水相Cd2+在南美白对虾体内的富集及氧化应激特征

ENRICHMENT AND OXIDATIVE STRESS CHARACTERISTICS OF CD2+ IN LITOPENAEUS VANNAMEI IN AQUEOUS ENVIRONMENT

  • 摘要: 为阐明水相环境中重金属镉元素(Cadmium, Cd)在甲壳类海产品中的富集与代谢过程、亚细胞微区分布特征和生物体氧化应激效应, 文章以南美白对虾(Litopenaeus vannamei)为研究对象, 应用双箱动力学模型设置了水环境下不同Cd暴露水平的富集吸收与清水净化释放试验, 实时监测南美白对虾内脏团和肌肉组织的Cd含量及谷胱甘肽巯基转移酶(Glutathione S-transferase, GST)、谷胱甘肽过氧化物酶(Glutathione peroxidase, GPx)和过氧化氢酶(Catalase, CAT)酶活力随时间变化情况, 同时结合差速离心技术分析了Cd富集后在机体内脏组织团中的亚细胞微区分布特征。实验得出南美白对虾对水环境中Cd的富集能力与水体暴露浓度呈明显的正相关关系, 内脏团组织是南美白对虾最主要的Cd元素吸收与代谢组织, 其对Cd的吸收速率、净化速率、生物富集因子及平衡状态时Cd含量均显著高于肌肉组织, 在相同暴露剂量下前者的生物富集因子平均为后者的75.5倍, 肌肉组织的Cd生物学半衰期明显长于内脏组织; Cd主要储存于类金属硫蛋白(Metallothionein-like protein, MTLP)和细胞碎片(Cell debris, CD)组分中, 少部分存在于细胞器(Organelle, ORG)、富含金属颗粒(Metal-rich granules, MRG)和热敏感蛋白(Heat sensitive protein, HSP), 且随着富集过程的持续, Cd的亚细胞微区分布发生动态变化, MTLP、ORG和HSP中Cd含量百分比逐渐升高, CD和MRG中的Cd含量百分比呈逐渐下降; 在肝脏和肌肉组织中GST、GPx和CAT酶活力在Cd富集阶段均持续显著升高, 在净化释放阶段处于下降趋势, 同一试验组下肝脏组织中抗氧化酶酶活力明显高于对应的肌肉组织。研究旨在阐述甲壳类海洋生物对环境中Cd元素的富集与分布特征, 了解Cd富集可能性机理, 为海洋甲壳类Cd污染风险评价与环境控制提供科学依据。

     

    Abstract: This study explored the enrichment and metabolism process, subcellular distribution characteristics and oxidative stress effect of heavy metal cadmium (Cd) in crustacean marine products in aqueous environment. Litopenaeus vannamei was used as the research object in this experiment. The enrichment phase of Cd in different exposure levels and pollution release in natural clean seawater were set up by two-box dynamic model. Both Cd content and the enzyme activity of glutathione S-transferase (GST), glutathione peroxidase (GPx) and catalase (CAT) in viscera and muscle tissues of Litopenaeus vannamei were monitored in real time. At the same time, the subcellular distribution characteristics of Cd enriched in viscera were analyzed by method of differential centrifugation. The results showed that the Cd enrichment in Litopenaeus vannamei was significantly positively correlated with the exposure levels in aqueous environment. Viscera was the most important tissue for Cd absorption and metabolism in Litopenaeus vannamei. The Cd absorption rate, purification rate, bioaccumulation factor and Cd content in equilibrium state were significantly higher than those in muscle tissue. Under the same exposure dose, the bioaccumulation factor of the Viscera was 75.5 times that of muscle, and the half-life of Cd in muscle tissue was significantly longer than that in visceral tissue. Cd was mainly stored in metallothionein-like protein (MTLP) and cell debris (CD) components, and a small part of Cd existed in organelle (ORG), metal-rich granules (MRG) and heat sensitive protein (HSP). With the continuous enrichment process, the percentage of Cd content in MTLP, ORG and HSP increased gradually, and the percentage of Cd content in CD and MRG decreased gradually. The activities of GST, GPx and CAT in liver and muscle tissues continued to increase significantly at the Cd enrichment stage, and decreased at the purification and release stage. Under the same experimental group, the activities of antioxidant enzymes in liver tissues were significantly higher than those in corresponding muscle tissues. This study aims to elaborate the enrichment and distribution characteristics of Cd in marine crustacean in the environment, preliminarily understand the possible mechanism of Cd enrichment, and provided scientific basis for risk assessment and environmental control of Cd pollution in marine crustacean.

     

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