Transcriptome, antioxidant enzymes and histological analysis reveal molecular mechanisms responsive to long-term cold...

Temperature is a major environmental factor influence fish growth, development, metabolism and physiological performance. Silver pomfret (Pampus argenteus) is an economically important fishery species, however, the molecular mechanisms responsive to long-term cold stress are still unclear. Hence, we altered water temperature from 13 °C to 8 °C, a logistic fit curve for the survival rate of P. argenteus under a gradient cold stress were thus achieved, 50% survival rate at a measured temperature of 7 °C-7.5 °C. After stimulation, the gill, liver and muscle tissues were investigated through transcriptome, antioxidant enzymes and histological observation. The results showed that antioxidant enzyme and Na⁺-k⁺ ATPase activity in gill tissue was significantly increased, tissue damage and apoptosis were observed in multi-tissues. By high-throughput sequencing, a total of 618,097,404 reads of raw data and 598,855,490 reads of clean data were obtained, containing 12,489 differently expressed genes (DEGs). KEGG pathway enrichment analysis showed that DNA replication, protein digestion and absorption, cardiac muscle contraction, adrenergic signaling in cardiomyocytes, and metabolic pathways were significantly enriched in multi-tissues. Fifteen DEGs were selected for real-time PCR (RT-qPCR) analysis, and the results were consistent with transcriptome profiling. Based on the results, we inferred that P. argenteus survived at low temperatures may be achieved by improving the ability to scavenge oxyradical substance and enhancing cell fluidity. This present study indicated that the effects of long-term cold stress on P. argenteus, which is valuable for breeding cold-tolerant P. argenteus stocks for cultivation.