食用蓝藻螺旋藻和葛仙米中金属元素的分析

采用硝酸和高氯酸(4∶1)混合酸消化2种可食用蓝藻螺旋藻和葛仙米,原子吸收光谱法检测螺旋藻和葛仙米中的K、Na、Mg、Ca、Zn、Fe、Cu、Mn、Cr、Pb和Cd共11种金属元素含量。结果表明,2种蓝藻中矿质元素含量均较高,特别是Ca含量高达61 905.132mg·kg~(-1);而有害重金属Cr,Po和Cd含量均远低于国家规定标准,表明这2种食用蓝藻均无重金属富集或污染。本结果显示,螺旋藻和葛仙米是极好的天然富钙营养食品,可作为人体矿质元素和微量元素缺乏症的补给品.     

基于遥感影像光谱分析的蓝藻水华识别方法

利用Landsat-7 ETM+遥感影像数据,以淀山湖为例,在分析蓝藻和其他典型地物影像光谱曲线及其特征的基础上,构建归一化蓝藻指数(NDI_CB),有效地从浑浊水体中提取蓝藻信息.通过k-均值非监督分类结果可以发现,构建的归一化蓝藻指数较传统的归一化差值植被指数(NDVI)和比值植被指数(RVI)更加适用于提取低密度蓝藻空间分布信息.在此基础上,基于遥感影像光谱特征和归一化蓝藻指数,采用了支持向量机的分类识别模型,最终得到淀山湖区域蓝藻的空间分布范围与面积,通过发现在某一特定时间蓝藻分布的规律,为蓝藻预警和治理的生态学分析提供了及时、有效和客观的依据.     

淀山湖蓝藻水华暴发的气象水文因素探讨

2007-2009年淀山湖的总氮和总磷年均浓度分别为3.47～4.53 mg/L和0.18～0.24mg/L,明显高于富营养化水平,成为蓝藻水华暴发的重要物质基础.MODIS影像分析结果表明,2007-2009年蓝藻水华暴发频次分别为3,6,10 d,呈逐年上升的趋势,并且暴发后易于集中在湖中心、东北和东部水域.受黄浦...     

Sequence analysis of the Microcystis aeruginosa FACHB-912 phytochrome gene supports positive selection in cyanobacteria

The phytochrome gene from Microcystis aeruginosa FACHB-912,isolated from algal blooms in Taihu Lake in China,was sequenced and found to code for a wavelength transition light receptor protein.The gene was composed of five distinct domains:a PAS fold domain,a GAF domain,a phytochrome domain,a His Kinase A(phosphoacceptor) domain,and a histidine kinase domain.Red-absorbing phytochrome,far-red-absorbing phytochrome,and photoconversion kinetics were monitored via the spectral characteristics of the protein.To detect positive selection,homologous sequences from cyanobacterium phytochrome genes were obtained from GenBank.Potential selective pressure was identified by phylogenetic analysis with maximum likelihood analyses.The frequency of the phytochrome gene being subjected to selective constraints suggests that positive selection is a potentially important mechanism that promotes the evolution of the cyanobacteria phytochrome gene.The sites identified in this study provide targets for further research on the structural-functional role of these residues,and on the correlation with the mechanism of algal blooms.     

丝状体蓝藻殖段分化的影响因子及其调节机制

本文阐述了丝状体蓝藻等灌殖段分化的影响因子——环境因子、离子等对分化的影响，对分化的调节机制也作了一定的阐述，指出光受体、谷氨酸等合成酶的合成和活性调节的Pn蛋白具有重要的作用。     

变化风场下太湖表层湖流特征及其对蓝藻迁移的影响

为了解太湖表层湖流对变化风场的响应特征,以及风场表层流场对蓝藻迁移的影响,通过GPS粒子示踪器对表层湖流进行观测,结合观测期间风场的变化特征和遥感图像,分析了变化风场条件下太湖的表层湖流特征以及蓝藻水华的迁移聚集过程。结果表明:太湖风场是太湖表层流场的主要驱动力,但受到地形特征、岸线特征等因素的影响,不同水域表层流场对风场的响应并不完全一致;太湖风场影响下太湖表层湖流在空间上的广泛差异性是导致蓝藻迁移过程中在不同区域聚集程度不同的主导因素,也是区域性蓝藻水华暴发的重要原因之一。风场表层流场蓝藻迁移聚集过程是一个依次传导的响应系统,条件适宜风场影响下的流场是触发蓝藻水华短时间、大面积暴发的重要外部因素。     

ApcD is required for state transition but not involved in blue-light induced quenching in the cyanobacterium Anabaena sp.PCC7120

Pbycobilisomes(PBS) are able to transfer absorbed energy to photosystem I and Ⅱ,and the distribution of light energy between two photosystems is regulated by state transitions.In this study we show that energy transfer from PBS to photosystem I(PSI) requires ApcD.Cells were unable to perform state transitions in the absence of ApcD.The apcD mutant grows more slowly in light mainly absorbed by PBS,indicating that ApcD-dependent energy transfer to PSI is required for optimal growth under this condition.The apcD mutant showed normal blue-light induced quenching,suggesting that ApcD is not required for this process and state transitions are independent of blue-light induced quenching.Under nitrogen fixing condition,the growth rates of the wild type and the mutant were the same,indicating that energy transfer from PBS to PSI in heterocysts was not required for nitrogen fixation.     

Filamentous cyanobacteria fossils and their significance in the Permian-Triassic boundary section at Laolongdong, Chongqing

The microbial communities blooming immediately after the end-Permian mass extinction represent abnormally extreme environments, and vary in different areas. In this study, filamentous cyanobacterial biota was found in the strata after the extinction in the famous Permian-Triassic boundary section at Laolongdong, Chongqing, southwest China. In thin sections, the filamentous cyanobacterial fossils are below 1 mm in length, and generally taper to one end, with the widest diameter up to 0.08 mm. Some of them are curved, indicating that they are soft in life. Their walls are composed of cryptocrystalline to microcrystalline calcites. The filaments have round cross section, and are internally filled with micrites and fine sparry calcites, which indicate that the filaments are originally empty. They are randomly distributed in the rocks, but in some places, they tend to be distributed in radial pattern. The filamentous organisms are morphologically similar to Rivularia of Rivulariaceae, Cyanobacteria Phylum, but with calcified sheaths, and are tentatively regarded as an indeterminate new species in Rivularia： Rivularia sp. Cyanobacteria are photosynthetic autotrophic, and can survive in dysoxic condition. The blooming of this organism and the absence of other organisms may indicate that the environment was oxygendeficient and shallow, since this photosynthetic autotrophic organism needed to live within photic.     

Plectonema boryanum作为外源质粒受体的筛选及其原生质球的制备与再生

对三种丝状蓝藻株系（ＰｈｏｒｍｉｄｉｕｍＬｕｒｉｄｕｍ，Ｐｈｏｒｍｉｄｉｕｍｆａｖｅｏｌａｒｕｍ和Ｐｌｅｃｔｏｎｅｍａｂｏ－ｒｙａｍｕｍ）的研究结果表明：Ｐ，ｂｏｒｙａｎｕｍ因无明显限制性内切核酸酶活性可作为受体进一步研究，对其原生质球的释出和新细胞再生的最适条件分析表明：０．１％溶菌酶作用的最适时间为２ｈ温度为３５℃，ｐＨ为７．０～７．５（０．８ｍｏｌ／Ｌ的甘露醇为最适渗透稳定剂）。这些条件适合于在ＢＧ－１１液体中释放原生质球及固体培养基上新细胞的再生。     

Relationship between topology and functions in metabolic network evolution

What is the relationship between the topological connections among enzymes and their functions during metabolic network evolution? Does this relationship show similarity among closely related organisms? Here we investigated the relationship between enzyme connectivity and functions in metabolic networks of chloroplast and its endosymbiotic ancestor, cyanobacteria (Synechococcus sp. WH8102). Also several other species, including E. coli, Arabidopsis thaliana and Cyanidioschyzon merolae, were used for the comparison. We found that the average connectivity among different functional pathways and enzyme classifications (EC) was different in all the species examined. However, the average connectivity of enzymes in the same functional classification was quite similar between chloroplast and one representative of cyanobacteria, syw. In addition, the enzymes in the highly conserved modules between chloroplast and syw, such as amino acid metabolism, were highly connected compared with other modules. We also discovered that the isozymes of chloroplast and syw often had higher connectivity, corresponded to primary metabolism and also existed in conserved module. In conclusion, despite the drastic re-organization of metabolism in chloroplast during endosymbiosis, the relationship between network topology and functions is very similar between chloroplast and its precursor cyanobacteria, which demonstrates that the relationship may be used as an indicator of the closeness in evolution.