Environmental Toxicology Graduate Program, University of California, Riverside, CA, 92521, USA; Department of Environmental Sciences, University of California, Riverside, CA, 92521, USA.
Department of Environmental Sciences, University of California, Riverside, CA, 92521, USA; School of Biological Sciences, Plymouth University, PL4 8AA, UK.
Environ Res. 2019 Oct;177:108564. doi: 10.1016/j.envres.2019.108564. Epub 2019 Jun 29.
Bifenthrin (BF) is a pyrethroid insecticide used in urban and agricultural applications. Previous studies in early life stages of fish have indicated anti-estrogenic activity; however, estrogenic activity has been observed in adults. To test the hypothesis that BF impairs sex differentiation, larval Japanese Medaka were exposed to BF during a critical developmental window for phenotypic sexual differentiation. Fish were exposed to environmentally relevant concentrations of BF (0.15 μg/L and 1.5 μg/L), a single concentration (0.3 mg/L) of an estrogen receptor (ER) antagonist (ICI 182,780), and an ER agonist (0.2 ug/L) (17β-estradiol). Fish were exposed at 8 days post hatch (dph) larvae for 30 days. Phenotypic sex, secondary sexual characteristics (SSC) and genotypic sex were investigated at sexual maturity (8 weeks). A trend towards masculinization (p = 0.06) based on the presence of papillary processes in anal fin rays of Japanese Medaka was observed in fish exposed to the lowest concentration of BF. However, genotypic gender ratios were not altered. These results show sex differentiation was not significantly altered by larval exposure to BF in Japanese medaka.
联苯菊酯（BF）是一种用于城市和农业应用的拟除虫菊酯杀虫剂。先前在鱼类早期生命阶段的研究表明其具有抗雌激素活性；然而，在成年鱼类中观察到了雌激素活性。为了验证 BF 会损害性别分化的假设，研究人员在日本青鳉的一个关键发育窗口期间，让幼虫暴露于 BF 中。鱼在暴露于环境相关浓度的 BF（0.15μg/L 和 1.5μg/L）、一种雌激素受体（ER）拮抗剂（ICI 182,780）的单一浓度（0.3mg/L）和一种 ER 激动剂（0.2ug/L）（17β-雌二醇）下进行暴露。从孵化后 8 天（dph）的幼虫开始，暴露 30 天。在性成熟（8 周）时调查表型性别、第二性征（SSC）和基因型性别。在暴露于最低浓度 BF 的日本青鳉中，观察到基于肛鳍射线中出现乳突过程的雄性化趋势（p=0.06）。然而，基因型性别比例没有改变。这些结果表明，BF 对日本青鳉幼虫的暴露并没有显著改变性别分化。
