Li Huiying, Xie Ping, Zhang Dawen, Chen Jun
Donghu Experimental Station of Lake Ecosystems, State Key Laboratory of Freshwater Ecology and Biotechnology of China, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, PR China.
Toxicon. 2009 May;53(6):595-601. doi: 10.1016/j.toxicon.2008.11.005.
Microcystins are heptapeptide toxins produced by cyanobacteria. Microcystin-RR (MC-RR) is a common variant among the 80 variants identified so far. There have been many investigations documenting the toxic effects of microcystins on animals and higher plants, but little is known on the toxic effects of microcystins on algae, especially at molecular level. We studied the effects of MC-RR on gene expression profile of a few antioxidant enzymes and heat shock protein-70 (Hsp70) in Synechocystis sp. PCC6803. After two days post-exposure, a high dose toxin (5 mg/l, about 4.8 x 10(-3) mM) significantly increased expression levels of the genes gpx1, sodB, katG, acnB, gamma-TMT and dnaK2, while a relatively low dose toxin (1 mg/l, about 9.63 x 10(-4) mM) induced a moderate and slow increase of gene expression. Our results indicate that MC-RR could induce the oxidative stress in Synechocystis sp. PCC6803 and the increase in gene expression of antioxidant enzymes and Hsp70 might protect the organism from the oxidative damage. In addition, cell aggregation was observed during the early period of exposure, which might be a specific oxidative stress reaction to MC-RR.
微囊藻毒素是蓝藻产生的七肽毒素。微囊藻毒素-RR（MC-RR）是迄今已鉴定出的80种变体中的常见变体。已有许多研究记录了微囊藻毒素对动物和高等植物的毒性作用，但对于微囊藻毒素对藻类的毒性作用，尤其是在分子水平上的作用，了解甚少。我们研究了MC-RR对集胞藻PCC6803中几种抗氧化酶和热休克蛋白-70（Hsp70）基因表达谱的影响。暴露两天后，高剂量毒素（5毫克/升，约4.8×10^(-3)毫摩尔）显著提高了gpx1、sodB、katG、acnB、γ-TMT和dnaK2基因的表达水平，而相对低剂量毒素（1毫克/升，约9.63×10^(-4)毫摩尔）则诱导基因表达出现中度且缓慢的增加。我们的结果表明，MC-RR可在集胞藻PCC6803中诱导氧化应激，抗氧化酶和Hsp70基因表达的增加可能保护该生物体免受氧化损伤。此外，在暴露初期观察到细胞聚集，这可能是对MC-RR的一种特定氧化应激反应。
