利用水螅检测Cd^(2+)毒性的研究方法比较

COMPARISONS OF THE METHODS FOR ASSESSING THE TOXICITY OF Cd^(2+) BY USING HYDRA SINENSIS

利用中国水螅,分别检测了自来水、无EDTA培养液(NEC)、含EDTA培养液(HEC)内Cd2+抑制水螅摄食的10min半数效应浓度(10minEC50)和24h、48h、72h的LC50。结果表明:(1)自来水、NEC、HEC的对照组10min已摄食个体数分别为94.17%、94.66%和51.90%;(2)自来水组与NEC组的10minEC50分别为0.991mg/L和4.300mg/L;(3)自来水组、NEC组、HEC组24hLC50的Cd2+浓度分别为0.138mg/L、0.330mg/L和0.473mg/L;其48hLC50分别为0.046mg/L、0.080mg/L和0.203mg/L;其72hLC50分别为0.036mg/L、0.040mg/L和0.307mg/L。经分析认为,HEC对水螅摄食具抑制作用,对重金属具螯合作用,不宜用于水螅培养和重金属毒理实验;自来水因各地水质指标的差异,不宜用于毒理实验;NEC是理想的毒理实验稀释液与培养液。研究提出的10minEC50的方法简便、快速。中国水螅比其他水螅更易繁殖,便于鉴别,是毒理实验理想的模式生物。

Methods in the acute toxicity test of cadmium（Cd^2＋） were explored by using Hydra sinensis.The median effective concentrations of Cd^2＋ by feeding inhibition experiment in 10min（10min-EC50） and median lethal concentrations（LC50） of Cd^2＋ were determined in hydras cultured in tap water,non-EDTA culture solution（NEC）,and culture solution with EDTA（HEC） in 24h,48h and 72h,respectively.As a result,predation rates of the control group cultured in tap water,NEC and HEC in 10 min were 94.17%,94.66% and 51.90%,respectively.The 10min-EC50s of the tap water group and NEC group were 0.991 mg/L and 4.300 mg/L respectively.LC50s of Cd^2＋ in hydras cultured in tap water,NEC and HEC in 24h were 0.138 mg/L,0.330 mg/L and 0.473 mg/L,respectively;in 48h were 0.046 mg/L,0.080 mg/L and 0.203 mg/L,respectively;in 72h were 0.036 mg/L,0.040 mg/L and 0.307 mg/L,respectively.The results indicated that HEC was unsuitable for culturing Hydra and carrying out the toxicity test of heavy metals as HEC inhibited hydra＇s feeding behavior and had the chelating effect for heavy metal as well.The tap water was also unsuitable for carrying out the toxicity test because the water from different cities could not reach the same quality standard.By comparison,NEC was the suitable culture solution to carry out the toxicity test of heavy metals in hydras and 10min-EC50 was the best method for toxicity test of Cd^2＋ due to the characteristics of simpleness and convenience.At last,as H.sinensis can easily be identified and reproduced,it was proposed here as a model organism for toxicity test of heavy metals.