Efeitos toxicológicos de nanopartículas de maghemita (γ-Fe2O3) em células e tecidos de Poecilia reticulata

• Autor(a) principal: Qualhato, Gabriel
• Data de Publicação: 2018
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFG
• Texto Completo: http://repositorio.bc.ufg.br/tede/handle/tede/8613
• topic: Nanopartículas; Biomarcadores; Ensaio cometa; Guppy; Melanomacrófagos; Nanoparticles; Biomarkes; Comet assay; Guppy; Melanomacrophages; CIENCIAS BIOLOGICAS::BIOLOGIA GERAL

The environmental risk of nanomaterials (NMs) designed and used in nanoremediation process is of emerging concern, but their ecotoxilogical effects to aquatic organism remains unclear. In this present study, the citrate-coated (maghemite) nanoparticles (IONPs) were synthesized and its genotoxic, mutagenic, the melanomacrophage centers (MMC) response and hepatic histopathological biomarkers were investigated in female guppy. Fish were exposed to IONPs at environmentally relevant iron concentration (0.3 mg L-1) during 21 days and the animals were collected at the beginning of the experiment and after 3, 7, 14 and 21 days of exposure. The genotoxicity and mutagenicity were evaluated in terms of DNA damage (comet assay), micronucleus (MN) test, erythrocyte nuclear abnormalities (ENA) frequency and the liver were dissected and fixed dehydrated through increasing ethanol gradient, immersed in xylene PA, embedded in paraffin, performed of liver sections (5 μm thick) (3 sections per animal) in the microtome, stained by Mallory’s Trichrome and H. E. and analyzed. Results showed differential genotoxic and mutagenic effects of IONPs in the P. reticulata according to exposure time. The IONP induced DNA damage in P. reticulata after acute (3 and 7 days) and long-term exposure (14 and 21 days), while the mutagenic effects were observed only after long-term exposure. The DNA damage and the total ENA frequency increase linearly over the exposure time, indicating a higher induction rate of clastogenic and aneugenic effects in P. reticulata erythrocytes after long-term exposure to IONPs. Guppies exposed to IONPs showed increasing in the number, area and perimeter of MMC when compared to the unexposed ones, especially after 7 days of exposure. The results showed an increase in the frequency of histopathological changes in fish after the 7 days of exposure to IONPs, such micro- and macro-vesicular steatosis, melanomacrophage aggregates, exudate and haemorrhagic foci. The acute (3 and 7 days) and long-term (14 and 21 days) exposure of P. reticulata to IONPs induced high histopathological indexes associated with circulatory disorders and inflammatory responses. Results indicated that blood system and liver tissue of P. reticulata are excellent target organs to studies the ecotoxicity of IONPs. Confirming that P. reticulata is a biomonitor specie indicated for studies of ecotoxicity of IONPs.