微囊藻毒素对鱼类的毒性效应

湖泊富营养化导致的蓝藻水华已成为国内外普遍关注的环境问题,它所带来的主要危害之一是产生的藻毒素对鱼类的影响。在已发现的藻毒素中,微囊藻毒素(microcystins,MCs)的分布广、毒性大、危害严重,而备受关注。阐述了MCs对鱼类的影响。微囊藻毒素能干扰胚胎的发育,降低孵化率,增加畸形率,影响存活率,胚胎孵化受微囊藻毒素影响还具有剂量依赖效应;野外室内实验均表明鱼类暴露于微囊藻毒素后不仅可在肝脏中富集还可在肌肉、肠道等组织器官中快速积累;对鱼类进行组织病理检测发现MCs可导致肝脏、肾脏、心脏、脑、鳃等组织受损;MCs在鱼体中的解毒过程可能开始于由谷胱甘肽S-转移酶催化的还原型谷胱甘肽的结合反应;MCs还可影响鱼类的生长、行为和血清生化指标,此外,还具有一定的免疫毒性。MCs的转运机制和分子作用机制以及在食物链中传递过程中对人类造成的潜在影响可能成为今后研究重点。

Effects of microcystins on fish

The increasing occurrence of cyanobacterial blooms in eutrophic water bodies has now caused worldwide concerns, which may cause adverse effects on the health of aquatic animals. Microcystins (MCs), a family of cyclic peptides, are the most widespread hepatotoxic toxins. This review details the effects of the MCs on fish, and discusses hotspots of future research. In early life stages, exposure to MCs causes, in a dose-dependent manner, perturbations to embryonic hatching, increasing malformation rate and decreasing survival rate. In adults, field and experimental studies demonstrated that MCs accumulate mainly in liver, but can also be found in muscle, intestine and other tissues. Histopathological damages in the liver, intestine, kidneys, heart, brain and gills were observed. Microcystin exposure also has been shown to affect growth rate, modify behavior and enzyme activities. In addition, MCs may have potential immunotoxicity. The detoxication mechanism of MCs in fish begins with a conjugation reaction to glutathione catalyzed by glutathione S-transferases. Further studies are needed to clarify the transport and molecule mechanism of MCs in fish, and the ecological impacts of MCs accumulation in aquatic food chains.