目前国内普遍采用传统种群和群落指标特征来进行重金属污染对土壤跳虫的研究.在国内首次通过添加不同浓度重金属镉(Cd2+)酵母喂食土壤跳虫室内实验种群白符跳(Folsomia candida),对白符跳体内金属硫蛋白(Metallothionein,MT)进行诱导,并采用实时荧光聚合酶链式反应(real-time fluorescent polymerase chain reaction,Real-time PCR)方法,测定其体内MT信使核糖核酸(mRNA)量的变化,从而判断Cd2+诱导作用下MT表达量的变化.结果表明:Cd2+染毒酵母饲料喂食28 d后,处理组与对照组(0 mg·kg-1 Cd2+)白符跳体内MT基因mRNA转录水平存在差异,MT表达量随Cd2+处理水平的升高而显著上升.在浓度范围探测试验中,1000 mg·kg-1 Cd2+处理组和100 mg·kg-1 Cd2+处理组的MT mRNA转录水平分别是对照组的9355.53倍和731.13倍;在浓度梯度试验中,500 mg·kg-1 Cd2+处理组的MT mRNA水平分别是对照组、12.5 mg·kg-1和250 mg·kg-1处理组的456.54、296.26和7.05倍,250 mg·kg-1和12.5 mg·kg-1处理组的MT mRNA水平分别是对照的64.78倍和1.54倍.这些结果说明:土壤弹尾纲白符跳体内金属硫蛋白mRNA转录水平能够被环境中的Cd2+所诱导,并与之呈正相关关系.以此推测,土壤弹尾虫体内金属硫蛋白mRNA转录水平可作为评价土壤Cd2+污染的潜在生物标志物特征.%Chinese studies on the effects of soil heavy metal pollution on soil collembolans have been based mainly on assessment of responses at the population and community structure level. In the present study, metallothionein (MT) mRNA in the soil collembolan species, Folsomia candida, was induced by the heavy metal, cadmium (Cd), mixed with yeast as a food resource. The MT mRNA amount was measured by real-time fluorescent polymerase chain reaction (Real-time PCR). The results indicated that after 28 days of incubation with the Cd2+ contaminated yeast, the MT mRNA trancription level significantly increased for the high Cd2+ concentration food treatment group. The mRNA treatment levels of 100 and 1000 mg·kg-1 Cd in the range-finding test produced a 731 and 9355 fold increase compared to the control group, respectively. In the final test the MT mRNA levels at 500 mg·kg-1 Cd2+ was 457, 296 and 7.05 times of those at the 0, 12.5 and 250 mg·kg-1 Cd treatments, respectively. These results demonstrate that the MT mRNA transcript level in soil collembolans could be induced and there is a positively correlation with the Cd2+ concentration. This means that the MT mRNA level of Folsomia candida can be used as a potential biomarker for the assessment of soil heavy metal pollution.
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