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1.
The aim of this study was to examine the protection of the yeast lacking the “antioxidant-like” prion precursor protein (Ure2p), by antioxidants and to elucidate how modification of redox homeostasis affects toxicity of agents inducing oxidative stress in the Δure2 cells. We found a diverse ability of a range of antioxidants to ameliorate the hypersensitivity of the Δure2 disruptant to oxidants and heavy metal ions. Glutathione and then ascorbate were the most effective antioxidants; Tempol, Trolox and melatonin were much less effective or even hampered the growth of the Δure2 cells exposed to tested agents. The intracellular level of ROS was augmented in the Δure2 mutant under normal growth conditions (1.7-fold), and after treatment with H 2O 2 (2.3-fold) and Cd(II) (2.8-fold), with respect to its wild-type counterpart. Glutathione was unable to prevent the increase in ROS production caused by CdCl 2. The Δure2 disruptant was also hypersensitive to heat shock, like mutants lacking glutathione S-transferases. 相似文献
2.
Efficacy of several antioxidants in the protection of the yeast Saccharomyces cerevisiae mutants deficient in CuZnSOD and deficient in glutaredoxin 5 to growth restriction induced by oxidants was studied. Ascorbate and glutathione protected the Δsod1 and Δgrx5 mutants against the effects of t-butyl hydroperoxide and cumene hydroperoxide, Δsod1 mutants against oxytetracycline and Δgrx5 mutants against menadione and 2,2'-azobis-(2-amidinopropane). However, Tempol, Trolox and melatonin were much less effective, showing prooxidative effects and, at high concentrations, hampering the growth of the mutants in the absence of exogenous oxidants. These results point to a complication of cellular effects of antioxidants by their prooxidative effects and to the usefulness of cellular tests to evaluate the biological effectiveness of antioxidants. 相似文献
3.
The effects of forskolin on electrical coupling among pancreatic β-cells were studied. Two microelectrodes were used to measure membrane potentials simultaneously in pairs of islet β-cells. Intracellular injection of a current pulse ( ΔI) elicited a membrane response ΔV1 in the injected cell and also a response ΔV2 in a nearby β-cell confirming the existence of cell-to-cell electrical coupling among islet β-cells. In the presence of glucose (7 mM), application of forskolin evoked a transient depolarization of the membrane and electrical activity suggesting that the drug induced a partial inhibition of the β-cell membrane K + conductance. Concomitant with this depolarization of the membrane there was a marked decrease in β-cell input resistance ( ΔV2/ ΔI) suggesting that exposure to forskolin enhanced intercellular coupling. Direct measurements of the coupling ratio ΔV2/ ΔV1 provided further support to the idea that forskolin enhances electrical coupling among islet cells. Indeed, application of forskolin reversibly increased the coupling ratio. These results suggest that cAMP might be involved in the modulation of electrical coupling among islet β-cells. 相似文献
4.
Two Bacillus strains were isolated from the foregut of the water beetle Agabus affinis (Payk.) and tested for their steroid transforming ability. After incubation with androst-4-en-3,17-dione (AD), 13 different transformation products were detected. AD was hydroxylated at C 6, C 7, C 11 and C 14, resulting in formation of 6 β-, 7 -, 11 - and 14 -hydroxy-AD. One strain also produced small amounts of 6 β,14 -dihydroxy-AD. Partly, the 6 β-hydroxy group was further oxidized to the corresponding 6-oxo steroids. In addition, a specific reduction of the Δ 4-double bond was observed, leading to the formation of 5 -androstane derivatives. In minor yields the carbonyl functions at C 3 and C 17 were reduced leading to the formation of 3 ξ-OH or 17 β-OH steroids. EI mass spectra of the trimethylsilyl and O-methyloxime trimethylsilyl ether derivatives of some transformation products are presented for the first time. 相似文献
5.
1. 1.|In 15 conscious Pekin ducks, 40 “warm sensitive” hypothalamic neurons were identified according to their discharge rates at 40°C Thy (F40), local temperature coefficients (Δ/ΔT) and Q10. 2. 2.|Q10 and either F40 or ΔF/ΔT were little or not related. 3. 3.|A positive correlation between F40 and ΔF/ΔT was observed which was particularly close (r = 0.94 and 0.96) when the neurons were classified according to their Q10 of <2 and >2. 4. 4.|The results suggest that neurons with positive temperature coefficients in the duck's hypothalamus mostly exhibit linear to exponential temperature-discharge relationships. 5. 5.|This is an contrast to observations on mammalian hypothalamic thermosensitive neurons and may relate to the absence of the thermosensory function in the duck's rostral brainstem.
Author Keywords: Neuronal thermosensitivity; hypothalamic thermosensory function; Temperature and synaptic transmission; avian thermoregulation; mammalian thermoregulation 相似文献
6.
Increased ATP/ADP ratio resulting from enhanced glycolysis and oxidative phosphorylation represents a plausible mechanism controlling the glucose-stimulated insulin secretion (GSIS) in pancreatic β-cells. Although specific bioenergetics might be involved, parallel studies of cell respiration and mitochondrial membrane potential (Δ Ψm) during GSIS are lacking. Using high resolution respirometry and parallel Δ Ψm monitoring by two distinct fluorescence probes we have quantified bioenergetics in rat insulinoma INS-1E cells representing a suitable model to study in vitro insulin secretion. Upon glucose addition to glucose-depleted cells we demonstrated a simultaneous increase in respiration and Δ Ψm during GSIS and showed that the endogenous state 3/state 4 respiratory ratio hyperbolically increased with glucose, approaching the maximum oxidative phosphorylation rate at maximum GSIS. Attempting to assess the basis of the “toxic” effect of fatty acids on insulin secretion, GSIS was studied after linoleic acid addition, which diminished respiration increase, Δ Ψm jump, and magnitude of insulin release, and reduced state 3/state 4 dependencies on glucose. Its effects were due to protonophoric function, i.e. uncoupling, since without glucose, linoleic acid accelerated both state 3 and state 4 respiration by similar extent. In turn, state 3 respiration increased marginally with linoleic acid at 10–20 mM glucose. We conclude that upon glucose addition in physiological range, the INS-1E cells are able to regulate the oxidative phosphorylation rate from nearly zero to maximum and that the impairment of GSIS by linoleic acid is caused by mitochondrial uncoupling. These findings may be relevant to the pathogenesis of type 2 diabetes. 相似文献
7.
Fluorescence transients were measured in lyophilized maize chloroplasts (suspended in Tris-maleate buffer (pH 6.6)) after extraction with heptane. (The fluorescence characteristics before extraction were qualitatively similar to those in the fresh chloroplasts.) The initial fluorescence level ( m) in the (dry) heptane-extracted sample remained the same as in the unextracted material, but the variable fluorescence (Δ m) was drastically diminished. A portion of variable fluorescence, however, could be restored by adding Na 2S 2O 4. If the heptane extraction was made in the presence of water (wet), the m level was almost as high as (or higher than) the final level ( M) of the unextracted sample, and Δ m was reduced. The “jet” of O 2 (that measures the pool size of the intersystem intermediate A) and the “microjet” (that measures the pool size of the reaction center complex E), present in the unextracted samples, were absent in both types of extracted samples. Some of the above data may be interpreted in a hypothesis in which two quenchers (Q 1 and Q 2) control the fluorescence (O → P) of chloroplasts — the reduction of Q 1 being responsible for the rapid and that of Q 2 for the slow fluorescence rise. 相似文献
8.
Accurate and precise determination of phospholipid composition by 31P NMR spectroscopy requires correct assignments and adequate spectral resolution. Because temperature and pH may affect chemical shifts ( δ), our first aim was to establish the temperature coefficient (Δ δ/Δ T) of common phospholipid classes when using sodium cholate as detergent. This parameter can then be used to aid in resonance assignments. The second goal was to investigate the pH dependence of δ so that, in addition to temperature, pH control can be used to minimize spectral overlap. For phosphatidylcholine, sphingomyelin, dihydrosphingomyelin and phosphatidylglycerol, δ values were invariant with pH and temperature. Whereas the Δ δ/Δ T for phosphatidylinositol was 4 × 10 −3 ppm/°C, regardless of pH, these coefficients were highly pH-dependent for phosphatidic acid, phosphatidylethanolamine and phosphatidylserine, exhibiting maximal variations with the deprotonation of the headgroup, particularly for phosphatidic acid. These trends indicate the importance of H-bonding on δ and Δ δ/Δ T for phospholipid resonances. 相似文献
9.
Yeast cytochrome c peroxidase (CCP) efficiently catalyzes the reduction of H 2O 2 to H 2O by ferrocytochrome c in vitro. The physiological function of CCP, a heme peroxidase that is targeted to the mitochondrial intermembrane space of Saccharomyces cerevisiae, is not known. CCP1-null-mutant cells in the W303-1B genetic background ( ccp1Δ) grew as well as wild-type cells with glucose, ethanol, glycerol or lactate as carbon sources but with a shorter initial doubling time. Monitoring growth over 10 days demonstrated that CCP1 does not enhance mitochondrial function in unstressed cells. No role for CCP1 was apparent in cells exposed to heat stress under aerobic or anaerobic conditions. However, the detoxification function of CCP protected respiring mitochondria when cells were challenged with H 2O 2. Transformation of ccp1Δ with ccp1W191F, which encodes the CCP W191F mutant enzyme lacking CCP activity, significantly increased the sensitivity to H 2O 2 of exponential-phase fermenting cells. In contrast, stationary-phase (7-day) ccp1Δ- ccp1W191F exhibited wild-type tolerance to H 2O 2, which exceeded that of ccp1Δ. Challenge with H 2O 2 caused increased CCP, superoxide dismutase and catalase antioxidant enzyme activities (but not glutathione reductase activity) in exponentially growing cells and decreased antioxidant activities in stationary-phase cells. Although unstressed stationary-phase ccp1Δ exhibited the highest catalase and glutathione reductase activities, a greater loss of these antioxidant activities was observed on H 2O 2 exposure in ccp1Δ than in ccp1Δ- ccp1W191F and wild-type cells. The phenotypic differences reported here between the ccp1Δ and ccp1Δ- ccp1W191F strains lacking CCP activity provide strong evidence that CCP has separate antioxidant and signaling functions in yeast. 相似文献
10.
为了探明典型荒漠灌木优势物种黑沙蒿(俗名油蒿, Artemisia ordosica)光合过程能量中分配对环境波动的相对变化及其长期调节机制, 该研究于2018年4-10月在宁夏盐池毛乌素沙地, 同时使用MONITORING-PAM多通道荧光监测仪和LI-6400XT便携式光合测量仪对黑沙蒿叶片的最小荧光产量( Fo)、最大荧光产量( Fm)、稳态荧光产量( Fs)、光下最大荧光产量( Fm′)、净光合速率( Pn)、暗呼吸速率( Rd)、蒸腾速率( E)和叶片气孔导度( gs)进行现场测定, 在实验室内计算比叶面积( SLA)、单位面积氮含量( Narea)、叶绿素含量( CChl)和叶绿素a/b (Chl a/b), 分析黑沙蒿光合过程能量分配中固碳耗能占比( ΦA)、光呼吸耗能占比( ΦPR)、调节性热耗散耗能占比( ΦNPQ)和非调节性热耗散耗能占比( ΦNO)与环境参数和叶性状参数之间的关系以及能量分配各组分之间的相对变化。结果表明, 光化学反应组分( ΦA、 ΦPR)和热耗散组分( ΦNPQ、 ΦNO)之间呈负相关竞争关系, 两组分内部呈正相关协同关系, E和 ΦA、 ΦPR正相关, 和 ΦNPQ、 ΦNO负相关。在低土壤含水量( SWC)和高饱和水汽压差( VPD)环境条件下, 黑沙蒿 ΦA、 ΦPR和 SLA显著降低, ΦNPQ和 ΦNO显著增加。研究认为, 在长期干旱或高蒸散条件下, 黑沙蒿通过降低 SLA等途径避免水分的过度流失, 同时将部分过剩光能由光呼吸代谢途径转移到热耗散组分进行耗散。波动环境下黑沙蒿形态性状的变异和光合过程能量分配的长期调节机制, 反映了其利用形态与生理的协同可塑性对逆境的适应。 相似文献
11.
This paper reviews the influence of DNA repair on spontaneous and mutagen-induced mutation spectra at the base-substitution ( hisG46) and -1 frameshift ( hisD3052) alleles present in strains of the Salmonella (Ames) mutagenicity assay. At the frameshift allele (mostly a CGCGCGCG target), ΔuvrB influences the frequency of spontaneous hotspot mutations (−CG), duplications, and deletions, and it also shifts the sites of deletions and duplications. Cells with pKM101+ ΔuvrB spontaneously produce complex frameshifts (frameshifts with an adjacent base substitution). The spontaneous frequency of 1-base insertions or concerted (templated) mutations is unaffected by DNA repair, and neither mutation is inducible by mutagens. Glu-P-1, 1-nitropyrene (1NP), and 2-acetylaminofluorene (2AAF) induce only hotspot mutations and are unaffected by pKM101, whereas benzo( a)pyrene and 4-aminobiphenyl induce only hotspot in pKM101 −, and hotspot plus complex in pKM101 +. At the base-substitution allele (mostly a CC/GG target), the ΔuvrB allele increases spontaneous transitions in the absence of pKM101 and increases transversions in its presence. The frequency of suppressor mutations is decreased 4× by ΔuvrB, but increased 7.5× by pKM101. Both repair factors cause a shift in the proportion of mutations to the second position of the CC/GG target. With UV light and γ-rays, the ΔuvrB allele increases the proportion of transitions relative to transversions. pKM101 is required for mutagenesis by Glu-P-1 and 4-AB, and the types and positions of the substitutions are not altered by the addition of the ΔuvrB allele. Changes in DNA repair appear to cause more changes in spontaneous than in mutagen-induced mutation spectra at both alleles. There is a high correlation ( r2=0.8) between a mutagen's ability to induce complex frameshifts and its relative base-substitution/frameshift mutagenic potency. A mutagen induces the same primary class of base substitution in TA100 ( ΔuvrB, pKM101) as it does in Escherichia coli, mammalian cells, or rodents as well as in the p53 gene of human tumors associated with exposure to that mutagen. Thus, a mutagen induces the same primary class of base substitution in most organisms, reflecting the conserved nature of DNA replication and repair processes. 相似文献
12.
The thermal and photochemical reactions of CpRe(PPh 3) 2H 4 and CpRe(PPh 3)H 4 (Cp = η5-C 5H 5) with PMe 3, P( p-tolyl) 3, PMe 2Ph, DMPE, DPPE, DPPM, CO, 2,6-xylylisocyanide and ethylene have been examined. While CpRe(PPh 3) 2H 2 is thermally inert, it will undergo photochemical substitution of one or two PPh 3 ligands. With ethylene, substitution is followed by insertion of the olefin into the C-H bond of benzene, giving ethylbenzene. CpRe(PPh 3)H 4 undergoes thermal loss of PPh 3, which leads to substituted products of the type CpRe(L) H 4. Photochemically, reductive elimination of dihydrogen occurs preferentially. The complex trans-CpRe(DMPE)H 2 was structurally characterized, crystallizing in the monoclinic space group P2 1/ n (No. 14) with a = 6.249(6), b = 16.671(8), c = 13.867(7) Å, β = 92.11(6)°, V = 1443.7(2.9) Å and Z = 4. The complex trans-CpRe(PMe 2Ph) 2H 2 was structurally characterized, crystallizing in the monoclinic space group P2 1/ n (No. 14) with a = 7.467(3), b = 23.874(14), c = 11.798(6) Å, β = 100.16(4)°, V = 2070.2(3.4) Å 3 and Z = 4. 相似文献
13.
An amperometric enzyme sensor for rapid and simultaneous detection of the lignin-degrading peroxidase activities secreted by Phanerochaete chrysosporium was developed, using H 2O 2, hydroquinone and veratryl alcohol as substrates. In the amperometric measurement, samples of culture filtrate with different lignin-degrading peroxidase activities measured by spectrophotometry were placed into electrochemical cells. The slope of the current increase ( Δcurrent/ Δtime) upon the addition of H 2O 2 into the culture filtrate solution containing hydroquinone was used as the index for total activity of lignin peroxidase and manganese peroxidase. Then a specific detection of lignin peroxidase was achieved by the addition of veratryl alcohol, which led to current decrease due to the redox competition between veratryl alcohol and hydroquinone. A good linear correlation was found between the electrochemical response and lignin peroxidase activity, manganese peroxidase activity in the range of 8.14–29.79 U l −1 and 0.085–1.37 U l −1, respectively. A regression model was established describing the relationship. The amperometric sensor described here is more rapid, sensitive and precise than conventional spectrophotometric assays, free from interference of turbidity and UV–vis-light-absorbing substances. In this paper, it was also applied in the detection of lignin-degrading peroxidases in compost bioremediation using P. chrysosporium, showing considerable advantages. 相似文献
14.
植物水的稳定同位素分馏过程是水在土壤-植物-大气连续体中循环的重要环节。以往研究由于叶片水 18O同位素比值( δ18O l,b)和氘(D)同位素比值( δD l,b)(合称 δl,b)实测数量少只能作为模型验证数据, 导致 δl,b富集机制研究多集中于模型研究, 缺乏基于野外试验条件的 δl,b富集的控制机制研究。叶片水 δD l,b和 δ18O l,b的富集程度( ΔD l,b和 Δ18O l,b, 合称 Δl,b)通常表示为 δl,b与茎秆水D同位素比值( δD x)和 18O同位素比值( δ18O x) (合称 δx)之差, 即 Δl,b = δl,b - δx。该研究以黑河中游沙漠绿洲春玉米( Zea mays)生态系统为研究对象, 重点采集和分析了季节和日尺度 δl,b和 δx数据, 配套开展了大气水汽 δ18O和 δD (合称 δv)等辅助变量的原位连续观测, 探讨了季节和日尺度上的 δl,b富集特征及其影响因素。结果表明: 叶片水 δl,b和 Δl,b的季节变化趋势不明显, 而受蒸腾作用影响表现出白天富集夜间贫化的单峰日变化特征。对于D来说, 无论季节尺度上还是日尺度上, 大气水汽 δv和相对湿度是 δD l,b和 ΔD l,b的主要环境控制因素; 而对于 18O来说, 无论季节尺度上还是日尺度上, 相对湿度是 δ18O l,b和 Δ18O l,b的主要环境控制因素。由于D和 18O在热力学平衡分馏上有约8倍差异, 直接分析叶片水 ΔD l,b和 Δ18O l,b与影响因素的差异性, 有助于理解叶片水 δD和 δ18O富集过程以及对模型发展有一定的指导意义。 相似文献
15.
Four ergosterol derivatives (1–4) have been isolated for the first time from the fruiting bodies of a basidiomycete fungus, Lactarius hatsudake, through activity-guided fractionation. Their structures were determined, using spectroscopic analysis, as: (22 E,24 R)-ergosta-5,7,22-dien-3 β-ol (ergosterol, 1); 5 ,8 -epidioxy-(22 E,24 R)-ergosta-6,22-dien-3 β-ol (ergosterol peroxide, 2); 5 ,8 -epidioxy-(24 S)-ergosta-6-en-3 β-ol (3); and (22 E,24 R)-ergosta-7,22-dien-3 β,5 ,6 β-triol (cerevisterol, 4). Compounds 2 and 3 showed selective inhibitory activity against Crotalus adamenteus venom phospholipase A 2 (PLA 2) enzyme, but not against Apis mellifcra bee venom PLA 2. The antiphospholipase A 2 activity of compounds 2 and 3 are reported here for the first time. 相似文献
16.
Effects of cyclopentenone prostaglandins, Δ 12-prostaglandin (PG) J 2 and PGA 2 on the expression of N- myc in relation to the effects on cell cycle progression were investigated using human neuroblastoma cell line GOTO. Both PGs suppressed M- myc expression within several hours prior to inducing G 1 arrest. The N- myc suppression with Δ 12-PGJ 2 was continued but with PGA 2 it was gradually released, followed by the release of G 1 arrest. These results suggest that Δ 12-PGJ 2 and PGA 2 inhibit cell cycle progression in strong association with N- myc suppression and Δ 12-PGJ 2 is more potent and has a longer effect than PGA 2. 相似文献
17.
蒸散发广义互补原理是实测数据稀少条件下估算蒸散发的重要方法, 其中准确估算参数 αe是应用该方法的关键。该研究利用中国不同气候和生态类型的8个通量站数据, 首先基于实测数据校准得到 αe年值及月值, 探究 αe的时空变异性并对比使用不同时间尺度的 αe对广义互补原理模型计算精度的影响。考虑到实际情况下蒸散发实测数据缺乏而无法校准得到 αe, 进一步探究两个基于干旱系数( AI)的 αe年值统计模型(下称Liu法和Brutsaert法)在站点尺度的适用性, 明确 αe是否可以利用 AI确定, 最后探讨各计算方法的误差来源。主要结论如下: 1)季节变化影响 αe, 不同通量站 αe月值变化规律有所差异; 在空间变化上, 湿润站点 αe年值总体大于干旱站点。Liu法和Brutsaert法计算的 αe接近年校准值。2)在应用广义互补原理模型时, 使用校准 αe年值能取得较好的模拟精度, 使用各月份 αe时精度进一步提升。两种基于 AI的免校准方法取得较好的模拟效果, 当缺少实测数据而无法校准 αe时, 基于 AI计算 αe具有较大的潜力。3)使用校准 αe年值时广义互补原理模型能模拟出蒸散发的年内变化趋势, 但在部分月份估算值出现偏差。Liu法和Brutsaert法计算的蒸散发在干旱站点的夏季月份呈现低估现象, 原因可能在于高估了降雨集中的夏季月份的 AI。结果也进一步验证了广义互补原理在估算广泛不同的自然环境下的蒸散发的潜力。 相似文献
18.
Aims Ecosystem light use efficiency ( LUE) reflects the ability of CO 2 uptake and light utilization via photosynthesis, which is a key parameter in ecosystem models to evaluate ecosystem productivity. The objectives of this study were to: (1) compare the differences of LUE derived from different methods; (2) elucidate the seasonal dynamics of LUE and its regulatory factors; and (3) evaluate the maximum LUE ( LUEmax) and its variability based on eddy-covariance (EC) flux. Methods Using the flux data from an EC tower during 2003-2005 at a broad-leaved Korean pine ( Pinus koraiensis) mixed forest, Changbai Mountain, two types of LUE indicators were generated from: 1) the apparent quantum yield ( ε) estimated with rectangular hyperbolic curve, and 2) the ecological light use efficiency ( LUEeco) calculated as the ratio between gross ecosystem productivity ( GEP) and photosynthetically-active radiation ( Q). Important findings The seasonal variation of ε and LUEeco appeared a unimodal pattern within a year, with the variations significantly dominated by soil surface temperature and Normalized Difference Vegetation Index ( NDVI). A positive correlation between GEP and LUE was found for both ε and LUEeco, with the effect of Q on LUE relatively weak. The increase in diffusion radiation appeared favorable for enhanced LUE. Generally, there was a significant positive relationship between ε and LUEeco, while ε was higher than LUEeco, especially during the mid-season. The annual maximum value of ε and LUEeco was (0.087 ± 0.003) and (0.040 ± 0.002) μmol CO 2·μmol photon -1 over the three years, respectively. The interannual variability of LUEmax for ε and LUEeco was 4.17% and 4.25%, respectively, with a maximum difference of >8%, likely resulted from considerable uncertainty in model simulations. Our results indicated that the inversion and optimization of maximum LUE should be taken seriously in the application of LUE models. 相似文献
19.
The glycolytic reaction of grapefruit PPi-dependent phosphofructokinase (PFP) depends on the presence of Fru-2,6-P 2 ( Ka=6.7 nM). This molecule was further demonstrated in grapefruit juice sac cells. Citrate, -ketoglutarate and isocitrate competitively inhibited the binding of Fru-2,6-P 2 to PFP. The affinity for Fru-6-P ( Km=159 μM) and PPi ( Km=33 μM) were not affected by the addition of these molecules. In the gluconeogenic reaction, the presence of Fru-2,6-P 2 did not affect the Km of Fru-1,6-P 2 (61 μM) in contrast to orange fruit PFP. These results led to the building of a computer model of PFP, based on the known structure of Bacillus stearothermophilus ATP-dependent phosphofructokinase (ATP-PFK). The results show that catalysis of Fru-6-P in the chain is most unlikely, due to amino-acid substitutions and that Fru-2,6-P 2 can bind between the and β subunits. 相似文献
20.
生态系统光能利用率( LUE)反映了植被通过光合作用利用光能吸收和固定大气中CO 2的能力, 是表征生态系统生产力的重要指标。选取长白山温带阔叶红松( Pinus koraiensis)林生态系统为研究对象, 利用涡度相关通量观测数据, 采用直角双曲线方程获取了生态系统光合作用的表观量子效率( ε); 基于总生态系统初级生产力( GEP)与下垫面入射光合有效辐射( Q)的比值得到生态光能利用率( LUEeco)。研究表明: 在季节尺度上, ε与 LUEeco均表现出显著的单峰变化特征, 并主要受到土壤温度和归一化植被指数( NDVI)的调控, 同时, ε和 LUEeco都受到 GEP的显著影响, 而与 Q的相关性较弱或无显著相关关系, 但散射辐射的增加在一定程度上有助于提高生态系统的 LUE。 ε与 LUEeco存在显著的线性正相关关系, 但 ε明显高于 LUEeco。2003-2005年, ε与 LUEeco每年最大值的平均值分别为(0.087 ± 0.003)和(0.040 ± 0.002) μmol CO 2·μmol photon -1, 年际间变异度分别为4.17%和4.25%, 而不同年份之间最大差异均达到8%或8%以上, 从而对模型模拟结果产生明显影响。因此, 在基于光能利用率模型的模拟研究中, 最大 LUE的年际变异需要在参数反演和优化中给予重要考虑。 相似文献
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