基于“标准化”背角无齿蚌及其鳃细胞损伤模型的镉生物积累及毒性机制研究

Bivalve Anodonta woodiana is demonstrated as an effective bioindicator to grasp the dynamics of waterborne metal pollution. To data, A. woodiana-based biomonitoring approach has been widely used to monitor and assess metal (especially Cd) pollution of fishery ecological environments. However, in-depth understanding seems to be lacked on the mechanism of particularly high Cd accumulative capacity, toxicological effect, and response strategy. Therefore, “standardized” A. woodiana (individuals obtained by artificial propagation techniques, possessing the similar biometric characterization, genetic quality, and low background of metals), with independent intellectual property, is chosen as model animal in the present study to investigate bioaccumulative dynamic of Cd through aqueous and dietary routes, accompanying with the application of stable isotopes (112Cd and 113Cd) labeling on water (waterborne Cd) and microalgae Chlorella vulgaris (dietary-borne Cd), respectively. Based on the results obtained, transcript levels of genes involved in the transport of Ca (ECaC), divalent metals (DMT1) and Zn (ZIP8) and assimilated Cd content will be further investigated with the target tissues (especially gill) for revealing Cd assimilation channel and accumulation mechanism. In addition, an in vitro approach of isolation and culture of the mussel gill cells will be used to establish a gill cells injury model for elucidation of Cd toxicological effect, and A. woodiana response strategy. The results must facilitate in conservation of both fishery ecological environment safety and aquatic products quality.

背角无齿蚌被证明是有效把握水环境重金属污染动态的生物指示物种，已被广泛用于渔业水环境Cd等重金属污染的评价。然而，其对Cd的高富集能力、毒理效应及其应答机制尚不清楚。鉴于此，本项目拟利用自主开发的“标准化”（人工繁育的生物因子相同、遗传质量稳定、污染本底值较低的监测专用）背角无齿蚌个体，运用稳定同位素（112Cd、113Cd）双标记水体（水相）和小球藻（Chlorella vulgaris）（食物相）等方法，深入研究蚌（包括组织、细胞及亚细胞水平）对水相和食物相Cd的积累动力学；再尝试从分子水平（ECaC、DMT1和ZIP8 mRNA相对表达量与Cd吸收量之间的关联性）探索蚌以鳃为代表的靶组织对Cd的吸收通道和生物积累特征；在此基础上，进一步突破蚌鳃细胞的体外培养难题，尝试建立鳃细胞损伤模型，以期揭示Cd的毒性效应及其应答机制。研究成果对我国渔业水域生态环境和水产品质量安全将具有重要意义。

背角无齿蚌（Anodonta woodiana）被证明是有效把握水环境重金属污染动态的生物指示物种，已被广泛用于渔业水环境Cd等重金属污染的评价。然而，其对Cd的高富集能力、毒理效应及其应答机制尚不清楚。本项目创新性地解决了“标准化”背角无齿蚌群体建立过程中寄生鱼种类的选择难题；运用毒理学和Cd稳定同位素双标记技术（水相112Cd、食物相113Cd）探索了Cd吸收、排出动力学，明确了Cd在个体（整个贝类包括软组织和贝壳）、组织（斧足、鳃、外套膜、消化腺和其余组织）、细胞（如鳃细胞）和亚细胞（富金属矿体、细胞碎屑、细胞器、热稳蛋白、类金属蛋白）水平上的转归和分布特征。基于Cd积累动力学，开展了利用“标准化”背角无齿蚌监测、预警渔业生态环境（太湖锡东水厂水域）Cd等重金属污染的应用研究；再通过转录组分析、基因克隆和荧光定量PCR技术，揭示了“泛素调节蛋白水解”通路直接参与“标准化”背角无齿蚌的Cd吸收，推断出ECaC和DMT为Cd吸收通道；在此基础上，突破了蚌鳃细胞的体外培养难题，成功获得了体外培养时间可长达5 d且细胞存活率≥90%的原代培养鳃细胞，并通过建立鳃细胞损伤模型，解析了Cd的毒性机制。通过本项目的开展，取得了大量突破性的研究成果（如论文、专利、奖项等）。这些成果对我国渔业水域生态环境、水产品质量安全的保护将具有重要意义，也可对国家水环境“湖长制”、“河长制”管理提供亟需的理论支撑。