内蒙古草原小毛足鼠的活动性、代谢特征和体温的似昼夜节律

小毛足鼠(Phodopus roborovskii)是分布在内蒙古草原沙地的一种小型哺乳动物,关于其生物学和生态学特征,尤其是生理学特征还知之甚少。似昼夜节律是动物行为学和生理生态学中备受关注的一个领域。在室内条件下通过体内埋置无线电传感器连续监测小毛足鼠的体温、用自动监测系统连续监测活动性和TSE LabMaster呼吸代谢测定系统连续测定了其代谢率的昼夜节律性。结果发现:小毛足鼠在夜间的平均体温是(37.27±0.39)℃,昼间的平均体温是(36.11±0.18)℃;在夜间的平均代谢率是(4.65±1.10)mLO2·g-1·h-1,昼间的平均代谢率是(3.09±0.42)mLO2·g-1·h-1;在夜间的平均活动率为(237±145)次/0.1h,昼间的平均活动率为(38±5)次/0.1h。小毛足鼠的代谢率、活动性和体温的峰值相位主要集中在夜间,属典型的夜行性动物。实验结果从行为学特性和生理学特征等新的角度支持了野外观察小毛足鼠是夜行性动物的推断。综合活动性、代谢率和体温三方面同步变化的特征,为小毛足鼠的似昼夜节律变化提供了新的机理性解释。研究也表明小毛足鼠是研究野生动物似昼夜节律变化机理的好模型。

Circadian rhythms of activity, metabolic rate and body temperature in desert hamsters (Phodopus roborovskii)

Most living beings change their behavior and physiology on a daily basis(24 h),with rhythmicity a fundamental property of living matter.Circadian rhythm is one of the important behavioral and physiological properties of wild animals.The desert hamster(Phodopus roborovskii) is a small rodent species which inhabits mainly desert and semi-arid environments in Inner Mongolia,China.Although field observations have shown that this species is mainly active at night,we know little about their biology and ecology,especially ecological physiology.In order to understand more about the behavioral and physiological adaptations of desert rodents,8 desert hamsters(4 males and 4 females,weighing 20.4 —27.5 g and aged between 11 and 13 months) were individually caged and kept under a temperature of(23±1)℃ and a photoperiod of(16L∶8D).Transmitters(ER-4000,Mini Mitter,USA) were implanted in the abdominal cavity of each hamster,and their body temperatures and activities were monitored for 24 h using a Vital View system.Their metabolic rates were also measured for 24 h using a TSE respirometry system(LabMaster,Germany).Our results showed that the average body temperature of the desert hamster is(37.27±0.39)℃ during the night and(36.11±0.18)℃ during the day.Their average metabolic rate is(4.65 ± 1.10)mLO2·g-1·h-1 and(3.09 ± 0.42) mLO2 ·g-1·h-1 during the night and day,respectively,and their average activity is(237±145) counts /0.1h during the night and(38±5) counts /0.1h during the day.Although ultradian activity rhythms were found over periods of 4,6,8,and 12 h,their amplitudes were much smaller than that of the 24h-circadian rhythm,which had a peak at(22.7±0.6) h.A similar pattern was observed for body temperature,which peaked at(23.1±0.5)h.Based on our analyses,body temperature,activity and metabolic rate all showed circadian rhythms and synchronization,with maxima during the night and minima during the day.These are typical properties of nocturnal animals,and support the idea that the desert hamster is a typical nocturnal rodent species.Behavioral observations in the field support this conclusion.Our results suggest that the desert hamster could be an ideal model for the study of the evolution and mechanisms of circadian rhythms inr wild animals.