High grazer toxicity of [D-Asp3 (E)-Dhb7]microcystin-RR of Planktothrix rubescens as compared to different microcystins
High grazer toxicity of [D-Asp3 (E)-Dhb7]microcystin-RR of Planktothrix rubescens as compared to different microcystins
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DOI：
10.1016/s0041-0101(01)00178-7
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发表时间：
2001-12-01
期刊：
影响因子：
2.8
通讯作者：
Jüttner, F
中科院分区：
文献类型：
--
作者：
Blom, JF;Robinson, JA;Jüttner, F
一般认为，苏黎世湖的主要蓝藻——蓝胸菌对浮游动物是有毒的。经核磁共振波谱和化学分析鉴定，主要毒素为[D-Asp(3), (E)-Dhb(7)] microcytin - rr。对该化合物进行了高纯度分离，并与微囊藻毒素- lr、微囊藻毒素- rr、微囊藻毒素- yr和结节素进行了24 h急性食草动物毒性比较。从LC50值来看[D-Asp(3),(E)-Dhb(7)]，微囊藻毒素- rr是毒性最强的微囊藻毒素。在该试验条件下，结核素的毒性略高。大量的个体可用于食草动物的生物测定，从而可以确定不同微囊藻毒素的剂量-反应曲线。这些曲线在陡度上有明显的差别。微囊藻毒素- rr的LC50与微囊藻毒素- lr和微囊藻毒素- yr的LC50几乎相同，呈非常平坦的剂量-反应曲线。这条平坦的曲线表明，对某些个体来说，较低浓度的这种微囊藻毒素比其他两种微囊藻毒素毒性更大。100%的死亡率需要更高浓度的微囊藻毒素，这表明一些动物对这种毒素具有耐药性。通过定量氨基酸分析，纯化的[D-Asp(3), (E)-Dhb(7)]微囊藻毒素具有比其他微囊藻毒素更高的摩尔吸收系数。这一观察结果对微囊藻毒素的风险评估产生了影响，并使微囊藻毒素的结构测定成为绝对需要。脱氢丁氨酸残基的存在可能是[D-Asp(3), (E)-Dhb(7)]微囊藻毒素- rr比含n-甲基脱氢丙氨酸的微囊藻毒素具有更高特异性毒性的原因。2001爱思唯尔科学有限公司版权所有。
Planktothrix rubescens, the dominant cyanobacterium in Lake Zurich, is generally considered to be toxic to zooplankton. The major toxin was determined by NMR spectroscopy and chemical analysis to be [D-Asp(3), (E)-Dhb(7)]microcystin-RR. The compound was isolated in high purity, and its 24-h acute grazer toxicity was compared with microcystin-LR, microcystin-RR, microcystin-YR, and nodularin using a Thamnocephalus platyurus bioassay. Based on LC50 values [D-Asp(3),(E)-Dhb(7)]microcystin-RR was the most toxic microcystin tested. Nodularin was slightly more toxic under the conditions of the assay. The large number of individuals available for the grazer bioassay allowed the determination of dose-response curves of the different microcystins. These curves showed marked differences in their steepness. Microcystin-RR, which had nearly the same LC50 as microcystin-LR and microcystin-YR, exhibited a very flat dose-response curve. This flat curve indicates that, for some individuals, lower concentrations of this microcystin are much more toxic than are the other two microcystins. Mortality of 100% requires much higher concentrations of microcystin-RR, indicating the resistance of some animals to the toxin. The purified [D-Asp(3), (E)-Dhb(7)]microcystin-RR exhibited a higher molar absorption coefficient determined by quantitative amino acid analysis than the coefficients generally used for other microcystins. This observation has consequences for the risk assessment for microcystins and makes a structural determination of microcystins an absolute requirement. The presence of the dehydrobutyrine residue may be the reason for the higher specific toxicity of [D-Asp(3), (E)-Dhb(7)]microcystin-RR when compared to the N-methyldehydroalanine-containing microcystins. (C) 2001 Elsevier Science Ltd. All rights reserved.