Institute for Genomics, Biocomputing and Biotechnology, Mississippi State University, Starkville, Mississippi, United States.
Environ Sci Technol. 2012 Jan 3;46(1):42-50. doi: 10.1021/es201245b. Epub 2011 Aug 5.
Small organisms can be used as biomonitoring tools to assess chemicals in the environment. Chemical stressors are especially hard to assess and monitor when present as complex mixtures. Here, fifteen polymerase chain reaction assays targeting Daphnia magna genes were calibrated to responses elicited in D. magna exposed for 24 h to five different doses each of the munitions constituents 2,4,6-trinitrotoluene, 2,4-dinitrotoluene, 2,6-dinitrotoluene, trinitrobenzene, dinitrobenzene, or 1,3,5-trinitro-1,3,5-triazacyclohexane. A piecewise-linear model for log-fold expression changes in gene assays was used to predict response to munitions mixtures and contaminated groundwater under the assumption that chemical effects were additive. The correlations of model predictions with actual expression changes ranged from 0.12 to 0.78 with an average of 0.5. To better understand possible mixture effects, gene expression changes from all treatments were compared using high-density microarrays. Whereas mixtures and groundwater exposures had genes and gene functions in common with single chemical exposures, unique functions were also affected, which was consistent with the nonadditivity of chemical effects in these mixtures. These results suggest that, while gene behavior in response to chemical exposure can be partially predicted based on chemical exposure, estimation of the composition of mixtures from chemical responses is difficult without further understanding of gene behavior in mixtures. Future work will need to examine additive and nonadditive mixture effects using a much greater range of different chemical classes in order to clarify the behavior and predictability of complex mixtures.
小型生物可以作为生物监测工具，用于评估环境中的化学物质。当化学物质以复杂混合物的形式存在时，尤其难以进行评估和监测。在这里，我们校准了针对大型溞基因的 15 种聚合酶链反应检测方法，这些方法针对的是大型溞在暴露于 24 小时的五种不同剂量的弹药成分 2,4,6-三硝基甲苯、2,4-二硝基甲苯、2,6-二硝基甲苯、三硝基苯、二硝基苯或 1,3,5-三硝基-1,3,5-三嗪环已烷时所引起的反应。我们使用了一种分段线性模型来预测基因检测的对数倍表达变化，假设化学效应是可加的，从而预测弹药混合物和受污染地下水的反应。模型预测与实际表达变化的相关性范围从 0.12 到 0.78，平均为 0.5。为了更好地理解可能的混合物效应，我们使用高密度微阵列比较了所有处理的基因表达变化。尽管混合物和地下水暴露与单一化学物质暴露具有相同的基因和基因功能，但也会影响到独特的功能，这与这些混合物中化学效应的不可加性一致。这些结果表明，虽然基于化学暴露，基因对化学暴露的反应行为可以部分预测，但如果没有进一步了解基因在混合物中的行为，就很难从化学反应中估计混合物的组成。未来的工作将需要使用更多不同化学类别的混合物来检查加性和非加性混合物效应，以便澄清复杂混合物的行为和可预测性。
