Abstract
Simple SummaryAt present, climate warming is a very serious environmental problem. A sudden and large increase or decrease in temperature is likely to cause stress response in animals. Rainbow trout is a kind of cultured cold-water fish, which is very sensitive to high temperature. Therefore, it is very vulnerable to heat waves during production. The current study found that the behavior, antioxidant capacity, and natural immune function of rainbow trout under acute heat stress were significantly enhanced in the early stages of stress response, but its anti-stress ability decreased with an increase in stress intensity and duration. Transcriptome sequencing and bioinformatics analysis showed that some non-coding RNAs could competitively bind to target genes, and jointly participate in metabolism, apoptosis, and the immune regulation of rainbow trout under stress environments. In conclusion, our study can lay a theoretical foundation for the breeding of heat-resistant rainbow trout varieties.As the global climate warms, more creatures are threatened by high temperatures, especially cold-water fish such as rainbow trout. Evidence has demonstrated that long noncoding RNAs (lncRNAs) play a pivotal role in regulating heat stress in animals, but we have little understanding of this regulatory mechanism. The present study aimed to identify potential key lncRNAs involved in regulating acute heat stress in rainbow trout. lncRNA and mRNA expression profiles of rainbow trout head kidney were analyzed via high-throughput RNA sequencing, which exhibited that 1256 lncRNAs (802 up-regulation, 454 down-regulation) and 604 mRNAs (353 up-regulation, 251 down-regulation) were differentially expressed. These differentially expressed genes were confirmed to be primarily associated with immune regulation, apoptosis, and metabolic process signaling pathways through Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis and coding-noncoding co-expression network analysis. These results suggested that 18 key lncRNA-mRNA pairs are essential in regulating acute heat stress in rainbow trout. Overall, these analyses showed the effects of heat stress on various physiological functions in rainbow trout at the transcriptome level, providing a theoretical basis for improving the production and breeding of rainbow trout and the selection of new heat-resistant varieties.
Highlights
Rainbow trout are cold-water fish that are widely farmed worldwide
These results indicated that the innate immune function of rainbow trout might be enhanced in the early stages of acute heat stress, lipid metabolism would be impaired with the accumulation of many peroxides, which leads to oxidative damage
The present study provides a systematic description of the changes in long noncoding RNAs (lncRNAs) and mRNAs in rainbow trout under acute heat stress conditions
Summary
Rainbow trout are cold-water fish that are widely farmed worldwide They have no obvious lower limit of temperature, 0–18 ◦C is their optimum growth temperature, and they are extremely sensitive to high temperature. When the water temperature exceeds 20 ◦C, it will cause a series of obvious stress reactions, such as reduced or decreased intake, abnormal behaviors, growth and reproduction disorders, and immunosuppression [1]. In water, their body temperature is close to the temperature of the surrounding water. Shallow water will heat up rapidly (especially in intensive artificial environments), making the ambient temperature of rainbow trout close to the extreme temperature they can withstand. This makes the rainbow trout an ideal test species for studying whether physiological regulation can keep up with rising temperatures
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