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1.
L. A. Vasil’ev E. V. Dzyubinskaya R. A. Zinovkin D. B. Kiselevsky N. V. Lobysheva V. D. Samuilov 《Biochemistry. Biokhimii?a》2009,74(9):1035-1043
Chitosan, CN−, or H2O2 caused the death of epidermal cells (EC) in the epidermis of pea leaves that was detected by monitoring the destruction of
cell nuclei; chitosan induced chromatin condensation and marginalization followed by the destruction of EC nuclei and subsequent
internucleosomal DNA fragmentation. Chitosan did not affect stoma guard cells (GC). Anaerobic conditions prevented the chitosan-induced
destruction of EC nuclei. The antioxidants nitroblue tetrazolium or mannitol suppressed the effects of chitosan, H2O2, or chitosan + H2O2 on EC. H2O2 formation in EC and GC mitochondria that was determined from 2′,7′-dichlorofluorescein fluorescence was inhibited by CN− and the protonophoric uncoupler carbonyl cyanide m-chlorophenylhydrazone but was stimulated by these agents in GC chloroplasts. The alternative oxidase inhibitors propyl gallate
and salicylhydroxamate prevented chitosan- but not CN−-induced destruction of EC nuclei; the plasma membrane NADPH oxidase inhibitors diphenylene iodonium and quinacrine abolished
chitosan- but not CN−-induced destruction of EC nuclei. The mitochondrial protein synthesis inhibitor lincomycin removed the destructive effect
of chitosan or H2O2 on EC nuclei. The effect of cycloheximide, an inhibitor of protein synthesis in the cytoplasm, was insignificant; however,
it was enhanced if cycloheximide was added in combination with lincomycin. The autophagy inhibitor 3-methyladenine removed
the chitosan effect but exerted no influence on the effect of H2O2 as an inducer of EC death. The internucleosome DNA fragmentation in conjunction with the data on the 3-methyladenine effect
provides evidence that chitosan induces programmed cell death that follows a combined scenario including apoptosis and autophagy.
Based on the results of an inhibitor assay, chitosan-induced EC death involves reactive oxygen species generated by the NADPH
oxidase of the plasma membrane. 相似文献
2.
A controlled growth chamber experiment was conducted to investigate the short-term water use and photosynthetic responses
of 30-d-old carrot seedlings to the combined effects of CO2 concentration (50–1 050 μmol mol−1) and moisture deficits (−5, −30, −55, and −70 kPa). The photosynthetic response data was fitted to a non-rectangular hyperbola
model. The estimated parameters were compared for effects of moisture deficit and elevated CO2 concentration (EC). The carboxylation efficiency (α) increased in response to mild moisture stress (−30 kPa) under EC when
compared to the unstressed control. However, moderate (−55 kPa) and extreme (−70 kPa) moisture deficits reduced α under EC.
Maximum net photosynthetic rate (P
Nmax) did not differ between mild water deficit and unstressed controls under EC. Moderate and extreme moisture deficits reduced
P
Nmax by nearly 85 % compared to controls. Dark respiration rate (R
D) showed no consistent response to moisture deficit. The CO2 compensation concentration (Γ) was 324 μmol mol−1 for −75 kPa and ranged 63–93 μmol mol−1 for other moisture regimes. Interaction between moisture deficit and EC was noticed for P
N, ratio of intercellular and ambient CO2 concentration (C
i/C
a), stomatal conductance (g
s
), and transpiration rate (E). P
N was maximum and C
i/C
a was minimum at −30 kPa moisture deficit and at C
a of 350 μmol mol−1. The g
s and E showed an inverse relationship at all moisture deficit regimes and EC. Water use efficiency (WUE) increased with moisture
deficit up to −55 kPa and declined thereafter. EC showed a positive influence towards sustaining P
N and increasing WUE only under mild moisture stress, and no beneficial effects of EC were noticed at moderate or extreme moisture
deficits. 相似文献
3.
J. Balogh Z. Nagy Sz. Fóti K. Pintér Sz. Czóbel E. R. Péli M. Acosta M. V. Marek Zs. Csintalan Z. Tuba 《Photosynthetica》2007,45(2):288-292
Measurements of CO2 and H2O fluxes were carried out using two different techniques—eddy-covariance (EC) and open system gas exchange chamber (OC)—during
two-years’ period (2003–2004) at three different grassland sites. OC measurements were made during fourteen measurement campaigns.
We found good agreement between the OC and EC CO2 flux values (n = 63, r
2 = 0.5323, OC FCO2 = −0.6408+0.9508 EC FCO2). The OC FH2O values were consistently lower than those measured by the EC technique, probably caused by the air stream difference inside
and outside the chamber. Adjusting flow rate within the chamber to the natural conditions would be necessary in future OC
measurements. In comparison with EC, the OC proved to be a good tool for gas exchange measurements in grassland ecosystems. 相似文献
4.
Simultaneous measurements of chlorophyll (Chl) fluorescence and CO2 assimilation (A) in Vicia faba leaves were taken during the first weeks of growth to evaluate the protective effect of 24-epibrassinolide (EBR) against
damage caused by the application of the herbicide terbutryn (Terb) at pre-emergence. V. faba seeds were incubated for 24 h in EBR solutions (2 × 10−6 or 2 × 10−5 mM) and immediately sown. Terb was applied at recommended doses (1.47 or 1.96 kg ha−1) at pre-emergence. The highest dose of Terb strongly decreased CO2 assimilation, the maximum quantum yield of PSII photochemistry in the dark-adapted state (F
V/F
M), the nonphotochemical quenching (NPQ), and the effective quantum yield (ΔF/F′M) during the first 3–4 weeks after plant emergence. Moreover, Terb increased the basal quantum yield of nonphotochemical processes
(F
0/F
M), the degree of reaction center closure (1 − q
p), and the fraction of light absorbed in PSII antennae that was dissipated via thermal energy dissipation in the antennae
(1 − F′V/F′M). The herbicide also significantly reduced plant growth at the end of the experiment as well as plant length, dry weight,
and number of leaves. The application of EBR to V. faba seeds before sowing strongly diminished the effect of Terb on fluorescence parameters and CO2 assimilation, which recovered 13 days after plant emergence and showed values similar to those of control plants. The protective
effect of EBR on CO2 assimilation was detected at a photosynthetic photon flux density (PFD) of 650 μmol m−2 s−1 and the effect on ΔF/F′M and photosynthetic electron transport (J) was detected under actinic lightings up to 1750 μmol m−2 s−1. The highest dose of EBR also counteracted the decrease in plant growth caused by Terb, and plants registered the same growth
values as controls. 相似文献
5.
Christian Brümmer Nicolas Brüggemann Klaus Butterbach-Bahl Ulrike Falk Jörg Szarzynski Konrad Vielhauer Reiner Wassmann Hans Papen 《Ecosystems》2008,11(4):582-600
In a combined field and laboratory study in the southwest of Burkina Faso, we quantified soil-atmosphere N2O and NO exchange. N2O emissions were measured during two field campaigns throughout the growing seasons 2005 and 2006 at five different experimental
sites, that is, a natural savanna site and four agricultural sites planted with sorghum (n = 2), cotton and peanut. The agricultural fields were not irrigated and not fertilized. Although N2O exchange mostly fluctuated between −2 and 8 μg N2O–N m−2 h−1, peak N2O emissions of 10–35 μg N2O–N m−2 h−1 during the second half of June 2005, and up to 150 μg N2O–N m−2 h−1 at the onset of the rainy season 2006, were observed at the native savanna site, whereas the effect of the first rain event
on N2O emissions at the crop sites was low or even not detectable. Additionally, a fertilizer experiment was conducted at a sorghum
field that was divided into three plots receiving different amounts of N fertilizer (plot A: 140 kg N ha−1; plot B: 52.5 kg N ha−1; plot C: control). During the first 3 weeks after fertilization, only a minor increase in N2O emissions at the two fertilized plots was detected. After 24 days, however, N2O emission rates increased exponentially at plot A up to a mean of 80 μg N2O–N m−2 h−1, whereas daily mean values at plot B reached only 19 μg N2O–N m−2 h−1, whereas N2O flux rates at plot C remained unchanged. The calculated annual N2O emission of the nature reserve site amounted to 0.52 kg N2O–N ha−1 a−1 in 2005 and to 0.67 kg N2O–N ha−1 a−1 in 2006, whereas the calculated average annual N2O release of the crop sites was only 0.19 kg N2O–N ha−1 a−1 and 0.20 kg N2O–N ha−1 a−1 in 2005 and 2006, respectively. In a laboratory study, potential N2O and NO formation under different soil moisture regimes were determined. Single wetting of dry soil to medium soil water
content with subsequent drying caused the highest increase in N2O and NO emissions with maximum fluxes occurring 1 day after wetting. The stimulating effect lasted for 3–4 days. A weaker
stimulation of N2O and NO fluxes was detected during daily wetting of soil to medium water content, whereas no significant stimulating effect
of single or daily wetting to high soil water content (>67% WHCmax) was observed. This study demonstrates that the impact of land-use change in West African savanna on N trace gas emissions
is smaller—with the caveat that there could have been potentially higher N2O and NO emissions during the initial conversion—than the effect of timing and distribution of rainfall and of the likely
increase in nitrogen fertilization in the future. 相似文献
6.
This study examined the effects of season-long exposure of Chinese pine (Pinus tabulaeformis) to elevated carbon dioxide (CO2) and/or ozone (O3) on indole-3-acetic acid (IAA) content, activities of IAA oxidase (IAAO) and peroxidase (POD) in needles. Trees grown in
open-top chambers (OTC) were exposed to control (ambient O3, 55 nmol mol−1 + ambient CO2, 350 μmol mol−1, CK), elevated CO2 (ambient O3 + high CO2, 700 μmol mol−1, EC) and elevated O3 (high O3, 80 ± 8 nmol mol−1 + ambient CO2, EO) OTCs from 1 June to 30 September. Plants grown in elevated CO2 OTC had a growth increase of axial shoot and needle length, compared to control, by 20% and 10% respectively, while the growth
in elevated O3 OTC was 43% and 7% less respectively, than control. An increase in IAA content and POD activity and decrease in IAAO activity
were observed in trees exposed to elevated CO2 concentration compared with control. Elevated O3 decreased IAA content and had no significant effect on IAAO activity, but significantly increased POD activity. When trees
pre-exposed to elevated CO2 were transferred to elevated O3 (EC–EO) or trees pre-exposed to elevated O3 were transferred to elevated CO2 (EO–EC), IAA content was lower while IAAO activity was higher than that transferred to CK (EC–CK or EO–CK), the change in
IAA content was also related to IAAO activity. The results indicated that IAAO and POD activities in Chinese pine needles
may be affected by the changes in the atmospheric environment, resulting in the change of IAA metabolism which in turn may
cause changes in Chinese pine’s growth.
An erratum to this article can be found at 相似文献
7.
The objective of this study was to improve the biological water–gas shift reaction for producing hydrogen (H2) by conversion of carbon monoxide (CO) using an anaerobic thermophilic pure strain, Carboxydothermus hydrogenoformans. Specific hydrogen production rates and yields were investigated at initial biomass densities varying from 5 to 20 mg volatile
suspended solid (VSS) L−1. Results showed that the gas–liquid mass transfer limits the CO conversion rate at high biomass concentrations. At 100-rpm
agitation and at CO partial pressure of 1 atm, the optimal substrate/biomass ratio must exceed 5 mol CO g−1 biomass VSS in order to avoid gas–liquid substrate transfer limitation. An average H2 yield of 94 ± 3% and a specific hydrogen production rate of ca. 3 mol g−1 VSS day−1 were obtained at initial biomass densities between 5 and 8 mg VSS−1. In addition, CO bioconversion kinetics was assessed at CO partial pressure from 0.16 to 2 atm, corresponding to a dissolved
CO concentration at 70°C from 0.09 to 1.1 mM. Specific bioactivity was maximal at 3.5 mol CO g−1 VSS day−1 for a dissolved CO concentration of 0.55 mM in the culture. This optimal concentration is higher than with most other hydrogenogenic
carboxydotrophic species. 相似文献
8.
Jirko Holst Chunyan Liu Nicolas Brüggemann Klaus Butterbach-Bahl Xunhua Zheng Yuesi Wang Shenghui Han Zhisheng Yao Jin Yue Xingguo Han 《Ecosystems》2007,10(4):623-634
Gross rates of N mineralization and nitrification, and soil–atmosphere fluxes of N2O, NO and NO2 were measured at differently grazed and ungrazed steppe grassland sites in the Xilin river catchment, Inner Mongolia, P. R.
China, during the 2004 and 2005 growing season. The experimental sites were a plot ungrazed since 1979 (UG79), a plot ungrazed
since 1999 (UG99), a plot moderately grazed in winter (WG), and an overgrazed plot (OG), all in close vicinity to each other.
Gross rates of N mineralization and nitrification determined at in situ soil moisture and soil temperature conditions were
in a range of 0.5–4.1 mg N kg−1 soil dry weight day−1. In 2005, gross N turnover rates were significantly higher at the UG79 plot than at the UG99 plot, which in turn had significantly
higher gross N turnover rates than the WG and OG plots. The WG and the OG plot were not significantly different in gross ammonification
and in gross nitrification rates. Site differences in SOC content, bulk density and texture could explain only less than 15%
of the observed site differences in gross N turnover rates. N2O and NO
x
flux rates were very low during both growing seasons. No significant differences in N trace gas fluxes were found between
plots. Mean values of N2O fluxes varied between 0.39 and 1.60 μg N2O-N m−2 h−1, equivalent to 0.03–0.14 kg N2O-N ha−1 y−1, and were considerably lower than previously reported for the same region. NO
x
flux rates ranged between 0.16 and 0.48 μg NO
x
-N m−2 h−1, equivalent to 0.01–0.04 kg NO
x
-N ha−1 y−1, respectively. N2O fluxes were significantly correlated with soil temperature and soil moisture. The correlations, however, explained only
less than 20% of the flux variance. 相似文献
9.
In sunflower (Helianthus annuus L.) grown under controlled conditions and subjected to drought by withholding watering, net photosynthetic rate (P
N) and stomatal conductance (g
s) of attached leaves decreased as leaf water potential (Ψw) declined from −0.3 to −2.9 MPa. Although g
s decreased over the whole range of Ψw, nearly constant values in the intercellular CO2 concentrations (C
i) were observed as Ψw decreased to −1.8 MPa, but C
i increased as Ψw decreased further. Relative quantum yield, photochemical quenching, and the apparent quantum yield of photosynthesis decreased
with water deficit, whereas non-photochemical quenching (qNP) increased progressively. A highly significant negative relationship between qNP and ATP content was observed. Water deficit did not alter the pyridine nucleotide concentration but decreased ATP content
suggesting metabolic impairment. At a photon flux density of 550 μmol m−2 s−1, the allocation of electrons from photosystem (PS) 2 to O2 reduction was increased by 51 %, while the allocation to CO2 assimilation was diminished by 32 %, as Ψw declined from −0.3 to −2.9 MPa. A significant linear relationship between mean P
N and the rate of total linear electron transport was observed in well watered plants, the correlation becoming curvilinear
when water deficit increased. The maximum quantum yield of PS2 was not affected by water deficit, whereas qP declined only at very severe stress and the excess photon energy was dissipated by increasing qNP indicating that a greater proportion of the energy was thermally dissipated. This accounted for the apparent down-regulation
of PS2 and supported the protective role of qNP against photoinhibition in sunflower. 相似文献
10.
Kun Yan Wei Chen Guoyou Zhang Sheng Xu Zhouli Liu Xingyuan He Lanlan Wang 《Acta Physiologiae Plantarum》2010,32(2):375-385
Using open top chambers, the effects of elevated O3 (80 nmol mol−1) and elevated CO2 (700 μmol mol−1), alone and in combination, were studied on young trees of Quercus mongolica. The results showed that elevated O3 increased malondialdehyde content and decreased photosynthetic rate after 45 days of exposure, and prolonged exposure (105 days)
induced significant increase in electrolyte leakage and reduction of chlorophyll content. All these changes were alleviated
by elevated CO2, indicating that oxidative stress on cell membrane and photosynthesis was ameliorated. After 45 days of exposure, elevated
O3 stimulated activities of superoxide dismutase (SOD, EC 1.15.1.1) and ascorbate peroxidase (APX, EC 1.11.1.11), but the stimulation
was dampened under elevated CO2 exposure. Furthermore, ascorbate (AsA) and total phenolics contents were not higher in the combined gas treatment than those
in elevated O3 treatment. It indicates that the protective effect of elevated CO2 against O3 stress was achieved hardly by enhancing ROS scavenging ability after 45 days of exposure. After 105 days of exposure, elevated
O3 significantly decreased activities of SOD, catalase (CAT, EC 1.11.1.6) and APX and AsA content. Elevated CO2 suppressed the O3-induced decrease, which could ameliorate the oxidative stress in some extent. In addition, elevated CO2 increased total phenolics content in the leaves both under ambient O3 and elevated O3 exposure, which might contribute to the protection against O3-induced oxidative stress as well. 相似文献
11.
Yanmei Duan Na Li Chao Liu Huiting Liu Yaling Cui Han Wang Fashui Hong 《Biological trace element research》2010,136(3):302-313
In order to study the mechanisms underlying the effects of TiO2 nanoparticles on lactate dehydrogenase (LDH, EC1.1.1.27), Institute of Cancer Research region mice were injected with nanoparticulate
anatase TiO2 (5 nm) of various doses into the abdominal cavity daily for 14 days. We then examined LDH activity in vivo and in vitro and
direct evident for interaction between nanoparticulate anatase TiO2 and LDH using spectral methods. The results showed that nanoparticulate anatase TiO2 could significantly activate LDH in vivo and in vitro; the kinetics constant (Km) and Vmax were 0.006 μM and 1,149 unit mg−1 protein min−1, respectively, at a low concentration of nanoparticulate anatase TiO2, and 3.45 and 0.031 μM and 221 unit mg−1 protein min−1, respectively, at a high concentration of nanoparticulate anatase TiO2. By fluorescence spectral assays, the nanoparticulate anatase TiO2 was determined to be directly bound to LDH, and the binding constants of the binding site were 1.77 × 108 L mol−1 and 2.15 × 107 L mol−1, respectively, and the binding distance between nanoparticulate anatase TiO2 and the Trp residue of LDH was 4.18 nm, and nanoparticulate anatase TiO2 induced the protein unfolding. It was concluded that the binding of nanoparticulate anatase TiO2 altered LDH structure and function. 相似文献
12.
Guillermo Quijano Alberto Ordaz Raúl Muñoz Frédéric Thalasso 《Biotechnology letters》2010,32(2):223-228
Numerous reports show that both transfer and uptake of poorly-water soluble substrates are significantly enhanced in two-phase
partitioning bioreactors (TPPBs). A number of hypotheses have been put forward to explain these enhancements and among them,
the occurrence of direct substrate or oxygen uptake from the vector/water interface has been suggested. The objective of this
paper was to quantify the direct oxygen uptake from the vector/water interface in a culture of Pseudomonas putida, performed in a stirred tank reactor, using glucose as substrate and silicone oil as vector. Despite of a sufficient dissolved
O2 concentration in the vector phase (17 mg l−1) and a significant vector surface area (4,000 m−1) no significant direct O2 uptake from the vector/water interface was observed, compared to O2 uptake from the aqueous phase. From these results it was concluded that, direct O2 or substrate uptake from the vector/water interface might not be significant in TPPBs. 相似文献
13.
Sánchez Fernández JF González-López CV Acién Fernández FG Fernández Sevilla JM Molina Grima E 《Applied microbiology and biotechnology》2012,94(3):613-624
This paper focuses on modelling the growth rate and exopolysaccharides production of Anabaena sp. ATCC 33047, to be used in carbon dioxide removal and biofuels production. For this, the influence of dilution rate, irradiance
and aeration rate on the biomass and exopolysaccharides productivity, as well as on the CO2 fixation rate, have been studied. The productivity of the cultures was maximum at the highest irradiance and dilution rate
assayed, resulting to 0.5 gbio l−1 day−1 and 0.2 geps l−1 day−1, and the CO2 fixation rate measured was 1.0 gCO2 l−1 day−1. The results showed that although Anabaena sp. was partially photo-inhibited at irradiances higher than 1,300 μE m−2 s−1, its growth rate increases hyperbolically with the average irradiance inside the culture, and so does the specific exopolysaccharides
production rate. The latter, on the other hand, decreases under high external irradiances, indicating that the exopolysaccharides
metabolism hindered by photo-damage. Mathematical models that consider these phenomena have been proposed. Regarding aeration,
the yield of the cultures decreased at rates over 0.5 v/v/min or when shear rates were higher than 60 s−1, demonstrating the existence of thus existence of stress damage by aeration. The behaviour of the cultures has been verified
outdoors in a pilot-scale airlift tubular photobioreactor. From this study it is concluded that Anabaena sp. is highly recommended to transform CO2 into valuable products as has been proved capable of metabolizing carbon dioxide at rates of 1.2 gCO2 l−1 day−1 outdoors. The adequacy of the proposed equations is demonstrated, resulting to a useful tool in the design and operation
of photobioreactors using this strain. 相似文献
14.
We determined the interactive effects of irradiance, elevated CO2 concentration (EC), and temperature in carrot (Daucus carota var. sativus). Plants of the cv. Red Core Chantenay (RCC) were grown in a controlled environmental plant growth room and exposed to 3
levels of photosynthetically active radiation (PAR) (400, 800, 1 200 μmol m−2 s−1), 3 leaf chamber temperatures (15, 20, 30 °C), and 2 external CO2 concentrations (C
a), AC and EC (350 and 750 μmol mol−1, respectively). Rates of net photosynthesis (P
N) and transpiration (E) and stomatal conductance (g
s
) were measured, along with water use efficiency (WUE) and ratio of internal and external CO2 concentrations (C
i/C
a). P
N revealed an interactive effect between PAR and C
a. As PAR increased so did P
N under both C
a regimes. The g
s
showed no interactive effects between the three parameters but had singular effects of temperature and PAR. E was strongly influenced by the combination of PAR and temperature. WUE was interactively affected by all three parameters.
Maximum WUE occurred at 15 °C and 1 200 μmol m−2 s− 1 PAR under EC. The C
i
/C
a
was influenced independently by temperature and C
a. Hence photosynthetic responses are interactively affected by changes in irradiance, external CO2 concentration, and temperature. EC significantly compensates the inhibitory effects of high temperature and irradiance on
P
N and WUE. 相似文献
15.
Vasil'ev LA Dzyubinskaya EV Kiselevsky DB Shestak AA Samuilov VD 《Biochemistry. Biokhimii?a》2011,76(10):1120-1130
Ubiquinone or plastoquinone covalently linked to synthetic decyltriphenylphosphonium (DTPP+) or rhodamine cations prevent programmed cell death (PCD) in pea leaf epidermis induced by chitosan or CN−. PCD was monitored by recording the destruction of cell nuclei. CN− induced the destruction of nuclei in both epidermal cells (EC) and guard cells (GC), whereas chitosan destroyed nuclei in
EC not in GC. The half-maximum concentrations for the protective effects of the quinone derivatives were within the pico-
and nanomolar range. The protective effect of the quinones was removed by a protonophoric uncoupler and reduced by tetraphenylphosphonium
cations. CN−-Induced PCD was accelerated by the tested quinone derivatives at concentrations above 10−8–10−7 M. Unlike plastoquinone linked to the rhodamine cation (SkQR1), DTPP+ derivatives of quinones suppressed menadione-induced H2O2 generation in the cells. The CN−-induced destruction of GC nuclei was prevented by DTPP+ derivatives in the dark not in the light. SkQR1 inhibited this process both in the dark and in the light, and its effect
in the light was similar to that of rhodamine 6G. The data on the protective effect of cationic quinone derivatives indicate
that mitochondria are involved in PCD in plants. 相似文献
16.
The histochemical and cytochemical localization of abscisic acid (ABA)-induced H2O2 production in leaves of maize (Zea mays L.) plants were examined, using 3,3-diaminobenzidine (DAB) and CeCl3 staining, respectively, and the relationship between ABA-induced H2O2 production and ABA-induced subcellular activities of antioxidant enzymes was studied. H2O2 generated in response to ABA treatment was detected within 0.5 h in major veins of the leaves and maximized at about 2–4 h. In mesophyll and bundle sheath cells, ABA-induced H2O2 accumulation was observed only in apoplast, and the greatest accumulation occurred in the walls of mesophyll cells facing large intercellular spaces. Meanwhile, ABA treatment led to a significant increase in the activities of the leaf chloroplastic and cytosolic antioxidant enzymes superoxide dismutase (SOD), ascorbate peroxidase (APX) and glutathione reductase (GR), and pretreatment with the NADPH oxidase inhibitor diphenyleneiodonium (DPI), the O
2
−
scavenger Tiron and the H2O2 scavenger dimethylthiourea (DMTU) almost completely arrested the increase in the activities of these antioxidant enzymes. Our results indicate that the accumulation of apoplastic H2O2 is involved in the induction of the chloroplastic and cytosolic antioxidant enzymes. Moreover, an oxidative stress induced by paraquat (PQ), which generates O
2
−
and then H2O2 in chloroplasts, also up-regulated the activities of the chloroplastic and cytosolic antioxidant enzymes, and the up-regulation was blocked by the pretreatment with Tiron and DMTU. These data suggest that H2O2 produced at a specific cellular site could coordinate the activities of antioxidant enzymes in different subcellular compartments. 相似文献
17.
Subsurface CO<Subscript>2</Subscript> Dynamics in Temperate Beech and Spruce Forest Stands 总被引:1,自引:0,他引:1
Rates of soil respiration (CO2 effluxes), subsurface pore gas CO2/O2 concentrations, soil temperature and soil water content were measured for 15 months in two temperate and contrasting Danish
forest ecosystems: beech (Fagus sylvatica L.) and Norway spruce (Picea abies [L.] Karst.). Soil CO2 effluxes showed a distinct seasonal trend in the range of 0.48–3.3 μmol CO2 m−2 s−1 for beech and 0.50–2.92 μmol CO2 m−2 s−1 for spruce and were well-correlated with near-surface soil temperatures. The soil organic C-stock (upper 1 m including the
O-horizon) was higher in the spruce stand (184±23 Mg C ha−1) compared to the beech stand (93±19 Mg C ha−1) and resulted in a faster turnover time as calculated by mass/flux in soil beneath the beech stand (28 years) compared to
spruce stand (60 years). Observed soil CO2 concentrations and effluxes were simulated using a Fickian diffusion-reaction model based on vertical CO2 production rates and soil diffusivity. Temporal trends were simulated on the basis of observed trends in the distribution
of soil water, temperature, and live roots as well as temperature and water content sensitivity functions. These functions
were established based on controlled laboratory incubation experiments. The model was successfully validated against observed
soil CO2 effluxes and concentrations and revealed that temporal trends generally could be linked to variations in subsurface CO2 production rates and diffusion over time and with depths. However, periods with exceptionally high CO2 effluxes (> 20 μmol CO2 m−2 s−1) were noted in March 2000 in relation to drying after heavy rain and after the removal of snow from collars. Both cases were
considered non-steady state and could not be simulated. 相似文献
18.
Sarra El Ichi Anna Miodek Hélène Sauriat-Dorizon Jean-Pierre Mahy Céline Henry Mohamed Nejib Marzouki Hafsa Korri-Youssoufi 《Journal of biological inorganic chemistry》2011,16(1):157-172
Structural characterization and study of the activity of new POX1B protein from garlic which has a high peroxidase activity and can be used as a biosensor for the detection of hydrogen peroxide
and phenolic compounds were performed and compared with the findings for other heme peroxidases. The structure–function relationship
was investigated by analysis of the spectroscopic properties and correlated to the structure determined by a new generation
of high-performance hybrid mass spectrometers. The reactivity of the enzyme was analyzed by studies of the redox activity
toward various ligands and the reactivity with various substrates. We demonstrated that, in the case of garlic peroxidase,
the heme group is pentacoordinated, and has an histidine as a proximal ligand. POX1B exhibited a high affinity for hydrogen peroxide as well as various reducing cosubstrates. In addition, high enzyme specificity
was demonstrated. The k
cat and K
M values were 411 and 400 mM−1 s−1 for 3,3′,5,5′-tetramethylbenzidine and 2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid), respectively. Furthermore, the
reduction of nitro compounds in the presence of POX1B was demonstrated by iron(II) nitrosoalkane complex assay. In addition, POX1B showed a great potential for application for drug metabolism since its ability to react with 1-nitrohexane in the presence
of sodium dithionite was demonstrated by the appearance of a characteristic Soret band at 411 nm. The high catalytic efficiency
obtained in the case of the new garlic peroxidase (POX1B) is suitable for the monitoring of different analytes and biocatalysis. 相似文献
19.
The effects of Ca(NO3)2 stress on biomass production, oxidative damage, antioxidant enzymes activities and polyamine contents in roots of grafted
and non-grafted tomato plants were investigated. Results showed that when exposed to 80 mM Ca(NO3)2 stress, the biomass production reduction in non-grafted plants was more significant than that of grafted plants. Under Ca(NO3)2 stress, superoxide anion radical (O2•−) producing rate, hydrogen peroxide (H2O2) and malondialdehyde (MDA) contents of non-grafted plants roots were significantly higher than those of grafted plants, however,
nitrate (NO3
−), ammonium (NH4
+) and proline contents, superoxide dismutase (SOD, EC1.15.1.1), peroxidase (POD, EC1.11.1.7), catalase (CAT, EC1.11.1.6) and
arginine decarboxylase (ADC, EC 4.1.1.19) activities of grafted plants roots were significantly higher than those of non-grafted
plants. Regardless of stress, free, conjugated and bound polyamine contents in roots of grafted plants were significantly
higher than those of non-grafted plants. The possible roles of antioxidant enzymes, prolines and polyamines in adaptive mechanism
of tomato roots to Ca(NO3)2 stress were discussed.
Gu-Wen Zhang and Zheng-Lu Liu contributed equally to this work. 相似文献
20.
Y. Kitaya L. Xiao A. Masuda T. Ozawa M. Tsuda K. Omasa 《Journal of applied phycology》2008,20(5):737-742
Symbiotic dinoflagellates of the species Amphidinium are expected to be pharmaceutically useful microalgae because they produce antitumor macrolides. A microalgae production
system with a large number of cells at a high density has been developed for the efficient production of macrolide compounds.
In the present study, the effects of culture conditions on the cellular growth rate of dinoflagellates were investigated to
determine the optimum culture conditions for obtaining high yields of microalgae. Amphidinium species was cultured under conditions with six temperature levels (21–35°C), six levels of photosynthetic photon flux density
(15–70 μmol photons m−2 s−1), three levels of CO2 concentration (0.02–0.1%), and three levels of O2 concentration (0.2–21%). The number of cells cultured in a certain volume of solution was monitored microscopically and the
cellular growth rate was expressed as the specific growth rate. The maximum specific growth rate was 0.022 h−1 at a temperature of 26°C and O2 concentration of 5%, and the specific growth rate was saturated at a CO2 concentration of 0.05%, a photosynthetic photon flux density of 35 μmol photons m−2 s−1 and a photoperiod of 12 h day−1 upon increasing each environmental parameter. The results demonstrate that Amphidinium species can multiply efficiently under conditions of relatively low light intensity and low O2 concentration. 相似文献