Gonadal development in medaka (Oryzias latipes) is dependent on the synergy between estrogens and androgens. Disruption of steroid hormone levels can lead to ovo-testis. To determine the sensitive windows for hormonally induced sex reversal in medaka, we developed a novel 42sp50-GFP_ChgH-GFP transgenic medaka line, allowing the identification of female gonadal tissue by fluorescence present in developing oocytes. Germinal transgenesis resulted in a stable line exhibiting a strong green fluorescent protein signal constitutively in the ovaries and in the liver in response to estrogens. The sensitivity of this line to disruption of sex determination following 16-d chronic exposures was in the nanograms per liter range. To identify the developmental period sensitive to exogenous agents, fry were exposed to 24-h pulses of high concentrations of 17β-estradiol (E2) or 5α-dihydrotestosterone (DHT) at various time points between days postfertilization (dpf) 0 and 12. Evaluation of phenotype followed by genotyping at 16 dpf revealed sensitivity to E2 between 1 and 8 dpf as well as 2 periods of susceptibility to DHT between 0 and 1 dpf and 4 and 8 dpf. No phenotypic sex reversal was detected after exposure to DHT or E2 on 11 or 12 dpf. The observed effects persisted to at least 24 dpf. The identified sensitive embryonic time periods for disruption of sex determination will aid future research on sex determination and the development of screening assays using early embryonic life stages. Environ Toxicol Chem 2020;00:1-10. © 2020 SETAC.

中文翻译：

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转基因Medaka可以识别对性别决定造成干扰的胚胎时期。

medaka（Oryzias latipes）的性腺发育取决于雌激素和雄激素之间的协同作用。类固醇激素水平的破坏会导致卵睾丸。为了确定在青aka中激素诱导的性逆转的敏感窗口，我们开发了一种新型的42sp50-GFP_ChgH-GFP转基因青aka线，可以通过发育中的卵母细胞中的荧光鉴定雌性性腺组织。发芽转基因产生稳定的系，其响应于雌激素而在卵巢和肝脏中组成性地显示强绿色荧光蛋白信号。在连续16天的慢性暴露后，该品系对破坏性别决定的敏感性为每升纳克。为了确定对外源性药物敏感的发育时期，将鱼苗在受精后0天至12天之间的不同时间点暴露于高浓度的17β-雌二醇（E2）或5α-二氢睾丸激素（DHT）的24小时脉冲中。对表型进行评估，然后在16 dpf进行基因分型表明敏感性在1到8 dpf之间的E2以及2到0到1 dpf和4到8 dpf的DHT敏感性。在11或12 dpf下暴露于DHT或E2后未检测到表型性逆转。观察到的影响持续至少24 dpf。识别出的敏感的胚胎时间段会破坏性别决定，这将有助于未来的性别决定研究以及使用早期胚胎生命阶段的筛查方法的开发。环境毒性化学2020; 00：1-10。©2020 SETAC。