Transcriptome Profile Based on Protein-Protein Interaction Networks Provides a Set of Core Genes for Understanding the Metabolic Mechanisms of the Egg-Protecting Behavior in Amphioctopus fangsiao

Marine organisms cannot grow and reproduce without proper metabolic regulation. Within a metabolic network, problems with a given link will affect the normal life activities of the organism. Many metabolic mechanisms associated with behaviors of Amphioctopus fangsiao are still unclear. Moreover, as a factor affecting the normal growth of A. fangsiao, egg protection has rarely been considered in previous behavioral studies. In this research, we analyzed the transcriptome profile of gene expression in A. fangsiao egg-unprotected larvae and egg-protected larvae, and identified 818 differentially expressed genes (DEGs). We used GO and KEGG enrichment analyses to search for metabolism-related DEGs. Protein-protein interaction networks were constructed to examine the interactions between metabolism-related genes. Twenty hub genes with multiple protein-protein interaction relationships or that were involved in multiple KEGG signaling pathways were obtained and verified by quantitative RT-PCR. We first studied the effects of egg protection on the metabolism of A. fangsiao larvae by means of protein-protein interaction networks, and the results provide valuable gene resources for understanding the metabolism of invertebrate larvae. The data serve as a foundation for further research on the egg-protecting behavior of invertebrates.