两种不同生态型麻疯树夏季光合特性的比较

以来源于海南及贵州的两种不同生态型麻风树(Jatropha curcas L.)为试材,利用LI-6400便携式光合作用测量系统及PAM-2100调制叶绿素荧光仪,在夏季对其气体交换特性及叶绿素荧光参数等进行测定.光强-光合速率响应曲线显示两种不同生态型叶片最大净光合速率(Pmax)和光饱和点(LSP)分别为18.9μmol · m-2 · s-1、1600μmol · m-2 · s-1(贵州型)和20.4μmol · m-2 · s-1、1700μmol · m-2 · s-1(海南型),而CO2光合速率响应曲线则显示两者的差异不大.两者的净光合速率(Pn)的日变化曲线都呈双峰型,主峰出现在10:00,在14:00左右出现低谷,次峰出现在16:00左右,有明显的光合"午休"现象.海南麻风树的Pmax、LSP、光补偿点(LCP)、表观量子效率(AQY)和暗呼吸速率(Rd)均高于贵州麻风树.两种生态型麻风树PSⅡ最大原初光化学效率(Fv/Fm)日变化无显著差异, 而实际光化学效率(ΦPSⅡ)变化趋势与Pn相同.这表明麻风树是一种具有较高的光合速率和强光适应性的木本能源植物,不同生态型麻风树的气体交换特性及叶绿素荧光参数有一定的差异,海南麻风树对强光的适应能力强于贵州麻风树.     

持续低温弱光对黄瓜叶片气体交换、叶绿素荧光猝灭和吸收光能分配的影响

持续常温弱光(25℃/18℃,l00umol m-2 s-1)、低温弱光(12℃/12℃,100 umol m-2 s-1和7℃/7℃,l00μmolm-2s-1)均导致黄瓜生长减慢或停滞、叶绿素含量、气孔导度和净光合速率、光合电子传递速率下降以及胞间CO2浓度上升.常温弱光和12℃弱光处理对光系统II的最大光化学效率Fv/Fm无显著影响,而7℃弱光处理导致Fv/Fm的可逆性下降.常温弱光和7℃、12℃弱光处理均导致了光化学反应速率的降低以及天线热耗散和反应中心过剩能量的增加.在胁迫后,12℃弱光0比7℃弱光更有利于植株光合功能的恢复.     

不同水分条件下三种附生地衣的光合作用特性

附生地衣是哀牢山湿性常绿阔叶林生态系统中重要的结构性组分。通过对该区域山地森林中3种典型附生地衣平滑牛皮叶 (Sticta nylanderiana)、网肺衣 (Lobaria retigera) 和橄榄斑叶 (Cetrelia olivetorum)在不同水分条件下的光合光响应及荧光参数的测定分析,结果显示,附生地衣光补偿点 (LCP)、光饱和点 (LSP)较高,对强光适应能力较强。在水分胁迫 (含水量5%~10%) 条件下,3种附生地衣的最大净光合速率 (Pmax) 仅为17~50nmol·g-1·s-1。随着含水量的增加,地衣的最大净光合速率 (Pmax) 与暗呼吸速率 (Rday) 逐渐增大,LCP降低,而LSP随之提高,这表明3种附生地衣具备“阳生植物”的某些特性,从而能够在一定程度上适应野外光照较强的灌丛、向阳林冠等生境。地衣叶绿素光反应中心初始荧光参数 (F0) 和最大光化学效率 (Fv/Fm) 随含水量下降而显著降低,暗示其光反应中心对水分有很强的敏感性。水分条件的改善有助于附生地衣的光反应中心进入到较高的生理活性状态。     

8种城市绿化攀缘植物的光合作用和水分关系特性

研究了华南地区有较好开发利用前景的8种城市绿化攀缘植物禾雀花(Mucuna birdwoodianauna)、炮仗花(Pyrostegia venusta)、鸡蛋果(Passiflora edulis)、使君子(Quisqualis indica)、蒜香藤(Pseudocalymma alliaceum)、小花青藤(Illigera paviflora)、龙吐珠(Clerodendron thomsonae)和砾叶粉藤(Cissus rhombifolia)盆栽植株叶片的光合速率-光强响应曲线,叶片部分形态特征和水分关系参数。结果表明,8种植物的Pmax(最大光合速率)、LSP(光合作用光饱和光强)、LCP(光合作用光补偿点)均较低,但在光合有效辐射(PAR)强度达1700μmolm-2s-1下未出现光抑制现象,显示其光合机构具有应对低光及高光强的可塑性。光强的提高会改变ILUE(瞬时光能利用效率)、Gs(气孔导度)、Tr(蒸腾速率)和Ci(细胞间隙CO2浓度)值,高光强下(PAR>500μmolm-2s-1)的Pn(净光合速率)与Gs呈正相关。低Gs和Ci是强光下限制Pn的主要因子。LT(叶片厚度)与水分关系参数(RWC相对含水量,IWUE瞬时水分利用效率,AWLR平均失水速率和RR复水率)之间没有明显的相关性。不同植物的Pmax,ILUE,LA,LT,IWUE和光合色素(Chl叶绿素,Car类胡萝卜素)含量等皆有显著的差别。禾雀花、炮仗花和鸡蛋果的光合作用和水分关系特性优于其余种类,而蒜香藤和小花青藤的这些参数的水平最低。     

光氧化胁迫下几种植物叶片的超氧自由基产生速率和光合特性

以甲基紫精 (MV) 0～ 1mmol/L在 15 0 0 μmolm-2s-1光下处理C3 植物花生、水稻和C4 植物玉米、甘蔗的叶圆片 30min ,O- ·2 产生速率随MV浓度提高而加快。MV浓度超过 10 μmol/L ,光合放氧出现负值并持续增大。光氧化作用降低叶绿素荧光参数Fv/Fm ,ΦPSⅡ和qP,而qN 则或提高 (C3 植物 ,MV 10 μmol/L )或几乎不变甚至有所降低 (C4 植物或C3 植物在高浓度MV下 )。热耗散系数KD 的变化与qN 相似。与C4 植物相比 ,C3 植物的O- ·2 产生速率和光下吸氧的速率较高 ,SOD活性较低 ,Fv/Fm ,ΦPSⅡ和qP 的降低幅度比C4植物大。对田间玉米叶片的MV涂抹试验看到 ,MV降低光合CO2 同化速率的同时 ,也降低气孔导度、PEP羧化酶和SOD活性 ,Ci增大。结果表明MV光氧化作用刺激PSⅠ的O2 光还原作用 ,引起PSⅡ部份失活 ,气孔部份关闭和关键酶类氧化失活 ,从而抑制了光合作用     

浑善达克沙地不同光合途径植物叶片气体交换和水势特征(英文)

以生长于浑善达克沙地上的C3植物白榆(Ulmus pumila)、C4植物沙米(Agriophyllum pungens)和CAM植物钝叶瓦松(Orostachys malacophyllus)3种不同光合途径植物为材料,测定了它们生长期叶片的光合气体交换参数、叶绿素荧光参数和水势,探讨它们对生长环境的生理响应特征.结果表明,白榆和沙米的净光合速率、气孔导度均高于钝叶瓦松,特别是在夏季高温(>40℃)和强光照(>2 100 μmol·m-2·s-1)条件下表现得更加明显.白榆和沙米的光合速率、叶片水势都发生了严重的午休现象,其白天光合速率的降低主要是由于气孔关闭造成的.钝叶瓦松的叶片水势在3种植物中最高,但是白天的光合速率很低;其Fv/Fm值在14:00最低,一天中此时光系统II受伤害最大;CAM物种瓦松的碳固定仅发生在夜间.研究发现,C3植物白榆和C4植物沙米比CAM植物钝叶瓦松对热和高光照有着更强的忍耐力,瓦松固定碳主要发生在生长最快的阶段;CAM植物瓦松为了能够在夏季强光和高温条件下生存,它必须进行高强度的呼吸,仅在早晨和夜间进行碳固定.     

濒危植物毛瓣金花茶与其同属广布种茶光合特性的比较

毛瓣金花茶为山茶科山茶属植物,该研究分别对野生种群和栽培种群的毛瓣金花茶及其同属广布种茶的光合特性进行了测定及差异比较。结果表明:在野生和栽培环境下,毛瓣金花茶的光补偿点(LCP)(分别为1.17和3.87μmol·m-2·s-1)和光饱和点(LSP)(分别为395.8和423.6μmol·m-2·s-1)均较低,最大净光合速率(Pmax)(分别为4.25和3.91μmol·m-2·s-1)较小,是典型的阴生植物;而茶的LCP(分别为6.57和9.09μmol·m-2·s-1)较低,LSP(分别为765.0和809.6μmol·m-2·s-1)较高,Pmax(分别为9.37和9.75μmol·m-2·s-1)较大,为耐荫植物。野生和栽培的毛瓣金花茶的Pmax、表观量子效率(AQY)、最大羧化速率(Vcmax)、最大电子传递速率(Jmax)和潜在最大净光合速率(Pmax)均显著低于茶(P0.05),这表明毛瓣金花茶的光合能力和CO2利用能力都比茶要弱。栽培的毛瓣金花茶叶片的Chla、Chlb、Chl(a+b)含量与茶相比无显著差异(P0.05),表明毛瓣金花茶较低的光合能力与其叶绿素含量无关。野生和栽培的毛瓣金花茶的叶面积与茶相比无显著差异(P0.05),而比叶重则显著高于茶(P0.05),与茶相比,毛瓣金花茶对光强的适应范围狭窄,光合能力和CO2利用能力低下,这可能是其分布狭窄的重要生理原因。     

青藏高原药用植物唐古特山莨菪和唐古特大黄光合作用对强光的响应

与唐古特大黄相比,唐古特山莨菪的表观光合量子效率(AQY)较高,但最大净光合速率(Pmax)较低。在光强小于1200μmolm-2s-1时,后者用于碳同化的电子传递占总光合电子传递的比例(JC/JF)比前者高,而分配于光呼吸的电子传递(JO/JF)及Rubisco氧化和羧化速率的比值(VO/VC)则相反;光强大于1200μmolm-2s-1以后两种植物的这些参数都趋向稳定。随光强增加,后者叶片吸收光能分配于热耗散(D)的增加斜率较前者高,表明两高山植物对强辐射的适应方式略有不同。加强光呼吸途径的耗能代谢和PSII天线热耗散份额是唐古特山莨菪适应高原强辐射的主要方式,而提高叶片光合能力则是唐古特大黄的一种适应方式。     

金沙江干热河谷希蒙得木光合及叶绿素荧光特性

比较研究了4a生希蒙得木[Simmondsia chinensis(Link.)Schneider]两个种源(美国Hyder和以色列Vacaville)叶片的光合及叶绿素荧光特性。结果表明:在金沙江干热河谷地区两个种源的希蒙得木的净光合速率(Pn)、气孔导度日变化均呈单峰曲线,峰值出现在上午10:00。相同的试验条件下,Vacaville种源的净光合速率、气孔导度高于Hyder种源;经充分暗适应后,Vacaville种源的叶片叶绿素F0、Fm、Fv、Fv/F0、NPQ和ETR均高于Hyder种源。光强度在200 μmol m-2s-1以下,两个种源的PhiCO2和PhiPS2呈线性负相关;而光强度在200-2000 μmol m-2s-1间则呈线性正相关。空气中CO2浓度和荧光光合速率、PhiPS2、PhiCO2值存在着一定的正相关关系。Vacaville种源较Hyder种源更适应金沙江干热河谷气候。     

新疆杂交榛良种光合作用对生态因子的响应

在夏季田间条件下,研究了4种新疆平欧杂交榛的光合特性。结果表明:4个品种的光饱和点(LSP)、光补偿点(LCP)、CO2饱和点(CSP)、CO2补偿点(CCP)分别位于1195.27～1620.63μmol·m-2·s-1、34.03～87.80μmol·m-2·s-1、1188.50～1617.05μmol·mol-1和64.88～99.15μmol·mol-1;新榛1号和新榛4号表现出低光合低蒸腾的特点,新榛2号具有较低的LCP和较高的LSP,表现出对光能利用范围较大、光合潜力高的特点,新榛3号的LCP和LSP均较大,同时具有低的CCP和高的CSP及表观羧化效率(CE),其最大净光合速率(Pmax)(31.55μmol·m-2·s-1)明显高于其他品种(24.63～25.45μmol·m-2·s-1);此外,与常温(25℃)相比,新榛1号的净光合速率(Pn)受40℃高温的影响较其他品种显著,新榛3号的气孔导度(Gs)比其他品种受影响的程度轻。     

六种藓类植物茎的比较解剖学研究

通过对6种藓类植物,即褶叶青藓(Brachythecium salebrosum(Web.et Mohr.)B.S.G.)、湿地匐灯藓(Plagiomnium acutum(Lindb.)Kop.)、侧枝匐灯藓(Plagiomnium maximoviczii(Lindb.)Kop.)、大凤尾藓(Fissidensnobilis Griff.)、大羽藓(Thuidium cymbifolium(Doz.et Molk.)B.S.G.)和大灰藓(Hypnum plumaeforme Wils.)嫩茎和老茎的石蜡切片和显微观察发现,同一藓类植株的嫩茎和老茎,茎结构稳定,不同种藓类植物茎横切面具有不同特征.植物体茎横切面形状、表层细胞的层数、细胞大小和细胞壁厚薄、皮层细胞大小和形状、中轴的有无以及比例等特征可以作为藓类植物的分科分类依据之一.     

Photoregulation of seed germination of wild-type and of an aurea-mutant of tomato

Seed germination of an aurea mutant of tomato ( Lycopersicon esculentum Mill.) is promoted by continuous irradiation with red, far-red or long-wavelength far-red (758 nm) light as well as by cyclic irradiations (5 min red or 5 min far-red/25 min darkness). Far-red light applied immediately after each red does not change the germination behaviour. Seed germination of the isogenic wild-type, cv. UC-105, is promoted by continuous and cyclic red light while it is inhibited by continuous and cyclic far-red light and by continious 758 nm irradiation. Far-red irradiation reverses almost completely the promoting effect of red light. The promoting effect (in the aurea mutant) and the inhibitory effect (in the wild-type) of continuous far-red light do not show photon fluence rate dependency above 20 nmol m⁻² s⁻¹. It is concluded that phytochrome controls tomato seed germination throgh low energy responses in both the wild type and the au mutant. The promoting effect of continuous and cyclic far-red light in the au mutant can be attributed to a greater sensitivity to P_fr.     

Cause of Senescence of Nine Sorts of Flowers

The levels of endogenous phytohormones and respiratory rate in nine sorts of flowers such as Cymbidium faberi Rolfe, Nopalxochia ackermannii Kunth and others were investigated both at full bloom and senescence and meanwhile the effect of exogenous phytohormones on prolonging the blossoms and promoting ethylene production were tested. There is a high content of endogenous ethylene in all the long-lived flowere, about 3–16 folds higer than the short-lived ones. There is a high level of ABA at full blooming flowers of short-lived flowers, in which there is no or only some cytokinins in it, but the ratio of CTK (6BA+zeatin)/ABA is smaller(l.7). The endogenous ABA reached a much higher level at senescence in all nine sorts of flowers, so it is reasonable to consider that it is ABA which plays an important role of regulation in controlling flower's senescence. There is a much higher level of GA3 and zeatin in the long-lived flowers which is not demonstrated in the shortlived ones. The respiratory rate is one of the factors controtling the longevity of flowers, but it does not play a decided role. Application of 6BA and zeatin prolongs distinctly orchid’s longevity, however exogenous IAA through the promotive action on ethylene production, evidently extends the longevity of the flowers of the Nopalxochia ackermannii Kunth.     

龙胆科药用植物化学成分的研究现状

龙胆科植物在我国的分布范围很广,且多数为药用植物,其多数种属的药用植物,至今其化学成分尚未被系统研究。综述了目前龙胆科药用植物的化学成分的研究现状及一般提取方法,对近年来发现的环烯醚萜及裂环烯醚萜类化合物进行了总结,为本科药用植物的更深入研究提供了参考。     

Interconnection of parameters of regulation system of lipid peroxidation and of morphophysiological parameters of mouse liver

A complex analysis of seasonal fluctuations of the mean group parameters of the system of regulation of lipid peroxidation has been performed in liver of Balb/c mice. Association of lipid characteristics and morphophysiological parameters is studied in the Balb/c mouse liver. An inter-connection is revealed between the liver index and the amount of lysoforms of phospholipids, the scale and character of the interconnection differing essentially depending on proportion of phos-phatidylcholine in mouse liver phospholipids.     

The effects of glutamine of the maintenance of embryogenic cultures of Cryptomeria japonica

Summary Embryogenic tissues of sugi (Cryptomeria japonica) were induced on a modified Campbell and Durzan (CD) medium containing 1 μM 2,4-dichlorophenoxyacetic acid (2,4-D) and 600 mg l⁻¹ glutamine, and subcultured in the medium of the same composition for over 1 yr. This resulted in a mixed culture of embryogenic and non-embryogenic cells. When embryogenic cells were isolated and cultured independently, their capacity to form embryogenic aggregates was lost. Thus, the non-embryogenic cells present within a mixed culture system were essential to the formation of embryogenic aggregates. When embryogenic tissues were isolated and cultured independently on a high glutamine-containing (2400 mg l⁻¹) medium, dry weights and endogenous levels of glutamine increased, and the tissue could generate a large number of embryogenic aggregates. Amino acid analysis of embryogenic and non-embryogenic cells from the maintenance culture indicated a higher level of glutamine was present in the latter. The high endogenous level of glutamine in the non-embryogenic portion of mixed cell masses may be the supplier of glutamine for maintaining the embryogenic property of the tissues.     

Specificity of action of piperidylcholine derivatives as substrates of cholinesterases of various origin

The review deals with study of enzymologic properties of a novel highly specific acetylcholinesterase substrate, N-(β-acetoxyethyl) piperidinium iodomethylate (“piperidylcholine”), and its 30 derivatives that were tested as effectors of cholinesterases of mammals and various species of Pacific squids. It was proven for the first time that responsible for specificity of action was structure of cyclic ammonium grouping of the alcohol part of molecule of the ester substrate. Analysis of specificity is performed based on enzymatic hydrolysis parameters—activity of catalytic center of cholinesterases and bimolecular constant of the reaction rate that are determined at optimal and low substrate concentrations. Among the specially synthesized group of thioester compounds there is revealed one more highly specific acetylcholinesterase substrate—N-(β-acetoxyethyl) piperidinium.     

Physiological characteristics of various species of strains of carboxydobacteria

Seven strains of aerobic carbon monoxide-oxidizing bacteria (carboxydebacteria) when growing on CO as sole source of carbon and energy had doubling times which ranged from 12–42 h. The activity profiles obtained after discontinuous sucrose density gradient centrifugation indicated that the CO-oxidizing enzymes are soluble and the hydrogenases are membrane-bound in all strains examined. The CO-oxidizing enzymes of Pseudomonas carboxydohydrogena, Pseudomonas carboxydoflava, Comamonas compransoris, and the so far unidentified strains OM2, OM3, and OM4 had a molecular weight of 230,000; that of Achromobacter carboxydus amounted to 170,000. The molecular weights of the CO-oxidizing and H₂-oxidizing enzymes turned out to be identical. The cell sonicates were shown to catalyze the oxidation of both CO and H₂ with methylene blue, thionine, phenazine methosulfate, toluylene blue, dichlorophenolindophenol, cytochrome c or ferricyanide as electron acceptors. Methyl viologen, benzyl viologen, FAD⁺, FMN⁺, and NAD(P)⁺ were not reduced. The spectrum of electron acceptors was identical for all strains tested. Neither free formate, hydrogen nor oxygen gas were involved in the CO-oxidation reaction. Methylene blue was reduced by CO at a 1:1 molar ratio. The results indicate that CO-oxidation by carboxydobacteria is catalyzed by identical or similar enzymes and that the reaction obeys the equation CO+H₂OCO₂+2H⁺+2e^- as previously shown for Pseudomonas carboxydovorans.Dedicated to Otto Kandler remembering almost three decades of enjoyable cooperation     

Modulation of allostery of pyruvate kinase by shifting of an ensemble of microstates

Since the introduction of the concepts of allostery about four decades ago, much advancement has been made in elucidating the structure-function correlation in allostery. However, there are still a number of issues that remain unresolved. In this review we used mammalian pyruvate kinase (PK) as a model system to understand the role of protein dynamics in modulating cooperativity. PK has a triosephosphate isomerase (TIM)(α/β)₈ barrel structural motif. PK is an ideal system to address basic questions regarding regulatory mechanisms about this common (α/β)₈ structural motif. The simplest model accounting for all of the solution thermodynamic and kinetic data on ligand-enzyme interactions involves two conformational states, inactive E^T and active E^R. These conformational states are represented by domain movements. Further studies provide the first evidence for a differential effect of ligand binding on the dynamics of the structural elements, not major secondary structural changes. These data are consistent with our model that allosteric regulation of PK is the consequence of perturbation of the distribution of an ensemble of states in which the inactive E^T and active E^R represent the two extreme end states. Sequence differences and ligands can modulate the distribution of states leading to alterations of functions. The future work includes: defining the network of functionally connected residues; elucidating the chemical principles governing the sequence differences which affect functions; and probing the nature of mutations on the stability of the secondary structural elements, which in turn modulate allostery.