栉孔扇贝在 B[a]P 胁迫下生物标志物筛选的研究

研究采用染毒→清除→二次染毒实验, 研究了 Ba]P 对栉孔扇贝组织解毒代谢酶活力和 DNA 损伤的影响, 筛选了栉孔扇贝在 Ba]P 胁迫下的生物标志物。结果表明: Ba]P 对栉孔扇贝鳃丝、消化盲囊芳烃羟化酶(AHH)、谷胱甘肽硫转移酶(GST)活力和还原型谷胱甘肽含量(GSH)及 DNA 损伤影响显著(P<0.05), 而对照组无明显变化。在一次染毒(0—15d)期间, 除 0.05 μg/L Ba]P 处理组鳃丝 AHH 活力与对照组无明显差异外, 其他处理组组织 AHH 活力均被显著诱导, 于 15d 时达到最大值, GST 活力和 GSH 含量则呈逐渐下降趋势, 5d 时达到最小值, 之后趋于稳定; 而组织 DNA 链断裂(F 值)基本呈下降趋势, DNA-蛋白质交联(DPC 值)呈逐渐升高, 至 15d 时分别达到最小值和最大值。在清除(15—45d)阶段, 各处理组组织 AHH 活力逐渐下降,GST 活力和 GSH 含量则逐渐升高, 在 25—40d 时均恢复至对照组水平; 各处理组组织 F 值和低浓度处理组(0.05、0.5 μg/L)DPC 值分别呈逐渐升高和下降趋势, 于 35—40d 时恢复至对照组水平, 而高浓度处理组(5、10 μg/L)DPC 值仍显著高于对照组水平。在二次染毒(45—60d)期间, 除鳃丝 AHH 活力在 50d 时达到最大值外, 其他指标变化趋势与一次染毒基本一致。由此可见, 栉孔扇贝在 Ba]P 胁迫下组织解毒代谢酶活力和DNA 损伤表现出明显的时间剂量效应性和稳定性, 依据相关性分析, 提出以鳃丝 AHH 活力和消化盲囊 GST活力为防御型生物标志物, 鳃丝、消化盲囊 DPC 值为损伤型生物标志物, 并将 AHH、GST 活力和 DPC 值整合作为 Ba]P 毒性评定的组合型生物标志物, 全面评价 PAHs 的污染毒性。

STUDY OF BIOMARKERS SELECTION OF THE SCALLOP CHLAMYS FARRERI EXPOSED TO B[A]P

Polycyclic aromatic hydrocarbons(PAHs) are ubiquitous environmental contaminants derived from incomplete combustion of carbon.As a pollutant,they are of concern because some compounds have been identified as carcinogenic,mutagenic and teratogenic.Benzopyrene(Ba]P) is a five-ring polycyclic aromatic hydrocarbon whose metabolites are mutagenic and highly carcinogenic.It is listed as a Group 1 carcinogen by the International Agency for Research on Cancer(IARC).Ba]P is the most studied high molecular mass PAH and usually used as the model of PAHs.In China,environmental PAHs concentrations have been increasing day after day,particularly in aquatic environment.Therefore,more and more researchers pay attention to the toxic effects of PAHs/Ba]P on organisms and human health.Biomarkers are important tools for measuring of exposure to and effects of stressors that may arise at the molecular,cellular,physiological or behavioral level of an individual organism.Recently,they have been widely used to assess the effects of pollutants on aquatic animals.In present study,the effects of Ba]P on activities of detoxification metabolism parameters in gills and digestive glands of scallop Chlamys farreri were studied.At first,the clams were exposed to different concentrations of Ba]P(0.05,0.5,5 and 10 μg/L) for 15 days,and then they were cultured in normal seawater without Ba]P for 30 days.At last,the clams were treated with Ba]P for 15 days again.The experiment lasted for 60 days and the gills and digestive glands of the clams in control and different treatments were sampled at 0,5,10,15,20,25,30,35,40,45,50,55 and 60 day respectively.The activities of aryl hydrocarbon hydroxylase(AHH) and Glutathione S-transferase(GST),the content of Glutathione(GSH),DNA damaged and DNA-protein crosslinks(DPC) were tested by Spectrophotometry.The results indicated that the activity of AHH was significantly induced(P<0 05) by Ba]P,while GST activity and GSH content decreased with the increase of Ba]P concentration and the prolong of experimental period.DNA damage and DNA-protein crosslinks were increased with the increase of concentration of Ba]P.All parameters were returned to control level during the clearance stage except the 5 and 10 μg/L groups DPC which were still significant higher than control.When the clams were treated with different concentration of Ba]P again,the change trends of all the parameters were similar to the first stage of Ba]P treatment.The correlation analysis showed that there was a good relativity between the indexes and the concentration of Ba]P.It supposed that all the parameters in the study can be the potential biomarkers for the PAHs contamination assessment.In addition,AHH,GST and DPC value were much more suitable for biological monitoring as the biomarkers because of their stability.They can form the combined biomarkers and used for pollution monitoring sensitively and effectively.In a word,the resulting data in this study may provide basic information of PAHs pollution assessment and the useful monitoring strategy of biomarkers for related departments.What is more,the scientific data must be useful for the assessment of food security in the ocean and estimate the hazard of pollutants to the aquatic products.