Key Laboratory of Applied Marine Biotechnology of Ministry of Education, School of Marine Sciences, Ningbo University, Ningbo, Zhejiang, 315211, China.
Ningbo Academy of Oceanology and Fishery, Zhejiang, 315012, China.
Sci Rep. 2019 Feb 25;9(1):2717. doi: 10.1038/s41598-018-37274-3.
Low temperature influences multiple physiological processes in fish. To explore the adaptability of the large yellow croaker (Larimichthys crocea) to low temperature, the concentrations of glycerol, blood urea nitrogen (BUN), and triglycerides (TG) in plasma, as well as the expression levels of metabolism-related genes aqp7 and aqp10, were measured after exposure to low temperature stress and during subsequent rewarming. In addition, tissue samples from the intestine and liver were histologically analyzed. We found that the concentrations of plasma glycerol, BUN, and TG, decreased under low temperature stress, suggesting the metabolism of fat and protein slowed at low temperature. The expression levels of aqp7 and aqp10 mRNA were also downregulated under exposure to low temperature. Interestingly, above plasma indices and gene expression returned to basic levels within 24 h after rewarming. Furthermore, the liver and the intestine were damaged under continuous low temperature stress, whereas they were repaired upon rewarming. From the above results, we concluded that aqp7 and aqp10 genes were sensitive to low temperature, and that the decrease in their expression levels at low temperature might reduce energy consumption by L. crocea. However, the adaptation to low temperature was limited because the key metabolic tissues were damaged under continuous exposure to low temperature. Interestingly, the metabolism of L. crocea was basically back to normal within 24 h of rewarming, showing that it has high capacity of self-recovery.
低温会影响鱼类的多种生理过程。为了探究大黄鱼（Larimichthys crocea）对低温的适应能力，我们在低温胁迫下以及随后的复温过程中测量了血浆中甘油、血尿素氮（BUN）和甘油三酯（TG）的浓度，以及代谢相关基因 aqp7 和 aqp10 的表达水平。此外，还对肠道和肝脏组织样本进行了组织学分析。我们发现，血浆甘油、BUN 和 TG 的浓度在低温胁迫下降低，表明低温下脂肪和蛋白质的代谢减缓。aqp7 和 aqp10 mRNA 的表达水平也在低温暴露下下调。有趣的是，上述血浆指标和基因表达在复温 24 小时内恢复到基本水平。此外，肝脏和肠道在持续低温胁迫下受损，而在复温后得到修复。从以上结果可以得出结论，aqp7 和 aqp10 基因对低温敏感，低温下其表达水平的降低可能会降低大黄鱼的能量消耗。然而，由于关键代谢组织在持续暴露于低温下受到损伤，大黄鱼对低温的适应能力是有限的。有趣的是，大黄鱼在复温 24 小时内基本恢复正常代谢，表明其具有很强的自我恢复能力。
