Transcriptome and physiological analysis reveal the regulation mechanism underlying the muscle quality effect of dietary S. chinensis in triploid crucian carp (Carassius auratus)

Schisandra chinensis (S. chinensis, sc) is generally demonstrated to improve antioxidant and immune functions in mammal. However, there is a lack of data concerning the effects of S. chinensis on fish health status and muscle quality. The study through transcriptome and physiological analysis reveals health status and alterations in muscle metabolisms of triploid crucian carp (Carassius auratus) cultured at different concentrations of S. chinensis diets after 8 weeks. The serum antioxidant enzyme activities analysis showed dietary S. chinensis could reduce oxidative stress, elevate organismic antioxidant capacity. Meanwhile, the detected results of muscle components presented that the amino acids and two flavor nucleotides of GMP and IMP significantly elevated while muscle crude lipid significantly reduced in S. chinensis feeding groups. In addition, springiness, gumminess chewiness, muscle fiber diameter and area in S. chinensis feeding groups muscle were significantly elevated while fiber density showed an opposite trend. By comparative transcriptome analysis of the muscles, 3879 (1451 up, 2399 down), 2840 (1105 up, 1735 down), 2069 (909 up, 1160 down), 3100 (1307 up, 1793 down), and 3194 (1369 up, 1825 down) differentially expressed genes (DEGs) between the sc0 group and the sc0.125%, sc0.25%, sc0.5%, sc1%, and sc2% groups, respectively. Functional analysis of DEGs showed that multiple enriched terms were related to purine metabolism, glycerolipid metabolism, regulation of actin cytoskeleton, and peroxisome. Finally, weighted gene co-expression network analysis (WGCNA) was performed to construct gene co-expression networks, and identified key factors which may play vital roles in regulating the molecular response to S. chinensis feeding in muscle of triploid crucian carp. Taken together, our findings facilitate the understanding of the molecular basis underlying the muscle quality effect of dietary S. chinensis in triploid crucian carp, which provides valuable insights into the nutritional strategies of the aquaculture industry.