太湖微囊藻毒素在罗非鱼体内累积及生物降解的初步研究

为了解蓝藻水华期间微囊藻毒素在罗非鱼体内的分布及累积传递过程,2008年6～8月采集了高密度蓝藻池塘及太湖网箱内的鱼样及水样,用ELISA法对鱼样和水样进行微囊藻毒素MC-LR含量的检测。结果表明,池塘水体微囊藻毒素MC-LR含量在0.123～0.514μg/L,MC-LR含量随着藻密度的下降而降低,对照组水体MC-LR浓度显著高于实验组MC-LR含量。池塘鱼体肌肉组织微囊藻毒素MC-LR累积含量在1.194～3.615ng/g,肝脏组织微囊藻毒素MC-LR累积含量显著高于肌肉组织。将池塘与网箱罗非鱼转至无微囊藻水体中暂养,跟踪检测MC-LR含量变化,池塘和网箱鱼体肌肉组织微囊藻毒素MC-LR含量均低于人体每日可耐受摄入量,而肝脏组织藻毒素MC-LR含量则分别需要经过10～20d自然生物降解后降低至安全摄入量之下。讨论了微囊藻毒素在鱼体组织分布与食物链中的累积传递。     

A review of cyanobacterial odorous and bioactive metabolites: Impacts and management alternatives in aquaculture

Increased demand has pushed extensive aquaculture towards intensively operated production systems, commonly resulting in eutrophic conditions and cyanobacterial blooms. This review summarizes those cyanobacterial secondary metabolites that can cause undesirable tastes and odors (odorous metabolites) or are biochemically active (bioactive metabolites) in marine and freshwater, extensive and intensive aquaculture systems. For the scope of this paper, biochemically active metabolites include (1) toxins that can cause mortality in aquaculture organisms or have the potential to harm consumers via accumulation in the product (hepatotoxins, cytotoxins, neurotoxins, dermatoxins, and brine shrimp/molluskal toxins), (2) metabolites that may degrade the nutritional status of aquaculture species (inhibitors of proteases and grazer deterrents) or (3) metabolites that have the potential to negatively affect the general health of aquaculture species or aquaculture laborers (dermatoxins, irritant toxins, hepatotoxins, cytotoxins). Suggestions are made as to future management practices in intensive and extensive aquaculture and the potential exposure pathways to aquaculture species and human consumers are identified.     

微囊藻毒素对陆生植物的污染途径及累积研究进展

微囊藻毒素(Microcystins,MCs)是全世界范围内普遍存在、且随着水体污染的加剧而在自然环境中大量积聚的蓝藻毒素之一,对多种生物有着严重的毒性作用。MCs在生物体内富集并通过食物链传递,对人类健康造成威胁。近些年,MCs对陆生植物的毒害作用及累积研究尤为引人关注,取得了一批重要的研究成果。MC-LR(L为亮氨酸)和MC-RR(R为精氨酸)是淡水水体中普遍存在且危害较大的两种MCs异构体。针对这两种毒素,重点介绍其对陆生植物的污染途径、毒性作用及其在作物体内的累积量,对今后的研究进行了展望。     

微囊藻毒素3种异构体的提取净化研究

[目的]建立微囊藻毒素提取净化的方法。[方法]对比分析固相萃取柱、及洗脱液等对微囊藻毒素3种异构体(MC-LR、MCYR、MC-RR)提取净化的影响,并建立固相萃取提取净化微囊藻毒素的方法。[结果]Accu BOND II ODS C18固相萃取柱对微囊藻毒素中3种异构体具有较高的回收率,其回收率均达80%以上;甲醇浓度越低的淋洗液淋洗能力越差,10%甲醇能去除大部分色素杂质,且3种异构体的流失率较小;甲醇浓度越高的洗脱液洗脱能力越强,70%和80%较低浓度甲醇洗脱液,其洗脱收集液中杂质较少,其中80%甲醇是较理想的洗脱液。[结论]该研究建立的微囊藻毒素提取净化方法简单可行,可为今后的工业化应用提供科学依据。     

液相色谱-三重四级杆质谱法测定水中9种微囊藻毒素

本文将水质样品经固相萃取柱富集,并用液相色谱-三重四极杆质谱法分离检测了水中9种微囊藻毒素。结果表明:该方法检出限为0.01～0.02μg/L;分别对加标浓度为0.05μg/L和0.25μg/L的地表水加标样品进行了6次重复测定,相对标准偏差分别为4.7%～10.0%和4.3%～13.0%,加标回收率范围分别为63.5%～113.0%和62.7%～101.0%。     

水库微囊藻毒素3种异构体与环境因子的关系研究

[目的]在野外自然环境下研究微囊藻毒素3种异构体与环境因子的关系。[方法]应用高效液相色谱,对北方某水库5个采样点水体中微囊藻毒素3种异构体（MC-LR、RR和YR）进行了为期1年的监测,研究3种异构体与环境因子的相互关系。[结果]3种异构体均与叶绿素a呈现正相关关系;LR和YR异构体均与水温呈显著线性正相关,但是RR异构体与水温的相关性不明显;LR和YR异构体与总氮、硝酸盐氮和有机氮的相关性比较显著,而RR异构体只与硝酸盐氮存在显著负相关关系;LR和RR均与总磷和有机磷呈现显著正相关,而磷对YR异构体的影响相对较小,它们之间的相关性不明显。[结论]研究了微囊藻毒素3种异构体与叶绿素a、水温及氮、磷等环境因子的关系,并初步分析了其原因,对控制水体蓝藻的生长和毒素合成有一定的意义。     

Effect of dietary cyanobacteria on growth and accumulation of microcystins in Nile tilapia (Oreochromis niloticus)

A 12-week growth trial was conducted in a flow-through system to investigate the chronic toxic effect of dietary intake of cyanobacteria on growth, feed utilization and microcystins accumulation in Nile tilapia (Oreochromis niloticus L.) (initial body weight: 5.6 g). Six isonitrogenous and isocaloric diets were formulated to include different contents of cyanobacteria with the dietary microcystins increasing from 0 to 5460.06 ng/g diet. The results showed that dietary intake of cyanobacteria could increase the growth of tilapia while there are no impacts on feed conversion efficiency or mortality. Feeding rate was higher for the diets containing highest cyanobacteria. Microcystins were mostly accumulated in fish liver. The relationship between microcystins contents in muscle, liver, spleen and dietary intake could be described by quadratic equations.Microcystins content in the muscle of Nile tilapia in present study exceeded the upper limit of the tolerable daily intake (TDI) of microcystins suggested by the WHO (0.04 μg/kg body weight/d). It is suggested that Nile tilapia fed on toxic cyanobacteria is not suitable for human food.     

微囊藻毒素降解方法研究进展

综述了微囊藻毒素的特性及各种去除方法,包括物理法、化学法和生物法等,并提出了去除微囊藻毒素新的研究方向。     

外源一氧化氮缓解微囊藻毒素对青菜幼苗的毒害效应

微囊藻毒素(MCs)能够诱导青菜幼苗产生氧化损伤,并进一步抑制青菜幼苗的生长。相比较于单独MCs处理,外源一氧化氮(供体为SNP)预处理能够显著降低青菜幼苗体内活性氧(ROS)水平、减缓脂质过氧化反应,从而可以在一定程度上缓解MCs胁迫对青菜幼苗生长的抑制效应。这说明一氧化氮可能作为信号参与了青菜幼苗对MCs的解毒反应。     

自来水厂常规水处理工艺对微囊藻毒素的去除研究

研究了贵州省以深水湖库为供水水源的自来水厂常规水处理工艺各个工艺段对微囊藻毒素的去除效果以及各工艺段微囊藻毒素不同形态含量的变化。结果表明:自来水厂常规水处理工艺对微囊藻毒素的去除有限,对总微囊藻毒素的平均去除率为30.0%,对胞外微囊藻毒素的平均去除率为7.9%,对胞内微囊藻毒素的平均去除率为89.6%。对于胞外藻毒素,水处理工艺中氯化消毒段的去除率最高;对于胞内藻毒素,水处理工艺中混凝过滤段的去除率最高。经预氯化混凝的藻在沉淀36.0 h后,胞内藻毒素被释放出来;而没有预氯化混凝沉淀的藻在静置48.0 h后,未发现胞外藻毒素增高。自来水厂水处理中,当水中藻毒素以胞外藻毒素为主要形态时,处理措施应以强化氧化为主;而当水中藻毒素以胞内藻毒素为主要形态时,处理措施应以强化混凝除藻为主。