Silver nanoparticles impair zebrafish skeletal and cardiac myofibrillogenesis and sarcomere formation

Metal nanoparticles from industries contaminate the environment and affect the normal development of fish even human health. However, little is known about their biological effects on fish embryogenesis and the potential mechanisms. In this study, zebrafish embryos exposed to/injected with silver nanopaticles (AgNPs) exhibited shorter body, reduced heartbeats, and dysfunctional movements. Less, loose, and unassembled myofibrils were observed in AgNPs-treated embryos, and genes in myofibrillogenesis and sarcomere formation were found to be down-regulated in treated embryos. Down-regulated calcium (Ca²⁺) signaling and loci-specific DNA methylation in specific muscle genes, such as bves, shroom1, and arpc1a, occurred in AgNPs-treated embryos, which might result in the down-regulated expression of myofibrillogenesis genes and muscle dysfunctions in the treated embryos. Our results for the first time reveal that through down-regulating Ca²⁺ signaling and myogenic loci-specific DNA methylation in zebrafish embryos, AgNPs might induce defects of myofibril assembly and sarcomere formation via their particles mostly, which may subsequently cause heartbeat reduction and behavior dysfunctions.