Sepia esculenta is one of the most abundant extant squid populations in Southeast Asia and is of interest due to its rapid reproductive rate and high commercial value. In recent years, with the rapid development of industrialization, issues such as global warming and heavy metal pollution in the oceans have emerged, posing a serious threat to the life activities of marine organisms. In this study, we used transcriptomic techniques to investigate the differences in Cu exposure immune responses in S. esculenta larvae under different temperature conditions. The enrichment of solute carrier family (SLC) genes and genes related to DNA replication and damage was significantly higher in the CuT group than in the Cu group. Functional enrichment analysis revealed that the FcγR-mediated phagocytosis and autophagy pathways were enriched in the CuT group. Based on the analysis of differentially expressed genes (DEGs) and functional enrichment results, we can preliminarily infer that the CuT group caused more severe disruption of intercellular ion transport and DNA replication and repair in larvae compared to the Cu group. This may have further interfered with the normal physiological activities of S. esculenta larvae. Overall, at high temperatures, Cu exposure induces a more intense inflammatory response. The results of this study provide a theoretical foundation for researchers to further understand the effects of environmental factors on the immunity of S. esculenta larvae, as well as preliminary insights into the enhanced toxic effects of metallic copper on aquatic organisms under high-temperature conditions.

The primary influencer of aquaculture quality in Amphioctopus fangsiao is pathogen infection. Both lipopolysaccharides (LPS) and polyinosinic:polycytidylic acid (Poly I:C) are recognized by the pattern recognition receptor (PRR) within immune cells, a system that frequently serves to emulate pathogen invasion. Hemolymph, which functions as a transport mechanism for immune cells, offers vital transcriptome information when A. fangsiao is exposed to pathogens, thereby contributing to our comprehension of the species’ immune biological mechanisms. In this study, we conducted analyses of transcript profiles under the influence of LPS and Poly I:C within a 24 h period. Concurrently, we developed a Weighted Gene Co-expression Network Analysis (WGCNA) to identify key modules and genes. Further, we carried out Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses to investigate the primary modular functions. Co-expression network analyses unveiled a series of immune response processes following pathogen stress, identifying several key modules and hub genes, including PKMYT1 and NAMPT. The invaluable genetic resources provided by our results aid our understanding of the immune response in A. fangsiao hemolymph and will further our exploration of the molecular mechanisms of pathogen infection in mollusks.

Sepia esculenta is a popular economic cephalopod with high yield, delicious meat, and rich nutrition. With the rapid development of heavy industry and medical industry, a large amount of waste has been released into the ocean recklessly in recent years, inducing a significant increase in the content of heavy metals, especially cadmium (Cd) and copper (Cu), in the ocean. This phenomenon significantly affects the growth and development of S. esculenta, causing a serious blow to its artificial breeding. In this study, transcriptome analysis is used to initially explore immune response mechanisms of Cd and Cu co-exposed juvenile S. esculenta. The results show that 1,088 differentially expressed genes (DEGs) are identified. And DEGs functional enrichment analysis results suggests that co-exposure may promote inflammatory and innate immune responses in juvenile S. esculenta. Fifteen key genes that might regulate the immunity of S. esculenta are identified using protein-protein interaction (PPI) network and KEGG enrichment analyses, of which the three genes with the highest number of interactions or involve in more KEGG pathways are identified as hub genes that might significantly affect the immune response processes. Comprehensive analysis of PPI network and KEGG signaling pathway is used for the first time to explore co-exposed S. esculenta juvenile immune response processes. Our results preliminarily reveal immune response mechanisms of cephalopods exposed to heavy metals and provide a valuable resource for further understanding of mollusk immunity.