镉铅对泥鳅DNA甲基化水平的影响

Influence of cadmium and lead on the DNA methylation level of loach Misgurnus anguillicaudatus

目的研究镉(Cd2+)、铅(Pb2+)以及二者联合(Cd2++Pb2+)作用对泥鳅(Misgurnus anguillicaudatus)肝胰脏、肾脏及鳃DNA甲基化水平的影响。方法0.05和5.00 mg/L Cd2+、Pb2+及Cd2++Pb2+对泥鳅染毒,染毒2、7、14、212、8和35 d时取样,用高效液相色谱(HPLC)分析DNA甲基化水平。结果5.00 mg/L Cd2+、Pb2+及Cd2++Pb2+染毒2 d导致DNA异常高水平甲基化;Cd2+及Cd2++Pb2+的毒性影响大于Pb2+(P<0.05)。0.05 mg/L Cd2+与Pb2+作用下,鳃DNA甲基化水平在第7天时明显升高,而肝胰脏和肾脏则在第14天时升高(P<0.05);染毒21 d后,3种组织甲基化水平均下降,并维持异常低度甲基化。结论Cd2+、Pb2+及Cd2++Pb2+对泥鳅DNA甲基化水平的影响与离子种类、浓度及其作用的时间、靶器官等均具有相关性。

Objective To study the influence of Cadmium（Cd^2＋ ）,lead（Pb^2＋ ） or Cd^2＋ ＋ Pb^2＋ on the total DNA methylation level of hepatopancreas, kidney and gill of the loach Misgurnus anguillicaudatus. Methods Loaches were exposed to Cd^2＋ , Pb^2＋ or Cd^2＋ ＋ Pb^2＋ which were divided into low-concentration（0.05 mg/L） and high-concentration（5.00 mg/L） treatment groups. The DNA methylation level was analyzed with high performance liquid chromatography （HPLC） after 2,7,14,21,28 or 35 d exposure. Results The extremely high DNA methylation was detected after 2 days exposure at high concentration in Cd^2＋ ,Pb^2＋ or Cd^2＋ ＋ Pb^2＋ treatment group; the toxicity effects of Cd^2＋ and Cd^2＋ ＋ Pb^2＋ were more significant than Pb^2＋ （P 〈 0.05 ）. Under the exposure to low concentration Cd^2＋ or Pb^2＋ , the increase of DNA methylation was found in gill at 7 days, while in hepatopancreas or kidney at 14 days. After 21 days treatment, DNA methylation level of hepatopancreas, kidney and gill decreased, and finally stabilized at a lower level than that in control group. Conclusion The influence of heavy metal ions on the DNA total methylatinn was correlative with the kind, concentration, treatment time and target organ of metal ions.