Multi-omics insights into the adaptive mechanisms of Luciobarbus brachycephalus to optimal alkalinity

This study determined the biochemical indicators of gills, serum, gut, and liver in Luciobarbus brachycephalus under optimal alkalinity. Meanwhile, liver transcriptomics and metabolomics were performed to explore the adaptive mechanisms. Results showed that under optimal alkalinity, L. brachycephalus displayed significant increases in blood urea nitrogen (BUN) and Na + /K + -ATPase activity with stable blood ammonia (BA), revealing that the species maintains osmotic homeostasis and avoids ammonia toxicity by converting ammonia into low-toxic urea. Hepatic antioxidant indicators (SOD, CAT, MDA) remained unchanged, implying no oxidative stress. Decreased amylase activity and elevated pepsin and lipase activities indicated adaptive regulation of intestinal nutrient metabolism. Transcriptomic and metabolomic analyses identified 341 differentially expressed genes (DEGs) and 292 differentially expressed metabolites (DEMs) between group A15 and A0. Both omics datasets showed significant enrichment ( P < 0.05) in seven conserved pathways, including Biosynthesis of unsaturated fatty acids, Central carbon metabolism in cancer, Glycerophospholipid metabolism, Phenylalanine metabolism, Alanine, aspartate and glutamate metabolism, Long-term depression, Glycine, serine and threonine metabolism. This study reveals that L. brachycephalus is capable of maintaining antioxidant and immune homeostasis under optimal alkalinity, and preserves osmotic balance via the activation of ion transport pathways. In addition, activation of the hepatic pentose phosphate pathway, glycolysis, and TCA cycle helps optimize energy provision and promotes growth performance.