Metabolism responses to silver nanoparticles stresses during zebrafish embryogenesis

Silver nanoparticles (AgNPs) are widely used in medical, optoelectronic, new energy and other related fields on account of their broad-spectrum antibacterial properties. However, their biological effects on aquatic organism embryogenesis as well as potential molecular characters and mechanisms are still poorly understood. In this study, microarray analysis unveiled the altered expression of metabolic genes in AgNPs-stressed zebrafish embryos at 24 hpf (hour post fertilization). The enrichment in pathways for the down-regulated differentially expressed genes (DEGs) indicated that genes in the metabolic pathways, such as glycolysis/gluconeogenesis, tyrosine metabolism, and fatty acid metabolism, were over-enriched for the gene lists with differential expression in both AgNPs-exposed and AgNPs-injected embryos. It was found that the down-regulated expression of the genes in glycolysis and tyrosine metabolic pathways in AgNPs-stressed embryos at 24 hpf was followed by a compensatory increased expression in embryos at 72 hpf. AgNPs might influence transcriptional expression of the glycolysis and tyrosine genes differentially through their particle and ion portions separately. Additionally, decreased hexokinase & succinate de-hydrogenase activities in glycolysis pathway and high level of pyruvate were observed in the AgNPs stressed embryos, which was similar to the metabolic molecular characters observed in progressive muscular dystrophy patients. Moreover, the altered glycolysis metabolic activities were assumed to influence the muscle fibrils maintenance via regulating the concentration of glycolysis metabolites rather than cell apoptosis and proliferation in trunk muscle cells. Furthermore, the altered tyrosine metabolic activities might be another contributor to touch response defects parallel to the defective neural circuit formation in AgNPs-stressed embryos.