Department of Earth and Environmental Sciences (DISAT), University of Milano-Bicocca, Piazza della Scienza 1, 20126 Milano, Italy.
Department of Environmental Science and Policy, University of Milan, Via Celoria 2, I-20133 Milano, Italy.
Environ Pollut. 2018 Apr;235:411-418. doi: 10.1016/j.envpol.2017.12.113. Epub 2018 Jan 5.
The main objective of the present study was to investigate possible links between sub-individual and supra-individual levels (i.e. population level) biomarkers in D. magna exposed to sublethal concentrations of the insecticide chlorpyrifos (CPF). To achieve the aim, 8-day old individuals were exposed for 96 h to two environmentally relevant concentrations of CPF (50 and 250 ng/L). Sub-individual level effects were investigated by measuring the activity of antioxidant (SOD, CAT, and GPx) and detoxifying (GST) enzymes, as well as by measuring the acetylcholinesterase (AChE) inhibition. In addition, the effects at supra-individual level were assessed by using a video-tracking system and analyzing changes in swimming capabilities (i.e. percentage of activity time, distance moved, and velocity). Our data have shown that daphnids exposed to both CPF concentrations were in a condition of stress which was highlighted by changes in both sub- and supra-individual biomarkers. Moreover, our results highlighted that the lowest tested CPF concentration did not modulate the antioxidant and detoxifying enzymes, whereas, an inhibition of AChE and a decrease of some parameters related to swimming behaviour (distance moved and velocity) were noted. On the contrary, significant changes in all the sub-individual biomarkers were measured at the highest tested concentration. In addition, organisms recovered the movement capability (distance moved) and also activate a mechanism of avoidance (increased swimming velocity). On the other hand, a reduction in the percent of active time was measured and this was attributed to the energy spent by organisms to activate antioxidant and detoxifying enzymes and the mechanism of avoidance. Based on these results, our study suggests the existence of a link between sub- and supra-individual levels, as the activation or non-activation in the antioxidant and detoxifying enzymes activities can led to different modifications of the swimming behaviour in D. magna.
本研究的主要目的是调查在接触到拟除虫菊酯氯氰菊酯（CPF）亚致死浓度的大型溞（D. magna）个体和种群水平生物标志物之间可能存在的联系。为了实现这一目标，将 8 天大的个体暴露于两种环境相关浓度的 CPF（50 和 250ng/L）中 96 小时。通过测量抗氧化（SOD、CAT 和 GPx）和解毒（GST）酶的活性，以及乙酰胆碱酯酶（AChE）抑制率来研究个体水平的影响。此外，通过使用视频跟踪系统评估个体以上水平的影响，并分析游泳能力的变化（即活动时间百分比、移动距离和速度）。我们的数据表明，暴露于两种 CPF 浓度下的大型溞处于应激状态，这种应激状态突出表现在个体生物标志物和种群生物标志物的变化上。此外，我们的结果表明，测试的最低 CPF 浓度没有调节抗氧化和解毒酶，而 AChE 的抑制和一些与游泳行为相关的参数（移动距离和速度）的降低则是明显的。相反，在最高测试浓度下，所有个体生物标志物都发生了显著变化。此外，生物体恢复了移动能力（移动距离），并激活了回避机制（增加游泳速度）。另一方面，测量到活跃时间的百分比降低，这归因于生物体激活抗氧化和解毒酶以及回避机制所消耗的能量。基于这些结果，我们的研究表明个体和种群水平之间存在联系，因为抗氧化和解毒酶活性的激活或不激活可能导致大型溞游泳行为的不同变化。
