北部湾文蛤体内氧化逆境标志物对重金属积累的响应研究

Study on the responses of oxidative stress biomarkers to heavy metals accumulation in the clam Meretrix meretrix along the Beibu Bay

研究目的是通过评价北部湾文蛤(Meretrix meretrix)体内7种氧化逆境标志物对重金属积累的响应,筛选出能够灵敏指示海域现场重金属污染压力的生物标志物.2011年秋季,在北部湾沿海潮间带6个典型站位采集文蛤样品,测定软组织中重金属含量及鳃、内脏中7种氧化逆境标志物水平,分析其空间、组织分布特征,然后对标志物水平与重金属含量进行相关性分析.结果表明,文蛤软组织中重金属积累量和氧化逆境标志物水平在站位间存在很大差异.大多数氧化逆境标志物具有明显的组织差异性,鳃中的超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GPx)、谷胱甘肽转硫酶(GST)活性以及还原型谷胱甘肽(GSH)、氧化型谷胱甘肽(GSSG)含量均高于内脏,过氧化氢酶(CAT)在内脏中的活性较高,而硫代巴比妥酸反应物(TBARs)在两组织中无明显的分布差异.多种重金属共存的情况下,鳃的GSH/GSSG与软组织Cd含量有显著相关性;4种抗氧化酶中,鳃CAT对Pb具有显著正响应,内脏CAT、GST对As具有显著负响应.鳃TBARs分别与Hg、Cd含量呈显著正相关、负相关,内脏TBARs则与Pb含量呈负相关,表明这些标志物能够灵敏指示重金属对文蛤抗氧化防御机能的影响,适于作为评价北部湾重金属污染压力的指标.

The research was designed to select the biomarkers which can sensitively indicate the heavy metals pollution pressure by evaluating the responses of the seven oxidative stress biomarkers to heavy metals accumulation in native clams Meretrix meretrix along Beibu Bay. In the autumn of 2011, native clams Meretrix meretrix from 6 sampling sites in the intertidal zone was examined. The contents of heavy metals in soft tissue and oxidative stress biomarkers in gill and digestive gland of clams were measured. The distribution characteristics of metals and biomarkers were also analyzed. Based on the analysis, we conducted correlation analysis between biomarkers and the contents of heavy metals. The result showed that there were great differences between heavy metals accumulation and oxidation stress biomarkers responses. Most oxidation stress biomarkers have obvious organizational differences. The contents of SOD, GPx, GST, GSH and GSSG in gill were higher than digestive gland, while CAT activity was higher in digestive gland. For TBARs there were no obvious differences between the two issues. In the environment that contains a variety of heavy metals, GSH/GSSG in gill and Cd in soft tissue have significant correlations. As for the antioxidant enzymes, CAT in gill has significant positive response with Pb, while GST in digestive gland has negative response with As. Besides, TBARs in gill has significant positive correlation with Hg and negative correlation with Cd. In addition, TBARs in digestive glands has negative correlation with Pb. Correlation analysis indicated that several kinds of biomarkers can sensitively indicate the influence of heavy metals on Meretrix meretrix antioxidant defense, therefore could be used as suitable indicators for the assessment of heavy metals contamination pressure of Beibu Bay.