A synchronized amphibian metamorphosis assay as an improved tool to detect thyroid hormone disturbance by endocrine disruptors and apolar sediment extracts
A synchronized amphibian metamorphosis assay as an improved tool to detect thyroid hormone disturbance by endocrine disruptors and apolar sediment extracts
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DOI：
10.1016/j.chemosphere.2007.06.048
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发表时间：
2007-11-01
期刊：
影响因子：
8.8
通讯作者：
Murk, Albertinka J.
中科院分区：
文献类型：
--
作者：
Gutleb, Arno C.;Schriks, Merijn;Murk, Albertinka J.
两栖动物变态测定用于评估内分泌干扰化合物对甲状腺激素轴的潜在影响。在这项研究中，非洲爪蟾蝌蚪被保存在 0.2% 硫脲 (TU) 溶液中，以阻止并同步它们的发育。这种同步两栖动物变态试验的优点是，同步蝌蚪可以随时开始变态实验，并且与从未处理的动物池中选择的组相比，实验组在实验开始时的同质性要高得多。在整个实验期间，每只动物的水量保持恒定，以克服由于变态和死亡而导致每个水族箱动物数量下降对剩余蝌蚪的密度依赖性发育的影响。 Clophen A50（一种工业 PCB 混合物）、单一同源物 3,3',4,4'-四氯联苯 (PCB 77) 和非极性沉积物提取物先前在 T-Screen（甲状腺激素破坏的体外增殖测定）中测试呈阳性，并在同步两栖动物变态测定中进行了测试。研究的终点包括60天实验期结束时的死亡率、畸形、体重和变态幼蛙的百分比、处于不同发育阶段的蝌蚪的百分比以及依赖于发育阶段的扣分。饮食中接触 Clophen A50（0.2-50 毫克/千克食物）会导致浓度高于 2 毫克/千克食物时未通过变态的蝌蚪百分比显着增加。 60天实验期后能够变态的动物的变态时间显着缩短。 PCB 77（一种易于代谢的同源物）的膳食暴露不会对任何暴露组（2-500 μg/kg 食物）产生显着影响。三个地点中两个受到多种化学物质污染的非极性沉积物提取物显着降低了变态动物的百分比，并显着增加了处于早期和晚期变态阶段的蝌蚪数量。当提取物与环境浓度相比稀释超过 1000 倍（以有机碳为基础）时，这些影响就已经发生。效力等级与 T 筛选获得的结果相当。这表明水生环境中存在甲状腺激素干扰化合物，以及此类化合物可能对野生动物发育产生影响。 (C) 2007 年，爱思唯尔有限公司出版。
Amphibian metamorphosis assays are used to evaluate potential effects of endocrine disrupting compounds on the thyroid hormone axis. In this study, Xenopus laevis tadpoles are kept in a solution of 0.2% thiourea (TU) to arrest and synchronise them in their development.The advantage of this synchronized amphibian metamorphosis assays is that synchronised tadpoles are available at any time to start metamorphosis experiments, and experimental groups arc much more homogenous at the start of experimental exposure compared with groups selected from an untreated pool of animals. The water volume per animal was kept constant throughout the experimental period to overcome the influence of declining numbers of animals per aquarium due to metamorphosis and mortality on the density dependent development of the remaining tadpoles. Clophen A50 (a technical PCB mixture), the single congener 3,3',4,4'-tetrachlorobiphenyl (PCB 77) and apolar sediment extracts that were previously tested positive in the T-Screen, an in vitro proliferation assay for thyroid hormone disruption, were tested in the Synchronized Amphibian Metamorphosis Assay. Endpoints studied were mortality, malformations, body weight, and percentage of metamorphosed froglets at the end of the 60-day experimental period, percentage of tadpoles in different developmental stages, and developmental stage-dependent awarded penalty points. Dietary exposure to Clophen A50 (0.2-50 mg/kg food) resulted in a significant increased percentage of tadpoles that did not pass metamorphosis at concentrations higher than 2 mg/kg food. Time until metamorphosis in those animals that were able to metamorphose after the 60-days experimental period was significantly decreased. Dietary exposure to PCB 77, a congener that can be readily metabolised, did not result in significant effects in any exposure group (2-500 mu g/kg food). Apolar sediment extracts from two of the three sites that are contaminated with a wide variety of chemicals significantly decreased the percentage of metamorphosed animals and significantly increased the number of tadpoles that remained in early and late metamorphic stages. These effects already occurred when the extracts where diluted more than 1000 times (on an organic carbon base) compared to environmental concentrations. The rank of potency was comparable to results obtained with the T-screen. This suggests the presence of thyroid hormone disrupting compounds in the aquatic environment and possible effects of such compounds on animal development in the wild. (C) 2007 Published by Elsevier Ltd.