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1.
低浓度SO2对云杉幼苗中碳水化合物代谢的影响研究 总被引:3,自引:0,他引:3
研究了低浓度SO2对云杉幼苗的光合作用速率及碳水化合物代谢的生理生化过程的影响,测定了CO2摄取速率、幼苗蔗糖含量、蔗糖磷酸合成酶、蔗糖合成酶和转化酶活性及ATP/ADP值.结果表明,低浓度的SO2(200μg·m(-3))能瞬时刺激幼苗对CO2的吸收.与对照组相比,幼苗中的蔗糖含量及蔗糖磷酸酶活性明显下降,ATP/ADP处于低水平.因此,在受到SO2污染形成可见伤害前,幼苗的生理生化过程可能已受到干扰. 相似文献
2.
在有PCR和PCO环活性抑制剂甘油醛和光合磷酸化解偶联剂NH4CL存在下,比较了生长于 3种 光环境的乔木黧蒴和灌木九节幼苗阳生和阴生叶片叶绿体的O2和NO2光还原速率。全自然光下两种 植物阳生叶片的叶绿体O2的光还原速率最高,占总光合电子传递活性的66%-68%,NO2光还原速率 也有类似趋势占总电子传递的11%-15%左右。36%和16%自然光下阴生叶片O2和NO2光还原 速率及O2光还原电子传递的比例显著降低,但NO2光还原电子传递的比例不受影响。与NO2光还原 相关的叶片NiR和NR活性及NiR/NR活性比也因叶片接受光强度大小而异,随光强减弱,黧蒴的 NiR活性降低,九节的NR活性增高,但黧蒴的NR活性和九节的NiR活性变化未达差异显著性。 相似文献
3.
两个品种的大豆叶圆片经10-4mol/L和10-3mol/L的H2O2处理12h后,超氧物歧化酶(SOD)、过氧化氢酶(CAT)与谷胱甘肽还原酶(GR)活性明显增加,但10-2mol/L的H2O2处理却使这些酶活性降低。抗旱性较强的大豆品种小粒豆1号较抗旱性较弱的鲁豆4号能维持较高的叶绿素含量和较高的SOD、CAT及GR活性,对H2O2的抗性较强。50μmol/L的亚胺环已酮(CHM)能消除H2O2对SOD、CAT与GR活性的刺激作用,而同样浓度的放线菌素D(AMD)则不能。 相似文献
4.
酵母PHO2蛋白的磷酸化研究 总被引:5,自引:5,他引:0
本文报道了PHO2蛋白能被一种未知的蛋白激酶磷酸化。PHO2蛋白的第230-233位氨基酸残基因组成一个可能p34^cdc3/CDC28相关的蛋白激酶识别的一致序列,用点突变的方法将Ser-230变成Ala可导致PHO2蛋白激活PHO5表达能力的完全丧失。 相似文献
5.
6.
应用实时生物分子相互作用分析技术(BIA)分析了酵母PHO4和PHO2蛋白的相互作用。将PHO4蛋白通过氨基耦联在感应片上。进样5μmol/L重组的谷胱甘肽转移酶融合的PHO2蛋白(GST-PHO2)及其两种突变体融合蛋白。结果表明PHO2的230位丝氨酸变为天冬氨酸的突变体(GST-2SD)与PHO4有强的表面等离子体激元共振信号,而生型PHO2和230位丝氨酸变为丙氨酸的突变体(GST-2SA 相似文献
7.
经磷脂酶A2 去脂的肌质网Ca2 + - ATPase 重组于不同比例的二油酰磷脂酰胆碱(Dioleoylphophatidylcholine,DOPC) 和二油酰磷脂酰乙醇胺(Dioleoylphophatidylethanolamine,DOPE) 形成脂酶体,研究了不同磷脂环境中Ca2 + - ATPase 的ATP 水解和Ca2 + 转运活力。结果表明,DOPC 和DOPE 分别有利于ATP 水解和Ca2 + 的转运,DOPE 可以增强Ca2 + - ATPase 的ATP水解和Ca2 + 转运之间的偶联效率。利用内源荧光、荧光淬灭及Forster 能量转移原理测定Ca2 + -ATPase 相应的构象变化, 发现随着DOPE/ DOPC 比例的改变使Ca2 + - ATPase 构象发生相应的变化。 相似文献
8.
UV—B辐射对小麦叶片H2O2代谢的影响 总被引:12,自引:1,他引:11
研究了温室种植的小麦在0(CK)、8.82kJ/m^2(T1)和12.6kJ/m^2(T2)三种剂量的紫外线B(UV-B)辐射下H2O2含量的变化及其机理。UV-B辐射下H2O2、还原型抗坏血酸(AsA)和还原型谷胱甘肽(GSH)含量增加,抗坏血酸过氧化物酶(APx)和谷胱甘肽不原酶(GR)活性升高,脂肪酸不饱和度指数(IUFA)降低。SDS-PAGE谱图没有质上的差异,但凝胶着色深浅有变化。分析 相似文献
9.
CO_2倍增对紫花苜蓿碳、氮同化与分配的影响 总被引:6,自引:0,他引:6
本文简要报道CO2倍增下紫花苜蓿碳素积累、氮素的吸收与生物固氮及其产物在地上、地下部分配的特性1 材料和方法在北京香山中国科学院植物研究所植物园试验区,建立了两个高2.8m、直径2.2m的钢管支撑的圆柱状开顶式薄膜培养室,由底部向室内连续通气,保证培养室内每分钟换气3次。对照室通入正常空气(350×10-6,1×CO2),处理室通入CO2加倍的空气(700×10-6,2×CO2)。室内CO2浓度经红外CO2分析仪(QGD-07型,北京分析仪器厂产品)测定,24h内均可保持在350×10-6及70… 相似文献
10.
邻二氮菲-Fe~(2+)氧化法检测H_2O_2/Fe~(2+)产生的羟自由基 总被引:82,自引:0,他引:82
报告检测H2O2/Fe2+所产生羟自由基的新方法.羟自由基氧化反应后,邻二氮菲-Fe2+的A536明显下降,且△A536与邻二氮菲,FeSO4及H2O2呈量效关系,随反应时间延长,△A536依幂函数规律上升.此法试验结果表明,甘露醇,抗坏血酸及硫肥清除羟自由基作用呈明显的量效关系. 相似文献
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12.
The determination of the CO2/O2 specificity factor (Ω) is very important to investigate the Rubisco carbon assimilation efficiency. In this paper, it is
proved that previous formulae can introduce notable errors into calculating the CO2/O2 specificity factor (Ω) because CO2 and O2 are both the substrates and the mutually competitive inhibitors for Rubisco. A simple integrated equation is proposed to
calculate the CO2/O2 specificity factor (Ω). On the other hand, previous multi-step procedures, including the manipulation of radioisotope (14C and/or 3H) and the chromatographic separation of the products, are inconvenient and may cause much random error. An improved assay
procedure is presented therefore, which includes the spectrophotometric measurement of 3-phosphoglycerate-dependent NADH oxidation
with a coupled enzyme system.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
13.
Photosynthesis-deficient mutant 45-3B of the green alga Chlamydomonas reinhardtii contains a chloroplast mutation that causes valine-331 to be replaced by alanine within the large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase. This amino acid substitution occurs in loop 6 of the alpha/beta-barrel active site, three residues distant from catalytic lysine-334. The mutation reduces the specific activity of the enzyme and also reduces its CO2/O2 specificity factor by 42%, but the amount of holoenzyme is unaffected. In a previous study, an intragenic-suppressor mutation, named S40-9D, was selected that causes threonine-342 to be replaced by isoleucine, thereby increasing the CO2/O2 specificity of the mutant enzyme by 36%. To determine which other residues might be able to complement the original mutation, nine additional genetically independent revertants have now been analyzed. Another intragenic suppressor, represented by mutation S61-2J, causes glycine-344 to be replaced by serine. This change increases the CO2/O2 specificity of the mutant enzyme by 25%. Of the revertants recovered and analyzed, the mutant enzyme was improved only due to true reversion or by intragenic suppression mediated by substitutions at residues 342 or 344. Changes in the physical properties of the two pairs of complementing substitutions indicate that steric effects within loop 6 are responsible for the observed changes in the CO2/O2 specificity of the enzyme. 相似文献
14.
Chloroplast intragenic suppression enhances the low CO2/O2 specificity of mutant ribulose-bisphosphate carboxylase/oxygenase 总被引:4,自引:0,他引:4
The competition between CO2 and O2 at the active site of ribulose-1,5-bisphosphate carboxylase/oxygenase limits net CO2 fixation in photosynthesis. In the green alga Chlamydomonas reinhardtii, a mutation in the chloroplast large-subunit gene reduces the CO2/O2 specificity of the enzyme by 37% and causes valine-331 to be replaced by alanine. Revertant selection identified an intragenic suppressor mutation that increases the CO2/O2 specificity of the mutant enzyme by 33%. This second-site mutation causes threonine-342 to be replaced by isoleucine. The complementing amino acid substitutions flank a catalytically essential lysyl residue at position 334. It thus appears that a number of amino acid residues can influence the CO2/O2 specificity of this bifunctional enzyme. The well defined chloroplast genetics of C. reinhardtii allows the interactions of these residues to be investigated. 相似文献
15.
黄淮海平原河北省范围内农田土壤二氧化碳和氧化亚氮排放量的估算 总被引:9,自引:1,他引:9
以黄淮海平原河北省范围内的农田土壤为研究对象,通过与田间实际观测数据进行比较发现,DNDC模型能够较好地反映农田土壤温室气体CO2和N2O的排放通量,可以用来模拟估算农田土壤CO2和N2O的排放通量.根据模型估算,2003年河北省111个县市农业土壤CO2排放量约3.758×106tC,各县市总的N2O排放量40.345×106kgN.全省释放的CO2和N2O中有40%左右来自冬小麦/夏玉米地.因此,减少该地区农业土壤CO2和N2O排放量的措施,应集中用于排放量高的县市和这些地区的冬小麦/夏玉米地,进行大范围的普遍减排可能收效甚微,并且没有必要. 相似文献
16.
Frank J. Koppenhagen Gert Storm Willy J. M. Underberg 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1998,716(1-2)
This paper describes the development of an isocratic reversed-phase high-performance liquid chromatographic method for the routine analysis of recombinant interleukin-2 (rIL-2) in liposome samples. The chromatographic system employed a C4 column maintained at 30°C eluted with 52.5% (w/w) acetonitrile in water, containing 100 mM NaClO4 and 10 mM HClO4. To remove phospholipid interference the chromatographic method was combined with a lipid-extraction procedure. No significant loss of rIL-2 was noted upon inclusion of this extraction step. The protein eluted from the column with a capacity factor (k′) of 5.8. The method was validated for robustness, linearity, precision and reproducibility. It was shown that the method was linear over a sample concentration range of 1–100 μg/ml. Upon assessment of the intra-day and inter-day precision, the relative standard deviations (RSD) were within the range of the methodical error (approximately 5%), except at the lower concentration of 10 μg/ml, where the intra-day RSD was relatively high (17.8%). The recovery of rIL-2 upon liposome preparation and subsequent analysis of the samples was in the range 94±9%. The results indicate that the method is suitable for routine quantitation of rIL-2 in liposomal samples. 相似文献
17.
Oxygen and ribulose-1,5-bisphosphate dependent, H(2)O(2) production was observed with several wild type Rubisco enzymes using a sensitive assay. H(2)O(2) and d-glycero-2,3-pentodiulose-1,5-bisphosphate, a known and potent inhibitor of Rubisco activity, are predicted products arising from elimination of H(2)O(2) from a peroxyketone intermediate, specific to oxygenase activity. Parallel assays using varying CO(2) and O(2) concentrations revealed that the partitioning to H(2)O(2) during O(2) consumption by spinach Rubisco was constant at 1/260-1/270. High temperature (38 degrees C), which reduces Rubisco specificity for CO(2) versus O(2), increased the rates of H(2)O(2) production and O(2) consumption, resulting in a small increase in partitioning to H(2)O(2) (1/210). Two Rubiscos with lower specificity than spinach exhibited greater partitioning to H(2)O(2) during catalysis: Chlamydomonas reinhardtii (1/200); and Rhodospirillum rubrum (1/150). 相似文献
18.
In order to see the effect of CO(2) inhibition resulting from the use of pure oxygen, we carried out a comparative fed-batch culture study of polyhydroxybutyric acid (PHB) production by Ralstonia eutropha using air and pure oxygen in 5-L, 30-L, and 300-L fermentors. The final PHB concentrations obtained with pure O(2) were 138.7 g/L in the 5-L fermentor and 131.3 g/L in the 30-L fermentor, which increased 2.9 and 6.2 times, respectively, as compared to those obtained with air. In the 300-L fermentor, the fed-batch culture with air yielded only 8.4 g/L PHB. However, the maximal CO(2) concentrations in the 5-L fermentor increased significantly from 4.1% (air) to 15.0% (pure O(2)), while it was only 1.6% in the 30-L fermentor with air, but reached 14.2% in the case of pure O(2). We used two different experimental methods for evaluating CO(2) inhibition: CO(2) pulse injection and autogenous CO(2) methods. A 10 or 22% (v/v) CO(2) pulse with a duration of 3 or 6 h was introduced in a pure-oxygen culture of R. eutropha to investigate how CO(2) affects the synthesis of biomass and PHB. CO(2) inhibited the cell growth and PHB synthesis significantly. The inhibitory effect became stronger with the increase of the CO(2) concentration and pulse duration. The new proposed autogenous CO(2) method makes it possible to place microbial cells under different CO(2) level environments by varying the gas flow rate. Introduction of O(2) gas at a low flow rate of 0.42 vvm resulted in an increase of CO(2) concentration to 30.2% in the exit gas. The final PHB of 97.2 g/L was obtained, which corresponded to 70% of the PHB production at 1.0 vvm O(2) flow rate. This new method measures the inhibitory effect of CO(2) produced autogenously by cells through the entire fermentation process and can avoid the overestimation of CO(2) inhibition without introducing artificial CO(2) into the fermentor. 相似文献
19.
氧化铝层析从云南红豆杉植物中转化提取紫杉醇 总被引:6,自引:0,他引:6
采用氧化铝层析从云南红豆杉植物汉膏中转化生成和分离提纯了紫杉醇。考察了氧化铝的类型、流动相中水和甲醇的添中、反应时间以及洗脱剂组成等层析操作条件对紫杉醇回收和分离的影响。研究表明,采用碱性氧化铝柱层析分离和回收紫杉醇效果显著,通过对紫杉醇转化和分离条件的优化,经一步氧化铝柱层析,可以使紫杉醇的含量从小于1.0%提高到大于27%,紫杉醇的回收大于170%。 相似文献
20.
华南丘陵区冬闲稻田二氧化碳、甲烷和氧化亚氮的排放特征 总被引:11,自引:0,他引:11
采用静态箱 气相色谱法对收获后冬闲稻田CO2、CH4和N2O排放进行了田间原位测定,探讨了越冬稻田3种温室气体的排放规律.结果表明,残茬稻田和裸田的CO2的排放峰值分别出现在18:00和16:00左右.日间CH4排放为净值,夜间表现为弱吸收.残茬稻田和裸田N2O夜间排放分别为日间平均的1.79和1.58倍.残茬稻田的昼夜CO2平均排放通量显著高于裸田(P<0.05).在测定期间,残茬稻田CO2排放随温度升高而增高.相关分析表明,CO2排放与土温、地表温度和气温均呈显著相关,表明温度是影响收获后稻田CO2排放的主要因素.在11月10日至翌年1月18日测定期间,残茬稻田的CO2和CH4平均排放通量分别为(180.69±21.21) mg·m-2·h-1和(-0.04±0.01) mg·m-2·h-1,CO2排放通量较裸田高13.06%,CH4吸收增高50%.残茬稻田的N2O排放通量为(21.26±19.31) μg·m-2·h-1,较裸田低60.75%.由此说明华南丘陵区冬闲稻田是大气CO2和N2O的源,CH4的汇. 相似文献