微囊藻毒素对小鼠肝脏的毒性研究

为研究微囊藻毒素(MC)对小鼠肝脏的影响,采用腹腔注射MC抽提物,剂量分别为对照、MC3.33μg/(kg.d)和6.67μg/(kg.d),注射MC抽取物14 d后发现,与对照组小鼠肝脏相比,注射MC抽提物的小鼠肝脏肿大,且随注射剂量的增加,小鼠肝脏的相对质量增加,肝脏的黏连程度更加明显。     

微囊藻毒素对鲢鱼肝脏GST和CYP7A1基因表达的影响

为探究微囊藻毒素(MC)对鲢鱼肝脏谷胱甘肽S转移酶(GST)和胆固醇7α-羟化酶(CYP7A1)基因表达的影响,克隆了鲢鱼肝脏GST和CYP7A1基因的部分c DNA片段,并对饲养密度为1.3×108cell/L的有毒和无毒两种铜绿微囊藻水体中第2 d、第4 d和第6 d的鲢鱼肝脏取样,通过RT-PCR与Q-PCR技术分析肝脏GST和CYP7A1基因在MC影响下不同时间点的表达情况。结果显示,有毒铜绿微囊藻水体中鲢鱼肝脏GST相对表达量在第6 d显著下降,说明GST基因在第6 d时在MC解毒过程中开始发挥作用;鲢鱼CYP7A1相对表达量自第2 d开始显著下调并随时间延续维持在一个较低的水平,说明MC作用下CYP7A1表达受到抑制,可能对胆汁酸合成造成影响。为进一步研究鱼类微囊藻毒素去毒基因以及抑制对MC转运和吸收的关键基因提供依据。     

PCR扩增法检测江苏省5大淡水湖泊产毒微囊藻的空间分布

微囊藻毒素（Microcystin,MC）的产生受微囊藻毒素合成酶基因簇（microcystin biosynthesis gene,mcy）调控,常用PCR扩增mcy基因检测产毒微囊藻。采集江苏省5大淡水湖泊——太湖、滆湖、高宝-邵伯湖、洪泽湖和骆马湖的水样,测定水体营养盐浓度和叶绿素a浓度,根据叶绿素a浓度计算5个湖泊的富营养化指数（Trophic state index,TSI）,同时应用单一和多重PCR扩增mcy基因。结果表明,太湖和滆湖处于富营养和超富营养化水平,洪泽湖和骆马湖处于中营养和富营养化水平,高宝-邵伯湖处于寡营养水平。太湖、滆湖、洪泽湖和骆马湖的所有水样均检出mcy基因,4个湖泊水体受到微囊藻毒素的潜在威胁,高宝-邵伯湖没有检测出mcy基因的存在,尚未受微囊藻毒素的污染。     

A kinetic study of accumulation and elimination of microcystin-LR in yellow perch (Perca flavescens) tissue and implications for human fish consumption

Fish consumption is a potential route of human exposure to the hepatotoxic microcystins, especially in lakes and reservoirs that routinely experience significant toxic Microcystis blooms. Understanding the rates of uptake and elimination for microcystins as well as the transfer efficiency into tissues of consumers are important for determining the potential for microcystins to be transferred up the food web and for predicting potential human health impacts. The main objective of this work was to conduct laboratory experiments to investigate the kinetics of toxin accumulation in fish tissue. An oral route of exposure was employed in this study, in which juvenile yellow perch (Perca flavescens) were given a single oral dose of 5 or 20 μg of microcystin-LR (MC-LR) via food and accumulation in the muscle, liver, and tank water were measured over 24 h. Peak concentrations of the water soluble fraction of microcystin were generally observed 8-10 h after dosing in the liver and after 12-16 h in the muscle, with a rapid decline in both tissues by 24 h. Up to 99% of the total recoverable (i.e., unbound) microcystin was measured in the tank water by 16 h after exposure. The relatively rapid uptake and elimination of the unbound fraction of microcystin in the liver and muscle of juvenile yellow perch within 24 h of exposure indicates that fish consumption may not be a major route of human exposure to microcystin, particularly in the Great Lakes.     

Hepatotoxic Seafood Poisoning (HSP) Due to Microcystins: A Threat from the Ocean?

Cyanobacterial blooms are a major and growing problem for freshwater ecosystems worldwide that increasingly concerns public health, with an average of 60% of blooms known to be toxic. The most studied cyanobacterial toxins belong to a family of cyclic heptapeptide hepatotoxins, called microcystins. The microcystins are stable hydrophilic cyclic heptapeptides with a potential to cause cell damage following cellular uptake via organic anion-transporting proteins (OATP). Their intracellular biologic effects presumably involve inhibition of catalytic subunits of protein phosphatases (PP1 and PP2A) and glutathione depletion. The microcystins produced by cyanobacteria pose a serious problem to human health, if they contaminate drinking water or food. These toxins are collectively responsible for human fatalities, as well as continued and widespread poisoning of wild and domestic animals. Although intoxications of aquatic organisms by microcystins have been widely documented for freshwater ecosystems, such poisonings in marine environments have only occasionally been reported. Moreover, these poisonings have been attributed to freshwater cyanobacterial species invading seas of lower salinity (e.g., the Baltic) or to the discharge of freshwater microcystins into the ocean. However, recent data suggest that microcystins are also being produced in the oceans by a number of cosmopolitan marine species, so that Hepatotoxic Seafood Poisoning (HSP) is increasingly recognized as a major health risk that follows consumption of contaminated seafood.     

微囊藻毒素-LR对草鱼肝脏超微结构的亚急性毒性影响

微囊藻毒素-LR(microcystin-LR, MC-LR)是一种由蓝藻水华产生的环状肝毒素,对鱼类存在不可忽视的影响.草鱼(Ctenopharyngodon idella)经腹腔注射MC-LR(纯度>98%,50 μg/kg体重),在注射后1、2、7、14和21 d采集肝脏样品,用透射电镜的方法研究发现,MC-LR除可导致线粒体水肿、内质网扩张外,还可引起草鱼肝脏细胞连接间隙增宽,胆汁淤积,炎性细胞浸润,细胞质中大量脂滴及脂褐素、溶酶体增多等一系列的病变;但在注射MC-LR 21 d后草鱼肝脏细胞连接又基本恢复正常.结果表明,MC-LR在低剂量下除了对膜系结构存在影响外,对细胞连接间隙等还存在影响,然而随着时间的延长,这些病变可逐渐修复.     

Cyanobacteria from Terrestrial and Marine Sources Contain Apoptogens Able to Overcome Chemoresistance in Acute Myeloid Leukemia Cells

In this study, we investigated forty cyanobacterial isolates from biofilms, gastropods, brackish water and symbiotic lichen habitats. Their aqueous and organic extracts were used to screen for apoptosis-inducing activity against acute myeloid leukemia cells. A total of 28 extracts showed cytotoxicity against rat acute myeloid leukemia (IPC-81) cells. The design of the screen made it possible to eliminate known toxins, such as microcystins and nodularin, or known metabolites with anti-leukemic activity, such as adenosine and its analogs. A cytotoxicity test on human embryonic kidney (HEK293T) fibroblasts indicated that 21 of the 28 extracts containing anti-acute myeloid leukemia (AML) activity showed selectivity in favor of leukemia cells. Extracts L26-O and L30-O were able to partly overcome the chemotherapy resistance induced by the oncogenic protein Bcl-2, whereas extract L1-O overcame protection from the deletion of the tumor suppressor protein p53. In conclusion, cyanobacteria are a prolific resource for anti-leukemia compounds that have potential for pharmaceutical applications. Based on the variety of cellular responses, we also conclude that the different anti-leukemic compounds in the cyanobacterial extracts target different elements of the death machinery of mammalian cells.     

稀土铈对水华鱼腥藻生理特性及藻毒素释放的影响

随着稀土及其化合物的广泛应用,越来越多的稀土直接或间接进入水体,因而稀土对水生生态环境的影响备受关注。采用室内模拟试验,研究不同浓度（0~10.00mg·L-1）的稀土元素铈（Ce3＋）对水华鱼腥藻的影响,绘制了水华鱼腥藻的生长曲线,测定了藻蓝蛋白、类胡萝卜素、可溶性蛋白含量和过氧化物酶（POD）活性4项生理指标,以及培养基中总磷（TP）、微囊藻毒素-LR（MC-LR）的浓度。结果表明,和其他各组相比,在0.10mg·L-1Ce3＋处理下,水华鱼腥藻的生存量最为显著（P=0.008）,同时营养元素P被吸收后,培养基中残留的TP浓度达到最低值（1.52mg·L-1）。藻蓝蛋白、类胡萝卜素、可溶性蛋白含量和POD活性均随着Ce3＋浓度的升高呈现出先升高后降低的趋势。MC-LR在所有培养基中含量均较低,低于世界卫生组织（WHO）标准1.00μg·L-1。铈元素胁迫水华鱼腥藻产生的＂低促-高抑＂的Hormesis效应显著。     

高效液相色谱法测定蓝藻发酵液及堆肥中微囊藻毒素含量

建立了高效液相色谱测定蓝藻发酵液和蓝藻堆肥中微囊藻毒素(MC-RR、MC-LR)含量的方法.样品中的MC-RR和MC-LR用5%乙酸溶液提取,离心分离后经过SPE小柱净化、富集,在C18柱上采用梯度洗脱,流动相为甲醇+0.05 mol/L磷酸二氢钾,利用二极管阵列检测器在238 nm进行检测.MC-RR、MC-LR的检测限为0.03 μg/ml,定量限为0.10 μg/ml.在50～200 μg/kg的添加范围内,MC-RR的回收率为78.0%～90.5%,MC-LR的回收率为82.0%～92.8%.     

Water quality,agriculture and food safety in China:Current situation,trends, interdependencies,and management

Water quality in China is becoming a severe challenge for agriculture and food safety,and it might also impact health of population via agriculture and food. Thus,it is causing widespread concern. Based on extensive literatures review and data mining,current situation of water pollution in China and its effects on food safety were analyzed. The 2nd National Water Resource Survey in China show that the surface water all over the country was under slight pollution and about 60% of groundwater is polluted. Drinking water quality is basically guaranteed in urban area but it is worrisome in rural areas. In addition,China is the largest consumer of fertilizer and pestici de in the world and the amounts of application still show increasing trends. Fertilizers and pesticides are the most important sources of pollution,which affect human health as persistent organic pollutants and environmental endocrine disruptors. Eutrophication of surface water and nitrate pollution of groundwater are serious threats to drinking water safety. Sewage irrigation is becoming a pollution source to China's water and land because of lacking of effective regulations. Although,with the advance in technology and management level,control of nitrogen and phosphorus emissions and reducing water pollution is still a major challenge for China.