草甘膦对叶绿体能量转换的影响

除草剂草甘膦抑制植物叶绿体光合磷酸化活力,促进希尔反应活力,表现出明显的解偶联效应。它对叶绿体膜上腺三磷酶(ATPase)活力也起抑制效应,说明ATP合成被抑制不是由ATP酶活力变化所引起。这种解偶联现象主要是因光下质子转移受到抑制,在较低浓度的草甘膦影响下,先抑制质醌转移的质子进入膜内腔,浓度增加到20 mM,对水释放质子也有抑制。所以草甘膦对叶绿体能量转换的影响主要反映在质子转移被抑制,引起磷酸化活力受抑制。     

镉离子对菠菜叶绿体色素蛋白质复合物及激发能分配的影响

Cd~(2+)使叶绿体低温(77K)荧光发射光谱中 F686/F736及 F696/F736和激发光谱中F480/F436比值降低,说明 Cd~(2+)不利于激发能向 PSⅡ传递。SDS-PAGE 分析表明,Cd(2+)处理后叶绿体类囊体膜中光系统Ⅱ捕光叶绿素蛋白质复合物 LHCⅡ的部分寡聚体解聚成单体,且 LHCⅡ的总量也减少了。分析表明 Cd~(2+)使属于 LHCⅡ的多肽减少。已知LHCⅡ在光能吸收、传递以及激发能在两个光系统间的分配和调节方面起着重要作用,Cd~(2+)引起部分 LHCⅡ解聚和总量减少,必然导致由 LHCⅡ捕获和向光系统Ⅱ中心传递的能量减少。     

氯丁唑和咪唑对叶绿体能量转换反应的效应

比较了氯丁唑和咪唑对叶绿体能量转换各步骤反应的效应,氯丁唑抑制光合基础的和偶联的电子传递,氯化铵可部分解除偶联的电子传递的抑制;咪唑促进基础电子传递。两者均抑制光合磷酸化、9-氨基吖啶荧光猝灭和膜上腺三磷酶活性。氯丁唑抑制质子吸收,促进游离腺三磷酶活;咪唑促进质子吸收,也促进游离腺三磷酶的活性。由此提出,氯丁唑具有能量传递抑制剂的特征,咪唑似解联剂。     

采后菠菜叶片失水萎蔫对膜透性及膜脂过氧化作用的影响

本文分析了菠菜叶片失水萎蔫时叶绿素、相对含水量、膜透性及膜脂过氧化产物丙二醛的变化,结果表明:叶片萎蔫衰老时随着相对含水量的降低,叶绿素含量减少,膜透性和丙二醛含量增大;并且随萎蔫程度加深,膜透性与丙二醛含量也明显增加.这说明菠菜叶片失水萎蔫与膜结构完整性的破坏有密切的关系。     

草酸处理对热胁迫下辣椒叶片膜透性和钙分布的影响

研究了外源草酸对热胁迫下辣椒叶片中细胞膜相对透性,谷胱甘肽（GSH）和抗坏血酸（AsA)含量变化以及Ca^2 分布的影响。结果表明：热胁迫使叶肉细胞膜相对透性升高,草酸处理则减轻升高幅度;热胁迫使叶片中GSH和AsA含量下降;草酸处理则使二者在热胁迫下含量下降幅度较小,常温下辣椒叶肉细胞的焦锑酸钙沉淀颗粒主要分布于液泡,胞间隙和叶绿体中,热胁迫下液泡,细胞间隙中减少,但在细胞核和细胞质中出现;经过草酸处理的叶肉细胞,焦匀酸钙沉淀颗粒在胞间隙中明显增多。液泡中减少。     

转入甜椒热激蛋白基因CaHSP18提高番茄的耐冷性

利用农杆菌介导法将甜椒热激蛋白基因转化番茄,Northern和Western杂交表明CaHSP18在番茄植株中表达,获得转CaHSP18的番茄植株。Northern杂交显示,CaHSP18基因受低温诱导,表达量随低温处理时间的延长而增加,6h时表达量最高。低温胁迫导致野生型和转基因番茄植株的相对电导率升高,光爱统Ⅱ（PSⅡ）最大光化学效率（Fv/Fm）和放氧速率下降,但转基因番茄植物维持较低的膜透性,较高的Fv/Fm和放氧速率。这些显示,在番茄植株中CaHSP18表达后耐冷性有提高。     

Characterization of Energy-Transduction in Thermal Pretreated Chloroplast from Spinach

Characterization of energy-transduction on the chloroplast thylakoid membranes from spinach (Spinacia oleracea L.) after thermal pretreatment was investigated. The related reactions of energy-transduction in chloroplasts were seriously affected by thermal pretreatment. The results were obtained as following: (1) The rate of cyclic photophosphorylation declined when the pretreatment temperature increased in the range of 25 to 45 ℃. (2) The thermal pretreatment led to a decrease of the activity of thylakoid membrane-bounded ATPase. (3) Proton uptake of chloroplasts and the fluorescence quenching of 9-aminoacridine (9-AA) in thylakoid membrane decreased after the thermal pretreatment, but addition of dicyclohexylcarbodiimide (DCCD) could partially restore the fluorescence quenching of 9-AA. (4) Both the rates of fast phase in electrochroism absorption change at 515 nm and the millisecond delayed light emission (ms-DLE) of chloroplast showed a progressive decrease upon raising the temperature of pretreatment. (5) Immunbloting analysis showed that the thermal pretreatment caused the changes of protein content and the electrophoresis mobility of thylakoid membrane-bound ATPase and its α-subunit. (6) If the temperature of pretreatment were higher than 33 ℃, oxygen uptake of PSⅠ -mediated in the samples was rapidly inhibited, but addition of sinapine into the reaction medium could partially restore the ability of oxygen uptake in the samples. These results are briefly discussed in relation to the change of permeability of thylakoid membranes, the dissociation of coupling factor complex as well as accumulation of the radicals in the thylakoid membranes after thermal pretreatment.     

菠菜叶中存在两种谷氨酰胺合成酶同工酶

运用非变性聚丙稀酰胺凝胶电泳结合活性染色的方法,在菠菜(Spinacia oleracea L．)生长发育过程中,观察到叶片中至少存在2种谷氨酰胺合成酶(GS),其中一种GS的活性随发育进程而逐渐升高,而另一种GS的活性逐渐降低。在不同来源的成熟的菠菜叶片中同样观察到2种GS的存在。     

Interaction between Phycobilisomes from <Emphasis Type="Italic">Porphyridium cruentum</Emphasis> and Thylakoid Membranes from <Emphasis Type="Italic">Gymnodinium</Emphasis> sp. or Spinach

Thylakoid membranes were isolated from Gymnodinium sp. and spinach, whereas the phycobilisomes were isolated and purified from red alga Porphyridium cruentum. The absorption spectra of the purified phycobilisomes (PBS) showed three peaks at 548, 564, and 624 nm, respectively, and the ratio of the fluorescence intensity at the ₆₈₀ ^em to that at ₅₈₀ ^em was about 7.3. All these results demonstrated that the purified PBS remained intact. The thylakoid membranes were incubated with the purified phycobilisomes, and the thylakoid membranes, which harbored the phycobilisomes, were purified by sucrose density gradient centrifugation. Meantime, the conjugates of phycobilisome-thylakoid membranes were constructed using glutaraldehyde and further purified. Their characteristics were studied by measuring the absorption spectra and fluorescence emission spectra. The results showed that the phycobilisomes from Porphyridium cruentum can attach to the thylakoid membranes from Gymnodinium sp. and spinach without covalent cross-linking, but the excited energy transfer did not occur. The conjugate of phycobilisome-thylakoid membranes with covalent cross-linking exhibits the excited energy transfer between the phycobilisomes and the thylakoid membranes.__________From Fiziologiya Rastenii, Vol. 52, No. 3, 2005, pp. 331–337.Original English Text Copyright © 2005 by Zhu, Wang, Tseng.This article was submitted by the authors in English.     

菠菜和蚕豆叶绿体CF_1结构与功能的比较

比较了菠菜和蚕豆叶绿体的光合磷酸化活力以及由不同活化方法活化的叶绿体及可溶CF1的Mg2＋－ATPase和Ca2＋－ATPase的活力,观测到两种叶绿体ATPase的合成和水解ATP的功能有明显差异。从两种叶绿体CF1的SDS－PAGE图谱上可见蚕豆CF1的ε亚基分子量明显小于菠菜的,蚕豆CF1的α和β亚基间分子量的差别也比菠菜的小。     

The action of lipases on chloroplast membranes I. The release of plastocyanin from galactolipase-treated thylakoid membranes

Bean chloroplasts treated with galactolipase (lipolytic acyl hydrolase) isolated from bean leaves showed an inhibition of photosystem I activity as measured by methyl viologen-mediated oxygen uptake and NADP⁺ photoreduction. This inhibition was partially reversed by exogenous plastocyanin added to galactolipase-treated thylakoid membranes. Galactolipase released substantial amounts of endogenous plastocyanin (about 40%) from bean chloroplasts. The results are discussed with regard to the localization of plastocyanin in thylakoid membranes.Abbreviations chlf chlorophyll - DCMU 3-(2,4-dichlorophenyl)-1,1-dimethylurea - DGDG digalactosyldiacylglycerol - MGDG monogalactosyldiacylglycerol - MV methyl viologen - NADP⁺ nicotinamide dinucleotide phosphate - PC phosphatidylcholine - PG phosphatidylglycerol - PE phosphatidylethanolamine - PI phosphatidylinositol - SQDG sulphoquinovosyldiacylglycerol - SDS sodium dodecyl sulphate - TMPD N,N,N,N-tetramethyl-p-phenylenediamine - Tricine N-Tris-(hydroxymethyl)-methylglycine - Tris Tris-(hydroxymethyl)-aminomethane     

Mechanical freeze-thaw damage and frost hardening in leaves and isolated thylakoids from spinach. I. Mechanical freeze-thaw damage in an artificial stroma medium

Abstract Freeze-thaw damage to thylakoids in spinach leaves has been simulated in vitro, using a complex, defined artificial stroma medium. The resulting mechanical damage was quantified by measuring the loss of the marker protein plastocyanin from the thylakoid lumen, which is released as a result of membrane rupture. Loss of plastocyanin was already apparent at 0°C and became more severe at subzero temperatures. The time course of plastocyanin loss during freezing was biphasic: after an initial rapid loss, plastocyanin release was linearly dependent on incubation time. In short-term experiments a linear dependence on freezing temperature was observed. Solute diffusion into the thylakoids, leading to influx of water and eventually membrane rupture, has been observed in vitro as well as after freezing of leaves.     

Chlorophyll-protein complex composition and photochemical activity in developing chloroplasts from greening barley seedlings

The time course for the observation of intact chlorophyll-protein (CP) complexes during barley chloroplast development was measured by mild sodium dodecyl sulfate polyacrylamide gel electrophoresis. The procedure required extraction of thylakoid membranes with sodium bromide to remove extrinsic proteins. During the early stages of greening, the proteins extracted with sodium bromide included polypeptides from the cell nucleus that associate with developing thylakoid membranes during isolation and interfere with the separation of CP complexes by electrophoresis. Photosystem I CP complexes were observed before the photosystem II and light-harvesting CP complexes during the initial stages of barley chloroplast development. Photosystem I activity was observed before the photosystem I CP complex was detected whereas photosystem II activity coincided with the appearance of the CP complex associated with photosystem II. Throughout chloroplast development, the percentage of the total chlorophyll associated with photosystem I remained constant whereas the amount of chlorophyll associated with photosystem II and the light-harvesting complex increased. The CP composition of thylakoid membranes from the early stages of greening was difficult to quantitate because a large amount of chlorophyll was released from the CP complexes during detergent extraction. As chloroplast development proceeded, a decrease was observed in the amount of chlorophyll released from the CP complexes by detergent action. The decrease suggested that the CP complexes were stabilized during the later stages of development.Abbreviations Chl chlorophyll - CP chlorophyll-protein - CPI P700 chlorophyll-a protein complex of photosystem I - CPa electrophoretic band that contains the photosystem II reaction center complexes and a variable amount of the photosystem I light-harvesting complex - CP A/B the major light-harvesting complex associated with photosystem II - DCIP 2,6-dichlorophenolindophenol - DCMU 3-(3,4-dichlorophenyl)-1,1-dimethylurea - DPC diphenyl carbazide - MV methyl viologen - PAR photosynthetically active radiation - PSI photosystem I - PSII photosystem II - SDS sodium dodecyl sulfate - SDS-PAGE sodium dodecyl sulfate polyacrylamide gel electrophoresis - TEMED N,N,N,N-tetramethylethylenediamine - TMPD N,N,N,N-tetramethyl-p-phenylenediamine Cooperative investigations of the United States Department of Agriculture, Agricultural Research Service, and the North Carolina Agricultural Research Service, Raleigh, NC 27695-7601. Paper No. 9949 of the Journal Series of the North Carolina Agricultural Research Service, Raleight, NC 27695-7601.     

在大肠杆菌中具有启动功能的菠菜叶绿体DNA片段的克隆及序列分析

将经sau3A部分酶切过的菠菜叶绿体DNA(ct DNA),克隆到载体pGA46的BgⅢ位点,得到了具有启动功能的菠菜ct DNA片段,对其中的两个片段进行序列分析后观祭到有与原核生物启动区域相符的保守顺序。由此,本文对片段所具有的启动功能的强弱做了说明。