Unravelling the factors determinig the genotoxic responses to pesticides: the crayfish Procambarus clarkii as a model species

• Autor(a) principal: Costa, Ricardo Jorge da
• Data de Publicação: 2016
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10773/22355
• topic: Lagostins; Pesticidas - Toxicidade

The way organisms may respond and adapt to the presence of contaminants and the subsequent repercussion on the success of the population are still poorly explored issues in the context of environmental toxicology. Knowing that the integrity of the genetic material (DNA) is vital for living beings, it is important to shed a light on eventual genetic adjustment strategies developed by well-succeeded species, in order to cope with, namely, pesticide environmental contamination. Thus, the major goals of the present study were to understand the influence of factors as “Population” and “Gender” in the genotoxic responses of the crayfish Procambarus clarkii, when exposed to a widely used herbicide (Viper®) and also to a model genotoxicant (ethyl methanesulfonate - EMS) in two distinct populations (one collected from a reference site – P1, and the other from an historically impacted site – P2). It was also sought to identify the damage mechanisms involved in eventual positive adjusts and/or vulnerabilities demonstrated by P. clarkii. Moreover, this study contribute to the evaluation of the environmental risk related to the utilization of pesticides and to contribute to the identification of strategies displayed by the crayfish P. clarkii, in particular, to cope with genotoxic damage. Therefore, crayfish specimens from each population (P1 and P2) were then divided into 4 groups, each with 12 individuals (6 males and 6 females; n=6), corresponding to a negative control, a model genotoxicant (5 mg L-1 EMS) and two environmentally relevant concentrations of the herbicide Viper®, 20 μgL-1 (V1) and 40 μgL-1 (V2). The improved version of the comet assay was used to assess the genetic damage, allowing, this way, the detection of oxidative lesions. The results proved the genotoxicity of the herbicide Viper® to the non-target species Procambarus clarkii. The use of a model genotoxicant (EMS) allowed us to observe an acquisition of a non-specific protection/vulnerability in relation to genetic damage. Organisms from the previously exposed population revealed a higher susceptibly towards the non-specific genotoxic pressure posed by Viper®, while in relation to DNA oxidation the same population showed an increased ability to deal with this type of damage. Furthermore, these effects of the exposure history were only evident in males and in relation to the agent Viper®. Overall, and considering the genotoxic evaluation as a whole, the influence of factors as “Population” and “Gender” was demonstrated, highlighting the importance of consider differences on the organisms’ physiological background for ecogenotoxicological-based environmental health assessment, permitting the elaboration of more plausible and holistic approaches.