Laboratory of Molecular Reproductive Biology, Institute for Environmental Science, University of Shizuoka, Shizuoka, Shizuoka 422-8526, Japan.
Department of Environmental Science, Institute of Science and Technology, Niigata University, Ikarashi, Niigata 950-2181, Japan.
Zoolog Sci. 2019 Oct;36(5):425-431. doi: 10.2108/zs180194.
We compared sex-reversal ratios induced by 17α-methyltestosterone (MT) and 17β-estradiol (E2) exposure in two inbred medaka strains: Hd-rR derived from and HNI-II from . All MT exposures (0.2-25 ng mL) induced complete XX sex-reversal in HNI-II. Although MT exposure at 0.2 ng mL induced XX sex-reversal at > 95% in Hd-rR, other concentrations tested caused XX sex-reversal at lower frequencies (<50%). MT exposure at 1, 5, and 25 ng mL induced XY sex-reversal in Hd-rR, but not in HNI-II. In Hd-rR, E2 exposure induced XY sex-reversal at > 10 ng mL, and in all fish feminization occurred 500 ng mL. In HNI-II, E2 induced XY sex-reversal at 50 and 250 ng mL, but only at rates below 20%. To clarify whether the strain differences in sex hormone-induced sex-reversal are characteristic of each species, we examined the effects of MT and E2 exposure on sex differentiation in five and two additional strains or wild stocks/populations of and , respectively. MT exposure induced low XX and high XY sex-reversal rates in , except in the Shizuoka population, but the trend was reversed in . Furthermore, E2-induced XY sex-reversal rates varied intraspecifically in . Our results demonstrated that sensitivity to MT and E2 varied within species. To evaluate the ecological impacts of environmental chemicals using medaka, it is important to define not only the species, but the strains, stocks, and populations to obtain accurate results.
我们比较了 17α-甲基睾丸酮（MT）和 17β-雌二醇（E2）暴露在两个近交系红大麻哈鱼中的性别反转比率：Hd-rR 来自 ，HNI-II 来自 。所有 MT 暴露（0.2-25ng/mL）在 HNI-II 中诱导完全的 XX 性别反转。虽然 MT 在 0.2ng/mL 的暴露在 Hd-rR 中诱导了超过 95%的 XX 性别反转，但其他测试浓度导致 XX 性别反转的频率较低（<50%）。MT 在 1、5 和 25ng/mL 的暴露在 Hd-rR 中诱导了 XY 性别反转，但在 HNI-II 中没有。在 Hd-rR 中，E2 暴露在>10ng/mL 时诱导 XY 性别反转，在所有鱼类中 500ng/mL 时发生雌性化。在 HNI-II 中，E2 在 50 和 250ng/mL 时诱导 XY 性别反转，但仅在低于 20%的频率下发生。为了阐明性别激素诱导的性别反转的品系差异是否是每个物种的特征，我们研究了 MT 和 E2 暴露对五个和另外两个 的品系或野生种群/群体的性别分化的影响。MT 暴露在 中诱导低 XX 和高 XY 性别反转率，除了静冈种群外，但在 中则相反。此外，E2 诱导的 XY 性别反转率在 中存在种内差异。我们的结果表明，对 MT 和 E2 的敏感性在 物种内有所不同。为了使用红大麻哈鱼评估环境化学品的生态影响，重要的是不仅要定义物种，还要定义品系、种群和群体，以获得准确的结果。
