洱海水华铜绿微囊藻生长特性的初步研究

目的:分离纯化出洱海主要的优势铜绿微囊藻并观察其生长规律及特性。方法:采用水滴-涂布平板法分离纯化铜绿微囊藻,采用90%的丙酮提取叶绿素,酶标仪测定其含量,用显微镜计数藻细胞的个数。结果:铜绿微囊藻细胞密度与OD665呈直线关系,R2=0.993 1,藻细胞的增长速率在第6天达到最大值为0.524,其叶绿素及类胡萝卜素的含量随时间的变化而逐步升高。结论:此铜绿微囊藻的生长符合"S"型曲线,藻细胞密度与吸光度成线性相关,其生长速率在第6天达到最大。     

铜绿微囊藻气囊结构蛋白GvpC的表达纯化与晶体生长研究

对GvpC进行了初步晶体学研究。首先对GvpC进行分子克隆,利用原核表达系统在体外进行异源表达;结合变复性和凝胶过滤层析的方法纯化GvpC;通过圆二色谱的方法鉴定GvpC的复性效果;运用坐滴蒸汽扩散法进行晶体初筛。结果表明：GvpC在大肠杆菌表达系统中表达为包涵体;通过变复性和凝胶过滤层析能纯化出纯度较高的蛋白;圆二色谱证实复性后的GvpC形成了正确的二级结构,复性效果较佳;通过晶体初筛获得了GvpC的晶体,后续即可通过解析GvpC的晶体结构而获得其三维结构。     

环境因子对铜绿微囊藻生长和产毒的影响

以铜绿微囊藻为试验对象,研究其在不同温度、光照、氮磷浓度条件下生长和产毒的情况.通过计算铜绿微囊藻细胞数来反应其生物量的变化趋势,用高效液相色谱仪测定藻毒素-LR的浓度来反应藻细胞产毒变化.结果表明,铜绿微囊藻在30℃、1 000 Lux时生长最快,而在25℃、500 Lux时产毒最多;铜绿微囊藻生物量和产毒量随着总氮浓度的升高而增多;磷是一种限制性营养因子,较低浓度时就可以满足铜绿微囊藻的生长和产毒;最适合铜绿微囊藻产毒的氮磷比为100∶1.     

垃圾填埋场渗沥液对部分淡水藻类的作用

报道了上海市老港垃圾填埋场2001年12月31日排放的渗沥液对铜绿微囊藻、斜生栅藻和蛋白核小球藻的生长、叶绿素a含量、细胞大小的影响。渗沥液影响藻类细胞的大小。渗沥液对铜绿微囊藻生长影响作用大于斜生栅藻和蛋白核小球藻。未处理的渗沥液比处理后的渗沥液对藻类影响作用大。     

温度、光照及藻细胞密度对3种水华蓝藻生长及竞争的影响

以铜绿微囊藻(Microcystis aeruginosa Kutzing)、细小平裂藻(Merismopedia minima G.Beck)和土生伪鱼腥藻(Pseudanabaena mucicola(NaumannHuber-Pestalozzi)Schwabe 1964)为研究对象,运用单因子和正交实验的方法,分析了温度、光照以及藻细胞初始密度对三者生长及竞争的影响.结果表明:铜绿微囊藻和细小平裂藻均能在高温、高光照的条件下达到最佳生长状态;黏伪鱼腥藻只有在低温、低光照的情况下才具有竞争优势.在相同的温度和光照条件下,不同的藻细胞初始密度是其竞争获得优势藻种地位的关键因子.除了控制营养盐和其他污染物的输入外,关注浮游植物群落结构变化,控制和降低蓝藻在水华爆发前的生物量密度,是治理淡水湖泊(水库)蓝藻水华的有效方法.     

鞣花酸对铜绿微囊藻和斜生栅藻的生长抑制作用

采用三种不同浓度的鞣花酸作用于斜生栅藻和铜绿微囊藻,探索了鞣花酸对这两种藻的生长抑制作用.通过同期生长的处理组与对照组的藻细胞数和OD值比较以及抑制率计算t、检验等对实验结果进行分析表明:鞣花酸对铜绿微囊藻和斜生栅藻的最大抑制率都在85%以上,但对铜绿微囊藻抑藻效果更显著.鞣花酸浓度为0.9 mmol/L时,对斜生栅藻的生长有明显的抑制作用;而在0.6mmol/L时就对铜绿微囊藻表现出明显的抑制效应,这些结果可为水华的治理提供理论参考.     

紫外光浸入式照射对铜绿微囊藻的去除

通过与常规照射方式对比,研究185nm紫外光浸入铜绿微囊藻溶液中接触式照射对铜绿微囊藻光密度、叶绿素a、可溶性蛋白及细胞结构的影响,考察不同初始质量浓度及通入空气量对各指标去除效果的影响.结果表明,光密度、叶绿素a质量浓度、可溶性蛋白质量浓度最终分别下降87.1%,99.8%和99.7%,去除效果明显优于常规方式的紫外照射.随着初始值的增加,叶绿素a的去除率,可溶性蛋白的降解速率减慢.通气量增加,各指标去除率有所增加,但差异不显著,在浸入照射方式下,氧对紫外光作用的催化效果不明显.185nm紫外光使铜绿微囊藻的细胞结构短时间受损,胞内物质结构及胞外物质均产生显著变化,藻细胞畸变.185nm紫外光在浸入方式下,短时间可以有效灭活藻细胞,降低其生理活性及生长速率.浸入式照射的强氧化性使各指标去除效果明显优于常规方式的紫外照射,并在后续培养中未出现光复活现象.     

185nm紫外光浸入式照射对铜绿微囊藻的去除

通过与常规照射方式对比,研究185nm紫外光浸入铜绿微囊藻溶液中接触式照射对铜绿微囊藻光密度、叶绿素a、可溶性蛋白及细胞结构的影响,考察不同初始质量浓度及通入空气量对各指标去除效果的影响.结果表明,光密度、叶绿素a质量浓度、可溶性蛋白质量浓度最终分别下降87.1%,99.8%和99.7%,去除效果明显优于常规方式的紫外照射.随着初始值的增加,叶绿素a的去除率,可溶性蛋白的降解速率减慢.通气量增加,各指标去除率有所增加,但差异不显著,在浸入照射方式下,氧对紫外光作用的催化效果不明显.185nm紫外光使铜绿微囊藻的细胞结构短时间受损,胞内物质结构及胞外物质均产生显著变化,藻细胞畸变.185nm紫外光在浸入方式下,短时间可以有效灭活藻细胞,降低其生理活性及生长速率.浸入式照射的强氧化性使各指标去除效果明显优于常规方式的紫外照射,并在后续培养中未出现光复活现象.     

亚致死剂量UV-C辐照抑制铜绿微囊藻生长的效果

铜绿微囊藻是中国典型的水华蓝藻。该文研究亚致死剂量短波紫外线(UV-C)辐照对其生长的抑制效果。采用准平行光束仪进行定量辐照处理,用共聚焦激光扫描显微镜进行藻细胞计数,用流式细胞术识别藻细胞膜完整性,三维荧光光谱分析藻蓝蛋白及叶绿a的相对荧光水平。结果表明:对初始密度为106个/mL铜绿微囊藻,UV-C辐照能抑制藻细胞生长,亚致死剂量范围是50~100 mJ/cm2,抑制效果可以持续7 d。     

AHLs及其结构类似物对蓝藻紫外防护剂生物合成的影响

MAAs和Scytonemins是蓝藻细胞中的紫外防护剂,与蓝藻细胞的强抗逆性形成和水华爆发密切相关.研究了AHLs及结构类似物对水华蓝藻铜绿微囊藻(Microcystis aeruginosa)FABHE905和集胞藻(Synechocystis sp.)FACHB898 MAAs和Scytonemin合成的影响.结果表明:AHLs能有效促进两种蓝藻MAAs及Scytonemin的生物合成,并且这种促进作用与其含有的内酯环有关.通过干扰AHLs物质内酯环相关的信号传递,影响蓝藻细胞紫外防护剂合成和抗逆性形成,可以为寻找新的抑藻方法提供新的思路.     

Immuno-isolation of Sec7p-coated transport vesicles from the yeast secretory pathway.

The transport of proteins destined for post-endoplasmic reticulum locations in the secretory pathway is mediated by small vesicular carriers. Transport vesicles have been generated in cell-free assays from the yeast Saccharomyces cerevisiae, and mammalian systems. Yeast genes encoding cytosolic components that participate in vesicular traffic were first identified from the collection of conditional-lethal sec-(secretory) mutants. Mutations in the yeast SEC7 gene disrupt protein transport in the secretory pathway at the nonpermissive temperature. The SEC7 gene product is a phosphoprotein of relative molecular mass 230,000 that functions from the cytoplasmic aspect of intracellular membranes. We report that in a yeast cell-free transport assay, the introduction of antibodies to Sec7 protein (Sec7p) results in the accumulation of transport vesicles. These vesicles are retrieved with Sec7p-specific antibodies by immuno-isolation for biochemical and electron microscopic characterization. Sec7p on the surface of the accumulated transport vesicles, in combination with previous genetic and biochemical studies, implicate Sec7p as part of a (non-clathrin) vesicle coat. This Sec7p-containing coat structure is proposed to be essential for vesicle budding at multiple stages in the yeast secretory pathway.     

水体流动对鄱阳湖撮箕湖原水培养基中铜绿微囊藻生长的影响

为定量化研究水动力对鄱阳湖撮箕湖水体中蓝藻生长的影响,该文采用灭菌撮箕湖原水在光照培养箱中控温、控光的无菌条件下,使用自制有机玻璃环形槽进行水体流速控制试验.研究结果表明:在撮箕湖原水培养液中微囊藻的生长随水流速度的增加呈先增加后降低的变化趋势,当水流速度为45 cm·s-1时最有利于微囊藻的生长,微囊藻最大比生长速率...     

An open form of syntaxin bypasses the requirement for UNC-13 in vesicle priming.

The priming step of synaptic vesicle exocytosis is thought to require the formation of the SNARE complex, which comprises the proteins synaptobrevin, SNAP-25 and syntaxin. In solution syntaxin adopts a default, closed configuration that is incompatible with formation of the SNARE complex. Specifically, the amino terminus of syntaxin binds the SNARE motif and occludes interactions with the other SNARE proteins. The N terminus of syntaxin also binds the presynaptic protein UNC-13 (ref. 5). Studies in mouse, Drosophila and Caenorhabditis elegans suggest that UNC-13 functions at a post-docking step of exocytosis, most likely during synaptic vesicle priming. Therefore, UNC-13 binding to the N terminus of syntaxin may promote the open configuration of syntaxin. To test this model, we engineered mutations into C. elegans syntaxin that cause the protein to adopt the open configuration constitutively. Here we demonstrate that the open form of syntaxin can bypass the requirement for UNC-13 in synaptic vesicle priming. Thus, it is likely that UNC-13 primes synaptic vesicles for fusion by promoting the open configuration of syntaxin.     

Internal control of the coated vesicle pp50-specific kinase complex

The polyhedral surface lattice of coated vesicles consists of three-legged hexameric protein complexes called triskelions which constitute the basic assembly unit. The triskelion is a molecular complex of molecular weight 630,000 (Mr 630K) composed of three clathrin heavy chains (subunit 180K) and three light chains (subunits 33K and 36K) (refs 2,3). The presence of additional coated vesicle-specific proteins in the 100-130K and 50-55K range have been reported. We previously described the presence of a cyclic nucleotide- and Ca2+-independent protein kinase activity in coated vesicles which was confirmed by others. This protein kinase specifically phosphorylates the 50K protein (pp50). In this report, we show that the coated vesicle kinase and its 50K protein substrate are part of a stable multimolecular system. In addition we show that the clathrin-light chain complex stimulates the pp50 phosphorylation and only light chains are implicated in this stimulation and that the pp50 phosphorylation does not seem to be affected by the vesicle.     

RIM1alpha forms a protein scaffold for regulating neurotransmitter release at the active zone.

Neurotransmitters are released by synaptic vesicle fusion at the active zone. The active zone of a synapse mediates Ca2+-triggered neurotransmitter release, and integrates presynaptic signals in regulating this release. Much is known about the structure of active zones and synaptic vesicles, but the functional relation between their components is poorly understood. Here we show that RIM1alpha, an active zone protein that was identified as a putative effector for the synaptic vesicle protein Rab3A, interacts with several active zone molecules, including Munc13-1 (ref. 6) and alpha-liprins, to form a protein scaffold in the presynaptic nerve terminal. Abolishing the expression of RIM1alpha in mice shows that RIM1alpha is essential for maintaining normal probability of neurotransmitter release, and for regulating release during short-term synaptic plasticity. These data indicate that RIM1alpha has a central function in integrating active zone proteins and synaptic vesicles into a molecular scaffold that controls neurotransmitter release.     

A small GTP-binding protein dissociates from synaptic vesicles during exocytosis.

Low-molecular-weight GTP-binding proteins are strong candidates for regulators of membrane traffic. In yeast, mutations in the sec4 or ypt1 genes encoding small GTP-binding proteins inhibit constitutive membrane flow at the plasma membrane or Golgi complex, respectively. It has been suggested that membrane fusion-fission events are regulated by cycling of small GTP-binding proteins between a membrane-bound and free state, but although most of these small proteins are found in both soluble and tightly membrane-bound forms, there is no direct evidence to support such cycling. In rat brain a small GTP-binding protein, rab3A, is exclusively associated with synaptic vesicles, the secretory organelles of nerve terminals. Here we use isolated nerve terminals to study the fate of rab3A during synaptic vesicle exocytosis. We find that rab3A dissociates quantitatively from the vesicle membrane after Ca2(+)-dependent exocytosis and that this dissociation is partially reversible during recovery after stimulation. These results are direct evidence for an association-dissociation cycle of a small GTP-binding protein during traffic of its host membrane.     

The liprin protein SYD-2 regulates the differentiation of presynaptic termini in C. elegans.

At synaptic junctions, specialized subcellular structures occur in both pre- and postsynaptic cells. Most presynaptic termini contain electron-dense membrane structures, often referred to as active zones, which function in vesicle docking and release. The components of those active zones and how they are formed are largely unknown. We report here that a mutation in the Caenorhabditis elegans syd-2 (for synapse-defective) gene causes a diffused localization of several presynaptic proteins and of a synaptic-vesicle membrane associated green fluorescent protein (GFP) marker. Ultrastructural analysis revealed that the active zones of syd-2 mutants were significantly lengthened, whereas the total number of vesicles per synapse and the number of vesicles at the prominent active zones were comparable to those in wild-type animals. Synaptic transmission is partially impaired in syd-2 mutants. syd-2 encodes a member of the liprin (for LAR-interacting protein) family of proteins which interact with LAR-type (for leukocyte common antigen related) receptor proteins with tyrosine phosphatase activity (RPTPs). SYD-2 protein is localized at presynaptic termini independently of the presence of vesicles, and functions cell autonomously. We propose that SYD-2 regulates the differentiation of presynaptic termini in particular the formation of the active zone, by acting as an intracellular anchor for RPTP signalling at synaptic junctions.     

A role for ADP-ribosylation factor in nuclear vesicle dynamics.

Two distinct steps in nuclear envelope assembly can be assayed in vitro: the protein-mediated binding of nuclear-specific vesicles to chromatin, and the subsequent fusion of these vesicles to enclose the chromatin within a double nuclear membrane. Nuclear vesicle fusion, like fusion in the secretory pathway, requires ATP and cytosol and is inhibited by nonhydrolysable GTP analogues. The sensitivity of nuclear vesicle fusion to GTP-gamma S requires a GTP-dependent soluble factor, the properties of which are strikingly similar to a GTP-dependent Golgi binding factor (GGBF) that inhibits Golgi vesicle fusion in the presence of GTP-gamma S and belongs to the ADP-ribosylation factor (ARF) family of small GTPases. In the presence of GTP-gamma S, ARF proteins and alpha-, beta-, gamma-, delta-COP ('coatomer') subunits are associated with Golgi transport vesicles, but the exact roles of ARF proteins in secretion are not yet understood. We report here that purified ARF1 and GGBF have GTP-dependent soluble factor activity in the nuclear vesicle fusion assay. Our results show that the function of ARF is not limited to the Golgi apparatus, and indicate that there may be a link between the formation of nuclear vesicles during mitosis and proteins involved in secretion.     

Topological restriction of SNARE-dependent membrane fusion

To fuse transport vesicles with target membranes, proteins of the SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptors) complex must be located on both the vesicle (v-SNARE) and the target membrane (t-SNARE). In yeast, four integral membrane proteins, Sed5, Bos1, Sec22 and Bet1 (refs 2-6), each probably contribute a single helix to form the SNARE complex that is needed for transport from endoplasmic reticulum to Golgi. This generates a four-helix bundle, which ultimately mediates the actual fusion event. Here we explore how the anchoring arrangement of the four helices affects their ability to mediate fusion. We reconstituted two populations of phospholipid bilayer vesicles, with the individual SNARE proteins distributed in all possible combinations between them. Of the eight non-redundant permutations of four subunits distributed over two vesicle populations, only one results in membrane fusion. Fusion only occurs when the v-SNARE Bet1 is on one membrane and the syntaxin heavy chain Sed5 and its two light chains, Bos1 and Sec22, are on the other membrane where they form a functional t-SNARE. Thus, each SNARE protein is topologically restricted by design to function either as a v-SNARE or as part of a t-SNARE complex.     

SnO2-montmorillonite composite for removal and inhibition Microcystis aeruginosa assisted by UV-light

Cyanobacterial blooms have become a serious pollution problem,in particular,for water resources.Microcystis aeruginosa(M.aeruginosa)is most common toxic cyanobacterial bloom in fresh waters.In this paper,Sn O_2-montmorillonite composite was prepared by ion exchange method and applied to remove M.aeruginosa with the assistance of UV-light.The structure of the resulting composite was identified by XRD,IR and TEM.It was determined that some Sn O_2nanoparticles were inserted into the interlayer of montmorillonite and some were dispersed on the surface of montmorillonite.M.aeruginosa removal efficiency was judged by the rate of 95%after treatment with 0.3 g/L Sn O_2-montmorillonite for 1 h.Sn O_2-montmorillonite composite absorbed M.aeruginosa and promoted M.aeruginosa lysis by damaging cell wall and membrane.The cellular contents,including protein and chlorophyll a,were then degraded with the assistance of UV-light,which inhibited the biological activity of M.aeruginosa.In fact,Sn O_2-montmorillonite composite removed M.aeruginosa by combination of adsorption flocculation and UV-induced catalytic degradation.Sn O_2-montmorillonite shows promise to become an effective material for the removal of algae and the cyanobacteria bloom.