effects of preeclampsia.
Female ; Humans ; Nitrate Reductase ; Nitric Oxide* ; Plasma* ; Pre-Eclampsia* ; Pregnancy ; Pregnant Women ; Umbilical Veins ; Veins

OBJECTIVE: This study is directed to determine whether the concentrations of nitrate and nitrite, metabolites of nitric oxide, in vaginal secretions could be used to predict a premature delivery. METHOD: A total of 60 pregnant women from March, 2000 to February, 2001 received continuous prenatal care and underwent delivery in our hospital was enrolled in the study. Gestational age was ranged between 20 and 37 weeks. Those patients were divided into four groups according to clinical parameters such as preterm labor, premature rupture of membranes and premature delivery. Specimens were obtained by thorough washing of vagina with 5 mL sterile physiologic sodium chloride solution for determination of nitric oxide metabolites. The total nitrate and nitrite concentration was determined by treatment with nitrate reductase followed by the Griess reaction. RESULTS: Subjects were divide into four groups (group I, no preterm labor and term delivery[n=19]; group II, preterm labor and term delivery[n=12]; group III, preterm labor and consequent premature delivery[n=6]; Group IV, preterm labor with premature rupture of membranes and consequent premature delivery[n=23]). Total nitrate and nitrite concentrations in group II-IV (62.2+/-50.3micromol/L in group II, 113.3+/-77.0micromol/L in group III, 101.9+/-72.4micromol/L in group IV) were significantly higher than the concentration in Group I (9.4+/-11.9micromol/L). From the receiver operating characteristic curve in the prediction of premature delivery, we set 27.6micromol/L as a cut-off value in this study. Sensitivity, specificity, positive predictive value, and negative predictive value were 71.9%, 78.6%, 79.3%, and 71.0%, respectively. CONCLUSION: Patients with premature delivery do have increased nitric oxide metabolites in vaginal secretions. These results suggest that nitric oxide may be involved in the initiation of cervical ripening and used as a predictor of premature delivery.
Cervical Ripening ; Female ; Gestational Age ; Humans ; Membranes ; Nitrate Reductase ; Nitric Oxide ; Obstetric Labor, Premature ; Pregnancy ; Pregnant Women ; Prenatal Care ; ROC Curve ; Rupture ; Sensitivity and Specificity ; Sodium Chloride ; Vagina

<p>OBJECTIVETo establish a rapid, inexpensive, and simple drug susceptibility test (DST) for Mycobacterium tuberculosis (M. tb) and evaluate its feasibility.p><p>METHODWe used nitrate reductase combined with mycobacteriophage assay (PhaB-NRA) to test 49 clinical M. tb isolates of, and the results were compared with those of PhaB-NRA and traditional absolute concentration method.p><p>RESULTSThe sensitivity, specificity, and accuracy of PhaB-NRA for rifampicin were 89.1%, 91.67%, and 89.8%; on the contrary, those of isonicotinyl hydrazide were 86.21%, 90.0%, and 87.8%, respectively. The coincidence between PhaB-NRA and traditional assay were 0.746 for rifampicin and 0.750 for isonicotinyl hydrazide.p><p>CONCLUSIONSPhaB-NRA is an inexpensive, rapid, and simple DST method. It is a promising rapid screening technique for DST of M. tb.p>
Anti-Bacterial Agents ; pharmacology ; Biological Assay ; methods ; Humans ; Microbial Sensitivity Tests ; methods ; Mycobacteriophages ; physiology ; Mycobacterium tuberculosis ; drug effects ; Nitrate Reductase ; metabolism ; Rifampin ; pharmacology ; Sensitivity and Specificity

<p>OBJECTIVETo establish a rapid method for testing drug sussceptibility on Mycobacterium tuberculosis.p><p>METHODSTaking absolute Concentration method for drug susceptibility testing of M. tuberculosis as the "gold standard", we examined the drug-resistant of M. tuberculosis strain with nitrate reducrase assay (NRA) and the drug-resistant of M. tuberculosis germ in sputum with NRA.p><p>RESULTSNRA and absolute concentration method was basically comparable with NRA susceptibility as 96.5% and the specificity was 100%, When comparing with traditional absolute concentration method, NRA could shorten the time about 3 weeks. Using NRA to test the drug-resistant of M. tuberculosis germ in sputum, its susceptibility was more than 66.7% and specificity was 100%, within 10-20 days.p><p>CONCLUSIONNRA could be used as a rapid drug susceptibility testing on M. tuberculosis.p>
Anti-Bacterial Agents ; pharmacology ; Drug Resistance, Bacterial ; Enzyme Assays ; methods ; Humans ; Microbial Sensitivity Tests ; methods ; Mycobacterium tuberculosis ; drug effects ; pathogenicity ; Nitrate Reductase ; metabolism ; Sputum ; microbiology

The effect of outer spermine on cell growth, accumulation of polysaccharides and utilization of nutrient together with the intracellular polyamine contents were investigated in suspension cultures of protocorm-like bodies from Dendrobium huoshanense. The results indicated that spermine at 0.6 mmol/L was the most effective in increasing cell growth and polysaccharide synthesis. The specific growth rate of cell increased from 0.046d(-1) to 0.054d(-1), and the maximum dry weight and polysaccharide production reached 32.4g DW/L and 2.46g/L respectively, which were 1.32-fold and 1.31-fold that of the control on day 30. The titres of intracellular free polyamines were higher in the cultures treated with spermine than that of the control. Invertase and nitrate reductase activities were found to increase significantly in the cultured cells treated with spermine, which was beneficial to the utilization of carbon and nitrogen source.
Biomass ; Carbon ; metabolism ; Cell Proliferation ; drug effects ; Cells, Cultured ; Dendrobium ; cytology ; drug effects ; metabolism ; Nitrate Reductase ; metabolism ; Nitrogen ; metabolism ; Plant Proteins ; metabolism ; Plant Stems ; cytology ; drug effects ; metabolism ; Polyamines ; metabolism ; Polysaccharides ; biosynthesis ; Spermine ; pharmacology ; Time Factors ; beta-Fructofuranosidase ; metabolism

An experiment was carried out to study the allelopathic effects of Coptis chinensis fibrous root extracts (CRE) on the germination and seedling growth of Vicia faba and Pisum sativum in order to alleviate the allelopathic effects and increase land productivity. The seeds of both garden pea (P. sativum) and broad been (V. faba) were germinated in CRE solution of various concentrations, the germination rate, seedling growth and related physiological indexes were measured. The result indicated that there were no significant effects of CRE in low concentrations on seed germination, including both the rate and index, and seed vitality and membrane permeability. With the increment of CRE concentrations, however, the high seed membrane permeability and germination inhibition were observed. For example, the germination rates were reduced by 23.4% (P. sativum) and 9.5% (V. faba), respectively, in CRE solution with 800 mg . L-1. Simultaneously, soluble sugars and the free amino acids in the seeds were lower than those in the control (without CRE) after soaking seeds in CRE solutions. In addition, the seedling growth and nitrate reductase activity were stimulated by CRE at low concentrations in contrast to high concentrations which behaved otherwise and inhibited the nutrient utilization in endosperm. Therefore, the large amount of allelochemicals released from the roots and remains of C. chinensis in soils could inhibit the seed germination and seedling growth of legumes, which may lead to decrease even fail crop yields after growing this medical plant.
Amino Acids ; metabolism ; Cell Membrane Permeability ; drug effects ; Coptis ; chemistry ; Dose-Response Relationship, Drug ; Germination ; drug effects ; Nitrate Reductase ; metabolism ; Peas ; drug effects ; metabolism ; physiology ; Pheromones ; isolation & purification ; pharmacology ; Plant Extracts ; isolation & purification ; pharmacology ; Plant Roots ; chemistry ; Seedlings ; drug effects ; growth & development ; Vicia faba ; drug effects ; metabolism ; physiology

Excessive nitrate accumulated in plants affects vegetable quality severely and excessive nitrate ingestion would do harm to human health. Assimilatory NADH: nitrate reductase (NR, EC 1.6.6.1), a complex Mo-pterin-, cytochrome b(557)- and FAD-containing protein, catalyzes the regulated and rate-limiting step in the utilization of inorganic nitrogen by higher plants. Enhancing the activity of NR is conducive to reduce the concentration of nitrate in plants. The experiments were conducted to investigate the activity of nitrate reductase in different plant tissues and the relationship between external inducing solution concentration and NR activity (NRA) in plant leaves. Six plant seedlings growing in solution culture were deprived of an external nitrogen (N) supply for 2 weeks. On selected days, three of six plant seedlings were exposed to 50mmol/L NO3- for 0, 2, 5, 8, 11h, and four of the six plant seedlings were exposed to 0, 10, 30, 50mmol/L NO3- for 2h. The NRA was determined in vivo at 538nm using spectrophotometer. The results showed that NRA increased when those plant seedlings were induced by nitrate solution. The change trends of NRA in roots and in leaves of cole, pea and tomato were different during treating time. The NRA in cole leaves was higher than that in its root and in other two plants and increased along with inducing time, but the NRA in bea and tomato was highest when the treating time was 8h and 2h, respectively. The highest NRA in leaves of three kinds of Chinese cabbages and tomato was induced by different concentrations of KNO3 solution. In tomato leaves, the highest NRA was induced by 10 - 30mmol/L KNO3 solution. In three Chinese cabbages, Brassica chinensis L. cv. AJH, XBC and KR-605, the highest NRA was induced by 10, 30, 10mmol/L KNO3 solution, respectively. The results indicated that the response manners of NRA in plants to external nitrate solutions were different. According to these results, the level of NR mRNA in plants could be enhanced by nitrate inducement. The total RNA was isolated from tomato leaves and root which induced by 30mmol/L KNO3 solution for 2h, and NR cDNA was obtained by RT-PCR using the specific primers. The fragments of PCR products were cloned and sequenced. There are 2736 base pairs in the whole cDNA fragment. The deduced protein sequence contains 911 amino acids. The NR gene can be fused to the CaMV 35S promoter, then introduced to higher plants, such as vegetables. It is hoped to decrease drastically the nitrate content of the transgenic plants.
Brassica ; drug effects ; enzymology ; genetics ; Cloning, Molecular ; methods ; Enzyme Activation ; drug effects ; Lycopersicon esculentum ; drug effects ; enzymology ; genetics ; Nitrate Reductase ; genetics ; metabolism ; Nitrates ; pharmacology ; Peas ; drug effects ; enzymology ; genetics ; Plant Proteins ; genetics ; metabolism ; Reverse Transcriptase Polymerase Chain Reaction ; Seedlings ; drug effects ; enzymology ; genetics