Carboxin can induce cardiotoxicity in zebrafish embryos.

Carboxin is a heterocyclic systemic fungicide, mainly used to prevent and control grain smut and wheat rust. Although its mammalian toxicity has been reported, its toxicity to acute exposure to aquatic animals is unknown. In our study, we used zebrafish as aquatic organisms to study Carboxin toxicity. Carboxin can cause developmental toxicity and cardiotoxicity in zebrafish embryos. Histopathological staining of cardiac sections reveals structural changes in zebrafish hearts, and fluorescence quantitative PCR results shows the heart developmental genes mRNA expression levels were disrupted significantly. Besides, carboxin can also cause oxidative stress and reactive oxygen species (ROS) accumulation in zebrafish embryos. The accumulation of ROS causes mitochondrial damage, which is where ATP energy is produced. So ATPase activities and gene expression level were measured and significantly decreased after exposure to carboxin. From the confocal images, the number of blood cells in the heart were decreased significantly after carboxin exposure. Besides, Carboxin exposure can inhibit myocardial cell proliferation. These are all causes to the heart failure, eventually leading to embryos death.