近岸水域盐度影响下的全氟化合物鳃毒性及机制研究

Pollution is increasing in estuary and coastal areas with the rapid urbanization in China. Perfluorinated chemicals (PFCs) and other pollutants are pooled in the area. The fluctuating salinity influences the toxicity of contaminants and thus the ecotoxicity assessment in the coastal areas. However, only a few studies have been done to explore the toxicity of chemicals under special environmental factor (salinity) in the region. Our previous work showed that salinity affected bioaccumulation and gill toxicity of perfluorooctane sulfonate and perfluorooctanoic acid. In the current project, the euryhaline fish-Oryzias melastigma wiil be used as the model to investigate the impacts of salinity on the toxicity of PFCs. PFCs with various carbon chain lengths and functional groups were selected to distinguish the structure-activity relationship. The bioaccumulation and toxicity of PFCs will be compared under various water salinity. The gill structure changes will be measured to explain the impacts of salinity on the PFCs bioaccumulation. We will further conduct the study to underlie the effects of PFCs on fish osmoregulation-salinity adaption at the levels of molecule, cell, tissue and physiological function. We will investigate the molecular mechanism of PFCs on the toxicity to osmoregulation by gill.The function of osmoregulation related hormones on the toxicity of PFCs will be studied. The roles of peroxisome proliferator-activated receptor alpha, hormone receptors and FXYD11 (recently reported as osmoregulation factor) in the toxicity will be studied by gene overexpression and knockdown in the primary cultured gill cells. Finally, the effects of gill remodeling induced by PFCs will be investigated on the absorptions of arsenic ion, mercury ion and silver nanoparticles. The interactions of organic pollutants, heavy metals and nanoparticles will be revealed in the fish absorption level. The project will provide a reference for ecotoxicity assessment of pollutants in the coastal areas.

城市化加剧了作为全氟化合物（PFCs）等污染物汇集区的河口-近岸水域的污染。近岸水域盐度波动大，盐度改变污染物毒性，影响其生态毒性评估。然而，针对污染物在近岸水域特殊环境因素（盐度）下的毒性研究很少。我们前期发现盐度影响PFOS和PFOA的鱼体蓄积和鳃毒性。据此，项目以广盐性海水青鳉鱼为模型，选择不同链长和功能基团的PFCs，比较不同盐度下PFCs生物蓄积和毒性的差别，查明导致差别的鳃结构变化基础。进而，综合分子、细胞、组织和功能水平，系统分析PFCs对鱼渗透调节-盐度适应的影响。探讨PFCs的渗透调节毒性机制，分析激素紊乱在毒性中的作用，构建过表达和沉默鳃细胞株，阐明PPARa、激素受体和新型因子FXYD11在渗透调节毒性中的作用。最后解析PFCs引起的鳃结构变化对鱼吸收砷、汞和纳米银的影响，了解有机污染物、重金属和纳米颗粒在吸收水平的毒性互作效应，为近岸水域污染的生态毒性评估提供参考。

快速城市化和工业化导致了污染物的集中排放，环境生态健康状况日趋恶化。全氟化合物（PFCs）等各类新兴污染物汇集于河口-近岸水域。而近岸水域环境复杂，盐度波动大，盐度改变污染物毒性，影响其生态毒性评估。然而，针对污染物在不同盐度下的毒性比较研究较少，无法为风险评估提供系统的理论依据。据此，本项目以具有广盐度适应能力的海水青鳉为模型，综合运用环境分析化学和生物化学等技术，比较不同盐度条件下，PFCs蓄积和毒性的变化。PFCs在鱼体内的蓄积浓度受链长影响，链长越大，PFCs蓄积浓度越高，从高到低顺序为：PFDoA>PFOS>PFOA>PFBS；侧链基团也影响蓄积，磺酸类PFOS蓄积浓度较羧酸类PFOA高。净化两周后，鱼体PFCs浓度明显降低。海水中的净化速率高于淡水，而长链PFCs的净化速率显著低于短链PFCs；长链PFCs比短链吸收快，而排出慢，其生物毒性可能更高。与已有研究不同的是，PFCs蓄积速率不受海水青鳉性别和体重的影响。我们进而分析盐度影响蓄积的机制。盐度并没有显著改变PFCs的水体浓度，但加速了鱼鳃对水相PFCs的富集速率。由于PFCs在体内与蛋白质结合。盐度可通过提高与污染物结合相关的蛋白质的表达水平，从而有助于鱼鳃对PFCs的吸收。离体鳃组织的荧光结果验证了这一机制。而四种类型的PFCs在鱼体的蓄积也和PFCs自身与蛋白质的结合能力密切相关。我们进而分析PFCs对鱼鳃的毒性影响。PFCs暴露诱导鱼鳃结构发生改变。RNA测序结果显示，四种PFCs都能影响渗透调节通路。综合以上结果，我们阐明了盐度促进PFCs在鱼体中的蓄积，PFCs自身的化学结构也影响其蓄积，而PFCs能影响鱼鳃的结构和功能变化。本项目研究相关结果共发表13篇SCI论文，这些结果有助于更真实的评估盐度多变区域PFCs等污染物的生态风险，并为污染物的结构-毒性关系研究提供更多科学数据。