Identification of Biomarkers of Mercury Contamination in Brachyplatystoma filamentosum of the Madeira River, Brazil, Using Metalloproteomic Strategies

Abstract

Predator fish can accumulate high levels of mercury, which qualifies them as potential indicators of this toxic metal. The predatory species Brachyplatystoma filamentosum, popularly known as filhote, is among the most consumed species in the Brazilian Amazon. Continuing the metalloproteomic studies of mercury in Amazonian fishes that have been developed in the last 5 years, the present paper provides the data of protein characterization associated with mercury in muscle and liver samples of filhote (Brachyplatystoma filamentosum) collected in the Madeira River, Brazilian Amazon. The mercury concentration in the muscle and liver samples was determined by graphite furnace atomic absorption spectrometry (GFAAS). The protein fraction was extracted in an aqueous medium, and later, a fractional precipitation procedure was performed to obtain the protein pellets. Then, the proteome of the tissue samples of this fish species was separated by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE), and a mercury mapping of the protein spots was carried out by GFAAS after acid digestion. Protein spots that had mercury were characterized by mass spectrometry with electrospray ionization in sequence (ESI-MS/MS) after tryptic digestion. It was possible to characterize 11 mercury-associated protein spots that presented biomarker characteristics and could be used to monitor mercury in fish species of the Amazon region. Thus, the metalloproteomic strategies used in the present study allowed us to characterize 11 mercury-associated protein spots. It should be noted that the protein spots identified as GFRP, TMEM186, TMEM57B, and BHMT, which have coordination sites for elements with characteristics of soft acids, such as mercury, can be used as biomarkers of mercury contamination in monitoring studies of this toxic metal in fish species from the Amazon region.

Trace element accumulation in different edible fish species from the Bolivian Amazon and the risk for human consumption

“…Nevertheless, literature has suggested that depending on the species, methyl-mercury can constitute an important percentage of total mercury in fish tissues, especially when muscle tissue is analyzed, constituting 80–100 % of total mercury in some cases ( Lino et al., 2019 ). Among different fish tissues tested in literature, muscle contained the highest ratio of methyl-mercury/total mercury in most fish species ( Bloom 1992 ; Peng et al., 2016 ; Yoon et al., 2018 ; de Queiroz et al., 2019 ), since muscle is a major tissue for high metal storage, being methyl-mercury an important one due to its negligible elimination ( Peng et al., 2016 ).…”

Multifaceted functions of RPS27a: An unconventional ribosomal protein

“…), a species of Amazonian fish, researchers found approximately two atoms of Hg per RPS27a molecule in hepatic tissue (J. C. S. Vieira et al, 2018). Moreover, in the hepatic and muscular tissue of filhote ( Brachyplatystoma filamentosum ), a giant catfish in the Amazonian rivers, Hg can also bind to RPS27a (de Queiroz et al, 2019). In the muscular tissues of two species of fish ( Prochilodus lineatus and Mylossoma duriventre ) that feed the Amazonian human population, Hg bind to RPS27a with particularly high affinity, and per molecule of RPS27a contains approximately one Hg atoms (J. C. S. Vieira et al, 2020).…”