The rates at which birds use energy may have profound effects on fitness, thereby influencing physiology, behavior,ecology and evolution. Comparisons of standardized metabolic rates (e.g., lower and upper limits of me...The rates at which birds use energy may have profound effects on fitness, thereby influencing physiology, behavior,ecology and evolution. Comparisons of standardized metabolic rates (e.g., lower and upper limits of metabolic power output)present a method for elucidating the effects of ecological and evolutionary factors on the interface between physiology and lifehistory in birds. In this paper we review variation in avian metabolic rates [basal metabolic rate (BMR; minimum normothermicmetabolic rate), summit metabolic rate (M_(sum); maximal thermoregulatory metabolic rate), and maximal metabolic rate (MMR;maximal exercise metabolic rate)], the factors associated with this variation, the evidence for functional links between thesemetabolic traits, and the ecological and evolutionary significance of avian metabolic diversity. Both lower and upper limits tometabolic power production are phenotypically flexible traits, and vary in association with numerous ecological and evolutionaryfactors. For both inter- and intraspecific comparisons, lower and upper limits to metabolic power production are generallyupregulated in response to energetically demanding conditions and downregulated when energetic demands are relaxed, or underconditions of energetic scarcity. Positive correlations have been documented between BMR, M_(sum) and MMR in some, but not allstudies on birds, providing partial support for the idea of a functional link between lower and upper limits to metabolic powerproduction, but more intraspecific studies are needed to determine the robustness of this conclusion. Correlations between BMRand field metabolic rate (or daily energy expenditure) in birds are variable, suggesting that the linkage between these traits is subjectto behavioral adjustment, and studies of the relationship between field and maximal metabolic rates are lacking. Our understandingof avian metabolic diversity would benefit from future studies of: (1) the functional and mechanistic links between lowerand upper limits of metabolic power output; (2) the environmental and ecological cues driving phenotypically flexible metabolicresponses, and how responses to such cues might impact population responses to climate change; (3) the shapes of metabolic reactionnorms and their association with environmental variability; and (4) the relationship of metabolic variation to fitness, includingstudies of repeatability and heritability of minimum and maximum metabolic power展开更多
Temperature and other environmental factors play an integral role in the metabolic adjustments of animals and drive a series of morphological,physiological,and behavioral adaptions essential to survival.However,it is ...Temperature and other environmental factors play an integral role in the metabolic adjustments of animals and drive a series of morphological,physiological,and behavioral adaptions essential to survival.However,it is not clear how the capacity of an organism for temperature acclimation translates into seasonal acclimatization to maintain survival.Basal metabolic rate(BMR),evaporative water loss(EWL),and energy budget were measured in the Chinese Hwamei(Garrulax canorus)following winter and summer acclimatization,and in those acclimatized to 15℃(cold)and 35℃(warm)under laboratory conditions for 28 days.In addition to the above indicators,internal organ masses,as well as state 4 respiration and cytochrome c oxidase(COX)activity were also measured for the liver,skeletal muscle,heart,and kidney.Both winter-acclimatized and cold-acclimated birds exhibited significantly higher BMR,EWL,and energy budget,as well as organ masses,state 4 respiration,and COX activity compared with the summer-acclimatized and warm-acclimated birds.This indicated that the Chinese Hwamei could adapt to seasonal or just temperature changes through some physiological and biochemical thermogenic adjustments,which would be beneficial to cope with natural environmental changes.A general linear model showed that body mass,BMR,GEI,state 4 respiration in the liver and kidney,and COX activity in the skeletal muscle,liver,and kidney were significantly affected by temperature and acclimation.A positive correlation was observed between BMR and each of the other parameters(body mass,EWL,energy budget,heart dry mass,kidney dry mass,state 4 respiration)in the muscle,heart,and kidney and also between BMR and COX activity in the muscle and kidney.The results suggested that similar to seasonal acclimatization,Chinese Hwameis subjected to temperature acclimation also exhibited significant differences in metabolism-related physiological and biochemical parameters,depending on the temperature.The data also supported the prediction that metabolic adjustment might be the primary means by which small birds meet the energetic challenges triggered by cold conditions.展开更多
To better understand the physiological characteristics of the silky starling(Sturnus sericeus), its body temperature(Tb), basal metabolic rate(BMR), evaporative water loss(EWL) and thermal conductance(C) elicited by d...To better understand the physiological characteristics of the silky starling(Sturnus sericeus), its body temperature(Tb), basal metabolic rate(BMR), evaporative water loss(EWL) and thermal conductance(C) elicited by different ambient temperatures(Ta)(5-30 °C) were determined in the present study. Our results showed that they have a high Tb(41.6±0.1 °C), a wide thermal neutral zone(TNZ)(20-27.5 °C) and a relatively low BMR within the TNZ(3.37±0.17 mL O2/g·h). The EWL was nearly stable below the TNZ(0.91±0.07 mg H2O/g·h) but increased remarkably within and above the TNZ. The C was constant below the TNZ, with a minimum value of 0.14±0.01 mL O2/g·h·°C. These findings indicate that the BMR, Tb and EWL of the silky starling were all affected by Ta, especially when Ta was below 20 °C and the EWL plays an important role in thermal regulation.展开更多
Environmental cues play important roles in the regulation of an animal's physiology and behavior. One such cue, photoperiod, plays an important role in the seasonal acclimatization of birds. It has been demonstrated ...Environmental cues play important roles in the regulation of an animal's physiology and behavior. One such cue, photoperiod, plays an important role in the seasonal acclimatization of birds. It has been demonstrated that an animal's body mass, basal metabolic rate (BMR), and energy intake, are all affected by photoperiod. The present study was designed to examine photoperiod induced changes in the body mass, metabolism and metabolic organs of the silky starling, Stumus sericeus. Captive silky starlings increased their body mass and BMR during four weeks of acclimation to a short photoperiod. Birds acclimated to a short photopedod also increased the mass of certain organs (liver, gizzard and small intestine), and both gross energy intake (GEl) and digestible energy intake (DEI), relative to those acclimated to a long photoperiod. Furthermore, BMR was positively correlated with body mass, liver mass, GEl and DEI. These results suggest that silky starlings increase metabolic thermogenesis when exposed to a short photoperiod by increasing their body and metabolic organ mass, and their GEl and DEI. These findings support the hypothesis that bird species from temperate climates typically display high phenotypic flexibility in thermogenic capacity.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
Background:The capacity for thermogenesis is considered part of an animal's adaptive strategy for survival,and basal metabolic rate(BMR) is one of the fundamental physiological standards for assessing the energy c...Background:The capacity for thermogenesis is considered part of an animal's adaptive strategy for survival,and basal metabolic rate(BMR) is one of the fundamental physiological standards for assessing the energy cost of thermoregulation in endotherms.BMR has been shown to be a highly flexible phenotypic trait both between,and within,species,but the metabolic mechanisms involved in the regulation of BMR,which range from variation in organ mass to biochemical adjustments,remain unclear.In this study,we investigated the relationship between organ mass,biochemical markers of metabolic tissue activity,and thermogenesis,in three species of small passerines:wild Bramblings(Fringilla montifringilla),Little Buntings(Emberiza pusilla) and Eurasian Tree Sparrows(Passer montanus),caught in Wenzhou,southeastern China.Methods:Oxygen consumption was measured using an open-circuit respirometry system.Mitochondrial state-4 respiration and cytochrome c oxidase(COX) activity in liver and pectoral muscle were measured with a Clark electrode.Results:Our results show that Eurasian Tree Sparrows had significantly higher BMR,digestive organ mass,mitochondrial state-4 respiration capacity and COX activity in liver and muscle,than Bramblings and Little Buntings.Furthermore,interspecific differences in BMR were strongly correlated with those indigestive tract mass,state-4 respiration and COX activity.Conclusions:Our findings suggest that the digestive organ mass,state-4 respiration and COX activity play an important role in determining interspecific differences in BMR.展开更多
The food habits hypothesis (FHH) stands as one of the most striking and often-cited interspecific patterns to emergefrom comparative studies of endothermic energetics. The FHH identifies three components of diet that ...The food habits hypothesis (FHH) stands as one of the most striking and often-cited interspecific patterns to emergefrom comparative studies of endothermic energetics. The FHH identifies three components of diet that potentially produce variabilityin mass-independent BMR, i.e. food quality, food availability, and food predictability or environmental productivity. Thehypothesis predicts that species with diets of low energy content and/or low digestibility should evolve low mass-independentBMRs. The effects of food habits on BMR have been widely investigated at the interspecific level, but the variation between individualsand populations has been largely ignored. Our focus is to compare predictions derived from interspecific studies withdata collected from within-species studies to explore the mechanisms and functional significance of adaptive responses predictedby the food-habits hypothesis among birds. We conclude that if BMR is correlated with daily energy expenditure, then organismsthat can lower BMR will reduce daily energy expenditure and hence, food requirements. Birds that lower BMR in stressful environmentsmay increase survival. Nevertheless, the mechanism (s) by which birds eating a low quality diet reduce BMR andwhether lower BMR affects fitness remain to be展开更多
Background: Basal Metabolic Rate (BMR) is the quantum of calories needed for optimum body function when at rest. This has long been an indicator of one’s health and the basis for determining the metabolic age of indi...Background: Basal Metabolic Rate (BMR) is the quantum of calories needed for optimum body function when at rest. This has long been an indicator of one’s health and the basis for determining the metabolic age of individuals. Many scholastic projects have led to the establishment of mathematical models and inventions that measure the BMR and other body composition parameters. However, existing computations have limitations as they do not offer accurate results for Ghanaians. Aim: The purpose of the study was to model BMR metrics that are most suitable for Ghanaians and to investigate the effect of caloric difference on weight, Lean Body Mass (LBM) and % fat composition that can be implemented with Information Technology. Research Methods and Procedures: This was an experimental study that adopted a quantitative approach. BMR and body composition were measured in a sample of 242 Ghanaian adults (141 males and 101 females) from 19 to 30 years of age. Body composition was measured using bioelectrical impendence analysis (BIA) in all participants. Each participant was under study for 7 days. A simple linear regression model was used to examine associations between BMR/calorie intake and total body weight and LBM. Results: There was a significant statistical relation between BMR and LBM and between BMR and weight of both men and women. Equations for BMR and weight were established for males and females. Furthermore, caloric intake differences affected changes in total weight as well as differences in % fat composition. Caloric intake however did not affect the difference in LBM. Conclusion: Caloric difference had an impact on total body weight and Lean Body Mass. The model derived from the study predicts weight change and BMR of Ghanaians from 19 to 30 years of age. It is termed the Health and Age Monitoring System (HAMS).展开更多
Background: Acclimatization to winter conditions is an essential prerequisite for the survival of small birds in the northern temperate zone.Changes in photoperiod,ambient temperature and food availability trigger sea...Background: Acclimatization to winter conditions is an essential prerequisite for the survival of small birds in the northern temperate zone.Changes in photoperiod,ambient temperature and food availability trigger seasonal physiological and behavioral acclimatization in many passerines.Seasonal trends in metabolic parameters are well known in avian populations from temperate environments;however,the physiological and biochemical mechanisms underlying these trends are incompletely understood.In this study,we used an integrative approach to measure variation in the thermogenic properties of the male Silky Starling(Sturnus sericeus) at different levels or organization,from the whole organism to the biochemical.We measured body mass(Mb),basal metabolic rate(BMR),energy budget,the mass of selected internal organs,state 4 respiration and cytochrome c oxidase(COX) activity in the heart,liver and muscle.Methods: Oxygen consumption was measured using an open-circuit respirometry system.The energy intake of the birds were then determined using an oxygen bomb calorimeter.Mitochondrial state 4 respiration and COX activity in heart,liver and pectoral muscle were measured with a Clark electrode.Results: The results suggest that acclimatization to winter conditions caused significant change in each of the measured variables,specifically,increases in Mb,organ mass,BMR,energy intake and cellular enzyme activity.Furthermore,BMR was positively correlated with body mass,energy intake,the mass of selected internal organs,state 4 respiration in the heart,liver and muscle,and COX activity in the heart and muscle.Conclusions: These results suggest that the male Silky Starling's enhanced basal thermogenesis under winter conditions is achieved by making a suite of adjustments from the whole organism to the biochemical level,and provide further evidence to support the notion that small birds have high phenotypic plasticity with respect to seasonal changes.展开更多
The study aimed to determine the relationships between the basal metabolic rate(BMR) and body composition of overweight and obese Chinese adults with type 2 diabetes mellitus(DM). This cross-sectional clinical stu...The study aimed to determine the relationships between the basal metabolic rate(BMR) and body composition of overweight and obese Chinese adults with type 2 diabetes mellitus(DM). This cross-sectional clinical study enrolled 193 Chinese adults with type 2 DM who were overweight(24 kg/m2≤BMI〈28 kg/m2, n=99), or obese(BMI ≥28 kg/m2, n=94). Ninety-seven adults with normal BMIs, including 50 DM patients and 47 healthy adults, were recruited as a control group. BMR was measured by indirect calorimetry; predicted BMR was calculated according to the Schofield equation; and the relationships between BMR, body composition, and biochemical results were determined by the Pearson correlation. The results showed that obese DM patients had significantly higher BMRs than both overweight patients(P〈0.05) and patients with normal BMI did(P〈0.05). The measured BMR was significantly lower than the predicted BMR(P〈0.05) in all groups. Obese and overweight DM patients had significantly greater weight, waist circumference, hip circumference, BMI, body surface area, body fat percentage, fat mass, and fat-free mass than patients with normal BMI. Except for waist circumference, these body composition measurements were significantly increased in obese DM patients when compared with those in overweight DM patients(P〈0.05). Fat-free mass was closely correlated with BMR in both DM patients(r=0.874, P〈0.01) and in healthy controls(r=0.902, P〈0.01). It was concluded that overweight and obese Chinese adults with type 2 DM had increased BMRs compared with normal-weight controls, which may result from the difference in fat-free mass.展开更多
Background: Food is an important environmental factor that affects animals' energy metabolism and food shortage has significant effects on animals' behavior, physiology and biochemistry. However, to date few s...Background: Food is an important environmental factor that affects animals' energy metabolism and food shortage has significant effects on animals' behavior, physiology and biochemistry. However, to date few studies have focused on the thermogenesis and its effects on the body condition of birds. In this study, we examined the effects of food restriction on the body mass, basal metabolic rate(BMR) and body composition, and several physiological, biochemical and molecular markers potentially related to thermogenesis, in the Chinese Bulbul(Pycnonotus sinensis).Methods: Birds in the control group were provided with food ad libitum whereas those in the food restriction group were provided with one-half of the usual quantity of food for 12 days. Oxygen consumption was measured using an open-circuit respirometry system. Mitochondrial state 4 respiration and cytochrome c oxidase(COX) activity in the liver and pectoral muscle were measured with a Clark electrode. Avian uncoupling protein(avUCP) mRNA expression was determined in pectorals muscle with quantitative Real-time PCR.Results:Chinese Bulbuls in food restriction group decreased in body mass,BMR and internal organ(heart,kidneys,small intestine and total digestive tract)mass compared with the control group over the 12-day period of food restriction.Bulbuls in the food restriction group also had lower levels of state-4 respiration,COX activity in the liver and muscle,and mitochondrial avUCP gene expression in muscle compared to the control group.BMR was positively correlated with body mass,state 4 respiration in the liver and COX activity in the muscle.Conclusions:Our data indicate that Chinese Bulbuls not only sustain food shortage through simple passive mechanisms,such as reducing body and organ mass and energy expenditure,but also by reducing energetic metabolism in the liver and muscle.展开更多
文摘The rates at which birds use energy may have profound effects on fitness, thereby influencing physiology, behavior,ecology and evolution. Comparisons of standardized metabolic rates (e.g., lower and upper limits of metabolic power output)present a method for elucidating the effects of ecological and evolutionary factors on the interface between physiology and lifehistory in birds. In this paper we review variation in avian metabolic rates [basal metabolic rate (BMR; minimum normothermicmetabolic rate), summit metabolic rate (M_(sum); maximal thermoregulatory metabolic rate), and maximal metabolic rate (MMR;maximal exercise metabolic rate)], the factors associated with this variation, the evidence for functional links between thesemetabolic traits, and the ecological and evolutionary significance of avian metabolic diversity. Both lower and upper limits tometabolic power production are phenotypically flexible traits, and vary in association with numerous ecological and evolutionaryfactors. For both inter- and intraspecific comparisons, lower and upper limits to metabolic power production are generallyupregulated in response to energetically demanding conditions and downregulated when energetic demands are relaxed, or underconditions of energetic scarcity. Positive correlations have been documented between BMR, M_(sum) and MMR in some, but not allstudies on birds, providing partial support for the idea of a functional link between lower and upper limits to metabolic powerproduction, but more intraspecific studies are needed to determine the robustness of this conclusion. Correlations between BMRand field metabolic rate (or daily energy expenditure) in birds are variable, suggesting that the linkage between these traits is subjectto behavioral adjustment, and studies of the relationship between field and maximal metabolic rates are lacking. Our understandingof avian metabolic diversity would benefit from future studies of: (1) the functional and mechanistic links between lowerand upper limits of metabolic power output; (2) the environmental and ecological cues driving phenotypically flexible metabolicresponses, and how responses to such cues might impact population responses to climate change; (3) the shapes of metabolic reactionnorms and their association with environmental variability; and (4) the relationship of metabolic variation to fitness, includingstudies of repeatability and heritability of minimum and maximum metabolic power
基金financially supported by grants from the National Natural Science Foundation of China(No.31971420 and No.32171497)。
文摘Temperature and other environmental factors play an integral role in the metabolic adjustments of animals and drive a series of morphological,physiological,and behavioral adaptions essential to survival.However,it is not clear how the capacity of an organism for temperature acclimation translates into seasonal acclimatization to maintain survival.Basal metabolic rate(BMR),evaporative water loss(EWL),and energy budget were measured in the Chinese Hwamei(Garrulax canorus)following winter and summer acclimatization,and in those acclimatized to 15℃(cold)and 35℃(warm)under laboratory conditions for 28 days.In addition to the above indicators,internal organ masses,as well as state 4 respiration and cytochrome c oxidase(COX)activity were also measured for the liver,skeletal muscle,heart,and kidney.Both winter-acclimatized and cold-acclimated birds exhibited significantly higher BMR,EWL,and energy budget,as well as organ masses,state 4 respiration,and COX activity compared with the summer-acclimatized and warm-acclimated birds.This indicated that the Chinese Hwamei could adapt to seasonal or just temperature changes through some physiological and biochemical thermogenic adjustments,which would be beneficial to cope with natural environmental changes.A general linear model showed that body mass,BMR,GEI,state 4 respiration in the liver and kidney,and COX activity in the skeletal muscle,liver,and kidney were significantly affected by temperature and acclimation.A positive correlation was observed between BMR and each of the other parameters(body mass,EWL,energy budget,heart dry mass,kidney dry mass,state 4 respiration)in the muscle,heart,and kidney and also between BMR and COX activity in the muscle and kidney.The results suggested that similar to seasonal acclimatization,Chinese Hwameis subjected to temperature acclimation also exhibited significant differences in metabolism-related physiological and biochemical parameters,depending on the temperature.The data also supported the prediction that metabolic adjustment might be the primary means by which small birds meet the energetic challenges triggered by cold conditions.
基金This study was financially supported the National Natural Science Foundation of China (31070366), the Natural Science Foundation (LY13C030005) in Zhejiang Province and the Zhejiang Province 'Xinmiao' Project.
文摘To better understand the physiological characteristics of the silky starling(Sturnus sericeus), its body temperature(Tb), basal metabolic rate(BMR), evaporative water loss(EWL) and thermal conductance(C) elicited by different ambient temperatures(Ta)(5-30 °C) were determined in the present study. Our results showed that they have a high Tb(41.6±0.1 °C), a wide thermal neutral zone(TNZ)(20-27.5 °C) and a relatively low BMR within the TNZ(3.37±0.17 mL O2/g·h). The EWL was nearly stable below the TNZ(0.91±0.07 mg H2O/g·h) but increased remarkably within and above the TNZ. The C was constant below the TNZ, with a minimum value of 0.14±0.01 mL O2/g·h·°C. These findings indicate that the BMR, Tb and EWL of the silky starling were all affected by Ta, especially when Ta was below 20 °C and the EWL plays an important role in thermal regulation.
基金supported by grants from the National Natural Science Foundation of China(31470472)the National Undergraduate"Innovation"Project and Zhejiang Province"Xinmiao"Project
文摘Environmental cues play important roles in the regulation of an animal's physiology and behavior. One such cue, photoperiod, plays an important role in the seasonal acclimatization of birds. It has been demonstrated that an animal's body mass, basal metabolic rate (BMR), and energy intake, are all affected by photoperiod. The present study was designed to examine photoperiod induced changes in the body mass, metabolism and metabolic organs of the silky starling, Stumus sericeus. Captive silky starlings increased their body mass and BMR during four weeks of acclimation to a short photoperiod. Birds acclimated to a short photopedod also increased the mass of certain organs (liver, gizzard and small intestine), and both gross energy intake (GEl) and digestible energy intake (DEI), relative to those acclimated to a long photoperiod. Furthermore, BMR was positively correlated with body mass, liver mass, GEl and DEI. These results suggest that silky starlings increase metabolic thermogenesis when exposed to a short photoperiod by increasing their body and metabolic organ mass, and their GEl and DEI. These findings support the hypothesis that bird species from temperate climates typically display high phenotypic flexibility in thermogenic capacity.
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financially supported by Grants from the National Natural Science Foundation of China (No. 31470472)the National Undergraduate "Innovation" Project and Zhejiang Province’s "Xinmiao" Project
文摘Background:The capacity for thermogenesis is considered part of an animal's adaptive strategy for survival,and basal metabolic rate(BMR) is one of the fundamental physiological standards for assessing the energy cost of thermoregulation in endotherms.BMR has been shown to be a highly flexible phenotypic trait both between,and within,species,but the metabolic mechanisms involved in the regulation of BMR,which range from variation in organ mass to biochemical adjustments,remain unclear.In this study,we investigated the relationship between organ mass,biochemical markers of metabolic tissue activity,and thermogenesis,in three species of small passerines:wild Bramblings(Fringilla montifringilla),Little Buntings(Emberiza pusilla) and Eurasian Tree Sparrows(Passer montanus),caught in Wenzhou,southeastern China.Methods:Oxygen consumption was measured using an open-circuit respirometry system.Mitochondrial state-4 respiration and cytochrome c oxidase(COX) activity in liver and pectoral muscle were measured with a Clark electrode.Results:Our results show that Eurasian Tree Sparrows had significantly higher BMR,digestive organ mass,mitochondrial state-4 respiration capacity and COX activity in liver and muscle,than Bramblings and Little Buntings.Furthermore,interspecific differences in BMR were strongly correlated with those indigestive tract mass,state-4 respiration and COX activity.Conclusions:Our findings suggest that the digestive organ mass,state-4 respiration and COX activity play an important role in determining interspecific differences in BMR.
文摘The food habits hypothesis (FHH) stands as one of the most striking and often-cited interspecific patterns to emergefrom comparative studies of endothermic energetics. The FHH identifies three components of diet that potentially produce variabilityin mass-independent BMR, i.e. food quality, food availability, and food predictability or environmental productivity. Thehypothesis predicts that species with diets of low energy content and/or low digestibility should evolve low mass-independentBMRs. The effects of food habits on BMR have been widely investigated at the interspecific level, but the variation between individualsand populations has been largely ignored. Our focus is to compare predictions derived from interspecific studies withdata collected from within-species studies to explore the mechanisms and functional significance of adaptive responses predictedby the food-habits hypothesis among birds. We conclude that if BMR is correlated with daily energy expenditure, then organismsthat can lower BMR will reduce daily energy expenditure and hence, food requirements. Birds that lower BMR in stressful environmentsmay increase survival. Nevertheless, the mechanism (s) by which birds eating a low quality diet reduce BMR andwhether lower BMR affects fitness remain to be
文摘Background: Basal Metabolic Rate (BMR) is the quantum of calories needed for optimum body function when at rest. This has long been an indicator of one’s health and the basis for determining the metabolic age of individuals. Many scholastic projects have led to the establishment of mathematical models and inventions that measure the BMR and other body composition parameters. However, existing computations have limitations as they do not offer accurate results for Ghanaians. Aim: The purpose of the study was to model BMR metrics that are most suitable for Ghanaians and to investigate the effect of caloric difference on weight, Lean Body Mass (LBM) and % fat composition that can be implemented with Information Technology. Research Methods and Procedures: This was an experimental study that adopted a quantitative approach. BMR and body composition were measured in a sample of 242 Ghanaian adults (141 males and 101 females) from 19 to 30 years of age. Body composition was measured using bioelectrical impendence analysis (BIA) in all participants. Each participant was under study for 7 days. A simple linear regression model was used to examine associations between BMR/calorie intake and total body weight and LBM. Results: There was a significant statistical relation between BMR and LBM and between BMR and weight of both men and women. Equations for BMR and weight were established for males and females. Furthermore, caloric intake differences affected changes in total weight as well as differences in % fat composition. Caloric intake however did not affect the difference in LBM. Conclusion: Caloric difference had an impact on total body weight and Lean Body Mass. The model derived from the study predicts weight change and BMR of Ghanaians from 19 to 30 years of age. It is termed the Health and Age Monitoring System (HAMS).
基金financially supported by grants from the National Natural Science Foundation of China(No.31470472)the National Undergraduate Innovation and Entrepreneurship Training Program and the Zhejiang Province“Xinmiao”Project
文摘Background: Acclimatization to winter conditions is an essential prerequisite for the survival of small birds in the northern temperate zone.Changes in photoperiod,ambient temperature and food availability trigger seasonal physiological and behavioral acclimatization in many passerines.Seasonal trends in metabolic parameters are well known in avian populations from temperate environments;however,the physiological and biochemical mechanisms underlying these trends are incompletely understood.In this study,we used an integrative approach to measure variation in the thermogenic properties of the male Silky Starling(Sturnus sericeus) at different levels or organization,from the whole organism to the biochemical.We measured body mass(Mb),basal metabolic rate(BMR),energy budget,the mass of selected internal organs,state 4 respiration and cytochrome c oxidase(COX) activity in the heart,liver and muscle.Methods: Oxygen consumption was measured using an open-circuit respirometry system.The energy intake of the birds were then determined using an oxygen bomb calorimeter.Mitochondrial state 4 respiration and COX activity in heart,liver and pectoral muscle were measured with a Clark electrode.Results: The results suggest that acclimatization to winter conditions caused significant change in each of the measured variables,specifically,increases in Mb,organ mass,BMR,energy intake and cellular enzyme activity.Furthermore,BMR was positively correlated with body mass,energy intake,the mass of selected internal organs,state 4 respiration in the heart,liver and muscle,and COX activity in the heart and muscle.Conclusions: These results suggest that the male Silky Starling's enhanced basal thermogenesis under winter conditions is achieved by making a suite of adjustments from the whole organism to the biochemical level,and provide further evidence to support the notion that small birds have high phenotypic plasticity with respect to seasonal changes.
基金supported by the National Natural Science Foundation of China(No.81370942)
文摘The study aimed to determine the relationships between the basal metabolic rate(BMR) and body composition of overweight and obese Chinese adults with type 2 diabetes mellitus(DM). This cross-sectional clinical study enrolled 193 Chinese adults with type 2 DM who were overweight(24 kg/m2≤BMI〈28 kg/m2, n=99), or obese(BMI ≥28 kg/m2, n=94). Ninety-seven adults with normal BMIs, including 50 DM patients and 47 healthy adults, were recruited as a control group. BMR was measured by indirect calorimetry; predicted BMR was calculated according to the Schofield equation; and the relationships between BMR, body composition, and biochemical results were determined by the Pearson correlation. The results showed that obese DM patients had significantly higher BMRs than both overweight patients(P〈0.05) and patients with normal BMI did(P〈0.05). The measured BMR was significantly lower than the predicted BMR(P〈0.05) in all groups. Obese and overweight DM patients had significantly greater weight, waist circumference, hip circumference, BMI, body surface area, body fat percentage, fat mass, and fat-free mass than patients with normal BMI. Except for waist circumference, these body composition measurements were significantly increased in obese DM patients when compared with those in overweight DM patients(P〈0.05). Fat-free mass was closely correlated with BMR in both DM patients(r=0.874, P〈0.01) and in healthy controls(r=0.902, P〈0.01). It was concluded that overweight and obese Chinese adults with type 2 DM had increased BMRs compared with normal-weight controls, which may result from the difference in fat-free mass.
基金financially supported by grants from the National Natural Science Foundation of China(No.31470472)the National Undergraduate “Innovation” Projectthe Zhejiang Province ‘Xinmiao’ Project
文摘Background: Food is an important environmental factor that affects animals' energy metabolism and food shortage has significant effects on animals' behavior, physiology and biochemistry. However, to date few studies have focused on the thermogenesis and its effects on the body condition of birds. In this study, we examined the effects of food restriction on the body mass, basal metabolic rate(BMR) and body composition, and several physiological, biochemical and molecular markers potentially related to thermogenesis, in the Chinese Bulbul(Pycnonotus sinensis).Methods: Birds in the control group were provided with food ad libitum whereas those in the food restriction group were provided with one-half of the usual quantity of food for 12 days. Oxygen consumption was measured using an open-circuit respirometry system. Mitochondrial state 4 respiration and cytochrome c oxidase(COX) activity in the liver and pectoral muscle were measured with a Clark electrode. Avian uncoupling protein(avUCP) mRNA expression was determined in pectorals muscle with quantitative Real-time PCR.Results:Chinese Bulbuls in food restriction group decreased in body mass,BMR and internal organ(heart,kidneys,small intestine and total digestive tract)mass compared with the control group over the 12-day period of food restriction.Bulbuls in the food restriction group also had lower levels of state-4 respiration,COX activity in the liver and muscle,and mitochondrial avUCP gene expression in muscle compared to the control group.BMR was positively correlated with body mass,state 4 respiration in the liver and COX activity in the muscle.Conclusions:Our data indicate that Chinese Bulbuls not only sustain food shortage through simple passive mechanisms,such as reducing body and organ mass and energy expenditure,but also by reducing energetic metabolism in the liver and muscle.