Parvalbumin and Ubiquitin as Potential Biomarkers of Mercury Contamination of Amazonian Brazilian Fish.

Recent studies have demonstrated the association of mercury (Hg) with some fish proteins, milk, and hair from individuals exposed to the element in the Amazon. However, few studies involve identifying biomarkers of mercury exposure. Therefore, the present study aimed to identify potential biomarkers of Hg exposure in fish. For this, the muscular tissues of two species of fish (Prochilodus lineatus and Mylossoma duriventre) that feed the Amazonian human population were analyzed. Through the analyses obtained by graphite furnace atomic absorption spectrometry (GFAAS), it was possible to identify four protein SPOTS where mercury was present. These SPOTS, identified by mass spectrometry (ESI-MS/MS), included parvalbumin and ubiquitin-40S ribosomal protein S27a, and these being metalloproteins with biomarker characteristics. In addition, the results show the intense Hg/protein ratio observed in the two proteins, which makes metalloproteins strong candidates for biomarkers of mercury exposure. Graphical Abstract.

Physiological and functional aspects of metal-binding protein associated with mercury in the liver tissue of pirarucu (Arapaima gigas) from the Brazilian Amazon.

High concentrations of mercury found in soils, sediments, fish, and humans of the Amazon region have gained prominence in scientific studies during the last decade. However, studies related to the elucidation of mercury toxicity mechanisms in ichthyofauna at the molecular and metallomic levels that seek to elucidate physiological and functional aspects, as well as the search for biomarkers of mercury exposure, are still sparse. In the search for these answers, the present study analyzed the hepatic tissue proteome of the Arapaima gigas (pirarucu) fish species collected in the Jirau hydroelectric power plant reservoir in the state of Rondônia state, Brazil, in order to identify mercury-related metal-binding proteins and to elucidate their physiological and functional aspects. The proteomic profile of the hepatic tissue of Arapaima gigas was obtained by two-dimensional electrophoresis (2D-PAGE) and the presence of mercury was mapped in the protein SPOTS by graphite furnace atomic absorption spectrometry(GFAAS). Mercury was detected in 18 protein SPOTS with concentrations ranging from 0.13 ±â€¯0.003 to 131.00 ±â€¯3 mg kg-1. The characterization of the protein SPOTS associated with mercury was performed by electrospray ionisation tandem mass spectrometry (ESI-MS/MS), and 10 proteins were identified. Bioinformatics analyses showed that most of the proteins found linked to mercury were involved in cellular component processes and biological processes. For the most part, protein sequences have cellular functions comprising catalytic, binding, sense of localization, and metabolic processes.

Changes in energy metabolism induced by fluoride: Insights from inside the mitochondria.

The mechanisms involved in changes in energy metabolism caused by excessive exposure to fluoride (F) are not completely understood. The present study employed proteomic tools to investigate the molecular mechanisms underlying the dose- and time-dependency of the effects of F in the rat liver mitochondria. Thirty-six male Wistar rats received water containing 0, 15 or 50 mgF/L (as NaF) for 20 or 60 days. Rat liver mitochondria were isolated and the proteome profiles were examined using label-free quantitative nLC-MS/MS. PLGS software was used to detect changes in protein expression among the different groups. The bioinformatics analysis was done using the software CYTOSCAPE® 3.0.7 (Java®) with the aid of ClueGo plugin. The dose of 15 mgF/L, when administered for 20 days, reduced glycolysis, which was counterbalanced by an increase in other energetic pathways. At 60 days, however, an increase in all energy pathways was observed. On the other hand, the dose of 50 mgF/L, when administered for 20 days, reduced the enzymes involved in all energetic pathways, indicating a lower rate of energy production, with less generation of ROS and consequent reduction of antioxidant enzymes. However, when the 50 mgF/L dose was administered for 60 days, an increase in energy metabolism was seen but in general no changes were observed in the antioxidant enzymes. Except for the group treated with 50 mgF/L for 20 days, all the other groups had alterations in proteins in attempt to maintain calcium homeostasis and avoid apoptosis. The results suggest that the organism seems to adapt to the effects of F over time, activating pathways to reduce the toxicity of this ion. Ultimately, our findings corroborate the safety of the use of fluoride for caries control.