Leet Jessica K, Richter Catherine A, Cornman Robert S, Berninger Jason P, Bhandari Ramji K, Nicks Diane K, Zajicek James L, Blazer Vicki S, Tillitt Donald E
Columbia Environmental Research Center, United States Geological Survey, Columbia, MO, USA.
Fort Collins Science Center, United States Geological Survey, Fort Collins, CO, USA.
PeerJ. 2020 Oct 2;8:e9614. doi: 10.7717/peerj.9614. eCollection 2020.
Endocrine disrupting contaminants are of continuing concern for potentially contributing to reproductive dysfunction in largemouth and smallmouth bass in the Chesapeake Bay watershed (CBW) and elsewhere. Exposures to atrazine (ATR) have been hypothesized to have estrogenic effects on vertebrate endocrine systems. The incidence of intersex in male smallmouth bass from some regions of CBW has been correlated with ATR concentrations in water. Fish early life stages may be particularly vulnerable to ATR exposure in agricultural areas, as a spring influx of pesticides coincides with spawning and early development. Our objectives were to investigate the effects of early life stage exposure to ATR or the model estrogen 17α-ethinylestradiol (EE2) on sexual differentiation and gene expression in gonad tissue. We exposed newly hatched largemouth bass (LMB, ) from 7 to 80 days post-spawn to nominal concentrations of 1, 10, or 100 µg ATR/L or 1 or 10 ng EE2/L and monitored histological development and transcriptomic changes in gonad tissue. We observed a nearly 100% female sex ratio in LMB exposed to EE2 at 10 ng/L, presumably due to sex reversal of males. Many gonad genes were differentially expressed between sexes. Multidimensional scaling revealed clustering by gene expression of the 1 ng EE2/L and 100 µg ATR/L-treated male fish. Some pathways responsive to EE2 exposure were not sex-specific. We observed differential expression in male gonad in LMB exposed to EE2 at 1 ng/L of several genes involved in reproductive development and function, including , , (previously ), , and . Expression of , and in males was also responsive to ATR exposure. Overall, our results confirm that early development is a sensitive window for estrogenic endocrine disruption in LMB and are consistent with the hypothesis that ATR exposure induces some estrogenic responses in the developing gonad. However, ATR-specific and EE2-specific responses were also observed.
内分泌干扰污染物一直令人担忧，因为它们可能导致切萨皮克湾流域（CBW）及其他地区的大口黑鲈和小嘴黑鲈出现生殖功能障碍。据推测，接触阿特拉津（ATR）会对脊椎动物内分泌系统产生雌激素效应。CBW某些地区雄性小嘴黑鲈的雌雄同体发生率与水中的ATR浓度相关。在农业地区，鱼类的早期生活阶段可能特别容易受到ATR暴露的影响，因为春季农药流入与产卵和早期发育同时发生。我们的目标是研究早期生活阶段接触ATR或模型雌激素17α-乙炔雌二醇（EE2）对性腺组织性分化和基因表达的影响。我们将刚孵化的大口黑鲈（LMB）在产卵后7至80天暴露于名义浓度为1、10或100μg ATR/L或1或10 ng EE2/L的环境中，并监测性腺组织的组织学发育和转录组变化。我们观察到，暴露于10 ng/L EE2的LMB中，雌性比例接近100%，这可能是由于雄性性逆转所致。许多性腺基因在两性之间存在差异表达。多维标度分析显示，经1 ng EE2/L和100μg ATR/L处理的雄性鱼类的基因表达聚类。一些对EE2暴露有反应的途径并非性别特异性。我们观察到，暴露于1 ng/L EE2的LMB雄性性腺中，几个参与生殖发育和功能的基因存在差异表达，包括 、 、 （以前称为 ）、 、 和 。雄性中 、 和 的表达也对ATR暴露有反应。总体而言，我们的结果证实，早期发育是LMB雌激素内分泌干扰的敏感窗口，并且与ATR暴露在发育中的性腺中诱导一些雌激素反应的假设一致。然而，也观察到了ATR特异性和EE2特异性反应。
