Toxic and recovery effects of copper on Caenorhabditis elegans by various food-borne and water-borne pathways

Copper pollutions are typical heavy metal contaminations, and their ability to move up food chains urges comprehensive studies on their effects through various pathways. Currently, four exposure pathways were prescribed as food-borne (FB), water-borne plus clean food (WCB), water-food-borne (WFB) and water-borne (WB). Caenorhabditis elegans was chosen as the model organism, and growth statuses, feeding abilities, the amounts of four antioxidant enzymes, and corresponding recovery effects under non-toxic conditions with food and without food were investigated. Based on analysis results, copper concentrations in exposure were significantly influenced by the presence of food and its uptake by C elegans. Both exposure and recovery effects depended on exposure concentrations and food conditions. For exposure pathways with food, feeding abilities and growth statuses were generally WFB < WCB <= FB (p < 0.05). The antioxidant activities were up-regulated in the same order. Meanwhile, the exposure pathway without food (WB) caused non-up-regulated antioxidant activities, and had the best growth statuses. For recoveries with food, growth statuses, feeding abilities and the inductions of the antioxidant enzymes were all WB approximate to WFB < WCB < FB (p < 0.05). For recoveries without food, the order of growth statuses remained WB > FB > WCB > WFB (p < 0.05), while the antioxidant activities were all inhibited in a concentration-dependent fashion. In conclusion, contaminated food was the primary exposure pathway, and various pathways caused different responses of C. elegans. (C) 2012 Elsevier Ltd. All rights reserved.