Manganese Exposure Induces Cellular Aggregates and the Accumulation of Β-Catenin in Skin of Zebrafish Embryos

The effects of manganese (Mn) toxicity in different organs and tissues in humans and other vertebrates have been studied since the beginning of the past century, but most of its cellular effects remain largely unknown. In this study, we studied the effects of Mn in zebrafish, at the cellular level, due to the transparent nature of zebrafish larvae that enables a powerful analysis under the light microscope. The collection of our results shows that environmental concentrations of 0.5 mg/L affect swim bladder inflation; at concentration of 50 and 100 mg/L Mn (1) induces alterations in viability, swim bladder, heart, and size of zebrafish larvae, (2) induces an increase in melanocyte area and the formation of cellular aggregates in the skin, and (3) induces an accumulation of β-Catenin in mesenchymal cells in the caudal fin of zebrafish larvae. Our data suggest that increased levels of Mn induce cell aggregate formation in the skin and the presence of more melanocytes in the zebrafish caudal fin. Interestingly, the adhesion protein β-Catenin was activated in mesenchymal cells near the cell aggregates. These results open important new questions on the role of Mn toxicity on cellular organization and β-Catenin responses in fishes.