Kadlec Sarah M, Johnson Rodney D, Mount David R, Olker Jennifer H, Borkholder Brian D, Schoff Patrick K
Integrated Biosciences Graduate Program, University of Minnesota-Duluth, Minnesota, USA.
Office of Research and Development, Mid-Continent Ecology Division, US Environmental Protection Agency, Duluth, Minnesota, USA.
Environ Toxicol Chem. 2017 Dec;36(12):3424-3435. doi: 10.1002/etc.3928. Epub 2017 Sep 8.
Testicular oocytes (TOs) have been found in black bass (Micropterus spp.) from many locations in North America. The presence of TOs is often assumed to imply exposure to estrogenic endocrine disrupting compounds (EDCs); however, a definitive causal relationship has yet to be established, and TO prevalence is not consistently low in fish from areas lacking evident EDC sources. This might indicate any of a number of situations: 1) unknown or unidentified EDCs or EDC sources, 2) induction of TOs by other stressors, or 3) testicular oocytes occurring spontaneously during normal development. In the present study, we analyzed TO occurrence in smallmouth bass (Micropterus dolomieu) from 8 populations in northeastern Minnesota watersheds with differing degrees of human development and, hence, presumed likelihood of exposure to anthropogenic chemicals. Three watersheds were categorized as moderately developed, based on the presence of municipal wastewater discharges and higher human population density (4-81 per km ), and 5 watersheds were minimally developed, with very low human population density (0-1 per km ) and minimal built environment. Testicular tissues from mature fish were evaluated using a semiquantitative method that estimated TO density, normalized by cross-sectional area. Testicular oocyte prevalence and density among populations from moderately developed watersheds was higher than in populations from minimally developed watersheds. However, TO prevalence was unexpectedly high and variable (7-43%) in some populations from minimally developed watersheds, and only weak evidence was found for a relationship between TO density and watershed development, suggesting alternative or more complex explanations for TO presence in smallmouth bass from this region. Environ Toxicol Chem 2017;36:3424-3435. © 2017 SETAC.
在北美许多地方的黑鲈（小口黑鲈属）中都发现了睾丸卵母细胞（TOs）。通常认为TOs的存在意味着接触了雌激素类内分泌干扰化合物（EDCs）；然而，尚未确定明确的因果关系，而且在缺乏明显EDC来源地区的鱼类中，TOs的患病率并非一直很低。这可能表明存在多种情况：1）未知或未识别的EDCs或EDC来源；2）其他应激源诱导产生TOs；3）在正常发育过程中自发出现睾丸卵母细胞。在本研究中，我们分析了明尼苏达州东北部流域8个种群的小口黑鲈（Micropterus dolomieu）中TOs的出现情况，这些流域的人类发展程度不同，因此假定接触人为化学物质的可能性也不同。根据市政废水排放情况和较高的人口密度（每平方公里4 - 81人），将3个流域归类为中度开发地区，5个流域为低度开发地区，人口密度非常低（每平方公里0 - 1人）且建筑环境最少。使用一种半定量方法评估成熟鱼类的睾丸组织，该方法通过横截面积对TO密度进行标准化估计。中度开发流域种群的睾丸卵母细胞患病率和密度高于低度开发流域的种群。然而，在一些低度开发流域的种群中，TOs的患病率意外地高且变化较大（7% - 43%），并且仅发现了TO密度与流域开发之间的微弱关系证据，这表明该地区小口黑鲈中TOs存在的原因可能另有他因或更为复杂。《环境毒理学与化学》2017年；36：3424 - 3435。© 2017 SETAC。
