Indole Alkaloids of the Stigonematales (Cyanophyta): Chemical Diversity,Biosynthesis and Biological Activity

The cyanobacteria are well recognized as producers of a wide array of bioactive metabolites including toxins, and potential drug candidates. However, a limited number of taxa are generally considered with respect to both of these aspects. That said, the order Stigonematales, although largely overlooked in this regard, has become increasingly recognized as a source of bioactive metabolites relevant to both human and environmental health. In particular, the hapalindoles and related indole alkaloids (i.e., ambiguines, fischerindoles, welwitindolinones) from the order, represent a diverse, and phylogenetically characteristic, class of secondary metabolites with biological activity suggestive of potential as both environmental toxins, and promising drug discovery leads. The present review gives an overview of the chemical diversity of biologically active metabolites from the Stigonematales—and particularly the so-called hapalindole-type alkaloids—including their biosynthetic origins, and their pharmacologically and toxicologically relevant bioactivities. Taken together, the current evidence suggests that these alkaloids, and the associated cyanobacterial taxa from the order, warrant future consideration as both potentially harmful (i.e., “toxic”) algae, and as promising leads for drug discovery.     

惠州地区小型村镇水源产毒蓝藻污染初探

为了揭示惠州地区农村小型水源产毒蓝藻污染情况,从惠州村镇采取不同类型水源地的水样,分别利用分子生物学和HPLC方法分析水样中的产毒蓝藻污染情况和微囊藻毒素含量。通过微囊藻毒素合成基因片段mcyA-Cd的检测发现,在采取的27个水样中,12个水样已经被产毒蓝藻污染。PCR-DGGE和克隆测序的结果证明,利用mcyA-Cd基因对环境样品中的产毒蓝藻进行初步检测具有较高的特异性和准确性,所有样品中只有一个样品检出来自阿氏浮丝藻属的产毒蓝藻,其他检出的产毒蓝藻均为微囊藻属;HPLC分析结果显示,8个水样检出微囊藻毒素,其中5个样品超过1μg.L-1。研究结果表明,mcyA-Cd基因可以用于快速、准确的对环境样品中的产毒蓝藻进行初步检测;采样区域部分水源地已经被产毒蓝藻污染,应该采取相应措施对惠州地区农村水源地进行产毒蓝藻的监测,防止或减少微囊藻毒素对人产生的危害。     

滇池打捞蓝藻总氮含量检测方法研究

 水体富营养化是蓝藻爆发的主要原因,污染水体中的蓝藻打捞是水环境治理的重要措施之一。目前没有检测打捞上岸的泥状蓝藻（藻泥）总氮（TN）含量的标准方法。为得到科学的计量打捞蓝藻含TN检测方法,供政府支付滇池水体污染物去除补偿计量使用,本文通过对从滇池中打捞的17批次37个蓝藻抽检样品,用鲜、干两样品状态分别采用LY/T1269—1999和NY525—2002两种标准方法进行蓝藻TN含量检测,并对检测结果进行配对t测验和偏差值分析。结果是：用鲜样测定蓝藻TN时,LY/T1269—1999方法和NY525—2002方法之间无显著差异、偏差小,两方法均可;而用风干样测定时NY525—2002方法的结果显著偏高,且高于其他没有显著差异的3种测定结果。同时,用NY525—2002方法测定风干样蓝藻TN的变异系数为1576%,远高于其他3种约11%~12%的变异系数。研究确定采用105℃烘箱法测定蓝藻含水率、LY/T1269—1999方法测定蓝藻TN,适用于打捞蓝藻去除的氮污染物的检测方法。     

Combined application of cyanobacteria with soil fixing chemicals for rapid induction of biological soil crust formation

Combined applications of cyanobacteria with soil fixing chemicals were investigated to generate artificially induced biological soil crust (BSC). Polyvinyl alcohol (PVA) and Tacki-Spray (TKS7) chemicals composed of bio-polysaccharides and tackifiers were examined under laboratory conditions. Following singular applications of chemicals, the mean weight diameter values of soil treated with TKS7 were 1.4–2.5 times higher than those of soil treated with PVA and thus TKS7 was selected for further tests for application with cyanobacteria (Nostoc Vaucher ex Bornet &; Flahault, Phormidium Kützing ex Gomont, and Scytonema arcangeli Bornet ex Flahault). Combined application of cyanobacteria and different concentrations of TKS7 enhanced soil aggregate stability, resulting in mean weight diameter values of 0.58–0.69 mm and was comparable to TKS7 singular application (0.18–0.40 mm). Surface hardness values were also highly improved by the combined application of cyanobacteria with TKS7 (4.5 MPa) compared to singular treatment of cyanobacteria (2.3 MPa). In addition, superabsorbent polymer (SAP) was applied as a water-holding material and nutrient supplement in soil. The SAP promoted cyanobacterial cell growth under dry conditions. Chlorophyll a content of soil was improved by the addition of SAP (CST1: 2.93 µg g^?1) compared to singular treatment of cyanobacteria (C: 2.25 µg g^?1). These results suggest that combined application of cyanobacteria with TKS7 and SAP can induce BSC formation faster than singular application of cyanobacteria. The novel method presented herein can be applied to restoration of degraded soils in arid and semiarid areas.     

微生物菌群JSM004对微囊藻毒素的生物降解

以太湖水华蓝藻中提取纯化的微囊藻毒素(microcystins,MCs)作为微生物生长的碳源和氮源,从富营养化的太湖水体中分离筛选到MCs高效降解菌群JSM004,24 h内可以将初始浓度分别为3.64和2.62 mg·L-1的MC-RR和MC-LR完全降解.在研究关于环境因子对JSM004降解效率的影响中,发现菌群JSM004的生长受温度和pH值影响较大,而且其对MCs的降解效率也随之变化.结果表明,在接近实际水体的中性和弱碱性环境中,JSM004对MCs的降解活性最强,加入不同含碳和含氮化合物能够促进混合微生物菌群的生长,但是对MCs的降解却有明显的延滞作用.与对照组相比,MCs被完全降解的时间至少推迟24 h.在实验室条件下,JSM004可在72 h内完全降解太湖水中高浓度的MCs.研究结果表明微囊藻毒素降解菌群JSM004具有良好的MCs降解效果,有实际应用前景.     

Influence of Low Salt Concentration on Growth Behavior and General Biomass Composition in Lyngbya purpurem (Cyanobacteria)

Cyanobacteria are essential for the vast number of compounds they produce and the possible applications in the pharmaceutical, cosmetical, and food industries. As Lyngbya species’ characterization is limited in the literature, we characterize this cyanobacterium’s growth and biomass. L. purpureum was grown and analyzed under different salinities, culture media, and incubation times to determine the best conditions that favor its cell growth and the general production of proteins, carbohydrates, lipids, and some pigments as phycocyanin and chlorophyll a. In this study, each analyzed biomolecule’s highest content was proteins 431.69 mg g⁻¹, carbohydrates 301.45 mg g⁻¹, lipids 131.5 mg g⁻¹, chlorophyll a 4.09 mg g⁻¹, and phycocyanin 40.4 mg g⁻¹. These results can provide a general context of the possible uses that can be given to biomass and give an opening to investigate possible biocompounds or bio metabolites that can be obtained from it.     

水分含量对蓝藻堆肥腐熟及藻毒素含量的影响

为探索和优化开放环境中蓝藻堆肥的腐熟化、无害化处理工艺参数,以蓝藻为原料,菌渣和稻壳为调理剂进行好氧堆肥,研究了初始含水率为50%(W50%)、55%(W55%)和60%(W60%)的处理对堆肥腐殖化进程及微囊藻毒素(M C)降解速率的影响。结果表明:堆肥48d后,各处理成品均已满足有机肥标准,种子发芽指数高于85%;3种含水量条件下,腐殖质含量分别下降23.16%、21.71%和19.50%;胡敏酸含量分别提高69.40%、60.58%和43.89%;富里酸含量分别下降50.30%、50.09%和40.36%;腐质化系数(胡敏酸/富里酸)分别为2.85、2.94和2.23,增幅为141.27%~240.81%。堆制48d,MC-LR和MC-RR含量均低于1μg kg-1,降解率高于95%;各处理组中,MC-LR和MC-RR降解速率变化趋势相似,且MC-RR的降解速率高于MC-LR。研究表明,W 50%和W55%处理有利于形成腐殖类物质,提高堆体腐熟度,W 55%处理MC的降解效果最好。     

Slr0351的表达及其在Synechocystis sp. PCC 6803中功能的初步研究

Slr0351是Synechocystis sp.PCC 6803中的未知功能蛋白,其同源蛋白广泛存在于各种蓝藻和铁硫杆菌中.为了确定S1r0351的性质,构建了表达质粒pET-slr0351,并在E.coli中表达Slr0351.在无氧条件下采用亲和层析纯化方法获得了Slr0351,无氧条件下Slr0351呈棕红色,在460 nm处有[2Fe-2S]铁硫簇的特征吸收峰,棕红色Slr0351对氧气敏感,能被连二亚硫酸钠还原,由此表明Slr0351为铁硫蛋白.为了获知slr0351的功能,基于基因同源重组交换的原理,利用Kana抗性片段替换slr0351,将Synechocystis sp.PCC 6803中的slr0351基因缺失,构建了△slr0351突变体.利用紫外-可见吸收光谱仪扫描了△slr0351与野生型Synechocystis sp.PCC 6803 (WT)的吸收光谱,发现正常光照条件下△slr0351的叶绿素a仅为WT的68.8％,slr0351的缺失使蓝藻中叶绿素a含量降低.比较了藻细胞在缺乏不同营养元素和不同光照条件下的生长速率差异,与WT相比,△slr0351具有如下特征:(1)对缺Fe和缺S胁迫条件更敏感;(2)在弱光照条件下△slr0351的光能利用效率和生长速率更低,该现象与△slr351中叶绿素a含量的降低有关.     

Effects of purified microcystin-LR and cell extracts of Microcystis strains PCC 7813 and CYA 43 on cardiac function in brown trout (Salmo trutta) alevins

Sub-lethal cardiac responses of brown trout alevins (Salmo trutta L.) were determined in response to aqueous extracts of the cyanobacterium Microcystis strains PCC 7813 (microcystins detectable by HPLC) and CYA 43 (no microcystins detectable by HPLC) and to the purified cyanobacterial hepatotoxin, microcystin-LR (MC-LR) at concentrations of 5, 50 and 500 g microcystin-LR equivalents l^–1. Responses were determined using a flow chamber and video camera attached to a low power microscope. Heart rate in brown trout alevins was acutely sensitive to cyanobacterial extracts and significant increases were observed within 15–60 sec of exposure to aqueous extracts, although no change was observed on exposure to purified MC-LR. Stroke volume increased in all treatments at 50 and 500 g MC-LR equivalents l^–1, which may, at least in part, have been due to vasodilation of the yolk-sac blood vessels. Cardiac output increased significantly at all three concentrations of cyanobacterial cell extracts but not at the lowest concentration of MC-LR, although the rate increased at levels at/or above 50 g l^–1. Increased heart rate, stroke volume and cardiac output occurred at environmentally relevant microcystin concentrations of Microcystis PCC 7813 and CYA 43 aqueous extracts.     

Trophic stability in an Irish mesotrophic lake: Lough Melvin

• 1. Mesotrophic lakes are a threatened habitat in the United Kingdom (UK), and are specified within the UK Biodiversity Action Plan (UKBAP) as requiring protection. Lough Melvin is a large mesotrophic lake that is of particular interest owing to the genetic diversity of its brown trout, but it is currently showing signs of nutrient enrichment.
• 2. In 1990, average lake total phosphorus (TP) was less than 19 µg P L^?1 but increased to 29.5 µg P L^?1 by July 2001. Inflow TP also increased from 34 µg P L^?1 to 41 µg P L^?1 over the same period. Neither phosphorus nor nitrogen appeared to be limiting.
• 3. Despite higher lake TP, annual chlorophyll a did not increase, remaining less than 5 µg L^?1. The phytoplankton was dominated by cyanobacteria and seems to have remained unchanged since the 1950s. Rotifer numbers increased significantly after 2001 but the macro‐zooplankton did not. The absence of a phytoplankton response to P enrichment is attributed to light limitation caused by peat staining and thorough mixing.
• 4. In the catchment, an accelerated programme of clear‐felling began in 1999. Recent changes in the lake are consistent with the known impacts of clear‐felling conifers on peat soils, namely larger P and dissolved organic carbon (DOC) losses. The latter was reflected in a lower Secchi depth and an enhanced microbial food‐web supporting a larger rotifer population.
• 5. It is suggested that, for the purposes of the Water Framework Directive (WFD), Lough Melvin and other large, alkaline but peat‐stained lakes may be treated as a distinct lake type as they do not fit easily into the conventional classifications of dystrophic or mesotrophic lakes.

Copyright © 2006 John Wiley & Sons, Ltd.