Feminization of male fish and the role of endocrine‐active chemicals in this phenomenon has been an area of intense study for many years. Estrone (E1), a natural steroid, is found in aquatic environments sometimes at high concentrations relative to the estrogenic steroids 17β‐estradiol (E2) and 17α‐ethynylestradiol. However, E1 has been less thoroughly studied than E2 or 17α‐ethynylestradiol due in part to a relatively lower potency in metabolically limited estrogen receptor (ER) binding/activation assays. Recent evidence suggests that in vivo biotransformation of E1 to E2 may occur in fathead minnows (Pimephales promelas) residing in environments with high concentrations of E1, such as near wastewater treatment plants. The enzymes likely responsible for this biotransformation, 17β‐hydroxysteroid dehydrogenases (17βHSDs), have been well characterized in mammals but to a lesser extent in fish species. In the present study, a novel systematic analysis of amino acid sequence data from the National Center for Biotechnology Information database demonstrated that multiple 17βHSD isoforms are conserved across different fish species. Experimentally, we showed that metabolically active hepatic cytosolic preparations from 2 commercially important salmonid species, rainbow trout and lake trout, biotransformed E1 to E2 to a degree sufficient to alter results of competitive ER binding assays. These results from in silico and in vitro analyses indicate that E1 and biotransformation may play a significant role in adverse effects on development and reproduction of a variety of fish species in contaminated aquatic environments. Environ Toxicol Chem 2020;39:2028–2040. Published 2020. This article is a US Government work and is in the public domain in the USA.

中文翻译：

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雌酮转化为 17β-雌二醇：评估环境雌激素对鱼类风险的潜在混杂因素

雄性鱼的雌性化和内分泌活性化学物质在这一现象中的作用多年来一直是一个深入研究的领域。雌酮 (E1) 是一种天然类固醇，在水生环境中发现的浓度有时高于雌激素类固醇 17β-雌二醇 (E2) 和 17α-乙炔雌二醇。然而，与 E2 或 17α-乙炔雌二醇相比，E1 的研究较少，部分原因是代谢受限的雌激素受体 (ER) 结合/激活测定中的效力相对较低。最近的证据表明，E1 到 E2 的体内生物转化可能发生在黑头鲦鱼（Pimephales promelas) 居住在 E1 浓度高的环境中，例如污水处理厂附近。可能负责这种生物转化的酶，17β-羟基类固醇脱氢酶 (17βHSDs)，已在哺乳动物中得到很好的表征，但在鱼类中的程度较低。在本研究中，对来自国家生物技术信息中心数据库的氨基酸序列数据进行的新系统分析表明，多种 17βHSD 同种型在不同鱼类中是保守的。在实验上，我们发现来自 2 种商业上重要的鲑鱼物种虹鳟和湖鳟的代谢活性肝细胞溶质制剂将 E1 生物转化为 E2 到足以改变竞争性 ER 结合测定结果的程度。环境毒物化学2020；39:2028–2040。2020 年出版。本文是美国政府的作品，在美国属于公共领域。