Toxicity evaluation of Wanzhou watershed of Yangtze Three Gorges Reservoir in the flood season in Caenorhabditis elegans

Abstract

Three Gorges Reservoir (TGR) in the upper stream of Yangtze River in China is a reservoir with the largest and the longest yearly water-level drop. Considering the fact that most of safety assessments of water samples collected from TGR region were based on chemical analysis, we here employed Caenorhabditis elegans to perform in vivo safety assessment of original surface water samples collected from TGR region in the flood season in Wanzhou, Chongqing. Among the examined five original surface water samples, only exposure to original surface water sample collected from backwater area could induce the significant intestinal ROS production, enhance the intestinal permeability, and decrease the locomotion behavior. Additionally, exposure to original surface water sample collected from backwater area altered the expressions of sod-2, sod-5, clk-1, and mev-1. Moreover, mutation of sod-2 or sod-5 was susceptible to the potential toxicity of original surface water sample collected from backwater area on nematodes. Together, our results imply that exposure to surface water sample from the backwater area may at least cause the adverse effects on intestinal function and locomotion behavior in nematodes.

Biosafety assessment of water samples from Wanzhou watershed of Yangtze Three Gorges Reservoir in the quiet season in Caenorhabditis elegans

“…This observation is very different from the effects of surface water samples in the TGR region in the flood season on wild-type nematodes. In wild-type nematodes, it has been shown that acute exposure to the surface water sample collected from the backwater area (W5) in the flood season could cause the significant decrease in locomotion behavior and induction of intestinal ROS production, although exposure to other four surface water samples in the flood season could not cause obvious toxicity 32 . These observations imply that, at least for the site of backwater area, the noticeable difference for the potential effect between surface water in the flood season and surface water in the quiet season may exist on environmental organisms.…”

“…The surface water samples were from 5 sampling sites (W1, shore water; W2, upstream; W3, shore water; W4, downstream; and W5, backwater area) in Wanzhou, Chongqing (Fig. 6), which are the same as those analyzed in our previous study 32 . The sampling season was selected in the quiet season (December 15, 2017).…”

“…Water temperature, pH value, total dissolved solids, and turbidity were analyzed as described by Xiao et al . 32 . Information for daily flow and water level of the sampling sites was from Yangtze River Hydrological Network (http://www.cjh.com.cn).…”

“…Moreover, due to the property of model animal, C. elegans is helpful for elucidating the underlying cellular and molecular mechanisms for the observed toxicity of environmental toxicants 29–31 . Recently, the safety assessment of original surface water samples collected from TGR region in the flood season in Wanzhou, Chongqing has been performed using C. elegans as an assay animal model 32 . It has been shown that, after acute exposure, the original surface water sample collected from backwater area in the flood season could induce the obvious toxicity on wild-type nematodes 32 .…”

“…Recently, the safety assessment of original surface water samples collected from TGR region in the flood season in Wanzhou, Chongqing has been performed using C. elegans as an assay animal model 32 . It has been shown that, after acute exposure, the original surface water sample collected from backwater area in the flood season could induce the obvious toxicity on wild-type nematodes 32 .…”