Gulf Ecosystem Measurement & Modeling Division, US Environmental Protection Agency, Gulf Breeze, Florida, USA.
Exposure Methods and Measurement Division, US Environmental Protection Agency, Athens, Georgia, USA.
Environ Toxicol Chem. 2020 Sep;39(9):1797-1812. doi: 10.1002/etc.4758. Epub 2020 Jul 7.
Standard ecological risk assessment practices often rely on larval and juvenile fish toxicity data as representative of the amphibian aquatic phase. Empirical evidence suggests that endpoints measured in fish early life stage tests are often sufficient to protect larval amphibians. However, the process of amphibian metamorphosis relies on endocrine cues that affect development and morphological restructuring and are not represented by these test endpoints. The present study compares developmental endpoints for zebrafish (Danio rerio) and the African clawed frog (Xenopus laevis), 2 standard test species, exposed to the herbicide trifluralin throughout the larval period. Danio rerio were more sensitive and demonstrated a reduction in growth measurements with increasing trifluralin exposure. Size of X. laevis at metamorphosis was not correlated with exposure concentration; however, time to metamorphosis was delayed relative to trifluralin concentration. Gene expression patterns indicate discrepancies in response by D. rerio and X. laevis, and dose-dependent metabolic activity suggests that trifluralin exposure perturbed biological pathways differently within the 2 species. Although many metabolites were correlated with exposure concentration in D. rerio, nontargeted hepatic metabolomics identified a subset of metabolites that exhibited a nonmonotonic response to trifluralin exposure in X. laevis. Linking taxonomic distinctions in cellular-level response with ecologically relevant endpoints will refine assumptions used in interspecies extrapolation of standard test effects and improve assessment of sublethal impacts on amphibian populations. Environ Toxicol Chem 2020;39:1797-1812. Published 2020. This article is a US government work and is in the public domain in the USA.
标准的生态风险评估实践通常依赖于幼鱼和幼体鱼类毒性数据来代表两栖动物的水生阶段。经验证据表明，在鱼类早期生活阶段测试中测量的终点通常足以保护幼体两栖动物。然而，两栖动物变态的过程依赖于内分泌信号，这些信号会影响发育和形态结构重建，而这些测试终点并不能代表这些信号。本研究比较了暴露于除草剂氟乐灵整个幼虫期的斑马鱼（Danio rerio）和非洲爪蟾（Xenopus laevis）这两种标准测试物种的发育终点。斑马鱼对氟乐灵更敏感，随着氟乐灵暴露量的增加，生长测量值降低。变态时非洲爪蟾的大小与暴露浓度无关；然而，相对于氟乐灵浓度，变态时间被延迟。基因表达模式表明，D. rerio 和 X. laevis 的反应存在差异，并且剂量依赖性代谢活性表明氟乐灵暴露在这两个物种内以不同的方式扰乱了生物途径。尽管许多代谢物与 D. rerio 中的暴露浓度相关，但非靶向性肝代谢组学鉴定出一组代谢物在 X. laevis 中对氟乐灵暴露表现出非单调响应。将细胞水平反应的分类学差异与生态相关终点联系起来，将细化在种间外推标准测试效果中使用的假设，并改善对两栖动物种群亚致死影响的评估。环境毒理化学 2020；39：1797-1812。发布 2020。本文是美国政府的一项工作，在美国境内属于公有领域。
