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.

The stable marine environment is conducive to the development of the aquaculture industry. However, with the change of seawater salinity in recent years, it has had a great impact on the survival and breeding of cephalopods such as Sepia esculenta. In this study, biochemical measurement and transcriptome sequencing were performed on the larvae of S. esculenta after different salinity stresses (salinity of 20 ppt and 40 ppt), and the reliability of transcriptome results was proved by physiological indexes. We performed Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis, and gene set enrichment analysis (GSEA) on all annotated genes, and gene sets were identified, including chemokine signaling pathways, MAPK signaling pathways, and cell cycle pathways. Finally, we constructed the protein-protein interaction networks (PPI) between the core genes in these gene sets and differentially expressed genes (DEGs) to identify key genes, including NFKBIA. Among them, the NFKBIA is not only a core gene in the chemokine signaling pathway gene set under four stresses but also has a high number of protein interactions. We speculate that this gene may have important immunomodulatory functions in the face of different time and salinity stresses. The results of our study explored the molecular mechanism of S. esculenta in the face of environmental stress, revealed the key molecular regulatory pathways for its survival and adaptation under complex environmental pressures, and may provide insights relevant to the development of S. esculenta pond culture.

Apostichopus japonicus is a temperate marine echinoderm whose growth and reproduction are strongly influenced by temperature. We compared adult sea cucumbers exposed to stepwise warming (10–12, 12–14, and 14–16 °C across three successive 20-day stages) with animals maintained at 15 °C. Growth indices, gonadosomatic index (GSI), gonadal histology, and energy-budget components were evaluated in females and males. The 60 d experiment used three replicate tanks for each treatment-by-sex combination. Compared with the constant 15 °C treatment, the stepwise-warming regime showed a higher female GSI at stage III; representative gonadal sections documented stage-related structural changes in both treatments. No significant treatment effects were detected for final wet weight, specific growth rate, daily growth rate, or feed conversion ratio. Excretory energy decreased during stages II and III, while the proportion allocated to gonadal growth increased. Stage-specific within-sex comparisons showed higher gonadal growth energy under stepwise warming in both sexes during stage II, while the clearest GSI difference occurred in females during stage III; treatment × sex interactions were not significant. The clearest differences between the two temperature regimes were observed during stages II and III (12–16 °C). The findings provide an integrative physiological basis for temperature management during broodstock conditioning of A. japonicus.