Objective: To investigate the molecular mechanisms on the alleviating effects of organic selenium on heat stress-induced liver injury in kaluga sturgeon. Methods: Four experimental groups were established as followed: control group (C, commercial feed at 19°C), organic selenium supplement group (S, commercial feed supplemented with 5mg/kg Se at 19°C), heat stress group (R, commercial feed at 28°C), and heat stress + organic selenium group (RS, 5mg/kg Se feed at 28°C). Liver tissues were sampled after 30 d heat stress treatment for subsequent transcriptome sequencing. Differentially expressed genes (DEGs) were identified and mapped to corresponding GO terms/KEGG pathways while PI3K-Akt pathway-related genes were validated by qRT-PCR. Results: 8715 DEGs were identified (3642 up-regulated, 5073 down-regulated) between R group and C group. GO enrichment analysis revealed DEGs could be enriched into cell cycle regulation, cell division, DNA repair, and transcription factor binding. KEGG analysis showed PI3K-Akt signaling pathway, cell cycle checkpoints, DNA replication, p53 pathway and glutathione metabolism could be significant enriched. qRT-PCR validation showed that heat stress significantly down-regulated CCND1 and mTOR by 2.3-fold and up-regulated HSP90 by 2.9-fold. Interestingly, organic selenium supplement effectively reversed these expression patterns changes induced by thermal exposure. Conclusion: Organic selenium effectively alleviated heat stress-induced liver injury in kaluga sturgeon by regulating PI3K-Akt signaling pathway. Our study would provide molecular evidence for understanding the detailed mechanism on the negative effects of heat stress on aquatic animals and pave path for the development of bio-active feed supplement agent to attenuate the harmful impacts of thermal stress.
 

Kaluga sturgeon； Organic selenium； Heat stress；Transcriptomics