College of Science and Technology, Ningbo University, Ningbo, 315211, China.
College of Environmental Science and Engineering, Donghua University, Shanghai, 201620, China.
Aquat Toxicol. 2019 Jan;206:54-60. doi: 10.1016/j.aquatox.2018.11.003. Epub 2018 Nov 6.
The enantioselective toxic mechanisms of chiral herbicides in photosynthetic organisms are closely related to the production of reactive oxygen species (ROS) production, however, there are few reports on how the enantioselective production of ROS can be triggered. In suboptimal conditions, photosynthesis is one of the most important processes in the production of ROS, especially in the process of light utilization and electron transfer. In this study, we investigated the interactions between chiral herbicide dichlorprop (DCPP) enantiomers and the chiral macroaggregates of the photosynthetic light-harvesting chlorophyll a/b pigment-protein complexes (LHCII) in Scenedesmus obliquus, which is of great significance in capturing and utilizing sun light, and also in dissipating the excess excitation energy. The results of the circular dichroism indicated that DCPP induced the structural changes of the LHCII chiral macroaggregates in an enantioselective manner and that the (R)-DCPP treated-group showed a bigger change accompanied by a changed enantioselective dissipation of the excitation energy. The excitation energy was excessed in DCPP treated-groups and the degree of excess was enantioselective and the detrimental non-chemical energy triggered the enantioselective production of ROS, that induced the enantioselective toxicity to green algae S. obliquus. Overall, this study has identified that how the enantioselective production of ROS can be triggered in chloroplasts; this can help to reveal the enantioselective mechanisms of chiral herbicides to photosynthetic organisms.
手性除草剂在光合生物中的对映体选择性毒性机制与活性氧（ROS）的产生密切相关，但关于对映体选择性 ROS 产生如何被触发的报道很少。在非最佳条件下，光合作用是 ROS 产生的最重要过程之一，尤其是在光利用和电子传递过程中。在这项研究中，我们研究了手性除草剂 2,4-二氯苯氧丙酸（DCPP）对映体与斜生栅藻（Scenedesmus obliquus）中光合色素蛋白复合物（LHCII）手性聚集体之间的相互作用，该藻在捕获和利用太阳光以及耗散过量激发能方面具有重要意义。圆二色性的结果表明，DCPP 以对映体选择性的方式诱导 LHCII 手性聚集体的结构发生变化，（R）-DCPP 处理组表现出更大的变化，并伴随着激发能的对映体选择性耗散的变化。在 DCPP 处理组中，激发能过剩，过剩程度具有对映体选择性，有害的非化学能量触发了 ROS 的对映体选择性产生，从而导致绿藻斜生栅藻的对映体选择性毒性。总的来说，这项研究确定了 ROS 的对映体选择性产生如何在叶绿体中被触发；这有助于揭示手性除草剂对光合生物的对映体选择性机制。
