Effects of anthropogenic influences in the DNA methylation and expression of genes involved in the metabolism of Geophagus surinamensis from the Pará River (Amazon, Brazil).

The Amazon region has been experiencing increasing anthropogenic pressures, especially in Barcarena, Pará, Brazil, where industrial activities such as aluminum refining and chemical processing have led to repeated contamination events. This study aimed to understand how multiple environmental stressors from an industrial complex affect Geophagus surinamensis, a native Amazonian fish, at the molecular level. We analyzed muscle, liver, and gill tissues of G. surinamensis collected in Barcarena, Abaetetuba, and Breves. We conducted DNA methylation analysis of the promoter regions of the cyp1b1 (involved in pollutant metabolism) and slc16a12b (a molecule transporter) genes using methylation-specific PCR (MSP) and quantified their expression. A hemimethylation pattern was found in all studied tissues and sampling sites for the cyp1b1 gene, whereas methylation patterns were more frequently observed for slc16a12b. Gene expression varied across sites and tissues. Muscle showed the highest expression of both genes, followed by liver and gills, with cyp1b1 more active than slc16a12b. In the gills, the expression levels of the two genes were positively correlated. These findings show that G. surinamensis exhibits biological responses to pollution and can be used as a bioindicator species. The study highlights the importance of using native species and molecular biomarkers to monitor the environmental impacts of industrial pollution in the Amazon.