The branched isomer mixture 4‐nonylphenol (4‐NP) has been used worldwide as a surfactant, and can have endocrine‐disrupting effects on aquatic organisms. For instance, 4‐NP induces the formation of testis‐ova (i.e., testicular and ovarian tissue in the same gonad) or male to female sex reversal of various teleost fishes. Recently, our group revealed that altered gsdf gene expression is associated with disruption of gonadal differentiation in Japanese medaka (Oryzias latipes) embryos exposed to methyltestosterone or bisphenol A, suggesting that gsdf might be useful as a biomarker for predicting the impact of endocrine‐disrupting chemicals (EDCs) on gonadal differentiation. Here, we used 4‐NP to examine further whether gsdf expression at the embryo stage is useful for predicting EDC impact on gonadal sex differentiation. When fertilized medaka eggs were exposed to 32 or 100 μg/L 4‐NP, testis‐ova in genetic males and sex reversal from genetic male to phenotypic female were observed. At stage 38 (just before hatching), 4‐NP exposure at 1‐100 μg/L did not affect gsdf expression in XX embryos compared with the nontreated control; however, in XY embryos, the gsdf expression in the 100 μg/L‐exposed group was significantly lower than that in the controls. The 4‐NP concentration at which gsdf expression was suppressed was equal to that at which testis‐ova and sex reversal were induced. These results indicate that expression of the gsdf gene at the embryonic stage in medaka is a useful biomarker for predicting the impact of EDCs on sexual differentiation.

中文翻译：

---

暴露于 4-壬基酚会导致日本青鳉 (Oryzias latipes) gsdf 和睾丸卵子形成和性别逆转的基因表达发生变化

支链异构体混合物 4-壬基苯酚 (4-NP) 已在世界范围内用作表面活性剂，可对水生生物产生内分泌干扰作用。例如，4-NP 诱导睾丸卵子（即同一性腺中的睾丸和卵巢组织）的形成或各种硬骨鱼的雄性向雌性逆转。最近，我们的小组发现，gsdf基因表达的改变与暴露于甲基睾酮或双酚 A 的日本青鳉（Oryzias latipes）胚胎的性腺分化破坏有关，这表明gsdf可能可用作预测内分泌干扰化学物质影响的生物标志物(EDC) 对性腺分化的影响。在这里，我们使用 4-NP 来进一步检查gsdf胚胎阶段的表达可用于预测 EDC 对性腺性别分化的影响。当受精的青鳉卵暴露于 32 或 100 μg/L 4-NP 时，观察到遗传雄性的睾丸卵子和遗传雄性到表型雌性的性别逆转。在第 38 阶段（孵化前），与未处理的对照相比，1-100 μg/L 的 4-NP 暴露不影响XX 胚胎中的gsdf表达；然而，在 XY 胚胎中，100 μg/L 暴露组的gsdf表达显着低于对照组。抑制gsdf表达的 4-NP 浓度等于诱导睾丸卵子和性逆转的浓度。这些结果表明gsdf 的表达 medaka 胚胎阶段的基因是一种有用的生物标志物，可用于预测 EDCs 对性别分化的影响。