微囊藻毒素的母体传递效应对斑马鱼子代胚胎发育的影响

Dense blooms of cyanobacterial (blue-green algae) are one of the consequences of the increasing eutrophication in many waters worldwide. With frequent occurrence of cyanobacterial blooms in recent years, cyanotoxins have become a great threat to aquatic animals and human health. Among cyanotoxins, microcystins (MC) are the most common and toxic. A number of recent studies have described the developing toxicity of MC by parental transform. However, the molecular mechanisms by which it expresses its toxicity during the early development are still largely unknown. Based on our previous work of establishing proteomic approaches of larvae, the present subject aims to study the law of MC-induced parental transform and developing toxicity under environmentally relevant concentrations, employing proteomic, LC-MS, gene expression and other molecular tools. To further our understanding of mechanisms of action and identify the potential biomarkers for MC exposure, the present study was carried out in several levels including organism, tissue, protein and gene based on our previous studies. Our findings would provide new theoretical basis for precaution of MC-induced developing toxicity.

水体富营养化引起蓝藻水华大规模暴发，随着藻细胞破裂而释放出来的各种毒素对动物和人的机体健康构成了极大的危害。微囊藻毒素(microcystin，MC)是已发现的蓝藻毒素中危害最为严重的一类藻毒素。近年来的研究发现，MC可通过母体传递给子代，并引发显著的胚胎发育毒性。然而，MC的母体传递规律、以及毒性传递所引发的胚胎发育毒性的研究多为描述性的探索性研究，缺乏对其致毒机制的深入探讨。课题申请者开展了部分前期工作，建立了斑马鱼仔鱼蛋白组学研究模型。本项目拟在前期研究的基础上采用慢性环境浓度染毒方式，综合运用蛋白质组学、液相色谱-质谱检测、基因表达等多种技术，从个体、组织、蛋白、基因等多个层面探讨MC的母体传递规律，以及这种传递对子代胚胎发育的影响。本项目是在已有基础上进行更加深入的探索，可拓展人们对MC胚胎发育毒性机制的认识，寻找可能的MC发育毒性的标记物，为防治MC产生的危害提供新的理论依据。

微囊藻毒素（Microcystins, MCs）是一类在蓝藻水华污染中出现频率最高、产量最大、造成危害最严重的蓝藻毒素。至今已发现 MCs 有80多种异构体，其基本结构是由七个氨基酸组成的环状多肽，在众多异构体中存在最普遍、毒性较大、研究较详细的是 MCLR及MCRR（L、R分别代表亮氨酸、精氨酸）。本研究结合斑马鱼胚胎模型以及胎鼠胚胎模型探讨了MC的母体传递规律，并观察了相应的胚胎发育毒性终点指标。同时在前期蛋白质组学研究结果的基础上详尽分析了MC引发的斑马鱼胚胎心脏细胞凋亡以及甲状腺激素分泌异常所引发的胚胎发育迟缓现象。为进一步深入探讨MC的母体传递规律，申请人以孕鼠为研究模型发现MC可穿过胎盘屏障后蓄积在胎鼠脑部，提示脑部为 MCLR 母体转移的重要靶器官，MCLR 可诱发子代的神经毒性。申请人分离了胎鼠海马组织细胞进行原代培养作为模型来探讨MCLR引发神经毒性的分子机制。通过蛋白组学分析申请人发现，CaN表达显著升高。MCLR 暴露引发的胎鼠海马神经元 CaN 过表达显著抑制了 Bad 的去磷酸化（加入 CaN 抑制剂可解除此抑制），与此同时，我们检测到了海马神经元线粒体 Cyt c 的减少，以及胞质中 Cyt c 的上升。据此，申请人推测 MCLR 可能通过 CaN 介导的线粒体细胞凋亡通路引发大鼠子代的神经毒性。