Efeitos genotóxicos, mutagênicos e comportamentais de nanopartículas de dióxido de titânio em girinos de Dendropsophus minutus (Hylidae, Anura)

• Autor(a) principal: Amaral, Diogo Ferreira do
• Data de Publicação: 2021
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da UFG
• dARK ID: ark:/38995/001300000b886
• Texto Completo: http://repositorio.bc.ufg.br/tede/handle/tede/11774
• topic: Anuros; Nanopartículas; Titânio; Ensaio cometa; Biomarcadores; Comportamento; Bibliometria; Frogs; Nanoparticles; Titanium; Comet assay; Biomarkers; Behavior; Bibliometrics; CIENCIAS BIOLOGICAS

Nanomaterials (NMs) have been used in an increasing number of commercial products, and its rapid expansion could lead to their release into aquatic environments. The accelerated production of the various types of conventional products at nanoscale has been fundamental for the economic progress of several countries. Many types of nanoparticles and nanomaterials are already being used, and other varieties are expected to appear in the future. However, there is little knowledge about the impact of NMs on biota, especially on amphibians. Therefore, there is a need to better classify and understand NMs. The first part of our study has reviewed the historical use of amphibian species as model systems in nanoecotoxicological studies, which summarized data available in the scientific literature on the genotoxic, mutagenic, histopathological, embryotoxic, and reproductive effects of NMs in different groups of amphibians. The interaction, bioaccumulation, mode of action (MoA), and ecotoxicity of NMs in amphibians were also reviewed. The nanoecotoxicological studies were carried out with 12 species of amphibians, eight from the Anura order and three from the Caudata order. Xenopus laevis was the most studied species. Studies were conducted primarily with inorganic NMs (72%) compared to organic ones. Nanoecotoxicity depends on the behavior of the NM, the transformation in the environment, and the developmental stages of the amphibians. The MoA of NMs in amphibians was mainly associated with the production of reactive oxygen species (ROS), oxidative stress, genotoxic and mutagenic effects. The results emphasized the need for more studies that test the ecotoxicity of different NMs, concentrations, and exposure periods in environmentally relevant approaches. In addition, there is a need for standard protocols for nanoecotoxicological testing with amphibians. The reviewed data showed that amphibians are suitable organisms to assess the environmental impact of NMs and indicated essential gaps in research on the ecotoxicity of NMs in freshwater ecosystems, as well as recommendations for future research. In this sense, we observed from the first chapter that the most produced and consumed nanoparticles worldwide are titanium dioxide nanoparticles (TiO2 NPs); whose release into the environment are known to induce toxic effects in aquatic invertebrates and vertebrates. However, knowledge of its impact on neotropical amphibians remains limited. Thus, the second chapter of this thesis aimed to evaluate the toxicity of TiO2 NPs and its dissolved counterpart, titanium dioxide (TiO2), in a species of anuran neotropical amphibian (Dendropsophus minutus). DNA damage, biometric parameters, and behavioral changes were analyzed in tadpoles after exposure to three environmentally relevant concentrations (0.1, 1.0, and 10 mg L-1) of TiO2 and TiO2 NPs for 7 days. As a result, we verified DNA damage in D. minutus tadpoles exposed to both forms of Ti compared to the control group. We also identified a similar reduction in overall size, body length, width, and height of the tail musculature in tadpoles exposed to TiO2 and TiO2 NPs compared to unexposed tadpoles. Regarding the behavioral test, the tadpoles showed less mobility and were more distant from the conspecifics (less aggregated) when exposed to NPs. Therefore, the simultaneous use of multiple biomarkers was essential to assess the adverse effects of the nanomaterial and establish a reliable approach for biomonitoring of aquatic ecosystems. Our study increases the knowledge about the genotoxic, morphological, and behavioral effects of TiO2 and TiO2 NPs in anuran amphibians, contributing to future studies in the environmental risk assessment of nanomaterials.