Abstract:Takifugu rubripes is a fierce, benthic, carnivorous, and stenothermic fish species. With global warming, physiological reactions such as stress are more common, due to rising temperatures in factory cultures, which result in declined breeding benefits. Stress can disrupt intracellular homeostasis and cause changes in other physiological and immune responses. Temperature is an important environmental variable that affects immune responsivity in fish. Among temperature stressors, heat stress is considered the most basic mechanism of cell protection in animals. Increased body temperature due to changes in the environmental temperature is a natural physiological response in fish, so it is practical to study the response of the vital organs of fish under heat stress. Taurine promotes fish growth, improves immune ability and stress resistance, and is closely related to the physiological and nutritional status of aquatic animals under stress. To explore the relationships between taurine and acute heat stress tolerance in fish, three diets of 0% (T1, control), 1.0% (T2), and 5.0% (T3) taurine were fed to T. rubripes[initial body weight:(32.28±0.20) g] for 56 d. At the end of the breeding experiment, a high-temperature[(28±0.3)℃) stress test was conducted for 30 min, and the three experimental groups were analyzed for their liver transcriptomes by RNA-Seq. The differentially expressed genes (DEGs) were screened with a threshold criterion of P<0.05. In total, 167 DEGs were identified under acute heat stress among which 111 genes were up-regulated and 56 genes were down-regulated. Gene ontology (GO) enrichment analysis showed that most of the DEGs in the T3 vs T1 group were significantly enriched in the proteolysis, serine-type peptidase activity, serine-type endopeptidase activity, serine hydrolase activity, endopeptidase activity, L-amino acid peptidase activity, and peptidase activity pathways. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis showed that most of the DEGs were involved in cell adhesion molecules and neuroactive ligand-receptor interaction pathways in T2 vs T1, while most of the DEGs were involved in the neuroactive ligand-receptor interaction and metabolic pathways in T3 vs T1. These results suggest that dietary taurine supplementation can change the temperature response of T. rubripes under acute heat stress and that the response varied with the amount of taurine. Real-time PCR (RT-PCR) was used to verify the transcriptome sequencing results, and the results showed similar expression patterns for 3 different genes in the RNA-seq and RT-PCR data. This indicates that the gene expression results of the transcriptome sequencing are credible. This study provides foundational information to further studying the effects of dietary taurine supplementation on the acute heat stress response in T. rubripes. This study also serves as an indicator of taurine's ability to resist heat stress.