[Objective]The aim was to assess the status of heavy metal pollution of Hunhe River and its ecological health impact on aquatic or-ganisms.[Method]The content of heavy metal elements like Al,Cr,Cu,Fe,Mg,Mn and Zn was determined.The model organism zebrafish were exposed to Hunhe River for 90 days,and the accumulation of heavy metal and the concentrations of superoxide dismutase(SOD),catalase (CAT),glutathione(GSH),glutathione-S-transferase(GST),lipid peroxidation(MDA)and acetylcholinesterase(AChE),total antioxidant ca-pacity(T-AOC)and Na +/K +-ATPase activity were determined in the brain,gill,liver,intestine and muscle tissue of zebrafish.[Result]The heavy metal elements in the Hunhe River were in line with the national standards ofⅡlevel,but compared with control group,the concentration of Cu,Fe,Mn,zinc element was increased by 42.9%,217.2%,77.8% and 96.2%,respectively.Different accumulation degrees in the brain,gill, liver,intestine and muscle tissues of zebrafish under the stress of Hunhe River,and the highest accumulation was in liver tissue.At the same time, the increasing rate of SOD and CAT in liver tissue was 109.1% and 32.0%,respectively,while T-AOC was decreased significantly at the rate of 28.5%,indicating that the antioxidant capacity of liver tissue decreased.MDA was significantly increased at the rate of 59.2%in gill tissue,indi-cating that heavy metal in water induced lipid peroxidation and induced oxidative damage in gill tissues of zebrafish.[Conclusion]The results show that liver and gill tissues of zebrafish were sensitive,and SOD,CAT,T-AOC and MDA can be used as sensitive biomarkers for toxicological research,and early warning of integrated toxicity of water.

[Objective] To study the effect of Cd and Cu stress on the genomic DNA methylation levels and states of Arabidopsis thaliana.[Method] Arabidopsis thaliana was planted in different concentration nutrient solution with 0,0.5 mg/L Cd,5.0 mg/L Cd,0.5 mg/L Cu,5.0 mg/L Cu for 21 days.Genomic DNA was extracted to conduct methylation-sensitive amplification polymorphism(MSAP) analysis.[Result] MSAP rate of 0,0.5 mg/L Cd,5.0 mg/L Cd,0.5 mg/L Cu,5.0 mg/L Cu was 30.2%,34.7%,41.0%,33.9%,39.2%,DNA methylation polymorphism rate of 0.5 mg/L Cd,5.0 mg/L Cd,0.5 mg/L Cu,5.0 mg/L Cu were 2.6%,13.2%,2.4%,11.2%,respectively.[Conclusion] Arabidopsis thaliana genome DNA methylation level and methylation polymorphism under Cd and Cu stress increases with the concentration increased obviously,the effect of Cd for the change of DNA methylation level and polymorphism is greater than Cu.

DNA cytosine methylation is a central epigenetic modification that has essential roles in the control of many critically important biological processes,including cell proliferation,differentiation,development,genomic imprinting and regulation of gene expression.With progresses in study on DNA methylation,detection techniques of DNA methylation have been developed to meet requirements of various researches.This article has established an improved bisulfite sequencing technique for analysis of MutL-homologue 1(MLH1) promoter methylation level of mismatch repair gene in Arabidopsis thaliana.After the genomic DNA in Arabidopsis thaliana was digested,purified,and then modified with bisulfite liquid,the PCR products were cloned into the pEASY-T1 vector.15 positive clones were randomly selected from each sample and then sequenced.The results showed that compared with the traditional method of methylation analysis,the improved method modified the digested DNA completely,reduced the modification time greatly,and improved the specificity,stability and repeatability of the PCR products.MLH1 promoter methylation level was 27.3% instead of 45.6%.The improved bisulfite sequencing technique avoided misidentification at non-methylated sites,and would provide a better means of research for analysis of DNA methylation in plant.

采用随机扩增多态性DNA（random amplified polymorphic DNA,RAPD）标记技术,并结合幼苗的形态和生理指标,研究镉（Cd）胁迫对拟南芥（Arabidopsis thaliana）幼苗基因组DNA损伤的影响。结果表明,不同浓度（0.25～5.0mg·L-1）Cd处理24d后,拟南芥幼苗根生长受到显著抑制,地上部分可溶性蛋白质含量呈先升高后降低的趋势,但对拟南芥幼苗叶片数、鲜重及叶绿素含量影响不大。选用12条寡核苷酸引物对拟南芥幼苗地上部分与根系基因组DNA进行PCR（polymerase chain reaction）扩增,发现处理组与对照组RAPD图谱之间存在明显差异,且与镉浓度之间存在剂量-效应关系。基因组模板的稳定性（genomic template stability,GTS）随着Cd浓度的增加而降低。3个处理组幼苗地上部分GTS分别为91%、89%和80%;相应根部GTS分别为71%、67%和60%。研究表明,利用RAPD技术获得的拟南芥DNA多态性变化可作为检测镉遗传毒性效应的生物标记物。比照其他几个指标,拟南芥幼苗根部RAPD谱带变化的敏感性更为优异,具有较好的应用前景。