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Zheng W.-H.,Wenzhou University | Zheng W.-H.,Zhejiang Provincial Key Laboratory for Subtropical Water Environment | Liu J.-S.,Wenzhou University | Liu J.-S.,Zhejiang Provincial Key Laboratory for Subtropical Water Environment | Swanson D.L.,University of South Dakota
Physiological and Biochemical Zoology | Year: 2014

Survival of small birds in fluctuating environments is facilitated by seasonal metabolic and morphological flexibility. Chinese bulbuls Pycnonotus sinensis show winter increases in resting metabolic rate (RMR), nutritional organ masses, and liver and muscle cellular aerobic capacity relative to summer. In this study, we build on these findings from previous studies by measuring seasonal adjustments in body mass (Mb), RMR, nutritional and exercise organ masses, and several physiological, biochemical, and hormonal markers over the entire annual cycle in wild-trapped Chinese bulbuls from Wenzhou, China. Furthermore, we analyzed the relationships between variation in organ masses and cellular aerobic capacity and variation in RMR in individual birds. Mb and RMR were higher in spring (March-May) and winter (December-February) than in summer (June-August). The dry masses of several nutritional organs and mitochondrial protein content, state 4 respiration, and cytochrome c oxidase (COX) activity in liver and muscle were all heightened in winter relative to other seasons. In addition, dry masses of heart and pectoral muscle, but not nutritional organs, and biochemical markers of cellular aerobic capacity in liver and muscle were positively correlated with RMR. Plasma triiodothyronine (T3) concentration was higher in winter and spring than in summer and autumn, and it was positively correlated with RMR, mitochondrial protein content, state 4 respiration, and COX activity in liver and muscle. These results suggest that seasonal changes in nutritional and exercise organ masses and liver and muscle cellular aerobic capacity interact to promote seasonal metabolic flexibility in Chinese bulbuls. T3 appears to promote these seasonal thermoregulatory adjustments. © 2014 by The University of Chicago. Source

Zheng W.-H.,Wenzhou University | Zheng W.-H.,Zhejiang Provincial Key Laboratory for Subtropical Water Environment | Lin L.,Wenzhou University | Liu J.-S.,Wenzhou University | And 3 more authors.
Comparative Biochemistry and Physiology - A Molecular and Integrative Physiology | Year: 2013

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 (T3) 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 T3 and metabolic biochemical markers. Little buntings mainly coped with a cold environment by enhancing thermogenic capacities through enhanced respiratory enzyme activities and plasma T3. These results support the view that the primary means by which small birds meet energetic challenges of cold conditions is through metabolic adjustments. © 2012 Elsevier Inc. Source

Xia S.,Wenzhou University | Yu A.,Wenzhou University | Zhao L.,Wenzhou University | Zhang H.,Wenzhou University | And 4 more authors.
Journal of Thermal Biology | Year: 2013

Basal metabolic rate (BMR) is thought to be a major hub in the network of physiological mechanisms connecting life history traits. Evaporative water loss (EWL) is a physiological indicator that is widely used to measure water relations in inter- or intraspecific studies of birds in different environments. In this study, we examined the physiological responses of summer-acclimatized Hwamei Garrulax canorus to temperature by measuring their body temperature (Tb), metabolic rate (MR) and EWL at ambient temperatures (Ta) between 5 and 40°C. Overall, we found that mean body temperature was 42.4°C and average minimum thermal conductance (C) was 0.15ml O2 g-1h-1°C-1 measured between 5 and 20°C. The thermal neutral zone (TNZ) was 31.8-35.3°C and BMR was 181.83ml O2 h-1. Below the lower critical temperature, MR increased linearly with decreasing Ta according to the relationship: MR (ml O2 h-1)=266.59-2.66 Ta. At Tas above the upper critical temperature, MR increased with Ta according to the relationship: MR (ml O2 h-1)=-271.26+12.85 Ta. EWL increased with Ta according to the relationship: EWL (mg H2O h-1)=-19.16+12.64 Ta and exceeded metabolic water production at Ta>14.0°C. The high Tb and thermal conductance, low BMR, narrow TNZ, and high evaporative water production/metabolic water production (EWP/MWP) ratio in the Hwamei are consistent with the idea that this species is adapted to warm, mesic climates, where metabolic thermogenesis and water conservation are not strong selective pressures. © 2013 . Source

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