title: DNA damage in fish (Anguilla anguilla) exposed to a glyphosate-based herbicide -- elucidation of organ-specificity and the role of oxidative stress.
abstract: 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.
authors.affiliation: Department of Biology and CESAM, University of Aveiro, 3810-193 Aveiro, Portugal. sofia.g.guilherme@ua.pt
authors.forename: S
authors.initials: S
authors.lastname: Guilherme
authors.forename: I
authors.initials: I
authors.lastname: Gaivão
authors.forename: M A
authors.initials: MA
authors.lastname: Santos
authors.forename: M
authors.initials: M
authors.lastname: Pacheco
mesh_terms: D000811:Anguilla / Q000235:genetics*; D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D020552:Comet Assay; D004249:DNA Damage; D004305:Dose-Response Relationship, Drug; D005399:Fishes / Q000235:genetics; D005880:Gills / Q000187:drug effects; D005998:Glycine / Q000031:analogs & derivatives* / Q000633:toxicity; D006540:Herbicides / Q000633:toxicity; D008099:Liver / Q000187:drug effects; D009153:Mutagens / Q000633:toxicity*; D009928:Organ Specificity; D018384:Oxidative Stress / Q000502:physiology*; D017382:Reactive Oxygen Species / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000633:toxicity*; D000097797:Glyphosate
chemical_list: D000975:Antioxidants; D005998:Glycine; D006540:Herbicides; D009153:Mutagens; D017382:Reactive Oxygen Species; D014874:Water Pollutants, Chemical; D000097797:Glyphosate