Transition to Time-Dependent Artificial Feed Induces Histological and Apoptotic Alterations in Mandarin Fish (Siniperca chuatsi)

This study aimed to investigate the response mechanisms of liver and gill tissues in mandarin fish (Siniperca chuatsi) at the histological, apoptotic, and gene expression levels during the weaning process from live prey to artificial feed. By analyzing fish samples at different domestication stages (D0, D7, D14), the results revealed that: (1) Histologically, the gill filaments exhibited shortening and thickening post-domestication, while the liver showed increased vacuolation; (2) apoptosis detection (TUNEL assay) and analysis of apoptosis-related gene (Bax/Bcl-2) expression indicated that the gill tissue experienced a significant increase in apoptosis at the mid-domestication stage (D7), which returned to baseline levels later (D14), whereas hepatic apoptosis showed no significant changes throughout the process; (3) transcriptome sequencing identified 3405 and 881 differentially expressed genes (DEGs) in the liver and gill tissues, respectively, and the significantly enriched pathways were steroid biosynthesis in the liver and alanine, aspartate, and glutamate metabolism in the gills. The apoptosis pathway was also significantly enriched in both tissues. GO analysis further indicated that the DEGs were primarily associated with metabolic processes, oxidative stress, and cell apoptosis. In conclusion, artificial feed domestication induces adaptive changes in the tissue structure and molecular profiles of the gill and liver in mandarin fish. The gill response to dietary transition is more rapid and characterized by a reversible apoptotic process, providing a theoretical foundation for understanding the stress mechanisms associated with domestication and promoting healthy aquaculture practices for this species.