Biosensor, ELISA, and frog embryo teratogenesis assay: Xenopus (FETAX) analysis of water associated with frog malformations in Minnesota

Between 1995 and 1997 over 62% of the counties in Minnesota reported the presence of malformed frogs. While most sites have recently shown a decline in malformed frog populations, one site in northeastern Minnesota with no prior history of containing malformed frogs was recently discovered to contain > 67% malformed Rana pipiens (northern leopard frogs). As part of an effort to study the presence of hormonally active agents in fresh water sources, water samples were collected from lakes in Minnesota containing malformed frogs and analyzed for the presence of hormonally active compounds using a novel evanescent field fluorometric biosensor and the frog embryo teratogenesis assay: Xenopus (FETAX) bioassay. The waveguide based biosensor developed by ThreeFold Sensors (TFS biosensor, Ann Arbor, MI) detects the presence of estrogenic compounds capable of interacting with free human ER-a and by inhibiting binding to an immobilized estrogen. The FETAX bioassay is a developmental assay, which measures teratogenicity, mortality, and inhibition of growth during the first 96 hours of organogenesis and thereby provides a universal screen for endocrine disruptors. TFS biosensor and FETAX screening of the water samples suggest a relationship between estrogenic activity, mineral supplementation, and the occurrence of malformed frogs.

1995年至1997年间，明尼苏达州超过62%的县报告出现了畸形蛙。虽然大多数地点的畸形蛙数量近期有所下降，但明尼苏达州东北部一个此前没有畸形蛙历史的地点最近被发现有超过67%的北美豹蛙（Rana pipiens）畸形。作为研究淡水源中激素活性物质的一部分工作，从明尼苏达州有畸形蛙的湖泊中采集了水样，并使用一种新型的消逝场荧光生物传感器以及非洲爪蟾胚胎致畸试验（FETAX生物测定）分析了其中是否存在激素活性化合物。由ThreeFold Sensors公司（密歇根州安阿伯市的TFS生物传感器）开发的基于波导的生物传感器能够检测出能够与游离的人雌激素受体α相互作用以及通过抑制与固定化雌激素结合的雌激素类化合物的存在。FETAX生物测定是一种发育测定，它测量器官发生的前96小时内的致畸性、死亡率和生长抑制情况，从而为内分泌干扰物提供了一种通用的筛选方法。对水样进行的TFS生物传感器和FETAX筛选表明，雌激素活性、矿物质补充与畸形蛙的出现之间存在关联。