铁胁迫诱导的赤潮异弯藻细胞生化组成变化

研究了铁胁迫对赤潮异弯藻细胞生化组成的影响．结果表明。铁胁迫下的细胞内所有色素浓度均降低,同富铁条件相比。铁胁迫下的细胞内叶绿素a浓度降低2倍多。叶绿素c也有相当程度的降低,因此,铁胁迫下的胞内叶绿素c与叶绿素a的比率变化不大．铁胁迫下的细胞内类胡萝卜素的含量降低了1．5倍,因此在铁胁迫下的细胞内类胡萝卜素相对于叶绿素a的比例升高。碳水化合物含量随培养基内铁浓度降低而下降,与铁丰富条件(10μmol·L-1)相比,受铁胁迫的细胞可溶蛋白电泳图谱中17kDa和55kDa附近的带明显增加,而在20kDa和35kDa附近的蛋白带降低     

Fe^3＋对雨生红球藻（Haematococcus pluvialis）生长及荧光特性的影响

为探求适宜雨生红球藻CG-06株生长的Fe^3＋浓度和Fe^3＋对藻细胞荧光特性的影响,以BBM为基础培养基,选用EDTA—FeNa（Ⅲ）为Fe^3＋源,设置0、1．79、8．95、17．9、35．8、71．6μmol·L^-1 6种Fe^3＋浓度梯度,实验测定藻的生长并分析不同Fe^3＋对藻细胞叶绿素荧光和77K低温荧光等的影响。结果表明：适合雨生红球藻CG-06株生长的Fe^3＋浓度为8．95μmol·L^-1,Fe^3＋浓度较高时,雨生红球藻的生长受到抑制,Fe^3＋浓度低于1．79μmol·L^-1将产生低铁限制。Walz—PAM测定数据显示,在铁不足或高铁抑制条件下,雨生红球藻光系统Ⅱ活性明显下降,开放态的反应中心数目减少,光合作用受到抑制。77K低温荧光光谱显示,在铁不足或高铁抑制条件下,710nm荧光峰降低,684nm和694nm荧光峰相对增强,说明能量在两个光系统分配上发生变化,能量更多的分配给光系统Ⅱ,限制了光系统Ⅰ的活性。在高铁抑制条件下,CP47蛋白荧光峰降低,CP43蛋白荧光峰增强,推测存在D1蛋白降解。     

鄂尔多斯高原碱湖的钝顶螺旋藻光合生理研究

鄂尔多斯高原碱湖的钝顶螺旋藻光合色素含量高低排列为藻胆素>叶绿素a>类胡萝卜素;各色素具有特定的吸收光谱,活体吸收光谱体现出了各色素的吸收;各色素的荧光发射主峰波长约长于活体的13￣35nm,相对荧光强度约是活体的11倍。其光合速率的日变化呈单峰曲线,13:00时达到最高;光补偿点为28￣30μmol.m-2.s-1;光饱和点为220￣235μmol.m-2.s-1;光合作用的最适温度为35℃。呼吸速率日变化随温度的升高呈缓慢上升的趋势。     

有机磷农药草甘膦异丙胺盐对赤潮异弯藻的毒物干扰效应

以我国典型赤潮藻赤潮异弯藻(Heterosigma akashiwo)为研究对象,设置了6个浓度梯度(0 mg·L^-1、0.001mg·L^-1、0.01 mg·L^-1、0.1 mg·L^-1、1 mg·L^-1和10 mg·L^-1)的草甘膦异丙胺盐处理,研究了草甘膦异丙胺盐暴露对赤潮异弯藻的生长、叶绿素a含量和可溶性蛋白含量等指标的影响.结果表明,草甘膦异丙胺盐对赤潮异弯藻具有明显的毒性效应,10 mg·L^-1浓度处理下,赤潮异弯藻细胞大量死亡,藻细胞密度以及叶绿素a、可溶性蛋白的含量显著降低(p<0.05);当草甘膦异丙胺盐浓度在0.001～1 mg·L^-1范围内,在培养的第3 d草甘膦异丙胺盐能够显著促进赤潮异弯藻的细胞密度增加,叶绿素a含量也明显高于对照组(p<0.05),表现出毒物刺激效应;在暴露实验的中后期(第7 d、第9 d和第11 d),赤潮异弯藻的各生长指标均与对照无显著差异,可能是随着培养时间的延长,农药的降解、生物体对农药的适应、进入细胞的农药减少等原因,藻细胞生理状态逐渐恢复到正常水平.     

假根羽藻外周天线色素分子间能量传递

假根羽藻外周天线捕光色素蛋白复合物(L ight-harvesting Comp lex II,LHC II)在不同聚集态的情况下,它所包含色素分子间的能量传递是不同的。采用荧光发射光谱和激发光谱技术对不同聚集态(单体、三聚体和寡聚体)的LHC II进行研究,发现三聚体中色素分子间的能量传递效率比较高,单体要小一些。520 nm激发下,类胡萝卜素分子向叶绿素a分子的能量传递效率:三聚体约为64%、单体约为56%;650 nm激发下,叶绿素b分子向叶绿素a分子的能量传递效率:三聚体约为89%、单体约为78%。寡聚体的能量传递要复杂些,从光谱分析出它包含两种不同吸收光谱特性的叶绿素b分子,吸收峰分别为480 nm和468 nm,其中蓝区吸收峰为480 nm的叶绿素b分子向发射685 nm荧光的叶绿素a分子的能量传递效率要小于75%。     

红树植物秋茄叶片水提物的抑藻效应

通过藻细胞密度的测定,探讨了不同浓度(0.5、1.0和2.0g·L-1)红树植物秋茄(Kandelia candel)新鲜叶片水提物对球形棕囊藻(Phaeocystis globosa)和赤潮异弯藻(Heterosigma akashiwo)的化感抑制效应,研究了高温处理对秋茄提取物化感作用的影响.结果表明:秋茄叶片提取物对两种赤潮藻均具有显著的化感抑制作用,不同浓度提取物化感作用强度不同;5 d内,浓度为2.0g·L-1秋茄叶片提取物对球形棕囊藻和赤潮异弯藻的最大抑制率分别为91.6％和77.0％;球形棕囊藻和赤潮异弯藻对红树植物秋茄提取物的敏感性不同,提取物对球形棕囊藻的抑制效果要优于赤潮异弯藻;经高温处理后,秋茄提取物抑藻效果显著降低(P＜0.05);秋茄叶片水提物影响藻细胞膜结构,使藻细胞体积增大、细胞破裂.     

螺旋藻原生质球的分离及其光合作用特性的研究

利用改进后的分离方法可获得大量有活性的钝顶螺旋藻 ( Spirulina platensis)原生质球。原生质球大小不等 ,直径在 2 .9～ 4 .6μm,原生质球表面有皱纹及小的孔洞 ,放氧速率为完整藻的 4 0 %。原生质球的室温吸收光谱表明其色素种类与完整细胞基本相同 ,都具有叶绿素 a、藻蓝蛋白、藻红蓝蛋白和类胡萝卜素。但原生质球中减少了藻蓝蛋白和类胡萝卜素的相对含量 ,而藻红蓝蛋白明显增多。螺旋藻的完整细胞与原生质球的 77K荧光发射光谱略有不同 :激发光为 4 36nm时 ,藻丝体和原生质球都具有 4个荧光发射峰 :F686、F696、F730和 F75 7,原生质球的 F75 7明显减弱 ;激发光为 5 80 nm时 ,藻丝体有 5个发射峰 :F64 0、F685、F693、F72 8和 F75 8,原生质球的 F75 8消失。原生球中 F72 8/F685、F64 0 /F685值增高 ,F693/F685值降低 ,光系统 的 F72 8与捕光色素系统的 F64 0的比值降低。上述结果表明 ,失去细胞壁可能抑制光系统 活性 ,在光系统 与 F695有关的核心天线色素系统受影响更大     

柱孢鱼腥藻(Anabaena cylindkica)营养细胞和异形胞叶绿素蛋白复合体的比较研究

比较了柱孢鱼腥藻(Anabaena cylindrica)营养细胞和异形胞类囊体膜叶绿素蛋白复合体的种类和性质。以SDS增溶营养细胞类囊体膜和不连续聚丙烯酰胺电泳分离得到4个P700叶绿素a蛋白复合体,分别为GPIa、CPIb、CPIc和CPI;和1个系统Ⅱ叶绿素蛋白复合体CPa。相对迁移率小的4个复合体含有P700,呼收光谱红区吸收峰为675nm,液氮低温荧光发射光谱有728nm荧光发射峰。CPIa和CPI的分量子分别为205 和105千道尔顿。未见诸文献的CPIb和CPIc复合体的分子量介于CPIa和CPI之间。相对迁移率较大的CPa有着吸收光谱红区672nm吸收峰,液氮低温荧光发射光谱有687nm荧光发射峰,分子量为56千道尔顿。同时化学氧化还原差示光谱不表现P700吸收降低。柱孢鱼腥藻异形胞类囊体膜经SDS增溶和电泳分离得到2个系统Ⅰ叶绿素蛋白复合体,它们的吸收光谱特性和分子量大小相近于营养细胞分离的CPIa和CPI复合体。异形胞类囊体膜缺少系统Ⅱ叶绿索蛋白复合体。     

满江红鱼腥藻(Anabaena azollae)和柱孢鱼腥藻(A.cylindrica)营养细胞和异形胞色素的种类

满江红鱼腥藻和柱孢鱼腥藻营养细胞和异形胞的液氮低温吸收光谱表明两种细胞含有叶绿素a、藻蓝素和β-胡萝卜素。液氮低温荧光发射光谱表明:柱孢鱼腥藻营养细胞存在藻蓝素、别藻蓝素和两个光系统的叶绿素a,柱孢鱼腥藻异形胞存在藻蓝素和系统Ⅰ叶绿素a。荧光发射光谱的685nm荧光发射仅为微弱突起。满江红鱼腥藻异形胞亦存在藻蓝素和系统Ⅰ叶绿素a,缺少系统Ⅱ叶绿素a。推断满江红鱼腥藻和桩孢鱼腥藻营养细胞分化为异形胞时,伴随光系统Ⅱ的改组。系统Ⅱ叶绿素a消退和藻胆色素含量显著减少。     

满江红鱼腥藻（Anabaena azollae）和柱孢鱼腥藻(A. cylindrica)营养细胞和异形胞色素的种类

满江红鱼腥藻和柱孢鱼腥藻营养细胞和异形胞的液氮低温吸收光谱表明两种细胞含有叶绿素a、藻蓝素和β-胡萝卜素。液氮低温荧光发射光谱表明:柱孢鱼腥藻营养细胞存在藻蓝素、别藻蓝素和两个光系统的叶绿素a,柱孢鱼腥藻异形胞存在藻蓝素和系统Ⅰ叶绿素a。荧光发射光谱的685nm荧光发射仅为微弱突起。满江红鱼腥藻异形胞亦存在藻蓝素和系统Ⅰ叶绿素a,缺少系统Ⅱ叶绿素a。推断满江红鱼腥藻和桩孢鱼腥藻营养细胞分化为异形胞时,伴随光系统Ⅱ的改组。系统Ⅱ叶绿素a消退和藻胆色素含量显著减少。     

Some physiological and biochemical changes in marine eukaryotic red tide alga Heterosigma akashiwo during the alleviation from iron limitation

Some physiological and biochemical changes in the marine eukaryotic red tide alga Heterosigma akashiwo (Hada) were investigated during the alleviation from iron limitation. Chlorophyll a/carotenoid ratio increases as a result of iron alleviation. In vivo absorption spectra of iron-limited cells showed a chlorophyll (Chl) absorption peak at 630 nm, 2 nm blue-shifted from the normal position. Low-temperature fluorescence emission spectra of the cells have one prominent Chl emission peak at 685 nm. The cells showed a decrease in fluorescence yield from 685 nm band during alleviation from iron limitation. Low-temperature fluorescence excitation spectra and room-temperature fluorescence spectra indicated an efficient excitation energy transfer in the cells alleviated from iron limitation. Photosynthetic efficiency and carbohydrate content per cell increased after alleviation from iron limitation. Total protein decreased in iron-limited cells, while iron deficiency induced the appearance of specific soluble proteins (17 and 55 kDa).     

Iron Deficiency in the Blue-Green Alga Anacystis nidulans: Fluorescence and Absorption Spectra Recorded at 77°K

Low-temperature (77°K) fluorescence and absorption spectra have been determined for whole cells and photosystem I particles of Anacystis nidulans grown in iron-supplied or iron-deficient inorganic media. Iron deficiency induces a decrease of F720 relative to F685 and F695 in the fluorescence spectra of both whole cells and photosystem I particles. This change is correlated to a reduction of preferentially the long wavelength absorbing fraction of chlorophyll a. The relative fluorescence intensity at 755 nm is increased by iron deficiency. No significant effects of culture-age are found in the ratio between the three fluorescence bands (F685: F695: F720) of iron-supplied A. nidulans.     

Fluorescence emission spectra of chloroplasts and subchloroplast preparations at low temperature.

A study was made of the chlorophyll fluorescence spectra between 100 and 4.2 K of chloroplasts of various species of higher plants (wild strains and chlorophyll b mutants) and of subchloroplast particles enriched in Photosystem I or II. The chloroplast spectra showed the well known emission bands at about 685, 695 and 715--740 nm; the System I and II particles showed bands at about 675, 695 and 720 nm and near 685 nm, respectively. The effect of temperature lowering was similar for chloroplasts and subchloroplast particles; for the long wave bands an increase in intensity occurred mainly between 100 and 50 K, whereas the bands near 685 nm showed a considerable increase in the region of 50--4.2 K. In addition to this we observed an emission band near 680 nm in chloroplasts, the amplitude of which was less dependent on temperature. The band was missing in barley mutant no. 2, which lacks the light-harvesting chlorophyll a/b-protein complex. At 4.7 K the spectra of the variable fluorescence (Fv) consisted mainly of the emission bands near 685 and 695 nm, and showed only little far-red emission and no contribution of the band at 680 nm. From these and other data it is concluded that the emission at 680 nm is due to the light-harvesting complex, and that the bands at 685 and 695 nm are emitted by the System II pigment-protein complex. At 4.2 K, energy transfer from System II to the light-harvesting complex is blocked, but not from the light-harvesting to the System I and System II complexes. The fluorescence yield of the chlorophyll species emitting at 685 nm appears to be directly modulated by the trapping state of the reaction center.     

Membrane Development in the Cyanobacterium, Anacystis nidulans, during Recovery from Iron Starvation

Deprivation of iron from the growth medium results in physiological as well as structural changes in the unicellular cyanobacterium Anacystis nidulans R2. Important among these changes are alterations in the composition and function of the photosynthetic membranes. Room-temperature absorption spectra of iron-starved cyanobacterial cells show a chlorophyll absorption peak at 672 nanometers, 7 nanometers blue-shifted from its normal position at 679 nanometers. Iron-starved cells have decreased amounts of chlorophyll and phycobilins. Their fluorescence spectra (77K) have one prominent chlorophyll emission peak at 684 nanometers as compared to three peaks at 687, 696, and 717 nanometers from normal cells. Chlorophyll-protein analysis of iron-deprived cells indicated the absence of high molecular weight bands. Addition of iron to iron-starved cells induced a restoration process in which new components were initially synthesized and integrated into preexisting membranes; at later times, new membranes were assembled and cell division commenced. Synthesis of chlorophyll and phycocyanins started almost immediately after the addition of iron. The absorption peak slowly returned to its normal wavelength within 24 to 28 hours. The fluorescence emission spectrum at 77K changed over a period of 14 to 24 hours during which the 696- and 717-nanometer peaks grew to their normal levels, and the 684 nanometer peak moved to 687 nanometers and its relative intensity decreased to its normal level. Analysis of chlorophyll-protein complexes on polyacrylamide gels showed that high molecular weight chlorophyll-protein bands were formed during this time, and that low molecular weight bands (related to photosystem II) disappeared. The origin of the fluorescence emission at 687 and 696 nanometers is discussed in relation to the specific chlorophyll-protein complexes formed during iron reconstitution.     

Fluorescence emission spectra of chloroplasts and subchloroplast preparations at low temperature

A study was made of the chlorophyll fluorescence spectra between 100 and 4.2 K of chloroplasts of various species of higher plants (wild strains and chlorophyll b mutants) and of subchloroplast particles enriched in Photosystem I or II. The chloroplast spectra showed the well known emission bands at about 685, 695 and 715–740 nm; the System I and II particles showed bands at about 675, 695 and 720 nm and near 685 nm, respectively. The effect of temperature lowering was similar for chloroplasts and subchloroplast particles; for the long wave bands an increase in intensity occurred mainly between 100 and 50 K, whereas the bands near 685 nm showed a considerable increase in the region of 50-4.2 K. In addition to this we observed an emission band near 680 nm in chloroplasts, the amplitude of which was less dependent on temperature. The band was missing in barley mutant no. 2, which lacks the lightharvesting chlorophyll a/b-protein complex. At 4.7 K the spectra of the variable fluorescence (F_v) consisted mainly of the emission bands near 685 and 695 nm, and showed only little far-red emission and no contribution of the band at 680 nm.From these and other data it is concluded that the emission at 680 nm is due to the light-harvesting complex, and that the bands at 685 and 695 nm are emitted by the System II pigment-protein complex. At 4.2 K, energy transfer from System II to the light-harvesting complex is blocked, but not from the light-harvesting to the System I and System II complexes. The fluorescence yield of the chlorophyll species emittting at 685 nm appears to be directly modulated by the trapping state of the reaction center.     

Dependence of fluorescence spectra of chloroplasts from the activity of photosystem 2]

By means of high sensitive spectrofluorometer the fluorescence spectra have been measured of normal chloroplasts and those with blocked photosystem 2 activity due to photoinhibition or treatment with 0.6 M tris-buffer. At room temperature fluorescence spectra of inactivated chloroplasts are similar to the spectrum of normal chloroplasts measured at low light intensity. Under excitation by intense light a decrease of intensity at 685 nm is appeared (about 3-4 times) in the fluorescence spectra of inactivated chloroplasts as compared to the spectrum of normal chloroplasts. The sharp intensity decrease of maxima at 685 and 695 nm (3-4 times) and small decrease at 680 and 730 nm (by 30-50%) are observed in low temperature fluorescence spectra of inactivated chloroplasts. Thus, the damage of photosystem 2 reaction centres is not accompanied by the preferential decrease of the only fluorescence band. The similarity of fluorescence difference spectra of chloroplasts distinguished by the state of photosystem 2 reaction centre, and the complex structure of difference spectra indicate that the variable fluorescence of chloroplasts during the induction is due to the emission of bulk chlorophyll alpha of the photosystem 2.     

Photosynthetic vesicles with bound phycobilisomes from Anabaena variabilis.

Photosynthetically active vesicles with attached phycobilisomes from Anabaena variabilis, were isolated and shown to transfer excitation energy from phycobiliproteins to F696 chlorophyll (Photosystem II). The best results were obtained when cells were disrupted in a sucrose/phosphate/citrate mixture (0.3 : 0.5 : 0.3 M, respectively) containing 1.5% serum albumin. The vesicles showed a phycocyanin/chlorophyll ratio essentially identical to that of whole cells, and oxygen evolution rates of 250 mumol O2/h per mg chlorophyll (with 4 mM ferricyanide added as oxidant), whereas whole cells had rates of up to 450. Excitation of the vesicles by 600 nm light produced fluorescence peaks (-196 degrees C) at 644, 662, 685, 695, and 730 nm. On aging of the vesicles, or upon dilution, the fluorescence yield of the 695 nm emission peak gradually decreased with an accompanying increase and final predominant peak at 685 nm. This shift was accompanied by a decrease in the quantum efficiency of Photosystem II activity from an initial 0.05 to as low as 0.01 mol O2/einstein (605 nm), with a lesser change in the Vmax values. The decrease in the quantum efficiency is mainly attributed to excitation uncoupling between phycobilisomes and Photosystem II. It is concluded that the F685 nm emission peak, often exclusively attributed to Photosystem II chlorophyll, arises from more than one component with phycobilisome emission being a major contributor. Vesicles from which phycobilisomes had been removed, as verified by electron microscopy and spectroscopy, had an almost negligible emission at 685 nm.     

Interaction of phycobilisomes with photosystem II dimers and photosystem I monomers and trimers in the cyanobacterium Spirulina platensis.

Distribution of phycobilisomes between photosystem I (PSI) and photosystem II (PSII) complexes in the cyanobacterium Spirulina platensis has been studied by analysis of the action spectra of H2 and O2 photoevolution and by analysis of the 77 K fluorescence excitation and emission spectra of the photosystems. PSI monomers and trimers were spectrally discriminated in the cell by the unique 760 nm low-temperature fluorescence, emitted by the trimers under reductive conditions. The phycobilisome-specific 625 nm peak was observed in the action spectra of both PSI and PSII, as well as in the 77 K fluorescence excitation spectra for chlorophyll emission at 695 nm (PSII), 730 nm (PSI monomers), and 760 nm (PSI trimers). The contributions of phycobilisomes to the absorption, action, and excitation spectra were derived from the in vivo absorption coefficients of phycobiliproteins and of chlorophyll. Analyzing the sum of PSI and PSII action spectra against the absorption spectrum and estimating the P700:P680 reaction center ratio of 5.7 in Spirulina, we calculated that PSII contained only 5% of the total chlorophyll, while PSI carried the greatest part, about 95%. Quantitative analysis of the obtained data showed that about 20% of phycobilisomes in Spirulina cells are bound to PSII, while 60% of phycobilisomes transfer the energy to PSI trimers, and the remaining 20% are associated with PSI monomers. A relevant model of organization of phycobilisomes and chlorophyll pigment-protein complexes in Spirulina is proposed. It is suggested that phycobilisomes are connected with PSII dimers, PSI trimers, and coupled PSI monomers.     

Spectral, Physical, and Electron Transport Activities in the Photosynthetic Apparatus of Mesophyll Cells and Bundle Sheath Cells of Digitaria sanguinalis (L.) Scop

Isolated mesophyll cells and bundle sheath cells of Digitaria sanguinalis were used to study the light-absorbing pigments and electron transport reactions of a plant which possesses the C₄-dicarboxylic acid cycle of photosynthesis. Absorption spectra and chlorophyll determinations are presented showing that mesophyll cells have a chlorophyll a-b ratio of about 3.0 and bundle sheath cells have a chlorophyll a-b ratio of about 4.5. The absorption spectrum of bundle sheath cells has a greater absorption in the 700 nm region at liquid nitrogen temperature, and there is a relatively greater amount of a pigment absorbing at 670 nm in the bundle sheath cells compared to the mesophyll cells. Fluorescence emission spectra, at liquid nitrogen temperature, of mesophyll cells have a fluorescence 730 nm-685 nm ratio of about 0.82 and bundle sheath cells have a ratio of about 2.84. The reversible light-induced absorption change in the region of P₇₀₀ absorption is similar in both cell types but bundle sheath cells exhibit about twice as much total P₇₀₀ change as mesophyll cells on a total chlorophyll basis. The delayed light emission of bundle sheath cells is about one-half that of mesophyll cells. Both mesophyll cells and bundle sheath cells evolve oxygen in the presence of Hill oxidants with the mesophyll cells exhibiting about twice the activity of bundle sheath cells, and both activities are inhibited by 1 μM 3-(3,4-dichlorophenyl)-1, 1-dimethylurea. Ferredoxin nicotinamide adenine dinucleotide phosphate reductase is present in both cells although it is about 3- or 4-fold higher in mesophyll cells than in bundle sheath cells. Glyceraldehyde 3-P dehydrogenases, both nicotinamide adenine dinucleotide and nicotinamide adenine dinucleotide phosphate, are equally distributed in the two cell types on a chlorophyll basis. Malic enzyme is localized in the bundle sheath cells.