铜绿微囊藻光合作用的昼夜节律变化

用氧电极对铜绿微囊藻Microcystis aeruginosa PCC7820的光合作用节律进行了研究,结果表明,在光照-黑暗(L/D)周期环境下该藻的光合作用速率呈现明显的昼高夜低近似24h的周期性变化,这种近似昼夜节律变化在连续光照的条件下至少能持续运行3个周期.L/D周期的改变能影响光合节律的相位,经反光周期处理后的藻液其光合放氧节律也随之发生反相变化.此外,光合节律相位还受到温度的影响,但节律周期在20～28℃范围内并不会发生显著改变,即具有温度补偿效应.因此,铜绿微囊藻的光合作用受到生物钟的调控,而温度和光照的改变能重置生物钟的时相.     

Differentiation of microcystin, nodularin, and their component amino acids by drop-coating deposition Raman spectroscopy

Raman spectra of microcystin-LR (MC-LR), MC-RR, MC-LA, MC-LF, MC-LY, MC-LW, MC-YR, and nodularin collected by drop-coating deposition Raman (DCDR) spectroscopy are sufficiently unique for variant identification. Amino acid spectra of L-phenylalanine, L-leucine, L-alanine, D-alanine, L-glutamic acid, L-arginine, L-tryptophan, L-tyrosine, and N-methyl-D-aspartic acid were collected in crystalline, DCDR, and aqueous forms to aid in cyanotoxin Raman peak assignments. Both peak ratio analysis and principal component analysis (PCA) properly classified 72 DCDR spectra belonging to the eight toxins. Loading plots for the first three principal components (PCs) most heavily weighted the peaks highlighted in the peak ratio analysis, specifically the 760 cm(-1) tryptophan peak, 853 cm(-1) tyrosine peak, and 1006 cm(-1) phenylalanine peak. Peak ratio analyses may be preferred under some circumstances because of the ease and speed with which the ratios can be computed, even by untrained lab technicians. A set of rules was created to mathematically classify toxins using the peak ratios. DCDR methods hold great potential for future application in routine monitoring because portable and hand-held Raman spectrometers are commercially available, DCDR spectra can be collected in seconds for biomolecule mixtures as well as samples containing impurities, and the method requires far fewer consumables than conventional cyanotoxin detection methods.     

Identification of microcystin toxins from a strain of Microcystis aeruginosa by liquid chromatography introduction into a hybrid linear ion trap-Fourier transform ion cyclotron resonance mass spectrometer

The cyclic heptapeptide microcystin toxins produced by a strain of Microcystis aeruginosa that has not been investigated previously were separated by liquid chromatography and identified by high-accuracy m/z measurements of their [M + H]+ ions and the fragment ions produced by collision-activated dissociation of the [M + H]+ ions. The cyanobacteria B2666 strain was cultured in a standard growth medium, and the toxins were released from the cells, extracted from the aqueous phase, and concentrated using standard procedures. The microcystins were separated by reversed-phase microbore liquid chromatography and introduced directly into a hybrid linear ion trap-Fourier transform ion cyclotron resonance mass spectrometer with electrospray ionization. The known microcystins (MC) MC-LR, MC-LA, [MeSer7]MC-LR, MC-LL, MC-LF, and MC-L(Aba) were identified along with the two previously unreported structural variants [Asp3]MC-LA and [Asp3]MC-LL. In addition to the [M + H]+ ions, accurate m/z measurements were made of 12-18 product ions for each identified microcystin. The mean difference between measured and calculated exact m/z was less than 2 parts per million, which often allowed assignment of unique compositions to the observed ions. A mechanism is presented that accounts for an important collision-activated dissociation process that gives valuable sequence ions from microcystins that do not contain arginine. The analytical technique used in this work is capable of supporting fairly rapid and very reliable identifications of known microcystins when standards are not available and of most structural variants independent of additional information from other analytical techniques.     

Hydrothermal decomposition of yeast cells for production of proteins and amino acids

This study examines hydrothermal decomposition of Baker's yeast cells, used as a model for spent Brewer's yeast waste, into protein and amino acids. The reaction was carried out in a closed batch reactor at various temperatures between 100 and 250 degrees C. The reaction products were separated into water-soluble and solid residue. The results demonstrated that the amount of yeast residue decreased with increasing hydrolysis temperature. After 20 min reaction in water at 250 degrees C, 78% of yeast was decomposed. The highest amount of protein produced was also obtained at this condition and was found to be 0.16 mg/mg dry yeast. The highest amount of amino acids (0.063 mg/mg dry yeast) was found at the lowest temperature tested after 15 min. The hydrolysis product obtained at 200 degrees C was tested as a nutrient source for yeast growth. The growth of yeast cells in the culture medium containing 2 w/v% of this product was comparable to that of the cells grown in the medium containing commercial yeast extract at the same concentration. These results demonstrated the feasibility of using subcritical water to potentially decompose proteinaceous waste such as spent Brewer's yeast while recovering more useful products.     

铜绿微囊藻(Microcystis aeruginosa)蛋白质组学研究方法的初步建立

参照一些植物蛋白的提取方法,初步确定了铜绿微囊藻总蛋白的提取方法,即TCA-丙酮法,并采用蛋白质组学技术路线,即双向凝胶电泳(2-D PAGE)及基质辅助激光解吸离子化-飞行时间质谱(MALDI-TOF)分析,建立了铜绿微囊藻在对数生长期的蛋白质组分子解剖图谱.将铜绿微囊藻接种于BG-11培养基28℃培养至对数生长期,提取藻种总蛋白进行双向电泳.从2-D PAGE图谱中随机选取110个蛋白质点进行肽质量指纹图谱(PMF)鉴定,检索发现21个确定为数据库中收录的蓝藻的基因或蛋白,其中10个为数据库中收录的聚球藻Synechococcus sp.PCC6803或微囊藻的基因或蛋白.     

铜绿微囊藻Microcystis aeruginosa PCC7820 ATP含量和细胞分裂昼夜节律的研究

为了研究铜绿微囊藻Microcystis aeruginosa PCC7820中是否存在内源昼夜节律,检测了其细胞中的三磷酸腺苷(ATP)含量和细胞分裂的日变化规律.通过生物发光法检测的细胞内ATP含量变化结果表明,在12h光/12h暗(L/D)周期环境下该藻的ATP含量呈现明显的近似24h的昼夜周期性变化,且这种周期性变化在连续光照条件下能至少持续运行3个周期,周期长度具有温度补偿效应, 而光照和温度的改变能重置昼夜节律的时相,这说明铜绿微囊藻ATP含量的昼夜节律变化受到内源生物钟的控制.通过对细胞数、细胞大小和细胞分裂素含量的检测发现,传代时间为38.4h的铜绿微囊藻的细胞分裂也呈现受生物钟调控的昼夜节律性,这种昼夜节律变化可能是生物钟通过一种门控机制调控M. aeruginosa PCC7820的细胞分裂时相而产生的.     

Indirect fluorescence detection of amino acids on electrophoretic microchips

Microfabricated devices enable rapid separations of a variety of clinically significant analytes, including DNA, proteins, and amino acids. However, absorbance detection has been difficult to achieve on these devices, prohibiting analysis of nonfluorophore-bearing or nonfluorescently tagged analytes. An alternative detection technique exploiting indirect fluorescence has been adapted to the electrophoretic microchip to provide fast analysis of amino acids, bypassing the need for absorbance detection or fluorescence derivitization procedures. Nineteen of the standard amino acids could be detected with an average detection limit of 32.9 microM (approximately 1.6 amol). Despite the fact that the detection sensitivity was lower than that achievable by labeling the amino acids with fluorescein isothiocyanate (approximately 1 nM), circumventing sample preparation and the difficulties inherent with tagging complex samples make this technique attractive for a variety of assays where sensitivity is not critical. To demonstrate the applicability to real sample matrixes, the analysis of urine with elevated amino acid levels is used as a model system where the elevated levels are indicative of a variety of pathologies including amino acid metabolism disorders and kidney malfunction. The minimal sample handling and rapid separations achievable by employing indirect detection on microchips provides the potential for high-throughput applications for certain amino acid analyses.     

Effects of Fe/SDS and Au nanoparticles on P. aeruginosa bacterial growth and biosurfactant production

The aim of this study was to evaluate the effects of iron (Fe)/SDS and gold (Au) nanoparticles on growth and biosurfactant production of Pseudomonas aeruginosa PBCC5. The concentrations of the nanoparticles used were 1, 500 and 1000 mg/l. In this research, the surface tension of biosurfactant, dry weight of biosurfactant and biomass, emulsification indexes (E₂₄) were measured and transmission electron microscopy analysis was used to monitor the nanoparticles. The test results showed that the effect of nanoparticles on the bacterial growth and biosurfactant production varied corresponding to the type and concentration of nanoparticles. Fe/SDS nanoparticles showed no bacterial toxicity when the concentration of nanoparticles was 1 mg/ml and increased the growth and biosurfactant production, 23.21 and 20.73%, respectively. While at higher concentrations (500, 1000 mg/l), the nanoparticles suppressed bacterial growth as well as biosurfactant production. Similarly, Au nanoparticles had no bacterial toxicity and also increased bacterial growth and biosurfactant production. The surface tensions of all samples decreased from 72 of distiled water to 32–35 mN/m.Inspec keywords: nanoparticles, iron, gold, nanofabrication, nanomedicine, surfactants, biomedical materials, surface tension, renewable materials, transmission electron microscopy, microorganismsOther keywords: Au nanoparticles, P. aeruginosa bacterial growth, biosurfactant production, Pseudomonas aeruginosa PBCC5, surface tension, biomass, emulsification indexes, dry weight, transmission electron microscopy, Fe‐SDS nanoparticles, distiled water, Fe, Au     

氨基酸离子液体应用研究进展

氨基酸离子液体是一类新型的功能化离子液体,除了具有常规离子液体的低蒸汽压、低熔点、宽液程、溶解性好和稳定性高等性质外,还具有很强的氢键网络结构、稳定的手性中心、双配位基团、生物兼容性和可生物降解等许多独特的性质。本文综述了近年来氨基酸离子液体在溶解生物质、气体吸收、手性分离、催化等方面的应用研究进展。     

铜绿微囊藻Microcystis aeruginosa PCC7820生物钟基因的克隆及其蛋白相互作用分析

为了深入研究铜绿微囊藻生物钟调控的分子机制,根据蓝藻钟基因的同源序列设计合成了简并引物,通过PCR和染色体步行的方法获得了铜绿微藻Microcystis aeruginosa PCC7820的生物钟基因簇kaiABC.kaiA基因全长873bp,编码一个由290αα组成,分子量大小为33.3kDa的蛋白;kaiB基因全长315bp,编码分子量大小为11.8kDa的蛋白;kaiC基因全长1563 bp,编码蛋白分子量大小为58.3kDa.Kai蛋白间的相互作用是昼夜节律计时产生的重要过程,利用酵母双杂交系统检测了三种Kai蛋白间的相互作用,结果表明KaiA、KaiB和KaiC蛋白自身及KaiA与KaiC、KaiB与KaiC之间都能发生明显的相互作用,而KaiB和KaiA之间没有检测到相互作用.     

Temperature and irradiance influences on cadmium and zinc uptake and toxicity in a freshwater cyanobacterium, Microcystis aeruginosa

Temperature and light irradiance are important factors affecting the occurrence of cyanobacterial blooms. In this study, we examined the influences of different temperatures (15, 24, and 30°C) and irradiances (18, 32, and 55 μmol photons m(-2)s(-1)) on the uptake and toxicity of cadmium (Cd) and zinc (Zn) in a freshwater cyanobacterium Microcystis aeruginosa. The subcellular distribution of Cd and Zn was analyzed. Enhanced growth rates were observed for the cyanobacterial cells incubated at higher temperature or irradiance conditions with lower metal concentrations. With increasing ambient Cd or Zn concentrations, both cellular growth rate and photosynthesis were significantly inhibited at elevated irradiance conditions. The observed increase in Cd and Zn toxicity might be attributed to the enhanced metal uptake and accumulation in Microcystis. Based on the intracellular Cd concentration, the 50% inhibition concentration (IC(50)) values were higher at the higher temperature or irradiance treatment. The subcellular distribution demonstrated that Cd in the metal rich granule (MRG) faction increased with elevated [Cd(2+)] concentration, suggesting that MRG may partially detoxify the Cd toxicity in the cyanobacterial cells. This study implied that temperature and irradiance may influence the biogeochemical cycling of metals during cyanobacterial blooming in eutrophic freshwater ecosystems.     

乳状液膜法分离氨基酸的动力学

探讨了含载体P2 0 4 (磷酸二异辛酯 )的液膜体系用于苯丙氨酸促进运输的动力学行为 .采用液滴法装置 ,控制实验条件 ,测定了内相氢离子浓度随时间的变化 ,适用于有机相界面的化学反应对溶质传递的影响 ,并将计算的结果同实验相比较 ,建立了水相 -有机相界面化学反应对溶质传质具有决定作用时的传质模型     

生物降解氨基酸衍生聚合物的研究进展

氨基酸衍生聚合物具有良好的生物相容性和生物活性,且降解产物无毒,是一种非常理想的生物材料,可在不同的生物医用领域发挥作用.本文介绍了可降解生物材料的发展历程,比较了各类材料的优劣,详细介绍了拟聚氨基酸生物材料的合成、性质以及国内外研究现状.     

Effects of amino group on the properties of carbon nanotubes

The surfaces of multi-walled carbon nanotubes were grafted with amino functional groups by reacting acyl-chloride-functionalized carbon nanotubes (CNTs) with hexamethylene diamine, which improves the surfactivity of CNTs. The dispersity, surface morphology, and thermogravimetry of acid-treated and amino-functionalized CNTs were investigated. Amino-functionalized CNTs were added into epoxy resin to analyze the effects of amino functional groups on the properties of resin composites. It was found that the properties of CNTs, such as morphology and scale, were not affected by amino functional groups, but the dispersity in water was highly improved. Amino-functionalized CNTs are better dispersed in resin matrix, and the mechanical properties of composites are improved significantly, whereas the conductivity of composites is not enhanced as expected.