| 1 | Thermogenic responses in Eurasian Tree Sparrow(Passer montanus)to seasonal acclimatization and temperature-photoperiod acclimation显示文摘Background:Small birds in temperate habitats must either migrate,or adjust aspects of their morphology,physiology and behavior to cope with seasonal change in temperature and photoperiod.It is,however,difficult to accurately measure how seasonal changes in temperature and photoperiod affect physiological processes such as basal metabolic rate(BMR)and metabolic activity.To address this problem,we collected data in each month of the year on body mass(Mb)and BMR,and conducted a series of experiments to determine the effect of temperature and photoperiod on Mb,BMR and physiological markers of metabolic activity,in the Eurasian Tree Sparrow(Passer montanus).Methods:In one experiment,we measured monthly change in Mb and BMR in a captive group of birds over a year.In another experiment,we examined the effects of acclimating birds to two different temperatures,10 and 30℃,and a long and a short photoperiod(16 h light:8 h dark and 8 h light:16 h dark,respectively)for 4 weeks.Results:We found that these treatments induced sparrows to adjust their Mb and metabolic rate processes.Acclimation to 30℃for 4 weeks significantly decreased sparrows’Mb,BMR,and energy intake,including both gross energy intake and digestible energy intake,compared to birds acclimated to 10℃.The dry mass of the liver,kidneys and digestive tract of birds acclimated to 30℃also significantly decreased,although their heart and skeletal muscle mass did not change significantly relative to those acclimated to 10℃.Birds acclimated to 30℃also had lower mitochondrial state-4 respiration(S4R)and cytochrome c oxidase(COX)activity in their liver and skeletal muscle,compared to those acclimated to 10℃.Birds acclimated to the long photoperiod also had lower mitochondrial S4R and COX activity in their liver,compared to those acclimated to the short photoperiod.Conclusions:These results illustrate the changes in morphology,physiology,and enzyme activity induced by seasonal change in temperature and photoperiod in a small temperate passerine.Both temperature and photoperiod probably have a strong effect on seasonal variation in metabolic heat production in small birds in temperate regions.The effect of temperature is,however,stronger than that of photoperiod. | Lin Li Jingru Ge Sangyu Zheng Lihong Hong Xini Zhang Ming Li Jinsong Liu | 2020 | Avian Research2020，11，3： | 1 |
| 2 | Antioxidant defense mechanisms and fatty acid catabolism in Red-billed Leiothrix(Leiothrix lutea)exposed to high temperatures显示文摘Extreme hot weather is occurring more frequently due to global warming,posing a significant threat to species survival.Birds in particular are more likely to overheat in hot weather because they have a higher body temperature.This study used a heat stress model to investigate the antioxidant defense mechanisms and changes in fatty acid catabolism in Red-billed Leiothrix(Leiothrix lutea)to gain an understanding of how birds adapt to high temperatures.The birds were divided into five groups:a control group(30℃for 0 days),1 D group(40℃for 1 day),3 D group(40℃for 3 days),14 D group(40℃for 14 days)and recovery group(40℃for 14 days,then 30℃for 14 days).Our results indicated that when Red-billed Leiothrix are subjected to heat stress,malondialdehyde(MDA)content in the liver significantly increased,as did the enzyme activities of catalase(CAT),glutathione-SH-peroxidase(GSH-PX)and total antioxidant capacity(T-AOC)in the liver.Furthermore,there was a significant increase in heat shock protein 70(HSP70)expression in the liver,while avian uncoupling protein(avUCP)expression in muscle was significantly reduced.Additionally,there was a significant reduction in fatty acid catabolism enzyme activity such as 3-hydroxyacyl-CoAdehydrogenase(HOAD)activity in the heart,and carnitine palmitoyl transferase 1(CPT-1)and citrate synthase(CS)activity in the heart and liver.Furthermore,fatty acid translocase(FAT/CD36)in the heart,heart-type fatty acid binding protein(H-FABP)and fatty acid binding protein(FABP-pm)in the liver and heart were also significantly decreased.These changes reverted after treatment,but not to the same level as the control group.Our results indicated that when Red-billed Leiothrix are exposed to heat stress their internal antioxidant defense system is activated to counteract the damage caused by high temperatures.However,even with high antioxidant levels,prolonged high temperature exposure still caused some degree of oxidative damage possibly requiring a longer recovery time.Additionally,Red-billed Leiothrix may be able to resist heat stress by reducing fatty acid transport and catabolism. | Ruiping Xu Canwen Yu Liyao Mao Mengchen Jiang Luyao Gao Ming Li Jinsong Liu | 2022 | Avian Research2022，13，1： | 0 |
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