Genotoxicity Effects in Freshwater Fish from a Brazilian Impacted River

Abstract

This study evaluated the incidence of nuclear abnormalities (NA) in four fish species from an impacted river in Northeastern Brazil, characterized by accumulation of heavy metals and organic sewage. Two carnivores (Serrasalmus brandtii and Hoplias malabaricus) and two omnivore species (Oreochromis niloticus and Geophagus brasiliensis), used as food sources by local populations, were collected during the dry and the rainy season along Contas River basin. Nuclear abnormalities (bulbs, binuclei, lobes, micronuclei, notches, and vacuoles) were reported in all fish samples, with high occurrence in S. brandtii and H. malabaricus, species commonly found in local fish markets. This result agrees with previous analyses of accumulation of trace metals in both species, suggesting an association of genotoxic effects and biomagnification. Moreover, native specimens collected near urban areas presented higher frequencies of NA while O. niloticus seems to be more tolerant to environmental contamination. Therefore, effective policies are required to reduce the contamination of Contas River, since pollution by xenobiotics are potential threats to both local biodiversity and human population.

Bioaccumulation of metals and genotoxic effects in females of Colomesus asellus collected in an Amazon River estuary, Amapá, Brazil

“…Smears were stained using Giemsa 10 % solution (De Jesus et al, 2016). Count of nuclear changes was performed under optical microscopy (Nikon Eclipse, E200) with ×1000 magnification.…”

Environmental diagnosis of water quality in situ and ex situ in streams in Upper Paraná River Basin, Brazil

“…Then, the sh were immersed in cold water in situ to reduce their activity to obtain blood samples through a cut in the caudal peduncle. For each sh sample, two blood smear slides were made that were air dried for 15 min and xed in absolute alcohol for another 15 min (Schmid 1975;Jesus et al 2016;De Souza et al 2019). Then, the slides were hydrolyzed in hydrochloric acid (HCl; 1N) for 10 min at 60°C, washed in distilled water, stained with reactive Schiff overnight, and counter-stained with Fast green.…”

Are there differences in the frequency of micronuclei in Astyanax lacustris in relation to sex, mass and length?

“…For each fish sample, a drop of blood was placed on two slides, to form a thin layer. The smears were dried in air for 15 min, fixed in absolute alcohol for 10 min and then stained with Giemsa solution at 10% for 20 min (Schmid, 1975;Jesus et al, 2016). 2000 blood cells per slide were analyzed, resulting in a total of 4000 cells for everyone, using an optical microscope with magnification of 1000x.…”