The effects of mercury exposure on Amazonian fishes: An investigation of potential biomarkers

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Souza Vieira, Jose Cavalcante ; Braga, Camila Pereira ; de Queiroz, Joao Vitor ; Cavecci-Mendonca, Bruna ; de Oliveira, Grasieli ; de Freitas, Natalia Galvao ; Henrique Fernandes, Ana Angelica ; Fernandes, Mileni da Silva ; Buzalaf, Marilia Afonso Rabelo ; Adamec, Jiri ; Zara, Luiz Fabricio ; Padilha, Pedro de Magalhaes

• Document type: Journal article
• Source: Chemosphere; v. 316, p. 13-pg., 2023-01-13.

Abstract

Exposure to mercury can interfere with the expression of proteins and enzymes, compromise important path-ways, such as apoptosis and glucose metabolism, and even induce the expression of metallothioneins. In this study, analytical techniques were used to determine the concentration of total mercury (THg) in muscle and liver tissue, protein pellets, and spots [using graphite furnace atomic absorption spectrometry (GFAAS)], and mo-lecular techniques were used to identify metalloproteins present in mercury-associated protein spots. Thirty individuals from three different fish species, Cichla sp. (n = 10), Brachyplatystoma filamentosum (n = 10), and Semaprochilodus sp. (n = 10) from the Brazilian Amazon were used. Oxidative stress indicators [such as gluta-thione peroxidase (GSH-Px), catalase (CAT), superoxide dismutase (SOD), a marker of lipid peroxidation (LPO)] and the possible expression of metallothioneins in muscle and liver tissues were investigated. The two piscivo-rous species, Cichla sp. and B. filamentosum, presented the highest concentrations of mercury in their hepatic tissue, 1219 +/- 15.00 and 1044 +/- 13.6 mu g kg -1, respectively, and in their muscle tissue, 101 +/- 1.30 mu g kg- 1 and 87.4 +/- 0.900 mu g kg -1, respectively. The non-carnivorous species Semaprochilodus sp. had comparatively low concentrations of mercury in both its hepatic (852 +/- 11.1 mu g kg -1) and muscle (71.4 +/- 0.930 mu g kg-1) tissues. The presence of mercury was identified in 24 protein spots using GFAAS; concentrations ranged from 11.5 to 787 mu g kg -1, and mass spectrometry identified 21 metal-binding proteins. The activities of GSH-Px, CAT, and SOD, related to oxidative stress, decreased proportionally as tissue Hg concentrations increased, while the levels of LPO markers increased, indicating the presence of stress. Our study results demonstrate possible mercury interference in oxidative stress markers (GSH-Px, CAT, SOD, and LPO), in addition to the identification of 21 metal-binding proteins as possible biomarkers of mercury exposure in fish. (AU)

• FAPESP's process: 16/19404-2 - Mercury toxicity biomarker characterization in fish from Basin of the Madeira River-Rondônia using metalloproteomic strategies
• Grantee: Pedro de Magalhães Padilha
• Support Opportunities: Regular Research Grants
• FAPESP's process: 19/02538-4 - Effect of mercury exposure frequency in riverside populations from the Amazon region: identification of possible biomarkers
• Grantee: Pedro de Magalhães Padilha
• Support Opportunities: Regular Research Grants
• FAPESP's process: 14/02668-1 - Utilization of metalloproteomic strategies for metallothionein evaluation in liver tissue samples of fishes collected in the reservoir of Ahe Jirau - Madeira River Basin, RO, Brazil
• Grantee: José Cavalcante Souza Vieira
• Support Opportunities: Scholarships in Brazil - Doctorate