University of Notre Dame, Department of Biological Sciences, Environmental Change Initiative, Notre Dame, Indiana, United States of America.
Cary Institute of Ecosystem Studies, Millbrook, NY, United States of America.
PLoS One. 2019 May 16;14(5):e0216481. doi: 10.1371/journal.pone.0216481. eCollection 2019.
The majority of maize planted in the US is genetically-engineered to express insecticidal properties, including Cry1Ab protein, which is designed to resist the European maize borer (Ostrinia nubilalis). After crop harvest, these proteins can be leached into adjacent streams from crop detritus left on fields. The environmental fate of Cry1Ab proteins in aquatic habitats is not well known. From June-November, we performed monthly short-term additions of leached Cry1Ab into four experimental streams with varying benthic substrate to estimate Cry1Ab transport and removal. At the start of the experiments, when rocks were bare, we found no evidence of Cry1Ab removal from the water column, but uptake steadily increased as biofilm colonized the stream substrate. Overall, Cry1Ab uptake was strongly predicted by measures of biofilm accumulation, including algal chlorophyll a and percent cover of filamentous algae. Average Cry1Ab uptake velocity (vf = 0.059 ± 0.009 mm s-1) was comparable to previously reported uptake of labile dissolved organic carbon (DOC; mean vf = 0.04 ± 0.008 mm s-1). Although Cry1Ab has been shown to rapidly degrade in stream water, benthic biofilms may decrease the distance proteins are transported in lotic systems. These results emphasize that once the Cry1Ab protein is leached, subsequent detection and transport through agricultural waterways is dependent on the structure and biology of receiving stream ecosystems.
美国种植的大部分玉米都是经过基因工程改造的，以表达杀虫特性，包括 Cry1Ab 蛋白，该蛋白旨在抵抗欧洲玉米螟（Ostrinia nubilalis）。作物收获后，这些蛋白质可以从留在田间的作物碎屑中浸出到相邻的溪流中。Cry1Ab 蛋白在水生栖息地中的环境归宿尚不清楚。6 月至 11 月，我们每月在四个具有不同底质的实验溪流中进行短期添加浸出的 Cry1Ab，以估计 Cry1Ab 的迁移和去除。在实验开始时，当岩石裸露时，我们没有发现 Cry1Ab 从水柱中去除的证据，但随着生物膜在溪流基质上定殖，摄取量稳步增加。总的来说，Cry1Ab 的摄取量与生物膜积累的测量值密切相关，包括藻类叶绿素 a 和丝状藻类的覆盖率。Cry1Ab 的平均摄取速度（vf = 0.059 ± 0.009 mm s-1）与先前报道的易溶性溶解有机碳（DOC；平均 vf = 0.04 ± 0.008 mm s-1）的摄取速度相当。尽管已经证明 Cry1Ab 在溪流水中迅速降解，但底栖生物膜可能会减少蛋白质在流水系统中迁移的距离。这些结果强调，一旦 Cry1Ab 蛋白被浸出，随后通过农业水道的检测和迁移取决于接收溪流生态系统的结构和生物学。
