Beaumelle Léa, Hedde Mickaël, Vandenbulcke Franck, Lamy Isabelle
UMR ECOSYS, INRA, AgroParisTech, Université Paris Saclay, 78026, Versailles, France.
LGCgE-Lille 1, Ecologie Numérique et Ecotoxicologie, Université de Lille, 59650 Villeneuve d'Ascq, France.
Environ Pollut. 2017 May;224:185-194. doi: 10.1016/j.envpol.2017.01.078. Epub 2017 Mar 9.
Partitioning tissue metal concentration into subcellular compartments reflecting toxicologically available pools may provide good descriptors of the toxicological effects of metals on organisms. Here we investigated the relationships between internal compartmentalization of Cd, Pb and Zn and biomarker responses in a model soil organism: the earthworm. The aim of this study was to identify metal fractions reflecting the toxic pressure in an endogeic, naturally occurring earthworm species (Aporrectodea caliginosa) exposed to realistic field-contaminated soils. After a 21 days exposure experiment to 31 field-contaminated soils, Cd, Pb and Zn concentrations in earthworms and in three subcellular fractions (cytosol, debris and granules) were quantified. Different biomarkers were measured: the expression of a metallothionein gene (mt), the activity of catalase (CAT) and of glutathione-s-transferase (GST), and the protein, lipid and glycogen reserves. Biomarkers were further combined into an integrated biomarker index (IBR). The subcellular fractionation provided better predictors of biomarkers than the total internal contents hence supporting its use when assessing toxicological bioavailability of metals to earthworms. The most soluble internal pools of metals were not always the best predictors of biomarker responses. metallothionein expression responded to increasing concentrations of Cd in the insoluble fraction (debris + granules). Protein and glycogen contents were also mainly related to Cd and Pb in the insoluble fraction. On the other hand, GST activity was better explained by Pb in the cytosolic fraction. CAT activity and lipid contents variations were not related to metal subcellular distribution. The IBR was best explained by both soluble and insoluble fractions of Pb and Cd. This study further extends the scope of mt expression as a robust and specific biomarker in an ecologically representative earthworm species exposed to field-contaminated soils. The genetic lineage of the individuals, assessed by DNA barcoding with cytochrome c oxidase subunit I, did not influence mt expression.
将组织金属浓度划分为反映毒理学可用库的亚细胞区室，可能为金属对生物体的毒理学效应提供良好的描述指标。在此，我们研究了镉、铅和锌的内部分室化与一种模式土壤生物——蚯蚓体内生物标志物反应之间的关系。本研究的目的是确定反映内栖性、自然存在的蚯蚓物种（暗色异唇蚓）暴露于实际受污染田间土壤时的毒性压力的金属组分。在对31种受污染田间土壤进行21天暴露实验后，对蚯蚓及三个亚细胞组分（胞质溶胶、碎片和颗粒）中的镉、铅和锌浓度进行了定量分析。测定了不同的生物标志物：金属硫蛋白基因（mt）的表达、过氧化氢酶（CAT）和谷胱甘肽 - S - 转移酶（GST）的活性，以及蛋白质、脂质和糖原储备。生物标志物进一步组合成一个综合生物标志物指数（IBR）。亚细胞分级比总内部含量能更好地预测生物标志物，因此支持在评估金属对蚯蚓的毒理学生物可利用性时使用它。金属最易溶的内部库并不总是生物标志物反应的最佳预测指标。金属硫蛋白的表达对不溶组分（碎片 + 颗粒）中镉浓度的增加有反应。蛋白质和糖原含量也主要与不溶组分中的镉和铅有关。另一方面，胞质溶胶组分中的铅能更好地解释GST活性。CAT活性和脂质含量的变化与金属亚细胞分布无关。IBR最好由铅和镉的可溶和不溶组分共同解释。本研究进一步扩展了mt表达作为暴露于受污染田间土壤的具有生态代表性的蚯蚓物种中一种稳健且特异的生物标志物的范围。通过细胞色素c氧化酶亚基I的DNA条形码评估的个体遗传谱系并未影响mt表达。
