Study On Toxicity Mechanism Of Nano Copper To Different Tissues Of Zebrafish

The widespread use of copper nanoparticles(nano-Cu)has raised health risks to the aquatic ecosystems.However,the toxic effects and mechanism of nano-Cu to different tissues of zebrafish is still limited.Therefore,the biological safety and ecological effects of nano-Cu should be paid enough attention.In this study,we found that the bioavailability of zebrafish to nano-Cu is tissue-specific,and the copper content in different tissues is intestine>gill>muscle.Subsequently,the RNA-Seq was performed on the gill,intestine and muscle of zebrafish exposed to nano-Cu,to explore its toxic mechanism to different tissues of zebrafish.The analysis results indicated that,in gill cells,nano-Cu enables CB1 receptor of the presynaptic membrane to affect short-term synaptic plasticity or long-term synaptic changes through DSI(depolarization-induced suppression of inhibition)and DSE(depolarization-induced suppression of excitation),thus causing dysfunction of intercellular signal transmission.However,nano-Cu leads to blocking of many functions involved in pyrimidine metabolic pathway in intestinal cells due to imbalance of UMP(uridine-5'-monophosphate)de novo synthesis and its conversion to UDP(uridine-5'-diphosphate),UTP(uridine-5'-triphosphate),uridine and uracil.Meanwhile,the toxicity of nano-Cu caused abnormal expression of rad51 gene in muscle cells,which affected the repair of damaged DNA through fanconi anemia and homologous recombination pathway,and thus caused cell cycle disorder.This work provides theoretical basis for a more comprehensive evaluation of nano-Cu-induced toxicity on aquatic organism.