Mouse Toxicity of Anabaena flos-aquae from Lake Dianchi, China

Some species of the genera Anabaena can produce various kinds of cyanotoxins, which may pose risks to environment and human health. Anabaena has frequently been observed in eutrophic freshwater of China in recent years, but its toxicity has been reported only in a few studies. In the present study, the toxicity of an Anabaena flos-aquae strain isolated from Lake Dianchi was investigated. Acute toxicity testing was performed by mouse bioassay using crude extracts from the lyophilized cultures. The mice exposed to crude extracts showed visible symptoms of toxicity and died within 10-24 h of the injection. Serum biochemical parameters were evaluated by the use of commercial diagnostic kits. Significant alterations were found in the serum biochemical parameters: alkaline phosphatase (AKP), gamma-glutamyl transpepticlase (gamma-GT), aspartate amino transferase (AST), alanine amino transferase (ALT), AST/ALT ratio, total protein content, albumin content, albumin/globulin (A/G) ratio, blood urea nitrogen (BUN), serum creatinine (Ssr), and total antioxidative capacity (T-AOC). Histopathological observations were carried out with hematoxylin and eosin (HE) stain under light microscope. Severe lesions were seen in the livers, kidneys, and lungs of the mice injected with crude extracts. The alterations of biochemical parameters were in a dose-dependent manner, and the severities of histological lesions were in the same manner. Based on biochemical and histological studies, this research firstly shows the presence of toxin-producing Anabaena species in Lake Dianchi and the toxic effects of its crude extracts on mammals. (C) 2008 Wiley Periodicals, Inc. Environ Toxicol 24: 10-18, 2009.

Growth and antioxidant system of Escherichia coli in response to microcystin-RR

Microcystins are a kind of cyclic hepatoxins produced by many species of cyanobacteria. The toxic effects of microcystins on animals and plants have been well studied. However, the reports about the effects of microcystins on microbial cells are very limited. In present paper, Escherichia coli was undertaken to determine the effect of microcystin-RR. These results suggested that microcystin-RR could prolong the growth of E. coli when exposed to high concentrations of microcystin-RR and cause the accumulation of ROS and induce the oxidant stress for a short time. The antioxidant system protects E. coli from oxidative damage.

Induction of hepatic cytochrome P4501A1/2B activity and disruption of thyroglobulin synthesis/secretion by mono-ortho polychlorinated biphenyl and its hydroxylated metabolites in rat cell lines

As the active metabolites of polychlorinated biphenyl (PCBs), hydroxylated polychlorinated biphenyls (OH-PCBs) are found in wildlife and human tissues. They have been proposed as main contributors for endocrine disruption of PCBs in living organisms. In this study, mono-ortho PCB 156 and its hydroxylated metabolites 4'-OH-PCB 159, 4'-OH-PCB 121, and 4'-OH-PCB 72 were selected to investigate the toxic effects on rat hepatoma H4IIE cell line and rat thyroid follicle FRTL-5 cell line at concentrations of 1, 10(2), 10(4) nM. 7-Ethoxyresorufin-O-deethylase (EROD) and 7-pentoxyresorufin-O-dealkylase (PROD) activities were determined with micro-EROD/PROD to indicate cytochrome P4501 A1 (CYP1A1) and cytochrome P4502B (CYP2B) induction in the H4IIE cell after exposure for 72 h. To assess thyroid disruption of these compounds, thyroglobulin concentrations also were detected inside FRTL-5 cell with immunocellularchemistry and in its medium with radioimmunoassay after exposure for 24 It. Significant inductions of EROD activity by PCB 156 at 102 and 104 nM (p < 0.05) were observed, but no effects by the three OH-PCBs in H4IIE cell line. 7-Pentoxyresorufin-O-dealkylase activities were induced only by 10(4) nM of PCB156 and the three OH-PCBs (p < 0.05). Meanwhile, significant increases of thyroglobulin concentrations were observed in the medium of FRTL-5 cell exposed to 4'-OH-PCB 121 and 4'-OH-PCB 72 at all of the test concentrations (p < 0.05), but not to the other compounds. The results demonstrated that mono-ortho PCBs mainly could be metabolized to hydroxylated metabolites through CYP1A1 instead of CYP2B. Moreover, after being metabolized, OH-PCBs still sustained the ability to induce PROD activity and did exhibit the disruption on thyroglobulin synthesis/excretion in rat cells.

Antioxidant enzyme activities of Microcystis aeruginosa in response to nonylphenols and degradation of nonylphenols by M-aeruginosa

The aim of this study was to examine the effects of chemical nonylphenols (NPs) on the antioxidant system of Microcystis aeruginosa strains. The degradation and sorption of NPs by M. aeruginosa were also evaluated. High concentrations of NPs (1 and 2 mg/l) were found to cause increases in superoxidase dismutase (SOD) and glutathione-S-transferase (GST) activities and in glutathione (GSH) levels. These results suggest that toxic stress manifested by elevated SOD and GST levels and GSH contents may be responsible for the toxicity of NPs to M. aeruginosa and that the algal cells could improve their antioxidant and detoxification ability through the enhancement of enzymatic and nonenzymatic prevention substances. The observed elevations in GSH levels and GST activities were relatively higher than those in SOD activities, indicating that GSH and GST contributed more in eliminating toxic effects than SOD. Low concentrations of NPs (0.05-0.2 mg/l) enhanced cell growth and decreased GST activity in algal cells of M. aeruginosa, suggesting that NPs may have acted as a protecting factor, such as an antioxidant. The larger portion of the NPs (> 60%) disappeared after 12 days of incubation, indicating the strong ability of M. aeruginosa to degrade the moderate persistent NP compounds. The sorption ratio of M. aeruginosa after a 12-day exposure to low nominal concentrations of NPs (0.02-0.5 mg/l) was relatively high (> 30%). The fact that M. aeruginosa effectively resisted the toxic effects of NPs and strongly degraded these pollutants indicate that M. aeruginosa cells have a strong ability to adapt to variations in environmental conditions and that low and moderate concentrations of organic compounds may favor its survival. Further studies are needed to provide detailed information on the fate of persistent organic pollutants and the survival of algae and to determine the possible role of organic pollutants in the occurrence of water blooms in eutrophic lakes.

Sequential ultrastructural and biochemical changes induced in vivo by the hepatotoxic microcystins in liver of the phytoplanktivorous silver carp Hypophthalmichthys molitrix

Up to now, in vivo studies on the toxic effects of microcystins (MCs) on the ultrastructures of fish liver have been very limited. The phytoplanktivorous silver carp was injected i.p. with extracted hepatotoxic microcystins (mainly MC-RR and -LR) at a dose of 1000 mu g MC-LReq. kg(-1) body weight, showing a time-dependent ultrastructural change in liver as well as significant increases in enzyme activity of plasma alanine aminotransferase (ALT), aspartate aminotransferase (AST) and lactate dehydrogenase (LDH). We observed for the first time the occurrence of a large amount of activated secondary lysosomes, which might be an adaptive mechanism to eliminate or lessen cell damage caused by MCs through lysosome activation. Quantitative and qualitative determinations of MCs in the liver were conducted by HPLC and LC-MS2, respectively. MCs concentration in the liver reached the maximum (114.20 mu g g(-1) dry weight) after 3 h post-injection, and then rapidly dropped to 7.57 mu g g(-1) dry weight at 48 h, indicating a deputation of 99% accumulated MC-LReq. On the other hand, a decrease trend in glutathione (GSH) concentration was observed in the liver of silver carp while the activity of glutathione S-transferase (GST) increased significantly after injection. The high tolerance of silver carp to MCs might be due to the high basic GSH level in their liver, and/or an increased GSH synthesis. (C) 2007 Elsevier Inc. All rights reserved.

Toxicity of microcystins in the isolated hepatocytes of common carp (Cyprinus carpio L.)

The toxicity of hepatotoxic microcystins produced mainly by Microcystis aeruginosa in mammals and fishes was well studied in recent years. However, there were scarcely reports in toxic effects of microcystins on isolated hepatocytes of fishes, especially investigation of microcystin-induced apoptosis and/or necrosis in carp hepatocytes. In the present study, the isolated hepatocytes of common carp were exposed to various concentrations of microcystins (0.01, 0.1, 1, 10, 100, 1000 mu g L-1) for 2, 4, 8, 16 and 24 h, respectively, and cytotoxicity of microcystins in the toxin-treated cells was determined. Results of this study showed that cytotoxicity of microcystins on carp hepatocytes was time and dose-dependent, and the approximate LC50 of microcystins in carp hepatocytes was 169.2 mu g L-1. The morphological changes typical of apoptosis, such as blebbing of cell membrane, condensation and fragmentation of cell nucleus were observed in the hepatocytes exposed to microcystins (1, 10 and 100 mu g L-1) using fluorescence and differential interference contrast microscopy. Agarose gel electrophoresis of DNA demonstrated a typical apoptotic "ladder pattern" in microcystin-treated hepatocytes after 16 h of exposure. Results of the present study indicated that the form of cell death in microcystin-treated hepatocytes depend on the exposure dose of toxin. When lower concentration of microcystins (10 and 100 mu g L-1) was used for exposure, carp hepatocytes died in apoptosis while, when higher one used (1000 mu g L-1), they died in the form of necrosis. (C) 2006 Elsevier Inc. All rights reserved.

First report of aphantoxins in China - waterblooms of toxigenic Aphanizomenon flos-aquae in Lake Dianchi

The oligohaline cyanobacterium Aphanizomenon flos-aquae (L.) Ralfs (A. flos-aquae) has been reported in several countries to produce paralytic shellfish poisons (PSPs) or protracted toxic effects. In the past years, A. flos-aquae blooms have occurred annually in the eutrophic Lake Dianchi (300 km(2) in area, located in southwestern China). Material from natural blooms dominated by A. flosaquae was collected and lyophilized. Acute toxicity testing was performed by mouse bioassay using extracts from the lyophilized material. Clear symptoms of PSPs, intoxications were observed. To confirm the production of PSPs, a strain of A. flos-aquae (DC-1) was isolated and maintained in culture. Histopathological effects were studied by examining the organ damages using transmission electron microscopy (TEM). Slight hepatocytic damage with swollen mitochondria was found. The ultrastructural pulmonary lesions were characterized by distortied nuclei and indenting of karyotheca, together with degeneration and tumefaction of mitochondria and endoplasmic reticulum. Control animals injected with acetic acid did not exhibit histopathological damage in any organ. Toxic effects of cultured algal cells on enzymatic systems in the mouse were studied using sublethal doses of extracts. Significant glutathione-S-transferase (GST) and lactate dehydrogenase (LDH) increases, together with decrease of the glutathione (GSH) level, were measured. These results indicated a potential role of PSPs intoxicating and metabolizing in the test animals. HPLC-FLD and LC/MS analysis of extracts from cultured material demonstrated the PSP toxins produced by A. flos-aquae bloom. To the best of our knowledge, this is the first study reporting chemically and toxicologically confirmed PSP toxins related to A. flosaquae in China. (c) 2005 Elsevier Inc. All rights reserved.

A screening study on persistent bioaccumulation toxins (PBT) in fuel combustion soot

Persistent bioaccumulative toxins (PBTs) are organic substances that are persistent, bioaccumulative and can cause severe toxic effects (e.g. potential oncogens, mutagenic, endocrine disrupters) to human health or environment which are the ones that need special attention. PBT chemicals could be released to the environment from several types of sources and are ubiquitous in environment. However, fast and efficiency monitoring and assessment methods to investigate PBTs in environment are still lacking. In this study, a cleaning-up procedure of analyzing PBTs in fuels combustion soot was developed and its performance was assessed through comparing the chromatograms of crude extracts with their cleaned extracts after the cleaning-up procedure. The results showed that polycyclic aromatic compounds (PACs) were the main components in fuel combustion soot and the clean-up procedure developed in this paper can be well used as the method of analyzing PBTs in fuels combustion soot.

Responses of antioxidant system in Arabidopsis thaliana suspension cells to the toxicity of microcystin-RR

Microcystins are cyclic heptapeptide hepatoxins produced by many species of cyanobacteria. The toxic effects and mechanism of microcystins on animals have been well studied both in vivo and in vitro. It was also reported that microcystins had adverse effects on plants. However, to our knowledge, there is no information about the toxic effects and mechanism of microcystins on plant suspension cells. In this study, Arabidopsis thaliana suspension cells were exposed to a range dose of microcystin-RR. Lipid peroxidation, a main manifestation of oxidative damage, was studied and a time- and dose-dependent increase in malondiadehyde was observed. In contrast, glutathione (GSH) levels in the cells decreased after 48 h treatment with 1 and 5 mg/L of microcystin-RR. The activities of superoxide dismutase (SOD) and catalase (CAT) increased significantly after 48 h exposure to I and 5 mg/L of microcystin-RR, but glutathione S-transferase (GST) activity showed no difference compared with the control. These results clearly indicate that microcystin-RR is able to cause oxidative damage in A. thaliana suspension cells. Decrease of GSH content and increases of SOD and CAT activities reveal that the antioxidant system may play an important role in eliminating or alleviating the toxicity of microcystin-RR. The possible toxicity mechanism of microcystin-RR on the A. thaliana suspension cells is also discussed in this paper. (C) 2005 Elsevier Ltd. All rights reserved.

Growth and antioxidant system of the cyanobacterium Synechococcus elongatus in response to microcystin-RR

Microcystins, one type of the cyanobacterial toxins, show a broad range of hazardous effects on other organisms. Most of the researches on the toxic effects of microcystins have involved in animals and higher plants. Little work, however, has been done on evaluating the mechanisms of microcystin toxicity on algae. In this study, the toxicological effects of microcystin-RR (MC-RR) on the cyanobacterium Synechococcus elongatus were investigated. For this purpose, six physio-biochemical parameters (cell optical density, reactive oxygen species (ROS), malondialdehyde (MDA), glutathione (GSH), glutathione peroxidase (GSH-Px) and glutathione S-transferase (GST)) were tested in algal cells when exposed to 100 mug(-1) microcystin-RR. The results showed that the growth of Synechococcus elongatus ( expressed as optical density) was significantly inhibited compared with the control. At the same time, the treated algae exhibited a pronounced increase in production of ROS and MDA after 6 days exposure to microcystin-RR. Signi. cant changes in GSH levels and GSH-Px, GSH activities were also detected in algal cells, with higher values being observed in the toxin treated algae after 6 days exposure. GST activities in the treated algae exhibited a decline after exposure and rapid augmentation on day 3, thereafter, they kept at a high level when compared to the control group. GSH contents and GSH-Px activities were also significantly raised in the toxin-treated algae cells from day 3, but they showed a sharp decrease on day 4, which was the onward of cell proliferation. These results suggested that oxidative stress manifested by elevated ROS levels and MDA contents might be responsible for the toxicity of microcystin to Synechococcus elongatus and the algal cells could improve their antioxidant ability through the enhancement of enzymatic and non-enzymatic preventive substances.

重金属对矮小拟丽突线虫的毒性效应研究

为了探讨重金属对矮小拟丽突线虫（Acrobeloides nanus）的毒性作用，本文采用室内培养的方法，研究了不同浓度Cu、Zn、Pb、Cd对矮小拟丽突线虫死亡率、生长发育和繁殖的影响，并对线虫世代间的毒性效应进行了比较。结果表明：1）Cu、Zn、Pb、Cd对矮小拟丽突线虫24 h的半致死浓度LC50值分别为 0.80、71.20、12.94 和 1.42 mg • L-1，48 h 的半致死浓度LC50值分别为 0.71、35.08、2.65 和 0.32 mg • L-1。不同重金属离子对矮小拟丽突线虫产生的毒性具有一定的差异，24 h四种重金属离子对矮小拟丽突线虫的毒性大小依次为Cu > Cd > Pb > Zn，48 h毒性大小依次为Cd > Cu > Pb > Zn；2）与对照组相比，各暴露组当代（P0）和后代（F1）线虫平均体长均显著降低（P<0.05, P<0.01）；随着暴露浓度的增加，当代（P0）和后代（F1）线虫平均体长呈逐渐降低的趋势。生物量比体长更能敏感地反应重金属对矮小拟丽突线虫生长发育的影响，可作为重金属污染的敏感检测指标；3）供试线虫的产卵数随着Cu、Zn、Pb、Cd暴露浓度的增加而降低；其中Cu对线虫产卵数的72h-EC50、EC20和EC10值分别为1.35、0.49 和 0.2mg • L-1，Zn的72h-EC20和EC10值分别为330.29 和 163.9 mg • L-1，Pb的72h-EC20、EC10分别为17.41、4.36 mg•L-1，而Cd对线虫产卵数的72h-EC50、EC20和EC10分别为4.47、0.91 和 0.53 mg • L-1。研究结果表明，重金属Cu、Zn、Pb、Cd暴露可显著抑制矮小拟丽突线虫的生长发育和繁殖；线虫体长、产卵数表现出明显的重金属浓度依赖性。

Strategy for analysis and screening of bioactive compounds in traditional Chinese medicines

Traditional Chinese medicines (TCMs), due to their long time clinic test and reliable therapeutic efficacy, are attracting increased global attention served as excellent pools of bioactive compounds for the discovery of new drugs. However, hundreds or even thousands of components are usually contained in traditional Chinese medicines and only a few compounds are responsible for the pharmaceutical and/or toxic effects. The large numbers of other components in traditional Chinese medicines make the screening and analysis of the bioactive components extremely difficult. By the way, the combination effect of bioactive components on the pharmacological activity makes it very difficult to clear the therapeutic mechanism of TCMs. Therefore, some strategies have to design for screening of bioactive compounds in traditional Chinese medicines, which further leads to disclose the therapeutic mechanism of TCMs in molecular level. The review will summarize the present state of the art of screening strategy for active compounds in traditional Chinese medicines, and the chromatography methods for screening and analysis of bioactive compounds in traditional Chinese medicines will be emphasized. (C) 2004 Elsevier B.V. All rights reserved.

塔玛亚历山大藻(Alexandrium tamarense)对鲈鱼(Lateolabrax japonicus) 的危害机制研究

本论文选择在我国分离得到的一株有毒赤潮甲藻-塔玛亚历山大藻（Alexandrium tamarense，ATHK株），研究了其对一种我国沿海常见和典型养殖鱼类鲈鱼（Lateolabrax japonicus）的危害机制。首先研究了塔玛亚历山大藻（ATHK）对鲈鱼鳃结构的影响及其溶血毒性； 然后采用腹腔注射的方法，研究了高剂量塔玛亚历山大藻毒素（ATHK毒素：约为1.6×105 细胞，相应PSP为0.886µg STX Equal，相当于每克湿重的鲈鱼PSP注射量为0.0118µg STX Equal）和低剂量塔玛亚历山大藻毒素（ATHK毒素： 约为0.16×105 细胞，相应PSP为0.0886µg STX Equal，相当于每克湿重的鲈鱼PSP注射量为0.00118µg STX Equal）在鲈鱼体内代谢过程中对鲈鱼肝脏、肾脏和鳃组织的超微结构、Na+K+-ATPase活性、肝脏功能和肾脏功能的影响、以及对抗氧化系统酶活性和异生物质代谢酶的影响，以期从不同方面了解塔玛亚历山大藻及其所产水溶性毒素（ATHK毒素）对鲈鱼的毒害效应及机制，为有毒赤潮的有效管理提供一定的科学依据。 塔玛亚历山大藻（ATHK）对鲈鱼鳃组织影响的实验结果表明，该藻使鲈鱼鳃组织出现水肿现象，细胞间隙变大；粘液细胞颗粒不规则，颜色加深，颗粒发生凝集，有板结状；氯细胞线粒体内部基质凝集。不产PSP的一种亚历山大藻（AT-6）也使鲈鱼鳃出现水肿，且使细胞出现一定的固缩现象。显微镜观察发现鲈鱼鳃丝间存在有这两种亚历山大藻细胞。由此推测塔玛亚历山大藻ATHK和AT-6的表面结构可能具有能导致鲈鱼鳃组织水肿的机械作用。对人血细胞溶血实验结果表明塔玛亚历山大藻（ATHK）具有较强的溶血毒性，大小与藻的生长阶段和细胞密度都有一定的关系：指数期的溶血毒性最大，随细胞数目的增多，活性逐渐加大；藻细胞、细胞碎片、细胞内容物都有一定的溶血毒性，其中细胞碎片的活性最大。通过11种（株）产PSP的亚历山大藻、不产PSP的亚历山大藻以及标准PSP的实验结果表明这种溶血毒性是由藻细胞的其它非PSP物质造成的，且这种溶血毒性在产PSP的亚历山大藻中具有一定的普遍性。 塔玛亚历山大藻（ATHK）对鲈鱼组织超微结构实验结果表明：ATHK毒素（约为1.6×105 细胞，相应PSP为0.886µg STX Equal，相当于每克湿重的鲈鱼PSP注射量为0.0118µg STX Equal）能导致鲈鱼组织细胞超微结构发生剧烈的变化，主要表现在：肝细胞细胞膜有肿胀现象，部分膜边缘溶解；细胞质糖原颗粒化；核糖体脱落，仅见滑面内质网；细胞质和线粒体内都出现空泡，且线粒体的嵴状结构也发生变化；核膜溶解比较严重，核质外溢，且异染色质边际化。前肾细胞超微结构的变化主要是淋巴细胞核质出现空泡，核膜有溶解迹象；Ⅰ型粒细胞颗粒膨大，伪足增多且变长；Ⅱ型颗粒细胞颗粒增多，内部出现空腔，细胞膜和核膜溶解，胞质、细胞器和核质外溢。鳃组织中氯细胞的核膜局部溶解，核仁弥散，线粒体膜溶解，微细小管膨大；粘液颗粒膜溶解，内部结构遭受破坏；扁平细胞核膜及线粒体膜几乎全部溶解。因此，我们的结果表明，ATHK毒素能作用于鲈鱼细胞的内膜和外膜系统，使膜发生溶解、脱落等变化；比较注射同样剂量大小ATHK毒素120h和240h时鲈鱼组织超微结构发现，细胞超微结构在一定程度上能够恢复。 ATHK毒素对Na+K+-ATPase活性、肝脏功能以及肾脏功能的影响结果表明，0.16×105―1.6×105细胞范围内的ATHK毒素可以显著影响肝脏和鳃组织中的Na+K+-ATPase，使这两种组织中的Na+K+-ATPase活性出现不同程度的下降； 而且还能够显著抑制肝脏中谷丙转氨酶的活性，最大抑制率为95%。但此范围内的ATHK毒素不能显著影响肾脏中的Na+K+-ATPase活性以及尿素氮含量。因此，ATHK毒素对Na+K+-ATPase活性的抑制则会导致细胞能量的缺失，使细胞进一步发生其它变化，而ATHK毒素对肝脏功能完整性的影响则可能会抑制对蛋白质的分解代谢。 ATHK毒素对鲈鱼肝脏、肾脏和鳃组织中的、超氧化物歧化酶（SOD）、过氧化氢酶（CAT）、谷胱肝肽过氧化物酶（GSH-Px）以及谷胱肝肽转硫酶（GST）活性变化影响的结果表明：高剂量（约为1.6×105 细胞，相应PSP为0.886µg STX Equal，相当于每克湿重的鲈鱼PSP注射量为0.0118µg STX Equal）ATHK毒素能显著诱导鲈鱼肝脏和鳃组织中SOD、GSH-Px以及GST酶活性，最大变化范围为正常状态下的3-4倍，对肝脏中CAT酶活性具有一定的抑制作用，对鳃中的CAT抑制效应则不显著；但此剂量的ATHK毒素仅对肾脏鳃中的GSH-Px活性有一定的诱导作用，对SOD、CAT以及GST的活性没有显著影响。低剂量（约为0.16×105 细胞，相应PSP为0.0886µg STX Equal，相当于每克湿重的鲈鱼PSP注射量为0.00118µg STX Equal）ATHK毒素也能诱导鲈鱼肝脏和鳃组织中SOD、GSH-Px以及GST酶活性，其在第一个24h内的诱导效果与临界致死毒素剂量相似； 且连续注射低剂量ATHK毒素则对肝脏和鳃中这三种酶活性具有累加的诱导作用，使这三种酶活性的变化范围为正常的5倍；低剂量ATHK毒素对肝脏中CAT酶活性也具有抑制作用，但对鳃中CAT酶活性的抑制作用并不显著。 同样，低剂量ATHK毒素除对肾脏中GSH-Px活性具有一定诱导效应外，对SOD、CAT以及GST都没有显著影响。 SOD、GSH-Px以及GST酶活性的显著升高表明ATHK毒素在鲈鱼体内代谢过程中能诱导鲈鱼产生活性氧自由基，且GST活性的升高则说明作为细胞色素P450依赖的异生物质代谢酶，GST在ATHK毒素代谢过程中可能可以加速ATHK毒素的代谢。推测鲈鱼可以通过这三种酶降低ATHK毒素以及次生毒物活性氧自由基对鲈鱼的危害。

DSP等赤潮藻毒素对哺乳类细胞的毒性效应及机制研究

本文研究了腹泻性贝毒的主要组分大田软海绵酸以及几株重要赤潮藻的提取物对四株哺乳类细胞的毒性效应，并探讨了应用细胞毒性检测方法作为赤潮藻毒素毒性检测常规方法的可能性。 结果发现：OA和利玛原甲藻提取物显著地抑制四株细胞的增殖并诱导四株细胞发生凋亡；四株细胞对毒素的敏感性存在一定的差异，人肝癌细胞和小鼠神经瘤细胞较敏感，其次分别为人肝细胞和小鼠皮肤细胞。 小鼠神经瘤细胞对OA反应敏感，细胞毒性检测指标及检测方法灵敏、快速，应用小鼠神经瘤细胞Neuro-2a进行的DSP毒素细胞毒性测试方法具有发展为该类毒素毒性监测常规方法的潜能。 米氏凯伦藻内存在抑制细胞增殖的毒性物质，且该物质是一种具有一定极性的脂溶性物质；该物质能够导致细胞肿胀、破裂，并诱导细胞发生脂质过氧化，导致脂质过氧化产物丙二醛(MDA)的积累。 相关亚历山大藻的去藻过滤液内存在抑制细胞增殖和诱导细胞凋亡的毒性物质，该毒性物质的分子量＞5K，这与本实验室以往的研究结果一致。 　　总之，通过我们的研究发现：DSP等赤潮藻毒素或毒性物质对哺乳类细胞存在毒性影响，且不同毒素的危害机制存在差异，赤潮藻毒素或赤潮藻产生的一些毒性物质威胁人类的健康，应引起我们的高度关注。

Experimental studies on the effects of toxic Microcystis aeruginosa PCC7820 on the survival and reproduction of two freshwater rotifers Brachionus calyciflorus and Brachionus rubens

Blooms of Microcystis aeruginosa frequently occur in many eutrophic lakes in China, however, there is very little experimental study on the relationship between Microcystis and rotifers from Chinese waters. The effects of different concentrations of toxic M. aeruginosa PCC7820 on two common freshwater rotifers Brachionus calyciflorus and B. rubens were investigated in laboratory experiments. B. calyciflorus was able to utilize this strain of M. aeruginosa as a food source. However, M. aeruginosa suppressed the survival and reproduction of B. calyciflorus at the highest concentration (10(6) cells/ml) probably due to the inadequate nutrition. B. rubens was inhibited by toxic M. aeruginosa PCC7820 and the inhibition increased with the increasing Microcystis concentration. Our study indicates that the two rotifers have different sensitivities to toxic M. aeruginosa and that toxic cyanobacteria may affect zooplankton community structure by differentially inhibiting the different zooplankton taxa.