Varnum-Finney B, Schroeder N A, Soll D R
Department of Biology, University of Iowa, Iowa City 52242.
Cell Motil Cytoskeleton. 1988;9(1):9-16. doi: 10.1002/cm.970090103.
When developing amebae of Dictyostelium discoideum are treated with constant concentrations of cAMP above 10(-8)M, the average rate of motility is depressed, with maximum inhibition at roughly 10(-6)M. It is demonstrated that shifting the concentration of cAMP from 0 M to concentrations ranging from 10(-8) to 10(-6)M in a perfusion chamber results in the immediate inhibition of motility. After shifting from 0 M to 10(-8) or 10(-7)M, the rate of cell motility remains low, then rebounds to a higher level, exhibiting a standard adaptation response. No adaptation is exhibited after a shift from 0 M to 10(-6)M, a concentration resulting in maximum inhibition. It is demonstrated that the level of inhibition and the extent of the adaptation period are dependent upon the concentration of cAMP after the shift, and that submaximal inhibition is additive. The characteristics of adaptation in this motility response are very similar to the characteristics of adaptation for the relay system and phosphorylation of the putative cAMP receptor.
当用浓度恒定且高于10⁻⁸M的环磷酸腺苷（cAMP）处理盘基网柄菌的发育中的变形虫时，其平均运动速率会降低，在大约10⁻⁶M时抑制作用达到最大。研究表明，在灌注室中将cAMP的浓度从0M转变为10⁻⁸至10⁻⁶M范围内的浓度时，运动会立即受到抑制。从0M转变为10⁻⁸或10⁻⁷M后，细胞运动速率保持较低水平，然后反弹至较高水平，呈现出标准的适应性反应。从0M转变为10⁻⁶M（导致最大抑制的浓度）后则不表现出适应性。研究表明，抑制水平和适应期的长短取决于转变后cAMP的浓度，且亚最大抑制是可叠加的。这种运动反应中的适应性特征与中继系统以及假定的cAMP受体磷酸化的适应性特征非常相似。
