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 acc...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.展开更多
Background:The thermoregulatory ability of animals is strongly influenced by the temperature of their environment.Acclimation to cold requires a range of physiological and morphological adjustments.In this study,we te...Background:The thermoregulatory ability of animals is strongly influenced by the temperature of their environment.Acclimation to cold requires a range of physiological and morphological adjustments.In this study,we tested the hypothesis that a small passerine,the Red-billed Leiothrix(Leiothrix lutea),can maintain homeothermy in cold conditions by adjusting the physiology and biochemistry of its tissue and organs and return to its former physiological and biochemical state when moved to a warm temperature.Methods:Phenotypic variation in thermogenic activity of the Red-billed Leiothrixs(Leiothrix lutea)was investigated under warm(35℃),normal(25℃)or cold(15℃)ambient temperature conditions.Oxygen consumption was measured using an open-circuit respirometry system.Mitochondrial state-4 respiration and cytochrome-c oxidase(COX)activity in liver,kidney heart and pectoral muscle were measured with a Clark electrode.Results:Birds acclimated to an ambient temperature of 15℃ for 4 weeks significantly increased their basal metabolic rate(BMR)compared to a control group kept at 25℃.Birds acclimated to 35℃ decreased their BMR,gross energy intake(GEI)and digestible energy intake(DEI).Furthermore,birds acclimated to 15℃ increased state-4 respiration in their pectoral muscles and cytochrome-c oxidase(COX)activity in their liver and pectoral muscle,compared to the 25℃ control group.Birds acclimated to 35℃ also displayed lower state-4 respiration and COX activity in the liver,heart and pectoral muscles,compared to those kept at 25℃.There was a positive correlation between BMR and state-4 respiration,and between BMR and COX activity,in all of the above organs except the liver and heart.Conclusions:Our study illustrates that the morphological,physiological,and enzymatic changes are associated with temperature acclimation in the Red-billed Leiothrix,and supports the notion that the primary means by which small birds meet the energetic challenges of cold conditions is through metabolic adjustments.展开更多
基金This study was financially supported by grants from the National Natural Science Foundation of China(No.31470472 and 31971420).
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.
基金supported by grants from the National Natural Science Foundation of China(Grant Nos.31470472 and 31971420)the National Undergraduate “Innovation” Projectthe “Xinmiao” Project in Zhejiang Province
文摘Background:The thermoregulatory ability of animals is strongly influenced by the temperature of their environment.Acclimation to cold requires a range of physiological and morphological adjustments.In this study,we tested the hypothesis that a small passerine,the Red-billed Leiothrix(Leiothrix lutea),can maintain homeothermy in cold conditions by adjusting the physiology and biochemistry of its tissue and organs and return to its former physiological and biochemical state when moved to a warm temperature.Methods:Phenotypic variation in thermogenic activity of the Red-billed Leiothrixs(Leiothrix lutea)was investigated under warm(35℃),normal(25℃)or cold(15℃)ambient temperature conditions.Oxygen consumption was measured using an open-circuit respirometry system.Mitochondrial state-4 respiration and cytochrome-c oxidase(COX)activity in liver,kidney heart and pectoral muscle were measured with a Clark electrode.Results:Birds acclimated to an ambient temperature of 15℃ for 4 weeks significantly increased their basal metabolic rate(BMR)compared to a control group kept at 25℃.Birds acclimated to 35℃ decreased their BMR,gross energy intake(GEI)and digestible energy intake(DEI).Furthermore,birds acclimated to 15℃ increased state-4 respiration in their pectoral muscles and cytochrome-c oxidase(COX)activity in their liver and pectoral muscle,compared to the 25℃ control group.Birds acclimated to 35℃ also displayed lower state-4 respiration and COX activity in the liver,heart and pectoral muscles,compared to those kept at 25℃.There was a positive correlation between BMR and state-4 respiration,and between BMR and COX activity,in all of the above organs except the liver and heart.Conclusions:Our study illustrates that the morphological,physiological,and enzymatic changes are associated with temperature acclimation in the Red-billed Leiothrix,and supports the notion that the primary means by which small birds meet the energetic challenges of cold conditions is through metabolic adjustments.
基金funded by the National Science and Technology Basic Resources Survey Project(SQ2019FY101602)the National Natural Science Foundation of China(31660195).
