| Summary: | Mestrado em Biologia Aplicada The presence of pesticides in water bodies is a worrying environmental issue, occurring mainly due to spray-drift, surface runoff or inadvertent applications. This vast class of agrochemicals is known to induce several pernicious effects in non-target aquatic organisms, namely fish. However, data concerning the genotoxic impact of these compounds are scarce. Hence, the present thesis aimed to fill the knowledge lacuna on pesticides capacity to induce genotoxicity to fish, addressing two commercial formulations: Decis®, a deltamethrin-based insecticide, and Roundup®, a glyphosate-based herbicide, each representing a widely used class of biocides. The present work aimed to assess: (i) the chromosomal damaging potential of Decis®, (ii) the DNA damage induction by Roundup®, (iii) the involvement of oxidative processes on the DNA integrity loss as well as (iv) the involvement of DNA repair system in the progression of the DNA damage induced by Roundup®. European eel (Anguilla anguilla L.) was adopted as test organism, performing short-term exposures of 3 days to environmentally realistic concentrations of Decis® and Roundup® and post-exposure evaluations of 1, 7 and 14 days to assess the damage evolution in pesticide-free water. In order to assess the genotoxic damage induced by Decis®, the erythrocytic nuclear abnormalities (ENA) assay was performed, evaluating chromosomal damage, a hardly repairable type of lesion. In what concerns to Roundup® experiment, the comet assay was adopted as genotoxic endpoint, measuring DNA damage as strand breaks, able to be repaired. In order to assess the involvement of oxidative damage in Roundup®-induced genotoxicity, the comet assay was performed with an extra step, where nucleoids were digested with the endonucleases formamidopyrimidine DNA glycosylase (FPG) and endonuclease III (EndoIII), measuring oxidized purines and pyrimidines, respectively. The base excision repair (BER) assay was adopted to evaluate the oxidative DNA damage repair ability of ...
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