Li Chenxing, Liu Chenyu, Hu Pingxia, Zheng Xiyu, Li Ming, Liu Jinsong
College of Life and Environmental Sciences, Wenzhou University, Wenzhou 325035, China.
J Exp Biol. 2022 Sep 1;225(17). doi: 10.1242/jeb.244502. Epub 2022 Sep 9.
For small birds to survive during seasonal acclimatization in temperate zones, regulation of body mass and thermogenesis is crucial. To determine the role of temperature and photoperiod in seasonal changes in body mass and thermogenesis in Chinese hwameis (Garrulax canorus), we compared body mass, basal metabolic rate (BMR), energy intake and cellular metabolic capacity of the tissue (muscle) and/or organs (liver, kidney, heart and small intestine) in seasonally acclimatized and laboratory-acclimated hwameis. A significant seasonal influence on body mass and BMR (which peaked in winter) was found, and these variations were mirrored by exposing the housed birds to cold temperatures or a short photoperiod. The level of dry matter intake, gross energy intake and digestible energy intake was higher during winter, and in housed animals that were exposed to cold temperatures. These results suggest that by increasing energy intake and thermogenesis, Chinese hwameis can overcome winter thermoregulatory challenges. When compared with warm-acclimated birds, cold-acclimated birds displayed higher mass-specific and whole-organ state 4 respiration in the muscle, liver and kidney, and higher mass-specific and whole-organ cytochrome c oxidase activity in the liver. These data demonstrate that cellular thermogenesis partly underpins basal thermoregulation in Chinese hwameis. Cold temperature and short photoperiod can be used as helpful environmental cues during seasonal acclimatization. However, the role of temperature is more significant compared with that of photoperiod in Chinese hwameis; the changes in energy metabolism and thermoregulation induced by temperature appear to be intensified by photoperiod.
对于小型鸟类在温带地区季节性适应过程中生存而言，体重调节和产热至关重要。为了确定温度和光周期在中国画眉（Garrulax canorus）体重和产热季节性变化中的作用，我们比较了季节性适应和实验室适应的画眉的体重、基础代谢率（BMR）、能量摄入以及组织（肌肉）和/或器官（肝脏、肾脏、心脏和小肠）的细胞代谢能力。发现体重和基础代谢率存在显著的季节性影响（冬季达到峰值），将圈养鸟类暴露于低温或短光周期下也会出现类似变化。冬季以及暴露于低温环境下的圈养动物的干物质摄入量、总能摄入量和可消化能量摄入量水平更高。这些结果表明，通过增加能量摄入和产热，中国画眉能够克服冬季体温调节挑战。与温暖适应的鸟类相比，冷适应的鸟类在肌肉、肝脏和肾脏中表现出更高的质量比和全器官状态4呼吸，在肝脏中表现出更高的质量比和全器官细胞色素c氧化酶活性。这些数据表明，细胞产热部分支撑了中国画眉的基础体温调节。低温和短光周期可作为季节性适应过程中的有益环境线索。然而，在中国画眉中，温度的作用比光周期更为显著；温度引起的能量代谢和体温调节变化似乎会因光周期而加剧。
