Department of Ecology and Evolution Biophore, University of Lausanne, Lausanne, Switzerland.
Present Address: Swiss Federal Institute of Technology (EPFL), 1015, Lausanne, Switzerland.
BMC Genomics. 2019 Jul 15;20(1):583. doi: 10.1186/s12864-019-5955-z.
The synthetic 17α-ethinylestradiol (EE2) is a common estrogenic pollutant that has been suspected to affect the demography of river-dwelling salmonids. One possibility is that exposure to EE2 tips the balance during initial steps of sex differentiation, so that male genotypes show female-specific gene expression and gonad formation. Here we study EE2 effects on gene expression around the onset of sex differentiation in a population of European grayling (Thymallus thymallus) that suffers from sex ratio distortions. We exposed singly-raised embryos to one dose of 1 ng/L EE2, studied gene expression 10 days before hatching, at the day of hatching, and around the end of the yolk-sac stage, and related it to genetic sex (sdY genotype). We found that exposure to EE2 affects expression of a large number of genes, especially around hatching. These effects were strongly sex-dependent. We then raised fish for several months after hatching and found no evidence of sex reversal in the EE2-exposed fish. We conclude that ecologically relevant (i.e. low) levels of EE2 pollution do not cause sex reversal by simply tipping the balance at early stages of sex differentiation, but that they interfere with sex-specific gene expression.
合成的 17α-乙炔基雌二醇（EE2）是一种常见的雌激素污染物，被怀疑会影响洄游性鲑鱼的种群数量。一种可能性是，EE2 的暴露会在性别分化的初始步骤中打破平衡，从而使雄性基因型表现出雌性特异性的基因表达和性腺形成。在这里，我们研究了 EE2 对遭受性别比例扭曲的欧洲红点鲑（Thymallus thymallus）种群在性别分化开始时周围基因表达的影响。我们将单独饲养的胚胎暴露于 1 纳克/升 EE2 剂量中，在孵化前 10 天、孵化当天以及蛋黄囊阶段末期研究基因表达，并将其与遗传性别（sdY 基因型）相关联。我们发现，EE2 的暴露会影响大量基因的表达，尤其是在孵化前后。这些影响强烈依赖于性别。然后，我们在孵化后饲养鱼类数月，没有发现 EE2 暴露的鱼类有性逆转的证据。我们得出结论，生态相关（即低）水平的 EE2 污染不会仅仅通过在性别分化的早期打破平衡来导致性逆转，而是会干扰性别特异性基因表达。
