Goldbeter A, Segel L A
Differentiation. 1980;17(3):127-35. doi: 10.1111/j.1432-0436.1980.tb01090.x.
In the first few hours after starvation, the developing cAMP secretory system in Dictyostelium discoideum has been observed to be successively in one of four states: (a) quiescent, (b) excitable (capable of relay), (c) autonomously oscillating, and (d) secreting at a high steady level. A theoretical model is presented which demonstrates that the proximal cause of the transitions between different types of behavior may be slow changes in the activities of the enzymes adenylate cyclase and phosphodiesterase. These changes affect the stability properties of the steady state admitted by the cAMP signalling system. Sustained oscillations develop when the steady state is unstable, whereas relay of cAMP signals occurs upon perturbation of a stable steady state for parameter values close to those which produce oscillations. The developmental path suggested in the adenylate cyclase-phosphodiesterase space for the sequential transitions compares with the time course observed for the synthesis of these enzymes after starvation. It is suggested that there is general significance for the understanding of differentiation in the example given of a state-point following a developmental path in parameter space, moving from one behavioral domain to another, and thereby bringing about shifts in qualitative behavior.
在饥饿后的最初几个小时里，已观察到盘基网柄菌中正在发育的环磷酸腺苷（cAMP）分泌系统依次处于四种状态之一：（a）静止状态，（b）可兴奋状态（能够进行信号传递），（c）自主振荡状态，以及（d）以高稳定水平分泌状态。本文提出了一个理论模型，该模型表明不同类型行为之间转变的近端原因可能是腺苷酸环化酶和磷酸二酯酶活性的缓慢变化。这些变化影响了cAMP信号系统所允许的稳态的稳定性特性。当稳态不稳定时会出现持续振荡，而对于接近产生振荡的参数值，当稳定稳态受到扰动时会发生cAMP信号的传递。在腺苷酸环化酶 - 磷酸二酯酶空间中为连续转变所建议的发育路径与饥饿后这些酶合成所观察到的时间进程相比较。有人提出，在参数空间中沿着发育路径的状态点从一个行为域移动到另一个行为域，从而导致定性行为的转变，这一例子对于理解分化具有普遍意义。
