School of Life and Environmental Sciences, Wenzhou University, Wenzhou 325035, China.
Comp Biochem Physiol A Mol Integr Physiol. 2013 Mar;164(3):483-90. doi: 10.1016/j.cbpa.2012.12.004. Epub 2012 Dec 14.
Acclimatization to different ambient conditions is an essential prerequisite for survival of small passerine birds. Long-distance migration and winter acclimatization induce similar physiological and biochemical adjustments in passerines. To understand metabolic adaptations, the resting metabolic rate (RMR), the thermogenic properties of mitochondria in liver and muscle, and the activity of thyroid hormones were examined in field-captured little buntings (Emberiza pusilla) between Southeastern (Wenzhou) and Northeastern (Qiqihar) China from March to May in 2008 during their migration. Twelve birds were trapped from March to April in Wenzhou region, Zhejiang Province (27°29'N, 120°51'E) and eleven birds originated from April to May in Qiqihar region, Heilongjiang Province (47°29'N, 124°02'E). We found that RMRs of little buntings were significantly higher in Qiqihar than in Wenzhou. Consistently, mitochondrial state-4 respiration capacities and cytochrome c oxidase activities (COX) in liver and muscle, and circulating levels of plasma triiodothyronine (T(3)) of little buntings were also significantly higher in Qiqihar than in Wenzhou. Variation in metabolic biochemical markers of liver and muscle, such as state-4 respiration and COX, and variation in thyroid hormone levels were correlated with variation in RMR. There was also a positive relationship between T(3) and metabolic biochemical markers. Little buntings mainly coped with a cold environment by enhancing thermogenic capacities through enhanced respiratory enzyme activities and plasma T(3). These results support the view that the primary means by which small birds meet energetic challenges of cold conditions is through metabolic adjustments.
适应不同的环境条件是小型雀形目鸟类生存的必要前提。长距离迁徙和冬季适应会在雀形目鸟类中引起类似的生理和生化调整。为了了解代谢适应，我们检查了 2008 年 3 月至 5 月期间在迁徙过程中从中国东南部（温州）和东北部（齐齐哈尔）捕获的小鸟（Emberiza pusilla）的静息代谢率（RMR）、肝脏和肌肉中线粒体的产热特性以及甲状腺激素的活性。从 3 月到 4 月，我们在浙江省温州市（27°29'N，120°51'E）的温州地区捕获了 12 只鸟，从 4 月到 5 月，我们在黑龙江省齐齐哈尔地区（47°29'N，124°02'E）捕获了 11 只鸟。我们发现，齐齐哈尔的小鸟的 RMR 明显高于温州。一致地，肝脏和肌肉中线粒体状态 4 呼吸能力和细胞色素 c 氧化酶活性（COX）以及小鸟的血浆三碘甲状腺原氨酸（T（3））循环水平也明显高于温州。肝脏和肌肉的代谢生化标志物，如状态 4 呼吸和 COX 的变化，以及甲状腺激素水平的变化与 RMR 的变化相关。T（3）与代谢生化标志物之间也存在正相关关系。小鸟主要通过增强呼吸酶活性和血浆 T（3）来增强产热能力，从而应对寒冷环境。这些结果支持了这样一种观点，即小型鸟类应对寒冷条件下的能量挑战的主要手段是通过代谢调整。
