Department of Biology and CESAM, University of Aveiro, 3810-193 Aveiro, Portugal.
Mutat Res. 2012 Mar 18;743(1-2):1-9. doi: 10.1016/j.mrgentox.2011.10.017. Epub 2012 Jan 14.
Organophosphate herbicides are among the most dangerous agrochemicals for the aquatic environment. In this context, Roundup(®), a glyphosate-based herbicide, has been widely detected in natural water bodies, representing a potential threat to non-target organisms, namely fish. Thus, the main goal of the present study was to evaluate the genotoxic potential of Roundup(®) in the teleost fish Anguilla anguilla, addressing the possible causative involvement of oxidative stress. Fish were exposed to environmentally realistic concentrations of this herbicide (58 and 116 μgL(-1)) during one or three days. The standard procedure of the comet assay was applied to gill and liver cells in order to determine organ-specific genetic damage. Since liver is a central organ in xenobiotic metabolism, nucleoids of hepatic cells were also incubated with a lesion-specific repair enzyme (formamidopyrimidine DNA glycosylase - FPG), in order to recognise oxidised purines. Antioxidants were determined in both organs as indicators of pro-oxidant state. In general, both organs displayed an increase in DNA damage for the two Roundup(®) concentrations and exposure times, although liver showed to be less susceptible to the lower concentration. The enzyme-modified comet assay showed the occurrence of FPG-sensitive sites in liver only after a 3-day exposure to the higher Roundup(®) concentration. The antioxidant defences were in general unresponsive, despite a single increment of catalase activity in gills (116 μgL(-1), 3-day) and a decrease of superoxide dismutase activity in liver (58 μgL(-1), 3-day). Overall, the mechanisms involved in Roundup(®)-induced DNA strand-breaks showed to be similar in both organs. Nevertheless, it was demonstrated that the type of DNA damage varies with the concentration and exposure duration. Hence, after 1-day exposure, an increase on pro-oxidant state is not a necessary condition for the induction of DNA-damaging effects of Roundup(®). By increasing the duration of exposure to three days, ROS-dependent processes gained preponderance as a mechanism of DNA-damage induction in the higher concentration.
有机磷除草剂是对水生环境最危险的农用化学品之一。在这种情况下，草甘膦基除草剂“Roundup(®)”已在天然水体中广泛检出，对非目标生物（即鱼类）构成潜在威胁。因此，本研究的主要目的是评估“Roundup(®)”对硬骨鱼鳗鲡的遗传毒性潜力，探讨氧化应激可能的因果关系。鱼类在环境现实浓度（58 和 116 μgL(-1)) 下暴露于该除草剂 1 或 3 天。彗星试验的标准程序应用于鳃和肝细胞，以确定器官特异性遗传损伤。由于肝脏是外源化学物代谢的中心器官，还孵育了肝细胞核与损伤特异性修复酶（甲酸嘧啶 DNA 糖基化酶 - FPG），以识别氧化嘌呤。两种器官中的抗氧化剂均作为促氧化剂状态的指标进行测定。一般来说，两种器官在两种“Roundup(®)”浓度和暴露时间下均显示 DNA 损伤增加，尽管肝脏对较低浓度的药物更敏感。在仅 3 天暴露于较高浓度“Roundup(®)”后，酶修饰的彗星试验仅显示肝脏中出现 FPG 敏感部位。抗氧化防御总体上无反应，尽管鳃中过氧化氢酶活性增加（116 μgL(-1)，3 天），肝脏中超氧化物歧化酶活性降低（58 μgL(-1)，3 天）。总的来说，“Roundup(®)”诱导 DNA 链断裂所涉及的机制在两种器官中相似。然而，已经证明，DNA 损伤的类型随浓度和暴露时间而变化。因此，在 1 天暴露后，促氧化剂状态的增加不是“Roundup(®)”诱导 DNA 损伤效应的必要条件。通过将暴露时间延长至 3 天，ROS 依赖性过程作为在较高浓度下诱导 DNA 损伤的机制占据了优势。
