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1.
Cytochromec' ofThiocapsa roseopersicina was partially purified by DEAE and Sephadex chromatography (highest purity index A 275 nm ox./A 396 nm ox.=0.54). It is autoxidizable,
thermostable, and is located in the soluble fraction. The reduced cytochromec' reacts with carbon monoxide and has a γ-band at 417 nm and a shoulder at 435 nm. Cyanide (10−2−10−3 M) does not inhibit the reduction of the cytochromec' by sulfide; only at higher concentrations of cyanide did the shoulder at 435 nm disappear. When the cytochromec' is reduced by dithionite, only one broad α-band at about 550 nm appears next to the γ-band. When is is reduced by sulfide,
the absorption spectrum shows an additional β-band at 521 nm. Cytochromec' is not reduced by thiosulfate. 相似文献
2.
Shi-Han Zhang Ling-Lin Cai Yun Liu Yao Shi Wei Li 《Applied microbiology and biotechnology》2009,82(3):557-563
The biological reduction of Fe(III) ethylenediaminetetraacetic acid (EDTA) is a key step for NO removal in a chemical absorption–biological
reduction integrated process. Since typical flue gas contain oxygen, NO2
− and NO3
− would be present in the absorption solution after NO absorption. In this paper, the interaction of NO2
−, NO3
−, and Fe(III)EDTA reduction was investigated. The experimental results indicate that the Fe(III)EDTA reduction rate decrease
with the increase of NO2
− or NO3
− addition. In the presence of 10 mM NO2
− or NO3
−, the average reduction rate of Fe(III)EDTA during the first 6-h reaction was 0.076 and 0.17 mM h−1, respectively, compared with 1.07 mM h−1 in the absence of NO2
− and NO3
−. Fe(III)EDTA and either NO2
− or NO3
− reduction occurred simultaneously. Interestingly, the reduction rate of NO2
− or NO3
− was enhanced in presence of Fe(III)EDTA. The inhibition patterns observed during the effect of NO2
− and NO3
− on the Fe(III)EDTA reduction experiments suggest that Escherichia coli can utilize NO2
−, NO3
−, and Fe(III)EDTA as terminal electron acceptors. 相似文献
3.
Physiological alterations and regulation of heterocyst and nitrogenase formation have been studied in Het− Fix− mutant strain of diazotrophic cyanobacterium Anabaena variabilis. Het− Fix− mutant strain of A. variabilis has been isolated by N-methyl-N′-nitro-N″-nitrosoguanidine (NTG) mutagenesis and was screened with the penicillin enrichment
(500 μg ml−1). Growth, heterocyst differentiation, nitrogenase and glutamine synthetase (biosynthetic and transferase), 14CO2-fixation, nitrate reductase (NR), nitrite reductase (NiR), glucose-6-phosphate dehydrogenase (G6PDH), and isocitrate dehydrogenase
(IDH) activities, and NO3
−, NO2
−, and NH4
+ uptake and whole cell protein profile in different metabolic conditions were studied in the Het− Fix− mutant strain taking wild-type A. variabilis as reference. Het− Fix− mutant strain was incapable of assimilating elemental nitrogen (N2) due to its inability to form heterocysts and nitrogenase and this was the reason for its inability to grow in BG-110 medium (free from combined nitrogen). In contrast, wild-type strain grew reasonably well in the absence of combined nitrogen
sources and also showed heterocyst differentiation (8.5%) and nitrogenase activity (10.8 ηmol C2H4 formed μg−1 Chl a h−1) in N2-medium. Wild-type strain also exhibited higher NR, NiR, and GS activities compared to its Het− Fix− mutant strain, which may presumably be due to acquisition of high uptake of NO3
−, NO2
−, and NH2
+. Wild-type strain in contrast to its Het− Fix− mutant strain also exhibited high level of G6PDH, IDH, and 14CO2 fixation activities. Low levels of G6PDH and IDH activities in Het− Fix− mutant strain further confirmed the lack of heterocyst differentiation and nitrogenase activity in the Het− Fix− mutant strain.
NR, NiR, and GS activities in both the strains were energy-dependent and the energy required is mainly derived from photophosphorylation.
Furthermore, it was found that de novo protein synthesis is necessarily required for the activities of NR, NiR, and GS in
both wild-type and its Het− Fix− mutant strain.
Received: 21 December 2001 / Accepted: 28 January 2002 相似文献
4.
The ability of an ecosystem to retain anthropogenic nitrogen (N) deposition is dependent upon plant and soil sinks for N,
the strengths of which may be altered by chronic atmospheric N deposition. Sugar maple (Acer saccharum Marsh.), the dominant overstory tree in northern hardwood forests of the Lake States region, has a limited capacity to take
up and assimilate NO3−. However, it is uncertain whether long-term exposure to NO3− deposition might induce NO3− uptake by this ecologically important overstory tree. Here, we investigate whether 10 years of experimental NO3− deposition (30 kg N ha−1 y−1) could induce NO3− uptake and assimilation in overstory sugar maple (approximately 90 years old), which would enable this species to function
as a direct sink for atmospheric NO3− deposition. Kinetic parameters for NH4+ and NO3− uptake in fine roots, as well as leaf and root NO3− reductase activity, were measured under conditions of ambient and experimental NO3− deposition in four sugar maple-dominated stands spanning the geographic distribution of northern hardwood forests in the
Upper Lake States. Chronic NO3− deposition did not alter the V
max or K
m for NO3− and NH4+ uptake nor did it influence NO3− reductase activity in leaves and fine roots. Moreover, the mean V
max for NH4+ uptake (5.15 μmol 15N g−1 h−1) was eight times greater than the V
max for NO3− uptake (0.63 μmol 15N g−1 h−1), indicating a much greater physiological capacity for NH4+ uptake in this species. Additionally, NO3− reductase activity was lower than most values for woody plants previously reported in the literature, further indicating
a low physiological potential for NO3− assimilation in sugar maple. Our results demonstrate that chronic NO3− deposition has not induced the physiological capacity for NO3− uptake and assimilation by sugar maple, making this dominant species an unlikely direct sink for anthropogenic NO3− deposition. 相似文献
5.
Isolation and characterization of nitrite-reductase-deficient mutants of Chlorella sorokiniana (strain 211-8k) 总被引:1,自引:0,他引:1
A method is presented to isolate mutants of Chlorella sorokiniana with defects in NO3
− metabolism. Three nitrite-reductase (NIR; E.C.1.7.7.1)-deficient mutants were obtained from 500 pinpoint-colony-forming clones.
The final screening was performed using NO3
−, NO2
− or NH+
4 as N-source. The mutants isolated absorb NO3
− with rates close to those measured for the wild type and they excrete NO2
− into the medium. The ratio between NO3
− uptake and NO2
− excretion was 1:1. The sensitivity of NO3
− uptake to NH+
4 was reduced in the mutant strains as it was in the N-starved wild type of Chlorella. Nitrate reductase (NR; EC 1.6.6.1) expression and NR activity were slightly reduced compared to the wild type due to feedback
regulation in the mutant strains. No NIR protein was found in the three mutants. However, NIR activity was obtained (50% of
the wild-type) for one mutant strain. The NIR-deficient mutants and the already available NR-deficient mutants will be promising
tools for investigations of the nitrate assimilation pathway on the molecular level and for studies searching for signaling
of C and N metabolism by inorganic N-compounds.
Received: 8 October 1999 / Accepted: 25 January 2000 相似文献
6.
Cytochromec oxidase was purified from mitochondria ofEuglena gracilis and separated into 15 different polypeptide subunits by polyacrylamide gel electrophoresis. All 15 subunits copurify through various purification procedures, and the subunit composition of the isolated enzyme is identical to that of the immunoprecipitated one. Therefore, the 15 protein subunits represent integral components of theEuglena oxidase. In anin vitro protein-synthesizing system using isolated mitochondria, polypeptides 1–3 were radioactive labeled in the presence of [35S]methionine. This further identifies these polypeptides with the three largest subunits of cytochromec oxidse encoded by mitochondrial DNA in other eukaryotic organisms. By subtraction, the other 12 subunits can be assigned to nuclear genes. The isolatedEuglena oxidase was highly active withEuglena cytochromec
558 and has monophasic kinetics. Using horse cytochromec
550 as a substrate, activity of the isolated oxidase was rather low. These findings correlate with the oxidase activity of mitochondrial membranes. Again, reactivity was low with cytochromec
550 and 35-fold higher with theEuglena cytochromec
558. The data show that the cytochromec oxidase of the protistEuglena is different from other eukaryotic cytochromec oxidases in number and size of subunits, and also with regard to kinetic properties and substrate specificity.Abbreviations kDa
kilodalton
- PAGE
polyacrylamide gel electrophoresis
- SDS
sodium dodecyl sulfate
- TN
turnover number 相似文献
7.
High-affinity nitrate transport was examined in intact hyphae of Neurospora crassa using electrophysiological recordings to characterize the response of the plasma membrane to NO−
3 challenge and to quantify transport activity. The NO−
3-associated membrane current was determined using a three electrode voltage clamp to bring membrane voltage under experimental
control and to compensate for current dissipation along the longitudinal cell axis. Nitrate transport was evident in hyphae
transferred to NO−
3-free, N-limited medium for 15 hr, and in hyphae grown in the absence of a nitrogen source after a single 2-min exposure to
100 μm NO−
3. In the latter, induction showed a latency of 40–80 min and rose in scalar fashion with full transport activity measurable
approx. 100 min after first exposure to NO−
3; it was marked by the appearance of a pronounced sensitivity of membrane voltage to extracellular NO−
3 additions which, after induction, resulted in reversible membrane depolarizations of (+)54–85 mV in the presence of 50 μm NO−
3; and it was suppressed when NH4
+ was present during the first, inductive exposure to NO−
3. Voltage clamp measurements carried out immediately before and following NO−
3 additions showed that the NO−
3-evoked depolarizations were the consequence of an inward-directed current that appeared in parallel with the depolarizations
across the entire range of accessible voltages (−400 to +100 mV). Measurements of NO−
3 uptake using NO−
3-selective macroelectrodes indicated a charge stoichiometry for NO−
3 transport of 1(+):1(NO−
3) with common K
m and J
max values around 25 μm and 75 pmol NO−
3 cm−2sec−1, respectively, and combined measurements of pH
o
and [NO−
3]
o
showed a net uptake of approx. 1 H+ with each NO−
3 anion. Analysis of the NO−
3 current demonstrated a pronounced voltage sensitivity within the normal physiological range between −300 and −100 mV as well
as interactions between the kinetic parameters of membrane voltage, pH
o
and [NO−
3]
o
. Increasing the bathing pH from 5.5 to 8.0 reduced the current and the associated membrane depolarizations 2- to 4-fold.
At a constant pH
o
of 6.1, driving the membrane voltage from −350 to −150 mV resulted in an approx. 3-fold reduction in the maximum current
and a 5-fold rise in the apparent affinity for NO−
3. By contrast, the same depolarization effected an approx. 20% fall in the K
m
for transport as a function in [H+]
o
. These, and additional results are consistent with a charge-coupling stoichiometry of 2(H+) per NO−
3 anion transported across the membrane, and implicate a carrier cycle in which NO−
3 binding is kinetically adjacent to the rate-limiting step of membrane charge transit. The data concur with previous studies
demonstrating a pronounced voltage-dependence to high-affinity NO−
3 transport system in Arabidopsis, and underline the importance of voltage as a kinetic factor controlling NO−
3 transport; finally, they distinguish metabolite repression of NO−
3 transport induction from its sensitivity to metabolic blockade and competition with the uptake of other substrates that draw
on membrane voltage as a kinetic substrate.
Received: 17 March 1997/Revised: 20 June 1997 相似文献
8.
Agostino Sorgonà Giovanni Cacco Lugi Di Dio Wolfgang Schmidt Paula Jay Perry Maria Rosa Abenavoli 《Acta Physiologiae Plantarum》2010,32(4):683-693
Spatial–temporal variation of the regulation and the kinetics of net nitrate (NO3
−) uptake rate (NNUR) along the tap root of Citrus aurantium L. were analysed. Suberin incrustation in the peripheral cell layers and plasma membrane (PM) H+-ATPase localisation, anatomical and physiological factors involved in NO3
− uptake were also investigated. The results clearly indicated a spatially uniform distribution of the regulation process,
accompanied by a temporal heterogeneous pattern of the kinetics of NO3
− uptake along citrus tap root. In particular, kinetic analysis had a biphasic pattern, saturating (high affinity transport
system) and linear (low affinity transport system), in response to increasing external NO3
− concentrations in each root region, where 200 μM NO3
− represented the threshold separating these two systems. Kinetic parameters, K
m and V
max, clearly indicated that apical segments reached the maximum value of induction before basal segments. Hence, the apical root
zones, early exhibiting the maximum of potential capacity to absorb the NO3
−, could be considered more efficient than basal root segments for acquiring NO3
− from external solution. Suberin incrustations in the hypodermal cell layer, characterised by uniform fluorescence intensity
among the root segments, could be responsible for the unchanged NNUR, while the PM H+-ATPase could explain the temporal pattern of NNUR. 相似文献
9.
Summary Short-term absorption experiments were conducted with intact barley (Hordeum vulgare L.) seedlings to observe the effects of the osmotic potential (Ψπ) and salt species on nitrate uptake andin vivo nitrate reduction. The experiments consisted of growing barley seedlings for 5 days in complete nutrient solutions salinized
to (Ψπ) levels of −0.6, −1.8, −3.0, −4.2, and −5.4 bars with NaCl, CaCl2 or Na2SO4. After the absorption period, the seedlings were separated into shoots and roots, weighed, then analyzed for NO3. The nutrient solutions were sampled for NO3 analysis each day immediately before renewing the solutions. The accumulative loss of NO3 from the solutions was considered to be uptake whereas NO3 reduction was the difference between uptake and seedling content. Lowering the (Ψπ) of the nutrient solutions resulted in decreased concentrations of NO3 in the plant, little or no effect (except at the lowest (Ψπ) level) on uptake, and increased nitrate reductase activity. Increased rates of NO3 reduction were in particular associated with the Cl concentration of the nutrient solution. 相似文献
10.
Chaetoceros muelleri (Lemn.) was cultured with nitrite (NO2−) or nitrate (NO3−) as the sole nitrogen source and aerated with air or with CO2-enriched air. Cells of C. muelleri excreted into the medium nitrite produced by reduction of nitrate when grown with 100 μM NaNO3 as nitrogen source. Accordingly, NO2− concentration reached 10.4 μM after 95 h at the low CO2 condition (aerated with air); while the maximum NO2− concentration was only around 2.0 μM at the high CO2 condition (aerated with 5% CO2 in air), furthermore, after 30 h it decreased to no more than 1.0 μM. NO2− was almost assimilated in 80 h when C. muelleri was cultured at the high CO2 condition with 100 μM NaNO2 as sole nitrogen source. At the high CO2 condition, after 3 h the activity of nitrite reductase was as much as 50% higher than that at the low CO2 condition. It was indicated that enriched CO2 concentration could inhibit nitrite excretion and enhance nitrite assimilation by cells. Therefore, aeration with enriched
CO2 might be an effective way to control nitrite content in aquaculture systems. 相似文献
11.
J. Alan Yeakley David C. Coleman Bruce L. Haines Brian D. Kloeppel Judy L. Meyer Wayne T. Swank Barry W. Argo James M. Deal Sharon F. Taylor 《Ecosystems》2003,6(2):0154-0167
We investigated the effects of removing near-stream Rhododendron and of the natural blowdown of canopy trees on nutrient export to streams in the southern Appalachians. Transects were instrumented
on adjacent hillslopes in a first-order watershed at the Coweeta Hydrologic Laboratory (35°03′N, 83°25′W). Dissolved organic
carbon (DOC), K+, Na+, Ca2+, Mg2+, NO3
−-N, NH4
+-N, PO4
3−-P, and SO4
2− were measured for 2 years prior to disturbance. In August 1995, riparian Rhododendron on one hillslope was cut, removing 30% of total woody biomass. In October 1995, Hurricane Opal uprooted nine canopy trees
on the other hillslope, downing 81% of the total woody biomass. Over the 3 years following the disturbance, soilwater concentrations
of NO3
−-N tripled on the cut hillslope. There were also small changes in soilwater DOC, SO4
2−, Ca2+, and Mg2+. However, no significant changes occurred in groundwater nutrient concentrations following Rhododendron removal. In contrast, soilwater NO3
−-N on the storm-affected hillslope showed persistent 500-fold increases, groundwater NO3
−-N increased four fold, and streamwater NO3
−-N doubled. Significant changes also occurred in soilwater pH, DOC, SO4
2−, Ca2+, and Mg2+. There were no significant changes in microbial immobilization of soil nutrients or water outflow on the storm-affected hillslope.
Our results suggest that Rhododendron thickets play a relatively minor role in controlling nutrient export to headwater streams. They further suggest that nutrient
uptake by canopy trees is a key control on NO3
−-N export in upland riparian zones, and that disruption of the root–soil connection in canopy trees via uprooting promotes
significant nutrient loss to streams.
Received 30 January 2001; accepted 25 July 2002. 相似文献
12.
Metabolism of ammonia (NH3) and hydroxylamine (NH2OH) by wild-type and a nitrite reductase (nirK) deficient mutant of Nitrosomonas europaea was investigated to clarify the role of NirK in the NH3 oxidation pathway. NirK-deficient N. europaea grew more slowly, consumed less NH3, had a lower rate of nitrite (NO2
−) production, and a significantly higher rate of nitrous oxide (N2O) production than the wild-type when incubated with NH3 under high O2 tension. In incubations with NH3 under low O2 tension, NirK-deficient N. europaea grew more slowly, but had only modest differences in NH3 oxidation and product formation rates relative to the wild-type. In contrast, the nirK mutant oxidized NH2OH to NO2
− at consistently slower rates than the wild-type, especially under low O2 tension, and lost a significant pool of NH2OH–N to products other than NO2
− and N2O. The rate of N2O production by the nirK mutant was ca. three times higher than the wild-type during hydrazine-dependent NO2
− reduction under both high and low O2 tension. Together, the results indicate that NirK activity supports growth of N. europaea by supporting the oxidation of NH3 to NO2
− via NH2OH, and stimulation of hydrazine-dependent NO2
− reduction by NirK-deficient N. europaea indicated the presence of an alternative, enzymatic pathway for N2O production. 相似文献
13.
Nitrogen relations of natural and disturbed tropical plant communities in northern Australia (Kakadu National Park) were
studied. Plant and soil N characteristics suggested that differences in N source utilisation occur at community and species
level. Leaf and xylem sap N concentrations of plants in different communities were correlated with the availability of inorganic
soil N (NH+
4 and NO−
3). In general, rates of leaf NO−
3 assimilation were low. Even in communities with a higher N status, including deciduous monsoon forest, disturbed wetland,
and a revegetated mine waste rock dump, levels of leaf nitrate reductase, xylem and leaf NO−
3 levels were considerably lower than those that have been reported for eutrophic communities. Although NO−
3 assimilation in escarpment and eucalypt woodlands, and wetland, was generally low, within these communities there was a suite
of species that exhibited a greater capacity for NO−
3 assimilation. These “high- NO−
3 species” were mainly annuals, resprouting herbs or deciduous trees that had leaves with high N contents. Ficus, a high-NO−
3 species, was associated with soil exhibiting higher rates of net mineralisation and net nitrification. “Low-NO−
3 species” were evergreen perennials with low leaf N concentrations. A third group of plants, which assimilated NO−
3 (albeit at lower rates than the high-NO−
3 species), and had high-N leaves, were leguminous species. Acacia species, common in woodlands, had the highest leaf N contents of all woody species. Acacia species appeared to have the greatest potential to utilise the entire spectrum of available N sources. This versatility in
N source utilisation may be important in relation to their high tissue N status and comparatively short life cycle. Differences
in N utilisation are discussed in the context of species life strategies and mycorrhizal associations.
Received: 5 July 1997 / Accepted: 13 July 1998 相似文献
14.
Koop JH Grieshaber MK 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2000,170(1):75-83
Fluctuating salinities at different sites on the German salt-polluted rivers Werra and Weser were compared with extracellular
ion levels of specimens of Gammarus tigrinus (Sexton; Amphipoda, Crustacea), collected at the same sites. G. tigrinus regulated haemolymph concentrations of inorganic anions (Cl−, SO2−
4, PO3−
4) and cations (Na+, K+, Mg2+, Ca2+) during fluctuations of salt pollution in the upper Weser. This capacity to regulate varying levels of salt pollution in
the upper Weser, correlated well with the distribution of the brackish amphipods in this river ecosystem. G. tigrinus tolerated periods of Na+ and Cl− stress (>380 mmol l−1) without compensating these maxima by regulating extracellular Na+ and Cl−. However, during such bursts of Na+ and Cl− stress in Werra and Weser, the ability to regulate extracellular [K+] at river water K+ stress of ≥6.0 mmol l−1 may explain why this brackish species has been more successful in these rivers than its competitors like Gammarus pulex. The present investigation demonstrates that the water salinity affects the [NO−
3] in the haemolymph of G. tigrinus. With increasing hypo-osmotic stress the animals accumulate increasing amounts of NO−
3. A simultaneous increase in stream water [NO−
3] causes an additional accumulation of NO−
3 in the haemolymph. The high extent of accumulation indicates that active ion transport systems may be involved. The accumulation
of NO−
3 in the haemolymph has low physiological consequences to G. tigrinus, but when hypo-osmotically stressed under anoxic conditions, nitrite formed by the reduction of nitrate may have an adverse
affect on the metabolism of G. tigrinus.
Accepted: 4 October 1999 相似文献
15.
16.
Seaweeds growing in the intertidal zone are exposed to fluctuating nitrate and ultraviolet radiation (UVR) levels. While it
has been shown that elevated UVR levels and the decrease of nitrate concentration can reduce photosynthetic levels in seaweeds,
less is known about the combined effect of nitrate levels and UVR on metabolism and photoprotection mechanisms of intertidal
species. Consequently, the objective of this study was to evaluate the effect of nitrate concentration and UVR treatments
on photosynthesis, respiration, nitrate reductase activity and phenolic compound levels of Ulva rigida (Chlorophyta). There was a two- to threefold increase in maximal gross photosynthesis (GPmax) and respiration rates, as nitrate increased from 0 to 50 μM NO3−. Similarly, nitrate reductase activity increased linearly from low values in algae incubated at 0 μM NO3 to high values in tissue incubated at 50 μM NO3−. Phenolic compounds in the tissue of U. rigida increased approximately 60% under 50 μM NO3− relative to those incubated at 0 μM NO3−. Algae exposed to UVR (8 h) showed a significant decrease in the effective quantum yield and respiration, however, no effect
was observed in the phenolic compounds levels. Full recovery of effective quantum yield was observed after U. rigida was transferred for 48 h to low PAR. Nitrate reductase also decreased after an 8-h UVR exposure, but no differences were
observed among the nitrate treatments. This study shows that high nitrate levels reduced the negative effect of UVR on the
effective quantum yield and increased the recovery of key metabolic enzymes. It is possible that the increase of phenolic
compounds in the thallus of U. rigida under high nitrate levels provide a photoprotective mechanism when exposed to high UV levels during low tides. 相似文献
17.
Nonibala Khumanthem Mayashree B. Syiem Arvind K. Singh Amar Nath Rai 《Indian journal of microbiology》2007,47(4):345-352
A Mastigocladus species was isolated from the hot spring of Jakrem (Meghalaya) India. Uptake and utilization of nitrate, nitrite, ammonium
and amino acids (glutamine, asparagine, arginine, alanine) were studied in this cyanobacterium grown at different temperatures
(25°C, 45°C). There was 2–3 fold increase in the heterocyst formation and nitrogenase activity in N-free medium at higher
temperature (45°C). Growth and uptake and assimilation of various nitrogen sources were also 2–3 fold higher at 45°C indicating
that it is a thermophile. The extent of induction and repression of nitrate uptake by NO3
− and NH4
+, respectively, differed from that of nitrite. It appeared that Mastigocladus had two independent nitrate/nitrite transport systems. Nitrate reductase and nitrite reductase activitiy was not NO3
−-inducible and ammonium or amino acids caused only partial repression. Presence of various amino acids in the media partially
repressed glutamine synthetase activity. Ammonium (methylammonium) and amino acid uptake showed a biphasic pattern, was energy-dependent
and the induction of uptake required de novo protein synthesis. Ammonium transport was substrate (NH4
+)-repressible, while the amino acid uptake was substrate inducible. When grown at 25°C, the cyanobacterium formed maximum
akinetes that remained viable upto 5 years under dry conditions. 相似文献
18.
The impacts of various nitrogen sources, i.e. NO−
3, NH4
+ or NH4NO3 in combination with gaseous NH3, on nitrogen-, carbon- and water-use efficiency and 13C discrimination (δ13C) by plants of the C3 species Triticum aestivum L. (wheat) and the C4 species Zea mays L. (maize) were studied. Triticum aestivum and Z. mays were hydroponically grown with 2 mol · m−3 of N supplied as NO−
3, NH4
+ or NH4NO3 for 21 and 18 d, respectively, and thereafter exposed to gaseous NH3 at 320 μg · m−3 or to ambient air for 7 d. In T. aestivum and Z. mays over a 7-d growth period, nitrogen-use efficiency (NUE) values were influenced by N-sources in the decreasing order NH4NO3-N > NO−
3-N > NH4
+-N and NO−
3-N > NH4NO3-N > NH4
+-N, respectively. Fumigation with NH3 decreased the NUE values of plants grown with any of the N-forms. During 28- and 7-d growth periods, N-sources affected water-use
efficiency (WUE) values in the decreasing order of NH4
+-N > NO−
3-N≈NH4NO3-N in non-fumigated T. aestivum, while fumigation with NH3 increased the WUE of NO−
3-grown plants. There were insignificant effects of N-sources on WUE values of Z. mays over 25- and 7-d growth periods. Furthermore, δ13C values in plant tissues (leaves, stubble and roots) were higher (less negative) in NH4
+-grown plants of T. aestivum and Z. mays than in those supplied with NH4NO3 or NO−
3. Regardless of the N-form supplied to the roots of the plant species, exposure to NH3 caused more-positive δ13C values in the plant tissues. These results indicate that the variations in N-source were associated with small but significant
variations in δ13C values in plants of T. aestivum and Z. mays. These differences in δ13C values are in the direction expected from differences in WUE values over long or short growth periods and with differences
in the extent of non-Rubisco (ribulose-1,5-bisphosphate carboxylase-oxygenase, EC 4.1.1.39) carboxylate contribution to net
C acquisition, as a function of N-source.
Received: 12 September 1997 / Accepted: 13 January 1998 相似文献
19.
Yukio Inoue 《Journal of plant research》1973,86(2):121-132
The electron transfer pathway in the respiratory particles ofStreptomyces griseus was studied. Vitamins K3 and K5,α- andβ-naphthoquinones, served as the hydrogen acceptors in succinate oxidation, and succinate- and reduced nicotinamide adenine
dinucleotide (NADH)-cytochromec reductase activities, but were ineffective for NADH oxidase activity. Vitamin K seemed to mediate the hydrogen from NADH-diaphorase
to cytochromec. Chlorpromazine inhibited electron transfer in the respiratory particles. Cyanide completely inhibited the electron transfer
system initially, however, oxygen consumption increased gradually with time. AlthoughS. griseus possesses cytochromesa, b, c and pigment 625 (probablyd), the electron transfer chain was complicated. Two terminal oxidase activities (cytochromec oxidase and cytochromec peroxidase activities) were detected in the respiratory particles ofS. griseus.
Dedicated to Prof. Shoichiro Usami celebrating his sexagenary birthday. 相似文献
20.
Effects of Anions on the Capacity and Affinity of Copper Adsorption in Two Variable Charge Soils 总被引:2,自引:0,他引:2
Effects of nitrate,(NO3−) chloride (Cl−), sulfate (SO42-, and acetate (Ac−) on Cu2+ adsorption and affinity of the adsorbed Cu2+ were evaluated in two Fe and Al enriched variable charge soils from Southern China. The maximum adsorption of Cu2+ (M, a parameter from the Langmuir isotherm model) in the presence of different anions decreased in the order
Cl− > Ac− > NO3− > SO42- for both soils. The clayey loamy soil (mixed siliceous thermic Typic Dystrochrept, TTD), developed on the Arenaceous rock,
adsorbed less Cu2+ than the clayey soil (kaolinitic thermic Plinthudults, KTP), derived from the Quaternary red earths, regardless of anion
type present in the medium. The affinity of adsorbed Cu2+ to both soils could be characterized by the Kd (distribution coefficient) values and successive extraction of the adsorbed Cu2+ with 1-mol NH4Ac L−1. The log10Kd value was smaller for the TTD soil than for the KTP soil and decreased in the order of Cl− > NO3− > SO42- > Ac−
at low initial Cu2+ concentrations (≤40 mg Cu2+L−1), whereas at 80 mg Cu2+L−1, the log10Kd value was similar for NO3−, SO42-, and Ac−, but was slightly higher for Cl−. Complete extraction of Cu2+ adsorbed in the presence of Ac− was achieved. Influence of NO3− and SO42- on the affinity of adsorbed Cu2+ was similar, but the effects of Cl− depended on the initial Cu2+ concentrations. The extracted percentage of the adsorbed Cu2+ in the presence of NO3− or SO42- increased with increasing Cu2+ adsorption saturation. The presence of Cl−, NO3−, or SO42- markedly decreased the equilibrium solution pH for both soils with increasing initial Cu2+ concentrations, and the delta pH values at the highest Cu2+ level were 0.5, 0.63, and 0.55 U for the TTD soil and 0.79, 0.84, and 0.93 U for the KTP soil, respectively for the three
anions. The presence of Ac− had a minimal influence on the equilibrium solution pH because of the buffering nature of the NaAc/HAc medium which buffered
the released protons. The effects of anions on Cu2+ adsorption and affinity of the adsorbed Cu2+ were dependent on anion types and were apparently related to the altered surface properties caused by anion adsorption and/or
the formation of anion– Cu2+ complexes. 相似文献