盐分胁迫下杠柳叶片光合特性的光响应研究

利用CID型便携式光合作用仪测定不同NaCl浓度下杠柳叶片净光合速率(P_n)、蒸腾速率(T_r)、气孔导度(G_s)、水分利用效率（WUE）及光能利用率(LUE)生理参数的光响应过程,阐明盐分胁迫下其对光照响应的规律,探讨有利于杠柳正常生长的盐分浓度和光照条件。结果表明:（1）各盐分浓度下杠柳叶片光补偿点（LCP）在21.89～65.05 μmol·m^-2·s^-1之间变动,介于阴性植物与阳性植物之间;杠柳随土壤盐分的不同,其光合作用参数对光照强度表现出一定的适应性和可塑性;50 mmol·L^-1盐分浓度下杠柳光合同化能力最强,最有利于其干物质的积累,表现出一定的耐盐性。（2）轻度的盐分胁迫（小于50 mmol·L^-1）可以提高杠柳叶片的P_n、G_s、WUE和LUE,而盐分胁迫对杠柳的T_r有抑制作用,并随着盐分浓度的增加其抑制作用愈强烈。（3）维持杠柳正常生长的土壤盐分浓度小于50 mmol·L^-1,最佳PAR为1 000～2 000 μmol·m^-2·s^-1;而保持杠柳最大WUE和LUE的光照强度分别为800和100 μmol·m^-2·s^-1。     

草光合作用日变化及其与环境因子的关系

对镇江北固山湿地优势植物——〓草的光合作用进行了试验研究。结果表明,春夏季晴天〓草净光合速率(P_n)的日变化为双峰曲线,有明显的光合“午休”现象;多云天〓草的P_n主要受光强制约,随光合有效辐射(PAR)变化而变化。经统计学验证,〓草的P_n与PAR、气孔导度(G_s)有显著正相关关系,而与细胞间隙CO₂浓度(C_i)呈显著负相关。用一元二次方程拟合了〓草的光响应曲线,得到光补偿点为38.572 μmol·m^-2·s^-1,光饱和点为2 087.5 μmol·m^-2·s^-1。     

城市不同地表覆盖类型对土壤呼吸的影响

采用Licor-6400-09的土壤呼吸测量系统对北京市区3种不同覆盖类型地表(全硬地表、半透砖地表、草坪覆盖地表)的土壤呼吸速率及其影响因子进行了测定和分析。结果表明:(1)不同地表覆盖类型的土壤呼吸速率年均值分别为7.928 μmol·m^-2·s^-1(全硬地表),5.592 μmol·m^-2·s^-1(部分硬化地表)、2.625 μmol·m^-2·s^-1(草坪覆盖地表);土壤呼吸日均值最高均出现在夏季(14.785,10.296,5.143 μmol·m^-2·s^-1),最低为冬季(0.490,0.319,0.239 μmol·m^-2·s^-1);(2)3种地表类型的土壤呼吸速率有显著差异(P<0.05),大小排序为:草坪覆盖地表<部分硬化地表<全硬地表;(3)3种地表类型土壤呼吸速率均与土壤温度呈显著的指数相关,Q₁₀值排序为:草坪覆盖地表<部分硬化地表<全硬地表;(4)土壤含水率和土壤电导率与土壤呼吸均有一定的相关性,但关系较为复杂,有待于进一步研究。     

显脉金花茶的光合生理特性研究

采用LI-6400便携式光合测定系统(Li-Cor Inc., USA)对显脉金花茶光合特性进行研究。结果表明：(1)在夏季,显脉金花茶叶片的P_n日变化呈单峰曲线,最高峰出现在中午11：00。其最大净光合速率（P_max）为3.81 μmol·m^-2·s^-1、光饱和点（LSP）为459.9 μmol·m^-2·s^-1、光补偿点（LCP）为6.9 μmol·m^-2·s^-1。显脉金花茶的光饱和点和光补偿点都比较低,表明其是一种阴生植物。（2）在控制光照强度和温度的条件下,CO₂浓度小于800 μmol·mol^-1,P_n几乎呈直线上升,升高CO₂浓度可使显脉金花茶的净高合速率增大,提高了叶片对光能的利用率。其叶片CO₂饱和点(CSP)大约在1 200 μmol·mol^-1左右,CO₂的补偿点（Г^*）为70.1 μmol·mol^-1,最大羧化速率（V_cmax）为17.5 μmol·m^-2·s^-1,最大电子传递速率（J_max）为40 μmol·m^-2·s^-1。     

华北平原玉米田生态系统光合作用特征及影响因素

采用涡度相关法对华北平原夏玉米田进行了连续4a(2003-2006年)的碳通量观测,结果表明:夏玉米田生态系统初始量子效率(α)、最大光合速率(P_max)、暗呼吸速率(R_d)和总初级生产力(GPP)随作物生长发育而变化。在夏玉米生育前期和后期,α、P_max、R_d和GPP都比较小,其最大值出现在抽穗期/灌浆期。2003-2006年,夏玉米生长季平均α、P_max、R_d的范围分别为0.054-0.124 μmol/μmol、1.72-2.93 mg CO₂ · m^-2 · s^-1、0.23-0.38 mg CO₂ · m^-2 · s^-1。α、P_max和R_d均随叶面积指数(LAI)增加呈指数增长。2003-2006年夏玉米生长季GPP总量分别为806.2、741.5、703.0、817.4 g C/m²,年际差异较大。玉米田生态系统GPP随温度升高呈指数增长。在玉米营养生长阶段,GPP随LAI增加而增大,两者之间的关系可用直角双曲线方程来表示;生殖生长阶段,GPP随LAI降低而下降.相同LAI下,生殖生长阶段的GPP明显低于营养生长阶段。     

昆仑山北坡不同海拔塔里木沙拐枣的光合生理生态特性

在2008年7月25日-8月6日的连续晴天中,选择昆仑山北坡塔里木沙拐枣自然分布区3个海拔高度(2100,2300,2500m),利用便携式光合测定仪LI-6400测定塔里木沙拐枣的光合生理生态特性。结果表明:2100m处塔里木沙拐枣的光补偿点(LCP)和光饱和点(LSP)与2300m,2500m处差异分别达到显著,而3者间的最大净光合速率(P_max)差异均达显著。表观量子效率(AQY)在3个海拔之间差异均不显著,但在2100m处的羧化效率(CE)分别与2300m和2500m处的差异显著。相同海拔下塔里木沙拐枣的暗呼吸速率值(R_day)要高于光呼吸速率值(R_p),且2500m处的暗呼吸速率分别与2100m和2300m处的有显著的差异,2100m处的光呼吸速率分别与2300m和2500m差异显著。3个海拔塔里木沙拐枣的净光合速率(P_n)、蒸腾速率(T_r)和气孔导度(G_s)的日变化均为单峰曲线。随着海拔的升高,塔里木沙拐枣P_n,T_r,G_s和L_s的日均值降低,但光能利用率(LUE)和水分利用效率(WUE)却显著增加。塔里木沙拐枣的P_n与叶温(T_l)、大气温度(T_a)和光照强度(PPFD)具有极显著的正相关关系,与海拔呈显著负相关,与空气相对湿度(RH)和大气CO₂浓度(C_a)之间均不具有显著相关性。T_r与T_a,T_l和PPFD具有极显著的正相关性,与RH之间存在显著的负相关。G_s只与C_a之间呈极显著的负相关。P_n与T_r,L_s,G_s,WUE和V_pdl分别具有极显著的正相关性,与C_i呈极显著的负相关。通过对不同海拔高度塔里木沙拐枣光合生理参数与光、温等生态因子关系的对比分析表明:塔里木沙拐枣对山地荒漠草地自然环境变化的温度和光照有很好的生态适应性。     

Photoinhibition during acclimatization of micropropagatedSpathiphyllum “Petite” plantlets

Summary MicropropagatedSpathiphyllum “Petite” plantlets were acclimatized at low- or high-light intensities [photosynthetic photon flux density (PPFD) 100 or 300 μmol·m⁻²·s⁻¹]. During the first days chlorophyll fluorescence measurements show a partial photoinhibition of the photosynthetic apparatus, expressed by a decrease of the variable over maximal fluorescence ratio (F_v/F_m). This inhibition of F_v/F_m was significantly higher for plants grown at high-light intensity, leading to a photooxidation of chlorophyll. Newly formed leaves were better adapted to the ex vitro climatic condition (as shown by the increase of the F_v/F_m ratio) and had a higher net photosynthesis compared with in vitro formed leaves. Nevertheless, plants grown at 300 μmol·m⁻²·s⁻¹ were photoinhibited, compared with those at 100 μmol·m⁻²·s⁻¹. A sudden exposure to high-light intensity of 1-, 10- or 25-d-old transplanted plants (shift in PPFD from 100 to 300 μmol·m⁻²·s⁻¹) gave a linear decrease of F_v/F_m over a 12-h period, which was reflected in a 50% reduction of net photosynthesis. No significant interaction between day and hour was found, indicating high-light exposure causes the same photoinhibitory effect on in vitro and ex vitro formed leaves.     

修剪节位及修剪时期对四季蜜芒枝条生长及反季节开花的综合效应

五种模型分别运用于紫茉莉的光合—光响应及CO₂响应曲线的拟合,研究其光合效率参数的变化,探讨紫茉莉光合—光响应及CO₂响应的最适模型。结果表明:(1)紫茉莉的光合—光响应及CO₂响应改进指数模型拟合R²均为0.999,拟合效果优于非直角双曲线、直角双曲线和直角双曲线修正模型。其饱和光强和最大净光合速率分别为797.299和7.879 μmolCO₂·m^-2·s^-1,饱和CO₂浓度和最大光合能力分别为1 264.447和16.783 μmol CO₂·m^-2·s^-1,均与实测值最接近;(2)五个模型拟合和预测的均方误差(MSE)、平均绝对误差(MAE),都是改进指数模型小于其他模型。改进指数模型为紫茉莉光合—光响应及CO₂响应曲线的最佳模型,实验结果可为紫茉莉的生理生态应用研究提供参考。     

改进指数模型对紫茉莉光合-光响应及CO2响应适用性研究

五种模型分别运用于紫茉莉的光合—光响应及CO₂响应曲线的拟合,研究其光合效率参数的变化,探讨紫茉莉光合—光响应及CO₂响应的最适模型。结果表明:(1)紫茉莉的光合—光响应及CO₂响应改进指数模型拟合R²均为0.999,拟合效果优于非直角双曲线、直角双曲线和直角双曲线修正模型。其饱和光强和最大净光合速率分别为797.299和7.879 μmolCO₂·m^-2·s^-1,饱和CO₂浓度和最大光合能力分别为1 264.447和16.783 μmol CO₂·m^-2·s^-1,均与实测值最接近;(2)五个模型拟合和预测的均方误差(MSE)、平均绝对误差(MAE),都是改进指数模型小于其他模型。改进指数模型为紫茉莉光合—光响应及CO₂响应曲线的最佳模型,实验结果可为紫茉莉的生理生态应用研究提供参考。     

淡水驯化对桐花树光合生理特性的影响

以实验地全光照条件下淡水和人工海水培养种植的桐花树（Aegiceras corniculatum）幼苗为材料,采用Li 6400光合测定仪对不同月份桐花树幼苗的光合生理生态特性日动态进行测定,研究了桐花树的光合生理生态特性。结果表明：在7、10月份桐花树的净光合速率日变化呈双峰型,均出现“光合午休”现象。在7月份人工海水组和淡水组的最大净光合速率（P_max）分别为9.97和11.95 μmol·m^-2·s^-1;而10月份的P_max分别为12.2和12.9 μmol·m^-2·s^-1。而且淡水驯化下,桐花树的净光合速率较人工海水组高。由光响应曲线可知,桐花树人工海水组的最大净光合速率（P_max）、光饱和点（LSP）、光补偿点（LCP）和表观量子效率（AQY）分别为7 μmol·m^-2·s^-1,1 477 μmol·m^-2·s^-1,30 μmol·m^-2·s^-1,0.031 3;而淡水组为8.69 μmol·m^-2·s^-1,980 μmol·m^-2·s^-1,40 μmol·m^-2·s^-1,0.011。在所测的生理生态因子中,光合有效辐射和气孔导度是影响桐花树光合作用最为强烈的因子,与桐花树的净光合速率和蒸腾速率均有极显著的相关关系（p<0.01）。试验说明淡水驯化的桐花树对光强的利用范围变窄,但有较高的净光合速率,表明桐花树对淡水环境具有较强的适应性。     

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.     

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.     

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。     

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.     

（鱼句）亚科花（鱼骨）型鱼类骨骼系统的比较

对我国花型Hemibarbuspattern鱼类作了骨骼系统比较,结果表明,此类型鱼类脑颅较长,副蝶骨平直或稍弯曲,眶蝶骨腹纵嵴发达(铜鱼Coreius septentrionalis例外),下颞窝和咽突中等大,基枕骨后突发达;脑颅中的上筛骨的后突、侧筛骨的外筛突,蝶耳骨的外突、上耳骨的后突、围眶骨和后颞窝等均有明显的差异;咽颅中的舌颌骨、尾舌骨、鳃盖骨和下咽齿的列数等又有显著的区别;附肢骨骼中的腰带骨、脊椎骨中的复合神经骨和第4椎骨腹侧的悬器等也有不同之处。据此,这些差异和区别可作为属间或种间的分类依据。