Oxidative Stress and Antioxidant Defense Mechanisms in Sepia esculenta Larvae Induced by Co-Exposure to Environmental Cadmium and Copper

Cu and Cd, as common heavy metals occurring in the oceans, can induce oxidative stress and toxic responses in marine organisms. Important economic cephalopods inhabit the eastern coastal areas of China, and exposure to Cu and Cd poses a threat to their normal physiological activities, resulting in serious inhibition of their growth. However, the underlying toxicological mechanisms affecting these cephalopods’ larval stages remain to be elucidated. Here, indicators of oxidative stress and transcriptomics were employed to analyze the toxicological mechanisms of S. esculenta larvae exposed to Cd and Cu. GO and KEGG analysis results indicated that material transport, cellular processes, DNA replication, and other processes were inhibited. A comprehensive analysis of a protein–protein interaction network and KEGG pathways was used to explore the mechanism underlying the toxicity of co-exposure to Cu and Cd toward S. esculenta larvae. We found that Cu and Cd induce significant damage and oxidative stress. The results showed that among 20 identified key genes, ITGA4, LAMA1, and LAMC1, which are involved in the adhesion and connection between cells and the extracellular matrix; COL6A1, COL6A3, COL6A4, and COL6A6, which maintain the integrity of the extracellular matrix; and ABCA1, ABCC5, and ABCC7, which regulate the transmembrane transport of Cu and Cd were involved in the mechanism of toxicity. We suggest that co-exposure to the metals primarily inhibits the connection and adhesion between the cells of the larvae and disrupts the structure and function of the extracellular matrix. The results provide a foundation for understanding the toxicological mechanism of S. esculenta and should be of benefit to artificial breeding programs.