Laboratoire de Génétique et Evolution des Populations Végétales, UMR CNRS 8016, Université des Sciences et Technologies de Lille-Lille 1, F-59655 Villeneuve d'Ascq Cedex, France.
Aquat Toxicol. 2010 May 10;97(4):334-42. doi: 10.1016/j.aquatox.2010.01.004. Epub 2010 Jan 13.
This study tested if a variation in light intensity, in comparison to constant light required in well-designed toxicity test, could have measurable consequences on the sensitivity of phototrophic biofilms (periphyton) to isoproturon. Two independent experiments were carried out to investigate the combined effects of light and isoproturon on the photochemical behavior of intact natural biofilms by measurements of chlorophyll fluorescence and pigment composition. Experiment 1 consisted of exposing biofilms to series of isoproturon concentrations (0-2 mg L(-1)) for 7 h under constant light at different irradiance levels (25-300 micromol m(-2) s(-1)). In experiment 2, biofilms were exposed using more environmentally realistic conditions to three selected concentrations of isoproturon (2, 6 and 20 microg L(-1)) during a 7-h-simulated daily light cycle. Our results demonstrated that light, considered here as a direct physical stressor, slightly modulated the acute toxicity of isoproturon on these diatom dominated communities. This was attributed to the fact that these two factors act specifically on the photosynthetic activity. Furthermore, it was shown that a dynamic light regime increased periphyton sensitivity to isoproturon by challenging its photoprotective mechanisms such as the xanthophyll cycle, therefore implying that traditional ecotoxicological bioassays lead to underestimate the effect of isoproturon.
本研究测试了在设计良好的毒性测试中，与恒定光照相比，光照强度的变化是否会对光养生物膜（周丛生物）对异噁草酮的敏感性产生可测量的影响。进行了两项独立的实验，通过测量叶绿素荧光和色素组成来研究光照和异噁草酮对完整自然生物膜光化学行为的联合影响。实验 1 包括在不同辐照度水平（25-300 μmol m(-2) s(-1)）下，将生物膜暴露于恒定光照下的异噁草酮浓度系列（0-2 mg L(-1)) 7 小时。在实验 2 中，生物膜在更接近实际环境的条件下暴露于三种选定浓度的异噁草酮（2、6 和 20 μg L(-1))，在 7 小时模拟的日常光照周期中。我们的结果表明，在这里被视为直接物理胁迫的光略微调节了异噁草酮对这些以硅藻为主的群落的急性毒性。这归因于这两个因素专门作用于光合作用这一事实。此外，研究表明动态光照条件通过挑战其光保护机制（如叶黄素循环）增加了周丛生物对异噁草酮的敏感性，因此意味着传统的生态毒理学生物测定会低估异噁草酮的影响。
