Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.7.1.4 (nitrite reductase)
 1,847 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Nitrous oxide (N(2)O) is a key atmospheric greenhouse gas that contributes to global climatic change through radiative warming and depletion of stratospheric ozone. In this report, N(2)O flux was monitored simultaneously with photosynthetic CO(2) and O(2) exchanges from intact canopies of 12 wheat seedlings. The rates of N(2)O-N emitted ranged from <2 pmol x m(-2) x s(-1) when NH(4)(+) was the N source, to 25.6 +/- 1.7 pmol x m(-2) x s(-1) (mean +/- SE, n = 13) when the N source was shifted to NO(3)(-). Such fluxes are among the smallest reported for any trace gas emitted by a higher plant. Leaf N(2)O emissions were correlated with leaf nitrate assimilation activity, as measured by using the assimilation quotient, the ratio of CO(2) assimilated to O(2) evolved. (15)N isotopic signatures on N(2)O emitted from leaves supported direct N(2)O production by plant NO(3)(-) assimilation and not N(2)O produced by microorganisms on root surfaces and emitted in the transpiration stream. In vitro production of N(2)O by both intact chloroplasts and nitrite reductase, but not by nitrate reductase, indicated that N(2)O produced by leaves occurred during photoassimilation of NO(2)(-) in the chloroplast. Given the large quantities of NO(3)(-) assimilated by plants in the terrestrial biosphere, these observations suggest that formation of N(2)O during NO(2)(-) photoassimilation could be an important global biogenic N(2)O source.
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PMID:Wheat leaves emit nitrous oxide during nitrate assimilation. 1142 11

Boron (B) toxicity has become important in areas close to the Mediterranean Sea where intensive agriculture has been developed. The objective of this research was to study the effects of B toxicity (0.5 mM and 2.0 mM B) on nitrogen (N) assimilation of two tomato cultivars that are often used in these areas. Leaf biomass, relative leaf growth rate (RGR(L)), concentration of B, nitrate (NO(3) (-)), ammonium (NH(4) (+)), organic N, amino acids and soluble proteins, as well as nitrate reductase (NR), nitrite reductase (NiR), glutamine synthase (GS), glutamate synthetase (GOGAT) and glutamate dehydrogenase (GDH) activities were analysed in leaves. Boron toxicity significantly decreased leaf biomass, RGR(L), organic N, soluble proteins, and NR and NiR activities. The lowest NO(3) (-) and NH(4) (+) concentration in leaves was recorded when plants were supplied with 2.0 mM B in the root medium. Total B, amino acids, activities of GS, GOGAT and GDH increased under B toxicity. Data from the present study prove that B toxicity causes inhibition of NO(3) (-) reduction and increases NH(4) (+) assimilation in tomato plants.
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PMID:Response of nitrogen metabolism to boron toxicity in tomato plants. 1968 74

Plant-type ferredoxins in Arabidopsis transfer electrons from the photosystem I to multiple redox-driven enzymes involved in the assimilation of carbon, nitrogen, and sulfur. Leaf-type ferredoxins also modulate the switch between the linear and cyclic electron routes of the photosystems. Recently, two novel ferredoxin homologs with extra C-termini were identified in the Arabidopsis genome (AtFdC1, AT4G14890; AtFdC2, AT1G32550). FdC1 was considered as an alternative electron acceptor of PSI under extreme ferredoxin-deficient conditions. Here, we showed that FdC1 could interact with some, but not all, electron acceptors of leaf-type Fds, including the ferredoxin-thioredoxin reductase (FTR), sulfite reductase (SiR), and nitrite reductase (NiR). Photoreduction assay on cytochrome c and enzyme assays confirmed its capability to receive electrons from PSI and donate electrons to the Fd-dependent SiR and NiR but not to the ferredoxin-NADP+ oxidoreductase (FNR). Hence, FdC1 and leaf-type Fds may play differential roles by channeling electrons from photosystem I to different downstream electron acceptors in photosynthetic tissues. In addition, the median redox potential of FdC1 may allow it to receive electrons from FNR in non-photosynthetic plastids.
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PMID:FdC1 and Leaf-Type Ferredoxins Channel Electrons From Photosystem I to Different Downstream Electron Acceptors. 2967 Jun 39