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1.
Leaves of Pelargonium zonale L. and Spinacia oleracea L. were fumigated with high concentrations of SO2 for very short periods of time with the aim of first producing acute symptoms of damage and then observing repair. The response of different photosynthetic parameters to SO2 was monitored during and after fumigation. The following results were obtained: (1) Inhibition of CO2 assimilation in the light was accompanied by increased reduction of the quinone acceptor, QA, of photosystem II and by increased oxidation of the electrondonor pigment P700 of photosystem I. Increased control of photosystem II activity in the SO2-inhibited state was also indicated by increased light scattering and by increased non-photochemical quenching of chlorophyll fluorescence. Both are indicators of chloroplast energization. Apparently, SO2 did not decrease but rather increased energization of the chloroplast thylakoid system by light. (2) Accumulation of dihydroxyacetone phosphate, fructose-1,6-phosphate and ribulose-1,5-phosphate and a decrease of 3-phosphoglycerate and hexosephosphate indicated that SO2 inhibited enzymes of the Calvin cycle. (3) Stimulated postillumination CO2 evolution suggested that when photosynthesis declined respiration increased to provide energy for repair reactions. (4) Increased leaf absorbance at 505 nm indicated increased stimulation of zeaxanthin formation in thylakoid membranes under the influence of SO2. A similar increase in 505-nm absorbance could be induced by high concentrations of CO2. In darkened leaves, SO2 did not produce changes in 505-nm absorbance. (5) While zeaxanthin formation was stimulated, changes in the fluorescence of the pH-indicating dye pyranine, which had been fed to the leaves, indicated acidification of the cytoplasm of leaf cells by SO2. Maximum acid production by SO2 required light. In contrast, cytoplasmic acidification of leaf cells by CO2 was similar in the light and in the dark. (6) Since zeaxanthin formation is known to depend on the acidification of the thylakoid lumen, SO2-dependent zeaxanthin formation indicated SO2-dependent acidification of the thylakoid lumen as the indirect result of cytoplasmic acidification by SO2. (7) Inhibition of photosynthesis and other effects of SO2 were fully reversible in the light. Detoxification of SO2 and reactivation of the photosynthetic apparatus were slow or absent in the dark. Light had a dual effect on the action of SO2. Transiently, it first increased the extent of inhibition of assimilation, but, finally, it reversed inhibition. Sulfur dioxide was inhibitory as a consequence of the chemical reactivity of its hydration products rather than as a result of cellular acidification by the produced acid. The initial acidification was followed by an appreciable alkalisation demonstrating the action of the pH-stat mechanism. (8) The data are discussed in relation to SO2 toxicity under field conditions when plants are chronically exposed to polluted air.Abbreviations Chl
chlorophyll
- DHAP
dihydroxyacetone phosphate
- FBP
fructose-1,6-bisphosphate
- F6P
fructoce-6-phosphate
- F, Fm, Fm, Fo, Fo
chlorophyll fluorescence levels
- PGA
3-phosphoglycerate
- P700
primary donor of photosystem I
- QA
primary quinone acceptor of photosystem II
- qp
photochemical quenching of chlorophyll fluorescence
- NPQ
non-photochemical quenching of chlorophyll fluorescence
- RuBP
ribulose-1,5-bisphosphate
Dedicated to Professor O.L. Lange on the occasion of his 65th birthdayOn leave from the Centre for Multidisciplinary Sciences, University of Belgrade, YugoslaviaThis work was supported by the Deutsche Forschungsgemeinschaft within the Sonderforschungsbereich 251 of the University of Würzburg. S. V.-J. acknowledges support by the Leibniz program of the Deutsche Forschungsgemeinschaft and by the Fonds for Science of the Republic of Serbia (contract no. 8604). We are grateful to Drs. Z.-H. Yin, U. Takahama and K.-J. Dietz (Julius-von-Sachs-Institut für Biowissenschaften, Universität Würzburg, FRG) for cooperation and helpful discussions. 相似文献
2.
Slovik Stefan Siegmund Alfred Kindermann Gerald Riebeling Rüdiger Balázs Árpad 《Plant and Soil》1995,(1):405-419
Monthly uptake rates and the annual deposition of gaseous SO2 via the stomata of six Norway spruce canopies (Picea abies (L.) Karst.) in Germany (Königstein im Taunus, Witzenhausen, Grebenau, Frankenberg, Spessart, Fürth im Odenwald) were calculated (i) from statistical response functions of stomatal aperture depending on meteorological data, and (ii) from the synchronously measured SO2 immission at these stands. The stomatal response functions had been derived on the basis of thorough stomatal water conductance measurements in the field. Calculations of the SO2 conductance of spruce twigs and SO2 uptake rates via stomata need continuously measured complete data sets of the (i) light intensity, (ii) air temperature, (iii) air humidity and (iv) SO2 concentration in spruce forests from all the year. These data were recorded half hourly in different German spruce forests. The apparent needle water vapour pressure difference and transpiration rates were calculated from meteorological data. Additional use of canopy through flow data in dry years allowed the estimation of the mean stomatal conductance for H2O and SO2 of whole spruce canopies. The annual SO2 uptake of a mean unit needle surface in spruce forests was 32% of the SO2 uptake rate of exposed needles at the top of spruce crowns. There is significant SO2 uptake all the year. The mean SO2 dose at all sites and years received through the stomata was (0.25±0.07) mol SO2 m-2 (total needle surface) (nPa Pa-1)-1 (annual mean of SO2 immission; 1 nPa (SO2) Pa-1 (air) = 1 ppb) day-1 (vegetation period per year). Comparison of calculated SO2 uptake rates into needles with measured SO4
2- accumulation rates in needles from the mentioned sites and additionally from Würzburg, Schneeberg (Fichtelgebirge) and from three sites in the eastern Erzgebirge (Höckendorf, Kahleberg, Oberbärenburg) revealed that oxidative SO2 detoxification (SO4
2- formation) dominates only at sites with high SO2 immission and short vegetation periods. Under these conditions 70 to 90% of the annual stomatal SO2 uptake is detoxified via SO4
2- accumulation in needles. Cations are needed for neutralization of accumulating SO4
2- which are inavailable to support growth. Thus, SO2 induces a dominant and competitive additional nutrient cation demand, cation deficiency symptoms and enhanced needle loss (spruce decline symptoms) mainly at sites, where the ratio R=(SO2 immission): (length of the vegetation period) is higher than R=0.07 nPa Pa-1 day-1. Correlation analysis of the relative needle loss versus the SO2-dependent SO4
2- formation rate revealed a significant increase of needle loss at the 98% level (Student). At sites with small SO2 immission and long vegetation periods (R<0.07 nPa Pa-1 day-1) reductive SO2 detoxification via growth (and/or phloem export of SO4
2-) is not kinetically overburdened. Under these conditions only 30% of the annual SO2 uptake is detoxified via SO4
2- formation and spruce decline is small or absent. On the basis of the critical value R0.07 nPa Pa-1 day-1 recommended SO2 immission limits can be deduced on a mere ecophysiological basis. These deduced values are close to the proposed SO2 immission limits of the IUFRO, WHO and the UNECE. 相似文献
3.
V. Mugica-Alvarez A. Hernández-Moreno B. L. Valle-Hernández F. A. Espejo-Montes F. Millán-Vázquez M. Torres-Rodríguez 《人类与生态风险评估》2017,23(5):1056-1071
Sugarcane processing emits atmospheric pollutants due to sugar mill operation as well as customary fields burning, intended to ease post harvesting land preparation and to minimize inherent wastes. Three atmospheric monitoring campaigns were conducted in the municipality of Zacatepec, Mexico. The data obtained were used to calibrate a Gaussian model built into a Geographic Information System, aimed at modeling a large number of plots from the burn database of the Zone of Zacatepec. During the sugarcane harvesting time and sugar mill operation, particulate matter (PM) concentrations went up to five- and threefold greater for PM10 and PM2.5, respectively, than during the period without the agro-industrial process. The PM10 and PM2.5 concentrations decreased between 39 and 43% when biomass burning activities stopped. In addition, measurements of 17 polycyclic aromatic hydrocarbons showed also the highest concentrations during the burning and sugar mill operating periods, where the most abundant of these compounds corresponded to those with the highest molecular weight displaying carcinogenic properties. Maps obtained of particles and benzo[a]pyrene equivalent concentrations allowed determining the populations mostly exposed, which are useful for the design of policies related to adequate conditions for agriculture burning, including the suitability of continuing with such practice. 相似文献
4.
二氧化硫是大气主要污染物之一,可对植物的关键生理过程光合作用产生重要影响。利用密闭环境控制室熏气处理,研究不同浓度(自然状态下浓度、0.5mg·L-1、1.5mg·L-1、3.0mg·L-1)SO2对盆栽巨桉和天竺桂幼树叶绿素含量、光响应曲线、光合特征参数、光合日变化及硫含量的影响。结果表明:(1)SO2胁迫显著减少了巨桉叶绿素a、b含量,且叶绿素a/b值显著降低,而天竺桂在SO2胁迫下叶绿素a、b含量显著增加,叶绿素a/b值无显著影响。(2)SO2胁迫显著抑制了两树种的净光合速率(Pn);在SO2胁迫下巨桉气孔导度(Gs)、胞间CO2浓度(Ci)和蒸腾速率(Tr)显著上升,而天竺桂的Gs和Tr显著被SO2抑制,Ci随SO2浓度的增加先升高后降低。(3)巨桉表观量子效率(AQY)、暗呼吸速率(Rd)、光补偿点(LCP)和光饱和点(LSP)及天竺桂Rd和LCP均随着SO2浓度的增加而先升高后降低,而天竺桂的AQY和LSP逐渐降低。(4)一天中,SO2胁迫显著提高了巨桉Pn、Gs和Tr,而对天竺桂Pn无显著影响,较低浓度SO2胁迫显著促进了天竺桂Gs和Tr,高浓度SO2胁迫则显著抑制其Gs和Tr;SO2胁迫显著抑制了两种植物的Ci。(5)SO2胁迫下,巨桉和天竺桂幼树叶片硫含量均显著增加。研究认为,巨桉对较低浓度的SO2胁迫有一定的适应能力,但对高浓度SO2胁迫的抗性不如天竺桂强,这可能与二者不同的叶片形态及生理特性有关。 相似文献
5.
There are six different vitamin B6 (VB6) forms, pyridoxal (PL), pyridoxamine (PM), pyridoxine (PN), pyridoxal 5′-phosphate (PLP), pyridoxamine 5′-phosphate (PMP), and pyridoxine 5′-phosphate (PNP), of which PLP is the active form. Although plants are a major source of VB6 in the human diet, and VB6 plays an important role in plants, the mechanisms underlying the interconversions of different VB6 forms are not well understood. In this study, in vitro tobacco plants were grown on Murashige and Skoog (MS) basal media supplemented with 100 mg/L of PM, PL or PN and the abundance of the different B6 vitamers in leaf tissue was quantified by high performance liquid chromatography (HPLC). The total amount of VB6 was about 3.9 μg/g fresh weight of which PL, PM, PN, PLP and PMP accounted for 23%, 14%, 37%, 20% and 6%, respectively. Tobacco plants contained a trace amount of PNP. Supplementation of the culture medium with any of the non-phosphorylated vitamers resulted in an increase in total VB6 by about 10-fold, but had very little impact on the concentrations of the endogenous phosphorylated vitamers. Administration of either PM or PN increased their endogenous levels more than the levels of any other endogenous B6 vitamers. PL supplementation increased the levels of plant PN and PM significantly, but not that of PL, suggesting that efficient conversion pathways from PL to PN and PM are present in tobacco. Additionally, maintenance of a stable level of PLP in the plant is not well-correlated to changes in levels of non-phosphorylated forms. 相似文献
6.
采用平行同步采样法,于2012年雨季,对广州市大夫山森林公园林内外空气的总悬浮颗粒物(TSP)和细颗粒物(PM2.5)样品进行了24 h收集,测定了TSP和PM2.5的质量浓度并分析了样品中水溶性无机离子成分。结果表明:林内外PM2.5的质量浓度平均值分别为(40.18±10.47)和(55.79±13.01) g/cm3;林内外TSP的质量浓度分别为(101.32 ± 33.19)和(116.61±35.36) g/cm3。林内与林外比,PM2.5和TSP平均质量浓度都显著减少(P < 0.05),表明森林能显著改善空气环境质量。TSP和PM2.5中SO42-、Na+、NH4+和NO3-为水溶性无机离子主要成分,占总离子质量的80%以上,林外这些离子的浓度高于林内(NH4+除外)。这4种离子雨季在空气中的主要存在方式为NaCl、Na2SO4、NH4HSO4和NH4NO3。计算表明,采样期间海盐对大夫山空气TSP和PM2.5的水溶性组分中Na+和Cl-贡献最大,其它元素主要源自陆地源。林内外TSP和PM2.5的c(NO3-)/c(SO42-)比值在0.3以下,表明固定源是大夫山森林公园空气主要污染贡献者,TSP中c(NO3-)/c(SO42-)的比值大于PM2.5的比值,说明移动源对TSP的贡献大于PM2.5。 相似文献
7.
Summary Changes in epicuticular wax morphology of Pseudotsuga menziesii needles were studied with scanning electron microscopy throughout the growing season in current-year and older needles in 20 trees from two sites, Kootwijk and Garderen (The Netherlands). Fusion of crystalline wax rods leading to a reticulate structure and ultimately to degradation of the regular three-dimensional porous structure started several weeks after bud break and reached a high level at the end of the first growing season. The increase in amorphous (solid) wax showed a similar, but slightly slower development. In 1- and 2-year-old needles the degradation of crystalline wax and increase in amorphous wax had progressed only slightly further. The rates of change in crystalline wax morphology were very similar for sun-exposed and shaded needles, for the two sites, and for the two tree vitality classes included in the samples. The development of epiphyllous fungi also appeared to be largely needle age dependent. The effects of NH3 on needle wax morphology were studied in young trees used in fumigation experiments. Short-term fumigation (approx. 5 weeks) did not affect wax morphology in current-year needles, but 1-year-old needles which had been exposed to different concentrations from bud break onwards showed a severe degradation of the crystalline wax, regardless of the NH3 concentration used. In 2-yearold needles the effect of NH3 could not be traced and was overshadowed by the natural ageing process. Ambient O3, SO2 and NOx levels did not effect epicuticular wax morphology. It is suggested that the variation recorded for the two forest stands does not show effects of local pollution levels. 相似文献
8.
《Free radical research》2013,47(1):601-607
Exposure of Lemma sp. to SO2 resulted in an increased activity of superoxide dismutase. About 3 to 4 fold increase in the activity was observed within 30 minutes after the plants were fumigated with 10 ml/l of SO2. Paraquat, a well known superoxide generator, doubled the enzyme activity after 1 hour of treatment with 0.1 mM paraquat. Superoxide dismutase activity was also enhanced by cadmium treatment but the response was not immediate. Optimum increase in the activity of enzyme was observed after 4 days of treatment with 40 mg/l of cadmium in the medium. Treatment with H2O2 very clearly inhibited the activity of superoxide dismutase in Lemna. 相似文献
9.
Eng-Chong Pua Elena Ragolsky Stephen F. Chandler Trevor A. Thorpe 《Plant Cell, Tissue and Organ Culture》1985,5(1):55-62
Callus of tobacco (Nicotiana tabacum L. cv. Wisconsin 38) was grown on callus-proliferating (CP) and shoot-forming (SF) media with elevated sodium sulfate (Na2SO4) concentrations either in the light or dark for more than one year. An increase in Na2SO4 concentration resulted in a decrease in callus growth index, an increase in percent dry weight of callus tissues grown on both media, and a decrease in both number of calli forming shoots and number of shoots per callus in SF medium. The CP callus grown in the light spontaneously began to form shoots after the 5th monthly transfer, and spontaneous root formation occured after the 16th transfer in the presence of 0.75 and 1.0% Na2SO4. Both water () and osmotic (s) potentials of the callus increased with increasing Na2SO4 concentration; and callus exhibited greater and s in the light than dark for both CP and SF media. 相似文献
10.
While sulfur dioxide (SO2) has been previously known for its toxicological effects, it is now known to be produced endogenously in mammals from sulfur-containing amino acid l-cysteine. l-cysteine is catalyzed by cysteine dioxygenase (CDO) to l-cysteinesulfinate, which converts to β-sulfinylpyruvate through transamination by aspartate aminotransferase (AAT), and finally spontaneously decomposes to pyruvate and SO2. The present study explored endogenous SO2 production, and AAT and CDO distribution in different rat tissue. SO2 content was highest in stomach, followed by tissues in the right ventricle, left ventricle, cerebral gray matter, pancreas, lung, cerebral white matter, renal medulla, spleen, renal cortex and liver. AAT activity and AAT1 mRNA expression were highest in the left ventricle, while AAT1 protein expression was highest in the right ventricle. AAT2 and CDO mRNA expressions were both highest in liver tissue. AAT2 protein expression was highest in the renal medulla, but CDO protein expression was highest in liver tissue. In all tissues, AAT1 and AAT2 were mainly distributed in the cytoplasm rather than the nucleus. These observed differences among tissues endogenously generating SO2 and associated enzymes are important in implicating the discovery of SO2 as a novel endogenous signaling molecule. 相似文献
11.
The vasodilatation of sulfur dioxide (SO2) derivatives on the rat thoracic aortic rings and its cell signal transduction pathway were studied. The levels of cAMP, cGMP, PGI2, TXA2 and activities of PKA and adenylyl cyclase (AC) in the rings exposed to SO2 derivatives were determined. The results indicated that SO2 derivatives could dose-dependently relax the isolated rat aorta rings with or without endothelium precontracted by NE, no difference was found between the rings with and without endothelium; Levels of cAMP, PGI2, AC activity and PKA activity in the aortic rings were significantly increased by the derivatives in a dose-related way; No change of cGMP and TXA2 levels in rings was observed; cAMP/cGMP and PGI2/TXA2 ratios were increased significantly by the SO2 derivatives. These results led to the conclusions that SO2 derivatives might cause the endothelium-independent vasorelaxation effect, and the vasorelaxation was mediated in partly by the signal transduction pathway of PGI2-AC-cAMP-PKA. 相似文献
12.
The characterization of indoor (a naturally ventilated office) and outdoor (adjacent courtyard) metals in PM2.5 during a winter period in Xi'an, China were carried out. The results indicated that the average mass concentrations of PM2.5 in indoor and outdoor environments all exceeded the daily average limit of 75 µg m–3 set by the Chinese government. The dominant metals in PM2.5 were Ca, Al, Zn, Mg, Fe, and Pb in both indoor and outdoor air. Concentration of As was much higher than the standard of 6 ng m–3 issued by the government. Enrichment factor analysis showed that anthropogenic emissions might be the primary sources of As, Cd, Pb, and Zn, while crust was the main origin of Co. A majority of indoor-to-outdoor concentration ratios of metal were lower than 1 indicating mostly the contribution of outdoor sources rather than indoor ones. As and Cr in both indoor and outdoor air posed the highest noncarcinogenic and carcinogenic risks, respectively. The noncarcinogenic and carcinogenic risks were 2.74 and 2.54 × 10?4 indoor and 4.04 and 3.87 × 10?4 outdoor, which suggested that possible adverse health effects should be of concern. 相似文献
13.
The effects of exposure to 0.5–0.7 ppm SO2 for about one month on the dry weight growth and net photosynthesis ofPolygonum cuspidatum were investigate. Furthermore, the carbon and nitrogen concentrations in each plant organ were measured. The results obtained
showed no significant decrease in the total dry weight of SO2-treated plants in comparison with controls. On the other hand, the leaf area (LA) and/or leaf dry weight of SO2-treated plants were increased, and the root dry weight (RW) was decreased, in comparison with controls. The leaf carbon assimilation rate (CAR) in SO2-treated plants was slightly decreased in spite of a clear decrease in net photosynthesis, and the value of (SW+RW)/LA (SW stem dry weight) was decreased in comparison with controls, thus minimizing the reduction in CAR. Furthermore, the ratio
of total leaf carbon absorption (leaf area x CAR) to total root nitrogen absorption (root dry weight x nitrogen assimilation
rate) in SO2-treated plants was similar to that in controls. From these results, it can be concluded that an increase in leaf area and/or
leaf dry weight and a decrease in root dry weight inP. cuspidatum under SO2 stress may be induced in order to compensate for the decrease in CAR and to maintain the ratio of total leaf carbon absorption
to total root nitrogen absorption in the early stage of vegetative growth. 相似文献
14.
The indoor air quality (IAQ) in classrooms highly affects the health and productivity of students. This article aims to clarify seasonal variation in indoor environment and sick building syndromes (SBS) symptoms in an Eastern Mediterranean climate. A series of field measurements were conducted during the fall and winter seasons from October 2011 to March 2012 in 12 naturally ventilated schools located in the Gaza Strip. Data on environmental perception and health symptoms were obtained from 724 students by using a validated questionnaire. The results showed that indoor PM10 and PM2.5 concentrations were 426.3 ± 187.6 μg/m3 and 126.6 ± 94.8 μg/m3, respectively. The CO2 concentrations and ventilation rate widely exceeded their reference values during the winter season. The prevalence rates of general symptoms were relatively high at baseline assessment in the fall season and increased significantly during follow-up in the winter season. Significant increases in disease symptoms such as mucosal irritation and pre-existing asthma symptoms among students could be related to poor indoor air quality. Five distinct groups of SBS symptoms from factor analysis of students’ related symptoms were significantly correlated with PM10 and PM2.5, CO2, ventilation rate, and indoor temperature. As vulnerable children, this situation negatively affects their school performance and health. 相似文献
15.
Summary The purpose of this study was to investigate the phytotoxicity of nitrapyrin 2-chloro-6-(trichloromethyl)pyridine to sunflower
(Helianthus annuus L.) under different N regimes and to see if N forms affect the phytotoxicity of nitrapyrin. Sunflower was grown in pot culture
for 21 days and was fertilized with (NH4)2SO4, NH4NO3 and NaNO3 to provide 0, 100 and 200 ppm N and with nitrapyrin application of 0 and 20 ppm. All N-treated sunflower plants in all N
regimes and regardless of titrapyrin treatment produced more root and shoot dry weights and contained a significantly higher
N than untreated check. Nitrapyrin toxicity appeared as a curling of leaf margin and a tendril type of stem growth, the visible
toxicity symptoms decreased in the order: (NH4)2SO4>NH4NO3>NaNO3. Furthermore nitrapyrin addition suppressed sunflower growth in each N regime, the suppressing effect being greater with
(NH4)2SO4 and NH4NO3 than as with NaNO3. Although, shoot growth from plants receiving nitrapyrin was not significantly affected by any N regime, root growth of nitrapyrin-treated
plants was somewhat restricted by NH4
+−N nutrition relative to NO3
−−N nutrition. 相似文献
16.
The Impact of Indigenous Microorganisms on the Mineral Corrosion and Mineral Trapping in the SO2 Co-injected CO2-Saline-Sandstone Interaction 总被引:1,自引:0,他引:1
Fengjun Zhang Yunpeng Song Chenyang Li Shengyu Zhang Kai Fan 《Geomicrobiology journal》2019,36(2):110-122
The impact of indigenous microorganisms on the mineral corrosion and mineral trapping in the SO2 co-injected CO2-saline-sandstone interaction was investigated in this study by lab experiments under 55?°C, 15?M pa. The results verified that co-injection of SO2 resulted in a decrease in biomass and shifts in microbial communities within 90?days, but some microorganisms still could adapt to acidic, high-temperature, high-pressure, and high-salinity environments. Firmicutes and Proteobacteria remained dominant phylum, but phylum Proteobacteria showed better tolerance to the co-injection of SO2 in the initial period. In the SO2 co-injected CO2-saline-sandstone interaction under microbial mediation, acid-producing bacteria further promoted the corrosion of K-feldspar, albite, and clay minerals, meanwhile mobilizing more K+, Na+, Ca2+, Mg2+ into solution. The acidogenic effect may be linked to the dominant genus of Bacillus, Paenibacillus, Acinetobacter, Pseudomonas and Exiguobacterium. Co-injection of SO2 inhibited the carbonates capture, while microbial acid production further reduced the pH, further inhibiting carbonates capture. As a result, no secondary carbonate (e.g., calcite) was observed on a short time scale within 90?days. So, microbial acidogenic effect was not conducive to carbonates capture in short term. 相似文献
17.
茉莉酸类物质(JAs)作为与昆虫啃噬及损伤相关的植物激素和信号分子在植物防御反应中起重要作用,但是茉莉酸引起的早期防御反应的机理仍不清楚。该研究以拟南芥叶片保卫细胞为材料,结合非损伤微测(NMT)及激光共聚焦技术探讨了茉莉酸诱导的保卫细胞中质膜H+-ATPase与H2O2积累的调控关系。结果表明:茉莉酸甲酯(MeJA)处理导致H+迅速跨膜外排和H2O2积累,H+外排和H2O2积累能够被钒酸钠抑制,而二苯基碘(DPI)处理则对MeJA诱导的H+跨膜外排无显著影响。研究结果证明,在MeJA诱导的早期信号事件中,质膜H+-ATPase的激活先于H2O2的产生。 相似文献
18.
Effects of Elevated Atmospheric CO2 Concentrations on CH4 and N2O Emission from Rice Soil: An Experiment in Controlled-environment Chambers 总被引:1,自引:0,他引:1
The effects of elevated concentrations of atmospheric CO2 on CH4 and N2O emissions from rice soil were investigated in controlled-environment chambers using rice plants growing in pots. Elevated
CO2 significantly increased CH4 emission by 58% compared with ambient CO2. The CH4 emitted by plant-mediated transport and ebullition–diffusion accounted for 86.7 and 13.3% of total emissions during the flooding
period under ambient level, respectively; and for 88.1 and 11.9% of total emissions during the flooding period under elevated
CO2 level, respectively. No CH4 was emitted from plant-free pots, suggesting that the main source of emitted CH4 was root exudates or autolysis products. Most N2O was emitted during the first 3 weeks after flooding and rice transplanting, probably through denitrification of NO3− contained in the experimental soil, and was not affected by the CO2 concentration. Pre-harvest drainage suppressed CH4 emission but did not cause much N2O emission (< 10 μg N m−2 h−1) from the rice-plant pots at both CO2 concentrations. 相似文献
19.
Pingsheng Wu Lyman J. Roberts Ii Ayumi K. Shintani James R. Sheller Patricia A. Minton Stanley B. Higgins 《Free radical research》2013,47(9):956-962
To investigate changes in oxidant stress during and following acute asthma exacerbations, this stidy measured 2,3-dinor-5,6-dihydro-15-F2t-IsoP (F2-IsoP-M), the major urinary metabolite of 15-F2t-IsoP, in eight asthmatic adults, during and following an asthma hospitalization. F2-IsoP-M concentrations at admission and follow-up were significantly higher than discharge (admission median: 4.12 ng/Cr mg, range 1.89–7.8; follow-up: 2.47 ng/Cr mg (1.56–6.86); discharge: 1.42 ng/Cr mg (0.7–4.44); both p<0.01), but not significantly different between admission and follow-up. F2-IsoP-M concentrations at follow-up were higher than a control group with stable asthma (0.68 ng/Cr mg (0.31–1.5), p=0.0008). In conclusion, asthma exacerbations requiring hospitalization are associated with 6-fold higher urinary F2-IsoP-M concentrations compared to stable asthmatics. F2-IsoP-M concentrations decreased significantly during hospitalization, but significant elevations 3 months following hospitalization suggest ongoing oxidative stress despite clinical improvement. Urinary F2-IsoP-M may be a clinically useful, simple non-invasive systemic measure of oxidative stress in asthmatics, providing information not captured by spirometry or symptoms. 相似文献
20.
By employing metal salts in dilute-acid pretreatment the severity can be reduced due to reduced activation energy. This study reports on a dilute-acid steam pretreatment of spruce chips by addition of a small amount of ferrous sulfate to the acid catalyst, i.e., either SO2, H2SO3 or H2SO4. The utilization of ferrous sulfate resulted in a slightly increased overall glucose yield (from 74% to 78% of the theoretical value) in pretreatment with SO2 and H2SO3. Impregnation with ferrous sulfate and sulfuric acid did not give any improvement compared with pretreatment based solely on H2SO4. 相似文献