沉水植物浸提液组分对三种常见附植藻类生长的影响

采用长江中下游湖泊典型沉水植物乡土种轮叶黑藻(Hydrilla verticillata)、穗状狐尾藻(Myriophyllum spicatum)和外来种伊乐藻(Elodea nuttallii)、水盾草(Cabomba caroliniana)叶片浸提液的组分:N-苯基-2-萘胺(4种沉水植物均有)、苯丙酮(伊乐藻特有)和苯并呋喃(水盾草特有),研究不同物质种类及浓度对3种附植藻类:普通小球藻(Chlorella vulgaris)、斜生栅藻(Scenedesmus obliqnus)和四尾栅藻(S.quadricanda)的相对生长率、藻细胞浓度、叶绿素含量等生长指标的影响。结果表明:3种物质均显著降低斜生栅藻和普通小球藻的细胞浓度以及叶绿素含量,对四尾栅藻生长的抑制较弱。3种附植藻类生长指标对不同物质浓度及处理时间的响应存在显著差异,呈现低浓度促进、高浓度抑制现象,随时间推移藻类显示出明显的生长趋势。物质作用效果:苯丙酮苯并呋喃N-苯基-2-萘胺,表明外来种沉水植物叶片浸提液中特有物质具有较强的抑藻效应。     

柳树叶浸提液对蛋白核小球藻的化感作用

通过对蛋白核小球藻进行细胞密度的测定,分析了不同浓度的柳树(Salix babylonica)叶浸提液对蛋白核小球藻(Chlorella pyrenoidosa)生长和细胞形态的影响。结果表明：柳树叶浸提液对蛋白核小球藻具有化感作用,不同浓度的浸提液化感作用强度不同;作用96 h的半效应浓度(EC₅₀,_{96 h}值)为11.82 g·L^-1,较低浓度(10和20 g·L^-1)浸提液对蛋白核小球藻表现出先抑制后促进的作用特性,而较高浓度（30 g·L^-1）浸提液则始终表现出抑制效果;10、20和30 g·L^-1浸提液对蛋白核小球藻的最大抑制率分别为37.5%、39.3%和56.5%;柳树叶浸提液作用下,部分蛋白核小球藻细胞平均颗粒体积增大,颜色变透明,膨胀后溶解;低浓度浸提液处理组少数细胞聚集在一起,高浓度浸提液处理组细胞大量聚集,形成多细胞群体,多数沉于瓶底,沉降性能增强。     

白色LED复合光谱对4种淡水微藻的影响

利用光效高、耗能小的LED光谱作为光源培养微藻能够降低微藻培养的成本,促进微藻培养实现工业化。比较了6种已市场化的,具有不同光强、不同光谱组成的白色LED复合光谱(1号,光强2 162 lx;2号,光强2 227lx;3号,光强2 794 lx;4号,光强4 587 lx;5号,光强5 356 lx;6号,光强6 244 lx)对4种淡水微藻生长情况和叶绿素含量的影响。结果发现:四尾栅藻在5号光源下,有最大生物质质量浓度和比生长速率,分别为2.89 g/L和0.32g/(L·d)(以细胞干质量计);钝顶螺旋藻在4号光源下,有最大生物质质量浓度和比生长速率,分别为5.05 g/L和0.33 g/(L·d);布朗葡萄藻在6号光源下,有最大生物质质量浓度和比生长速率,分别为1.22 g/L和0.25g/(L·d);而集胞藻在光强较小的光源下生长较好,当光强为2 162 lx时,生物质质量浓度和比生长速率分别为3.05 g/L和0.22 g/(L·d)。在光强较低的情况下,光质的红蓝比对四尾栅藻和布朗葡萄藻的生长没有显著影响(p0.05);与蓝光相比,红光更利于集胞藻和钝顶螺旋藻的生长,分别在红蓝比(R/B)为11.7的1号光源和4号光源下有最大藻细胞密度3.05和5.05 g/L。四尾栅藻、钝顶螺旋藻和布朗葡萄藻的单位水体内叶绿素含量与比生长速率成正比,而单位质量干藻细胞内的叶绿素含量随光强的增大而有所降低。     

水芹水浸提液对斜生栅藻的化感效应研究

采用栅藻在不同浓度的水芹水浸提液中纯培养的方法,研究了水芹水浸提液对斜生栅藻细胞数、叶绿素含量及藻细胞超微结构的影响。结果显示,10 g·L^-1水芹水浸提液对斜生栅藻的生长和叶绿素含量的增加具有明显的促进效应;20 g·L^-1水芹水浸提液对藻细胞数和叶绿素含量的增加持续到第3 d,3 d后出现显著的抑制效应;高浓度（30~50 g·L^-1）水芹水浸提液对藻细胞数和叶绿素含量的明显抑制在第2 d始现,随时间延长而加剧,并具有浓度效应;40 g·L^-1水芹水浸提液处理后,斜生栅藻细胞壁断裂甚至消失,细胞中叶绿体片层肿胀甚至解体,核膜破裂,核质外渗。水芹水浸提液对斜生栅藻具有化感效应,低浓度促进生长,高浓度抑制。     

表面活性剂CTAC和STAB对四尾栅藻的毒性效应

采用室内培养法考察了十六烷基三甲基氯化铵(CTAC)和十八烷基三甲基溴化铵(STAB)对四尾栅藻(Scenedesmus quadricauda)的生长状况、蛋白质含量、叶绿素含量、脂质过氧化丙二醛(MDA)含量以及超氧化歧化酶(SOD)活性的影响,分析了CTAC和STAB对四尾栅藻的毒性机理。结果表明:CTAC和STAB对四尾栅藻的生长抑制效应受浓度和时间的影响显著,STAB对四尾栅藻的毒性大于CTAC,且CTAC和STAB作用4d内,藻种蛋白质、叶绿素含量以及SOD酶活性均先上升后下降,MDA含量下降。根据5种指标变化与CTAC(或STAB)之间呈现的浓度-效应关系和时间-效应关系推测,表面活性剂对藻细胞的最初攻击点是通过改变其细胞膜膜脂分子的水溶性,破坏四尾栅藻的细胞膜;表面活性剂通过刺激细胞产生活性氧自由基引起脂质及其他生物大分子的氧化损伤可能是其对四尾栅藻产生毒害效应的主要机制。     

咪唑离子液体对四尾栅藻的毒性

按照藻类生长抑制试验标准方法,以四尾栅藻为受试生物,研究了离子液体1-丁基-3-甲基咪唑氯盐([C4mim][Cl])和1-丁基-3-甲基咪唑四氟硼酸盐([C4mim][BF4])对四尾栅藻的影响,测定了半数有效浓度(EC50)和叶绿素含量。结果表明:[C4mim][Cl]和[C4mim][BF4]对四尾栅藻的生长和叶绿素的产生均具有抑制作用,毒性效应随着浓度的增大和培养时间的增长而增加,96 h的EC50分别为57.8和38.8 mg/L。离子液体质量浓度为200mg/L时,四尾栅藻的叶绿素总量仅为对照组的32%和26%。此结果可以说明离子液体对生态系统存在潜在的负面效应。     

不同藻密度下布洛芬浓度对萼花臂尾轮虫生命表统计学参数的影响

在不同斜生栅藻(Scenedesmus obliquus)密度(1.0×10~6、2.0×10~6个细胞/m L和4.0×10~6个细胞/m L)下,研究了不同浓度的(0、1、10、100、1000μg/L和5000μg/L)布洛芬对萼花臂尾轮虫(Brachionus calyciflorus)生命表统计学参数的影响。结果表明,与各藻密度下的对照组相比,当藻密度为1.0×106个细胞/m L时,100—5000μg/L布洛芬处理组中轮虫的生命期望和平均寿命显著缩短,100μg/L布洛芬处理组中轮虫的世代时间显著缩短,1.0μg/L布洛芬处理组中轮虫的净生殖率显著提高,10—5000μg/L布洛芬处理组中轮虫的后代混交率显著提高。当藻密度为2.0×10~6个细胞/mL时,10—5000μg/L布洛芬处理组中轮虫的生命期望和平均寿命显著缩短,1000μg/L和5000μg/L布洛芬处理组中轮虫的世代时间显著缩短,1、10、1000μg/L和5000μg/L布洛芬处理组中轮虫的种群内禀增长率显著提高,1μg/L和1000μg/L布洛芬处理组中轮虫的后代混交率显著提高。当藻密度为4.0×10~6个细胞/mL时,10—5000μg/L布洛芬处理组中轮虫的生命期望、平均寿命和世代时间显著缩短。藻密度对轮虫的世代时间、净生殖率和种群内禀增长率有显著性影响(P0.05),布洛芬浓度对轮虫的生命期望、平均寿命、世代时间、净生殖率和种群内禀增长率有显著性影响(P0.05),藻密度和布洛芬浓度的交互作用对轮虫的生命期望、平均寿命和后代混交率有显著性影响(P0.05)。在实验设置的布洛芬浓度范围内,2.0×10~6个细胞/m L藻密度下,轮虫的生命期望、平均寿命和世代时间与布洛芬浓度之间均具有显著的剂量—效应关系(P0.05); 4.0×10~6个细胞/m L藻密度下,轮虫的生命期望、平均寿命和净生殖率与布洛芬浓度之间均具有显著的剂量—效应关系(P0.05)。     

草甘膦对可食用蓝藻葛仙米生长和生理的影响

葛仙米（N．sphaeroides）的产量和产地面积逐年减少,这可能与当地广泛使用除草剂草甘膦有关。为此,本文测定了不同浓度（0．15、0．30、0．45、0．6mmol／L）的草甘膦处理的葛仙米的颗粒大小、干重、叶绿素荧光、叶绿素浓度。所有测量参数与浓度和时间显著相关：0．15mmol／L处理组的颗粒直径较对照组小15％（2d后）;叶绿素a浓度和最大量子产率（Fv／Fm）在最高浓度组（0．6mmol／L）4d后开始受到影响;第8天,相对生长速率（以干重计算,大于0．15mmol／L）、光合作用活性（大于0．3mm01／L）均受显著抑制,其中0．15mmol／L处理组相对生长下降60％,而更高浓度处理组出现负生长,0．6mm01／L组藻体漂白死亡。结合实验结果,文章讨论了草甘膦的毒性机理及其对葛仙米（N．sphaeroides）的潜在影响。     

药用植物浸提液抑制蛋白核小球藻生长的化感效应

研究了11种药用植物浸提液对水华藻种蛋白核小球藻的影响,结果显示:黄连、重楼、贯众、防己4种药用植物的浸提液均有抑藻效应。当药用植物浸提液的相对浓度为1g/L处理时,其半抑制效应时间LT50的排序为:防己重楼黄连贯众。进一步研究防己的相对浓度梯度抑藻效应,结果表明:在相对浓度为2g/L时,实验3d后的藻细胞几乎全部死亡;防己的抑藻效应受贮藏时间和贮藏温度的影响不显著。在所研究的药用植物中,防己的抑藻效果最好,在抑藻方面有较大应用前景,其它3种药用植物对轻度藻类爆发的控制也有潜在应用价值。     

温度和氮磷浓度对平裂藻和栅藻生长及竞争的影响

为了解温度及氮磷浓度对平裂藻和栅藻生长及竞争的影响,分别在18、25和35℃条件下,以BG11培养基为基础,设置了不同的氮磷浓度组,进行了2种藻的单独培养试验和混合培养试验,结果表明:在纯培养条件下,低营养浓度组(磷浓度分别为0.1和0.5 mg/L)平裂藻在3种温度下基本停止生长,高营养盐浓度组(磷浓度分别为1.0和1.5 mg/L)除18℃1.0 mg/L组停止生长外,其余均能正常生长增殖,且细胞最大密度表现为25℃ 18℃ 35℃, 1.5和1.0 mg/L浓度组细胞生长差异不显著。栅藻在纯培养条件下,细胞密度总体表现为随着营养盐浓度升高而增加的趋势,细胞最大密度表现为18℃ 25℃ 35℃。在混合培养试验中,除35℃、1.5 mg/L组平裂藻对栅藻的竞争抑制参数大于栅藻对平裂藻的竞争抑制参数外,其余试验组均表现为栅藻受平裂藻影响较小。在混合培养体系中, 0.1 mg/L组平裂藻仍基本停止生长, 0.5 mg/L组受栅藻的刺激作用,生长优于纯培养体系。1.0和1.5 mg/L组均受栅藻的抑制作用,且浓度越高抑制作用越强。       

藻类活性物质对紫草细胞生长和色素形成的影响

本文研究了螺旋藻、栅列藻和织线藻的水提物对新疆紫草和硬紫草细胞生长和色素形成的作用。结果表明不同种类的藻的提取物对不同紫草细胞作用呈现差异。在生长阶段,对新疆紫草,上述3种藻的低浓度提取物促进生长但作用不大,高浓度的螺旋藻和栅列藻提取物强烈抑制生长;对硬紫草,各种藻提取液的所有浓度处理均有促生长作用。在色素形成阶段,连续用高浓度织线藻提取物处理可以加速新疆紫草色素形成,同时提高色素含量。低浓度的织线藻提取液处理能提高硬紫草色素含量。栅列藻的水提物对两种紫草的色素形成均起抑制作用。螺旋藻水提物的适当浓度可加速两种紫草的色素形成。B_5培养基中加高浓度织线藻水提物,可抑制新疆紫草生长阶段的色素形成。     

栅藻对水环境中镍的累积效应与机理分析

对不同Scenedesmus品种的藻细胞从含镍水溶液 (10mg/L)中累积金属镍的能力进行了分析 ,结果表明 :藻细胞对镍的生物累积量表现出明显的品种差异性。ScenedesmusquadricaudaFACHB 4 4和ScenedesmusquadricaudaFACHB 5 0 6表现出很强的累积能力 (累积量达到 5～ 6mgNi /g干重 ) ,而Scenedesmussp .FACHB 4 16和Scenedesmussp .FACHB 4 89在相同条件对金属镍累积量要少得多 (1～ 1.5mgNi /g干重 )。这种差异可能与不同品种藻细胞间的形态结构和生理特性是相关的。对S .quadricaudaFACHB 4 4重金属抗性和累积能力进一步的分析表明 ,S .quadricaudaFACHB 4 4用于含镍重金属废水处理是非常有效的 ,在高浓度 (10 0mg/L)的镍溶液中 ,藻细胞的最大累积量能达到 (2 6 .7mgNi/g干重 )。对该藻细胞镍累积动力学分析发现 :藻细胞对镍的生物累积包括一个快速的被动吸附过程 (5min ,结合 70 %的镍 )和一个缓慢的耗能累积过程 (2～ 3h时间内的累积量占总量的 2 0 %～ 30 % )。与其他藻类相比 ,S .quadricaudaFACHB 4 4对水溶液中镍的耗能累积量明显高于其他藻类。透射电子显微镜(TEM)和X射线能谱 (EDX)分析结果均表明 ,藻细胞耗能累积的镍主要集中在原生质体中 ,尤以淀粉粒和染色质中为多。     

Effects of copper, lead and zinc on phytoplankton growth

Impact of Cu, Pb and Zn on the growth of Closterium acerosum, Pediastrum simplex, Chlorella vulgaris and Scenedesmus quadricauda was studied in vitro. At concentration 0.1 g m-3 these metals were not toxic, however, at concentration 10.0 g m-3 the growth of phytoplankton was inhibited. Cu was the most toxic followed by Pb and Zn. S. quadricauda expressed highest tolerance to these metals, and least tolerance was exhibited by C. acerosum. This revised version was published online in July 2006 with corrections to the Cover Date.     

Quantified small-scale turbulence inhibits the growth of a green alga

1. Laboratory experiments were conducted to elucidate the effect of small-scale turbulent fluid motion on the growth of laboratory cultures of the freshwater algae Scenedesmus quadricauda . Turbulent flow was generated using an oscillating-grid apparatus. The experiments were performed under the range of fluid flow conditions similar to those occurring in nature. The only growth limiting factor was the effect of small-scale fluid motion; all other environmental factors, such as light, temperature and nutrients, were kept constant.
2. Growth of Scenedesmus quadricauda , measured in terms of chlorophyll a concentration, was inhibited when the level of turbulence in the water column was increased. Algal growth was maximum in a quiescent fluid. The inhibitory effect of fluid motion was observed independently of flow regime (laminar, transitional, turbulent) in the water column.
3. Cell destruction and aggregation of dead and living cells of algae were observed in a turbulent flow. High shear rates, estimated from the dissipation of turbulent kinetic energy, caused the cell destruction, algal collision and agglomeration of algae. Data on Scenedesmus responses to small-scale fluid motion will enhance and broaden our ability to develop predictive multispecies models for freshwater phytoplankton communities.     

Points of commitment to reproductive events as a tool for analysis of the cell cycle in synchronous cultures of algae

Methods for determining the points of commitment for cell division are described for species of green algae dividing by multiple fission, both forming coenobia (Scenedesmus quadricauda) and releasing single daughter cells (Chlamydomonas eugametos, Scenedesmus armatus). The timing of commitment points was followed in detail in synchronous cultures of S. quadricauda grown under various light intensities, illumination regimes, and temperatures. The pre-commitment periods were rate limiting, while the post-commitment periods remained more or less constant under various light intensity. Temperature, on the other hand, affected both periods in a similar manner and they were prolonged with decreasing temperature.     

DNA damage during G2 phase does not affect cell cycle progression of the green alga Scenedesmus quadricauda

DNA damage is a threat to genomic integrity in all living organisms. Plants and green algae are particularly susceptible to DNA damage especially that caused by UV light, due to their light dependency for photosynthesis. For survival of a plant, and other eukaryotic cells, it is essential for an organism to continuously check the integrity of its genetic material and, when damaged, to repair it immediately. Cells therefore utilize a DNA damage response pathway that is responsible for sensing, reacting to and repairing damaged DNA. We have studied the effect of 5-fluorodeoxyuridine, zeocin, caffeine and combinations of these on the cell cycle of the green alga Scenedesmus quadricauda. The cells delayed S phase and underwent a permanent G2 phase block if DNA metabolism was affected prior to S phase; the G2 phase block imposed by zeocin was partially abolished by caffeine. No cell cycle block was observed if the treatment with zeocin occurred in G2 phase and the cells divided normally. CDKA and CDKB kinases regulate mitosis in S. quadricauda; their kinase activities were inhibited by Wee1. CDKA, CDKB protein levels were stabilized in the presence of zeocin. In contrast, the protein level of Wee1 was unaffected by DNA perturbing treatments. Wee1 therefore does not appear to be involved in the DNA damage response in S. quadricauda. Our results imply a specific reaction to DNA damage in S. quadricauda, with no cell cycle arrest, after experiencing DNA damage during G2 phase.     

The activity of total histone H1 kinases is related to growth and commitment points while the p13suc1-bound kinase activity relates to mitoses in the alga Scenedesmus quadricauda

Under optimal growing conditions, synchronous cultures of the alga Scenedesmus quadricauda underwent three DNA replications and three mitoses during one cell cycle. This resulted in eight daughter cells. By different illumination regimes and temporal addition of cycloheximide, cell divisions resulting in two, four or eight daughter cells per cycle were obtained. The selected cell cycle patterns differed in timing of commitment points, the number of nuclear divisions, and their positioning in the cell cycle. These distinct cell cycle patterns allowed to assess the correlation of histone H1 kinase activity with commitment points and mitoses. The activity of the histone H1 kinases was assayed in cellular protein extracts and after affinity purification using the p13^suc1 protein. The main peaks of kinase activity in the cellular extract were found to correlate with the commitment points. Small histone H1 kinase activity peaks were also found which preceded the nuclear division. Contrary to the histone H1 kinase activity of cellular extracts, the p13^suc1-bound kinase activity preceded the nuclear division, whilst its activity was negligible at the commitment points. Being able to manipulate the timing of commitment points and cell division by manipulating experimental conditions, we could precisely match the commitment points to an as yet unidentified histone H1 kinase activity and mitosis to p13^suc1-bound CDK activity during a particular cell division pattern with overlapping cycles. This provides molecular evidence, that local activation of CDKs regulates distinct events of the cell cycle.     

Effects of enhanced solar irradiation on chlorophyll fluorescence and photosynthetic oxygen production of five species of phytoplankton

Abstract The effects of solar irradiation on chlorophyll a fluorescence and photosynthetic oxygen production of three Cryptomonas species, Euglena gracilis and Scenedesmus cf. quadricauda were investigated in comparative field studies in Erlangen (280 m above sea level) and at Zugspitze (2957 m above sea level). The experiments showed that the decrease of fluorescence and the inhibition of photosynthetic oxygen production occurred after shorter times of exposure to solar radiation at Zugspitze compared to Erlangen in all tested organisms. Cryptomonas maculata was more sensitive towards radiation than the other organisms: fluorescence decreased earlier, while Scenedesmus cf. quadricauda seemed to be much less sensitive since fluorescence and photosynthetic oxygen production decreased later and to a smaller extent compared to the other organisms. The results of the present study indicate that increased solar radiation (with an increased level of UV-B radiation) at higher geographical altitudes may have significant effects on phytoplankton populations.     

Effect of dilution rate on competitive interactions between the cyanobacterium Microcystis novacekii and the green alga Scenedesmus quadricauda in mixed chemostat cultures

We examined the competition between the cyanobacterium Microcystisnovacekii (Kom.) Comp. and the green alga Scenedesmus quadricauda(Turpin) Brébisson using unialgal and mixed chemostatcultures with various supply rates of culture medium where limited algal growth. In unialgal cultures, bothspecies grew at all of the dilution rates examined (0.1, 0.3and 0.8 day^-1): steady-state cell densities were 1 x 10⁴ to8 x 10⁴ cells mL^-1 for M. novacekii and 0.5 x 10⁵ to 2.1 x 10⁵cells mL^-1 for S. quadricauda. Microcystis novacekii was dominantin mixed cultures at a dilution rate of 0.1 day^-1, where thesteady-state cell density was 1 x 10⁴ to 7 x 10⁴ cells mL^-1for M. novacekii and 1 x 10² to 5 x 10² cells mL^-1 for S. quadricauda.Scenedesmus quadricauda was dominant in mixed cultures at thehigher dilution rates (0.3 and 0.8 day^-1), where the final celldensity was 0.5 x 10² to 6.4 x 10² cells mL^-1 for M. novacekiiand 0.2 x 10⁵ to 7 x 10⁵ cells mL^-1 for S. quadricauda. Thisresult indicates that the dilution rate affects the competitiveinteraction. We conclude that it is necessary to consider waterexchange in the study of mechanisms of cyanobacterial blooms.     

Influence of light on the autospore number of some chlorococcal algae

The method of cultivation of algae on the surface of solid, medium under regulated conditions was used for studying the influence of light on the autospore number with three strains of chlorococcal algae:Scenedesmus quadricauda, Scenedesmus obliquus andChlorella kessleri. The results of these experiments show that not only light but the type of medium as well, exert a very important influence upon both nuclear and cell division and the whole course of the life cycle of algal cells. The number of autospores produced by single cells can be ascertained reliably on the surface of the solid medium. Owing to this fact the relations in cellular populations can be expressed with greater precision in comparison with the evaluation of cultures in liquid media.