内蒙古高原甘蒙锦鸡儿光合作用和水分代谢的生态适应性研究

 对分布于内蒙古高原和林格尔和阿拉善的甘蒙锦鸡儿（Caragana opulens）种群的光合特性和水分代谢特性进行了比较研究。结果发现：和林格尔种群的光补偿点（500 μmol proton·m-2·s-1以下）、光饱和点（1 200 μmol proton·m-2·s-1）、光合最适温度（26 ℃）均低于阿拉善种群（光补偿点为700～800 μmol proton·m-2·s－1之间;光饱和点为1 500 μmol proton·m－2·s－1;光合最适温度为28～29 ℃）,在低温、低光强下表现出更高的光合速率;和林格尔种群比阿拉善种群需要更高的空气湿度来维持其光合速率;和林格尔种群表现高蒸腾、高光合和低水分利用效率的代谢特点,阿拉善种群采取低蒸腾、低光合和高水分利用效率的节水对策。这些生理特性与它们分布区的光、温、湿条件相适应。阿拉善种群的净光合速率、蒸腾速率和光能利用效率远低于和林格尔种群,而水分利用效率和叶水分亏缺明显高于和林格尔种群。这主要是由于两地区水分状况差异引起的。     

利用调制荧光仪在线监测叶绿素荧光

介绍了利用便携式调制荧光仪PAM-2100在线监测叶绿素荧光的技术。该技术不影响植物的自然光合状态,司以在线监测Ft、F′m、Y、rETR、qP、qN或NPQ、PAR和叶温等指标。以凤眼莲为例进行了在线监测,每隔5min监测一次,共进行了225min的监测。结果表明叶绿索荧光参数的变化依赖于PAR的变化。Ft、rETR、qN和NPQ的变化与PAR的变化趋势一致,F′m、Y和qP的变化与PAR的变化相反。通过对风眼莲的在线监测,说明该技术是可靠的,具有简单、快速、灵敏等特点。随着新型调制荧光仪的出现,该技术可能在植物生态学领域得到广泛应用。     

Effect of zooplankton availability on the rates of photosynthesis, and tissue and skeletal growth in the scleractinian coral Stylophora pistillata

This work investigated the effect of light and feeding on tissue composition as well as on rates of photosynthesis and calcification in the zooxanthellae (zoox) scleractinian coral, Stylophora pistillata. Microcolonies were maintained at three different light levels (80, 200, 300 μmol m⁻² s⁻¹) and subjected to two feeding regimes (starved and fed) over 9 weeks. Corals were fed both natural plankton and Artemia salina nauplii four times a weeks and samplings were made after 2, 5, and 9 weeks. Results confirmed that feeding enhances coral growth rate and increases both the dark and light calcification rates. These rates were 50-75% higher in fed corals (FC; 60±20 and 200±40 nmol Ca²⁺ cm⁻² h⁻¹ for dark and light calcification, respectively) compared to control corals (CC; 30±9 and 124±23 nmol Ca²⁺ cm⁻² h⁻¹). The dark calcification rates, however, were four times lower than the rates of light calcification (independent of trophic status). After 5 weeks, chlorophyll a (chl-a) concentrations were four to seven times higher in fed corals (7-21 μg cm⁻²) than in control corals (2-5 μg cm⁻²). The amount of protein was also significantly higher in fed corals (2.11-2.50 mg cm⁻²) than in control corals (1.08-1.52 mg cm⁻²). Rates of photosynthesis in fed corals were 2-10 times higher (1.24±0.75 μmol O₂ h⁻¹ cm⁻²) than those measured in control corals (0.20±0.08 μmol O₂ h⁻¹ cm⁻²).     

Use of light and inorganic carbon acquisition by two morphotypes of Zostera noltii Hornem

The affinity for dissolved inorganic carbon (DIC) and the mechanisms to use HCO₃⁻ as a source of DIC for photosynthesis were investigated in two morphotypes of Zostera noltii Hornem. Both morphotypes were collected at Ria Formosa lagoon (Southern Portugal) at two different levels in the intertidal. Affinity for DIC at saturating photon fluence rate (PFR), estimated as photosynthetic conductance for CO₂ (g_p(CO2)), was reduced by 75% in the Z. noltii plants adapted to shade conditions (lower intertidal) in comparison to the sun morphotype (45×10⁻⁶ and 182×10⁻⁶ m s⁻¹, respectively), indicating that the plants acclimated to sun conditions (higher intertidal) had a higher capacity to use HCO₃⁻ as DIC source for photosynthesis. Since external carbonic anhydrase activity was negligible and a large inhibitory effect was produced by Tris buffer addition, this HCO₃⁻ use was attributed to the operation of H⁺ ATPases creating low pH zones in periplasmic space. The photosynthetic CO₂-flux supported for this mechanism was calculated to be 53 μmol O₂ m⁻² s⁻¹ in sun morphotype, about 80% out of maximum photosynthesis rate. In order to determine the possible photosynthetic energy cost of the HCO₃⁻ use, the effect of decreasing light on photosynthetic rates and g_p(CO2) was estimated. Photosynthetic conductance decreased in both morphotypes at non-saturating PFR. This dependence of g_p(CO2) on PFR indicated the existence of a positive interactive effect between DIC and PFR which was more pronounced in the shade morphotype since the ascending slope of O₂ evolution vs. PFR curves at limiting PFRs was reduced from 7.2 to 2.3 mmol O₂ mol photon⁻¹ at 4 and 0.5 mol m⁻³ of DIC, respectively.     

Use of photoacclimation in the design of a novel photobioreactor to achieve high yields in algal mass cultivation

The concept of a completely new and novel photobioreactor consisting of various compartments each with a specific light regime is described. This is in response to the debate and development which have taken place in recent years concerning photobioreactor design and closed systems. It is well known that algae can photo-acclimate to various light intensities. At the extremes, they can be high light (HL) or low light (LL) acclimated. Both HL and LL acclimated algae typically have very specific characteristics indicating the plasticity of the organisms, which have developed specific strategies during evolution to cope with continuous and dynamic light fields. Not only are these considerations important in photobioreactor design, but also for the production of certain biocompounds, whose synthesis has specific light requirements. In the continuous flow photobioreactor described here, algal cells acclimated to different light conditions together permit utilization of the entire light gradient found in an optically dense medium, such as in a high-density culture. Compared to a single compartment vertical flat-plate photobioreactor, the multicompartment reactor yielded a 37% higher productivity rate. This is a significant improvement in photobioreactor performance.     

鱼腥藻7120响应NaCl胁迫的光合特性

NaCl胁迫处理丝状蓝藻鱼腥藻7120后光合特性的变化表明;鱼腥藻7120的净光合放氧速率和呼吸速率随NaCl浓度的程式高而降低,且浓度低于0.4mol/LNaCl时的降幅比高于0.4mol/LNaCl时的降幅小,加入0.4%(W?V)的蔗糖后可提高盐胁迫后的鱼腥藻7120的光合放氧速率,吸收光谱测定结果表明盐胁迫没有改变鱼腥藻7120的光合色素组成,但导致藻胆蛋白的总含量降低,类胡萝卜素含量增加。低温荧光发射光谱测定表明盐胁迫后改变了光能在两个光系统之间的分配。由藻胆蛋白吸收的光能向光Ⅱ传递受阻。荧光动力学分析表明光系统Ⅱ的光化学效率随盐浓度的增加而降低。表现出与光合放氧速率的一致性。     

空气CO2增高条件下荔枝叶片光合作用和超氧自由基产率

研究结果表明,生长在77±5PaCO2分压下30d的荔枝幼树,其光合速率较大气CO2分压（39.3Pa）下的低23％,光下线粒体呼吸速率和不包含光下呼吸的CO2补偿点亦略有降低。空气CO2增高使叶片最大羧化速率（Vcmax）和最大电子传递速率（Jmax）降低,表明大气增高CO2分压下叶片的光I(PSI)能量水平较低,呈片超氧自由基产率亦降低39％,叶片感染荔枝霜疫霉病率则从生长在大气CO2分压下的1.8％增至9.5％,可能较低光合和呼吸代谢诱致较低的超氧自由基产率,而使叶片易受病害侵染。叶片受病害侵染后表现为超氧自由基的激增。在全球大气CO2分压增高趋势下须加强对荔枝霜疫霉病的控制。     

在水生与气生状态下石莼光合作用对光照和温度的响应

如何对付由于高潮时的水生状态与低潮时的气生状态高频率循环所导致的不同环境条件,是潮间带海藻的光合作用所面临的独特问题。对采自汕头沿岸的石莼(Ulva lactuca)在水生和气生不同状态下光合作用对光照和温度的响应特性进行了测定,以探讨这种常见的潮间带绿藻在潮汐循环背景下的光合特性。在气生状态下,光饱和净光合速率(Pmax)随气生暴露时间的变化模式可以很好地用三次方程进行描述,而温度影响方程的系数;当水分损失为15％时,石莼的Pmax增加至最大值,然后Pmax随进一步脱水而下降,在水分损失为80％时下降至0。温度对Pmax的影响在水生状态下比在气生状态下更大。气生状态下(充分水化)Pmax在10℃时显著小于水生状态下的值,而在30％时则相反。在10℃时,气生干出时间在6h以内,或在20％时,气生干出时间在2．2h以内,石莼的净碳固定量在气生状态下比在水生状态下要大;而在30％时,在气生状态下的净碳固定量比总是小于在水生状态下的净碳固定量。认为石莼在低潮气生状态下与在高潮水生状态下光合特性及净碳固定存在差异,但这种差异与环境温度及叶状体的水分状态有关。     

The Lhca antenna complexes of higher plants photosystem I

The Lhca antenna complexes of photosystem I (PSI) have been characterized by comparison of native and recombinant preparations. Eight Lhca polypeptides have been found to be all organized as dimers in the PSI-LHCI complex. The red emission fluorescence is associated not only with Lhca1-4 heterodimer, but also with dimers containing Lhca2 and/or Lhca3 complexes. Reconstitution of Lhca1 and Lhca4 monomers as well as of the Lhca1-4 dimer in vitro was obtained. The biochemical and spectroscopic features of these three complexes are reported. The monomers Lhca1 and Lhca4 bind 10 Chls each, while the Chl a/b ratio is lower in Lhca4 as compared to Lhca1. Three carotenoid binding sites have been found in Lhca1, while only two are present in Lhca4. Both complexes contain lutein and violaxanthin while β-carotene is selectively bound to the Lhca1-4 dimer in substoichiometric amounts upon dimerization. Spectral analysis revealed the presence of low energy absorption forms in Lhca1 previously thought to be exclusively associated with Lhca4. It is shown that the process of dimerization changes the spectroscopic properties of some chromophores and increases the amplitude of the red absorption tail of the complexes. The origin of these spectroscopic features is discussed.