黄土高原不同发育阶段生物结皮的导水和持水特征

为探明黄土高原不同发育阶段生物结皮对土壤导水和持水特性的影响,以裸沙和不同发育阶段生物结皮(藻结皮、藻-藓混生结皮、藓结皮)为研究对象,分别采用定水头法和威尔科克斯法对其导水和持水特性进行了测定.结果表明,在0～10 cm土层,生物结皮显著降低了土壤饱和导水率,藻结皮、藻-藓混生结皮和藓结皮土壤的饱和导水率较裸沙分别平...     

放养不同数量白鲢对罗氏沼虾池塘蓝藻水华及水质的影响

该文旨在探讨在罗氏沼虾养殖后期放养白鲢对池塘水质及浮游植物种类与数量的影响。试验选取规格为80尾/kg白鲢鱼种,按放养数量分别为0(1号塘)、1000尾/667m^2(2号塘)、1500尾/667m^2(3号塘)、2000尾/667m^2(4号塘),投放到4个养殖条件相近的罗氏沼虾池塘中,每隔10d检测池塘水质指标和浮游藻类,共5次。结果显示,池塘pH值呈先下降后稳定的趋势;各组溶氧均有显著的提升;2号和4号池塘透明度提升速率明显高于对照组;各组氨氮、亚硝含量变化不明显。各组化学需氧量(CODCr)、总氮、总磷、修正营养状态指数(TSIM)均呈下降趋势,且试验组下降幅度高于对照组,其中4号池塘下降最为明显。试验组池塘蓝藻下降幅度均高于对照组,且随着投放鲢鱼数量的增大,蓝藻占水体浮游植物的百分比越小。结果表明,在罗氏沼虾养殖后期放养白鲢,能够改善养殖水体环境,降低水体富营养化程度,有效控制蓝藻水华的发生。     

Effect of inoculation of the cyanobacteria Oscillatoria sp. on tilapia biofloc culture

Cyanophytes are the most ancient photosynthetic organisms. During its evolution, they have developed various ecophysiological adaptation strategies to survive in extreme conditions. The environment prevailing under biofloc cultures provides various conditions appropriate for cyanobacterial proliferation. An outdoor experiment (7 weeks) was performed with a simple random design consisting of four inoculation levels (by triplicate) of Oscillatoria sp. (0.0, 0.1, 0.5 and 1 mg L^?1) in saltwater biofloc. The objective was to evaluate the effect of the cyanobacteria inoculation on water quality and tilapia production parameters. The results indicated that the amount of Oscillatoria sp. inoculated significantly affected water quality (pH, chlorophyll a, TSS and NO₃‐N) and tilapia parameters (final weight, feed conversion ratio, specific growth rate and survival). No significant effects on dissolved oxygen, total ammonia nitrogen (TAN) or NO₂‐N were observed. We recommend identifying the cyanobacteria species that are able to grow in a biofloc system and their possible adverse effects on the system.     

Hierridin B Isolated from a Marine Cyanobacterium Alters VDAC1, Mitochondrial Activity,and Cell Cycle Genes on HT-29 Colon Adenocarcinoma Cells

Background: Hierridin B was isolated from a marine cyanobacterium Cyanobium sp. strain and induced cytotoxicity selectively in HT-29 adenocarcinoma cells. The underlying molecular mechanism was not yet elucidated. Methods: HT-29 cells were exposed to the IC₅₀ concentration of hierridin B (100.2 μM) for 48 h. Non-targeted proteomics was performed using 2D gel electrophoresis and MALDI-TOF/TOF mass spectrometry. The mRNA expression of apoptotic and cell cycle genes were analyzed by real-time PCR. Automated quantification of 160 cytoplasm and mitochondrial parameter was done by fluorescence microscopy using CellProfiler software. Results: Proteomics identified 21 significant different proteins, which belonged to protein folding/synthesis and cell structure amongst others. Increase of VDAC1 protein responsible for formation of mitochondrial channels was confirmed by mRNA expression. A 10-fold decrease of cytoskeleton proteins (STMN1, TBCA) provided a link to alterations of the cell cycle. CCNB1 and CCNE mRNA were decreased two-fold, and P21CIP increased 10-fold, indicative of cell cycle arrest. Morphological analysis of mitochondrial parameter confirmed a reduced mitochondrial activity. Conclusion: Hierridin B is a potential anticancer compound that targets mitochondrial activity and function.     

Polymethoxy-1-alkenes from Aphanizomenon ovalisporum Inhibit Vertebrate Development in the Zebrafish (Danio rerio) Embryo Model

Cyanobacteria are recognized producers of a wide array of toxic or otherwise bioactive secondary metabolites. The present study utilized the zebrafish (Danio rerio) embryo as an aquatic animal model of vertebrate development to identify, purify and characterize lipophilic inhibitors of development (i.e., developmental toxins) from an isolate of the freshwater cyanobacterial species, Aphanizomenon ovalisporum.Bioassay-guided fractionation led to the purification, and subsequent chemical characterization, of an apparent homologous series of isotactic polymethoxy-1-alkenes (1–6), including three congeners (4–6) previously identified from the strain, and two variants previously identified from other species (2 and 3), as well as one apparently novel member of the series (1). Five of the PMAs in the series (1–5) were purified in sufficient quantity for comparative toxicological characterization, and toxicity in the zebrafish embryo model was found to generally correlate with relative chain length and/or methoxylation. Moreover, exposure of embryos to a combination of variants indicates an apparent synergistic interaction between the congeners. Although PMAs have been identified previously in cyanobacteria, this is the first report of their apparent toxicity. These results, along with the previously reported presence of the PMAs from several cyanobacterial species, suggest a possibly widespread distribution of the PMAs as toxic secondary metabolites and warrants further chemical and toxicological investigation.     

Cyanobacterial Toxic and Bioactive Peptides in Freshwater Bodies of Greece: Concentrations,Occurrence Patterns,and Implications for Human Health

Cyanobacterial harmful algal blooms represent one of the most conspicuous waterborne microbial hazards in aquatic environments mostly due to the production of toxic secondary metabolites, mainly microcystins (MCs). Other bioactive peptides are frequently found in cyanobacterial blooms, yet their concentration and ecological relevance is still unknown. In this paper we studied the presence and concentration of cyanobacterial peptides (microcystins, anabaenopeptins, anabaenopeptilides) in 36 Greek freshwater bodies, using HPLC-DAD, ELISA, and PP1IA. Microcystins were found in more than 90% of the samples investigated, indicating that microcystin-producing strains seem to also occur in lakes without blooms. Microcystins MC-RR, MC-LR, and MC-YR were the main toxin constituents of the bloom samples. Anabaenopeptin A and B were predominant in some samples, whereas anabaenopeptolide 90A was the only peptide found in Lake Mikri Prespa. The intracellular concentrations of anabaenopeptins produced by cyanobacterial bloom populations are determined for the first time in this study; the high (>1000 µg·L⁻¹) anabaenopeptin concentration found indicates there may be some impacts, at least on the ecology and the food web structure of the aquatic ecosystems. The maximum intracellular MC values measured in Lakes Kastoria and Pamvotis, exceeding 10,000 µg·L⁻¹, are among the highest reported.     

我国蓝藻水华遥感监测研究进展

近年来,蓝藻水华频繁暴发,成为备受关注的环境问题。遥感技术具有快速、大范围、动态的特点,在蓝藻水华监测中广泛应用。在总结我国蓝藻水华遥感监测研究成果的基础上,对现有研究中的数据源、研究方向进行了分析,对未来发展方向提出展望。     

蓝细菌中与PⅡ蛋白或NtcA蛋白相互作用的PipX蛋白的生物信息学分析

应用NCBI、Expasy等在线生物信息学网站与生物信息学软件对蓝细菌各菌株的PipX进行多序列同源对比分析,获得保守序列,预测了二级结构与结构域,分析了pipX的基因簇等。分别构建了蓝细菌的16S rDNA进化树以及基于PipX的分子进化树,同时也对与PipX相互作用的NtcA和PⅡ构建分子进化树进行了比较分析,了解它们之间起源与进化的关系。由此推测PipX可能是蓝细菌氮代谢途径中除NtcA、PⅡ外的另一个关键调控蛋白,有着重要的生理功能。     

Are Known Cyanotoxins Involved in the Toxicity of Picoplanktonic and Filamentous North Atlantic Marine Cyanobacteria?

Eight marine cyanobacteria strains of the genera Cyanobium, Leptolyngbya, Oscillatoria, Phormidium, and Synechococcus were isolated from rocky beaches along the Atlantic Portuguese central coast and tested for ecotoxicity. Strains were identified by morphological characteristics and by the amplification and sequentiation of the 16S rDNA. Bioactivity of dichloromethane, methanol and aqueous extracts was assessed by the Artemia salina bioassay. Peptide toxin production was screened by matrix assisted laser desorption/ionization time of flight mass spectrometry. Molecular analysis of the genes involved in the production of known cyanotoxins such as microcystins, nodularins and cylindrospermopsin was also performed. Strains were toxic to the brine shrimp A. salina nauplii with aqueous extracts being more toxic than the organic ones. Although mass spectrometry analysis did not reveal the production of microcystins or other known toxic peptides, a positive result for the presence of mcyE gene was found in one Leptolyngbya strain and one Oscillatoria strain. The extensive brine shrimp mortality points to the involvement of other unknown toxins, and the presence of a fragment of genes involved in the cyanotoxin production highlight the potential risk of cyanobacteria occurrence on the Atlantic coast.     

Marine benthic cyanobacteria contain apoptosis-inducing activity synergizing with daunorubicin to kill leukemia cells, but not cardiomyocytes

The potential of marine benthic cyanobacteria as a source of anticancer drug candidates was assessed in a screen for induction of cell death (apoptosis) in acute myeloid leukemia (AML) cells. Of the 41 marine cyanobacterial strains screened, more than half contained cell death-inducing activity. Several strains contained activity against AML cells, but not against non-malignant cells like hepatocytes and cardiomyoblasts. The apoptotic cell death induced by the various strains could be distinguished by the role of caspase activation and sensitivity to the recently detected chemotherapy-resistance-associated prosurvival protein LEDGF/p75. One strain (M44) was particularly promising since its activity counteracted the protective effect of LEDGF/p75 overexpressed in AML cells, acted synergistically with the anthracycline anticancer drug daunorubicin in AML cells, and protected cardiomyoblasts against the toxic effect of anthracyclines. We conclude that culturable benthic marine cyanobacteria from temperate environments provide a promising and hitherto underexploited source for novel antileukemic drugs.