Metabolic plasticity and gut microbiome synergy underlie high-altitude adaptation in the plateau frog Rana kukunoris:...

Life on the Qinghai-Tibet Plateau is exposed to extreme abiotic stressors, yet endemic frog species such as Rana kukunoris thrive due to specialized adaptations. However, the metabolic and gut microbial mechanisms that enable survival at high altitude remain unclear. Here, we used metabolomic analysis and metagenomic sequencing to compare metabolic profiles of liver and skeletal muscle, as well as gut microbial composition and function, between high- (3730 m) and low-altitude (1990 m) populations. Metabolomic profiling revealed significant altitude-driven shifts, including the down-regulation of glycolysis (fructose-1,6-bisphosphate and glyceraldehyde 3-phosphate decreased by 44.2 % and 40.7 %, respectively) and tricarboxylic acid (TCA) cycle intermediates (fumaric acid and malic acid reduced by 37.7 % and 35.9 %, respectively) in the liver, and enhanced oxidative phosphorylation efficiency via elevated flavins (flavin mononucleotide and flavin adenine dinucleotide increased 1.43- and 1.28-fold, respectively) in skeletal muscle. These findings suggest a conserved strategy of metabolic rate depression and tissue-specific metabolic regulation. Significantly differential metabolites were enriched in glycerophospholipid metabolism and glycosylphosphatidylinositol (GPI)-anchor biosynthesis, highlighting membrane remodeling as a key adaptive response to cold stress at high altitudes. Moreover, gut microbiomes of high-altitude frogs exhibited increased α-diversity and functional enrichment in the biosynthesis of secondary metabolites, cofactors, amino acids, and carbohydrate-active enzymes (GHs/GTs), all likely improving tolerance to stressful environments and maintaining homeostasis. Key microbial taxa, including Candidatus Udaeobacter, Desulfovibrio, Bradyrhizobium, and Akkermansia, showed a specific dominance in high-altitude frogs, which may support host energy homeostasis and fortify gut barrier function. Multi-omics data highlighted the convergence of protective mechanisms in high-altitude frogs, including autophagy and two-component/quorum sensing systems. This study reveals significant adaptive remodeling of metabolism and gut microbiota in high-altitude R. kukunoris, providing novel insights into host-microbe synergistic interactions under extreme environments.