Transcriptome-and metabolome-based mechanisms of high-temperature adaptation in triploid rainbow trout (Oncorhynchus mykiss)

ABSTRACT:

High-temperature stress critically challenges cold-water aquaculture; however, the size-dependent molecular mechanisms underlying thermal adaptation in triploid rainbow trout (Oncorhynchus mykiss) remain poorly understood. Here, we integrated transcriptomic and metabolomic profiling of liver tissues from three body-weight classes-small (0.8 kg), medium (1.5 kg), and large (2.5 kg)-sampled under peak summer heat stress. Transcriptomic analysis identified 974, 570, and 862 group-specific differentially expressed genes, respectively, revealing a non-linear, size-dependent transcriptional pattern. The ribosome pathway was universally enriched across all size groups, whereas carbon metabolism and amino acid biosynthesis were enriched exclusively in smaller fish, indicating a higher catabolic burden under heat stress. Metabolomic profiling identified 1,123 metabolites, with lipids accounting for 45.06%, and showed size-specific enrichments in biosynthesis of unsaturated fatty acids, glycerophospholipid metabolism, arachidonic acid metabolism, and necroptosis. Integrative analysis revealed that in smaller fish, pla2g1b and gpx4a coordinately regulate the accumulation of prostaglandin H2 and 16(R)-HETE, forming a regulatory network with ferroptosis-related genes acsl4a and hmox1a; concurrently, chka, lpin1, and phospholipase A2 members drive extensive membrane phospholipid remodeling. A negative correlation between hsd17b3 and 7alpha-hydroxytestosterone suggests size-dependent steroid-mediated energy repartitioning. Collectively, smaller fish undergo extensive transcriptional and metabolic reprogramming with heightened activation of cell death pathways, whereas larger fish maintain greater thermal buffering capacity. These findings provide molecular targets for size-stratified thermal management and selective breeding in rainbow trout aquaculture.

INSTRUMENT(S): Liquid Chromatography MS - negative - reverse-phase, Liquid Chromatography MS - positive - reverse-phase

PROVIDER: MTBLS14507 | MetaboLights | 2026-05-17

REPOSITORIES: MetaboLights