Evaluation of reversal and transposition generational damages caused by manganese (II) in zebrafish

Abstract

Although manganese (Mn) is a common water pollutant, little is known about the potential for the trans-generational transfer of biological effects in fish exposed to low concentrations in aquatic organisms, or the persistence of these effects. The aim was to identify when biological effects were firstly observed in the brain, liver and intestinal tissues of zebrafish exposed to environmentally relevant concentrations of Mn and whether these effects were subject to reversal when exposures ceased. We also aimed to assess whether biological effects observed in zebrafish exposed to Mn for 21-days were also observed in the early life stages of the F1 generation. Behavioral changes were observed in the animals exposed for 14 days to MnCl2 (4.0 mg L-1). There was also an oscillation in the mitochondrial activity and TUNEL positive cells in the telencephalon of exposed fish from all treatments. These results indicated that brain neurogenesis in zebrafish occurred with greater magnitude and speed than the neuronal Mn damage. Histopathological changes were observed in the intestine and liver of zebrafish exposed to Mn for 72 h and 21 days. Behavioral alterations and intestinal histopathological alterations were reversed after the recovery period, although hepatocyte vacuolization persisted. Behavioral alterations were also observed in the early developmental stages of F1 generation larvae of zebrafish parents exposed to Mn, but this profile was normalized throughout the development. In addition to the direct toxic effects of low concentrations of Mn, some changes, such as hepatocyte vacuolization persisted in zebrafish even after the toxicant removal.