环境温度对白头鹎代谢产热和蒸发失水的影响

基础代谢率(BMR)是恒温动物维持正常生理机能的最小产热速率,是动物在清醒时维持身体各项基本功能所需的最小能量值。"能量需求"假设认为,鸟类短期BMR的调整可以通过改变内部器官的大小来适应能量需求。以白头鹎(Pycnonotus sinensis)为研究对象,分别在10℃和30℃的不同环境中适应4周后,测定了其BMR、蒸发失水(EWL)和内部器官(心、肝、肾、胃、小肠和整体消化道)的重量,同时分析了白头鹎内部器官的变化及与BMR的关系。驯化4周后,白头鹎暖温组(30℃)的体重有明显降低的趋势;经协方差校正体重后,低温组(10℃)单位体重BMR与整体BMR明显高于暖温组,同时两组间EWL表现出显著差异。协方差分析表明,低温组白头鹎的肝脏、肾脏、小肠及总消化道重量显著高于暖温组。低温引起白头鹎能量需求增加,内部器官发生相应改变,要求摄入更多的氧气以维持代谢平衡,导致散失更多的蒸发水。     

树麻雀代谢率和器官重量在季节驯化中表型的可塑性变化

动物能量代谢的生理生态特征与物种的分布和丰富度密切相关,基础代谢率(BMR)是内温动物能量预算的重要组成部分。北温带的小型鸟类,通过增加产热来适应低温环境。增加BMR的基础之一是中心器官(代谢机器)发生明显的变化。本研究中我们测定了树麻雀(Passermontanus)的BMR、体重和各器官的重量,分析了麻雀各器官的季节性变化及与BMR的关系。方差分析表明:麻雀的BMR存在明显的季节性变化,在冬季和秋季较高。麻雀内部器官的变化同样有明显的季节性,冬季和秋季麻雀的肝脏、心脏、肌胃、小肠、直肠和整体消化道的重量,都有明显的增加。相关分析表明:麻雀的BMR与肝脏、心脏和消化道等内部器官存在明显的相关性。我们的结果验证了“中心限制假说”,即麻雀体内存在着与BMR相关的“代谢机器”,中心器官是提高麻雀BMR的基础之一。     

光周期对白头鹎（Pycnonotus sinensis）体重、器官重量和能量代谢的影响

光周期是四季环境变化的最直接表现因素之一,并影响动物的生理变化特征。为探讨光周期驯化对白头鹎(Pycnonotus sinensis)体重、器官重量及能量代谢的影响,以室温28℃、不同光周期 (16L ∶ 8D,LD组和8L ∶ 16D,SD组)对两组白头鹎进行为期4周的光周期驯化,测定其体重、各器官鲜重和干重、基础代谢率(BMR)和食物摄入能、排泄能及同化能并计算同化率。结果发现,SD组个体体重、内部器官(肝、小肠)重量、BMR及同化率相应显著高于LD组个体;短光照刺激白头鹎显著降低摄入能、排泄能及同化能。这些结果表明:光周期对白头鹎的体重、器官重量、BMR及能量收支有着一定影响,并且短光照较长光照更能引起白头鹎体重、器官重量及能量代谢的明显变化,同时验证了"中心限制假说",即白头鹎BMR与中心器官代谢(肝、小肠等)具有相关性,中心器官是改变白头鹎BMR的主要原因之一。     

光周期对白头鹎体重、器官重量和能量代谢的影响

光周期是四季环境变化的最直接表现因素之一,并影响动物的生理变化特征。为探讨光周期驯化对白头鹎(Pycnonotussinensis)体重、器官重量及能量代谢的影响,以室温28℃、不同光周期(16L∶8D,LD组和8L∶16D,SD组)对两组白头鹎进行为期4周的光周期驯化,测定其体重、各器官鲜重和干重、基础代谢率(BMR)和食物摄入能、排泄能及同化能并计算同化率。结果发现,SD组个体体重、内部器官(肝、小肠)重量、BMR及同化率相应显著高于LD组个体;短光照刺激白头鹎显著降低摄入能、排泄能及同化能。这些结果表明:光周期对白头鹎的体重、器官重量、BMR及能量收支有着一定影响,并且短光照较长光照更能引起白头鹎体重、器官重量及能量代谢的明显变化,同时验证了中心限制假说,即白头鹎BMR与中心器官代谢(肝、小肠等)具有相关性,中心器官是改变白头鹎BMR的主要原因之一。     

白头鹎肝脏和肌肉冬夏两季的代谢产热特征比较

动物能量代谢的生理生态特征与物种的分布和丰富度密切相关,基础代谢率(basal metabolic rate,BMR)是恒温动物维持正常生理机能的最小产热速率,是内温动物能量预算的重要组成部分.该文以白头鹎(Pycnonotus sinensis)为研究对象,分别在冬季和夏季测定了白头鹎的体重、BMR、肝脏和肌肉的线粒体蛋白质含量、线粒体呼吸及细胞色素C氧化酶(cytochrome c oxidase,COX)活力及血清中甲状腺素(T4)及三碘甲腺原氨酸(T3)含量的变化,从细胞和酶学水平上解释白头鹎基础产热的季节适应规律.耗氧量采用封闭式流体压力呼吸测定仪测定,肝脏和肌肉的线粒体状态4呼吸及COX活力采用铂氧电极-溶氧仪测定.结果显示:白头鹎的体重和BMR冬季显著高于夏季;肝脏和肌肉的线粒体呼吸,以及肝脏和肌肉的COX活力冬季明显高于夏季;血清T3浓度冬季较高,夏季较低.这些结果表明:在野外自然条件下,肝脏和肌肉在细胞水平产热能力的提高和血清T3含量的增加是白头鸭BMR增加的细胞学机制之一,同时是白头鹎抵御冬季寒冷的一种重要方式.     

鸟类基础产热的可塑性

基础代谢率(basal metabolic rate,BMR)是动物在清醒时维持身体各项基本功能所需的最小能量值,能反映出鸟类对环境独特的适应机制和进化对策。鸟类的BMR具有一定的可塑性,包括实验室适应、迁徙和季节性驯化期间的变化。鸟类BMR可塑性变化的形态学、生理学及生化分子生物学基础包括:调整代谢活性器官的重量、特殊器官的代谢强度及组织器官内氧含量和底物的转运能力等。     

白头鹎体温、体重及能量代谢的昼夜节律

动物的生理昼夜节律是对环境昼夜变化的一种重要适应。为探讨白头鹎(Pycnonotus sinensis)体温、体重及能量代谢的昼夜节律变化,采用数字式温度计、电子天平及封闭式流体压力呼吸仪,测定了白头鹎的日体温、日体重和昼夜基础代谢率(BMR)。结果发现:白头鹎日体温及日体重变化存在显著差异,其中夜间体温明显低于白昼,并在4:00时体温呈现最低值;而白头鹎夜间体重显著低于白昼,在4:00时达到最小值,在18:00时达到最大值。另外,白头鹎的BMR也表现出了明显的昼夜差异,夜间BMR显著低于白昼。表明白头鹎体温、体重及能量代谢存在显著的昼夜节律变化,并调节达到自身生理能量平衡,从而适应昼夜环境变化。     

黑线仓鼠体重和能量代谢的季节性变化

为阐明小型哺乳动物体重和能量代谢的季节性变化以及生理调节机制,将黑线仓鼠驯化于自然环境下12个月,测定其体重、能量收支、身体组织器官和血清瘦素水平的季节性变化。黑线仓鼠能量摄入和支出的季节性变化显著,冬季摄入能、基础代谢率(BMR)、非颤抖性产热(NST)显著高于夏季。体重季节性变化不显著,但身体组织器官重量呈现显著的季节性变化,冬季肝脏、心脏、肾脏以及消化道重量显著高于夏季。体脂含量夏季最高,冬季最低,冬季显著低于夏、秋和春季(P <0.01)。血清瘦素水平的季节性变化显著,夏季瘦素水平比秋、冬季分别高88.2% 和52.4% (P <0.05)。结果表明,黑线仓鼠体重维持季节性稳定,与“调定点假说”的预测不同;但脂肪含量和血清瘦素季节性变化显著,符合该假说。夏季血清瘦素升高具有抑制能量摄入的作用,冬季血清瘦素可能是促进代谢产热的重要因子,瘦素对能量代谢和体重的调节作用与气候的季节性变化有关。       

温度与光周期对白头鹎体质量、能量收支和消化道形态的影响

温度与光周期是环境季节性变化的最直接表现因子及时间变化指示标志,对动物的形态、生理及行为产生重要的影响.本文以白头鹎为研究对象,探讨了不同温度与光周期对其体质量、能量收支和消化道形态的影响,分析了能量收支与消化道形态特征的关系.将28只白头鹎(12雄16雌)分为4组:暖温长光组(30℃,16 L8 D;3雄4雌)、暖温短光组(30 ℃,8 L16 D;3雄4雌)、低温长光组(10 ℃,16 L8 D;3雄4雌)和低温短光组(10 ℃,8 L16 D;3雄4雌).结果表明: 低温与短光照可促进白头鹎的体质量、摄入能及同化能明显增加,同时温度与光周期的交互作用对白头鹎的摄入能及同化能影响显著.低温条件下,胃、小肠、直肠及总消化道的湿质量及干质量明显增加.残差分析表明,小肠与总消化道的长度及干质量与摄入能和同化能显著相关.表明低温与短光照下白头鹎通过增加体质量、能量摄入和改变消化道形态来应对严酷的环境条件.     

白头鹎对季节性驯化和温度适应的生理反应

在自然环境中,有机体某一特性的可塑性变化在适应和功能方面是非常重要的。以成年白头鹎(Pycnonotus sinensis)为研究对象,分别在野外驯化条件和实验室温度适应条件下测定静止代谢率(RMR)、蒸发失水率(EWL)和代谢活性器官的重量,同时测定肝脏及肌肉的线粒体呼吸和细胞色素C氧化酶活力(COX)。野外季节性驯化在冬季和夏季时测定;实验室温度适应分为2组,分别在10℃和30℃下适应4周后进行测定。结果显示,与夏季驯化和暖适应组相比,冬季驯化和冷适应组RMR和EWL较高、代谢活性器官较重,线粒体呼吸速率和COX活性显著增加;器官重量和细胞产热能力的适应性变化可能是导致了RMR适应性调节。结果表明,白头鹎可以表现出对季节性驯化和温度适应的生理反应,利用这种能力应付野外环境温度的波动。生理能量特性的可塑性是鸟类能量代谢的共同特征。     

温州地区4种雀形目鸟类基础代谢率与器官重量的相关性分析

动物代谢率存在差异的原因及其意义是进化牛理学上的一个核心问题.为了解代谢率的影响因素和功能意义,测定了红头长尾山雀Aegithalos concinnus、白头鹎Pycnonotus sinensis、丝光椋鸟Stumus sericeus和小鸦Emberi-za pusilla的基础代谢率,分析了动物体内的8种器官或者组织的大小与代谢率的关系.结果显示,基础代谢率与脑、肝脏,.肾脏、胃、小肠和总消化道干重(胃、小肠与直肠的干重之和)相关显著.     

The functional significance of individual variation in basal metabolic rate

Basal metabolic rate (BMR) was established as a common reference point allowing comparable measures across different individuals and species. BMR is often regarded as a minimal rate of metabolism compatible with basic processes necessary to sustain life. One confusing aspect, however, is that BMR is highly variable, both within and between species. A potential explanation for this variability is that while individuals with high BMRs may suffer the disadvantage of having to feed for longer to cover the extra energy demands, this may be offset by advantages that accrue because of the high metabolic rate. One suggested advantage is that high levels of BMR are a consequence of maintaining a morphology that permits high rates of the maximal sustained rate of metabolism (SusMR)--the rate of metabolism that can be sustained for days or weeks. We have been studying the energetics of MF1 laboratory mice during peak lactation to investigate this idea. In this article, we review some of our work in connection with three particular predictions that derive from the hypothesised links among morphology, basal metabolism, and sustained metabolic rate. By comparing groups of individuals, for example, lactating and nonlactating individuals, the patterns that emerge are broadly consistent with the hypothesis that BMR and SusMR are linked by morphology. Lactating mice have bigger organs connected with energy acquisition and utilisation, greater resting metabolic rates in the thermoneutral zone, called RMRt (approximately equivalent to BMR), and high sustainable rates of maximal energy intake. However, when attempts are made to establish these relationships across individuals within lactating mice, the associations that are anticipated are either absent or very weak and depend on shared variation due to body mass. At this level there is very little support for the suggestion that variation in RMRt (and thus BMR) is sustained by associations with SusMR.     

Quantitative genetics parameters show partial independent evolutionary potential for body mass and metabolism in stonechats from different populations

Phenotypic variation in physiological traits, such as energy metabolism, is commonly subjected to adaptive interpretations, but little is known about the heritable basis or genetic correlations among physiological traits in non-domesticated species. Basal metabolic rate (BMR) and body mass are related in complex ways. We studied the quantitative genetics of BMR, residual BMR (on body mass), mass-specific BMR and body mass of stonechats originating from four different populations and bred in captivity. Heritabilities ranged from 0.2 to 0.7. The genetic variance–covariance structure implied that BMR, mass-specific BMR and body mass can in part evolve independently of each other, because we found genetic correlations deviating significantly from one and minus one. BMR, mass-specific BMR and body mass further differed among populations at the phenotypic level; differences in the genetic correlation among populations are discussed.     

内蒙古草原布氏田鼠代谢率与身体器官的关系

动物代谢率存在差异的原因及其意义是进化生理学的一个核心问题。为了解代谢率的影响因素和功能意义, 我们测定了不同驯化条件下布氏田鼠(Microtus brandti) 的基础代谢率(basal metabolic rate , BMR) 、日能量消耗(daily energy expenditure , DEE) 和冷诱导的最大代谢率(maximum metabolic rate , MMR) , 分析了动物体内11 种器官、组织的重量与代谢率的关系。结果显示, 排除温度、光照、食物质量和体重的影响后, BMR 与心脏、肝脏、肾脏、胃和盲肠相关; DEE与心脏、肾脏、胃和盲肠相关; MMR 与脑重显著负相关。这表明: 在布氏田鼠体内存在着代谢活性器官, 主要包括心脏、肝脏、肾脏、胃和盲肠, 这些器官对BMR 有较大的贡献。动物的能量周转水平与体内“代谢机器” (metabolic machinery) 的大小相关连, 主要受到心脏、肾脏、胃和盲肠的影响。最大代谢率受脑重的影响。BMR 与MMR 的相关性不显著, 而BMR 与DEE 的相关性显著, 说明较高的BMR 有助于维持较高的DEE , 但不能维持较高的MMR。     

The quantitative genetics of sustained energy budget in a wild mouse

We explored how morphological and physiological traits associated with energy expenditure over long periods of cold exposure would be integrated in a potential response to natural selection in a wild mammal, Phyllotis danwini. In particular, we studied sustained energy expenditure (SusMR), the rate of expenditure fueled by concurrent energy intake, basal metabolic rate (BMR), and sustained metabolic scope (SusMS = SusMR/BMR), a measure of the reserve for sustained work. We included the masses of different central processing organs as an underlying factor that could have a mechanistic link with whole animal traits. Only the liver had heritability statistically different from zero (0.73). Physiological and morphological traits had high levels of specific environmental variance (average 70%) and postnatal common environmental variance (average 30%) which could explain the low heritabilities estimates. Our results, (1) are in accordance with previous studies in mammals that report low heritabilities for metabolic traits (SusMR, BMR, SusMS), (2) but not completely with previous ones that report high heritabilities for morphological traits (masses of central organs), and (3) provide important evidence of the relevance of postnatal common environmental variance to sustained energy expenditure.     

黑线仓鼠的BMR个体差异及其应对高脂食物的能量学对策

为探讨高脂食物对小型哺乳动物能量代谢的影响及其与基础代谢率(Basal metabolic rate, BMR)的关系,将成年雌性黑线仓鼠(Cricetulus barabensis)分为高、低BMR组,每组再随机分为低脂、高脂食物组,驯化6周后,测定体重、摄入能和代谢率,以及消化酶活力、褐色脂肪组织(Brown adipose tissue, BAT)和主要内脏器官与肌肉的细胞色素c氧化酶(Cytochrome c oxidase, COX)活性、解偶联蛋白(Uncoupling protein, UCP) mRNA表达等。结果显示,高脂食物对高、低BMR组动物体重均无显著影响。与低脂食物组相比,高脂食物组的摄食量、摄入能和消化能显著下降,小肠脂肪酶活力显著增强,消化率明显增加,但高、低BMR组的组间差异不显著。夜间代谢水平显著高于昼间,高脂食物使高BMR组的夜间代谢率显著升高。BAT、肌肉和内脏器官COX活性不受高脂食物的影响,高、低BMR组的组间差异也不显著。高脂食物组仅肝脏UCP2表达显著上调。结果表明,能量摄入和消化系统形态及功能的可塑性调节是黑线仓鼠应对高脂食物的主要策略;黑线仓鼠的代谢率具有显著的昼夜节律,既受高脂食物的影响,也与动物自身的BMR水平有关,但UCP表达具有组织特异性,这可能不是导致BMR个体差异的因素。     

The maximum metabolizable energy intake and the relationship with basal metabolic rate in the striped hamsterCricetulus barabensis

The maximum metabolizable energy intake (MEI_max) of striped hamsterCricetulus barabensis (Pallas, 1773) was determined in gradually lowering temperature. The MEI_max was gained at 0 C, 3.6 ± 0.1 kJ/(g × d) or 121.9 ± 4.9 kJ/d, which is 2.8 times the basal metabolic rate (BMR). This suggests that the actual energy budgets of striped hamsters in natural environment will keep near the upper physiological limit. As the temperature decreased, both metabolizable energy intake (MEI) and BMR increased though there was no significant correlation between the MEI and BMR or between the MEI_max and BMR. However, the significant correlation between MEI_max and BMR was found in nine species of rodents. Our results support the assimilation capacity model of the origin and evolution of endothermy at the interspecific level.     

Phenotypic flexibility in basal metabolic rate and the changing view of avian physiological diversity: a review

Comparative analyses of avian energetics often involve the implicit assumption that basal metabolic rate (BMR) is a fixed, taxon-specific trait. However, in most species that have been investigated, BMR exhibits phenotypic flexibility and can be reversibly adjusted over short time scales. Many non-migrants adjust BMR seasonally, with the winter BMR usually higher than the summer BMR. The data that are currently available do not, however, support the idea that the magnitude and direction of these adjustments varies consistently with body mass. Long-distance migrants often exhibit large intra-annual changes in BMR, reflecting the physiological adjustments associated with different stages of their migratory cycles. Phenotypic flexibility in BMR also represents an important component of short-term thermal acclimation under laboratory conditions, with captive birds increasing BMR when acclimated to low air temperatures and vice versa. The emerging view of avian BMR is of a highly flexible physiological trait that is continually adjusted in response to environmental factors such as temperature. The within-individual variation observed in avian BMR demands a critical re-examination of approaches used for comparisons across taxa. Several key questions concerning the shapes and other properties of avian BMR reaction norms urgently need to be addressed, and hypotheses concerning metabolic adaptation should explicitly account for phenotypic flexibility.     

Basal metabolic rate: history, composition, regulation, and usefulness

The concept of basal metabolic rate (BMR) was developed to compare the metabolic rate of animals and initially was important in a clinical context as a means of determining thyroid status of humans. It was also important in defining the allometric relationship between body mass and metabolic rate of mammals. The BMR of mammals varies with body mass, with the same allometric exponent as field metabolic rate and with many physiological and biochemical rates. The membrane pacemaker theory proposes that the fatty acid composition of membrane bilayers is an important determinant of a species BMR. In both mammals and birds, membrane polyunsaturation decreases and monounsaturation increases with increasing body mass and a decrease in mass-specific BMR. The secretion and production of thyroid hormones in mammals are related to body mass, with the allometric exponent similar to BMR; yet there is no body size-related variation in either total or free concentrations of thyroid hormones in plasma of mammals. It is suggested that in different-sized mammals, the secretion/production of thyroid hormones is a result of BMR differences rather than their cause. BMR is a useful concept in some situations but not in others.     

Dominant black-capped chickadees pay no maintenance energy costs for their wintering status and are not better at enduring cold than subordinate individuals

Winter requires physiological adjustments in northern resident passerines. Cold acclimatization is generally associated with an increase in physiological maintenance costs, measured as basal metabolic rate (BMR), and cold endurance, reflected by summit metabolic rate (M _sum). However, several northern species also form social groups in winter and a bird’s hierarchical position may influence the size of its metabolically active organs as well as its BMR. Winter metabolic performance in these species may therefore reflect a complex set of adjustments to both seasonal climatic variations and social environment. We studied the effect of social status on parameters of cold acclimatization (body mass, size of fat reserves and pectoral muscles, BMR and M _sum) in free-living black-capped chickadees (Poecile atricapillus). Birds that were structurally large and heavy for their body size, mostly dominant individuals, carried more fat reserves and had larger pectoral muscles. However, social status had little effect on metabolic performance in the cold. Indeed, M _sum was independent of social rank while mass-corrected BMR was slightly lower in dominant individuals, likely due to a statistical dilution effect caused by large metabolically inactive fat reserves. BMR and M _sum, whether considered in terms of whole-animal values, corrected for body mass or body size were nevertheless correlated, suggesting a functional link between these metabolic components. Our results therefore indicate that the energy cost of social dominance is not a generalized phenomenon in small wintering birds.