CIRCADIAN TIMING
CIRCADIAN TIMING
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DOI：
10.1111/j.1749-6632.1984.tb23452.x
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发表时间：
1984-01-01
影响因子：
5.2
通讯作者：
ASCHOFF, J
中科院分区：
文献类型：
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作者：
ASCHOFF, J
对于任何生命系统，时间的两个方面可以区分：在有机体内部，多种相互作用的过程必须在时间上（如在空间上）协调，并且还需要外部时间上的调整，以适应其他有机体和环境中不断变化的条件。在许多方面，内部和外部计时意味着时间的测量，例如，通过解码中枢神经系统内的脉冲频率。为了达到这样的目的，可以设想各种机制，这些机制不一定代表永久运行的时钟。然而，有四种这样的时钟原型，它们是为了适应环境中的四个主要周期而进化的：潮汐、昼夜、月亮周期和季节。这些环境周期中的每一个都代表了一个时间程序，它以规则的间隔重复自己，因此是可预测的。通过将这样一个程序的副本纳入其组织，生物体能够调整其活动以适应周期性变化的条件，并在随后的任务之前做好准备，即通过生物钟测量外部时间。这四种生物钟的特征类似于自持振荡。它们在恒定的条件下持续存在，其频率与它们模仿的环境周期略有偏离。这通过用于指定昼夜节律、昼夜节律、月周节律和年周节律的前缀“circa”来表示。作为一种有用的时间测量设备，一个时钟必须与它的环境周期同步运行。这是通过从环境中的周期性因素（Zeitgebers）中夹带信号来实现的。
For any living system, two aspects of timing can be distinguished: Within the organism, a multiplicity of interacting processes has to be coordinated in time (as in space), and externally temporal adjustment of the organism’s behavior to that of other organisms and to changing conditions in the environment is also needed. In many ways, internal as well as external timing implies the measurement of time, for example, by the decoding of impulse frequencies within the central nervous system. To serve such purposes, various mechanisms can be imagined that do not necessarily represent permanently running clocks. There are, however, four prototypes of such clocks that have evolved in adaptation to the four main periodicities in the environment: the tides, day and night, the lunar cycle, and the seasons. Each of these environmental cycles represents a temporal program that repeats itself in regular intervals and is hence predictable. By incorporating into its organization a copy of such a program, an organism is enabled to adjust its activities to the periodically changing conditions, and to be prepared in advance of ensuing tasks, that is, to measure external time by means of a biological clock.’The characteristics of the four biological clocks resemble those of self-sustaining oscillations.’They persist in constant conditions with a frequency that slightly deviates from those of the environmental cycles that they mimic. This is indicated by the prefix “circa” used to designate circatidal, circadian, circalunar, and circannual clocks. To be useful as a time-measuring device, a circa-clock must run in synchrony with its environmental cycle. This is achieved through entraining signals from periodic factors in the environment, the zeitgebers.’