Multi-omics analysis of the effects of dietary Spirulina replacing different ratios of fishmeal on the liver metabolic function of Zig-zag eel (Mastacembelus armatus)

Abstract

The demand for fishmeal brought about by the vigorous development of the aquaculture industry has brought unprecedented stress to the ecological environment. In this experiment, Spirulina platensis powder (SPP) was used to replace 0 % (F0), 5 % (F1), 10 % (F2), 15 % (F3), and 20 % (F4) of fishmeal in the diet of Zig-zag eel (Mastacembelus armatus, MA), respectively. The metabolic mechanisms of the MA on SPP-containing diets were analyzed by histomorphology, liver biochemical indices, transcriptomics, and metabolomics. The final results of the study showed that, after replacing a portion of the fishmeal, SPP significantly improved the degradation of lipids and decreased the accumulation of fat in the liver of MA. The SOD of F3 was significantly lower than that of F0 and the other experimental groups (P < 0.05), and the T-AOC of F4 was significantly lower than that of the control group and all the other groups (P < 0.05). The transcriptome results indicated that the increase in SPP addition ratio significantly up-regulated relevant pathways of protein metabolism and lipid metabolism. These pathways included the cAMP signaling pathway, the PI3K-Akt signaling pathway, the MAPK signaling pathway, pancreatic secretion, protein digestion and absorption, fat digestion and absorption, steroid biosynthesis, and glycerolipid metabolism. Metabolomic results confirmed that SPP addition significantly affected the α-linolenic acid metabolism pathway and resulted in a decrease of this metabolite. This information lays the theoretical foundation for the application of SPP and extends our understanding of the potential mechanisms of liver metabolism as it replaces fishmeal.