Study of proteins associated to mercury in fishes of the amazon region

Author(s)

Bruna Cavecci Mendonça

• Document type: Doctoral Thesis
• Press: Botucatu. 2017-04-19.
• Institution: Universidade Estadual Paulista (Unesp). Instituto de Biociências. Botucatu
• Defense date: 2017-02-23
• Advisor: Pedro de Magalhães Padilha

Abstract

Fish is an important source of high biological value proteins, vitamins and minerals. However, this food is also one of the main routes of human exposure to toxic contaminants such as methylmercury (MeHg). Thus, their accumulation in the fish may predispose serious risks to human health. The high concentrations of mercury found in soil, sediments, fish and humans in the Brazilian Amazon; have been studied intensively by the scientific community in the last decades, trying to elucidate the mechanisms of mercury toxicity. Mercurial species bind preferentially to proteins. It may mean that the bioavailable fraction of mercury species in different species of fish may be dependent on the way they are bound to these proteins. Therefore, this work proposal sought to optimize 2D-PAGE electrophoretic procedures for fractionation and identification of proteins responsible for the transport of mercury in samples of muscle and liver tissue collected in the reservoir of the Jirau Hydroelectric Power Plant - on the Madeira river; using atomic absorption spectrometry in graphite furnace (GFAAS), for the determination of mercury in the tissues and protein spots obtained; Evaluated the oxidative stress of fish contaminated with mercury through the activities of the enzymes catalase (CAT), glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD), as well as the concentrations of lipid hydroperoxide (HP); and characterized by mercury transport proteins by Mass Spectrometry (ESI-MS/MS) and later by Shotgun involving the combination of Mass Spectrometry and High Performance Liquid Chromatography (ESI-MS/MS + HPLC) Finalizing the work with bioinformatics tools. In this work three species of fish, appreciated in the region and also commercialized, were studied Brachyplatystoma rousseauxii (Dourada), Mylossoma sp., Myleus sp. (Pacu) and Prochilodus nigricans (Curimatã), the muscle and liver tissue of each of these species was used. The results obtained demonstrate a high concentration of mercury in the hepatic tissue of the three fish species studied in an average thirteen times more concentrated than in muscle tissue. After optimization of extractions, precipitations and electrophoretic runs, two mercury-bound proteins were identified: Triosephosphate isomerase A in six protein spots, five of them in the liver of Dourada and one protein spot in the liver of Pacu, and Protein FAM45A in the protein spot of Cutimatã liver. The data generated by the bioinformatics programs confirm the tendency of these proteins to be linked to mercury. (AU)

• FAPESP's process: 14/02638-5 - Study metallothionein associated with mercury in fish of the Amazon Region
• Grantee: Bruna Cavecci Mendonça
• Support Opportunities: Scholarships in Brazil - Doctorate