Zebrafish models for attention deficit hyperactivity disorder (ADHD)

Attention deficit hyperactivity disorder (ADHD) is a common, debilitating neurodevelopmental disorder associated with inattentiveness, pathological hyperactivity and impulsivity. Despite the mounting human and animal evidence, the neurological pathways underlying ADHD remain poorly understood. Novel translational model organisms, such as the zebrafish (Danio rerio), are becoming important tools to investigate genetic and pathophysiological mechanisms of various neuropsychiatric disorders. Here, we discuss ADHD etiology, existing animal models and their limitations, and emphasize the advantages of using zebrafish to model ADHD. Overall, the growing utility of zebrafish models may improve our understanding of ADHD and facilitate drug discovery to prevent or treat this disorder. © 2019 Elsevier Lt

Coal extraction causes sediment toxicity in aquatic environments in Santa Catarina, Brazil

This study evaluated water parameters in ponds affected by coal extraction. Allium cepa assay was used to measure genotoxicity/mutagenicity of the sediment. Samples were collected from four ponds in the southern state of Santa Catarina. Water temperature, pH, dissolved oxygen, conductivity and turbidity were measured. Sediments were analyzed for heavy metals. Elutriate samples were prepared at a ratio of 1:4 sediment:water. Allium cepa bulbs were placed in samples prepared from each pond, with ultrapure water used as negative control and methyl methane sulfonate as positive control. Root length, mitotic index, chromosomal aberrations, micronuclei, and nuclear abnormalities were measured. The pH of two ponds, as well as electrical conductivity and dissolved oxygen of all ponds were below the minimum limits set by Brazilian regulation. All heavy metals analyzed were found in all sediment samples, but only Cd concentration was above the legal limit set by Brazilian law. Allium cepa root growth for samples from Ponds 1, 2, and 4 was significantly lower than the negative control. Meristematic cells exposed to elutriate samples showed no significant changes in cell division. There was a significant increase in total chromosomal aberrations in all treated samples in comparison with the negative control. This study demonstrates that even low concentrations of heavy metals can damage exposed biota, possibly due to synergistic effects. We also found the A. cepa bioassay to be a simple and useful tool for genotoxicity/mutagenicity analyses, and recommend its use for environmental monitoring and management in areas influenced by mining activities