Influence of increasing acclimation temperature on growth, digestion, antioxidant capacity, liver transcriptome and intestinal microflora of Ussruri whitefish Coregonus ussuriensis Berg

For effective restoration, conservation of Ussruri whitefish Coregonus ussuriensis Berg and coping with global climate change, effects of environmental temperature on Ussruri whitefish urgently need to be explored. In current study, the effects of different acclimation temperatures on the growth, digestive physiology, antioxidant ability, liver transcriptional responses and intestinal microflora patterns of Ussruri whitefish were investigated. Ussruri whitefish (15.20 g ± 1.23 g) were reared for 42 days under different acclimation temperatures, i.e., 10, 13, 16, 19, 22 and 25°C, respectively. Result first determined 28°C as the semi-lethal temperature in order to design the temperature gradient test. Highest main gain rate (MGR) and specific growth rate (SGR) were observed in fish group having acclimation temperature of 19°C. Significantly decrease (P<0.05) in triglyceride (TG) content appeared at 19°C as compared to the 10°C and 13°C temperature groups. 19°C notablely increased protease activities of stomach and intestine and intestinal lipase and amylase activities. 19°C group obtained the highest activities of chloramphnicol acetyltransferase (CAT) and total antioxidant capacity (T-AOC) and higher activities of superoxide dismutase (SOD). The intestinal microflora composition was most conducive to maintaining overall intestinal health when the temperature was 19°C, compared to 10°C and 25°C. Ussruri whitefish exposed to 10°C and 25°C possessed the lower Lactobacillus abundance compared to exposure to 19°C. Temperature down to 10°C or up to 25°C, respectively, triggered cold stress and heat stress, which leading to impairment in intestinal digestion, liver antioxidant capacity and intestinal microflora structure. Liver transcriptome response to 10°C, 19°C and 25°C revealed that Ussruri whitefish might require the initiation of endoplasmic reticulum stress to correct protein damage from cold-temperature and high-temperature stress, and it was speculated that DNAJB11 could be regarded as a biomarker of cold stress response.Based on the quadratic regression analysis of MGR and SGR against temperature, the optimal acclamation temperature were, respectively, 18.0°C and 18.1°C. Our findings provide valuable theoretical insights for an in-depth understanding of temperature acclimation mechanisms and laid the foundation for conservation and development of Ussruri whitefish germplasm resources.