丝光椋鸟的代谢产热特征及体温调节的日周期变化

为探讨丝光椋鸟(Sturnus sericeuts)代谢产热特征及体温调节的日周期变化,本研究采用开放式氧气分析仪及数字式温度计,测定了丝光椋鸟24 h体温、体重(Mb)和基础代谢率(BMR)的连续变化.结果显示,丝光椋鸟体温、体重及代谢率的日周期变化存在显著差异.丝光椋鸟夜间体温明显低于白昼,其中体温在凌晨5时降至(40.4±0.1)℃;体重昼夜变化明显,且在20:00～次日6:00时雌雄丝光椋鸟体重的下降与时间分别存在明显的线性关系,雌性为Mb=83.46(±0.12)-0.41(±0.02)t(R2=0.992,P＜0.01);雄性为Mb =76.74(±0.15)-0.39(±0.02)t(R2=0.986,P＜0.01)(式中的t代表时间).丝光椋鸟的BMR在凌晨4时降至最低,为(1.96±0.06) ml/(g·h).结果表明,丝光椋鸟通过内源性的调节,即夜间降低体温、体重及代谢率等途径,调节生理能量平衡,从而适应昼夜环境变化.     

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。     

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。     

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。     

白头鹎的代谢率与器官重量在季节驯化中的可塑性变化

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,是内温动物能量预算的重要组成部分.本研究测定了白头鹎(Pycnonotus sinensis)的BMR、内部器官(肝、心、肌胃、小肠、肾和整体消化道)和肌肉的重量,分析了白头鹎内部器官和肌肉重量的季节性变化及与BMR的关系.方差分析表明,白头鹎的BMR存在明显的季节性变化,冬季较高,夏季最低.其内部器官及肌肉重量的变化同样有明显的季节性.相关分析表明,白头鹎的BMR与肝、心、消化道等内部器官和肌肉重量存在明显的相关性.     

温度对红尾沙蜥代谢昼夜节律的影响

爬行动物很多生理、生化和行为指标都表现出昼夜节律。代谢昼夜节律不仅涉及内在因子的固有控制,而且受到多种外部因素的影响。为了探究温度对代谢昼夜节律的影响,在恒定的温度下(18℃和28℃)测定了红尾沙蜥Phrynocephalus erythrurus体温、心率、标准代谢率(SMR)和血糖浓度的昼夜变化。结果表明:(1)在2个温度下红尾沙蜥体温没有明显的昼夜变化;(2)昼间SMR明显高于夜间,18℃下SMR水平以及SMR昼夜变化的范围都低于28℃下的结果;(3)心率的变化也与代谢率的变化一致,但最低点提前了2 h;(4)28℃下的血糖浓度整体水平显著高于18℃下的,而波动规律却不同:28℃条件下白天平均值高于晚上,血糖浓度在16∶00显著高于20∶00、00∶00和12∶00;18℃条件下,血糖浓度在20∶00和08∶00明显低于00∶00和12∶00(P0.05),而在04∶00和16∶00处于中间水平。该研究证实了红尾沙蜥SMR、心率和血糖浓度等生理生化指标也存在明显的昼夜节律,虽然这种现象受环境温度的影响,但主要还是由内在因子决定,这可能与某些激素的分泌活动有关。     

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.     

大熊猫尿中肾上腺皮质激素的近日节律初探

本文用放射免疫法测定了三头火熊猫尿中皮质醇水平的昼夜变化。尿中皮质醇水平在凌晨1时后升高,黎明达最高值,下午列夜间零时一般在日平均水平下波动,19:00—23:00之内出现最低值,表现出明显的昼夜节律性变化。     

应用植入式遥测技术观察自发性高血压大鼠血压的昼夜波动

目的应用植入式遥测技术观察自发性高血压大鼠在清醒无束缚状态下血压昼夜波动变化。方法取8只SPF级3月龄雄性SHR大鼠,进行C50-PXT植入子植入手术,恢复7 d后,用遥测系统进行24 h连续清醒无束缚的血压监测,并用EMKA分析软件对动态血压心率均值、24 h血压心率趋势等指标进行分析。结果 3月龄的SHR大鼠血压和心律呈昼夜节律性变化,白昼阶段血压明显低于夜间阶段(P<0.01),血压在1∶30～2∶30和20∶30～21∶30时出现两个高峰期,14∶00～14∶30时出现一低谷期。其中夜间阶段平均收缩压为166.02 mmHg,两个收缩压峰值分别为172.13 mmHg和171.38 mmHg;白昼平均收缩压是162.73 mmHg,收缩压谷底值为155.73mmHg。而心率两个高峰期出现在1∶30～2∶00和20∶00～21∶00,高峰值分别为375.00次/分和373.26次/分;心率低谷出现在11∶00左右,谷底值为310.91次/分,白昼和夜间的平均心率分别为328.85次/分和346.05次/分。结论 3月龄的SHR大鼠血压和心律呈昼夜节律性变化,血压和心率在夜间出现两个高峰,白昼出现一个低谷,且夜间的平均血压和心率要高于白昼,SHR大鼠的血压和心率的节律变化与其活动有关。植入式遥测技术可准确反映SHR大鼠血压昼夜的节律性变化,有助于正确评价抗高血压药物的作用和高血压的生理机制研究。     

食物限制对高山姬鼠能量代谢和内脏器官形态的影响

为探讨栖息于横断山区高山姬鼠对食物匮乏的适应策略,在实验室条件下,以每日能量需求为标准,测定了饲喂食量为130%每日能量需求(DER)和70%DER两组高山姬鼠的体重、体温、基础代谢率(BMR)、非颤抖性产热(NST)等的变化,并在限食28d后,测定了肝脏鲜重和消化道形态的变化。结果显示:限食组高山姬鼠的体温、体重、BMR、NST显著降低,比0d分别下降了4.4%、23.6%、38.6%、20.3%。肝脏鲜重显著下降,小肠长度和小肠含内容物重显著增加。在限食条件下,高山姬鼠主要通过降低体重、体温、减少肝脏重量和能量代谢水平及消化器官适应性变化来减少能量支出,以适应食物资源短缺的外部环境。     

Anthropometric measures, body composition, body fat distribution, and knee osteoarthritis in women

Objective: Increased BMI is a well‐recognized risk factor for radiographic knee osteoarthritis (rKOA); however, the contributions of the components of body composition, body fat distribution, and height to this association are not clear. Research Methods and Procedures: We examined 779 women ≥45 years of age from the Johnston County Osteoarthritis Project. Body composition was assessed using DXA, and rKOA was defined as Kellgren‐Lawrence grade ≥2. Logistic regression models examined the association between rKOA and the fourth compared with the first quartiles of anthropometric, body composition, and fat distribution measures adjusting for age, ethnicity, and prior knee injury. Results: The adjusted odds ratios and 95% confidence interval of BMI and weight were 5.27 (3.05, 9.13) and 5.28 (3.05, 9.16), respectively. In separate models, higher odds of rKOA were also found for fat mass [4.54 (2.68, 7.69)], percent fat mass [3.84 (2.26, 6.54)], lean mass [3.94 (2.22, 6.97)], and waist circumference [4.15 (2.45, 7.02)]. Waist‐to‐hip ratio was not associated with rKOA [1.45 (0.86, 2.43)], and percent lean mass was associated with lower odds [0.20 (0.11, 0.35)]. Taller women had higher odds of rKOA after adjustment for BMI [1.77 (1.05, 3.00)]. Discussion: This study confirms that BMI and weight are strongly associated with rKOA in women and suggests that precise measurements of body composition and measures of fat distribution may offer no advantage over the more simple measures of BMI or weight in assessment of risk of rKOA.     

How does environmental variation influence body mass,body size,and body condition? Roe deer as a case study

We tested the influence of population density and of drought intensity (measured as the Gaussen Index in spring and summer of the year of birth) on winter body mass, hind foot length, and body condition of roe deer fawns. Body mass decreased with increasing density and increased with increasing Gaussen Index in summer, in a similar way for both males and females. Hind foot length of males showed the same response. On the other hand, hind foot length of females decreased with increasing density only after dry summers, hence when environmental conditions were very harsh. Body condition was affected neither by density nor by drought intensity. Our results indicate that body mass and size are much better indicators of phenotypic quality than body condition in roe deer. The sex-specific responses of body size to environmental conditions could correspond to a differential allocation in favour of daughters by heavier than average roe deer mothers.     

The influence of genetic and environmental factors in estimations of current body size, desired body size, and body dissatisfaction.

The objective was to investigate the genetic epidemiology of figural stimuli. Standard figural stimuli were available from 5,325 complete twin pairs: 1,751 (32.9%) were monozygotic females, 1,068 (20.1%) were dizygotic females, 752 (14.1%) were monozygotic males, 495 (9.3%) were dizygotic males, and 1,259 (23.6%) were dizygotic male-female pairs. Univariate twin analyses were used to examine the influences on the individual variation in current body size and ideal body size. These data were analysed separately for men and women in each of five age groups. A factorial analysis of variance, with polychoric correlations between twin pairs as the dependent variable, and age, sex, zygosity, and the three interaction terms (age x sex, age x zygosity, sex x zygosity) as independent variables, was used to examine trends across the whole data set. Results showed genetic influences had the largest impact on the individual variation in current body size measures, whereas non-shared environmental influences were associated with the majority of individual variation in ideal body size. There was a significant main effect of zygosity (heritability) in predicting polychoric correlations for current body size and body dissatisfaction. There was a significant main effect of gender and zygosity in predicting ideal body size, with a gender x zygosity interaction. In common with BMI, heritability is important in influencing the estimation of current body size. Selection of desired body size for both men and women is more strongly influenced by environmental factors.     

Ethnicity, body mass, and genome-wide data

This article combines social and genetic epidemiology to examine the influence of self-reported ethnicity on body mass index (BMI) among a sample of adolescents and young adults. We use genetic information from more than 5,000 single nucleotide polymorphisms in combination with principal components analysis to characterize population ancestry of individuals in this study. We show that non-Hispanic white and Mexican-American respondents differ significantly with respect to BMI and differ on the first principal component from the genetic data. This first component is positively associated with BMI and accounts for roughly 3% of the genetic variance in our sample. However, after controlling for this genetic measure, the observed ethnic differences in BMI remain large and statistically significant. This study demonstrates a parsimonious method to adjust for genetic differences among individual respondents that may contribute to observed differences in outcomes. In this case, adjusting for genetic background has no bearing on the influence of self-identified ethnicity.