铜绿微囊藻光合活性对LED光短期暴露的响应

为探究LED光对蓝藻光合活性的影响,以铜绿微囊藻Microcystis aeruginosa PCC 7806为对象, 25μmol photons/(m²·s)白色荧光灯为对照,检测了不同光质光强LED处理2h的光合活性。结果表明,与对照相比,25—50μmol photons/(m²·s) LED红光和蓝光、25—100μmol photons/(m²·s) LED白光和绿光处理下,细胞光合活性(F_v/F_m)显著提高。大于100μmol photons/(m²·s)的LED红光和蓝光、大于200μmol photons/(m²·s)的LED白光及大于500μmol photons/(m²·s)的LED绿光处理对光合活性有显著抑制作用,光系统Ⅱ(PSⅡ)最大光化学效率F_v/F_m、电子传递速率ETR(Ⅱ)、光量子产量Y(Ⅱ)、光系统Ⅰ(PSⅠ)电子传递速率ETR(Ⅰ)、...     

超声波对铜绿微囊藻超微结构和生理特性的影响

为了研究超声波对蓝藻细胞的影响,利用超声波（40W）处理200 mL铜绿微囊藻（Microcystis aeruginosa） 悬浮液20min,之后继续培养并于不同时间取样检测。检测悬浮藻细胞生物量发现其3d降低了97.84%;分别观察1、3、5d时沉降藻细胞超微结构变化,发现13d时细胞内脂质颗粒和藻青素颗粒增多、类囊体片层断裂、藻胆体脱落,5d时拟核区萎缩消失、细胞基础结构解体、胞质出现空洞、胞内结构颗粒降解;检测藻细胞光合放氧速率、叶绿素a （Chl.a）、超氧化物歧化酶（SOD）和过氧化氢酶（CAT）活性、膜透性以及跨膜ATP酶活性,发现光合放氧速率3d下降24.83%,Chl.a含量5d下降23.75%,超声组细胞SOD活性变化幅度比较大,但总体上活性降低,而CAT活性则表现为先增后减,活性始终大于对照组,同时胞内有机物渗出量增大,三种跨膜ATP酶活性（Na+/K+-ATPase、Mg2+-ATPase 和Ca2+-ATPase）均先升后降,并与膜透性变化相关。以上结果表明,超声波使铜绿微囊藻细胞沉降,并对其造成了胁迫,使部分藻细胞光合作用减弱,光合色素遭到损伤,细胞膜透性增大,甚至引起藻细胞程序性死亡。SOD活力的快速降低表明超声波使藻细胞内超氧离子（O2-）过量累积,从而对藻细胞造成氧化损伤,除此之外,超声波使藻细胞基础结构破坏、细胞内结构颗粒降解、细胞膜透性增大,这些都可能是致使部分铜绿微囊藻细胞死亡的重要原因。铜绿微囊藻细胞CAT以及跨膜ATP酶活性增大,表明藻细胞增强抗氧化酶活性以及离子调控和能量活动以抵御超声波的胁迫,而当胁迫随着时间减小后,细胞开始恢复生长和代谢,酶活力开始降低。       

黑暗条件下不同氮源对铜绿微囊藻(Microcystis aeruginosa)生长和pH的影响

在黑暗条件下,利用不同形态的氮源(硝酸盐氮,氨氮,有机氮和硝酸盐氮,有机氮)培养蓝藻水华优势种铜绿微囊藻(Microcystis aeruginosa),分析其氮代谢和对水体pH的影响.研究结果表明,在不同氮源的培养液中铜绿微囊藻密度在最初的24 h内出现波动,之后下降.培养液中pH值在试验最初的24 h显著下降,之后趋于稳定,在硝态氮培养液中pH值下降最大,从8.18下降到7.19,其反硝化作用产生的NO-2浓度也最大.不同氮源培养液中总氮含量都有所下降,以混合氮源培养液中总氮减少量最大,说明化合态氮经过反硝化作用生成了氮气并溢出培养液,因此,在黑夜条件下藻华水体中存在反硝化作用.     

粉绿狐尾藻（Myriophyllum aquaticum）对铜绿微囊藻（Microcystis aeruginosa）的化感抑制效应及其生理机制

由于生物法,尤其是水生植物化感控藻方法在治理水体富营养化及水华现象中具有多方面的优势,近年来该领域的理论和技术研究备受世界各国关注.采用初始添加种植水和连续添加种植水的方法,研究挺水型粉绿狐尾藻对铜绿微囊藻的化感抑藻效应,并从光合作用的角度探讨其对铜绿微囊藻化感抑制的生理生态机制及作用靶点.研究结果表明:粉绿狐尾藻能够分泌某些化感物质有效抑制铜绿微囊藻的正常生长,其抑藻效应是通过连续释放某些化感物质作用于铜绿微囊藻而实现的,且具有累积性;粉绿狐尾藻分泌化感物质对铜绿微囊藻的Chl a、PC及APC的损伤程度存在差异(如处理5 d后,Chl a、PC、APC的相对含量分别降至52.7%、15.3%、7.6%),其中藻胆蛋白(尤其是APC)比Chl a 更为敏感,说明藻胆蛋白是粉绿狐尾藻化感物质抑制铜绿微囊藻的关键靶点.研究为水生植物化感控藻技术的发展提供了新的材料,并有助于深入了解水体生态系统的化学生态作用及其机制.     

KCl和NaCl对毕氏海蓬子生长和几种抗氧化酶活性的影响

50-200 mmol·L-1NaCl显著促进海蓬子生长和抗氧化酶[超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)]活性,与NaCl浓度相同的KCl明显抑制海蓬子生长和此3种酶的活性,但KCl下的超氧阴离子(O2-)和丙二醛(MDA)含量增加程度则明显高于同浓度的NaCI处理.据此认为,KCl伤害海蓬子的原因之一是抗氧化酶活性下降,不能及时清除活性氧,以致活性氧和MDA积累,引起质膜伤害,海蓬子生长受抑和生长量下降.     

来源于蓝藻、铜绿微囊藻的尿苷二磷酸葡萄糖脱氢酶基因的克隆和鉴定

以已知的尿苷二磷酸葡萄糖脱氢酶基因的保守区为基础,自行设计一对简并引物,该对引物从形成水华的蓝藻（Synechocystis PCC6803)铜绿微囊藻FACHB 905株(Microcystis aeruginosa FACHB 905)的基因组DNA中扩增到一个476bp的DNA片段。通过TAIL-PCR和连接介导的PCR两种方法分离该片段的侧翼序列,最后得到大小约2．5kb的DNA片段。序列分析揭示其中有一个编码462个氨基酸的开放阅读框,我们将此开放阅读框对应的蛋白命名为Mud。该Mud蛋白的氨基酸序列与蓝藻(73％相同,87％相似)和细菌(Bacillus subtilis)(51％相同,67％相似)的尿苷二磷酸葡萄糖脱氢酶氨基酸序列表现高度的同源性。将该mud基因克隆于p-GEX-4T-1融合表达载体并在大肠杆菌中表达GST—Mud融合蛋白,经过酶活力测定发现,GST—Mud蛋白具有一定的尿苷二磷酸葡萄糖脱氢酶活性。用抗GST-Mud蛋白的多抗对Maeruginosa FACHB 905的胞质蛋白组分进行Western印迹分析,结果显示一条分子量大小约49kD的专一条带,这个分子量与从基因推断出的蛋白分子量大小基本一致。综上所述,我们认为从微囊藻克隆到的Mud蛋白基因是尿苷二磷酸葡萄糖脱氢酶基因,该酶在其他生物如植物和细菌中参与多糖合成,是多糖合成的关键酶之一,而在藻类中对尿苷二磷酸葡萄糖脱氢酶开展研究却是首次报道。     

来源于蓝藻、铜绿微囊藻的尿苷二磷酸葡萄糖脱氢酶基因的克隆和鉴定

以已知的尿苷二磷酸葡萄糖脱氢酶基因的保守区为基础,自行设计一对简并引物,该对引物从形成水华的蓝藻(Synechocystis PCC6803)铜绿微囊藻FACHB 905株(Microcystis aeruginosa FACHB 905)的基因组DNA中扩增到一个476 bp的DNA片段.通过TAIL-PCR和连接介导的PCR两种方法分离该片段的侧翼序列,最后得到大小约2.5 kb的DNA片段.序列分析揭示其中有一个编码462个氨基酸的开放阅读框,我们将此开放阅读框对应的蛋白命名为Mud.该Mud蛋白的氨基酸序列与蓝藻(73%相同,87%相似)和细菌(Bacillus subtilis)(51%相同,67%相似)的尿苷二磷酸葡萄糖脱氢酶氨基酸序列表现高度的同源性.将该mud基因克隆于p-GEX-4T-1融合表达载体并在大肠杆菌中表达GST-Mud融合蛋白,经过酶活力测定发现,GST-Mud蛋白具有一定的尿苷二磷酸葡萄糖脱氢酶活性.用抗GST-Mud蛋白的多抗对M.aeruginosa FACHB 905的胞质蛋白组分进行Western印迹分析,结果显示一条分子量大小约49 kD的专一条带,这个分子量与从基因推断出的蛋白分子量大小基本一致.综上所述,我们认为从微囊藻克隆到的Mud蛋白基因是尿苷二磷酸葡萄糖脱氢酶基因,该酶在其他生物如植物和细菌中参与多糖合成,是多糖合成的关键酶之一,而在藻类中对尿苷二磷酸葡萄糖脱氢酶开展研究却是首次报道.     

Effects of Sb(V) on Growth and Chlorophyll Fluorescence of Microcystis aeruginosa (FACHB-905)

In this study, effects of antimony Sb(V) on growth, pigments content, oxygen evolution, and photosystem II (PSII) activity of Microcystis aeruginosa were investigated. JIP-test, Q _A ^? reoxidation kinetic test and S-state test were used in this study to study the energy distribution and electron transport in PSII. Treatment with Sb(V) at various concentrations ranging from 5 to 100?mg/l had long-term effects on growth, pigments content, and oxygen evolution of M. aeruginosa. Low concentration of Sb(V) had no significant inhibition of the biomass production and PSII activity but inhibited the pigment synthesis. Growth, pigments content, oxygen evolution, and PSII activity were seriously inhibited when treated by high concentration of Sb(V) (100?mg/l). The target sites of Sb(V) toxic effect on the PSII of M. aeruginosa were mainly on the donor side and the apparatus in the light-dependent reaction. The quantum yield for photochemistry, density of reaction centers and photosynthesis performance index decreased, whereas the dissipated energy increased. PSII activity of M. aeruginosa was promoted when exposure to 50?mg/l Sb(V) by increasing the density of active reaction centers and electron transport after Q _A ^? .     

Photosynthesis and primary production of Microcystis aeruginosa Kutz. in Lake Kasumigaura

Seasonal changes in the photosynthesis and primary productionof Microcystis aeruginosa Kütz. were investigated in LakeKasumigaura during 1981–1982. Microcystis always showeda light-saturated photosynthesis-light curve. Both P_max andthe initial slope of the photosynthesis-light curve of Microcystisin early summer were very high, so it was concluded that Microcystisutilized both low and high light intensities efficiently. TheP_max of Microcystis was found to be a function of the watertemperature except in August and September. The linear regressionon the temperature-P_max relationship discontinued at 11°C,where the P_max value dropped; Microcystis did not photosynthesizebelow 4°C. The initial slope of the curve was also descendingbelow 11°C. It is suggested that Microcystis changes itsphysiological properties below 11°C. The highest value ofgross production calculated for M. aeruginosa was 5.4 gC m^–2d^–1 in July; the annual gross production was estimatedto be 300 gC m^–2year^–1 (i.e., 40% of the total primaryproduction in this lake).     

铜绿微囊藻(Microcystis aeruginosa)对惠氏微囊藻(Microcystis wesenbergii)的化感作用

通过混合培养和添加过滤液两种方式观察铜绿微囊藻和惠氏微囊藻的生长曲线,探讨两种微囊藻之间的化感作用。结果表明:在混合培养条件下,两者能够形成相互抑制作用;当两者起始藻密度高于0.5×106cells.mL-1、混合比为1:1时,惠氏微囊藻的生长因化感作用而受到显著抑制(P<0.05),同时惠氏微囊藻也会对铜绿微囊藻产生一定的胁迫作用;处于对数生长期的铜绿微囊藻过滤液能抑制惠氏微囊藻的生长,且惠氏微囊藻起始藻密度低于0.5×106cells.mL-1,连续滴加该过滤液后,其生长受到极显著抑制(P<0.01)。     

Effects of nitrate on intracellular nitrite and growth of Microcystis aeruginosa

Although nitrate is a macronutrient and can serve as good nitrogen source for many species of phytoplankton, high nitrate concentrations do not benefit the growth of phytoplankton. We hypothesise that algae cultured under high nitrate concentrations can accumulate intracellular nitrite, which is produced by nitrate reductase (NR) and can inhibit the growth of algae. To assess the validity of this hypothesis, Microcystis aeruginosa was grown under different nitrate concentrations from 3.57 to 21.43 mM in low CO₂ and high CO₂ conditions for 15 days. We observed that, with increasing nitrate concentrations, the intracellular nitrite concentrations of the alga increased and the growth rates and photosynthesis declined. When grown under high CO₂ conditions, M. aeruginosa showed lower intracellular nitrite concentrations and higher growth rates and \textP_\textm^\textchla {\text{P}}_{\text{m}}^{{\text{chl}}a} , \textR_\textd^\textchla {\text{R}}_{\text{d}}^{{\text{chl}}a} , α^chla than under low CO₂ conditions. These results suggest that the accumulation of intracellular nitrite could be the cause of inhibition of algal growth under high nitrate concentrations.     

Effects of the blue-green alga Microcystis aeruginosa on zooplankton competitive relations

Summary Field distribution patterns and laboratory feeding experiments have suggested that blooms of colonial blue-green algae strongly inhibit relatively large-bodied daphnid cladocerans. We conducted laboratory experiments to test the hypothesis that blooms of the colonial blue-green alga Microcystis aeruginosa would shift competitive dominance away from large-bodied daphnid cladocerans toward smaller-bodied cladocerans, copepods, and rotifers. In laboratory competition experiments, increasing the proportion of M. aeruginosa in the algal food supply resulted in a shift from dominance by the relatively largebodied cladoceran Daphnia ambigua to dominace by the copepod Diaptomus reighardi. The small-bodied cladoceran Bosmina longirostris was always numerically heavily dominant over D. ambigua, but its estimated population biomasses were only slightly higher than those of D. ambigua. Daphnia ambigua consistently outcompeted the rotifer Brachionus calyciflorus. Our results demonstrate that blooms of M. aeruginosa can alter zooplankton competitive relations in laboratory experiments, favoring small-bodied cladocerans and copepods at the expense of large-bodied cladocerans. However, contrary to predictions, blooms of M. aeruginosa did not improve the competitive ability of rotifers.     

Effects of Chilling on the Ultrastructure and Net Photosynthesis of Pellia epiphylla

Thalli of Pellia epiphylla were collected frozen from natureand chilled artificially for varying lengths of time at –22°C. The survival and recovery of this material was comparedwith that of the non-chilled material by performing CO₂ exchangeexperiments. Electron microscopy was done from the chilled andhardened thalli, and clear differences were observed in theultrastructure of these materials. The vacuoles of the hardenedtissue contained fine granular material but those of the chilledtissue had large electrondense particles embedded in finer granularsubstance. Oil bodies had greatly changed. In the cytoplasmthere were abundant lipid-like bodies resembling oil globulesof oil bodies and particularly in the vacuoles there were oily-lookingflecks. Chloroplasts had large starch grains and the lamellarsystem was somewhat disorganized. Net photosynthesis was highestwith material stored for the longest time at –22 °C. Pellia epiphylla, ultrastructure, net photosynthesis, chilling     

Effects of Microcystis aeruginosa on interference competition between Daphnia pulex and Keratella cochlearis

Laboratory experiments tested the hypothesis that a toxic strain of Microcystis aeruginosa decreases the ability of Daphnia pulex to interfere with Keratella cochlearis. To test a variety of conditions, juvenile and adult Daphnia were exposed to the cyanobacterium for different time periods prior to, and during the experiments. Adult Daphnia not only suppressed rotifers over successive two-day intervals, but also had a significant impact within a 24-hour period. However, the presence of Microcystis (5 × 105 cells ml^–1) decreased the Daphnia effect in both experiments. Although juvenile Daphnia also significantly suppressed Keratella population growth, the presence of Microcystis (10⁵ and 5 × 10⁵ cells ml^–1) caused a significant reduction in daphniid body size and decreased the ability of both nonacclimated and acclimated daphniids to suppress rotifers. Keratella inhalation and mortality are positively correlated with filtering rates and body size of Daphnia. Therefore, the feeding rates and size structure of a Daphnia population will determine its potential to interfere with vulnerable rotifers. In all experiments the presence of Microcystis significantly decreased the ability of Daphnia to interfere with this rotifer despite the fact that Keratella was also inhibited. In the field this effect might be augmented if Microcystis colonies are more easily ingested by cladocerans than by the rotifers.     

Effects of Microcystis aeruginosa exposure and nutritional status on the reproduction of Daphnia pulex

Microcysrtis aeruginosa exposure, as well as low food availabilitybefore the experiment, resulted in decreased egg viability inDaphnia pulex Food availability during the experiment did notaffect the results significantly