Yin Liyan, Huang Jiaquan, Huang Wenming, Li Dunhai, Liu Yongding
State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, the Chinese Academy of Sciences, Wuhan 430072, China.
Toxicon. 2005 Dec 15;46(8):859-64. doi: 10.1016/j.toxicon.2004.12.025. Epub 2005 Nov 2.
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 5mg/L of microcystin-RR. The activities of superoxide dismutase (SOD) and catalase (CAT) increased significantly after 48 h exposure to 1 and 5mg/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.
微囊藻毒素是由多种蓝藻产生的环状七肽肝毒素。微囊藻毒素对动物的毒性作用和机制已在体内和体外进行了充分研究。也有报道称微囊藻毒素对植物有不良影响。然而，据我们所知，关于微囊藻毒素对植物悬浮细胞的毒性作用和机制尚无相关信息。在本研究中，将拟南芥悬浮细胞暴露于不同剂量的微囊藻毒素-RR中。研究了氧化损伤的主要表现——脂质过氧化，观察到丙二醛呈时间和剂量依赖性增加。相反，在用1mg/L和5mg/L微囊藻毒素-RR处理48小时后，细胞内谷胱甘肽（GSH）水平下降。在暴露于1mg/L和5mg/L微囊藻毒素-RR 48小时后，超氧化物歧化酶（SOD）和过氧化氢酶（CAT）的活性显著增加，但谷胱甘肽S-转移酶（GST）的活性与对照组相比没有差异。这些结果清楚地表明微囊藻毒素-RR能够在拟南芥悬浮细胞中引起氧化损伤。GSH含量的降低以及SOD和CAT活性的增加表明抗氧化系统可能在消除或减轻微囊藻毒素-RR的毒性方面发挥重要作用。本文还讨论了微囊藻毒素-RR对拟南芥悬浮细胞可能的毒性机制。
