不同藻类对大型溞存活和生殖的影响

通过生命表技术观察了大型溞（Daphnia magna）在实验室恒定温度（25 ℃）下分别以梅尼小环藻、铜绿微囊藻905、铜绿微囊藻469和斜生栅藻为饵料时的存活率和生殖量变化,并据此探讨了不同藻类对大型溞生活史特征的影响。结果表明：大型溞食用梅尼小环藻和铜绿微囊藻469后生长良好,大型溞在斜生栅藻中也能较好生长,而铜绿微囊藻905对大型溞的生长和繁殖均有不良影响;大型溞对不同藻类的净生殖率(R₀)、世代历期(T)和内禀增长率(r_m)及存活率有不同的影响,梅尼小环藻分别为44.35、11.86、0.32、5%;铜绿微囊藻469分别为48.20、14.25、0.27、30%;斜生栅藻分别为8.10、12.47、0.17、15%;铜绿微囊藻905分别为0、0、0、0。     

鲢对藻类摄食效应的室内模拟研究

为研究鲢(Hypophthalmichthys molitrix)对藻类的摄食作用, 采用小环藻(Cyclotella)、小球藻(Chlorella)、微囊藻(Microcystis)和东湖原水开展了小规格鱼种的养殖试验, 对鲢摄食和排泄物进行了研究。结果显示: 在3 种纯培养藻种投喂下鲢存活率从高到低依次是小环藻组 小球藻组 微囊藻组;相应地, 鲢对藻的平均摄食率排序也是小环藻组 小球藻组 微囊藻组。在显微镜下观察粪便发现大部分小环藻为空壳, 一部分小球藻外部形态结构不完整, 外部形态完整的小球藻则色泽暗淡、内部结构紊乱, 微囊藻没有明显变化;3 种藻类细胞的受损率分别为20.04%、7.13%和1.97%。叶绿素荧光活性显示, 粪便中小环藻基本失去光合活性, 小球藻活性极显著降低(P0.01), 微囊藻活性明显降低(P0.05), 东湖原水处理组光合活性较对照极显著降低(P0.01)。对东湖水饲喂试验组排泄物的检测发现, 浮鞘丝藻Planktolyngya、鱼腥藻Anabeana(有破损)、假鱼腥藻Pseudoanabaena 和颤藻Oscillatoria 细胞受损严重;空星藻Coelastrum 和盘星藻Pediastrum 细胞部分破损;针杆藻Synedra、小环藻、桥弯藻Cymbella 和舟形藻Navicula 多为空壳。鱼粪中平裂藻Merismopedia、微囊藻、浮鞘丝藻、鱼腥藻、颤藻、卵囊藻Oocystis、栅藻Scenedesmus 和衣藻Chlamydomonas 在重新培养后恢复了生长。本研究显示硅藻尤其是小环藻、针杆藻和舟形藻对鲢摄食最敏感;栅藻、卵囊藻和平裂藻对摄食压力不敏感。研究表明鲢捕食对藻类群落结构有明显的改变效应, 利用鲢的滤食进行藻类群落调节和水华防控具有可行性。       

超声波对铜绿微囊藻与蛋白核小球藻生理特征及竞争生长的影响

铜绿微囊藻是常见的水华蓝藻,常常在湖泊中与蛋白核小球藻共存或竞争生长。超声波可用于藻华即时治理,能够降低藻类生理活性,影响藻类生长,还可能改变藻类种间竞争关系。为了探究超声胁迫(35 kHz,0.035 W·cm^-3)对铜绿微囊藻与蛋白核小球藻的生理特征及种间竞争的影响,本研究设置纯藻组和1:1混合组(细胞浓度比)进行试验。结果表明: 铜绿微囊藻对超声胁迫更加敏感。超声处理600 s后,铜绿微囊藻的光合活性(F_v/F_m)和酯酶活性存在显著变化,纯藻组和混合组的F_v/F_m分别降低了51.8%和64.7%。而各组中蛋白核小球藻的光合活性变化较小。同时,铜绿微囊藻释放的荧光溶解性有机物(类色氨酸、类酪氨酸、类富里酸物质)含量多于蛋白核小球藻。两种藻的细胞浓度对超声波的响应也不同,蛋白核小球藻变化较小,而铜绿微囊藻的细胞浓度出现不同程度的下降。尤其是600 s超声处理大幅降低了混合组中铜绿微囊藻的细胞浓度(-42.6%),在超声胁迫解除后的8 d内蛋白核小球藻占优势,种间关系由铜绿微囊藻单边抑制蛋白核小球藻转变为两者互相抑制。在超声处理后,铜绿微囊藻的活性能够逐渐恢复,为了提高控藻效果的持久性,建议在一周后再次进行超声处理。     

大通湖浮游植物群落结构及其与环境因子关系

2008年12月至2009年10月按季度对养殖湖泊大通湖浮游植物群落结构及与环境因子关系进行了初步研究,并通过与1960年数据的纵向比较,探讨了集约化养殖对大通湖水域环境的影响,为其渔业可持续发展提供理论依据.调查期间,共发现浮游植物98种,隶属于7门54属.优势种类包括二角多甲藻、尖尾蓝隐藻、小球藻、卵形隐藻、梅尼小环藻、啮蚀隐藻、卷曲鱼腥藻、铜绿微囊藻和固氮鱼腥藻,优势种的季节更替明显.浮游植物细胞密度的年平均值为1.84×106 cells·L-1,其中夏季最高,为16.4×106 cells·L-1,其他3个季度在1.71×106 ～ 1.98×106 cells·L-1.浮游植物丰富度指数(D)全年在2.01 ～4.55,Shannon多样性指数(H)在1.26 ～2.69,均匀度指数(J)在0.69～1.27.典范对应分析表明,水深、水温、透明度、总磷、氧化还原电位、电导率是影响大通湖浮游植物群落结构的主要因子.     

纳米银抑制铜绿微囊藻的研究

目的:探讨不同浓度的纳米银对铜绿微囊藻的影响。方法:采用血球计数板计数和电子扫描显微镜研究纳米银对铜绿微囊藻生长和形态的影响。结果:当纳米银的浓度达到1.965 mg/L时,对铜绿微囊藻细胞的生长繁殖和叶绿素a的合成有抑制作用;当纳米银的浓度大于或等于9.825 mg/L时完全抑制叶绿素a的合成,但藻细胞依然能够存活。随着纳米银浓度的升高,对铜绿微囊藻的抑制作用增强。在扫描电镜下,可以清晰地看到纳米银与铜绿微囊藻的相互作用,纳米银结合在铜绿微囊藻的细胞壁上,引起细胞形变或裂解。结论:实验结果表明纳米银对铜绿微囊藻叶绿素a合成有较强的抑制作用,对细胞的生长繁殖的抑制相对较弱。     

铜锈环棱螺对水华中常见藻类的抑制效应

藻类水华频发已成为全球性的水环境问题,近年来,生物控藻法因具有环境友好的特点而备受关注。本研究以我国富营养化湖泊中常见大型底栖动物铜锈环棱螺为操纵生物,通过室内培养试验,研究了其对水华水体中常见蓝藻铜绿微囊藻、绿藻普通小球藻和斜生栅藻生长及光合活性的影响,以期阐明螺-藻间相互作用关系,探究铜锈环棱螺作为生物操纵物种的可行性。结果表明: 铜锈环棱螺能在短时间内大量摄食藻细胞,其对铜绿微囊藻产毒株和不产毒株以及斜生栅藻的去除率均在12 h内达到最大值,分别为73.7%、73.2%和51.1%;其对普通小球藻的摄食强于其他藻类,至试验结束时去除率达到99.2%。产毒铜绿微囊藻产生的微囊藻毒素会在铜锈环棱螺体内累积并促发其肝脏病理学变化,进而阻碍铜锈环棱螺的摄食。试验后期各处理组藻细胞光合活性均显著低于对照组,表明铜锈环棱螺的摄食作用对藻细胞造成了损伤,抑制了其大量增殖。此外,当不产毒铜绿微囊藻与斜生栅藻混合时,铜锈环棱螺的选择摄食性导致微囊藻的优势地位被斜生栅藻所取代。因此,铜锈环棱螺可以通过摄食作用抑制藻类的光合活性并降低其生物量,从而在一定程度上抑制或减缓水华的形成。     

铜绿微囊藻与小球藻对低温和黑暗的响应与恢复

研究以水华蓝藻铜绿微囊藻(Microcystis aeruginosa PCC 7806)与绿藻小球藻(Chlorella sp. FACHB-31)为研究对象, 探讨低温和黑暗对其生长、色素含量、最大光化学效率(F_v/F_m)、丙二醛(MDA)含量及过氧化氢酶活性的变化。结果表明, 30d的低温和黑暗处理, 显著降低了铜绿微囊藻和小球藻的叶绿素a浓度, 增加了单位细胞类胡萝卜素含量。在低温黑暗条件下, 铜绿微囊藻的MDA含量及CAT活性均显著增加, 而小球藻变化不明显。30d低温黑暗处理, 铜绿微囊藻的存活率为54.6%, 显著高于小球藻的31.3%。当恢复正常温度与光照, 2种藻均迅速生长。这些结果表明低温黑暗影响了微囊藻和小球藻的生理特性。在低温黑暗处理下, 微囊藻的F_v/F_m显著降低, 而小球藻则保持较为恒定的F_v/F_m, 表明微囊藻通过降低自身光合活性来渡过冬季低温黑暗的条件, 而小球藻在低温黑暗条件下仍保持较高的光合活性。     

藻类批量培养中的比增长率最大值

批量培养谷皮菱形藻、莱茵衣藻、粉核小球藻、斜生栅藻、羊角月牙藻和铜绿微囊藻等六种藻类,在对数生长期,逐日计数而确定比增长率最大值（μｍａｒ）,发现（μｍａｒ）值出现的时间在各种藻类中不同。同时讨论了每种藻类的（μｍａｒ）与营养物质、光强、温度和起始浓度之间的关系。铜绿微囊藻的（μｍａｒ）在一定的总磷（ＴＰ）浓度范围内随ＴＰ浓度呈上升趋势。根据获得增大率最大值的条件,对它们在浮游植物群落中的生态位作     

一株溶藻细菌NP23的初步分离鉴别及其溶藻作用研究

从水体中分离得到一株具有溶藻能力的细菌,命名为NP23。经形态特征、生理生化鉴定和16S rDNA序列分析表明,该菌株属于肠杆菌属(Enterobacter)。研究了该菌株对湖泊中优势藻的溶藻效果,初步探讨了其溶藻方式及溶藻物质。结果表明,该菌株对小球藻、惠氏微囊藻、栅藻和蛋白核小球藻具有一定的去除效果,叶绿素a的去除率分别为64.1%、53.1%、87.2%和84.4%,而且在10-108CFU/mL菌浓度范围内,藻的去除率与菌液的浓度成正相关;该菌株对小球藻、栅藻和蛋白核小球藻是间接溶藻,对惠氏微囊藻是直接溶藻;该菌株对栅藻的溶藻物质是蛋白类物质,对蛋白核小球藻的溶藻因子是菌体胞外分泌的具有热稳定性的非蛋白类物质。     

铜绿微囊藻、斜生栅藻对氮磷饥饿的耐受能力研究

在太湖微囊藻水华暴发期间 , 监测了梅梁湾水体中叶绿素 a 和氮磷营养盐的动态变化, 并通过批量培养实验研究了氮磷缺乏对铜绿微囊藻和斜生栅藻生长的影响 , 以探讨两种藻对氮磷饥饿的耐受能力对微囊藻水华形成的影响。结果表明 , 在水华期间 , 水体的氮磷营养盐浓度并不高, 并处于波动状态; 铜绿微囊藻和斜生栅藻对氮磷饥饿的耐受能力存在很大差异 : 在无磷培养基中 , 铜绿微囊藻能保持 8 天的指数生长, 而斜生栅藻在无氮或无磷培养基中生长都非常缓慢。两种藻对磷饥饿的耐受能力均高于氮。通过生长速率的比较, 发现铜绿微囊藻对磷饥饿的耐受能力明显高于斜生栅藻, 因此更能够适应波动的营养供给条件。对营养盐饥饿耐受能力的不同导致两种藻在营养盐波动的情况下微囊藻更易取得优势, 成为水华期间浮游植物的优势种。     

萼花臂尾轮虫培养滤液对铜绿微囊藻、斜生栅藻和小球藻群体形成及生长的影响

为探索浮游动物和藻类之间可能存在的信息传递,研究了萼花臂尾轮虫培养滤液对铜绿微囊藻、斜生栅藻和小球藻的生长及群体形成的影响.把萼花臂尾轮虫按1000个·L^-1的初始密度置于小球藻中培养24h后,用孔径0.15μm的微孔滤膜抽滤,得到轮虫培养滤液,此滤液中含有轮虫在生活过程中释放的一些信息化学物质.将轮虫培养滤液以20%的比例分别加入纯培养的铜绿微囊藻、斜生栅藻和小球藻中,进行为期7d的试验.结果表明,萼花臂尾轮虫培养滤液能显著地促进斜生栅藻的群体形成,而对铜绿微囊藻和小球藻在群体形成方面没有显著作用.另外,该滤液能显著提高小球藻种群的增长,对铜绿微囊藻和斜生栅藻的生长无明显影响.3种藻类对萼花臂尾轮虫的潜在牧食采取了不同的生态策略:斜生栅藻形成群体,增大摄食阻力,从而降低被摄食的风险;小球藻通过提高增长率来抵消被取食的损失;铜绿微囊藻是通过其它方式来降低被牧食(例如毒素).这些方式分别是这些藻类维持种群规模的反牧食防御策略之一.     

Isolation and characterization of a novel antialgal allelochemical from Phragmites communis

Antialgal allelochemicals were isolated from Phragmites communis Tris. The isolated allelopathic fraction showed strong inhibition activity on the growth of Chlorella pyrenoidosa and Microcystis aeruginosa but had no inhibition on Chlorella vulgaris. The 50% effective concentrations (EC50) of the allelopathic fractions on C. pyrenoidosa and M. aeruginosa were 0.49 and 0.79 mg/liter, respectively. The allelopathic activity of the fraction was species-specific. The isolated allelopathic fraction caused metal ion leakage from algal cells. The fraction decreased the activities of antioxidant enzymes, such as superoxide dismutase and peroxidase. The addition of the isolated fraction increased the concentration of unsaturated lipid fatty acids in cell membrane of C. pyrenoidosa and M. aeruginosa. This caused a change in plasma membrane integrity and the leakage of ions in the protoplast. The allelopathic compound was identified by nuclear magnetic resonance and gas chromatography-mass spectrometry as ethyl 2-methylacetoacetate. Synthesized ethyl 2-methylacetoacetate also showed allelopathic activity on C. pyrenoidosa and M. aeruginosa. The EC50 of synthesized ethyl 2-methylacetoacetate on C. pyrenoidosa and M. aeruginosa were 0.49 and 0.65 mg/liter, respectively.     

溶微囊藻细菌的富集筛选及其菌群结构特征

利用铜绿微囊藻(Microcystis aeruginosa)作为溶藻对象富集、筛选, 获得一个稳定的溶藻菌群。采用叶绿素、PCR和变性梯度凝胶电泳(DGGE)方法研究溶藻过程及其细菌种群结构的变化。结果显示, 富集的溶藻菌经1×10-5稀释后仍有显著溶藻效果。Rubritepida菌C1、假单胞菌C2和鞘氨醇单胞菌C3是存在于铜绿微囊藻中的3种伴生细菌。加入富集的溶藻菌群后, 菌群结构发生明显的变化, Rubritepida菌C1、假单胞菌C2消失, 混合菌群包含未培养黄杆菌A2、鞘氨醇单胞菌C3和噬氢     

Protective role of 20-hydroxyecdysone against lead stress in Chlorella vulgaris cultures

Treatment of cultured C. vulgaris cells with 10(-6)-10(-4) M lead decreased their growth and chemical composition during the first 48 h of cultivation. However, at concentrations above 10(-4) M, lead is cytotoxic to Chlorella vulgaris cells, resulting in cellular fragmentation and lysis. In contrast, at concentrations below 10(-6) M lead had no influence on the growth and metabolism of C. vulgaris cells. 20-Hydroxyecdysone (20E) (10(-10)-10(-8) M) increased growth and chemical composition of C. vulgaris cells over a concentration range. Levels per cell of chlorophylls, protein, sugars are all increased by 20E treatment, when compared to non-treated control cells. However, the cultures treated with 20E and lead show a lower stimulation than the cultures treated with 20E alone. The effects of 20E mixed with lead on the growth and the level of cellular lead, chlorophyll, sugar and protein in C. vulgaris are also reported. The decreased growth and composition of C. vulgaris cells treated with lead was restored by the 20E. Application of 20E to C. vulgaris cultures reduced the impact of lead stress on growth, prevented chlorophyll, sugar and protein loss and increased phytochelatins synthesis. Furthermore, 20E did not restore toxic effect of lead on C. vulgaris cells. The combined treatment with lead and 20E appeared to have a stimulatory effect on the above parameters during the 48 h of cultivation, as compared to the control. 20E reduced the toxicity of lead and the growth recovered to the level of cells treated with 20E alone. Concentration-dependent stimulation was observed with increasing concentration of 20E and decreasing concentration of lead.     

梓属5个种对干旱胁迫的生理响应

为分析梓属5个种干旱胁迫响应程度,为梓属耐旱树种的筛选、抗旱育种及栽培工作提供理论依据。本研究选取梓属的黄金树、滇楸、灰楸、梓树和楸树为试材,将其在浇水量为700 mL和400 mL的水分条件下培养50 d,测量其苗高、地径、叶水势、叶绿素相对含量、叶绿素荧光参数和比叶重等指标,并运用隶属函数法对其抗旱性进行综合评价。结果表明:在2种水分条件下,生长状态最好的为楸树,梓树相对较差。在干旱胁迫条件下,除黄金树外,其他各树种的叶片水势(ΨL)都降低,最大气孔导度(Gs)均增加。不同种的叶绿素相对含量(SPAD)值均在干旱胁迫条件下升高。除滇楸和楸树外,各树种的光系统Ⅱ最大光能转换效率(Fv/Fm)随干旱胁迫而增加。除灰楸外,干旱胁迫增加了其他树种的比叶重(LMA)。利用隶属函数法综合评价抗旱性的结果为:灰楸>梓树>滇楸>楸树>黄金树。说明梓属不同树种间有着不同的抗旱能力。综合分析,楸树和灰楸的抗旱能力较强,滇楸和梓树的抗旱能力次之,黄金树的抗旱能力最差。     

LIGHT-DEPENDENT GROWTH, DARK SURVIVAL, AND GLUCOSE UPTAKE BY CRYPTOPHYTES ISOLATED FROM A FRESHWATER CHEMOCLINE

Clones of Cryptomonas phaseolus Skuja , Cryptomonas rostratiformis ( Skuja ) Skuja in Huber-Pestalozi, and Cryptomonas undulata Gervais were isolated from the deep chlorophyll maximum near the oxic/anoxic boundary layer of the mesoeutrophic lake Schlachtensee, Germany. Different autecological features of these species were studied in batch culture experiments . Cryptomonas cf . ovata Ehrenberg and Chroomonas sp. that never dominated in the deep chlorophyll layer were also isolated from Schlachtensee to study their light-dependent growth in comparison to the deep-living species . Cryptomonas undulata, C. cf . ovata, and C. phaseolus had a very low light compensation point ( 5–7 μmol.m^-2.s^-1 ), whereas the growth rate of Chroomonas sp. and C. rostratiformis was positive above 16 and 24 μmol.m^-2.s^-1 . Cryptomonas phaseclus and Chroomonas sp. became photoinhibited above photon flux densities of 92 and 116 μmol.m^-2.s^-1 . Cryptomonas rostratiformis, C. cf . ovata, and C. undulata reached a maximum growth rate at a considerably higher photon flux density (198–250 μmol.m^-2.s^-1 ). Cryptomonas phaseolus grew fastest under light-limiting conditions . Chyptomonas phaseolus and C. undulata were best able to suruive prolonged periods of darkness . Cryptomonas phaseolus, C. rostratiformis, and C. undulata did not show any uptake of fluorescent latex beads. When labeled glucose was provided in naturally occurring concentrations, carbon uptake by C. phaseolus, C. rostratiformis, and C. undulata was negligibly small in comparison to cellular carbon content. I suggest that the adaptation to a low-light environment is an important preadaptation for the dominance of C. phaseolus and C. undulata near the freshwater chemocline .     

Mechanisms for tolerating freeze-thaw stress of two evergreen chaparral species: Rhus ovata and Malosma laurina (Anacardiaceae)

The response to freeze-thaw stress was examined for two co-occurring evergreen species, Malosma laurina and Rhus ovata. Laboratory and field experiments on adults and seedlings were made in the spring and winter in 1996 and again on adults in 2003 and 2004. Laboratory and field results indicated that the stem xylem for adults of M. laurina and R. ovata were similarly susceptible to freezing-induced cavitation (percentage loss of conductivity = 92 ± 2.6% for R. ovata and 90 ± 4.2% for M. laurina at ≤ -6°C). In contrast, leaves of M. laurina were more susceptible to freezing injury than leaves of R. ovata. Among seedlings in the field, leaves of M. laurina exhibited freezing injury at -4°C and total shoot mortality at -7.2°C, whereas co-occurring seedlings of R. ovata were uninjured. Surprisingly, R. ovata tolerates high levels of freezing-induced xylem embolism in the field, an apparently rare condition among evergreen plants. Rhus ovata avoids desiccation when xylem embolism is high by exhibiting low minimum leaf conductance compared to M. laurina. These results suggest a link between minimum leaf conductance and stem hydraulics as a mechanism permitting the persistence of an evergreen leaf habit in freezing environments.     

生长素吲哚乙酸对铜绿微囊藻生理生化及产毒特性的影响

为了探究生长素吲哚乙酸(IAA)对产毒铜绿微囊藻(Microcystis aeruginosa)的影响, 从生长、光合色素含量、叶绿素光诱导荧光特征、脂质氧化和微囊藻毒素合成特性等方面, 研究了IAA对M. aeruginosa CHAB6301生理生化及产毒的影响。结果表明, 在低浓度IAA(0.04和0.2 mg/L)条件下, 铜绿微囊藻生长、叶绿素含量、光合系统(PSⅡ)电子传递效率及藻毒素含量均无明显变化, 藻蓝蛋白、别藻蓝蛋白和丙二醛(MDA)含量均低于对照。高浓度IAA(1和5 mg/L)能够促进细胞生长, 提高叶绿素含量, 但是抑制藻蓝蛋白和别藻蓝蛋白含量, 降低膜脂过氧化程度和细胞内藻毒素合成。综合各指标测定结果, 低浓度IAA对M. aeruginosa CHAB6301生长和光合作用影响不明显, 而高浓度IAA可促进藻细胞生长和光合作用, 增加微囊藻水华形成几率。     

改性纳米TiO2对蓝藻的生理生态影响

在自然光照条件和日光灯光照条件下,用掺1％Ag纳米TiO2、掺5％Fe2O3纳米TiO2、掺10％ZnO纳米TiO2和纯纳米TiO2对铜绿微囊藻（Synechocystis sp．）PCC6803和集胞藻（Microcystis aeruginosa）进行处理,并对2种藻样的叶绿素含量、类胡萝卜素含量、体外超氧自由基含量及超氧化物歧化酶（superoxidase dismutase,SOD）活性进行测定。结果表明,自然光照条件比日光灯光照条件更利于纳米材料光催化反应的进行;改性后的3种纳米材料对蓝藻的抑制效果要好于纯纳米TiO2,其中效果最好的为掺1％Ag纳米TiO2;2种藻样在适应由光催化剂引发光催化而产生的自由基胁迫时,集胞藻的适应能力比铜绿微囊藻更强。