Previous studies have shown that BDE-47, one of the most abundant polybrominated diphenyl ethers (PBDEs) congeners, has a weak estrogenic activity, but it has remained unclear whether BDE-47 disrupts gonadal development and causes male-to-female sex reversal in lower vertebrates, with limited and controversial data. The present study aimed to determine the effects of BDE-47 on gonadal development in Xenopus laevis, a model amphibian species for studying adverse effects of estrogenic chemicals on reproductive development. X. laevis at stage 45/46 were exposed to BDE-47 (0.5, 5, 50 nM) in semi-static system, with 1 nM 17β-estradiol (E2) as the positive control. When reaching stage 53, tadpoles were examined for gonadal morphology, histology and sex-dimorphic gene expression. The phenotypic sex (gonadal morphology and histology) of each BDE-47-treated tadpole matched its genetic sex, showing no sex-reversal, whereas one half of genetic males treated with E2 displayed ovarian-like features. However, some genetic males (26%) in the 50 nM BDE-47 treatment group were found to contain more germ cells clumping together in the medulla, along with an increasing tendency of the gonad length/kidney length ratio in males, resembling feminizing outcomes of E2. These observations seem to suggest that BDE-47 exerted weak feminizing effects. However, BDE-47 induced increases in expression of both female-biased genes and male-biased genes in two sexes, which disagrees with feminizing outcomes, suggesting complicated effects of BDE-47 on gonadal development. Taken together, all results demonstrate that nanomolar BDE-47 disrupted gonadal development and exerted weak feminizing effects, but not resulted in male-to-female sex reversal in X. laevis.

中文翻译：

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2,2'，4,4'-四溴二苯醚（BDE-47）破坏了非洲爪蛙（Xenopus laevis）的性腺发育。

先前的研究表明，BDE-47是最丰富的多溴联苯醚（PBDEs）同系物之一，雌激素活性较弱，但尚不清楚BDE-47是否会破坏性腺发育并引起雌雄性逆转。低等脊椎动物，数据有限且有争议。本研究旨在确定BDE-47对非洲爪蟾（Xenopus laevis）的性腺发育的影响，非洲爪蟾是一种两栖动物模型，用于研究雌激素化学物质对生殖发育的不利影响。在半静态系统中，将处于阶段45/46的X. laevis暴露于BDE-47（0.5、5、50 nM），以1 nM17β-雌二醇（E2）作为阳性对照。到达第53阶段时，检查了for的性腺形态，组织学和性别双态基因表达。每个经BDE-47治疗的t的表型性（性腺形态和组织学）与其遗传性相匹配，没有性别逆转，而接受E2处理的遗传男性中有一半表现出类似卵巢的特征。但是，发现50 nM BDE-47治疗组中的某些遗传雄性（26％）在髓质中包含更多的聚集在一起的生殖细胞，以及雄性腺长度/肾脏长度比的增加趋势，类似于女性化的结果。 E2。这些观察结果似乎表明，BDE-47的女性化作用较弱。但是，BDE-47诱导了两个性别的女性偏向基因和男性偏向基因的表达增加，这与女性化的结果不同，这表明BDE-47对性腺发育的复杂影响。在一起