Sharma V K, Chandrashekaran M K
Chronobiology Laboratory, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore, Karnataka, India.
Chronobiol Int. 2000 Mar;17(2):129-36. doi: 10.1081/cbi-100101037.
When organisms are maintained under constant conditions of light and temperature, their endogenous circadian rhythms free run, manifesting their intrinsic period. The phases of these free-running rhythms can be shifted by stimuli of light, temperature, and drugs. The change from one free-running steady state to another following a perturbation often involves several transient cycles (cycles of free-running rhythm drifting slowly to catch up with the postperturbation steady state). Although the investigation of oscillator kinetics in circadian rhythms of both insects and mammals has revealed that the circadian pacemaker phase shifts instantaneously, the phenomenon of transient cycles has remained an enigma. We probed the phases of the transient cycles in the locomotor activity rhythm of the field mouse Mus booduga, evoked by a single light pulse (LP), using LPs at critically timed phases. The results of our experiments indicate that the transient cycles generated during transition from one steady state to another steady state do not represent the state of the circadian pacemaker (basic oscillator) controlling the locomotor activity rhythm in Mus booduga.
当生物体在恒定的光照和温度条件下维持时，它们的内源性昼夜节律会自由运行，显示出其固有周期。这些自由运行节律的相位可因光、温度和药物刺激而发生改变。在受到扰动后，从一种自由运行的稳定状态转变到另一种状态通常涉及几个瞬态周期（自由运行节律的周期缓慢漂移以赶上扰动后的稳定状态）。尽管对昆虫和哺乳动物昼夜节律中振荡器动力学的研究表明昼夜节律起搏器的相位会瞬间改变，但瞬态周期现象仍然是一个谜。我们使用在关键时间相位的单个光脉冲（LP），探测了由其诱发的野生小家鼠（Mus booduga）运动活动节律中瞬态周期的相位。我们的实验结果表明，在从一种稳定状态转变到另一种稳定状态期间产生的瞬态周期并不代表控制野生小家鼠运动活动节律的昼夜节律起搏器（基本振荡器）的状态。
