Analysis of Photosynthetic Responses and Adaptation to Nitrogen Starvation in Chlorella Using In Vivo Chlorophyll Fluorescence

Nitrogen (N) starvation resulted in degreening, inhibition of photosynthetic oxygen evolution and dark respiration, reduced survival, and increased age-specific mortality in both Chlorella fusca and Chlorella vulgaris. Analysis of in vivo chlorophyll (Chl) fluorescence induction kinetics revealed the presence of N-starvation-induced changes at the level of degreened thylakoids in both species. These changes included decreased yield of the photochemistry of photosystem 2 (PS2), and a declined photosynthetic efficiency. Synthesis of secondary carotenoids represented a biochemical change in carotenogenesis that had a photoprotective effect in degreened C. fusca. This inferred photoprotection was reflected in the delayed inhibition of oxygen evolution and improved survival of C. fusca under N-starvation. The effect was further elucidated by comparison with C. vulgaris which was not able to synthesize secondary carotenoids under the same conditions.     

Fluorescence Decay Studies of Chlorophyll a in Vivo

The study of the fluorescence of chlorophyll a offers a useful approach toward better understanding of the primary act of photosynthesis. This paper describes new measurements of the decay of chlorophyll a fluorescence in vivo, made with a considerably improved oscilloscopic-display technique. The main result is the identification of two decay periods both of the order of a few nanoseconds. Possible interpretations of this phenomenon are discussed.     

Characterization of Photosynthetic Rhythms in Marine Dinoflagellates: II. Photosynthesis-Irradiance Curves and in Vivo Chlorophyll a Fluorescence

Using data from light-dark cultures of Gonyaulax polyedra entrained to a 24-hour cycle, whole cell absorption curves and photosynthesis-irradiance curves were constructed for various circadian times. While whole cell absorbance and half-saturation constants of photosynthesis showed no statistical difference that could be directly related to the photosynthetic rhythm, the initial slope of the photosynthesis-irradiance curve was a time-dependent parameter which altered in direct proportion to the change in photosynthetic capacity. The results indicated a temporal change in the relative quantum yield of photosynthesis, and the circadian rhythmicity of light-limited photosynthesis was established under constant conditions. Circadian rhythmicity was detected in room temperature chlorophyll fluorescence yield. Low temperature fluorescence kinetics also showed fluctuations. The results suggest that regulation of photosynthesis by the biological clock of Gonyaulax may be mediated through the membrane-bound light reactions and a partial explanation of the underlying mechanism is proposed.     

Measurement of Differences in Red Chlorophyll Fluorescence and Photosynthetic Activity between Sun and Shade Leaves by Fluorescence Imaging

With a flash-lamp chlorophyll (Chl) fluorescence imaging system (FL-FIS) the photosynthetic activity of several thousand image points of intact shade and sun leaves of beech were screened in a non-destructive way within a few seconds. The photosynthetic activity was determined via imaging the Chl fluorescence at maximum F_p and steady state fluorescence F_s of the induction kinetics (Kautsky effect) and by a subsequent determination of the images of the fluorescence decrease ratio R_Fd and the ratio F_p/F_s. Both fluorescence ratios are linearly correlated to the photosynthetic CO₂ fixation rates. This imaging method permitted to detect the gradients in photosynthetic capacity and the patchiness of photosynthetic quantum conversion across the leaf. Sun leaves of beech showed a higher photosynthetic capacity and differential pigment ratios (Chl a/b and Chls/carotenoids) than shade leaves. Profile analysis and histogram of the Chl fluorescence yield and the Chl fluorescence ratios allow to quantify the differences in photosynthetic activity between different leaf parts and between sun and shade leaves with a high statistical significance.     

Assessment of Photosynthetic Performance of Prochloron in Lissoclinum patella in hospite by Chlorophyll Fluorescence Measurements

Two new PAM fluorometers (pulse amplitude modulated) were usedin an investigation of photosynthetic performance of Prochloronresident as a symbiont in the ascidian Lissoclinum patella,growing in a coral reef of Heron Island on the Great BarrierReef. With a new DIVING-PAM in situ measurements of effectivePSII quantum yield (     

Photoinhibition of Photosynthesis and in Vivo Chlorophyll Fluorescence in the Green Alga Ankistrodesmus braunii

The unicellular, green alga Ankistrodesmus braunii is subjectto a rapid photoinhibition of photosynthesis when exposed toa photon fluence rate in excess of that required to saturatephotosynthesis. Photoinhibition is manifested as a time-dependentdecrease in the capacity for either ¹⁴CO₂ fixation or CO₂-dependentO₂ evolution. Room temperature chlorophyll fluorescence inductionin intact cells, has been used to probe the primary site(s)of light damage during photoinhibition. Initially, at least,photoinhibition is due to a block in Photosystem II of photosyntheticelectron transport, at a site on the water-splitting side. (Received September 19, 1983; Accepted February 7, 1984)     

华南地区8种藤本植物叶绿素荧光特性对模拟二氧化硫污染的响应

研究了模拟SO2处理对8种华南地区常见盆栽藤本植物离体叶片的叶绿素荧光参数、快速光强响应曲线(RLC)、叶片总抗氧化能力(清除有机自由基1,1-diphenyl-2-picrylhydrazyl 水平)和叶片色素含量的影响.结果表明,经过10 h的20 mmol/L NaHSO3浸泡,8种藤本植物离体叶片的Fv/Fm,φPSII,rETR,rETRmax和RLC初始斜率α与对照(纯净水浸泡)相比有明显下降.8种供试植物的叶片总抗氧化能力和叶片色素含量的变化存在种间差异.8种藤本植物中龙吐珠(Clerodendron thomsonae)、锦屏藤(Cissus sicyoides)和禾雀花(Mucuna birdwoodiana)是对模拟SO2抗性较强的绿化藤本植物,抗性较差的是首冠藤(Bauhinia corymbosa)、红花西番莲(Passiflora coccinea)和宝巾(Bougainvillea glabra).     

观赏山楂耐热性及其叶片光合与叶绿素荧光特性研究

以引自国内外的15种观赏山楂苗木为材料,于上海夏季自然高温下对其叶片光合气体交换参数及叶绿素荧光参数进行测定,并观察它们的田间耐热性,以揭示其耐热的光合生理机制.结果显示,4种山楂表现出较强耐热性,6种较耐热,而5种耐热性较差;15种山楂叶片净光合速率(P_n)、蒸腾速率(T_r)、气孔导度(G_s)、瞬时水分利用效率(WUE)的种间差异显著(P<0.05),且耐热性强的品种P_n、T_r、G_s、WUE值较高,高温下能够维持较高的光合固碳水平;各品种山楂叶片的PSⅡ最大光能转换效率F_v/F_m、电子传递效率ΦPSⅡ和光能捕获效率F_v'/F_m'差异显著,耐热性强品种F_v/F_m保持在0.8以上,且ΦPSⅡ值与F_v'/F_m'较高.研究表明,观赏山楂主要通过加大气孔蒸腾散热、降低叶表面温度以及维持较高光能电子传递与转化效率来减轻高温对光合机构伤害,以维持植株正常光合作用;山楂叶片PSⅡ原初光能转换效率及潜在活性与其耐热性密切相关,F_v/F_m值可作为山楂耐热性鉴定指标.     

Reversible Inhibition of Poliovirus RNA Synthesis In Vivo and In Vitro by Viral Products

In poliovirus-infected HeLa-S3 cells, the protease inhibitors tolylsulfonyl-phenylalanyl chloromethyl ketone and iodoacetamide cause an accumulation of large precursor proteins, and they block viral RNA synthesis most probably via these products. Viral RNA polymerase activity can, however, be extracted by detergent containing buffer (Tris/Nonidet P-40, deoxycholate) from the inhibited cells. Only cytoplasmic extracts from infected cells treated with tolylsulfonyl-phenylalanyl chloromethyl ketone or iodoacetamide contain a protein which inhibits the in vitro polymerase reaction.     

Inhibition of Glutamine Synthetase Activity by Phosphinothricin Results in Disappearance of the Peak M2 of the Chlorophyll Fluorescence Induction Curve

The treatment of green algae Chlorococcum lobatum with the herbicide BASTA containing phosphinothricin lead to a significant decrease in the level of peak M2 of the chlorophyll fluorescence induction curve. This agrees with the suggestion that glutamine synthetase activity affects this region of the induction curve.     

Inhibition of Glutamine Synthetase Activity by Phosphinothricin Results in Disappearance of the Peak M2 of the Chlorophyll Fluorescence Induction Curve

The treatment of green algae Chlorococcum lobatum with the herbicide BASTA containing phosphinothricin lead to a significant decrease in the level of peak M2 of the chlorophyll fluorescence induction curve. This agrees with the suggestion that glutamine synthetase activity affects this region of the induction curve. This revised version was published online in June 2006 with corrections to the Cover Date.     

Phosphate Buffers Effect on Protective Enzyme System and Relationship of Enzyme System with SO2 Pollution in Wheat Seedlings

The effect of phosphate buffer on protective enzyme system was different as the way of treatment and wheat (Triticum aestivum L. ) species. Normally superoxide dismutase (SOD) and peroxidase (POD) activity increased markedly. The former decreased with the increase of SO2 fumigation dosage but it was higher than control and producted new isoenzyme pedigree. The latter increased according to SO2 fumigation and showed relative gain effect with phosphate buffer the isoenzyme pedigree increased markedly. The change of protective enzyme system of scavenging free radicals was possible one cause that phosphate buffer eased SO2 insult of wheat seedlings.     

氮素水平对不同品种茶树光合及叶绿素荧光特性的影响

为探明氮素水平对不同品种茶树的光合系统的影响机制,以‘福鼎大白茶’、‘保靖黄金茶1号’、‘白毫早’两年生茶苗为材料,设置不施氮N_0(0g)、低氮N_1(11g)、中氮N_2(22g)和高氮N_3(33g)4个氮素[(NH_4)_2SO_4]水平的盆栽实验,研究了铵态氮对3个品种茶树的生长势、叶片叶绿素含量、光合参数与叶绿素荧光参数的影响。结果表明:(1)施氮处理能够显著促进茶树的生长,提高茶树叶片叶绿素含量、净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr),降低胞间CO_2浓度(Ci),并以N_2处理最好,但水分利用率(WUE)在3个品种茶树间表现不同。(2)在N_2处理下,3个茶树品种的叶片光系统Ⅱ(PSⅡ)暗适应下的最大光化学效率(F_v/F_m)、光化学猝灭系数(qP)、PSⅡ的相对电子传递速率(rETR)亦增加最大,非光化学淬灭系数(NPQ)降低。(3)茶树叶片叶绿素含量与光合参数间存在着一定的联系,并且具有品种特异性。研究发现,适量施氮能够显著增加茶树叶绿素含量、气孔导度、光合活性,从而使得各品种茶树净光合速率增加;氮素水平对各茶树品种的光合及荧光特性影响存在差异,水分利用率亦具有品种特异性;生产中应综合叶绿素含量、光合作用参数、叶绿素荧光参数,可快速、直观地评价不同品种茶树对氮素营养的内在需求,为茶园施肥管理提供指导。     

大气CO2浓度倍增和施氮对冬小麦光合及叶绿素荧光特性的影响

采用开顶式气室,通过土培盆栽实验研究了不同大气CO2浓度(背景空气浓度375μmol·mol-1和倍增浓度750μmol·mol-1)和氮素水平(不施氮和施氮0.25 g/kg)下两个冬小麦品种(小偃6号和小偃22)主要生育期(拔节、孕穗、扬花、灌浆期)叶片叶绿素含量和荧光动力学参数的变化.结果显示,与背景CO2浓度相比,在不施氮条件下大气CO2浓度倍增处理的小麦叶片出现明显的光合下调现象,而施氮时变化不明显;同时,CO2浓度倍增后小麦各主要生育期叶片叶绿素含量均有不同程度地下降,荧光参数初始荧光(F0)值明显提高,最大荧光(Fm)、可变荧光(Fv)、最大光能转换效率(Fv/Fm)和PSⅡ潜在活性(Fv/F0)值均显著降低.施氮可提高冬小麦各个时期叶片叶绿素含量、Fm、Fv、和Fv/F0值,降低F0值;不施氮条件下,大气CO2浓度倍增对冬小麦各主要生育时期叶绿素含量和荧光参数的影响明显,而施氮后影响微弱.研究表明,大气CO2浓度升高对冬小麦光合速率、叶绿素含量和光系统Ⅱ(PSⅡ)的光合电子传递和潜在活性具有一定抑制作用,通过施氮可以有效地缓解其负面效应.     

用叶绿素a的瞬变荧光测定分析水分胁迫在光合电子传递中的作用部位

用瞬变荧光方法研究花生、小麦、高粱等植物,发现叶脱水最先引起荧光产量的升高,至最大值后才开始下降,这说明水分胁迫在叶绿体中的原初作用部位应在光系统Ⅱ的还原一侧。当脱水超过一定限度时,可能在光系统Ⅱ的氧化一侧造成损害,导致荧光产量的下降。     

Light-Induced Changes in the Fluorescence Yield of Chlorophyll a In Vivo: II. Chlorella pyrenoidosa

The long-term fluorescence induction in Chlorella pyrenoidosa consists of a fast rise of the fluorescence yield from the level S (of the first wave transient) to a maximum M, followed by slower decay to a terminal stationary level T. The maximum M is attained within 40 seconds from the onset of illumination while the decay to the terminal level T lasts for several minutes. The fluorescence rise (S → M) coincides with an increase in the rate of oxygen evolution, which, however, remains constant during the fluorescence decay (M → T). Poisons of photosynthesis 3, (3,4-dichlorophenyl)-1,1 dimethylurea (DCMU, o-phenathroline) inhibit the fluorescence induction, while uncouplers of photophosphorylation affect the fluorescence time course only when they function at an early stage of the coupling sequence e.g., carbonyl cyanide p-trifluoremethoxy phenylhydrazone, (FCCP, atabrin). Phosphorylation inhibitors affecting only the terminal esterification step (phlorizin) have little effect on the fluorescence kinetics. These results suggest that the fluorescence induction requires the operation of a phosphorylating electron transport and that it is possibly related to the light-induced structural changes which accompany photophosphorylation.     

Light-Induced Changes in the Fluorescence Yield of Chlorophyll a In Vivo: I. Anacystis nidulans

he fluorescence yield of chlorophyll a in dark adapted Anacystis nidulans undergoes a slow change with continuous illumination. After the completion of the initial fast transient, the fluorescence yield rises from the level S to a plateau M within a minute, declining only after prolonged illumination. Both normal and 1,1-dimethyl-3(3'4'-dichloro)-phenylurea (DCMU)-poisoned Anacystis are capable of these changes. In normal Anacystis, the slow increase in the fluorescence yield (S --> M) requires light absorbed in system II while light absorbed in system I is ineffective. In DCMU-poisoned Anacystis, however, these changes are also promoted by light absorbed in system I. Addition of carbonyl cyanide p-trifluoromethoxy phenylhydrazone (FCCP), a photophosphorylation uncoupler acting near the photosynthetic electron transport chain, abolishes the rise from S to M in normal but has no effect in the DCMU-poisoned system. Phlorizin, a phosphorylase inhibitor, has very little effect. These results suggest that the light-induced variation in the fluorescence yield is related to the conformational changes which accompany photophosphorylation. The fluorescence yield of the auxiliary pigment phycocyanin remains constant throughout the interval of the light-induced changes in the fluorescence yield of chlorophyll a. Consequently, the fluorescence spectrum of the alga is variable on continuous illumination.     

胡杨、灰叶胡杨光合及叶绿素荧光特性的比较研究

比较研究了两年生胡杨和灰叶胡杨叶片的光合及叶绿素荧光特性.结果表明:胡杨和灰叶胡杨均表现出净光合速率(Pn)日变化呈单峰曲线,只是在12:00时胡杨的Pn略微降低;气孔导度日变化均呈单峰型曲线;胞间CO2浓度日变化呈近“V”字型曲线.相同的试验条件下,胡杨的净光合速率、气孔导度高于灰叶胡杨,净光合速率与气孔导度峰值出现在上午10:00时;胡杨胞间CO2浓度低于灰叶胡杨,胞间CO2浓度最低值均出现在中午14:00时.经充分暗适应后的叶片叶绿素荧光参数初始荧光、PSⅡ原初光能转换效率和PSⅡ潜在活性均为胡杨显著大于灰叶胡杨.以太阳光为光化学光,测定的叶绿素荧光参数日变化显示,胡杨PSⅡ实际的光化学反应量子效率、非循环电子传递速率、光化学猝灭系数均大于灰叶胡杨,而非光化学猝灭系数却较灰叶胡杨小.胡杨与灰叶胡杨在光合与叶绿素荧光特性上的差异,是胡杨更能适应干旱荒漠区高光、高温与低相对空气湿度环境,从而表现出高净光合速率的部分生理学原因之一.     

Evaluation of the Effect of Light Intensity on the Measurement of the Photosynthetic Rate in Plankton Microalgae by the Chlorophyll Fluorescence Method

The use of relative variable fluorescence (RVF) of chlorophyll, as measured in the presence of Diuron, an inhibitor of electron transfer, for the estimation of the photosynthetic activity of plankton microalgae was analyzed under a wide range of light intensities in the PAR region. Oxygen evolution rates (estimated by the method of light and dark bottles and the amperometric method), RVF, and chlorophyll a concentration were measured in parallel in natural algal cenoses and microecosystems. When the previously used regression equation, in the form A = b(F/F _d)C _chl I, where A is O₂ evolution rate (g/(m³ h), F/F _d is RVF (relative units), C _chl is chlorophyll a concentration (mg/m³), and I is light intensity (W/m²), was verified in the PAR region, we observed a nonlinear dependence of the correction coefficient b on I, which can be described by the formula b = 6.227 × 10³I. This result agrees with the hypothesis that chlorophyll a fluorescence quenching comprises photochemical (qQ) and energy (qE) components. On the basis of the energy model, we determined the upper limit b _max = 0.003 for light intensity range I< 4.4 W/m² and the lower limit b _min = 0.0003 for I = 400 W/m².