LeBlanc Susan, Pick Frances R, Aranda-Rodriguez Rocio
Centre for Advanced Research in Environmental Genomics, Ottawa-Carleton Institute of Biology, Department of Biology, University of Ottawa, 150 Louis Pasteur, P.O. Box 450, Station A, Ottawa, Ontario, Canada.
Environ Toxicol. 2005 Feb;20(1):67-73. doi: 10.1002/tox.20079.
Cyanotoxins are a group of compounds produced by cyanobacteria that can have severe physiological effects on other organisms, including humans. The potential allelopathic effects of Microcystis aeruginosa, a toxic cyanobacterium, on the duckweed plant, Lemna gibba L., were examined using three experimental methods: (1) a series of toxicity bioassays, (2) evaluation of toxin production by M. aeruginosa in the direct and indirect presence of L. gibba, and (3) inhibition of oxygen evolution in photosynthesis. The results showed that, first, there were no clear dose-dependent effects of the microcystin-LR standard or the toxic M. aeruginosa culture filtrate on any of the end points measured in the toxicity bioassays (plant and frond number, dry weight, growth rate, chlorophyll content; one-way ANOVA, p > 0.05). In those cases in which an EC(50) value could be obtained, chlorophyll a was the most sensitive end point, as it had the lowest EC(50) value (14.47 microg/L microcystin-LR) of all the end points. Second, the presence of L. gibba did not result in higher microcystin-LR production in the toxic M. aeruginosa culture. And, last, oxygen evolution was not affected in isolated chloroplasts exposed directly to microcystin-LR. Therefore, microcystins from the toxic cyanobacterium Microcystis aeruginosa do not appear to have an allelopathic effect on the common aquatic macrophyte Lemna gibba.
蓝藻毒素是蓝细菌产生的一类化合物，可对包括人类在内的其他生物产生严重的生理影响。利用三种实验方法研究了有毒蓝细菌铜绿微囊藻对浮萍植物纤细浮萍的潜在化感作用：（1）一系列毒性生物测定；（2）在纤细浮萍直接和间接存在的情况下评估铜绿微囊藻的毒素产生；（3）抑制光合作用中的氧气释放。结果表明，首先，微囊藻毒素-LR标准品或有毒铜绿微囊藻培养滤液对毒性生物测定中测量的任何终点（植物和叶状体数量、干重、生长速率、叶绿素含量；单因素方差分析，p>0.05）均无明显的剂量依赖性影响。在可以获得半数有效浓度（EC50）值的情况下，叶绿素a是最敏感的终点，因为它在所有终点中具有最低的EC50值（14.47μg/L微囊藻毒素-LR）。其次，纤细浮萍的存在并未导致有毒铜绿微囊藻培养物中微囊藻毒素-LR产量增加。最后，直接暴露于微囊藻毒素-LR的分离叶绿体中的氧气释放未受影响。因此，有毒蓝细菌铜绿微囊藻产生的微囊藻毒素似乎对常见水生大型植物纤细浮萍没有化感作用。
