Encurtamento telomérico e danos genotóxicos em bioindicadores aquáticos em afluentes do rio Iguaçu (Brasil)

Abstract

Human activities result in toxic pollutants that can contaminate the ecosystem, and generally surface and underground waters are the main recipients of these residues. In many cases, these residues have the capacity to provide genotoxic effects with DNA damage and telomeric shortening. In this sense, the objective of our research was to monitor the quality of the Iguaçu River, one of the most important rivers in Brazil and which was once considered the second most polluted in the country, using the native species Rhamdia quelen to check the length of telomeres and DNA damage. We selected the municipalities of Dois Vizinhos (DV) and Cascavel (CVL) in addition to the metropolitan region of Curitiba (RMC) for verification. For each location, we selected three points with different characteristics to compare with a control point, the Iguaçu National Park (PNI). At each point we collected muscle and kidney samples from 20 individuals for analysis of telomere length by qPCR and DNA damage by comet assay. Significant telomere shortening was observed in six of the nine sampling points, with emphasis on the three urban points, where all showed significantly greater shortening compared to the PNI. Only the rural point of Cascavel differed statistically from the control point. In relation to the so-called preserved points, DV and RMC presented statistically shorter telomeres. In relation to DNA damage, five points showed statistically higher breakage rates compared to the PNI, with the three Cascavel points being among them, in addition to preserved DV and RMC. Our results demonstrated that there is evidence of genotoxic damage to native species throughout the Iguaçu River basin, which is worrying due to the highly endemic nature of the river and its importance for the region where it is located.