After stimulation by chemoattractant, Dictyostelium cells exhibit a rapid response. The concentrations of several intracellular proteins rise rapidly reaching their maximum levels approximately 5-10 seconds, after which they return to prestimulus levels. This response, which is found in many other chemotaxing cells, is an example of a step disturbance rejection, a process known to biologists as perfect adaptation. Unlike other cells, however, the initial first peak observed in the chemoattractant-induced response of Dictyostelium cells is then followed by a slower, smaller phase peaking approximately one to two minutes after the stimulus. Until recently, the nature of this biphasic response has been poorly understood. Moreover, the origin for the second phase is unknown. In this paper we conjecture the existence of a feedback path between the response and stimulus. Using a mathematical model of the chemoattractant-induced response in cells, and standard tools from control engineering, we show that positive feedback may elicit this second peak.

中文翻译：

---

正反馈可能导致在网基网柄菌细胞的化学引诱剂诱导反应中观察到的双相反应

在化学引诱剂刺激后，网基网柄菌细胞表现出快速反应。几种细胞内蛋白质的浓度迅速上升，在大约 5-10 秒后达到最高水平，然后恢复到刺激前水平。这种在许多其他趋化细胞中发现的反应是阶跃干扰排斥的一个例子，生物学家称之为完美适应的过程。然而，与其他细胞不同的是，在网基网柄菌细胞的化学引诱剂诱导反应中观察到的最初的第一个峰值随后是一个较慢、较小的阶段，在刺激后大约一到两分钟达到峰值。直到最近，人们对这种双相反应的性质知之甚少。此外，第二阶段的起源是未知的。在本文中，我们推测响应和刺激之间存在反馈路径。使用细胞中化学引诱物诱导反应的数学模型和来自控制工程的标准工具，我们表明正反馈可能会引发第二个峰值。